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Browse Prior Art Database

EMC Gasket for Organic-Coated Sheet Metal

IP.com Disclosure Number: IPCOM000021552D
Original Publication Date: 2004-Jan-22
Included in the Prior Art Database: 2004-Jan-22
Document File: 3 page(s) / 102K

Publishing Venue

IBM

Abstract

An EMC gasket comprised of dendritic particles capable of puncturing organic coatings on sheet metal provides a low impedance path to ensure adequate electromagnetic interference protection.

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EMC Gasket for Organic-Coated Sheet Metal

The basic problem concerns breaking through a thin insulating barrier on materials that have an organic coating to prevent fingerprints. Recently, development is moving towards antifingerprint coatings consisting of a thin organic coating that is present on the material to prevent discoloration. The problem with the present low-cost fabric over foam gaskets (e.g., nickel/copper polyester knitted mesh, or a nickel/copper nylon ripstop with urethane coating) is that the fabric usually does not break through the antifingerprint coating in a uniform manner to provide the low transfer impedance needed to limit transverse power flow through the gasketted junction. Present materials with an antifingerprint coating do not compare favorably with the traditional materials,
e.g., G30, when tested in contact with present fabric over foam gasketting. When the coating is thinned to allow good contact to the gasket, it is too thin to protect the material against fingerprints and the resultant discoloration.

In order to provide the low transfer impedance of an EMC gasket when used in conjunction with an antifingerprint coating, a dendritic, 'spiked' metal particle is incorporated into the gasket which breaks through the thin organic coating. The metal particles/powder is calendared onto the appropriate fabric in much the same fashion as aluminum oxide powder is coated onto a paper substrate for sandpaper. A direct metal-to-metal contact is...