ABSTRACT:We describe a novel inspection system based on the application of the stereo technique to the detection of defects related to the three-dimensional (3D) profile of IC wire bonds. In our singlecamera-based setup, stereo views are obtained by rotating the IC chip under the CCD camera with a telecentric lens. The edges of the wires are detected using Petrou's line filter and the facet model applied to obtain subpixel edge localization. After linking 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 are obtained using the disparity equation derived from the imaging geometry.

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