Pattern detecting apparatus

[54] PATTERN DETECTING APPARATUS

[75] Inventors: Yasuhiko Hara, Machida; Koichi Karasaki, Hadano; Noriaki Ujiie; Akira Sase, both of Katsuta, all of Japan

[73] Assignee: Hitachi, Ltd., Tokyo, Japan

[21] Appl. No.: 686,007

[22] Filed: Dec. 24, 1984

[30] Foreign Application Priority Data

Dec. 26, 1983 [JP] Japan 58-243850

Dec. 26, 1983 [JP] Japan 58-243851

[51] Int. CI.4 G01R 31/02

[52] U.S. CI. 324/73 PC; 324/158 R;

356/394; 356/398; 358/101; 358/106

[58] Field of Search 324/73 PC, 158 R, 158 D,

324/158 T; 358/101, 105, 106, 111, 113; 356/376, 394, 398; 250/302; 178/105, 106

[56] References Cited

U.S. PATENT DOCUMENTS

FOREIGN PATENT DOCUMENTS 4898886 1/1973 Japan .

A pattern detecting apparatus for inspecting a printed wiring board is disclosed in which a fluorescent image formed by the fluorescent light from the substrate of the printed wiring board and an image formed by the reflected light from the wiring pattern of the printed wiring board are both used because a wiring material which is left on an undesired portion of the substrate and has low reflectivity, is detected only at the fluorescent image and a defective portion of the wiring pattern where a surface layer thereof peels off, is detected only at the image formed by the reflected light, the image used for detecting the above defective portion is preferably formed by the reflected infrared light from the wiring pattern for the reason that infrared light is insensitive to a shallow flaw in the surface of the wiring pattern, and the fluorescent image and the infrared image are processed by a detection circuit, and then compared with each other to detect a pattern defect on the basis of a difference between the images thus processed.

9 Claims, 33 Drawing Figures