Effect of Vacuum Annealing on Tensile Mechanical Characteristics of Au Bonding Wires

In this paper, the effect of vacuum annealing on the mechanical properties of Au bonding wires is described. Au bonding wires with a diameter of 25 mu m are subjected to quasi-static uniaxial tensile tests in laboratory air. The bonding wire specimens are prepared by attaching a wire to a Si frame fabricated by deep reactive ion etching (DRIE). The mean Young's modulus and 0.2% offset yield strength are 114 GPa and 354 MPa, respectively. By annealing at 100-300 degrees C for 10 min in vacuum, Young's modulus gradually decreases with increasing annealing temperature, whereas yield strength rapidly decreases in the annealed wires at temperatures above 200 degrees C. The annealing effect is discussed on the basis of the change in the number of recrystallized grains in the wires.