JP6570211B1 - Appearance inspection device - Google Patents

Abstract

In an appearance inspection apparatus capable of simultaneously inspecting defects exposed on the surface and inside of an inspection object, it is possible to recognize more defects while suppressing an increase in the size of the apparatus configuration. An appearance inspection apparatus 10 emits red light, green light, and blue light having the same linear polarization characteristics to an inspection object W at different angles, respectively, and predetermined reflected light 30. A polarized beam splitter 13 that separates reflected light 31 having linear polarization characteristics and reflected light 32 from which a predetermined linear polarization characteristic has been removed; a color camera 15 that photographs parallel reflected lights 31 and 32 simultaneously; And an image processing device 16 that extracts red, green, and blue components from the image. Thereby, it becomes possible to expose more defects by optimizing the irradiation angle of each illumination according to the inspection object. Moreover, since the reflected lights 31 and 32 are incident on the same color camera 15, an increase in the size of the apparatus configuration can be suppressed. [Selection] Figure 1

Description

  The present invention relates to an appearance inspection apparatus, and more particularly to an appearance inspection apparatus capable of simultaneously inspecting both a defect exposed on the surface of an inspection object and a defect existing inside the inspection object.

  As an appearance inspection apparatus that performs an appearance inspection of an inspection object such as a chip part, the appearance inspection apparatuses described in Patent Documents 1 and 2 are known. In the appearance inspection apparatus described in Patent Documents 1 and 2, the angle formed between the illumination axis of red light and the optical axis is set large, while the angle formed between the illumination axis of blue light and the optical axis is decreased. Realizes dark field optical system and bright field optical system. In dark field optics, since reflection (specular reflection) from the surface of the inspection object does not enter the camera, only reflection (diffuse reflection) of light that enters the inspection object enters the camera. On the other hand, in the bright field optical system, both specular reflection and diffuse reflection are incident on the camera. However, since the reflectivity of the specular reflection is high, reflection from the target surface is dominant in the obtained image. As described above, in the visual inspection apparatus described in Patent Documents 1 and 2, visualization of internal defects and surface defects of the inspection target is realized by fixing the illumination irradiation angle to a predetermined angle in advance.

  However, in the appearance inspection apparatus described in Patent Documents 1 and 2, since the illumination irradiation angle is fixed at a predetermined angle in advance, there is a problem that a defect that does not manifest at the irradiation angle cannot be found. there were.

  On the other hand, in Patent Documents 3 to 5, the reflected light from the inspection object is separated into an S-polarized wave and a P-polarized wave using a polarization beam splitter, and an image composed of an S-polarized wave and an image composed of a P-polarized wave are respectively provided. A method for photographing with different cameras is disclosed. According to this method, it is possible to recognize both a defect existing on the surface of the inspection object and a defect existing inside without using illumination of a plurality of wavelengths.

Japanese Patent No. 4713279 Japanese Patent No. 4493048 JP-A-10-227623 Japanese Patent No. 3358099 Japanese Patent No. 4,716,827

  However, even in the appearance inspection apparatuses described in Patent Documents 3 to 5, it is difficult to find a defect that does not become apparent at the irradiation angle. Moreover, since two cameras, a camera that receives an S-polarized wave and a camera that receives a P-polarized wave, are required, there is also a problem that the apparatus configuration is increased in size.

  Therefore, the present invention provides a visual inspection apparatus capable of simultaneously inspecting both a defect exposed on the surface of an inspection object and a defect existing inside the inspection object, while suppressing an increase in the size of the apparatus and increasing the number of the apparatus. The purpose is to make the defect recognizable.

  An appearance inspection apparatus according to the present invention irradiates an inspection object at a first angle with a stage on which the inspection object is placed and a first polarized light having a first wavelength and a predetermined linear polarization characteristic. A first illumination and a second polarized light having a second wavelength different from the first wavelength and having the same linear polarization characteristic as the predetermined linear polarization characteristic at a second angle different from the first angle The second illumination that irradiates the inspection object, the reflected light from the inspection object, the first reflected light having a predetermined linear polarization characteristic and the second reflected light from which the predetermined linear polarization characteristic is removed The first polarizing beam splitter to be separated, the first mirror that makes the optical axis of the first reflected light and the optical axis of the second reflected light parallel, and the parallel first and second reflected lights are simultaneously received. , A first color that generates a first image based on the first reflected light and a second image based on the second reflected light. A camera, and an image processing device that extracts the first wavelength component and the second wavelength component from the first image, and extracts the first wavelength component and the second wavelength component from the second image. It is characterized by.

