JP5396751B2 - Board inspection equipment using X-rays - Google Patents

Description

  The present invention relates to a board inspection apparatus that generates a tomographic image by X-ray for a component mounting board, and inspects a bonding state between a component side electrode and a board, an internal structure of a solder electrode, and the like using the generated image. .

  In general X-ray CT, as shown in FIG. 13, the X-ray source 100 and the X-ray detector 101 are arranged so as to face each other with the object F interposed therebetween, and the X-ray sources 100 and 2 for the object F are arranged. By performing X-ray fluoroscopic imaging a plurality of times while changing the orientation of the dimensional X-ray detector 101, an image necessary for reconstructing a tomographic image of the plane G through which X-rays pass is acquired.

  When the above method is applied to imaging of a substrate, the X-ray source 100 and the two-dimensional X-ray detector 101 are moved along the periphery of the substrate so that a plane orthogonal to the thickness of the substrate becomes a plane G. Alternatively, the substrate needs to be rotated about the thickness direction. However, with such a method, it is difficult to increase the enlargement ratio of the part to be inspected on the substrate, and a virtual image may be generated by beam hardening.

  As an invention for solving the above-mentioned problem, the following Patent Document 1 discloses that a substrate to be inspected is supported on a eucentric table whose rotation axis can be set at an arbitrary position, and the rotation axis of this table is inclined. An X-ray source and a two-dimensional X-ray detector are arranged opposite each other in the direction crossing the X-ray, and X-ray fluoroscopic imaging is performed multiple times while rotating the table by a minute angle, and each generated X-ray fluoroscopic image is rotated. It describes that a tomographic image is reconstructed by converting it into an image that has been transmitted from a direction perpendicular to the axis (see paragraphs 0009, 0012, 0013, and FIG. 1 of Patent Document 1).

  Next, tomosynthesis is a method for generating a tomographic image of a substrate more easily than X-ray CT. For example, in Patent Document 2, an X-ray source is disposed with its optical axis facing directly above, an XY stage that supports a substrate above it, and an XY stage that supports a two-dimensional X-ray detector above it. Arrange each and stop each predetermined angle while moving each XY stage along a circular orbit centered on the optical axis of the X-ray source, or synthesize the images generated by each shooting It is described that a tomographic image is generated (see paragraphs 0077 to 0100 and FIGS. 12 to 17 of Patent Document 2).

  As described in Patent Document 2, in tomosynthesis imaging, a target plane is projected onto the same coordinates of an hourly image while the upper and lower planes of the target plane are projected onto the same coordinates. The relationship between the X-ray source, the X-ray detector and the substrate in the hourly imaging is adjusted so that each component point is projected onto a different coordinate for each imaging. As a result, when the images are combined, the constituent points of the target plane are superimposed and clarified, while the constituent points of the other planes become unclear, so that a tomographic image with reduced noise is generated for the target plane Can do.

Japanese Patent No. 3694833 JP 2005-121633 A

  Comparing tomographic images with tomosynthesis and X-ray CT images, the latter is superior in terms of accuracy. However, in X-ray CT, the number of imaging operations is increased and the calculation is complicated, so that the time required for generating a tomographic image becomes longer. On the other hand, according to tomosynthesis, the number of times of imaging can be reduced and the calculation is simple, so that a tomographic image can be obtained in a relatively short time. On the other hand, according to tomosynthesis, a noise component that cannot be ignored may be included in a tomographic image depending on the shape of the region to be inspected and the relationship with surrounding components.

  Under such circumstances, a company that manufactures and inspects a substrate desires to select and execute X-ray CT and tomosynthesis according to the type of the part to be inspected and the state of the surrounding of the part to be inspected. ing. However, an inspection apparatus having both functions has not been presented so far.

  In view of the above, the present invention provides a substrate inspection apparatus having both a function of generating an X-ray CT image and a function of generating a tomosynthesis tomographic image, thereby improving the convenience of substrate inspection by X-rays. The issue is to significantly improve.

  A substrate inspection apparatus according to the present invention includes a substrate stage that supports a substrate to be inspected in a state where the substrate surface is horizontal, and an X-ray source that is fixedly disposed above or below the substrate stage with the optical axis oriented vertically. A two-dimensional X-ray detector, a detector stage that supports the two-dimensional X-ray detector at a position facing the X-ray source across the substrate stage, and a predetermined inspection of the substrate by controlling each of the above components And a control unit that generates an X-ray tomographic image of the region.

In the above, the substrate stage supports the substrate so that the substrate can be moved horizontally by linear movement mechanisms each having a drive shaft in two directions corresponding to the respective edge directions of the substrate being supported, and the detector stage is configured to drive each of the substrate stages. a linear moving mechanism with a parallel drive shaft respectively to the shaft by a rotating mechanism for rotating the direction axis orthogonal to the detection surface of the two-dimensional X-ray detector, horizontally movable and axially rotating the two-dimensional X-ray detector Support as possible.

In addition, the above-described control unit is configured so that the position of the two-dimensional X-ray detector in each of a plurality of X-ray fluoroscopic imaging necessary for generating an X-ray tomographic image of the examination region is a virtual centered on the optical axis of the X-ray source. The substrate is stopped in a positional relationship necessary for X-ray fluoroscopic imaging of the inspection region with respect to the two-dimensional X-ray detector and the X-ray source that have changed on the circle and stopped when the two-dimensional X-ray detector is stopped. In addition, the operation of each linear movement mechanism of the substrate stage and the detector stage is controlled, and X-ray fluoroscopic imaging using an X-ray source and a two-dimensional X-ray detector is executed in accordance with the stop of each stage. Further, when generating an X-ray CT image for an examination area, the operation of the rotation mechanism of the detector stage is controlled so that the posture of the two-dimensional X-ray detector at the time of imaging differs with the examination area. On the other hand, when a tomosynthesis tomographic image is generated for the examination region, the rotation mechanism is stopped in a state where the direction of each coordinate axis of the two-dimensional X-ray detector is aligned with the direction of each drive axis of the detector stage .

