Ultrasonic-assisted soldering of Sn-based alloys during die bonding for high-temperature application

This paper describes a new method to achieve rapid formation of intermetallic phases joints for hightemperature packaging application. A high-melting-point joint which consists of (Cu,Ni)6Sn5 and Cu3Sn was formed without flux in air with a high shear strength of 67 MPa was obtained at the conditions of 500 W ultrasonic power for 10 s. Compared with other studies based on transient-liquid-phase soldering, the processing time of our method was dramatically reduced from several hours to several seconds and there was no external force acted on chips.