Improve mechanical properties and corrosion resistance of Al/Sn heterogeneous joints by ultrasonic-assisted liquid phase diffusion bonding

How to obtain a high-strength and corrosion resistance of Al/Sn/Al joint has been a longstanding goal for electronics industry. In this work, 6063Al was joined in the air by ultrasonic-assisted liquid phase diffusion bonding using a Sn filler metal . It was performed by applying an uninterrupted ultrasonic vibration at a heating temperature of 360 ℃, final obtaining a 6063Al joint without enriched-Sn. Under the action of ultrasonic vibrating, the breaking of oxide film , the diffusing of Sn, and dissolving of Al alloy occurred in sequence. It resulted in a transition of bonding interface from Sn/Al to an α-Al/α-Al bonding interface embedded a few Mg 2 Sn partials, after depleting Sn by grain boundary diffusion . The joints possessed a high strength coefficient of 86.7% of 6063Al base metal and 161.8% of soldering joint. The joint had a better corrosion resistance that the tensile strength only reduced 35.3% after a corroding of 72 h in 3.5 wt% NaCl solution in comparison with the soldering joints. Finally, the evolution of the interface structure and mechanism of improving corrosion resistance were discussed in detail. It is a promising technology for manufacturing high-reliable Al/Sn heterogeneous joints.