Researh On Interface Structure And Mechanical Properties Of Joints Of Soldering Pure Al And Al-mn Alloy With Sn Based Solders

Aluminum alloys have benn widely used in aerospace, automotive industry,machinery manufacturing, shipbuilding and electronic communications field, due totheir performances of good thermal conductivity, easy molding, cheap price, low densityand high strength. Therefore, the research on aluminum and aluminum alloys weldinghas important theoretical and practical value.Ultrasonic sodering and scratch sordering of1060Al and3003Al was conductedat300°C in air with pure Sn and Sn-9Zn solders. Microstructure of the solder joints,interface structure, mechanical properties of joints were investigated in this study.When soldering of1060Al and3003Al with pure Sn, the interfaces are uneven.Fracture initiates at the interface during tensile test. The tensile strength of Sn/1060Aljoint can reach approximately60MPa, the tensile strength of joint of ultrasonic soderingof3003Al with pure Sn is about68MPa, and the tensile strength of joint of scratchsodering of3003Al with pure Sn is about100MPa.The fracture of joints of1060Al and3003Al soldering with Sn-9Zn initiates in thesolder. The tensile strength of Sn-9Zn/1060Al joint is about80MPa, and the tensilestrength of Sn-9Zn/3003Al joint is about120MPa, then we come to the conclusion thatthe Sn/Al interface is strengthened by SnZnAl solid solution.An oxygen-rich layer is found at the interface of the joints of sodering1060Al or3003Al with pure Sn or Sn-9Zn solder, and the content of oxygen in the oxygen-richlayer can reach approximately40%. The oxygen-rich layer is proved to be amorphous.Generate of amorphous doesn’t have significant relationship with ultrasonic time, it canbe generated in both ultrasonic sodering and scratch sordering.The scratching soldering method is improved when soldering1060Al with pure Sn,the solder on the soldering surface is removed and the surface is exposed to air. Thetensile strength of normal scratch sordering Sn/1060Al joint is about65MPa, and itgenerates litte amorphous at the interface. But with the improved sordering method, thetensile strength of joint is about80MPa, and it generates more amorphous. Visiblely thebonding strength of Sn/Al interface has been increased by the amorphous layer.