JP2008185514A - Substrate visual inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the misinformation rate regardless of the skewness of a substrate image in performing the visual inspection of the substrate using CAD (Computer Aided Design) data. <P>SOLUTION: This substrate visual inspection apparatus includes a substrate observing means 100 for determining an observation value A that is observation data of a photographed substrate image and reflects the deformation of the substrate image, a design value calculating means 200 for calculating the design value (a) in relation to the design image created from the CAD data, a deformation parameter calculating means 20 for calculating a deformation parameter given by A/a, a reference image creating means 30 for making the deformation parameter act on the design value (a) to deform the design image into the reference image, and an image superimposing means 40 that calculates the coincidence between the substrate attribute and reference attribute related to the respective positions in the substrate image and reference image while varying the relative position between the substrate image and reference image, and superimposes the substrate image and reference image on each other at the point of the highest coincidence. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a board appearance inspection apparatus for inspecting appearance of a printed wiring board and a mounting board.

  On the printed wiring board, a wiring pattern, a through hole for connecting the electronic component to the wiring pattern, a land, a pad, silk, and the like for soldering the lead frame of the electronic component to the wiring pattern are formed. In the manufacturing process of a printed wiring board, defects such as disconnection, short circuit, pattern width shortage, foreign matter adhesion, and pinholes of these wiring patterns may occur.

  These defects are detected by a substrate appearance inspection. Conventionally, the substrate appearance inspection has been performed by an operator visually observing the substrate appearance. However, in recent years, a dedicated substrate appearance inspection apparatus has been introduced in order to increase the accuracy and speed of inspection, and automation of substrate appearance inspection has been achieved (for example, see Patent Document 1).

  In the technique described in Patent Document 1, first, a printed printed board is photographed. Then, after the position of the photographed image (hereinafter referred to as “substrate image”) is corrected using the master data, the appearance inspection is performed by comparing with the master image photographed in advance.

Furthermore, as a recent new trend, an attempt has been made to use, as a master image for visual inspection, an image created from CAD (Computer Aided Design) data instead of an image obtained by photographing a printed circuit board (for example, Patent Document 2). reference).
JP 10-123063 A JP 2005-164277 A

  However, the technique described in Patent Document 2 has a problem that there are many false reports because the master image obtained from CAD data is simply superimposed on the substrate image.

  Hereinafter, this point will be described in detail. A substrate image obtained by photographing a printed circuit board may be distorted due to the effects of substrate warpage, manufacturing error, aberration of the lens used for photographing, fluctuation in the conveyance speed of the substrate, and the like.

  In the technique described in Patent Document 2, a master image derived from CAD data is superimposed on a substrate image without considering this distortion. For this reason, it may be difficult to distinguish between the distortion of the substrate image and the true defect, and as a result, many false reports have been generated.

  The present invention has been made in view of such problems. Accordingly, an object of the present invention is to provide a substrate appearance inspection apparatus with a small false alarm rate regardless of the distortion of the substrate image when performing the appearance inspection of the substrate using CAD data.

  In order to achieve the above-described object, the substrate visual inspection apparatus of the present invention includes the following functional means as constituent elements. As is well known, these functional means are realized by causing a computer to read a program.

  The board appearance inspection apparatus according to claim 1 uses a computer and functions as a board observing means, a design value calculating means, a deformation parameter calculating means, a reference image creating means, an image superimposing means, and a storage means. And.

  The board observing means obtains an observation value A that is the observation data relating to the physical quantity of the board image, which is an image of the taken board, and reflects the deformation of the board image caused by the internal factor or the external factor.

  The design value calculation means obtains a design value a corresponding to the observation value A for a design image created by reading CAD data for board design from the storage means.

  The deformation parameter calculation means calculates a deformation parameter given by A / a.

  The reference image creating means creates a reference image that is a deformed image of the design image by applying the deformation parameter to the design value a.

  The image superimposing means tentatively superimposes the substrate image and the reference image, and is an attribute common to the substrate image and the reference image, the substrate attribute related to the position in each of the substrate image and the reference image. And the reference attribute are calculated while changing the relative positions of the board image and the reference image, and the board image and the reference image at the point where the degree of matching is maximized are superimposed.

  According to the first aspect of the present invention, the deformation parameter calculation means calculates the degree of deformation of the board image obtained by photographing the board with respect to the design image derived from CAD data as the deformation parameter. Then, the reference image creating means creates the reference image by deforming the design image according to the deformation parameter. The created reference image derived from CAD data is an image reflecting the distortion of the board image.

  Furthermore, when superimposing the board image and the reference image, the image superimposing means calculates the degree of coincidence between the board attribute and the reference attribute while shifting both images little by little. Then, the overlay of both images is adjusted by a shift amount that gives the maximum degree of matching. As a result, both images are accurately superimposed.

  The substrate appearance inspection apparatus according to claim 2 is the substrate appearance inspection device according to claim 1, preferably, the substrate attribute is a shape of a specific component arranged on the substrate image, and the reference attribute is on the reference image. The shape of the part corresponding to the specified specific part is used.

  According to the second aspect of the present invention, the image superimposing unit adopts the shape of the specific component that exists in common in both the board image and the reference image as the board attribute and the reference attribute. Thereby, the image superimposing unit can evaluate the degree of coincidence between the board attribute and the reference attribute as the degree of coincidence on both images of the specific component. As a result, the image superimposing unit can accurately superimpose the substrate image and the reference image.

  According to a third aspect of the substrate visual inspection apparatus of the present invention, the first orthogonal coordinate system including the first coordinate axis and the second coordinate axis is commonly set in the substrate image and the reference image. Then, the board attribute is a first and second board image color distribution as the color distribution of the board image along each of the first and second coordinate axes, and the reference attribute is on each of the first and second coordinate axes. First and second reference image color distributions as the color distributions of the reference images along.

  According to the third aspect of the present invention, the substrate image color distribution (first and second substrate image color distribution) along each of the first and second coordinate axes is employed as the substrate attribute. Similarly, the color distribution of the reference image (first and second reference image color distribution) along each of the first and second coordinate axes is adopted as the reference attribute.

  Accordingly, the image superimposing unit relatively shifts the positions of the substrate image and the reference image, thereby matching the first substrate image color distribution and the first reference image color distribution, the second substrate image color distribution, and the first image distribution. The degree of coincidence of the two reference image color distributions can be evaluated. As a result, the image superimposing unit can accurately superimpose the substrate image and the reference image.

  A substrate appearance inspection apparatus according to a fourth aspect is the substrate appearance inspection apparatus according to any one of the first to third aspects, wherein three or more common reference areas are set for each of the substrate image and the design image.

  Then, the substrate observation unit sets n substrate distances from the first substrate distance to the n-th substrate distance (n is an integer of 3 or more) as the distance between the reference regions in the substrate image as the observed value A.

  Further, the design value calculation means sets n design distances from the first design distance to the nth design distance as distances between reference regions in the design image as design values a.

  Further, the deformation parameter calculation means calculates (first substrate distance / first design distance) to (nth substrate distance / nth design distance) as the deformation parameter A / a.

  Further, the reference image creation means multiplies (first board distance / first design distance) by the first design distance, multiplies (second board distance / second design distance) by the second design distance,... And (first substrate distance / first design distance) to (nth substrate distance / nth design) as deformation parameters A / a so that (nth substrate distance / nth design distance) is multiplied by nth design distance. By multiplying the distance) by the first design distance to the nth design distance as the design value a, a reference image obtained by deforming the design image is created.

  According to the fourth aspect of the present invention, as a deformation parameter for obtaining a reference image obtained by deforming the design image according to the board image, the ratio of the distance between the reference areas set in common in the board image and the design image Is used.

  Specifically, the first design distance between the reference regions of the design image is multiplied by (first substrate distance / first design distance), and the second design distance is (second substrate distance / second design distance). Multiplication,..., (Nth substrate distance / nth design distance) is multiplied by (nth substrate distance / nth design distance). The design image is deformed by multiplying each by (1 design distance) to (nth substrate distance / nth design distance). As a result, the reference image creating means creates a reference image reflecting the deformation of the board image from the design image.

  The substrate appearance inspection apparatus according to claim 5 is the substrate appearance inspection apparatus according to any one of claims 1 to 3, wherein the substrate image and the design image include a third coordinate axis and a fourth coordinate axis. Are set in common.

  Then, the board observing means uses the coordinates of one end and the other end of the board image along the third coordinate axis direction and the peak coordinates in the color distribution of the board image along the third coordinate axis direction as the first reference points, respectively. In addition, the coordinates of one end and the other end of the substrate image along the fourth coordinate axis direction and the peak coordinates in the color distribution of the substrate image along the fourth coordinate axis direction are set as the second reference points. Then, m (m is an integer of 1 or more) third substrate reference point distances as distances between adjacent first reference points, and p (as a distance between adjacent second reference points) Both the distances between the fourth substrate reference points (p is an integer equal to or greater than 1) are defined as the observed value A described above.

  In addition, the design value calculation means sets the coordinates of one end and the other end of the design image along the third coordinate axis direction, and the peak coordinates in the color distribution of the design image along the third coordinate axis direction, respectively, as a third reference point. And the coordinates of one end and the other end of the design image along the fourth coordinate axis direction and the peak coordinates in the color distribution of the design image along the fourth coordinate axis direction are respectively set as the fourth reference points. . And a distance between m third design reference points as a distance between adjacent third reference points, and a distance between p fourth design reference points as a distance between adjacent fourth reference points. Both are set to the above-mentioned design value a.

  The deformation parameter calculation means calculates m (distance between third substrate reference points / distance between third design reference points) as the deformation parameter A / a with respect to the third coordinate axis direction, and the fourth coordinate axis. Regarding the direction, p pieces (distance between fourth substrate reference points / distance between fourth design reference points) are calculated.

