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Advances in Materials Science and Engineering
Volume 2014, Article ID 606814, 10 pages
Research Article

The Effects of Gallium Additions on Microstructures and Thermal and Mechanical Properties of Sn-9Zn Solder Alloys

1Department of Electronics Engineering and Computer Science, Tung Fang Design Institute, No. 110, Dong Fang Road, Hunei, Kaohsiung 82941, Taiwan
2Department of Aeronautics and Astronautics, Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 70101, Taiwan
3Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan
4Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

Received 19 September 2013; Revised 10 December 2013; Accepted 12 December 2013; Published 22 January 2014

Academic Editor: Tao Zhang

Copyright © 2014 Kang I. Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The effects of gallium additions on microstructures and thermal and mechanical properties of the Sn-9Zn solder alloys are investigated in this study. The results show that the melting temperature of the alloys decreases with the increase in the Ga concentration, while the pasty ranges of the alloys are simultaneously enlarged. By adding a 0.25–0.5 wt.% Ga element, the Sn-matrix region is slightly increased and the Zn-rich phase becomes slightly coarser; however, the overall microstructure is still very similar to that of the Sn-9Zn alloy. It is found that, when the Ga concentration is less than 0.50 wt.%, the ultimate tensile strength and elongation are maintained at the same values. The addition of a 0.25–0.50 wt.% Ga to the Sn-9Zn alloy also leads to small cup and cone fracture surfaces which exhibit near-complete ductile fracturing. With the addition being increased to 0.75 wt.%, larger cup and cone fractures are observed. The 1.00 wt.% Ga alloy has lower strength and ductility due to the coarser and nonuniform microstructures. However, the fracture surfaces of the 1.00 wt.% Ga alloy show partial cleavage and a partially dimpled fracture.