Inspection device

Abstract

Provided is an inspection device capable of suppressing the generation of sound and vibration when accelerating an inspection object (holding part) stopped at a standby position.　In an inspection device 1 having a radiation generator 22, a holding part 24 for holding an inspection object 12, a detector 26, and a control unit 10, a holding part driving unit 18 for moving the holding part 24 has an X driving part 18e for moving the holding part 24 in the X-axis direction, and a Y driving part 18c for moving the holding part 24 in the Y-axis direction. The control unit 10 determines a standby position PS and an input position Pi so as to reduce the larger value among a component in the X-axis direction of weight moved by the X driving part 18e and a component in the Y-axis direction of weight moved by the Y driving part 18c when the holding part 24 moves on a feeding track 28i.

Description

Inspection Equipment

[0001] The present invention relates to an inspection device.

[0002] In electronic circuit boards, the connection state between the soldered electronic components (e.g., pins) and the wiring on the board is difficult to determine by visual inspection, so an inspection device using a tomosynthesis method using X-rays is used. Specifically, the device is configured to rotate and move the object to be inspected (electronic circuit board) and a detector held by a holder through a beam of X-rays emitted from a light source, acquire transmitted image data, and generate three-dimensional image data. A so-called H-shaped XY stage is used as a drive unit for moving the holder and detector (see, for example, Patent Document 1).

[0003] JP 2023-053558 A

[0004] Such an inspection device is configured to load an inspection object stopped at a standby position onto a track that rotates the object to be inspected in order to capture a transmission image, but noise and vibrations are generated when the stopped inspection object is accelerated. In particular, when the speed of the rotation movement when capturing a transmission image is increased in order to shorten the time required to inspect one inspection object, the noise and vibrations become louder during acceleration. The loud noise generated during acceleration deteriorates the work environment in which the inspection device is installed, and the vibrations generated can cause problems such as a decrease in the resolution of the transmission image and a decrease in inspection accuracy (a decrease in the resolution of three-dimensional image data and a decrease in the accuracy of judgment).

[0005] The present invention has been made in consideration of such problems, and aims to provide an inspection device that can suppress the generation of noise and vibration when accelerating an object to be inspected (holding part) stopped in a standby position.

[0006] In order to solve the above problem, an inspection device according to the present invention includes a light source that emits light along an axis extending in a third direction, a holder that holds the object under inspection and moves in a predetermined orbit around the axis on a holder orbit plane that is a plane orthogonal to the axis, a detector that moves in a predetermined orbit around the axis on a detector orbit plane that is a plane orthogonal to the axis and different from the holder orbit plane, thereby detecting light that is emitted from the light source and transmitted through the object under inspection, a holder drive unit that moves the holder, and a control unit that controls operation of the holder drive unit, wherein the holder drive unit is a first drive unit that moves the holder in a first direction on the holder orbit plane. and a second drive unit that moves the holding unit in a second direction perpendicular to the first direction on the holding unit orbital surface, and the control unit controls the operation of the first drive unit and the second drive unit to move the holding unit, which is stopped at a waiting position outside the turning orbit on the holding unit orbital surface, on a linear throw-in orbit from the waiting position to a throw-in position on the turning orbit, and to cause the holding unit to turn on the turning orbit from the throw-in position, and determines the waiting position and the throw-in position so that the larger value of the first direction component of the weight moved by the first drive unit and the second direction component of the weight moved by the second drive unit is smallest when the holding unit moves on the throw-in orbit.

[0007] In such an inspection device, it is preferable that a straight line connecting the intersection of the holding portion track surface and the axis to the loading position is perpendicular to the loading track.

[0008] Furthermore, it is preferable that such an inspection device determines the standby position and the loading position so that n obtained by the following formula is minimized: n = max(α·cos θ, β·sin θ) where, α: weight moved by the first drive unit β: weight moved by the second drive unit θ: angle formed by a line in a first direction passing through the intersection of the holding unit track surface and the axis, and a line connecting the intersection and the loading position (0°<θ<90°, the turning direction is positive) max(): function that selects the maximum value among the numerical values ​​set in the arguments

[0009] Furthermore, in such an inspection device, it is preferable that the control unit controls the operation of the holding unit drive unit so that the holding unit, which is moving in a revolving manner on the revolving orbit, moves along a linear reversal orbit from the insertion position on the revolving orbit to an evacuation position outside the revolving orbit on the holding unit orbit plane and stops there, and that the evacuation orbit is located on an extension of the insertion orbit.

[0010] According to the inspection device of the present invention, it is possible to suppress the generation of noise and vibration when accelerating the object to be inspected (holding portion) stopped at the standby position.

