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Electrochemical behavior of metal interconnects in electronic assemblies

Published online by Cambridge University Press:  31 January 2011

Ling Chunxian Zou
Affiliation:
National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom
Christopher Hunt*
Affiliation:
National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

The electrochemical and corrosion behaviors of solder alloys—SnAgCu (SAC), SnZnBi, SnPb, and Sn—and printed circuit board finish materials Cu and AuNi were investigated in carboxylic acids (flux) and NaCl solutions using the potentiodynamic scanning technique. The results show that SAC and Sn are passivated in the diluted flux solution, but SnPb, SnZnBi, Cu, and AuNi are under active dissolution when anodically polarized. However, passivation of SAC alloy is not observed in concentrated flux solution. Although a passive film forms on SAC in a 2% NaCl solution, the film is less stable than in the flux solution. In addition, oxidation of the most commonly used lead-free and lead solders, SAC and SnPb, at high temperature was evaluated via sequential electrochemical reduction analysis (SERA). The SERA results revealed that the SAC alloy oxidized more significantly than SnPb under hot, dry conditions.

Type
Articles
Copyright
Copyright © Materials Research Society 2008

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References

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