Beryllium Copper Finger Strips,EMI Products,EMI shielding material

2008-10-09T17:23:00.000-07:00

We can supply BeCu finger strip gasket
Here are brief introduction of our company:
our company is a high-tech enterprise majoring in the research and development of soft electromagnetic shielding materials.Mainly products are shielding gasket,shielding fabrics,shielding foam ,shielding tapes,etc.
Finger gasket is made of complete metal material and has the lowest electric resistance for EMI shielding.
The raw material, beryllium copper has great stability itself.
Finger gasket is produced by own special manufacturing method.
All kinds of size and shapes are available.

Samjiefu@gmail.com

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

BeCu EMI Gaskets

2008-10-09T17:22:00.000-07:00

BeCu EMI Gaskets do two things very well:

Their mechanical spring characteristics far surpass all other gaskets in the industry.
They offer the highest EMI shielding effectiveness.

CGC has been designing and manufacturing BeCu EMI Gaskets since the early days of the computer and electronics industries. WE combine these years of manufacturing and EMI experience with one key ingredient -- the needs of the customer.

Our innovative EMI Gasket designs are a direct result of out experience and customer input. Our new CompactPCI line of EMI Gaskets is an example of a design that was driven by the needs of a customer and evolved into a line of gaskets that meet all the requirements for CompactPCI faceplate standards while providing superior mechanical and shielding performance.

CGC offers many standard off-the-shelf EMI Gaskets as well as the engineering and custom manufacturing experience to help you solve your application. Whether you need one prototype or a large quantity order, our Team at CGCis available to respond to your needs.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Beryllium Copper Finger Stock

2008-10-09T17:19:00.000-07:00

GENERAL INFORMATION East Coast Shielding offers the most complete line of standard EMI shielding strips in the industry. These RoHS compliant shielding strips are designed for a wide variety of application requirements. They are available in strips ranging from 16 to 24 inches in length, in continuous coils up to 35 feet long, as single fingers, or cut to requested full-fingerlengths. Uncompressed heights of standard finger stock range from .03" to .44", which will occupy gaps as low as .01". Many gaskets are offered in two material thicknesses to meet diverse application compression requirements: "Standard" and "TF", which requires less force to compress the gasket to its operating range.

BERYLLIUM COPPER EMI SHIELDING PRODUCTS

• Finger Stock
• "D" Connector Gaskets
• Contact Rings

STAINLESS STEEL EMI SHIELDING PRODUCTS

• Finger Stock
• "D" Connector Gaskets
• Expansion Slot

EMI Shielding Performance
Material	H-Field - 100kHz	E-Field - 10MHz	P-Field - 1GHz
BeCu	>110 dB	>110 dB	<110>
Note: Plating the mating surfaces with the same material will provide superior performance. Chromate chemical film on aluminum maintains surface conductivity by reducing corrosion.

ELECTROMAGNETIC COMPATIBILITY
EMI/RFI Shielding Products are designed to either keep out or keep in electromagnetic interference. Shielding reflects and absorbs incident radiation. The higher the attenuation of the shielding, the more effective it is at keeping in or out the undesired electromagnetic interference.

AVAILABLE FINISHES

FINISH	RoHS COMPLIANT
Solderable	No
Clean and Bright	Yes
Gold	Yes
Silver	Yes
Cadmium/Clear Chromate	No
Tin Lead	No
Bright Tin	Yes
Nickel	Yes
Zinc/Clear Chromate	Yes
Electroless Nickel	Yes

RFI-EMI beryllium copper shielding gaskets

2008-10-09T17:15:00.000-07:00

	Copper alloy shielding gaskets are the standard to which all other gasket materials are compared. In particular, beryllium copper base metals offer a combination of the greatest electrical conductivity, highest resistance to stress relaxation and the resultant attenuation properties in excess of 110 dB up to 1 GHz. In addition, they provide an opportunity to electroplate the surface for a most exacting galvanic compatibility when situations require. FerriShield’s two surface finishes, bright copper and tin plated, are standard for all parts – providing compatibility through the entire cathodic-anodic electrochemical potential scale for the common electronic enclosure base metals and finishes. Our standard selection of parts accommodates a wide range of gap sizes from .004” to .500” (0,10 to 12,7 mm) in easy mounting adhesive and clip-on styles.



	HIGH DEFLECTION D-SHAPE WITH ADHESIVE MOUNT. Ideal for enclosure cabinet doors, or where great variations in mounting surfaces occur. Functional in a wide variety of applications, this series combines high dynamic range, very low compression force and long service life after repeated compressions. Installs easily with standard Very High Bond adhesive by peeling away the protective paper liner.



	HIGH DEFLECTION D-SHAPE, FOLD-OVER WITH ADHESIVE MOUNT. A variation of the series shown above, these designs incorporate a “fold-over” extension on the base which protects the upper part of the contact in the relaxed position and as it slides into the compressed position. Very useful in high traffic areas. Installs easily with standard Very High Bond adhesive by peeling away the protective paper liner.



	HIGH DEFLECTION NO-SNAG, FOLD-UNDER WITH ADHESIVE MOUNT. For applications requiring low compression force. Designed with a minimum residual stress and highly leveraged spring action. The free end features a fold-under lip which facilitates a low coefficient of friction on most surfaces. Allows a minimum of compressive force to move through the deflection range, resulting in the highest levels of shielding effectiveness with a minimum force. Extremely high endurance life. Installs easily with standard Very High Bond adhesive.


	All dimensions in inches millimeters ±1.6%, or ±0.005" 0,13 mm minimum

Beryllium Copper Finger Strips

2008-10-09T17:12:00.000-07:00

Finger strip gasket or (spring) finger contact strip are usually manufactured from beryllium copper foil. Gasket profiles are resilient / compliant and can provide very low contact resistance between mating faces providing excellent EMI shielding performance. Profiles are available that are capable of coping with comparatively large variations in seam (gap) width. Very low closure force sections fabricated from light gauge foil are available.

One key benefit of finger strip is that ‘D’ or curved profiles may be used in applications where there is a wiping or shear action on the gasket e.g. sliding door.

Various plated finishes are available (e.g. tin, zinc, nickel) that can improve electrical contact properties, corrosion resistance, or improve wear characteristics.

Most sections are based around a ‘D’ profile. There are multiple variants in terms of size (profile height), design features, and mounting methods. Most commonly these include, self adhesive, clip on, rivet mount, slot mount or solder in place.

Design considerations/features

Finger strip sections are generally only suitable for indoor or controlled environments unless used inboard of suitable environmental protection.

As most sections are rivet mount or ‘clip on’ they lend themselves to efficient assembly on most sheet metalwork enclosures

They offer potentially very high shielding performance particularly if used in knife edge / channel configuration

Ideally suited for application where covers, doors etc are repeatedly opened and closed, particularly if there is a shearing or wiping action applied. This effect is useful as it ensures that contact faces are maintained in a clean condition

Sections exhibit excellent recovery – very low compression set

Be careful not to mount finger some strip sections in locations where it might be vulnerable to damage. For example, surface mounted fingers can be ‘snagged’ by clothing in doorways or access hatches

Applications

Typically used on 19” rack assemblies, communications cabinets, high performance screened enclosures

Single fingers or strip sections can be used for grounding or connection points

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Faster installation for shielding gasket strip

2008-07-22T06:05:00.001-07:00

Shielding specialist, TBA Electro Conductive Products now offers a beryllium copper (BeCu) gasket strip for narrow gap applications featuring new "Quick-Release" tape backing for faster installation

Shielding specialist, TBA Electro Conductive Products (ECP) now offers a beryllium copper (BeCu) gasket strip for narrow gap applications featuring new "Quick-Release" tape backing for faster installation Offering up to 100dB attenuation, ECP 630 Quick Release is a low profile gasket with just 1.52mm profile height making it ideal for use in the increasing number of applications where narrow gaps from 0.5mm require closing

The durable BeCu gasket features 360 "no-snag" fingers and is smooth to the touch making it suitable for bi-directional applications.

The gaskets also offer low closure forces from 8 to 30kg/m for 25 to 50% compression respectively and feature a leading edge that hooks over the module frame for full protection.

Installation is simplicity itself.

The leading edge of the gasket is hooked over the mounting flange and the opposing side is then attached by removing the backing sheet from the double sided pressure sensitive transfer tape which secures the gasket in position.

Material thickness is 0.05mm as standard and fingers are 2.54mm wide and 7.1mm long on 3.18mm pitch.

Strips are available up to 406mm long.

TBA's ECP 630 Quick Release gaskets are complemented by the company's extensive range of EMI shielding finger strip products.

These include clip-on, stick-on, snap-on and special mounting styles, each available with various plating options from clean and bright through gold and silver to zinc/clear chromate and electroless nickel.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

EMI shielding gaskets resist rough use

2008-07-22T06:03:00.000-07:00

A new option for the ECP 400 series of soft gaskets protects against tears in the conductive fabric coating.

A new option for the ECP 400 series of soft gaskets protects against tears in the conductive fabric coating The new ECP 400 Ripstop series features a specially enhanced conductive fabric that is designed to prevent fabric tears making it ideal for use in applications where doors, panels and apertures are subjected to frequent opening and closing

ECP 400 Ripstop series soft EMI shielding gaskets comprise a conductive fabric bonded over a soft nonwicking polyurethane closed cell foam.

The gaskets are ideal for shielding applications where high performance levels over a wide frequency range are required and particularly where low closure forces combine with a requirement for good environmental sealing.

All gaskets feature a self-adhesive strip to aid location and mounting.

A wide range of standard profiles is available cropped to any length up to 2m encompassing rectangular, flat, square, D-shaped, V-section, clip-on D-shaped, knife-edge, P-shaped, U-shaped, L- or J-shaped, keyhole and circular.

In addition to standard shapes, TBA ECP can provide custom designs with virtually no limitation to the design of the gasket profile and incorporating full or partial wrap of the conductive fabric.

Tailor made die cut shapes in widths up to 150mm can be produced.

Various finishes are available including nickel/copper (Ni/Cu) plated as standard and gold plated for higher attenuation.

Typical specifications for polyurethane foam include UL94V0 flammability rating and 6% maximum compression set.

The conductive fabric is woven polyester (nonwoven option available) and surface resistivity is 0.05ohm/square.

Offering excellent abrasion resistance, overall shielding effectiveness is 68 to 88dB from 30MHz to 1GHz with a temperature limit of 200C.

TBA's ECP 400 Ripstop soft gaskets extend the company's comprehensive line of EMI shielding products that also includes knitted wire mesh gaskets, woven wire sheet, metal foil tapes, oriented wire in silicone rubber, moulded and extruded conducting elastomers, printable EMI shielding elastomers, EMI shielding windows, honeycomb vents, shielded fan vents and quiet vents.

The company also offers an extensive line of beryllium copper and stainless-steel fingerstock for all EMI shielding applications.

Beryllium copper fingerstrip catalogue on the net

2008-07-22T06:02:00.000-07:00

EMI shielding specialist TBA Electro Conductive Products has announced that its latest beryllium copper fingerstrip catalogue is now available on-line at the company's website

EMI shielding specialist, TBA Electro Conductive Products (ECP) has announced that its latest beryllium copper fingerstrip catalogue is now available on-line at the company's website, www.tbaecp.co.uk The on-line catalogue is divided into sections and can be downloaded in the popular Adobe pdf format for viewing and printing off-line Catalogue sections cover material specification and general information, D-subminiature connector gaskets, pressure sensitive mounting, low-profile and hook-on gaskets, snap-on mounting, clip-on mounting, special mounting and contact rings

A further downloadable file includes the entire catalogue.

Over the next few weeks, further TBA ECP catalogues will be added to the site including static control products and polymers and coatings.

During 2001, the entire TBA ECP web site will be upgraded and will include all catalogues viewable on-line as well as downloadable.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

Faster installation for shielding gasket strip

2008-07-22T06:01:00.000-07:00

Shielding specialist, TBA Electro Conductive Products now offers a beryllium copper (BeCu) gasket strip for narrow gap applications featuring new "Quick-Release" tape backing for faster installation

The durable BeCu gasket features 360 "no-snag" fingers and is smooth to the touch making it suitable for bi-directional applications.

The gaskets also offer low closure forces from 8 to 30kg/m for 25 to 50% compression respectively and feature a leading edge that hooks over the module frame for full protection.

Installation is simplicity itself.

Material thickness is 0.05mm as standard and fingers are 2.54mm wide and 7.1mm long on 3.18mm pitch.

Strips are available up to 406mm long.

TBA's ECP 630 Quick Release gaskets are complemented by the company's extensive range of EMI shielding finger strip products.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

sall Beryllium Copper Finger Strips

2007-09-11T03:54:00.000-07:00

We work in many materials – beryllium copper, phosphor bronze, spring steel and stainless steel, brass, precious metals and others, in gauges from 0.1 mm to 2 mm (0.004” – 0.080”).

Right from the outset Capital Springs and Pressings have specialised in the manufacture of strip springs. We produce an extensive range of components for every need – from delicate precious metal components to large springs used in heavy industry.

Precision components are made specifically to our customers’specifications. We can offer technical assistance in the design and refinement or your spring requirements based on our engineers’experience as well as on the latest computer-aided design technology

In our Tool Room we design and manufacture any specialist tools required for the manufacture of your components.

We product countless variations of pressings, from basic stamped washers or shims to precision blanked and formed components. We manufacture parts, ready for assembly, from almost any type of material.

For the production of precision components, drawings or samples are required and, where necessary, samples can be submitted in order that the exact form and dimensions of a component can be determined in practical tests prior to production.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

World's fifth beryllium smeltery built in NW. China

2007-08-27T20:51:00.000-07:00

The earthwork of a beryllium smeltery, believed to be the fifth of its kind in the world, has been completed in Fuyun County in northern Xinjiang Uygur Autonomous Region, northwest China.

Workers are busy installing and testing equipment at the 50-million-yuan (6-million-US dollars) smeltery and operation is scheduled to begin in November. The annual production of the plant is designed at 100 tons of beryllium oxide and 800 tons of beryllium-copper alloy.

Beryllium, also known as metallic glass, is a deoxidizer and additive applicable for producing many kinds of alloys. It is widely used in the fields of electronics, power, petroleum and chemistry. The beryllium reserve in Fuyun County makes up 70 percent of the total reserve in China. Some 31,300 tons of beryllium ore has been exploited in one mine alone. – Xinhua

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

China's second beryllium refinery begins operation

2007-08-27T20:50:00.000-07:00

China's second beryllium refinery, which is also the world's fifth such refinery, was put into production in Fuyun County in northwest Xinjiang Uygur Autonomous Region earlier this month.

Involving a total investment of 50 million yuan (US$6 million), the new refinery is designed to produce 100 tons of industrial beryllium oxide and 1,000 tons of beryllium-copper mother alloy a year.

The refinery has been constructed by the Fuyun Hengsheng Beryllium Industry Co., Ltd., a joint venture launched by Xinjiang Nonferrous Metals Industry Group, Xinjiang Henghe Investment Co., Ltd. and Xinjiang Nonferrous Metals Industry Group Nonferrous Metals Co.

Fuyun County possesses more than 70 per cent of China's verified beryllium ore reserves.

So far, 3.13 million tons of beryllium ores have been mined from its Keketuohai No.3 mine.

Beryllium, nicknamed metallic glass, is a kind of deoxidant and additive for various alloys.

It is widely applicable to electronic, power, petroleum and chemical industries

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Exploring the world of rare earth metals

2007-08-27T20:48:00.000-07:00

More common metals such as gold, silver, iron, zinc, lead and copper are well-documented in financial pages such as this, and for good reason. But let’s focus for a moment or so on the lesser-known rare earth metals, those materials with many applications in our daily lives, investing in whose makers can boost the portfolios of those with an eye for value.

Molybdenum is a transition metal that does not react with oxygen or water at room temperature. The ability of molybdenum to withstand extreme temperatures without significantly expanding or softening make it useful in applications that involve intense heat, such as aircraft parts, electrical contacts, industrial motors, and filaments.

One company hard at finding and developing molybdenum is British Columbia-based United Bolero Development Corp., which trades on the TSX Venture under the symbol UNB. Besides its mining enterprises, United had also been busy in the oil patch, but scaled back those activities by the end of 2005, to focus almost exclusively on being a junior mineral exploration company.

UNB currently has options to purchase 100% interests in two properties in southwestern Montana. One of them, the Bald Butte property, has 22 patented claims comprising about 350 acres. Mining there began in June of this year. The deposit at Bald Butte shows an inferred resource of 105 million tons at a high grade of molybdenum.

Another property, elsewhere in the state, has been subject to previous explorations by other companies that have proven rich in molybdenite property.

The burgeoning market for molybdenum should be good news for those looking to snap up potentially strong stocks at low prices. UNB fortunes tailed off a bit from its 52-week peak over the 90-cent Canadian mark during May. At the beginning of August, the stock sat around 60 cents. While out of its 20-cent gully from this time last year, UNB is still very affordable.

Rare earth metals such as lithium are in higher demand, due to the exploding market for hybrid cars. Neodynium is also enjoying a surge for its place in the hybrid car market. Lithium ion is a key component in rechargeable batteries while neodymium is used to make the super magnets integral to hybrid and electric car technology.

All this is good news for such rare earth metal producers as Toronto-based Avalon Ventures Ltd.. Avalon, whose shares trade on the TSX Venture under the symbol AVL, focuses on metals in increasing demand in high technology and environment-friendly applications, including lithium and neodymium, as well as calcium feldspar and beryllium, the latter of which can be used in copper alloys found in electronic products.

Avalon owns five rare metals and mineral projects in Canada, three of them in advanced development. Its Separation Rapids project in northwestern Ontario is hard at work producing lithium, while the Warren Township property, in northeastern Ontario, specializes in calcium feldspar. Its Thor Lake beryllium project, in the Northwest Territories, is home to a high-grade beryllium silicate mineral.

AVL enjoyed a leap in net revenues in fiscal year 2006 to $87,588 Canadian from $414 the year before. Total assets experienced a 50%-plus hike to $6.9 million. AVL stock prices have achieved a five-year peak of $2.21 Canadian in July, after plumbing to a 52-week low of 70 cents Canadian last fall.

Tungsten, though not widely known, is prized for a hardness ranking behind only diamonds, world-leading heat resistance density (greater than lead or uranium) and environmentally-friendly qualities; it neither breaks down nor decomposes.

Tungsten is found in sporting goods (most notably golf clubs and sports fishing weights), jet turbine engines, light bulb filaments and high-speed cutting tools.

Vancouver-based North American Tungsten Corporation Ltd., trading on the TSX Venture under the symbol NTC , is a Tier One junior resource company engaging in mining, developing and acquiring tungsten and other mineral-related properties in Canada. Its 100%-owned Cantung mine and Mactung development project in the Northwest and Yukon Territories make it one of the few tungsten producers with a strategic asset in the western world.

Production in recent months has taken off for NTC, jumping 20% from March to April of this year to a record 30,000 metric tonnes of tungsten concentrate. Unaudited sales figures came in for the first three quarters of fiscal 2007 at nearly $40 million U.S., compared to $45.1 million for all of fiscal 2006.

North American Tungsten reported $51.4 million in revenues at the end of fiscal 2006, a quantum leap from the $158,000 the previous year. NTC stock traded in early August in the $1.35 Canadian range, creating a new 52-week peak, and a far cry from 50-cent Canadian ditch in which it found itself last November.

Simply put, the bargains are out there. Companies like the ones just mentioned are avidly seeking to bring these metals to the surface and make them part of our lives.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

RFI shielding enclosures and their closure seals

2007-08-27T17:51:00.000-07:00

An enclosure is shielded from electromagnetic radiation, especially for testing electronic equipment such as cellular telephones. An electrically conductive housing with a rectangular chamber has open top with a flange extending upward from its perimeter. An electrically conductive closure hinged to the housing has a peripheral groove holding a conductive spring finger assembly. When closed, the flange fits into the spring finger assembly, forcing the fingers apart and against the walls of the groove. This provides excellent conductive connection between the housing and the closure through the flange, the fingers, and the groove. The conductive spring finger assembly is machined from thin beryllium copper strip, formed to final shape into straight portions and corner portions with small radii and then heat treated to retain its final spring form. Claims

What is claimed is:

1. A sealing strip assembly for RFI shielding of an openable closure for an opening in a housing, in which there is a groove having opposed side walls in either one of the closure or the housing and a flange in the other of the closure or the housing, the strip assembly comprising:

a) four substantially straight portions;

b) four corner portions, each corner portion having a radius;

c) each portion having a continuous base with opposed long sides;

d) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

e) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends;

f) the free ends being arranged to elastically engage the side walls of the groove and then to wipe the side walls as the flange is inserted between the fingers; and

g) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final straight and corner forms.

2. The strip assembly according to claim 1, in which each of the portions are fabricated separately, and inserted into the groove to closely approximate one another to thereby form a substantially continuous endless shielding strip at the periphery of the closure.

3. The strip assembly according to claim 1, in which a plurality of the portions are formed together, and inserted into the groove to closely approximate one another to thereby form a substantially continuous endless shielding strip at the periphery of the closure.

