JP2013011569A - Displacement amount identification device, displacement amount identification method, and displacement amount identification program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of easily detecting warpage of a substrate.SOLUTION: A displacement amount identification device: selects a reference pad for detecting warpage of a substrate from pads for mounting electronic components on the substrate; acquires an image including a reference pad image that is photographed with a camera of which optical axis is oriented in the direction inclined with respect to a reference plane that is a surface of the substrate when no warpage is generated therein; and identifies the amount of the warpage of the substrate in the direction perpendicular to the reference plane on the basis of a position of the reference pad image within the image, and the reference position that is a position of the reference pad image within the image when no warpage is generated in the substrate.

Description

  The present invention relates to a displacement amount specifying device, a displacement amount specifying method, and a displacement amount specifying program.

  Conventionally, an appearance inspection of a substrate is performed by a perspective camera arranged so that an optical axis is oblique with respect to a reference plane which is a surface of the substrate when the substrate is not warped. The substrate to be inspected may be warped due to the temperature in the reflow furnace, the weight and density of electronic components mounted on the substrate, the force acting on the substrate by the substrate support means, etc. Since the inspection target part is photographed in a state where the optical axis is inclined with respect to the reference plane, it is difficult to specify the position of the inspection target part when the substrate is warped.

  Therefore, as a technique for correcting the positional deviation due to the warpage of the substrate, for example, as in Patent Document 1, the position of the laser light irradiated from the direction of being oblique with respect to the reference plane is set so that the optical axis is perpendicular to the reference plane. A technique is known in which the amount of positional deviation of a substrate is measured by observing with a camera set to, and the relative height relationship between the substrate and the camera is corrected by the amount of positional deviation.

JP 2004-198129 A

  However, in the case of the above-mentioned Patent Document 1, it is necessary to separately provide a device for irradiating a laser beam for measuring the warpage of the substrate, leading to an increase in the cost of the equipment. In addition, since a space for arranging a device for measuring the amount of positional deviation such as a laser beam irradiation device is required separately, there may be restrictions on the arrangement of the camera, illumination, and the like.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a technique capable of easily detecting a warp of a substrate.

  In order to achieve the above object, in the present invention, a reference pad for detecting warpage of a substrate is selected from pads for mounting electronic components on the substrate, and an image of the reference pad taken by a perspective camera is selected. Is obtained, and is perpendicular to the reference plane based on the position of the reference pad image in the image and the reference position, which is the position of the reference pad image in the image when the substrate is not warped. The amount of warpage of the substrate in a specific direction is specified. That is, the warpage of the substrate is detected based on the reference pad selected from the pads for mounting the electronic component on the substrate.

  Thus, in the present invention, warpage can be detected based on an image acquired by a perspective camera, and the perspective camera can be used when inspecting the inspection target part as described above. Therefore, the detection and inspection of the warp can be performed by a common perspective camera, and there is no need to provide a dedicated camera or laser light irradiation device for the detection of the warp. Restrictions on the arrangement of lighting and the like can be suppressed. Further, an electronic component is usually mounted on the substrate, and a normal substrate always includes a pad for mounting the electronic component. Therefore, there is no need to provide a mark or the like as a reference for detecting the warpage of the substrate, and a highly versatile technique can be provided.

  Here, the reference pad selection means only needs to be able to select the reference pad from among the pads provided on the substrate, and may select from design data related to the substrate and electronic components, or an image taken by the camera. The reference pad may be selected based on the included pad image. The pad is generally a part provided on the surface of the substrate as a part of a conductive wiring pattern such as copper, and an electronic component such as a resistance element is soldered to the pad.

  Then, the reference pad is selected from the pads in order to detect the warpage of the substrate. Therefore, the reference pad may be any pad that can specify the warp of the substrate from the difference between the position of the reference pad image in the image and the reference position, and specifies the position of the reference pad image in the image. A pad that is easy to be used may be used as a reference pad.

  The reference pad need only be able to be specified directly or indirectly according to a predetermined rule. As the former, the reference pad itself is specified based on the size and shape of the reference pad, characteristics in the image, etc. Can be assumed. As the latter, it is possible to assume a configuration in which the reference pad is specified based on the size and shape of a component mounted on the reference pad, the amount of solder to be soldered to the reference pad, and the like.

  The image acquisition means obtains an image of a reference pad photographed by a camera in which the optical axis is oriented in a direction inclined with respect to a reference plane which is the surface of the substrate when the substrate is not warped, that is, a perspective camera. What is necessary is just to be able to acquire the image containing. Here, the position of the reference pad is specified before shooting with the perspective camera, and an image including the image of the reference pad may be acquired by shooting the position of the reference pad. The configuration may be such that a portion including the image of the reference pad is identified from the image captured in step S1, and the identified portion is acquired as an image including the image of the reference pad.

  The warp amount specifying means only needs to be able to specify the amount of warpage of the substrate based on the position in the image of the image of the reference pad and the reference position. In other words, since the design position of the reference pad is determined in advance at the design stage of the board, the board in which no warp has occurred based on the design position of the reference pad is taken in the image when the camera is photographed by the perspective camera. The ideal position of the reference pad is identified. Therefore, if the position of the image of the reference pad in the image when the reference pad existing at the ideal position is photographed is defined as the reference position, the image of the image of the reference pad and the image of the reference pad actually photographed. By considering that the difference from the position in the substrate is caused by the warpage of the substrate, the amount of warpage of the substrate in the reference pad portion can be specified. Of course, if the amount of warpage of the substrate in the reference pad portion is specified, the amount of warpage of an arbitrary part on the substrate can be estimated based on the amount of warpage.

  In the warp amount specifying means, the position of the image of the reference pad in the image is specified in the process of specifying the amount of warpage, but there are various methods for specifying the position of the image of the reference pad in the image. This method can be adopted. For example, the position of the reference pad image in the image can be specified by specifying the feature amount of the reference pad image. As the feature amount, for example, the edge of the reference pad image is used. It can be assumed.

  That is, on the surface of the substrate, the pads and portions other than the pads are different in color and material, and the luminance changes greatly particularly at the boundary between the pads. Further, the shape of the pad is determined at the design stage of the substrate. Therefore, if the edge of the image of the reference pad is detected, the position of the image of the reference pad in the image can be specified by the position of the edge in the image. For example, a configuration in which the position in the image of the edge is regarded as a position in the image of the reference pad image or a configuration in which a position having a predetermined relationship with the edge is regarded as a position in the image of the reference pad image can be adopted. It is.

  As a method for detecting an edge, various methods can be employed. For example, a method for detecting an edge by a Sobel filter, a Prewitt filter, or the like can be employed. Of course, in order to improve the accuracy when detecting edges, it is configured to extract edges across multiple pixels, or to detect edges that are oriented parallel to the direction in which the pixels of the imaging element are aligned Etc. may be adopted. As the former, a cumulative value of luminance is calculated for a plurality of pixels arranged in a predetermined direction in an image, a change in the cumulative value along a direction perpendicular to the predetermined direction is analyzed, and the cumulative value is rapidly (predetermined value). As described above, a configuration may be adopted in which the changing position is the position in the edge image.

