WO2024117099A1 - Inspection device - Google Patents

Inspection device Download PDF

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Publication number
WO2024117099A1
WO2024117099A1 PCT/JP2023/042440 JP2023042440W WO2024117099A1 WO 2024117099 A1 WO2024117099 A1 WO 2024117099A1 JP 2023042440 W JP2023042440 W JP 2023042440W WO 2024117099 A1 WO2024117099 A1 WO 2024117099A1
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height information
unit
inspected
inspection
image
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PCT/JP2023/042440
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French (fr)
Japanese (ja)
Inventor
コァン チュ ガン
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株式会社サキコーポレーション
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Publication of WO2024117099A1 publication Critical patent/WO2024117099A1/en

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  • the present invention relates to an inspection device.
  • the state of connection between electronic components e.g., pins
  • the wiring on the board by solder hereinafter referred to as the "solder joint state"
  • tomosynthesis-type X-ray inspection equipment is used.
  • inspection must be performed based on the exact position of the surface (top surface) of the electronic circuit board, so there are inspection equipment that irradiate the surface of the electronic circuit board with laser light, obtain height information of the surface of the electronic circuit board from the reflected light, and eliminate the effects of warping and bending based on this height information (see, for example, Patent Document 1).
  • cross-sectional image In order to generate a three-dimensional reconstructed image (cross-sectional image) from an X-ray transmission image to inspect the state of solder joints, it is necessary to obtain information on the warping and bending of the electronic board and, based on this information, accurately select the cross-sectional image (cross-sectional image of the board surface) to be used for inspection.
  • the surface of the electronic board may be coated with a resist or have electronic components attached, the position at which the laser light can be irradiated to measure the height of the board surface is limited. For example, a pad surface on the board with no electronic components attached is provided, and the height is measured by irradiating this pad surface with laser light.
  • detectors for detecting X-ray transmission images have become larger and have higher resolution, increasing the amount of data per cross-sectional image, and so there is a tendency for the amount of processing required to select the cross-sectional image of the inspection target to also increase.
  • the present invention has been made in consideration of these problems, and aims to provide an inspection device configured to acquire height information of an electronic board (inspected object) that is the object of inspection, determine a search range in a reconstructed image generated from a transmission image based on this height information, and compare the reconstructed image (cross-sectional image) within the determined search range with a reference image to determine the cross-sectional image of the inspection object.
  • an inspection device configured to acquire height information of an electronic board (inspected object) that is the object of inspection, determine a search range in a reconstructed image generated from a transmission image based on this height information, and compare the reconstructed image (cross-sectional image) within the determined search range with a reference image to determine the cross-sectional image of the inspection object.
  • the inspection device has a radiation source, a holding unit that holds an object to be inspected, a detector, a height information acquisition unit that acquires height information of the object to be inspected, a drive unit that changes the relative positions of the radiation source, the object to be inspected held by the holding unit, and the detector, and the relative positions of the object to be inspected held by the holding unit and the height information acquisition unit, and a control unit, and the control unit executes the steps of acquiring height information of the object to be inspected by the height information acquisition unit, generating cross-sectional images of the object to be inspected from a plurality of transmission images of the object to be inspected obtained by detecting radiation emitted from the radiation source and passing through the object to be inspected by the detector when the radiation source, the object to be inspected held by the holding unit, and the detector are in a predetermined relative position by the drive unit, determining a predetermined range in the height direction based on the height information, determining a cross-section
  • the control unit of the inspection device desirably moves the object to be inspected held by the holding unit relative to the height information acquisition unit using the drive unit, acquires height information of multiple positions on the substrate surface of the object to be inspected using the height information acquisition unit, and determines height information of the substrate surface at a predetermined position in an area including the multiple positions from the height information of the multiple positions.
  • the control unit of the inspection device desirably moves the object to be inspected held by the holding unit relative to the height information acquisition unit using the drive unit, acquires height information of multiple positions on the object to be inspected using the height information acquisition unit, removes height information other than that of the substrate surface from the height information of the multiple positions by calculation, and determines height information of the substrate surface at a predetermined position in an area including the multiple positions.
  • the control unit of the inspection device acquires the height information at the multiple positions while changing the relative position between the height information acquisition unit and the test object held by the holding unit using the drive unit.
  • the control unit of the inspection device preferably acquires the position of the substrate surface of the object to be inspected from image data of the object to be inspected that has been acquired in advance, and acquires the height information of the acquired position by the height information acquisition unit.
  • the control unit of the inspection device in the step of acquiring the height information, it is desirable for the control unit of the inspection device according to the present invention to acquire the position of the substrate surface from color information of the object to be inspected in the image data.
  • the control unit of the inspection device preferably acquires height information of the multiple positions while changing the relative position of the object to be inspected held by the holding unit with respect to the height information acquisition unit using the drive unit, and determines height information of the substrate surface of the object to be inspected from the height information of the multiple positions.
  • the height information acquisition unit of the inspection device according to the present invention is a displacement meter that acquires the height information on the top or bottom surface of the substrate of the object to be inspected.
  • the height measurement unit acquires height information of the object to be inspected, and then the transmission image is acquired to generate a reconstructed image of the object to be inspected. Based on the height information from the height measurement unit, the search range of the inspection surface in the reconstructed image is determined, and the cross-sectional image of the object to be inspected is compared with the reference image within this range to select the cross-sectional image of the inspection surface.
  • the time required to select the cross-sectional image of the inspection surface can be shortened compared to when comparing with all cross-sectional images.
  • FIG. 1 is an explanatory diagram for explaining a configuration of an inspection device according to an embodiment of the present invention.
  • FIG. 2 is an explanatory diagram for explaining each functional block of a control unit of the inspection device. 4 is a flowchart for explaining an inspection process in the inspection device.
  • FIG. 2 is an explanatory diagram showing an example of an object to be inspected by the inspection device.
  • 10 is a flowchart for explaining a substrate inspection surface detection process.
  • 11 is an explanatory diagram for explaining the relationship between height information and a search range in a reconstructed image.
  • FIG. 13 is a flowchart for explaining a modified example of a method for acquiring height information.
  • 10 is an explanatory diagram showing an example of a measurement position when acquiring height information of the entire surface of the upper surface of a substrate of an object to be inspected.
  • FIG. 1 is an explanatory diagram for explaining a configuration of an inspection device according to an embodiment of the present invention.
  • FIG. 2 is an explanatory diagram for
  • the inspection device 1 is configured to have a control unit 10, which is made up of a processing device such as a personal computer (PC), a monitor 11, and an imaging unit 32.
  • the imaging unit 32 further has a radiation quality change unit 14, a radiation generator drive unit 16, a substrate holder drive unit 18, a detector drive unit 20, a radiation generator 22, a substrate holder 24, a detector 26, and a height information acquisition unit 50.
  • the radiation generator 22 is a device (ray source) that generates radiation such as X-rays, and generates radiation by colliding accelerated electrons with a target such as tungsten or diamond.
  • a target such as tungsten or diamond.
  • the radiation in this embodiment is described as being X-rays, the radiation is not limited to this.
  • the radiation may be alpha rays, beta rays, gamma rays, ultraviolet rays, visible light, or infrared rays.
  • the radiation may also be microwaves or terahertz waves.
  • the board holding unit 24 holds the electronic board, which is the object under inspection 12.
  • the object under inspection 12 held by the board holding unit 24 is irradiated with radiation generated by the radiation generator 22, and the radiation that has passed through the object under inspection 12 is detected by the detector 26 to capture an image.
  • the radiation transmission image of the object under inspection 12 captured by the detector 26 will be referred to as a "transmission image.”
  • the board holding unit 24, which holds the electronic board, which is the object under inspection 12, and the detector 26 are moved relative to the radiation generator 22 to obtain multiple transmission images, and a reconstructed image (cross-sectional image) is generated from these transmission images.
  • the transmission image captured by the detector 26 is sent to the control unit 10, and is reconstructed into an image including the three-dimensional shape of the solder at the joint using a known technique such as the Filtered Backprojection (FBP) method.
  • the reconstructed image and the transmission image are stored in a storage unit (e.g., the storage unit 34 described later) in the control unit 10 or in an external storage unit (not shown).
  • a storage unit e.g., the storage unit 34 described later
  • an external storage unit not shown.
  • an image reconstructed into a three-dimensional image including the three-dimensional shape of the solder at the joint based on the transmission image is referred to as a "reconstructed image”.
  • An image obtained by cutting out an arbitrary cross section from the reconstructed image is referred to as a "cross-sectional image”.
  • Such a reconstructed image and cross-sectional image are output to the monitor 11.
  • the monitor 11 displays not only the reconstructed image and the cross-sectional image, but also the inspection results of the solder joint state described later.
  • the reconstructed image in this embodiment is also called a "planar CT" because it is reconstructed from a planar image (transmission image) captured by the detector 26 as described above.
  • the radiation quality change unit 14 changes the radiation quality generated by the radiation generator 22.
  • the radiation quality is determined by the voltage (hereafter referred to as “tube voltage”) applied to accelerate the electrons to be collided with the target, and the current (hereafter referred to as "tube current") that determines the number of electrons.
  • the radiation quality change unit 14 is a device that controls the tube voltage and tube current. This radiation quality change unit 14 can be realized using known technology such as a transformer or rectifier.
  • the quality of radiation is determined by the brightness and hardness of the radiation (spectral distribution of radiation).
  • Increasing the tube current increases the number of electrons that collide with the target, and the number of radiation photons generated.
  • the brightness of the radiation increases.
  • some components such as capacitors are thicker than other components, and in order to capture a transmission image of these components, it is necessary to irradiate them with radiation of high brightness.
  • the brightness of the radiation is adjusted by adjusting the tube current.
  • increasing the tube voltage increases the energy of the electrons that collide with the target, and the energy (spectrum) of the generated radiation increases.
  • the tube voltage can be used to adjust the contrast of a transmission image.
  • the radiation generator driving unit 16 has a driving mechanism such as a motor (not shown) and can move the radiation generator 22 up and down along axis A passing through its focal point (axis (optical axis) passing through the center of the radiation direction of the radiation emitted from the radiation generator 22, the direction of this axis being referred to as the "Z-axis direction").
  • a driving mechanism such as a motor (not shown) and can move the radiation generator 22 up and down along axis A passing through its focal point (axis (optical axis) passing through the center of the radiation direction of the radiation emitted from the radiation generator 22, the direction of this axis being referred to as the "Z-axis direction").
  • This makes it possible to change the distance between the radiation generator 22 and the inspected object (electronic board) 12 held by the board holding unit 24 to change the irradiation field and change the magnification ratio of the transmitted image captured by the detector 26.
  • the position of the radiation generator 22 in the Z-axis direction is detected
  • the detector driving unit 20 also has a driving mechanism such as a motor (not shown) and rotates the detector 26 along the detector rotation track 30.
  • the substrate holding unit driving unit 18 also has a driving mechanism such as a motor (not shown) and moves the substrate holding unit 24 in parallel on the plane on which the substrate rotation track 28 is provided.
  • the substrate holding unit 24 is configured to rotate on the substrate rotation track 28 in conjunction with the rotation of the detector 26. This makes it possible to capture multiple transmission images with different projection directions and projection angles while changing the relative positional relationship between the test object 12 held by the substrate holding unit 24 and the radiation generator 22.
  • the area on the test object 12 where a transmission image can be acquired is determined by the size of the area where the detector 26 detects radiation and the relative positions of the radiation generator 22, the test object 12 (substrate holding unit 24), and the detector 26.
  • the area where this transmission image can be acquired is called the "FOV (field of view)".
  • the rotation radius of the substrate rotation orbit 28 and the detector rotation orbit 30 is not fixed, but can be freely changed. This makes it possible to arbitrarily change the irradiation angle of the radiation irradiated to the substrate of the inspected object 12 and the components attached to this substrate.
  • the orbital plane of the substrate rotation orbit 28 and the detector rotation orbit 30 is perpendicular to the Z-axis direction described above, and if the directions perpendicular to this orbital plane are the X-axis direction and the Y-axis direction, the positions of the substrate holding part 24 in the X-axis direction and the Y-axis direction are detected by a substrate position detection part (not shown) and output to the control part 10, and the positions of the detector 26 in the X-axis direction and the Y-axis direction are detected by a detector position detection part (not shown) and output to the control part 10.
  • the height information acquisition unit 50 is disposed above the board holding unit 24 and is configured as a displacement meter that acquires height information of the top surface of the electronic board, which is the object to be inspected 12 held by the board holding unit 24.
  • This displacement meter can be configured, for example, to detect the position (height) of the top surface of the electronic board in the Z-axis direction by irradiating the top surface of the electronic board with laser light and receiving the reflected light, but is not limited to this configuration. For example, it may be configured to acquire height information by contacting a probe with the top surface of the electronic board.
  • the height information acquisition unit 50 in the following description is assumed to be a displacement meter that acquires height information using laser light, as described above.
  • the board constituting the object to be inspected 12 is not warped and does not bend when held by the board holding unit 24, the top surface of the board (board inspection surface described later) is flat, and its position in the Z direction is known from information such as the design of the electronic board (this ideal board inspection surface is called the "reference surface").
  • this ideal board inspection surface is called the "reference surface”
  • the control unit 10 can obtain information (hereinafter referred to as "height information") regarding the height of the upper surface (substrate inspection surface) of the substrate of the inspected object 12 held by the substrate holding unit 24 through the height information acquisition unit 50, and obtain the amount of deviation from the reference surface.
  • This height information is managed, for example, in an XYZ coordinate system with a predetermined position of the inspection device 1 as the origin, but the coordinate system is not limited to this.
  • the control unit 10 controls all operations of the inspection device 1 described above. Below, the main functions of the control unit 10 are explained using FIG. 2. Although not shown, input devices such as a keyboard and a mouse are connected to the control unit 10.
  • the control unit 10 includes a memory unit 34, an imaging processing unit 35, a cross-sectional image generating unit 36, a board inspection surface detecting unit 38, a pseudo cross-sectional image generating unit 40, and an inspection unit 42.
  • the imaging processing unit 35 of the control unit 10 also has the function of an imaging control unit that controls the operation of the radiation quality changing unit 14, the radiation generator driving unit 16, the board holding unit driving unit 18, and the detector driving unit 20.
  • each of these functional blocks is realized by the cooperation of hardware, such as a CPU that executes various arithmetic processes, and a RAM that is used as a work area for storing data and executing programs, and software. Therefore, these functional blocks can be realized in various ways by combining hardware and software.
  • the memory unit 34 stores information such as imaging conditions for capturing a transmission image of the electronic board, which is the inspected object 12, and the design of the electronic board.
  • the memory unit 34 also stores transmission images and reconstructed images (cross-sectional images, pseudo cross-sectional images) of the electronic board, as well as inspection results of the inspection unit 42, which will be described later.
