Study of free-air-ball and bonding properties of Ag–Au–Pd alloy wires

Abstract In this paper, ball-burning and bonding tests were conducted using Ag–Au–Pd alloy wires with a diameter of ϕ 0.025 mm, and the performance of free air ball (FAB) morphology and bonding strength under various bonding parameters was investigated. The results showed that when the electronic flame off (EFO) current is 20 mA, the FAB of Ag–Au–Pd bonding alloy wire appears small ellipsoid, whereas increasing the EFO current to 40 mA resulted in a golf club-shaped FAB. Similarly, when the EFO time was 0.4 ms, the FAB appears as a small spherical, but extending the EFO time to 1.2 ms caused the FAB to enlarge and exhibit a golf club phenomenon. The addition of Pd element reduced the FAB heat affected zone length of Ag–Au–Pd alloy wire by 19.4% compared to Ag–Au wire. Insufficient ultrasonic power and bonding pressure lead to weak bonding at the bonded interface, thereby reducing the bonding strength, while excessive ultrasonic power and bonding pressure can cause short circuits and pad damage. The optimized bonding parameters for the Ag–Au–Pd alloy wire determined to be: an ultrasonic power of 65 mW and a bonding pressure of 45 g for the ball bond, and an ultrasonic power of 95 mW and a bonding pressure is 75 g for the wedge bond.