  Furthermore, in order to specify the position accurately, it is preferable that the reference pad is large. Further, the more easily the edge of the reference pad can be detected, the more easily the position of the edge in the image can be specified. Therefore, it is preferable to adopt a configuration in which a pad having a predetermined size or more is used as a candidate pad as a reference pad candidate, and a candidate pad that does not have an element that inhibits edge detection is selected as a reference pad.

  That is, by using a pad having a predetermined size or more as a candidate pad, the size of an image forming an edge is increased, and the statistical accuracy at the time of edge detection can be improved. Further, a pad having a predetermined size or more is less likely to be covered with solder than the other pads, and an edge corresponding to the boundary of the pad can be detected with high probability. Therefore, an edge can be accurately detected by using a pad having a predetermined size or more as a candidate pad. Of course, the predetermined size as a condition for defining the candidate pad may be defined for the size of the pad itself or for the size of a part of the pad (for example, an edge portion). Also good.

  Furthermore, by selecting a candidate pad that does not have an element that hinders edge detection in the surrounding area, a pad that can detect an edge more accurately can be used as a reference pad. Here, the element that hinders edge detection is an element that makes edge detection impossible or an element that makes edge detection difficult, and the element exists around each candidate pad. It is determined whether or not.

  Examples of the element include electronic components around candidate pads, silk printing, wiring extending from the pads, insulating resin (such as a green mask) on the substrate surface, and a structure formed on the substrate. More specifically, when there is an electronic component that intersects a straight line connecting the candidate pad and the imaging element of the perspective camera around the candidate pad, the electronic component is referred to as an “element that inhibits edge detection”. It is possible to adopt a configuration to That is, when there is an electronic component that hinders the photographing of the candidate pad in the field of view of the perspective camera and the candidate pad becomes a shadow of the electronic component, the electronic component is set as an “element that inhibits edge detection”. According to this configuration, it is possible to extract a shootable pad from candidate pads and use it as a reference pad.

  Of course, when there is a high possibility that the electronic component inhibits the photographing of the candidate pad, a configuration in which such an electronic component is used as an “element that inhibits edge detection” may be employed. For example, when electronic components exist at a density equal to or higher than a predetermined value within a predetermined distance around the candidate pad, such an electronic component is set as an “element that hinders edge detection”. Of course, when electronic components of a predetermined size or more exist with a density of a predetermined value or more within a predetermined distance around the candidate pad, such an electronic component is set as an element that hinders edge detection. Also good.

  Further, when silk printing is present on a substrate within a predetermined distance from the candidate pad, it is possible to adopt a configuration in which the silk printing is used as an “element that hinders edge detection”. That is, since the silk-printed image on the substrate has a high luminance, it is difficult to distinguish it from the edge formed by the image of the reference pad. Therefore, if the silk print existing on the substrate within a predetermined distance from the candidate pad is set as an “element that hinders edge detection”, erroneous determination that the silk print portion other than the pad is regarded as a reference pad can be prevented. Can do.

  Further, when there is a wiring pattern extending from a portion corresponding to the edge of the candidate pad, it is possible to adopt a configuration in which the wiring pattern is an “element that hinders edge detection”. That is, if the wiring pattern extends from the portion corresponding to the edge, the effective length of the edge is shortened and it is difficult to detect the edge. Therefore, when there is a wiring pattern extending from a portion corresponding to the edge of the candidate pad, if the wiring pattern is set as an “element that hinders edge detection”, the candidate pad whose edge detection accuracy is likely to decrease is used as a reference pad. The selection can be prevented.

  The wiring pattern extending from the portion corresponding to the edge of the candidate pad may or may not be covered with an insulating resin (green mask or the like) formed on the substrate surface. Here, one of them may be an “element that inhibits edge detection”, or both may be “an element that inhibits edge detection”.

  Furthermore, when a structure such as a through hole is formed within a predetermined distance from the candidate pad, a configuration in which the structure is an “element that hinders edge detection” may be employed. That is, the structure formed on the substrate often includes a portion with a large luminance change, and is difficult to distinguish from the edge formed by the image of the reference pad. Therefore, when a structure such as a through hole is formed within a predetermined distance from the candidate pad, if the structure is used as an element that inhibits edge detection, the structure other than the pad is used as a reference pad. It is possible to prevent misjudgment that is considered to be.

  Further, the number of reference pads selected from the candidate pads is not limited. For example, a configuration in which two reference pads are used for one inspection target part or one inspection target part is provided at one place. A configuration using a reference pad can be employed. As a more specific application example, two parallel sides of the substrate are supported, and the camera and the camera are moved relative to each other in a direction parallel to the reference plane so that the camera can move an arbitrary position on the substrate surface. An example of application to a configuration in which an image is taken and an inspection is performed based on the taken image is given. That is, a configuration in which a substrate inspection is performed by moving in a plane with two parallel sides of the substrate clamped is an application example.

  In this configuration, on the substrate based on the reference pad closest to the inspection target portion on one side in the direction parallel to the two sides and the reference pad closest to the inspection target portion on the other side in the direction parallel to the two sides. A configuration in which the amount of warpage in the inspection target portion is specified can be adopted. That is, the amount of warpage in the inspection target portion is specified based on the reference pad that sandwiches the inspection target portion from both sides along the direction parallel to the two sides of the substrate and is closest to the inspection target portion. When the two sides of the substrate are supported, the position (height) in the direction perpendicular to the reference plane of the supported part can be regarded as constant. Therefore, if the height of the substrate at the position of each reference pad is specified, the height of the inspection target part sandwiched between the reference pads by performing an interpolation process based on the position of the reference pad and the height of the supported part. Can be specified. And by using the reference pad which pinches | interposes an inspection object part from both sides, the height of an inspection object part can be specified by interpolation, and it is possible to specify the height of an inspection object part correctly. .

  Furthermore, two parallel sides of the substrate are supported, and the substrate and the camera move relative to each other in a direction parallel to the reference plane so that an arbitrary position on the substrate surface is photographed by the camera. In the configuration for performing the inspection, a configuration may be adopted in which the amount of warpage in the inspection target portion on the substrate is specified based on the reference pad closest to the inspection target portion. That is, in a configuration that supports two parallel sides of the substrate, the amount of warpage of the substrate changes greatly in the direction perpendicular to the two sides, but the amount of warpage changes greatly in the direction parallel to the two sides. Absent. Therefore, if the height of the substrate at the position of the reference pad closest to the inspection target portion is specified, interpolation processing is performed based on the position of the reference pad and the height of the supported part, so that the direction in the direction perpendicular to the two sides is determined. The height of the substrate can be specified, and the height of the inspection target part can be specified by assuming that there is no change in height in the direction parallel to the two sides.

