Influence of Pt Addition on Corrosion Resistance of Sn-9Zn-0.02Al-xPt Solder Alloys

The corrosion behaviour and mechanism of Sn-9Zn-0.02Al-xPt alloys were investigated. The addition of Pt significantly enhanced the corrosion resistance of the alloy, as evidenced by two key observations at different additive levels: (1) With a minor addition of Pt, the reduced potential difference between the small-sized Zn-rich phase and the eutectic phase decreased the galvanic corrosion sensitivity, and (2) with a large addition of Pt, the anodic barrier effect of the noble Pt2Zn10.72 phase and the consumption of Zn significantly protected the anodic Zn. The corrosion resistance increased in the order: Sn-9Zn-0.02Al-0.03Pt < Sn-9Zn-0.02Al < Sn-9Zn-0.02Al-0.01Pt, Sn-9Zn-0.02Al-0.1Pt < Sn-9Zn-0.02Al-0.25Pt.