  According to the present invention, since a plurality of illuminations having different wavelengths and irradiation angles are used and separated into two reflected lights having different linear polarization characteristics for each wavelength, irradiation of each illumination is performed according to the inspection object. By optimizing the angle, more defects can be revealed. In addition, since the two reflected lights separated by the polarization beam splitter are collimated by the mirror and incident on the same color camera, it is possible to suppress an increase in the size of the apparatus configuration.

FIG. 1 is a schematic diagram for explaining the configuration of an appearance inspection apparatus 10 according to the first embodiment of the present invention. FIG. 2 is a schematic diagram showing an example in which the ND filter 42 and the glass plate 41 are arranged on the optical paths of the reflected lights 31 and 32, respectively. FIG. 3 is an image obtained by extracting red light from the reflected lights 31 and 32, where the left side is an image based on the reflected light 31 and the right side is an image based on the reflected light 32. FIG. 4 is an image obtained by extracting green light from the reflected light 31 and 32, where the left side is an image based on the reflected light 31 and the right side is an image based on the reflected light 32. FIG. 5 is an image obtained by extracting blue light from the reflected light 31 and 32, where the left side is an image based on the reflected light 31 and the right side is an image based on the reflected light 32. FIG. 6 is a schematic diagram for explaining the configuration of an appearance inspection apparatus 20 according to the second embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a schematic diagram for explaining the configuration of an appearance inspection apparatus 10 according to the first embodiment of the present invention.

  As shown in FIG. 1, the appearance inspection apparatus 10 according to the first embodiment includes a transparent stage S on which an inspection object (work) W is placed, and illuminations 11R and 11G that irradiate the inspection object W with light. , 11B, 11RGB. The type of the inspection object W is not particularly limited, but can be a small chip component such as a multilayer ceramic capacitor. A small chip component such as a multilayer ceramic capacitor may have a defect on its surface and may have a defect inside (surface layer portion). The appearance inspection apparatus 10 according to the present embodiment is an inspection object W. It is possible to simultaneously inspect both the defects exposed on the surface of the wafer and the defects existing inside the inspection object W.

  The illuminations 11R, 11G, and 11B irradiate the inspection object W with light having different wavelengths and irradiation angles. Here, the illumination 11R emits red light, the illumination 11G emits green light, and the illumination 11B emits blue light. The illumination 11RGB is auxiliary illumination for supplementing brightness by irradiating white light in which red light, green light, and blue light are mixed. Here, the reason why the inspection object W is irradiated with three types of light having different irradiation angles is that the types of defects that are manifested differ depending on the irradiation angle. For example, when the inspection object W is a multilayer ceramic capacitor, the illumination 11R is used for inspection of scratches, dirt and foreign matter on the surface of the ceramic portion, dirt and foreign matter inside the ceramic portion, and the size and shape of the terminal electrode portion. Is suitable. Further, the illumination 11G is suitable for inspection of a chip on the ridge line of the ceramic portion. Furthermore, the illumination 11B is suitable for inspection of metal foreign matter on the surface of the ceramic part, chipping on the ridge line of the ceramic part, and cracks inside the ceramic part. It is possible to obtain three types of images with different irradiation angles by one imaging by imaging with a color camera after dividing the wavelength of each illumination light.

  Here, the contrast of the defect that is manifested by each illumination greatly changes depending on the irradiation angle. For example, a defect that is manifested by the illumination 11R is enhanced in contrast by irradiating irradiation light as parallel as possible to the optical axis. In consideration of this point, in the present embodiment, the illumination angle of the illumination 11R is inclined by 90 ° with respect to the optical axis, and the half mirror 12 is used to guide it coaxially with the optical axis. On the other hand, the defect which becomes obvious by the illumination 11B is enhanced in contrast by irradiating the irradiation light with a certain angle with respect to the optical axis. Considering this point, in the present embodiment, the irradiation angle of the illumination 11B is inclined to a predetermined angle with respect to the optical axis. Further, the contrast that is manifested by the illumination 11G is enhanced by irradiating the defect from the back side of the inspection object W. Considering this point, in this embodiment, the illumination 11G is irradiated from the back surface S2 side of the stage S. On the other hand, the illuminations 11R and 11B are arranged on the placement surface S1 side of the stage S on which the inspection object W is placed.