[0011] FIG. 1 is an explanatory diagram for explaining the configuration of an inspection device. FIG. 1 is an explanatory diagram for explaining the insertion orbit, rotation orbit, and avoidance orbit of a holder in the inspection device. FIG. 2 is an explanatory diagram for explaining the configuration of a holder drive unit of the inspection device. FIG. 3 is an explanatory diagram for explaining each functional block of a control unit of the inspection device. FIG. 4 is a flowchart for explaining inspection processing in the inspection device. FIG. 5 is a flowchart for explaining transmission image capturing and reconstruction image generation processing in the inspection processing. FIG. 6 is a flowchart for explaining judgment processing in the inspection processing. FIG. 7 is an explanatory diagram for explaining the relationship between the rotation orbit of the holder and the insertion orbit. FIG. 8 is an explanatory diagram showing the relationship between n and θ in the insertion orbit.

[0012] A preferred embodiment of the present invention will now be described with reference to the drawings. As shown in Fig. 1, an inspection device 1 according to this embodiment includes a control unit 10, which is a processing device such as a personal computer (PC), a monitor 11, and an imaging unit 32. The imaging unit 32 also includes a radiation generator 22, a holder 24, a detector 26, a radiation quality changing unit 14, a light source driver 16, a holder driver 18, and a detector driver 20.

[0013] The radiation generator 22 is a device (light source) that generates radiation such as X-rays. For example, the radiation is generated by colliding accelerated electrons with a target such as tungsten or diamond. In this embodiment, the radiation is described as X-rays, but the radiation is not limited to X-rays. 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. The radiation generator 22 is configured to emit radiation along an axis A passing through the focal point of the radiation generator 22 (an axis (optical axis) passing through the center of the radiation direction of the radiation emitted from the radiation generator 22, and the direction of this axis (third direction) is referred to as the "Z-axis direction"). Therefore, when there is no obstacle, the beam of radiation emitted from the radiation generator 22 forms a cone shape with the light source at its apex.

[0014] The holder 24 holds an electronic substrate (hereinafter simply referred to as a "substrate"), which is the object under inspection 12. The object under inspection 12 held by the holder 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 radiographic 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 detector 26 and the holder 24 that holds the substrate, which is the object under inspection 12, are moved relative to the radiation generator 22 to acquire a plurality of transmission images, and a reconstructed image (cross-sectional image), which is a three-dimensional image, is generated from these transmission images.

[0015] The transmission image captured by the detector 26 (transmission image data, which is data of the transmission image output from the detector 26) is sent to the control unit 10, where it is reconstructed into image data 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 data and transmission image data are then stored in a storage unit within the control unit 10 (e.g., the storage unit 34, described later) or in an external storage unit (not shown). Hereinafter, image data obtained by extracting one cross section of the three-dimensional shape calculated based on the transmission image data will be referred to as a cross-sectional image (cross-sectional image data). Furthermore, a set of one or more cross-sectional image data will be referred to as "three-dimensional image data" or "reconstructed image data." In other words, image data obtained by cutting out an arbitrary cross section from the three-dimensional image data (reconstructed image data) is cross-sectional image data. Such reconstructed images and cross-sectional images are output to the monitor 11. Note that the monitor 11 displays not only the reconstructed images and cross-sectional images, but also the inspection results of the solder joint state, described later. Hereinafter, the reconstructed image in this embodiment is also referred to as "planar CT" because it is reconstructed from a planar image (transmission image data) captured by the detector 26, as described above.

[0016] The radiation quality modification unit 14 modifies the radiation quality of the radiation generated by the radiation generator 22. The radiation quality is determined by a voltage (hereinafter referred to as "tube voltage") applied to accelerate electrons to be bombarded with a target, and a current (hereinafter referred to as "tube current") that determines the number of electrons. The radiation quality modification unit 14 is a device that controls the tube voltage and tube current. The radiation quality modification unit 14 can be realized using known technology such as a transformer or a rectifier.

[0017] The quality of radiation is determined by its brightness and wavelength (spectral distribution). Increasing the tube current increases the number of electrons colliding with the target and the number of radiation photons generated. This results in higher radiation brightness. For example, some components, such as capacitors, are thicker than other components, and high-brightness radiation is required to capture transmission images of these components. In such cases, adjusting the tube current adjusts the radiation brightness. Furthermore, increasing the tube voltage increases the energy of the electrons colliding with the target, thereby increasing the energy (spectrum) of the generated radiation. Generally, the higher the radiation energy, the greater its penetration power and the less it is absorbed by materials. Transmission images captured using such radiation have lower contrast. Therefore, the tube voltage can be used to adjust the contrast of transmission images.

