Electronic component inspection method and electronic component manufacturing method

Abstract

To improve the accuracy of inspection by captured images.SOLUTION: An electronic component inspection method according one aspect includes: an image-capturing step for capturing an image of an inspection object which is either an electronic component or an in-process article of the electronic component against a colored background; a discrimination step for discriminating between a section of the inspection object and a section of the background in the captured image of the inspection object by a hue; and an inspection step for inspecting the inspection object by the section of the inspection object discriminated in the captured image.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for inspecting an electronic component and a method for manufacturing an electronic component. [Background technology]

[0002] As the applications of electronic components become more diverse, they are being asked to meet requirements beyond the traditional need for miniaturization. A typical example of such a requirement is that electronic components used in communication infrastructure, industrial equipment, automobiles, etc. must be able to withstand harsh environments such as high temperatures and humidity without causing any malfunctions.

[0003] One of the reasons for the failure of electronic components in harsh environments is thought to be instability in molding precision and assembly precision during the electronic component manufacturing process. For this reason, there is a need to improve and stabilize the precision of the electronic component manufacturing process, which in turn requires improvements in dimensional measurement, etc. However, in recent electronic component manufacturing processes, the state of the electronic components changes with each process, the tables used for transportation are also changed, and component sizes can be less than 1 mm, making visual inspection and dimensional measurement difficult.

[0004] For example, Patent Document 1 discloses a technique for calculating a plurality of position coordinates on the outermost peripheral surface of a coil from angle detection values ​​obtained by an encoder and distance measurement values ​​obtained by a measuring device. Furthermore, for example, Patent Document 2 discloses a technology for an appearance inspection device that performs predetermined inspections by processing captured images, in which, during inspection, white illumination light is irradiated onto the object to be inspected from all directions, and colored illumination light is irradiated from specific directions according to the inspection item. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-118195 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-71577 Summary of the Invention [Problem to be solved by the invention]

[0006] Inspection using photographed images is applicable to a wide range of objects and the installation conditions for the inspection equipment are relaxed, so it is expected to be introduced into appearance inspection and dimensional measurement inspection in the manufacturing process of electronic components. However, as electronic components become smaller, scratches and dirt on the plates that transport the components become noise when determining the boundary between the electronic component and the background, making it difficult to accurately capture the boundary. For this reason, it is difficult to introduce dimensional measurement inspections using captured images in the actual manufacturing process of electronic components, and it is also difficult to guarantee dimensional specifications.

[0007] In view of the above circumstances, an object of the present invention is to improve the accuracy of inspection using captured images. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, an electronic component inspection method according to one aspect of the present invention includes a photographing step of photographing an inspection object, which is either an electronic component or an intermediate product in the manufacturing process of an electronic component, against a colored background to obtain photographed images of the inspection object and the background, a discrimination step of determining inspection object data of the inspection object from the photographed image based on the difference in color between the inspection object and the background, and a comparison step of inspecting the inspection object data by comparing it with an inspection standard.

[0009] According to an electronic component inspection method according to one aspect of the present invention, the photographing step involves placing the object to be inspected on a colored background, and illuminating the object to be inspected and the background with a light source biased to a color different from that of the background, thereby photographing the object to be inspected. According to the electronic component inspection method of one aspect of the present invention, the background portion has a higher saturation than the inspection target.

[0010] According to the electronic component inspection method of one aspect of the present invention, the background portion is red, and the light from the light source has a peak in the blue wavelength region. In the electronic component inspection method according to one aspect of the present invention, the determining step obtains the inspection object data by determining based on both saturation and hue.

[0011] According to an electronic component inspection method according to one embodiment of the present invention, the photographing step obtains a plurality of photographed images of one of the inspection objects with different focus positions on the inspection object, the discrimination step obtains a plurality of pieces of inspection object data for each of the plurality of photographed images, and the comparison step compares each of the plurality of pieces of inspection object data with an inspection standard to perform a three-dimensional inspection of the electronic component.

