JP2001343337A - Printed wiring board defect detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board defect detector by image processing. SOLUTION: An image inputted from a CCD camera 1 is stored in an image buffer 8 and is sent to a silk-printed part extraction threshold value circuit 10 in the case of an oblique illumination picture image, to a plated part extraction threshold value circuit 11 in the case of coaxial vertical illumination, and to a round part detecting circuit 13 by passing a hole and cutout extracting threshold value circuit 12 in the case of transmission illumination by an image switch-over circuit 9 to extract an image having brightness exceeding a predetermined brightness in each threshold value circuit. These extracted images are sent to an image division buffer 14 and are stored as image division region data. Defect detection sensitivity of a plated part, a silk-printed part, and a round part can be independently selected in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an electronic circuit board such as a printed circuit board, and the like. The present invention relates to a substrate defect detection device for detecting a substrate defect.

[Prior Art] When detecting a defect from information of a picked-up image, in a conventional defect detection apparatus, the defect detection sensitivity is set to be the same in all regions of the image, and the defect detection sensitivity of an image with less noise is reduced. When the sensitivity is set in an area, a large number of pseudo defects (portions determined to be defective but not a defect) are detected in a large amount in a noisy image area, and in order to avoid this, it is necessary to adjust the defect detection sensitivity in a noisy area. However, there is a problem that a defect to be detected cannot be detected.

[Problems to be solved by the invention]
The present invention has been made to solve this problem, and by using the present invention, a substrate defect detection device has become practical. Particularly, because of the large amount of noise, it is considered to be the most difficult among the substrate inspection devices. Therefore, it is not possible to automate, and it becomes possible to automate the inspection of the final board (final state before mounting components on the board in the state where the resist was applied to the board) which was conventionally visually inspected by humans, Along with labor savings, he released workers from the heavy labor of visual inspection.

[Means for Solving the Problems] In the inspection of the substrate, the final substrate has a lot of noise when viewed in terms of image, and in the conventional method in which all regions have the same defect detection sensitivity, the defect is not detected. Detection is nearly impossible. Therefore, in the present invention, a method is employed in which the substrate is divided into a plated portion, a silk-printed portion, a round portion, and other portions, and the optimum defect detection sensitivity is independently set in each region. As a result of the experiment, it was found that the magnitude of the noise of the substrate can be divided for each of the above portions. Therefore, if the defect detection sensitivity is set for each of the above parts, a device that can prevent a pseudo defect and detect only an actual defect becomes possible. It would take a very long time for a human to classify each part as described above, which is practically impossible. In the present invention, the classification for each part,
This is done by making good use of changes in the image caused by illumination. As a result of the experiment, when the substrate is irradiated with coaxial epi-illumination, the plated portion is close to total reflection, and a very bright image is obtained only in the plated portion. In the present invention, using this phenomenon, a bright portion imaged by coaxial epi-illumination is recognized as a plated portion. Also, as a result of the experiment, it was found that the silk-printed portion glows brightly when the substrate is subjected to oblique illumination that irradiates the substrate in an oblique direction. This is thought to be due to irregular reflection due to the swelling of the silk printing section. In the present invention, utilizing this phenomenon, a bright image portion obtained by oblique illumination is determined to be a silk-printed portion. Further, in the present invention, the substrate is illuminated from the side opposite to the imaging device, and a bright place is determined as a hole or a notch in the substrate, and the periphery thereof is detected as a round part. By the means as described above, in the present invention, a defect detection device for a final substrate is realized.

