Process Monitor for Electrical Microweld
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Disclosed is an in-situ monitor which is arranged to directly monitor a key physical parameter governing an electrical microweld bonding process. Ordinarily the process is driven by a controlled voltage source and the process is monitored by measuring the current flowing through the bonding tip. The circuit diagram representing the conventional setup is shown in Fig. 1, where Ri, Rs and Rc are respectively the internal resistance of the voltage source, the standard resistance used to measure the current and the resistance of the tip. R(t) is the resistance of the melt zone and the contact resistance between the bonding tip and the wire represented by a single time-varying resistance. Since all the energy deposited into the wire is governed by R(t), it is the key physical parameter of the process.