Effects of solder solidification temperature on residual stress distribution and failure location in BGA solder joints

This study investigates how the solder solidification temperature affects residual stress distribution and failure locations in BGA solder joints, aiming to provide insights that enhance solder alloy selection and reflow process optimization. Through experimental thermal cycling tests on BGA208 assemblies using SAC305 (∼220 °C) and Sn37Pb (∼180 °C) solder alloys, subjected to temperatures ranging from −40 °C to 125 °C, we found that SAC305 assemblies predominantly failed at corner joints due to warpage stresses. In contrast, Sn37Pb assemblies failed at second-row joints under the die edge due to shear stresses. These results were validated by Finite element analysis (FEA) simulations, which showed that higher solidification temperatures, as in SAC305, resulted in higher residual stresses and maximum stresses at corner joints, whereas lower solidification temperatures, as in Sn37Pb, shifted stress concentrations to non-corner joints. These results underscore the critical role of the solidification temperature in determining failure locations and provide valuable insights for improving the reliability of BGA components in electronic applications.