Effect of trace Mn modification on the microstructure and corrosion behavior of Sn−9Zn solder alloy

Abstract

The effect of trace Mn modification (0.05–0.1 wt%) on the microstructure and corrosion behavior of Sn–9Zn solder alloy in 0.5 M NaCl solution (pH 5.8) was evaluated by electrochemical techniques complemented with surface characterization. Mn could refine the Zn‐rich precipitates and facilitate forming of a new ternary precipitation phase containing higher amount of Mn element. Impedance results reveal that trace Mn modification improves the corrosion resistance of Sn–9Zn alloy in the solution. As a result, both cathodic and anodic reaction rates were reduced. Moreover, Mn notably enhances the stability of the passive films formed on the modified alloys with respect to a lower passive current density to maintain the passive state. Mott–Schottky analysis shows that the passive films exhibit n‐type semiconducting properties and the donor density decreases with Mn addition. The mechanism by which Mn influences the corrosion resistance of Sn–9Zn alloy can be explained in terms of the differences in both microstructure of the alloy and in semiconducting properties of the passive films.

Recent research progress on the passivation and selective oxidation for the 3d-transition-metal and refractory multi-principal element alloys

“…It has been found that the passive film formed on the equiatomic CrMnFeCoNi alloy was more defective than that formed on the equiatomic CrFeCoNi alloy, which meant that Mn addition facilitated the formation and migration of oxygen vacancies in the passive film 29,89 . However, for other MPEAs, such as Sn 91 Zn 9 alloy, Mn alloying can markedly reduce the donor densities of the passive films and enhance their stability 90 .…”

Review on Corrosion in Electronic Packaging Trends of Collaborative between Academia–Industry

“…Application of phase growth approach to prediction of thermal fatigue crack initiation lifetime in SN-3.0AG-0.5CU solder joints [93] Collaboration works in Japan between COSEL Co., Ltd., Machinery and Electronics Research Institute and Toyama Prefectural University. Effect of trace Mn modification on the microstructure and corrosion behavior of Sn-9Zn solder alloy [110] Collaboration works in China between China Ship Development and Design Center and Tsinghua University. Corrosion of Ga-doped Sn-0.7Cu solder in simulated marine atmosphere [105] Ab initio surface properties of Ag-Sn alloys: Implications for lead-free soldering [112].…”

Effect of relative humidity on the corrosion behavior of Sn–0.7Cu solder under polyvinyl chloride fire smoke atmosphere

“…Solders play an important role in electrical and mechanical connections that are a part of the electronic packaging. [ 1–3 ] Sn–Pb solder is a traditional and widely used electric material, as it is economical and it has a lower melting point, good corrosion resistance, good wettability, and appreciable mechanical properties, [ 4,5 ] but its use has been restricted since July 1, 2006, due to lead toxicity, by the implementation of the European Union's Restriction of Hazardous Substances Directive. [ 6,7 ] Sn–0.7Cu solder, a lead‐free solder, has been used as the most promising alternative for commercial use, such as wave soldering, due to its low cost, availability, nontoxicity, and perfect thermal fatigue life.…”