| In-based solder is a kind of solder with lower melting point.The solder joints maded by transient liquid phase diffusion(TLP)bonding technology can be prepared under the low temperature bonding and service under the high temperature,which is important to solve the high temperature resistance of chip.In-based solder joints are prepared by TLP technology in this paper,and the bonding process is optimized.Excellent performance solder joints are treated by high temperature aging at 300 ℃,and then the effect of high temperature aging on the structure and mechanical properties of solder joints is studied.The reliability of In-based composite solder joints is evaluated under high temperature service.The microstructures and mechanical properties of Cu/In-xNi/Cu solder joints were studied.The content of Ni,bonding time,bonding temperature and bonding pressure of Cu/In-xNi/Cu solder joints were optimized.The results show that the optimum content of Ni is 30%,and the optimum technological parameters are 3MPa-260℃-120 min.When the content of Ni is 30%、the structure of the solder joint is the most compact and the shear strength is better,which is 7.9 MPa.The In-rich phase decreases gradually with bonding time increasing.When bonding time increases to 120 minutes,the In-rich phase consumes completely and the Cu2In phase begins to generate at the interface.A large number of holes are generated in the weld due to low or high bonding pressure.The structure of the weld is the most compact when bonding pressure reaches 3MPa.Bonding temperature is the key factor affecting the growth of IMC,and the growth of IMC can be promoted at a moderate temperature,but when the temperature achieve 280℃,Kirkendall voids are formed in the solder joints and gradually expand into cracks.The shear strength of solder joints increases first and then decreases with the increase of bonding time,bonding pressure and bonding temperature.The highest shear strength of solder joints reaches 9.24 MPa when bonding time is 120 min,bonding pressure is 3 MPa,and bonding temperature is 260 C.The optimum content of Ni InSn-xNi was investigated,and the bonding process of solder joints was optimized by orthogonal optimization.The results show that the optimum Ni content is 45%,and the optimum technological parameters are 1 MPa-260 C-30min.InNi6Sn5 phase is formed in the in-situ region of the Cu/InSn-xNi/Cu solder joints,while Cu6(In,Sn)5 phase is first generated at the interface and gradually transformed into Cu3(In,Sn)phase.The prismatic(Cu,Ni)6(In,Sn)5 quaternary phase was formed between the in-situ and the interface,which pins the solder joints and enhances the bonding performance between the interface and the in-situ.The content of(Cu,Ni)6(In,Sn)5 phase in the solder joints is the highest,and the shear strength reaches 9.76MPa when the content of Ni is 45%.Orthogonal optimization results show that bonding pressure has the greatest influence on the mechanical properties of the solder joints,followed by bonding temperature and bonding time.According to the results of polarity analysis,the optimal bonding parameters are 1 MPa,260 C,30min.The shear strength of the prepared solder joints under this condition is 15.89MPa,which is 72%higher than that of In-30Ni solder joints.The effect of high temperature aging at 300℃ on the structure and mechanical properties of Cu/InSn-45Ni/Cu solder joints was studied,The results show that the Cu/Cu3(In,Sn)/Cu6(In,Sn)5 first forms at the interface.With the increase of aging time,the Cu6(In,Sn)5 phase in the solder joints gradually transforms into the Cu3(In,Sn)phase,and finally forms the stable structure of the full Cu3(In,Sn)phase.In-Sn-Ni ternary solid solution precipitates Sn at high temperature and gradually transforms into Ni3Sn 4 and InNi phases,which is accompanied by the formation of holes.The room temperature and high temperature shear strength of solder joints decrease with aging time.The room temperature shear strength is always higher than the high temperature shear strength,but the two tends to be identical with aging time. |
