Effect of electrode pattern on the outputs of piezosensors for wire bonding process control

A polyvinylidene fluoride (PVDF) piezosensor was installed as an integral part of an ultrasonic wire-bonding transducer for measuring bonding parameters, such as impact force, ultrasonic amplitude, and bond time. Four different types of electrode patterns were used to optimize the sensor outputs. When the ring-shaped electrode of the sensor was subdivided into four different sections, namely the top, bottom, left, and right sections, different output signals were observed during the wire-bonding process. The top section of the sensor was more sensitive to the impact force while the left and right sections could track the changes in the ultrasonic amplitude proficiently. This sensor has good potential to be used in an in situ automatic wire-bonding process-control system.