Current-induced weakening of Sn3.5Ag0.7Cu Pb-free solder joints

Weakening of Pb-free solder joints by high-density electric currents was investigated by combining electromigration experiments with micromechanical testing. Prolonged exposure of the Sn3.5Ag0.7Cu/Cu interconnects to electric currents resulted in hillock formation on the sample surface. After electromigration, the strength of the solder joint was reduced by nearly half. However, the strength loss was recoverable by thermal annealing of the electromigration damage.