A stereo vision system for the inspection of IC bonding wires

We describe a novel inspection system based on the application of the stere o technique to the detection of defects related to the three-dimensional (3 D) profile of IC wire bonds. In our single-camera-based setup, stereo views are obtained by rotating the IC chip under the CCD camera with a telecentr ic lens. The edges of the wires are detected using Petrou's line filter and the facet model applied to obtain subpixel edge localization. After linkin g edges to form meaningful curves, stereo matching is conducted between the two curve lists of a stereo pair. The height profiles of the wire bonds ar e obtained using the disparity equation derived from the imaging geometry. (C) 2001 John Wiley & Sons Inc.