Evaluation of gold and aluminum wire bond performance for high temperature (500 °C) silicon carbide (SiC) power modules

This paper describes an investigation of aluminum and gold wire bonding processes for high temperature electronics. Ultrasonic wire bonding of 8 and 15 mil aluminum wire and 3 mil gold wire on various metallized substrates was investigated. Aluminum wire bonds to nickel-plated aluminum nitride (AlN) and silicon nitride (SiN) substrates were thermally cycled between -55 °C and 400 °C, and gold wires bonded to gold-coated AlN and SiN substrates were thermally cycled between -55 °C and 500 °C. The thermal cycling was accomplished according to MIL-STD-883E criteria. An environmental scanning electron microscope (ESEM) was used to examine the wire/pad and pad/substrate interface areas before and after the thermal cycling. After thermal cycling, the samples were subjected to destructive pull testing at room temperature. The results of the testing revealed no significant degradation of the bonds after thermal cycling.