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Sn-Ag-Cu solders and solder joints: Alloy development, microstructure, and properties

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  • Lead-Free Solders
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Abstract

Slow cooling of Sn-Ag-Cu and Sn-Ag-Cu-X (X = Fe, Co) solder-joint specimens made by hand soldering simulated reflow in surface-mount assembly to achieve similar as-solidified joint microstructures for realistic shearstrength testing, using Sn-3.5Ag (wt.%) as a baseline. Minor substitutions of either cobalt or iron for copper in Sn-3.7Ag-0.9Cu refined the joint matrix microstructure, modified the Cu6Sn5 intermetallic phase at the copper substrate/solder interface, and increased the shear strength. At elevated (150°C) temperature, no significant difference in shear strength was found in all of the alloys studied. Ambient temperature shear strength was reduced by largescale tin dendrites in the joint microstructure, especially by the coarse dendrites in solute poor Sn-Ag-Cu.

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Authors and Affiliations

  1. Ames Laboratory (U.S. DOE), Iowa State University, 222 Metals Dev. Bldg., 50011, Ames, Iowa, USA

    I. E. Anderson, B. A. Cook, J. L. Harringa & R. L. Terpstra

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  1. I. E. Anderson
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  2. B. A. Cook
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  3. J. L. Harringa
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  4. R. L. Terpstra
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Anderson, I.E., Cook, B.A., Harringa, J.L. et al. Sn-Ag-Cu solders and solder joints: Alloy development, microstructure, and properties. JOM 54, 26–29 (2002). https://doi.org/10.1007/BF02701845

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  • DOI: https://doi.org/10.1007/BF02701845

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