| 摘要 |
PURPOSE:To detect a fine defect in a printed circuit board with patterns formed on the front and back surfaces thereof by combining a black line lighting system and a transmission lighting system. CONSTITUTION:A printed circuit board 1 with patterns formed on both surfaces thereof is irradiated from above with a light beam in a first wave band transmitted through a first filter F1 through a black line mask 11. A reflection pattern from a black line pattern 3 is detected with a first 1-D imaging element 15 through a second filter F1'. The printed circuit board 1 is illuminated by a light beam from a second light source 17 from the direction F through a third filter F2 with the wavelength band differing from that of the first filter F1 and a transmission pattern through the light beam is detected with a second 1-D imaging element 16. The detection outputs of the first and second imaging elements 15 and 16 are applied to an AND gate circuit after binary-coded with a binary coding circuit to detect a defect such as a pin hole. |
