Inspection system, inspection information processing terminal and program

Abstract

To provide an art that enables a user to easily check a state of a part of an examination object as to a substrate where an electronic component having a solder bonding-purpose metal bump formed on a package bottom surface is mounted.SOLUTION: An examination system for a substrate where an electronic component having a solder bonding-purpose metal bump with a mounting substrate of the electronic component formed on a mounting bottom surface is mounted has: three-dimensional date creation means that creates three-dimensional data on the substrate using information on a plurality of X-ray images taken by X-ray imaging means; review-purpose image creation means that creates a review-purpose image showing a shape of a solder of a solder bonding part as a second-dimensional shape of a review surface of user desire, using the three-dimensional data; and display means that displays the image created by the review-purpose image creation means.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inspection system, an inspection information processing terminal, and a program, and more particularly to a technique for checking the soldering condition based on three-dimensional data acquired using an X-ray CT. [Background technology]

[0002] In recent years, various products have become smaller and more precise, and for example, the density of components mounted on component-mounted boards has increased, resulting in an increase in the number of parts that are shaded in the imaging field of a visual inspection device, and therefore an increase in the number of parts that cannot be accurately inspected by visual inspection. In response to this, a technology has become publicly known that uses X-ray CT inspection to inspect parts that cannot be inspected by visual inspection (for example, Patent Document 1).

[0003] Furthermore, Patent Document 2 discloses that when an inspection is performed using three-dimensional information, the user can check the condition of the area being inspected (an area that cannot be seen from the outside). Specifically, it discloses creating a profile image based on three-dimensional shape data, showing relative values ​​of physical quantities related to the shape of the area being inspected as viewed from a user-selected observation direction, and displaying this on a screen. With this technology, even for an area being inspected that cannot be seen from the outside, the user can easily check by referring to the screen what the specific condition of the area is and whether the pass / fail judgment result is appropriate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-223468 [Patent Document 2] Japanese Patent Publication No. 2021-135153 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, some electronic components used in component mounting boards, such as ball grid arrays (BGAs), have metal bumps for soldering formed on the bottom surface of the package. For such electronic components, even if the technology described in Patent Document 2 is used, it is not possible to create an appropriate user confirmation image of the solder joint between the component and the board. Figure 17 shows the correspondence between the user confirmation image created by such a conventional technology and the state of the BGA solder joint. As shown in Figure 17, the profile shape of the solder joint created by the technology described in Patent Document 2 has problems such as difficulty in matching the actual shape of the solder wetting and inability to confirm the difference between the profile shapes of good and bad products.

[0006] The present invention has been made in consideration of the above-described circumstances, and aims to provide a technology that allows a user to easily check the condition of an inspection target area on a board on which an electronic component having metal bumps for solder bonding formed on the bottom surface of the package is mounted. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs the following configuration: An inspection system for a component mounting board on which electronic components are surface-mounted, comprising: the electronic component has metal bumps formed on the bottom surface of the package for soldering to the component mounting substrate, X-ray generating means for irradiating the component mounting board with X-rays; an X-ray imaging means for capturing an image of X-rays transmitted through the component mounting board; a three-dimensional data creation means for creating three-dimensional data of an area including at least a solder joint between the component mounting board and the electronic component, using information on a plurality of X-ray images taken by the X-ray photography means; a confirmation image creation means for creating a confirmation image that shows the shape of the solder at the solder joint as a two-dimensional shape of an observation surface desired by a user, using the three-dimensional data; and a display means for displaying a screen including the confirmation image created by the user confirmation image creation means.

[0008] The above-mentioned inspection system may be configured as an inspection device in which each means is integrated. The "user-desired observation surface" may be, for example, the side surface (surface viewed from the side) of the joint between the electronic component and the component mounting board. However, the target surface is not limited to a surface visible from the outside, but also includes a cross section at any position (and direction) in a shape defined by three-dimensional data.

[0009] With this configuration, even in the case of a component mounting board on which components such as BGAs, which have metal bumps formed on the bottom surface of the package, are mounted, the solder shape of the inspection target area that the user wants to check can be displayed as the two-dimensional shape of the observation surface that the user wants to check.

[0010] The confirmation image creation means further comprises: a reference plane specifying means for specifying, in the three-dimensional data, a component-side reference plane which is a horizontal tomographic position serving as a reference on the electronic component side in the solder joint, and a board-side reference plane which is a horizontal tomographic position serving as a reference on the component-mounting board side; a horizontal tomographic solder area calculation means for calculating the area and center of gravity of the solder of each horizontal tomographic solder layer constituting the three-dimensional data between the component-side reference surface and the board-side reference surface; a first profile image creation means for creating a first profile image showing a contour shape of the solder on the observation surface based on the calculated area and center of gravity position of the solder on each of the horizontal cross sections, The verification image may include the first profile image.

[0011] The component-side reference plane and the board-side reference plane may be determined based on the horizontal cross-sectional position that is the center plane of the solder ball. This configuration allows the user to easily check the outline shape of the solder at the inspection target location on the desired observation plane.

[0012] The inspection system further includes a first non-defective product standard calculation means for calculating a first non-defective product standard relating to an area of ​​each horizontal cross section of the solder based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component mounting board that is a non-defective product, The first profile image creating means may create the first profile image that indicates the outline shape of the solder and the non-defective product standard.

[0013] Here, "one or more of the solder joints" may be one land (soldered portion on one) on one component mounting board, or a group including multiple lands. In the case of multiple lands, it is desirable to group lands for which the same measurement conditions (inspection standards) are set. Furthermore, the mounting board used as a non-defective product may be multiple or just one. With this configuration, the user can easily confirm whether the outline shape of the solder at the inspection target location meets the non-defective product standards (i.e., if inspection results are available, whether the results are valid).

[0014] Further, the first conforming product standard calculation means calculates a first upper limit approximation curve indicating an upper limit of the area of ​​each horizontal layer of the solder as a conforming product and a first lower limit approximation curve indicating a lower limit of the area of ​​each horizontal layer of the solder, based on the one or more conforming product three-dimensional data; The first profile image creation means may create the first profile image that shows at least one of a first upper limit profile created based on the first upper limit approximation curve and a first lower limit profile created based on the first lower limit approximation curve superimposed on the outline shape of the solder.

