| 摘要 |
PURPOSE:To detect defective filling in a through-hole with high accuracy by analyzing the optical picture of a circuit board with the through-hole filled and discriminating the irregular state of a packing material. CONSTITUTION:There are a recessed defect, a projecting defect, a short defect, a bleeding defect and a scattering defect in the defects of a packing material in a through-hole. The picture signal of a shadow formed by irregularities is brought to a level lower than a through-hole filling section. Consequently, when a binary-coded binary picture detecting only the shadow is used for detecting irregularities, discrimination from other defects is enabled. A binary- coded binary picture in VH1 near the center of the picture signal level is employed for detecting the short defect. A binary-coded threshold close to a base material level may be set anew in order to detect the fine scattering defect, etc. Consequently, the defects are detected from binary pictures acquired by a plurality of, binary-coded thresholds. Accordingly, the recessed defect and the short defect can be discriminated and inspected positively. |
