Sensors for ultrasonic wire bonding process control

Ultrasonic wire bonding is an important technique in microelectronics packa ging, as it provides electrical connections between an integrated circuit ( IC) and the chip carrier. As the bond quality can vary appreciably, it is i mportant to develop some in-process monitoring method to improve the reliab ility 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 im parted to the bonding pad by the bonding tool. A calibrated wire strain gau ge was also used to measure the impact dynamic Force and the static force a pplied to the bond surface. This is compared to that of the PZT sensor.