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A Study of Impact Reliability of Lead-free BGA Balls on Au/Electrolytic Ni/Cu Bond Pad

Published online by Cambridge University Press:  01 February 2011

Shengquan Ou ,
Yuhuan Xu ,
K. N. Tu ,
M. O. Alam  and
Y. C. Chan
Shengquan Ou
Affiliation:
Department of Materials Science and Engineering, UCLA, Los Angeles, CA, 90095-1595
Yuhuan Xu
Affiliation:
Department of Materials Science and Engineering, UCLA, Los Angeles, CA, 90095-1595
K. N. Tu
Affiliation:
Department of Materials Science and Engineering, UCLA, Los Angeles, CA, 90095-1595
M. O. Alam
Affiliation:
Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong
Y. C. Chan
Affiliation:
Department of Electrical Engineering, City University of Hong Kong, Kowloon, Hong Kong
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Abstract

The most frequent failure of wireless, handheld, and movable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of wire-bonds or solder joints between a Si chip and its packaging module. Existing metrologies, such as ball shear, and pull test cannot well represent the shock reliability of the package. In this study, a micro-impact machine is utilized to test the impact reliability of three kinds of lead-free solders: 99Sn1Ag, 98.5Sn1Ag0.5Cu and 97.5Sn1Ag0.5Cu1In (hereafter called Sn1Ag, Sn1Ag0.5Cu, and Sn1Ag0.5Cu1In). The effect of thermal aging on the impact toughness is also evaluated in this study. We find a ductile-to-brittle transition in SnAg (Cu) solder joints after thermal aging. The impact toughness is enhanced by the thermal aging. This is a combination effect of the growth of intermetallic compound (IMC) at the interface provided strong bonding, and the softening of the solder bulk during the thermal aging absorbed more energy during plastic deformation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 863: Symposium B – Materials, Technology and Reliability of Advanced Interconnects , 2005 , B10.5
Copyright
Copyright © Materials Research Society 2005

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References

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