Visual inspection system for electronic components

Abstract

This invention provides a visual inspection system that can accurately detect peeling of terminal electrodes W of electronic components. [Solution] The lighting means consists of an upper lighting device 10 and a lower lighting device 20 arranged opposite each other above and below the transport means. The upper lighting device has an opening 15 for imaging the object to be inspected. Both the upper and lower lighting devices include a first light source group arranged perpendicular to the transport direction of the transport means, a second light source group arranged at an angle to the transport direction of the transport means, and a third light source group arranged horizontally to the transport direction of the transport means. The light source arrangement of the first and second light source groups is a staggered arrangement of red and blue light sources, while the light source arrangement of the third light source group is an arrangement of only green light sources. The imaging means has its imaging optical axis X positioned at an elevation angle (θ) of 5 to 60° with respect to the transport direction A of the transport means at the inspection position P on the transport means.

Description

Technical Field

[0001] The present invention relates to an appearance inspection system for six-sided electronic components such as chip capacitors and chip light-emitting diodes, and particularly to an appearance inspection system that can accurately inspect the end faces.

Background Art

[0002] Defects and peeling formed on the terminal electrodes of six-sided electronic components such as chip capacitors affect product quality as defects in the terminal electrodes. Therefore, an inspection device that can accurately inspect defects existing in the terminal electrodes is required. When inspecting the end faces of six-sided electronic components such as chip capacitors, the electronic components are conveyed in a predetermined conveyance direction by conveyance means, and at an inspection position set at a predetermined position during the conveyance, the end faces of the electronic components are illuminated by illumination means, and at the same time, the end faces of the electronic components are imaged from diagonally forward by imaging means. On the other hand, in recent years, miniaturization of electronic components has advanced, and in order to cope with miniaturization, it has been required to appropriately arrange the imaging camera and the illumination device in order to accurately image the end face properties.

[0003] Patent Documents 1 to 3 disclose an inspection device provided with an illumination mechanism for illuminating an inspection surface of an inspection object (electronic component) at an inspection position determined on a conveyance path, and the illumination mechanism arranges a light emitter close to the conveyance path in a state where it is closer to the conveyance path than another group of light emitters and separated from the inspection position, so as to provide a space for imaging the inspection surface of the inspection object between the light emitter close to the conveyance path and the other group of light emitters, and arranges the imaging camera so that the angle (elevation angle) formed by the conveyance direction and the imaging optical axis of the imaging camera is minimized as much as possible. However, Patent Documents 1 to 3 disclose that peeling of the terminal electrodes of electronic components is determined by a decrease in the amount of reflected light, and do not disclose selectively determining peeling of the terminal electrodes of electronic components by selecting the wavelength of illumination light. Patent documents 4 to 5 disclose an inspection device that includes an illumination mechanism for illuminating the inspection surface of an object to be inspected (electronic component) at an inspection position determined on a transport path, the illumination mechanism comprising a blue illumination means for emitting blue light and a red illumination means for emitting red light, and an image acquisition unit comprising a color image acquisition unit for acquiring a color image of the object to be inspected that is illuminated by two types of illumination means of different colors, and the blue illumination means and red illumination means are arranged such that the inspection light from the blue illumination means illuminates the external surface of the object to be inspected and the inspection light from the red illumination means penetrates into the interior of the object to be inspected. However, Patent Documents 4 and 5 do not disclose a method for selectively determining terminal electrode peeling of electronic components by mixing blue and red illumination light. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-160016 [Patent Document 2] Japanese Patent Publication No. 2020-115110 [Patent Document 3] Japanese Patent Publication No. 2021-156808 [Patent Document 4] Japanese Patent Publication No. 2007-64801 [Patent Document 5] Japanese Patent Publication No. 2009-36710 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention provides a visual inspection system that can accurately detect defects, particularly peeling of the terminal electrode W1, in a chip-type capacitor (hexahedral electronic component, hereinafter referred to as "object to be inspected W") in which a terminal electrode W1 is formed at the end of an internal electrode W2 as illustrated in Figure 1. [Means for solving the problem]

[0006] The problem of the present invention can be solved by the following embodiments (1) to (6). Specifically,