4. The strip assembly according to claim 1, in which the material of construction is beryllium copper.

5. The strip assembly according to claim 4, in which the material is plated with nickel.

6. A radio frequency shielded enclosure comprising;

a) An electrically conductive housing having a substantially rectangular shape with corners having radii, the housing enclosing a large chamber with an opening;

b) a flange coextensive with the housing and extending away therefrom at the periphery of the opening, the flange having a first thickness;

c) a closure openably connected to the housing configured for closing off the opening;

d) a groove in the closure having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

e) a sealing strip assembly comprising:

A) four substantially straight portions;

B) four corner portions, each corner portion having a radius;

C) each portion having a continuous base with opposed long sides;

D) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

E) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange; and

F) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final straight and corner forms;

f) the strip assembly being received into the groove to thereby form a substantially continuous endless shielding strip at the periphery of the closure, and

g) the flange arranged to pass freely between the free ends of the fingers and to force the fingers apart and against the groove walls when passing the bends, thereby creating electrical contact between the flange, the fingers and the opposed walls of the groove when the closure is closed.

7. The enclosure according to claim 6, in which the sealing strip assembly is constructed of eight individual portions that are fabricated separately and inserted into the groove in close proximity to one another.

8. The enclosure according to claim 6, in which a plurality of the portions are formed together and then inserted into the groove in close proximity to one another.

9. The enclosure according to claim 6, in which the material of construction of the sealing strip assembly is beryllium copper.

10. The enclosure according to claim 9, in which the beryllium copper is plated with nickel.

11. The enclosure according to claim 6, further comprising a projection at each of the opposed walls of the groove at the open end thereof that engage the free ends of the fingers to prevent the strip assembly from leaving the groove as the flange is removed from the strip assembly.

12. The enclosure according to claim 11, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

13. The enclosure according to claim 6, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

14. A radio frequency shielded enclosure comprising:

a) an electrically conductive housing having a particular shape, the housing enclosing a large chamber with an opening;

b) a closure configured for closing off the opening;

c) a flange having a first thickness, the flange being coextensive with either one of the housing or the closure and extending away therefrom at the periphery of the opening;

d) a groove in the other of the closure or the housing, the groove having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

e) a sealing strip assembly comprising:

A) a plurality of portions;

B) each portion having a continuous base with opposed long sides;

C) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

D) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange; and

E) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final forms required to form a substantially continuous shielding strip at the periphery of the opening;

f) the strip assembly being received into the groove to thereby form a substantially continuous endless shielding strip at the periphery of the closure, and

h) the flange arranged to pass freely between the free ends of the fingers and to force the fingers apart and against the groove walls when passing the bends, thereby creating electrical contact between the flange, the fingers and the opposed walls of the groove when the closure is closed.

15. The enclosure according to claim 14, in which the free ends are arranged to elastically engage the opposed side walls of the groove and to then wipe the opposed side walls of the groove as the flange is inserted.

16. The enclosure according to claim 15, further comprising a projection at each of the opposed walls of the groove at the open end thereof that engage the free ends of the fingers to prevent the strip assembly from leaving the groove as the flange is removed from the strip assembly.

17. A sealing strip assembly for an RFI shielded enclosure, the enclosure having:

an electrically conductive housing, the housing enclosing a large chamber with an opening;

a closure configured for closing off the opening;

a flange having a first thickness, the flange being coextensive with either one of the housing or the closure and extending away therefrom at the periphery of the opening; and

a groove in the other of the closure or the housing, the groove having opposed side walls and an opening for receiving therein the flange when the closure closes the opening;

the sealing strip assembly comprising:

A) a plurality of portions;

B) each portion having a continuous base with opposed long sides;

C) a plurality of closely spaced apart fingers extending away from each of the long sides and terminating in a free end, such that the fingers on one long side oppose the fingers on the other long side;

D) the fingers on each side having a bend at a point intermediate the free end and the base, the bend directed toward the opposing fingers, such that the space between the opposed fingers at that point is less than the space between the opposed fingers at the free ends, and slightly less than the first thickness of the flange;

E) the free ends being constructed to elastically engage the opposed side walls of the groove when inserted therein, and to then wipe the opposed walls of the groove as the flange is inserted for enhanced electrical contact; and

F) the portions being constructed of a thin, electrically conductive material treated after forming to be springy and retain the final forms required to form a substantially continuous shielding strip at the periphery of the opening.

Description

BACKGROUND OF THE INVENTION

This invention relates to enclosures that are shielded from electromagnetic radiation and more particularly to such enclosures and doors that are provided with seals that achieve effective radio frequency shielding by simply closing the door.

DESCRIPTION OF THE PRIOR ART

It is common practice to place apparatus that emits electromagnetic radiation (EMR), or which is sensitive to radio frequency interference (RFI) within a shielded enclosure. When the enclosure must be frequently opened, the means for ensuring that the shielding will be restored when the opening is once again closed present problems. It is well known to provide the access door or panel with a forwardly directed blade along its perimeter that conductively engages separate sealing strips with springy contact fingers conductively held in a groove at the enclosure opening. U.S. Pat. No. 5,223,670 issued Jun. 29, 1993 to Hogan describes such an apparatus and the problems encountered. When cellular telephones are tested, they must be shielded from even the slightest stray radiation. Their emitted radiation must also be shielded when they are tested in a production facility. The closure must be repeatedly opened and closed, as each phone is tested in turn. The closure must be easy to open and close. The unit should take up little space.

LIGI TOOL AND ENGINEERING, INC. OF POMPANO BEACH, Fla. has been producing the RFI-100 Radio Interference Test Box for this purpose. It provides 80 decibel isolation up to 3 GHz. It employs a beryllium copper spring finger strip held captive in the cover that cooperates with a flange extending from the enclosure opening. The strip is series 97-542 produced by INSTRUMENT SPECIALTIES OF DELAWARE WATER GAP, Pa., U.S. Pat. No. 3,504,095. The fingers are spaced apart farther than is desirable to permit some bending of the straight strip. Because the strip cannot be bent through a radius of less than 3 inches, the overall dimensions of the apparatus are larger than is desirable. Construction needed to hold the strip in place adds to the cost. It would be desirable to have a greater degree of shielding, a smaller enclosure, and one that was less costly to produce.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a means of shielding an openable closure that would enable providing smaller radii, greater shielding, less costly construction, and longer useful life without maintenance. The invention comprises a closure seal and an openable RFI shielded enclosure for testing electronic equipment. The seal of the invention comprises a generally U shaped conductive spring finger strip seated in a groove in the cover. The strip comprises a continuous web with springy fingers extending downward therefrom. The strip is comprised of eight portions, four corner portions with small radius, and four straight portions closely adjacent to one another to make an effectively continuous perimeter. The strips are formed into the final desired curved and straight shapes prior to heat treatment. A short flange extends from the housing and is designed to fit into the strip, forcing the fingers of the strip apart to press the legs against the opposed walls of the groove. This provides spring biased electrical contact between the housing, the springy fingers, and the walls of the groove.

These and other objects, features, and advantages of the invention will become more apparent when the detailed description is studied in conjunction with the drawings in which like elements are designated by like reference characters in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an enclosure of the prior art with cover open.

FIG. 2 is a sectional view taken through line 2--2 of FIG. 1 with cover closed.

FIG. 3 is top view of the enclosure of the invention with cover closed.

FIG. 4 is an end view of the enclosure.

FIG. 5 is a top view of the housing with the cover removed.

FIG. 6 is a sectional view taken through 6--6 of FIG. 5.

FIG. 7 is a side elevation view of the housing.

FIG. 8 is a plan view of the cover from the underside.

FIG. 9 is a sectional view taken through 9--9 of FIG. 8.

FIG. 10 is an enlarged detail of the encircled portion of FIG. 9.

FIG. 11 is a plan view of a corner portion of the gasket after milling and before forming to final shape.

FIG. 12 is a plan view of a short straight portion of the gasket after milling and before forming to final shape.

FIG. 13 is a plan view of a long straight portion of the gasket after milling and before forming to final shape.

FIG. 14 is an enlarged detail as in FIG. 10 with the gasket in place and the cover closed to show the sealing mechanism.

FIG. 15 is a plan view of a portion of the gasket of another embodiment of the invention after milling and before forming to final shape.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawing FIGS. 1-2, an enclosure 1' of the prior art for testing a cellular telephone 10' is shown. It features a beryllium copper shielding gasket 2' held captive between slot 3' in the cover 4' and the slot 3" in the plate 6'. The gasket 2' has springy fingers 5' which extend laterally until bent inward by the flange 7' on the housing 8' as it closes. The finger before closing is shown in phantom. The radius of the seal is limited by the radius through which the strip may be bent. This determines the dimensions and shape of the finished enclosure. A more rectangular chamber of smaller dimensions would be more useful. The spring fingers are spaced apart by 0.015 inches to permit some bending. Machining the groove 3' with precision is very difficult, and increases the cost of manufacture.

Referring now to FIGS. 3-14, an RFI shielding enclosure 1 of the invention suitable for testing and adjusting cellular telephones is shown. Housing 8 has a substantially rectangular chamber 21 with four straight sides and four corners with small radius. A cover 4 has a slot 3 with four straight sides and four corners with central radius of 0.826 inches that holds captive a beryllium copper springy sealing gasket 2 with generally U shaped spring fingers 11 extending from a continuous base 14. A bend 18 intermediate the free ends 17 of the fingers and the base closes the space between the bends to 0.1476 inches. The fingers are spaced apart from adjacent fingers by only 0.005 for enhanced shielding. The gasket is able to conform to the small radius corners by means of its special construction. It is made up of four straight sections and four corner sections. They are chemically milled out of 0.005 inch beryllium copper strip stock. They are then formed to shape and heat treated to become springy and retain their shape. Tabs 9 may be bent out to retain the sections in holes 5 in the bottom of the slot. The slot 3 is cut out to 0.286 inches wide, and then an intermediate portion of the walls are cut away to 0.3060 inches width, forming projections 10 in groove 3 that hold the gasket sections in place once they are snapped in. The fingers 11 extend outward to touch the side walls of groove 3, and the free ends 17 of the fingers prevent movement past the projections 10 in the groove. The housing 8 has an upwardly projecting flange 12 with a thickness of 0.1520 inches arranged to slide between the bends 18 of fingers 11, forcing them further apart by 0.0024 inches on each side, and pressing the fingers against the side walls of groove 3, thereby making excellent low resistance double contact for enhanced electrical shielding. The beryllium copper gasket is plated with nickel to resist formation of insulating corrosion products. The flange is provided with a rounded edge 13 to facilitate insertion and prevent damage to the gasket. The dimensions of the gasket and the flange are arranged to cause very slight deflection for easy operation and long life, yet with enough wiping and spring action to ensure low resistance contact. The strip is free to move slightly within its groove under the forces of the moving flange 12, causing a wiping contact of the free ends of the strip against the walls of the groove, as well as the wiping contact between the flange and the fingers. Shielded multi pin electrical connector 22 is mounted in an aperture in the side wall.

In an alternative embodiment of the invention, as shown in FIG. 15, the two corner sections may be combined with one short section and two halves of the long sections to fabricate the sealing strip in only two separate identical pieces 20 for ease of manufacture and assembly.

In an alternative embodiment (not shown), the groove may be in the housing and the flange in the closure. The shape of the opening may vary, as desired.

The above disclosed invention has a number of particular features which should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While I have shown and described the preferred embodiments of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

sell Beryllium Copper Finger Strips

2007-08-27T17:44:00.000-07:00

Modern electronic equipment often requires EMI Gaskets to avoid radiating EMI/RFI and to prevent susceptibility to outside sources of EMI/RFI. EMI Gaskets designed and manufactured utilizing the strengths of beryllium copper (BeCu) are the industry standard throughout the world. Starting with the emergence of RFI problems in the early days of military electronics, BeCu EMI Gaskets have been the choice solution.

BeCu EMI Gaskets do two things very well:

1. Their mechanical spring characteristics far surpass all other gaskets in the industry.
2. They offer the highest EMI shielding effectiveness.


Clip On 2100	Snap On 2200	Stick On 2300	Twisted Fingers 2400	Angle Fingers 2500	More Fingerstrips

The contact of Beryllium copper finger strips are tolerant of a wiping or sliding action. The EMI Finger strip gaskets are produced in Beryllium copper or stainless steel, both have a high resilient spring quality. This makes the stainless- and beryllium copper finger strips ideal for applications where frequent opening and closing operations are likely. The product is available in a wide range of profiles and is also available in various plated versions.

Beryllium Copper Finger Strips are made from Beryllium Copper (BeCu),
that combine its high electrical conductivity giving high levels of EMI
shielding and grounding, with its spring features, fatigue resistance,
and anti-corrosion make them ideal for high cycle applications in
both compression and in a wiping action and for closure
applications where low closure forces are required. With these
characteristics the strips are suitable for used on closure doors,
electronic enclosures, and boxes where frequently opening and
closing operations are involved.

In order to be effective for maximum electrical contact and shielding
performance, the gasket must be compensate the gap between two
adjoining surfaces that exist due to the gap tolerances, misaligned
and/or irregular surfaces. Therefore, the compression should be
minimum of 25% of the original height, attenuation exceeding 100
dB for most profiles can therefore be achievable

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Radiation resistant closure

2007-08-27T07:43:00.000-07:00

A radiation resistant joint between an edge of a movable member and a corresponding edge of a fixed member. The joint comprises at least two bowed conductive contact fingers fixed at one end to one of the members with one finger superimposed over the other finger. The free end of the upper finger engages the bow portion of the lower finger. Means are provided for moving the lower finger and consequently the upper finger away from the member with which they are attached such that the bow portions of each finger engage a conductive plate on the other member to make a radiation resistant seal therewith
.Radiation resistant closures are known in which inflatable tubes are utilized to move flexible conductive contact strips mounted on one member into conductive contact with a plate mounted on another member. An advantage of such a construction is that wear and tear of the contact strips is reduced because the strips are not subjected to the sliding action of the plate passing over the strips during opening and closing movement of the members relative to one another since the tube is inflated only after the members are in a closed position with respect to each other. For example, in U.S. Pat. No. 2,757,225, there is disclosed a door for a radio shielded enclosure having an inflatable tube contained in the edges of a door for a moving contact member made of a thin flexible sheet metal strip into contact with a conductive strip mounted on the edges of a door frame. Because the sheet metal strip is of solid construction, it is important that the door fit accurately in its frame so as to assure that all portions of the strip along its length will be in conductive contact with portions of the door frame when the tube is inflated. The need for accurate and close fitting between the door frame and door necessarily increases cost of production.

Conductive strips in the form of comb-like bowed fingers such as disclosed in U.S. Pat. No. 3,589,070 have been proposed where the bowed portions of the fingers flex outwardly of a member to which they are mounted to conductively engage a conductive plate mounted on another member. The individual fingers are easily flexed so that they will accommodate variations in spacing between the members. However since the strips containing the fingers are made of a light flexible material, such as beryllium copper, the fingers can be easily broken or bent out of shape, which if this occurs, can lead to impairment of radiation seal integrity.

It is therefore an object of my invention to provide for a closure for forming a radiation resistant joint which may utilize the advantages of conductive strips having a plurality of comb-like conductive bowed fingers and which at the same time will insure integrity of a seal even in the event one of the fingers is broken off or bent out of shape.

Broadly a radiation resistant joint according to the invention comprises first and second resilient electrically conductive contact fingers where each finger has a bowed portion comprising a part of a finger strip affixed to an edge of either a movable member or a fixed member. The second resilient fingers are affixed at one end in an overlapping relation to an end of the first fingers with both fingers being connected to an edge of one of the members. The free ends of the second fingers overlap and engages the bowed portions of the first fingers. Bowed portions of both fingers are adapted to engage a conductive plate on the other member with which the fingers are not connected so that the fingers form a conductive seal between the edges of the members.

Preferably the fingers are in a comb-like strip and are made of an electrically conductive material, such as for example, beryllium copper.

Further an inflatable tube is preferably positioned between the first fingers and the member to which it is connected such that when the tube is inflated, it will move the bowed portions of the first fingers and the free ends and bowed portions of the second fingers outwardly towards a conductive plate of the other member. When the tube is in a deflated condition, the natural flexure of the fingers will move the bowed portions of the fingers out of contact with the conductive plate. By this construction the fingers are protected from damage when the members are moved to a closed position with respect to one another where the conductive plate is free to slide over the fingers without contact during opening and closing movement of the members. Further use of an inflatable tube to move the fingers outwardly into conductive engagement with the plate allows the fingers to be positioned in a groove contained in the member the sides of which give further protection against inadvertent damage to the fingers.

The fingers and inflatable tube may be mounted on either the edges of the movable door member or on the edges of a fixed frame member surrounding the door. The conductive plate would be mounted on a corresponding edge of the other member. Preferably the fingers and tube extend around the complete periphery of either the door or fixed frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of edges of a door and corresponding edge of a fixed frame having a closure according to the invention in an unsealed position; and

FIG. 2 is a view similar to FIG. 1 showing the closure in a sealing position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2 there is illustrated a movable door member 1 and a fixed frame member 2 with the door member being in a closed position with respect to the fixed frame member. A first bowed finger 3 is connected at one end to a conductive strip 4 forming part of the door member. A second bowed finger 5 is also connected to the strip 4 and in overlapping relation to the finger 3 such that the free end 6 of the second finger 5 engages the bowed portion 7 of the first finger 3.

The first and second fingers 3 and 5 comprise comb-like strips and are connected to the conductive strip 4 by means of a screw 10 engaging a clamp 11 between which the ends of finger strips are positioned. Other means, for example riveting or welding, could be used to connect the finger strips to the conductive strip.

The door 1 comprises conductive side plates 15 and 16 preferably of a ferrous material so as to provide a shielded structure. An inflatable tube 17 is positioned between the side plates 15 and 16 and is adapted to be connected to a source of fluid pressure, not shown.

The fixed frame member 2 has a side plate 18 comprising ferrous material also forming a shielding structure. A conductive plate 19 is connected to the plate 18 and extends perpendicularly thereto. As shown in FIG. 2 the plate 19 is adapted to be contacted by the bowed portions 7 and 5' of the finger strips 3 and 5 so that a conductive connection is made at two points. Thus if one of the fingers is broken off or bent out of shape, the other finger will continue to make sealing contact with the plate to insure integrity of radiation resilient joints between the members.

The inflatable tube 17 comprises an elastomeric material which has a memory to assume the shape shown in FIG. 1 when deflated to assure that the fingers 3 and 5 may spring or flex out of contact with the plate 19.

The side plate 16 may as shown in the figures extend in the righthand direction beyond the plate 19 so as to provide some degree of protection to the tube 17 and fingers when the door member is in an open position with respect to the frame member.

While the arrangement shown in FIGS. 1 and 2 includes having the fingers and inflatable tube mounted in a door member, the fingers and inflated tube could instead be mounted in a fixed frame member and the conductive plate adapted to contact the fingers would then be part of the door member.

Contact fingers constructed according to the invention are also applicable for use as face seals between a sliding type door which is adapted to slide parallel to a wall to cover or close a wall opening. In this instance the fingers would be affixed to the face of the wall around the wall opening to engage the face of the door, or, alternatively, would be affixed to the face of the door around its periphery to engage the face of the wall around the door opening.

Further while two fingers are shown superimposed, further fingers could be added so as to be superimposed on the second finger 5 if further radio frequency attenuation was desired.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Mechanical design tips for EMI shielding

2007-08-26T05:43:00.000-07:00

Nowadays every company is involved with CE / EMI demands. The use of electronics increases as well as the frequencies. Therefore radiation and immunity has to be taken into account in an early stage during the development of new products. In many cases EMI problems cannot be solved at PCB level, the enclosures and cables will have to be shielded.

When to use shielding?

Shielding is a fast way to comply with legal demands like CE or FCC or to prevent electro-magnetic interference. Since time-consuming development is not required, shielding is cost-effective. Therefore shielding is used for non consumer products quantities or if a quick market introduction is needed. It is also used for appliances with high radiation or sensitivity levels or for products of which these levels are not known in advance, like modular enclosures.

Radiation and conduction

Electro-magnetic interference can be transferred by radiation and conduction. Conduction plays an important role with frequencies below 10 MHz. To prevent this, cables and enclosures have to be shielded with magnetically conductive materials. The lower the frequency, the thicker the shielding needs to be. Click HERE for cable shielding solutions.

For high frequencies (HF shielding, >40 MHz), only a very thin layer of highly conductive material is needed.

Avoid gaps

The higher the frequency, the shorter the wavelength. This means that when the frequency increases, the tolerable gap dimensions decrease. In other words: doors, panels and other parts need to be connected electrically on all sides. The easiest way to do this is with highly conductive EMI shielding gaskets. Most of them are self-adhesive for easy mounting.

To select the appropriate gasket, several aspects have to be taken into account: the rigidity of the construction, the distance between the fixings, the distance between them and the construction materials used.

The allowed stiffness of the gasket depends on the rigidity of the construction and the distance between the fixings. If the gasket is too stiff, the door, lid or panel will deflect and gaps will be caused instead of prevented (fig. 1). Especially for doors several kinds of gaskets have been developed, which combine a very large compression range, low closure force and high conductivity. Many of them can be used in existing products, without changing the construction. The gasket selection diagram is very helpful to determine the appropriate gasket material.

Galvanic corrosion

The conductive layer on the outside of the gasket needs to be in the same galvanic range as the construction materials. Otherwise galvanic corrosion will occur and the electrical conduction between the parts will be lost. This will decrease the shielding performance. Commonly used criteria: no more than 0.3 Volts for harsh environments (salt spray / weathering) and no more than 0.5 Volts for benign environments (indoors, salt-free condensation only). Click HERE for an overview of the galvanic range.

