Corrosion Study of Sn-9Zn Lead-Free Solder in Alkaline Solution

Abstract

The corrosion potential and current of Sn-9Zn/Cu in 6 M KOH solution was investigated. The potential abruptly increases with increased immersion time before saturation at -1120 mV. The corrosion current drops significantly until it reaches a stable value at 10 μA. Morphological and elemental analyses reveal the formation of oxides on the surface after immersion. The post-immersion solder joint displays 22% reduction in ultimate tensile strength as a result of Sn and Zn consumption during the production of corrosion products at the bulk solder region of the Cu/Sn-9Zn/Cu butt joint.