Dynamic material characterisation of solder interconnects in microelectronic packaging

Abstract

An Investigation of quasi-static and dynamic properties of Sn-37Pb solder and two lead-free solder materials, Sn-3.5Ag and Sn-3.8Ag-0.7Cu was carried out using the split Hopkinson pressure bar (SHPB). Each solder was cast at three different cooling rates (slow cooling, moderate cooling and quench cooling) to understand how microstructure and material response change with the variation of rate of solidification of these solders. A Finite Element analysis software simulation of the SHPB experiments on single balls was performed using the bulk dynamic material properties to assess how well the bulk material response obtained in experiments represents actual solder deformation.All dynamically deformed materials show a distinct increase in yield strength and flow stress as compared to their quasi-static properties. Simulations using both dynamic and quasi-static material of solder demonstrate better reflection of solder ball response in SHPB experiments.