Effect of Cu addition on interfacial reactions between Sn-9Zn lead-free solder and Ni substrate

This study investigates interfacial reactions of (Sn-9Zn) + xCu/Ni systems. Ni5Zn21, Cu5Zn8, (Ni,Zn,Cu)(3)Sn-4, (Cu,Ni,Zn)(6)Sn-5, and Cu6Sn5 phases were formed oil the Sn-9Zn/Ni interface at 240-270 degrees C, when 0-10 wt% Cu was added to the Sn-9Zn solder. Experimental results indicate that changing the concentration of Cu in the Sn-9Zn solder dramatically changes the formation of intermetallic compounds (IMCs) in the (Sn-9Zn) + xCu/Ni system. Different diffusion and segregation rates of elements are the main reasons for a change in the IMC evolution.