Reliability of Au-Ag alloy wire bonding

Au-Ag alloy wire is a low cost wire bonding solution instead of gold wire for IC packaging. Comparing with copper wire, Au-Ag wire has better productivity because it does not need protective gas and it is softer. The main issue of Au-Ag alloy wire bonding is its reliability in humidity environment. In present study, the bond parameters effect on PCT reliability was investigated. The correlation between the IMC profile and PCT lifetime was established. The IMC characteristic length was defined to express the relationship quantitatively. Meanwhile, The Au-Ag-Al IMC growth equation was obtained through HTS. It is found that the IMC growth rate is slower one order of magnitude than 99.99% gold wire.