In situ observation of ultrasonic flip-chip bonding using high-speed camera

Room-temperature microjoining in air ambient has been achieved by using a cone-shaped Au microbump with ultrasonic application. In situ observation of ultrasonic bonding is performed using a high-speed camera to investigate the dynamics of the bonding process. "Softening" of the bump under ultrasonic application is observed. It is suggested that bonding is achieved within 50 ms. (C) 2015 The Japan Society of Applied Physics