Ultrasonic wire bonding method

The ultrasonic wire bonding method for bonding the conductor of a sheathed wire to the terminal of an electronic part comprises the steps of forming a first rough-finished surface on either a portion of the sheath of the sheathed wire or the end of a bonding tip which is to be in contact with the sheath and to impart an ultrasonic vibration to sheath, while forming a second rough-finished surface on either another portion of the sheath of the sheathed wire or the face of the terminal of the electronic part to which the conductor of the sheathed wire is to be bonded; and placing the sheathed wire between the bonding tip and the terminal and imparting an ultrasonic vibration to the sheathed wire while lightly forcing the bonding tip to the terminal. The sheathed wire has the sheath thereof scraped without slipping and thus the conductor thereof naked, and this conductor is thereafter or simultaneously bonded to the terminal positively, which can improve the efficiency of wire bonding.