Intrinsic Thermocouple Monitor for Laser Wirebonding

The use of the thermoelectric voltage generated between the tip and the wire during laser wirebonding is described as a process monitor. The change in thermoelectric response during melting of the wire is detected and used to control the laser pulselength. Thus, optimum bonding is achieved independent of thermal environment at different pad locations. The use of the process monitor for bonding on gold pads on multilayer alumina substrates is described in detail. © 1995 IEEE