[0015] With this configuration, the user can easily check the difference between good and bad parts of the inspection target area, and can clearly check the relationship between the outline shape of the solder and the upper and lower thresholds of the inspection standard.

[0016] The inspection system further includes a storage means for storing inspection standards relating to quality determination of the solder joints on the component mounting board; a first inspection standard initial value calculation means for calculating, based on the one or more non-defective product three-dimensional data, a first upper limit side coincidence rate, which is a coincidence rate between an approximation curve based on an average value of the area of ​​each horizontal cross section of the solder of the non-defective product and the first upper limit approximation curve, and a first lower limit side coincidence rate, which is a coincidence rate between the approximation curve based on an average value of the area of ​​each horizontal cross section of the solder of the non-defective product and the first upper limit approximation curve; The apparatus may further comprise a first inspection standard setting means for setting the first upper limit side coincidence rate and the first lower limit side coincidence rate as at least a part of the inspection standard.

[0017] According to this configuration, the initial values ​​of the inspection criteria are automatically set in the system, so that even a user who is unfamiliar with setting inspection criteria can operate the inspection system.

[0018] Furthermore, the non-defective product standard calculation means calculates the first non-defective product standard for the electronic component side and the component mounting board side, with a predetermined position between the component-side reference surface and the board-side reference surface of the solder joint as a boundary, The first profile image creation means may create the first profile image that indicates the first conforming standard on the electronic component side for the contour shape of the solder joint on the electronic component side, and that indicates the first conforming standard on the component mounting board side for the contour shape of the solder joint on the component mounting board side.

[0019] In the case of electronic components such as BGAs that have metal bumps for soldering formed on the bottom surface of the package, even good products have different trends in the measurement values ​​(area of ​​horizontal sections, major axis) between the board side and the component side, separated by the ball center plane. Therefore, with the above-mentioned configuration, the accuracy of the good product standards for both the board side and the component side can be increased, allowing the user to easily confirm the relationship between the accurate good product standards and the outline shape of the solder at the inspection target location.

[0020] The confirmation image creation means further comprises: a reference plane specifying means for specifying, in the three-dimensional data, a component-side reference plane which is a horizontal tomographic position serving as a reference on the electronic component side in the solder joint, and a board-side reference plane which is a horizontal tomographic position serving as a reference on the component-mounting board side; a horizontal tomographic solder long diameter calculation means for calculating the long diameter and center of gravity of the solder of each horizontal tomographic solder layer constituting the three-dimensional data between the component-side reference surface and the board-side reference surface; a second profile image creating means for creating a second profile image showing a contour shape of the solder on the observation surface based on the half-value of the major axis of the solder of each horizontal cross section and the position of the center of gravity, The confirmation image may include the second profile image.

[0021] In electronic components such as BGAs that have metal bumps for soldering formed on the bottom surface of the package, if a defect occurs in which the joint between the solder on the component side and the solder on the board side shifts sideways (a so-called "pillow defect"), the method that uses the area and center of gravity of the solder in a horizontal tomographic image cannot accurately show the outline shape of the solder on the observation surface desired by the user. In this regard, with the above-mentioned configuration, the user can easily confirm the outline shape of the solder at the inspection target area, even in defective products such as pillow defects.

[0022] The inspection system further includes a second non-defective product standard calculation means for calculating a second non-defective product standard relating to a major axis of each horizontal cross section of the solder based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component-mounted board that is a non-defective product, The second profile image creating means may create the second profile image showing the outline shape of the solder and the second non-defective product standard.

[0023] Further, the second conforming product standard calculation means calculates a second upper limit approximation curve indicating an upper limit of a major axis of each horizontal layer of the solder as a conforming product and a second lower limit approximation curve indicating a lower limit of the major axis of each horizontal layer of the solder, based on the one or more conforming product three-dimensional data; The second profile image creation means may create the second profile image that shows at least one of a second upper limit profile created based on the second upper limit approximation curve and a second lower limit profile created based on the second lower limit approximation curve superimposed on the outline shape of the solder.

[0024] The inspection system further comprises: a storage means for storing inspection standards relating to quality determination of the solder joints on the component mounting board; a second inspection standard initial value calculation means for calculating, based on the one or more non-defective product three-dimensional data, a second upper limit side coincidence rate, which is a coincidence rate between an approximation curve based on the average values ​​of the major axes in each horizontal tomography of the solder of the non-defective product, and the second upper limit side coincidence rate, and a second lower limit side coincidence rate, which is a coincidence rate between the approximation curve based on the average values ​​of the major axes in each horizontal tomography of the solder of the non-defective product, and the second upper limit side coincidence rate. The system may further comprise a second inspection standard setting means for setting the second upper limit side coincidence rate and the second lower limit side coincidence rate as at least a part of the inspection standard.

[0025] Furthermore, the second conforming product standard calculation means calculates the second conforming product standard for each of the electronic component side and the component mounting board side, with a predetermined position between the component-side reference surface and the board-side reference surface of the solder joint as a boundary, The profile image creation means may create the second profile image, which indicates the second conforming standard on the electronic component side for the contour shape of the solder joint on the electronic component side, and which indicates the second conforming standard on the component mounting board side for the contour shape of the solder joint on the component mounting board side.

[0026] The inspection system also includes a horizontal tomographic solder roundness calculation means for calculating the roundness of the solder of each horizontal tomographic plane that constitutes the three-dimensional data between the component-side reference plane and the board-side reference plane; The apparatus may further include a third profile image creation means for creating a third profile image that displays a circularity profile in which the circularity is plotted in a two-dimensional graph area with each horizontal cross-sectional position as one axis and the circularity as the other axis.

