fingerstock Gaskets

Parker Chomerics Beryllium Copper and Stainless Steel Gaskets

Parker Chomerics beryllium-copper (BeCu) and stainless steel EMI gaskets (SPRING-LINE®) combine high levels of shielding effectiveness with a broad deflection range and low closure force properties. The spring finger wiping action can also help to reduce oxide build-up at mating contact surfaces when the gasket is used in applications demanding repeated openings and closings. The excellent performance qualities of beryllium-copper, including: high tensile strength, extreme operating temperature range and superb electrical conductivity, make it an ideal material for EMI shielding over a broad frequency range. For applications that are mechanically less demanding, stainless steel gaskets offer good tensile strength, extreme operating temperature range and good electrical conductivity. Stainless steel gaskets have higher compression set than BeCu, when used in demanding applications.

**note: please click to open the Fingerstock Catalog to view tables referred to below.

Our BeCu shielding gaskets are available in four Parker Chomerics standard finishes: clean and bright (unplated), zinc / clear trivalent chromate, bright nickel, and bright tin. These four finishes are RoHS compliant. Other common finishes are listed in Table 1 & 5 and are available upon request. BeCu gasket finishes should be chosen to minimize galvanic corrosion of the final assembly, see Table 3.

Stainless steel gaskets are only available with clean and bright (unplated) finishes. BeCU and Stainless steel gasket shielding effective properties are shown in Table 4.

Galvanic Compatibility

Galvanic corrosion occurs as electrons move from dissimilar metals through an electrolyte, such as water or salt spray / fog. The goal of an EMI gasket is to be part of an electrically conductive shield and the gasket material is typically mated with a structural metal, such as aluminum or stainless steel. Since BeCu or stainless steel EMI gaskets are galvanically different than aluminum or steel, there would be two dissimilar metals in contact with each other. If the assembly in the application is susceptible to the presence of an electrolyte, there is a high probability that galvanic corrosion will occur, which will degrade both the structure and the shielding effectiveness in the application. To reduce the potential for corrosion, the electrical potential difference between the two metals should be minimized. This is where the availability of different finishes on BeCu parts can help. For example, bright and clean BeCu parts in contact with chem filmed aluminum will typically corrode less if they are finished with tin plating. Nickel plated aluminum parts will work well with nickel plated BeCu. As an added bonus, among the current finishes we offer, nickel plating is also very abrasion resistant. Those applications with a lot of wear or many cycles could benefit from a nickel finish. Against zinc plated steel and zinc castings, the use of zinc/clear trivalent chromate parts is often used. See the Electromechanical Compatibility Table 3 on page 4 for further details.

For those applications where there is no concern for corrosion, such as those where there is no electrolyte present, then the risk for galvanic corrosion is minimal. In these applications a bright and clean (unplated) finish will suffice and save finish costs.

 

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NOTICE: The information contained herein is to the best of our knowledge true and accurate. However, since the varied conditions of potential use are beyond our control, all recommendations or suggestions are presented without guarantee or responsibility on our part and users should make their own tests to determine the suitability of our products in any specific situation. This product is sold without warranty either expressed or implied, of fitness for a particular purpose or otherwise, except that this product shall be of standard quality, and except to the extent otherwise stated Chomerics’ invoice, quotation, or order acknowledgement. We disclaim any and liability incurred in connection with the use of information contained herein, or otherwise. All risks of such are assumed by the user. Furthermore, nothing contained herein shall be construed as a recommendation to use any process or to manufacture or to use any product in conflict with existing or future patents covering any product or material or its use.