To obtain a contact surface within the same galvanic range as the conductive covering of the gaskets, a Metal Tape with conductive self-adhesive can be applied. This can be provided with a masking tape of a smaller width. The paint overlaps the tape, which increases bonding and corrosion resistance (fig 2).

An other way to avoid galvanic corrosion is to take care that the environmental influences do not reach the EMI shielding gasket, for example with a combined EMI / water seal (fig. 3)

Some manufacturers of EMI shielding gaskets use carbon containing layers on the outside to prevent corrosion of the gasket. Please be aware that these are not galvanically compatible with many commonly used construction materials and that corrosion of the contact surfaces of the construction will take place. EMI shielding gaskets with a conductive layer of reinforced Amucor® foil are much more compatible with materials like zinc plated steel and aluminium, and will prevent this kind of corrosion.

Displays / vent panels

Not only connections between construction parts, but of course also displays and vent panels need to be shielded. Displays can be provided with a sputtered transparent Conductive Coating for HF shielding (>30 Mhz, fig 4) or a fine metal wire mesh for lower frequency / high performance shielding (fig. 5). The conductive sputter layer can be coated directly on the display or can be supplied on thin films for smaller amounts.

Of course, the shielding of the displays will have to be connected with the shielding of the enclosure to guarantee optimal damping. This can be done with a gasket or metal tape with conductive self-adhesive.

Vent Panels are usually shielded with aluminium honeycomb vents. These give excellent shielding performance with minimal loss of airflow. For superb shielding performance so-called cross-cell honeycomb vents are used. These consist of two or more layers of aluminium honeycomb, rotated 90° (fig. 6). Honeycombs are usually applied with a rigid aluminium frame and a gasket of 2-5 mm for optimal connection with the construction.

Cables

To prevent radiation from escaping past the shielding through power and signal cables, they need to be shielded or filtered. Shielding can be provided by ready-made shielded cables, shielding tube and cable wrapping. Shielding tube consists of hollow braided metal wire, through which the cable or bundle of cables can be pulled to shield it. Cable Wrapping is a knitted metal wire tape, which is wrapped around a cable or bundle of cables. With this, it is very easy to make branches.

The shielding of the cables always needs to be connected properly with the shielding of the enclosure; otherwise the cable will act as an antenna and the shielding will be useless. For heavy duty and military applications, shielded cable glands and special cable entry systems with compressed conductive rubber seals are commonly used. For commercial applications and appliances that do not need a water seal, Entry-shield is used in most cases. Entry-shield consist of two pre-compressed flexible strips of EMI shielding gasket, between which the cables are entered. This way, many cables can be entered simultaneously with minimal mounting and it is very easy to add cables later (fig. 7).

Connectors

What was said about cables also applies for Connectors. These also need to be shielded or filtered and connected with a gasket. These gaskets can consist of 1mm thick die-cut material, which can also be manufactured easily according to customer specifications, with little tooling costs (fig. 8).

Shielding at the source

If the source of the radiation or sensitivity is known, shielding can be done at the source. The interfering parts can be packed in a folded box or envelope of die-cut shielding foil with an insulating layer on the inside to avoid short-circuiting (fig. 9). It can also be done by soldering vertical metal strips on the PCB to create compartments. These compartments are closed by adding a lid of flexible die-cut shielding foil (fig. 10) or by pressing a soft foam sheet with a conductive surface against the strips (fig. 11). With the latter option, many compartments can be shielded with just one single cover.

EMI Regulations

2007-08-26T05:34:00.000-07:00

Government regulations in the US and many other countries prohibit electronic products from emitting EMI that could interfere with radio and television receivers. European regulations also include EMI immunity levels. Manufacturers of commercial electronic products generally contend with three types of EMI problems:

* Suppression of internally generated signals to prevent excessive levels of radiated and/or conducted emissions
The FCC in the United States, CSA in Canada, VCCI in Japan, AUSTEL in Australia, and legislation by EU (European Union) member countries all set certain standards for EMI emission levels that commercial electronic devices must meet before being sold in those countries. Many electronic products sold in the US must be tested and verified or certified for compliance with the FCC’s Part 15 regulations.

* External ambient interference with equipment operation
Many companies establish their own specifications for immunity to EMI over a range of phenomena. These may include electrostatic discharge (ESD), radiated immunity, and electricfast transients (EFT). This is not yet a requirement in the US; however, EU regulations currently do include immunity requirements.

* Internally generated emissions interfering with equipment operation
EMI from one circuit can interfere with the function of another within the same system or subsystem. Typically called cross-talk, this problem is the most common source of system susceptibility. Cross-talk frequently occurs in densely packaged mobile or portable equipment.
Design assistance that can make
a real difference in time and cost …
As the world’s largest manufacturer of EMI shielding materials, Chomerics offers its customers unparalleled knowledge of system design and regulatory compliance. We encourage you to contact our Applications Engineering Departments in Woburn or Marlow for practical advice on product selection. Featured in this catalog is Chomerics’ comprehensive product line for commercial applications. Since 1961, vigorous product development in pace with the rapid advances in electronics has made Chomerics a primary force in EMI shielding technology.
If you don’t find the ideal solution, call us.
We’re probably working on it!

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Electromagnetic Compatibility and Interference

2007-08-26T05:31:00.000-07:00

Figure 1
Reducing EMI Radiation and EMI Susceptibility

Radiated EMI may be eliminated or reduced by the use of shielded enclosures and shielding materials. The second method for establishing EMC in a device is to improve its immunity (or reduce its susceptibility) to interference from external EMI sources. Figure 1a illustrates an EMI-susceptible device. Susceptibility to external EMI may be reduced or even eliminated by designing circuits and choosing components which are inherently less sensitive to interference. As in the case of internal sources, conducted EMI may be reduced with filtering devices on incoming and outgoing leads as shown in Figure 1b, and susceptibility to externally radiated EMI may be reduced with use of effective shielding, as illustrated in Figure 1c.

EMI Shielded Window Provides Optical Clarity on CRT

2007-08-26T05:28:00.000-07:00

A manufacturer of process control instruments needed to improve the readability of shielded CRT displays on a number of its models. Shielded windows used on the CRTs significantly reduced light transmission, resulting in undesirably dark screens. Some displays were also troubled with distorted text when the mesh in the shielded windows presented moiré pattern problems. The solution could not add cost or reduce the current shielding effectiveness.

Chomerics provided emiclare™ EMI shielded windows to improve CRT readability at costs less than the previous method. The emiclare windows feature a unique wire mesh weave developed for brighter image quality through higher light transmission. These polycarbonate windows are fully laminated with optically matched adhesives to reduce losses from reflection and dispersion. Their front surfaces have a non-glare hardcoat, and a clear hardcoat is on rear surfaces.

Together, these construction features provided great improvement to the CRTs' optical performance. They also provided better shielding performance, surpassing 50 dB effectiveness at 100 MHz. The emiclare shielding windows were delivered in 2 weeks at unit costs below the original window prices.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Metal Spring Fingers Add Shielding on High-Density Connector

2007-08-26T05:27:00.000-07:00

.A mainframe OEM was experiencing radiated EMI problems at the interface of a high-density, cable connector and an input/output (I/O) panel. 360-degree shielding was needed around the pin area. The shielding design had to accommodate changing deflection forces as the connector was flexed or jostled.
.....Chomerics designed a metal spring finger shielding solution using finite element analysis and 3-D models to find the optimum gasket shape, thickness, compression force and deflection dynamics to meet attachment and plug-in requirements.
The gasket shape included an integral clip for secure mounting along the front edges of the connector's die-cast back shell. Strips of the gasket ran across the perimeter of the connector and made tight, continuous contact with the I/O panel to provide a Faraday cage-type EMI shielding solution.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI Shielding Methods

2007-08-26T05:21:00.000-07:00

EMI Shielding Principles
The importance of wave impedance is shown by an electromagnetic wave encountering an obstacle such as a metal shield (see Figure 3). If the impedance of the wave differs greatly from the natural impedance of the shield, much of the energy is reflected and the rest is transmitted across the surface boundary, where absorption in the shield further attenuates it. Because most metals have an intrinsic impedance of only milliohms, less low impedance H-field energy is reflected and more is absorbed. This is because the metal is more closely matched to the impedance of the field. This is also why it is difficult to shield against magnetic fields. On the other hand, the wave impedance of electric fields is high, so most of the energy is reflected for this case. At higher frequencies, typically over 10 MHz, EMI shielding is governed mostly by absorption

Figure 3
Attenuation of EMI by a Shield
Shielding effectiveness of metallic enclosures is not infinite, because the conductivity of all metals is finite. They can, however, approach very large values. Because metallic shields have less than infinite conductivity, part of the field is transmitted across the boundary and supports a current in the metal, as illustrated in Figure 4. The amount of current flow at any depth in the shield, and the rate of decay is governed by the conductivity of the metal, its permeability, and the frequency and amplitude of the field source. The residual current appearing on the opposite face is the one responsible for generating the field which exists on the other side.

*

The current density in a metal shield is not affected by the shield’s thickness. A secondary reflection occurs at the far side of the shield for all thicknesses. The only difference with thin shields is that a large part of the re-reflected wave may appear on the front surface. This wave can add to or subtract from the primary reflected wave depending upon the phase relationship between them. For this reason, a correction factor appears in shielding equations to account for reflections from the far surface of a thin shield.

Figure 4
Variation of Current Density
with Thickness for Electrically Thin Wall
E = Electric Field Strength
J = Current Density
i = initial
t = transmitted

*

EMI Gasketing

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A gap or seam in a shield will allow electromagnetic fields to radiate through the shield, unless the current continuity can be preserved across the gaps. The function of an EMI gasket is to preserve continuity or current flow in the shield. If a gasket is made of material identical to the walls of the shielded enclosure, the current density in the gasket will be the same. (This assumes it could perfectly fill the slot, which is not possible due to mechanical considerations.)

The flow of current through a shield including a gasket interface is illustrated in Figure 5. Electromagnetic leakage through the seam can occur in two ways. First, the energy can leak through the material directly. The gasket material shown in Figure 5 is assumed to have lower conductivity than the material in the shield. The rate of current decay, therefore, is less in the gasket, resulting in more current flow on the far side of the shield. This increased flow causes a larger leakage field to appear on the far side. Second, leakage can occur at the interface between the gasket and the shield. If an air gap exists at the interface, the flow of current will be diverted to the points or areas in contact. A change in the direction of the flow of current alters the current distribution in the shield as well as in the gasket, which lowers shielding performance. A high resistance joint does not behave much differently than an open seam. It simply alters the distribution of current somewhat. A current distribution for a typical seam is shown in Figure 5. Lines of constant current spaced at larger intervals indicate less flow of current. It is important in gasket design to make the electrical properties of the gasket as similar to the shield as possible, maintain low impedance interface surfaces, and avoid air gaps which also increase joint resistance.

*

Shielding and EMI Gasket Equations

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As described above, electromagnetic waves incident upon a discontinuity will be partially reflected, and partly absorbed by the material. The effectiveness of the shield is the sum total of these two effects, plus a correction factor to account for reflections from the back surfaces of the shield.

Reductions in field strength are determined by the frequency, the shielding material’s conductivity, thickness and permeability, and by the distance between the radiating source and the EMI shield.

How well a shield reduces the energy of (attenuates) a radiated electromagnetic field is referred to as its shielding effectiveness, or SE. The standard unit of SE measurement is the decibel, or dB. The decibel value is the ratio of two measurements of electromagnetic field strength taken before and after shielding is in place. Every 20 dB increase in SE represents a tenfold reduction in EMI leakage through a shield. A 60 dB shield reduces field strength by a factor of 1,000 times (e.g., from 5 volts per meter to 5 millivolts/meter).

The overall expression for shielding effectiveness is written as:
SE = R + A + B (1)
where
SE is the shielding effectiveness
R is the reflection factor
A is the absorption factor, and
B is the correction factor to account for reflections from the far boundary

All values are expressed in dB (decibels) Reflection loss (R) includes reflections at both surfaces of the shield, and is dependent upon the relative mismatch between the incoming wave impedance and the frequency of the impinging wave, as well as upon the electrical parameters of the shielding material itself. The equations for the three principal fields are given by the following expressions:

where:

RE, RH, and RP are the reflection terms for the electric, magnetic, and plane wave fields expressed in dB
G is the relative conductivity referred to copper
f is the frequency in Hz
m is the relative permeability referred to free space
r1 is the distance from the source to the shield in inches
The absorption term (A) is the same for all three waves and is given by the expression:

where:
A is the absorption or penetration loss expressed in dB, and t is the thickness of the shield in mils.

The correction factor (B) can be mathematically positive or negative (in practice it is always negative), and becomes insignificant when A>6 dB. It is usually only important when metals are thin, and at low frequencies (i.e., below approximately 20 kHz).

*

A plot of reflection and absorption loss for copper and iron is shown in Figure 6. This illustration gives a good physical representation of the behavior of the component parts of an electromagnetic wave. It also illustrates why it is so much more difficult to shield magnetic fields than electric fields or plane waves. Note: in Figure 6, copper offers more shielding effectiveness than iron in all cases except for absorption loss. This is due to the high permeability of iron. These shielding numbers are theoretical, hence they are very high (and unrealistic) practical values.

When only electric field or plane wave protection is required, reflection is the important factor to consider in the design. If magnetic shielding is required, particularly at frequencies below 10 kHz, it is customary to neglect all terms in equation (1) except the absorption
term A.

Nomographs are available from Chomerics to aid designers in determining absorption and magnetic field reflection losses directly. These nomographs are based on the previously shown equations used in determining shielding effectiveness. Commercial equipment typically needs shielding of 40-60 dB from 30 MHz to 1 GHz, and often 10 GHz. (See also Chomerics’ EMI Shielding for Military/Aerospace Electronics Engineering Handbook.)

EMI Gasket Types

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Conductive EMI gaskets must conform intimately to enclosure mating surfaces. They provide current continuity in shielding systems by reducing resistance across the seams. EMI gaskets are generally made of metal, metal combined with elastomer materials, or metallized fabric over foam cores. All-metal gaskets include knitted wire mesh made in different metals for cost-performance choices. By knitting wire mesh around elastomer cores, metal gaskets can better meet mechanical design needs such as enhanced compressibility. Another type of metal gasket, typically used in door seams (where shear forces are present), features linear rows of beryllium copper spring fingers, or spirals.
Foam-core gaskets covered by conductive fabric, yarn or metal foil provide a large deflection range with modest closure force. Another approach for low closure force applications is a hollow silicone tube with a conductive surface coating.

Conductive elastomer gaskets, which contain metal-plated particles, provide excellent shielding characteristics. Such gaskets can be extruded and cut to length, typically for preventing EMI leakage around the perimeters or between sections of electronic enclosures. Co-extruded EMI gaskets combine a conductive elastomer with a non-conductive silicone environmental seal. Conductive elastomers can also be die-cut from sheet material, or molded into intricate shapes. Robotically applied form-in-place gasketing systems precisely dispense conductive elastomer compounds on electronic housings. Specially formulated conductive elastomers can be molded onto thin-wall plastic spacer frames to provide grounding of circuit boards in small enclosures such as cellular phone housings. Conductive elastomers are also being molded directly onto the inner surface of large plastic housing covers in place of plating or other types of metallizing. These shielded covers feature integral conductive elastomer walls, which eliminate the need for EMI gaskets. When form-stable gaskets are impractical for an application, conductive adhesives and sealants can often be applied. A variety of formulations are available for providing either rigid or flexible shielding solutions. These materials can also be used for bonding EMI gaskets to flange surfaces.

EMI Gasket Selection

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The most critical features to consider when evaluating EMI gaskets are: shielding effectiveness, operating environmental conditions, fitting the physical properties of the gasket with the packaging design, electrical stability, and the installed cost. Chomerics’ inPHormTM product selection software provides a convenient, comprehensive system for engineers to create an application profile. The inPHorm program recommends one or more products that will best fit the application needs. On-line technical data is provided for hundreds of EMI shielding products (see Inside Front Cover).

Shielding Effectiveness
As described in the preceding pages, determining a system’s overall shielding needs involves understanding the radiated emission spectrum of the equipment, and the specifications the unit must meet. Various EMI gasket types provide different levels of shielding effectiveness across the frequency range of 10 kHz to 20 GHz.

Operating Conditions
One reason so many gasket variations exist is a result of trying to provide a best fit for the different operating environmental conditions. Exposure to high and low temperatures, wind and rain, salt spray from the ocean, solvents used in cleaning and plating, and other conditions can severely affect the life of a gasket.

Mechanical Requirements
The primary goal of a shielding gasket is to seal openings in an electronic enclosure to prevent transmission of EMI. Improper design of the seal or enclosure mating flanges can result in a failure to meet this goal. Several mechanical design issues must be considered for the proper mating of an EMI gasket with the flanges of an electronic enclosure. Among the most important are compression-deflection and compression set.

* Compression-Deflection
EMI gaskets require some amount of compressive force to function properly. As a result of this load the material will decrease in height (deflect). The magnitude of the decrease is proportional to the applied load up to the elastic limit or the point at which the material yields or ruptures. Many commercial-grade gaskets must deflect 30-40% under low closure forces to properly maintain contact with mating flanges.

* Compression Set
If a gasket material is subjected to a compressive force for an extended time, some deflection remains when the load is removed. Compression set is an important property in designs where the gasket will be compressed and released regularly while in service, such as in enclosure doors and access panels.

Electrical Stability
EMI gaskets provide conductive pathways that electrically bond system components to a common ground. The gaskets serve as low impedance conductors to ensure the reliability of an enclosure’s shielding. For example, an EMI gasket will provide continuity between the housing shield and other system ground points. Gasket conductivity and electrical stability are critical to system performance and shielding integrity.

Installed Cost
The method of installing an EMI gasket can be a major factor in determining EMI shielding costs. Gaskets can be installed using pressure-sensitive adhesives, fasteners, or epoxies, or by press-fitting into grooves. Some gaskets are molded in place on the enclosure flange or on a plastic spacer frame.
The installed cost for an EMI gasket includes the cost of the gasket, together with labor and other manufacturing costs. A gasket applied without fasteners or adhesives, for instance, may offer lower installed cost than an EMI gasket purchased at a lower price.

Where EMI Shielding is Needed
Requirements for EMI shielding abound in computers, medical devices, telecommunications, and many other types of electronic equipment. As new emission and immunity requirements are placed on these devices, the importance of shielding grows.
Among the typical applications for EMI shielding are the following:

Enclosures
Plastic and other non-conductive materials used for lightweight housings can be metallized with sprayable conductive paints, thin-film metal coatings or plating. Laminates of metal foil and plastic film can be formed and die-cut into shadow shields, ground planes or Faraday cages. Metal housings for electronic systems provide inherent levels of EMI shielding, dependent on factors such as metal type, flange design, and seam and aperture treatment.

Apertures
Doors, cable ports, vents, windows, access panels and other openings in an otherwise shielded electronic package are pathways for radiated EMI. A variety of gaskets and specialized conductive materials are available for preserving shielding around door seams and the perimeters of other openings. Shielding vents and windows are designed to reduce the amount of EMI passing through such apertures.
The amount of EMI leakage through an opening is a function of the maximum dimension of the opening at a given frequency. A long, narrow slit, regardless of width, like the gap around the edge of a door, will leak much more radiation than a round hole of the same area. The imperfect joints between panels or covers and enclosure walls are typical “slots” where EMI can efficiently escape or enter a shielded enclosure. Conductive EMI gaskets inserted between panel mating surfaces will provide low resistance across the seam, preserve current continuity of the enclosure, and provide the necessary shielding.

Cables
Signal-carrying cables can act as antennas to radiate EMI. Conversely, false signals can occur when EMI couples into a cable. A number of shielding products are available for reducing EMI problems on both internal and external cables.

Grounding Issues
Shielding against EMI emissions is commonly provided by a conductive enclosure. The separate parts of the enclosure must be electrically bonded together and grounded for the shielding to work. Disruptions in the electrical continuity between parts adversely affect shielding performance. Proper grounding of PCBs and shielding enclosure components is also a method for reducing board-generated EMI. However, improper or ineffective grounding may actually increase EMI emission levels, with the ground itself become a major radiating source. Many Chomerics shielding materials can be used for providing conductive grounding paths.

Gasket Mounting Choices

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Our various EMI gasket mounting techniques offer designers cost-effective choices in both materials and assembly. These options offer aesthetic choices and accommodate packaging requirements such as tight spaces, weight limits, housing materials and assembly costs. Most Chomerics gaskets attach using easily repairable systems. Our Applications Engineering Department or your local Chomerics representative can provide full details on EMI gasket mounting. The most common systems are shown here with the available shielding products.

Pressure-Sensitive Adhesive
Quick, efficient attachment strip

* Conductive Elastomers
* SOFT-SHIELD
* POLASHEET
* SPRING-LINE
* POLASTRIP

Friction Fit in a Groove
Prevents over-deflection of gasket Retaining groove required

* Conductive Elastomers
* MESH STRIP
* POLASTRIP
* SOFT-SHIELD
* SPRINGMESH

Adhesive Compounds
Conductive or non-conductive spot bonding

* Conductive Elastomers
* MESH STRIP

Robotically Dispensed
Form-in-Place
Conductive Elastomer
Chomerics’ Cho-Form™
automated technology applies
high quality conductive elastomer gaskets to metal or plastic housings. Manufacturing options include Chomerics facilities, authorized Application Partners, and turnkey systems.

