JPH10103931A - Appearance inspection method for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To upgrade accuracy, stability, quickness and the like in the inspection of the appearance of electronic components by image processing. SOLUTION: The appearance of a laminated ceramic capacitor 1 as electronic component is taken by a color TV camera 6 and an image data alone is processed pertaining to light with a specified wavelength allowing better extraction of the features of the appearance, for example, light of red to generate a concentration histogram. The concentration histogram of a product to be inspected is compared with that of an acceptable product to judge the propriety of the appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the appearance of an electronic component by image processing.

[0002]

2. Description of the Related Art In order to determine the quality of an electronic component such as a multilayer ceramic capacitor, the appearance of the electronic component is inspected. By performing this appearance inspection, the electrode formed on the outer surface of the component body has a shortage or excessive area, application to an undesired area, discoloration, and further, regarding the component body, discoloration and cracking,
Parts with chipping or the like are removed.

At present, the above-described appearance inspection mainly depends on visual observation of an operator. Therefore, applying image processing technology to automate this inspection,
This is important for labor saving.

[0004]

As an inspection method using an image processing technique, a method of performing a black and white binarization process using a monochrome image and a method of performing a color image process have been attempted. However, both methods have problems to be solved. First, in the method using a monochrome image, it is impossible to extract a subtle color difference in appearance.For example, when the surface of the component body is made of ceramic, a difference in the color of the ceramic depending on the raw material causes an erroneous determination. May be

[0005] On the other hand, the method based on a color image makes it possible to extract a subtle color difference. However, since it is necessary to process three colors of red, green and blue, the inspection apparatus becomes expensive and the luminance varies due to illumination fluctuation. Since the level fluctuates, the problem is encountered that the accuracy and stability of the test results are rather poor. SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic component appearance inspection method using an image processing technique that can solve the above-described problems.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a method for inspecting the appearance of an electronic component by image processing. The method includes the steps of selecting light of a specific wavelength that can be extracted in the manner described above, and processing image data obtained from the appearance of the electronic component based on the light of the specific wavelength.

Preferably, in the present invention, the step of processing the image data includes a step of creating a density histogram based on light of a specific wavelength. In the process of processing the image data, it is more preferable to compare the density histogram of the non-defective product with the density histogram of the inspected product.

[0008]

1 to 3 illustrate a method for inspecting the appearance of an electronic component according to an embodiment of the present invention. FIG. 1 is a plan view showing the appearance of a chip-shaped multilayer ceramic capacitor 1 as an example of an electronic component. FIG. 2 is a block diagram schematically illustrating an appearance inspection apparatus for an electronic component. FIG. 3 shows a density histogram obtained by performing image processing on the appearance of the multilayer ceramic capacitor 1 shown in FIG.

Referring to FIG. 1, a multilayer ceramic capacitor 1 includes a rectangular parallelepiped component body 2.
The electrodes 3 and 4 serving as terminals are respectively formed on both end portions and on the outer surface. For example, electrodes 3 and 4 are silver, and component body 2 has an intermediate color between green and blue. Therefore, in order to collect all the image information on the appearance of such a multilayer ceramic capacitor 1, a color image pickup device is basically required, and it is necessary to process the respective image data of red, green and blue. However, in this embodiment, the red light is selected as light of a specific wavelength from which the appearance characteristics of the multilayer ceramic capacitor 1 can be well extracted, and an image obtained from the appearance of the multilayer ceramic capacitor 1 based on the red light. The data is processed. According to the experiment, the multilayer ceramic capacitor 1
In the case of such ceramic electronic components, it has been found that individual differences are less likely to occur when the wavelength is longer, so that red light is preferred.

In image processing, more specifically,
As shown in FIG. 2, the multilayer ceramic capacitor 1 includes:
White light is provided from a light source 5 and the multilayer ceramic capacitor 1 is imaged by a color television camera 6 as an image sensor. Of the video signals obtained from the camera 6, only the red video signal is extracted, the video signal is converted into a digital signal by the A / D conversion circuit 7, and the digital data is calculated by the calculation circuit 8, This calculation result is output.