[Embodiment of the Invention] FIG. 1 shows an example of an illumination configuration according to the present invention, in which coaxial epi-illumination (2) for extracting a plating image and oblique illumination for extracting a silk portion. Illumination (3), transmitted illumination (4) for extracting a round portion, illumination controller (6) for switching these illuminations, CCD camera (1) for capturing an image, and captured image Image processing device for analyzing images (7)
Consists of FIG. 2 shows an example of an initial setting circuit of the image processing apparatus according to the present invention. An image input from a CCD camera (1) is stored in an image buffer (8), and is tilted by an image switching circuit (9). The illumination image passes through the silk extraction threshold circuit (10), the coaxial incident illumination passes through the plating extraction threshold circuit (11), and the transmitted illumination passes through the hole / notch extraction threshold circuit (12). , Round part detection circuit (13)
, And each threshold circuit extracts an image having a certain brightness or higher. These extracted images are stored in an image segmentation buffer (1
4) and stored as divided area data of the image. The image switching circuit (9) is a lighting switching circuit (15)
And sends information to switch between coaxial epi-illumination, oblique and transmissive illumination. FIG. 3 shows an example of an inspection circuit of the image processing apparatus. An image picked up by a CCD camera is stored in an image buffer (8), sent to an area switching circuit (15), and sent to an image division buffer (14). From the silk part defect detection circuit (1
6), the plating part defect detection circuit (17), the round part defect detection circuit (18), and the other area defect detection circuit (19), which are sent to determine whether the defect is a defect or not. ), And the defect image is displayed.

[Effects of the Invention] By using the present invention, it is possible to inspect the final substrate, which has been difficult in the past, and it is possible to save labor and to relieve the worker from severe visual inspection.

[Brief description of the drawings]

[FIG. 1] shows an example of an illumination configuration, [FIG. 2] shows an example of an initialization circuit of the image processing apparatus of the present invention, and [FIG. 3] shows an example of an image processing apparatus of the present invention. 5 illustrates an example of an inspection circuit.

[Explanation of symbols]

 1 is a CCD camera 2 is a coaxial epi-illumination 3 is an oblique illumination 4 is a transmission illumination 5 is a substrate 6 is an illumination controller 7 is an image processing device 8 is an image buffer 9 is an image switching circuit 10 is a silk printing portion extraction threshold circuit 11 is a plating portion Extraction threshold circuit 12 is a hole, notch extraction threshold circuit 13 is a round part detection circuit 14 is an image division buffer 15 is an area switching circuit 16 is a silk part defect detection circuit 17 is a plating part defect detection circuit 18 is a round part defect detection circuit 19 Is the other area defect detection circuit 20 is the image defect display circuit

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[Procedure amendment]

[Submission date] August 3, 2000 (2000.8.3)

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 shows an example of a lighting configuration of the present invention.

FIG. 2 illustrates an example of an image processing initial setting circuit according to the present invention.

FIG. 3 shows an example of an inspection circuit of the image processing apparatus of the present invention.

[Description of References] 1 is a CCD camera 2 is a coaxial epi-illumination 3 is an oblique illumination 4 is a transmitted illumination 5 is a substrate 6 is an illumination controller 7 is an image processing device 8 is an image buffer 9 is an image switching circuit 10 is a silk printing portion extraction threshold Circuit 11 is a plating portion extraction threshold circuit 12 is a hole and cutout portion extraction threshold circuit 13 is a round portion detection circuit 14 is an image division buffer 15 is an area switching circuit 16 is a silk portion defect detection circuit 17 is a plating portion defect detection circuit 18 is a round Part defect detection circuit 19 is other area defect detection circuit 20 is image defect display circuit

Claims (5)

[Claims] An apparatus for detecting defects in an electronic circuit board such as a printed circuit board, wherein a coaxial epi-illumination for illuminating an inspection object from a vertical direction and an oblique illumination for illuminating an inspection object from an oblique direction are combined. A substrate defect detection device for detecting a defect by means of a substrate. 2. A substrate defect detecting device, wherein a plated portion and a silk printed portion of a substrate are separated when detecting a defect of the substrate, and the detection sensitivity of the defect is set independently in each region. 3. A substrate defect detecting device which detects a plated portion of a substrate by utilizing the fact that the plated portion shines brightly when the substrate is irradiated with coaxial incident illumination. 4. A substrate defect detecting device for detecting a silk-printed portion of a substrate by utilizing the fact that the silk-printed portion shines brightly when the substrate is irradiated with oblique illumination. 5. A substrate is illuminated with light from the opposite side of the imaging device, a bright portion of an image obtained by the imaging device is determined to be a hole or a notch in the substrate, and the periphery thereof is detected as a round portion. A substrate defect detection device capable of setting the defect detection sensitivity of a round part independently of others.