The Dependence on Thermal History of the Electrical Properties of an Epoxy-Based Isotropic Conductive Adhesive

The effect of thermal history on the electrical resistivity of a typical isotropic conductive adhesive (ICA) composed of an epoxy-based binder has been investigated in the present work. The electrical resistivities of test specimens were found to be different depending on the curing temperature, even if they exhibited similar degrees of conversion, although the values of Tg for the ICA specimens were determined by their degree of conversion, regardless of the curing temperature. Postannealing effects in terms of decreased electrical resistivity could be induced at a temperature in the vicinity of the glass transition temperature (Tg), even if the specimens already achieved full conversion during the preliminary curing process. The magnitude of the annealing effect was found to depend on the preliminary curing and postannealing temperatures. When the specimens exhibit conversions of greater than 25% prior to the postannealing process, the preliminary curing state of the binder can influence the electrical resistivity of the ICA that is obtained after annealing.