Effect of electric current stressing on mechanical performance of solders and solder joints: A review

Mechanical performance is one of the most important factors influencing the reliability of solder joints. Heretofore, plenty of works have been conducted on reliability of solder joints under various mechanical loads. However, with the miniaturization of electronic products, the current density flowing through the solder joints is increasing. Electric current stressing can induce microstructure evolution, and mechanical performance of solder joints may be altered consequently, which leads to electric current stressing becoming an important factor affecting the mechanical reliability of solder joints. Therefore, this review focuses on summarizing the influence of electric current stressing on the mechanical performance, which involves tensile, shear, creep, fatigue and thermal cycling, shock, vibration and nano-indentation performances, of solder and solder joints. Moreover, the mechanical performance of solders and solder joints can be tested after and concurrent with electric current stressing. Although the mechanical test of solders and solder joints with electric current stressing is more valuable for assessing the serving reliability of solder joints, the mechanical test of solders and solder joints after electric current stressing can be inspiring and enlightening for clarifying the failure mechanism of solder joints in the former condition. Therefore, they will be elaborated separately and sequentially in this review. Furthermore, the remained key issues and possible research directions on the current topic are also pointed out. Graphical abstract