[0007] (Aspect 1) An appearance inspection system comprising: an inspection unit equipped with illumination means for illuminating an object to be inspected, transport means for transporting the object to be inspected, and imaging means; an image acquisition unit that uses an image signal from the object to be inspected acquired by the imaging means as an inspection image; an image processing unit that processes the inspection image created by the image acquisition unit; a determination unit that determines the inspection image processed by the image processing unit; an inspection control unit equipped with a system control unit that controls the illumination means, the transport means, and the imaging means; and a communication means that connects the inspection unit and the inspection control unit, wherein the illumination means consists of an upper illumination device and a lower illumination device arranged opposite to the upper and lower sides of the transport means, the upper illumination device has an opening for imaging the object to be inspected, and both the upper illumination device and the lower illumination device each include a first light source group arranged perpendicular to the transport direction of the transport means, a second light source group arranged inclined with respect to the transport direction of the transport means, and a third light source group arranged horizontally with respect to the transport direction of the transport means, The light source arrangements of the first and second light source groups are configured in a staggered pattern of red and blue light sources, and the light source arrangement of the third light source group is configured in a pattern of only green light sources. The imaging means is an appearance inspection system characterized by positioning the imaging optical axis X at a predetermined elevation angle (θ) with respect to the transport direction of the transport means at the inspection position P on the transport means. By employing polygonal (for example, hexagonal) dome lighting, it is possible to have a first group of light sources arranged perpendicular to the transport direction, a second group of light sources arranged at an angle to the transport direction of the transport means, and a third group of light sources arranged horizontally to the transport direction of the transport means. This allows for uniform direct illumination of the front, back, oblique sides, and end faces of the object to be inspected, enabling accurate detection of peeling and defects in the object. The first and second light source groups, which serve as end-face illumination illuminating the sides and end faces of the object to be inspected, are arranged in a staggered pattern of red and blue illumination. By illuminating the object to be inspected with red and blue illumination from the same direction, it is possible to accurately detect the exposure of copper-colored (red-colored metal) internal electrodes due to the peeling of silver-colored (blue-colored metal) terminal electrodes during end-face inspection of the object to be inspected.

[0009] (Pattern 2 ) Characterized by the elevation angle (θ) being 5 to 60°. Appearance 1 This is the visual inspection system described below. This is because setting the elevation angle (θ) to 5-60°, more preferably 15-45°, allows for accurate detection of detachment of the terminal electrode W1. [Effects of the Invention]

[0010] According to the present invention, a polygonal (for example, hexagonal) dome illumination system is employed that can irradiate illumination light to the front, back, oblique sides, and end faces of the object to be inspected. Furthermore, a substrate-mounted high-brightness LED with a wide beam angle while maintaining high brightness is used as the illumination light source for the dome illumination system. This allows for uniform illumination light to be irradiated to the front, back, sides, and end faces of the object to be inspected, enabling accurate detection of peeling and defects in the object. The first and second light source groups, which serve as end-face illumination illuminating the sides and end faces of the object to be inspected, are arranged in a staggered pattern of red and blue illumination. By illuminating the object to be inspected with red and blue illumination from the same direction, the exposure of copper-colored (red-colored metal) internal electrodes due to peeling of silver-colored (blue-colored metal) terminal electrodes can be accurately detected during end-face inspection of the object to be inspected. Furthermore, by using green illumination light for the third light source group that illuminates both the front and back surfaces of the object being inspected, it is possible to accurately detect shape defects in the object without interference from the red and blue illumination lights. [Brief explanation of the drawing]

[0011] [Figure 1] This is an illustrative diagram of a hexahedral electronic component that is the object to be inspected in the visual inspection system of the present invention. [Figure 2] This diagram illustrates the configuration of the visual inspection system of the present invention. [Figure 3] This is a side view showing an embodiment of the inspection unit that constitutes the visual inspection system of the present invention. [Figure 4] This is a front view showing an embodiment of the inspection unit that constitutes the visual inspection system of the present invention. [Figure 5] This is a diagram showing the arrangement of light sources for the lighting device that constitutes the lighting means of the visual inspection system of the present invention. [Figure 6] This is an explanatory diagram of the mechanism for determining terminal detachment using the visual inspection system of the present invention.

Embodiments for Carrying out the Invention

[0012] Embodiments for carrying out the present invention will be described based on FIGS. 1 to 6. However, FIGS. 1 to 6 are merely examples of embodiments and are not limited thereto.

[0013] 1. Configuration of Appearance Inspection System FIG. 2 is a configuration diagram illustrating the configuration of an appearance inspection system 300 of the present invention. An inspection object W is placed on a rotating means 3 on a conveying means 1 and transferred in a conveying direction A, and an inspection image is acquired by an imaging means 2 at an inspection position P. The appearance inspection system 300 of the present invention is composed of an inspection unit 100, an inspection control unit 200, and a communication means 4 connecting the inspection unit 100 and the inspection control unit 200.

