Enhancement of electrical conductivity developed in an epoxy-based adhesive with silver flakes loading

Effect of binder chemistry on the electrical conductivity of electrically conductive adhesives (ECAs) composed of an epoxy-based binder containing 5-50 vol% of silver flakes was examined. After curing ECAs at 473 K for 1 h in air, the ECAs containing a reactive diluent showed lower electrical resistivity compared with those containing no reactive diluent. A chemical analysis using pulse NMR spectroscopy suggested domains mainly composed of the reactive diluent molecules preferentially interacts with the filler surface. Electrical conductivity development of ECAs was found to be enhanced by the addition of the reactive diluent during curing. In addition, the addition of reactive diluent was effective to reduce apparent activation energy for electrical conductivity development. These results indicate electrical conductivity can be controlled by interfacial chemistry between the binder and fillers.