A fully additive, polymeric process for the fabrication and assembly of substrate and component level packaging

A novel base technology that is applicable to all major packaging and redistribution elements in an electronic module is presented. A single family of polymer/metal composite conductors can be used for chip packaging redistribution layers, MCM or multilayer PWB interconnects, and SMT assembly. High density multilayer circuits with landless blind and buried vias can be fabricated by filling conductor paste into photoimaged dielectrics and thermal processing. Via layers are prepared directly on the inherently planarized circuit layer in identical fashion. Building up layers sequentially in this manner results in multilayer circuits built on a single substrate layer and minimizes the number of interfaces between dissimilar materials. As these composite materials are applied in an additive fabrication method, metal substrates can be employed for high thermal dissipation and excellent CTE control over a wide temperature range. Two variants of the composite conductor can successfully replace solder for surface mount and chip on board assembly. These reliable, highly thermally and electrically conductive materials are compatible with standard metal finishes and can be adopted piecemeal as desired; however, the largest reliability and cost benefit is realized when all of the elements are used in conjunction. The conductor materials are based on interpenetrating polymer and metal networks that are formed in situ from metal particles and a thermosetting flux/binder.