[0012] A method for manufacturing an electronic component according to one aspect of the present invention includes the above-described manufacturing process having a plurality of steps; and an inspection step of providing the inspection object in a plurality of the steps and inspecting the inspection object by the inspection method. [Effects of the Invention]

[0013] According to the present invention, the accuracy of inspection using captured images is improved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing a coil component to be manufactured and inspected; [Figure 2] FIG. 2 is a bottom view showing the coil component to be manufactured and inspected. [Figure 3] 1A to 1C are diagrams illustrating an example of a manufacturing method for manufacturing a coil component. [Figure 4] FIG. 10 is a diagram showing a core member as an example of an intermediate product. [Figure 5] FIG. 1 illustrates an example of an inspection system. [Figure 6] FIG. [Figure 7] FIG. [Figure 8]FIG. 1 is a spectral distribution diagram showing the spectrum of a white LED. [Figure 9] 6 is a diagram showing an example of an inspection method executed by the inspection system shown in FIG. 5. [Figure 10] 10A to 10C are diagrams each showing a schematic example of a processing result in each step shown in FIG. 9. [Figure 11] 10 is a table showing the results of examining coordinate values. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (such as usage conditions and usage environment).

[0016] The technical scope of the present invention is defined by the claims and is not limited by the following specific embodiments. The drawings used in the following description may differ in scale and shape from the actual structure to make each component easier to understand. The correspondence between the drawings may not strictly correspond to each other to simplify the description. Components shown in previously described drawings may be referenced as appropriate in the description of subsequent drawings.

[0017] <Electronic components> 1 and 2 are diagrams showing coil components to be manufactured and inspected, with Fig. 1 showing a perspective view and Fig. 2 showing a bottom view. In this embodiment, a coil component 100, which is an example of an electronic component, is the object of manufacture and inspection. In this embodiment, as will be described later, an intermediate product, which is an intermediate stage in the manufacture of the coil component 100, is also the object of inspection. An intermediate product is formed during manufacturing and is ultimately included in the electronic component. Therefore, scraps and the like generated during the manufacturing process do not fall under the category of intermediate products.

[0018] 1 and 2 is, as an example, a wound coil component 100 having a drum core. The size of the coil component 100 is such that the smallest dimension among the length, width, and depth is 6 mm or less. Note that the size of the coil component 100 may be such that the smallest dimension among the length, width, and depth is 3 mm or less, or 1 mm or less.

[0019] The coil component 100 has a magnetic substrate 11, external electrodes 12, and an exterior portion 13. The coil component 100 may not have the exterior portion 13, or may have a non-magnetic substrate instead of the magnetic substrate 11. Magnetic substrate 11 is a drum core, and has, for example, an upper flange 111 and a bottom flange 112, and has a winding core connecting upper flange 111 and bottom flange 112 inside coil component 100 (not shown).

[0020] The external electrode 12 is formed of, for example, solder, and is provided on, for example, the bottom surface of the coil component 100, which is the surface of the bottom flange 112. The coil component 100 has inside it a coil conductor in which, for example, a conducting wire is wound around a winding core of the magnetic base 11, and a lead wire 14 drawn out from the coil conductor is connected to the external electrode 12. The exterior part 13 is made of, for example, resin, and covers and protects the outer periphery of the coil conductor.

[0021] <Manufacturing method> FIG. 3 is a diagram showing an example of a method for manufacturing the coil device 100. In step S101, a compact containing a magnetic material is formed by, for example, powder pressing, sheet forming, or molding.

[0022] In step S102, the dimensions and outer shape of the molded body are inspected. Any molded body whose dimensions do not meet the manufacturing tolerances or that has chips or cracks in its outer shape is discarded. Details of the inspection in step S102 will be described later. In step S103, the compact is heat-treated to form a core member. Depending on the raw materials used for the compact, the heat treatment may involve thermosetting at a temperature of 200°C or less, or sintering at a temperature of 600°C or more, or 1000°C or more.

[0023] In step S104, the dimensions and outer shape of the core member are inspected. Core members whose dimensions do not meet the manufacturing tolerances or whose outer shape has chips or cracks are discarded. Details of the inspection in step S104 will be described later.

