Inspection Equipment

Abstract

To provide an imaging device that can obtain an image in which the oversight of a defect or the risk of misinformation can be suppressed regardless of a surface state of an imaging object.SOLUTION: An imaging device includes: an imaging unit 3 that obtains image data by imaging an imaging object 1; an illumination unit including a regular reflection white light source 4a that irradiates the imaging object 1, a regular reflection RGB light source that delivers RGB light to the imaging object 1, and a diffusion reflection RGB light source; a transport unit that transports the imaging object 1 or the imaging unit 3 and the illumination unit to change an imaging region of the imaging unit on the imaging object 1; an imaging control unit that controls the transport speed of the transport unit or the transport speed of the imaging unit 3 so that the imaging unit 3 can image more than once in a period for which a predetermined region of the imaging object, which is moved relative to the imaging unit 3 by the transport unit, is in the imaging region of the imaging unit; and an illumination control unit that controls the lighting timing of each light source of the illumination unit to be synchronized with the imaging timing of the imaging unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging device, which is an optical system used in a board appearance inspection device that mainly inspects defects in printed circuit boards and the like, and to an inspection device using the same. [Background technology]

[0002] Conventionally, various configurations have been known as imaging optical inspection devices that inspect the surface of an object for scratches, the presence of foreign matter, etc., based on an image obtained by imaging the object. The present applicant has already proposed an inspection device having a specific optical system as an imaging optical inspection device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5806808 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the imaging optical inspection device, it is possible to inspect mainly uneven defects using accumulated image data captured with white light, and to show defects in each primary color component of color printing using accumulated image data captured with each monochromatic light.

[0005] Generally, when inspecting a printed circuit board or the like for defects, a board that is judged as NG by a visual inspection device is then sent to a re-inspection process called a verify inspection, where a final OK / NG judgment is made. In a verify inspection, an inspector typically visually judges the defect using a color image (RGB image) that closely resembles what the human eye sees. Therefore, the present applicant has discovered a problem: for example, in areas where the reflective properties change depending on the surface condition, such as gold plating on an electrode, and the brightness of the color image changes, there is a risk of overlooking defects or false detection.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an imaging device that can obtain images that can reduce the risk of overlooking defects or false reports, regardless of the surface condition of the object being imaged. [Means for solving the problem]

[0007] The imaging device of the present invention comprises an imaging unit that images an object to be imaged and obtains image data; an illumination unit that includes a specular white light source that irradiates the object to be imaged with white light and where the light reflected from the object to be imaged enters the imaging unit as specularly reflected light; a specular RGB light source that irradiates the object to be imaged with each of RGB lights and where the light reflected from the object to be imaged enters the imaging unit as specularly reflected light; and a diffuse RGB light source that irradiates the object to be imaged with each of RGB lights and where the light reflected from the object to be imaged enters the imaging unit as diffusely reflected light; a transport unit that transports the object to be imaged or the imaging unit and the illumination unit, and moves the positions of the object to be imaged and the imaging unit relatively to change the imaging area of ​​the imaging unit on the object to be imaged; an imaging control unit that controls the transport speed of the transport unit or the transfer speed of the imaging unit so that the imaging unit can capture multiple images within the time period when a predetermined area of ​​the object to be imaged, which is moved relative to the imaging unit by the transport unit, is within the imaging area of ​​the imaging unit; and an illumination control unit that controls the lighting timing of each light source of the illumination unit to synchronize with the imaging timing of the imaging unit. [Effects of the Invention]

[0008] The imaging device according to the present invention can obtain images that can reduce the risk of overlooking defects or false reports, regardless of the surface condition of the plating. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration of an imaging device according to a first embodiment. [Figure 2] 1 is a block diagram showing a configuration of an imaging device according to a first embodiment and a configuration of an inspection device including the imaging device. [Figure 3] 3 is a flowchart of an imaging method according to the first embodiment. [Figure 4]3A and 3B are schematic diagrams illustrating an image of the surface state of a substrate captured by the imaging device according to the first embodiment using an RGB light source and a white light source. DETAILED DESCRIPTION OF THE INVENTION

