PURPOSE: To enable high speed processing, by scanning the detected image of the through-hole provided to a printed circuit board by a rotary mirror and a lens system while detecting leaked light from the through-hole to be inspected by and transmitted light from said through-hole to be inspected by a light detector.
CONSTITUTION: Light 2 is allowed to vertically irradiate the surface of a printed circuit board provided with plural through holes 4 each having a conductive layer provided to the inner wall surface thereof and light is transmitted from the through-hole 4 having a defect. In addition, a mask 3 for blocking light 2 is provided on the through-hole 4 to be inspected of the printed circuit board 1. If a defect is generated to the conductive layer of the through-hole 4 to be inspected, light is condensed by a condensing part 5 and the condensed light is reflected by a rotary mirror 7 to be detected by detectors 10, 11. By this constitution, high speed processing can be performed.
MITA KIKUO
KAKIGI GIICHI
