In Situ Observation of Ultrasonic Flip-Chip Bonding Using High-Speed Camera

Room-temperature microjoining in the air ambient has been achieved by using cone-shaped Au bump with ultrasonic application. In-situ observation of the ultrasonic bonding is performed using a high speed camera for the purpose of investigating dynamics of the bonding process. “Softening” of the bump under the application of ultrasonic is observed. It is suggested that bonding is almost completed within 100 ms.