A study of board level reliability test with bump structure of WLCSP lead-free solder joints

With the increasing market demands of electric products for smaller, thinner, faster, and cost-effectiveness, the wafer-level chip-scale package (WLCSP) is the perfect solution and has already proven in a number of electron applications. In this study, the board level solder joint reliability (SJR) with different bump structure were investigated in WLCSP, drop test is intended to evaluate and compare drop performance of surface mount electronic components for handheld electronic product applications in an accelerated test environment, where excessive flexure of a circuit board causes product failure. Another concern in solder joint reliability is the failure due to loading with cyclic stresses, temperature cycling test (TCT) is therefore an important index of board-level solder joint reliability progress. Cross-section SEM analysis was done and showed that the fracture after broad-level reliability test is solder joint failure.