Graphite/conductive-epoxy EMI shielding

Electromagnetic News Report, Jan/Feb 2001

As a result of research done by John D. Lennhoff and George G. Harris of Triton Systems for the John H. Glenn Research Center, Cleveland, Ohio, and reported in NASA Tech Briefs, lightweight EMI shields can now be fabricated from composites of electrically conductive fibers made of bromine-intercalated graphite in matrices of electrically conductive epoxy. As shown in detail below, the shielding ability of a given thickness of this composite material equals that of a greater thickness of aluminum.

Electrical conductivity of surface layers is essential for EMI shielding. Previously, NASA had developed EMI shields made of bromine-intercalated graphite fibers in matrices of electrically insulating epoxy. However, those shields were not as effective as aluminum shields because of the lack of electrical conductivity in the epoxy (especially in surface layers).

It has been estimated that by using this composite material, it should be possible to make EMI shields thinner than aluminum shields (which are typically about 2mm), but equally as strong and effective. Reductions in weight, relative to aluminum shields, can be expected to lie between 34 and 88%.

For more information, access the Technical Support Package (TSP) free on-line at www.nasatech.com under the Materials category. Inquiries about rights for commercial use should be addressed to NASA Glenn Research Center, Commercial Technology Office, Attn: Steve Fedor, Mail Stop 4-8, 21000 Brookpark Rd., Cleveland, OH 44135/Refer to LEW-16647.