Wire for ultrasonic bonding - has wire of ductile metal such as gold or copper coated with thin layer of harder material

摘要

A wire made from a ductile metal like gold or copper with a low yield point is used for ultrasonic bonding. The wire is coated with a thin layer of material which is hard compared with the wire. The layer is between 5 and 100 nanometres thick, and it forms a brittle oxide layer in air, or with the aid of additional oxidation means. As an example, the coating layer can be aluminium or nickel or tin. Alternatively, hard material can be embedded in it. The layer may be diffused into the wire to give a hard crystalline solid solution as an outer surface. ADVANTAGE Ultrasonic bonding can be carried out at room temperature.