JP2014009969A - Image processing device, image processing method, and exposure pattern inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device for imaging a surface of a photosensitive material to highly sensitively inspect a state of a surface of a photosensitive material by image processing.SOLUTION: An exposure pattern inspection device 100 includes: an imaging control section 10 for controlling an imaging unit 3 imaging a surface of a photo-resist on a print circuit board PS to be transported in a predetermined direction; an illumination control section 11 for controlling an illumination unit 4 illuminating a surface; and an image processing section 12 for processing an image to be output by the imaging unit 3. The image processing unit 12 elicits a difference between a first image G1 that is output after imaging a predetermined area of a surface of a photo-resist by the imaging unit 3 when the illumination unit 4 illuminates the surface with a first illumination light including light with a first wavelength and a second image G2 that is output after imaging a predetermined area by the imaging unit 3 when the illumination unit 4 illuminates a surface with a second illumination light including light with a second wavelength shorter than that of the first wavelength.

Description

  The present invention relates to an image processing apparatus, an image processing method, and an exposure pattern inspection apparatus that process an image obtained by illuminating the surface of a photosensitive material with light.

  Conventionally, a method for optically inspecting a photosensitive portion of a resist layer after exposure of the resist layer of the substrate or after development of the exposed resist layer is known (see, for example, Patent Document 1).

  This method irradiates the resist layer with visible light having a wavelength of 522 to 645 nm that does not reflect on the exposed portion of the resist layer after exposure but reflects on other portions and does not affect the unexposed portion. Take an image with a line camera. As a result, the boundary between the exposed portion and the unexposed portion can be detected more clearly.

  In addition, the surface of the object is imaged with a line camera while alternately illuminating an object conveyed in a predetermined direction with an illuminating device installed upstream in the conveying direction and an illuminating device installed downstream in the conveying direction. An image processing method for processing an obtained image is known (for example, see Patent Document 2).

  This method makes use of the difference in the appearance of concave defects, convex defects, and flat stains on the surface of the object caused by irradiating light toward the object from different directions. And flat dirt can be distinguished from each other.

JP 2004-347913 A JP 2006-329919 A

  However, the method of Patent Document 1 discloses that one type of visible light having specific wavelength characteristics is applied to the resist layer, and the method of Patent Document 2 discloses that one type of visible light having the same wavelength characteristics is divided into two types. It is only disclosed to alternately hit the object from the direction. Therefore, in the methods of Patent Documents 1 and 2, the surface of the photosensitive material after exposure having a plurality of portions having different characteristics relating to light absorption and reflection, the stains on the surface, the surface structure, etc. Cannot be imaged so that they can be distinguished by image processing.

  In view of the above, the present invention provides an image processing apparatus, an image processing method, and an exposure pattern inspection apparatus that image the surface of a photosensitive material so that the state of the surface of the photosensitive material can be inspected with higher sensitivity by image processing. The purpose is to provide.

  In order to achieve the above object, an image processing apparatus according to an embodiment of the present invention includes an imaging control unit that controls an imaging apparatus that images the surface of a photosensitive material conveyed in a predetermined direction, and illumination that illuminates the surface. An illumination control unit that controls the device; and an image processing unit that processes an image output from the imaging device, wherein the image processing unit uses the first illumination light that includes light having a first wavelength. A first image that the imaging device images and outputs a predetermined area of the surface when the surface is illuminated, and a second illumination light that includes light having a second wavelength shorter than the first wavelength, The difference between the image pickup apparatus and the second image output by the image pickup apparatus picking up the predetermined area when illuminating is revealed.

  An image processing method according to an embodiment of the present invention includes an imaging step in which an imaging device images the surface of a photosensitive material conveyed in a predetermined direction, an illumination step in which an illumination device illuminates the surface, and the imaging device includes: An image processing step for processing an image to be output. In the image processing step, when the illumination device illuminates the surface with first illumination light including light of a first wavelength, the imaging device The imaging device captures the predetermined region when the illumination device illuminates the surface with a first image that captures and outputs a predetermined region and the illumination device illuminates the surface with a second illumination light including light having a second wavelength shorter than the first wavelength. Thus, the difference from the second image to be output becomes obvious.

