Abstract: To meet the demands of high-reliability electronic packaging, the development of new solder alloys is required. In this study, an alloy system was designed using Ni, Bi, In, and Sb with SAC107 solder as the matrix, employing the calculation of phase diagrams method. By adjusting the mass fraction ratio of Bi to Sb, the mechanical properties of solder joints and the growth behavior of interfacial intermetallic compounds were systematically examined before and after aging at 170 ℃, and the optimal addition ratio was identified. The results demonstrate that appropriate additions of Bi and Sb can effectively suppress the excessive growth of (Cu,Ni)₆(Sn,In,Sb)₅ and (Cu,Ni)₃(Sn,In,Sb) phases. When the mass fraction ratio of Bi to Sb is 3∶3, controllability over both interfacial and internal particle precipitation in solder joints is achievable, along with a balanced combination of joint strength and plastic properties. This makes it the optimal ratio.