Increasing the ultrasonic bondability at low processing temperatures-surface modification by vacuum- coating of very fine Au wires

摘要

The coating of thin Au wires with a layer of hardmetal by the technique of magnetron sputtering istechnologically feasible. The best suited coating materials arealuminium and tantalum. Comprehensive practical experimentswith the ultrasonic wedge-wedge-bonding technique prove thatAu-wires are reliably bondable at room temperature, as long asthe layer in question is at least 20 nm (aluminium) or 15 nm(tantalum) thick. Additional ageing tests and material analyseshave shown a reliable contact between wire and metallization.The production of industrial samples in accordance with thetechnology described is taking place at the TU Dresden.