  An exposure pattern inspection apparatus according to an embodiment of the present invention includes an imaging control unit that controls an imaging apparatus that images the surface of an ultraviolet-sensitive material after exposure conveyed in a predetermined direction, and an illumination device that illuminates the surface. An illumination control unit for controlling, and an image processing unit for processing an image output from the imaging device, wherein the image processing unit is configured to apply the first illumination light including light of a first wavelength to the surface. When the imaging device illuminates the surface with a second image including a first image that the imaging device captures and outputs a predetermined area of the surface when illuminated, and the illumination device includes light having a second wavelength shorter than the first wavelength Further, the difference between the image pickup device and the second image output by picking up the predetermined area is made obvious.

  By the means described above, the present invention provides an image processing apparatus, an image processing method, and an exposure pattern inspection apparatus for imaging the surface of a photosensitive material so that the state of the surface of the photosensitive material can be inspected with higher sensitivity by image processing. Can be provided.

It is a block diagram which shows the structural example of the exposure pattern inspection apparatus which concerns on the Example of this invention. It is a side view of the exposure pattern inspection apparatus of FIG. It is an upper surface view of a printed circuit board when the printed circuit board conveyed with a belt conveyor is located in the vertically downward direction of an imaging device. FIG. 4 is an enlarged view of a region IV surrounded by a dotted line in FIG. 3. It is a flowchart which shows the flow of an exposure pattern inspection process. It is a figure which shows the example of the photomask used in the case of exposure of a photoresist. It is a figure which shows the relationship of the various images used or produced | generated by the exposure pattern test | inspection process.

  FIG. 1 is a block diagram showing a configuration example of an exposure pattern inspection apparatus 100 according to an embodiment of the present invention. FIG. 2 is a side view of the exposure pattern inspection apparatus 100. In the present embodiment, the exposure pattern inspection apparatus 100 inspects, for example, an exposure pattern of a photoresist that is an ultraviolet photosensitive material on the printed circuit board PS conveyed by the belt conveyor BC. Specifically, the exposure pattern inspection apparatus 100 is configured to remove a resist pattern immediately after exposure, a resist pattern immediately after removal of a photomask, a resist pattern after resist development, or a resist residue after resist removal, and the surface structure of the printed circuit board. Inspect with distinction.

  The photoresist contains a dye that causes a photosensitive action, and the chemical structure of the dye is changed by the photosensitive action, whereby the photosensitive part or the non-photosensitive part is selectively dissolved by the developer. The photosensitive portion is different from the unexposed portion in wavelength characteristics regarding light absorption and reflection. Therefore, the exposed portion and the unexposed portion can be optically distinguished by illuminating the exposed photoresist with light having a wavelength that matches the wavelength characteristics of the exposed portion. In addition, by exposing the exposed photoresist with light having energy lower than that of ultraviolet rays for causing a photosensitive action, the unexposed portion is optically distinguished from the unexposed portion without exposing the unexposed portion. Can do.

  Some pigments in the photoresist emit visible light having a relatively low energy by a fluorescent action when irradiated with light having a relatively high energy such as ultraviolet rays. After the unexposed portion of the photoresist is removed, there is no risk of additionally exposing the unexposed portion even if the photoresist is irradiated with ultraviolet rays. And other parts can be optically distinguished.

  The exposure pattern inspection apparatus 100 inspects the exposure pattern using the characteristics of the photoresist as described above.

  In the present embodiment, the exposure pattern inspection apparatus 100 mainly includes a control device 1, an input device 2, an imaging device 3, an illumination device 4, and an output device 5.

  The control device 1 is a device for controlling the exposure pattern inspection device 100. For example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a non-volatile RAM (NVRAM), and the like. It is a computer equipped with. Specifically, for example, the control device 1 reads out programs corresponding to the respective functional elements of the imaging control unit 10, the illumination control unit 11, and the image processing unit 12 from the ROM and expands them in the RAM, while expanding each functional element. The CPU is caused to execute processing corresponding to the above.

  The input device 2 is a device for inputting various types of information, and is, for example, a keyboard, a mouse, a touch pad, a button, a microphone, or the like for inputting a command to the control device 1 by an operator.