[0014] The inspection unit 100 includes illumination means (10, 20) for illuminating the inspection object W, a conveying means 1 for conveying the inspection object W, a rotating means 3 for placing the inspection object W on a rotation axis and rotating it, and an imaging means 2 disposed at an inspection position P on the conveying means 1 with an imaging optical axis X at a predetermined elevation angle (θ) with respect to the conveying direction A of the conveying means. The imaging means 2 images the inspection object W through an opening 15 provided in the upper surface illumination device 10. The illumination means (10, 20) is composed of an upper surface illumination device 10 and a lower surface illumination device 20 disposed opposite to each other above and below the conveying means 1. The upper surface illumination device 10 includes an opening 15 for imaging the inspection object W. Further, both the upper surface illumination device 10 and the lower surface illumination device 20 include a first light source group 11 disposed in a manner perpendicular to the conveying direction A of the conveying means 1, a second light source group 12 disposed in a manner inclined with respect to the conveying direction A of the conveying means 1, and a third light source group 13 disposed in a manner horizontal to the conveying direction A of the conveying means 1.

[0015] The inspection control unit 200 includes an image acquisition unit 31 that uses the image signal from the object to be inspected W acquired by the imaging means 2 as an inspection image, an image processing unit 32 that processes the inspection image acquired by the image acquisition unit 31, an information storage unit 33 that stores the processing program for executing the image processing and information necessary when the program is executed, a determination unit 34 that makes a determination on the inspection image processed by the image processing unit 32, and a system control unit 35 that controls the transport means 1, the imaging means 2, and the illumination means (10, 20).

[0016] The following will describe the inspection target W, inspection unit 100, inspection control unit 200, and communication means 4 in that order.

[0017] 2. Items to be inspected The object W to be inspected by the visual inspection system 300 of the present invention is not particularly limited as long as it is a hexahedron-shaped member that requires end-face inspection. Specifically, it is an electronic component such as a chip capacitor or a chip light-emitting diode. This is because chips and peeling formed on the electrode portion of the end face affect product quality as defects in the electrode portion, and therefore there is a need for an inspection device that can accurately inspect defects present on the electrode portion of the end face of an electronic component.

[0018] 3. Inspection Department Figure 3 is a side view showing an embodiment of an inspection unit 100 equipped with a transport means 1 for transporting an object to be inspected W, and Figure 4 is a front view showing the embodiment. The inspection unit 100 constituting the appearance system 300 of the present invention comprises illumination means (10, 20) for illuminating the object to be inspected W, transport means 1 for transporting the object to be inspected W, rotating means 3 for rotating the object to be inspected W on a rotating axis, and imaging means 2 positioned at an inspection position P on the transport means 1 with the imaging optical axis X at a predetermined elevation angle (θ) with respect to the transport direction A of the transport means.

[0019] (3-1) Lighting means The illumination means of the visual inspection system 300 of the present invention consists of an upper illumination device 10 and a lower illumination device 20 arranged opposite to the upper and lower sides of the transport means 1. Both the upper illumination device 10 and the lower illumination device 20 include a first light source group (11, 21) arranged perpendicular to the transport direction A of the transport means 1, a second light source group (12, 22) arranged inclined with respect to the transport direction A of the transport means 1, and a third light source group (13, 23) arranged horizontally with respect to the transport direction A of the transport means 1. The first light source group (11, 21), the second light source group (12, 22), and the third light source group (13, 23) are fixed to light source support parts (16, 26), respectively. The shape of the light source support section (16, 26) is polygonal (a hexagon when the upper and lower illumination devices are combined), and the light emitted from the first light source group (11, 21), the second light source group (12, 22), and the third light source group (13, 23) illuminates the end face of the object to be inspected W, the slope between the end face and the upper (lower) surface, and the illumination light perpendicular to the upper (lower) surface, respectively. As a result, uniform illumination light can be emitted to the end face, slope, and upper (lower) surface of the object to be inspected W, enabling accurate detection of peeling and defects in the object to be inspected W. The top illumination device 10 is equipped with an opening 15 for the imaging means 2 to acquire reflected light from the object to be inspected W.