[0027] The inspection system also includes a third non-defective product standard calculation means for calculating a third upper limit approximation curve indicating an upper limit of the circularity of the solder as a non-defective product and a third lower limit approximation curve indicating a lower limit, based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component mounting board as a non-defective product. a storage means for storing an inspection standard for determining whether the solder joints on the component mounting board are good or bad; a third inspection standard initial value calculation means for calculating a third upper limit side coincidence rate, which is a coincidence rate between an approximation curve of the average circularity calculated from the average values ​​of the area and major axis in each horizontal cross section of the solder of the non-defective product and the third upper limit approximation curve, and a third lower limit side coincidence rate, which is a coincidence rate between the approximation curve of the average circularity calculated from the average values ​​of the area and major axis in each horizontal cross section of the solder of the non-defective product, and the third upper limit approximation curve, based on the one or more non-defective product three-dimensional data; The system may further comprise a third inspection standard setting means for setting the third upper limit side coincidence rate and the third lower limit side coincidence rate as at least a part of the inspection standard.

[0028] Due to the shape characteristics of pillow defects, roundness is generally used as a pass / fail judgment criterion. Therefore, by using the above configuration, the user can easily confirm realistic inspection criteria corresponding to pillow defects and the profile of the inspection target area according to the inspection criteria (a profile showing the roundness in each horizontal plane). In other words, it becomes easier to confirm the validity of the pass / fail judgment results in the case of pillow defects. Note that the third upper limit approximation curve may be determined based on the first and second upper limit approximation curves, and the third lower limit approximation curve may be determined based on the first and second upper limit approximation curves.

[0029] The confirmation image creating means may further comprise a vertical projection image creating means for performing a binarization process on each horizontal tomographic image between the component-side reference plane and the board-side reference plane of the three-dimensional data, and creating a vertical projection image by projecting the binarized result in the depth direction of the observation plane desired by the user, and the confirmation image may include the vertical projection image creating means. With this configuration, the user can check the solder shape of the inspection target area as viewed from the user-desired observation direction in the binarized image.

[0030] The inspection system further includes an inspection standard acquisition means for acquiring an inspection standard related to quality determination of the solder joints on the component mounting board, The confirmation image creation means may be configured to highlight and display, in the case where there is a portion of the two-dimensional shape that is determined to be defective in light of the inspection standard, the portion that is determined to be defective.

[0031] With this configuration, if the shape of the inspection target portion does not satisfy the inspection standard, the user can easily and clearly identify the portion that does not satisfy the inspection standard.

[0032] The confirmation image creation means may create a first confirmation image showing the shape of the solder of the entire solder joint, a second confirmation image showing only the shape of the solder on the electronic component side, a third confirmation image showing only the shape of the solder on the component mounting board side of the solder joint, and a fourth confirmation image showing both the second confirmation image and the third confirmation image simultaneously, and the display means may display a screen including any of the first to fourth confirmation images. The electronic component side and the component mounting board side here may be defined, for example, as a predetermined boundary between the component-side reference surface and the board-side reference surface. This configuration allows separate confirmation images to be created for the component side and the board side of the solder joint, allowing the user to display only the desired portion.

[0033] The present invention can also be understood as an inspection information processing terminal that includes the three-dimensional data creation means and the confirmation image creation means and that constitutes at least a part of the inspection system.

[0034] The present invention also provides a program for making a computer function as the above-mentioned inspection information processing terminal. The program can also be regarded as a computer-readable recording medium on which such a program is non-transitoryly recorded.

[0035] The present invention can be achieved by combining the above-described configurations and processes as long as no technical contradiction occurs. [Effects of the Invention]

[0036] According to the present invention, a technology can be provided that allows a user to easily check the condition of an inspection target area on a board on which an electronic component having metal bumps for solder bonding formed on the bottom surface of the package is mounted. [Brief explanation of the drawings]

[0037] [Figure 1]FIG. 1 is a schematic diagram showing a schematic configuration of an X-ray inspection apparatus according to an application example of the present invention. [Figure 2] FIG. 2 is a flowchart showing the flow of confirmation image display processing in the X-ray inspection apparatus according to an application example of the present invention. [Figure 3] FIG. 3 is a block diagram showing a schematic configuration of the X-ray inspection system according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating a solder joint to be inspected in the first embodiment. [Figure 5] Fig. 5A is a first diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 1. Fig. 5B is a second diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 1. Fig. 5C is a third diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 1. [Figure 6] FIG. 6 is a flowchart showing the flow of confirmation image display processing in the X-ray inspection system according to the first embodiment. [Figure 7] FIG. 7 is a block diagram showing a schematic configuration of an X-ray inspection system according to the second embodiment. [Figure 8] FIG. 8 is a diagram illustrating a process for calculating a non-defective product standard based on three-dimensional shape data of a non-defective product in the second embodiment. [Figure 9] Fig. 9A is a first diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 2. Fig. 9B is a second diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 2. [Figure 10] Fig. 10A is a diagram showing another example of processing for calculating a non-defective product standard based on three-dimensional shape data of a non-defective product in embodiment 2. Fig. 10B is a third diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 2. Fig. 10C is a fourth diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 2. [Figure 11]FIG. 11 is a flowchart showing a part of the flow of processing performed in the X-ray inspection system according to the second embodiment. [Figure 12] FIG. 12 is a flowchart showing the flow of confirmation image display processing in the X-ray inspection system according to the second embodiment. [Figure 13] FIG. 13 is a block diagram showing a schematic configuration of an X-ray inspection system according to the third embodiment. [Figure 14] FIG. 14 is a flowchart showing a part of the flow of processing performed in the X-ray inspection system according to the third embodiment. [Figure 15] FIG. 15 is a block diagram showing a schematic configuration of an X-ray inspection system according to the fourth embodiment. [Figure 16] Fig. 16A is a diagram illustrating a solder joint to be inspected in embodiment 4. Fig. 16B is a diagram showing an example of a confirmation image displayed in the X-ray inspection system according to embodiment 4. [Figure 17] FIG. 17 is an explanatory diagram showing the correspondence between the state of the solder joints of the component targeted by the present invention and the confirmation image according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0038] <Application example> (Configuration of application examples) An example of an embodiment of the present invention will be described below. The present invention can be applied, for example, to an X-ray inspection apparatus for X-ray-imaging a component-mounted board on which electronic components, such as BGA packages, are mounted, with metal bumps for solder bonding formed on the bottom surface thereof, and inspecting the component-mounted board based on the captured image. FIG. 1 is a schematic diagram showing the overall configuration of an X-ray inspection apparatus 9 according to this application example. The X-ray inspection apparatus 9 generally includes a control terminal 91 and an imaging unit 94 having an X-ray source 92 and an X-ray camera 93. In the following description of the embodiment, when using a coordinate system, the vertical direction is defined as the Z-axis, the horizontal direction indicating the depth is defined as the Y-axis, and the horizontal direction perpendicular to the Y-axis is defined as the X-axis. In the following description, the Z-axis is defined as having a positive downward direction, the Y-axis is defined as having a positive forward direction, and the X-axis is defined as having a positive rightward direction (a so-called image coordinate system).

