Computer vision system for the measurement of IC wire-bond height

In the production of integrated circuits (ICs), the wire-bond operation constructs an electrical connection between the bond pads and the package leads using fine gold wire with diameter ranging from 25 /spl mu/m to 65 /spl mu/m. Good quality control of the bonding operation requires the bonded ball diameter and height on the aluminum pad of the silicon chip to be within a certain specified tolerance. This paper describes a low-cost and high-speed visual inspection system for the automatic measurement of the wire-bond ball height using a structured lighting technique. This method is superior to other possible techniques reported so far, because of its potential in online implementation. The system can measure the wire-bond height to an accuracy of /spl plusmn/3 /spl mu/m. Higher accuracy can be achieved with a higher resolution camera and video frame grabber.<>