Friction Fit on Tangs Accommodates thin walls, intricate shapes

* Conductive Elastomers

Spacer Gaskets
Fully customized, integral conductive elastomer and plastic spacer provide economical EMI shielding and grounding in small enclosures. Locator pins ensure accurate and easy installation, manually or robotically.

Clip-On Gaskets
Require knife edge mounting flange.

* Conductive Elastomers
* METALKLIP
* CLIP-SHIELD
* SOFT-SHIELD 5000

Rivets/Screws
Require integral compression stops Require mounting holes on flange

* Conductive Elastomers
* SHIELDMESH
* SPRING-LINE
* COMBO STRIP

Frames
Extruded aluminum frames and strips add rigidity. Built-in compression stops for rivets and screws.

* Conductive Elastomers
* Mesh Strip

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

RFI Shielding Ferrites and Gaskets

2007-08-26T05:03:00.000-07:00

Without question, the two most effective, simple and inexpensive methods of RFI shielding today are ferrite RFI suppressors and copper alloy RFI shielding gaskets.

It is of no value to use a shielded enclosure, no matter how well designed, and then allow electromagnetic energy to flow through openings or penetrate it along the power cables and signal cables. The alternative...deal with the openings and cables in the most effective manner...ferrites and gaskets.

Eclipse's ferrite designs are the most innovative types found today - solid beads and split beads made in many versatile geometries, material compounds and installation alternatives give you more than ample choices for the optimum approach.

Eclipse's copper alloy gaskets are the standard to which all other forms of gaskets are compared despite obvious incomparability - they are substantially the highest strength, highest performance gasket alternative. A wide selection of available profile shapes and sizes offers a solution for every application.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Choosing the Right EMI Shielding Gasket

2007-08-26T04:58:00.000-07:00

In choosing the most effective EMI shielding gasket for products such as telecommunications equipment, computers, and automotive and medical electronics, often you can narrow the selection to three options: conductive fabric over foam, conductive elastomers, or beryllium-copper (BeCu) strips (fingerstock). Depending on the product’s needs, these solutions provide varying EMI protection, intricacy of forms, and environmental protection.

Several factors must be considered when designing EMI shielding into products:

Form, referring to the complexity of the form or pattern in which the gasket fits.
Mechanical durability.
Attenuation level. Most commercial applications typically require 60 to 100 dB but can go as high as 120 dB.
Compression. Most commercial applications require low closure force. Compression force has the greatest effect on conductive elastomer shielding characteristics. Since they can be loaded with relatively low- to high-conductivity filler materials, conductive elastomers supply the widest range of shielding effectiveness.
BeCu strips and conductive fabric-over-foam gaskets are not affected as much by compression forces. As a result, they offer a narrower range of shielding capabilities. See Table 1 for a comparison of typical shielding effectiveness for foam over fabric, elastomers, and BeCu strips.
Galvanic compatibility between the gasketing conductive material and substrate metal. This avoids creating a galvanic cell, which can lead to corrosion.
Environmental sealing from water, dust, and similar external substances.

Gasket Type	Typical Shielding Effectiveness (10-kHz to 10-GHz Range)
Conductive Fabric Over Foam	80 to 115 dB
Conductive Elastomers	40 to 120 dB
BeCu Strips	75 to 120 dB

Other selection considerations include cost, service life (cycles, actuations), tolerances, and mounting methods such as fastener types and adhesives.

Conductive Fabric Over Foam

Conductive fabric over foam makes sense where no environmental seal, complex profile, or demanding mechanical durability is needed (Figure 1). It can be the lowest-cost option.

The covering can consist of nylon thread coated with conductive metals woven into a fabric and wrapped over a soft urethane foam. Alternatively, a woven fabric may be metallized with nickel-copper or other metal coating, then wrapped around the foam core.

Flexible, conformable fabric over foam maintains close contact with surfaces with minimal compression for low-closure-force applications. It provides snug contact over irregular surfaces and around bends and corners, making it good for electronic enclosures such as doors and access panels.

Less demanding EMI applications include grounding contact pads in cell phones and laptop computers. Fabric-over-foam gaskets also can shield the input/output backplane of laptops and PCs.

The manufacturing process limits it to relatively simple cross-sectional profiles such as squares, rectangles, and D-shapes. When a more complex profile is necessary, fabric over foam may not be the best solution.

Conductive Elastomers

For very small cross sections, a formed-in-place silicone-based silver-copper-filled or nickel-graphite-filled conductive elastomer is dispensed robotically (Figure 2). The robot can deposit the elastomer on a surface as narrow as 0.025 to 0.030 in.

Conductive elastomers are filled with a range of materials, from silver (highest conductivity) to carbon. Carbon-filled elastomers, having the lowest conductivity and cost, serve applications requiring low shielding levels. Other filler materials include nickel-coated graphite, silver-plated glass, silver-plated copper, and silver-plated aluminum. Nickel-graphite is the most popular for commercial applications because of good cost/performance attributes.

BeCu Strips

When you need mechanical durability, such as frequent direct compression actuations or shearing forces, BeCu strips make the best choice (Figure 3). BeCu fingerstock withstands lateral shearing forces as well as perpendicular forces, where other shielding materials are best suited for perpendicular, direct-compression applications.

Thin BeCu strips, available in many profiles, provide shielding or grounding but do not supply an environmental seal. BeCu fingerstock can be plated with many different metal types, offering broad galvanic compatibility with substrate metals.

In response to EPA restrictions and ISO 14000 requirements regarding disposal of beryllium, stainless steel is gaining preference over BeCu in many applications. Readily disposable stainless steel solves environmental problems, and provides comparable shielding effectiveness at prices similar to BeCu.

The use of stainless steel is progressing slowly because of the expense of developing new tooling. Presently, only a relatively small number of profiles are offered in stainless steel. In some cases, customers are sharing the expense of developing tooling for specific applications with the EMI gasket manufacturer.

Hybrid Shielding Materials

Two other hybrid EMI shielding options round out the designer’s choices. They can cost half that of conductive elastomers but are limited to relatively simple profiles.

The first material is a silicone or fluorosilicone rubber strip coextruded with wire mesh (Figure 4). Limited to a square or rectangular profile, it can be used in enclosures that have grooves. In the groove, the silicone faces the environment for environmental sealing; the wire mesh faces inside toward the electronics to provide the electromagnetic attenuation.

In the second option, oriented monel or aluminum wires are situated perpendicularly through pads of silicone rubber. Again, simple shapes are cut from sheets of this material. Costs are lower than conductive elastomer, but the material cannot adapt to applications requiring complex forms.

Applications

A prolific application for EMI shielding materials is wireless telecommunications in base stations and cellular phones. Here are two examples:

An aluminum casting for a wireless base station component posed both an EMI and an environmental shielding challenge because the electronics were isolated with a pattern of thin walls which formed separate compartments. The walls were too thin to accommodate fabric-over-foam or BeCu gaskets.
The solution was to mold a conductive elastomer with a rigid insert in the pattern that fit over the compartments. The resulting rigid gasket simplified assembly in the casting.
The circuit boards of a small cellular phone handset are isolated by erecting thin ledges around them and covering the ledges with EMI and environmental shielding. To lay down the ultrathin gasket, a robot dispenses a form-in-place conductive elastomer on top of the ledges.

Selecting a Solution

Conductive foam over fabric, conductive elastomer, and BeCu strips provide applications for a wide range of EMI shielding. Based on detailed data provided by the manufacturer, you can select the best EMI shielding solution. For more guidance and expertise in designing the most effective solution, consult your EMI shielding manufacturer.

Beryllium Copper Finger Strips 6

2007-08-25T23:56:00.000-07:00

92-060

92-062

92-064

92-065

92-066

92-069

92-070/072/074/076/078

92-071

92-073

92-079/100

92-082/084/086

92-101

92-102/104

92-106

92-108

92-110

92-112

92-114

92-120

92-130

92-136

92-140

92-141

Beryllium Copper Finger Strips 5

2007-08-25T23:55:00.000-07:00

92-008

92-010/012

92-014/016

92-018/020

92-021

92-030/031/032/034/035/045

92-033

92-036/037

92-038

92-039

92-040

92-041

92-042

92-043

92-044

92-046

92-047

92-048/049/080

92-050

92-051

92-052

92-054

92-056

92-058

Gasket Installation

2007-08-25T23:53:00.001-07:00

Retaining Lance Options for Clip-ons - Most clip-on styles are available with optional retaining lances which enhance the spring grip onto the mounting surface.

Adhesive Tape Specifications - Eclipse's shielding designs incorporate two types of transfer adhesive tape on many of the gaskets.

Instant Tac Adhesive

Conductive Tac Adhesive

Attachment

1. Proper Size - Determine the correct size of the mounting area.

2. Dynamic Range of Compression - Each shield gasket compresses a certain distance depending on the design. A positive contact force can usually be assured after the gaskets are compressed 25% of relaxed height and beyond.

3. Attachment Methods - Among Eclipse's standard configurations, are the following:

4. Correct Orientation - Many of the Eclipse gasket designs depend on the active contact surface (top) being engaged at, or behind, the cross-sectional centerline. To assure the proper angle of engagement, follow the guidelines below for best results.

Beryllium Copper Finger Strips 4

2007-08-25T23:48:00.000-07:00

Designed with a minimum residual stress and highly leveraged spring action. The free end features a fold-under lip which facilitates a low coefficient of friction on most surfaces. Extremely high endurance life. Installs easily with standard Instant Tac adhesive.


					Designed with a minimum residual stress and highly leveraged spring action. The free end features a fold-under lip which facilitates a low coefficient of friction on most surfaces. Extremely high endurance life. Installs easily with standard Instant Tac adhesive.

Low profile of .080" (2,0mm) allows practical installation and compression action in very minimal gap situations. Long, slender finger profile yields very low compression forces and high endurance life. Works very well with "wiping" applications.

Simple snap-in installation. Three sizes fit most applications. Very low compression force and no friction drag when compressed. Excellent for "sliding" applications. Symmetrical design allows bi-directional contact engagement. Very handy for ESD grounding or RFI shielding on:

enclosure doors • enclosure panels • chassis covers • back panels • rack drawers • plug-in assemblies

Available in short lengths cut to size in multiples of "C" dimension. See slot-mount installation guidelines below.

A typical slot-mount shielding application is shown at right on an electric enclosure. Follow the dimensional specifications shown at left and in the chart below for the optimum installation performance.

Note: the "J-slot" length per application in multiples of "C" dimension plus .010" (0,25mm). See chart abolw

Beryllium Copper Finger Strips 3

2007-08-25T23:40:00.000-07:00

For applications requiring a high dynamic range of deflection, very low compression force and an extended service life after repeated compressions. Assures firm grip on mounted surface. Available with optional retaining lance.



			Male rings are formed with the curved contact surfaces on the O.D. For microwave cavities, tuning and shielding applications. Rings are sized in diameters as indicated by forming many of our standard shielding strips. Each male ring style can be formed with a wide range of inside diameters. When ordering, indicate the specific inside diameter to fit your requirement. Female rings are formed with the curved contact surfaces on the I.D. Rings are sized in diameters by forming many of our standard shielding strips. Each female ring style can be formed with a wide range of outside diameters beginning with the minimum O.D. shown in the chart. When ordering, indicate the specific outside diameter to fit your requirement.

Beryllium Copper Finger Strips 2

2007-08-25T23:39:00.000-07:00

his style combines a high dynamic range of deflection, very low compression force and a long service life after repeated compressions. Provides a firm grip on the mounted panel section. Ideal for situations where adhesive attachment is not desired. Simple, quick clip-on assembly.

	"V"style lance - click for Installation Guide

		For certain applications where the direction of contact engagement requires orientation in the opposite direction from standard clip-ons. Grips a wide range of panel thicknesses. Available with or without retaining lances.

	"C"style lance - click for Installation Guide

		Clip-ons with a concentration of contact force at spherical radius contact points located on the end of the spring members.


		A range of sizes which accommodate common clip-on applications.

Beryllium Copper Finger Strips,EMI Products,EMI shielding material 5

2007-08-25T23:37:00.000-07:00

One of the smallest practical clip-on designs available. Very low compression force and virtually no compression set. Perfect for areas where there is very little surface area to grip onto.

	"C"style lance - click for Installation Guide

		The smallest clip-on design in this series. The contact end is folded over to facilitate a smooth engagement with the contact surface during compression. Perfect for areas where there is very little surface area to grip.

	"C"style lance - click for Installation Guide

		A clip-on variation with a flat upper contact member which allows very low compression force throughout deflection range.

	"C"style lance - click for Installation Guide

		The continuous leading edge on this style is designed for situations where snagging of the edge is a concern. Slots facilitate continuous engagement along uneven surfaces. Quick, simple clip-on installation.


		A clip-on style for applications where extremely low force is a must. designed with a minimum of residual stress and highly leveraged spring action. The free end features a folded-under lip which facilitates a low coefficient of friction on most surfaces. Extremely high endurance life. Simply clips into position.

Beryllium Copper Finger Strips,EMI Products,EMI shielding material 4

2007-08-25T23:34:00.000-07:00

For applications where a small dynamic range is required and a clip-on mounting is preferred. Mounts simply by pressing into position.

	"C"style lance - click for Installation Guide

			Very low profile and low compression force. For extremely small gaps where an active dynamic range as small as .07" (1,8mm) may be all that is available. Full electrical contact occurs within a very short range of movement.

	"C"style lance - click for Installation Guide

			Specifically designed for edge mount applications with perpendicular and/or parallel loading. Larger size multipurpose contact mounts over lips and edges. Very low compression forces due to the free-hanging finger end which travels in open space. Gripping lances on the underside engage mounting surface to lock into desired position.

	"C"style lance - click for Installation Guide

		Specifically designed for very small electronic packages where contact surfaces are thin walls and adjoining edges, such as telecom applications. 99-485-06 is excellent for sliding movements in the longitudinal direction. 99-490-06 accepts compression forces in the perpendicular direction by deflecting the spring arms. Gripping lances on the underside of each design engage mounting surface to lock into desired position.

	"C"style lance - click for Installation Guide

Beryllium Copper Finger Strips,EMI Products,EMI shielding material 3

2007-08-25T23:33:00.000-07:00

For areas where a small dynamic range is required, and where the shield in its "compressed state" will not extend beyond its uncompressed dimension. "A." Mounting is simple with standard Instant Tac adhesive. Optional poron rubber Environseal protects against moisture, dust and other contaminants. Also available in continuous length rolls.


			A double row of contacts in one narrow shield strip. Mounts securely with standard Instant Tac adhesive. Optional poron rubber Enviroseal protects against moisture, dust and other contaminants. Also available in continuous length rolls.


			Multipurpose contact strip used where low contact force is required, or for applications which necessitate a minimum of deflection to attain peak shielding effectiveness. Optional poron rubber Enviroseal protects against moisture, dust and other contaminants. Installs simply with Instant Tac adhesive.


			For applications where side mounting is required. See "G" dimension. Mounts securely with Instant Tac adhesive which adheres to the surface perpendicular to the area where compression contact occurs.

Beryllium Copper Finger Strips,EMI Products,EMI shielding material 2

2007-08-25T23:31:00.000-07:00

This series combines high dynamic range, very low compression force and long service life after repeated compressions. Ideal for enclosure cabinet doors. Installs easily with standard Instant Tac adhesive.


		These designs incorporate a "fold-over" extension on the base which protects the upper part of the contact in the relaxed position and as it slides into the compressed position. Installs easily with standard Instant Tac adhesive.


	Specifically designed for large enclosure doors, or where compression of the gasket is achieved by angular engagement of the mating surfaces such as with screen room doors or in joining groups of enclosures. Mounting holes of .142" (3,6mm) diameter on .375" (9,5mm) centers accomodate mechanical fastening with screws or rivets.


	For large deflection applications with built-in location edge, or to simplify mechanical installation of fastener hardware. Holes are provided for hardware assembly. Instant Tac adhesive version is also available.


	Large deflection for wide mounting surfaces such as enclosure doors. Assures long endurance life in continuous wiping motion compressions. Holes are provided for mechanical installation of fastener hardware.

Beryllium Copper Finger Strips,EMI Products,EMI shielding material

2007-08-25T23:28:00.000-07:00

The ideal shielding strip where space is at a premium and high dynamic range is required. Available with optional conductive adhesive.


			This family of shielding contact strips offers a variety of high performance end configurations for shielding, grounding and ESD applications. Optional mounting holes available.


	Used where a concentration of high contact force is needed to assure a strong electrical bond; i.e. in a vibrating environment. Available with optional conductive adhesive.


		This multipurpose style contains a spherical radius contact point which provides a concentration of contact force to assure a strong electrical bond when deflected. Optional mounting holes are available.

Beryllium copper gaskets from TBA ECP now ROHS-compliant

2007-08-25T22:35:00.000-07:00

EMI shielding specialist, TBA Electro Conductive Products (ECP)'s beryllium copper fingerstock gaskets for EMI shielding now meet the Restriction of Hazardous Substances Directive 2002/95/EC (RoHS Directive).

The Directive banned the use of certain substances in new products from July 2006, specifically lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE).

TBA ECP's range of BeCu gaskets contains none of the banned substances and fully meets RoHS directive requirements. TBA ECP's beryllium copper fingerstock is available in different styles including clip-on, stick-on, snap-on, hook-on and special mounting types plus low profile and connectors gaskets all delivering high-shielding effectiveness.

Different plating options are also available including clean and bright, gold, silver, bright tin, bright nickel, zinc/clear chromate and electroless nickel among others. Beryllium copper shielding strips offer good spring qualities and long life.

Other important characteristics of BeCu gaskets include low closing forces and high attenuation exceeding 100dB for many styles. Complementing its range of beryllium copper shielding strips is TBA ECP's steel version of low-profile and pressure-sensitive mounting gaskets.

This range of gaskets extends the choice of materials available to design engineers and provide hard-wearing and long-lasting EMI/RFI shielding in various applications.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents. All products supplied by TBA ECP comply with RoHS directive 2002/95/EC.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Shielding vents protect apertures against EMI/RFI

2007-08-25T22:28:00.000-07:00

Designed as simple screw on panels, aluminium shielding vents are have several styles of frame and allow an easy solution for protecting airflow or lighting apertures

Shielding specialist, TBA Electro Conductive Products (ECP) now offers over 80 standard sizes in its range of shielding vents that provide effective shielding against electromagnetic and radio frequency interference (EMI/RFI). Designed as simple screw on panels, ECP 8000 series aluminium shielding vents are available with several styles of frame and allow designers and OEMs an easy solution for protecting airflow or lighting apertures.According to TBA ECP, the standard sizes are pre-tooled with either drilled holes or threaded inserts provided for fixing, enabling users to avoid the cost of special tooling that would be needed for a custom design.

With 80-plus standard versions, users will be able to closely match their requirements by designing their aperture to fit the shielded vents available rather than designing a custom vent to fit the aperture.

Standard construction of all vents comprises an aluminium honeycomb in two 6.3mm thick layers with a 3mm cell diameter, laminated in a cross cell construction and contained in a peripheral extruded aluminium frame.

Optional frame styles are flat or with groove depending on type of seal required.

A variety of finishes is available encompassing chromate, tin and nickel for standard honeycomb versions, providing attenuation levels from 60dB typical for chromate up to 115dB typical for nickel (1GHz plane wave).

A chromate finish with cross cell honeycomb version provides 90dB typical attenuation (1GHz plane wave).

Fan apertures can be shielded with the ECP 8200 series standard shielded vents where enclosures require EMI shielding combined with maximum airflow.

These vents feature a 6.4mm single honeycomb layer with 1.6 or 3mm diameter cells held in pre-drilled rigid aluminium frames with a conductive chromate finish.

Five sizes are available to match popular standard fan sizes and these vents can be supplied with optional dust screens if required.

Fan vents are also supplied fitted with the company's ECP 625 beryllium copper gaskets as standard.

ECP 8300 series Quiet Vents are available in no fewer than 66 sizes and deliver an excellent low cost solution to the demanding cooling requirements of modern electronic equipment.

The honeycomb panels feature rigid, extruded aluminium frames with optional captive fasteners or through-holes.

Quiet Vents are supplied as standard with composite knitted gaskets that combine a neoprene gasket with wire mesh to provide efficient EMI/RFI shielding between the frame and mounting surface.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Beryllium copper gaskets are RoHS compliant

2007-08-25T22:26:00.000-07:00

TBA Electro Conductive Products' range of Beryllium Copper fingerstock gaskets for EMI shielding meets the Restriction of Hazardous Substances Directive 2002/95/EC (RoHS Directive)

EMI shielding specialist, TBA Electro Conductive Products (ECP) has announced that its range of Beryllium Copper fingerstock gaskets for EMI shielding meets the Restriction of hazardous substances Directive 2002/95/EC (RoHS Directive). The directive bans the use of certain substances in new products from July 2006, specifically Lead, Mercury, Cadmium, Hexavalent Chromium, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE).
TBA ECP's extensive range of BeCu gaskets contains none of the banned substances and fully meets RoHS directive requirements.

TBA ECP's beryllium copper fingerstock is available in a wide range of styles including clip-on, stick-on, snap-on, hook-on and special mounting types plus low profile and connectors gaskets all delivering high shielding effectiveness.

A wide range of plating options is available including clean and bright, gold, silver, bright tin, bright nickel, zinc/clear chromate and electroless nickel among others.

