Strain-rate effects on mechanical properties for SAC387 and SAC105-Y solder

In this paper, solder alloy of Sn-3.8Ag-0.7Cu (SAC387) and Sn-1.0Ag-0.5Cu-Y (SAC105-Y), where Y is a small addition of a fourth element, were tested at room temperature to study the strain-rate-dependent elastic modulus and yield strength of the solder. Nano-indentation tests were conducted at various strain rates from 10^-3 to 10¹ 1/s by using the continuous stiffness measurement (CSM) technique. Microstructures of the IMC for SAC105-Y on NiAu surface finish and OSP surface finish were investigated prior to the nano-indentation tests. Based on the test results, the higher the strain rate the higher the elastic modulus and yield stress of the solder. The power law relationship is used to curve fit the strain-rate-dependent yield stress with the indentation strain rate.