Electromigration-Induced Failure of Low-Temperature Sn-57Bi-1Ag Solder Interconnect Under Low Frequency Pulsed Direct Current Stressing

The electromigration behavior of low- temperature Sn-57%Bi-1%Ag (wt.%) solder interconnects subjected to the low frequency pulsed direct current stressing was investigated. The pulsed direct current stressing induced damages in low-temperature Sn-57Bi-1Ag solder interconnects. Subsequently, the melting of solder in the center of interconnects occurred, and consequently leading to the failure of solder interconnects induced by the liquid-solid electromigration. Bi-rich layer (12.6 μm) at the anode of solder interconnects under 75 % duty factor (DF) was thicker than those of solder interconnects under 25 % and 50 % DF (4.8 and 8.2 μm, respectively). However, the average lifetime of solder interconnects under 75 % DF was 150.4 h, which was longer than those of solder interconnects under 25 % and 50 % DF (35.8 and 51.0 h, respectively). As the duty factor decreased, the electromigration lifetime of solder interconnects was significantly shortened, which was attributed to the fatigue stress caused by the pulsed direct current stressing.