  Thus, the visual inspection apparatus 10 according to the present embodiment irradiates the inspection object W with light having different wavelengths from each other at different angles. Further, the irradiation angles of the respective lights 11R, 11G, and 11B are not fixed and can be appropriately adjusted so that the highest contrast can be obtained.

  Each illumination 11R, 11G, and 11B includes a polarization filter (not shown), and the light emitted from each illumination 11R, 11G, and 11B is aligned with the same linear polarization characteristic. For example, the light emitted from each of the illuminations 11R, 11G, and 11B may be S-polarized waves. In this case, since the light irradiated to the inspection target W is an S-polarized wave for each wavelength component, the specular reflection light from the inspection target W is also an S-polarized wave. On the other hand, the diffuse reflected light obtained by diffusing the irradiated light to the surface layer of the inspection object W loses its polarization characteristics and becomes a non-polarized wave. Therefore, the reflected light 30 passing through the half mirror 12 contains S-polarized waves due to specular reflection and non-polarized waves due to diffuse reflection.

  The reflected light 30 is incident on the polarizing beam splitter 13 and is separated into a first reflected light 31 and a second reflected light 32 by the polarizing beam splitter 13. The first reflected light 31 is light including linearly polarized components of light emitted from each of the illuminations 11R, 11G, and 11B, and the reflected light 30 may be allowed to pass through as it is. The light may be light that has passed through a polarizing filter that selectively passes the light. That is, when the light emitted from each of the illuminations 11R, 11G, and 11B is an S-polarized wave, the first reflected light 31 is light including the S-polarized wave. Therefore, the main component of the first reflected light 31 is specular reflected light from the inspection object W.

  On the other hand, the second reflected light 32 is light from which the linearly polarized light components emitted from the respective illuminations 11R, 11G, and 11B are removed, and passes through a polarizing filter that selectively cuts the linearly polarized light components. Light. For example, when the light emitted from each of the illuminations 11R, 11G, and 11B is an S-polarized wave, the S-polarized wave is removed using a polarizing filter that selectively allows the P-polarized wave to pass through. Therefore, the main component of the second reflected light 32 is diffusely reflected light from the inspection object W. However, it is not essential to completely remove the S-polarized wave from the second reflected light 32, and it is sufficient that at least a part is removed.

  The second reflected light 32 enters the prism 14, the traveling direction is bent by 90 ° by the mirror 14 m included in the prism 14, and the second reflected light 32 is parallel to the first reflected light 31. The parallel first and second reflected lights 31 and 32 are incident on the color camera 15. Thereby, an image based on the first reflected light 31 and an image based on the second reflected light 32 can be obtained simultaneously. The image obtained by the color camera 15 is supplied to the image processing device 16.

  Here, as shown in FIG. 2, on the optical path of the second reflected light 32, a glass plate 41 that matches the optical path length of the first reflected light 31 with the optical path length of the second reflected light 32 is arranged. It is preferable. In this way, if the optical path length of the first reflected light 31 and the optical path length of the second reflected light 32 are matched using the glass plate 41, the color camera 15 can detect the image formed by the first reflected light 31 and the first reflected light. Thus, it is possible to correctly focus on both of the two images of the reflected light 32. As shown in FIG. 2, an ND filter 42 that reduces the amount of the first reflected light 31 is preferably disposed on the optical path of the first reflected light 31. Thus, if the light quantity of the 1st reflected light 31 is reduced using the ND filter 42, it is possible to reduce the difference between the light quantity of the first reflected light 31 and the light quantity of the second reflected light 32. Become.

  The image processing device 16 generates three images by extracting the wavelength components of the illuminations 11R, 11G, and 11B from the image obtained by the color camera 15. That is, an image obtained by extracting red light from the reflected lights 31 and 32, an image obtained by extracting green light from the reflected lights 31 and 32, and an image obtained by extracting blue light from the reflected lights 31 and 32 are obtained. Each image can be confirmed by the operator via the monitor 17.

