The effect of electromigration (EM) on Sn(Cu)/Ni/Cu solder joint interfaces under current stressing of 10(4) A/cm(2) at 160A degrees C was studied. In the pure Sn/Ni/Cu case, the interfacial compound layer was mainly the Cu6Sn5 compound phase, which suffered serious EM-induced dissolution, eventually resulting in serious Cu-pad consumption. In the Sn-0.7Cu case, a (Cu,Ni)(6)Sn-5 interfacial compound layer formed at the joint interface, which showed a strong resistance to EM-induced dissolution. Thus, there was no serious consumption of the Cu pad under current stressing. In the Sn-3.0Cu case, we believe that thea massive pound Cu6Sn5 phase in the solder matrix eased possible EM-induced dissolution at the interfacial compound layer due to current stressing.
