Cure kinetics and mechanical properties of conductive adhesive

Abstract

The curing reaction of a conductive adhesive was studied with a differential scanning calorimeter (DSC) under isothermal conditions in the range of 100-160/spl deg/C. An autocatalyzed kinetic model was used to describe the curing reaction. The rate constant and the reaction orders were determined and used in the model to predict the progress of the curing reactions. A good agreement is found between the proposed kinetic model and the experimental reaction rate data. The reaction rate constants were correlated with the isothermal temperature by the Arrhenius equation. The activation energy for the curing reaction is determined to be 94.9 kJ/mol. The reaction order which represents the effects of the unreacted materials is found to be a parabolic function of temperature. But the effects of the reacted materials on the reaction rate change sharply at around 120/spl deg/C. Unlike some previous results on epoxy curing kinetics, the sum of the two reaction orders is not a constant for this conductive adhesive. Thermogravimetric Analyzer (TGA) was used to study the weight loss during thermal processes. The degradation temperature of the conductive adhesive was found to be 250/spl deg/C. The properties of the corresponding unfilled epoxy were also studied with the DSC and TGA. Results were compared with those obtained from the conductive adhesive. Tests were conducted to investigate the mechanical and electrical property changes during cure.