Electromigration-induced cracks in eutectic SnPb solder reaction couple at room temperature

Research paper by G. C. Xu, H. W. He, F. Guo

Indexed on: 24 Apr '08Published on: 24 Apr '08Published in: Journal of Materials Science: Materials in Electronics


Electromigration (EM) of 63Sn–37Pb solder reaction couple was studied under high current density of 5 × 103 A/cm2 at room temperature. There was non-uniform distribution of current density across the linear specimen, and the dissimilar interface of two different materials could trigger current crowding especially at the edge of the interface. Though the atoms/ions of Sn and Pb would migrate along the direction of electron flow pushed by electron wind force, the Sn atoms were observed to be the principal diffusion entities at room temperature. Depletion of mass at cathode side induced the tensile stress along parallel direction of the specimen cross-section, while the accumulation of mass at anode side induced the compressive stress along the perpendicular direction of the specimen cross-section. Crack initiation and propagation in both cathode and anode side was found to be strongly dependent on the current density distribution.