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Microstructural Evolution in Lead-Free Solder Alloy. Part II: Directionally Solidified Eutectic Tin-Silver-Copper, Tin-Copper and Tin-Silver Alloys.

Published

Author(s)

S L. Allen, M R. Notis, R R. Chromik, Richard P. Vinci, D J. Lewis, Robert J. Schaefer

Abstract

The tin-silver-copper eutectic is a three-phase eutectic consisting of Ag(sub3)Sn plates and Cu(sub6)Sn(sub 5) rods in a (Sn) matrix. It is thought that the two phases will coarsen independently. Directionally solidified ternary eutectic and binary eutectic samples were isothermally annealed. Coarsening of the Cu(sub6)Sn(sub5) rods in the binary and ternary eutectics had activation energies of 73 + 3 and 82 + 4 kJmol(superscript -1), respectively. This indicates volume copper diffusion is the rate controlling mechanism in both. The Ag(sub3)Sn plates break down and then coarsen. The activation energies for the plate breakdown process were 35 and 38 kJmol(superscript -1) for the binary and ternary samples respectively. This indicates that tin diffusion along the Ag(sub3)Sn/(Sn) interfaces is probably the rate controlling mechanism. The rate controlling mechanisms for Cu(sub6)Sn(Sub5) coarsening and Ag(Sub3)Sn plate breakdown are the same in the ternary and binary systems indicating that the phases evolve microstructurally independently of one another in the ternary eutectic.
Citation
Journal of Materials Research

Keywords

coarsening, eutectic, microstructure

Citation

Allen, S. , Notis, M. , Chromik, R. , Vinci, R. , Lewis, D. and Schaefer, R. (2021), Microstructural Evolution in Lead-Free Solder Alloy. Part II: Directionally Solidified Eutectic Tin-Silver-Copper, Tin-Copper and Tin-Silver Alloys., Journal of Materials Research (Accessed February 24, 2024)
Created October 12, 2021