  According to the above configuration, when X-ray CT imaging is performed, the X-ray source and the two-dimensional X-ray detector are fixed and the substrate is rotated about the vertical axis passing through the inspection region. In this state, the positions of the two-dimensional X-ray detector and the substrate in the hourly imaging and the attitude of the two-dimensional X-ray detector with respect to the inspection region can be changed so that X-ray fluoroscopic imaging is performed on the inspection region. In addition, when imaging for tomosynthesis, a two-dimensional X-ray detector in hourly imaging is used so that a constituent point of a predetermined plane in the examination region is always projected onto the same coordinates of the two-dimensional X-ray detector. And the position of the inspection area can be changed. Therefore, since X-ray CT imaging and tomosynthesis imaging can be selected and executed, the examination to be performed can be selected according to the type of the region to be inspected and the surrounding condition. , Can improve convenience.

  In the above-described substrate inspection apparatus, in a preferable aspect in the case of generating an X-ray CT image for the inspection region, the control unit is centered on the optical axis of the X-ray source while the two-dimensional X-ray detector rotates in a certain direction. And a two-dimensional X-ray detector for controlling the operation of the detector stage so as to move linearly to a plurality of positions of the virtual circle in the order along the virtual circle, and to temporarily stop the movement and shaft rotation at each position. The movement of the substrate stage is controlled so that the substrate moves linearly to a position corresponding to the next stop position of the two-dimensional X-ray detector and stops at that position.

  According to the above control, the two-dimensional X-ray detector is moved linearly along the virtual circle, and the substrate is also moved linearly in conjunction with the movement of the two-dimensional X-ray detector. Can move well. Further, by rotating the two-dimensional X-ray detector in a certain direction, it is possible to efficiently change the posture of the two-dimensional X-ray detector with respect to the examination region.

  Furthermore, in a preferable aspect in the case where X-ray fluoroscopic imaging is sequentially performed on a plurality of examination areas for generating an X-ray CT image, the control unit at that time according to the end of the imaging cycle corresponding to the preceding examination area. The position of the two-dimensional X-ray detector with respect to the X-ray source and the posture with respect to the inspection region are maintained, and the next inspection region is necessary for X-ray fluoroscopy with respect to the two-dimensional X-ray detector and the X-ray source. The imaging cycle corresponding to the next inspection area is started after the substrate is moved so as to be in a relationship, and the cycle in which the moving direction and the axis rotation direction of the two-dimensional X-ray detector in this cycle are the previous one Control to be the opposite.

  According to the above aspect, when a plurality of X-ray fluoroscopic imagings for one examination area are completed and imaging for the next examination area is started, only the position of the substrate is moved without moving the two-dimensional X-ray detector. This can be accommodated by adjusting According to such control, it is possible to shorten the processing time by eliminating useless movement of the two-dimensional X-ray detector. Further, when the two-dimensional X-ray detector is rotated, the cable connecting the two-dimensional X-ray detector and the control unit is twisted. According to the above control, an imaging cycle corresponding to one inspection region is generated. Each time the process is finished, the moving direction and the rotating direction of the two-dimensional X-ray detector are reversed, so that the twisting of the cable can be eliminated naturally.

Next, in a preferable aspect when generating a tomosynthesis tomographic image for the examination region, the control unit maintains a state in which the two-dimensional X-ray detector matches the direction of each coordinate axis with the direction of each drive axis of the detector stage . The detector stage is controlled to move linearly in the order along the virtual circle to a plurality of positions of the virtual circle centered on the optical axis of the X-ray source, and to temporarily stop the movement at each position. The substrate stage is moved so that the substrate moves linearly to a position corresponding to the next stop position of the two-dimensional X-ray detector and stops at the position in accordance with the movement and stop of the two-dimensional X-ray detector. Control the behavior.

  According to the above control, even when tomosynthesis imaging is performed, the movement path of the detector stage and the substrate stage can be shortened, and the time required for imaging can be shortened.

  Furthermore, in a preferable aspect in which imaging for tomosynthesis is sequentially performed on a plurality of examination areas, the control unit detects a two-dimensional X-ray detector at that time according to the end of the imaging cycle corresponding to the preceding examination area. The next inspection is performed after the substrate is moved so that the next inspection region is in a positional relationship necessary for X-ray fluoroscopic imaging with respect to the two-dimensional X-ray detector and the X-ray source while maintaining the position and orientation of The imaging cycle for the area is started, and the moving direction of the two-dimensional X-ray detector is kept constant until all imaging cycles for the plurality of examination areas are completed.

  According to the above control, when the two-dimensional X-ray detector is not moved unnecessarily and the imaging cycle for one examination area is completed, the imaging cycle for the next examination area can be quickly started.

  In another preferable aspect of the substrate inspection apparatus described above, the control unit is configured to perform a plurality of X-ray fluoroscopic imaging for generating X-ray tomographic images of a plurality of inspection regions in a predetermined order. A registration unit for registering an operation control sequence, an image storage unit for storing an X-ray fluoroscopic image, and X-ray fluoroscopic imaging for a plurality of examination regions are executed based on the sequence registered in the registration unit. Imaging control means for controlling the operation of each stage, X-ray source and two-dimensional X-ray detector, and X-ray fluoroscopic images generated by hourly imaging, respectively, corresponding inspection areas and two-dimensional X-ray detection at the time of imaging Image storage means for storing in the image storage means together with information for identifying the stop position of the container.

  According to said aspect, it is suitable for moving an X-ray detector and a board | substrate efficiently based on the relationship between the distance between test | inspection area | regions, the distance and direction in the stop position of the X-ray detector with respect to each test | inspection area | region, etc. By registering a sequence and performing imaging for a plurality of examination areas in parallel based on the sequence, it becomes possible to perform imaging more efficiently than performing X-ray fluoroscopy for each examination area in order. In addition, after a series of imaging is completed, the process of specifying the fluoroscopic image for each examination region and the process of recognizing the relationship between the images can be performed without error based on the identification information stored together with the image. Therefore, there is no possibility that the generation of the tomographic image will be hindered.

  Since the above-described substrate inspection apparatus has a function of generating both an X-ray CT image and a tomosynthesis tomographic image, a tomographic image can be generated by any method depending on the type of the region to be inspected and the surrounding state. The inspection can be executed by selecting whether to perform the inspection, and the convenience of the substrate inspection using the X-ray tomographic image can be improved.