  Furthermore, the reference image creation means multiplies the corresponding distance between the third design reference points by m (distance between the third substrate reference points / distance between the third design reference points) in the third coordinate axis direction. For the fourth coordinate axis direction, a reference image is obtained by multiplying each of the p (distance between fourth substrate reference points / distance between fourth design reference points) by the corresponding distance between fourth design reference points. Create

  According to the fifth aspect of the present invention, the substrate observing means is configured such that, from the substrate image, the distances between the m third substrate reference points and the p fourth substrates along the third and fourth coordinate axes, respectively. The distance between the reference points is calculated. The distance between the third and fourth substrate reference points represents the distance between peaks of the color distribution of the substrate image along the third and fourth coordinate axes.

  Similarly, the design value calculation means is configured to determine the distance between m third design reference points and the distance between p fourth design reference points from the design image along the third and fourth coordinate axes common to the board image. Is calculated. The distance between the third and fourth design reference points represents the distance between peaks of the color distribution of the design image along the third and fourth coordinate axes.

  Here, each of the m third substrate reference point distances has a one-to-one correspondence with the m third design reference point distances. Similarly, each of the p fourth substrate reference point distances has a one-to-one correspondence with the p fourth design reference point distances.

  For the third coordinate axis, the deformation parameter calculation means calculates the distance between the third pair of substrate reference points and the distance between the third design reference points corresponding to each other with respect to the third coordinate axis (distance between the third substrate reference points / third design reference point). Distance).

  Similarly, the deformation parameter calculating means calculates the distance between the fourth substrate reference point and the distance between the fourth design reference points corresponding to each other with respect to the fourth coordinate axis (distance between the fourth substrate reference points / the fourth distance). The distance between design reference points is calculated.

  Thus obtained m (distance between third substrate reference points / distance between third design reference points) and p (distance between fourth substrate reference points / distance between fourth design reference points) are obtained. It is a deformation parameter.

  The deformation parameter represents the ratio between the distance between peaks of the color distribution of the substrate image undergoing deformation and the distance between peaks of the color distribution of the design image, which is a design drawing of the substrate. That is, m (distance between third substrate reference points / distance between third design reference points) and p (distance between fourth substrate reference points / distance between fourth design reference points) as deformation parameters are It represents the degree of deformation of the board image.

  The reference image creating means multiplies the corresponding distance between the third design reference points by multiplying the distance between the third design reference points by the distance between the third substrate reference points / the distance between the third design reference points. Deform along the coordinate axis direction. Similarly, the design image is deformed along the fourth coordinate axis direction by multiplying the corresponding distance between the fourth design reference points by the distance between the fourth substrate reference points / the distance between the fourth design reference points. In this way, for both the third and fourth coordinate axes, an image in which the design image is deformed similarly to the board image, that is, a reference image is created.

The substrate appearance inspection apparatus according to claim 6, in the substrate appearance inspection apparatus according to any one of claims 1 to 3, taken a substrate is conveyed at set transport speed V ₀ which is set in advance by the line sensor image Is used as the substrate image.

  The substrate observation means uses the actual conveyance speed V (d) at the position coordinate d along the substrate conveyance direction as the observation value A.

The design value calculation means uses the set conveyance speed V ₀ as the design value a regarding the design image.

The deformation parameter calculation means uses (V (d) / V ₀ ) at the position coordinate d of the substrate as the deformation parameter A / a.

The reference image creating means divides the length along the transport direction of the design image by (V (d) / V ₀ ) as the deformation parameter A / a at the position corresponding to the position coordinate d of the design image. Thus, a reference image is created.

  According to the sixth aspect of the present invention, it is possible to correct the substrate conveyance speed fluctuation that occurs during photographing.

  More specifically, when the substrate is imaged by the line sensor, the obtained substrate image is shifted in length along the conveyance direction due to fluctuations in the substrate conveyance speed when passing through the imaging region.

  That is, in the region where the conveyance speed is high, the length of the substrate passing through the imaging region is relatively long during the imaging time interval (shutter interval) of the line sensor. In other words, the distance between the substrate area photographed by the first shutter and the substrate area photographed by the second shutter becomes longer. As a result, in the region where the conveyance speed is high, the length of the substrate image is apparently relatively short. For the same reason, in the region where the conveyance speed is low, the length of the substrate image is apparently relatively long.

In the present invention, (V (d) / V ₀ ) at the position coordinate d of the substrate is used as the deformation parameter. Therefore, by dividing the length of the design image along the conveyance direction by (V (d) / V ₀ ) at the position of the design image corresponding to the position coordinate d, a reference image reflecting the conveyance speed distribution is obtained. can get.

  A substrate appearance inspection apparatus according to a seventh aspect is the substrate appearance inspection apparatus according to any one of the first to third aspects, wherein three or more common reference areas are set for each of the substrate image and the design image.

  Then, the substrate observation unit sets n substrate distances from the first substrate distance to the n-th substrate distance (n is an integer of 3 or more) as the distance between the reference regions in the substrate image as the observed value A.

  Further, the design value calculation means sets n design distances from the first design distance to the nth design distance as distances between reference regions in the design image as design values a.

  Further, the deformation parameter calculation means calculates a simple average of (first substrate distance / first design distance) to (nth substrate distance / nth design distance) as the deformation parameter A / a.

  Furthermore, the reference image creation means creates the reference image by deforming the design image by multiplying the first design distance to the nth design distance as the design value a by the simple average as the deformation parameter A / a, respectively. .

  The invention described in claim 7 is the same as the invention described in claim 4 until three or more reference regions are set in the substrate image and the design image, respectively, and the observation value A and the design value a are obtained. It is. The difference from the invention of claim 4 is that a “simple average” of (first substrate distance / first design distance) to (nth substrate distance / nth design distance) is used as the deformation parameter. That is, a single value (simple average value) is used as the deformation parameter.

  As a result, when the board image and the design image are similar, the reference image can be created more easily by multiplying the design image by a simple average value.

  The substrate appearance inspection apparatus according to an eighth aspect is the substrate appearance inspection apparatus according to the seventh aspect, wherein the reference image creating means is (first substrate distance / first design distance) to (nth substrate distance / nth design distance). A simple average is calculated by removing outliers from the inside.

  According to the eighth aspect of the present invention, a simple average is obtained after excluding abnormal values from (first substrate distance / first design distance) to (nth substrate distance / nth design distance). Yes. Thereby, it is possible to prevent the simple average value from being dragged to the abnormal value.

  The substrate appearance inspection apparatus according to a ninth aspect uses a computer and includes substrate observation means, design value calculation means, deformation parameter calculation means, reference image creation means, and image superimposition means.

  The substrate observing means and the design value calculating means are configured in the same manner as the substrate observing means and the design value calculating means of the invention of claim 1.

  The deformation parameter calculation means calculates a deformation parameter given by a / A.

  The reference image creating means multiplies the deformation parameter by the observed value A to deform the substrate image to obtain a reference image.

  The image superimposing means provisionally superimposes the reference image and the design image, and is an attribute common to the reference image and the design image, and is a reference attribute related to the position in each of the reference image and the design image And the design attribute are calculated while changing the relative positions of the reference image and the design image, and the reference image and the design image at the point where the degree of coincidence is maximized are superimposed.

  The invention according to claim 9 is different from the inventions of claims 1 to 8 in that the substrate image is deformed in accordance with the design image. That is, a reference image is created by applying a deformation parameter to the substrate image, and the reference image and the design image are overlaid with a maximum degree of coincidence.

  Since the present invention is configured as described above, it is possible to provide a substrate visual inspection apparatus with a low false alarm rate regardless of the distortion of a substrate image when performing visual inspection of a substrate using CAD data. it can.

  Embodiments of the present invention will be described below with reference to the drawings. Each drawing is merely a schematic representation of the shape, size, and arrangement relationship of each component to the extent that the present invention can be understood. Moreover, although the preferable structural example of this invention is demonstrated hereafter, the material of each component, a numerical condition, etc. are only a suitable example. Therefore, the present invention is not limited to the following embodiments. Moreover, in each figure, the same code | symbol is attached | subjected to a common component and the description may be abbreviate | omitted.

(Embodiment 1)
With reference to FIGS. 1-6, the board | substrate external appearance inspection apparatus of Embodiment 1 is demonstrated.

<Board>
First, a substrate to be inspected by the substrate appearance inspection apparatus 10 will be described with reference to FIG.

  FIG. 1 shows a photograph of a partial region of the surface of the substrate S taken by the substrate appearance inspection apparatus 10. As shown in FIG. 1, the substrate S is preferably a printed circuit board, for example. On the substrate S, substrate components such as wiring patterns, lands, pads, and silk are arranged in a predetermined pattern. The board appearance inspection apparatus 10 extracts a plurality of areas to be inspected from the pattern according to the difference in shape and color. The substrate appearance inspection apparatus 10 determines the quality of the substrate by inspecting the color for each region to be inspected in the appearance inspection.

  Hereinafter, the pattern of the substrate S taken by the substrate appearance inspection apparatus 10 is referred to as a “substrate image”.

  The substrate S is composed of a plurality of layers stacked in the thickness direction of the substrate S. In each of these layers, a different pattern is formed for each layer. Each of these layers is made of a transparent material (for example, a prepreg or a solder resist) or a non-transparent material (for example, a copper wiring layer). Here, “transparent” is a concept including not only colorless and transparent but also colored and transparent. Hereinafter, a pattern formed in each layer is referred to as a “layer pattern”.

  As a result, the color and shape of the pattern included in the substrate image are determined by the balance between the color and transparency of each layer constituting the substrate S and the layer pattern shape of each layer.

  For example, in the region of the substrate S having a laminated structure of “transparent material layer / non-transparent material layer”, the layer pattern of the non-transparent material layer existing below the transparent material layer is visually observed through the transparent material layer. Is done. The color of this area is the sum of the color of the transparent material layer and the color of the non-transparent material layer.

  On the other hand, in the region having a laminated structure of “non-transparent material layer / transparent material layer”, only the layer pattern of the non-transparent material layer existing on the upper side is visually observed, and the layer pattern of the transparent material layer existing on the lower side is Cannot be seen. And this area | region exhibits only the color of a non-transparent material layer.

