Effect of high-speed loading conditions on the fracture mode of the BGA solder joint

High-speed ball shear test was investigated in terms of the effects of two test parameters, shear speed and shear height, with an experimental and computational simulation utilizing 3-dimensional non-linear finite element modeling for evaluating the solder joint integrity of ball grid array (BGA) packages. A representative Pb-free solder alloy, Sn–0.7Cu, 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. These were discussed with the strengthening mechanism of the solder materials by density and mobility of dislocations. 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.