Flexible film with circuitry thereon having improved local compliance

Abstract

The invention relates to an improved, high density electrical connector, such as a backplane connector, which utilizes a flexible film having circuitry thereon for interconnecting plural planar electronic devices, such as a daughter board to a mother board. The improvement is derived through the use of a flexible film enhanced for local compliance, and to the inclusion of a force distribution member. The enhanced flexible film comprises a composite of a thin, flexible, dielectric film having upper and lower surfaces, a thin layer of metal disposed along the lower surface, and a plurality of discrete metallic pads or traces along the upper surface. Improved local compliance is accomplished by the thin metal layer having plural through slots, by mechanical punching or laser cutting, where each slot is aligned between a pair of adjacent metallic pads or traces. By this arrangement, the composite has improved local compliance between adjacent metallic pads or traces. To further improve the electrical connection of this enhanced flexible film, a force distribution member, underlying and in contact with the flexible film is provided. The force distribution member comprises an elastomeric member adjacent a first surface of the flexible film composite, and a thin metal force integrator along a surface of the elastomeric member remote from the composite. The force distribution member, in turn, is urged against the flexible film composite by a coil spring, for example, as known in the art.