Beryllium copper shielding strips offer excellent spring qualities and long life.

Other important characteristics include low closing forces and high attenuation exceeding 100dB for many styles.

Complementing its range of beryllium copper shielding strips, TBA ECP also supplies stainless steel versions of its low-profile and pressure sensitive mounting gaskets.

These extend the choice of materials available to design engineers and provide hard-wearing and long-lasting EMI/RFI shielding in a wide range of applications.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

All products supplied by TBA ECP comply with RoHS Directive 2002/95/EC.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Beryllium copper EMI/RFI shielding strips

2007-08-25T22:24:00.000-07:00

EMI shielding specialist, TBA Electro Conductive Products (ECP) has introduced new small size beryllium copper EMI/RFI shielding strips

EMI shielding specialist, TBA Electro Conductive Products (ECP) has introduced new small size beryllium copper EMI/RFI shielding strips that are designed for use in applications where very narrow gaps are encountered. The new ECP620 gaskets are ideal for bidirectional applications including sub-rack assemblies, plug-in units, front panels, backplanes and other shielding and grounding enclosure applications requiring high shielding effectiveness for narrow gaps.ECP620 small size gaskets feature an uncompressed (free) height of just 2mm and require compression force of 16 to 50kg/m for 25 to 50% compression respectively (1.5 to 1mm).

The gaskets are manufactured from 0.5mm thick beryllium copper and are supplied in 406mm long strips.

Fingers are 1.06mm wide on 1.52mm pitch and strip width is 5.33mm uncompressed.

TBA ECP's new ECP620 small size gaskets feature pressure sensitive (stick-on) mounting and soft no-snag fingers.

They also meet the requirements of the RoHS and WEEE directives.

Like all TBA ECP's beryllium copper gaskets, the new small size designs are available in a wide range of plating options including clean and bright (unsolderable) as standard, solderable unplated, gold, silver, tin lead, bright tin, bright nickel, zinc/clear chromate and electroless nickel among others.

Beryllium copper shielding strips offer excellent spring qualities and long life.

Other important characteristics include low closing forces and high attenuation exceeding 100dB for many styles.

Complementing its range of beryllium copper shielding strips, TBA ECP also supplies stainless steel versions of its low-profile and pressure sensitive mounting gaskets.

These extend the choice of materials available to design engineers and provide hard-wearing and long-lasting EMI/RFI shielding in a wide range of applications.

TBA ECP's comprehensive range of standard beryllium copper fingerstock delivers cost effective EMI/RFI shielding with high attenuation.

Custom shielding is also available for board-level shielding and connector gaskets.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI shielding material：EMI gaskets shielding、EMI gasket、fabric tape、aluminum foil tape、copper foil tape

2007-08-25T22:21:00.000-07:00

EMI gaskets shielding
EMI gaskets shieldingEMI gaskets shielding are used to provide an electrically conductive seal for electronic equipment openings and housing covers to prevent or restrict electromagnetic interference. EMI Gaskets have good performance after strictly testing. It is an efficient way using our gaskets and fabric tapes into any electronics to avoid the electromagnetic interference.

Fabric tape
fabric tapeFabric tape/Electrically-Conductive Adhesive Transfer Tapes are designed to help you save time in a variety of specialized electronics assembly operations – from attaching EMI shields and gaskets to grounding and bonding flexible circuits and PCBs – while improving the performance and reliability of your finished products.

Aluminum foil tape
aluminum foil tape Aluminum Foil Tapes are an economical EMI shielding solution for a variety of commercial uses. The tapes are available in copper, aluminum, or tinned copper foil backed with QuanYi’s highly conductive pressure-sensitive adhesive. Standard length rolls and die-cut custom shapes can be ordered.

Copper foil tape
copper foil tape Copper Foil Tapes are an economical EMI shielding solution for a variety of commercial uses. The tapes are available in copper, aluminum, or tinned copper foil backed with our highly conductive pressure-sensitive adhesive. Standard length rolls and die-cut custom shapes can be ordered. Copper foil tapes are recommended for electro-static shielding, cable wrapping, and stained glass work.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI Introduction

2007-08-25T22:20:00.000-07:00

A knowledge of the fundamental concepts of EMI will aid the designer in selecting the gasket inherently best suited to a specific design.
To choose a most effective EMI shielding gasket for products such as telecommunications equipment, handset device, laptop PC, PC related, automotive and medical electronics, often you have three options: conductive fabric over foam (Aluminum foil over foam), conductive elastomer, or beryllium-copper (BeCu) strips (fingerstock). Depending on the product’s needs, these solutions provide varying EMI protection, intricacy of forms, and environmental protection.

As designing EMI shielding into products, some factors must be considered:

* Attenuation level. Most commercial applications typically require 60 to 100 dB but can go as high as 120 dB.
1. EMI Gasket of Conductive fabric over foam -Typical EMI shielding effectiveness is around 80 to 115 dB.( 10kHz to 10GHz frequency range)
2. EMI Gasket of Conductive elastomers - Typical EMI shielding effectiveness is around 40 to 120 dB.( 10kHz to 10GHz frequency range)
3. EMI Gasket of BeCu Strips (Fingerstock) - Typical EMI shielding effectiveness is around 75 to 120 dB.( 10kHz to 10GHz frequency range)
* Compression. Most commercial applications require low closure force. Compression force has the greatest effect on conductive elastomer shielding characteristics. Since they can be loaded with relatively low- to high-conductivity filler materials, conductive elastomers supply the widest range of shielding effectiveness.
BeCu strips and conductive fabric-over-foam gaskets are not affected as much by compression forces. As a result, they offer a narrower range of shielding capabilities.
* Mechanical durability.
* Form, referring to the complexity of the form or pattern in which the gasket fits.
* Galvanic compatibility between the gasketing conductive material and substrate metal. This avoids creating a galvanic cell, which can lead to corrosion.
* Environmental sealing from water, dust, and similar external substances.

Other selection considerations include cost, service life (cycles, actuations), tolerances, and mounting methods such as fastener types and adhesives.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI Theory

2007-08-25T22:18:00.000-07:00

Electronic devices operating normally in their intended environment, without conducting or radiating excessive amounts of electromagnetic energy, or being susceptible to such energy from internal or external sources, are in the state of electromagnetic
compatibility, or EMC. Electromagnetic interference, EMI, is radiated or conducted energy that adversely affects circuit performance, and thus disrupts a device’s EMC. Many types of electronic circuits radiate or are susceptible to EMI and must be shielded to ensure proper performance. Establishing basic electromagnetic compatibility in any electronic device generally requires two distinct approaches. The first approach is to reduce EMI generated from internal sources. It is the best accomplished by designing an electronic circuit or device so that it inherently generates less EMI. Residual EMI may then be suppressed or contained within the enclosure by appropriate filtering and shielding methods. Filtering cables at the point where they enter or leave the enclosure will reduce conducted emissions. Radiated EMI may be eliminated or reduced by the use of shielded enclosures and shielding materials. The second method for establishing EMC in a device is to improve its immunity (or reduce its susceptibility) to interference from external EMI sources.

Here you will find everything you need, to solve all your EMI shielding issues. Products including: 1. EMI Shielding gasket (Conductive fabric over foam, Conductive elastomer, BeCu Strips), 2. EMI shielding/conductive tape (Copper foil tape, Aluminum foil tape, conductive fabric tape), 3. EMI shielding adhesive (Conductive adhesive). Our technical engineers will work together with you from the design phase through final production

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI shielding gasket -- Conductive Fabric Over Foam

2007-08-25T22:16:00.000-07:00

Conductive fabric over foam makes sense where no environmental seal, complex profile, or demanding mechanical durability is needed. It can be the lowest-cost option.The covering can consist of nylon thread coated with conductive metals woven into a fabric and wrapped over a soft urethane foam. Alternatively,a woven fabric may be metallized with nickel-copper or other metal coating, then wrapped around the
foam core.
Flexible, conformable fabric over foam maintains close contact with surfaces with minimal compression for low-closure-force applications. It provides snug contact over irregular surfaces and around bends and corners, making it good for electronic enclosures such as doors and access panels.
Less demanding EMI applications include grounding contact pads in cell phones and laptop computers. Fabric-over-foam gaskets also can shield the input/output backplane of laptops and PCs.
The manufacturing process limits it to relatively simple cross-sectional profiles such as squares, rectangles, and D-shapes. When a more complex profile is necessary, fabric over foam may not be the best solution.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI shielding gasket --Conductive Elastomers

2007-08-25T22:15:00.000-07:00

For more demanding shielding applications, conductive silicone elastomers provide a wide range of attenuation capabilities plus environmental and moisture sealing. The metal-filled elastomers can be extruded or molded into a wide range of form-fitting shapes and cross sections.
For very small cross sections, a formed-in-place silicone-based silver-copper-filled or nickel-graphite-filled conductive
elastomer is dispensed robotically.The robot can deposit the elastomer on a surface as narrow as 0.025 to 0.030 in.
Conductive elastomers are filled with a range of materials, from silver (highest conductivity) to carbon. Carbon-filled elastomers, having the lowest conductivity and cost, serve applications requiring low shielding levels. Other filler materials include nickel-coated graphite, silver-plated glass, silver-plated copper, and silver-plated aluminum. Nickel-graphite is the most popular for commercial applications because of good cost/performance attributes.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI shielding gasket -- BeCu Strips also called fingerstock

2007-08-25T22:14:00.000-07:00

When you need mechanical durability, such as frequent direct compression actuations or shearing forces, BeCu strips make the best choice. BeCu fingerstock withstands lateral shearing forces as well as perpendicular forces, where other shielding materials are best suited for perpendicular, direct-compression applications.
Thin BeCu strips, available in many profiles, provide shielding
or grounding but do not supply an environmental seal. BeCu fingerstock can be plated with many different metal types, offering broad galvanic compatibility with substrate metals.
The use of stainless steel is progressing slowly because of the expense of developing new tooling. Presently, only a relatively small number of profiles are offered in stainless steel. In some cases, customers are sharing the expense of developing tooling for specific applications with the EMI gasket manufacturer.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Beryllium copper EMI/RFI shielding strips offered

2007-08-25T22:10:00.000-07:00

EMI shielding specialist has introduced three new beryllium copper EMI/RFI shielding strips for bidirectional applications, offering enhanced strength with improved flexibility

EMI shielding specialist, TBA Electro Conductive Products (ECP) has introduced three new beryllium copper EMI/RFI shielding strips offering enhanced strength with improved flexibility. The new Alternate Slot Gaskets are ideal for bidirectional applications including sub-rack assemblies, plug-in units, front panels, backplanes and other shielding and grounding enclosure applications.
Extending across the contact radius of these new symmetrical profile gaskets are slots alternating from one side to the other.

This provides increased strength while maintaining the gasket's flexibility.

The gaskets require only a low closing force while snap-mounting on a track or direct to metalwork provides a secure mechanical assembly.

The new Alternate Slot Gaskets also meet the requirements of the RoHS and WEEE directives.

Like all TBA ECP's beryllium copper gaskets, the new alternate slot designs are available in a wide range of plating options including clean and bright (unsolderable) as standard, solderable unplated, gold, silver, tin lead, bright tin, bright nickel, zinc/clear chromate and electroless nickel among others.

Beryllium copper shielding strips offer excellent spring qualities and long life.

Other important characteristics include low closing forces and high attenuation exceeding 100dB for many styles.

Complementing its range of beryllium copper shielding strips, TBA ECP also supplies stainless steel versions of its low-profile and pressure sensitive mounting gaskets.

These extend the choice of materials available to design engineers and provide hard-wearing and long-lasting EMI/RFI shielding in a wide range of applications.

TBA ECP's comprehensive range of standard beryllium copper fingerstock delivers cost effective EMI/RFI shielding with high attenuation.

Custom shielding is also available for board-level shielding and connector gaskets.

TBA Electro Conductive Products is a specialist manufacturer of high quality electro static protection (ESP) and electro magnetic interference (EMI) shielding products.

The EMI shielding range includes an extensive portfolio of gaskets and gasketing materials, metal foil tapes, shielded windows and mesh products, vent panels and shielded fan vents.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Finger Stock Gaskets -shielding strips

2007-08-25T21:57:00.000-07:00

shielding strips are designed for a wide variety of application requirements, and can be supplied cut to length or full size in any of the following mounting configurations. Consult our engineering department for special modifications to suit your requirements.

If you know the Shielding Strip Part Number you are looking for, see the http://www.cgccn.com

Clip-on Mounting

Clip-on Mounting provides a reliable mechanical installation when there is an accessible mounting flange. Various flange thicknesses can be accommodated, and lances can be incorporated to enhance the holding force to the flange.

Certain Clip-on strips have lance locations other than shown above. These dimensions are specified on the product drawings.

Extrusion Mounting

Tech-Etch "S" Series symmetrical shielding strips can be installed on extrusions specially designed to provide a useful free height. The drawing below illustrates guidelines for designing the extrusion.

Dimension "A" less allowance for initial contact is the compression range. Dimension "B" should be approximately .020" less than the open dimension of the shielding strip.

Stick-on Mounting

Pressure Sensitive Mounting provides double-sided pressure sensitive transfer tape for a fast, reliable installation. 3M F9469PC transfer tape or equivalent may be used at ambient temperatures from -67°F to 300°F. Apply only on a clean, oil-free surface, and allow a 24-hour cure time. Consult the factory for other adhesives and extended liner options.

STICK-ON GASKET

HOOK & STICK-ON GASKET

Hook and stick fingers are ideal for flange mounting applications requiring low compression forces and small gap shielding.

SPIDER gaskets, featuring a continuous, smooth web of fingers on each side, are available in both Stick-on and Hook & Stick-on mounting configurations.

Non-conductive .010" thick adhesive may be specified for improved adhesion on rough surfaces. Conductive adhesives and extended liners are also available. Consult the factory for these options.

Snap-on Mounting

Snap-on Slot and Edge Mount Symmetrical fingers using single or double fingers are very economical for applications such as sliding drawers, doors, rack-mounted assemblies and covers. They perform well in bi-directional applications and the snap-on capability makes them easy to install.

When continuous shielding is required the V Series or VE Series utilizing the same snap on mounting feature can be used. Available repeating finger patterns for the V and VE Series are shown here*.

*Consult Tech-Etch for the availability of other patterns.

Special Mounting

Special Mounting shielding strips can be installed by spot welding or soldering. Rivets can be used for the 375A and 500A profiles and conductive pressure sensitive adhesives are available. Consult the factory.

Track / Extrusion Mounting

Track or extrusion mounted symmetrical fingers provide a durable shielding solution for applications requiring bi-directional motion, such as drawers and plug-in modules.

TR Series Track is typically installed with plastic rivets, but is also available with pressure sensitive tape for adhesive mounting. The track can be installed prior to the assembly of the finger strips to avoid damaging the fingers. See below. Photos at illustrate several methods of retention, including "T" Retaining Caps. Retention stops can also be incorporated in the sheet metal.

Plastic Rivets

Plastic rivets can be used to install Track and as rivet stops to retain shielding on a track as shown below and in the photo on the right. When used on a flange, the hole diameter for the rivet should be .125". Two rivets are available: PR45 and PR60.

"T" Retaining Caps

"T" Retaining Caps can also be used to hold shielding on the Track.

Retainer Options

Track the in left photo shows two shielding retainer options: Plastic Rivet Stop on the left and "T" Retainer on the right. Right photo shows the same track with shielding snapped into place.

Track - Pressure Sensitive Transer Tape Mounting

Perhaps the easiest track mounting option is with double sided pressure sensitive transfer tape. Simply apply on a clean, oil-free surface, and allow a 24-hour cure time.

OMNI Track

Omni Track is designed to provide a track type mounting for single finger applications. It is typically supplied with pressure sensitive tape for adhesive mounting. Holes are available for rivet mounting.

Econo Track

Econo Track has self-fastening clips and optional retention to provide the most economical method of mounting Symmetrical Fingers. Installation requires the fingers to be slid on from either end. Track and strip are then pressed into .12" diameter flange mounting holes. Flange thickness varies from .02" to .07". At right Econo Track is shown separately next to shielding strip and then combined.

Composite bonding material of beryllium, copper alloy and stainless steel and composite bonding method

2007-08-25T09:16:00.000-07:00

According to the present invention, an insert material is laid between metal beryllium and copper alloy, wherein the insert material has the minimum, solidus temperature of not lower than 870.degree. C. to the metal beryllium and copper alloy, respectively, and a single diffusion bonding process is performed under the condition that the temperature is not lower than 850.degree. C. and less than the minimum solidus temperature, and the pressure is 20 to 30O MPa, so that the metal beryllium, copper alloy and stainless steel can be effectively bonded without deterioration of corrosion resistance for sensitizing of the stainless steelRecently, the industry became interested in developing composite bonding technology for bonding various materials having different properties to each other to form a composite body.

Such bonding materials include metal beryllium, which is used for various purposes, such as transmission windows for X-ray, equipment due to excellent X-ray transmissibility and various applications related to nuclear equipment.

For applying to X-ray windows, it has been conventional practice to bond metal beryllium to a flange or like structural body made of stainless steel by brazing or diffusion bonding. However, stainless steel to which metal beryllium has been directly bonded suffers from a general problem of insufficient thermal conductivity.

Therefore, in order to improve thermal conductivity, a bonding process has been developed in which the copper alloy is bonded to a structural body of stainless steel in advance, and the metal beryllium is then bonded to the bonded body of copper alloy and stainless steel.

However, the above-mentioned bonding process requires that, after the stainless steel and copper alloy have been bonded to each other, an additional step is required to bond the metal beryllium to the bonded body of copper alloy and stainless steel by brazing or diffusion bonding, so that there remain problems that not only the bonding treatment is complicated, but also it is costly to perform.

Also, it has been a general practice that the brazing or diffusion bonding of metal beryllium be performed at a temperature within a range of 650 to 800.degree. C. This temperature range overlaps with the sensitizing temperature of the stainless steel. However, when brazing or diffusion bonding is performed in such a temperature range the corrosion resistance of the stainless steel is significantly diminished.

SUMMARY OF THE INVENTION

The invention serves to solve the above-mentioned problems. It is an object of the invention to provide a composite bonded body in which metal beryllium, copper alloy and stainless steel are effectively bonded to each other without the problem relating to the sensitizing of the stainless steel, as well as an advantageous bonding method therefor.

The details of the development which resulted in the invention will be described below.

As mentioned above, the conventional method for bonding metal beryllium, copper alloy and stainless steel to each other is to bond a copper alloy to a structural body made of stainless steel in advance, and then further bond the metal beryllium to the bonded body of copper alloy and stainless steel.

The reason for this procedure is that is because a satisfactory bonded body can not be obtained when metal beryllium, copper alloy and stainless steel are to be bonded to each other simultaneously. More specifically, the preferable bonding temperature of copper alloy and stainless steel is a relatively high temperature of 850 to 1050.degree. C., while the preferable bonding temperature of metal beryllium and copper alloy is a relatively low temperature of not higher than 800.degree. C. Therefore, when the bonding is performed in the former case at relatively high temperatures beryllium and copper alloy react with each other to form a eutectic alloy having a low melting point causing the bonding surface to melt. On the other hand, when the bonding is performed in the latter case at low temperatures a sufficient bond between the copper alloy and the stainless steel is not achieved.

The inventors conducted thorough investigations for the purpose of solving the above-mentioned ambivalent problems, and arrived at the novel recognition that the above mentioned object of the invention can be advantageously achieved by interposing an insert material between the metal beryllium and copper alloy, which presents the formation of an eutectic alloy of a low melting temperature even when reacted with metal beryllium or stainless steel.

The invention is based on the above-mentioned recognition, and featured by the following constitutions.

1 A composite bonded body of metal beryllium, copper alloy and stainless steel, all of which are joined by a single diffusion bonding process with the stainless steel as a substrate, the copper alloy bonded to the surface of stainless steel, substrate and the metal beryllium bonded to the outer surface of said copper alloy.

2. A composite bonding method for bonding metal beryllium, copper alloy and stainless steel, all of which are sequentially depoisted on the outer surface and bonded to each other in this order, wherein an insert material is interposed between the metal beryllium and copper alloy, layers said insert material having the minimum solidus temperature of not lower than 870.degree. C. relative to the metal beryllium and copper alloy, respectively, and a single diffusion bonding process is performed at a temperature not lower than 850.degree. C. and less than the minimum solidus temperature, and at a pressure at 20 to 300 MPa, so that the metal beryllium, copper alloy and stainless steel are simultaneously bonded to each other.

3. A composite bonding method for bonding metal beryllium, copper alloy and stainless steel according to paragraph 2 above, wherein said insert material interposed between the metal beryllium and copper alloy is niobium metal.

4. A composite bonding method for bonding metal beryllium, copper alloy and stainless steel according to paragraph 2 above, wherein said insert material interposed between the metal beryllium and copper alloy is molybdenum metal.

5. A composite bonding method of metal beryllium, copper alloy and stainless steel according to paragraph 2 above, wherein said insert material interposed between the metal beryllium and copper alloy is titanium metal.

6. A composite bonding method of metal beryllium, copper alloy and stainless steel according to paragraph 2, 3, 4 or 5 above, wherein a nickel intermediate layer is formed between the stainless steel and copper alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of X-ray windows;

FIG. 2 is a perspective view of a glass coating HIP bonding method; and

FIG. 3 is an explanatory view of showing the bonding between metal beryllium, copper alloy and stainless steel according to one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention will be described in further detail below.

