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Transmission electron microscopy studies of interfacial reactions and void formation in lead-free solders with minor elements

Published online by Cambridge University Press:  31 January 2011

Y.T. Chin ,
P.K. Lam ,
H.K. Yow  and
T.Y. Tou
P.K. Lam
Affiliation:
Intel Malaysia, Kulim Hi-Tech 2/3, 09000 Kulim, Malaysia
T.Y. Tou*
Affiliation:
Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor, Malaysia
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Electroless nickel (Ni–P) is a common surface finish used in the ball grid array (BGA) package and interfacial reactions between its surface finish and lead-free solders can form complex intermetallic compound (IMC) layers. The presence of minor elements in lead-free solders either intentionally added or due to impurity contamination during solder manufacturing, can affect the solder-joint performance. In this work, interfacial reactions between Ni–P surface finish and the Sn–Ag–Cu solders were modified by varying Ag and Cu contents and also by adding a small amount of minor elements such as phosphorus (P), indium (In), and germanium (Ge). A transmission electron microscope was used to determine the intermetallic layer phases, compositions, crystal structures, and void defects. Varying the solder alloy elements led to the modulation of voids formation.

Keywords

SolderingTransmission electron microscopy (TEM)Phase equilibria
Type
Articles
Information
Journal of Materials Research , Volume 25 , Issue 7 , July 2010 , pp. 1304 - 1311
Copyright
Copyright © Materials Research Society 2010

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References

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