Experimental and Modeling Studies of Looping Process for Wire Bonding

Looping is one of the key technologies for modern thermosonic wire bonders, and it has been affected by many interacting factors. In this study, the wire looping process was observed with a high-speed camera, and the evolution of wire profiles during looping and the capillary trace were obtained through experiments. A dynamic finite element (FE) model was developed to learn the details of the looping process, where real capillary geometry dimensions, capillary trace, diameter of bonded ball and the gold wire material were used, and the friction force and air tension force were considered. The simulated profiles were compared with those of the experiment. Using the verified FE model, the effects of material properties, capillary parameters, and capillary traces on the looping process were studied, and the relationships between the final profiles and parameters were discussed.