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Indexed by:期刊论文

Date of Publication:2014-09-01

Journal:METALS AND MATERIALS INTERNATIONAL

Included Journals:SCIE

Volume:20

Issue:5

Page Number:953-958

ISSN No.:1598-9623

Key Words:soldering; microstructure; wetting; interfaces; intermetallics

Abstract:The influence of trace rare earth (RE) Ce addition on the microstructure, melting point and wettability of pure Sn as well as on the soldering reactions in Sn-xCe/Cu(Ni) solder joints was investigated. In bulk Sn-xCe solders, large beta-Sn grains were observed with the Ce addition less than 0.2 wt%; while the beta-Sn grain size decreased markedly when the Ce addition was 0.2 wt%, resulting in a refined microstructure. The addition of trace RE Ce had little effect on the melting temperature of the solders. Smaller wetting angles of Sn-xCe solders on both Cu and Ni substrates were measured when the samples were reflowed at a higher temperature. The Sn-0.2Ce solder owned the best wettability on Cu substrate. Scallop-like Cu6Sn5 intermetallic compound (IMC) grains formed at the Sn-xCe/Cu interfaces, while a continuous Ni3Sn4 IMC layer formed at each Sn-xCe/Ni interface. With the increase of Ce addition, the interfacial IMC grain size and the interfacial IMC layer thickness on both Cu and Ni substrates decreased gradually. The activity of Sn was lowered with the Ce addition, which depressed the growth of the interfacial IMC. In the current study, the Ce addition of 0.2 wt% exhibits the optimized performance.