[0018] The inspection device 1 is configured to revolve the inspection object 12 held by the holder 24 along a revolving orbit (holder revolving orbit) 28 on a holder orbit plane, which is a plane orthogonal to the axis A, within the beam of radiation emitted from the radiation generator 22, and to revolve the detector 26 along a revolving orbit (detector revolving orbit) 30 on a detector orbit plane different from the holder orbit plane, thereby detecting the radiation that has passed through the inspection object 12 and capturing a transmission image of the inspection object 12. Note that the orbit planes of the holder revolving orbit 28 and the detector revolving orbit 30 are orthogonal to the Z-axis direction described above. If the orbital directions orthogonal to this orbit plane are defined as the X-axis direction (first direction) and the Y-axis direction (second direction), the positions of the holder 24 in the X-axis direction and the Y-axis direction are detected by a substrate position detection unit 29 and output to the control unit 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 unit 31 and output to the control unit 10.

[0019] Here, the movement path of the object under test 12 (holding unit 24) within the inspection device 1 when capturing a transmission image of the object under test 12 will be described with reference to Fig. 2. Note that the transmission image of the object under test 12 is captured at predetermined positions on a circle centered on axis A by rotating the object under test 12, but in this description, the images are captured at eight imaging positions P1 to P8. However, the positions at which the transmission images are captured are not limited to eight.

[0020] Before the start of inspection, the holder 24 is stopped at a standby position PS while holding the object under test 12 that has been carried into the inspection apparatus 1. This standby position PS is located outside the holder rotation orbit 28 on the holder track surface. When inspection begins, the holder 24 starts moving from this standby position PS, passes along the linear insertion orbit 28i, and enters the holder rotation orbit 28 from the first imaging position P1. Here, the position (imaging position P1) at which the holder enters the holder rotation orbit 28 from the standby position PS is referred to as an insertion position Pin. Furthermore, the holder that has entered the holder rotation orbit 28 moves sequentially through the second and subsequent imaging positions (P2 to P8) on the holder rotation orbit 28, moves from the first imaging position P1 (insertion position Pin) to a linear retreat orbit 28o, and moves through this retreat orbit 28o to a stop position PE located outside the holder rotation orbit 28 on the holder track surface, where it stops. The object under test 12 is then carried out of the inspection apparatus 1.

[0021] When the object under test 12 (holding unit 24) is at one of the imaging positions P1 to P8, a transmission image is captured by the detector 26. Therefore, although not shown, the detector 26 also moves on the detector orbit plane along the same movement path as the holding unit 24. As described above, the object under test 12 (holding unit 24) revolves around axis A within the conical beam of light emitted from the radiation generator 22. Therefore, the diameter of the detector orbit 30 of the detector 26 that is farther from the radiation generator 22 than the object under test 12 (holding unit 24) is greater than the diameter of the holding unit orbit 28. To shorten the time required to capture a transmission image of the object under test 12, it is preferable to capture images without stopping the holding unit 24 and the detector 26 (while continuing their revolving movement) at the imaging positions P1 to P8. During revolving movement, the movement time can be shortened by moving linearly between the imaging positions as shown by the solid line in FIG. 1 , but they may also move along a circumference as shown by the dotted line. Furthermore, the initial imaging position P1 and the insertion position Pin do not need to be at the same position, and the initial imaging position P1 may be set at a position after the insertion from the insertion position Pin into the holding unit rotation orbit 28.

[0022] The light source driving unit 16 has a driving mechanism such as a motor (not shown), and is able to move the radiation generator 22 up and down in the Z-axis direction along the axis A. This makes it possible to change the distance between the radiation generator 22 and the object under test (substrate) 12 held by the holder 24, thereby changing the irradiation field and changing 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 the light source position detection unit 23 and output to the control unit 10.

[0023] The holder driving unit 18 has a driving mechanism such as a motor, and moves the holder 24 in a rotational path (holder rotation path) 28 on a holder path plane that is a plane perpendicular to the axis A. As shown in Fig. 3, the holder driving unit 18 is an H-shaped XY stage, and is configured to include a moving table 18a to which the holder 24 is attached, a Y-direction guide 18b extending in the Y-axis direction, a Y-driver 18c that moves the moving table 18a in the Y-axis direction along the Y-direction guide 18b, two X-direction guides 18d that support the Y-direction guide 18b at both ends and are configured to be able to move the moving table 18a and the Y-direction guide 18b in the X-axis direction, and an X-driver 18e that moves the moving table 18a and the Y-direction guide 18b in the X-axis direction. The detector driving unit 20 also has a driving mechanism such as a motor, and moves the detector 26 in a revolving manner along a revolving orbit (detector revolving orbit) 30 on a detector orbit plane that is different from the holding unit orbit plane and that is perpendicular to the axis A. The detector driving unit 20 also has the same configuration as the holding unit driving unit 18 described above.