[0024] FIG. 4 is a diagram showing a core member as an example of an intermediate product. The core member 150 is an intermediate product that will ultimately become the magnetic substrate 11, and has an upper flange 151, a bottom flange 152, and a winding core 153 that connects the upper flange 151 and the bottom flange 152.

[0025] 3, a conductor is wound around the winding core 153 of the core member 150 to form a wound portion of a coil conductor. In addition, both ends of the conductor are pulled out from the wound portion and fixed to the bottom flange 152 of the core member 150. In step S106, the outer periphery of the circumferential portion is covered with a resin material, and an exterior portion that will ultimately become the exterior portion 13 is formed.

[0026] In step S107, the dimensions and outer shape of the finished product, including the outer casing, are inspected. Products whose dimensions do not meet the manufacturing tolerances due to resin overflow or other reasons, or products with chips or cracks in their outer shape, are discarded. Details of the inspection in step S107 will be described later.

[0027] In step S108, external electrodes 12 are formed on the surface of bottom flange 152 with solder, and coil component 100 is completed. In step S109, the dimensions and outer shape of the coil component 100 are inspected. Coil components 100 whose dimensions do not satisfy the manufacturing tolerances or that have chips or cracks in their outer shape are discarded. The following describes the details of the tests performed in steps S102, S104, S107, and S109.

[0028] <Inspection system> Before describing the test in detail, the system used in the test will first be described.

[0029] FIG. 5 is a diagram illustrating an example of an inspection system. Inspection system 200 shown in Fig. 5 is a system that is arranged in a part of a production line that manufactures coil component 100, and that inspects an inspection object that is at least one of coil component 100 and an intermediate product in the manufacturing process of coil component 100. In this embodiment, inspection system 200 shown in Fig. 5 is used in each of steps S102, S104, S107, and S109 in Fig. 3. Fig. 5 shows coil component 100 as an example of an inspection object.

[0030] The configuration of inspection system 200 shown in Fig. 5 is one example, and inspection systems with other configurations may be used in the inspection method of the present invention. Furthermore, inspection systems 200 with the same configuration may be used in steps S102, S104, S107, and S109 of Fig. 3, or inspection systems with different configurations may be used. In this embodiment, it is assumed that inspection systems 200 with the same configuration are used. The inspection system 200 includes a camera 210 as a detector, an LED light 220 as a light source, a moving stage 230 on which the coil component 100 to be inspected and the plate 300 as the background are placed, and a control device 240 that controls each of them.

[0031] The camera 210 captures an image of the object to be inspected, and the LED lighting 220 illuminates the object to be inspected with white light. The moving stage 230 is, for example, an XY stage, and moves the inspection object within the angle of view of the camera 210. In the example shown in Fig. 5, the moving stage 230 moves a plurality of inspection objects arranged on a plate 300 for transporting the inspection objects together with the plate 300, and moves each inspection object sequentially into the angle of view of the camera 210.

[0032] FIG. 6 is a diagram showing the plate 300, and FIG. 7 is a partially enlarged view of the plate 300. As shown in FIG. Plate 300 is used to transport coil component 100 and in-process products in part or all of the manufacturing process shown in Fig. 3. Plate 300 is made of a material that can withstand heat treatment, is highly durable, and does not easily generate static electricity, such as aluminum or stainless steel. In the following description, an aluminum plate 300 is used as an example.

[0033] The plate 300 is provided with a recess 310 and a positioning hole 320. The positioning hole 320 is used to position the plate 300 relative to the moving stage 230. A plurality of depressions 310 are provided in a vertical and horizontal array on the entire surface of the plate 300. A coil component 100 or a partially completed product is individually placed in each depression 310. Each depression 310 is approximately square in shape, with rounded corners. Two of the depressions 310 shown in FIG. 6 are shown in FIG. 7.

[0034] The surface 330 of the plate 300, including the inside of the recess 310, is colored anodized, and is colored red, for example. On the other hand, the light of the LED lighting 220 shown in FIG. 5 is white light, but is biased towards blue, which is different from the color of the plate 300.

