Effects of Zn addition on mechanical properties of eutectic Sn-58Bi solder during liquid-state aging
(1. Department of Applied Physics, Institute of Advanced Materials Physics,
Faculty of Science, Tianjin University, Tianjin 300072, China;
2. Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology,
Tianjin University, Tianjin 300072, China)
Faculty of Science, Tianjin University, Tianjin 300072, China;
2. Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology,
Tianjin University, Tianjin 300072, China)
Abstract: Interfacial reaction, tensile strength and creep resistance of Sn-58Bi-xZn (x=0, 0.7, mass fraction, %) solder samples during liquid-state aging were investigated. The coarsening of Bi and the growth of Cu-Sn intermetallic compounds (IMCs) in Sn-58Bi-0.7Zn solder sample were both effectively suppressed. With the addition of 0.7% Zn, ultimate tensile strengths (UTSs) of the Sn-58Bi solder slabs were respectively increased by 6.05% and 5.50% after reflow soldering and liquid-state aging, and those of the Cu/Sn-58Bi/Cu solder joints were also increased by 21.51% and 29.27%, respectively. The increase in strengthening effect of Cu/Sn-58Bi-xZn/Cu solder joints could be attributed to the fracture surface which was changed from the Cu/IMC interface to the IMC/solder interface due to the finer Bi grain. Nanoindentation results revealed that the creep behavior of Sn-58Bi-0.7Zn solder was significantly improved compared with that of the eutectic Sn-58Bi solder after reflow soldering and liquid-state aging.
Key words: Zn; Sn-Bi solder; liquid-state aging; reflow soldering; creep