[0024] As described above, the rotational movements of the holder 24 and the detector 26 are linked, and they are configured to rotate on the holder rotation orbit 28 and the detector rotation orbit 30, respectively. This makes it possible to capture multiple transmission images with different projection directions and projection angles while changing the relative positional relationship between the object under test 12 held by the holder 24 and the radiation generator 22. Note that in the inspection device 1 according to this embodiment, the area on the object under test 12 from which a transmission image can be acquired is determined by the size of the radiation detection area of ​​the detector 26 and the relative positions of the radiation generator 22, the object under test 12 (holder 24), and the detector 26. This area (imaging area) from which a transmission image can be acquired is called the "FOV (field of view)." When the object under test 12 is divided into multiple imaging areas (FOVs) for imaging, each imaging area moves on the holder rotation orbit 28 described above.

[0025] The rotation radii of the holder rotation orbit 28 and the detector rotation orbit 30 are not fixed but can be freely changed, which makes it possible to arbitrarily change the irradiation angle of the radiation irradiated onto the substrate, which is the object under test 12, and onto the components attached to this substrate.

[0026] The control unit 10 controls all operations of the above-described inspection device 1. The main functions of the control unit 10 will be described below with reference to Fig. 4. Although not shown, input devices such as a keyboard and a mouse are connected to the control unit 10.

[0027] The control unit 10 includes a storage unit 34, an imaging processing unit 35, a cross-sectional image generating unit 36, a substrate inspection surface detecting unit 38, a pseudo-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 light source driving unit 16, the holder driving unit 18, and the detector driving unit 20. Furthermore, each of these functional blocks is realized by 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.

[0028] The storage unit 34 stores information such as imaging conditions for capturing a transmission image of a substrate, which is the inspected object 12, and the design of the substrate. The storage unit 34 also stores image data such as transmission images and reconstructed images (cross-sectional images, pseudo-cross-sectional images) of the substrate, as well as inspection results of the inspection unit 42, which will be described later. The storage unit 34 also stores information for driving the light source drive unit 16, the holder drive unit 18, and the detector drive unit 20 (for example, the position of the radiation generator 22, the position (turning trajectory) and speed at which the holder drive unit 18 moves the holder 24, and the position (turning trajectory) and speed at which the detector drive unit 20 moves the detector 26, etc.).

[0029] The imaging processing unit 35 moves the radiation generator 22, the holder 24, and the detector 26 using the light source driving unit 16, the holder driving unit 18, and the detector driving unit 20, captures an image of the inspected object 12 held by the holder 24, acquires transmission image data, and generates reconstructed image data (cross-sectional image data) from the transmission image data. The methods of acquiring transmission image data (capturing a transmission image) and generating reconstructed image data (cross-sectional image data) by the imaging processing unit 35 will be described later.

[0030] The cross-sectional image generator 36 generates reconstructed image data (cross-sectional image data) based on the multiple transmission image data 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 data and different reconstruction times. Therefore, multiple reconstruction algorithms and parameters used for the algorithms may be prepared in advance and the user may select one. This provides the user with the freedom to choose, for example, prioritizing a shorter reconstruction time or higher image quality even if it takes longer. Each of the generated cross-sectional image data is stored in the storage unit 34 along with attribute information, such as information determining the position of each cross-sectional image data in the Z-axis direction and the positions (coordinates) of pixels in the cross-sectional image data in the X-axis and Y-axis directions.

[0031] The substrate inspection surface detection unit 38 identifies image data (cross-sectional image data) that shows the surface to be inspected on the substrate, which is the inspected object 12 (for example, the top surface of the substrate, which will be referred to as the "substrate inspection surface") from the multiple cross-sectional image data generated by the cross-sectional image generation unit 36. Hereinafter, the cross-sectional image (cross-sectional image data) that shows the substrate inspection surface of the substrate will be referred to as the "inspection surface image (inspection surface image data)."

[0032] The pseudo cross-sectional image generating unit 40 stacks a predetermined number of consecutive cross-sectional images (cross-sectional image data) from the cross-sectional image data generated by the cross-sectional image generating unit 36 ​​to image a region of the substrate that is thicker than the cross-sectional image. The number of cross-sectional images to be stacked is determined based on the thickness of the region of the substrate represented 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 used as the slice thickness for the pseudo cross-sectional image, then 500 / 50 = 10 cross-sectional images should be stacked. In this case, the inspection surface image data identified by the substrate inspection surface detecting unit 38 is used to identify the position of the solder.

