Abstract
An automatic optical through-hole inspection system for ultrahigh density printed wiring boards (PWBs) using leakage light detection has been developed. To detect the dim leakage light emitted from the through-hole defect, we enhanced the sensitivity of the light detector 150 times using a microchannel plate tube. However, the tube caused two problems: stray light sensing and image distortion. To solve these problems, we optically isolated the sensing optics and developed a distortion correction method. We have developed a prototype system that can detect a defect as small as 100 μm.
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References
Ando M, Mita K, Inagaki T (1985) Automatic optical through-hole inspection method for printed wiring boards using leakage light detection. IEEE International Conference on Robotics and Automation, 5D-5: 481–486
Born M, Wolf E (1975) Principles of Optics. Fifth edition, Pergamon Press, Oxford
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Ando, M., Inagaki, T. Automatic optical inspection of plated through-holes for ultrahigh density printed wiring boards. Machine Vis. Apps. 1, 175–181 (1988). https://doi.org/10.1007/BF01213005
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DOI: https://doi.org/10.1007/BF01213005