[0039] The control terminal 91 can be configured, for example, by a general-purpose computer, and has the following functional units: a drive control unit 911, a memory unit 912, a three-dimensional data creation unit 913, an inspection unit 914, an image creation unit 915, and a display unit 916.

[0040] X-ray source 92 irradiates X-rays onto component-mounted board O being transported by transport rollers (not shown), and X-ray camera 93 photographs the X-rays that have passed through component-mounted board O. X-ray source 92 is movable by X-stage 921 and Y-stage 922, and X-ray camera 93 is movable by X-stage 931 and Y-stage 932. X-ray source 92 and X-ray camera 93 are moved on circular orbits C1 and C2 by these stages, respectively, and photographs are taken at multiple positions on the orbits.

[0041] The drive control unit 911 controls the drive of each unit constituting the X-ray inspection apparatus 9. As a result, the X-ray inspection apparatus 9 changes the relative positions of the component mounting board O, the X-ray source 92, and the X-ray camera 93, and captures images of the component mounting board O from a plurality of imaging positions.

[0042] The storage unit 912 stores at least information related to the component mounting board O (for example, the type, shape, and dimensions of the components to be mounted) and information related to inspection standards such as thresholds. It may also store a program for controlling the inspection device, data for creating an image for user confirmation (described later), and the like.

[0043] The three-dimensional data creation unit 913 creates three-dimensional data of the component mounting board O (or a portion thereof that is an inspection target area) from the multiple X-ray images captured as described above. Since publicly known techniques such as CT (Computed Tomography) and tomosynthesis can be applied to the method of creating (constructing) this data, detailed explanations will be omitted. Furthermore, the inspection unit 914 performs an inspection to determine whether the component mounting board O is good or bad by comparing the created three-dimensional data with inspection standards stored in the storage unit 912.

[0044] The image creation unit 915 creates a user confirmation image that shows the shape of the inspection target portion on the component mounting board O as a two-dimensional shape when observed from a predetermined direction (for example, a direction in which the XZ plane of the component mounting board is the front) using the three-dimensional data created by the three-dimensional data creation unit 913. The display unit 916 is configured to include a display device such as a liquid crystal display, and displays the user confirmation image created by the image creation unit 915.

[0045] (Processing flow) The procedure of the above processing performed by the X-ray inspection device 9 in this application example is shown in Fig. 2. First, the X-ray inspection device 9 takes X-ray images of the component mounting board O from multiple different positions and acquires multiple X-ray image data (S901). Next, the X-ray inspection device 9 creates three-dimensional data of the component mounting board O from the multiple X-ray image data acquired in step S901 (S902).

[0046] The X-ray inspection device 9 then inspects the component mounting board O based on the three-dimensional data created in step S902 (S903). Specifically, for example, the quality of the component mounting board O is determined by comparing the three-dimensional data with an inspection standard (threshold value) related to the shape of the component mounting board O that is stored in advance in the storage unit 912. The determination result may also be displayed on the display unit 916.

[0047] X-ray inspection device 9 further uses the three-dimensional data created in step S902 to perform preprocessing for creating an image for user confirmation (described later) (S904). Specifically, for example, from the three-dimensional data, a component-side reference plane, which is a horizontal tomographic position serving as a reference on the component side of the target image creation area, and a board-side reference plane, which is a horizontal tomographic position serving as a reference on the board side, are identified. Then, the area and center of gravity of the solder for each horizontal tomographic position between the component-side reference plane and the board-side reference plane are calculated.

[0048] Then, based on the processing of step S904, the X-ray inspection device 9 creates a user confirmation image showing the solder shape of the desired inspection target portion on the component mounting board O as a two-dimensional shape when observed from a direction desired by the user (S905). Specifically, for example, a profile image showing the outline shape of the solder when viewed from the observation direction desired by the user of the target portion is created.

[0049] Then, X-ray inspection apparatus 9 displays the image created in step S905 on display unit 916 (step S906), and ends the series of processes. Note that the display on display unit 916 may automatically display an image of a predetermined inspection target location, or may wait for an instruction input from the user and then display an image in accordance with the instruction. Also, an image for user confirmation may be displayed together with the inspection result of step S903.

[0050] With the X-ray inspection device 9 according to this application example, the user can easily check the condition of the inspection target area on a board mounted with electronic components, such as BGAs, that have metal bumps for solder bonding formed on the bottom surface of the package. This makes it easy to determine whether the inspection results are good or bad, set and correct inspection standards, and so on, using the X-ray inspection device.

[0051] <Embodiment 1> Next, more detailed examples of embodiments of the present invention will be described with reference to Figures 3 to 6. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the components described in these embodiments are not intended to limit the scope of the present invention to those alone.

[0052] (System Configuration) 3 is a schematic block diagram showing the functional configuration of an X-ray inspection system 1 according to this embodiment. The X-ray inspection system 1 according to this embodiment includes an X-ray imaging device 11, an inspection terminal 12, and a data server 13, and is an inspection system used to inspect component mounting boards in which metal bumps for soldering are formed on the bottom surface of packages such as BGA. The X-ray imaging device 11, the inspection terminal 12, and the data server 13 are connected to each other so as to be able to communicate with each other via communication means (not shown).