[0035] FIG. 8 is a spectral distribution diagram showing the spectrum of a white LED. The horizontal axis of FIG. 8 represents wavelength, and the vertical axis represents relative energy. The white LED, which is the light source of the LED lighting 220, is a combination of a blue LED and a yellow phosphor. Therefore, the spectrum of the white LED has a peak in the blue wavelength range of 450 nm to 495 nm, and the energy of the peak is more than twice the energy in other wavelength ranges different from the wavelength range of the color to which the peak belongs. As a result, the light of the LED lighting 220 is bluish white light.

[0036] Since white LEDs have a peak in the blue wavelength range of 450 nm to 495 nm, a spectral reflectance characteristic having a peak outside the blue wavelength range of 450 nm to 495 nm is selected for either the inspection object or the background. For example, in this embodiment, the color of the inspection object is a color having a peak in the blue wavelength range, and a color having a peak outside the blue wavelength range is selected for the background. Furthermore, if the color of the inspection object is a color having a peak outside the blue wavelength range, a color having a peak in the blue wavelength range is selected for the background.

[0037] 5 controls the camera 210, the LED lighting 220, and the moving stage 230 to capture images of the inspection objects one by one, thereby acquiring captured images of each inspection object. Based on the captured images, the control device 240 inspects the dimensions and external shape of the inspection object.

[0038] <Testing method> FIG. 9 is a diagram showing an example of an inspection method executed by inspection system 200 shown in FIG. 5, and FIG. 10 is a diagram showing a schematic example of a processing result in each step shown in FIG. In step S201, the inspection object is moved by the moving stage 230 into the angle of view of the camera 210, and a color image of the inspection object is captured by the camera 210. When capturing the image in step S201, as an example, the imaging conditions are such that a red plate serves as the background and is illuminated with bluish illumination light. That is, in step S201, the inspection object is placed on a colored background, and the inspection object and the background are illuminated by a light source biased to a color different from that of the background, and then photographed. Furthermore, the background used in step S201 has a higher saturation than the inspection object. For example, the background is red, and the illumination light has a peak in the blue wavelength region. A photographed image 400 is obtained by color imaging. The photographed image 400 includes a red background 410, a portion 420 of the magnetic substrate, a portion 430 of the external electrode, and a portion 440 of the lead wire.

[0039] Although imaging in step S201 may be performed once for one inspection object, in this embodiment, imaging is performed multiple times with the focus adjusted on each of the top flange 111 and the bottom flange 112 of the magnetic base 11. In other words, multiple captured images with different focus positions on one inspection object are obtained. The focal position may be changed by adjusting the lens of the camera 210, by moving the camera 210, or by moving the inspection target using a Z stage or the like. In step S202, a specific color portion in the captured image is extracted based on coordinate values ​​in the HSV color space. The color extraction process may be performed based on coordinate values ​​in a color space other than the HSV color space, such as the Lab color space or the sRGB color space. In the HSV color space, colors are expressed using intuitively understandable parameters such as color vividness and brightness as coordinate values. Therefore, color extraction based on coordinate values ​​in the HSV color space enables color extraction that is less susceptible to variations in brightness and color tone due to light from outside the inspection system 200.

[0040] Specifically, in the color extraction process, the image portion of red, which is the color of plate 300, is extracted, and the captured image is divided into a background portion 450 and an object portion 460 containing the inspection object. The object portion 460 is used as inspection object data. That is, in step S202, inspection object data of the inspection object is obtained from the captured image 400 based on the difference in color between the object portion 460 of the inspection object and the background portion 450.

[0041] While plate 300, which serves as the background for photography, is colored and highly saturated, the colors of coil component 100 and the in-process product to be inspected are low in saturation, such as white, black, or gray, so discrimination based on color allows for accurate discrimination between background portion 450 and subject portion 460. In particular, the red plate is highly versatile because it has different colors for many types of electronic components.

[0042] If the plate 300 is colored and discrimination is performed based on color, even if there are steps, scratches, dirt, etc. on the plate 300, they will be accurately discriminated as background portion 450. Therefore, it is possible to handle small inspection objects that are greatly affected by scratches and dirt, and it is also possible to handle objects with complex shapes.