[0010] an illumination unit that includes: an imaging unit that images an object to be imaged and obtains image data; a specular white light source that is positioned so that white light is irradiated onto the object to be imaged and the light reflected from the object to be imaged enters the imaging unit as specularly reflected light; a specular RGB light source that is positioned so that RGB light is irradiated onto the object to be imaged and the light reflected from the object to be imaged enters the imaging unit as specularly reflected light; and a diffuse RGB light source that is positioned so that RGB light is irradiated onto the object to be imaged and the light reflected from the object to be imaged enters the imaging unit as diffusely reflected light; a transport unit that transports the object to be imaged or the imaging unit and the illumination unit, and moves the positions of the object to be imaged and the imaging unit relatively to change the imaging area of ​​the imaging unit on the object to be imaged; an imaging control unit that controls the transport speed of the transport unit or the transfer speed of the imaging unit so that the imaging unit can capture multiple images within the time period in which a predetermined area of ​​the object to be imaged, which is moved relative to the imaging unit by the transport unit, is within the imaging area of ​​the imaging unit; and an illumination control unit that controls the lighting timing of each light source of the illumination unit to synchronize with the imaging timing of the imaging unit.

[0011] The imaging device according to the second aspect may further include an image processing unit that generates specular white image data by accumulating image data obtained from a specular white light source and RGB image data by accumulating image data obtained from a specular RGB light source and a diffuse RGB light source, based on the image data obtained from the imaging unit according to the first aspect.

[0012] The imaging device according to the third aspect may be the same as that of the first or second aspect, in which the illumination control unit turns on the specular reflection RGB light source and the diffuse reflection RGB light source at the same time, and the image processing unit creates RGB image data by accumulating image data captured under simultaneous illumination from the specular reflection RGB light source and the diffuse reflection RGB light source.

[0013] The imaging device according to a fourth aspect is the imaging device according to any one of the first to third aspects, wherein the specular reflection white light source and the specular reflection RGB light source may be configured by a single lighting device.

[0014] An inspection device according to a fifth aspect includes an imaging device according to any one of the first to fourth aspects, and an inspection unit that inspects the surface condition of an object to be imaged based on specular reflection white image data obtained by the imaging device and RGB image data that is an accumulation of image data obtained by a specular reflection RGB light source and a diffuse reflection RGB light source.

[0015] An imaging device according to an embodiment and an inspection device using the imaging device will be described below with reference to the accompanying drawings, in which substantially identical components are designated by the same reference numerals.

[0016] (Embodiment 1) <Imaging device> Fig. 1 is a schematic diagram showing the configuration of an imaging device 10 according to embodiment 1. Fig. 2 is a block diagram showing the configuration of the imaging device 10 according to embodiment 1 and the configuration of an inspection device 20 including this imaging device 10. An imaging device 10 according to the first embodiment includes an imaging unit 3 that captures an image of an object 1, a transport unit 2 that transports the object 1, illumination units 4a-4g that illuminate the object 1, an imaging control unit 5, an illumination control unit 6, an image processing unit 7, and a synchronization signal generating unit 8. The illumination units 4a-4g include a specular reflection white light source 4a, specular reflection RGB light sources 4b, 4c, and 4d, and diffuse reflection RGB light sources 4e, 4f, and 4g. Here, the RGB light source is typically a combination of three light sources that emit monochromatic light of red (R), green (G), and blue (B), which are the three primary colors, and is a light source that can control the lighting of each light-emitting element of each RGB color. However, the present invention is not limited to this, and any light source that can realize similar lighting conditions may be used. The imaging device 10 includes RGB light sources 4b, 4c, and 4d (specular reflection RGB light sources) and 4e, 4f, and 4g (diffuse reflection RGB light sources). By combining these light sources, images can be obtained for both cases: when the plating surface is mirror-like and the specular reflection is strong; and when the surface is diffuse and the diffuse reflection is strong. Furthermore, uneven defects such as steps are difficult to detect in color images captured using RGB light sources, but are easier to detect in monochrome images captured using a white light source. Furthermore, even with a white light source, steps are almost impossible to detect using a diffuse reflection light source; they can only be detected using a specular reflection light source. The imaging device 10 includes a specular reflection white light source 4a, enabling highly accurate detection of uneven defects such as step differences in patterns and resists. It should be noted that the image processing unit 7 is not essential. The imaging control unit 5 may also function as a synchronization signal generating unit.