Although the light source 5 supplies white light, red monochromatic light may be supplied. When a monochromatic red light is provided, a monochrome camera may be used instead of the color television camera 6. Based on the calculation results obtained as described above, a density histogram as shown in FIG. 3 is created. This density histogram is
Based on the red light, the appearance characteristics of the multilayer ceramic capacitor 1 are well extracted. In FIG.
(A) shows the case of a non-defective product, (b) shows the case where the area of the electrode 3 or 4 is small, and (c) shows the case where the electrode 3 or 4 is discolored.

For example, in FIG. 3A and the like, the low concentration peak indicates the concentration of the part body 2, and the high concentration peak indicates the concentration of the electrodes 3 and 4.
The peak value and the distribution width (dispersion) due to the part of the component body 2 and the peak value and the distribution width (dispersion) due to the electrodes 3 and 4 are as follows.
It is confirmed that if the sample is a non-defective product, they approximately match in the form as shown in FIG.

On the other hand, when the area of the electrode 3 or 4 is small or when the electrode 3 or 4 is discolored, the respective density histograms are as shown in FIG. 3 (b) or (c). Is different from the density histogram of the non-defective product shown in FIG. Similarly, even when the area of the electrode 3 or 4 is excessive, applied to an undesired area, or when the component body 2 is cracked or chipped, the density histograms of the respective components are the same as those of non-defective products. Gives a different pattern.

Therefore, when the average density histogram of non-defective products shown in FIG. 3A is used as a standard pattern, and this is compared with the density histogram of the inspected product by a method such as pattern matching, a multilayer ceramic capacitor can be obtained. The quality of the external appearance can be quickly determined, and a good product and a defective product can be efficiently sorted according to the quality determination. In FIG. 2, the appearance inspection is simply performed for one multilayer ceramic capacitor 1. However, a plurality of multilayer ceramic capacitors 1 that are within the field of view of the camera 6 can be inspected simultaneously.

The present invention, as shown in the illustrated embodiment,
The present invention can be applied not only to a multilayer ceramic capacitor but also to other electronic components.

[0016]

As described above, according to the present invention, light of a specific wavelength from which the characteristics of the external appearance of an electronic component can be satisfactorily extracted is selected, and an image obtained from the external appearance of the electronic component based on the light of the specific wavelength. Since data is processed, it is possible to extract subtle color differences in appearance, unlike the method of performing black-and-white binarization processing using a monochrome image, and to inspect using color image processing technology. In contrast, there is no need to process the three colors of red, green, and blue, so that the inspection apparatus does not become expensive, and fluctuations in the luminance level due to illumination fluctuations are suppressed, so that the accuracy and stability of the inspection results are reduced. It can be better.

In the present invention, when processing image data, if a density histogram based on light of a specific wavelength is created, the density histogram can be used to provide an insufficient or excessive electrode area or to provide an electrode with an undesired area. Information regarding the presence or absence of a defect such as discoloration, and furthermore, cracking or chipping of the component body can be expressed globally. In the process of processing the image data, if the density histogram of the non-defective product is compared with the density histogram of the inspected product, the appearance of the inspected product can be determined efficiently and quickly.

[Brief description of the drawings]

FIG. 1 is a plan view showing a multilayer ceramic capacitor 1 as an example of an electronic component to which a visual inspection method according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram schematically showing an appearance inspection apparatus for the multilayer ceramic capacitor 1 shown in FIG.

FIGS. 3A and 3B show density histograms obtained by performing image processing on the appearance of the multilayer ceramic capacitor 1 shown in FIG. 1, wherein FIG. 3A shows a non-defective product, and FIG. In this case, (c) shows the case where the electrode 3 or 4 has changed color.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 multilayer ceramic capacitor 2 component body 3, 4 electrode 5 light source 6 color television camera

Claims (3)

[Claims] 1. A method for inspecting an external appearance of an electronic component by image processing, wherein light of a specific wavelength capable of satisfactorily extracting characteristics of the external appearance of the electronic component is selected. An appearance inspection method for an electronic component, comprising: a process for processing image data obtained from an appearance of a component. 2. The electronic component appearance inspection method according to claim 1, wherein the step of processing the image data includes a step of creating a density histogram based on the light of the specific wavelength. 3. The electronic component appearance inspection method according to claim 2, wherein the step of processing the image data further includes a step of comparing a density histogram of a non-defective product with a density histogram of an inspected product.