[0043] Furthermore, in this embodiment, the color of the LED illumination 220 is white with a blue bias, which differs from the red of the plate 300. Therefore, the color of the inspection object is a slightly bluish black or white, and since the background and the inspection object have different hues, the accuracy of distinguishing between the background portion 450 and the subject portion 460 is further improved. In other words, it is desirable that the plate 300 has one of the colors blue, green, yellow, orange, and red, and that the illumination light be light that is biased toward one of the colors blue, green, yellow, orange, and red other than the color of the plate 300.

[0044] In other words, it is desirable that the illumination light has a peak in a wavelength range of any of blue, green, yellow, orange, and red other than the color of the plate 300. The blue wavelength range is from 450 nm to less than 495 nm, the green wavelength range is from 495 nm to less than 570 nm, the yellow wavelength range is from 570 nm to less than 590 nm, the orange wavelength range is from 590 nm to less than 620 nm, and the red wavelength range is from 620 nm to less than 750 nm.

[0045] The extraction in step S202 is performed for each captured image 400 obtained by capturing images multiple times. That is, in step S202, multiple pieces of inspection object data are obtained from the multiple captured images 400. The part of the inspection object that is in focus appears clearly in the photographed image 400 as the subject part 460 and is determined to be part of the background part 450. On the other hand, the part of the inspection object that is out of focus does not appear clearly in the photographed image 400, but is mixed with the red color of the plate 300 and becomes part of the background part 450. In this way, a colored background in the photograph is also effective in extracting the three-dimensional outline of the inspection object.

[0046] In step S203, a pre-processing filter is applied to the subject portion 460 from which the background portion 450 has been removed to remove minute noise. In step S204, a reference line 500 is added to the subject portion 460, and the distances between the intersections 510, 520 where the outline of the subject portion 460 intersects with the reference line 500 are measured as the dimensions of the object to be inspected. The measured dimensions are then inspected to see if they satisfy the manufacturing tolerances. The outline of the subject portion 460 is also inspected to see if there are any defects or the like.

[0047] As described above, when multiple images are taken with different focuses, a dimensional inspection and an external shape inspection are performed on each of the top flange 111 and the bottom flange 112 of the magnetic base 11. As a result, it becomes possible to inspect the three-dimensional shape of the inspection object. That is, in step S204, each of the multiple pieces of inspection object data is compared with the inspection standard to perform a three-dimensional inspection.

[0048] The inspection method shown in Figure 9 enables stable measurement of the external dimensions of the object to be inspected, making it possible to automate inspections and other applications. Here, specific coordinate values ​​in the color extraction in step S202 will be considered.

[0049] FIG. 11 is a table showing the results of examining the coordinate values. Here, we investigated the color range for background extraction and considered multiple extraction ranges for hue, the H coordinate in the HSV color space, and saturation, the S coordinate. The extraction range for lightness, the V coordinate in the HSV color space, was fixed. The HSV color space used is a color space in which the coordinate values ​​of H, S, and V are expressed in 256 steps, ranging from 0 to 255. The H coordinate in the HSV color space is a coordinate that cycles continuously from 255 to 0.

[0050] For brightness, the fixed extraction range was set to 0 to 235 on the V coordinate. For saturation, the upper limit of the S coordinate was fixed at 255, and the lower limit was changed to 10, 30, 50, 70, and 90, respectively. For hue, the upper limit of the H coordinate was fixed at 5, and the lower limits, which passed through 0 and 255, were changed to 150, 220, and 250, respectively.

[0051] The extraction results are shown in the table in Figure 11 as "Excellent," "Good," or "Poor." "Poor" indicates that the influence of noise is large, resulting in false detection of dimensions and external shapes. "Good" indicates that the influence of noise is small, and false detection is suppressed. "Excellent" indicates that the influence of noise is extremely small, and there is no false detection.

