WIRE BONDING METHOD

PURPOSE:To prevent any crack in semiconductor chip from occurring by a method wherein, when a copper wire is bonded on an electrode, an end of capillary chip or an end of copper wire is heated by inert gas at high temperature. CONSTITUTION:When a ball 8 is formed at the end of a copper wire 1 pierced through a capillary chip 7, a through hole 7a is fed with inert gas at high temperature from a feeding pipe 10 to heat the end of the capillary chip 7 and the ball 8 of copper wire 1 and after bonding the ball 8 on an electrode 3 of semiconductor chip 2 by thermal pressure fixing jointly using ultrasonic waves, the other end of copper wire 1 is stitch-bonded on a lead 4 by heating within the preferable temperature range of 100 deg.C-150 deg.C. Because the hardness of ball 8 can not be sufficiently lowered under 100 deg.C and the surface of copper wire 1 is remarkably oxidized at above 150 deg.C while the coefficient of friction between inner surface of capillary 7 and the copper wire 1 is also increased. Through these procedures, the bonding operation can be performed using a ball with lowered hardness, making the bonding conditions optimum without increasing the output of ultrasonic.