Interfacial Reactions of Sn-9Zn-xCu (x = 1, 4, 7, 10) Solders with Ni Substrates

Abstract

This study investigates the effects of various reaction times and Cu contents on the interfacial reactions between Sn-9Zn-xCu alloys and Ni substrates. After aging at 255°C for 1 h to 3 h, the Ni5Zn21 and Cu5Zn8 phases formed at the interface of Sn-9Zn/Ni and Sn-9Zn-1wt.%Cu/Ni couples, respectively. The (Ni,Zn)3Sn4 phase was found in the Sn-9Zn-4wt.%Cu/Ni couple, and the (Cu,Ni)6Sn5 and Cu6Sn5 phases formed, respectively, in the Sn-9Zn-7wt.%Cu/Ni and Sn-9Zn-10wt.%Cu/Ni couples. As the reaction time was increased from 5 h to 24 h, the (Cu5Zn8 + Ni5Zn21) phases replaced the Cu5Zn8 phase to form in the Sn-9Zn-1wt.%Cu/Ni couple; the (Ni,Zn)3Sn4 phase formed in the Sn-9Zn-4wt.%Cu/Ni couple, and (CuZn + Cu6Sn5) formed in the Sn-9Zn-10wt.%Cu alloys. Experimental results indicate that intermetallic compound (IMC) formation in Sn-9Zn-xCu/Ni couples changes dramatically with reaction time and Cu content. The Sn-Zn-Ni, Sn-Cu-Ni, and Sn-Zn-Cu ternary isothermal sections greatly help us to understand the IMC evolutions in the Sn-9Zn-xCu/Ni couples.