Microstructure-electromigration correlation in a thin stripe of eutectic SnPb solder stressed between Cu electrodes

Room-temperature electromigration occurs in a thin stripe of eutectic SnPb solder stressed by a current density of 105 amp/cm2. Hillocks and voids grow at the anode and the cathode, respectively. While the dominant diffusion species is Sn in this two-phase alloy, the growth of the hillocks, surprisingly, originates from the Pb grains.