Thermosonic bonding of high-power semiconductor devices for integration with planar microstrip circuitry

This paper reports the results of our thermosonic bonding process development effort for the attachment of high power discrete Gunn devices to a machined and plated copper block, for interconnection with planar microstrip circuitry. High power devices are attached to the gold on a plated copper block at elevated temperature under pressure from a vacuum pickup tool tip. Diodes are then gold-ribbon bonded to microstrip circuitry using the same approach. The paper addresses the ranges of bonding temperatures, bond load, ultrasonic power and the duration of bonding required to minimize the stresses that damage the diode, without degrading the bond integrity. It is observed that the introduction of ultrasonic energy into the bonding process significantly reduces the temperature and assembly force applied to the diode. Finally, this paper describes our findings concerning the effects of different assembly parameters on device heat dissipation.