Fatigue and failure behaviors of silver-filled electronically-conductive adhesive joints subjected to elevated humidity

摘要

Conductive adhesives are used in electronics packaging applications for hybrid,die-attach and display assemblies.There are a number of issues of concern in the design of joints bonded using electronically-conductive adhesives (ECAs).An important issue is the cyclic fatigue behavior of conductive adhesive joints under elevated humidity environments,in which failures may occur due to cyclic mechanical and/or thermal stresses.This paper addresses the effect of elevated humidity levels on the fatigue and failure behaviors of ECAs.For this purpose,joints were prepared using stainless-steel adherend specimens and a commercial ECA,and tested under monotonic and cyclic fatigue conditions,at two humidity levels,namely 20% and 90% relative humidity at 28degC.Furthermore,joint failure mechanisms were analyzed using optical techniques,and joint conductivity measurements.Load versus number of cycles (P-N) curves were generated using these specimens at three different load ratios (R),namely 0.1,0.5 and 0.9,at a cyclic frequency of 150 Hz.The P-N curves were parallel and the failure modes were found to be predominantly interfacial,accompanied by a significant decrease in joint conductivity.