  The following X-ray-based board inspection devices reconstruct X-ray tomographic images for areas where visual inspection is difficult, such as back fillets formed on IC leads and solder electrodes that make up the BGA. The inspection using the generated tomographic image is performed. Further, the substrate inspection apparatus of this embodiment has a function of generating an X-ray CT image and a function of generating a tomosynthesis tomographic image as a tomographic image.

FIG. 1 shows a schematic configuration of an imaging processing unit of the substrate inspection apparatus.
In the figure, reference numeral 1 denotes a substrate stage that supports a substrate 10 to be inspected, below which an X-ray source 2 is fixedly arranged with its optical axis oriented in the vertical direction. A detector stage 4 is provided above the substrate stage 1. In the figure, reference numeral 11 denotes a component mounted on the substrate 10.

  In the above description, the substrate stage 1 includes a pair of conveyor portions 15a and 15b that support the substrate 10 at respective edge portions along the length direction (left and right direction in the figure, hereinafter referred to as the X direction), and each conveyor. A pair of conveyor support portions 16a and 16b for fixing and supporting the portions 15a and 15b, a linear movement mechanism 17 and a stopper 18 described later, and the like are provided. The conveyor units 15a and 15b receive the substrate 10 from an upstream mechanism (not shown), convey the substrate 10 to a position where it abuts against the stopper 18, and stop. The stopper 18 is provided so as to be able to appear and retract with respect to the conveyance path of the substrate 10, and is raised when the substrate 10 is carried in to fix the substrate, and is lowered when the inspection is completed. The conveyor parts 15a and 15b carry the substrate 10 out as the stopper 18 is lowered.

  The conveyor support portions 16a and 16b are supported by the linear moving mechanism 17 so as to be movable in the X and Y directions while supporting the conveyor portions 15a and 15b. The movement of the conveyor support portions 16a and 16b causes the substrate 10 to move horizontally (moves on a horizontal virtual plane).

  The detector stage 4 includes a pair of slide rails 41a and 41b (hereinafter referred to as “Y-axis rails 41a and 41b”) along the Y-axis direction, and a pair of slide rails 42a and 42b (hereinafter referred to as “Y-axis rails 41a and 41b”). X-axis rails 42a and 42b "). Each Y-axis rail 41a, 41b is provided with a pair of sliders 43, 44, respectively. Both ends of the X-axis rail 42a are supported by sliders 43 and 43 of the Y-axis rails 41a and 41b. Similarly, both ends of the X-axis rail 42b are supported by the sliders 44 and 44 of the Y-axis rails 41a and 41b.

  Large sliders 45 and 47 are provided on the X-axis rails 42a and 42b, respectively. A flat panel detector 3 (hereinafter abbreviated as “FPD3”) is attached to the slider 45 of the X-axis rail 42a as a two-dimensional X-ray detector via a rotation mechanism 46 having a rotation axis along the vertical direction. Yes. Further, the CCD camera 5 and the displacement sensor 6 are attached to the slider 47 of the X-axis rail 42b.

Each of the sliders 43, 44, 45, 47 constitutes a linear moving mechanism 48 shown in FIG. 2 together with a drive motor (not shown).
The FPD 3, the CCD camera 5, and the displacement sensor 6 move along the X-axis direction according to the movements of the corresponding sliders 45 and 47, and in the Y-axis direction according to the movements of the sliders 43 and 44 of the Y-axis rails 41a and 41b. Move along. Further, the FPD 3 rotates about the direction orthogonal to the detection surface 31 (shown in FIGS. 3 and 4) as an axis according to the movement of the rotation mechanism 46.

  The FRP 3 is connected to the control device 7 shown in FIG. Although not shown in FIG. 1, the X-ray source 2, the CCD camera 5, the displacement sensor 6, and the drive units of the stages 1 and 4 are also cable-connected to the control device 7.

  The CCD camera 5 and the displacement sensor 6 are used for the purpose of checking the state of the substrate 10 before inspection. Specifically, the CCD camera 5 images the fiducial mark 19 on the substrate 10 in order to align the substrate 10 at an accurate position. An image generated by this imaging is input to the control device 7 and used to measure the amount of positional deviation of the substrate 10, and the positional relationship between the stages 1 and 4 is adjusted based on the measured value.

  The displacement sensor 6 measures the distance to the upper surface of the substrate 10. The measured distance data is also input to the control device 7 and used for the purpose of adjusting the height of a reference plane T, which will be described later, at the time of fluoroscopic imaging.

FIG. 2 is a block diagram of the main part of the substrate inspection apparatus.
In addition to the imaging processing unit shown in FIG. 1, this board inspection apparatus is provided with a control device 7 that performs control related to fluoroscopic imaging, an image processing device 8 that performs tomographic image reconstruction processing and inspection, and the like. These devices 7 and 8 are each constituted by a personal computer in which a dedicated program is installed.

  In addition to the CPU 70 and the memory 71, the control device 7 is provided with a stage control unit 72, an X-ray controller 73, a detector controller 74, an image input unit 75, and the like. These are all dedicated interfaces. The stage control unit 72 is connected to the linear movement mechanisms 17 and 48 of the substrate stage 1 and the detector stage 4 and the rotation mechanism 46 of the FPD 3. The X-ray source 2 and the FPD 3 are connected to the detector controller 74, respectively. The image input unit 75 is for capturing and digitally converting the X-ray fluoroscopic image generated by the FPD 3, and the converted image is stored in the memory 71.

  The CPU 70 performs X-ray fluoroscopic imaging (projection) on the substrate 10 while variously changing the relationship between the X-ray source 2, the FPD 3, and the substrate 10 by controlling the operation of each mechanism through the various interfaces described above. . Although not shown here, the control device 7 is also connected to the CCD camera 5, the displacement sensor 6, and the conveyor portions 15 a and 15 b described above. The function of adjusting the position of the substrate 10 based on the input of the above and the set value of the height of the reference plane T at the time of photographing based on the input from the displacement sensor 6 are changed. A function of adjusting the amount of movement is also provided.

