Research On Ultrasound Assisted Sorldering By Ni-Sn Composite Filler

Aluminum and copper is widely used in many industrial areas, such as aerospace, aviation, automotive, electronics and others because of their excellent electrical conductivity, mechanical propert y and excellent performance. With the rapid development of science technology and industrial economy, the demand of welding is also increasing. So the research on the connection properties and connection technology also will be deep. In the low-temperature connection, since the mechanical properties of Sn-based solder is weak, the mechanical strength of the joint has become a major factor restricting of the development and applications. Therefore, this paper proposes a way to use Ni-Sn composite solder to connect the metal with ultrasound assisted soldering. In this method, ultrasonic promotes the Ni and Sn react with Al or Cu in composite filler to improve the joint strength and performance. In this paper, Ni-Sn composite filler is the basic line and the 7075 Al is the base metal as well as T2 Cu. Build the soldering platform and do some research in feasibility of improving strength using Ni-Sn composite filler. Study the factor of IMC changing and internal mechanisms of ultrasonic.The result shows that under the condition of 0.2MPa pressure and 10 s ultrasonic load time, the Ni-Sn composite filler can effectively improve the microstructure of IMC and mechanical properties. When 7075 Al is soldered, the effect of ultrasonic can form the IMC Al3 Nimetallurgical bonding at the interface and a bar of layered structure formed in the inside of filler including Ni bar, Ni3Sn4 IMC and Al3 Ni with Sn matrix. When ultrasonic load time reach20 s, the shear strength become 59.6MPa. When T2 Cu is soldered, the effect of ultrasonic can form the thicker Cu6Sn5 layer at the interface and the bar of layered structure is formed in the inside of filler including Ni bar, Ni3Sn4 and Cu6Sn5 with Sn matrix. With the increasing of temperature, in the condition of 60 s, the dispersion-distribution Cu6Sn5 joint will be formed and the shear strength become 85 MPa.Owing to the two phase structure in Ni-Sn composite filler, the joint can get the high performance. During the soldering process, Ni bar of Ni-Sn composite filler is in solid phase and the Sn is in liquid phase. There are many solid liquid interfaces in filler so that the effect of ultrasonic can be improved. More and more cavitation bubble and hole would be formed to increase the diffusion and nucleation. In addition, the induction heating brings efficient and stable temperature environment and the role of ultrasound brought crushing surface oxide film. All the above is the important factor in this soldering of ultrasonic and induction by Ni-Sn composite filler.