Dynamic phase-frequency characteristic of thermosonic wire bonder transducer

The resonant frequency of transducer is changed with the state of thermosonic wire bonding interface. The ultrasonic generator need to trace the frequency of transducer, and keep the stimulate frequency consist with the resonant frequency of transducer. The frequency tracking strategy is based on the phase-frequency transducer. The dynamic phase-frequency characteristic was measured with a new FPGA based ultrasonic generator. The dynamic phase-frequency characteristic shows that the stimulation frequency may change by the generator quickly, but the change of phase difference between voltage and current of stimulate electronic signal need 12 ms or much longer time, and the final stable phase is much different with the static phase-frequency characteristic measured by HP4191A. This may be one reason for the phase tracking need 3-5 ms.