Rapid formation, grain refinement and shear property of high-temperature-stable full IMC joints

Abstract

Solid liquid interdiffusion (SLID) bonding that can fabricate high-melting point full IMC joints is playing an increasing key role in 3rd-generation semiconductor power electronic device packaging for high temperature applications. In this study, rapid formation of Cu/intermetallic compounds (IMCs)/Cu–8Ni joints with fine (Cu,Ni)6Sn5 and (Cu,Ni)3Sn grains was achieved by SLID bonding Cu/Sn/Cu–8Ni structure. The formation and evolution of the IMCs and the elemental distribution and shear property of the full IMC joints during bonding and subsequent aging were systematically investigated. Due to the Ni doping, the growth of the (Cu,Ni)6Sn5 IMC was significantly accelerated during bonding while that of the Cu3Sn phase was strongly suppressed during both bonding and aging. The total IMC growth rate in the Cu/Sn/Cu–8Ni solder joints was approximately 44 times faster than that in the Cu/Sn/Cu solder joints under the same bonding condition. After aging at 260 °C for up to 400 h, the full IMC joints showed good thermostability composing of fine IMC grains and no Kirkendall voids were observed. The shear strength of the full IMC joints slightly dropped from 63.17 MPa after bonding to 54.35 MPa after aging. The proposed SLID bonding using Cu/Sn/Cu–8Ni structure was proved to be a promising method for forming high-temperature-stable full IMC joints for 3rd-generation semiconductor power device packaging or 3D packaging applications.