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Microstructural evolution in lead-free solder alloys: Part I. Cast Sn–Ag–Cu eutectic

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Abstract

Coarsening of the ternary eutectic in cast Sn–Ag–Cu lead-free solder alloys was investigated. The process was found to follow r3 ∝ t kinetics where r is the rod radius of the dispersed phase and t is time. The effective activation energy for the process is 69 ± 5 kJmol-1. The two types of intermetallic rods, Cu6Sn5 and Ag3Sn, in the eutectic structure coarsen at different rates, with each having a different rate-controlling mechanism. The overall coarsening kinetics for the Sn–Ag–Cu ternary eutectic is significantly slower than that found for the Pb-Sn eutectic, which has implications for long-term reliability of Sn–Ag–Cu solder joints.

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Authors and Affiliations

  1. Department of Materials Science and Engineering, Lehigh University, Whitaker Laboratory, 5 East Packer Avenue, 18015, Bethlehem, Pennsylvania, USA

    Sarah L. Allen, Michael R. Notis, Richard R. Chromik & Richard P. Vinci

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  1. Sarah L. Allen
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  2. Michael R. Notis
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  3. Richard R. Chromik
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  4. Richard P. Vinci
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Allen, S.L., Notis, M.R., Chromik, R.R. et al. Microstructural evolution in lead-free solder alloys: Part I. Cast Sn–Ag–Cu eutectic. Journal of Materials Research 19, 1417–1424 (2004). https://doi.org/10.1557/JMR.2004.0190

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  • DOI: https://doi.org/10.1557/JMR.2004.0190

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