Effects of In and aging treatment on the microstructure, mechanical properties and electrochemical corrosion behavior of Sn2Cu solder alloy

This paper aims to investigate the effects of In and aging treatment on the microstructure, mechanical properties and electrochemical corrosion behavior of Sn2Cu solder alloy. It is found that In could refine the β-Sn grains, resulting in an improved microstructure and enhanced microhardness and tensile properties. Moreover, adding In lowered the undercooling of the Sn2Cu solder alloy, with a maximum reduction of 5.97 °C. The corrosion resistance of the alloy was also dramatically improved by In addition, as evidenced by: (1) a lower corrosion current density compared to the matrix alloy; (2) a smaller surface roughness and pit depth after corrosion; (3) an increased ratio of SnO2 in the corrosion product layer. On the other hand, aging treatment had an adverse impact on the mechanical properties, but a beneficial influence on corrosion resistance of solder alloy.