Impact Vibration Control of a Wire Bonder through Damping Treatments

Abstract

A procedure for solving the vibration problems in a wire bonder is established through experimen tation and modeling. During the bonding operation, the impact of the capillary of the bonder on the workpiece generates undesirable dynamic forces that ultimately reduce the bond yield and bond quality. Experiments simulating the bonding process show that the force exerted by the capillary on the workpiece overshoots the desired value with subsequent oscillations. Mode shape measurements indicate that an operating arm actu ally rocks about its pivot and exhibits severe bending near its capillary. This vibration mode leads to the development of a simple model for predicting the arm response and two feasible ways for improving the bon der's performance. Numerical results from the model show that force overshoots can be reduced by adding a damper to the arm and choosing softer materials for the capillary. For a critically damped wire bonder, there is a threshold for the striking speed below which force overshoots are close to the minimum value.