[0033] The inspection unit 42 is configured to execute various control processes for inspection using the cross-sectional image data generated by the cross-sectional image generation unit 36, the inspection surface image data identified by the board inspection surface detection unit 38, and the pseudo cross-sectional image data generated by the pseudo cross-sectional image generation unit 40, based on the board inspection data stored in the memory unit 34. Here, the board inspection data is inspection data created for each type of board. An inspection area (hereinafter referred to as an "inspection window") is set for each inspection location on the image data of the inspected object 12, and the inspection data is composed of inspection items set for each inspection window and inspection criteria that serve as the basis for determining whether the product is acceptable or not. One or more inspection windows are set for each inspection item. For example, in an inspection item that determines the quality of solder application, typically, the same number of inspection windows as the number of solder application areas on the component are set in an arrangement corresponding to the arrangement of the solder application areas. Furthermore, for inspection items that use image data that has undergone predetermined image processing on the inspected object 12, the details of the image processing are also included in the inspection data.

[0034] The inspection unit 42 inspects the solder joint state. Because the solder that joins the board and the component is located near the inspection surface of the board, it is possible to determine whether the solder is properly joining the board and the component by inspecting the inspection surface image data and the cross-sectional image data that shows the area on the side of the radiation generator 22 relative to the inspection surface image data.

[0035] Here, "solder joint condition" refers to whether or not a proper conductive path is formed when the board and the component are joined by solder. Inspection of the solder joint condition includes bridge inspection, melting condition inspection, and void inspection. A "bridge" refers to an undesirable conductive path between conductors caused by the solder joining. Furthermore, a "melting condition" refers to whether or not the joint between the board and the component is insufficient due to insufficient solder melting, i.e., whether or not there is a so-called "float." A "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 melting condition inspection unit 46, and a void inspection unit 48.

[0036] The processes performed by the bridge inspection unit 44, the molten state inspection unit 46, and the void inspection unit 48 will be described later, but the bridge inspection unit 44 and the void inspection unit 48 inspect bridges and voids, respectively, based on the pseudo cross-sectional image data 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 data identified by the board inspection surface detection unit 38. The inspection results from the bridge inspection unit 44, the molten state inspection unit 46, and the void inspection unit 48 are stored in the memory unit 34.

[0037] 5 to 7 are flowcharts showing the flow (inspection process) of capturing a transmission image (acquiring transmission image data), generating reconstructed image data (cross-sectional image data), specifying inspection surface image data, generating a pseudo cross-sectional image, and performing the inspection (acquiring the solder joint state, etc.). 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).

[0038] 5 , when the inspection is started, the control unit 10 carries the inspected object 12 into the carry-in position in the inspection apparatus 1 and holds it with the holding unit 24, and moves the holding unit 24 and the detector 26 to the standby position (step S100). Next, the imaging processing unit 35 of the control unit 10 sets an irradiation field of radiation emitted from the radiation generator 22 by the light source driving unit 16 (an imaging region to which radiation is irradiated in order to obtain transmission image data of the above-mentioned field of view FOV), and when there are multiple imaging regions (fields of view FOV) on the inspected object 12, selects one imaging region from among them (step S102), and starts the transmission image capturing / reconstruction image generation process (step S104).

[0039] 6, when the transmission image capturing / reconstruction image generating process S104 is started, the imaging processing unit 35 of the control unit 10 starts the holding unit 24 and the detector 26 (step S1041), and as described with reference to FIG. 2, the holding unit 24 and the detector 26 are inserted into the rotation orbits (holding unit rotation orbit 28 and detector rotation orbit 30) via the insertion orbit 28i to start rotational movement (note that the insertion orbit and the retreat orbit of the detector 26 are not shown or numbered here). Then, while the holding unit 24 and the detector 26 are moving on the rotation orbits 28 and 30, the imaging processing unit 35 determines whether the holding unit 24 and the detector 26 are located at the imaging positions (P1 to P8 in FIG. 2) (S1042). If it is determined that the holding unit 24 and the detector 26 are not located at the imaging positions (step S1042: N), the imaging processing unit 35 repeats the determination of step S1042. On the other hand, when it is determined that the detector 26 is at the imaging position (step S1042: Y), the imaging processing unit 35 captures a transmission image of the inspection object 12 with the detector 26 and stores the transmission image data in the storage unit 34 (step S1043), and determines whether imaging has been completed at all imaging positions (step S1044). When it is determined that there is an imaging position at which a transmission image has not yet been captured (step S1044: N), the imaging processing unit 35 returns to step S1042 and repeats the above-described process. On the other hand, when it is determined that transmission images have been captured at all imaging positions (step S1044: Y), the imaging processing unit 35 moves the holder 24 and the detector 26 from the insertion position Pin of the rotation orbits 28, 30 via the retraction orbit 28o to the retraction position PE and stops them (step S1045).

[0040] When the transmission image is captured, the cross-sectional image generation 36 of the control unit 10 generates reconstructed image data (cross-sectional image data) using the transmission image data stored in the memory unit 34 and stores it in the memory unit 34 (step S1046), thereby completing the transmission image capture / reconstructed image generation process S104.