  The layer pattern of each layer is formed based on CAD data for each layer stored in advance (hereinafter referred to as “CAD data for each layer”). That is, the CAD data for each layer corresponds to each layer in a one-to-one relationship, and functions as a design drawing for each layer.

  The layer-specific CAD data does not include information on color and transparency. The CAD data for each layer includes only information about the layer pattern shape of each layer until it gets tired.

  The CAD data corresponding to the photographed board image (FIG. 1) is obtained by superimposing the layered CAD data of all layers after alignment. Hereinafter, the image of the substrate S created from the superimposed CAD data is referred to as a “design image”. The design image is a design drawing of the substrate image.

<Configuration and operation of substrate visual inspection apparatus>
Next, the structure and operation of the substrate visual inspection apparatus will be described with reference to FIG. FIG. 2 is a block diagram of the board appearance inspection apparatus.

  Referring to FIG. 2, the board appearance inspection apparatus 10 includes, as components, an imaging unit 102, a board observing means 100, a design value calculating means 200, a deformation parameter calculating means 20, a reference image creating means 30, and an image. Superimposing means 40. Further, the board appearance inspection apparatus 10 includes a CAD data storage unit 50, an inspection unit 70, and an output unit 80 as components.

  The substrate observation unit 100 includes a correction unit 104, a substrate reference region extraction unit 106, and an observation value calculation unit 108 as functional units. The design value calculation unit 200 includes a CAD data reading unit 202, a design image creation unit 204, a design reference area extraction unit 206, and a calculation value calculation unit 208 as functional units. The CAD data storage unit 50 includes a reference area storage unit 52 as a function unit. The inspection unit 70 includes a region feature data extraction unit 72, an inspection unit 74, and a reference feature data storage unit 76 as functional units.

  Of these components, the remaining units other than the photographing unit 102 and the output unit 80 are configured as computer functional units. The CAD data storage means 50 and the reference feature data storage means 76 are provided in common or separately as an internal memory or an external memory of the computer, and can be arbitrarily configured. Further, although not shown, a storage unit for storing required information or data other than the information stored in the CAD data storage unit 50 and the reference feature data storage unit 76 may be provided as required.

  Although individual explanation is omitted, information or data generated by each means is stored in a desired storage means so as to be readable. If the information or data is stored in this way, the information or data can be read out from the storage means and used in each process described below.

  Moreover, the board | substrate visual inspection apparatus 10 is provided with an input part (not shown). The input unit may include a keyboard, a mouse, and the like, as well as an electrical, magnetic, or optical reading device.

  Hereinafter, the configuration and operation of each functional unit described above will be described in detail.

  The photographing unit 102 constitutes a part of the input unit, and creates an original substrate image by photographing the substrate S transported on the stage T. The photographing unit 102 is preferably configured as an RGB (Red, Green, and Blue) line sensor, for example. The original substrate image created in the imaging unit 102 is output to the correction unit 104.

  The board observing means 100 has a function of obtaining observation values A that are observation data relating to physical quantities of a board image, which is an image of the taken board S, and reflecting the deformation of the board image caused by an internal factor or an external factor.

  Here, the “deformation of the substrate image caused by internal or external causes” will be described. As described in the section (Problems to be Solved by the Invention), the substrate image may be deformed (distorted). Substrate image deformation is broadly classified into intrinsic and extrinsic ones. The causes of intrinsic deformation include, for example, warpage of the substrate S that occurs during the manufacturing process of the substrate S, and positional displacement of substrate components (such as pads) due to manufacturing errors. Examples of the cause of the exogenous deformation include fluctuation in the conveyance speed of the substrate S at the time of photographing, lens aberration of the photographing camera, and the like.

  The substrate observation unit 100 includes a correction unit 104, a substrate reference region extraction unit 106, and an observation value calculation unit 108 as functional units.

  The correcting unit 104 corrects the original substrate image photographed by the photographing unit 102 and creates a substrate image. More specifically, the correction unit 104 mainly performs skew correction of the original substrate image. “Skew” means the inclination of the original substrate image on the image.

  More specifically, the substrate S is provided with two linear alignment marks orthogonal to each other in order to represent the inclination of the substrate S. The correcting unit 104 corrects the skew by rotating the original substrate image so that one alignment mark is parallel to the X axis on the image and the other alignment mark is parallel to the Y axis on the image. .

  The board image created in this way is output to both the board reference area extracting unit 106 and the image superimposing unit 40.

  The board reference area extraction unit 106 extracts three or more reference areas common to both the board image and the design image from the board image.

  More specifically, the substrate reference area extraction unit 106 is connected to the reference area storage unit 52 of the CAD data storage unit 50. The reference area storage unit 52 stores coordinates indicating the shape of the reference area for each reference area. As the reference region, for example, lands and pads provided in various places on the substrate S can be preferably used.

  The reference area storage unit 52 of the CAD data storage unit 50 stores the coordinates of the reference area and the position coordinates of the center of gravity in the design image. The reference area will be described later.

  The CAD data storage means 50 further stores the layer-specific CAD data described above.

  Substrate reference region extraction means 106 searches for a reference region on the substrate image (hereinafter referred to as “in-image reference region”) in the vicinity of the coordinates read from reference region storage unit 52. Specifically, an area on the substrate image having a high degree of coincidence with the shape of the reference area read from the reference area storage unit 52 is determined as an in-image reference area. The coordinates of the reference area in the image thus determined are output to the observation value calculation means 108.

  The observation value calculation means 108 calculates “a first substrate distance to an nth substrate distance (n is an integer of 3 or more)” as an observation value A as a distance between three or more reference regions in the image. .

  More specifically, the observed value calculation means 108 calculates the center of gravity of the image reference region for each image reference region. Then, “a first substrate distance to an nth substrate distance” as a distance between these centroids is calculated.

  Here, with reference to FIG. 3A, the calculation of the observed value A performed by the observed value calculating means 108 will be described with an example. FIG. 3A is a schematic plan view of a substrate image. In order to avoid complication of the drawing, in FIG. 3A, illustration of substrate components other than the pad as the reference area in the image is omitted.

  In the substrate image, for example, it is assumed that five pads Pm1 to Pm5 exist as reference areas in the image at the four corners and the central portion. The observation value calculation means 108 reads the center of gravity coordinates of the pads Pm1 to Pm5 and reads the calculation formula of the distance from a storage means (not shown) to obtain the first substrate distance Lm12 and the first substrate distance Lm12 as the distance between the centers of gravity of the pads Pm1 to Pm5. The second substrate distance Lm23, the third substrate distance Lm34, the fourth substrate distance Lm14, the fifth substrate distance Lm15, the sixth substrate distance Lm25, the seventh substrate distance Lm35, and the eighth substrate distance Lm45 are calculated.

  The first to eighth substrate distances Lm12 to Lm45 calculated in this way are output to the deformation parameter calculation means 20 shown in FIG.

  On the other hand, the design value calculation means 200 has a function of obtaining a design value a corresponding to the observed value A from a design image created from CAD data for designing the substrate S.

  The CAD data reading means 202 of the design value calculating means 200 has a function of reading CAD data for designing the substrate S from the CAD data storage means 50. Specifically, the CAD data reading unit 202 reads the above-described layer-specific CAD data from the CAD data storage unit 50.

  The layer-by-layer CAD data read by the CAD data reading means 202 is output to the design image creating means 204.

  The design image creation unit 204 creates a design image from the layer-by-layer CAD data input from the CAD data reading unit 202. Specifically, the design image creation unit 204 superimposes the layer-specific CAD data after alignment in the same order as the stacking order of each layer on the substrate S. Thereby, a design image corresponding to the substrate image is obtained.

  The design image created by the design image creation means 204 is output to both the design reference area extraction means 206 and the reference image creation means 30.

  The design reference area extraction unit 206 extracts three or more reference areas common to both the design image and the board image from the design image.

  More specifically, the design reference area extraction unit 206 is connected to the reference area storage unit 52 of the CAD data storage unit 50. As already described, the reference area storage unit 52 stores coordinates indicating the shape of the reference area for each reference area. The design reference area extraction unit 206 determines a reference area (hereinafter referred to as “design reference area”) on the design image from the read coordinates. The coordinates of the design reference area thus determined are output to the calculated value calculation means 208.

  The calculated value calculation means 208 reads a distance calculation formula from a storage means (not shown), and calculates “first design distance to nth design distance” as a distance between three or more design reference areas as the design value a. To do.

  More specifically, the calculated value calculation means 208 calculates the coordinates of the center of gravity of the design reference area for each design reference area. Then, “first design distance to nth design distance” as a distance between the centroids is calculated.

  Here, with reference to FIG. 3B, the calculation of the design value a performed by the calculation value calculation means 208 will be described with an example. FIG. 3B is a schematic plan view of a design image. In order to avoid complication of the drawing, in FIG. 3B, illustration of elements other than the pad as the design reference region is omitted.

  In the design image, for example, it is assumed that five pads Ps1 to Ps5 exist as design reference areas corresponding to the pads Pm1 to Pm5 (substrate reference area: FIG. 3A). Similar to the observed value calculation means 108, the calculated value calculation means 208 is a first design distance Ls12, a second design distance Ls23, a third design distance Ls34, and a fourth design distance Ls14 as the distance between the centers of gravity of the pads Ps1 to Ps5. , Fifth design distance Ls15, sixth design distance Ls25, seventh design distance Ls35, and eighth design distance Ls45.

  The first to eighth design distances Ls12 to Ls45 calculated in this way are output to the deformation parameter calculation means 20.

  The deformation parameter calculation means 20 receives the first to eighth substrate distances Lm12 to Lm45 as the observation value A from the observation value calculation means 108. Further, the first to eighth design distances Ls12 to Ls45 as the design value a are input to the deformation parameter calculation unit 20 from the calculation value calculation unit 208.

  The deformation parameter calculation means 20 reads the deformation parameter A / a from a storage means (not shown), and (first substrate distance Lm12 / first design distance Ls12) to (eighth substrate distance Lm45 / eighth design distance Ls45). calculate.

