A system for PCB automated inspection using fluorescent light

Research was performed on the detection of faults such as shorts, cuts, and nicks in a printed circuit board pattern. The possibility was investigated of detecting a pattern by illuminating a printed circuit board with violet or ultraviolet rays and detecting the pattern using the (yellow or other) fluorescent light emitted by the base material consisting of glass-epoxy or glass-polyimide, etc. It was found that the pattern could be detected clearly by selecting an optical fiber that would separate the emitted fluorescent light from the illumination and using a detector consisting of a high-sensitivity TV camera that produces a silhouette image in which the base material is bright and the pattern is dark. A printed-circuit-board pattern inspector using this approach was developed. Test operation of the inspector in a plant demonstrated that it performs consistently good pattern inspections