Abstract:
An automatic machine for ball bonding a lead wire to an expanded contact of a semiconductor device and stitch bonding the wire to a lead of the semiconductor package is described. The machine automactically aligns an X-Y table in predetermined relationship to the semiconductor device by means of an electrooptical system. A bonding needle mounted on the table is then moved in a predetermined manner to press the balled end of the wire against the expanded contact. Wire is then positively payed out as the bonding needle is moved to the lead where a stitch bond is performed. After the stitch bond, the needle is raised to pull out a length of wire, then the wire is clamped to break the wire near the stitch bond. The length of the wire protruding from the needle is then passed through a flame to form a new ball preparatory to a new cycle. The wire is payed out to the bonding needle from a spool supported by an air bearing. After the ball is formed, reverse torque is applied to the spool to pull the ball up against the end of the bonding needle. After the ball bond, forward torque is applied to pay out the wire, and the wire is positively fed through the needle by an air stream. After the stitch bond is completed and the ball reformed by the flame, reverse torque is again applied to the spool to draw the ball up against the end of the needle preparatory to the next bonding cycle.
Abstract:
An automatic method and system for packaging discrete semiconductor devices such as transistors is described. The system includes a chasis for indexing a plurality of chucks past a series of work stations. The work stations include three wire loading stations for loading flat-headed lead wires in the chucks, a glass loading station for placing a glass ring around the necks of the lead wires, a series of heaters for heating the glass rings, a pair of molding stations for molding the heated glass rings around the necks of the lead wires to form a header, an alloy station for placing the semiconductor devices in a predetermined orientation on the head of one of the lead wires, and a series of automatic bonding stations for connecting the base and emitter contacts of the semiconductor devices to the heads of the other lead wires. The overall system is controlled by a digital computer. Stations are provided for detecting the absence of a lead wire, the absence of a glass ring, or the absence of a transistor device. The system also detects failure of any one of the bonder stations and terminates operation of the system. The computer is programmed to provide shift registers which define each index position of the chasis and logic signals are shifted through the shift register to continually locate any chuck which is defectively loaded so as to prevent the successful completion of a header assembly. The computer then disables each subsequent station as the defectively loaded chuck is positioned at the respective station.