PURPOSE: To realize a ball having good profile and finish by increasing the pressure from zero to a set level in a predetermined time and then applying the set pressure for a desired time thereby protecting an objected to be bonded against cracking or breaking.
CONSTITUTION: A ball is formed at the forward end of a wire and then pressure and ultrasonic power are applied to a capillary thus connecting a wire to a bonding point. In such wire bonding method, pressure is increased from zero to a set level P in a predetermined time T1 and the set pressure P is applied for a desired time TP. Alternatively, ultrasonic power is increased from zero to a predetermined level W in a predetermined time T2-TD1. and then the set ultrasonic power W is applied for a desired time TW. Alternatively, the time TD1 for starting to apply ultrasonic power is delayed behind the time To for starting to apply pressure and the time T2 at which the set ultrasonic power W is reached is delayed behind the time T1 at which the set pressure P is reached.
KUDO HITOSHI
KOKUTA TETSUAKI
