Relieving Sn whisker growth driven by oxidation on Cu leadframe by annealing and reflowing treatments

C. C. Wei, P. C. Liu, Chih Chen*, Jeffrey C.B. Lee, I. Ping Wang

*Corresponding author for this work

研究成果: Article

22 引文 斯高帕斯(Scopus)

摘要

Owing to environmental concern, Pb-free solders are replacing eutectic tin lead in electronic packaging industry. Thus, whisker growth becomes a serious reliability issue for Sn finishes. In this study, the mechanism of whisker growth from Sn finish on Cu leadframe was investigated under the temperature/humidity storage test. It is found that oxidation of the Sn finish was the driving force behind the whisker growth. Thermal treatments including annealing at 220 °C and reflowing at 260 °C were employed to mitigate the whisker growth. It is found that both heat treatments can significantly reduce the whisker growth rate. It is speculated that the heat treatments can relieve the residual stress in the Sn finishes and can modify their grain structure, resulting in a slower oxidation rate. Thus, they can slow down the grow rate of Sn whiskers. In addition, reflowing treatment can change the columnar grain structure of the Sn film to the equiaxed grain structure in some of its regions, resulting in a lower grain boundary diffusion rate of Sn. Therefore, the reflowed sample had the lowest growth rate of Sn whiskers.

原文English
文章編號043521
期刊Journal of Applied Physics
102
發行號4
DOIs
出版狀態Published - 7 九月 2007

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