Interfacial reaction of Cu/SAC105/Cu solder joints reinforced with Ti nanoparticles under vacuum thermo-compression bonding

In this study, 0.3 wt% Ti nanoparticles (Ti NPs) were incorporated into Sn1.0Ag0.5Cu (SAC105) solder, and vacuum thermo-compression soldering was employed to fabricate two distinct solder joints: Cu/SAC105/Cu and Cu/SAC105-0.3Ti/Cu. The research delved into how altering bonding pressures and durations affects the development of interfacial intermetallic compounds (IMCs) and, consequently, the mechanical characteristics of solder joints. The thickness of the solder joints exhibited a gradual decrease with increasing bonding pressure, reaching approximately 13 μm at a bonding pressure of 1.0 MPa. The incorporation of Ti NPs demonstrated an effective inhibition of the interfacial IMC layer growth. This led to a notable decrease in the thickness of the IMC layer in the Cu/SAC105-0.3Ti/Cu solder joints. Furthermore, the introduction of Ti NPs did not cause a notable alteration in the fracture path of the solder joints. Exceptionally high shear strengths exceeding 38 MPa were achieved for both solder joints at a bonding pressure of 0.6 MPa. Moreover, the shear strength of the Cu/SAC105-0.3Ti/Cu solder joints slightly surpassed that of the Cu/SAC105/Cu solder joints. However, at a bonding pressure of 1.0 MPa, the aggregation of Ti NPs in the solder joints adversely affected the microstructure, leading to a deterioration in shear strength.