Sintered conductive adhesives for high temperature packaging

There is a growing need for high-conductivity and high-temperature stable conductive adhesives in a variety of electronic packaging applications. Void-free bondlines combined with low mechanical stiffness make conductive adhesives an attractive alternative to solders. The majority of conventional silver-filled conductive adhesives, however, have interfacial resistance characteristics that limit their utility in many applications. We report on the development of transient liquid phase sintering (TLPS) adhesives that are embodied and processed like conventional conductive adhesives but that have thermal and electrical characteristics closer to solders. These solvent-free materials are composed of fluxing polymeric binders and a mixture of low and high melting point metals that are designed to liquid phase sinter during cure. The result is bondlines with low interfacial resistance and high effective thermal and electrical conductivity. Further, the cure-profiles of these materials can be tailored to facilitate low-temperature rework or to establish high-temperature stability.