  Hereinafter, the deformation parameters A / a (first substrate distance Lm12 / first design distance Ls12) to (eighth substrate distance Lm45 / eighth design distance Ls45) are simply expressed as (Lm12 / Ls12) to (Lm45 / Ls45). ).

  Here, the deformation parameter A / a represents the degree of deformation of the board image with respect to the design image. For example, (Lm12 / Ls12) is obtained by dividing the distance between the pads Pm1 and Pm2 in the board image (first board distance Lm12) by the distance between the corresponding pads Ps1 and Ps2 in the design image (first design distance Ls12). Is.

  Therefore, if the substrate image is deformed so that the first substrate distance Lm12 is longer than the first design distance Ls12, the deformation parameter (Lm12 / Ls12) is larger than 1 (Lm12 / Ls12> 1). . Conversely, if the substrate image is deformed so that the first substrate distance Lm12 is shorter than the first design distance Ls12, the deformation parameter (Lm12 / Ls12) is less than 1 (Lm12 / Ls12 <1).

  The deformation parameters (Lm12 / Ls12) to (Lm45 / Ls45) calculated as described above are output to the reference image creating unit 30.

  The design image is input from the design image creation unit 204 to the reference image creation unit 30. Further, the transformation parameters (Lm12 / Ls12) to (Lm45 / Ls45) are input to the reference image creation unit 30 from the transformation parameter calculation unit 20.

  The reference image creation means 30 multiplies the deformation parameters (Lm12 / Ls12) to (Lm45 / Ls45) by the first to eighth design distances Ls12 to Ls45 as the design value a, respectively, to deform the design image. Create an image.

  More specifically, the lengths of the first to eighth design distances Ls12 to Ls45 in the design image are shortened or expanded in accordance with each of the deformation parameters (Lm12 / Ls12) to (Lm45 / Ls45). Thereby, a design image deformed according to the distortion of the board image, that is, a deformed image is generated as a reference image.

  Here, with reference to FIG. 4, the creation of the reference image by the reference image creation means 30 will be described. FIG. 4 is a schematic diagram for explaining the creation of a reference image.

  In FIG. 4, pads indicated by broken lines indicate pads Ps1 to Ps5 in the design image. Pads indicated by solid lines indicate pads Pr1 to Pr5 in the reference image.

  In the design image, the first to eighth design distances Ls12 to Ls45 are multiplied by deformation parameters (Lm12 / Ls12) to (Lm45 / Ls45), respectively. Thereby, the reference image creation means 30 deforms the entire design image so that the positions of the pads Ps1 to Ps5 are displaced to the pads Pr1 to Pr5.

  An image obtained in this manner, that is, an image in which the entire design image is deformed according to the deformation parameters (Lm12 / Ls12) to (Lm45 / Ls45) is the reference image.

  The reference image created in this way is output to the image superimposing means 40.

  The image superimposing unit 40 receives the substrate image from the correcting unit 104 and the reference image from the reference image creating unit 30.

  The image superimposing means 40 provisionally superimposes the substrate image and the reference image, and is an attribute common to the substrate image and the reference image, and is related to the positions in the images of the substrate image and the reference image. The degree of coincidence between the attribute and the reference attribute is calculated while changing the relative positions of the board image and the reference image, and the board image and the reference image are superimposed on the point where the degree of coincidence is maximized.

  More specifically, the image superimposing means 40 employs, for example, a pad shape as attributes (substrate attributes and reference attributes) common to the substrate image and the reference image.

  The image superimposing means 40 temporarily superimposes the substrate image and the reference image so that these pads overlap each other. Then, the degree of coincidence of the pad shapes, that is, the overlapping area of the pads is calculated while displacing either the substrate image or the reference image. Then, the overlapping position of the substrate image and the reference image is determined at the point where the overlapping area of the pads is maximized, that is, the point of coincidence is maximized.

  Here, the operation of the image superimposing means 40 will be specifically described with reference to FIG. FIG. 5 is a schematic diagram for explaining the determination operation of the overlapping position of the reference image and the substrate image.

  As shown in FIG. 5, the image superimposing means 40 provisionally superimposes the reference image and the board image. At this time, the pad Pm on the substrate image and the pad Ps on the reference image corresponding to the pad Pm are at least partially overlapped.

  Then, the image overlapping means 40 moves, ie scans, the reference image in both the X-axis direction and the Y-axis direction as indicated by an arrow A in the figure while calculating the overlapping area between the pad Pm and the pad Ps. This scanning is performed by the so-called raster scan method.

  As a result, graphs as shown in FIGS. 6A and 6B are obtained. In FIG. 6A, the vertical axis represents the overlapping area of the pads Pm and Ps, and the horizontal axis represents the displacement amount of the reference image in the X direction. Similarly, in FIG. 6B, the vertical axis represents the overlapping area of the pads Pm and Ps, and the horizontal axis represents the displacement amount of the reference image in the Y direction.

Figure 6 curve C1 is a point having the maximum value (A), the a displacement X ₀ which gives the maximum degree of coincidence between pad Pm and Ps of the X-direction. Similarly, in FIG. 6 (B) curve C2 is a point having the maximum value, the displacement amount Y ₀ which gives the maximum degree of coincidence between pad Pm and Ps in the Y direction.

The image superimposing means 40 superimposes the substrate image and the reference image at a point where the degree of coincidence between the substrate attribute and the reference attribute is maximized, that is, at points where the displacement amounts are X ₀ and Y ₀ .

  The image (hereinafter referred to as “inspected image”) in which the substrate image and the reference image are superimposed in this manner is output to the inspection unit 70.

  The inspection unit 70 has a function of performing a substrate appearance inspection using the inspected image.

  The region feature data extraction unit 72 of the inspection unit 70 determines a plurality of regions to be inspected based on the difference in image shape and color in the image to be inspected, and assigns region numbers to the regions to be inspected. Then, the region feature data extraction unit 72 reads feature data pixel by pixel from each inspection region. Here, the feature data is, for example, a color for each pixel (RGB gradation value).

  That is, the area feature data extraction unit 72 assigns an area number to each inspection area and reads the characteristic data of each inspection area one pixel at a time.

  The feature data obtained in this way is output to the inspection unit 74 together with the region number and the pixel position.

  The inspection unit 74 compares the feature data for each region to be inspected with reference feature data stored in advance, and inspects whether each region to be inspected is a good product or a defective product.

  More specifically, the inspection unit 74 is connected to the reference feature data storage unit 76. The reference feature data storage means 76 stores the color (RGB gradation value) for each area to be inspected in a one-to-one relationship with the area number as a reference value (reference feature data) of the feature data.

  The inspection unit 74 compares the reference feature data read from the reference feature data storage unit 76 with the feature data input from the region feature data extraction unit 72 for each region having the same region number.

  Then, it is checked whether or not the feature data matches the reference feature data. If they match, the inspection unit 74 determines that there is no defect in the pixel. Conversely, if the two do not match, the pixel is determined to be a mismatched pixel, and the coordinates of the mismatched pixel are stored.

  The inspection unit 74 evaluates the spatial spread of the mismatched pixels when the inspection in one inspection region is completed. That is, the inspection unit 74 determines that there is a defective portion in the inspected area when the inconsistent pixels are continuously present in a predetermined area or more.

  The position of the defective portion detected by the inspection unit 74 is transmitted to the output unit 80.

  The output unit 80 includes a display device such as a display, an output device such as a printer, and the like, and has a function of presenting the inspection result of the inspection unit 74 to the operator.

  More specifically, the output unit 80 marks the position of the defective portion input from the inspection unit 74 on the substrate image and displays it on a display device such as a display.

<Effect>
(1) In the board appearance inspection apparatus 10, the deformation parameter calculation means 20 calculates the degree of deformation of the board image obtained by photographing the board with respect to the design image derived from CAD data as the deformation parameter. Then, the reference image creation means 30 creates a reference image obtained by deforming the design image according to the deformation parameter. Thereby, the distortion of a board | substrate image is reflected in the reference image derived from CAD data.

  As a result, even if there is distortion in the board image, the reference image derived from CAD data can be accurately superimposed on the board image. Therefore, it is possible to reduce false information in the substrate appearance inspection.

  (2) The board appearance inspection apparatus 10 is such that the image superimposing means 40 has the highest degree of coincidence between the shape of the pad Pm as the board attribute and the shape of the pad Ps as the reference attribute. And overlay. As a result, the reference image can be accurately superimposed on the substrate image. Therefore, it is possible to reduce false information in the substrate appearance inspection.

  (3) The board appearance inspection apparatus 10 can create a reference image that also reflects the distortion (Embodiment 3) of the board image caused by a fluctuation in the conveyance speed of the board S described later.

<Design conditions>
(1) In this embodiment, the case where the board | substrate S was a printed circuit board was demonstrated. However, the board S is not limited to a printed board. For example, the board S may be a mounting board in which various electronic components are mounted on a printed board.

  (2) In this embodiment, the case where the reference image is created by deformation of the design image has been described. However, the reference image may be created by deforming the board image according to the design image.

  Also by doing in this way, the reference image and the design image can be superimposed with the maximum degree of coincidence.

  (3) In this embodiment, when creating a reference image, (first substrate distance / first design distance) is a deformation parameter that corresponds one-to-one with (first design distance to nth design distance). The case of multiplying by (nth substrate distance / nth design distance) has been described.

  However, when the similarity between the substrate image and the design image is ensured at a practically sufficient level, the deformation parameters are (first substrate distance / first design distance) to (nth substrate distance / first). A simple average of (n design distances) may be used.

  Here, “similarity between the substrate image and the design image is ensured at a practically sufficient level” means, for example, (first substrate distance / first design distance) to (nth substrate distance / nth). This means that the variation in the value of the design distance is within a certain range.

  In this case, if there is an abnormal value with a variation exceeding a certain range in (first substrate distance / first design distance) to (nth substrate distance / nth design distance), the abnormality is detected. A simple average that is a deformation parameter may be obtained by excluding the value.