  • the memory unit 34 also stores information for driving the radiation generator driving unit 16, the board holder driving unit 18, and the detector driving unit 20 (e.g., the speed at which the radiation generator driving unit 16 drives the radiation generator 22, the speed at which the board holder driving unit 18 drives the board holder 24, and the speed at which the detector driving unit 20 drives the detector 26, etc.).
  • the imaging processing unit 35 drives the radiation generator 22, substrate holding unit 24, and detector 26 using the radiation generator driving unit 16, substrate holding unit driving unit 18, and detector driving unit 20 to capture a transmission image of the object to be inspected held by the substrate holding unit 24, and generates a reconstructed image (cross-sectional image) from the transmission image.
  • the method of capturing the transmission image and generating the reconstructed image (cross-sectional image) by this imaging processing unit 35 will be described later.
  • the imaging processing unit 35 is also configured to control the operation of the height information acquisition unit 50.
  • the cross-sectional image generating unit 36 generates a cross-sectional image (reconstructed image) based on the multiple transmission images acquired from the storage unit 34. This can be achieved using known techniques, such as the FBP method or the maximum likelihood estimation method. Different reconstruction algorithms result in different properties of the reconstructed image and different times required for reconstruction. Therefore, multiple reconstruction algorithms and parameters used in the algorithms may be prepared in advance and the user may select one. This provides the user with the freedom to choose, such as prioritizing a shorter reconstruction time or prioritizing better image quality even if it takes more time.
  • Each of the generated cross-sectional images is output to the storage unit 34 along with attribute information, such as information that determines the position of each cross-sectional image in the Z-axis direction and the positions (coordinates) of pixels in the cross-sectional image in the X-axis direction and the Y-axis direction, and is stored in the storage unit 34.
  • attribute information such as information that determines the position of each cross-sectional image in the Z-axis direction and the positions (coordinates) of pixels in the cross-sectional image in the X-axis direction and the Y-axis direction
  • the board inspection surface detection unit 38 identifies an image (cross-sectional image) showing the surface to be inspected on the electronic board (e.g., the surface of the electronic board) from among the multiple cross-sectional images generated by the cross-sectional image generation unit 36.
  • a cross-sectional image showing the inspection surface of the electronic board is referred to as an "inspection surface image.”
  • the board inspection surface detection unit 38 is configured to identify the inspection surface image based on the height information acquired by the height information acquisition unit 50 described above. The method of identifying the inspection surface image will be described later.
  • the pseudo cross-sectional image generating unit 40 images the area of the board that is thicker than the cross-sectional image by stacking a predetermined number of consecutive cross-sectional images of the cross-sectional images generated by the cross-sectional image generating unit 36.
  • the number of cross-sectional images to be stacked is determined by the thickness of the area of the board that is shown by the cross-sectional image (hereinafter referred to as the "slice thickness") and the slice thickness of the pseudo cross-sectional image.
  • the inspection surface image identified by the board inspection surface detection unit 38 is used to identify the position of the solder.
  • the inspection unit 42 inspects the solder joint condition based on the cross-sectional image generated by the cross-sectional image generation unit 36, the inspection surface image identified by the board inspection surface detection unit 38, and the pseudo cross-sectional image generated by the pseudo cross-sectional image generation unit 40. Since the solder that joins the electronic board and the component is located near the board inspection surface, by inspecting the inspection surface image and the cross-sectional image that shows the area on the radiation generator 22 side of the inspection surface image, it is possible to determine whether the solder is properly joining the board and the component.
  • solder joint condition refers to whether or not an appropriate conductive path is formed when the electronic board and the component are joined by solder. Inspection of the solder joint condition includes bridge inspection, molten state inspection, and void inspection. “Bridge” refers to an undesirable conductive path between conductors caused by solder joining. “Melted state” refers to a state in which the joint between the electronic board and the component is insufficient due to insufficient melting of the solder, that is, whether or not there is a so-called “floating” state. "Void” refers to a defect in the solder joint caused by air bubbles in the solder joint. Therefore, the inspection unit 42 includes a bridge inspection unit 44, a molten state inspection unit 46, and a void inspection unit 48.
  • bridge inspection unit 44 inspects and voids, respectively, based on the pseudo cross-sectional image generated by the pseudo cross-sectional image generation unit 40, and the molten state inspection unit 46 inspects the molten state of the solder based on the inspection surface image identified by the board inspection surface detection unit 38.
  • the inspection results in the bridge inspection unit 44, molten state inspection unit 46, and void inspection unit 48 are stored in the memory unit 34.
  • FIG. 3 is a flowchart showing the process from obtaining height information on the substrate inspection surface, taking a transmitted image and generating a reconstructed image (cross-sectional image), to identifying the inspection surface image and inspecting the solder joint condition.
  • the process in this flowchart starts, for example, when the control unit 10 receives an instruction to start the inspection from an input device (not shown).
  • the image processing unit 35 of the control unit 10 first acquires height information of the board inspection surface (the upper surface of the board on which electronic components are attached) of the inspected object 12 by the height information acquisition unit 50 (step S100), as shown in FIG. 3.
  • the height information acquisition unit 50 is fixedly arranged, the height information of the board inspection surface of the inspected object 12 is acquired by moving the inspected object 12 by the board holding unit 24 to acquire height information of a desired position on the inspected object 12 (height information of the board inspection surface).
  • the height information acquisition unit 50 is configured to be movable, the height information of a desired position on the inspected object 12 is acquired by moving the height information acquisition unit 50.
  • the acquired height information is composed of a position (X, Y) on the XY plane and a height (Z) at that position, and is stored in the memory unit 34 in association with the field of view FOV as (X, Y, Z), for example.
  • Figure 4 shows an example of the object 12 to be inspected, which is an electronic board inspected by the inspection device 1.
  • the object 12 to be inspected has electronic components 12b to 12f attached to the board 12.
  • the dashed rectangle indicates the field of view FOV.
  • the image processing unit 35 of the control unit 10 may measure height information at the center O as height information of the top surface of the board 12a in the field of view FOV using the height information acquisition unit 50, or may measure height information at multiple points in the field of view FOV (for example, height information at the four corners P1 to P4 of the field of view FOV in Figure 4) and calculate height information at the center O of the field of view FOV from this height information using linear interpolation or the like.
  • the location where the top surface of the board 12a can be directly measured can be determined from data such as the design of the inspected object (electronic board) 12.
  • the location where no electronic components are attached can be identified from image data (two-dimensional color image) of the top surface of the inspected object 12 captured in advance. Since a green resist is generally applied to the top surface of the board 12a, the green parts of the image data can be identified and these green parts can be determined to be locations where no electronic components are attached.
  • height information can be acquired at the position of the board surface while moving the height information acquisition unit 50 and the board holding unit 24 (inspected object 12) relative to each other, so that height information can be acquired efficiently at multiple positions on the board surface.
  • the inspected object (electronic board) 12 is brought into the inspection device 1, it hits a stopper used to position the inspected object 12 and rotates slightly. At this time, the position of the inspected object (electronic board) 12 can be correctly read by reading the recognition mark, and the same route on the board can always be scanned when measuring height information with the height information acquisition unit 50, thereby improving the reproducibility of the measurement.
  • the relative positions of the substrate holding unit 24 and the height information acquisition unit 50 holding the object to be inspected 12 may be fixed for each location for which height information is to be acquired (in the case of a configuration in which the substrate holding unit 24 is moved to move the position at which the laser light from the height information acquisition unit 50 is irradiated, the substrate holding unit drive unit 18 moves the substrate holding unit 24 to move the object to be inspected 12 to the position at which the laser light is irradiated, and then the substrate holding unit 24 is stopped), or the height information may be acquired at a desired position while changing the relative positions of the substrate holding unit 24 and the height information acquisition unit 50 holding the object to be inspected 12 (in the case of a configuration in which the substrate holding unit 24 is moved to move the position at which the laser light from the height information acquisition unit 50 is irradiated, the substrate holding unit drive unit 18 moves the substrate holding unit 24).
  • the imaging processing unit 35 of the control unit 10 sets the irradiation field of the radiation emitted by the radiation generator 22 (the area where the radiation is irradiated to acquire a transmission image of the field of view FOV described above) by the radiation generator driving unit 16, moves the substrate holding unit 24 by the substrate holding unit driving unit 18, and moves the detector 26 by the detector driving unit 20 to change the imaging position, while setting the radiation quality of the radiation generator 22 by the radiation quality changing unit 14, irradiates the substrate with radiation, and captures a transmission image.
  • the cross-sectional image generating unit 36 of the control unit 10 generates a reconstructed image from the multiple transmission images thus captured (step S102).
  • This reconstructed image can also be managed in the same coordinate system (e.g., XYZ coordinate system) as the above-mentioned height information.
  • the movement path of the substrate holder 24 by the substrate holder driver 18 and the movement path of the detector 26 by the detector driver 20 when capturing a transmission image are set in advance in the substrate holder driver 18 and the detector driver 20 by reading information stored in the memory 34 or inputting information from an input device.
  • the position of the radiation generator 22 in the Z-axis direction is also set in advance in the radiation generator driver 16 by a similar method.
  • the substrate holder driver 18 and the detector driver 20 may move the substrate holder 24 and the detector 26 to a desired position, and the substrate holder 24 and the detector 26 may be stopped at a position where a transmission image is to be acquired before capturing a transmission image, or the substrate holder driver 18 and the detector driver 20 may move the substrate holder 24 and the detector 26 to a desired position while capturing a transmission image.
  • the captured transmission image and the generated reconstructed image are stored in the memory 34 for each field of view FOV.
  • the board inspection surface detection unit 38 of the control unit 10 receives the transmission image or the reconstructed image (cross-sectional image) from the cross-sectional image generation unit 36, and executes a board inspection surface detection process to identify the inspection surface image from the transmitted image or the reconstructed image (cross-sectional image) (step S104). For example, when identifying the inspection surface image from the reconstructed image, as shown in FIG. 5, the board inspection surface detection unit 38 of the control unit 10 first reads the height information of the current field of view FOV (height information acquired in step S100) from the storage unit 34 (step S1041), and determines the search range in the Z-axis direction in the reconstructed image (cross-sectional image) from this height information (step S1042).
  • FOV height information acquired in step S100
  • the search range is a predetermined range in the Z direction that includes the Z-direction position of the board inspection surface measured by the height information acquisition unit 50. This is because there is a high possibility that the cross-sectional image (inspection surface image) of the board inspection surface is included in the cross-sectional image in the predetermined range (search range) in the Z direction that includes the height information of the current field of view FOV (the measured Z-direction position of the board inspection surface).
  • the memory unit 34 stores in advance a cross-sectional image (called the "reference image") of the substrate inspection surface of a normal object to be inspected that has no abnormalities such as a solder joint state.
  • the substrate inspection surface detection unit 38 of the control unit 10 reads out the reference image of the current field of view FOV from the memory unit 34 (step S1043), and further reads out from the memory unit 34 the cross-sectional images within the search range determined in step S1042 among the reconstructed images of the current field of view FOV (the reconstructed images generated in step S102) (step S1044).
  • the substrate inspection surface detection unit 38 of the control unit 10 compares the reference image with each of the cross-sectional images read out in step S1024, identifies the cross-sectional image that most closely matches the reference image as the inspection surface image, stores the position of the identified cross-sectional image (inspection surface image) in the Z-axis direction as the position of the substrate inspection surface in the current field of view FOV (step S1045), and ends the substrate inspection surface detection process.
  • a phase-only correlation method can be used, which allows the matching rate to be found quickly and regardless of positional deviation. For example, as shown in FIG.
  • the pseudo cross-sectional image generating unit 40 of the control unit 10 generates a pseudo cross-sectional image based on the inspection surface image identified in step S104 and the Z-direction position of the substrate inspection surface (step S106).
  • the bridge inspection unit 44 of the control unit 10 obtains a pseudo cross-sectional image of a slice thickness equivalent to that of the solder ball that shows the solder ball from the pseudo cross-sectional image generation unit 40 (reads it from the storage unit 34) and inspects whether or not a bridge exists (step S108). If no bridge is detected ("N" in step S110), the molten state inspection unit 46 of the control unit 10 obtains an inspection surface image from the board inspection surface detection unit 38 (reads it from the storage unit 34) and inspects whether or not the solder is molten (step S112).
  • the void inspection unit 48 of the control unit 10 obtains a pseudo cross-sectional image that partially shows the solder ball from the pseudo cross-sectional image generation unit 40 (reads it from the storage unit 34) and inspects whether or not a void exists (step S116). If no voids are found ("N" in step S118), the inspection unit 42 of the control unit 10 determines that the solder joint condition is normal (step S120) and outputs this information to the memory unit 34.
  • step S110 If a bridge is detected ("Y" in step S110), the solder is not melted ("N” in step S114), or a void is present ("Y” in step S118), the inspection unit 42 determines that the solder joint condition is abnormal (step S122) and outputs this information to the memory unit 34. When the solder condition is output to the memory unit 34, the processing in this flowchart ends.
  • steps S104 to S122 shown in FIG. 3 is also performed for each of the above-mentioned fields of view FOVs, but steps S104 to S122 may be performed for each field of view FOV after capturing images of all fields of view FOVs in step S102, or steps S104 to S122 may be performed in parallel with capturing images of other fields of view FOVs, starting from the field of view FOV for which generation of reconstructed images (cross-sectional images and pseudo-cross-sectional images) has been completed.
  • the inspection device 1 before acquiring a transmission image of the inspected object 12, height information for each field of view FOV of the inspected object 12 is acquired by the height information acquisition unit 50, and then a transmission image is acquired for each field of view FOV to generate a reconstructed image of the inspected object. Based on the height information from the height information acquisition unit 50, a search range for the substrate inspection surface in the reconstructed image is determined, and the reconstructed image (cross-sectional image) of the inspected object 12 is compared with a reference image in this search range to determine the cross-sectional image of the substrate inspection surface.
  • the range of the reconstructed image (cross-sectional image) that includes the cross-sectional image of the substrate inspection surface is limited, and a comparison is performed within this limited range, so that the time required to identify the cross-sectional image of the substrate inspection surface can be shortened compared to the case of comparing with all cross-sectional images.
  • the height information acquisition unit 50 can acquire height information during preparation time for generating radiation from the radiation generator 22, height information can be acquired during a time when a transmitted image cannot be acquired, thereby suppressing an increase in the overall examination time due to processing for acquiring height information.
  • the electronic board is coated with a resist or the like, and when height information is obtained from above the resist or the like (height information is obtained by irradiating the resist or the like with laser light), there is variation in the thickness of the resist or the like, and therefore variation in the height information occurs.
  • the height information obtained by the height information acquisition unit 50 determines the search range in the cross-sectional image, and the selection of the cross-sectional image of the board inspection surface is made by comparing the cross-sectional image in the determined search range with the reference image, so there is no effect on the accuracy of the selection of the cross-sectional image of the board inspection surface.
  • height information is obtained at multiple positions within the field of view FOV of the inspected object 12, and height information within the field of view FOV (e.g., height information at the center of the field of view FOV) is calculated from these multiple height information, so that information regarding deviation from the reference surface within the field of view FOV due to warping or bending can be obtained with high accuracy, and the search range of the cross-sectional image can be determined more accurately.
