Size effect of rare-earth intermetallics in Sn-9Zn-0.5Ce and Sn-3Ag-0.5Cu-0.5Ce solders on the growth of tin whiskers
Journal
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Journal Volume
39
Journal Issue
12
Pages
2862-2866
Date Issued
2008
Author(s)
Abstract
In contrast to the large cluster-shaped CeSn3 peritectic phase formed in Sn-3Ag-0.5Cu-0.5Ce solder, Sn-9Zn-0.5Ce possesses very fine (Ce0.8Zn0.2)Sn3 intermetallics. Image analyses indicate that the total exposed area of fine peritectic intermetallics in Sn-9Zn-0.5Ce solder is near that of coarse clusters in Sn-3Ag-0.5Cu-0.5Ce. However, long fiber-type and coarse hillock-type whiskers have been observed on the surface of Sn-3Ag-0.5Cu-0.5Ce after air storage at room temperature and 150 °C, respectively. On the contrary, only tin sprouts appear on the oxide layer of peritectic (Ce0.8Zn0.2)Sn3 intermetallics of Sn-9Zn-0.5Ce solder. The prevention of the lengthening and coarsening of these tin sprouts in Sn-9Zn-0.5Ce solder is attributed to the small size of its rare-earth (RE) containing peritectic clusters. The results imply that Zn atoms have an inhibition effect for the whisker growth of RE-doped solders. © The Minerals, Metals & Materials Society and ASM International 2008.
Type
journal article