Influence of Curing Procedures on the Electrical Properties of Epoxy-Based Isotropic Conductive Adhesives

A typical isotropic conductive adhesives (ICAs) composed of an epoxy-based binder containing micro-sized silver flakes was prepared and the effects of different curing procedures on the electrical properties of the ICAs were investigated. The results show that there is greater influence of the curing temperature on 55wt% silver loading, the volume resistivity of ICAs decreases to 4.5x10(-3) Omega.cm from 5.2x10(-2) Omega.cm cured at 250 and 180 degrees C, respectively. However, there is almost no effect on the high silver loading. The variations in electrical resistance of the ICAs with 65wt% silver loading was in situ monitored during the curing process, and it is found that the resistance reaches to 1.99x10(6) Omega at 180 degrees C after cured for 27 min, 1.39 x10(-3) Omega for 40 min, and 18.8 Omega for 60 min and the cooling process has almost no effect on the electrical resistance of the ICAs. The reasons for the dependence of the bulk resistivity on temperatures were also discussed in terms of the dispersing of the silver flakes in ICAs by SEM.