  • the width of the search range of the cross-sectional image can be narrowed (fewer cross-sectional images are compared with the reference image), thereby shortening the time required to detect the substrate inspection surface, and as a result, the time required for the entire inspection can be shortened.
  • the substrate holding part 24 (test object 12) when acquiring height information at multiple positions on the test object 12, if the substrate holding part 24 (test object 12) is stopped relative to the height information acquisition part 50 each time the acquisition position is moved, the accuracy of the acquired height information is improved because no vibrations or the like are generated in the test object 12; however, when moving to the next measurement position, the substrate holding part 24 (test object 12) must be moved again relative to the height information acquisition part 50, which takes time to stop and start. Therefore, by acquiring height information at multiple positions while moving the height information acquisition part 50 and the substrate holding part 24 (test object 12) relative to each other, the time it takes to acquire the height information can be shortened.
  • the height information acquired by the height information acquisition unit 50 determines the range in which the cross-sectional images are searched, and the selection of the cross-sectional image of the substrate inspection surface is made by comparing the cross-sectional images in the determined search range with the reference image, so there is no effect on the selection of the cross-sectional image of the substrate inspection surface.
  • the height information acquisition unit 50 is disposed on the upper surface side of the inspected object 12.
  • the height information acquisition unit 50 is disposed on the upper surface side of the inspected object 12, it is located on the radiation generator 22 side, so that the height information acquisition unit 50 can be disposed in a position where it is not directly irradiated with radiation emitted from the radiation generator 22, thereby avoiding exposure to radiation.
  • the height information acquisition unit 50 may be disposed on the rear surface side of the inspected object 12 to acquire height information of the rear surface of the substrate of the inspected object 12.
  • the substrate of the inspected object 12 is flat, and the thickness of this substrate is known from information such as design.
  • the height information of the upper surface of the substrate can be calculated from the height information of the rear surface of the substrate of the inspected object 12. Even if the accuracy of the height information of the upper surface calculated from the height information of the rear surface of the substrate is low, as described above, the range in which the cross-sectional image is searched is determined, and the selection of the cross-sectional image of the substrate inspection surface is performed by comparing the cross-sectional image in the determined search range with the reference image, so there is no effect on the selection of the cross-sectional image of the substrate inspection surface.
  • the height information acquisition unit 50 is placed on the back surface of the substrate of the inspected object 12, the radiation emitted from the radiation generator 22 will directly irradiate the height information acquisition unit 50, resulting in exposure to radiation. In this way, the height information acquisition unit 50 can acquire height information from both the top surface and the back surface of the substrate of the inspected object 12, which increases the degree of freedom in the placement position of the height information acquisition unit 50 in the inspection device 1.
  • FIG. 7 shows a flow chart of a modified method of acquiring height information.
  • the image processing unit 35 of the control unit 10 acquires height information of the entire upper surface of the substrate of the object 12 (step S1001).
  • the substrate 12a of the object 12 is divided into regions indicated by dashed lines M, the substrate holding unit 24 is moved relative to the height information acquiring unit 50, and height information is acquired in each region.
  • the object 12 is moved from the upper left region to the right while acquiring height information in each region, and the object 12 is moved from the upper right region to the next lower step and moved leftward while acquiring height information in each region.
  • the acquired height information is stored in the memory unit 34 together with the coordinates on the substrate in the form of (X, Y, Z).
  • the image capture processing unit 35 of the control unit 10 applies a minimum value filter to the height information of each region to remove the height information of the components (step S1002).
  • the minimum value filter is a filter that compares the height information of the region of interest with the height information of the regions surrounding the region of interest, and converts the height information of the region of interest into height information with the smallest value. Since the components are attached to the top surface of the substrate, the height information of the components can be removed by applying this minimum value filter.
  • the image capture processing unit 35 of the control unit 10 applies an average value filter to the height information of each region to which the minimum value filter has been applied, and removes abnormal values.
  • the average value filter is a filter that calculates the average value between the good height information of interest and the height information of regions surrounding the interest, and changes the height information of the interest region to the average value. By applying the average value filter, it is possible to remove abnormal values.
  • the image capturing processing unit 35 of the control unit 10 calculates the height information of the center of each FOV from the height information of the area included in the FOV, for example by linear interpolation (step S1004), and ends the height information acquisition process.

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Abstract

Provided is an inspection device that determines a search range in a reconstructed image from height information pertaining to a body being inspected and, by comparing the reconstructed image (cross-sectional image) within the search range and a reference image, determines a cross-sectional image of an inspection subject.　A control device 10 of this inspection device 1, which has driving units (e.g., a substrate-holding-part-driving unit 18) that change the relative positions of a radiation generator 22, a body being inspected 12 held by a substrate-holding part 24, and a detector 26, as well as the relative positions of the body being inspected 12 and a height-information-acquiring unit 50, executes: a step for acquiring height information pertaining to the body being inspected 12 by using the height-information-acquiring unit 50; a step for generating a cross-sectional image of the body being inspected 12 from a transmission image of the body being inspected 12; a step for determining a prescribed height-direction range on the basis of the height information, and determining the cross-sectional image of an inspection subject from the cross-sectional image within this range; and a step for carrying out inspection on the basis of the cross-sectional image of the inspection subject.

Description

検査装置Inspection Equipment
　本発明は、検査装置に関する。 The present invention relates to an inspection device.
　電子基板において、はんだによる電子部品（例えばピン）と基板上の配線との接続状態（以下「はんだの接合状態」と呼ぶ）は、外観検査では判定が難しく、トモシンセス方式のＸ線検査装置が用いられる。このような検査装置においては、電子基板の表面（上面）の正確な位置に基づいて検査を行う必要があるため、電子基板の表面にレーザー光を照射し、その反射光から電子基板の表面の高さ情報を取得し、この高さ情報に基づいて反りや撓みの影響を排除する検査装置がある（例えば、特許文献1参照）。 In electronic circuit boards, the state of connection between electronic components (e.g., pins) and the wiring on the board by solder (hereinafter referred to as the "solder joint state") is difficult to determine by visual inspection, so tomosynthesis-type X-ray inspection equipment is used. With such inspection equipment, inspection must be performed based on the exact position of the surface (top surface) of the electronic circuit board, so there are inspection equipment that irradiate the surface of the electronic circuit board with laser light, obtain height information of the surface of the electronic circuit board from the reflected light, and eliminate the effects of warping and bending based on this height information (see, for example, Patent Document 1).
特開２０１１－１９１２１７号公報JP 2011-191217 A
　Ｘ線透過画像から３次元画像である再構成画像（断面画像）を生成してはんだの接合状態を検査するためには、電子基板の反りや撓みの情報を取得し、この情報に基づいて検査に用いられる断面画像（基板面の断面画像）を精度良く選択する必要がある。しかしながら、電子基板の表面には、レジスト等が塗布されていたり、電子部品等が取り付けられていたりするため、基板表面の高さの測定のためにレーザー光を照射する位置が制限される。例えば、基板上に電子部品等が取り付けられていないパッド面を設け、このパッド面にレーザー光を照射して高さが測定される。 In order to generate a three-dimensional reconstructed image (cross-sectional image) from an X-ray transmission image to inspect the state of solder joints, it is necessary to obtain information on the warping and bending of the electronic board and, based on this information, accurately select the cross-sectional image (cross-sectional image of the board surface) to be used for inspection. However, since the surface of the electronic board may be coated with a resist or have electronic components attached, the position at which the laser light can be irradiated to measure the height of the board surface is limited. For example, a pad surface on the board with no electronic components attached is provided, and the height is measured by irradiating this pad surface with laser light.
　一方、レーザー光を用いずに、検査対象である電子基板のＸ線透過画像から再構成画像を生成し、予め準備しておいた検査対象面を示す断面画像（基準画像）と、再構成画像（断面画像）とを比較して検査対象の断面画像を選択する方法がある。しかし、この方法では、精度良く検査対象の断面画像を選択できるが、再構成画像から目的の断面画像を選択するために、多くの断面画像と基準画像との比較処理をしなければならず、断面画像の選択の処理に時間がかかり、結果として検査全体の時間も長くなってしまう。特に、近年、Ｘ線透過画像を検出するための検出器の大型化や高解像度化が進み、断面画像毎のデータ量が増大しているため、検査対象の断面画像を選択するための処理も増加してしまう傾向にある。 On the other hand, there is a method that does not use laser light, but generates a reconstructed image from an X-ray transmission image of the electronic board to be inspected, and selects the cross-sectional image of the inspection target by comparing the reconstructed image (cross-sectional image) with a cross-sectional image (reference image) that shows the surface to be inspected that has been prepared in advance. However, while this method can select the cross-sectional image of the inspection target with high accuracy, it is necessary to compare many cross-sectional images with the reference image in order to select the desired cross-sectional image from the reconstructed image, which takes time to select the cross-sectional image and, as a result, increases the overall inspection time. In particular, in recent years, detectors for detecting X-ray transmission images have become larger and have higher resolution, increasing the amount of data per cross-sectional image, and so there is a tendency for the amount of processing required to select the cross-sectional image of the inspection target to also increase.
　本発明はこのような課題に鑑みてなされたものであり、検査対象である電子基板（被検査体）の高さ情報を取得し、この高さ情報に基づいて透過画像から生成された再構成画像における探索範囲を決定し、決定された探索範囲内の再構成画像（断面画像）と基準画像とを比較して検査対象の断面画像を決定するように構成された検査装置を提供することを目的とする。 The present invention has been made in consideration of these problems, and aims to provide an inspection device configured to acquire height information of an electronic board (inspected object) that is the object of inspection, determine a search range in a reconstructed image generated from a transmission image based on this height information, and compare the reconstructed image (cross-sectional image) within the determined search range with a reference image to determine the cross-sectional image of the inspection object.
　前記課題を解決するために、本発明に係る検査装置は、線源と、被検査体を保持する保持部と、検出器と、前記被検査体の高さ情報を取得する高さ情報取得部と、前記線源と前記保持部で保持された前記被検査体及び前記検出器との相対位置、及び、前記保持部で保持された前記被検査体と前記高さ情報取得部との相対位置を変化させる駆動部と、制御部と、を有し、前記制御部は、前記高さ情報取得部により前記被検査体の高さ情報を取得するステップと、前記駆動部により前記線源と前記保持部で保持された前記被検査体及び前記検出器とが所定の相対位置にあるときに、前記線源から放射され前記被検査体を透過した放射線を前記検出器で検出して取得した複数の前記被検査体の透過画像から前記被検査体の断面画像を生成するステップと、前記高さ情報に基づいて所定の高さ方向の範囲を決定し、前記範囲内の前記断面画像から検査対象の断面画像を決定するステップと、前記検査対象の断面画像に基づいて検査をするステップと、を実行する。 In order to solve the above problem, the inspection device according to the present invention has a radiation source, a holding unit that holds an object to be inspected, a detector, a height information acquisition unit that acquires height information of the object to be inspected, a drive unit that changes the relative positions of the radiation source, the object to be inspected held by the holding unit, and the detector, and the relative positions of the object to be inspected held by the holding unit and the height information acquisition unit, and a control unit, and the control unit executes the steps of acquiring height information of the object to be inspected by the height information acquisition unit, generating cross-sectional images of the object to be inspected from a plurality of transmission images of the object to be inspected obtained by detecting radiation emitted from the radiation source and passing through the object to be inspected by the detector when the radiation source, the object to be inspected held by the holding unit, and the detector are in a predetermined relative position by the drive unit, determining a predetermined range in the height direction based on the height information, determining a cross-sectional image of the object to be inspected from the cross-sectional images within the range, and performing an inspection based on the cross-sectional images of the object to be inspected.
　本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、前記駆動部により前記保持部で保持された前記被検査体を前記高さ情報取得部に対して相対移動させ、前記高さ情報取得部により前記被検査体の基板面の複数の位置の高さ情報を取得させ、前記複数の位置の高さ情報から、当該複数の位置を含む領域の所定の位置の基板面の高さ情報を決定することが望ましい。 In the step of acquiring the height information, the control unit of the inspection device according to the present invention desirably moves the object to be inspected held by the holding unit relative to the height information acquisition unit using the drive unit, acquires height information of multiple positions on the substrate surface of the object to be inspected using the height information acquisition unit, and determines height information of the substrate surface at a predetermined position in an area including the multiple positions from the height information of the multiple positions.
　また、本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、前記駆動部により前記保持部で保持された前記被検査体を前記高さ情報取得部に対して相対移動させ、前記高さ情報取得部により前記被検査体の複数の位置の高さ情報を取得させ、前記複数の位置の高さ情報から、演算により基板面以外の高さ情報を除去し、当該複数の位置を含む領域の所定の位置の基板面の高さ情報を決定することが望ましい。 Furthermore, in the step of acquiring the height information, the control unit of the inspection device according to the present invention desirably moves the object to be inspected held by the holding unit relative to the height information acquisition unit using the drive unit, acquires height information of multiple positions on the object to be inspected using the height information acquisition unit, removes height information other than that of the substrate surface from the height information of the multiple positions by calculation, and determines height information of the substrate surface at a predetermined position in an area including the multiple positions.
　また、本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、前記駆動部により前記高さ情報取得部と前記保持部で保持された前記被検査体との相対位置を変化させながら、前記複数の位置の高さ情報を取得することが望ましい。 Furthermore, in the step of acquiring the height information, it is preferable that the control unit of the inspection device according to the present invention acquires the height information at the multiple positions while changing the relative position between the height information acquisition unit and the test object held by the holding unit using the drive unit.
　また、本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、予め取得された前記被検査体の画像データから、前記被検査体の基板面の位置を取得し、前記高さ情報取得部により、取得された位置の高さ情報を取得することが望ましい。 Furthermore, in the step of acquiring the height information, the control unit of the inspection device according to the present invention preferably acquires the position of the substrate surface of the object to be inspected from image data of the object to be inspected that has been acquired in advance, and acquires the height information of the acquired position by the height information acquisition unit.
　また、本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、前記画像データにおける前記被検査体の色情報から前記基板面の位置を取得することが望ましい。 Furthermore, in the step of acquiring the height information, it is desirable for the control unit of the inspection device according to the present invention to acquire the position of the substrate surface from color information of the object to be inspected in the image data.
　また、本発明に係る検査装置の前記制御部は、前記高さ情報を取得するステップにおいて、前記駆動部により前記高さ情報取得部に対する前記保持部で保持された前記被検査体の相対位置を変化させながら、前記複数の位置の高さ情報を取得し、前記複数の位置の高さ情報から、前記被検査体の基板面の高さ情報を決定することが望ましい。 Furthermore, in the step of acquiring the height information, the control unit of the inspection device according to the present invention preferably acquires height information of the multiple positions while changing the relative position of the object to be inspected held by the holding unit with respect to the height information acquisition unit using the drive unit, and determines height information of the substrate surface of the object to be inspected from the height information of the multiple positions.
