Research on the Influence of Contact Velocity on the Quality of Gold Wire Bonding

In addition to the ultrasonic power, force, time and temperature and other parameters, the gold wire ball bonding quality is also affected by the contact velocity between the free air ball and the chip pad, which will affect the initial deformation of ball and thus affect the bonding quality. So, contact velocity is also an important factor affecting the bonding quality. Through the analysis of the process of the free air ball formation, the capillary movement and the contact deformation of the ball, the influence of the contact velocity between the free air ball and the chip pad on the bonding quality of 1 mil diameter gold wire was studied. By changing the contact velocity during bonding, the effect of contact velocity on the mashed ball diameter, the bonding strength, and the breaking mode of the wire was studied. The research results show that for free air ball with the diameter of 1.8 mils, when the contact velocity increases within 0.2 mils/ms to 1.0 mils/ms, the mashed ball diameter can be increased, thereby, increasing the contact area between the gold ball and the chip pad, and the bonding strength increases first and then decreases. And the contact velocity has no effect on the wire breaking mode in the wire pull test.