[0053] The X-ray imaging device 11 includes an X-ray source 111, an X-ray camera 112, a stage 113 that holds the substrate, and a control unit (not shown) that controls these components, and these components move relatively to each other to capture X-ray images of the substrate at different positions (and orientations). Since any known technology can be used for the X-ray imaging device 11, detailed descriptions of the X-ray source 111, X-ray camera 112, stage 113, etc. will be omitted.

[0054] Although not shown, the inspection terminal 12 can be a general-purpose computer equipped with a processor such as a CPU or DSP, a storage means, an input means such as a keyboard or a mouse, and an output means such as a liquid crystal display. The inspection terminal 12 may be configured as a single computer or may be configured as multiple computers that cooperate with each other.

[0055] The storage means includes, for example, a main storage unit such as a read-only memory (ROM) or a random access memory (RAM), and an auxiliary storage unit such as an EPROM, a hard disk drive (HDD), or a removable medium. The auxiliary storage unit of the storage means stores an operating system (OS), various programs, etc., and the programs are loaded into the working area of ​​the main storage unit and executed. The inspection terminal 12 is controlled through the execution of the programs, thereby realizing functional units that fulfill predetermined purposes, as described below. Some or all of the functional units may be realized by hardware circuits such as ASICs or FPGAs.

[0056] The data server 13 stores imaging conditions for the X-ray imaging device 11 (according to the inspection contents), information on the inspection target board (for example, the type, shape, and dimensions of the components), information on inspection conditions such as inspection items and thresholds, and is also provided with an area for storing saved data generated in the inspection terminal 12 as described below. Note that a program for controlling the inspection terminal 12 may be stored in the data server 13.

[0057] (Functional parts of the testing terminal) Next, we will explain each functional unit provided in the inspection terminal 12. The inspection terminal 12 has, as functional units related to input and output, an input unit 121 including input means such as a keyboard and a mouse, and an output unit 122 including output means such as a liquid crystal display. The inspection terminal 12 also has a three-dimensional data creation unit 123, an inspection unit 124, and a confirmation image creation unit 125.

[0058] The three-dimensional data creation unit 123 creates data of the three-dimensional shape of the inspection target portion (hereinafter simply referred to as three-dimensional data) based on a plurality of X-ray images of the inspection target substrate acquired from the X-ray imaging device 11. Note that the X-ray image data may be acquired directly from the X-ray imaging device 11, or may be acquired by first transmitting the data from the X-ray imaging device 11 to the data server 13 and then saving the data in the data server 13.

[0059] The inspection unit 124 acquires inspection information including the inspection standard from the data server 13, and performs an inspection to determine whether the inspection target substrate is good or bad by comparing the created three-dimensional data with the inspection standard.

[0060] (About the confirmation image creation section) The confirmation image creation unit 125 creates a confirmation image that shows the solder shape of the inspection target portion of the inspection target as a two-dimensional shape when observed from a direction desired by the user, using the three-dimensional data created by the three-dimensional data creation unit 123. In order to create this image, the confirmation image creation unit 125 further includes functional units, such as a reference plane identification unit 1251, an area centroid position calculation unit 1252, a contour shape image creation unit 1253, and a vertical projection image creation unit 1254.

[0061] The reference plane identifying unit 1251 identifies a component-side reference plane, which is a horizontal tomographic position that serves as a reference on the component side of the solder joint (hereinafter also referred to as land), and a board-side reference plane, which is a horizontal tomographic position that serves as a reference on the board side, in the above-mentioned three-dimensional data. Specifically, it first searches for a horizontal tomographic position that is the (solder) ball center plane in the three-dimensional data. The ball center plane can be, for example, the horizontal tomographic position where the brightness variation (brightness variance) is greatest in the horizontal tomographic image of the land at the inspection target location. Figure 4 shows the correspondence relationship between the ball center plane, component-side reference plane, and board-side reference plane in the solder joint to be inspected.

[0062] Next, scanning is performed in the +Z direction of the 3D shape data from the horizontal cross section position that is the identified ball center plane to search for the horizontal cross section position that is the board bonding surface. Specifically, for example, the wiring pattern in a specified area on the board is detected (using specified feature quantities, etc.), and the horizontal cross section position where the wiring pattern is most frequently detected is determined to be the board bonding surface. Then, the horizontal cross section position that is offset a specified amount in the -Z direction from the identified board bonding surface is identified as the board-side reference surface (the solder bonding surface on the board side). The offset value can be set in advance based on board design information such as pad thickness.

[0063] Furthermore, from the horizontal fault position that is the ball center plane, a horizontal fault position that is the component bonding surface in the -Z direction is searched for. This search can be performed in the same way as for the board bonding surface described above. Then, a horizontal fault position that is offset a predetermined amount in the +Z direction from the searched component bonding surface is identified as the component-side reference surface (solder bonding surface on the component side).

[0064] The area centroid position calculation unit 1252 performs binarization processing on each horizontal tomographic image in the range between the board-side reference plane and the component-side reference plane in the three-dimensional data, and calculates the area and centroid position of the solder in each horizontal tomographic image. In the following, unless otherwise specified, "each horizontal tomographic image" refers to each horizontal tomographic image in the range between the board-side reference plane and the component-side reference plane. The binarization method can be any known technique, such as discriminant analysis.

[0065] The contour shape image creation unit 1253 creates a contour shape (profile) image showing the contour shape of the solder in the observation plane desired by the user based on the calculated solder area and center of gravity position of each horizontal cross section. Here, the created contour shape image can be displayed in two parts: a component side contour shape image showing only the solder portion from the ball center plane to the component side reference plane, and a board side contour shape image showing only the solder portion from the ball center plane to the board side reference plane.

[0066] The vertical projection image creation unit 1254 creates a vertical projection image by projecting the binarized image of each horizontal slice in the depth direction of the observation plane as desired by the user. The projection method can be, for example, maximum intensity projection (projecting the brightest pixel). The created vertical projection image can be split into a component-side vertical projection image that shows only the solder portion from the ball center plane to the component-side reference plane, and a board-side vertical projection image that shows only the solder portion from the ball center plane to the board-side reference plane.

