Growth kinetics of the solid-state interfacial reactions in the Sn–Cu/Co and Sn/Co–Cu couples

• Published in: Materials chemistry and physics 2011-10, Vol.130 (1), p.651-656
• Main Authors: Wang, Chao-hong, Kuo, Chun-yi
• Format: Article
• Language: English
• Subjects: Alloying effects; Cobalt; Copper; Couples; Interface reactions; Interfaces, Intermetallic compounds, Annealing, Diffusion; Phases; Retarding; Tin
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2011.07.042

► Interfacial reactions between Sn–Cu solder and Co substrate reveals the CoSn 3 and (Cu,Cu) 6Sn 5 layers were formed. ► Minor Cu addition into the solder results in strongly suppressing the IMC layer growth. ► Interfacial reactions between Sn and Co–Cu substrate were also investigated. ► IMC growth kinetics data was proposed. Two different Sn–Cu/Co and Sn/Co–Cu reaction couples were examined at temperatures ranging from 150 °C to 200 °C to examine the Cu alloying effect by varying Cu contents. Two reaction phases, CoSn 3 and (Cu,Co) 6Sn 5, were observed simultaneously at the interfaces of the Sn–Cu/Co couples (0.1 wt%–3 wt%Cu). The CoSn 3 layer was much thicker than (Cu,Co) 6Sn 5, and CoSn 3 exhibited a linear growth rate at the initial reaction stage. Remarkably, minor Cu addition into the solders resulted in strongly suppressing the layer growth. On the other hand, the potential Co–Cu alloy substrate was also considered because of its impact on decreasing the growth rate. Sn/Co–Cu (less than 10 wt%Cu) interfacial reactions were carried out. Only one CoSn 3 phase layer was produced. In addition, the temperature dependence of the reaction layer growth was also examined. Compared with the binary Sn/Co couple, the layer growth rates in the Sn–Cu/Co and Sn/Co–Cu couples are relatively lower and more temperature-sensitive.