Abstract: The influence of electromigration on tensile mechanical behaviors of low-Ag lead-free microscale solder joints was characterized under different current densities (0.63~1.0×10⁴ A/cm²) and holding time (0~48 hours).The experiment results show that tensile strength of low-Ag lead-free microscale solder joints is obviously degraded by electromigration, and the increase in both current density and holding time leads to a decrease of tensile strength of the microscale solder joints. In addition, electromigration induces fracture mode transition phenomena at the cathode interface of the solder joints, that is, from ductile fracture in the solder joints without electromigration to brittle fracture for those after strong electromigration using high current density and long holding time. Also, higher Ag content in the low-Ag lead-free microscale solder joints will improve electromigration resistance.