　また、本発明に係る検査装置の前記高さ情報取得部は、前記被検査体の基板の上面又は裏面における前記高さ情報を取得する変位計であることが望ましい。 In addition, it is preferable that the height information acquisition unit of the inspection device according to the present invention is a displacement meter that acquires the height information on the top or bottom surface of the substrate of the object to be inspected.
　本発明に係る検査装置によれば、被検査体の透過画像を取得する前に、高さ測定部により被検査体の高さ情報を取得し、その後、透過画像を取得して被検査体の再構成画像を生成し、高さ測定部による高さ情報に基づいて、再構成画像における検査面の探索範囲を決定し、この範囲で被検査体の断面画像と基準画像とを比較して検査面の断面画像を選択するため、再構成画像（断面画像）のうち、検査面の断面画像が含まれる範囲を特定してその特定した範囲内での比較となるため、全ての断面画像と比較する場合と比べて、検査面の断面画像を選択する時間を短くすることができる。 　In the inspection device according to the present invention, before acquiring a transmission image of the object to be inspected, the height measurement unit acquires height information of the object to be inspected, and then the transmission image is acquired to generate a reconstructed image of the object to be inspected. Based on the height information from the height measurement unit, the search range of the inspection surface in the reconstructed image is determined, and the cross-sectional image of the object to be inspected is compared with the reference image within this range to select the cross-sectional image of the inspection surface. Therefore, since the range within the reconstructed image (cross-sectional image) that includes the cross-sectional image of the inspection surface is identified and comparison is performed within this identified range, the time required to select the cross-sectional image of the inspection surface can be shortened compared to when comparing with all cross-sectional images.
本発明の実施形態に係る検査装置の構成を説明するための説明図である。FIG. 1 is an explanatory diagram for explaining a configuration of an inspection device according to an embodiment of the present invention. 上記検査装置の制御部の各機能ブロックを説明するための説明図である。FIG. 2 is an explanatory diagram for explaining each functional block of a control unit of the inspection device. 上記検査装置における検査の処理を説明するためのフローチャートである。4 is a flowchart for explaining an inspection process in the inspection device. 上記検査装置で検査される被検査体の一例を示す説明図である。FIG. 2 is an explanatory diagram showing an example of an object to be inspected by the inspection device. 基板検査面検出処理を説明するためのフローチャートである。10 is a flowchart for explaining a substrate inspection surface detection process. 高さ情報と再構成画像における探索範囲との関係を説明するための説明図である。11 is an explanatory diagram for explaining the relationship between height information and a search range in a reconstructed image. FIG. 高さ情報の取得方法の変形例を説明するためのフローチャートである。13 is a flowchart for explaining a modified example of a method for acquiring height information. 被検査体の基板の上面の全面の高さ情報を取得するときの測定位置の一例を示す説明図である。10 is an explanatory diagram showing an example of a measurement position when acquiring height information of the entire surface of the upper surface of a substrate of an object to be inspected. FIG.
　以下、本発明の好ましい実施形態について図面を参照して説明する。図１に示すように、本実施形態に係る検査装置１は、パーソナルコンピュータ（ＰＣ）等の処理装置で構成される制御部１０、モニタ１１、及び、撮像部３２を有して構成されている。また、撮像部３２は、更に、線質変更部１４、放射線発生器駆動部１６、基板保持部駆動部１８、検出器駆動部２０、放射線発生器２２、基板保持部２４、検出器２６、及び、高さ情報取得部５０を有している。 Below, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the inspection device 1 according to this embodiment is configured to have a control unit 10, which is made up of a processing device such as a personal computer (PC), a monitor 11, and an imaging unit 32. The imaging unit 32 further has a radiation quality change unit 14, a radiation generator drive unit 16, a substrate holder drive unit 18, a detector drive unit 20, a radiation generator 22, a substrate holder 24, a detector 26, and a height information acquisition unit 50.
　放射線発生器２２は、Ｘ線等の放射線を発生させる装置（線源）であり、例えば加速させた電子をタングステンやダイアモンド等のターゲットに衝突させることで放射線を発生するものである。なお、本実施形態における放射線は、Ｘ線の場合について説明するが、これに限定されるものではない。例えば、放射線は、アルファ線、ベータ線、ガンマ線、紫外線、可視光、赤外線でもよい。また、放射線は、マイクロ波やテラヘルツ波でもよい。 The radiation generator 22 is a device (ray source) that generates radiation such as X-rays, and generates radiation by colliding accelerated electrons with a target such as tungsten or diamond. Note that, although the radiation in this embodiment is described as being X-rays, the radiation is not limited to this. For example, the radiation may be alpha rays, beta rays, gamma rays, ultraviolet rays, visible light, or infrared rays. The radiation may also be microwaves or terahertz waves.
　基板保持部２４は、被検査体１２である電子基板を保持する。基板保持部２４に保持された被検査体１２に放射線発生器２２で発生させた放射線を照射し、被検査体１２を透過した放射線を検出器２６で検出して画像として撮像する。以下、検出器２６で撮像された被検査体１２の放射線透過画像を「透過画像」と呼ぶ。なお、後述するように、本実施形態においては、被検査体１２である電子基板を保持した基板保持部２４と検出器２６とを放射線発生器２２に対して相対移動させて複数の透過画像を取得して、それらの透過画像から再構成画像（断面画像）を生成する。 The board holding unit 24 holds the electronic board, which is the object under inspection 12. The object under inspection 12 held by the board holding unit 24 is irradiated with radiation generated by the radiation generator 22, and the radiation that has passed through the object under inspection 12 is detected by the detector 26 to capture an image. Hereinafter, the radiation transmission image of the object under inspection 12 captured by the detector 26 will be referred to as a "transmission image." As will be described later, in this embodiment, the board holding unit 24, which holds the electronic board, which is the object under inspection 12, and the detector 26 are moved relative to the radiation generator 22 to obtain multiple transmission images, and a reconstructed image (cross-sectional image) is generated from these transmission images.
　検出器２６で撮像された透過画像は、制御部１０に送られ、例えば、フィルタ補正逆投影法（Filtered-Backprojection法（ＦＢＰ法））等の既知の技術を用いて、接合部分のはんだの立体形状を含む画像に再構成される。そして、再構成された画像や透過画像は、制御部１０内のストレージ（例えば、後述する記憶部３４）や、図示しない外部のストレージに記憶される。以下、透過画像に基づいて接合部分のはんだの立体形状を含む３次元画像に再構成された画像を「再構成画像」と呼ぶ。また、再構成画像から任意の断面を切り出した画像を「断面画像」と呼ぶ。このような再構成画像及び断面画像はモニタ１１に出力される。なお、モニタ１１には再構成画像や断面画像のみならず、後述するはんだの接合状態の検査結果等も表示される。なお、本実施形態における再構成画像は、上述したように、検出器２６で撮像された平面画像（透過画像）から再構成されるため「プラナーＣＴ」とも呼ばれる。 The transmission image captured by the detector 26 is sent to the control unit 10, and is reconstructed into an image including the three-dimensional shape of the solder at the joint using a known technique such as the Filtered Backprojection (FBP) method. The reconstructed image and the transmission image are stored in a storage unit (e.g., the storage unit 34 described later) in the control unit 10 or in an external storage unit (not shown). Hereinafter, an image reconstructed into a three-dimensional image including the three-dimensional shape of the solder at the joint based on the transmission image is referred to as a "reconstructed image". An image obtained by cutting out an arbitrary cross section from the reconstructed image is referred to as a "cross-sectional image". Such a reconstructed image and cross-sectional image are output to the monitor 11. The monitor 11 displays not only the reconstructed image and the cross-sectional image, but also the inspection results of the solder joint state described later. The reconstructed image in this embodiment is also called a "planar CT" because it is reconstructed from a planar image (transmission image) captured by the detector 26 as described above.
　線質変更部１４は、放射線発生器２２で発生される放射線の線質を変更する。放射線の線質は、ターゲットに衝突させる電子を加速するために印加する電圧（以下「管電圧」と呼ぶ）や、電子の数を決定する電流（以下「管電流」と呼ぶ）によって定まる。線質変更部１４は、これら管電圧と管電流とを制御する装置である。この線質変更部１４は変圧器や整流器等、既知の技術を用いて実現できる。 The radiation quality change unit 14 changes the radiation quality generated by the radiation generator 22. The radiation quality is determined by the voltage (hereafter referred to as "tube voltage") applied to accelerate the electrons to be collided with the target, and the current (hereafter referred to as "tube current") that determines the number of electrons. The radiation quality change unit 14 is a device that controls the tube voltage and tube current. This radiation quality change unit 14 can be realized using known technology such as a transformer or rectifier.
　ここで、放射線の線質は、放射線の輝度と硬さ（放射線のスペクトル分布）とで定まる。管電流を大きくすればターゲットに衝突する電子の数が増え、発生する放射線の光子の数も増える。その結果、放射線の輝度が高くなる。例えば、コンデンサ等の部品の中には他の部品と比較して厚みがあるものもあり、これらの部品の透過画像を撮像するには輝度の高い放射線を照射する必要がある。このような場合に管電流を調整することで放射線の輝度を調整する。また、管電圧を高くすると、ターゲットに衝突する電子のエネルギーが大きくなり、発生する放射線のエネルギー（スペクトル）が大きくなる。一般に、放射線のエネルギーが大きいほど物質の貫通力が大きくなり、物質に吸収されにくくなる。そのような放射線を用いて撮像した透過画像はコントラストが低くなる。このため、管電圧は透過画像のコントラストを調整するのに利用できる。 Here, the quality of radiation is determined by the brightness and hardness of the radiation (spectral distribution of radiation). Increasing the tube current increases the number of electrons that collide with the target, and the number of radiation photons generated. As a result, the brightness of the radiation increases. For example, some components such as capacitors are thicker than other components, and in order to capture a transmission image of these components, it is necessary to irradiate them with radiation of high brightness. In such cases, the brightness of the radiation is adjusted by adjusting the tube current. Also, increasing the tube voltage increases the energy of the electrons that collide with the target, and the energy (spectrum) of the generated radiation increases. In general, the greater the energy of the radiation, the greater its penetrating power into materials, and the less likely it is to be absorbed by materials. A transmission image captured using such radiation has low contrast. For this reason, the tube voltage can be used to adjust the contrast of a transmission image.
　放射線発生器駆動部１６は、図示しないモータ等の駆動機構を有しており、放射線発生器２２をその焦点を通る軸Ａ（放射線発生器２２から放射される放射線の放射方向の中心を通る軸（光軸）であって、この軸の方向を「Ｚ軸方向」とする）に沿って上下に移動させることができる。これにより放射線発生器２２と基板保持部２４に保持される被検査体（電子基板）１２との距離を変えて照射野を変更し、検出器２６で撮像される透過画像の拡大率を変更することが可能となる。なお、放射線発生器２２のＺ軸方向の位置は、図示しない発生器位置検出部により検出され、制御部１０に出力される。 The radiation generator driving unit 16 has a driving mechanism such as a motor (not shown) and can move the radiation generator 22 up and down along axis A passing through its focal point (axis (optical axis) passing through the center of the radiation direction of the radiation emitted from the radiation generator 22, the direction of this axis being referred to as the "Z-axis direction"). This makes it possible to change the distance between the radiation generator 22 and the inspected object (electronic board) 12 held by the board holding unit 24 to change the irradiation field and change the magnification ratio of the transmitted image captured by the detector 26. The position of the radiation generator 22 in the Z-axis direction is detected by a generator position detection unit (not shown) and output to the control unit 10.
　検出器駆動部２０も図示しないモータ等の駆動機構を有しており、検出器回転軌道３０に沿って検出器２６を回転移動させる。また、基板保持部駆動部１８も図示しないモータ等の駆動機構を有しており、基板回転軌道２８が設けられた平面上を、基板保持部２４を平行移動させる。また、基板保持部２４は、検出器２６の回転移動と連動して、基板回転軌道２８上を回転移動する構成となっている。これにより、基板保持部２４が保持する被検査体１２と放射線発生器２２との相対的な位置関係を変更させながら、投射方向及び投射角度が異なる複数の透過画像を撮像することが可能となる。なお、本実施形態に係る検査装置１は、検出器２６の放射線を検出する領域の大きさと、放射線発生器２２、被検査体１２（基板保持部２４）及び検出器２６の相対位置により、被検査体１２上の透過画像を取得することができる領域が決定される。この透過画像を取得することができる領域を「ＦＯＶ（視野）」と呼ぶ。 The detector driving unit 20 also has a driving mechanism such as a motor (not shown) and rotates the detector 26 along the detector rotation track 30. The substrate holding unit driving unit 18 also has a driving mechanism such as a motor (not shown) and moves the substrate holding unit 24 in parallel on the plane on which the substrate rotation track 28 is provided. The substrate holding unit 24 is configured to rotate on the substrate rotation track 28 in conjunction with the rotation of the detector 26. This makes it possible to capture multiple transmission images with different projection directions and projection angles while changing the relative positional relationship between the test object 12 held by the substrate holding unit 24 and the radiation generator 22. In the inspection device 1 according to this embodiment, the area on the test object 12 where a transmission image can be acquired is determined by the size of the area where the detector 26 detects radiation and the relative positions of the radiation generator 22, the test object 12 (substrate holding unit 24), and the detector 26. The area where this transmission image can be acquired is called the "FOV (field of view)".
　基板回転軌道２８と検出器回転軌道３０との回転半径は固定ではなく、自由に変更できる構成となっている。これにより、被検査体１２の基板やこの基板に取り付けられている部品に照射する放射線の照射角度を任意に変更することが可能となる。なお、基板回転軌道２８及び検出器回転軌道３０の軌道面は、上述したＺ軸方向と直交しており、この軌道面において直交する方向をＸ軸方向及びＹ軸方向とすると、基板保持部２４のＸ軸方向及びＹ軸方向の位置は、図示しない基板位置検出部で検出されて制御部１０に出力され、検出器２６のＸ軸方向及びＹ軸方向の位置は、図示しない検出器位置検出部で検出されて制御部１０に出力される。 The rotation radius of the substrate rotation orbit 28 and the detector rotation orbit 30 is not fixed, but can be freely changed. This makes it possible to arbitrarily change the irradiation angle of the radiation irradiated to the substrate of the inspected object 12 and the components attached to this substrate. The orbital plane of the substrate rotation orbit 28 and the detector rotation orbit 30 is perpendicular to the Z-axis direction described above, and if the directions perpendicular to this orbital plane are the X-axis direction and the Y-axis direction, the positions of the substrate holding part 24 in the X-axis direction and the Y-axis direction are detected by a substrate position detection part (not shown) and output to the control part 10, and the positions of the detector 26 in the X-axis direction and the Y-axis direction are detected by a detector position detection part (not shown) and output to the control part 10.