It is a schematic block diagram which shows the board | substrate external appearance inspection apparatus containing the displacement amount specific device concerning this embodiment. (2A) is a view of the substrate viewed from the side, and (2B) is a view of the substrate viewed from the top. It is a flowchart which shows a reference | standard pad selection process. It is a figure which shows the example of a board | substrate. It is a flowchart which shows a board | substrate external appearance inspection process. (6A) is a diagram showing a function for specifying the amount of warpage of the substrate, (6B) is a diagram showing a perspective image for warping specification, and (6C) is a diagram showing edge detection.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of substrate visual inspection apparatus:
(2) Reference pad selection processing:
(3) Board appearance inspection processing:
(4) Other embodiments:

(1) Configuration of substrate visual inspection apparatus:
FIG. 1 shows a schematic configuration of a substrate visual inspection apparatus including a displacement amount specifying device according to the present embodiment. In FIG. 1, the board appearance inspection apparatus 1 includes an imaging unit 10, a control unit 20, and a display unit 30. The imaging unit 10 captures an image of the substrate 50 illustrated in FIGS. 2A and 2B to be inspected, and outputs the image to the control unit 20. The control unit 20 inputs a photographed image and analyzes the photographed image, thereby inspecting the external appearance of electronic components such as chip components on the substrate 50 to be inspected and their soldered portions. Further, the control unit 20 specifies the amount of warpage of the substrate 50 based on the image acquired by the imaging unit 10, and corrects the positional deviation on the image of the inspection target portion caused by the warpage. The display unit 30 can display the acquired image and various data generated in the course of the substrate appearance inspection process.

  As shown in FIGS. 1, 2A, and 2B, the imaging unit 10 performs planar movement of the perspective camera 11a and the direct-view camera 11b, the guide rail 12 that supports the substrate 50, and the substrate 50 that is supported by the guide rail 12. -Y stage 13. The imaging unit 10 is controlled by the control unit 20.

  The guide rail 12 is fixed to the XY stage 13, and positions the substrate 50 transported from a transport device (not shown) with respect to the XY stage 13 and clamps two parallel sides facing each other. And support. The two parallel sides of the substrate 50 supported in this manner serve as a reference when calculating the positional deviation amount described later.

  The XY stage 13 moves the substrate 50 fixed by the guide rail 12 within a predetermined plane. Therefore, the upper surface of the substrate 50 when the substrate 50 is not warped as shown by the dashed line in FIG. 2A is parallel to a predetermined plane on which the substrate 50 moves. In the present embodiment, the upper surface of the substrate 50 is referred to as a reference plane Fs.

  The perspective camera 11a is disposed so that its optical axis is oblique with respect to the reference plane Fs by a predetermined angle θ ° (θ ≠ 0 °, 90 °). In the present embodiment, an image of the substrate 50 taken by the perspective camera 11a is referred to as a perspective image. The number of perspective cameras 11a is not limited, but the board appearance inspection apparatus according to this embodiment includes four perspective cameras 11a. Further, the perspective cameras 11a are arranged so that the optical axes of the respective perspective cameras 11a intersect at one point on the reference plane Fs. Further, assuming a projection straight line obtained by projecting the optical axis of each perspective camera 11a onto the reference plane Fs, the projection straight lines related to the two perspective cameras 11a overlap and are parallel to the Y axis, and the other two perspective cameras 11a. And the projection straight lines overlap and are parallel to the X axis. FIG. 2A illustrates one perspective camera 11a in which the projected straight line is parallel to the Y axis.

  The direct-view camera 11b is arranged so that its optical axis is parallel to a direction perpendicular to the reference plane Fs. In this embodiment, the image of the board | substrate 50 image | photographed with the direct view camera 11b is called a direct view image.

  In the present embodiment, the perspective camera 11 a and the direct-view camera 11 b are fixed to the board appearance inspection apparatus 1. Therefore, in the present embodiment, the relative position between the substrate 50 and the perspective camera 11a is changed by moving the XY stage 13 in the plane in the XY (horizontal) direction. As a configuration for changing the relative position between the substrate 50 and the perspective camera 11a, for example, the perspective camera 11a is moved in a plane parallel to the reference plane Fs so as to fix the position of the substrate 50. The means, the substrate 50, and the perspective camera 11a may be configured to move in a plane parallel to the reference plane Fs.

  Here, in the present embodiment, as shown in FIG. 2A, the direction from one side of the guide rail 12 to the other is the Y direction, and the direction parallel to the reference plane orthogonal to the Y direction is the X direction as shown in FIG. 2B. Let's say. A direction (height direction) perpendicular to the X direction and the Y direction is referred to as a Z direction. Since the substrate 50 in this embodiment is supported by the guide rails 12 at both ends in the Y direction, when warping occurs, the warping amount changes in the positive direction or the negative direction in the Z direction shown in FIG. 2A. .

  As shown in FIG. 1, the control unit 20 includes a camera control unit 21, a guide rail control unit 22, a stage control unit 23, a CPU 24, a memory 25, and an output unit 26. The CPU 24 can execute various programs recorded in the memory 25. In the present embodiment, a board appearance inspection program 25a is recorded in the memory 25. The board appearance inspection program 25a is a program for causing the CPU 24 to realize a function of executing an appearance inspection of the inspection target portion based on an image obtained by photographing the board 50 with the perspective camera 11a and the direct-view camera 11b. The recorded board data 25b, electronic component data 25c, reference table 25d, and the photographed image data 25e and coordinate correction data 25f recorded in the memory 25 in the course of the appearance inspection process are used for the inspection target portion on the board 50. Perform visual inspection.

  The board data 25b is design information of the board 50, a part code for designating an electronic component mounted on the board 50, a position where the electronic component is mounted, a direction in which the electronic component is mounted, and a surface above the board 50. Information indicating the position of silk printing and the position of the wiring pattern is included. Of course, information such as circuit symbols of parts may be included. The electronic component data 25c is information in which an inspection method and a pass / fail judgment condition are associated with each of a plurality of electronic components. The comparison table 25d is information indicating a correspondence relationship between the component code indicated by the board data 25b and the electronic component indicated by the electronic component data 25c, and the CPU 24 refers to the comparison table 25d so that each electronic component indicated by the board data 25b is indicated. It is possible to specify an inspection method and pass / fail judgment conditions for a part. In the present embodiment, the inspection method and the pass / fail determination conditions are defined for each of the direct-view image and the perspective image. That is, an inspection method and pass / fail judgment conditions for a direct-view image captured by the direct-view camera 11b, and an inspection method and pass / fail judgment conditions for a perspective image captured by the perspective camera 11a are defined.

