ELECTROMIGRATION OF SNPB FLIP CHIP SOLDER BUMPS WITH THICK NI/CU UNDER BUMP METALLIZATION

摘要

Flip Chip Technology is one of the most important packaging methods for high current density IC device. As the applied current density continues to increase, electromigration in solder joint has become a critical issue on device reliability [1]. Concerning electromigration, the device design rule requires each solder bump to carry 0.2A to 0.4A. Thus the current density will reach 103~104A/cm2. There is still little study on solder EM with thick UBM structure (Ni/Cu). In this study, electromigration in SnPb solder with thick under bump metallization (UBM) is investigated at 105~106A/cm2 at 150. Failure mechanism was found to be UBM consumption. Solder dissolution accelerates continuous IMC formation, and continues redistribution between Sn and Pb was found. The findings in TTF, Sn80Pb20 is significant longer than e-SnPb. In addition, the temperature and current distribution due to the IMC formation was correction by simulated to prove Black’s equation.