  The fluoroscopic image generated by the hourly fluoroscopic imaging is stored in the memory 71. The CPU 70 sets information for identifying the corresponding inspection region and the position of the FPD 3 at the time of photographing as additional information in these images, and stores these additional information in the memory 71 in association with the images. Further, the CPU 70 reads out an image generated by each photographing and transmits it to the image processing device 8 every time a plurality of photographing necessary for reconstruction of one tomographic image is completed. The image processing apparatus 8 executes a tomographic image reconstruction process using the transmitted image, and then processes the generated tomographic image using previously registered examination data, thereby determining the suitability of the part to be examined. judge. The determination result is output to a monitor or an external device (not shown).

  Hereinafter, the imaging process performed by the substrate inspection apparatus having the above configuration will be described in detail. In the following FIGS. 3 and 4, the vertical relationship between the X-ray source 2 and the FPD 3 is reversed in order to clarify the X-ray fluoroscopic state.

  FIG. 3 schematically shows the positional relationship between the X-ray source 2, the FPD 3, and the substrate 10 when a part of the substrate 10 is enlarged and imaging for tomosynthesis is performed. In the figure, 12 is one of solder electrodes for connecting the component 11, and 13 is a component mounted on the back side of the substrate 10 (hereinafter referred to as “backside component 13”). T is a plane that crosses a three-dimensional inspection region (not shown) including the solder electrode 12 along the horizontal direction, and is used as a reference for fluoroscopic imaging. A point O is a reference point set at a predetermined position on the plane T.

  In tomosynthesis imaging, the substrate 10 is moved and positioned so that the reference point O is aligned with two points P1 and P2 that are point-symmetric with respect to the optical axis L of the X-ray source 2. The FPD 3 is moved to positions (points Q1, Q2 in the figure) where the reference point O is projected onto the center point R of the detection surface 31 of the FPD 3, and photographing is performed at these positions. Since a conical beam is emitted from the X-ray source 2, the X-ray irradiation angles with respect to the reference point O at each position are substantially the same. Further, since the distances of the points P1 and P2 with respect to the optical axis L are equal, the distances of the points Q1 and Q2 with which the center point R of the detection surface 31 is aligned are also equal. Therefore, each point in the plane T including the reference point O is projected on the same coordinates on the detection surface 31 in photographing at any position of Q1 and Q2. On the other hand, points at different heights from the plane T, such as constituent points of the back surface component 13, are projected at different heights each time.

  Based on the above principle, in this embodiment, as shown in FIG. 4, a plurality of combinations of azimuths facing each other through the optical axis of the X-ray source 2 are selected, and in these azimuths, X-ray sources are respectively selected. 2, the FPD 3 and the substrate 10 control the operations of the linear moving mechanisms 17 and 48 of the substrate stage 1 and the detector stage 4 so as to stop with the same positional relationship as shown in FIG. Note that X1 and Y1 in FIG. 4 are drive axes of the detector stage 4, and are set in parallel to the drive axis of the substrate stage 1 (not shown), that is, in the direction along the edge direction of each direction of the substrate 10. In addition, the direction of each coordinate axis of the coordinate system of the two-dimensional image of the FPD 3 at this time is also matched with X1 and Y1.

  5 associates X-ray fluoroscopic images A1, A2, A3, and A4 generated by positioning the substrate 10 and the FPD 3 in the four directions shown in FIG. And a tomographic image B reconstructed by each image is arranged at the center of these images. For convenience of illustration, in each image, a portion having a high X-ray absorption rate (corresponding to a portion having a high gradation in the image data) is indicated by a hatched pattern.

  S1 to S4 in each of the images A1 to A4 are projection ranges of the solder electrodes 12, and U1 to U4 are projection ranges of the back surface component 13. As described with reference to FIG. 3, the constituent points of the solder electrode 12 on the plane T are projected on the same coordinates in any of the fluoroscopic images A1 to A4, but the constituent points of the back surface component 13 are projected. Coordinates vary depending on the image.

  In this embodiment, paying attention to the above points, for each set of pixels corresponding to each other, the pixel data indicating the lowest X-ray absorption rate in the set is selected, and each selected pixel is selected. A tomographic image B is generated from the data. According to this method, for the pixels corresponding to the projection ranges S1 to S4 of the solder electrode 12, data representing the solder electrode 10 is selected regardless of which image data is selected. On the other hand, since the image data (image data with the smallest noise component) on which the back surface component 13 is not projected is selected for a place other than the projection range of the solder electrode 10, the image of the back surface component 13 is displayed in the tomographic image B. Never appears.

  FIG. 6 schematically shows a change in the relationship between the X-ray source 2 and the FPD 3 when imaging for tomosynthesis is performed. In this example, the FPD 3 is stopped in eight directions including the four directions shown in FIG. 4 and the four directions in the middle of these directions, and photographing is performed.

  As described above, since the distance between the FPD 3 at the time of imaging and the optical axis L of the X-ray source 2 is always constant, the FPD 3 at the time of imaging is positioned on a virtual circle 300 centered on the optical axis L. It is thought that. Therefore, in this embodiment, the FPD 3 moves in order along the virtual circle 300 to the positions corresponding to the eight directions (that is, the FPD 3 is changed by 45 °) and paused at each position. Thus, the operation of the detector stage 4 is controlled. Although not shown in FIG. 6, the substrate 10 is similarly moved along a virtual circle centered on the optical axis L of the X-ray source 2, and the relationship shown in FIG. 3 is always obtained when the FPD 3 stops. The operation of the substrate stage 1 is controlled so as to stop at a position where the above is established. Further, by adjusting the movement amounts of the stages 1 and 4 in the X and Y directions, the substrate 10 and the FPD 3 are moved in a straight line so that the movement is performed efficiently.

  Next, FIG. 7 shows a change in the relationship between the X-ray source 2 and the FPD 3 when X-ray CT imaging is performed. As shown in this figure, in X-ray CT imaging, as in tomosynthesis imaging, the FPD 3 is straightened by a predetermined angle along a virtual circle 300 centered on the optical axis L of the X-ray source 2. Move to the shape. Although not shown in the drawing, as in the tomosynthesis imaging, the substrate 10 also has a single point in the plane T having a predetermined height as the reference point O, and the reference point O is the center point of the imaging surface 31 in any imaging. The operation of the substrate stage 1 is controlled so that the relationship projected onto R is maintained.

