The conduction development mechanism of silicone-based electrically conductive adhesives

Abstract

The conduction development mechanism of silicone-based electrically conductive adhesives (Silo-ECAs) is studied. The reduction of surfactants on silver flakes by hydride in the silicone backbone and the subsequent sintering of the generated silver nanoparticles between micron-sized silver flakes are found to be the major contributor to the conductivity development in Silo-ECAs; this is in contrast with the mechanism observed in most polymer–metal ECAs, where the curing shrinkage of the polymer matrix is the major cause of conductivity development. The conductivity development in Silo-ECAs ceases when the polymer curing is completed. Hence, in order to enhance the resulting electrical conductivity, the curing process is prolonged by using a long-chain prepolymer, lowering the platinum catalyst concentration, or adding curing inhibitors. A bulk resistivity of 8.82 × 10⁻⁵ Ω cm is achieved, which is 55% lower than the best values reported previously for Silo-ECAs.