Effect of La addition on the interfacial intermetallics and bonding strengths of Sn-58Bi solder joints with Au/Ni/Cu pads
Resource
Journal of Alloys and Compounds, 491(1-2), 610-617
Journal
Journal of Alloys and Compounds
Journal Volume
491
Journal Issue
1-2
Pages
610-617
Date Issued
2010
Date
2010
Author(s)
Shiue, Yu-Yun
Abstract
The addition of 0.5 wt.% La into a Sn-58Bi alloy leads to the formation of rare earth containing intermetallic plates in the solder matrix and a slight reduction of its eutectic point. After reflowing, Ni3Sn4 intermetallic compounds appear at the solder/pad interfaces of Sn-58Bi and Sn-58Bi-0.5La packages with Au(0.1 μm)/Ni(5 μm) surface finish, which grow linearly during the aging at 75 and 100 °C for various times ranging from 100 to 1000 h. It can also be observed that the interfacial intermetallics layers in Sn-58Bi-0.5La solder joints are much thinner than those in undoped Sn-58Bi. However, voids in the Sn-58Bi-0.5La solder balls resulted in lower bonding strengths of their solder joints as compared to those in Sn-58Bi packages. Ball shear tests with a shear rate of 0.4 mm/s caused the reflowed and aged solder joints of both packages to rupture through the solder balls with brittle characteristic, which remain unchanged as the shear rate increased to 2000 mm/s. © 2009 Elsevier B.V. All rights reserved.
Type
journal article
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