DETECTING APPARATUS OF CONTACT ON SURFACE TO BE BONDED

摘要

PURPOSE:To control the downward movement of a capillary after the contact thereby keeping constant load there and stabilize the quantity of bonding by detecting the change of current of ultrasonic vibration with a current change detecting circuit and detecting that the capillary has reached the surface to be bonded. CONSTITUTION:A horn 2 is moved downward with a driver under the condition that an ultrasonic vibrator 1 is vibrated at an amplitude smaller than the vibration during bonding. When a capillary 3 comes in contact with the bonding surface of a semiconductor chip 5, a current flowing into the ultrasonic vibrator 1 becomes small because an impedance thereof becomes large and the vibrator is driven at a constant voltage. Such change of current is detected by a current change detecting circuit 22. A main control circuit 29 receives a signal sent from a comparison circuit 28 and drives the ultrasonic wave vibrator 1 with a voltage required for bonding by sending a signal to an ultrasonic wave oscillator 21 and simultaneously detects the position with a position detector 8 and controls successive downward movement. The horn 2 is rotatably supported by the holding shaft 10 and therefore the load after the contact on the surface to be bonded is determined by elongation of a spring 11 and when downward movement is constant, the load is always constant.