| 摘要 |
PURPOSE:To detect various pattern defects of the printed circuit board by a method wherein both upper width and lower width of a copper foil part on the printed board are detected and whether the difference between both width sizes is within the reference value or not is measured. CONSTITUTION:A laser beam 5a from a laser device 5 is irradiated to a copper foil part 2 of a printed circuit board 1. Since the intensity of the light reflected from an upper width part L1 is larger than that from a lower width part L2, it is enough to provide a single means for detecting the reflected light intensity. Among the reflected lights detected by the detecting means set in the laser device 5, the one from the upper width L1 is applied to an upper width detecting circuit 6a and another from the lower width L2 is applied to a lower width detecting circuit 6b. The edge part of the lower width L2 is detected and a measuring circuit 8 is operated by a command from an instruction circuit 9 to measure both upper width L1 and lower width L2. If the difference between thus measured values is larger than the reference value, it is judged as a defective part. With this, it becomes possible to detect such a case that the lower width L2 is normal but the upper width L1 includes a defect, as illustrated. |
