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论文类型：会议论文

发表时间：2010-08-02

收录刊物：EI、CPCI-S、Scopus

卷号：654-656

页面范围：1385-+

关键字：Liquid structure; Sn-Cu solder; IMC

摘要：The liquid structure of two lead-free solder molten alloys, Sn-0.5Cu and Sn-1.8Cu (wt.%), have been investigated using X-ray diffraction method. The main peak for liquid structure of Sn-0.5Cu is similar to that of pure Sn. A pre-peak has been found in the low Q part on the structure factor S(Q) of Sn-1.8Cu tested under 320 degrees C and the pre-peak decreases its intensity with increasing temperature, but it disappeared finally when the testing temperature reached 350 degrees C. The microstructure of the solder matrix as well as interfacial reaction between liquid solders and Cu substrate was also studied. The structural unit size corresponding to the pre-peak almost equals to magnitude of crystal planar distance of Cu6Sn5 phase. The appearance of a pre-peak may be due to existence of clusters with Cu6Sn5-phase-like structure in the melt. Quantity and size of clusters increases with decreasing temperature but their structural unit size remains constant. Cu6Sn5 phases develop from incorporating and growing of the clusters during solidification, thus result in the correlation between liquid structure and solid microstructure.