[0052] It was confirmed that when the extraction range for the hue H coordinate is between 220 and 255, and between 0 and 5, the background is extracted accurately and false positives are reduced to a level that can be used for inspection, regardless of the extraction range for the saturation S coordinate. Furthermore, it was confirmed that when the lower limit for the saturation S coordinate is between 30 and 70, there are no false positives and highly accurate inspection is possible.

[0053] On the other hand, when the extraction range for the hue H coordinate was set to 250 to 255 and 0 to 5, the extraction conditions for red were too strict, and false detection occurred regardless of the extraction range for the saturation S coordinate. Furthermore, when the extraction range for the H coordinate of hue is set to 150 to 255 or 0 to 5, even slightly bluish areas are extracted. For this reason, when the lower limit of the S coordinate of saturation is set to 50 or less, false detection occurs, but when the lower limit is set to 70 or more, false detection is suppressed to a level that can be used for inspection.

[0054] In the above description, a wire-wound type coil component 100 in which copper wire is wound around a drum core is exemplified as the electronic component of the present invention, but the electronic component of the present invention may be a metal integrally molded type coil component or a laminated type coil component. Alternatively, the electronic component of the present invention may be a passive component such as a capacitor, resistor, or filter. The coil component 100 may be an inductor, a transformer, a filter, a reactor, or any of various other coil components. The coil component 100 may be a coupled inductor, a choke coil, or any of various other magnetically coupled coil components. The coil component 100 may be, for example, an inductor used in a DC / DC converter. The uses of the coil component 100 are not limited to those explicitly described in this specification.

[0055] Furthermore, although the above description shows an example in which the inspection object referred to in the present invention is transported on a plate, the inspection object referred to in the present invention may be transported on an index conveyor or a glass table. When the inspection object is transported on an index conveyor, the colored background is realized by a turntable with a colored surface. When the inspection object is transported on a glass table, the colored background is realized by a colored backlight.

[0056] Furthermore, although the above description shows an example in which multiple tests performed during the manufacture of electronic components are similar to each other, the manufacturing method of the present invention may also involve multiple tests of different types. Furthermore, in the above description, red is exemplified as the background color and bluish white light is exemplified as the illumination light, but a color other than red may be used as the background color, and light biased toward a color other than blue may be used as the illumination light. [Explanation of symbols]

[0057] 11 Magnetic substrate 12 External electrode 13 Exterior part 14 Leader 100 Coil parts 111 Upper flange 112 Bottom flange 150 Core member 151 Upper flange 152 Bottom flange 153 Spool 200 Inspection System 210 Camera 220 LED lighting 230 Moving Stage 240 Control Device 300 plates 310 Depression 320 Positioning hole 400 images 450 Background part 460 Subject part

Claims

1. an imaging step of photographing an inspection object, which is either an electronic component or an intermediate product in the manufacturing process of the electronic component, against a colored background to obtain photographed images of the inspection object and the background; a determining step of determining inspection object data of the inspection object from the photographed image based on a difference in color between the inspection object and the background; a collation step of inspecting the inspection target data against inspection standards; An inspection method for an electronic component comprising:

2. 2. The electronic component inspection method according to claim 1, wherein the photographing step is performed by placing the inspection object on a colored background and illuminating the inspection object and the background with a light source biased to a color different from that of the background.

3. The method for inspecting electronic components according to claim 2 , wherein the background portion has a higher saturation than the object to be inspected.

4. 3. The method for inspecting electronic components according to claim 2, wherein the background is red and the light from the light source has a peak in the blue wavelength region.

5. 3. The method for inspecting electronic components according to claim 2, wherein said determining step obtains said inspection object data by determining based on both saturation and hue.

6. The photographing step includes obtaining a plurality of photographed images of one of the inspection objects at different focus positions on the inspection object, The determining step obtains a plurality of pieces of inspection object data from a plurality of the photographed images, 2. The electronic component inspection method according to claim 1, wherein the collation step performs a three-dimensional inspection by comparing each of the plurality of inspection object data with an inspection standard.

7. the manufacturing process having multiple steps; an inspection step of providing the inspection object in a plurality of the steps and inspecting the inspection object by the inspection method according to claim 1; A method for manufacturing an electronic component having the above structure.

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