  Further, in X-ray CT imaging, the posture of the FPD 3 in hourly imaging is changed by moving the rotation mechanism 46 in accordance with the above movement. Specifically, the relative position and posture of the FPD 3 with respect to the substrate 10 change in the same state as when the substrate 10 is rotated about the vertical axis passing through the reference point O with the X-ray source 2 and the FPD 3 fixed. Thus, the FPD 3 is axially rotated.

  When a plurality of fluoroscopic imaging is performed based on the control shown in FIG. 7, the image processing apparatus 8 firstly normalizes the normal direction of the detection surface 31 of the FPD 3 with respect to the image generated by the imaging every hour. Is corrected for a distortion caused by not being aligned with the center line of the X-rays transmitted through the substrate, and the corrected image is converted into an image showing a state seen through from a direction orthogonal to the thickness of the substrate 10. Furthermore, the X-ray absorption rate of each component point of the plane to be processed is calculated using each converted image, and a tomographic image is generated.

  In the examples of FIGS. 6 and 7, the FPD 3 is stopped in all eight directions to perform imaging, but in actual processing, the number of imaging when reconstructing an X-ray CT image is generally that of tomosynthesis. It is set to a larger value than when a tomographic image is reconstructed. In addition, in the X-ray CT image reconstruction process, the calculation for the X-ray absorption rate is complicated. In particular, in order to obtain three-dimensional data for the examination region, it is necessary to execute an operation for calculating the X-ray absorption rate for each of a plurality of planes along the horizontal direction.

  On the other hand, in the reconstruction process of tomosynthesis tomographic images, the number of times of imaging can be reduced, and the calculation for reconstruction of tomographic images is simple, and the tomographic image can be generated in a short time. Also, when reconstructing a tomographic image of a plurality of planes in order to obtain three-dimensional data of the examination region, each X-ray fluoroscopic image is shift-corrected based on the ratio of the height to the reference plane for each plane. 5, the coordinates of the constituent points of the target plane in the image may be made the same, and the method shown in FIG. 5 may be applied. Can be shortened.

  Thus, according to tomosynthesis, a tomographic image can be acquired in a shorter time than when processing by X-ray CT is performed. However, a tomographic image generated by tomosynthesis may be superimposed with noise components from components that exist in places other than the target plane, so depending on the shape of the area to be inspected and the state of surrounding components, a large noise component May cause problems in the inspection. For this reason, in this embodiment, when the inspection area is defined on the substrate 10 before the inspection, the X-ray CT image or the tomosynthesis tomographic image is selected for each inspection area. The selection result is registered in a memory 71 of the control device 7 or a memory (not shown) of the image processing device 8. Further, in the inspection, the inspection area corresponding to the same photographing mode is continuously processed based on the registration information in the memory 71, and the control as shown in FIGS. 8 and 9 is executed for each photographing mode.

  8 and 9, for simplicity of explanation, the number of times of photographing is set to four times in accordance with the example of FIG. 4, and the stop position of the FPD 3 in each photographing is indicated by symbols A, B, C, and D, respectively. Show. In each example, the movement of the substrate 10 is not shown, but as described above, a series of imaging (hereinafter referred to as “imaging for one cycle”) is performed on one inspection region. The substrate 10 moves toward a position satisfying the conditions shown in FIG. 3 according to the movement of the FPD 3 and stops at that position. In each embodiment, the height of the reference plane T in each inspection region is constant so that it is not necessary to move the FPD 3 when imaging for one inspection region is completed and imaging for the next inspection region is started. The height is unified.

FIG. 8 shows a method for performing X-ray CT imaging.
In this embodiment, the direction of movement of the FPD 3 and the direction of axial rotation are controlled clockwise (hereinafter referred to as “clockwise mode”), and the direction of movement of the FPD 3 and the direction of axial rotation are counterclockwise. The control (hereinafter referred to as “counterclockwise mode”) is performed for one cycle of photographing (in this embodiment, four photographings at positions A, B, C, and D constitute one cycle. ) To switch each time. Further, by maintaining the position and posture of the FPD 3 when the last imaging of the previous inspection area is performed and performing the first imaging of the next inspection area, unnecessary movement of the FPD 3 is eliminated. .

  Specifically, referring to FIG. 8, in the first cycle, the clockwise mode is set, the FPD 3 is moved in the order of A, B, C, and D, and the FPD 3 is rotated in the clockwise direction. Shoot at each position. When the photographing at the last position D is completed, the substrate 10 is moved so that the next inspection area is located at a position suitable for photographing while maintaining the position and posture of the FPD 3 at that time, and the first time in the second cycle. Take a photo of Thereafter, in the counterclockwise mode, the FPD 3 is moved in the order of D, C, B, and A, and the FPD 3 is also rotated counterclockwise to perform photographing at each position.

  Next, when the last imaging in the second cycle is completed at the position A, the substrate 10 is moved so that the next inspection area is located at a position suitable for imaging while maintaining the position and posture of the FPD 3 at that time. The first image is taken in the third cycle. After that, moving and rotating in the clockwise mode are performed again, and shooting is performed at each position. Thereafter, similarly, the orientation and posture of the FPD 3 of the previous cycle are maintained and the first imaging for the next inspection area is performed, and each time the inspection area changes, the movement direction and the axis rotation direction of the FPD 3 are changed. Reverse.

  The purpose of the control shown in FIG. 8 is to eliminate useless movement of the FPD 3 and to eliminate the twist of the cable 30 (shown in FIG. 1) caused by the rotation of the shaft of the FPD 3. If the FPD 3 is always moved in the same direction without performing this control, it is necessary to interrupt the processing as appropriate and perform processing such as idling the FPD 3 to eliminate the twist of the cable 30. According to the control in FIG. 8, the twist of the cable 30 can be naturally eliminated in each shooting without performing such processing.

  Next, FIG. 9 shows a control method when photographing for tomosynthesis. In tomosynthesis photography, the FPD 3 is fixed and moved so that the direction of each side is aligned with the X and Y axes without rotating the FPD 3, so that the cable 30 may be twisted. Absent. In this embodiment, therefore, the FPD 3 is always moved in a fixed direction, and the first shooting of the next cycle is performed while maintaining the position and posture of the FPD 3 at the last shooting of each cycle.