  By doing so, it is possible to create a reference image by similar deformation of the design image, and it is possible to reduce the amount of calculation for obtaining the reference image.

  (4) In this embodiment, the case where the inspection unit 74 uses RGB gradation values as the characteristic data of the region to be inspected has been described. However, the feature data is not limited to RGB gradation values, and may be, for example, luminance for each pixel.

(Embodiment 2)
With reference to FIGS. 7 to 11, the substrate appearance inspection apparatus according to the second embodiment will be described. FIG. 7 is a block diagram of the substrate appearance inspection apparatus according to the second embodiment. In FIG. 7, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The appearance inspection apparatus 12 according to the second embodiment is different from the first embodiment in that a color histogram is used to calculate deformation parameters and to superimpose a substrate image and a reference image.

  Referring to FIG. 2, the board appearance inspection apparatus 12 includes an imaging unit 102, a board observing means 100, a design value calculating means 200, a deformation parameter calculating means 20, a reference image creating means 30, and an image superimposing means 400. It has. Furthermore, the board appearance inspection apparatus 12 includes a CAD data storage unit 50, an inspection unit 70, and an output unit 80.

  Of these components, the remaining units other than the photographing unit 102 and the output unit 80 are configured as computer functional units. Similarly to the first embodiment, the board appearance inspection apparatus 12 includes a storage unit and an input unit (not shown).

  Hereinafter, the configuration and operation of each functional unit described above will be described in detail.

  Since the configuration and operation of the imaging unit 102 are the same as those in Embodiment 1, the description thereof is omitted.

  The board observation unit 100 sets the coordinates of one end and the other end of the board image along the third coordinate axis direction and the peak coordinates in the color distribution of the board image along the third coordinate axis direction as the first reference points. And m (m is an integer of 1 or more) third substrate reference point distances between the adjacent first reference points, and one end and the other end of the substrate image along the fourth coordinate axis direction Part coordinates and peak coordinates in the color distribution of the substrate image along the fourth coordinate axis direction are set as second reference points, respectively, and p pieces (p is 1 or more) as a distance between adjacent second reference points Integer) has a function of calculating the distance between the fourth substrate reference points as the observed value A.

  The substrate observation unit 100 includes a correction unit 104, a first substrate histogram creation unit 110, and an observation value calculation unit 112.

  Since the configuration and operation of the correction unit 104 are the same as those in the first embodiment, description thereof is omitted.

  The first substrate histogram creating means 110 has a function of creating a color histogram from a substrate image.

  Hereinafter, this point will be described in detail with reference to FIG. FIG. 8 is a schematic diagram showing a substrate image together with a color histogram (color distribution).

The first substrate histogram creating means 110, on the substrate image, sets the coordinate axes _{X 2} and _{Y 2} are orthogonal to each other. Here, coordinate axes X ₂ corresponds to the third coordinate axis mentioned above, and coordinate axes Y ₂ corresponds to the fourth coordinate axis mentioned above. The coordinate system consisting of coordinate axes X ₂ and Y ₂ corresponds to the second orthogonal coordinate system.

The first substrate histogram creating means 110 creates a third substrate histogram mH ₃ reflecting a specific color of the substrate image (hereinafter referred to as “specific color”) along the coordinate axis X ₂ direction. Similarly, the first substrate histogram creating means 110, along the coordinate axis _{Y 2} direction, creating a fourth substrate histogram mH ₄ for a specific color. The third and fourth substrate histograms mH ₃ and mH ₄ correspond to the “color distribution” described in the claims.

  More specifically, the first substrate histogram creation unit 110 calculates the brightness of a specific color for all the pixels of the substrate image. Then, the board image is binarized with respect to a specific color using a suitably selected luminance threshold. That is, the board image is converted into a black and white image related to the specific color.

Then, at any point of the coordinate axes X _2, the number of white pixels counted in Y ₂ axially, the intensity of the histogram at that point. This operation was performed for all points of the coordinate axes X _2, to create a third substrate histogram mH _3.

Similarly, at any point in the coordinate axis Y _2, the number of white pixels counted in the X ₂ axis direction, the strength of the histogram at that point. This operation was performed for all points of the coordinate axis Y _2, to create a fourth substrate histogram mH _4.

The third and fourth substrate histograms mH ₃ and mH ₄ created in this way are output to the observation value calculation means 112.

The observation value calculation means 112 reads the peak coordinates as the first reference point from the third substrate histogram mH ₃ and calculates the distance between the third substrate reference points (observation value A) as the distance between the adjacent first reference points. To do. Similarly, the observed value calculation means 112 reads the peak coordinates as the second reference point from the fourth substrate histogram mH ₄ , and the fourth substrate reference point distance (observed value A as the distance between the adjacent second reference points). ) Is calculated.

Hereinafter, the operation of the observation value calculation unit 112 will be described in detail with reference to FIG. The observation value calculation unit 112 analyzes the third substrate histogram mH ₃ and obtains the coordinates of the three peaks regarding the coordinate axis X ₂ as the first reference points mP ₁ , mP ₂ and mP ₃ . Furthermore, the observed value calculating means 112, the coordinates of one end and the other end of the substrate image along the coordinate axis _{X 2,} determined as the first reference point mP ₀ and mP _4. Here, the magnitude relationship between the coordinates of the first reference points mP _{0 to} mP _{4 in} the direction of the coordinate axis X ₂ is “mP ₀ <mP ₁ <mP ₂ <mP ₃ <mP ₄ ”.

Then, the observation value calculation means 112 calculates four third substrate reference point distances mL ₀₁ , mL ₁₂ , mL ₂₃ and mL ₃₄ as the distances between the adjacent first reference points.

Similarly, the observed value calculation means 112 analyzes the fourth substrate histogram mH ₄ and obtains the coordinates of the three peaks regarding the coordinate axis Y ₂ as the second reference points mP ₆ , mP ₇ and mP ₈ . Further, the observation value calculating means 112 obtains the coordinates of one end and the other end of the substrate image along the coordinate axis Y ₂ as the second reference points mP ₅ and mP ₉ . Here, the magnitude relationship between the coordinates of the second reference points mP _{5 to} mP ₉ with respect to the coordinate axis Y ₂ is “mP ₅ <mP ₆ <mP ₇ <mP ₈ <mP ₉ ”.

Then, the observed value calculation means 112 calculates four fourth substrate reference point distances mL ₅₆ , mL ₆₇ , mL ₇₈ and mL ₈₉ as the distances between the adjacent second reference points.

The distances between the third and fourth substrate reference points calculated in this way, mL _{01 to} mL ₈₉ , correspond to the observed value A. These observation values A are output to the deformation parameter calculation means 20.

  On the other hand, the design value calculation means 200 uses the third reference coordinates for the coordinates of one end and the other end of the design image along the third coordinate axis direction and the peak coordinates in the color distribution of the design image along the third coordinate axis direction. Set as a point, the distance between m third design reference points as the distance between adjacent third reference points, and the coordinates of one end and the other end of the design image along the fourth coordinate axis direction, The peak coordinates in the color distribution of the design image along the fourth coordinate axis direction are set as the fourth reference points, respectively, and both of the p fourth design reference point distances as the distances between the adjacent fourth reference points. As a design value a.

  Since the configuration and operation of the CAD data reading unit 202 and the design image creating unit 204 of the design value calculating unit 200 are the same as those in the first embodiment, the description thereof is omitted.

  The design histogram creation means 210 has a function of creating a color histogram from a design image which is a so-called line drawing.

  Hereinafter, this point will be described in detail.

  As described in the first embodiment, the design image is only the superimposed CAD data for each layer, and does not include information on color. Therefore, the design histogram creating means 210 first performs an operation of coloring the design image when creating the color histogram.

  More specifically, the design histogram creation unit 210 reads the color data 54 for each layer in the CAD data storage unit 50. The layer-specific color data 54 stores information on the color and transparency of each layer constituting the design image. The CAD data storage means 50 stores the above-described layer-specific CAD data in addition to the layer-specific color data 54.

  The design histogram creation means 210 colors each layer based on the layer-specific color data 54 to obtain a colored design image.

  Thereafter, the design histogram creating unit 210 creates a color histogram from the design image in the same manner as the first substrate histogram creating unit 110 already described.

  Hereinafter, this point will be described in detail with reference to FIG. FIG. 9 is a schematic diagram showing a design image together with a color histogram.

The design histogram creation means 210 sets a third coordinate axis (coordinate axis X ₂ ) and a fourth coordinate axis (coordinate axis Y ₂ ) that are common to the board image on the design image.

Then, the design histogram creating means 210 binarizes the design image for the specific color already described. On top of that, at any point in the coordinate axis X _2, the number of white pixels counted in Y ₂ axially, the intensity of the histogram at that point. This operation was performed for all points of the coordinate axes X _2, to create a third design histogram sH _3.

Similarly, at an arbitrary point on the coordinate axis Y ₂ , the number of white pixels counted in the X ₂ axis direction is taken as the intensity of the histogram at that point. This operation was performed for all points of the coordinate axis Y _2, to create a fourth design histogram sH _4.

The third and fourth design histograms sH ₃ and sH ₄ created in this way are output to the calculated value calculation means 212.

Calculated value calculating means 212, the third design histogram sH ₃ reads the peak coordinates of the third reference point, calculate a third between design reference point distance as the distance between the third reference point that is adjacent (design value a) To do. Similarly, the calculated value calculating means 212, the fourth design histogram sH ₄ reads the peak coordinates of the fourth reference point, the distance between the fourth design reference point as the distance between the fourth reference points adjacent (design value a ) Is calculated.

  The operation of the calculation value calculation means 212 is the same as that of the observation value calculation means 112 already described. Therefore, description of the configuration and operation is omitted, and only the results obtained are described.

As shown in FIG. 9, the calculated value calculation means 212 obtains third reference points sP ₀ , sP ₁ , sP ₂ , sP ₃ and sP ₄ from the third design histogram sH ₃ . Then, the third design reference point distances sL ₀₁ , sL ₁₂ , sL ₂₃ and sL ₃₄ are calculated as the design value a.

