Thermal Stress Comparison on Copper and Gold Wire Bonded on Aluminium Bondpad

Abstract

This paper reports on the thermal stress comparison between gold (Au) and copper (Cu) wires in wire bonding. The objective of this study is to examine the stress induced during different operating temperatures. ANSYS 11 has been deployed as the simulation tool for this study. This simulation was performed using a three dimensional (3D) non-linear finite element model. The gold and copper wires were attached to an aluminium bondpad on a silicon die. The results showed that when the highest stress concentrates at the area between the ball bond and the bondpad. Moreover, increasing temperature will increase the von mises stress. As for this study, the Cu wire display the greater thermal stress compared to Au wire due to its harder and stiffer material properties.