[0017] Each component constituting this imaging device 10 will be described below.

[0018] <Image object> The object to be imaged 1 is, for example, a printed circuit board, for example, a printed circuit board having plating such as gold plating on copper.

[0019] <Transportation section> The transport unit 2 may transport the object to be imaged 1 in one direction, for example. A transport stage using a general-purpose single-axis robot may be used as the transport unit 2. The transport unit 2 transports the object to be imaged 1, and moves the relative positions of the object to be imaged 1 and the imaging unit 3, thereby changing the imaging area of ​​the imaging unit 3 on the object to be imaged 1. In this imaging device 10, the transport unit 2 does not have to transport the object to be imaged. For example, the imaging unit and the illumination unit can be configured as an integrated imaging unit, which can be transported in one direction relative to the object to be imaged 1 by the transport unit 2 to capture an image of the entire object to be imaged. In this case, too, the positions of the object to be imaged 1 and the imaging unit 3 can be moved relatively to change the imaging area of ​​the imaging unit 3 on the object to be imaged 1.

[0020] <Image capture unit> The imaging unit 3 has an imaging element 3a such as a CCD or CMOS for capturing an image of the object to be imaged and obtaining image data. The imaging unit 3 may be either a line sensor or an area sensor. A line sensor may be used for high-speed scanning along the conveyance direction. The line sensor may be a single monochrome line sensor. In FIG. 1, the imaging unit 3 is positioned at a very high angle, at an angle of 83° from the horizontal plane and an angle of 7° from the normal, which is almost normal to the horizontal plane, but the invention is not limited to this. In FIG. 2, the lens 3b is shown separated from the imaging unit 3, but this is merely for convenience in order to show the imaging state in which the image is captured from approximately directly above. The lens 3b may be included in the imaging unit 3. Also, in FIG. 2, the imaging unit 3 and the subsequent image processing unit 7 and the like are shown as being separated from each other, which is called a head-separated type, but they may also be an integrated type. The subsequent imaging control unit 5, image processing unit 7 and the like may be integrated as a control unit. The image processing device may also include an output means for reducing the number of gradations of the image signal and outputting it to the outside.

[0021] <Lighting Department> The illumination units 4a to 4g include a specular reflection white light source 4a, specular reflection RGB light sources 4b, 4c, and 4d, and diffuse reflection RGB light sources 4e, 4f, and 4g. The specular reflection white light source 4a is disposed at a position where it irradiates the object 1 with white light and where the light reflected from the object 1 enters the imaging unit 3 as specular reflection light. The specular reflection RGB light sources 4b, 4c, and 4d are disposed at positions where it irradiates the object 1 with RGB light and where the light reflected from the object 1 enters the imaging unit 3 as specular reflection light. Therefore, the specular reflection RGB light sources 4b, 4c, and 4d are disposed so as to irradiate light from substantially the same direction as the specular reflection white light source 4a. Therefore, the specular reflection white light source 4a and the specular reflection RGB light sources 4b, 4c, and 4d may be configured as a single illumination device. The specular reflection RGB light sources 4b, 4c, and 4d each include a specular reflection R light source 4b, a specular reflection G light source 4c, and a specular reflection B light source 4d. The diffuse reflection RGB light sources 4e, 4f, and 4g are arranged at positions where they irradiate the object 1 with RGB light and the light reflected from the object 1 enters the imaging unit 3 as diffuse reflection light. The diffuse reflection RGB light sources 4e, 4f, and 4g consist of a diffuse reflection R light source 4e, a diffuse reflection G light source 4f, and a diffuse reflection B light source 4g. Therefore, the illumination units 4a to 4g have light sources for seven channels.

