Mechanical Deformation in Conductive Adhesives as Measured With Electron-Beam Moiré

Abstract

Two forms (paste and film) of isotropically conductive adhesives (CAs) were mechanically loaded in shear mode. The specimens were instrumented with crossed-line gratings so that normal and shear displacements could be measured. The CA paste specimen failed outside the observed region at a stress 28 percent below the manufacturer’s predicted value. In the observed region there were no normal strains, only shear strains restricted to the CA. In the film specimen the conducting particles began breaking away from the matrix epoxy at very low loads. However, the specimen continued carrying the additional loading increments until the load was transferred to the adjacent material.