  The captured image data 25e is data of an image captured by the direct view camera 11b and the perspective camera 11a. That is, the CPU 24 instructs the stage control unit 23 on the coordinates of the imaging region and the camera control unit 21 about the imaging timing by processing of the board appearance inspection program 25a. In response to the instruction, the stage control unit 23 drives the XY stage 13 so that the coordinates of the imaging region are located at a predetermined position (for example, the center of the visual field) of the direct-view camera 11b or the perspective camera 11a. Transport. When the conveyance of the substrate 50 by the XY stage 13 is finished, the camera control unit 21 drives the direct view camera 11b or the perspective camera 11a to take an image. When shooting is completed, the CPU 24 controls the camera control unit 21 to acquire image data output from the direct-view camera 11b or the perspective camera 11a and record it in the memory 25. Of the images photographed by the perspective camera 11a in this embodiment, an image photographed with the reference pad is a warp amount specifying perspective image, and an image photographed with a soldered portion of an electronic component that is an inspection target part is called an inspection perspective image. Shall. Of course, when the reference pad is an inspection object, the warp amount specifying perspective image can be used as the inspection perspective image.

  The coordinate correction data 25f is information for correcting the coordinates of the imaging region described above when an inspection image is captured, and is specified according to the amount of warpage of the substrate 50. That is, the coordinates of the imaging region are specified so that the field of view includes a pad on which the electronic component to be inspected is mounted based on the coordinates of the electronic component indicated by the substrate data 25b, but the substrate 50 is warped. If it has occurred, the CPU 24 corrects the coordinates of the imaging region based on the coordinate correction data 25f. The coordinate correction data 25f is calculated for each inspection target part.

  The substrate appearance inspection program 25a has a function of specifying the amount of warpage of the substrate 50 in order to perform correction according to the warpage of the substrate 50 as described above. That is, the board appearance inspection program 25a can cause the CPU 24 to implement the reference pad selection function 25a1, the image acquisition function 25a2, and the warp amount specifying function 25a3 in order to specify the warp of the board 50. The reference pad selection function 25a1 causes the CPU 24 to realize a function of selecting a reference pad for detecting warpage of the substrate 50 from among pads on which electronic components to be mounted on the substrate 50 are mounted. In addition, the pad which can become a reference pad in the board | substrate 50 concerning this embodiment is a rectangle, and the four sides are parallel to the four sides of the board | substrate 50 normally. That is, it is parallel to the X direction and the Y direction shown in FIGS. 2A and 2B.

  The image acquisition function 25a2 acquires an image including a reference pad photographed by a camera having an optical axis oriented in a direction inclined with respect to a reference plane which is a surface of the substrate when the substrate is not warped. The function is realized by the CPU 24. Further, the warp amount specifying function 25a3 is based on the position of the reference pad image in the image and the reference position that is the position in the image of the reference pad image when the substrate is not warped. The CPU 24 realizes a function of specifying the amount of warpage of the substrate in the direction perpendicular to the CPU. As described above, in this embodiment, the memory 25 that records the reference pad selection function 25a1, the image acquisition function 25a2, and the warp amount specifying function 25a3 and the CPU 24 that executes these functions constitute a displacement amount specifying device.

(2) Reference pad selection processing:
Hereinafter, processing of the board appearance inspection program 25a will be described together with details of functions realized by the reference pad selection function 25a1, the image acquisition function 25a2, and the warp amount specifying function 25a3. In the present embodiment, a pad having a predetermined size or more is a candidate pad that is a candidate for a reference pad, a candidate pad is specified based on the size of an electronic component, and an edge of the pad around the candidate pad The reference pad is selected by selecting a candidate pad that does not have an element that hinders the detection of.

  That is, since the size of the pad for mounting each electronic component is determined in advance at the design stage of the substrate 50, if the electronic component indicated by the substrate data 25b is specified, the size of the pad for mounting the electronic component is specified. Can be specified. Therefore, in the present embodiment, an electronic component to be mounted on a pad having a predetermined size or more is specified in advance, and the pad on which the electronic component is mounted is a pad having a predetermined size or more. The flag shown is recorded in the substrate data 25b in association with the data of each electronic component.

FIG. 4 is a diagram showing an example of the surface of the substrate 50, and a plurality of pads are indicated by white circles. As shown in FIG. 4, when the size of the electronic component is increased, the size of the terminal of the electronic component is increased, and accordingly, the size of the pad is also increased. In the example shown in FIG. 4, the pad indicated by a solid white circle is a pad smaller than a predetermined size (pad P shown in FIG. 4), and the pad indicated by a white dotted circle is larger than a predetermined size. It is a pad. Therefore, in the example shown in FIG. 4, all of the pads S ₀₁ , S ₀₂ , C ₁ and C ₂ are candidate pads.

  As described above, in a state where pads of a predetermined size or larger are defined as candidate pads, the CPU 24 performs the reference pad selection process shown in FIG. 3 in advance by the process of the reference pad selection function 25a1 before the start of the appearance inspection process. The reference pad on the substrate 50 is selected by executing. That is, the CPU 24 first acquires the board data 25b (step S100), and acquires the electronic component data 25c (step S105). Then, the CPU 24 refers to the comparison table 25d and creates an inspection procedure for each electronic component (step S110). That is, based on the comparison table 25d, the CPU 24 associates information indicating the inspection method and pass / fail judgment conditions for each electronic component described in the board data 25b and defines the inspection procedure. Information indicating the inspection procedure is defined for each of the direct-view image and the perspective image, and is referred to in a substrate appearance inspection process described later.

  Next, the CPU 24 selects a candidate pad (step S115). That is, in the data of each electronic component described in the board data 25b, if the pad to which the electronic component is connected is equal to or larger than a predetermined size, a flag indicating that the pad is a candidate pad is associated. . Therefore, the CPU 24 identifies data of the electronic component associated with the flag, and selects a pad to which the electronic component is connected as a candidate pad.

  Next, in steps S120 to S130, the CPU 24 selects a candidate pad that does not include an element that inhibits edge detection around the candidate pad, and sets the selected candidate pad as a reference pad. That is, in the substrate appearance inspection process, a configuration is adopted in which an edge included in the warp specifying perspective image is detected and the position of the reference pad is specified by the position of the edge in the image. Therefore, in this embodiment, a configuration is adopted in which a candidate pad that does not include an element that hinders detection of the edge is used as a reference pad.

  Specifically, the CPU 24 first excludes candidate pads that are shadows of the electronic component (step S120). That is, the CPU 24 refers to the board data 25b and specifies the height and the relative positional relationship (distance and direction) with the candidate pad for each electronic component existing within a predetermined distance around the candidate pad. Then, the CPU 24 identifies the positional relationship between the optical axis of the perspective camera 11a and the candidate pad, determines whether the candidate pad becomes a shadow of each electronic component, and excludes the candidate pad when it becomes a shadow. . That is, if there is an electronic component that intersects a straight line connecting the candidate pad and the imaging element of the perspective camera, the candidate pad is excluded. In the present embodiment, a flag indicating that the pad is not a reference pad is associated with the electronic component mounted on the excluded candidate pad and recorded in the substrate data 25b (the same applies hereinafter).