　高さ情報取得部５０は、基板保持部２４の上方に配置され、この基板保持部２４で保持された被検査体１２である電子基板の上面の高さ情報を取得する変位計で構成されている。この変位計としては、例えば、電子基板の上面にレーザー光を照射し、その反射光を受光することで電子基板の上面のＺ軸方向の位置（高さ）を検出するように構成することができるが、この構成に限定されることはない。例えば、電子基板の上面にプローブを接触させて高さ情報を取得するように構成してもよい。なお、以降の説明における高さ情報取得部５０は、上述したように、レーザー光を用いて高さ情報を取得する変位計であるとする。被検査体１２を構成する基板に反りがなく、又、基板保持部２４で保持されたときに撓みが発生していない理想的な条件であれば、基板の上面（後述する基板検査面）は平面であり、そのＺ方向の位置は電子基板の設計等の情報から既知となる（この理想的な基板検査面を「基準面」と呼ぶ）。しかしながら、実際に検査の対象となる被検査体（電子基板）１２には反りや撓みが発生するため、基板検査面は基準面からずれている。そのため、制御部１０は、高さ情報取得部５０により、基板保持部２４に保持されている被検査体１２の基板の上面（基板検査面）の高さに関する情報（以下「高さ情報」と呼ぶ）を取得し、基準面からのずれ量を得ることができる。この高さ情報は、例えば、検査装置１の所定の位置を原点としたＸＹＺ座標系で管理されるが、座標系はこれに限定されることはない。 The height information acquisition unit 50 is disposed above the board holding unit 24 and is configured as a displacement meter that acquires height information of the top surface of the electronic board, which is the object to be inspected 12 held by the board holding unit 24. This displacement meter can be configured, for example, to detect the position (height) of the top surface of the electronic board in the Z-axis direction by irradiating the top surface of the electronic board with laser light and receiving the reflected light, but is not limited to this configuration. For example, it may be configured to acquire height information by contacting a probe with the top surface of the electronic board. Note that the height information acquisition unit 50 in the following description is assumed to be a displacement meter that acquires height information using laser light, as described above. Under ideal conditions, the board constituting the object to be inspected 12 is not warped and does not bend when held by the board holding unit 24, the top surface of the board (board inspection surface described later) is flat, and its position in the Z direction is known from information such as the design of the electronic board (this ideal board inspection surface is called the "reference surface"). However, warping and bending occur in the object to be inspected (electronic board) 12, so the board inspection surface is shifted from the reference surface. Therefore, the control unit 10 can obtain information (hereinafter referred to as "height information") regarding the height of the upper surface (substrate inspection surface) of the substrate of the inspected object 12 held by the substrate holding unit 24 through the height information acquisition unit 50, and obtain the amount of deviation from the reference surface. This height information is managed, for example, in an XYZ coordinate system with a predetermined position of the inspection device 1 as the origin, but the coordinate system is not limited to this.
　制御部１０は、上述した検査装置１の全動作を制御する。以下、制御部１０の主な機能について図２を用いて説明する。なお、図示されていないが、制御部１０にはキーボードおよびマウスなどの入力装置が接続されている。 The control unit 10 controls all operations of the inspection device 1 described above. Below, the main functions of the control unit 10 are explained using FIG. 2. Although not shown, input devices such as a keyboard and a mouse are connected to the control unit 10.
　制御部１０は、記憶部３４、撮像処理部３５、断面画像生成部３６、基板検査面検出部３８、疑似断面画像生成部４０、及び検査部４２を含む。なお、図示しないが制御部１０の撮像処理部３５は線質変更部１４、放射線発生器駆動部１６、基板保持部駆動部１８、及び検出器駆動部２０の作動を制御する撮像制御部の機能も有している。また、これらの各機能ブロックは、各種演算処理を実行するＣＰＵ、データの格納やプログラム実行のためのワークエリアとして利用されるＲＡＭなどのハードウェア、およびソフトウェアの連携によって実現される。したがって、これらの機能ブロックはハードウェアおよびソフトウェアの組み合わせによって様々な形で実現することができる。 The control unit 10 includes a memory unit 34, an imaging processing unit 35, a cross-sectional image generating unit 36, a board inspection surface detecting unit 38, a pseudo cross-sectional image generating unit 40, and an inspection unit 42. Although not shown, the imaging processing unit 35 of the control unit 10 also has the function of an imaging control unit that controls the operation of the radiation quality changing unit 14, the radiation generator driving unit 16, the board holding unit driving unit 18, and the detector driving unit 20. Furthermore, each of these functional blocks is realized by the cooperation of hardware, such as a CPU that executes various arithmetic processes, and a RAM that is used as a work area for storing data and executing programs, and software. Therefore, these functional blocks can be realized in various ways by combining hardware and software.
　記憶部３４は、被検査体１２である電子基板の透過画像を撮像するための撮像条件や、電子基板の設計等の情報を記憶する。記憶部３４はまた、電子基板の透過画像や再構成画像（断面画像、疑似断面画像）、及び後述する検査部４２の検査結果等を記憶する。記憶部３４はさらに、放射線発生器駆動部１６、基板保持部駆動部１８及び検出器駆動部２０を駆動するための情報（例えば、放射線発生器駆動部１６が放射線発生器２２を駆動する速度、基板保持部駆動部１８が基板保持部２４を駆動する速度および検出器駆動部２０が検出器２６を駆動する速度、等）も格納されている。 The memory unit 34 stores information such as imaging conditions for capturing a transmission image of the electronic board, which is the inspected object 12, and the design of the electronic board. The memory unit 34 also stores transmission images and reconstructed images (cross-sectional images, pseudo cross-sectional images) of the electronic board, as well as inspection results of the inspection unit 42, which will be described later. The memory unit 34 also stores information for driving the radiation generator driving unit 16, the board holder driving unit 18, and the detector driving unit 20 (e.g., the speed at which the radiation generator driving unit 16 drives the radiation generator 22, the speed at which the board holder driving unit 18 drives the board holder 24, and the speed at which the detector driving unit 20 drives the detector 26, etc.).
　撮像処理部３５は、放射線発生器駆動部１６、基板保持部駆動部１８及び検出器駆動部２０により、放射線発生器２２、基板保持部２４及び検出器２６を駆動させて、基板保持部２４により保持された被検査体の透過画像を撮像し、透過画像から再構成画像（断面画像）を生成する。この撮像処理部３５による透過画像の撮像及び再構成画像（断面画像）の生成方法については、後述する。また、撮像処理部３５は高さ情報取得部５０の作動も制御するように構成されている。 The imaging processing unit 35 drives the radiation generator 22, substrate holding unit 24, and detector 26 using the radiation generator driving unit 16, substrate holding unit driving unit 18, and detector driving unit 20 to capture a transmission image of the object to be inspected held by the substrate holding unit 24, and generates a reconstructed image (cross-sectional image) from the transmission image. The method of capturing the transmission image and generating the reconstructed image (cross-sectional image) by this imaging processing unit 35 will be described later. The imaging processing unit 35 is also configured to control the operation of the height information acquisition unit 50.
　断面画像生成部３６は、記憶部３４から取得した複数の透過画像に基づいて、断面画像（再構成画像）を生成する。これは、例えばＦＢＰ法や最尤推定法等、既知の技術を用いて実現できる。再構成アルゴリズムが異なると、得られる再構成画像の性質や再構成に要する時間も異なる。そこで、あらかじめ複数の再構成アルゴリズムやアルゴリズムに用いられるパラメータを用意しておき、ユーザに選択させる構成としてもよい。これにより、再構成に要する時間が短くなることを優先したり、時間はかかっても画質の良さを優先したりするなどの選択の自由度をユーザに提供することができる。生成した断面画像の各々は、各断面画像のＺ軸方向の位置や、断面画像内の画素のＸ軸方向及びＹ軸方向の位置（座標）を決定する情報等の属性情報とともに記憶部３４に出力し、この記憶部３４に記憶される。 The cross-sectional image generating unit 36 generates a cross-sectional image (reconstructed image) based on the multiple transmission images acquired from the storage unit 34. This can be achieved using known techniques, such as the FBP method or the maximum likelihood estimation method. Different reconstruction algorithms result in different properties of the reconstructed image and different times required for reconstruction. Therefore, multiple reconstruction algorithms and parameters used in the algorithms may be prepared in advance and the user may select one. This provides the user with the freedom to choose, such as prioritizing a shorter reconstruction time or prioritizing better image quality even if it takes more time. Each of the generated cross-sectional images is output to the storage unit 34 along with attribute information, such as information that determines the position of each cross-sectional image in the Z-axis direction and the positions (coordinates) of pixels in the cross-sectional image in the X-axis direction and the Y-axis direction, and is stored in the storage unit 34.
　基板検査面検出部３８は、断面画像生成部３６が生成した複数の断面画像の中から、電子基板上の検査の対象となる面（例えば、電子基板の表面）を映し出している画像（断面画像）を特定する。以後、電子基板の検査面を映し出している断面画像を「検査面画像」と呼ぶ。基板検査面検出部３８は、上述した高さ情報取得部５０により取得された高さ情報に基づいて検査面画像を特定するように構成されている。検査面画像の特定方法については後述する。 The board inspection surface detection unit 38 identifies an image (cross-sectional image) showing the surface to be inspected on the electronic board (e.g., the surface of the electronic board) from among the multiple cross-sectional images generated by the cross-sectional image generation unit 36. Hereinafter, a cross-sectional image showing the inspection surface of the electronic board is referred to as an "inspection surface image." The board inspection surface detection unit 38 is configured to identify the inspection surface image based on the height information acquired by the height information acquisition unit 50 described above. The method of identifying the inspection surface image will be described later.
　疑似断面画像生成部４０は、断面画像生成部３６が生成した断面画像について、連続する所定枚数の断面画像を積み上げることにより、断面画像よりも厚い基板の領域を画像化する。積み上げる断面画像の枚数は、断面画像が映し出す基板の領域の厚さ（以後、「スライス厚」という。）と、疑似断面画像のスライス厚とによって定める。例えば、断面画像のスライス厚が５０μｍで、疑似断面画像としてＢＧＡのはんだボール（以後単に「はんだ」という。）の高さ（例えば５００μｍ）をスライス厚としようとするならば、５００／５０＝１０枚の断面画像を積み上げればよい。この際、はんだの位置を特定するために、基板検査面検出部３８が特定した検査面画像が用いられる。 The pseudo cross-sectional image generating unit 40 images the area of the board that is thicker than the cross-sectional image by stacking a predetermined number of consecutive cross-sectional images of the cross-sectional images generated by the cross-sectional image generating unit 36. The number of cross-sectional images to be stacked is determined by the thickness of the area of the board that is shown by the cross-sectional image (hereinafter referred to as the "slice thickness") and the slice thickness of the pseudo cross-sectional image. For example, if the slice thickness of the cross-sectional image is 50 μm and the height (e.g., 500 μm) of a BGA solder ball (hereinafter simply referred to as "solder") is to be the slice thickness of the pseudo cross-sectional image, then 500/50 = 10 cross-sectional images should be stacked. At this time, the inspection surface image identified by the board inspection surface detection unit 38 is used to identify the position of the solder.
　検査部４２は、断面画像生成部３６が生成した断面画像、基板検査面検出部３８が特定した検査面画像、及び疑似断面画像生成部４０が生成した疑似断面画像に基づいて、はんだの接合状態を検査する。電子基板と部品とを接合するはんだは基板検査面付近にあるので、検査面画像及び検査面画像に対して放射線発生器２２側の領域を映し出している断面画像を検査することで、はんだが基板と部品とを適切に接合しているか否かが判断できる。 The inspection unit 42 inspects the solder joint condition based on the cross-sectional image generated by the cross-sectional image generation unit 36, the inspection surface image identified by the board inspection surface detection unit 38, and the pseudo cross-sectional image generated by the pseudo cross-sectional image generation unit 40. Since the solder that joins the electronic board and the component is located near the board inspection surface, by inspecting the inspection surface image and the cross-sectional image that shows the area on the radiation generator 22 side of the inspection surface image, it is possible to determine whether the solder is properly joining the board and the component.
　ここで、「はんだの接合状態」とは、電子基板と部品とがはんだにより接合し、適切な導電経路が生成されているか否かのことをいう。はんだの接合状態の検査には、ブリッジ検査、溶融状態検査、及びボイド検査が含まれる。「ブリッジ（ｂｒｉｄｇｅ）」とは、はんだが接合することにより生じた導体間の好ましくない導電経路のことをいう。また、「溶融状態」とは、はんだの溶融不足により、電子基板と部品との間の接合が不足しているか否かの状態、いわゆる「浮き」か否かの状態をいう。「ボイド（ｖｏｉｄ）」とは、はんだ接合部内の気泡によるはんだ接合の不具合のことをいう。したがって検査部４２は、ブリッジ検査部４４、溶融状態検査部４６、及びボイド検査部４８を含む。 Here, "solder joint condition" refers to whether or not an appropriate conductive path is formed when the electronic board and the component are joined by solder. Inspection of the solder joint condition includes bridge inspection, molten state inspection, and void inspection. "Bridge" refers to an undesirable conductive path between conductors caused by solder joining. "Melted state" refers to a state in which the joint between the electronic board and the component is insufficient due to insufficient melting of the solder, that is, whether or not there is a so-called "floating" state. "Void" refers to a defect in the solder joint caused by air bubbles in the solder joint. Therefore, the inspection unit 42 includes a bridge inspection unit 44, a molten state inspection unit 46, and a void inspection unit 48.
　ブリッジ検査部４４、溶融状態検査部４６、及びボイド検査部４８の動作の詳細は後述するが、ブリッジ検査部４４およびボイド検査部４８は、疑似断面画像生成部４０が生成した疑似断面画像に基づいてそれぞれブリッジおよびボイドの検査をし、溶融状態検査部４６は基板検査面検出部３８が特定した検査面画像に基づいてはんだの溶融状態を検査する。なお、ブリッジ検査部４４、溶融状態検査部４６、及びボイド検査部４８における検査結果は記憶部３４に記憶される。 The operation of the bridge inspection unit 44, molten state inspection unit 46, and void inspection unit 48 will be described in detail later, but the bridge inspection unit 44 and void inspection unit 48 inspect bridges and voids, respectively, based on the pseudo cross-sectional image generated by the pseudo cross-sectional image generation unit 40, and the molten state inspection unit 46 inspects the molten state of the solder based on the inspection surface image identified by the board inspection surface detection unit 38. The inspection results in the bridge inspection unit 44, molten state inspection unit 46, and void inspection unit 48 are stored in the memory unit 34.
　図３は基板検査面の高さ情報の取得、透過画像の撮像及び再構成画像（断面画像）の生成、並びに、検査面画像の特定からはんだの接合状態を検査するまでの流れを示したフローチャートである。本フローチャートにおける処理は、例えば、制御部１０が図示しない入力装置から検査開始の指示を受け付けたときに開始する。 FIG. 3 is a flowchart showing the process from obtaining height information on the substrate inspection surface, taking a transmitted image and generating a reconstructed image (cross-sectional image), to identifying the inspection surface image and inspecting the solder joint condition. The process in this flowchart starts, for example, when the control unit 10 receives an instruction to start the inspection from an input device (not shown).