[0067] Figures 5A to 5C show examples of a contour shape image and a vertical projection image. The left side shows a vertical projection image, and the right side shows a contour shape image. Figure 5A shows an example of a contour shape image and a vertical projection image showing the two-dimensional shape of the solder in the entire range between the board-side reference surface and the component-side reference surface in one solder joint. The horizontal axis of the contour shape image indicates the ratio (%) of the radius (=√(area / π)) calculated from the area relative to the land radius. The left and right plot positions are determined based on the center of gravity position, and plotting these on each horizontal plane (vertical axis) results in a line indicating the contour. Figure 5B shows an example of a component-side contour shape image and a component-side vertical projection image, and Figure 5C shows an example of a board-side contour shape image and a board-side vertical projection image.

[0068] The confirmation image creation unit 125 creates a confirmation image including these contour shape images and vertical projection images. Then, when a command to display a confirmation image is given by the user via input unit 121, the confirmation image is displayed on a liquid crystal display serving as output unit 122.

[0069] (Confirmation image display process flow) Next, a process flow from capturing an X-ray image of a substrate to be inspected to displaying a confirmation image in this embodiment will be described with reference to Fig. 6. First, an X-ray image of the substrate is captured by the X-ray imaging device 11 (S101). Then, the three-dimensional data creation unit 123 creates three-dimensional data of the substrate (or the area to be inspected) from multiple X-ray images (S102).

[0070] Next, the user sets the lands for which a confirmation image is to be displayed among the solder joints of the components on the board via the input unit 121 (S103). The number of lands to be set is not limited to one, and multiple lands can also be set. Then, the confirmation image creation unit 125 executes the process of loop L1, which will be described below, for all the lands that have been set.

[0071] In loop L1, the reference plane identification unit 1251 first identifies the ball center plane from the three-dimensional data created in step S102 (S104), and then identifies the board-side reference plane and the component-side reference plane (S105, S106). Note that the order of steps S105 and S106 may be reversed. Then, the area and center of gravity calculation unit 1252 performs the next loop L2 process on each horizontal tomographic image within the range between the board-side reference plane and the component-side reference plane. Specifically, it performs binarization processing on each horizontal tomographic image within the range, and calculates the area and center of gravity of the solder on each horizontal tomographic image (S107). Once the area and center of gravity of the solder on all horizontal tomographic images have been calculated, loop L2 ends, and the confirmation image creation unit 125 creates a confirmation image based on the information calculated in loop L2 (S108). Then, when the processes from step S104 to step S108 are performed for all the set lands, loop L1 ends. It is recommended that information on the created confirmation image be stored in the data server 13 by the confirmation image creation unit 125. Details of the processes from step S104 to step S108 have already been explained in the explanation of the above functional units, so they will be omitted here.

[0072] After the processing of the above loop L1 is completed, the user may select any land from the lands set in step S103 via the input unit 121 at any timing (S109). The output unit 122 then executes a process to display the confirmation image created in loop L1 for the selected land on a display device such as an LCD display (S110), and then ends this routine for the time being.

[0073] The X-ray inspection system 1 described above makes it possible to visually recognize, as two-dimensional information, the approximate contour shape of an inspection target portion of a board mounted with electronic components, such as BGAs, each having metal bumps for soldering formed on the bottom surface of the package, as viewed from a desired direction. This makes it easy to determine the validity of the inspection results in the X-ray inspection of component-mounted boards. Furthermore, it becomes possible to set inspection standards based on this.

[0074] <Embodiment 2> (System Overview) Next, an X-ray inspection system 2 according to another embodiment of the present invention will be described with reference to Fig. 7 to Fig. 12. The X-ray inspection system 2 according to this embodiment has many components in common with the above-described X-ray inspection system 1, and therefore similar components and functions are denoted by the same reference numerals and detailed description thereof will be omitted.

[0075] 7 is a schematic block diagram showing the functional configuration of the X-ray inspection system 2 according to this embodiment. As shown in FIG. 7, the X-ray inspection system 2 according to this embodiment includes a functional unit of the inspection terminal 22 and Apart from being provided with a non-defective product standard calculation unit 221, the X-ray inspection system 2 has the same configuration as the X-ray inspection system 1. Furthermore, the images created by the contour shape image creation unit 222 and the vertical projection image creation unit 223 in the X-ray inspection system 2 are different from those in the X-ray inspection system 1.

[0076] (Calculation of quality standards) The acceptable product criteria calculation unit 221 calculates acceptable product criteria for the solder at the inspection target location from three-dimensional data of the acceptable product created based on an X-ray image of the acceptable component mounting board. Specific processing for calculating the acceptable product criteria will be described below with reference to Fig. 8. Fig. 8 is a diagram illustrating the processing for calculating the acceptable product criteria based on three-dimensional shape data of the acceptable product.

[0077] The non-defective product standard calculation unit 221 first performs a process to calculate the solder area of ​​each horizontal fault in the range between the board-side reference surface and the component-side reference surface for each land for one or more lands (e.g., 15 lands) in the non-defective product three-dimensional data. That is, the process from step S101 to step S107 described above is performed for (one or more lands of) a non-defective component-mounted board. Then, the calculated area of ​​each fault for each land is plotted at the corresponding fault position (see the graph area in the center of Figure 8). Furthermore, the average value and standard deviation of the plotted areas are calculated for each fault, and two approximation curves showing the relationship between the fault position and the area are calculated (see the graph area on the right side of Figure 8).

[0078] The two approximate curves are, for example, S=A×Z 2 The curves are calculated using the function +B×Z+C, with one being an upper limit approximation curve indicating the upper limit criteria for a non-defective product, and the other being a lower limit approximation curve indicating the lower limit criteria for a non-defective product. Here, S is the value on the horizontal axis of the graph, and Z is the value on the vertical axis. The upper limit approximation curve can be calculated by taking the area value of one or more lands in each horizontal fault (i.e., S) as the "average area value + n × standard deviation," and the lower limit approximation curve can be calculated by taking the area value of one or more lands in each horizontal fault (i.e., S) as the "average area value - n × standard deviation." n is a value that adjusts the range of variation and can be set to any value, for example, n = 3.