Further, the CPU 24 excludes candidate pads in which silk printing is present within a predetermined distance (step S125). That is, the CPU 24 refers to the board data 25b, determines whether or not silk printing exists within a predetermined distance around the candidate pad, and excludes the candidate pad when silk printing exists. For example, in the example shown in FIG. 4, pads S ₀₁ , S ₀₂ , C ₁ , and C ₂ are all candidate pads, but pad C ₁ is excluded because silk printing (IC655 characters) is present nearby. .

  Further, the CPU 24 excludes candidate pads whose wiring pattern extends from a portion corresponding to the edge (step S130). That is, the CPU 24 refers to the board data 25b, and is farthest from the end of the electronic component within the boundary (peripheral line) of the candidate pad from the position and direction of the candidate pad and the electronic component connected to the candidate pad. A boundary existing at a position is specified as an edge to be detected. Then, the CPU 24 refers to the board data 25b, determines whether or not the wiring pattern extends from the detection target edge, and excludes the candidate pad when the wiring pattern extends from the detection target edge.

For example, in the example shown in FIG. 4, a rectangular parallelepiped electronic component is connected to the pads S ₀₂ and C _2. One end of the rectangular parallelepiped is pad S ₀₂ and the other end is soldered on the pad C _2. Implementation is performed by attaching. In these pads S ₀₂ and C ₂ , the boundary that is farthest from the end of the electronic component is the boundary B _{1 on} the left side of the drawing for the pad S _{02 and} the boundary B ₂ on the right side of the drawing for the pad C. is there. In the present embodiment, these boundaries are detected edges. Therefore, in the present embodiment, it is determined whether or not the wiring pattern extends from these boundaries, and the pad C ₂ extending from the boundary in the right direction of the drawing is excluded.

After the above processing, the CPU 24 determines, as reference pads, candidate pads that remain without being excluded (that is, candidate pads that are not associated with a flag indicating that they are not reference pads) (step S135). In the example shown in FIG. 4, the reference pads S ₀₁ and S ₀₂ are specified from the candidate pads S ₀₁ , S ₀₂ , C ₁ and C ₂ . Since most of the candidate pads as described above are provided, the reference pad can be selected from most of the substrates. Therefore, there is no need to provide a mark or the like as a reference for detecting the warpage of the substrate, and a highly versatile technique can be provided.

(3) Board appearance inspection processing:
Next, the board appearance inspection process executed by the board appearance inspection program 25a will be described in detail. FIG. 5 is a flowchart showing the substrate appearance inspection process. In the substrate appearance inspection process, first, the CPU 24 loads the substrate 50 onto the guide rail 12 on the XY stage 13 by a transport mechanism (not shown) and supports both ends thereof (step S200). In the present embodiment, a configuration is adopted in which imaging and inspection are sequentially executed for each inspection object portion, and the CPU 24 refers to the substrate data 25b by the processing of the substrate appearance inspection program 25a, and processes each inspection object portion. The inspection is executed by the loop processing of steps S205 to S220.

  Specifically, the CPU 24 moves the substrate to the imaging position of the inspection target part (step S205). That is, based on the substrate data 25 b, the coordinates of the inspection target part that is the processing target are specified, and a signal indicating the coordinates is output to the stage control unit 23. As a result, the coordinates of the inspection target part to be processed are included in the visual field of the direct-view camera 11b. Next, the CPU 24 captures a direct view image (step S210). That is, the CPU 24 outputs a control signal to the camera control unit 21 and captures a direct-view image in the imaging region with the direct-view camera 11b.

  Next, the CPU 24 inspects the inspection target portion that is the processing target (step S215). That is, the CPU 24 refers to the above-described inspection procedure, performs image processing shown in the inspection method, acquires a feature amount, compares the feature amount with a threshold value as a pass / fail determination condition, and determines pass / fail. Note that the present embodiment is configured such that the pass / fail determination result is undetermined under specific conditions, such as when the difference between the feature amount and the threshold is small. Of course, various methods can be employed as the inspection method, and a method for determining pass / fail of the inspection object by pattern matching or a method for visually inspecting based on the direct-view image displayed on the display unit 30 may be employed. . Information indicating the inspection result is recorded in the memory 25.

  When the inspection of the inspection target part that is the processing target is finished, the CPU 24 determines whether or not the inspection of all the inspection target parts is finished (step S220), and the inspection of all the inspection target parts is finished. If it is not determined, the processing from step S205 is repeated. That is, one inspection target part that is not a processing target is extracted from the inspection target parts and set as a new processing target, and the processes in and after step S205 are repeated. If it is determined in step S220 that the inspection of all the inspection target parts has been completed, the CPU 24 determines whether or not there is an inspection target part that requires detailed inspection (step S225). That is, in the inspection in step S215, if there is an inspection target part for which the pass / fail determination result is undetermined, it is considered that there is an inspection target part that requires detailed inspection.

  If it is not determined in step S225 that there is an inspection target part that requires detailed inspection, the CPU 24 outputs the inspection result (step S230). That is, the CPU 24 outputs, to the output unit 26, a control signal for displaying information in which each inspection target unit is associated with the pass / fail determination result on the display unit 30. As a result, the display unit 30 displays information associating each inspection target unit with the pass / fail determination result, and the user can grasp the pass / fail determination result of each inspection target unit. Then, the CPU 24 releases the support of the substrate 50 by the guide rails 12 on the XY stage 13 by a transport mechanism (not shown), and unloads the substrate 50 from the XY stage 13 (step S235).

  On the other hand, if it is determined in step S225 that there is an inspection target part that requires detailed inspection, the CPU 24 performs detailed inspection in step S240 and subsequent steps. In the present embodiment, a configuration is adopted in which imaging and inspection are sequentially executed for an inspection target portion that requires detailed inspection, and the CPU 24 refers to the substrate data 25b by the processing of the substrate appearance inspection program 25a, and details The inspection is executed by the loop processing of steps S240 to S300 for each of the inspection target portions that require inspection.

  Specifically, the CPU 24 uses the reference pad selection function 25a1 to process the reference pad closest to the inspection target portion to be processed on both sides in the direction parallel to the two sides supported by the guide rail 12 of the substrate 50. Is specified (step S240). That is, the reference pad closest to the inspection target portion to be processed is specified on one side in the direction parallel to the two sides supported by the guide rail 12 of the substrate 50. Further, the reference pad closest to the inspection target portion to be processed is specified on the other side in the direction parallel to the two sides supported by the guide rail 12 of the substrate 50.