Similarly, the calculated value calculation means 212 obtains fourth reference points sP ₅ , sP ₆ , sP ₇ , sP ₈ and sP ₉ from the fourth design histogram sH ₄ . Then, the fourth design reference point distances sL ₅₆ , sL ₆₇ , sL ₇₈ and sL ₈₉ are calculated as the design value a.

The distances sL _{01 to} sL ₈₉ between the third and fourth design reference points calculated in this way correspond to the design value a.

  The design value a obtained in this way is output to the deformation parameter calculation means 20.

The third and coordinate values of the fourth reference point _sP 0 to SP ₉ read from the third and fourth design histogram sH ₃ and sH ₄ is output to the reference image forming unit 30.

From the observed value calculating unit 112, the third substrate reference point distances mL _{01 to} mL ₃₄ and the fourth substrate reference point distances mL _{56 to} mL ₈₉ are input to the deformation parameter calculating unit 20. . Further, the deformation parameter calculation means 20 is inputted with the third design reference point distances sL _{01 to} sL ₃₄ and the fourth design reference point distances sL _{45 to} sL ₈₉ as the design value a from the calculation value calculation means 212. Is done.

  The deformation parameter calculation means 20 calculates m (distance between third substrate reference points / distance between third design reference points) with respect to the third coordinate axis direction as the deformation parameter A / a, and the fourth coordinate axis direction. With respect to, p pieces (distance between fourth substrate reference points / distance between fourth design reference points) are calculated.

More specifically, deformation parameter calculation means 20, from the storage means, deformation been read out parameter calculation formula, as a modified parameters related coordinate axis X ₂ direction, the third inter-substrate reference point distance and the third design in the corresponding relationship to each other The ratio of the distance between the reference points is calculated. Specifically, the deformation parameter calculation means 20 uses (mL ₀₁ / sL ₀₁ ), (mL ₁₂ / sL ₁₂ ), (mL ₂₃ / sL ₂₃ ), and (mL ₃₄ / sL) as deformation parameters in the coordinate axis X ₂ direction. ₃₄ ) is calculated.

Similarly, the transformation parameter calculation means 20, from the storage means, been read out transformation parameter calculation formula, as a modified parameters related coordinate axis Y ₂ direction, the inter-4 substrate reference point distance, and a fourth design reference point in correspondence with each other The distance ratio is calculated. Specifically, the deformation parameter calculation means 20 uses (sL ₅₆ / mL ₅₆ ), (mL ₆₇ / sL ₆₇ ), (mL ₇₈ / sL ₇₈ ), and (mL ₈₉ / sL) as deformation parameters in the direction of the coordinate axis Y _{2. 89} ) is calculated.

The deformation parameters (mL ₀₁ / sL ₀₁ ) to (mL ₈₉ / sL ₈₉ ) calculated as described above are output to the reference image creation unit 30.

The design image is input from the design image creation unit 204 to the reference image creation unit 30. Further, the deformation parameters (mL ₀₁ / sL ₀₁ ) to (mL ₈₉ / sL ₈₉ ) are input to the reference image creation unit 30 from the deformation parameter calculation unit 20. Further, the coordinate values of the reference points sP _{0 to} sP ₉ of the third and fourth design histograms sH ₃ and sH ₄ are input to the reference image creation unit 30 from the calculation value calculation unit 212.

  For the third coordinate axis direction, the reference image creation means 30 multiplies each of the m (distance between third substrate reference points / distance between third design reference points) by the corresponding third design reference point distance, For the fourth coordinate axis direction, the design image is obtained by multiplying each of the p (distance between the fourth substrate reference points / distance between the fourth design reference points) by the corresponding distance between the fourth design reference points. It has a function of creating a deformed reference image.

More specifically, the reference image forming means 30, as shown in FIG. 10, to set the coordinate axes _{X 2} and _{Y 2} in the design image, the coordinate axes _{X 2} and _{Y 2,} sets a reference point _sP 0 to SP ₉ To do. Then, the reference image creation means 30 multiplies the distances between reference points sL _{01 to} sL ₈₉ by the corresponding deformation parameters (mL ₀₁ / sL ₀₁ ) to (mL ₈₉ / sL ₈₉ ).

Thereby, for example, the area between the reference points sP ₁ and sP ₂ (hatched in the figure) has a width from sL ₁₂ to mL ₁₂ (= sL ₁₂ × (mL ₁₂ / sL ₁₂ )). (Refer to the broken line in the figure). Here, since mL ₁₂ is the width between the reference points mP ₁ and mP ₂ of the board image, the design image matches the board image by applying the deformation parameter (mL ₁₂ / sL ₁₂ ). It turns out that it deform | transforms into.

In this way, the total deformation parameters (mL ₀₁ / sL ₀₁ ) to (mL ₈₉ / sL ₈₉ ) are multiplied by all the reference point distances sL _{01 to} sL ₈₉ , thereby deforming the design according to the distortion of the substrate image. An image, ie a reference image, is created.

  The reference image created in this way is output to the image superimposing means 400.

  The image superimposing means 400 provisionally superimposes the substrate image and the reference image, and has an attribute common to the substrate image and the reference image, and is a substrate related to the position in each of the substrate image and the reference image. The degree of coincidence between the attribute and the reference attribute is calculated while changing the relative positions of the board image and the reference image, and the board image and the reference image are superimposed on the point where the degree of coincidence is maximized.

  More specifically, the image superimposing unit 400 employs, for example, a color distribution as attributes (substrate attributes and reference attributes) common to the substrate image and the reference image.

  The image superimposing unit 400 includes a reference image histogram generating unit 402, a second substrate histogram generating unit 404, a shift amount calculating unit 406, and an image superimposing unit 408.

  The reference image histogram creating means 402 sets a common first orthogonal coordinate system including the first coordinate axis and the second coordinate axis to the reference image in common, and the color of the reference image along each of the first and second coordinate axes. The first and second reference image color distributions as the distributions are created as reference attributes.

  More specifically, a reference image is input from the reference image creation unit 30 to the reference image histogram creation unit 402. The reference image histogram creation means 402 creates a color histogram as a reference attribute from this reference image.

The reference image histogram creating means 402 sets coordinate axes X ₁ and Y ₁ that are orthogonal to each other on the reference image. Here, coordinate axes X ₁ corresponds to the first coordinate axis mentioned above, and coordinate axes Y ₁ corresponds to the second coordinate axis mentioned above. The coordinate system consisting of axes X ₁ and Y ₁ corresponds to the first orthogonal coordinate system.

The reference image histogram creation unit 402 creates the first reference histogram rH ₁ reflecting the specific color of the reference image along the coordinate axis X ₁ direction, similarly to the design histogram creation unit 210. Similarly, the reference image histogram creating unit 402, along the coordinate axis Y ₁ direction, creating a second reference histogram rH ₂ for a specific color.

Here, the first reference histogram rH _{1 corresponds} to the first reference image color distribution, and the second reference histogram rH ₂ corresponds to the second reference image color distribution.

The first and second reference histograms rH ₁ and rH ₂ created in this way are output to the shift amount calculation means 406.

The second substrate histogram creating means 404 sets the same coordinate axes X ₁ and Y ₁ as the reference image to the substrate image, and the first and second color distributions of the substrate image along the first and second coordinate axes, respectively. A two-substrate image color distribution is created as a substrate attribute.

  More specifically, the substrate image is input from the correcting unit 104 to the second substrate histogram creating unit 404. The second substrate histogram creating means 404 creates a color histogram as a substrate attribute from this substrate image.

The second substrate histogram creating means 404, in the same manner as the first substrate histogram creating means 110, along the coordinate axis X ₁ direction, the specific color of the reference image to create a first substrate histogram mH ₁ that is reflected. Similarly, the second substrate histogram creating means 404, along the coordinate axis _{Y 1} direction, creating a second substrate histogram mH ₂ for a specific color.

Here, the first substrate histogram mH _{1 corresponds} to the first substrate image color distribution, and the second substrate histogram mH ₂ corresponds to the second substrate image color distribution.

The first and second substrate histograms mH ₁ and mH ₂ created in this way are output to the shift amount calculation means 406.

The shift amount calculation means 406 determines the overlapping position of the reference image and the substrate image using the first and second reference histograms rH ₁ and rH ₂ and the first and second substrate histograms mH ₁ and mH _2. Has the function of

More specifically, as shown in FIG. 11, the shift amount calculation means 406 provisionally superimposes the first reference histogram rH ₁ and the first substrate histogram mH ₁ on the common coordinate axis X ₁ . On top of that, while calculating a correlation coefficient between the two histograms rH ₁ and mH ₁ (degree of coincidence), (Fig changing the relative positions of both histograms rH ₁ and mH ₁ on the coordinate axes _{X 1,} arrows B). Then, to determine the position where the correlation coefficient is the highest value as the position superposition of the substrate image and the reference image in the coordinate axis X _1.

In the same manner for the axis Y ₁ direction, the second reference histogram rH ₂ and the second substrate histogram mH _2, while calculating a correlation coefficient, is shifted on the coordinate axis Y _1. Then, to determine the position that gives the maximum correlation coefficient as a position superposition of the substrate image and the reference image in the coordinate axis Y _1.

The superposition position in the coordinate axis X ₁ and Y ₁ directions determined in this way is output to the image superposition means 408.

  The image superimposing unit 408 superimposes the substrate image and the reference image at the overlapping position input from the shift amount calculating unit 406. In this way, the inspection image in which the substrate image and the reference image are superimposed is output to the inspection means 70.

  The inspection unit 70 has a function of performing a substrate appearance inspection using the inspected image.

  The inspection unit 70 includes an area feature data extraction unit 72, an inspection unit 74, and a reference feature data storage unit 76.

  Since the configuration and operation of the inspection means 70 are the same as those in the first embodiment, description thereof is omitted.

  Since the configuration and operation of the output unit 80 are the same as those in the first embodiment, description thereof is omitted.

