Study of curing process of electrically conductive adhesives using differential scanning calorimetry

Abstract

Differential scanning calorimetry has been used to verify quality of curing of nine formulations of electrically conductive adhesive based on epoxy resin matrix filled with silver flakes. Three formulations have been added with low concentration of silver nanoparticles. The measurement has been performed in addition to the measurement of tensile strength and shear strength of thermally aged adhesive joints, since it has been found that mechanical properties of some joints have improved after thermal ageing provided at the temperature of 125 °C for 300 hours. This could suggest an imperfect cure of adhesives despite the fact that adhesives have been cured according to instructions of a manufacturer. It has been found, by the use of DSC that exothermic reactions associated with additional hardening of adhesive occur for some formulations during the initial stage of thermal ageing. This means that the curing schedules for these adhesives, recommended by a manufacturer, have not been optimal. Such way cured adhesives have worse electrical and mechanical properties.