Toshikazu Yasue

Defect detection method for stamped patterns utilizing random access parallel matching technique

In the fabrication processor of electronic components, the outlook inspection has been performed primarily by visual observation. The automation of this process is presently considered important. This paper describes automatic defect detection considering the stamped pattern on the surface of the electronic parts on the integrated circuit, etc. The only clue to the information on the kind of electronics part is the characters and symbols stamped on its surface. In this sense, the stamped pattern is considered as a part of the part quality. Some defects of the stamped pattern are the disappearance, lack of a part, and dirt. The feature of these defects are discussed first. The fixed-point sampling is considered which detects the existence of the character pattern at the observation point. The method is modified so that the decision can be made at the observation point along the stroke. Furthermore, a character defect detection system is proposed which can shift the observation point in horizontal and vertical directions so that the system can cope with the variation of the position of the character. A dedicated image processing device was developed to perform the defect detection with high speed. The architecture and the operation of the system are described. The system is advantageous in that the high-speed operation is realized by the pipeline control for a series of processings, from the parallel read-out of the local patterns in the image memory to the matching operation. Finally, the configuration of the experimental system is described and the results are shown for the automatic outlook inspection for the stamped pattern of the actual electronic part, thereby indicating the usefulness of the proposed system.

Consideration on automatic defect detection algorithm for stamped patterns in electronic parts

Central Research Laboratory, Hitachi, Ltd., Kokubunji, Japan 185 One of the most important problems in the quality inspection of printed characters, monitoring of printing devices, and evaluation of character recognition devices, is the automatic quality evaluation of the printed character for the character patterns stamped on the object surface or on a paper sheet. This paper considers the characters stamped on the surface of an electronic part such as transistor and integrated circuit, and reports on the result of comparison of defect detection methods for the automatic outlook inspection. First, properties of the stamped pattern, which is the object of inspection, are described, indicating the problems in detecting the defects such as lack, smudge and blur. Then three realizations of the defect detection are proposed: (1) a weighted matching is made with the reference pattern; (2) the reference pattern is divided spatially, and the matching is tried for the divided patterns; and (3) essential points are extracted from the core and background portions of the character, and a local pattern matching is tried. Finally, those defect detection methods are implemented on a computer, and an experiment was made for the actual stamped patterns on the transistor. The results for those methods are compared, and their effectiveness and the range of applications are indicated.