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Effects of electromigration on interfacial reactions in cast Sn/Cu joints

Published online by Cambridge University Press:  03 March 2011

Sinn-Wen Chen*
Affiliation:
Department of Chemical Engineering, National Tsing Hua University, Hsin-chu, Taiwan
Chao-Hong Wang
Affiliation:
Department of Chemical Engineering, National Tsing Hua University, Hsin-chu, Taiwan
*
a) Address all correspondence to this author. e-mail: swchen@che.nthu.edu.tw
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Abstract

The Sn/Cu/Sn/Cu/Sn sandwich-type couples prepared by the casting method are used for examining the effects of electromigration on Sn/Cu interfacial reactions. The samples are reacted at 170 and 180 °C for 24–240 h by passing an electric current with a density of 5000 A/cm2. At the interfaces where electrons flow from the Sn side to the Cu side, uniform layers of Cu6Sn5 and Cu3Sn are formed. The results are similar to those without passage of an electric current. The relatively thicker Cu6Sn5 layer is attributed to the extra Cu source from the dissolved Cu during the sample preparation. At the interfaces where electrons flow from the Cu side to the Sn side, large and nonplanar Cu6Sn5 phase regions are formed. Formation of large Cu6Sn5 regions is the result of electromigration-enhanced Cu diffusion through the grain boundaries and surfaces.

Type
Articles
Copyright
Copyright © Materials Research Society 2007

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References

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