Microstructure refinement, characterization of tensile behavior and aging resistance of Zr-modified SAC105 solder alloy

In this study, 0.2wt% zirconium (Zr) added Sn-1.0Ag-0.5Cu (SAC105) lead-free solder alloy was prepared and its microstructure, tensile property, and aging stability were investigated and compared with the original SAC105 solder alloy. The SAC105 and SAC105-0.2Zr solder alloys were fabricated by vacuum induction melting method. The results showed that the Zr-added SAC105 solder exhibited a significantly refined microstructure. The primary -Sn phases, Ag3Sn particle size, and spacing of Ag3Sn had been obviously reduced with the addition of trace amounts of Zr. The tensile test demonstrated that both strength and elongation of the SAC105-0.2Zr solder improved because of the finer microstructure. Isothermal aging was performed at 180 degrees C for 36h, 84h, and 156h. The existence of Zr could significantly inhibit the coarsening of the Ag3Sn phases, thus enhancing the microstructure stability under severe aging conditions. Moreover, the Zr-added SAC105 solder showed significant decrease in supercooling, but the melting range was almost unchanged.