[0079] Then, the quality standard calculation unit 221 calculates the upper and lower limit areas at each cross-sectional position that are determined to be quality-qualifying based on the calculated upper limit approximation curve and lower limit approximation curve. The upper and lower limit areas correspond to the quality standard.

[0080] In the above, it is desirable to group one or more lands selected when calculating the pass criteria by setting the same measurement conditions. Electronic components with metal bumps for soldering on the bottom of their packages, such as BGAs, are typically mounted with multiple metal bumps arranged in a grid pattern, which tends to result in larger components. This makes them susceptible to changes in the X-ray irradiation angle depending on the viewing position. Even within the same component, the appearance of the soldered state of the metal bumps often differs depending on the viewing position. In such cases, it is common to set different measurement conditions for each land. By aggregating land groups with the same measurement conditions, the accuracy of the approximate curve calculation described above can be improved.

[0081] Furthermore, large components such as BGAs are susceptible to board warpage, so even within the same component, the fault position that serves as the board-side reference plane may differ depending on the field of view. For this reason, it is desirable to use Z (i.e., the fault position) in the above formula as the relative position from the board-side reference plane.

[0082] (Create a confirmation image) The contour shape image creation unit 222 in this embodiment creates a contour shape image by superimposing a non-defective product standard profile, which is a plot of the non-defective product standard calculated by the non-defective product standard calculation unit 221, on the contour shape of the solder at the inspection target location. Here is an example.

[0083] 9A is a diagram showing a vertical projection image and a contour shape image in which an upper-limit non-defective reference profile is superimposed, and FIG. 9B is a diagram showing a vertical projection image and a contour shape image in which a lower-limit non-defective reference profile is superimposed. When the non-defective reference profile is superimposed, the magnitude relationship between the profile value indicating the contour shape of the inspection target area and the non-defective reference profile value is compared at each cross-sectional position, and parts that do not meet the non-defective standard can be highlighted in both the contour shape image and the vertical projection image. In the example shown in FIG. 9B, a part of the solder shape of the inspection target area has an area smaller than the lower-limit non-defective standard (i.e., it deviates from the lower-limit standard and does not meet the non-defective standard), so that part is highlighted.

[0084] The acceptable product standard calculation unit 221 may calculate acceptable product standards separately for the solder portion from the ball center plane to the component-side reference plane (hereinafter simply referred to as the component-side solder) and the solder portion from the ball center plane to the board-side reference plane (hereinafter simply referred to as the board-side solder). Fig. 10A shows an example of an approximation curve when calculating acceptable product standards separately for the component-side solder and the board-side solder. Fig. 10B shows an example of a component-side perpendicular projection image and a component-side contour shape image when a acceptable product standard profile for the component-side solder is superimposed on the component-side contour shape image. Fig. 10C shows an example of a board-side perpendicular projection image and a board-side contour shape image when a acceptable product standard profile for the board-side solder is superimposed on the board-side contour shape image.

[0085] (Processing flow) Next, referring to Figures 11 and 12, we will explain the process flow in this embodiment for calculating the quality standards based on a quality substrate (hereinafter also referred to as the learning stage, etc.), and the process flow up to displaying a confirmation image reflecting the quality standards during inspection (hereinafter also referred to as the inspection stage, etc.).

[0086] Fig. 11 is a flowchart showing the flow of processing in the learning stage of this embodiment. As shown in Fig. 11, in the learning stage, first, X-ray images of a non-defective board are taken by the X-ray imaging device 11 (S201). Then, the three-dimensional data creation unit 123 creates non-defective three-dimensional data of the board from the multiple X-ray images (S202).

[0087] Next, the quality criteria calculation unit 221 executes the process of loop L3, described below, for all land groups (e.g., set in advance by the user) for which quality criteria are to be calculated. Specifically, for each land group for which the same measurement conditions are set, the process of loop L4, described below, is executed for all lands in the land group. In loop L4, first, the ball center plane is identified from the three-dimensional data created in step S202 (S203), and then the board-side reference plane and the component-side reference plane are identified (S204, S205). Note that the order of the processes of steps S204 and S205 may be reversed. Next, the quality criteria calculation unit 221 executes the process of the next loop L5 for each horizontal tomographic image within the range between the board-side reference plane and the component-side reference plane. Specifically, each horizontal tomographic image within the range is subjected to binarization processing, and the area and center of gravity of the solder in each horizontal tomographic image are calculated (S206).

[0088] The non-defective product criteria calculation unit 221 ends the processing of loop L5 when the area and center of gravity of the solder in all horizontal sections have been calculated. Then, when the processing of loop L4 has been completed for all lands, the non-defective product criteria calculation unit 221 calculates an upper limit approximation curve and a lower limit approximation curve based on the information calculated in loop L4 and loop L5 (S207). Then, when the processing of step S207 (i.e., calculation of the upper limit approximation curve and the lower limit approximation curve) has been completed for all land groups, the processing of loop L3 ends, and a series of routines in the learning stage is completed. Note that the approximation curves created in step S207 (or the non-defective product criteria calculated therefrom) are used to calculate the non-defective product criteria. It is preferable that the information on the reference surface profile (quasi-profile) is stored in the data server 13. The processes executed in steps S203 to S206 are the same as the processes executed by the reference surface identification unit 1251 and the area centroid position calculation unit 1252.

[0089] Next, the processing flow of the inspection stage in this embodiment will be described with reference to FIG. 12. However, since the processing flow of the inspection stage in this embodiment is substantially the same as the processing flow in the X-ray inspection system 1 according to the first embodiment, the same steps as those in the X-ray inspection system 1 are denoted by the same reference numerals and will not be described again. As shown in FIG. 12, the processing flow of the inspection stage in this embodiment differs from the processing flow in the X-ray inspection system 1 only in that step S301 is included between steps S109 and S110. That is, after the processing of loop L1 is completed and the user selects a land for which a confirmation image is to be displayed at any time in S109, the confirmation image creation unit 125 creates a confirmation image including a contour shape image with a non-defective reference profile superimposed (S301). At this time, if there is a portion of the solder at the inspection target location that deviates from the non-defective reference, a contour shape image and a vertical projection image are created with the portion highlighted. Then, the created confirmation image is displayed in step S110.

