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Cruciform pattern formation in Sn/Co couples

Published online by Cambridge University Press:  31 January 2011

Chao-hong Wang  and
Sinn-wen Chen
Chao-hong Wang
Affiliation:
Department of Chemical Engineering, National Tsing Hua University, Hsin-chu, Taiwan 300
Sinn-wen Chen
Affiliation:
Department of Chemical Engineering, National Tsing Hua University, Hsin-chu, Taiwan 300
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Abstract

CoSn3 phase is formed in Sn/Co couples reacted at 200 °C. The reaction phase shows a unique cruciform pattern that is observed for the first time in the solid/solid reaction. The reaction phase layers are thick and uniform along the edges of the Co substrate, and there are no reaction phases at the corners. A continuous reaction layer is formed in Sn/Co couples reacted at 180 °C. A metastable CoSn4 phase is formed at the corner, and the reaction phase along the edge of the Co substrate is the CoSn3 phase. The reaction CoSn3 phase region shows a cruciform pattern if the CoSn4 phase region is ignored. It is concluded that the Sn flux is much faster than the Co flux, and the cruciform pattern of the reaction CoSn3 phase layer is formed either by cracking or transformation to the CoSn4 phase at the corners where stresses are most intensified.

Keywords

MicrostructureSolderingSn
Type
Articles
Information
Journal of Materials Research , Volume 22 , Issue 12 , December 2007 , pp. 3404 - 3409
Copyright
Copyright © Materials Research Society 2007

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