[0041] It is assumed that the movement path of the holder 24 driven by the holder driving unit 18 and the movement path of the detector 26 driven by the detector driving unit 20 when acquiring the transmission image data are set in advance in the holder driving unit 18 and the detector driving unit 20 by reading information stored in the storage unit 34 or by inputting the information from an input device. It is also assumed that the position of the radiation generator 22 in the Z-axis direction is set in advance in the light source driving unit 16 by a similar method. The acquired transmission image data is stored in the storage unit 34 for each imaging region (FOV). The radiation generator 22 may be configured to irradiate the inspection object 12 with radiation continuously during the rotational movement, or may be configured to irradiate only when the inspection object 12 is at the imaging position and a transmission image is captured by the detector 26.

[0042] 5 , the board inspection surface detection unit 38 of the control unit 10 receives the transmission image data or reconstructed image data (cross-sectional image data) from the cross-sectional image generation unit 36 ​​and executes a board inspection surface detection / pseudo-sectional image generation process to identify an inspection surface image from the received data (step S106). Here, the storage unit 34 pre-stores cross-sectional image data (referred to as "reference image data") of the board inspection surface of a normal object 12 to be inspected, which has no abnormalities in the solder joint state, etc. In the board inspection surface detection / pseudo-sectional image generation process S106, the board inspection surface detection unit 38 of the control unit 10 compares the reference image data with each of the cross-sectional image data generated in step S1046 of step S104, identifies the cross-sectional image data that most closely matches the reference image data as the inspection surface image data, and stores the identified cross-sectional image data (inspection surface image data) in the storage unit 34, and also stores its position in the Z-axis direction as the position of the board inspection surface in the current field of view FOV in the storage unit 34. The cross-sectional image data most closely matching the reference image data can be identified from the cross-sectional image data by, for example, using a phase-only correlation method, which allows the inspection surface image data to be identified quickly and with a high degree of matching regardless of positional deviation. The pseudo cross-sectional image generating unit 40 of the control unit 10 generates pseudo cross-sectional image data based on the identified inspection surface image data and the position of the substrate inspection surface in the Z-axis direction, and stores the data in the storage unit 34.

[0043] Here, multiple cross-sectional image data are generated as reconstructed image data from the transmission image data, and reference image data is determined and pseudo-cross-sectional image data is generated for these cross-sectional image data. However, each time a piece of cross-sectional image data is generated as reconstructed image data, the reference image data may be determined and pseudo-cross-sectional image data may be generated, and the next cross-sectional image data may be generated.

[0044] Next, the inspection unit 42 of the control unit 10 selects one of the inspection windows set in the current field of view (FOV) (step S108), and executes the judgment process (inspection) set in that inspection window (step S110). Various judgment processes can be set in the inspection window, but here, the process of judging the solder joint state will be described as an example.

[0045] In the above-mentioned judgment process S110, when the inspection unit 42 determines that the inspection in the currently selected inspection window is an inspection of the solder joint condition, the inspection unit 42 of the control unit 10 executes the joint condition judgment process shown in Figure 7 for the currently selected inspection window.

[0046] First, the bridge inspection unit 44 of the control unit 10 acquires pseudo cross-sectional image data of a slice thickness equivalent to that of the solder balls from the pseudo cross-sectional image generation unit 40 (read from the storage unit 34) and inspects the currently selected inspection window for the presence or absence of bridges (step S1101). If no bridges are detected (step S1102: N), the molten state inspection unit 46 of the control unit 10 acquires inspection surface image data from the board inspection surface detection unit 38 (read from the storage unit 34) and inspects the currently selected inspection window for the presence or absence of molten solder (step S1103). If the solder is molten (step S1104: Y), the void inspection unit 48 of the control unit 10 acquires pseudo cross-sectional image data of a portion of the solder balls from the pseudo cross-sectional image generation unit 40 (read from the storage unit 34) and inspects the currently selected inspection window for the presence or absence of voids (step S1105). If no voids are found (step S1106: N), the inspection unit 42 of the control unit 10 determines that the solder joint condition in the currently selected inspection window is normal and outputs this information to the storage unit 34 (step S1107). If a bridge is detected (step S1102: Y), the solder is not melted (step S1104: N), or a void is present (step S1106: Y), the inspection unit 42 determines that the solder joint condition in the currently selected inspection window is abnormal and outputs this information to the storage unit 34 (step S1108). Once the solder condition is output to the storage unit 34, the joint condition determination process in this flowchart is terminated. Note that the bridge inspection, melting state inspection, and void inspection may be performed in parallel.