[0020] (3-2) Light source arrangement Figure 5 is a diagram showing the arrangement of light sources for the lighting devices that constitute the lighting means (10, 20) of the inspection unit 100 of the visual inspection system 300 of the present invention, with (a) being a side view and (b) being a perspective view, respectively. The lighting device consists of a first light source group (11, 21) arranged perpendicular to the transport direction A of the transport means 1, a second light source group (12, 22) arranged at an angle to the transport direction A of the transport means 1, and a third light source group (13, 23) arranged horizontally to the transport direction A of the transport means 1. The first light source group (11, 21), the second light source group (12, 22), and the third light source group (13, 23) each consist of multiple LED light sources arranged at intervals of 1 to 10 mm in the X and Y directions. The LED light sources can be bullet-shaped or surface-mount type, but high-brightness surface-mount LEDs with a wide beam angle are preferred. The LED light sources are dimmable. For example, if metallic colors with different reflectivity are mixed, the amount of emitted light can be adjusted to perform inspections with precision.

[0021] The first light source group (11, 21) and the second light source group (12, 22) constituting the illumination means (10, 20) of the inspection unit 100 of the visual inspection system 300 of the present invention are configured in a staggered arrangement of red light sources (wavelength range 610 nm to 780 nm) and blue light sources (wavelength range 460 nm to 500 nm). By using a mixed color configuration of red light sources (Red) and blue light sources (Blue) arranged in a staggered pattern for the first and second light source groups that irradiate the terminal electrodes W1 of the object to be inspected W, the red light source (Red) and the blue light source (Blue) can be irradiated onto the object to be inspected W from the same direction, and the exposure of the copper-colored (red-colored metal) internal electrodes due to peeling of the silver-colored (blue-colored metal) terminal electrodes W1 of the object to be inspected can be detected with high accuracy. On the other hand, the third light source group (13, 23) consists only of green light sources (wavelength range of 500 nm to 570 nm). By using only green light sources, it is possible to accurately detect shape defects in the object being inspected without interference from red and blue illumination.

[0022] Figure 6 is an explanatory diagram illustrating how the visual inspection system 300 of the present invention can accurately determine whether the terminal electrode W1 of a chip-type capacitor has peeled off. Each of the figures illustrates the following examples: (a) a good product, (b) a defective product in which the internal electrode W2 (copper: red metal) is exposed due to the peeling of the terminal electrode W1, and (c) a good product in which only scratches are caused by deformation of the terminal electrode W1 (silver: blue metal), and the internal electrode W2 (copper: red metal) is not exposed. The images obtained by illuminating the terminal electrodes W1 of (a) good products, (b) defective products, and (c) good products with the first and second light source groups used in the visual inspection system 300 of the present invention, using illumination means (10, 20) in which red light sources (Red) and blue light sources (Blue) are arranged in a staggered pattern, are compared with images illuminated with white light (prior art). In the case of peeling of the terminal electrode W1 of a chip capacitor, since the terminal electrode W1 of the chip capacitor is made of silver (a blue metal), when the terminal electrode W1 peels off, the internal electrode W2 (copper (a red metal)) is exposed. Therefore, by irradiating the terminal electrode W1 with a mixed illumination of a red light source (Red) and a blue light source (Blue) on the same illumination axis, and acquiring images from the red light source (Red) and blue light source (Blue) with the imaging means 2, only those in which peeling of the terminal electrode W1 has occurred can be selectively detected as defective, and those in which the plating of the terminal electrode W1 does not peel off can be considered good products.

[0023] (3-3) Imaging methods The imaging means 2 of the visual inspection system 300 of the present invention is an image sensor using an integrated circuit (IC) that converts reflected light from the object to be inspected W at the inspection position P through the aperture 15 into an image signal. Specifically, a configuration in which a large number of photodiodes are arranged on a planar silicon substrate is used, and an integrated circuit such as a charge-coupled device (CCD) or complementary metal oxide semiconductor (CMOS) is used for data transfer. The system also consists of an optical system that forms an image of the object to be inspected W on the imaging surface of the solid-state image sensor, and a signal processing circuit that processes the output of the solid-state image sensor to obtain a brightness value for each pixel. A color area camera is preferred depending on the nature of the object to be inspected W. Furthermore, at the inspection position P, the elevation angle (θ) of the transport means for the imaging optical axis X with respect to the transport path is arranged to be in the range of 5 to 60°, more preferably 15 to 45°.

[0024] (3-4) Conveying means The transport means 1 of the visual inspection system 300 of the present invention comprises a disc-shaped rotating means 3 made of a transparent or translucent glass plate, and a drive mechanism (not shown) that rotates the rotating means 3 horizontally in the direction of arrow A. The system control unit 35 controls the rotating means 3 so that at the inspection position P, the terminal electrodes W1 of the object to be inspected W are oriented toward the imaging optical axis X of the imaging means 2.

