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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.52  No.1 (2011)  >  pp.54-60

<<Previous article Vol.52  No.1 (2011)   pp.54 - 60 Next article>>

Effect of Zinc Content on Microstructural Evolution and Electrification-Fusion-Induced Failure Mechanism of Sn-xZn Alloys

Gong-An Lan1), Chung-Wei Yang2), Truan-Sheng Lui1) and Li-Hui Chen1)
1) Department of Materials Science and Engineering, National Cheng Kung University
2) Department of Materials Science and Engineering, National Formosa University

Microstructural features of Sn-xZn alloys with varying Zn content of 7, 9, 20, 30 mass% on the electrification-fusion phenomenon were investigated in this study. Experimental results showed that the critical fusion current density (CFCD) of Sn-xZn alloys increased with increasing Zn content. The enrichment of Zn-rich phase was the main factor in the improvement of electrical conductivity and the required electrical current density for triggering microstructural evolution for the hypereutectic Sn-30Zn alloy was much higher than the hypoeutectic Sn-7Zn alloy. There is an obvious difference in the increase rate of CFCD from the hypoeutectic composition (Sn-7Zn) to the eutectic composition (Sn-9Zn) due to the microstructural evolution with increasing Zn content. Through the in-situ examination of microstructural evolution during electrification-fusion tests, the initial site of electrification-fusion-induced failure was significantly emerged from the Sn/Zn eutectic phase for both the hypoeutectic composition (Sn-7Zn) and the hypereutectic composition (Sn-30Zn). The fusion behavior of Sn-7Zn was dominated by double massive fusion regions on Sn/Zn eutectic phase and β-Sn phase, whereas the fusion behavior of Sn-30Zn was dominated by massive fusion regions only on Sn/Zn eutectic phase.

lead free solder, electrification-fusion effect, critical fusion current density, in-situ examination, microstructural evolution

Received: August 04, 2010
Accepted: October 08, 2010 , Published online: December 25, 2010
Copyright (c) 2011 The Japan Institute of Metals



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