　検査が開始されると、制御部１０の撮像処理部３５は、図３に示すように、まず、高さ情報取得部５０により被検査体１２の基板検査面（電子部品が取り付けられている基板の上面）の高さ情報を取得する（ステップＳ１００）。被検査体１２の基板検査面の高さ情報は、高さ情報取得部５０が固定して配置されているときは、基板保持部２４により被検査体１２を移動させて、被検査体１２上の所望の位置の高さ情報（基板検査面の高さ情報）を取得する。あるいは、高さ情報取得部５０が移動可能に構成されているときは、この高さ情報取得部５０を移動させて被検査体１２上の所望の位置の高さ情報を取得する。ここで、取得された高さ情報は、ＸＹ平面上の位置（Ｘ，Ｙ）と、その位置での高さ（Ｚ）で構成され、例えば、（Ｘ，Ｙ，Ｚ）として視野ＦＯＶと対応付けられて記憶部３４に記憶される。 When the inspection is started, the image processing unit 35 of the control unit 10 first acquires height information of the board inspection surface (the upper surface of the board on which electronic components are attached) of the inspected object 12 by the height information acquisition unit 50 (step S100), as shown in FIG. 3. When the height information acquisition unit 50 is fixedly arranged, the height information of the board inspection surface of the inspected object 12 is acquired by moving the inspected object 12 by the board holding unit 24 to acquire height information of a desired position on the inspected object 12 (height information of the board inspection surface). Alternatively, when the height information acquisition unit 50 is configured to be movable, the height information of a desired position on the inspected object 12 is acquired by moving the height information acquisition unit 50. Here, the acquired height information is composed of a position (X, Y) on the XY plane and a height (Z) at that position, and is stored in the memory unit 34 in association with the field of view FOV as (X, Y, Z), for example.
　図４は、検査装置１で検査される電子基板である被検査体１２の一例を示している。この被検査体１２は、基板１２上に電子部品１２ｂ～１２ｆが取り付けられている。また、破線の矩形は視野ＦＯＶを示している。制御部１０の撮像処理部３５は、視野ＦＯＶにおける基板１２ａの上面の高さ情報として、中心Ｏの高さ情報を高さ情報取得部５０で測定してもよいし、視野ＦＯＶの複数の箇所の高さ情報（例えば、図４では視野ＦＯＶの四隅Ｐ１～Ｐ４の高さ情報）を測定し、これらの高さ情報から線形補完等により視野ＦＯＶの中心Ｏの高さ情報を算出してもよい。例えば、視野ＦＯＶの中心Ｏに電子部品が配置されているときは（図１の場合は電子部品１２ｂが配置されている）、視野ＦＯＶ内で電子部品が配置されておらず、高さ情報取得部５０により基板１２ａの上面を直接測定する（高さ情報取得部５０から基板１２ａの上面に直接レーザー光を照射できる部分の高さ情報を測定する）ことにより、これらの高さ情報を用いて中心Ｏの基板検査面の高さ情報を算出することができる。なお、被検査体１２における複数の視野ＦＯＶの透過画像（及びそれらの透過画像から生成される再構成画像）を取得するときは、それぞれの視野ＦＯＶにおいて高さ情報が取得される。 Figure 4 shows an example of the object 12 to be inspected, which is an electronic board inspected by the inspection device 1. The object 12 to be inspected has electronic components 12b to 12f attached to the board 12. The dashed rectangle indicates the field of view FOV. The image processing unit 35 of the control unit 10 may measure height information at the center O as height information of the top surface of the board 12a in the field of view FOV using the height information acquisition unit 50, or may measure height information at multiple points in the field of view FOV (for example, height information at the four corners P1 to P4 of the field of view FOV in Figure 4) and calculate height information at the center O of the field of view FOV from this height information using linear interpolation or the like. For example, when an electronic component is placed at the center O of the field of view FOV (electronic component 12b is placed in the case of Figure 1), no electronic component is placed within the field of view FOV, and the top surface of the board 12a is directly measured by the height information acquisition unit 50 (height information of a portion where the top surface of the board 12a can be directly irradiated with laser light from the height information acquisition unit 50 is measured), and height information of the board inspection surface at the center O can be calculated using this height information. When acquiring transmission images of multiple FOVs of the object 12 to be inspected (and reconstructed images generated from these transmission images), height information is acquired for each FOV.
　ここで、基板１２ａの上面を直接測定できる場所（すなわち、電子部品１２ｂ～１２ｆが取り付けられておらず基板が露出しており、この基板の上面に直接レーザー光を照射できる場所）は、被検査体（電子基板）１２の設計等のデータから決定することができる。あるいは、被検査体１２の上面を予め撮像した画像データ（２次元のカラー画像）から電子部品が取り付けられていない場所を特定してもよい。一般的に基板１２ａの上面には緑色のレジストが塗布されているため、画像データの緑色の部分を識別し、この緑色の部分を電子部品が取り付けられていない場所と判断してもよい。また、被検査体１２の画像データから電子部品が取り付けられていない基板面を特定することにより、高さ情報取得部５０と基板保持部２４（被検査体１２）とを相対移動させながら、基板面の位置で高さ情報を取得することができるので、基板面の複数の位置での高さ情報を効率良く取得することができる。 Here, the location where the top surface of the board 12a can be directly measured (i.e., the location where the board is exposed without electronic components 12b to 12f attached and where the top surface of the board can be directly irradiated with laser light) can be determined from data such as the design of the inspected object (electronic board) 12. Alternatively, the location where no electronic components are attached can be identified from image data (two-dimensional color image) of the top surface of the inspected object 12 captured in advance. Since a green resist is generally applied to the top surface of the board 12a, the green parts of the image data can be identified and these green parts can be determined to be locations where no electronic components are attached. In addition, by identifying the board surface where no electronic components are attached from the image data of the inspected object 12, height information can be acquired at the position of the board surface while moving the height information acquisition unit 50 and the board holding unit 24 (inspected object 12) relative to each other, so that height information can be acquired efficiently at multiple positions on the board surface.
　また、上述した２次元のカラー画像データをあらかじめ取得しておき、基板が露出している場所を多く通るように、高さ情報取得部５０でスキャンするルートを計算するときに、被検査体１２の基板上にあらかじめ設けられた「認識マーク」を用いることにより、位置合わせが有効になる。被検査体（電子基板）１２は、検査装置１に搬入するたびに、被検査体１２の位置決めをするためのストッパーに当たり、多少回転する。このとき、認識マークを読み取ることで、被検査体（電子基板）１２の位置を正しく読み取ることができ、高さ情報取得部５０で高さ情報を計測するときに常に基板上の同じルートをスキャンすることができ、これにより、計測の再現性を向上させることができる。 Also, by acquiring the above-mentioned two-dimensional color image data in advance, and using "recognition marks" provided in advance on the board of the inspected object 12 when calculating the route to be scanned by the height information acquisition unit 50 so as to pass through many exposed areas of the board, alignment becomes effective. Each time the inspected object (electronic board) 12 is brought into the inspection device 1, it hits a stopper used to position the inspected object 12 and rotates slightly. At this time, the position of the inspected object (electronic board) 12 can be correctly read by reading the recognition mark, and the same route on the board can always be scanned when measuring height information with the height information acquisition unit 50, thereby improving the reproducibility of the measurement.
　なお、視野ＦＯＶ内の複数の場所の高さ情報を取得する場合は、高さ情報を取得する場所毎に、被検査体１２を保持する基板保持部２４及び高さ情報取得部５０の相対位置を固定して（基板保持部２４を移動させて高さ情報取得部５０からのレーザー光を照射する位置を移動させる構成のときは、基板保持部駆動部１８により基板保持部２４を移動させてレーザー光を照射する位置に被検査体１２を移動させた後、基板保持部２４を停止させて）その場所の高さ情報を取得してもよいし、被検査体１２を保持する基板保持部２４及び高さ情報取得部５０の相対位置を変化させながら（基板保持部２４を移動させて高さ情報取得部５０からのレーザー光を照射する位置を移動させる構成のときは、基板保持部駆動部１８により基板保持部２４を移動させながら）所望の位置で高さ情報を取得してもよい。 When acquiring height information for multiple locations within the field of view FOV, the relative positions of the substrate holding unit 24 and the height information acquisition unit 50 holding the object to be inspected 12 may be fixed for each location for which height information is to be acquired (in the case of a configuration in which the substrate holding unit 24 is moved to move the position at which the laser light from the height information acquisition unit 50 is irradiated, the substrate holding unit drive unit 18 moves the substrate holding unit 24 to move the object to be inspected 12 to the position at which the laser light is irradiated, and then the substrate holding unit 24 is stopped), or the height information may be acquired at a desired position while changing the relative positions of the substrate holding unit 24 and the height information acquisition unit 50 holding the object to be inspected 12 (in the case of a configuration in which the substrate holding unit 24 is moved to move the position at which the laser light from the height information acquisition unit 50 is irradiated, the substrate holding unit drive unit 18 moves the substrate holding unit 24).
　図３に戻り、以上のようにして被検査体１２の基板検査面（基板の上面）の高さ情報が取得されると、制御部１０の撮像処理部３５は、放射線発生器駆動部１６により放射線発生器２２により放射される放射線の照射野（上述した視野ＦＯＶの透過画像を取得するために放射線が照射される領域）を設定し、基板保持部駆動部１８により基板保持部２４を移動させるとともに、検出器駆動部２０により検出器２６を移動させて撮像位置を変更しながら、線質変更部１４により放射線発生器２２の線質を設定して放射線を基板に照射して透過画像を撮像する。さらに、制御部１０の断面画像生成部３６は、このようにして撮像された複数枚の透過画像から再構成画像を生成する（ステップＳ１０２）。この再構成画像（断面画像）も、上述した高さ情報と同じ座標系（例えば、ＸＹＺ座標系）で管理することができる。なお、透過画像を撮像する際の、基板保持部駆動部１８による基板保持部２４の移動経路、及び、検出器駆動部２０による検出器２６の移動経路は、記憶部３４に記憶させた情報を読み込む方法や、入力装置から入力する方法により、予め基板保持部駆動部１８及び検出器駆動部２０に設定されているものとする。また、放射線発生器２２のＺ軸方向の位置も、同様の方法により予め放射線発生器駆動部１６に設定されているものとする。また、この場合も、基板保持部駆動部１８及び検出器駆動部２０により基板保持部２４及び検出器２６を所望の位置に移動させ、透過画像を取得する位置で基板保持部２４及び検出器２６を停止させてから透過画像を撮像してもよいし、基板保持部駆動部１８及び検出器駆動部２０により基板保持部２４及び検出器２６を移動させながら、所望の位置で透過画像を撮像してもよい。撮像された透過画像及び生成された再構成画像は、視野ＦＯＶ毎に記憶部３４に記憶される。 Returning to FIG. 3, when the height information of the substrate inspection surface (top surface of the substrate) of the inspected object 12 is acquired as described above, the imaging processing unit 35 of the control unit 10 sets the irradiation field of the radiation emitted by the radiation generator 22 (the area where the radiation is irradiated to acquire a transmission image of the field of view FOV described above) by the radiation generator driving unit 16, moves the substrate holding unit 24 by the substrate holding unit driving unit 18, and moves the detector 26 by the detector driving unit 20 to change the imaging position, while setting the radiation quality of the radiation generator 22 by the radiation quality changing unit 14, irradiates the substrate with radiation, and captures a transmission image. Furthermore, the cross-sectional image generating unit 36 of the control unit 10 generates a reconstructed image from the multiple transmission images thus captured (step S102). This reconstructed image (cross-sectional image) can also be managed in the same coordinate system (e.g., XYZ coordinate system) as the above-mentioned height information. In addition, the movement path of the substrate holder 24 by the substrate holder driver 18 and the movement path of the detector 26 by the detector driver 20 when capturing a transmission image are set in advance in the substrate holder driver 18 and the detector driver 20 by reading information stored in the memory 34 or inputting information from an input device. The position of the radiation generator 22 in the Z-axis direction is also set in advance in the radiation generator driver 16 by a similar method. In this case, the substrate holder driver 18 and the detector driver 20 may move the substrate holder 24 and the detector 26 to a desired position, and the substrate holder 24 and the detector 26 may be stopped at a position where a transmission image is to be acquired before capturing a transmission image, or the substrate holder driver 18 and the detector driver 20 may move the substrate holder 24 and the detector 26 to a desired position while capturing a transmission image. The captured transmission image and the generated reconstructed image are stored in the memory 34 for each field of view FOV.
　次に、制御部１０の基板検査面検出部３８は、断面画像生成部３６から透過画像または再構成画像（断面画像）を受け取り、その中から検査面画像を特定する基板検査面検出処理を実行する（ステップＳ１０４）。例えば、再構成画像から検査面画像を特定する場合、図５に示すように、まず、制御部１０の基板検査面検出部３８は、現在の視野ＦＯＶの高さ情報（ステップＳ１００で取得された高さ情報）を記憶部３４から読み込み（ステップＳ１０４１）、この高さ情報から再構成画像（断面画像）におけるＺ軸方向の探索範囲を決定する（ステップＳ１０４２）。ここで探索範囲は、高さ情報取得部５０により測定された基板検査面のＺ方向の位置を含むＺ方向の所定の範囲である。現在の視野ＦＯＶの高さ情報（計測された基板検査面のＺ方向の位置）を含むＺ方向の所定の範囲（探索範囲）にある断面画像の中に、基板検査面の断面画像（検査面画像）が含まれている可能性が最も高いからである。 Next, the board inspection surface detection unit 38 of the control unit 10 receives the transmission image or the reconstructed image (cross-sectional image) from the cross-sectional image generation unit 36, and executes a board inspection surface detection process to identify the inspection surface image from the transmitted image or the reconstructed image (cross-sectional image) (step S104). For example, when identifying the inspection surface image from the reconstructed image, as shown in FIG. 5, the board inspection surface detection unit 38 of the control unit 10 first reads the height information of the current field of view FOV (height information acquired in step S100) from the storage unit 34 (step S1041), and determines the search range in the Z-axis direction in the reconstructed image (cross-sectional image) from this height information (step S1042). Here, the search range is a predetermined range in the Z direction that includes the Z-direction position of the board inspection surface measured by the height information acquisition unit 50. This is because there is a high possibility that the cross-sectional image (inspection surface image) of the board inspection surface is included in the cross-sectional image in the predetermined range (search range) in the Z direction that includes the height information of the current field of view FOV (the measured Z-direction position of the board inspection surface).