There is schematically shown in FIG. 1 an X-ray window which has been formed by the bonding process described herein. In FIG. 1, reference numeral 1 designates a beryllium foil, 2 a copper alloy, and 3 a structural body made of stainless steel.

In the arrangement shown in FIG. 1, stainless steel is used as the structural body for providing a predetermined strength and corrosion resistance to the cooling water. As such stainless steel, there may be advantageously used austenitic stainless steel such as SUS 304, SUS 316, SUS 316L, SUS 316LN, or ferritic stainless steel such as SUS 430, SUS 430LX, SUS 434, SUS 436.

Also, the copper alloy used as a heat dissipation material is preferably comprised of oxygen free copper (OFC), alumina dispersion-strengthened copper (DSCu), beryllium copper (C17510, C17500, etc.), chromium-zirconium copper or the like.

According to the present invention, when the stainless steel, copper alloy and metal beryllium are bonded to each other simultaneously, the preferable bonding process employed is a so-called glass-coated HIP (hot isostatic press) bonding wherein, as shown in FIG. 2, the bonded body as a whole is covered with glass powder 4 and then subjected to heating under pressure.

In general, when stainless steel and copper alloy are bonded by the HIP process, the preferred heating temperature is within a range of about 850 to 1050.degree. C. However, if the metal beryllium, copper alloy and stainless steel are simultaneously bonded to each other under such a temperatures, an eutectic alloy having a low melting point is formed between the copper alloy and metal beryllium preventing the formation of a strong bond.

It is desirable to form interface bonds capable of withstanding 70 MPa of pressure or preferably not less than 100 MPa of pressure.

On the other hand, according to the invention, niobium, molybdenum, titanium or the like metal is interposed as an insert material between the metal beryllium and copper alloy, so as to advantageously avoid the above-mentioned disadvantages.

This is due to the fact that when, for example, a niobium metal is interposed between the metal beryllium and stainless steel, a eutectic alloy is formed at the interface of the niobium and beryllium having a melting point of 1440.degree. C. which is not only higher than the melting point (866.degree. C.) of the eutectic alloy formed between beryllium and copper alloy, but also higher than the melting point (1289.degree. C.) of the metal beryllium itself. Also, while the minimum solidus temperature of the alloy formed from the niobium metal and copper alloy is not always definite, it is well higher than the melting point of the alloy made from the metal beryllium and copper alloy, so that particular problems do not occur even when the three materials are simultaneously bonded to each other by HIP bonding at temperatures at or below 850.degree. C.

Similarly, when molybdenum metal is interposed between metal beryllium and stainless steel, the eutectic alloy formed between the molybdenum and beryllium has a melting point of 1827.degree. C. , and the minimum solidus temperature of alloy formed from the molybdenum metal and copper alloy alone is higher than melting point of the copper alloy, so that particular problems do not occur even when the three materials are simultaneously bonded to each other by HIP bonding at temperatures at or below 850.degree. C.

Also, when a titanium metal is interposed between the metal beryllium and stainless steel, the minimum solidus temperature of the alloy formed from the titanium metal and metal beryllium is 980.degree. C., and the minimum solidus temperature of the alloy formed from the titanium metal and copper alloy is 885.degree. C., so that particular problems do not occur even when the three materials are simultaneously bonded to each other by HIP bonding at a temperature greater 850.degree. C.

Therefore, according to the invention, when metal beryllium, copper alloy and stainless steel are bonded to each other by HIP bonding, an insert material is interposed between the metal beryllium and stainless steel, which comprises niobium, molybdenum, titanium or the like metal capable of forming an alloy with the metal beryllium or copper alloy, having the minimum solidus temperature of not lower than 870.degree. C.

According to the invention, it is preferable that the thickness of the insert material be within a range of 0.5 to 600 .mu.m. When the thickness of the insert metal is less than 0.5 .mu.m, as a diffusion barrier cannot be achieved. When when the thickness of the insert metal exceeds 600 .mu.m, the effect of beryllium is maximized besides that an excessive thickness is disadvantageous from economical viewpoint.

The method of forming the insert material is not limited to a specific process. The available methods, include, but are not limited to, physcially inserting a metal foil between the substrate layers, a PVD processing such as vapor deposition, sputtering, magnetron sputtering, ion plating or the like, or an ordinary plating process.

By interposing niobium, molybdenum, titanium or like insert material between the metal beryllium and copper alloy, in the manner described above, it is possible to perform bonding by a HIP process under a temperature condition of not less than 850.degree. C., which is suitable for bonding the metal beryllium and copper alloy. However, when the bonding temperature is higher than the minimum solidus temperature of the alloy formed between the insert material and beryllium or between the insert material and copper alloy, the bonding interface melts. Therefore, according to the invention, the upper limit of the bonding temperature is decreased below the minimum solidus temperature.

Also, it is necessary that the pressure for the HIP bonding process be within a range of 20 to 300 MPa. This is due to the fact that, when the pressure is lower than 20 MPa, satisfactory diffusion bonding is not achieved, and when the pressure is higher than 300 MPa, the benifits of increased pressure are maximized and the apparatus becomes costly which is not advantageous from economical viewpoint.

In addition, according to the invention, it is advantageous to form a nickel intermediate layer between the stainless steel and copper alloy. This is due to the fact that, when such a nickel intermediate layer is present, the stainless steel and copper alloy can be bonded to each other not only easily and at a relatively low temperature, but also in such a manner as to improve the bond strength.

For example, when the stainless steel and alumina dispersion strengthened copper (DSCu) are directly bonded to each other, the bond is strong enough to withstand forces within a range of 130 to 180 MPa. In contrast, when a nickel intermediate layer is formed between the stainless steel and alumina dispersion strengthened copper, it is possible to achieve a bond strengths of at least 250 MPa and higher.

The process of forming intermediate layer is similar to the above-mentioned process of forming the insert material, and the preferable thickness of the intermediate layer is within a range of 1 to 50,.mu.m.

DESCRIPTION OF THE PREFERRED EMBODIMENT

EXAMPLE 1

In oxygen free copper (OFC) was used as a component of the copper alloy, and SUS 316 was used as stainless steel. Then, a metal beryllium, the oxygen free copper and SUS 316 were joined as shown in FIG. 3. In this instance, an insert material 5 was interposed between the metal beryllium and the oxygen free copper in various methods as shown in Table 1. Also, for some specimens shown in Table 1, a nickel layer was interposed between the oxygen free copper and SUS 316.

Each joined body was placed in a stainless steel casing with a thickness of 2 mm, and the casing was sealed by TIG welding after establishing a vacuum within the casing.

In the next place, these joined bodies were bonded by HIP process under the conditions shown in Table 1, to form composite bonded bodies.

Then, shearing test samples as shown by broken lines A and B in FIG. 3 were cut off from the so-obtained composite bonded bodies, and subjected to simple shear test.

Also, corrosion resistance test pieces were cut off from the SUS 316 part of the composite bonded bodies, and were subjected to 65% nitric acid test in conformity with JIS G 573.

The results of the above-mentioned tests are also shown in Table 1.

Also, for the purpose of comparison, Table 1 further shows the results of tests with respect to composite bonding performed without interposing an insert materials.

TABLE 1
Presence and Method of
Insert Method of thickness of forming HIP
BE/Cu Cu/stainless
material forming nickel inter- nickel temperature, HIP
interface steel interface Corrosion
and thick- insert mediate layer intermediate time
pressure shear strength shear strength speed
No. ness (.mu.m) material (.mu.m) layer (.degree. C.
.times. h) (MPa) (MPa) (MPa) (g/m.sup.2 .multidot. h)
Note
1 Nb (50 .mu.m) foil none -- 900 .times. 2 140
130 100 <0.1 Inventive
inserted
Example
2 Nb (10 .mu.m) sputtering none -- 1050 .times. 2 140
140 180 <0.1 Inventive
Example
3 Mo (5 .mu.m) sputtering none -- 1000 .times. 2 100
110 170 <0.1 Inventive
Example
4 Nb (2 .mu.m) vapor presence (5 .mu.m) plating 950 .times. 2
150 130 175 <0.1 Inventive
deposition
Example
5 Ti (10 .mu.m) vapor presence (5 .mu.m) plating 850 .times. 4
140 120 170 0.1 Inventive
deposition
Example
6 Nb (10 .mu.m) ion plating presence (2 .mu.m) plating 950 .times.
2 50 100 180 <0.1 Inventive
Example
7 Mo (10 .mu.m) vapor presence (10 .mu.m) plating 900 .times.
2 100 90 175 <0.1 Inventive
deposition
Example
8 none -- none -- 880 .times. 140 Be/Cu
interface was melted, separation Comparative
took place at the bonded part Example
9 none -- non -- 700 .times. 2 140 130
60 1.8 Comparative
Example
10 none -- none -- 800 .times. 2 140 120
80 1.2 Comparative
Example

As can be appreciated from Table 1 above, in the case of specimens according to the invention (Nos. 1 to 7), which were prepared by interposing an appropriate insert material between the metal beryllium and copper alloy, and performing HIP process at a temperature of not lower than 850.degree. C., it is possible to achieve a satisfactory shear strength at the Be/OFC interface and OFC/SUS 316 interface, as well as an excellent corrosion resistance. Particularly, the specimens formed by interposing a Ni intermediate layer between OFC/SUS 316 exhibit a further improvement in terms of the interface shear strength.

On the contrary, when HIP bonding was performed at a temperature greater than 850.degree. C. without interposing an insert material (No. 8), the Be/OFC interface melted during the bonding and separation took place at the bond interface.

In this context, the specimens labeled No. 9 and No. 10, which were prepared by performing HIP bonding at a temperature of not higher than 800.degree. C., did not suffer from problems related to the bonding strength, though it was observed that a marked deterioration of the corrosion resistance took place due to the overlap of the treatment temperature with the sensitization temperature of the stainless steel.

EXAMPLE 2

In Example 2, alumina dispersion-strengthened copper (DSCu) was used as a component of the copper alloy, and SUS 316LN stainless steel was used, to form composite bonded bodies under the condition shown in Table 2, and in the manner similar to the method employed to form the previously described embodiment.

The results of shear test and 65% nitric acid test performed with respect to the so-obtained bonded bodies are shown in Table 2.

For the purpose of comparison, Table 2 further shows the results of tests performed with respect to the composite bonding without interposing an insert material between the copper alloy and stainless steel layers.

TABLE 2
Presence and Method of
Insert Method of thickness of forming HIP
BE/Cu Cu/stainless
material forming nickel inter- nickel temperature, HIP
interface steel interface Corrosion
and thick- insert mediate layer intermediate time
pressure shear strength shear strength speed
No. ness (.mu.m) material (.mu.m) layer (.degree. C.
.times. h) (MPa) (MPa) (MPa) (g/m.sup.2 .multidot. h)
Note
11 Nb (50 .mu.m) foil none -- 900 .times. 2 140
140 180 <0.1 Inventive
inserted
Example
12 Nb (10 .mu.m) sputtering none -- 1050 .times. 2 140
150 300 <0.1 Inventive
Example
13 Mo (5 .mu.m) sputtering none -- 1000 .times. 2 100
120 280 <0.1 Inventive
Example
14 Nb (2 .mu.m) vapor presence (5 .mu.m) plating 950 .times. 2
150 155 280 <0.1 Inventive
deposition
Example
15 Ti (10 .mu.m) vapor presence (5 .mu.m) plating 850 .times. 4
140 120 260 <0.1 Inventive
deposition
Example
16 Nb (10 .mu.m) ion plating presence (2 .mu.m) plating 950 .times.
2 50 100 285 <0.1 Inventive
Example
17 Mo (10 .mu.m) vapor presence(10 .mu.m) plating 900 .times. 2
100 95 275 <0.1 Inventive
deposition
Example
18 none -- none -- 880 .times. 140 Be/Cu
interface was melted, separation Comparative
took place at the bonded part Example
19 none -- non -- 700 .times. 2 140
60 1.9 Comparative
Example
20 none -- none -- 800 .times. 2 140
100 1.3 Comparative
Example

According to the present invention, it is possible simultaneously to perform a composite bonding of metal beryllium, copper alloy and stainless steel, by a single bonding treatment, without deterioration of corrosion resistance for sensitizing of the stainless steel. The bonding treatment is easy to perform, and a significant reduction in terms of production cost can be achieved

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

Look forward to hearing from you soon.

Best regards,

Sam Xu
Contact me:
MSN: xubiao_1996@hotmail.com
GMAIL: samjiefu@gmail.com
SKPYE:jiefu1996

Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Production of beryllium-copper alloys and beryllium copper alloys produced thereby

2007-08-25T09:12:00.000-07:00

A process for producing the beryllium-copper alloy comprises the steps of casing a beryllium-copper alloy composed essentially of 1.00 to 2.00% by weight of Be, 0.18 to 0.35% by weight of Co, and the balance being Cu, rolling the cast beryllium-copper alloy, annealing the alloy at 500.degree. to 800.degree. C. for 2 to 10 hours, then cold rolling the annealed alloy at a reduction rate of not less than 40%, annealing the cold rolled alloy again at 500.degree. to 800.degree. C. for 2 to 10 hours, thereafter cold rolling the alloy to a desired thickness, and subjecting the annealed alloy to a final solid solution treatment. The beryllium-copper alloy obtained by this producing process is also disclosed, in which an average grain size is not more than 20 .mu.m, and a natural logarithm of a coefficient of variation of the grain size is not more than 0.25(1) Field of the Invention

The present invention relates to a process for producing beryllium-copper alloys having excellent mechanical strength, electric conductivity, reliability, etc. The invention also relates to beryllium-copper alloys produced by the above process.

(2) Related Art Statement

Beryllium-copper alloys composed mainly of Be and Cu have been widely used as as high strength spring materials, electrically conductive materials, etc. Beryllium-copper alloy is ordinarily converted to a thin sheet by conventional processes as shown in FIG. 2, for example. A beryllium-copper alloy having a given composition is cast, the cast beryllium-copper alloy is hot rolled, the hot rolled alloy is worked to a given dimension by subjecting it to annealing and cold rolling to remove work hardening, and finally, the cold rolled sheet is finished by solid solution treatment.

The annealing effected midway is carried out by strand annealings in which the alloy is recrystallized at high temperatures not lower than 800.degree. C. for a short time period, and the alloy is subjected to the solid solution treatment to soften the alloy. Further, no conventional knowledge is available regarding the reduction rate in the cold rolling which is carried out between a plurality of intermediate annealing steps, and such a reduction rate has been merely set by expediency. The term "reduction rate" (%) equals (thickness before rolling--thickness after rolling)/(thickness before rolling).times.100 with respect to the alloy.

However, the process for producing the beryllium-copper alloy shown by the flow chart in FIG. 2 has the following problems.

(1) Variations are likely to occur in alloy characteristics since the annealing is effected at high temperatures for a short time period and a recrystallization grain-growing speed is high. Therefore, since variations are likely to occur in the grain size and since the treatment is effected for a short time, a non-uniform texture after the hot rolling is difficult to eliminate.

(2) It is difficult to control the average crystalline grain diameter of the final product. This is because when the grain size is controlled to obtain desired characteristics, the grain size must be controlled only by the final solid solution treatment in the case of intermediate annealing effected at high temperatures.

(3) There is a high possibility that extremely duplex microstructure is produced. This is because when the temperature of the final solid solution treatment is controlled to increase the grain size, the temperature of the final solid solution treatment needs to be raised, which is likely to produce the duplex microstructure.

As discussed above, the conventional process has problems in a desired average grain size and grain size uniformity which greatly influence various characteristics, particularly, reliability. Accordingly, beryllium-copper alloys having excellent characteristics cannot be obtained.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the above-mentioned problems, and to provide a process for producing a beryllium-copper alloy, which produces an alloy product having uniform microstructure, small variations in alloy characteristics, and high reliability, whereby crystalline grain size can be easily controlled. The present invention also provides beryllium-copper alloys produced by this process.

The process for producing the beryllium-copper alloy according to the present invention is characterized by the steps of casting a beryllium-copper alloy composed essentially of 1.00 to 2.00% by weight of Be, 0.18 to 0.35% by weight of Co, and the balance being Cu, rolling the cast beryllium-copper alloy, annealing the alloy at 500.degree. to 800.degree. C. for 2 to 10 hours, then cold rolling the annealed alloy at a reduction rate not less than 40%, annealing the cold rolled alloy again, at 500.degree. to 800.degree. C. for 2 to 10 hours thereafter cold rolling the alloy to a desired thickness, and subjecting the annealed alloy to a final solid solution treatment.

The beryllium-copper alloy produced by the process according to the present invention is characterized in that the average grain size is not more than 20 .mu.m, and a natural logarithm of a coefficient of variation of the crystalline grain size is not more than 0.25.

These and other objects, features and advantages of the invention will be appreciated upon reading of the following description of the invention when taken in conjunction with the attached drawings, with the understanding that some modifications, variations and changes of the same could be made by the skilled person in the art to which the invention pertains without departing from the spirit of the invention or the scope of claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference is made to the attached drawings, wherein:

FIG. 1 is a flow chart of an example of the process for producing beryllium-copper alloy according to the present invention; and

FIG. 2 is a flow chart of an example of a conventional process for producing beryllium-copper alloy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the above process of the present invention, a beryllium-copper alloy commercially available as a high strength beryllium-copper alloy and having an ordinary composition is annealed twice by using overaging. The desired final grain size after the final solid solution treatment can be attained by specifying the temperature and time of the annealings and the reduction rate of the cold rolling effected therebetween.

The mechanism for controlling the grain size according to the present invention will be explained. The microstructure of the alloy having undergone hot rolling is non-uniform in many cases, and the non-uniform microstructure remains even after the cold rolling and the conventional annealing by the solid solution treatment, following the hot rolling. In view of this, this non-uniformity can be considerably reduced by annealing the alloy for a long time as in the case of the present invention. When the annealed alloy is then cold rolled at a given reduction rate and then annealed again for a long time, the thus reduced non-uniformity is eliminated. By such a consecutive treatment, a uniform microstructure can be obtained after the final solid solution treatment, while preventing occurrence of duplex microstructure.

Further, the precipitate formed on annealing using the overaging according to the present invention plays an important role in controlling the average grain size. The beryllium-copper alloy having the specified composition according to the present invention has an aging region and a solid solution region below and above about 600.degree. C., respectively. Therefore, when the annealing temperature is changed to be about 600.degree. C. as a center, microstructure a having different precipitation states can be obtained. The alloy has broadly two different kinds of the precipitates. One of them is spherical precipitate formed around a CoBe compound as nuclei, and the other is an acicular precipitate. The latter acicular precipitate is easily solid solved at the final solid solution treatment, whereas the former spherical precipitate is not readily solid solved. Thus the spherical precipitate pins recrystallized grain boundaries. Accordingly, the grain size of the alloy can be controlled by the same solid solution treatment through controlling the amount and the grain size of the spherical precipitate. The precipitate can be controlled by adjusting the annealing temperature during overaging. The desired uniformity of the spherical precipitate, i.e., the desired uniformity of the microstructure, can be attained by not only both annealing steps but also by intermediate cold rolling at a given reduction rate.

Next, reasons for various limitations in the present invention will be explained. First, the reason why the composition is limited to 1.00 to 2.00% by weight Be, 0.18 to 0.35% by weight of Co and the balance being Cu is that this composition is the most industrially practical from the standpoint of the mechanical strength, electrical conductivity and economy. The reason why the annealing temperature is set at 500.degree. to 800.degree. C. is that if the temperature is less than 500.degree. C., it is difficult to sufficiently recrystallize the alloy so that a non-uniform microstructure containing a non-recrystallized portion is produced, whereas if the temperature is more than 800.degree. C., the crystalline grains greatly grow to make it difficult to control the grain size in the succeeding final solid solution treatment. Further, the reason why the annealing time is limited to 2 to 10 hours is that if the time is less than 2 hours, uniformity is insufficient, whereas if it is more than 10 hours, no further annealing effect can be obtained. Further uniformity can be desirably attained by setting the annealing time to not less than 4 hours. In addition, the reason why the reduction rate in the cold rolling is set to not less than 40% is that if the reduction rate is less than 40%, sufficient uniformity can not be attained in the second annealing. In order to further increase the uniformity, the reduction rate is preferably not less than 60%.

FIG. 1 is the flow chart illustrating an example of the process for producing the beryllium-copper alloy according to the present invention. As shown in FIG. 1, after a beryllium-copper alloy having a given composition is cast, the cast ingot is subjected to rolling consisting of hot rolling and cold rolling. Then, the alloy rolled to a desired thickness of, for example, 2.5 mm is subjected to a first annealing at 500.degree. to 800.degree. C. for not less than 2 hours. Then, after the thus annealed alloy is cold rolled at a reduction rate of not less than 40%, the alloy is annealed again under the same annealing conditions as those of the first annealing. Finally, after the resulting alloy is cold rolled to a desired thickness, the alloy is subjected to solid solution treatment to obtain the beryllium-copper alloy according to the present invention.

The present invention will be explained in more detail with reference to specific examples.