[0047] 5, when the determination process S110 for the currently selected examination window is completed, the examination unit 34 of the control unit 10 determines whether or not there is a next examination window (step S112). If it is determined that there is a next examination window (step S112: Y), the process returns to step S108, selects the next examination window, and repeats the determination process. On the other hand, if the examination unit 34 of the control unit 10 determines that the determination process for all examination windows has been executed (step S112: N), the imaging processing unit 35 of the control unit 10 determines whether or not there is a next imaging field of view (FOV) (step S114). If it is determined that there is a next imaging field of view (step S114: Y), the process returns to step S102, selects the next imaging field of view (FOV), and repeats the image acquisition and determination process. On the other hand, if the imaging processing unit 35 of the control unit 10 determines that there is no next imaging area (FOV) (step S114: N), the inspection process is terminated, and the control unit 10 moves the holding unit 24 to the removal position and removes the object to be inspected 12 from the inspection device 1 (step S116).

[0048] As described above, the image acquisition and determination process may be performed for each imaging region (FOV), or the examination may be performed in parallel with the acquisition of transmission image data and the generation of reconstructed image data for other imaging regions (FOV), starting from the imaging region (FOV) for which the generation of reconstructed image data (cross-sectional image data and pseudo-cross-sectional image data) has been completed.

[0049] As described above, the inspection device 1 according to this embodiment is configured such that, when capturing a transmission image of the inspected object 12, the holder 24 and the inspector 26 are started from the standby position PS, and then the holder 24 and the inspector 26 are inserted into the revolving orbits 28, 30 from the insertion position Pin via the insertion orbit 28i. At this time, the holder 24 and the inspector 26, which are stopped on the insertion orbit 28i, are accelerated to a predetermined speed and inserted into the revolving orbits 28, 30, so that noise and vibrations are generated in the holder drive unit 18 and the detector drive unit 20 during acceleration. In particular, the noise and vibrations generated by the holder drive unit 18, which moves the heavy holder 24, have a large effect, and it is necessary to suppress the generation of this noise and vibration from the holder drive unit 18.

[0050] Because the holder driver 18 is an H-shaped XY stage, the direction of the insertion orbit 28i can be set taking into account the weights moved by the X driver 18e and the Y driver 18c, thereby suppressing noise and vibrations generated during acceleration. Specifically, for the linear insertion orbit 28i extending from the standby position PS to the insertion position Pin, the X-axis component of the weight moved by the X driver 18e is compared with the Y-axis component of the weight moved by the Y driver 18c, and the standby position PS and the insertion position Pin are determined so that the larger value is minimized. The insertion orbit 28i is set perpendicular to the line connecting the center of the holder rotation orbit 28 (the intersection of the holder orbit plane and the axis A) and the insertion position Pin (i.e., if the holder rotation orbit 28 is a circle, the insertion orbit 28i is set to a tangent to the circle at the insertion position Pin). This suppresses noise and vibrations generated when the insertion orbit 28i is transferred to the holder rotation orbit 28.

[0051] Using FIG. 8 , the relationship between the holder rotation path 28 and the insertion path 28i for suppressing noise and vibration when accelerating the holder 24 will be further described. As shown in FIG. 8( a), the angle between a line in the X-axis direction (X-axis) passing through the intersection of the holder path plane and the axis A (as described above, this is the rotation center of the holder rotation path 28, and is designated "point O" in FIG. 8( a)) and a line L connecting the intersection O and the insertion position Pin (P1) is defined as θ. Note that the angle θ is positive in the rotation direction, and is in the range of 0°<θ<90°. Assuming that the insertion path 28i and the line L are perpendicular to each other, when weights α and β are moved along the insertion path 28i, as shown in FIG. 8( b), the components (α·cos θ, β·sin θ) of the weights (α, β) moved by the X drive unit 18e and the Y drive unit 18c in the movement direction of each drive unit are as shown in FIG. 8( b). At this time, the generation of noise and vibration can be suppressed by setting the standby position PS and the insertion position Pin so that the angle θ minimizes n, which is calculated using the following equation (1): Note that max() is a function that selects the maximum value among the numerical values ​​set as arguments.

[0052] n = max (α·cos θ, β·sin θ) (1) where, α: weight moved by the X driving unit 18e, and β: weight moved by the Y driving unit 18c.

[0053] Of the weights (α, β) moved by the X drive unit 18e and the Y drive unit 18c, the components (α cos θ, β sin θ) in the direction of movement of each drive unit contribute to the generation of noise and vibration during acceleration. Furthermore, between the weight of the X-axis component of the weight moved by the X drive unit 18e (α cos θ) and the weight of the Y-axis component of the weight moved by the Y drive unit 18c (β sin θ), the larger one contributes more to the generation of noise and vibration during acceleration (the greater the weight, the more noise and vibration are generated during acceleration). Therefore, when the X-axis component of the weight moved by the X drive unit 18e and the Y-axis component of the weight moved by the Y drive unit 18c are compared and the larger value is selected (the selected value is n), the insertion trajectory 28i (the standby position PS and the insertion position Pin are set) is based on the θ that minimizes this value of n, thereby suppressing the generation of noise and vibration during acceleration.

