Sensors for ultrasonic wire bonding process control

Ultrasonic wire bonding is an important technique in microelectronics packaging, as it provides electrical connections between an integrated circuit (IC) and the chip carrier. As the bond quality can vary appreciably, it is important to develop some in-process monitoring method to improve the reliability and quality of bonding. In this work, a piezoelectric lead zirconate titanate (PZT) sensor was used to measure two critical parameters. They are: (1) the temporal profiles of ultrasonic power and (2) the impact force imparted to the bonding pad by the bonding tool. A calibrated wire strain gauge was also used to measure the impact dynamic force and the static force applied to the bond surface. This is compared to that of the PZT sensor.