The Influence of Electromigration and Aging on the Reliability of SnAgCu Lead-Free Solder Joint at 100°C

The butting solder joint of Cu/Sn-3.0Ag-0.5Cu/Cu was used to investigate the evolution of the intermetallic compound (IMC) and the degradation of the tensile strength of solder joint in this paper with different electromigration and aging time by scanning electron microscopy equipped with energy dispersive spectrometer and micromechanical testing. Meanwhile, the fracture of solder joint was also evaluated. The results show that under the condition of electric current density for 1.78×10⁴A/cm² and test temperature at 100°C, with increasing of electromigration time, the growth of interfacial IMC presents an obviously polarity effect. The IMC thickens at anode and thins at cathode, and the evolvement of the IMC at anode follows a parabolic growth rule. Meanwhile the ultimate tensile strength of the solder joint declines continuously and the fracture mode gradually transforms from plastic fracture to brittle fracture. For aging at 100°C without current stressing, the growth of interfacial IMC was more slowly and the decrease of tensile strength was less.