　記憶部３４には、はんだの接合状態等に異常がない正常な被検査体の基板検査面の断面画像（これを「基準画像」と呼ぶ）が予め記憶されている。制御部１０の基板検査面検出部３８は、記憶部３４から現在の視野ＦＯＶの基準画像を読み出し（ステップＳ１０４３）、さらに、記憶部３４から、現在の視野ＦＯＶの再構成画像（ステップＳ１０２で生成された再構成画像）のうち、ステップＳ１０４２で決定された探索範囲内の断面画像を読み出す（ステップＳ１０４４）。そして、制御部１０の基板検査面検出部３８は、基準画像とステップＳ１０２４で読み出された断面画像の各々とを比較し、基準画像と最も一致する断面画像を検査面画像として特定し、特定された断面画像（検査面画像）のＺ軸方向の位置を現在の視野ＦＯＶにおける基板検査面の位置として記憶し（ステップＳ１０４５）、基板検査面検出処理を終了する。ここで、断面画像の中から基準画像に最も一致する断面画像を特定する方法としては、例えば、位相限定相関法を用いることで、高速に位置ずれに関係なく一致率を求めることができる。例えば、図６に示すように、高さ情報取得部５０により取得された現在の視野ＦＯＶの高さ情報（Ｚ軸方向の位置）がｚｓであった場合、この位置ｚｓを含むＺ軸方向の所定の範囲Ｒｓにある再構成画像（図６において実線で示す断面画像）に対して基準画像との比較処理を実行し、検査面画像を特定する。 The memory unit 34 stores in advance a cross-sectional image (called the "reference image") of the substrate inspection surface of a normal object to be inspected that has no abnormalities such as a solder joint state. The substrate inspection surface detection unit 38 of the control unit 10 reads out the reference image of the current field of view FOV from the memory unit 34 (step S1043), and further reads out from the memory unit 34 the cross-sectional images within the search range determined in step S1042 among the reconstructed images of the current field of view FOV (the reconstructed images generated in step S102) (step S1044). The substrate inspection surface detection unit 38 of the control unit 10 then compares the reference image with each of the cross-sectional images read out in step S1024, identifies the cross-sectional image that most closely matches the reference image as the inspection surface image, stores the position of the identified cross-sectional image (inspection surface image) in the Z-axis direction as the position of the substrate inspection surface in the current field of view FOV (step S1045), and ends the substrate inspection surface detection process. Here, as a method for identifying the cross-sectional image that most closely matches the reference image from among the cross-sectional images, for example, a phase-only correlation method can be used, which allows the matching rate to be found quickly and regardless of positional deviation. For example, as shown in FIG. 6, if the height information (position in the Z-axis direction) of the current field of view FOV acquired by the height information acquisition unit 50 is zs, a comparison process is performed with the reference image for a reconstructed image (cross-sectional image shown by a solid line in FIG. 6) in a predetermined range Rs in the Z-axis direction that includes this position zs, to identify the inspection surface image.
　図３に戻り、制御部１０の疑似断面画像生成部４０は、ステップＳ１０４で特定された検査面画像及び基板検査面のＺ方向の位置に基づいて、疑似断面画像を生成する（ステップＳ１０６）。 Returning to FIG. 3, the pseudo cross-sectional image generating unit 40 of the control unit 10 generates a pseudo cross-sectional image based on the inspection surface image identified in step S104 and the Z-direction position of the substrate inspection surface (step S106).
　次に、制御部１０のブリッジ検査部４４は、疑似断面画像生成部４０からはんだボールを映し出しているはんだボールと同程度のスライス厚の疑似断面画像を取得し（記憶部３４から読み出し）、ブリッジの有無を検査する（ステップＳ１０８）。ブリッジを検出しない場合には（ステップＳ１１０の「Ｎ」）、制御部１０の溶融状態検査部４６は基板検査面検出部３８から検査面画像を取得し（記憶部３４から読み出し）、はんだが溶融しているか否かを検査する（ステップＳ１１２）。はんだが溶融している場合には（ステップＳ１１４の「Ｙ」）、制御部１０のボイド検査部４８は疑似断面画像生成部４０からはんだボールを部分的に映し出している疑似断面画像を取得し（記憶部３４から読み出し）、ボイドが存在するか否かを検査する（ステップＳ１１６）。ボイドが見つからない場合には（ステップＳ１１８の「Ｎ」）、制御部１０の検査部４２は、はんだの接合状態は正常と判断し（ステップＳ１２０）、その旨を記憶部３４に出力する。また、ブリッジを検出した場合（ステップＳ１１０の「Ｙ」）、はんだが溶融していない場合（ステップＳ１１４の「Ｎ」）、またはボイドが存在する場合（ステップＳ１１８の「Ｙ」）には、検査部４２ははんだの接合状態は異常と判断して（ステップＳ１２２）その旨を記憶部３４に出力する。はんだの状態が記憶部３４に出力されると、本フローチャートにおける処理は終了する。 Next, the bridge inspection unit 44 of the control unit 10 obtains a pseudo cross-sectional image of a slice thickness equivalent to that of the solder ball that shows the solder ball from the pseudo cross-sectional image generation unit 40 (reads it from the storage unit 34) and inspects whether or not a bridge exists (step S108). If no bridge is detected ("N" in step S110), the molten state inspection unit 46 of the control unit 10 obtains an inspection surface image from the board inspection surface detection unit 38 (reads it from the storage unit 34) and inspects whether or not the solder is molten (step S112). If the solder is molten ("Y" in step S114), the void inspection unit 48 of the control unit 10 obtains a pseudo cross-sectional image that partially shows the solder ball from the pseudo cross-sectional image generation unit 40 (reads it from the storage unit 34) and inspects whether or not a void exists (step S116). If no voids are found ("N" in step S118), the inspection unit 42 of the control unit 10 determines that the solder joint condition is normal (step S120) and outputs this information to the memory unit 34. If a bridge is detected ("Y" in step S110), the solder is not melted ("N" in step S114), or a void is present ("Y" in step S118), the inspection unit 42 determines that the solder joint condition is abnormal (step S122) and outputs this information to the memory unit 34. When the solder condition is output to the memory unit 34, the processing in this flowchart ends.
　なお、図３に示すステップＳ１０４～Ｓ１２２の処理も、上述した視野ＦＯＶ毎に行われるが、ステップＳ１０２で全ての視野ＦＯＶの撮影を実行した後に、各々の視野ＦＯＶ毎にステップＳ１０４～Ｓ１２２を実行してもよいし、再構成画像（断面画像及び疑似断面画像）の生成が終了した視野ＦＯＶから順に、他の視野ＦＯＶの撮像と並行してステップＳ１０４～Ｓ１２２を実行してもよい。 The processing of steps S104 to S122 shown in FIG. 3 is also performed for each of the above-mentioned fields of view FOVs, but steps S104 to S122 may be performed for each field of view FOV after capturing images of all fields of view FOVs in step S102, or steps S104 to S122 may be performed in parallel with capturing images of other fields of view FOVs, starting from the field of view FOV for which generation of reconstructed images (cross-sectional images and pseudo-cross-sectional images) has been completed.
　本実施形態に係る検査装置１によると、被検査体１２の透過画像を取得する前に、高さ情報取得部５０より被検査体１２の視野ＦＯＶ毎の高さ情報を取得し、その後、視野ＦＯＶ毎に透過画像を取得して被検査体の再構成画像を生成し、高さ情報取得部５０による高さ情報に基づいて、再構成画像における基板検査面の探索範囲を決定し、この探索範囲で被検査体１２の再構成画像（断面画像）と基準画像とを比較して基板検査面の断面画像を決定している。そのため、基板検査面を特定する処理において、再構成画像（断面画像）のうち、基板検査面の断面画像が含まれる範囲を限定し、その限定された範囲内での比較を実行するため、全ての断面画像と比較する場合と比べて、基板検査面の断面画像を特定する時間を短くすることができる。 In the inspection device 1 according to this embodiment, before acquiring a transmission image of the inspected object 12, height information for each field of view FOV of the inspected object 12 is acquired by the height information acquisition unit 50, and then a transmission image is acquired for each field of view FOV to generate a reconstructed image of the inspected object. Based on the height information from the height information acquisition unit 50, a search range for the substrate inspection surface in the reconstructed image is determined, and the reconstructed image (cross-sectional image) of the inspected object 12 is compared with a reference image in this search range to determine the cross-sectional image of the substrate inspection surface. Therefore, in the process of identifying the substrate inspection surface, the range of the reconstructed image (cross-sectional image) that includes the cross-sectional image of the substrate inspection surface is limited, and a comparison is performed within this limited range, so that the time required to identify the cross-sectional image of the substrate inspection surface can be shortened compared to the case of comparing with all cross-sectional images.
　また、高さ情報取得部５０による高さ情報の取得を、放射線発生器２２から放射線を発生させるための準備の時間に行うことができるため、透過画像を取得することができない時間に高さ情報を取得することができるため、高さ情報を取得するための処理による、検査全体の時間の増加を抑えることができる。 In addition, since the height information acquisition unit 50 can acquire height information during preparation time for generating radiation from the radiation generator 22, height information can be acquired during a time when a transmitted image cannot be acquired, thereby suppressing an increase in the overall examination time due to processing for acquiring height information.
　また、電子基板にはレジスト等が塗布されており、レジスト等の上から高さ情報を取得する（このレジスト等にレーザー光を照射して高さ情報を取得する）と、レジスト等の厚みにバラツキがあるため、その高さ情報にバラツキが発生するが、高さ情報取得部５０により取得された高さ情報は、上述したように、断面画像における探査範囲を決定するものであり、基板検査面の断面画像の選択は、決定された探索範囲にある断面画像と基準画像との比較によりなされるため、基板検査面の断面画像の選択の精度に影響はない。 In addition, the electronic board is coated with a resist or the like, and when height information is obtained from above the resist or the like (height information is obtained by irradiating the resist or the like with laser light), there is variation in the thickness of the resist or the like, and therefore variation in the height information occurs. However, as described above, the height information obtained by the height information acquisition unit 50 determines the search range in the cross-sectional image, and the selection of the cross-sectional image of the board inspection surface is made by comparing the cross-sectional image in the determined search range with the reference image, so there is no effect on the accuracy of the selection of the cross-sectional image of the board inspection surface.
　また、本実施形態の検査装置１では、被検査体１２における視野ＦＯＶ内の複数の位置で高さ情報を取得し、それらの複数の高さ情報から、視野ＦＯＶ内の高さ情報（例えば、視野ＦＯＶの中心の高さ情報）を算出しているため、反りや撓みによる視野ＦＯＶ内における基準面からのずれに関する情報を精度良く取得することができ、断面画像の探索範囲をより正確に決定することができる。高さ情報の精度を上げることにより、断面画像の探索範囲の幅を狭くする（基準画像と比較する断面画像を少なくする）ことができるので、基板検査面の検出に要する時間を短くし、結果として検査全体に要する時間を短くすることができる。 In addition, in the inspection device 1 of this embodiment, height information is obtained at multiple positions within the field of view FOV of the inspected object 12, and height information within the field of view FOV (e.g., height information at the center of the field of view FOV) is calculated from these multiple height information, so that information regarding deviation from the reference surface within the field of view FOV due to warping or bending can be obtained with high accuracy, and the search range of the cross-sectional image can be determined more accurately. By increasing the accuracy of the height information, the width of the search range of the cross-sectional image can be narrowed (fewer cross-sectional images are compared with the reference image), thereby shortening the time required to detect the substrate inspection surface, and as a result, the time required for the entire inspection can be shortened.
　ここで、被検査体１２における複数の位置で高さ情報を取得する際に、取得する位置を移動する毎に、高さ情報取得部５０に対して基板保持部２４（被検査体１２）を停止させていると、被検査体１２に振動等が発生しないため取得できる高さ情報の精度は向上するが、次の測定位置に移動する際に再度、高さ情報取得部５０に対して基板保持部２４（被検査体１２）を移動させなければならず、停止及び起動に時間が掛かってしまう。そのため、高さ情報取得部５０と基板保持部２４（被検査体１２）とを相対移動させながら複数の位置の高さ情報を取得することにより、高さ情報の取得の時間を短縮することができる。なお、高さ情報取得部５０と基板保持部２４（被検査体１２）とを相対移動させながら高さ情報を取得すると、停止した状態で取得した高さ情報に比べて精度が悪くなるが、高さ情報取得部５０により取得された高さ情報は、上述したように、断面画像を探査する範囲を決定するものであり、基板検査面の断面画像の選択は、決定された探索範囲にある断面画像と基準画像との比較によりなされるため、基板検査面の断面画像の選択に影響はない。 Here, when acquiring height information at multiple positions on the test object 12, if the substrate holding part 24 (test object 12) is stopped relative to the height information acquisition part 50 each time the acquisition position is moved, the accuracy of the acquired height information is improved because no vibrations or the like are generated in the test object 12; however, when moving to the next measurement position, the substrate holding part 24 (test object 12) must be moved again relative to the height information acquisition part 50, which takes time to stop and start. Therefore, by acquiring height information at multiple positions while moving the height information acquisition part 50 and the substrate holding part 24 (test object 12) relative to each other, the time it takes to acquire the height information can be shortened. Note that if height information is acquired while moving the height information acquisition unit 50 and the substrate holding unit 24 (inspected object 12) relative to each other, the accuracy will be poorer than height information acquired in a stationary state; however, as described above, the height information acquired by the height information acquisition unit 50 determines the range in which the cross-sectional images are searched, and the selection of the cross-sectional image of the substrate inspection surface is made by comparing the cross-sectional images in the determined search range with the reference image, so there is no effect on the selection of the cross-sectional image of the substrate inspection surface.
　なお、上述した説明では、被検査体１２の上面側に高さ情報取得部５０を配置した場合について説明した。被検査体１２の上面側に高さ情報取得部５０を配置すると、放射線発生器２２側に位置するため、この放射線発生器２２から放射される放射線が直接照射されない位置に高さ情報取得部５０を配置することができるので、放射線による被曝を避けることができる。一方、被検査体１２の裏面側に高さ情報取得部５０を配置して被検査体１２の基板の裏面の高さ情報を取得するように構成してもよい。被検査体１２の基板は平板状であり、この基板の厚さは設計等の情報から既知である。したがって、被検査体１２の基板の裏面の高さ情報から基板の上面の高さ情報を演算により算出することができる。基板の裏面の高さ情報から演算で求められた上面の高さ情報の精度が低いとしても、上述したように、断面画像を探査する範囲を決定するものであり、基板検査面の断面画像の選択は、決定された探索範囲にある断面画像と基準画像との比較によりなされるため、基板検査面の断面画像の選択に影響はない。但し、被検査体１２の基板の裏面に高さ情報取得部５０を配置すると放射線発生器２２から放射された放射線が直接この高さ情報取得部５０に照射され被曝してしまう。このように、高さ情報取得部５０による高さ情報の取得は、被検査体１２の基板の上面でも裏面でも取得することが可能なので、検査装置１における高さ情報取得部５０の配置位置の自由度を上げることができる。 In the above description, the height information acquisition unit 50 is disposed on the upper surface side of the inspected object 12. When the height information acquisition unit 50 is disposed on the upper surface side of the inspected object 12, it is located on the radiation generator 22 side, so that the height information acquisition unit 50 can be disposed in a position where it is not directly irradiated with radiation emitted from the radiation generator 22, thereby avoiding exposure to radiation. On the other hand, the height information acquisition unit 50 may be disposed on the rear surface side of the inspected object 12 to acquire height information of the rear surface of the substrate of the inspected object 12. The substrate of the inspected object 12 is flat, and the thickness of this substrate is known from information such as design. Therefore, the height information of the upper surface of the substrate can be calculated from the height information of the rear surface of the substrate of the inspected object 12. Even if the accuracy of the height information of the upper surface calculated from the height information of the rear surface of the substrate is low, as described above, the range in which the cross-sectional image is searched is determined, and the selection of the cross-sectional image of the substrate inspection surface is performed by comparing the cross-sectional image in the determined search range with the reference image, so there is no effect on the selection of the cross-sectional image of the substrate inspection surface. However, if the height information acquisition unit 50 is placed on the back surface of the substrate of the inspected object 12, the radiation emitted from the radiation generator 22 will directly irradiate the height information acquisition unit 50, resulting in exposure to radiation. In this way, the height information acquisition unit 50 can acquire height information from both the top surface and the back surface of the substrate of the inspected object 12, which increases the degree of freedom in the placement position of the height information acquisition unit 50 in the inspection device 1.