[0022] In addition, the specular reflection white light source 4a and the specular reflection RGB light sources 4b, 4c, and 4d are arranged at an angle of 83° from the horizontal plane and an angle of 7° from the normal, which is almost normal to the object, at a very high angle in Figure 1. The high angle arrangement makes the reflected light brighter than when it is arranged at a low angle, making it easier to detect defects. Note that the arrangement is not limited to this high angle. On the other hand, the diffuse reflection RGB light sources 4e, 4f, and 4g are arranged at an angle of 62° from the horizontal plane and an angle of 28° from the normal in Figure 1. Generally, diffuse reflection light sources are arranged at an angle of 45° from the horizontal plane and 45° from the normal. However, because the specular reflection light source is arranged at a high angle, the diffuse reflection light source is arranged at an angle slightly higher than the usual 45° to prevent the image produced by the diffuse reflection light source from being too dark compared to the light produced by the specular reflection. Note that the arrangement is not limited to this. The specular reflection RGB light sources 4b, 4c, and 4d are arranged such that the angle of incidence between the incident direction and the normal to the surface of the object 1 is smaller than the angle of incidence of the diffuse reflection RGB light sources 4e, 4f, and 4g, i.e., they are arranged at a higher angle. 1, the diffuse reflection RGB light sources 4e, 4f, and 4g are arranged on the opposite side to the specular reflection white light source 4a and the specular reflection RGB light sources 4b, 4c, and 4d, but this is not limitative and they may be arranged on the same side. In order to avoid physical collisions in FIG. 1, the specular reflection white light source 4a and the specular reflection RGB light sources 4b, 4c, and 4d are arranged on the opposite side from the diffuse reflection RGB light sources 4e, 4f, and 4g.

[0023] The illumination units 4a to 4g can illuminate the object 1 under different illumination conditions by appropriately switching among the seven channels. Alternatively, two or more of the seven channels may be turned on simultaneously for illumination. For example, the specular reflection RGB light sources 4b, 4c, and 4d and the diffuse reflection RGB light sources 4e, 4f, and 4g may be turned on at the same time for illumination. In this case, RGB image data can be acquired by accumulating image data from the specular reflection RGB light sources 4b, 4c, and 4d and the diffuse reflection RGB light sources 4e, 4f, and 4g. The illumination unit is not limited to the seven channels described above, and may be provided with more channels.

[0024] <Imaging control unit> The imaging control unit 5 controls the conveying speed of the conveying unit 2 or the transfer speed of the imaging unit 3 so that the imaging unit 3 can take multiple images within the time period when a specified area of ​​the object to be imaged 1 being conveyed by the conveying unit 2 is within the imaging area of ​​the imaging unit 3, i.e., so that multiple data transfers are possible from the imaging unit 3.

[0025] <Lighting control unit> The lighting control unit 6 controls the lighting timing of each of the light sources 4a-4g of the lighting unit to be synchronized with the imaging timing of the imaging unit 3, that is, to be synchronized with the data transfer. The lighting control unit 6 sequentially switches each of the light sources 4a-4g based on the synchronization signal. Note that control of the lighting conditions in switching imaging is not limited to sequentially switching between multiple lights, and for example, two or more lights may be combined and irradiated simultaneously, or one light may be irradiated multiple times while switching the wavelength or brightness. The illumination control unit 6 may be provided in either the imaging control unit 5 or the synchronization signal generating unit 8. Alternatively, it may share the same functions as these units. Alternatively, it may be provided as a separate unit.

[0026] <Synchronization signal generator> As described in JP 2012-42297 A, the synchronization signal generating means 8 sends a synchronization signal to the imaging unit 3 and the illumination control unit 6, and can drive them using a so-called switching imaging method, which synchronizes the switching of illumination conditions by each of the light sources 4a-4g with the timing of imaging. Furthermore, after imaging is completed, the switching to the next illumination condition is synchronized with the output of the image signal captured under the previous illumination condition. Therefore, the switching of each of the light sources 4a-4g is synchronized with the output corresponding to the previous illumination condition. The synchronization signal generating unit 8 may be provided in either the imaging control unit 5 or the illumination control unit 6. Alternatively, it may share the same functions as these units. Alternatively, it may be provided as a separate unit.

[0027] <Image processing unit> The image processing unit 7 generates specular reflection white image data by accumulating image data from the specular reflection white light source 4a based on the image data transferred from the imaging unit 3. It also generates RGB image data by accumulating image data from the specular reflection RGB light sources 4a, 4b, and 4c and the diffuse reflection RGB light sources 4e, 4f, and 4g.

