Influence of stress on the electromigration life of solder

It was suggested that electromigration (EM) life of solder can be improved by proper choice of stress property (compressive or tensile) at the two corners where electron current enter and exit. In this paper, we investigated this problem systematically by experiment and finite element simulation. The experimental results show that, compared with the case of tensile stress, the meantime to failure (MTTF) of solder will be slightly longer if the stress at the current entrance and exit are compressive. The finite elemental simulation results show that the arising rate of vacancy density at cathode corner will be the lowest if the stress here is compressive and the stress at anode corner is tensile, and the reverse is the worst case, while the other two cases as we verified in the experiment are intermediate. But in general, the differences in arising rate of vacancy density at cathode corner of solder and thus the influence of stress on electromigration life of solders are not obvious.