Grain Refinements of Cu₆Sn₅ in Sn-3wt%Ag-5wt%Cu High Temperature Solder Alloys

Abstract:

This paper investigated the effect of trace addition of Al and Mg on the grain refinements of Cu₆Sn₅ in Sn-3wt%Ag-5wt%Cu high temperature solder alloys. Furthermore, the effect of Al and Mg addition on the Sn/Ag₃Sn eutectic were also investigated. It was found that the addition of both Al and Mg successfully refined the Cu₆Sn₅ in Sn-3wt%Ag-5wt%Cu solder alloy. In addition, Al suppresses the formation of Ag₃Sn in the Sn/Ag₃Sn eutectic; while Mg promotes the formation of fine Sn/Ag₃Sn eutectic microstructure. The refinement of Cu₆Sn₅ is believed to be due to heterogeneous nucleation by Al and Mg rich intermetallic particles respectively. Effect of Al and Mg addition on the undercooling of the Sn/Ag₃Sn eutectic was found to be similar, both reducing undercooling effectively at a low addition rate of 0.025wt%. The addition of Al and Mg have mixed effect on the nucleation temperature of Cu₆Sn₅. It is found that the nucleation temperature of Cu₆Sn₅ is increased with 0.025wt% Al and 0.1wt% Mg addition to the unmodified alloy, while the nucleation temperature slowly decreases again as the trace element addition rate increases.

• Periodical: Solid State Phenomena (Volume 273)
• Pages: 20-26
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.273.20
• Online since: April 2018
• Authors: Xin Fu Tan, Mohd Arif Anuar Mohd Salleh, Stuart D. McDonald, Kazuhiro Nogita
• Keywords: Grain Refinement, Pb-Free Solder, Tin Alloy, Undercooling

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