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Electromigration-induced Pb and Sn whisker growth in SnPb solder stripes

Published online by Cambridge University Press:  31 January 2011

C.C. Wei ,
P.C. Liu ,
Chih Chen  and
K.N. Tu
C.C. Wei
Affiliation:
Department of Materials Science and Engineering, National Chiao Tung University, Hsin-chu 30010, Taiwan, Republic of China
P.C. Liu
Affiliation:
Department of Materials Science and Engineering, National Chiao Tung University, Hsin-chu 30010, Taiwan, Republic of China
Chih Chen*
Affiliation:
Department of Materials Science and Engineering, National Chiao Tung University, Hsin-chu 30010, Taiwan, Republic of China
K.N. Tu
Affiliation:
Department of Materials Science and Engineering, University of California at Los Angeles, Los Angeles, California 90095-1595
*
a)Address all correspondence to this author. e-mail: chih@faculty.nctu.edu.tw
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Abstract

Electromigration at 5 × 104 A/cm2 and 100 °C was conducted to grow composite Pb/Sn whiskers from SnPb solders, in which a Pb whisker grows first and then a whisker of Sn grows. In some cases, small Sn islands are embedded in Pb whiskers. The diameter of a composite whisker is <1 μm, which is much smaller than that of spontaneous Sn whisker growth on leadframes. The growth orientation of Pb whiskers was in the [110], [1¯11], and [112] directions. This investigation proposes that compressive stress generated by electromigration at the anode provides the force driving whisker growth. Therefore, accelerated tests of whisker growth at higher temperatures using electromigration are feasible.

Keywords

Packaging
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Articles
Information
Journal of Materials Research , Volume 23 , Issue 7 , July 2008 , pp. 2017 - 2022
Copyright
Copyright © Materials Research Society 2008

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References

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