Study on Oxidation of Lead-Free Sn Alloys by Electrochemical Reduction Analysis

The oxidation of pure Sn and Sn-0.7Cu, Sn-3.5Ag, Sn-1Zn, and Sn-9Zn alloys at 150 degrees C was investigated. Both the chemical nature and the amount of oxides were characterized using electrochemical reduction analysis by measuring the electrolytic reduction potential and total transferred electrical charges. X-ray photoelectron spectroscopy (XPS) was also conducted to support the results of reduction analysis. The effect of Cu, Ag and Zn addition on surface oxidation of Sn alloys is reported. For Sn, Sn-0.7Cu and Sn-3.5Ag, SnO grew first and then the mixture of SnO and SnO2 was found. SnO2 grew predominantly for a long-time aging. For Zn-containing Sn alloys, both ZnO and SnO2 were formed. Zn promotes the formation of SnO2. Sn oxide growth rate of Pb-free solder alloys was also discussed in terms of alloying elements.

By: Sungil Cho; Jin Yu; Sung K. Kang; Da-Yuan Shih

Published in: JOM - Journal of the Minerals Metals and Materials Society, volume 57, (no 6), pages 50-52 in 2005

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