Joint Time-Frequency Analysis of Capillary Tip Vibration in Thermosonic Wire Bonding

In thermosonic wire bonding process, the capillary of transducer is a critical component that contacts directly to the ball bump of IC chip, and its vibration characteristic is an important factor that affects directly the bonding quality. The aim of this investigation is to understand the vibration characteristics of capillary tip in thermosonic wire bonding. With laser Doppler non-contact measurement, vibration signal of capillary tip is picked up and analyzed by joint time-frequency analysis. The results show that, compared to pure time or frequency domain analysis, joint time-frequency analysis can more clearly and more completely reveal the dynamic vibration characteristics of capillary tip in joint time-frequency domain, including the shift of frequency, change of harmonic components and its corresponding energy in bonding process. Moreover, joint time-frequency analysis can be used to show success and failure in bonding