Properties and microstructure of Sn–0.7Cu–0.05Ni solder bearing rare earth element Pr
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Effects of trace amount of rare earth element Pr on properties and microstructure of Sn–0.7Cu–0.05Ni solder were investigated in this paper. The solderability of Sn–Cu–Ni–xPr alloy and shear strengh of Sn–Cu–Ni–xPr soldered micro-joints were determined by means of the wetting balance method and shear test, respectively. Moreover, microstructure of solder alloys bearing Pr, as well as intermetallic compound (IMC) layer formed at solder/Cu interface after soldering were observed. It was concluded that the major benefits of rare earth element Pr on Sn–Cu–Ni lead-free solder are: improving solderability, refining microstructure, and depressing IMC (IMC) growth, which exhibited improved mechanical properties. It also revealed that (Cu,Ni)6Sn5 is the majority IMC phase at the interface of Sn–Cu–Ni–xPr/Cu solder joints. Ni added into the solder effectively suppressed the growth of Cu3Sn and consequently also the total IMC layer thickness. Above all, the thickness and morphology of the interfacial (Cu,Ni)6Sn5 IMC were optimized due to alloying Pr. It can be inferred that Pr and Ni would play an important role in improving the reliability of Sn–Cu–Ni lead-free solder joints.
KeywordsSolder Joint Solder Alloy Solder Matrix Ceramic Resistor Solder Bear
The present work was carried out with the supported by Provincial Key Lab of Advanced Welding Technology,Jiangsu University of Science and Technology Foundation (JSAWT-09-02); supported by Nanjing University of Aeronautics and Astronautics Innovative Research Base of Graduate Students (laboratory) Open Fund. (Project No. 200902012).
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