TWI Industrial Member Report Summary 396/1989
N R Stockham
Ultrasonic wire bonding techniques are widely used for making the connections between low power Si devices and external circuitry. 25-50µm diameter Al and Au wires are employed for wedge/wedge and ball/wedge bonding respectively. Because of the increase in production of high power devices for sophisticated automobile controls, microwave devices, etc, there is a growing interest in using ultrasonic welding for making connections in thick wires (125-500µm diameter) capable of carrying currents of 5-20A. This report describes the development of the ultrasonic ball bonding technique to enable it to be used on 500µm diameter Al wires. Bonding trials have been conducted to establish optimum conditions when ball bonding to Al thin film coated Si and capillary wedge bonding to unplated and Ni plated Cu lead frames.