<Effect>
(1) In the board appearance inspection apparatus 12, the deformation parameter calculation means 20 calculates the degree of deformation of the board image obtained by photographing the board with respect to the design image derived from CAD data as the deformation parameter. Then, the reference image creation means 30 creates a reference image obtained by deforming the design image according to the deformation parameter. Thereby, the distortion of a board | substrate image is reflected in the reference image derived from CAD data.

  As a result, even if there is distortion in the board image, the reference image derived from CAD data can be accurately superimposed on the board image. Therefore, it is possible to reduce false information in the substrate appearance inspection.

(2) The board appearance inspection apparatus 12 of this embodiment aligns the reference image and the board image with the first and second board histograms mH ₁ and mH ₂ and the first and second reference histograms rH ₁ and rH. ₂ is used. As a result, the alignment can be performed at a higher speed than the substrate appearance inspection apparatus 10 according to the first embodiment that aligns the reference image and the substrate image using the image itself.
(3) The board appearance inspection apparatus 12 can create a reference image that also reflects the distortion (Embodiment 3) of the board image caused by fluctuations in the conveyance speed of the board S described later.

<Design conditions>
(1) In this embodiment, the coordinate axes _{X 2} and _{Y 2} which substrate observation means 100 and the design value calculating means 200 is set, coordinate axes _{X 1} and _{Y 1} image superimposing unit 400 is set has been described differ .

However, the coordinate axes X ₁ and Y ₁ and the coordinate axes X ₂ and Y ₂ may be shared. With this configuration, the second substrate histogram creation unit 404 can be omitted. In this case, the third and fourth substrate histograms mH ₃ and mH ₄ created by the first substrate histogram creating unit 110 may be input to the shift amount calculating unit 406. Thereby, the structure of the board | substrate visual inspection apparatus 12 can be simplified.

(2) In this embodiment, the substrate image color distribution (first and second substrate histograms mH ₁ and mH ₂ ) as the substrate attribute, and the reference image color distribution (first and second reference histograms) as the reference attribute. The case where the substrate image and the reference image are superimposed using rH ₁ and rH ₂ ) has been described.

  However, the board attribute and the reference attribute are not limited to the color distribution, and may be, for example, the shape of a specific component arranged on the board as in the first embodiment.

  (3) In this embodiment, the case where the reference image is created by deformation of the design image has been described. However, the reference image may be created by deforming the board image according to the design image.

(Embodiment 3)
With reference to FIGS. 12-14, the board | substrate external appearance inspection apparatus of Embodiment 3 is demonstrated.

<Deformation of substrate image due to change in conveyance speed>
First, with reference to FIG. 12, a mechanism for deforming a substrate image due to a change in the conveyance speed of the substrate S will be described. FIG. 12A is a schematic diagram for explaining a substrate image obtained when the substrate transport speed is low. FIG. 12B is a schematic diagram for explaining a substrate image obtained when the substrate conveyance speed is high.

  12A and 12B, S indicates a substrate. For convenience, the substrate S is divided into regions A to G arranged in series along the transport direction. LS indicates a line sensor. The line sensor LS is fixed above the substrate S. An imaging region of the line sensor LS is indicated by a triangular region extending from the line sensor LS in the substrate S direction. Further, the photographing time interval of the line sensor LS (hereinafter also referred to as “shutter interval”) is Δt.

  In FIG. 12A, the line sensor LS images the area A of the substrate S that is transported at the transport speed v1 at time t. After that, the line sensor LS captures the substrate S again at time t + Δt when the shutter interval Δt has elapsed.

  As shown in FIG. 12A, when the transport speed is low, the line sensor LS images the region B of the substrate S at time t + Δt. Thereafter, the entire length of the substrate S is imaged in the same manner. As a result, as shown in the figure, the obtained substrate image includes all regions A to G of the substrate S.

  On the other hand, as shown in FIG. 12B, when the substrate transport speed v2 (> v1) is fast, after the area A of the substrate S is imaged at time t, until the next image capturing time t + Δt. In addition, the substrate S is transported for a long distance. As a result, at time t + Δt, for example, the region D is photographed by the line sensor LS. Thereafter, the entire length of the substrate S is imaged in the same manner. As a result, as shown in the drawing, the obtained substrate image is an image in which the regions A, D, and G are arranged in series.

  That is, when the transport speed of the substrate S is fast (FIG. 12B), not all the regions A to G of the substrate S are photographed, but the regions are photographed in succession. As a result, the substrate images (A, D, G) obtained when the transport speed of the substrate S is fast are the substrate images (A, B, C, D, E, F, G) obtained when the transport speed is slow. As compared with the above, the length along the transport direction of the substrate S becomes shorter.

  From the same discussion, it can be said that when the transport speed of the substrate S is slow, the length along the transport direction of the substrate image becomes longer.

<Configuration and operation of substrate visual inspection apparatus>
Hereinafter, the configuration and operation of the substrate appearance inspection apparatus according to the third embodiment will be described with reference to FIG. FIG. 13 is a block diagram of the board appearance inspection apparatus.

  Referring to FIG. 13, the board appearance inspection apparatus 14 includes an imaging unit 102, an actual conveyance speed measurement unit 114, a board observation unit 100, a design value calculation unit 200, a deformation parameter calculation unit 20, and a reference image creation unit. 30 and an image superimposing means 400. Furthermore, the board appearance inspection apparatus 10 includes a CAD data storage unit 50, an inspection unit 70, and an output unit 80.

  Of these components, the remaining units other than the photographing unit 102, the actual conveyance speed measuring unit 114, and the output unit 80 are configured as computer functional units. Similarly to the first embodiment, the board appearance inspection apparatus 14 includes a storage unit and an input unit (not shown).

  Hereinafter, the configuration and operation of each functional unit described above will be described in detail.

  Since the configuration and operation of the imaging unit 102 are the same as those in Embodiment 1, the description thereof is omitted.

  The actual transport speed measuring unit 114 measures the actual transport speed V (d) at the position d along the transport direction of the substrate transported on the stage T.

More specifically, the actual transport speed V (d) of the substrate S is not strictly constant and fluctuates around the set value (set transport speed V ₀ ) due to various external factors. The actual transport speed measuring unit 114 measures and stores the magnitude of the fluctuation of the actual transport speed V (d) together with the position d along the transport direction of the substrate S.

  The actual conveyance speed V (d) measured in this way is output to the deformation parameter calculation means 20 together with the position d.

  Since the configuration and operation of the correcting unit 104 of the substrate observing unit 100 are the same as those in the first embodiment, description thereof is omitted.

  The board image created by the correcting unit 104 is output to the second board histogram creating unit 404.

  Since the configuration and operation of the CAD data reading unit 202 and the design image creating unit 204 of the design value calculating unit 200 are the same as those in the first embodiment, the description thereof is omitted. The design image created by the design image creation unit 204 is output to the reference image creation unit 30.

The set speed reading means 214 is connected to a transport device (not shown) for the substrate S, and reads a preset transport speed V ₀ for the substrate S from the transport device. The set conveyance speed V ₀ read in this way is output to the deformation parameter calculation means 20.

The deformation parameter calculation means 20 calculates (V (d) / V ₀ ) at the position coordinate d of the substrate S as the deformation parameter.

More specifically, the actual conveyance speed V (d) is input from the actual conveyance speed measurement unit 114 to the deformation parameter calculation unit 20. Further, the set conveyance speed V ₀ is input from the set speed reading means 214 to the deformation parameter calculating means 20.

The deformation parameter calculation means 20 calculates a deformation parameter (V (d) / V ₀ ) from the actual transport speed V (d) and the set transport speed V ₀ and creates a graph as shown in FIG.

FIG. 14 is a diagram illustrating the relationship between the deformation parameter (V (d) / V ₀ ) and the position d of the substrate S. In FIG. 14, the horizontal axis represents position coordinates d measured along the transport direction of the substrate S. The vertical axis indicates the value of the deformation parameter, that is, the ratio (V (d) / V ₀ ) of the actual transport speed V (d) to the set transport speed V ₀ .

In FIG. 14, the vertical axis indicates “1”, which indicates that V (d) = V ₀ . In the region where the vertical axis exceeds 1, V (d)> V ₀ , that is, the actual conveyance speed is greater than the set conveyance speed. Conversely, in the region where the vertical axis is less than 1, V (d) <V ₀ , that is, the actual transport speed is lower than the set transport speed.

The deformation parameter (V (d) / V ₀ ) calculated in this way is output to the reference image creation means 30.

The reference image creating means 30 divides the length along the transport direction of the design image at a position corresponding to the position coordinate d of the design image with (V (d) / V ₀ ) as the deformation parameter A / a. Thus, a reference image obtained by deforming the design image is created.

More specifically, the deformation parameter (V (d) / V ₀ ) is input from the deformation parameter calculation unit 20 and the design image is input from the design image generation unit 204 to the reference image generation unit 30.

  As already described in the section (deformation of substrate image due to variation in conveyance speed), the substrate image partially expands and contracts along the conveyance direction due to fluctuations in the actual conveyance speed V (d) of the substrate S. The reference image creation means 30 deforms the design image according to the expansion / contraction of the board image.

Specifically, the reference image creation means 30 uses the deformation parameter (V (d) / V ₀ ) as the length along the transport direction of the design image at the position of the design image corresponding to the position coordinate d of the substrate S. Divide.

Thus, the length along the transport direction is shortened at a point where the transport speed of the substrate S is high (V (d) / V ₀ > 1), that is, at a point where the substrate image is shortened in the transport direction. In addition, the design image is deformed.

Conversely, at the point where the transport speed of the substrate S is slow (V (d) / V ₀ <1), that is, the point where the substrate image extends in the transport direction, the length along the transport direction seems to expand. In addition, the design image is deformed.

  As a result, a design image deformed according to the deformation of the substrate image, that is, a reference image is obtained.

  The reference image obtained in this way is output to the image superimposing means 400.

  Since the configuration and operation of the image superimposing means 400 are the same as those in the second embodiment, description thereof is omitted.