  Specifically, with reference to FIG. 9, in this embodiment, the state in which the clockwise mode is executed is fixed, and in the first cycle, the FPD 3 is moved in the order of A, B, C, and D to perform shooting. When the photographing at the position D is completed, the substrate 10 is moved so that the next inspection area is located at a position suitable for photographing while maintaining the position and posture of the FPD 3 at that time, and the first photographing in the second cycle. I do. Hereinafter, shooting is performed by moving the FPD 3 in the order of A, B, and C.

  Further, in the imaging process of the third cycle, the substrate is placed so that the next inspection area is located at a position suitable for imaging while maintaining the position and posture of the FPD 3 at the position C where the last imaging of the second cycle was performed. 10 is moved for the first shooting, and then the FPD 3 is moved in the order of D, A, and B for shooting. Thereafter, by performing the same control, useless movement of the FPD 3 can be eliminated.

  In the example of FIGS. 8 and 9, when the height of the reference plane T between the inspection areas is made uniform, when the imaging cycle for one inspection area is completed and the imaging cycle for the next inspection area is shifted to, the FPD3 The position of the FPD 3 is finely adjusted according to the end of the imaging cycle corresponding to the preceding inspection area when changing the size of the inspection area, the imaging magnification, or the like. However, in this case as well, the direction and orientation of the FPD 3 may be maintained at the final shooting state of the preceding shooting cycle.

  Hereinafter, a detailed procedure of the imaging process including the control illustrated in FIGS. 8 and 9 will be described with reference to FIGS. In each figure, i is the identification number of the inspection area of the substrate, N is the total number of inspection areas, and pn is the number of imaging. Further, j is an identification number indicating the stop position of the substrate 10 and the FPD 3 and is given in the clockwise order starting from a specific direction. For example, referring to FIGS. 8 and 9, pn = 4, j = 1 represents position A, j = 2 represents position B, j = 3 represents position C, and j = 4 represents position D. Will be expressed.

  10 and 11, the height of the reference plane T is constant, and it is not necessary to move the FPD 3 when the inspection area is switched.

  The imaging process for X-ray CT in FIG. 10 will be described with reference to the reference numerals of the respective steps in the figure. First, i and j are set to 1 (ST101), and the i-th inspection region Ri from the memory 71 is set. The position information of (first inspection area at this stage) is read (ST102).

  Next, the first inspection region and the FPD 3 are moved to the j-th stop position (the first stop position at this stage), and imaging is performed (ST103, 104). The X-ray fluoroscopic image generated by this imaging is stored in the memory 71 by the image input unit 75. Further, CPU 70 attaches the current values of i and j as additional information to this image (ST105).

  Hereinafter, while updating the value of j until the number of times of photography pn is reached (ST106, 107), the first inspection area and the FPD 3 are moved to the stop position indicated by the hourly j, and photographing and image storage processing are executed. . Although not shown in FIG. 10, in ST103, the rotation mechanism 46 is driven in accordance with the movement of the FPD 3, and the posture of the FPD 3 with respect to the first examination region and the X-ray source 3 is changed every time.

  In the loop of ST103 to ST106, the clockwise mode is executed by changing the position of the first inspection region and FPD3 while incrementing the value of j. Here, when pn times of shooting are completed (ST106 is “YES”), images stored in the memory 71 during these shootings are read and transmitted to the image processing device 8 (ST108).

  When the processing for the first inspection area is completed as described above, the value of i is updated (ST109, 110), and attention is paid to the second inspection area. Here, first, position information of the focused second inspection area is read (ST111), and then the second inspection area is moved to the j-th stop position while maintaining the position and posture of the FPD 3 (ie, The detector stage 4 is stopped and only the substrate stage 1 is moved.) The value of j at this time is pn indicating the end point of the movement path in the clockwise mode.

  When the second inspection area moves to the pnth stop position, the first imaging is executed (ST113), and the generated image is stored in the memory 71 (ST114). Also in this step, the current values of i and j are attached as additional information as in the previous ST108.

  Next, the value of j is decremented (ST116), and the second inspection area and FPD3 are moved to the stop position indicated by j after the update (ST117). When the movement is further completed, photographing (ST113) and storage of images and additional information (ST114) are executed.

  Similarly, the steps ST117, 113, and 114 are executed while the value of j is decremented until it becomes 1. Also in this case, the posture of the FPD 3 in hourly photographing is changed by rotating the FPD 3 in accordance with the movement. With this control, the counterclockwise mode is executed for the second inspection region.

  When imaging for the second inspection area is completed, the image stored in the memory 71 is transmitted to the image processing apparatus 8 (ST118). Next, attention is focused on the third inspection region by incrementing the value of i (ST119, 120). Also here, first, the position information of the inspection area under consideration is read (ST121), and the third inspection area is moved to the position indicated by the current value of j while maintaining the position and orientation of the FPD 3 (ST122). At this stage, j has an initial value of 1 due to the execution of the counterclockwise mode.

  When the third inspection region moves to the first stop position, the process jumps to ST104 in the loop of ST103 to ST106, and the loop is started from this step. As a result, the clockwise mode is executed for the third inspection region.

  Similarly, when i is an odd number, the processing is performed pn times by the clockwise mode processing (ST122, ST103 to 106), and when i is an even number, the processing is counterclockwise mode (ST112 to 117). The pn X-ray fluoroscopic images generated by these imaging are transmitted to the image processing apparatus 8. When the process for the last Nth inspection area is completed, ST109 or ST119 is “YES”, and the process is terminated.

  In the above, in the image transmission to the image processing apparatus 8 (ST108, 118), an image with additional information attached is transmitted. As a result, even if the generation order of images corresponding to each stop position differs depending on the examination region, the image processing apparatus 8 can specify the relationship between images without error and calculate the X-ray absorption rate.

  Next, the imaging processing for tomosynthesis shown in FIG. 11 will be described. First, identification numbers i and j and a variable k indicating the number of imaging are set to 1 (ST201).

  Next, focusing on the first inspection area based on the current value of i, the position information is read (ST202). Here, since the determination in ST203 is “YES”, the process proceeds to ST204, and the first inspection region and the FPD 3 are moved to the j-th stop position (first in this stage) (ST204). When the movement is completed, X-ray fluoroscopic imaging and processing for storing the generated image and additional information are executed (ST206, 207), as in the procedure of FIG.