For example, in FIG. 2B, the reference pad is indicated by a broken-line rectangle, and the inspection target part I is indicated by a broken-line circle, and the direction parallel to the X direction is parallel to the two sides supported by the guide rails 12 of the substrate 50. It is. In this example, if the top of FIG 2B one in a direction parallel to the X direction, the closest reference pad inspection target portion I is a reference pad S _1. Further, when the other direction parallel to the X direction is lower Figure 2B, the closest reference pad inspection target portion I is a reference pad S _2. Therefore, in the example shown in FIG. 2B, when step S240 is executed for the inspection target portion I that is the processing target, the reference pad S _{1 that} is separated from the inspection target portion I by a distance L ₁ min and the inspection target portion I. The reference pad S ₂ that is a distance L ₂ min downward from the center is specified as the reference pad closest to the inspection target part I on both sides in the direction parallel to the two sides.

When the reference pad is specified in step S240, the CPU 24 moves the substrate 50 so that one reference pad is included in the field of view of the perspective camera 11a by the processing of the image acquisition function 25a2 (step S245). That is, based on the substrate data 25 b, the coordinates of the inspection target part that is the processing target are specified, and a signal indicating the coordinates is output to the stage control unit 23. As a result, the coordinates of the inspection target part to be processed are included in the field of view of the perspective camera 11a. For example, in the example shown in FIG. 2B, a state where the reference pad S ₁ is included in the field of view of the perspective camera 11a.

Next, the CPU 24 captures a warp specifying perspective image by the processing of the image acquisition function 25a2 (step S250). That is, the CPU 24 outputs a control signal to the camera control unit 21 to capture an image of the imaging region by the perspective camera 11a, and the perspective camera 11a disposed on the side opposite to the end of the electronic component mounted on the reference pad. The image photographed in step 3 is set as a warp specifying perspective image. In the example illustrated in FIG. 2B, reference pad S ₁ is a predetermined position in the field (eg, field center) of the image located is photographed. Then, included among the image taken by four oblique camera 11a, the reference pad S boundary located farthest from the end of the electronic components mounted on the ₁ in the image without being in the shadow of the electronic component The extracted image is extracted as a warp specifying perspective image. For example, in the case of the reference pads S ₀₁ and S ₀₂ shown in FIG. 4, an image obtained by photographing the reference pads S ₀₁ and S ₀₂ with the perspective camera 11a located on the left side of the drawing is a warp specifying perspective image.

  Next, the CPU 24 specifies the warpage amount in the Y direction of the substrate 50 based on the warpage amount at the position of one reference pad (step S255). That is, the position of the image of the reference pad in the warp specifying perspective image and the reference position that is the position of the image of the reference pad in the warp specifying perspective image when the substrate 50 is not warped. The warpage amount corresponding to the difference is regarded as occurring at the position of the reference pad, the warpage amount of the substrate 50 is specified, and the warpage amount in the Y direction is estimated based on the warpage amount.

Note that the position fluctuation of the reference pad accompanying the warpage of the substrate 50 in this embodiment mainly appears in the Z direction, and the position fluctuation in the X direction and the Y direction is so small that it can be ignored. Therefore, in the present embodiment, it is assumed that the position variation of the reference pad accompanying the warp of the substrate 50 occurs only in the Z direction. FIG. 6A is a diagram showing the shape of the upper surface of the substrate 50 at the position X ₁ in the X direction shown in FIG. In FIG. 6A, an example of the case where the substrate 50 is warped upward is exaggerated.

6A, the position of the reference pad S _{1 in} the Y direction is indicated as Y ₁ , and the width between the two sides on which the substrate 50 is supported is W. In the present embodiment, the photographing position by the perspective camera 11a is set so that Y ₁ which is the position of the reference pad S _{1 in} the Y direction passes through the optical axis of the perspective camera 11a when the substrate 50 is not warped. . Accordingly, when the substrate 50 is not warped, the position Y ₁ in the image where the reference pad S ₁ is photographed corresponds to the reference position.

When the warp as shown in FIG. 6A has occurred in the substrate 50, a reference for the position of the pad S ₁ is shifted in the Z direction, perspective camera 11a of the image of the reference pad S ₁ in the visual field on the optical axis of the perspective camera 11a The reference position Y ₁ does not exist. When the position variation direction of the reference pad S ₁ is only the Z direction, the position of the image of the reference pad S ₁ in the warp specifying perspective image taken by the perspective camera 11a and the warp specifying for the reference position Y ₁ are specified. S _a corresponding to the amount of deviation between the position in the perspective image is a one-to-one correspondence with the warp amount h _a in the Z direction of the substrate 50. Therefore, in the present embodiment, information in which the shift amount S _A and the warp amount h _A are associated with each other is recorded in the memory 25 in advance.

Then, CPU 24, by analyzing the warp specifying perspective image, obtains a shift amount S _A between the position and the reference position Y ₁ of the image of the reference pad S ₁ in warp specifying perspective image, referring to the memory 25 identifying warpage h _a corresponding to and offset amount S _a. In the present embodiment, the position of the image of the reference pad S ₁ is identified based on the position of the reference pad S ₁ of the image of the edge of the warp specifying perspective image.

Figure 6B shows an example of a warp specifying perspective image obtained by photographing the reference pad S ₁ by a perspective camera 11a shown in FIG. 6A, X direction shown in the vertical direction in FIG. 2B, Y showing lateral direction in FIG. 6B ' Shown as direction. As shown in FIG. 6B, the edge of the image of the reference pad S ₁ is parallel to the X direction. The position of the edge in the warp specifying perspective image is determined by setting the brightness value in the image in the direction parallel to the edge direction of the reference pad S ₁ (X direction) in the warp amount specifying perspective image as shown in FIG. 6B. The result of integration is specified by comparing the result of integration of the luminance values along a direction perpendicular to the edge portion (Y ′ direction).

FIG. 6C shows the sum of the luminance values in the X direction at each position in the Y ′ direction in the warp amount specifying perspective image shown in FIG. 6B, the horizontal axis as the Y ′ direction, and the vertical axis as the integrated value Br of the luminance values. It is an example of a graph. In the substrate 50, the luminance value of the insulating resin on the surface is relatively small, the luminance value of the surface of the electronic component is relatively larger than the luminance value of the insulating resin, the luminance value of the pad and the solder on the pad The luminance value is relatively largest. Therefore, the luminance value integrated value Br changes abruptly at the edge corresponding to the boundary of the pad. In FIG. 6C, the position where the integrated value Br changes rapidly is the position Y′e. Therefore, the position Y in the image reference position Y ₁ of the reference pad S ₁ is being photographed when the warpage in the substrate 50 does not occur 'and _1; actual edge of the reference pad S ₁ is imaging position Y' If the shift amount S _A is specified based on the shift (number of pixels) from e, the warp amount h _A corresponding to the shift amount S _A can be specified.

