Failure behaviors of BGA solder joints under various loading conditions of high-speed shear test

Failure behaviors of ball grid array (BGA) solder ball joints under various loading conditions of high-speed shear test were investigated with an experimental and non-linear 3-dimensional finite element modeling work. A representative Pb-free solder alloy, Sn-3.0Ag-0.5Cu, was employed in this study. Far greater shear forces were measured by high-speed shear test than by low-speed shear test. The shear force further increased with shear speed mainly due to the high strain-rate sensitivity of the solder alloy. Brittle interfacial fractures can be more easily achieved by high-speed shear test, especially in higher shear speed. This was discussed with the relationship between the strain-rate and work-hardening effect and resulting stress concentration at interfacial regions. Shear force decreased with shear height, and it could be found that excessively high shear heights unfavorably affected the test results leading to unexpectedly high standard deviation values or shear tip sliding from the solder ball surface.