Strain-rate and impact velocity effects on joint adhesion strength

In this paper, numerical studies are carried out on high-speed cold ball pull test by using explicit transient finite element simulations to predict transient response of package-level solder ball subjected to pull loads. The material constitutions of solder alloys are obtained from quasi-static tensile test and Hopkinsonpsilas bar test. Erosion technique is adopted for simulations of bulk solder fracturing, and interfacial element for intermetalic compound (IMC) fracturing. Parameter studies on pull velocity effect as well as strain-rate effect are also carried out. Transition points of pull velocity between bulk solder fracturing mode and IMC fracturing mode are identified therefore. From simulation results, transform relationship between pull forces to joint adhesion strengths of solder joints can be set up.