（高さ情報の取得方法の変形例）
　上述した説明では、被検査体１２の基板１２ａの上面の電子部品（１２ｂ～１２ｆ）等が取り付けられていない位置の高さ情報を取得する場合について説明した。この場合、被検査体１２の設計等の情報や画像データから高さ情報を取得する位置を決定しなければならない。そこでこの変形例では、被検査体１２の基板の上面における電子部品等の配置状態を考慮せずに複数の位置で高さ情報を取得し、取得された情報から基板の上面の高さ情報を演算で算出する方法について説明する。 (Modification of the method for acquiring height information)
In the above description, a case has been described where height information is acquired for positions on the top surface of the substrate 12a of the inspected object 12 where no electronic components (12b to 12f) are attached. In this case, the positions from which the height information is acquired must be determined from information such as the design of the inspected object 12 and image data. In this modified example, therefore, a method will be described in which height information is acquired at a plurality of positions without considering the arrangement of electronic components and the like on the top surface of the substrate of the inspected object 12, and height information for the top surface of the substrate is calculated from the acquired information.
　図７は、高さ情報の取得方法の変形例のフローチャートを示しており、被検査体１２の検査における高さ情報の取得処理（図３に示すステップＳ１００）において、制御部１０の撮像処理部３５は、被検査体１２の基板の上面の全面の高さ情報を取得する（ステップＳ１００１）。例えば、図８に示すように、被検査体１２の基板１２ａを破線Ｍで示す領域に分割し、高さ情報取得部５０に対して基板保持部２４を移動させ、それぞれの領域において高さ情報を取得する。一例としては、左上の領域から右方向に向かって被検査体１２を移動させながら各領域で高さ情報を取得し、右上の領域からは一つ下の段に移動して左方向に向かって被検査体１２を移動させながら各領域で高さ情報を取得するという処理を繰り返す。取得された高さ情報は、基板上の座標とともに（Ｘ，Ｙ，Ｚ）の形式で記憶部３４に記憶される。 FIG. 7 shows a flow chart of a modified method of acquiring height information. In the process of acquiring height information in the inspection of the object 12 (step S100 shown in FIG. 3), the image processing unit 35 of the control unit 10 acquires height information of the entire upper surface of the substrate of the object 12 (step S1001). For example, as shown in FIG. 8, the substrate 12a of the object 12 is divided into regions indicated by dashed lines M, the substrate holding unit 24 is moved relative to the height information acquiring unit 50, and height information is acquired in each region. As an example, the object 12 is moved from the upper left region to the right while acquiring height information in each region, and the object 12 is moved from the upper right region to the next lower step and moved leftward while acquiring height information in each region. The acquired height information is stored in the memory unit 34 together with the coordinates on the substrate in the form of (X, Y, Z).
　このように、被検査体１２の基板１２ａの上面の全面の高さ情報を取得すると、基板面の高さ情報だけでなく、部品１２ｂ～１２ｆの高さ情報も取得されてしまう。そのため、基板面以外の高さ情報を演算により除去する。まず、制御部１０の撮像処理部３５は、各領域の高さ情報に対して最小値フィルタを適用し、部品の高さ情報を除去する（ステップＳ１００２）。最小値フィルタは、注目している領域の高さ情報と、その注目している領域の周辺にある領域の高さ情報との大小比較を行い、注目している領域の高さ情報を最も小さい値の高さ情報に変換するフィルタである。部品は基板の上面に取り付けられているため、この最小値フィルタを適用することにより、部品の高さ情報を除去することができる。 In this way, when height information of the entire top surface of the substrate 12a of the inspected object 12 is obtained, not only height information of the substrate surface but also height information of the components 12b to 12f is obtained. Therefore, height information other than that of the substrate surface is removed by calculation. First, the image capture processing unit 35 of the control unit 10 applies a minimum value filter to the height information of each region to remove the height information of the components (step S1002). The minimum value filter is a filter that compares the height information of the region of interest with the height information of the regions surrounding the region of interest, and converts the height information of the region of interest into height information with the smallest value. Since the components are attached to the top surface of the substrate, the height information of the components can be removed by applying this minimum value filter.
　次に、制御部１０の撮像処理部３５は、最小値フィルタが適用された各領域の高さ情報に対して平均値フィルタを適用し、異常値を除去する。平均値フィルタ、注目している良規の高さ情報と、その注目している領域の周辺にある領域の高さ情報との平均値を求め、その平均値を高さ情報に注目している領域の高さ情報に変化するフィルタである。平均値フィルタを適用することにより、異常値を除去することができる。 Next, the image capture processing unit 35 of the control unit 10 applies an average value filter to the height information of each region to which the minimum value filter has been applied, and removes abnormal values. The average value filter is a filter that calculates the average value between the good height information of interest and the height information of regions surrounding the interest, and changes the height information of the interest region to the average value. By applying the average value filter, it is possible to remove abnormal values.
　最後に、制御部１０の撮像処理部３５は、視野ＦＯＶ毎に、その視野ＦＯＶに含まれる領域の高さ情報から、例えば線形補完等により視野ＦＯＶの中心の高さ情報を算出し（ステップＳ１００４）、高さ情報の取得処理を終了する。 Finally, the image capturing processing unit 35 of the control unit 10 calculates the height information of the center of each FOV from the height information of the area included in the FOV, for example by linear interpolation (step S1004), and ends the height information acquisition process.
　このように、被検査体１２上の複数の位置（基板の上面の全面）で高さ情報を取得し、それらの複数の高さ情報から、基板面以外の高さ情報（例えば、基板上に取り付けられた部品の高さ情報）を演算により除去することにより、基板面か否かにかかわらず、被検査体１２上の複数の位置で高さ情報を取得し、それらの高さ情報から基板面の高さ情報を精度良く取得することができる。 In this way, by acquiring height information at multiple positions on the object to be inspected 12 (the entire top surface of the board), and then calculating and removing height information other than that of the board surface (for example, height information of components mounted on the board) from the multiple height information, it is possible to acquire height information at multiple positions on the object to be inspected 12, regardless of whether it is the board surface or not, and to acquire height information of the board surface from the acquired height information with high accuracy.
１　検査装置
１０　制御部
１２　被検査体
１６　放射線発生器駆動部（駆動部）
１８　基板保持部駆動部（駆動部）
２０　検出器駆動部（駆動部）
２２　放射線発生器（線源）
２４　基板保持部（保持部）
２６　検出器
５０　高さ情報取得部 1 Inspection device 10 Control unit 12 Inspected object 16 Radiation generator drive unit (drive unit)
18 Substrate holder drive unit (drive unit)
20 Detector driving unit (driving unit)
22 Radiation generator (ray source)
24 Substrate holding part (holding part)
26 Detector 50 Height information acquisition unit

Claims (8)

  1. 　線源と、
    　被検査体を保持する保持部と、
    　検出器と、
    　前記被検査体の高さ情報を取得する高さ情報取得部と、
    　前記線源と前記保持部で保持された前記被検査体及び前記検出器との相対位置、及び、前記保持部で保持された前記被検査体と前記高さ情報取得部との相対位置を変化させる駆動部と、
    　制御部と、を有し、
    　前記制御部は、
    　前記高さ情報取得部により前記被検査体の高さ情報を取得するステップと、
    　前記駆動部により前記線源と前記保持部で保持された前記被検査体及び前記検出器とが所定の相対位置にあるときに、前記線源から放射され前記被検査体を透過した放射線を前記検出器で検出して取得した複数の前記被検査体の透過画像から前記被検査体の断面画像を生成するステップと、
    　前記高さ情報に基づいて所定の高さ方向の範囲を決定し、前記範囲内の前記断面画像から検査対象の断面画像を決定するステップと、
    　前記検査対象の断面画像に基づいて検査をするステップと、
    を実行する検査装置。     A radiation source;
    A holder for holding an object to be inspected;
    A detector;
    a height information acquiring unit for acquiring height information of the object to be inspected;
    a drive unit that changes a relative position between the radiation source and the object to be inspected and the detector held by the holder, and a relative position between the object to be inspected held by the holder and the height information acquisition unit;
    A control unit,
    The control unit is
    acquiring height information of the test subject by the height information acquiring unit;
    generating a cross-sectional image of the object to be inspected from a plurality of transmission images of the object to be inspected obtained by detecting, with the detector, radiation emitted from the radiation source and transmitted through the object to be inspected, when the radiation source, the object to be inspected held by the holder, and the detector are at a predetermined relative position by the driving unit;
    determining a predetermined range in a height direction based on the height information, and determining a cross-sectional image of an object to be inspected from the cross-sectional images within the range;
    performing an inspection based on the cross-sectional image of the inspection object;
    Inspection equipment that performs the above.
  2. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　前記駆動部により前記保持部で保持された前記被検査体を前記高さ情報取得部に対して相対移動させ、前記高さ情報取得部により前記被検査体の基板面の複数の位置の高さ情報を取得させ、
    　前記複数の位置の高さ情報から、当該複数の位置を含む領域の所定の位置の基板面の高さ情報を決定する
    　請求項１に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    The object under test held by the holding unit is moved relative to the height information acquisition unit by the driving unit, and height information at a plurality of positions on a substrate surface of the object under test is acquired by the height information acquisition unit;
    The inspection apparatus according to claim 1 , further comprising: determining height information of the substrate surface at a predetermined position in an area including the plurality of positions from the height information of the plurality of positions.
  3. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　前記駆動部により前記保持部で保持された前記被検査体を前記高さ情報取得部に対して相対移動させ、前記高さ情報取得部により前記被検査体の複数の位置の高さ情報を取得させ、
    　前記複数の位置の高さ情報から、演算により基板面以外の高さ情報を除去し、当該複数の位置を含む領域の所定の位置の基板面の高さ情報を決定する
    　請求項１に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    The test object held by the holding unit is moved relative to the height information acquisition unit by the driving unit, and height information at a plurality of positions of the test object is acquired by the height information acquisition unit;
    The inspection device according to claim 1 , further comprising: a calculation to remove height information other than that of the substrate surface from the height information of the plurality of positions; and to determine height information of the substrate surface at a predetermined position in an area including the plurality of positions.
  4. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　前記駆動部により前記高さ情報取得部と前記保持部で保持された前記被検査体との相対位置を変化させながら、前記複数の位置の高さ情報を取得する
    　請求項２または３に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    The inspection device according to claim 2 , wherein the height information at the plurality of positions is acquired while the drive section changes a relative position between the height information acquisition section and the object under inspection held by the holding section.
  5. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　予め取得された前記被検査体の画像データから、前記被検査体の基板面の位置を取得し、
    　前記高さ情報取得部により、取得された位置の高さ情報を取得する
    　請求項２に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    acquiring a position of a substrate surface of the object to be inspected from image data of the object to be inspected that has been acquired in advance;
    The inspection device according to claim 2 , wherein the height information acquisition unit acquires height information of the acquired position.
  6. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　前記画像データにおける前記被検査体の色情報から前記基板面の位置を取得する
    　請求項５に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    The inspection apparatus according to claim 5 , wherein the position of the substrate surface is obtained from color information of the object to be inspected in the image data.
  7. 　前記制御部は、
    　前記高さ情報を取得するステップにおいて、
    　前記駆動部により前記高さ情報取得部に対する前記保持部で保持された前記被検査体の相対位置を変化させながら、前記複数の位置の高さ情報を取得し、前記複数の位置の高さ情報から、前記被検査体の基板面の高さ情報を決定する
    　請求項５または６に記載の検査装置。     The control unit is
    In the step of acquiring height information,
    7. The inspection device according to claim 5 or 6, further comprising: acquiring height information of the plurality of positions while changing the relative position of the object to be inspected held by the holding unit with respect to the height information acquisition unit using the driving unit; and determining height information of the substrate surface of the object to be inspected from the height information of the plurality of positions.
  8. 　前記高さ情報取得部は、前記被検査体の基板の上面又は裏面における前記高さ情報を取得する変位計である
    　請求項１～７のいずれか一項に記載の検査装置。     8. The inspection device according to claim 1, wherein the height information acquisition unit is a displacement meter that acquires the height information on the top surface or the back surface of the substrate of the object to be inspected.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030035576A1 (en) * 2001-07-31 2003-02-20 Roder Paul A. Automatic X-ray determination of solder joint and view Delta Z values from a laser mapped reference surface for circuit board inspection using X-ray laminography
JP2006292465A (en) * 2005-04-07 2006-10-26 Nagoya Electric Works Co Ltd X-ray inspection device, x-ray inspection method and x-ray inspection program
JP2012237729A (en) * 2011-05-13 2012-12-06 Omron Corp Inspection region setting method and x-ray inspection system
WO2019065701A1 (en) * 2017-09-28 2019-04-04 株式会社サキコーポレーション Inspection position specification method, three-dimensional image generation method, and inspection device
JP2021162523A (en) * 2020-04-02 2021-10-11 株式会社サキコーポレーション Inspection device
JP2021173575A (en) * 2020-04-22 2021-11-01 株式会社サキコーポレーション Inspection device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030035576A1 (en) * 2001-07-31 2003-02-20 Roder Paul A. Automatic X-ray determination of solder joint and view Delta Z values from a laser mapped reference surface for circuit board inspection using X-ray laminography
JP2006292465A (en) * 2005-04-07 2006-10-26 Nagoya Electric Works Co Ltd X-ray inspection device, x-ray inspection method and x-ray inspection program
JP2012237729A (en) * 2011-05-13 2012-12-06 Omron Corp Inspection region setting method and x-ray inspection system
WO2019065701A1 (en) * 2017-09-28 2019-04-04 株式会社サキコーポレーション Inspection position specification method, three-dimensional image generation method, and inspection device
JP2021162523A (en) * 2020-04-02 2021-10-11 株式会社サキコーポレーション Inspection device
JP2021173575A (en) * 2020-04-22 2021-11-01 株式会社サキコーポレーション Inspection device

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