Experimental study on EFO process of thermosonic wire bonding by using high-speed video record

The stable bonding of gold wire is becoming more and more important with the development of high integration and miniaturization of semiconductor. At the beginning of the thermosonic wire bonding cycle, the auto wire bonder uses an Electronic Flame-Off (EFO) unit to create a Free Air Ball(FAB). As FAB affects the quality of the first bond directly, consistency of FAB formation is very important for the stable wire bonding. In this study, a high-speed camera system was used to record the EFO and FAB formation process under different EFO currents. Continuous image sequences of FAB formation were processed by using matlab software. Finally, the influence law of EFO current on FAB fomation was obtained.