DEVICE FOR INSPECTING SOLDERING EXTERNAL APPEARANCE FOR PRINTED CIRCUIT BOARD

PURPOSE:To detect existence or a kind of a surface defect, and to decide whether a soldering state is satisfactory or not, by reading a soldering pattern as an image, converting it into a multi-valued variable density data and bringing it to a histogram processing and comparing it with a reference data. CONSTITUTION:A soldering pattern on a printed circuit board 2a to be inspected is read as an image by a camera 3 and inputted to an image processor 4. In the device 4, an image data is converted to a digital data of 256 gradations by an A/D converter 4a, and also, in a histogram processing part 4j, a histogram processing is executed. This output is compared with a reference data by a comparator part 4k, and a kind of a surface defect is detected by a surface defect detection processing 4l. On the other hand a variable density value data obtained by a variable density data processing means 4b is converted to a binary data showing a solder surface and a non-solder surface, by a binarization processing part 4c and a shape defect data is obtained and stored temporarily in a binary data storage art 4d. Also, a non-defective printed circuit board 2b is processed in the same way and used as a reference data.