Non-pressure Joining Method for Zn-Al Solder By Pre-Ultrasonic Bonding

摘要

This paper reports joining technology for Zn-Al solder without pressure during reflow process. SiC power devices can operate at temperatures over 200°C. Taking the advantage of this benefit, the cooling system which occupies a large volume in an inverter can be downsized. However, high melting point solder is required, such as Zn-Al solder. This solder was needed to pressure during reflow process because Zn-Al solder preform has stiff natural oxide film on its surface. We propose a new process for breaking the oxide film and creating temporary joining by ultrasonic bonding. As the result, the solder can join other components without pressure during reflow.