A stereo vision system for the inspection of IC bonding wires

Abstract

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.

Adaptive image thresholding for real‐time particle monitoring

“…In most cases, the emphasis has focused on controlling the imaging environment and not on developing an image thresholding method that can adapt to the undesired changes. Typically, after changing the imaging system to minimize the variation in the quality of the captured images, a thresholding technique is applied (Ye et al, 2000). Histogram-based thresholding and attribute-based thresholding appear to be the most frequently used methods for particle size analysis and appeared most suited for this work.…”

Illumination system for wire bonding inspection

“…A fiber-optic ring light was used as the light source to highlight the bonding wires. Ye et al 5 presented an inspection system that applied a stereo vision technique to detect defects related to the 3D profile of bonding wires. They proposed that the illumination system should maximize light reflected from the bonding wires and should minimize light reflected from the surface of the chip or the background of the bonding wires.…”