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Elimination of Au-embrittlement in solder joints on Au/Ni metallization

Published online by Cambridge University Press:  03 March 2011

M.O. Alam
Affiliation:
Department of Electronic Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong
Y.C. Chan*
Affiliation:
Department of Electronic Engineering, City University of Hong Kong, Kowloon Tong, Hong Kong
K.N. Tu
Affiliation:
Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California 90095-1595
*
a)Address all correspondence to this author.e-mail: EEYCCHAN@cityu.edu.hk
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Abstract

Systematic experimental work was carried out to understand the mechanism of Au diffusion to the solder interface, and a novel method was proposed to eliminate Au embrittlement by circumventing the continuous layer of (Au,Ni)Sn4 at the solder interface. Contrary to the usual expectation, it was determined that utilization of a very thin Ni metallization in the Au/Ni/Cu under bump metallization (UBM) was an effective means of maintaining mechanical integrity of the solder joint. It was found that the out-diffusion of Cu during the aging period changes the chemistry and morphology of the intermetallic compounds at the interface.

Type
Rapid Communications
Copyright
Copyright © Materials Research Society 2004

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References

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