Fundamental study on adhesive strength of electrical conductive adhesives (ECAs)

Electrical conductive adhesives (ECAs) are perceived as the next generation interconnection materials, for printed wiring boards (PWBs) and electronic packaging. Poor adhesive strength and weakness in impact resistance obstructs the wide application of the ECAs. For this reason, fundamental studies for ECAs are needed. In this paper, relationships between the orientation of silver flakes in epoxy ECAs and the adhesive strength were investigated. Two kinds of processes to randomize the orientation of silver flakes were proposed. The randomization of silver flakes orientation was found to be effective in improving the adhesive strength. Novel non-Au/Pd sputtering SEM technique was proposed. By this technique, the conductive path of ECAs was easily identified. The edges of the silver flakes and small particles in the ECAs were found to be very effective in electrical contact that illustrated the non-Au/Pd sputtering SEM study.