[0025] 4. Inspection and Control Unit The inspection control unit 200 of the visual inspection system 300 of the present invention is responsible for controlling the entire visual inspection system 300 of the present invention. Specifically, it comprises an image acquisition unit 31 that acquires video signals from the imaging means 2 as images, an image processing unit 32 that processes the images acquired by the image acquisition unit 31 into inspection images, an information storage unit 33 that stores processing programs for executing image processing and information necessary when the program is executed, a determination unit 34 that determines whether or not there is peeling or damage to the terminal electrodes W1 of the object to be inspected W from the image-processed inspection image, and a system control unit 35 that controls the illumination means (10, 20), the imaging means 2, the transport means 1 and the rotating means 3. System control information is input from the input device 36, and the operating status of the visual inspection system 300 and the inspection results are output from the display device 37.

[0026] (4-1) Image acquisition unit The image acquisition unit 31 is responsible for acquiring the video signal obtained by the imaging means 2 from the terminal electrode W1 of the object to be inspected W as an image and transmitting it to the image processing unit 32. It also has the function of controlling the operation of the imaging means 2, such as the timing of imaging, via general-purpose communication interfaces such as Camera Link, USB (Universal Serial Bus), CXP (CoaXPress®), and Gigabit Ethernet (GigE).

[0027] (4-2) Image Processing The image processing unit 32 is responsible for performing various image processing operations on the image information from the image acquisition unit 31 to create an inspection image.

[0028] (4-3) Information storage section The information storage unit 33 includes ROM (Read Only Memory) and RAM (Random Access Memory). The ROM stores various programs, such as inspection method programs, executed by the CPU, and information necessary for the execution of these programs. The various programs and information stored in the ROM are loaded into the RAM and executed.

[0029] (4-4) Judgment section The determination unit 34 is responsible for determining whether or not there is any peeling or damage to the terminal electrode W1 of the object W being inspected.

[0030] (4-5) System Control Unit The system control unit 35 is responsible for controlling the lighting means (10, 20), the imaging means 2, the transport means 1, and the rotary table 3.

[0031] 5. Means of communication The communication means 4 of the present invention has the role of transmitting the image signal acquired by the inspection unit 100 to the image acquisition unit 31, and the role of transmitting information that the system control unit 35 uses to control the illumination means (10, 20), the imaging means 2, the transport means 1, and the rotary table 3 to the inspection unit 100. [Industrial applicability]

[0032] The present invention provides a method for inspecting the end faces of hexahedral electronic components. [Explanation of Symbols]

[0033] 100 Inspection Department 200 Inspection Control Unit 300 Visual Inspection System W is the object to be inspected, a chip-type capacitor. W1 is the terminal electrode, and W2 is the internal electrode. 1. Conveying means 2. Imaging means 3. Rotating means 4. Means of communication 10 Top illumination device 11,21 1st light source group 12,22 2nd light source group 13,23 Third light source group 14,24 terminals 15 Opening 16 Light source support part 31 Image acquisition unit 32 Image Processing Unit 33 Information storage section 34 Judgment section 35 System Control Unit 36 Input devices 37 Display device

Claims

1. An inspection unit comprising an illumination means for illuminating the object to be inspected, a transport means for transporting the object to be inspected, and an imaging means, An image acquisition unit that uses the image signal from the object to be inspected acquired by the imaging means as an inspection image, An inspection control unit comprising an image processing unit that processes the inspection image acquired by the image acquisition unit, a determination unit that determines the inspection image processed by the image processing unit, and a system control unit that controls the illumination means, the transport means, and the imaging means, A communication means connecting the inspection unit and the inspection control unit, An appearance inspection system comprising, The illumination means consists of an upper illumination device and a lower illumination device arranged opposite to the upper and lower surfaces of the transport means, the upper illumination device has an opening for imaging the object to be inspected, and both the upper illumination device and the lower illumination device each include a first light source group arranged perpendicular to the transport direction of the transport means, a second light source group arranged inclined with respect to the transport direction of the transport means, and a third light source group arranged horizontally with respect to the transport direction of the transport means. The light source arrangements of the first and second light source groups are configured in a staggered pattern of red and blue light sources, and the light source arrangement of the third light source group is configured in a pattern of only green light sources. The imaging means is positioned such that the imaging optical axis X is positioned at a predetermined elevation angle (θ) with respect to the transport direction of the transport means at the inspection position P on the transport means. A visual inspection system characterized by the following features.

2. The visual inspection system according to claim 1, characterized in that the elevation angle (θ) is 5 to 60°.

Images