Comparison of Insulated with Bare Au Bonding Wire: HAZ Length, HAZ Breaking Force, and FAB Deformability

Two types (A and B) of 25-μm-diameter bare Au bonding wire and their corresponding insulated wire were used to produce 50-μm-diameter free-air balls (FABs) for heat-affected zone (HAZ) and FAB deformability analyses. Insulated wires showed no significant difference in HAZ length compared with bare wire for type A, while their difference lay in the range of 4% to 12% longer for type B. The HAZ breaking load of bare wire is 0.3% to 1.8% smaller than that of insulated wire for type A and not significantly different for type B even though the HAZ length is shown to be larger for insulated wire B. The deformability of the FAB from insulated wires is 1.0% to 2.1% smaller than that from bare wires for type A and 2.1% to 3.4% larger for type B.