Study on vibration characteristics of capillary in an ultrasonic wire bonding system

Dynamic characteristics of the capillary in an ultrasonic wire bonding system are studied to have a better understanding of the bonding mechanism and further predict the bond quality during the bonding process. With finite element method, a dynamic contact model of the capillary is built, and then various loading frequencies and bonding forces are applied to the model to calculate and simulate the vibration responses and contact friction properties. The result shows that the loading frequency and bonding force have a significant effect on the vibration response and the contact friction stress, and thus on the bond quality. Two conclusions are obtained. Firstly, in order to achieve a good bond quality, appropriate loading frequency and bonding force must be selected. Secondly, the vibration response changes of the capillary can be used as an indicator to evaluate and predict the bond quality. These results can be used as references for the bonding process control and the study on bonding quality detection techniques.