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Interfacial Intermetallic Growth and Strength of Composite Lead-Free Solder Alloy Through Isothermal Aging

Sivasubramaniam, V. ; Bosco, N.S. ; Janczak-Rusch, J. ; Cugnoni, J. ; Botsis, J.

In: Journal of Electronic Materials, 2008, vol. 37, no. 10, p. 1598-1604

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    Title
    • Interfacial Intermetallic Growth and Strength of Composite Lead-Free Solder Alloy Through Isothermal Aging
    Author
    • Sivasubramaniam, V.. Laboratory for Surface and Joining Technology, Swiss Federal Laboratories for Materials Testing and Research (EMPA), 8600, Duebendorf, Switzerland
    • Bosco, N.S.. Laboratory for Surface and Joining Technology, Swiss Federal Laboratories for Materials Testing and Research (EMPA), 8600, Duebendorf, Switzerland
    • Janczak-Rusch, J.. Laboratory for Surface and Joining Technology, Swiss Federal Laboratories for Materials Testing and Research (EMPA), 8600, Duebendorf, Switzerland
    • Cugnoni, J.. Laboratoire de Mécanique Appliquée et d'analyse de Fiabilité, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
    • Botsis, J.. Laboratoire de Mécanique Appliquée et d'analyse de Fiabilité, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Journal of Electronic Materials, 2008, vol. 37, no. 10, p. 1598-1604. Springer US; http://www.springer-ny.com
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:314935
    Summary
    The effects of particle reinforcement of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) lead-free solder on interfacial intermetallic layer growth and strength of the ensuing joints through short-term isothermal aging (150°C) were studied. Composite solders were prepared by either incorporating 2wt.% Cu (3μm to 20μm) or Cu2O (∼150nm) particles into SAC405 paste. Aggressive flux had the effect of reducing the Cu2O nanoparticles into metallic Cu which subsequently reacted with the solder alloy to form the Cu6Sn5 intermetallic. While all solders had similar interfacial intermetallic growth upon reflow, both of the composite solders' growth rates slowed through aging to reach a common growth rate exponent of approximately 0.38, considerably lower than that of the nonreinforced solder (n=0.58). The nanoscale reinforced solder additionally exhibited the highest tensile strength in both the initial and aged conditions, behavior also attributed to its quick conversion to a stable microstructure