JPH04357444A - Apparatus for inspecting printed circuit board - Google Patents

Abstract

PURPOSE:To achieve the reduction of inspection result, the enhancement of inspection accuracy and the facilitation of repairing work in the inspection of a printed circuit board. CONSTITUTION:A first reference value memory 205 registering the image of a printed circuit board to which the proper wiring of conductors is applied as a reference board, an input device taking in the image of the printed circuit board becoming an inspection object and a pre-processing circuit 203 for the pre-processing of the image taken in by the input device are mounted. Further, a second memory 204 holding the image processed by the pre-processing circuit 203, a comparison circuit comparing the images of the first and second memories 205,204 to calculate the degree of coincidence of both of them and a display device 4 displaying an inspection result on the basis of the output of the comparison circuit are mounted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board inspection apparatus, and more particularly to an inspection apparatus for inspecting the wiring condition of conductors on a printed circuit board.

0002

2. Description of the Related Art Conventionally, the wiring condition of conductors on printed circuit boards has been inspected by visual inspection or electrical inspection. In the former case, it is difficult to train and secure workers;
In addition, there was a problem of lack of stability and speed of inspection accuracy. In addition, in the latter case, in order to perform an inspection in a semi-finished product state, it is necessary to create a jig and an inspection program, and if the inspection is performed in a state close to the product state, the cost of repairing defective products is large. Become.

0003

[Problems to be Solved by the Invention] This invention was devised to solve these conventional problems, and has the following advantages:
The purpose of the present invention is to provide a printed circuit board inspection device that improves the inspection system and facilitates repair work.

0004

[Means for Solving the Problems] A printed circuit board inspection device according to the present invention compares a board on which conductor wiring has been properly performed and a board to be inspected as images, and based on the degree of agreement between the two, the board to be inspected is inspected. It is used to judge the quality of the product. According to the inspection device according to the present invention, no visual inspection or electrical inspection is required.

[0005]

Embodiment Next, an embodiment of the inspection apparatus according to the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, the inspection apparatus includes a video camera 1 as an input system, an image processing section 2, a terminal device 3, and a display device 4 as an output system. The image processing section 2 further includes a control circuit 201, a central processing unit 202, a preprocessing circuit 203, a memory 204, and a reference value memory 205.

[0006] First, an image of a reference printed circuit board on which conductor wiring has been properly performed is captured through a camera 1, and a preprocessing circuit performs noise processing. The central processing unit performs binarization and thinning processing on the noise-processed image. and,
The thinned image is stored in the reference value memory. Next, noise processing is performed on the image of the printed circuit board to be inspected.
Binarization and thinning are performed, and the thinned image is stored in memory. Then, the central processing unit performs pattern matching between the thinned image of the printed circuit board to be inspected and the thinned image of the reference printed circuit board already stored in the reference value memory. That is, the central processing unit has a function as a comparison circuit.

[0007] In a thinned image, each figure is narrowed to one pixel width, so long and narrow figures such as conductor patterns are
The feature of its extension direction is emphasized. That is, in a simple binary image, a conductor pattern with a cut causes only a slight change in area, but in a thin line image, the cut is enlarged and appears as a change in length. Therefore, defects in the conductor pattern can be easily detected. The same applies to improper joining of patterns; the spacing between the regular patterns to be separated is expanded due to line thinning, and the difference between the regular patterns and the defective patterns becomes significant. Note that for a relatively noticeable defect, it is not necessarily necessary to perform line thinning, and a sufficient defect determination can be made by calculating the degree of matching by pattern matching of a multivalued image or a binary image.

[0008] As a result, as shown in FIG. 2, parts such as conductor wiring mistakes (a), improper wiring connections (b), and broken wires (c) can be matched with the thinned image of the reference printed circuit board. First, it will be judged as a defective printed circuit board. These processes performed by the image processing section 2 are instructed through a terminal device such as a computer, and the calculated results are outputted to the display section 4 via an interface to determine the quality of the printed circuit board to be inspected. If the suitability of conductor wiring is determined by processing image data in this way, high-speed inspection is possible and labor savings can also be realized.

[0009]

As described above, according to the present invention, it is possible to provide an apparatus that can save labor, improve inspection accuracy, and facilitate repair work in inspecting the quality of printed circuit boards.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a diagram for explaining thinned images of a reference printed circuit board and a defective inspected printed circuit board.

[Explanation of symbols]

Claims (2)

[Claims] 1. A first memory that registers an image of a printed circuit board on which conductor wiring has been properly performed as a reference board;
An input device that captures an image of a printed circuit board to be inspected, a preprocessing circuit that preprocesses the image captured by this input device, and a second circuit that holds the image processed by this preprocessing circuit.
, a comparison circuit that compares images in the first and second memories to determine the degree of agreement between the two, and a display device that displays inspection results based on the output of the comparison circuit. Device. 2. The printed circuit board inspection apparatus according to claim 1, wherein the image is thinned and the degree of coincidence of the thinned image is determined.