| 摘要 |
PURPOSE:To automatically detect defective solder without the aid of visual or electrical inspection by projecting the black and white photograph of the rear surface of a normal printed circuit board on the rear surface of a printed circuit board to be inspected and detecting the light reflected therefrom with an optical sensor. CONSTITUTION:The soldered parts of the printed circuit board are taken black on a black and white film and the other parts are taken transparent thereon if light is irradiated to the rear surface of the normal printed circuit board and the photograph thereof is taken by the black and white film. The photograph is enlarged to a life size by an enlarger and is projected to the rear surface of the printed circuit board which is an object to be inspected. The light reflected therefrom is detected by the optical sensor and is sent to a discrimination circuit consisting of an amplifier, comparator, switch, etc. Since only the soldered parts emit the reflected light, the reflected light is not generated by the black image from the film if the circuit board is normal. A defective part emits the reflected light if the circuit board is defective. The defective part is searched in the discrimination circuit. |
