Thermal cycling fatigue analysis of SAC387 solder joints

In this study, finite element analysis (FEA) was used to simulate a thermal cycling test result for a PBGA assembly with Sn-3.8Ag-0.7Cu solder joints subject to thermal cycling of -40°C to +125°C. The PBGA assembly was modeled using a 3D-quarter 1/8th octant model of the PBGA assembly. Two constitutive models for the SAC387 solder were investigated using the Anand Viscoplastic (AV) model and elastic-plastic-creep (EPC) model. Low cycle fatigue life prediction based on non-linear Plastic work (PLWK) and inelastic strain energy density (SED) were used to predict the thermal cycling fatigue life and compared to the test results. Volume averaging studies are needed to quantify the effect of the volume of elements selected on the non-linear Plastic work (PLWK) and inelastic strain energy density (SED), and fatigue life results