Examples and Comparative Examples

A beryllium-copper alloy composed essentially of 1.83% by weight of Be, 0.2% by weight of Co, and the balance being Cu was cast, and the cast ingot was hot rolled to obtain a hot rolled plate having a thickness of 7.6 mm. The hot rolled sheet was then cold rolled to a thickness of 2.3 mm. Next, the sheet thus cold rolled was subjected to a first annealing under annealing temperature and time conditions given in the following Table, and then cold rolled at a reduction rate also shown in Table 1 after the annealing. Then, the cold rolled sheet was subjected to a second annealing under annealing temperature and time conditions also given in Table 1. Finally, after the alloy was cold rolled to a thickness of 0.24 mm, it was subjected to the solid solution treatment at 800.degree. C. for 1 minute.

A microstructure of each of the thus obtained alloy sheets falling inside and outside the scope of the present invention was photographed by an optical microscope. The degree of duplex representing the mean grain size and the spreading of the grain size distribution after the final solid solution treatment was determined by image analysis based on the photograph. The mixed grain size is a coefficient of variation assuming that a logarithm normal distribution is established. A small coefficient of variation represents a relatively uniform microstructure. Further, a R/t value as a bending characteristic and a hardness of the obtained alloy sheet were measured, and its coefficient of variation, CV, was determined to obtain variation degrees thereof. The coefficient of variation, CV, was determined according to CV=.sigma./x after obtaining an average value x and a standard deviation .sigma. with respect to 30 alloy sheets. Results are also shown in Table 1.

TABLE 1
__________________________________________________________________________
First annealing Second annealing
Temper- Reduction at
Temper- Mean grain
Degree
ature
Time
intermediate cold
ature
Time
size of CV Value
CV Value
Run No. (.degree.C.)
(hr)
rolling (%)
(.degree.C.)
(hr)
(.mu.m)
duplex
of RH of hardness
__________________________________________________________________________
Examples
1 500 10 76 500 6 12.5 0.175
0.009 0.020
in Present
2 565 10 76 565 6 7.5 0.220
0.007 0.017
Invention
3 700 6 40 565 6 7.0 0.222
0.007 0.018
4 700 6 60 600 6 7.7 0.215
0.009 0.017
5 700 6 40 630 4 8.2 0.220
0.013 0.023
6 630 6 60 630 6 8.0 0.220
0.015 0.025
7 700 4 76 700 6 12.0 0.183
0.011 0.020
8 700 6 76 700 6 13.0 0.180
0.010 0.019
9 800 4 60 565 6 7.0 0.210
0.006 0.017
10 800 4 60 800 4 17.0 0.210
0.009 0.020
Compar-
1 800 1 min.
76 565 10 7.6 0.300
0.046 0.029
ative 2 800 1 min.
76 830 1 min.
15.0 0.275
0.050 0.020
Examples
3 800 1 min.
60 -- -- 14.5 0.280
0.055 0.025
4 500 10 60 -- -- 12.0 0.190
0.030 0.020
5 565 10 60 -- -- 7.5 0.280
0.019 0.020
__________________________________________________________________________

As is clear from the results in Table 1, the alloy sheets of the present invention which have undergone the first and second annealings and the intermediate cold rolling therebetween have a smaller grain size, a smaller degree of duplex, a smaller variations in the mechanical properties, and a more uniform microstructure as compared with Comparative Examples outside the scope of the present invention. Further, it is also clear from the results in Table 1 that the mean grain size can be controlled over a wide range by the producing process of the present invention. That is, when the formability is to be improved, the second annealing may be effected at about 560.degree. C. On the other hand, when the strength before the final aging treatment is to be lowered, the second annealing may be effected at not less than 700.degree. C.

As is clear from the above-mentioned explanation, according to the present invention, when the beryllium-copper alloy is subjected to the first and second annealings utilizing overaging under the specified annealing temperature, and is subjected to time and the intermediate cold rolling at the specified reduction rate between the first and second annealings grain size can be controlled to yield a beryllium-copper alloy having uniform microstructure. As a result, a highly reliable product can be obtained by removing variations in the mechanical properties.

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

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Beryllium Copper Finger Strips and Industrial Enclosure Shielding

Beryllium-copper bonding material

2007-08-25T09:10:00.000-07:00

For bonding pure beryllium to a copper alloy, a beryllium-copper material comprising a single layer or multiple layers having a thickness of 0.3-3.0 mm and containing at least 50 atomic % of Cu is inserted between the pure beryllium and the copper alloy to prevent bonding strength from degrading in the bonding process or during operation of a nuclear fusion reactor, by effectively mitigating formation of brittle intermetallic compounds and generation of thermal stress at the bonding interfaceThis invention relates to a functionally gradient beryllium-copper materials, which is particularly suitable for bonding pure beryllium to pure copper or copper alloy.

BACKGROUND ART

In nuclear fusion reactors, beryllium is considered a promising plasma-resistant material due to its excellent heat resistance and suppressed absorption of tritium. However, beryllium lacks sufficient thermal conductivity and may thus undergo an inside heat accumulation. Therefore, as shown in FIG. 1, beryllium is designed to be bonded to a pure copper or copper alloy as a heat conductive material.

In FIG. 1, reference numeral 1 denotes a pure beryllium, 2 a pure copper or copper alloy, and 3 a cooling pipe.

Conventionally, vacuum silver soldering has been mainly used as the bonding method though it is pointed out that this method may adversely affect plasma and that it lacks reliability in actual plant level.

That is to say, in the case of vacuum silver soldering, as silver is transformed into cadmium by nuclear reaction, it is highly likely that silver is mixed in plasma as impurities thereby adversely affecting it. Moreover, there may occur a chemical reaction between the solder material and bonded material; therefore, it is difficult to obtain achieve reliable bonding.

Thus, diffusion bonding method has been studied as a new bonding technique, though a satisfactory result has not yet been achieved.

That is to say, in the case of diffusion bonding, it is highly likely that intermetallic compounds are formed between pure beryllium and pure copper or copper alloy. Moreover, there is a significant difference in thermal expansion coefficient between pure beryllium and pure copper or copper alloy. In view of the above, there has been no effective solution for a problem of decreased bonding strength which is caused by thermal stress occurring during the bonding process or during operation of the nuclear fusion reactor.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to effectively solve the abovementioned problems and provide a functionally gradient beryllium-copper material which is suitable for bonding pure beryllium to pure copper or copper alloy, having a satisfactory thermal conductivity and being capable of maintaining a satisfactory bonding strength during the bonding process or during operation of the nuclear fusion reactor, by preventing formation of brittle intermetallic compounds in the bonding section and mitigating occurrence of thermal stress.

To this end, the present invention provides a functionally gradient beryllium-copper materials suitable for bonding pure beryllium to pure copper or copper alloy, comprising a single layer or a plurality of layers of Be--Cu alloy having a thickness of 0.3-3.0 mm and containing at least 50 atomic % of Cu, wherein the Be--Cu alloy layer situated closer to the pure copper or copper alloy has a composition with a higher Cu content.

According to the present invention, an oxygen-free copper is particularly suitable for the pure copper, and an Al.sub.2 O.sub.3 -dispersion strengthened copper, a CuCrZr alloy, a CuNiBe alloy, a CuCrZrSi alloy, a CuW alloy, etc., are particularly suitable for copper alloy.

The present invention is based on experimental results to be explained hereinafter.

At the outset, the inventors conceived to insert a thin sheet of Be--Cu alloy as a bonding material when a pure beryllium is bonded to a pure copper or copper alloy (hereinafter collectively referred to as "copper alloy"), and performed a diffusion bonding with one or more Be--Cu alloy sheets of various Be contents inserted as a bonding material.

As a result, the inventors found that there were instances in which the materials could be successfully bonded and other instances in which the bonding could not be successfully achieved, so that one cannot definitely predict the bonding condition.

Then, the inventors investigated various characteristics of Be--Cu alloy, in particular, thermal conductivity from the viewpoint of heat conductive capacity, and thermal expansion coefficient and formation of brittle intermetallic compounds from the viewpoint of bonding strength.

First, the inventors prepared eleven testpieces changing the Cu content by 10 atomic % from a pure beryllium to a pure copper as shown in the following Table 1, and measured the thermal conductivity at various temperatures.

The result obtained is illustrated in FIG. 2.

TABLE 1
______________________________________
(atomic %)
1 2 3 4 5 6 7 8 9 10 11
______________________________________
BE 100 90 80 70 60 50 40 30 20 10 0
Cu 0 10 20 30 40 50 60 70 80 90 100
______________________________________

As can be appreciated from FIG. 2, the thermal conductivity of Be--Cu alloy does not gradually increase in proportion to the content of copper from pure beryllium to pure copper; rather, at every measuring temperature, it undergoes a reduction in the case of a low Cu content and becomes higher than that of beryllium when the content of Cu increases to at least 50 atomic %, and thereafter increases to the thermal conductivity of pure copper in a sense of quasi-quadric function curve.

Therefore, from the viewpoint of heat conductive capacity, it has been found necessary to use a Be--Cu alloy containing at least 50 atomic % of Cu.

In the next place, the inventors measured the thermal expansion coefficient with the same testpieces.

The result obtained is illustrated in FIG. 3.

As can be appreciated from FIG. 3, the thermal expansion coefficient of Be--Cu alloy increases approximately in proportion to the Cu content.

Therefore, a Be--Cu alloy containing at least 50 atomic % of Cu is particularly suitable for functionally gradient material having a satisfactory thermal conductivity and a reduced difference in thermal expansion coefficient between the pure beryllium and the copper alloy.

It has been further found that the functionally gradient material need not be in the form of a single layer, and multiple layers comprising two, three or more layers may also be used. In particular, the multiple layers are more advantageous than a single layer in terms of fatigue-resistant strength for a repeated thermal stress. However, in the case of multiple layers, it is important for the Be--Cu alloy layer situated closer to the copper alloy side to have a composition with a higher Cu content.

In this instance, when the functionally gradient material of Be--Cu alloy is a single layer, it is preferable for the Be--Cu alloy to have a composition which comprises 50-90 atomic % of Cu.

When the functionally gradient material has two layers, preferably, the first layer contains 50-80 atomic % of Cu and the second layer contains 60-90 atomic % of Cu. Also, when the functionally gradient material has three layers, preferably, the first layer as counted from the beryllium side contains 50-70 atomic % of Cu, the second layer contains 60-80 atomic % of Cu and the third layer contains 70-90 atomic % of Cu, respectively.

Furthermore, it has been found necessary for the thickness of the functionally gradient material to be 0.3-3.0 mm for both cases of a single layer and the multiple layers.

This is because the thickness less than 0.3 mm is not sufficient for reducing the difference in thermal expansion coefficients while the thickness more than 3.0 mm reduces the heat conductive capacity from the pure beryllium.

Furthermore, as regard the reduction in bonding strength due to brittle intermetallic compound formed in the bonding interface of pure beryllium and copper alloy, which has conventionally been a problem, it has been found that such a problem can be advantageously eliminated by using a powder sintering process when manufacturing the functionally gradient beryllium-copper materials.

That is, when pure beryllium is simply bonded to a copper alloy, the bonding strength at the bonding interface is degraded due to brittle intermetallic compounds, such as Be.sub.3 Cu(.delta.) and BeCu(.gamma.), which are formed in the bonding interface in a laminated manner when the bonding interface is heated to a temperature not less than 400.degree. C. in the bonding process or during operation of the nuclear fusion reactor.

Furthermore, when the bonding interface is heated to a temperature over 600.degree. C., a third intermetallic compound, i.e., BeCu(.beta.), is formed and this .beta. phase decomposes into Cu and .gamma. phases at 620.degree. C. by eutectoid reaction in the cooling process, which causes significant volumetric shrinkage, cracking and significantly degraded bonding strength.

In this respect, by using a powder sintering process, even when the intermetallic compounds, such as the .delta. phase and the .gamma. phase, are formed during the sintering process, they are formed around the beryllium particles with the beryllium particles as the core. Thus, a functionally gradient beryllium-copper material wherein such intermetallic compounds are finely dispersed in its surface is substantially free from formation of brittle intermetallic compounds at the interface of the pure beryllium in laminated manner, thereby making it possible to highly improve the bonding strength at the bonding interface.

Furthermore, as the functionally gradient beryllium-copper material according to the present invention has a satisfactory heat conductive capacity, as described above, the temperature at the bonding interface does not exceed 600.degree. C. even during operation of the nuclear fusion reactor. It is thus possible to effectively prevent formation of cracks due to formation and decomposition of the .beta. phase. Even if the .beta. phase is formed, the direct contact area of pure beryllium and copper alloy is small and it is thus possible to significantly mitigate degradation of bonding strength due to cracks, as compared to conventional materials.

A preferred manufacturing method according to the present invention is illustrated in FIG. 4.

As shown in FIG. 4, the Be powder and Cu powder preferably under 200 mesh are mixed mechanically, and are subsequently hot-pressed and then formed into a shaped body by a hot isostatic press (HIP) sintering process.

Preferably, the hot-press conditions are 400-600.degree. C. and 1-5 hours at 3-20 MPa, and the HIP conditions are 400-600.degree. C. and 1-8 hours at 100-200 MPa, respectively.

Subsequently, the shaped body is machined and ground on both surfaces, so as to form a functionally gradient material for bonding.

The functionally gradient beryllium-copper material according to the present invention makes it possible to effectively bond a pure beryllium to a copper alloy without degrading the bonding strength, not only in the bonding process but also during operation of the nuclear fusion reactor, and exhibits distinguished performance when used as a plasma-resistant material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of the bonding state of pure beryllium and copper alloy according to a conventional method;

FIG. 2 shows the influence of composition change of Be--Cu alloy on the thermal conductivity;

FIG. 3 shows the influence of composition change of Be--Cu alloy on thermal expansion coefficient;

FIG. 4 shows a preferred manufacturing process of Be--Cu alloy according to the present invention;

FIG. 5 is an illustration of the bonding state of pure beryllium and copper alloy according to the present invention; and

FIG. 6a illustrates the breaking point of a prior art testpiece subjected to a tensile test and

FIG. 6b illustrates the breaking point of a testpiece of the present invention subjected to a tensile test.

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLE 1

According to the manufacturing process shown in the above FIG. 4, 11 g of Be powder under 200 mesh and 704 g of oxygen-free Cu powder under 200 mesh were mixed, hot-pressed at 6.9 MPa and 600.degree. C. for 3 hours and formed into a shaped body by a HIP process at 192 MPa and 600.degree. C. for 2 hours, and then machined and polished on both surfaces to form an alloy sheet having a thickness of 10 mm and a composition of 10 atomic % of Be and 90 atomic % Cu.

As shown in FIG. 5, this alloy sheet was inserted between a pure beryllium 1 and an oxygen-free copper 2 as a bonding material 4, and a diffusion bonding was performed at 600.degree. C. and 150 MPa.

The bonding strength of the testpiece obtained as above was measured and it has been found that the bonding strength was 25 kgf/mm.sup.2 which is significantly improved as compared to the bonding strength of 15 kgf/mm.sup.2 which could be achieved by a conventional simple diffusion bonding.

Moreover, as shown in FIGS. 6a and 6b, the breaking point of the testpiece is situated in the oxygen-free copper side in the case of the present example (FIG. 6b), while that of the testpiece of a conventional material is in the bonding interface (FIG. 6a). It will be appreciated that the breaking strength of 25 kgf/mm.sup.2 is the strength of oxygen-free copper itself and that the bonding interface has a strength which is greater than that of oxygen-free copper.

EXAMPLE 2

Two kinds of sintered testpieces were prepared by the same process as example 1, wherein one testpiece has a thickness of 1 mm and a composition of 10 atomic % of Be and 90 atomic % of Cu, while the other testpiece has a thickness of 1 mm and a composition of 20 atomic % of Be and 80 atomic % of Cu.

Subsequently, as shown in FIG. 5, these two kinds of testpieces were stacked with the other and inserted between the pure beryllium and an oxygen-free copper as a bonding material, with the sintered testpiece having a higher Cu content, i.e., the testpiece having the composition of 10 atomic % of Be and 90 atomic % of Cu, situated adjacent to the copper alloy, and a diffusion bonding was then performed at 600.degree. C. and 150 MPa.

The bonding strength of the testpiece obtained by the above process is 25 kgf/mm.sup.2 and the breaking point is also situated in the oxygen-free copper side.

EXAMPLE 3

The bonding strength and the breaking point were investigated, with respect to a sintered material having a thickness of 1 mm and a composition of 10 atomic % of Be and 90 atomic % of Cu, and also with respect to the same sintered material which is stacked with another sintered material having a thickness of 1 mm and a composition of 20 atomic % of Be and 80 atomic % of Cu. These sintered materials were used as the inserted material, and the materials shown in Table 2 were used as the copper alloy.

The result obtained is shown in Table 2.

TABLE 2
______________________________________
Number of Bonding
sheets strength Breaking
Kinds of alloy
inserted (kgf/mm.sup.2)
position
______________________________________
Al.sub.2 O.sub.3 -dispersed
1 45 copper alloy side
strengthened Cu
0.3%Cr--0.1%Zr--Cu
1 65 copper alloy side
alloy
0.3%Ni-1.8%Be--Cu
1 85 copper alloy side
alloy
0.35%Cr--0.1%Zr--
2 55 copper alloy side
0.03%Si--Cu alloy
70%W--Cu alloy
2 40 copper alloy side
______________________________________

As can be appreciated from Table 2, when the functionally gradient material according to the present invention is used as the inserted material, a satisfactory bonding strength not less than 25 kgf/mm.sup.2 could be obtained in every case.

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Blogger: Beryllium Copper Finger Strips,EMI,EMC Products, - Create Post then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

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Beryllium Copper Finger Strips and Industrial Enclosure Shielding

EMI shield having flexible fingers with nonlinear slits

2007-08-25T09:06:00.000-07:00

An electromagnetic interference shield for use around access panels and doors in electronic equipment enclosures includes a base and profile manufactured from an electrically nonconductive solid material such as a thermoplastic resin polymer. An electrically conductive layer of a metallized fabric is bonded to the profile to provide effective shielding and grounding function. The underlying polymer provides elastic compliancy and resiliency to the shield. The shield may be divided into flexible fingers which can be rectangular or nonlinear shaped. The nonlinear shaped flexible finger from nonlinear shaped slits between the fingers which provides improved EMI shielding by reducing the amount of EMI transmission that can pass through the shield. The electromagnetic interference shield may also be made from an electrically conductive material. During normal operation, electronic equipment generates undesirable electromagnetic energy that can interfere with the operation of proximately located electronic equipment due to EMI transmission by radiation and conduction. The electromagnetic energy can by of a wide range of wavelengths and frequencies. To minimize the problems associated with EMI, sources of undesirable electromagnetic energy may be shielded and electrically grounded. Shielding is designed to prevent both ingress and egress of electromagnetic energy relative to a housing or other enclosure in which the electronic equipment is disposed. Since such enclosures often include gaps or seams between adjacent access panels and around doors, effective shielding is difficult to attain because the gaps in the enclosure permit transference of EMI therethrough. Further, in the case of electrically conductive metal enclosures, these gaps can inhibit the beneficial Faraday Cage Effect by forming discontinuities in the conductivity of the enclosure which compromise the efficiency of the ground conduction path through the enclosure. Moreover, by presenting an electrical conductivity level at the gaps that is significantly different from that of the enclosure generally, the gaps can act as slot antennae, resulting in the enclosure itself becoming a secondary source of EMI.

Specialized EMI gaskets have been developed for use in gaps and around doors to provide a degree of EMI shielding while permitting operation of enclosure doors and access panels. To shield EMI effectively, the gasket should be capable of absorbing or reflecting EMI as well as establishing a continuous electrically conductive path across the gap in which the gasket is disposed. Conventional metallic gaskets manufactured from copper doped with beryllium are widely employed for EMI shielding due to their high level of electrical conductivity. Due to inherent electrical resistance in the gasket, however, a portion of the electromagnetic field being shielded induces a current in the gasket, requiring that the gasket form a part of an electrically conductive path for passing the induced current flow to ground. Failure to ground the gasket adequately could result in radiation of an electromagnetic field from a side of the gasket opposite the primary EMI field.

In addition to the desirable qualities of high conductivity and grounding capability, EMI gaskets should be elastically compliant and resilient to compensate for variable gap widths and door operation, yet tough to withstand repeated door closure without failing due to metal fatigue. EMI gaskets should also be configured to ensure intimate electrical contact with proximate structure while presenting minimal force resistance per unit length to door closure, as the total length of an EMI gasket to shield a large door can readily exceed several meters. It is also desirable that the gasket be resistant to galvanic corrosion which can occur when dissimilar metals are in contact with each other for extended periods of time. Low cost, ease of manufacture, and ease of installation are also desirable characteristics for achieving broad use and commercial success.

Conventional metallic EMI gaskets, often referred to as copper beryllium finger strips, include a plurality of cantilevered or bridged fingers forming linear slits therebetween. The fingers provide spring and wiping actions when compressed. Other types of EMI gaskets include closed-cell foam sponges having metallic wire mesh knitted thereover or metallized fabric bonded thereto. Metallic wire mesh may also be knitted over silicone tubing. Strips of rolled metallic wire mesh, without foam or tubing inserts, are also employed.

