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Interfacial reactions and joint strength of Sn–37Pb and Sn–3.5Ag solders with immersion Ag-plated Cu substrate during aging at 150 °C

Published online by Cambridge University Press:  03 March 2011

Jeong-Won Yoon
Affiliation:
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
Jun Hyung Lim
Affiliation:
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
Hoo-Jeong Lee
Affiliation:
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
Jinho Joo
Affiliation:
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
Seung-Boo Jung*
Affiliation:
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
Won-Chul Moon
Affiliation:
Micro Electronic Packaging Consortium, Sungkyunkwan University, Jangan-gu, Suwon, Gyeonggi-do 440-746, Korea
*
a) Address all correspondence to this author. e-mail: sbjung@skku.ac.kr
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Abstract

Joint reliability of immersion Ag with two different solders, Sn–37Pb and Sn–3.5Ag, were evaluated. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn–Pb solder produced a Pb-rich phase along the interface between the solder and the Cu substrate during aging. In contrast, the Sn–Ag solder exhibits an off-eutectic reaction to produce the eutectic phase and Ag3Sn precipitate. The shear test results show that the Sn–Pb solder joint fractured along the interface showing brittle failure indications possibly due to the brittle Pb-rich layer. In contrast, the failure of Sn–Ag solder joint was only through the bulk solder, providing evidence that the interface is mechanically reliable. The results from this study confirm that the immersion Ag/Sn–Ag solder joint is mechanically robust, and thus the combination is a viable option for a Pb-free package system.

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Articles
Copyright
Copyright © Materials Research Society 2006

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