Aluminium Wires Have the Free Air Balls (FABs): Electronic Flame-Off, Fracture Strength, Electrical Properties, and Bonding Characteristics of Nano Zn Film Al–Si Bonding Wires

摘要

Aluminum wire is a common material for wire bonding due to its resistance to oxidation and low price. It does not melt when becoming a free air ball (FAB) during the electronic flame-off (EFO) process with wettability and is applied by wedge bonding. This study used 20 μm Zn-coated Al–0.5 wt % Si (ZAS) wires to improve the FAB shape after the EFO process, while maintaining the stability of the mechanical properties, including the interface bonding strength and hardness. In order to test circuit stability after ball bonding, the current-tensile test was performed. During the experiment, it was found that 80 nm ZAS with wire bonding had lower resistance and its fusing current was higher. For the bias tensile test, the thicker Zn film diffused into the Al–Si matrix easily, after which the strength was reduced. The ball-bond interfaces had no change in their condition before and after the bias. Accordingly, the ZAS wire could be a promising candidate for ball bonding in the future.