  3 to 5 are images obtained by extracting red light, green light, and blue light from the reflected lights 31 and 32, respectively. The left side is an image based on the reflected light 31, and the right side is an image based on the reflected light 32. FIG. As shown in FIGS. 3 to 5, the appearance inspection apparatus 10 according to the present embodiment can simultaneously acquire six images from one inspection object W. That is, the six images are an image obtained by specular reflection of red light, green light, and blue light, and an image obtained by diffuse reflection of red light, green light, and blue light. As shown in FIGS. 3 to 5, the surface of the inspection object W and the state of the ridge line can be grasped from the image obtained by specular reflection, and the inside of the inspection object W can be determined from the image obtained by diffuse reflection It can be seen that the state of the ridgeline can be grasped.

  As described above, according to the appearance inspection apparatus 10 according to the present embodiment, six images can be simultaneously acquired from one inspection object W. Moreover, since the irradiation angles of the respective illuminations 11R, 11G, and 11B can be arbitrarily changed so that the contrast becomes the highest, it becomes possible to reveal more defects. In addition, since the two reflected lights 31 and 32 separated by the polarization beam splitter 13 are collimated and enter the same color camera 15, it is possible to suppress an increase in the size of the apparatus configuration.

<Second Embodiment>
FIG. 6 is a schematic diagram for explaining the configuration of an appearance inspection apparatus 20 according to the second embodiment of the present invention.

  As shown in FIG. 6, the visual inspection apparatus 20 according to the second embodiment uses two color cameras 26U and 26L to inspect an inspection object (workpiece placed on the placement surface S1 of the transparent stage S. ) W is taken simultaneously from above and below. Illuminations 21R, 21B, 21RGB, a half mirror 23U, a polarizing beam splitter 24U, a prism 25U, and a color camera 26U are arranged on the stage S placement surface S1, and illuminations 22R, 22G are arranged on the back surface S2 side of the stage S. 22RGB, a half mirror 23L, a polarizing beam splitter 24L, a prism 25L, and a color camera 26L. Here, since the stage S is transparent, the inspection object W is also irradiated with light from the illuminations 22R and 22G arranged on the back surface S2 side.

  The illuminations 21R and 21B irradiate red light and blue light, respectively, and both illuminate from the front, rear, left, and right directions of the inspection object W. Here, since the illumination 21R and the illumination 21B have different positions from the stage S, the irradiation angle of the red light by the illumination 21R and the irradiation angle of the blue light by the illumination 21B are different from each other. In the example shown in FIG. 6, the illumination 21R constitutes a high angle illumination, and the illumination 21B constitutes a low angle illumination. The illumination 21RGB is auxiliary illumination for supplementing brightness by irradiating white light in which red light, green light, and blue light are mixed, and is irradiated coaxially with the optical axis of the color camera 26U by the half mirror 23U.

  The illuminations 22R and 22G irradiate red light and green light, respectively, and both illuminate from the front, rear, left and right directions of the inspection object W. Here, since the positions of the illumination 22R and the illumination 22G from the stage S are different from each other, the irradiation angle of the red light by the illumination 22R and the irradiation angle of the green light by the illumination 22G are different from each other. In the example shown in FIG. 6, the illumination 22R constitutes a high angle illumination, and the illumination 22G constitutes a low angle illumination. The illumination 22RGB is auxiliary illumination for supplementing brightness by irradiating white light in which red light, green light, and blue light are mixed, and is irradiated coaxially with the optical axis of the color camera 26L by the half mirror 23L.

  As in the first embodiment, each of the illuminations 21R, 21B, 22R, and 22G includes a polarization filter (not shown), and light emitted from each of the illuminations 21R, 21B, 22R, and 22G has the same linear polarization characteristics (for example, S-polarized wave). The polarization beam splitters 24U and 24L are irradiated with light including linearly polarized components of light emitted from the respective illuminations 21R, 21B, 22R, and 22G, that is, specular reflection light, and illuminations 21R, 21B, 22R, and 22G. The light is separated into light from which the linearly polarized light component is removed, that is, diffusely reflected light. The specular reflection light and the diffuse reflection light are collimated by the mirrors 25Um and 25Lm included in the prisms 25U and 25L, and enter the color cameras 26U and 26L.

