Effect of chemical factors on the evolution of electrical conductivity during curing in Ag-loaded conductive adhesives composed of an epoxy-based binder — A new understanding of electrically conductive adhesives

The effect of chemical processes on the evolution of electrical conductivity in a typical electrically conductive adhesive (ECA) composed of an epoxy-based binder containing Ag filler particles has been investigated. The electrical resistivities of the test specimens were found to differ depending on the curing temperature. Moreover, the specimens containing Ag fillers with adipic acid surfactant had significantly lower electrical resistivities. In these specimens, to analyze the behavior of electrical conductivity evolution with temperature, simultaneous measurements of the viscoelasticity and electrical conductivity during curing were taken. The results suggested that interfacial chemical phenomena form inter-filler conductive contacts in the vicinity of the filler surface, and play an important role in determining the electrical conductivity in ECAs. Furthermore, these chemical phenomena were accelerated by increasing the curing temperature and the presence of surfactant in the filler.