A wire bonder connects silicon chips with container connections using aluminum wires. Ultrasonic sound is used for welding wire connections on silicon chips and pins. On the silicon chip uncoated areas for welding are very small. Therefore positioning has to be very precise for ultrasonic bonding. In the semi-conductor field vision systems are used for that purpose.
Especially in the power sector the surface of the chips is passivated and only few visible structures are left for exact position detection. The vision system introduced here uses any possible polygon as a reference for position detection. This way the user is able to use optimal structures on the chip as a reference. In addition the search area is tracked dynamically to achieve the shortest period of time possible for position detection.
This is important because even a saving of milliseconds adds up when processing a large number of parts.
The presented vision system is integrated in the control of the double head aluminum wire bonder and contains the complete control as well as the double picture vision system for both work stations. The existing vision system hardware was replaced by PC compatible computers.
The computers control the complete bonding process and determine the accurate bond positions with two integrated vision systems with position detection.
The system is operated alternatively via VGA monitor and trackball or via text overlay on BAS monitors and a keyboard.
