Interaction of Surface Roughness and Copper Ball Adhesion Using Shearing Simulation

Wire bonding is one of the commanding interconnection techniques used at the back end of line due to its vast adaptability to the advancing trend of circuit designs. Wire bond shear test method is utilized to examine adhesion strength of the bonded wires. In this paper, the stress response of copper ball bond during wire bond shear test is investigated The influences of three types of bond pad surface; flat surface, hemisphere surface and sharp groove surface on the stress response of copper ball bond during wire bond shear test were evaluated. The simulation was done using Ansys version 11.The simulation results showed the bond pad surface had a significant influence on the stress response of copper ball bond. At the shear ram displacement distance of 35µm, the peak stress responses for all three bond pad surface were obtained.