  Thereafter, while incrementing the number of times of photographing k and j indicating the stop position (ST209, ST212), steps ST204, 206, and 207 are executed until the value of k reaches pn. When the pn-th shooting is completed, ST208 is “YES”, the process proceeds to ST213, and the accumulated image is transmitted to the image processing apparatus 8.

  When the processing for the first inspection area is completed as described above, the value of i is incremented and the value of k is returned to the initial value of 1 (ST214 to ST216). On the other hand, the value of j is j = pn because the loop of ST204 to ST212 is executed pn times for the first inspection area, but this value is maintained.

  After updating i and k, the process returns to ST202, and the position information of the inspection area Ri (second inspection area at this stage) indicated by the updated i is read. Since the next determination in ST203 is “NO”, the process proceeds to ST205, and the second inspection region is moved to the jth, that is, pnth stop position while maintaining the position and orientation of the FPD3.

  Thereafter, photographing (ST206) and image storage processing (ST207) are executed, and the value of k is further incremented (ST208, 209). Next, since the value of j at this time is pn, the determination in ST210 is “YES”, and processing for returning the value of j to the initial value of 1 is executed (ST211). Thereafter, the process proceeds to ST204, and the second inspection region and the FPD 3 are moved to the stop position indicated by j after the update, that is, the first stop position.

  Hereinafter, similarly, the loop of ST204 to 212 is executed while incrementing the values of k and j until pn times of imaging are executed. With this flow, the clockwise mode starting from the pnth stop position is executed in photographing the second inspection region.

  Similarly, in the following inspection areas, pn times of imaging are executed while the hourly inspection areas Ri and FPD3 are moved in the clockwise direction, and the images accumulated in the memory 71 are transmitted to the image processing apparatus 8 by each imaging. To do. Even in this transmission, the corresponding i and j values are attached to each image as additional information. Therefore, even if the hourly image generation order is different, the image processing apparatus 8 misrepresents the relationship between the images. Can be identified without. Therefore, even when the image processing apparatus 8 performs image shift correction in order to generate a plurality of tomographic images, it can cope with no problem.

  When imaging for tomosynthesis is performed after imaging for X-ray CT, and imaging for the final examination region of imaging for X-ray CT is performed in the clockwise mode, the FPD 3 is rotated counterclockwise. It is desirable to eliminate the twist of the cable 30 by moving and rotating the shaft. However, since this process can be executed in parallel with the process of moving the first examination area for tomosynthesis imaging to the first stop position, there is no possibility that the process will be significantly delayed.

  In the above description, it is assumed that the inspection area set on the substrate is divided into a group for performing X-ray CT imaging and a group for tomosynthesis imaging, and processing is performed for each group. Not limited to the processing content, the processing order may be determined based on the positional relationship between the inspection areas, and the imaging control corresponding to the area may be performed for each inspection area.

  Next, in each of the above embodiments, it is assumed that each inspection area is processed one by one. However, depending on the positional relationship of the inspection areas, it is also possible to execute imaging for a plurality of inspection areas in parallel. is there.

FIG. 12 is a schematic diagram showing the relative positional relationship between each inspection region and the FPD 3 with respect to two inspection regions R1 and R2 to be processed by tomosynthesis, and when imaging processing for these inspection regions R1 and R2 is performed in parallel. A specific example is shown.
In the drawing, a1 to a4 indicate the position of the FPD 3 when imaging the inspection region R1, and b1 to b4 indicate the position of the FPD 3 when imaging the inspection region R2. In addition, encircled numbers shown in the vicinity of each position indicate the order of shooting.

  In this figure, the positional relationship between the inspection areas R1, R2 and the hourly FPD 3 is shown on the assumption that the substrate 10 is stationary. However, the actual substrate 10 moves every time an image is taken, and the inspection area to be imaged Will move to a place (see FIG. 3) that meets the conditions for fluoroscopic imaging. Therefore, if the heights of the reference planes T in the inspection regions R1 and R2 are the same, a1 and b1, a2 and b2, a3 and b3, and a4 and b4 in the drawing are substantially at the same position. Correspond. Referring again to FIG. 9, the actual position corresponding to a1 and b1 is A, the actual position corresponding to a2 and b2 is B, the actual position corresponding to a3 and b3 is C, and a4 , B4, the actual position is D.

  Therefore, according to the example of FIG. 12, the FPD 3 is switched at the shooting switching timing (first to second, third to fourth, fifth to sixth, and seventh to eighth) indicated by the thick dotted line in the figure. It is only necessary to move the substrate 10 in order to change the inspection area while maintaining the position and orientation of the substrate. Therefore, the number of times of moving the FPD 3 can be further reduced.

  When the distance between the inspection areas is short and there is a common point in the imaging conditions of each inspection area, the processing for each inspection area is performed by performing parallel processing as shown in the example of FIG. 12 for these inspection areas. There is a possibility that the processing time can be shortened compared with the case where the processes are executed in order. Also in X-ray CT imaging, imaging related to a plurality of examination areas can be performed in parallel as described above. Therefore, if it is considered that there is such a possibility, a simulation based on the positional relationship of the inspection area and the set value of the number of imaging may be performed in advance to select the most efficient imaging procedure.

  Even in the case of performing parallel processing, the identification information of the corresponding examination area and stop position is associated with the image generated by the photographing every hour as additional information and stored in the memory 71. Further, since the image with the additional information attached is also transmitted to the image processing device 8, the image processing device 8 can specify the image for each inspection region even if the image generation order is not consistent due to the parallel processing. It is possible to reconstruct a tomographic image by recognizing the position of the FPD 3 when each image is generated without error.