  With this configuration, the color camera 26U can photograph the inspection object W from the upper surface side, and the color camera 26L can photograph the inspection object W from the lower surface side. Then, the image processing device 27 extracts a red component, a green component, and a blue component from the images obtained by the color cameras 26U and 26L, so that a total of twelve images composed of an image by specular reflection light or an image by diffuse reflection light are obtained. Generate an image. Each image can be confirmed by the operator via the monitor 28.

  As described above, according to the appearance inspection apparatus 20 according to the present embodiment, in addition to the effects of the appearance inspection apparatus 10 according to the first embodiment, the inspection is performed by simultaneously photographing from one upper and lower sides from one inspection object W. It becomes possible to inspect the entire object W at a time.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, in each of the above embodiments, the inspection object W is irradiated with light of three colors consisting of red light, green light, and blue light, but it is not essential to use light of three colors in the present invention. Depending on the type of inspection object W and the type of defect to be detected, light of two colors or four or more colors may be used.

10, 20 Appearance inspection apparatus 11R, 11G, 11B, 11RGB, 21R, 21B, 21RGB, 22R, 22G, 22RGB Illumination 12, 23L, 23U Half mirrors 13, 24L, 24U Polarizing beam splitters 14, 25L, 25U Prisms 14m, 25Lm , 25 Um Mirror 15, 26 U, 26 L Color camera 16, 27 Image processing device 17, 28 Monitor 30 to 32 Reflected light 41 Glass plate 42 ND filter S Stage S 1 Mounting surface S 2

Claims (6)

A stage on which the inspection object is placed;
A first illumination having a first wavelength and irradiating the inspection object with a first polarized light having a predetermined linear polarization characteristic at a first angle;
The second object having a second wavelength different from the first wavelength and having the same linear polarization characteristic as the predetermined linear polarization characteristic is applied to the inspection object at a second angle different from the first angle. A second illumination for illuminating the object;
A first polarization beam splitter that receives the reflected light from the inspection object and separates the first reflected light having the predetermined linear polarization characteristic and the second reflected light from which the predetermined linear polarization characteristic has been removed. When,
A first mirror that parallels the optical axis of the first reflected light and the optical axis of the second reflected light;
A first color camera which receives the first and second reflected lights in parallel and generates a first image based on the first reflected light and a second image based on the second reflected light; ,
An image processing apparatus for extracting the first wavelength component and the second wavelength component from the first image, and extracting the first wavelength component and the second wavelength component from the second image; A visual inspection apparatus comprising: A third polarized light having a third wavelength different from the first and second wavelengths and having the same linear polarization characteristic as the predetermined linear polarization characteristic is different from the first and second angles. A third illumination that irradiates the inspection object at an angle of
The image processing apparatus further extracts the third wavelength component from the first image and further extracts the third wavelength component from the second image. Visual inspection equipment.   The glass plate further comprising a glass plate disposed on an optical path of the first or second reflected light and configured to match an optical path length of the first reflected light with an optical path length of the second reflected light. 3. An appearance inspection apparatus according to 1 or 2.   The appearance inspection apparatus according to claim 1, further comprising an ND filter disposed on an optical path of the first or second reflected light. The stage is transparent,
The first illumination is located on a placement surface side on which the inspection object is placed on the surface of the stage,
5. The appearance inspection apparatus according to claim 1, wherein the second illumination is located on a back surface side opposite to the placement surface of the surface of the stage. Second polarized light that receives another reflected light from the inspection object and separates into third reflected light having the predetermined linear polarization characteristic and fourth reflected light from which the predetermined linear polarization characteristic has been removed. A beam splitter,
A second mirror that parallels the optical axis of the third reflected light and the optical axis of the fourth reflected light;
A second color camera that receives the third and fourth reflected lights in parallel and obtains a third image based on the third reflected light and a fourth image based on the fourth reflected light; Further comprising
The image processing apparatus extracts the first wavelength component and the second wavelength component from the third image, and extracts the first wavelength component and the second wavelength component from the fourth image. Extract and
The first polarizing beam splitter and the first color camera are provided on the placement surface side of the stage,
The visual inspection apparatus according to claim 5, wherein the second polarizing beam splitter and the second color camera are provided on the back surface side of the stage.