[0054] In addition, noise and vibration are also generated when the holding unit 24 and the detector 26 stop, but by determining the evacuation position PE so that the evacuation orbit 28o is located on an extension of the insertion orbit 28i, it is possible to effectively suppress the generation of noise and vibration when moving from the holding unit rotation orbit 28 to the evacuation orbit 28o, as well as the generation of noise and vibration when decelerating and stopping on the evacuation orbit 28o.

[0055] As an example of the inspection device 1 according to this embodiment, the angle θ at which the value n in equation (1) is minimized when the weight α moved by the X drive unit 18e and the weight β moved by the Y drive unit 18c are changed is shown in Table 1 below. The weights α and β are generally measured in units of "kg," but are not limited to this. The unit of θ is "°." FIG. 9 shows the relationship between n and θ in each example.

[0056] (Table 1) α β θ Example 1 8 12 35 Example 2 10 10 45 Example 3 15 5 75

[0057] Furthermore, for the sake of simplifying coordinate calculations and making it easier to understand visually, if it is determined that there is not much difference between the weight α moved by the X drive unit 18e and the weight β moved by the Y drive unit 18c, it has been found that even if the angle θ is set to 45°, the generation of noise and vibration during acceleration can be suppressed to a certain extent.

[0058] As described above, by setting the direction of the insertion orbit 28i and the evacuation orbit 28o so that the larger of the weight of the X-axis component of the weight moved by the X drive unit 18e and the weight of the Y-axis component of the weight moved by the Y drive unit 18c is the smallest, it is possible to suppress the generation of noise and vibration when the holding unit 24 accelerates and decelerates, or when it is inserted into and evacuated from the turning orbit.

[0059] REFERENCE SIGNS LIST 1 Inspection device 10 Control unit 12 Inspected object 18 Holder driving unit 18c Y driving unit (second driving unit) 18e X driving unit (first driving unit) 20 Detector driving unit 22 Radiation generator (light source) 24 Holder 26 Detector 28 Holder rotation orbit 28i Insertion orbit 28o Avoidance orbit 30 Detector rotation orbit

Claims

1. A device comprising: a light source which emits light along an axis extending in a third direction; a holder which holds the object to be inspected and which moves in a predetermined orbit about the axis on a holder orbit plane which is a plane perpendicular to the axis; a detector which detects light which is emitted from the light source and which has passed through the object to be inspected by moving in a predetermined orbit about the axis on a detector orbit plane which is a plane perpendicular to the axis and different from the holder orbit plane; a holder drive unit which moves the holder; and a control unit which controls the operation of the holder drive unit, wherein the holder drive unit comprises: a first drive unit which moves the holder in a first direction on the holder orbit plane; and a second drive unit which moves the holder in a second direction perpendicular to the first direction on the holder orbit plane, An inspection device in which a control unit controls the operation of the first drive unit and the second drive unit to move the holding unit, which is stopped at a waiting position outside the rotation orbit on the holding unit orbit plane, on a linear input orbit from the waiting position to a putting-in position on the rotation orbit, and to rotate the holding unit from the putting-in position on the rotation orbit, and determines the waiting position and the putting-in position so that the larger of the first directional component of the weight moved by the first drive unit and the second directional component of the weight moved by the second drive unit is smallest when the holding unit moves on the input orbit.

2. The inspection device according to claim 1, wherein a straight line connecting the intersection of the holding portion track surface and the axis to the insertion position is perpendicular to the insertion track.

3. The inspection device according to claim 2, which determines the waiting position and the insertion position so that n obtained by the following formula is minimized: n = max (α·cos θ, β·sin θ), where α: weight moved by the first drive unit, β: weight moved by the second drive unit, θ: angle between a straight line in a first direction passing through an intersection between the holding unit track surface and the axis, and a straight line connecting the intersection and the insertion position (0°<θ<90°, the rotation direction is positive), max(): function that selects the maximum value among the numerical values ​​set in the arguments.

4. An inspection device as described in any one of claims 1 to 3, wherein the control unit controls the operation of the holding unit drive unit so as to move the holding unit, which is moving in a revolving manner on the revolving orbit, along a linear reversal orbit from the insertion position on the revolving orbit to a reversal position outside the revolving orbit on the holding unit orbit plane and stop the holding unit thereon, and determines the reversal position so that the reversal orbit is located on an extension of the insertion orbit.