It is a figure which shows schematic structure of the imaging | photography process part of the board | substrate inspection apparatus using X-rays. It is a block diagram of the main structures of a board | substrate inspection apparatus. It is a figure which shows the positional relationship of an X-ray source, FPD, and a board | substrate in the case of imaging | photography for tomosynthesis. It is a figure which shows the example of the change of the position of a board | substrate and FPD in the imaging process for 1 cycle. It is a figure which shows the principle of the reconstruction process of the tomographic image of tomosynthesis. It is a figure which shows the change of the relationship between X-ray source and FPD in the case of imaging | photography for tomosynthesis. It is a figure which shows the change of the relationship between X-ray source and FPD in the case of imaging | photography for X-ray CT. It is a figure explaining the control in the case of carrying out several cycles of imaging | photography for X-ray CT. It is a figure explaining the control in the case of carrying out several cycles of imaging | photography for tomosynthesis. It is a flowchart which shows the procedure of the imaging process for X-ray CT. It is a flowchart which shows the procedure of the imaging | photography process for tomosynthesis. It is a figure explaining the specific example in case the imaging process with respect to two test | inspection area | regions is performed in parallel. It is a figure which shows the method of general X-ray CT imaging.

Explanation of symbols

1 Substrate stage 2 X-ray source 3 Flat panel detector (FPD)
4 Detector stage 7 Control device 10 Substrate 17, 48 Linear movement mechanism 46 Rotation mechanism

Claims (6)

A substrate stage that supports a substrate to be inspected in a state where the substrate surface is horizontal, an X-ray source that is fixedly disposed above or below the substrate stage with the optical axis oriented vertically, and a two-dimensional X-ray detector A detector stage that supports the two-dimensional X-ray detector at a position facing the X-ray source across the substrate stage, and an X-ray tomographic image of a predetermined inspection region of the substrate by controlling each of the above components An inspection device comprising a control unit for generating
The substrate stage supports the substrate in a horizontally movable manner by linear movement mechanisms each having a drive shaft in two directions corresponding to each edge direction of the supporting substrate,
The detector stage includes a linear moving mechanism having parallel driving shafts to each drive shaft of the substrate stage, by a rotating mechanism for rotating the direction axis orthogonal to the detection surface of the two-dimensional X-ray detector, wherein Support the two-dimensional X-ray detector so that it can move horizontally and rotate,
The controller is
The position of the two-dimensional X-ray detector in each of a plurality of fluoroscopic imaging necessary for generating an X-ray tomographic image of the examination area changes on a virtual circle centered on the optical axis of the X-ray source. And the substrate so that the substrate stops with a positional relationship necessary for X-ray fluoroscopic imaging of the inspection region with respect to the two-dimensional X-ray detector and the X-ray source stopped when the two-dimensional X-ray detector is stopped. Control the operation of each linear moving mechanism of the stage and detector stage, and perform X-ray fluoroscopic imaging with an X-ray source and a two-dimensional X-ray detector according to the stop of each stage,
When generating an X-ray CT image for the inspection region, the operation of the rotation mechanism of the detector stage is controlled so that the posture of the two-dimensional X-ray detector with respect to the inspection region at the time of imaging becomes different at every imaging. On the other hand, when generating a tomosynthesis tomographic image for the examination region, the rotation mechanism is stopped in a state in which the direction of each coordinate axis of the two-dimensional X-ray detector is aligned with the direction of each drive axis of the detector stage .
A board inspection apparatus using X-rays.   When generating an X-ray CT image for the examination region, the control unit generates a virtual circle centered on the optical axis of the X-ray source while the two-dimensional X-ray detector rotates in a certain direction. Controls the operation of the detector stage so that it moves linearly in the order along the virtual circle to a plurality of positions, and temporarily stops the movement and shaft rotation at each position, and moves and stops the two-dimensional X-ray detector. The operation of the substrate stage is controlled so that the substrate moves linearly to a position corresponding to the next stop position of the two-dimensional X-ray detector and stops at the position accordingly. Board inspection equipment using X-rays.   The control unit, when sequentially performing X-ray fluoroscopy for a plurality of examination areas for generating X-ray CT images, in accordance with the end of the imaging cycle corresponding to the preceding examination area, the two-dimensional X at that time The position of the X-ray detector with respect to the X-ray source and the posture with respect to the inspection region are maintained, and the next inspection region is in a positional relationship necessary for X-ray fluoroscopy with respect to the two-dimensional X-ray detector and the X-ray source. The imaging cycle corresponding to the next inspection area is started after the substrate is moved to the position, and the movement direction and the axis rotation direction of the two-dimensional X-ray detector in this cycle are opposite to the previous cycle. The substrate inspection apparatus using X-rays according to claim 2, wherein When generating a tomosynthesis tomographic image for the examination region, the control unit maintains the state in which the two-dimensional X-ray detector matches the direction of each coordinate axis with the direction of each drive axis of the detector stage. The detector stage is controlled to move linearly to a plurality of virtual circle positions around the optical axis of the X-ray source in the order along the virtual circle, and to temporarily stop the movement at each position. In addition, the substrate moves linearly to a position corresponding to the next stop position of the two-dimensional X-ray detector according to the movement and stop of the two-dimensional X-ray detector, and stops at the position. The substrate inspection apparatus using X-rays according to claim 1, which controls the operation of the substrate stage.   When sequentially performing X-ray fluoroscopy for a plurality of examination areas for generating tomosynthesis tomographic images, the control unit performs two-dimensional X at that time according to the end of the imaging cycle corresponding to the preceding examination area. The position and orientation of the line detector are maintained, and the substrate is moved so that the next inspection area is in the positional relationship necessary for fluoroscopic imaging with respect to the two-dimensional X-ray detector and the X-ray source. 5. The imaging cycle corresponding to the next inspection area is started, and the moving direction of the two-dimensional X-ray detector is maintained constant until all imaging cycles corresponding to the plurality of inspection areas are completed. The described X-ray-based board inspection apparatus.   The controller is configured to register a sequence of operation control of each stage so that a plurality of X-ray fluoroscopic imaging related to generation of X-ray tomographic images of a plurality of examination regions are executed in a predetermined order; Each stage, X-ray source, and two-dimensional image storage means for storing a fluoroscopic image, and X-ray fluoroscopic imaging for the plurality of examination regions are executed based on a sequence registered in the registration means An imaging control means for controlling the operation of the X-ray detector, and an X-ray fluoroscopic image generated by the imaging every hour, together with information for identifying a corresponding inspection region and a stop position of the two-dimensional X-ray detector at the time of imaging The substrate inspection apparatus using X-rays according to claim 1, further comprising an image storage unit that accumulates in the image storage unit.

Images