Investigation of fracture behaviors of Cu-Sn intermetallics using impact test

It is well known that high temperature thermal aging can increase the thickness of the IMC layer of a solder joint and, consequently, the mechanical strength of the solder joint is reduced. Yet there is still no conclusive explanation that can answer the question why the growth of IMC layer can reduce the strength of solder joints. In this study, the fracture energies of the Cu-Sn IMC layer after various periods of thermal aging were compared using the impact test method. Detailed fractographic analysis was also performed. In addition, the brittle failure of solder joints under high speed ball pull tests was analyzed for comparison.