One problem with metallic finger strips is that to ensure a sufficiently low door closure force, the copper finger strips are made from thin stock, for example on the order of about 0.05 mm (0.002 inches) to about 0.15 mm (0.006 inches) in thickness. Accordingly, sizing of the finger strip uninstalled height and the width of the gap in which it is installed must be controlled to ensure adequate electrical contact when installed and loaded, yet prevent plastic deformation and resultant failure of the strip due to overcompression of the fingers. To enhance toughness, beryllium is added to the copper to form an alloy; however, the beryllium adds cost. Finger strips are also expensive to manufacture, in part due to the costs associated with procuring and developing tooling for outfitting presses and rolling machines to form the complex contours required. Changes to the design of a finger strip to address production or performance problems require the purchase of new tooling and typically incur development costs associated with establishing a reliable, high yield manufacturing process. Notwithstanding the above limitations, metallic finger strips are commercially accepted and widely used. Once manufacturing has been established, large quantities of finger strips can be made at relatively low cost.

Metallic mesh and mesh covered foam gaskets avoid many of the installation disadvantages of finger strips; however, they can be relatively costly to produce due to the manufacturing controls required to realize acceptable production yields.

Another problem with conventional finger strips is that they are not as effective in EMI shielding as clock speed of an electronic product is increased. As clock speed is increased, the wavelength of the EMI waves produced decreases. Accordingly, the waves can penetrate smaller and smaller apertures in the enclosure and in the EMI shield. At lower wavelengths, the slits formed in the finger shields can act as slot antennae, permitting the passage of EMI therethrough and the resultant shielding effectiveness of the shields decreases. Conventional finger strips with linear slits formed between the fingers are increasingly less effective in these applications.

SUMMARY OF THE INVENTION

A metallized fabric clad polymer EMI shield overcomes many of the limitations and disadvantages of conventional EMI shields. One method of manufacturing a metallized fabric clad polymer shield for shielding EMI from passing through a seam between first and second electrically conductive bodies includes forming a base and a profile of an electrically nonconductive solid material in a predetermined configuration. The base is designed to secure the shield to the first body while the profile is designed to contact the second body. An electrically conductive layer is then disposed on at least part of the profile so as to be interdisposed between the profile and the second body upon installation of the shield in a suitable gap of an electronic enclosure. In one exemplary embodiment, the profile and base may be an extrusion of a polymer such as polyvinyl chloride ("PVC"), a thermoplastic resin, and the conductive layer may be a metallized fabric bonded to the profile by a heat sensitive glue. The forming and deposition processes may be separate or may be substantially contiguous. After extrusion and cooling of the profile and base, the metallized fabric may be bonded to the profile in a separate operation. Alternatively, by employing an in-line crosshead extrusion method, the polymer base and profile may be formed and substantially immediately thereafter, the metallized fabric applied as a thermally activated glue-backed tape. Resultant thermal energy in the extrusion activates the glue on the fabric side of the tape, bonding the metallized fabric to the profile. As a subsequent step in either manufacturing method, the profile may be divided into a plurality of independently flexible cantilevered or bridged fingers to compensate for variable gap width along the length of the gap.

Another embodiment for manufacturing a metallized fabric clad polymer EMI shield according to the invention includes disposing an electrically conductive layer on an electrically nonconductive solid sheet material and then forming the sheet into a base and a profile of a predetermined configuration. The sheet may be a polymer such as PVC, the conductive layer may be a metallized fabric bonded to the sheet by a thermally activated glue, and the profile and base may be formed by a thermal process such as thermoforming. As a subsequent step in the manufacturing method, the profile may be divided into a plurality of independently flexible cantilevered or bridged fingers.

According to certain embodiments of the invention, a metallized fabric clad polymer shield for shielding EMI from passing through a seam between first and second electrically conductive bodies includes a base for securing the shield to the first body, a profile of an electrically nonconductive solid material attached to the base for contacting the second body, and an electrically conductive layer disposed on the profile.

The base and the profile may be formed integrally of the same material by extrusion or of different materials by co-extrusion. Alternatively, the base and the profile may be similar or distinct materials joined together by bonding. Additionally, a hinge of a material exhibiting different flexural characteristics may be disposed between the base and the profile, either by co-extrusion or bonding. As used herein, the term bonding includes chemical processes such as those using glues or solvents, as well as mechanical processes such as friction welding and interlocking mechanical cross-sections.

To facilitate installing the EMI shield in an enclosure, an adhesive strip may be attached to the base. Alternatively, the base may include apertures for mechanical fasteners or a return for insertion in a slot or for capturing a flange of the first body. The return may also include barbing to stabilize the shield once installed.

Further EMI shield effectiveness may be achieved using nonlinear shaped EMI shielding fingers forming nonlinear slits therebetween. Various embodiments of nonlinear fingers and slits are contemplated, including those which are arcuate, sinusoidal, interdigitated, chevron-shaped, and combinations thereof. By using nonlinear fingers, the slits formed between the fingers do not form linear apertures so that EMI transmission in a given direction cannot line up with an entire slit length, but only a limited portion of the slit length. For arcuate and sinusoidal slits, as the radius of curvature is decreased, in the limit, the wavelength of EMI waves capable of passing through the slits approaches slit width, which can be substantially zero.

In one embodiment, the EMI shielding fingers with nonlinear slits may be manufactured out of an electrically conductive material such as a copper beryllium alloy or other metallic material. In another embodiment, the NM shielding fingers with nonlinear slits may be manufactured out of a metallized fabric clad polymer or other coated or clad material composition. In general, the nonlinear slits may be employed in any EMI finger shield, regardless of the material and method of manufacture, providing greatly improved EMI shielding effectiveness for short and very short wavelength radiation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, in accordance with preferred and exemplary embodiments, together with further advantages thereof, is more particularly described in the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1A is a schematic plan view of a portion of an EMI shield in accordance with one embodiment of the present invention;

FIG. 1B is a schematic sectional view of the EMI shield depicted in FIG. 1A taken along line 1B--1B;

FIG. 1C is an enlarged view of FIG. 1B rotated counterclockwise ninety degrees and including the metallized fabric.

FIG. 2 is a schematic sectional view of an EMI shield disposed in a gap in accordance with a another embodiment of the present invention;

FIG. 3 is a schematic sectional view of an EMI shield in an uninstalled state in accordance with yet another embodiment of the present invention;

FIG. 4 is a schematic block diagram representation of a method of manufacture of an EMI shield by extrusion in accordance with one embodiment of the present invention;

FIG. 5A is a schematic plan view of an EMI finger shield with non-linear arcuate fingers forming arcuate slits in accordance with one embodiment of the present invention;

FIG. 5B is a schematic plan view of an EMI finger shield with non-linear sinusoidal fingers forming sinusoidal slits in accordance with another embodiment of the present invention;

FIG. 6A is a schematic plan view of an EMI finger shield with non-linear chevron fingers forming chevron slits in accordance with yet another embodiment of the present invention;

FIG. 6B is a schematic plan view of an EMI finger shield with non-linear zigzag fingers forming zigzag slits in accordance with still another embodiment of the present invention;

FIG. 7A is a schematic plan view of an EMI finger shield with non-linear interdigitated fingers forming corresponding slits in accordance with yet still another embodiment of the present invention; and

FIG. 7B is a schematic plan view of an EMI finger shield with non-linear interdigitated fingers forming corresponding slits in accordance with still a further embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B are schematic plan and sectional views, respectively, of a metallized fabric clad polymer EMI shield 10 in accordance with one embodiment of the present invention. The shield 10 is formed from an electrically nonconductive solid material to produce a substantially planar base 12 and a generally arcuate profile 14 having an offset tip 16. The base 12 is configured with a series of apertures 18 so that the base 12 can be secured to a first body (not depicted) by a plurality of nuts and bolts, self-tapping machine screws, rivets, or other mechanical fasteners.

Referring now to FIG. 1C, an enlarged sectional view of the EMI shield 10 is depicted, including an electrically conductive layer of metallized fabric 20 disposed on the profile 14. The relative thicknesses of the fabric 20 and the profile 14 in this and other embodiments are for illustrative purposes only. In some embodiments, as will be discussed in greater detail hereinbelow, the thickness of the fabric 20 is typically substantially less than that of the profile 14. The metallized fabric 20 is bonded to the profile 14 with the fabric portion proximate the profile 14 and the metallic portion remote therefrom. The fabric 20 extends from the base 12 proximate the aperture 18 along the profile 14 and wraps around the offset tip 16. Accordingly, when the EMI shield 10 is compressed between first and second bodies at contact zones shown generally as arrows B1 and B2, the fabric provides an electrically conductive path therebetween. Since the EMI shield 10 is secured to the first body solely at the base 12 in a bridge configuration, the tip 16 is free to slide across the first body as the profile 14 is compressed by the second body. By offsetting the tip 16 slightly, the tip 16 slides readily over imperfections in the surface of the first body. Accordingly, the profile 14 elastically deforms during compressive loading, such as when the door is closed, instead of being jammed and crushed.

As is apparent from the depiction in FIG. 1C, the plane of the base 12 is offset from an end of the tip 16 so that when the EMI shield 10 is secured to the first body, a predetermined elastic deformation of the profile 14 results. This preloading of the EMI shield 10 ensures that the tip 16 remains in intimate contact with the first body, thereby providing a positive electrical ground path. In other embodiments, the fabric 20 may extend along the base 12 covering the aperture 18 so that a redundant electrical ground path exists when a fastener such as an aluminum rivet passes through the fabric and aperture, securing the EMI shield 10 to the first body. In yet another embodiment, the fabric may extend further, wrapping around the base 12 so that the fabric 20 is captured between the base 12 and the first body thereby providing a more positive electrical ground path. For any of these embodiments, the fabric 20 may stop short of the tip 16 or need not wrap around the tip 16, if desired.

Referring again to FIG. 1A, the profile 14 of the EMI shield 10 may be divided at regular intervals into a plurality of independently flexible fingers 22, each extending from the common base 12. By subdividing the profile 14 in this manner, the EMI shield 10 can provide effective shielding in a gap which varies in width along its length. Reliefs 24 may be provided at the corners of the fingers 22 to blunt the fingers 22 and minimize catching of the tips 16 on surface imperfections in the first body.

Instead of having a compressive arcuate profile 14, an EMI shield 100 may have a substantially planar profile 114 attached to a substantially planar base 112 by a hinge 26 in a cantilevered configuration so that the EMI shield 100 resembles a recumbent "W" as depicted in FIG. 2. A metallized fabric 120 envelops the entire exterior surface of the EMI shield 100 and wraps around respective tips of both the base 112 and profile 114. The base 112 may be attached to a first body 28 by a thin layer of adhesive 32 along a portion thereof to retain the EMI shield 100 in a predetermined position. The adhesive 32 may be electrically conductive. As a second body 30 moves relative to the first body 28 varying the width of a gap G formed therebetween, the hinge 26 elastically deforms to keep the profile 114 in contact therewith. The V-shaped configuration of the hinge 26 is designed to accommodate a relatively large range of motion between the first and second bodies 28, 30 while maintaining contact for electrical ground and shielding purposes; however, any of a variety of hinge configurations may be used. While the fabric 120 is depicted as being bonded to the entire exterior surface of the EMI shield 100, for ease of manufacture the fabric 120 need not be bonded to the hinge 26. A sufficient amount of fabric 120 should be provided in the area of the hinge 26, however, so as not to restrict the full range of compression of the EMI shield 100.

In this EMI shield 100, all of the base 112, the hinge 26 and the profile 114 are manufactured from the same polymer material; however, different materials with different material properties may be used as depicted in FIG. 3. The EMI shield 200 includes a substantially planar profile 214 which forms an acute angle with a substantially planar base 212 in a cantilevered configuration so that the EMI shield 200 resembles a recumbent "U". Instead of terminating at a tip, however, the base 212 includes a return 34 which forms a throat 36 to permit mounting the EMI shield 200 on a planar flange of the first body. The return includes barbing 38 directed into the throat 36 to stabilize the EMI shield 200 once installed on the flange. The return 34 could alternatively be configured for insertion into a slot in the first body. Barbing 38 extending in opposing directions from both sides of the return may be used to stabilize the EMI shield 200 in such a configuration.

The profile 214 is attached to the base 212 by a hinge 126, but instead of being manufactured from the material used to make the base 212 and the profile 214, the hinge 126 may be manufactured of a more flexible material resistant to fatigue failure to extend the life of the EMI shield 200. A metallized fabric 220 envelops the entire exterior surface of the EMI shield 200, wrapping around the tip of profile 214 and extending into the throat 36 to provide a electrical ground path between the first and second bodies. While the fabric 220 is depicted as being bonded to the entire exterior surface of the EMI shield 200, the fabric 220 need not be bonded to the hinge 126. A sufficient amount of fabric 220 should be provided in the area of the hinge 126, however, so as not to restrict the full range of compression of the EMI shield 200.

A cost effective method of manufacture of the various EMI shields is by continuous extrusion of one or more selected polymers using a screw extruder 40 having a die 42 with the desired shape of the cross-section of the shield 10 as depicted schematically in FIG. 4. In one embodiment, the shield 10 may be manufactured from high temperature rated PVC for flame retardancy, although any electrically nonconductive material with a suitable modulus of elasticity may be employed. Flame retardancy is desirable, however, since such EMI shields can be approved for installation in safety certified electronic equipment enclosures. If a more flexible hinge is desired, a compatible material such as polyester can be coextruded with the profile and base to form the hinge. A suitable polyester hinge material is Hytrel.TM., available from DuPont located in Wilmington, Del. Techniques of coextrusion are well known to those skilled in the art of polymer processing.

Once the polymer portion of the EMI shield 10 has been formed to the desired configuration, an electrically conductive layer is disposed on the profile 14 and any other portion of the EMI shield 10 desired. One method employs a metallized fabric 20 in tape form of suitable width backed with a thermally activated glue. The glue may cover substantially the entire backing or solely portions thereof such as along the edges. In a process known to those skilled in the art as in-line crosshead extrusion, as the polymer is being extruded through the die 42, the hot extrusion passes through a second die 44 in which the metallized fabric tape 20 is mated thereto. The thermal energy in the extrusion and the second die 44 activates the glue, bonding the metallized fabric 20 to the profile 14. Alternatively, the metallized fabric 20 can be disposed on the extrusion in a separate operation, such as by passing the formed polymer and metallized fabric tape 20 through a heated die after the polymer has been cut to a desired length.

As used herein, the term metallized fabrics include articles having one or more metal coatings disposed on woven, nonwoven, or open mesh carrier backings and equivalents thereof. See, for example, U.S. Pat. No. 4,900,618 issued to O'Connor et al., U.S. Pat. No. 4,901,072 issued to Morgan et al.; U.S. Pat. No. 5,075,037 issued to Morgan et al., and U.S. Pat. No. 5,393,928 issued to Cribb et al., the disclosures of which are herein incorporated by reference. Metallized fabrics are commercially available in a variety of metal and fabric carrier backing combinations. For example, pure copper on a nylon carrier, nickel-copper alloy on a nylon carrier, and pure nickel on a polyester mesh carrier are available under the registered trademark Flectron.RTM. from Advanced Performance Materials located in St. Louis, Mo. An aluminum foil on a polyester mesh carrier is available from Neptco, located in Pawtucket, R. I. Other suitable metals include silver and tin. The choice of metal is guided, in part, by installation conditions of the EMI shield. For example, a particular metal might be chosen due to the composition of abutting body metal in the enclosure to avoid galvanic corrosion of the EMI shield which could increase electrical resistance and deteriorate electrical grounding performance. Metallized tapes are desirable both for ease of application as well as durability. Deposition of a metal layer directly on the polymer profile would wear away relatively quickly due to friction when compared to the metallized fabrics.

Once the metallized fabric has been bonded to the EMI shield, other features can be formed. For example, the EMI shield may pass through rotary drilling, stamping, or piercing tools to divide the profile into independently flexible fingers or create apertures in the base for mounting the shield. The EMI shield can be cut to the desired length before or after these finishing operations.

Instead of forming the polymer and then applying the metallized fabric, according to some embodiments of the present invention, the metallized fabric can be first bonded to either flat or preformed polymer sheet stock. Then, the sheet stock can be thermoformed to a final predetermined configuration by as known by those skilled in the art. Thermoforming can be accomplished on discrete pieces of sheet stock in a heated die or continuously by passing the sheet stock through heated rollers to produce the desired configuration. Additional manufacturing steps such as generating the mounting apertures or dividing the profile into fingers can be accomplished prior to, during, or after thermoforming, as desired.

By relying on the metallized fabric to provide an electrically conductive path and the underlying polymer to provide elastic compliancy and resiliency, lower electrical resistance is achievable since beryllium is not required to be added to copper for toughness. As a result, the electrical conductivity and the resultant EMI shielding capability of the EMI shield according to this invention is improved over conventional copper beryllium finger strips. Further, the polymer portion of the shield is less brittle than all metal copper beryllium finger strips, resulting in reduced handling and installation damage to the EMI shield, improved safety, and extended service life.

In an exemplary embodiment, the thickness of an EMI shield profile according to the invention may be between about 0.13 mm (0.005 inches) or less and about 01.5 mm (0.060 inches) or more. In a preferred embodiment, the thickness of the EMI shield profile may be between about 0.25 mm (0.010 inches) or less and about 1.0 mm (0.04 inches) or more. The metallized fabric may have a thickness between about 0.1 mm (0.004 inches) or less and about 0.5 mm (0.02 inches) or more. These ranges are considered exemplary in nature and specific dimensions for a particular application would depend on the mechanical properties of the polymer material selected for the profile and hinge, the overall configuration of the EMI shield, and the electrical properties of the metallized fabric. Accordingly, values outside these ranges are considered to be within the scope of the invention.

An improved method of EMI shielding can be achieved by modifying the configuration of the EMI shield fingers. Instead of dividing the profile 14 of the EMI shield 10 into rectangularly shaped independent fingers 22, according to some embodiments of the present invention, the profile 14 may be divided into fingers of other nonlinear shapes. As depicted in FIG. 5A, an EMI shield 310 having a profile 314 may be divided into arcuate-shaped, independently flexible fingers 322, which form nonlinear arcuate slits 350 therebetween. The width of the slits depicted in the figures is exaggerated to facilitate depiction. In practice, slit width can be substantially zero, with the profile being cut only, without the removal of any material. By dividing the profile 314 into non-rectangular fingers, the EMI shield 310 can provide improved EMI shielding, because an EMI transmission in a given direction cannot be aligned with the entire slit length from the base 312 to the tip 316. As with the EMI shield 10 with the independently flexible fingers 22 of rectangular shape depicted in FIG. 1A, the EMI shield 310 with arcuate shaped independently flexible fingers 322 shown in FIG. 5A may also include the other features, such as apertures 318 in a base 312 thereof and an offset tip 316.

Instead of having arcuate-shaped independently flexible fingers 322, an EMI shield 410 may be a version thereof, and have a profile 414 divided into sinusoidal-shaped independently flexible fingers 422, as depicted in FIG. 5B. The EMI shield 410 with sinusoidal-shaped independently flexible fingers 422 also may include a base 412 and apertures 418 formed therein. The radius or radii of curvature of the arcuate and sinusoidal fingers 322, 422 may be selected, as desired, to minimize the passage of EMI waves therethrough, as discussed hereinabove.

An EMI shield 510 with a profile 514 may be divided into chevron-shaped independently flexible fingers 522 as depicted in FIG. 6A. A base 512 may form apertures 518. Alternatively, an EMI shield 610 may be a version thereof, with a profile 614 being divided into zigzag shaped independently flexible fingers 622 as depicted in FIG. 6B, with an associated base 612 and apertures 618.

An EMI shield 710 with a profile 714 may also be divided into more complex shapes, such as independently flexible interdigitated fingers 722 as depicted in FIG. 7A, with a base 712 and apertures 718.

Lastly, as depicted in FIG. 7B, an EMI shield 810 with a profile 814 may combine the features of other fingers, such as the zigzag fingers 622 of FIG. 6B and the generally rectangularly interdigitated fingers 722 of FIG. 7A to form independently flexible interdigitated fingers 822 with tapered portions.

The EMI finger shields having fingers of non-rectangular shape may be manufactured according to any method and with any material, including electrically conductive materials, such as copper beryllium alloy, as well as metallized fabric clad polymers.

While there have been described herein what are to be considered exemplary and preferred embodiments of the present invention, other modifications of the invention will become apparent to those skilled in the art from the teachings herein. For example, instead of the fingers being arcuate or planar, more complex contours such as partially twisted fingers may be created by thermoforming when the profile is divided into fingers or thereafter. Additionally, the invention is not limited to linear EMI shields, but rather includes shaped EMI shields such as those in the form of annuli and other closed or open curves required for specific applications. Still further, the non-linear slits formed between adjacent fingers may be any combination of the shapes disclosed herein, as well as other geometries and variants thereof. For example, the slits may be chevron-shaped proximate the base and arcuate proximate the tip. Moreover, the non-linear slits may be formed in any EMI finger shield, irrespective of the method of attachment to the enclosure to be shielded. For example, the shield base may be bonded to the enclosure or may include a return with barbing to attach to an enclosure flange. In general, all combinations and permutations of the EMI shields disclosed herein are considered to be within the scope of the invention. The particular methods of manufacture of and geometries disclosed herein are exemplary in nature and are not to be considered limiting.

It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the invention. Accordingly, what is desired to be secured by Letters Patent is the invention as defined and differentiated in the following claims

We can supply any quantity and any kind of Copper Beryllium Finger Strips and Industrial Enclosure Shielding from stock.would you please inform us how many you need and your target price, then we will confirm ASAP. We are sincerely hope to do business with you and establish long term business relationship with your respectable company.

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Sam Xu
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Beryllium Copper Finger Strips and Industrial Enclosure Shielding