  The imaging device 3 is a device for imaging the inspection target, and is, for example, a line camera that images a part of the surface of the printed circuit board PS. Specifically, the imaging device 3 is a line camera in which imaging elements such as CMOS and CCD are arranged in a line, and images a range RC perpendicular to the transport direction of the printed circuit board PS indicated by an arrow AR from directly above. Note that the image output by the imaging device 3 may be a color image or a monochrome image.

  FIG. 3 is a top view of the printed circuit board PS when the printed circuit board PS conveyed by the belt conveyor BC is positioned vertically below the imaging apparatus 3, and an area surrounded by a one-dot chain line indicates an imaging range RC of the imaging apparatus 3. Show.

  As described above, the imaging device 3 includes the entire width (the length in the direction perpendicular to the transport direction) of the printed circuit board PS to be inspected in the imaging range RC.

  The illumination device 4 is a device for illuminating the inspection target. For example, the upstream illumination unit 4U disposed on the upstream side in the transport direction with respect to the imaging device 3 and the downstream in the transport direction with respect to the imaging device 3 2 illumination parts of the downstream illumination part 4D arrange | positioned at the side are included. Note that both of the two illumination units may be disposed on the upstream side in the transport direction with respect to the imaging device 3, or may be disposed on the downstream side in the transport direction with respect to the imaging device 3.

  In the present embodiment, the upstream side illumination unit 4U is arranged so as to illuminate the printed circuit board PS at an angle of 45 degrees with respect to the optical axis of the imaging device 3 extending in the vertical direction from the upstream side in the transport direction. Further, the downstream side illumination unit 4D is disposed so as to illuminate the printed circuit board PS at an angle of 45 degrees with respect to the optical axis of the imaging device 3 from the downstream side in the transport direction. In this way, the upstream side illumination unit 4U and the downstream side illumination unit 4D are arranged so that the illumination by each is line-symmetric with respect to the optical axis of the imaging device 3. However, the present invention is not limited to this. Both the upstream side illumination unit 4U and the downstream side illumination unit 4D may be arranged so as to illuminate the printed circuit board PS from almost directly above, or may be arranged so as to illuminate the printed circuit board PS from the same direction. The illumination may be arranged so as to be asymmetric with respect to the optical axis of the imaging device 3.

  The upstream side illumination unit 4U includes a light source 40U, an optical fiber 41U, a light emitting unit 42U, and a cylindrical lens 43U.

  The light source 40U is a light source that emits first illumination light including light of a first wavelength. For example, a laser diode that emits first illumination light mainly containing light having a wavelength absorbed by the photosensitive portion of the photoresist. Or it is a light emitting diode. Note that the first illumination light includes, for example, light having a wavelength of 600 nm or more as dominant light, and is preferably monochromatic light having a wavelength of 600 nm or more. In this embodiment, the light source 40U is composed of a plurality of light emitting diodes that emit red light having a wavelength of 645 nm.

  The optical fiber 41U is a member that guides the first illumination light emitted from the light source 40U to the light emitting unit 42U, and the light emitting unit 42U is a member that emits the first illumination light toward the cylindrical lens 43U.

  The cylindrical lens 43U is a lens that changes the incident light only in one axial direction so that a linear beam is formed at the focal point. Specifically, the cylindrical lens 43U directs the first illumination light incident from the light emitting unit 42U to the printed circuit board PS and illuminates a range RU perpendicular to the conveyance direction of the printed circuit board PS.

  A region surrounded by a broken line in FIG. 3 indicates the illumination region RU of the upstream illumination unit 4U. The illumination area RU includes the imaging range RC of the imaging device 3 therein.

  Similar to the upstream side illumination unit 4U, the downstream side illumination unit 40D includes a light source 40D, an optical fiber 41D, a light emitting unit 42D, and a cylindrical lens 43D.

  The light source 40D is a light source that emits second illumination light including light having a second wavelength shorter than the first wavelength. For example, the second illumination that mainly includes light having a wavelength reflected by the photosensitive portion of the photoresist. It is a laser diode or a light emitting diode that emits light. Note that the second illumination light includes, for example, light having a wavelength of less than 600 nm as dominant light, and is preferably monochromatic light having a wavelength of less than 600 nm. In this embodiment, the light source 40D is composed of a plurality of light emitting diodes that emit green light having a wavelength of 522 nm. The light source 40D may be a laser diode or a light emitting diode that emits light having a wavelength that causes the fluorescence action of the photoresist, for example, less than 522 nm, preferably 450 nm or less.

