PRINTED CIRCUIT BOARD THROUGH HOLE INSPECTOR

摘要

PURPOSE:To enable automatic inspection, by judging the presence of a void depending on the quantity of passing light reflected on a plated surface of the wall of a through hole. CONSTITUTION:A printed circuit board 2 having a through hole which is fixed on a transparent plate 1 drivable in the direction Y is illuminated from below by a light source 3 and an image is formed on a linear sensor 5 through an objective lens 4 from the direction inclined by theta from the vertical line. An image signal of the linear sensor 5 is distributed into two parts to be binary coded with comparator 8 and 9 respectively having a reference voltage and the resulting binary coded signals are sent to a defect judging circuit 10. When a defect of a through hole is detected, a microcomputer 16 reads out an XY coordinates of the present position thereof with an NC controller 15 to be outputted to a defect output unit 17 as coordinate where a defect exists. This enables automatic inspection of a through hole of the printed circuit board.