Measurement of driving electrical signal and input impedance analysis of PZT transducer in thermosonic bonding

摘要

In thermosonic bonding process, the driving electrical signal and input impedance of PZT transducer reflect directly the bonding process between gold ball and substrate. This paper describes a method of getting the electrical signal of PZT transducer during the thermosonic bonding process, and analyzes the input impedance of PZT transducer based on the sampled data. From many experiment samples we find that, the driving voltage and current of PZT transducer are approximately 62 kHz sine wave; the range of the voltage is from 2 V to 8 V, and the current is only from 20 mA to 100 mA; the real bonding period is about 52ms. By PSD (power spectrum density) analysis to the electrical signal, we find that there are harmonics in the signal. At last, the paper uses the concept of generalized impedance to analyze the input impedance of PZT transducer during the thermosonic bonding process.