  The optical fiber 41D is a member that guides the second illumination light emitted from the light source 40D to the light emitting unit 42D, and the light emitting unit 42D is a member that emits the second illumination light toward the cylindrical lens 43D.

  Similarly to the cylindrical lens 43U, the cylindrical lens 43D is a lens that changes the incident light only in one axial direction so that a linear beam is formed at the focal point. Specifically, the cylindrical lens 43D directs the second illumination light incident from the light emitting unit 42D to the printed circuit board PS and illuminates a range RD perpendicular to the transport direction of the printed circuit board PS.

  A region surrounded by a broken line in FIG. 3 indicates an illumination region RD of the downstream illumination unit 4D. The illumination area RD is the same area as the illumination area RU of the upstream side illumination unit 4U, and includes the imaging range RC of the imaging device 3 therein.

  The output device 5 is a device for outputting various information, and is, for example, a display for displaying the inspection result of the exposure pattern by the control device 1, or a speaker for outputting the inspection result by voice.

  Next, various functional elements included in the control device 1 will be described.

  The imaging control unit 10 is a functional element for controlling the imaging device 3 and controls, for example, the imaging timing of the imaging device 3.

  Specifically, for example, when the imaging control unit 10 detects that the printed circuit board PS has approached or entered the imaging range RC of the imaging device 3 by an object detection sensor such as a photoelectric sensor (not shown), the imaging device 3. The imaging by is started.

  The illumination control unit 11 is a functional element for controlling the illumination device 4, and controls the illumination timing of the illumination device 4, for example.

  Specifically, for example, the illumination control unit 11 operates the two illumination units of the illumination device 4 alternately in synchronization with the imaging by the imaging device 3, and the illumination range RU including the imaging range RC of the imaging device 3, Illuminate RD alternately.

  Here, the relationship among the imaging timing of the imaging device 3, the illumination timing of the illumination device 4, and the conveyance speed of the printed circuit board PS will be described with reference to FIG. 4 is an enlarged view of a region IV surrounded by a dotted line in FIG. 3, and shows a state of the printed circuit board PS passing through the imaging range RC of the imaging device 3. Note that each of the regions RC-RU1, RC-RU2, RC-RU3, and RC-RU4 indicated by the thin alternate long and short dash lines in FIG. Represents. In addition, each of the regions RC-RD1, RC-RD2, and RC-RD3 indicated by the thick alternate long and short dash lines in FIG. 4 represents the relative position of the imaging range RC with respect to the printed circuit board PS when the downstream illumination unit 4D emits light.

  FIG. 4 shows a state where the imaging range of the imaging device 3 moves on the stationary printed circuit board PS in the left direction in the figure, but actually, the imaging range that is fixedly arranged is the printed circuit board PS. Passes in the right direction of the figure. For the sake of clarity, FIG. 4 shows the imaging range when the upstream illumination unit 4U emits light and the imaging range when the downstream illumination unit 4D emits light being shifted up and down. The range does not deviate.

  As illustrated in FIG. 4, when the control device 1 detects that the printed circuit board PS has approached or entered the imaging range RC by an object detection sensor (not shown), the imaging control unit 10 causes the printed circuit board to be connected to the imaging device 3. The surface of PS is imaged. In addition, the control device 1 causes the illumination control unit 11 to cause the upstream illumination unit 4U to emit light in synchronization with imaging by the imaging device 3.

  Thereafter, the control device 1 stands by until the printed circuit board PS moves by a predetermined distance D1 with respect to the imaging range RC. Specifically, the control device 1 calculates a required movement time required for the movement of the predetermined distance D1 from a predetermined conveyance speed of the printed circuit board PS, and waits until the required movement time elapses.

  The predetermined distance D1 is a value stored in advance as a distance for determining the imaging interval, and is, for example, a value obtained by dividing the pixel resolution of the imaging device 3 by the number of illumination units of the illumination device 4.

