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The Effect of Substrate on the Microstructure and Mechanical Behavior of Eutectic Indium-Tin

Published online by Cambridge University Press:  15 February 2011

J. L. Freer Goldstein
Affiliation:
Center for Advanced Materials, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720
J. W. Morris Jr.
Affiliation:
Center for Advanced Materials, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA 94720
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Abstract

This study was conducted in order to determine and understand the effect of substrate on eutectic In-Sn. Samples for mechanical testing were produced with either bare Cu or Ni on Cu substrates. Both the microstructure and the mechanical behavior are strongly dependent on substrate, with In-Sn on Cu having a non-uniform and irregular microstructure and In-Sn on Ni having a uniform, normal colony-based eutectic. Deformation is more uniform in the In-Sn on Ni, while it is concentrated along the length of the joint in the In-Sn on Cu. This is reflected in the different shapes of stress-strain curves between In-Sn on Cu and In-Sn on Ni. The stress exponents and activation energies for creep also vary with substrate. Creep deformation is governed by the In-rich γ phase for In-Sn on Cu and by the Sn-rich y phase for In-Sn on Ni. If In-Sn on Ni samples are aged, the microstructure coarsens and the mechanical behavior changes to resemble that of the as-cast In-Sn on Cu.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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