When the warpage amount at the position of the reference pad is specified as described above, the CPU 24 specifies the warpage amount in the Y direction of the substrate 50 based on the warpage amount. That is, the warp amount at the position of the reference pad corresponds to the warp amount h _A at the position Y ₁ in the example shown in FIG. 6A. Therefore, the upward convex curve shown in FIG. 6A is specified based on the warp amount h _A. In the Y direction, the amount of warpage is assumed to change as shown by the curve.

Specifically, the CPU 24 specifies the amount of warpage in the Y direction by specifying a function (Z = f (Y)) where Y is an independent variable and Z is a dependent variable. In this embodiment, as shown in FIG. 6A, the coordinates (Z, Y) = (0, 0), (W, 0) of the fixed ends of the substrate and the coordinates (Y ₁ , h _A ) of the reference pad. The deviation amount Z is defined by a quadratic function shown in the following equation (1) that passes through three points.
Z = h _A × {Y × (Y−W)} / {Y ₁ × (Y ₁ −W)} (1)
In this way, the near-term amount can be estimated from the actual positional deviation amount by the equation that represents the Y-direction warpage amount Z in a curve.

  The deviation amount Z is a function with Y as an independent variable and Z as a dependent variable, and may be any expression that can approximately estimate the deviation amount at an arbitrary point on the substrate. It is not limited to (1). For example, various spline functions and linear functions may be employed. Of course, the amount of deviation at a plurality of positions may be specified based on reference pads at a plurality of positions in the Y direction, and the function Z may be specified based on the amount of deviation at the plurality of positions. Further, the function Z may be expressed by a plurality of approximate expressions obtained by subdividing the section in the Y direction.

As described above, when the amount of warping in the Y direction at the position of the reference pad is specified based on one reference pad, the CPU 24 specifies the amount of warping in the Y direction at the position of the reference pad based on the other reference pad. . That is, when the amount of warpage in the Y direction at the position X ₁ is specified based on the reference pad S ₁ shown in FIG. 2B, the CPU 24 further performs the process in the Y direction at the position X ₂ based on the reference pad S ₂ in steps S260 to S270. Specify the amount of warpage.

Steps S260 to S270 are realized by performing the same processing as steps S245 to S255 on the other reference pad (reference pad S ₂ ). That is, in step S260, the substrate 50 is moved so that the other reference pad is included in the field of view of the perspective camera 11a. In step S265, a warp specifying perspective image is taken for the other reference pad. Further, in step S270, the CPU 24 specifies the warpage amount in the Y direction of the substrate 50 based on the warpage amount at the position of the other reference pad.

When the warpage amount in the Y direction at the position X ₁ and the warpage amount in the Y direction at the position X ₂ are specified as described above, the CPU 24 performs the warpage amount specifying function 25a3 to process the warpage amount at the position of the inspection target portion. Is specified (step S275). In the present embodiment, the CPU 24 refers to the two warp amounts in the Y direction specified based on the reference pad (the warp amounts specified in steps S255 and S270), and determines the distance between the reference pad and the inspection target portion. Based on this, an interpolation calculation is performed to specify the amount of warpage at the position of the inspection target portion.

For example, in the example shown in FIG. 2B, the coordinates of the inspection target part I are (Xi, Yi). Further, the warpage amount in the Y direction at the positions X ₁ and X ₂ in the X direction is specified based on the warpage amount at the positions of the reference pads S ₁ and S ₂ . Accordingly, referring to these warpage amounts, the warpage amounts δ ₁ and δ _{2 at} the coordinates (X ₁ , Yi) and (X ₂ , Yi) can be specified. Therefore, by using the distance L ₂ min with coordinates (X _1, Yi) coordinates (Xi, Yi) the distance between L ₁ min and the coordinate (X _2, Yi) coordinates (Xi, Yi), inspection The amount of warping Δ at the coordinates (Xi, Yi) of the target portion I is, for example, Δ = (L ₂ min / (L ₁ min + L ₂ min)) × δ ₁ + (L ₁ min / (L ₁ min + L ₂ min)) Xδ ₂ can be calculated.

When the warpage amount of the inspection target portion is specified as described above, the CPU 24 determines the position of the inspection target portion of the perspective camera 11a in the state where the substrate 50 is warped by the warpage amount by the processing of the warpage amount specifying function 25a3. The coordinate correction data 25f indicating the coordinates of the imaging region for imaging the perspective image for inspection set within the field of view is created (step S280). The generated coordinate correction data 25 f is recorded in the memory 25. Here, the coordinate correction data 25f is created by utilizing the fact that the amount of deviation between the position of the reference pad image in the image and the reference position has a one-to-one correspondence with the amount of warpage of the substrate 50 in the Z direction. do it. For example, if the warpage amount in the inspection target portion is the same as the warp amount h _A shown in FIG. 6A, the correction amount by using the perspective angle θ shift amount S _A and perspective camera 11a corresponding to the amount of warpage h _A M It calculates _{a =} S _a × _sinθ, it is possible to employ a configuration in which the coordinate correction data 25f are compared with the reference position Y ₁ to identify the coordinates have moved by a correction amount M _a in the Y direction.

  Next, the CPU 24 moves the substrate 50 by the processing of the substrate appearance inspection program 25a so that the inspection target part is included in the field of view of the perspective camera 11a (step S285). That is, based on the coordinate correction data 25f, the corrected coordinates relating to the inspection target part that is the processing target are specified, and a signal indicating the corrected coordinates is output to the stage control unit 23. As a result, the corrected coordinates relating to the inspection target portion that is the processing target are included in the visual field (for example, the visual field center) of the perspective camera 11a.

  Next, the CPU 24 captures an inspection perspective image by the processing of the board appearance inspection program 25a (step S290). That is, the CPU 24 outputs a control signal to the camera control unit 21 to capture an image of the imaging region with the perspective camera 11a, and the captured image is used as an inspection perspective image.

  Next, the CPU 24 inspects the inspection target portion that is the processing target by the processing of the board appearance inspection program 25a (step S295). That is, the CPU 24 refers to the above-described inspection procedure, performs image processing shown in the inspection method, acquires a feature amount, compares the feature amount with a threshold value as a pass / fail determination condition, and determines pass / fail. As a result, the pass / fail determination result that has been determined for the inspection target portion that is the processing target is specified. Of course, also here, various methods can be adopted as the inspection method, and a method of judging the quality of the inspection object by pattern matching or a method of visually inspecting based on the direct-view image displayed on the display unit 30 is adopted. May be. Information indicating the inspection result is recorded in the memory 25.