  “Pixel resolution” means the imaging size per pixel, and is, for example, a value obtained by dividing the visual field size in a predetermined direction by the number of pixels in the predetermined direction of the imaging device.

  In this embodiment, the field of view size of the imaging device 3 in the transport direction of the printed circuit board PS is D2 [μm], and the number of pixels of the image sensor in the transport direction is 1, so the pixel resolution is D2 [μm]. . Moreover, since the number of the illumination parts of the illuminating device 4 is 2, the predetermined distance D1 is D2 / 2 [μm]. If the transport speed of the printed circuit board PS is V [μm / second], the required movement time is D1 / V [second], that is, D2 / (2 × V) [second].

  When detecting that the required travel time has elapsed, the control device 1 causes the imaging control unit 10 to cause the imaging device 3 to image the surface of the printed circuit board PS again. In addition, the control device 1 causes the illumination control unit 11 to cause the downstream illumination unit 4D to emit light in synchronization with imaging by the imaging device 3.

  Thereafter, the control device 1 alternates between the upstream illumination unit 4U and the downstream illumination unit 4D every time the required movement time elapses until the rear end in the transport direction of the printed circuit board PS comes out of the imaging range RC of the imaging device 3. The imaging by the imaging device 3 is repeated while emitting light.

  With such imaging timing and illumination timing, the control device 1 joins the images captured when the upstream illumination unit 4U emits light, and represents the entire surface of the printed circuit board PS illuminated with the first illumination light 1 A first image can be generated. Similarly, the control device 1 joins the images captured when the downstream side illumination unit 4D emits light, and generates one second image representing the entire surface of the printed circuit board PS illuminated with the second illumination light. can do. Specifically, the imaging control unit 10 separately stores an image captured when the upstream side illumination unit 4U emits light and an image captured when the downstream side illumination unit 4D emits light. A first image and a second image are generated.

  Further, due to the above-described imaging timing and illumination timing, the deviation between the first image and the second image in the transport direction of the printed circuit board PS is less than the pixel resolution of the imaging device 3. Therefore, the first image and the second image display substantially the same surface area without deviation, and are in a state suitable for taking the difference between the two images.

  In the above-described embodiment, the predetermined distance D1 is set to a value obtained by dividing the pixel resolution of the imaging device 3 by the number of illumination units of the illumination device 4. However, the present invention is not limited to this. Before the moving distance of the printed circuit board PS reaches the pixel resolution of the imaging device 3, imaging when the upstream illumination unit 4U emits light and imaging when the downstream illumination unit 4D emits light are performed once. If the moving distance of the printed circuit board PS until the next imaging for causing the same illumination unit to emit light is equal to or greater than the pixel resolution, the predetermined distance D1 is set to an arbitrary value within a range larger than 0 and smaller than D2. It may also be changed for each imaging.

  The image processing unit 12 is a functional element that processes an image captured by the imaging device 3 so that an exposure pattern can be inspected. For example, the image processing unit 12 executes a process of making the difference between the first image and the second image manifest.

  Here, with reference to FIG. 5, a process (hereinafter referred to as “exposure pattern inspection process”) in which the control device 1 inspects the exposure pattern based on the first image and the second image will be described. FIG. 5 is a flowchart showing the flow of the exposure pattern inspection process.

  First, the image processing unit 12 of the control device 1 binarizes each of the first image and the second image to generate a binarized first image and a binarized second image (step S1). When the imaging device 3 outputs a color image, the image processing unit 12 performs binarization processing after performing grayscale processing on each of the first image and the second image.

  Thereafter, the image processing unit 12 generates a first difference image representing a difference between the binarized first image and the binarized second image (step S2).

  The first image is an image captured when the surface of the printed circuit board PS is illuminated by the first illumination light in which light having a wavelength absorbed by the photosensitive portion of the photoresist is dominant. That is, the first image can be visually recognized by the first illumination light, and is all the shapes, patterns, and colors (hereinafter referred to as “shapes”) on the surface of the printed circuit board PS, except for the shape of the photosensitive portion. The shape and the like are stored in an image so as to be visible.