[0028] <Image capture method> FIG. 3 shows the imaging device according to the first embodiment, max10 is a flowchart of an imaging method for obtaining image data in switching imaging in which imaging is performed by sequentially switching between illuminations. (1) As an initial setting, n=1 and m=1 are set (S01). (2) Imaging of the nth line begins (S02). (3) The mth light is turned on (S03). (4) Expose and capture an image to obtain an image signal (S04). (5) The mth light is turned off (S05). (6) An image signal corresponding to the m-th illumination is output (S06). (7) Lighting number m is m max (S07) max If so, reset the lighting number m to 1 (S08), and max If not, m is incremented (m=m+1) (S09), and the process returns to step S03. Note that resetting the lighting number m (S08) does not necessarily have to be performed at this stage. For example, the lighting number m may be reset at the same time as starting to capture the nth line (S02). (8) After resetting the lighting number m to 1, the line number n is n max (S10) max If the line number n is n max If not, n is incremented (n=n+1) (S11), and the process returns to step S02. Thus, m max In switching imaging, in which imaging is performed by sequentially switching between illuminations, image data corresponding to each illumination can be obtained.

[0029] <Inspection equipment> The inspection device 20 includes the imaging device 10 and an inspection unit 12. The inspection unit 12 inspects the surface condition of the imaged object 1 based on the specular reflection white image data obtained by the imaging device 10 and RGB image data obtained by accumulating image data from the specular reflection RGB light sources 4b, 4c, and 4d and the diffuse reflection RGB light sources 4e, 4f, and 4g. The inspection unit 12 may inspect the shape, pattern, color, etc. of the imaged object 1 using, for example, a pattern matching technique for the image data. Also, various image processing filters may be used to extract defects in the imaged object 1. Note that the combination of multiple images is not limited to the combination of all RGB images described above. For example, a combination of only R images or only G images may be used.

[0030] The inspection unit 12 inspects the object 1 based on the obtained image data. For example, there are roughly two types of defect inspection: one to detect defects that appear in a different color from a passing product (OK product), and one to detect uneven defects.

[0031] First, defects that cause color appearances different from those of acceptable products (OK products) include defects such as pad shape, scratches, foreign matter, and copper exposure on gold pads (gold chipping, revealing the underlying copper). These defects can be detected by inspecting color images under conditions equivalent to visual inspection. In the inspection system 20, color images are generated using image data from the specular reflection RGB light sources 4b, 4c, and 4d and image data from the diffuse reflection RGB light sources 4e, 4f, and 4g. When the surface of a plating, such as gold plating, is close to a mirror finish, specular reflection light is strong and diffuse reflection light is weak. In contrast, when the surface of a plating is diffuse, specular reflection light is weak and diffuse reflection light is strong. With the imaging device and inspection device according to the first embodiment, regardless of whether the plating surface is specular or diffuse, combining the image data from the specular reflection RGB light sources 4b, 4c, and 4d and the image data from the diffuse reflection RGB light sources 4e, 4f, and 4g produces an effect similar to dome lighting, which provides illumination from all directions, thereby producing a sufficiently bright color image. This reduces the risk of overlooking defects or false reports due to the surface condition of the plating, and improves the accuracy of defect detection.

[0032] The second type of unevenness defect includes pattern steps, PAD unevenness, foreign matter under the resist (steps caused by foreign matter), scratches, and foreign matter (unevenness caused by foreign matter). Note that a pattern step itself may not be a defect, but it may become a defect under certain conditions, such as the presence of foreign matter. These defects are difficult to see in color images, but can be detected by differences in the angle and reflectance of the unevenness if the image data is taken using a specular white light source. The imaging device and inspection device according to the first embodiment can detect unevenness defects using image data taken using the specular white light source 4a.

