Recrystallization and Grain Growth of Gold bonding Wire

Recrystallization and grain growth of gold bonding wire have been investigated with Electron Back Scatter Diffraction (EBSD). The textures of the drawn gold wires contain major <111>, minor <100> and small fractions of complex fiber components. The <100> oriented regions are located in the center and surface of the wire, and the complex fiber component regions are located near the surface. The <111> oriented regions occur throughout the wire and have large Taylor factors and would be expected to have higher stored energy as a result of plastic deformation compared to the <100> regions. Both <111> and <100> grains grow during annealing. In particular, <100> grains in the surface and the center part grow into the <111> regions at 300 and 400°C. Conversely, at 600°C, <111> grains grow into the <100> regions and a large number of twin boundaries occur. Large misorientations (angles > 40°) are located between the <111> and <100> regions, which means that the boundaries between them are likely to have high mobility. Boundaries within the <111> regions are predominantly <111> tilt grain boundaries with large misorientations, similarly, the <100> regions have <100> tilt grain boundaries with smaller misorientations. Grain Orientation Spread (GOS) is similar in the <111> and <100> regions although significant variation is observed with annealing temperature. It appears that the stored energy as indicated by geometrically necessary dislocation content in the subgrain structure is similar in all orientations despite the large differences in Taylor factor.