  The second image is an image captured when the surface of the printed circuit board PS is illuminated by the second illumination light in which the light having the wavelength reflected by the photosensitive portion of the photoresist is dominant. That is, the second image is stored in an image-like manner so that all the shapes including the shape of the photosensitive portion among the shapes on the surface of the printed circuit board PS that can be visually recognized by the second illumination light are visible.

  Therefore, the first difference image is a shape etc. excluding the shape memorized in the first image out of the shape memorized in the second image, ie, the shape of the photosensitive part of the photoresist, etc. Represents. Specifically, in the first difference image, the pixel value of the pixel included in the image portion representing the shape or the like of the photosensitive portion is set to a value that can be distinguished from the pixel values of other pixels.

  Since the first image and the second image are formed using the imaging timing and illumination timing as shown in FIG. 4, the image resolution (number of vertical and horizontal pixels) is the same, and the imaging range is substantially the same. . Therefore, the image processing unit 12 does not require additional processing such as positioning processing and enlargement / reduction processing for associating the pixels in the first image with the pixels in the second image.

  Thereafter, the image processing unit 12 generates a second difference image representing the difference between the exposure pattern reference image and the first difference image (step S3).

  The exposure pattern reference image is an image representing an ideal exposure pattern stored in advance in a ROM or the like.

  Therefore, the second difference image is an image having no shape to be displayed if the shape of the photosensitive portion of the photoresist represented by the first difference image is the same as the ideal exposure pattern. On the other hand, if the shape of the photosensitive portion of the photoresist represented by the first difference image is different from the ideal exposure pattern, the second difference image represents only the shape of the different portion. Specifically, in the second difference image, the pixel value of a pixel (hereinafter referred to as “difference display pixel”) included in an image portion representing the shape or the like of the different portion can be distinguished from the pixel values of other pixels. Set to a valid value.

  Thereafter, the control device 1 determines whether there is an abnormality in the exposure pattern based on the second difference image generated by the image processing unit 12 (step S4).

  For example, the control device 1 determines that there is an abnormality in the exposure pattern if the number of different display pixels in the second difference image is equal to or greater than a predetermined value. Then, the control device 1 displays the second differential image on the display as the output device 5 together with the text message notifying the presence of the abnormality, or the voice message or buzzer notifying the presence of the abnormality from the speaker as the output device 5. Output audio.

  Next, various images used or generated in the exposure pattern inspection process will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram illustrating an example of a photomask used for exposure of a photoresist. FIG. 6A illustrates a photomask MK without adhesion of foreign matter, and FIG. The photomask MK to which the foreign material FP is attached is shown. FIG. 7 is a diagram showing the relationship between various images used or generated in the exposure pattern inspection process.

  As shown in FIG. 7, the first image G1 output by the image pickup device 3 is picked up when the first illumination light having a wavelength dominant in the light absorbed by the photosensitive portion of the photoresist is used as illumination. Since it is an image, the shape of the photosensitive portion is not displayed so as to be visible. On the other hand, the first image G1 displays dirt DC and wrinkles WR1 and WR2 on the surface of the photoresist so as to be visible. The dirt DC and the wrinkles WR1 and WR2 are for reflecting the first illumination light.

  In addition, the second image G2 output from the imaging device 3 is an image that is captured when the second illumination light having a dominant wavelength reflected by the photosensitive portion of the photoresist is used as illumination. The shape EPa of the photosensitive portion and the remaining resist UP are displayed so as to be visible. This is because the shape EPa of the photosensitive portion and the resist remaining UP reflect the second illumination light. The shape EPa of the photosensitive portion is an exposure pattern obtained when exposure is performed using the mask pattern MK to which the foreign matter FP shown in FIG. 6B is attached, and a defective portion due to the presence of the foreign matter FP. Has FPa. Further, the second image G2 displays the stain DC and wrinkles WR1 and WR2 on the surface of the photoresist so as to be visible. The dirt DC and the wrinkles WR1 and WR2 are for reflecting the second illumination light.

  Therefore, the first difference image G3 generated by taking the difference between the first image G1 and the second image G2 as described above is the stain DC displayed on both the first image G1 and the second image G2. This represents a state in which the image portions of the wrinkles WR1 and WR2 have been removed. That is, the first difference image G3 displays the shape EPa of the photosensitive portion and the remaining resist UP UP that are not displayed in the first image G1 but are displayed in the second image G2.

