Study On Thermo-compression Bonding And Mechanism Of Cu/SAC105/Cu Full Intermetallic Compound Solder Joints

With the rapid development of the electronics industry,the third-generation semiconductor high-temperature power devices such as SiC has large forbidden band width,high breakdown voltage and high power density compared with the traditional Si power devices,which will inevitably lead to rapid development of high-temperature power devices and will also become the mainstream of semiconductor power devices.However,this will put forward new challenges for microelectronic packaging technology and interconnect materials.Therefore,the development of chip bonding technology capable of stable interconnection in a high temperature environment is one of the research hotspots in the field of electronic packaging.In recent years,the preparation of full IMC?Intermetallic Compounds,IMC?joints with high melting point characteristics can meet the requirements of high-temperature reliability of micro solder joints of high-temperature power devices.In this study,Sn-1.0Ag-0.5Cu?SAC105?and pure Sn were used as the intermediate layer solder,and the Cu/SAC105/Cu and Cu/Sn/Cu structures were soldered.The effects of interconnected temperature,pressure and time on the microstructure of the joint were investigated.The best process parameters were obtained in a short time to obtain full intermetallic compounds solder joints.The interfacial reaction mechanism,microstructure and mechanical properties of the solder joints were analyzed.The effects of Ag element on the interfacial reaction mechanism and mechanical properties were investigated.The Cu/SAC105/Cu structures were interconnected by thermo-compression bonding process.And the microstructure evolution mechanism of solder joints was explored by prolonging the thermo-compression bonding time.Finally,the full intermetallic compounds solder joints were obtained under the temperature and pressure of 450?C and 0.016 MPa at 9.9 s,revealing the effect of temperature gradient on the reaction mechanism of the joint interface by thermo-compression bonding process.The growth rate of the intermetallic compounds at cold end is higher than that at hot end under the temperature gradient.It is also revealed that Ag element formed an intermetallic compound at the top of Cu₆Sn₅during the interfacial reaction.Simultaneously,Ag₃Sn inhibits the diffusion of Cu atoms of Cu substrates from hot end to cold end,and reduces the interfacial reaction rate.The Cu/SAC105/Cu structures were interconnected by high frequency induction bonding technology,and full Cu/IMC/Cu solder joints were finally obtained at 570?C and 260 s during high frequency induction bonding process.The high frequency induction bonding technology improves the interfacial reaction rate between the Cu element and the SAC105,and the magnetic stirring during the high frequency induction bonding process not only accelerates the interface reaction rate,but also changed the morphology of the interfacial intermetallic compound Cu₃Sn.The mechanism of microstructure evolution of the solder joints under high frequency induction bonding was revealed.However,the magnetic field force reduced the mechanical properties of full IMC solder joints.The hardness and elastic modulus of intermetallic compounds at the interface of Cu/SAC105/Cu solder joints were investigated by nanoindentation test.The effects of bonding methods and Ag element on the mechanical properties of full intermetallic compounds solder joints were investigated.