Electrical and mechanical properties of a metal-filled polymer composite for interconnection and testing applications

A group of metal-filled polymer composites developed as compliant interconnection materials for connector and testing applications is discussed. This material group is referred to as elastomeric conductive polymer interconnection (ECPI) materials. ECPIs make electrical connection between opposing contact areas using conductive columns that are uniformly distributed within a sheet of silicone rubber and are separated by a spacing of 7 mil or less. The materials are suitable for interconnecting high-density, fine-pitch, pad-grid arrays and are capable of accommodating tolerance variations arising from plating thickness, substrate warp, and nonplanarities between opposing contact areas. ECPIs can be deformed by up to 40% of their uncompressed thickness without compromising their electrical properties. For the high-performance interconnections the material should be less than 20 mil, which would provide a maximum compliance of 8 mil