  The exposure pattern reference image GR is an image stored in advance in a ROM or the like, and represents an ideal exposure pattern EP obtained when exposure is performed using the mask pattern MK shown in FIG.

  The second difference image G4 generated by taking the difference between the exposure pattern reference image GR and the first difference image G3 is obtained by removing the image portion displayed in both the exposure pattern reference image GR and the first difference image G3. Represents a state. That is, the second difference image G4 is not displayed in the exposure pattern reference image GR, but is not displayed in the resist remaining UP displayed in the first difference image G3 and the first difference image G3. The displayed defect portion FPa is displayed in the exposure pattern reference image GR so as to be visible.

  Based on the image portion that is visible in the second difference image G4 generated as described above, that is, the pixel having a predetermined luminance value, the control device 1 detects abnormalities such as a defective portion or a resist residue in the exposure pattern. Can be detected. Further, the control device 1 determines that the image portion represented by the pixels having the predetermined luminance value is exposed depending on whether or not the pixels having the predetermined luminance value are included in the region where the exposure pattern should be. It is possible to distinguish whether the pattern is a defective portion or a resist residue. Note that the region where the exposure pattern should be is determined based on the exposure pattern reference image GR.

  With the above configuration, the exposure pattern inspection apparatus 100 can determine whether there is an abnormality in the exposure pattern formed on the printed circuit board PS. In addition, the exposure pattern inspection apparatus 100 can distinguish between types of abnormalities in the exposure pattern such as a defective portion and a resist residue, and can recognize the shape of the abnormal portion.

  In addition, the exposure pattern inspection apparatus 100 can distinguish between dirt and wrinkles on the surface of the printed circuit board PS and the shape of the photosensitive portion, and prevents such dirt and wrinkles from being erroneously detected as a resist residue. be able to.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the exposure pattern inspection apparatus 100 causes light having predetermined wavelengths different from each other to be dominant in each of the first illumination light and the second illumination light. The light possessed may be visible light or other than visible light. For example, the exposure pattern inspection apparatus 100 may be configured such that the ultraviolet light that causes the fluorescent action of the photosensitive portion is dominant in the second illumination light. In this case, imaging by the exposure pattern inspection apparatus 100 is performed after resist development. This is because if the image is taken before resist development, the unexposed portion of the resist before development is exposed to ultraviolet rays.

  In the above-described embodiment, the exposure pattern inspection apparatus 100 captures one imaging range RC with one imaging apparatus 3 while switching the type of illumination light, but performs common imaging while switching the type of illumination light. You may make it image the surface of the printed circuit board PS with the several imaging device 3 which has the range RC. In this case, the exposure pattern inspection apparatus 100 requires an additional process such as a positioning process or an enlargement / reduction process in accordance with the optical magnification of each of the plurality of imaging apparatuses 3 in order to acquire a difference image. There is a case. This means that such additional processing can be omitted when one imaging device 3 images one imaging range RC.

  Alternatively, the exposure pattern inspection apparatus 100 may capture the same region on the surface of the printed circuit board PS with a plurality of imaging apparatuses 3 having different imaging ranges while switching the type of illumination light. In this case, the exposure pattern inspection apparatus 100 images the same region on the surface of the printed circuit board PS at different timings and different places. Therefore, the conveyance speed of the printed circuit board PS needs to be controlled with high accuracy. This means that the requirement for the accuracy of the conveyance speed of the printed circuit board PS is alleviated when one or more imaging devices 3 image one imaging range RC.

  In the above-described embodiment, the exposure pattern inspection apparatus 100 employs a line camera as the imaging apparatus 3, but may employ an area camera. When an area camera having an imaging range that can include the entire surface of the printed circuit board PS is used, the exposure pattern inspection apparatus 100 moves the printed circuit board PS by a distance corresponding to the pixel resolution in the transport direction of the area camera. The imaging under the illumination with the first illumination light and the imaging under the illumination with the second illumination light are each performed once. When an area camera is employed, a large number of pixels are required to obtain a high resolution image, and it is necessary to store image information relating to each of these many pixels in a short time. This means that when a line camera is employed, the demand for the number of pixels and the demand for storage of image information are alleviated.