  Moreover, since the structure and operation | movement of the test | inspection means 70 and the output part 80 are the same as that of Embodiment 1, the description is abbreviate | omitted.

<Effect>
(1) In the board appearance inspection apparatus 14, the deformation parameter calculation means 20 calculates the degree of deformation of the board image obtained by photographing the board with respect to the design image derived from CAD data as the deformation parameter. Then, the reference image creation means 30 creates a reference image obtained by deforming the design image according to the deformation parameter. Thereby, the distortion of a board | substrate image is reflected in the reference image derived from CAD data.

  As a result, even if there is distortion in the board image, the reference image derived from CAD data can be accurately superimposed on the board image. Therefore, it is possible to reduce false information in the substrate appearance inspection.

<Design conditions>
(1) In this embodiment, the case where the reference image is created by deformation of the design image has been described. However, the reference image may be created by deforming the board image according to the design image.

The photograph of the partial area | region of the board | substrate S surface image | photographed by the board | substrate external appearance inspection apparatus is shown. 1 is a block diagram of a substrate appearance inspection apparatus according to a first embodiment. FIG. 6A is a schematic plan view of a substrate image used for explanation of calculation of an observation value in the first embodiment. FIG. 6B is a schematic plan view of a design image used for explanation of calculation of design values in the first embodiment. 6 is a schematic diagram for explaining the creation of a reference image according to Embodiment 1. FIG. 6 is a schematic diagram for explaining an operation for determining an overlapping position between a reference image and a substrate image in the first embodiment. FIG. (A) And (B) is a schematic diagram with which it uses for description of the determination operation | movement of the superimposition position of the reference image and board | substrate image in Embodiment 1. FIG. FIG. 6 is a block diagram of a substrate appearance inspection apparatus according to a second embodiment. In Embodiment 2, it is a schematic diagram which shows a board | substrate image with a color histogram (color distribution). In Embodiment 2, it is a schematic diagram which shows a design image with a color histogram. In Embodiment 2, it is a schematic diagram with which it uses for operation | movement description of a reference image preparation means. In Embodiment 2, it is a schematic diagram with which it uses for operation | movement description of the shift amount calculation means. (A) is a schematic diagram for explanation of a substrate image obtained when the substrate transport speed is slow in the third embodiment. (B) is a schematic diagram used for description of a substrate image obtained when the substrate conveyance speed is high. FIG. 10 is a block diagram of a substrate appearance inspection apparatus according to a third embodiment. FIG. 10 is a diagram illustrating a relationship between a deformation parameter and a position of a substrate S in the third embodiment.

Explanation of symbols

10, 12, 14 Substrate visual inspection device 20 Deformation parameter calculation means 30 Reference image creation means 40, 400 Image superimposition means 402 Reference image histogram creation means 404 Second substrate histogram creation means 406 Shift amount calculation means 408 Image superposition means 50 CAD Data storage means 52 Reference area storage section 54 Color data by layer 70 Inspection means 72 Area feature data extraction means 74 Inspection section 76 Reference feature data storage means 80 Output section 100 Substrate observation means 102 Imaging section 104 Correction means 106 Substrate reference area extraction means 108, 112 Observation value calculation means 110 First substrate histogram creation means 114 Actual transport speed measurement means 200 Design value calculation means 202 CAD data reading means 204 Design image creation means 206 Design reference area extraction means 208, 212 Calculation value calculation means 2 10 Design histogram creating means 214 Setting speed reading means

Claims (9)

A board visual inspection apparatus using a computer,
Board observation means for obtaining an observation value A that reflects the deformation of the board image caused by an internal factor or an external factor, which is observation data relating to a physical quantity of a board image that is a captured board image;
A design value calculating means for obtaining a design value a corresponding to the observed value A with respect to a design image created by reading out CAD data for designing the substrate from a storage means;
Deformation parameter calculation means for calculating a deformation parameter given by A / a;
Reference image creating means for creating a reference image that is a deformed image of the design image by applying the deformation parameter to the design value a;
The board image and the reference image are temporarily overlapped, and the board has an attribute common to the board image and the reference image, and is related to the position in each of the board image and the reference image The degree of coincidence between the attribute and the reference attribute is calculated while changing the relative positions of the board image and the reference image, and image superposition is performed to superimpose the board image and the reference image at a point where the degree of coincidence is maximized. And a substrate visual inspection apparatus.   The board attribute is a shape of a specific part arranged on the board image, and the reference attribute is a shape of a part corresponding to the specific part arranged on the reference image. Item 1. A substrate visual inspection apparatus according to Item 1. A first orthogonal coordinate system including a first coordinate axis and a second coordinate axis is commonly set for the substrate image and the reference image,
The board attribute is a first and second board image color distribution as a color distribution of the board image along each of the first and second coordinate axes, and the reference attribute is a first and second coordinate axis. The board visual inspection apparatus according to claim 1, wherein first and second reference image color distributions as color distributions of the reference image along each of the first and second reference image color distributions are provided. Set three or more common reference areas for each of the substrate image and the design image;
The substrate observation means uses the first substrate distance to the nth substrate distance (n is an integer of 3 or more) as the distance between the reference regions in the substrate image as the observation value A,
The design value calculation means respectively sets a first design distance to an nth design distance as a distance between the reference regions in the design image as the design value a.
The deformation parameter calculation means calculates (first substrate distance / first design distance) to (nth substrate distance / nth design distance) as the deformation parameter A / a,
The reference image creating means uses (first substrate distance / first design distance) to (nth substrate distance / nth design distance) as the deformation parameter A / a as a first design distance as the design value a. The substrate appearance inspection apparatus according to claim 1, wherein the reference image is created by multiplying each of the nth design distance. A second orthogonal coordinate system including a third coordinate axis and a fourth coordinate axis is commonly set in the substrate image and the design image;
The substrate observation means includes
The coordinates of one end and the other end of the substrate image along the third coordinate axis direction and the peak coordinates in the color distribution of the substrate image along the third coordinate axis direction are set as first reference points, respectively. M (m is an integer of 1 or more) third substrate reference point distances as distances between adjacent first reference points, and
The coordinates of one end and the other end of the substrate image along the fourth coordinate axis direction and the peak coordinates in the color distribution of the substrate image along the fourth coordinate axis direction are set as second reference points, respectively. Both of p (p is an integer of 1 or more) fourth substrate reference point distances as the distance between adjacent second reference points are the observed values A,
The design value calculation means includes
The coordinates of one end and the other end of the design image along the third coordinate axis direction and the peak coordinates in the color distribution of the design image along the third coordinate axis direction are set as third reference points, respectively. M distances between third design reference points as distances between adjacent third reference points, and
The coordinates of one end and the other end of the design image along the fourth coordinate axis direction and the peak coordinates in the color distribution of the design image along the fourth coordinate axis direction are respectively set as fourth reference points, Both of the p fourth design reference point distances as the distance between the adjacent fourth reference points are set as the design value a,
The deformation parameter calculation means calculates m (distance between third substrate reference points / distance between third design reference points) for the third coordinate axis direction as the deformation parameter A / a; and For the four coordinate axis directions, p (distance between fourth substrate reference points / distance between fourth design reference points) is calculated,
The reference image creating means includes
With respect to the third coordinate axis direction, each of the m (distance between third substrate reference points / distance between third design reference points) is multiplied by the corresponding distance between the third design reference points, and
For the fourth coordinate axis direction, by multiplying each of the p (distance between fourth substrate reference points / distance between fourth design reference points) by the corresponding distance between the fourth design reference points,
The substrate visual inspection apparatus according to claim 1, wherein the reference image is created. An image obtained by photographing the substrate transported at a preset transport speed V ₀ with a line sensor is used as the substrate image.
The substrate observing means uses an actual transport speed V (d) at a position coordinate d along the transport direction of the substrate as the observed value A,
The design value calculation means uses the set conveyance speed V ₀ as the design value a related to the design image,
The deformation parameter calculation means uses (V (d) / V ₀ ) at the position coordinate d of the substrate as a deformation parameter A / a.
The reference image creating means is (V (d) / V ₀ ) as the deformation parameter A / a at a position corresponding to the position coordinate d of the design image along the transport direction of the design image. The substrate visual inspection apparatus according to claim 1, wherein the reference image is created by dividing a length. A common reference area of three or more points is set for each of the board image and the design image,
The substrate observation means uses the first substrate distance to the nth substrate distance (n is an integer of 3 or more) as the distance between the reference regions in the substrate image as the observation value A,
The design value calculating means sets the first design distance to the nth design distance as the distance between the reference regions in the design image as the design value a.
The deformation parameter calculation means calculates a simple average of (first substrate distance / first design distance) to (nth substrate distance / nth design distance) as the deformation parameter A / a,
The reference image creating means creates the reference image by multiplying the simple average as the deformation parameter A / a by a first design distance to an nth design distance as the design value a, respectively. The board | substrate visual inspection apparatus as described in any one of Claims 1-3.   The reference image creating means calculates the simple average by excluding abnormal values from (first substrate distance / first design distance) to (nth substrate distance / nth design distance). The board | substrate external appearance inspection apparatus of Claim 7. A board visual inspection apparatus using a computer,
Board observation means for obtaining an observation value A that reflects the deformation of the board image caused by an internal factor or an external factor, which is observation data relating to a physical quantity of a board image that is a captured board image;
Design value calculating means for calculating a design value a corresponding to the observed value A from a design image created by reading CAD data for designing the substrate from the storage means;
deformation parameter calculating means for calculating a deformation parameter given by a / A;
A reference image creation means for transforming the substrate image into a reference image by multiplying the observed parameter A by the deformation parameter;
The reference image and the design image are temporarily overlapped, and are attributes common to the reference image and the design image, and the reference is related to the position in each of the reference image and the design image Image superimposition that calculates the degree of coincidence between the attribute and the design attribute while changing the relative position of the reference image and the design image, and superimposes the reference image and the design image at a point where the degree of coincidence is maximized And a substrate visual inspection apparatus.