  When the inspection of the inspection target portion that is the processing target is completed, the CPU 24 determines whether or not the inspection has been completed for all of the inspection target portions that require detailed inspection (step S300), and all the inspection targets are determined. If it is not determined that the part inspection has been completed, the processes in and after step S240 are repeated. That is, out of the inspection target portions that require detailed inspection, one inspection target portion that is not a processing target is extracted and set as a new processing target, and the processes in and after step S240 are repeated. If it is determined in step S300 that the inspection has been completed for all of the inspection target portions that require detailed inspection, the CPU 24 outputs the inspection result (step S305). That is, the CPU 24 outputs, to the output unit 26, a control signal for displaying information in which each inspection target unit is associated with the pass / fail determination result on the display unit 30. As a result, the display unit 30 displays information associating each inspection target unit with the pass / fail determination result, and the user can grasp the pass / fail determination result of each inspection target unit. Then, the CPU 24 releases the support of the substrate 50 by the guide rail 12 on the XY stage 13 by a transport mechanism (not shown), and unloads the substrate 50 from the XY stage 13 (step S310). Through the above processing, it is possible to accurately determine whether or not the inspection target portion is good even if the substrate 50 is warped.

(4) Other embodiments:
The above embodiment is an example for carrying out the present invention, and various other embodiments can be adopted as long as the amount of warpage of the substrate is specified based on the reference pad selected from the pads on the substrate. is there. For example, the number of perspective cameras is not limited to four, and may be an arbitrary number of one or more. Of course, the optical axis direction of the perspective camera may be fixed or movable. Further, the edge corresponding to the boundary of the reference pad is preferably oriented so as to be perpendicular to the projection line of the optical axis of the perspective camera, and is fixedly arranged based on the substrate data 25b. The reference pad having the relationship with the perspective camera may be specified, or the orientation of the perspective camera or the board may be adjusted based on the board data 25b.

  Furthermore, in the above-described embodiment, the warp of the substrate is specified based on the two reference pads. However, the number of reference pads referred to for specifying the warp of the substrate is not limited to two. One or more may be sufficient. For example, a configuration may be adopted in which the amount of warpage in the inspection target portion is specified based on the reference pad closest to the inspection target portion on the substrate. That is, as in the example shown in FIG. 2B, in the state where the two sides of the substrate 50 are supported, the amount of warpage of the substrate changes greatly in the Y direction, but the change in the X direction is small. The amount of warp in the Y direction can be specified based on one reference pad. Therefore, if the amount of warpage in the Y direction is specified based on one reference pad and the amount of warpage of the substrate does not change in the X direction, the amount of warpage of the substrate at an arbitrary position based on one reference pad. Can be specified.

Further, in the above-described embodiment, the warpage amount of the substrate in an arbitrary position is estimated by specifying the warpage amount of the substrate in the Y direction. The warpage amount of the substrate at an arbitrary position may be specified based on the warpage amount of the substrate. For example, to identify the warping amount in the reference pad S ₁ of the coordinates (X _1, Yi) on the basis of the reference pad S ₁ shown in FIG. 2B, reference pad S ₂ of coordinates based on reference pad S ₂ (X _2, Yi identify warpage in), the inspection target portion of the coordinates (Xi, Yi) and the coordinate (X _1, Yi) the distance between and the inspected portion of the coordinates (Xi, Yi) and the coordinate (X _2, Yi) and the You may identify the board | substrate curvature amount in the coordinate (Xi, Yi) of a test object part by the interpolation calculation using distance.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate visual inspection apparatus, 10 ... Imaging part, 11a ... Perspective camera, 11b ... Direct view camera, 12 ... Guide rail, 13 ... XY stage, 20 ... Control part, 21 ... Camera control part, 22 ... Guide rail control , 23... Stage control unit, 24... CPU, 25... Memory, 25 a... Board appearance inspection program, 25 a 1... Reference pad selection function, 25 a 2 ... Image acquisition function, 25 a 3. Electronic component data, 25d ... contrast table, 25e ... photographed image data, 25f ... coordinate correction data, 26 ... output unit, 30 ... display unit, 50 ... substrate

Claims (7)

Reference pad selecting means for selecting a reference pad for detecting warpage of the substrate from among pads for mounting electronic components on the substrate;
Image acquisition means for acquiring an image including an image of the reference pad photographed by a camera having an optical axis oriented in a direction inclined with respect to a reference plane which is a surface of the substrate when the substrate is not warped. When,
Based on the position of the image of the reference pad in the image and the reference position, which is the position of the image of the reference pad in the image when no warpage occurs in the substrate, is perpendicular to the reference plane. A warp amount specifying means for specifying the amount of warpage of the substrate in the direction;
Displacement amount specifying device comprising: The warpage amount specifying means detects an edge of the image of the reference pad, and specifies a position of the image of the reference pad in the image by a position of the edge in the image.
The displacement amount specifying device according to claim 1. The reference pad selection means selects the pad having a predetermined size or more as a candidate pad that is a candidate for the reference pad, and selects the candidate pad that does not include an element that hinders detection of the edge around the candidate pad. The reference pad
The displacement amount specifying device according to claim 2. The substrate is supported on two parallel sides of the substrate, the substrate and the camera move relatively in a direction parallel to the reference plane,
The reference pad selection means is the closest to the reference pad on the substrate on one side in the direction parallel to the two sides and the inspection target portion on the other side in the direction parallel to the two sides. Identifying the amount of warpage of the substrate in the inspection target portion based on the reference pad that is close,
The displacement amount specifying device according to claim 3. The substrate is supported on two parallel sides of the substrate, the substrate and the camera move relatively in a direction parallel to the reference plane,
The reference pad selecting means specifies the amount of warpage of the substrate in the inspection target portion based on the reference pad closest to the inspection target portion on the substrate;
The displacement amount specifying device according to claim 3. A reference pad selection step of selecting a reference pad for detecting warpage of the substrate from among pads for mounting an electronic component on the substrate;
An image acquisition step of acquiring an image including an image of the reference pad photographed by a camera having an optical axis oriented in a direction inclined with respect to a reference plane which is a surface of the substrate when the substrate is not warped. When,
Based on the position of the image of the reference pad in the image and the reference position, which is the position of the image of the reference pad in the image when no warpage occurs in the substrate, is perpendicular to the reference plane. A warp amount specifying step for specifying the amount of warpage of the substrate in the direction;
Displacement amount specifying method including A reference pad selection function for selecting a reference pad for detecting warpage of the substrate from among pads for mounting electronic components on the substrate;
An image acquisition function for acquiring an image including an image of the reference pad photographed by a camera having an optical axis oriented in a direction inclined with respect to a reference plane that is a surface of the substrate when the substrate is not warped. When,
Based on the position of the image of the reference pad in the image and the reference position, which is the position of the image of the reference pad in the image when no warpage occurs in the substrate, is perpendicular to the reference plane. A warpage amount specifying function for specifying the amount of warpage of the substrate in the direction;
Displacement amount identification program that makes a computer realize.