  Further, in the above-described embodiment, the exposure pattern inspection apparatus 100 images the surface of the printed circuit board PS while alternately switching two types of illumination light, but the printed circuit board PS while cyclically switching three or more types of illumination light. You may make it image the surface of. When three types of illumination light are used, the exposure pattern inspection apparatus 100 performs illumination under each of the three types of illumination light while the printed circuit board PS moves a distance corresponding to the pixel resolution in the transport direction of the imaging device 3. The imaging at is performed once each.

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus 2 ... Input device 3 ... Imaging device 4 ... Illumination device 4D, 4U ... Illumination part 40D, 40U ... Light source 41D, 41U ... Optical fiber 42D, 42U ... Light emitting part 43D, 43U ... Cylindrical lens 5 ... Output device 10 ... Imaging control part 11 ... Illumination control part 12 ... Image processing part 100 ... Exposure pattern inspection apparatus BC ..Belt conveyor DC ... Dirt EP, EPa ... Exposure pattern FP ... Foreign matter G1 ... First image G2 ... Second image G3 ... First difference image G4 ... Second Difference image GR: Exposure pattern reference image MK: Mask pattern PS: Printed circuit board RC, RC-RD1 to RC-RD3, RC-RU1 to RC-RU4: Imaging range RD, RU: Illumination range UP: Resist remaining WR1, WR2: Wrinkle

Claims (9)

An imaging controller that controls an imaging device that images the surface of the photosensitive material conveyed in a predetermined direction;
An illumination control unit that controls an illumination device that illuminates the surface;
An image processing unit that processes an image output by the imaging device,
The image processing unit includes: a first image that the imaging device images and outputs a predetermined region of the surface when the illumination device illuminates the surface with first illumination light including light of a first wavelength; and the illumination When the apparatus illuminates the surface with second illumination light including light having a second wavelength shorter than the first wavelength, the imaging apparatus makes a difference from the second image that is output by imaging the predetermined region,
Image processing device. The illumination control unit controls the illumination device to illuminate the predetermined region by sequentially switching a plurality of types of illumination light having different wavelength characteristics,
The imaging control unit each time the moving distance of the photosensitive material conveyed at a predetermined speed in the predetermined direction becomes a value obtained by dividing the pixel resolution of the imaging device by the number of types of illumination light of the illumination device. Controlling the imaging device so that the imaging of the predetermined area is performed by the imaging device,
The switching by the illumination controller and the imaging by the imaging controller are synchronized.
The image processing apparatus according to claim 1. The image processing unit makes the difference between the first image and the second image obvious by taking a difference between the first image and the second image;
The image processing apparatus according to claim 1. The imaging device is a line camera having a field of view perpendicular to the conveyance direction of the photosensitive material.
The image processing apparatus according to claim 1. The second wavelength is less than 522 nm;
The image processing apparatus according to claim 1. The second wavelength is 450 nm or less.
The image processing apparatus according to claim 1. The lighting device is a light emitting diode or a laser diode.
The image processing apparatus according to claim 1. An imaging step in which the imaging device images the surface of the photosensitive material conveyed in a predetermined direction;
An illumination step in which an illumination device illuminates the surface;
An image processing step for processing an image output by the imaging device,
In the image processing step, when the illumination device illuminates the surface with first illumination light including light of a first wavelength, the imaging device images and outputs a predetermined area of the surface, and the illumination When the apparatus illuminates the surface with second illumination light including light having a second wavelength shorter than the first wavelength, the difference from the second image that the imaging apparatus images and outputs the predetermined area is made obvious. ,
Image processing method. An imaging control unit that controls an imaging device that images the surface of the ultraviolet-sensitive material after exposure conveyed in a predetermined direction;
An illumination control unit that controls an illumination device that illuminates the surface;
An image processing unit that processes an image output by the imaging device,
The image processing unit includes: a first image that the imaging device images and outputs a predetermined region of the surface when the illumination device illuminates the surface with first illumination light including light of a first wavelength; and the illumination When the apparatus illuminates the surface with second illumination light including light having a second wavelength shorter than the first wavelength, the imaging apparatus makes a difference from the second image that is output by imaging the predetermined region,
Exposure pattern inspection device.

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