Failure mechanism of Ag-4Pd alloy wire bonded on Al-Si metallization under high temperature storage and thermal cycle tests in corrosive environments

This study investigated the failure mechanism of Ag-4Pd wire bonded on Al metallization under chlorine corrosive environments after high temperature storage tests (HTST) and thermal cycle tests (TCT). Results show that as-bonded samples encountered the fastest failure, caused by corrosion of Al metallization accelerated by galvanic corrosion. For HTST samples, the intermetallic compound (IMC) layer was corroded and separated into the upper layer of Ag2Al and Ag3Al and the lower layer of Ag3Al2. The non-continuous Ag3Al2 IMC layers in TCT samples can act as a barrier to inhibit the galvanic corrosion and effectively retard the corrosion rate of Al metallization.