Electrochemical corrosion behavior of Sn-0.7Cu solder alloy with the addition of bismuth and iron

Abstract The corrosion behavior of Fe and Bi added Sn-0.7Cu solder was investigated in 3.5 wt% NaCl solution. Addition of Fe and Bi results in higher corrosion current density, reduction in passivation and pseudo passivation domain. Formation of FeSn2 continuously forces the Sn to dissolve, forming SnCl2 and SnCl4. This process generates electric current flow, resulting in a rougher surface. Rougher corrosion products were observed on the surface of modified alloys. The presence of a Bi-rich phase results in galvanic action between Bi and Sn. EIS results show higher capacitance and lower overall electrical resistivity of the modified alloys.