[0033] FIG. 4 is a schematic diagram showing an image of the surface state of a substrate captured by the imaging device according to the first embodiment using an RGB light source and an image using a white light source. In Figure 4, OSP stands for water-soluble pre-flux. In the color image, which was created by integrating image data from specular reflection RGB light sources 4b, 4c, and 4d and image data from diffuse reflection RGB light sources 4e, 4f, and 4g, the OSP appeared orange. The gold pads were also gold. The copper on the gold pads also had copper peeking through the gold. As shown in Figure 4, it can be seen that it is difficult to detect the step in the pattern, the unevenness of the gold pad, and the step on the resist in the color image. On the other hand, in the monochrome image taken with the specular white light source 4a, the OSP appears gray and the gold pad appears white. In contrast, the step in the pattern and the step on the resist appear somewhat dark, but the striped structure and island-like step with shading as shown in the schematic diagram can be seen. Furthermore, the copper on the gold pad appears black against the surrounding white. The unevenness of the gold pad also appears black against the surrounding white.

[0034] This imaging device and the inspection device equipped with it include a specular reflection white light source 4a, specular reflection RGB light sources 4b, 4c, and 4d, and diffuse reflection RGB light sources 4e, 4f, and 4g, which allows defects to be detected regardless of the surface condition of plating such as gold plating.

[0035] In addition, the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and can achieve the effects of each embodiment and / or example. [Industrial Applicability]

[0036] According to the imaging device and the inspection device using the imaging device of the present invention, defects can be detected regardless of the surface condition of the plating, such as gold plating, that is the object to be imaged. [Explanation of symbols]

[0037] 1 Imaged object 2. Conveyor section 3. Imaging unit 3a Image sensor 3b lens 4a Specular white light source 4b Specular reflection R light source 4c Specular reflection G light source 4d specular B light source 4e Diffuse reflection R light source 4f Diffuse Reflection G Light Source 4g Diffuse reflection B light source 5. Imaging control means 6. Lighting control means 7 Image processing section 8. Synchronization signal generating means 10. Imaging device 12 Inspection Department 20 Inspection equipment

Claims

1. an imaging unit that captures an image of a printed circuit board as an object to be imaged and obtains image data; an illumination unit including: a specular reflection white light source that irradiates the object to be imaged with white light and is positioned so that reflected light from the object to be imaged is incident on the imaging unit as specular reflection light; a specular reflection RGB light source that irradiates the object to be imaged with each of RGB lights and is positioned so that reflected light from the object to be imaged is incident on the imaging unit as specular reflection light; and a diffuse reflection RGB light source that irradiates the object to be imaged with each of RGB lights and is positioned so that reflected light from the object to be imaged is incident on the imaging unit as diffuse reflection light; a transport unit that transports the object to be imaged, or the imaging unit and the illumination unit, and moves the object to be imaged and the imaging unit relative to each other to change the imaging area of ​​the imaging unit on the object to be imaged; an imaging control unit that controls a conveying speed of the conveying unit or a transfer speed of the imaging unit so that the imaging unit can capture images multiple times within a time period in which a predetermined area of ​​the object to be imaged, which is moved relative to the imaging unit by the conveying unit, is within an imaging area of ​​the imaging unit; an illumination control unit that controls the lighting timing of each of the light sources of the illumination unit to be synchronized with the image capturing timing of the image capturing unit; an image processing unit that generates specular reflection white image data by accumulating image data obtained by the specular reflection white light source and RGB image data by accumulating image data obtained by the specular reflection RGB light source and the diffuse reflection RGB light source based on the image data obtained by the imaging unit; an imaging device comprising: an inspection unit that detects, based on the RGB image data, any of the gold pad color, pad shape, scratches, foreign matter, or copper appearance on the gold pad, which are defects in the plating portion of the printed circuit board that appear in a different color from that of an acceptable product, and detects uneven defects of the printed circuit board that is the object to be imaged, based on the specular reflection white image data; An inspection device comprising:

2. the illumination control unit turns on the specular reflection RGB light source and the diffuse reflection RGB light source at the same timing; 2. The inspection device according to claim 1, wherein the image processing unit creates RGB image data by accumulating image data captured under conditions where the specular reflection RGB light source and the diffuse reflection RGB light source are simultaneously irradiated.

3. 3. The inspection device according to claim 1, wherein the specular reflection white light source and the specular reflection RGB light source are configured as a single illumination device.

Images