[0090] As described above, the X-ray inspection system 2 according to this embodiment can superimpose a profile of a non-defective standard learned from a non-defective board onto a contour image, and highlight faults corresponding to solder areas that do not meet the non-defective standard. This allows the user to easily check the difference in contour shape between a non-defective and defective part, even for parts such as BGAs that have metal bumps formed on the package bottom.

[0091] <Embodiment 3> Next, an X-ray inspection system 3 according to still another embodiment will be described with reference to Fig. 13 and Fig. 14. The X-ray inspection system 3 according to this embodiment shares many of the configurations and processes with the above-described X-ray inspection system 2, and therefore the same configurations, functions, and processes are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0092] Fig. 13 is a schematic block diagram showing the functional configuration of the X-ray inspection system 3 according to this embodiment. As shown in Fig. 13, the X-ray inspection system 3 according to this embodiment has the same functional configuration as the X-ray inspection system 2, except that it includes functional units of an inspection standard value calculation unit 321 and an inspection standard setting unit 322.

[0093] The inspection standard value calculation unit 321 calculates the rate of agreement between the upper limit approximation curve and the lower limit approximation curve calculated by the non-defective product standard calculation unit 221 and an approximation curve based on the average value of the area of ​​each horizontal cross section for each land in the non-defective product three-dimensional data. The average value of the area of ​​each horizontal cross section for each land in the non-defective product three-dimensional data may be calculated by the non-defective product standard calculation unit 221 or by the inspection standard value calculation unit 321. In this embodiment, the rate of agreement between the upper limit approximation curve and the average value of the area of ​​each horizontal cross section for each land in the non-defective product three-dimensional data is referred to as the upper side agreement rate. Furthermore, the rate of agreement between the lower limit approximation curve and the average value of the area of ​​each horizontal cross section for each land in the non-defective product three-dimensional data is referred to as the lower side agreement rate.

[0094] Then, the inspection standard setting unit 322 sets the upper side match rate and the lower side match rate calculated by the inspection standard value calculation unit 321 as the inspection standard for the component (for the corresponding land). Specifically, the calculated upper side match rate and lower side match rate are saved (initial registration) as the inspection standard values ​​to be stored in the data server 13, or the existing inspection standard is overwritten with these values.

[0095] Generally, the evaluation index called the match rate is a value that depends on internal information processing (algorithm) and is not a physical value, so it is relatively difficult for users to use the match rate in testing. It is not easy to determine an appropriate inspection standard value, especially during initial setup. On the other hand, a commonly used method is to statistically determine pass / fail based on a multiple determined by the user for the variation range (of non-defective products). In this regard, the upper and lower limit approximation curves used to calculate the upper and lower match rates have their variation range adjusted using the multiple n of the standard deviation, as described above. That is, if the user sets the value of n during the learning stage, after learning, the inspection standard value calculation unit 321 calculates the upper and lower limit match rates, and the inspection standard setting unit 322 sets these as the inspection standard value. Therefore, even for inspection standards that are difficult for users to implement, such as match rates, the inspection standard value can be easily set.

[0096] (Processing flow) Next, the processing flow of the learning stage in this embodiment will be described with reference to Fig. 14. However, since the processing flow of the learning stage in this embodiment is almost the same as the processing in the X-ray inspection system 2 according to embodiment 2, the same processes as those in the X-ray inspection system 2 are denoted by the same reference numerals and descriptions thereof will be omitted. As shown in Fig. 14, the processing flow of the learning stage in this embodiment differs from the processing in the X-ray inspection system 2 only in that processing of steps S401 and S402 has been added. Note that with the addition of this processing, the loop processing equivalent to loop L3 in Fig. 14 is designated as loop L6.

[0097] In the learning stage of this embodiment, when the processing of a series of loops L4 is completed, the upper and lower limit approximation curves are calculated in S207, and then the inspection standard value calculation unit 321 calculates the upper and lower match rates (S401). Then, the inspection standard setting unit 322 sets the upper and lower match rates as the inspection standards for the part (S402), completing the processing of loop L6 and terminating the series of routines for the learning stage.

[0098] According to the X-ray inspection system 3 of this embodiment as described above, the inspection standard setting unit automatically sets the inspection standard, so even a user who is unfamiliar with setting inspection standards can operate the inspection system. Furthermore, once the inspection standard is set, the set inspection standard can be fine-tuned through the operation of the board inspection, so the user can manually set more appropriate inspection standards.

[0099] <Embodiment 4> Next, we will explain an X-ray inspection system 4, which is yet another embodiment. In each of the above embodiments, the area (and center of gravity) of each horizontal slice of three-dimensional data was used to create a solder contour image. Furthermore, the inspection criteria were also based on the area value of each horizontal slice. However, in the case of a defect in which the solder on the component side and the solder on the board side are laterally misaligned during component mounting (a so-called "pillow defect"), each of the above embodiments cannot properly display the solder contour as a two-dimensional shape viewed from the user's desired observation direction. The X-ray inspection system 4 according to this embodiment is configured to be able to handle cases in which such a pillow defect exists.

[0100] Fig. 15 is a schematic block diagram showing the functional configuration of the X-ray inspection system 4. As shown in Fig. 15, the X-ray inspection system 4 according to this embodiment has many configurations and processes in common with the above-mentioned X-ray inspection system 3, and therefore, the same configurations, functions and processes are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0101] Compared with the X-ray inspection system 3, the X-ray inspection system 4 further includes a functional unit of a non-defective product roundness calculation unit 424. Also, the functions of the non-defective product standard calculation unit 421, the inspection standard value calculation unit 422, the inspection standard setting unit 423, and the confirmation image creation unit 425 are slightly different from those of the X-ray inspection system 3. The confirmation image creation unit 425 includes a roundness calculation unit 4244 in addition to the reference surface identification unit 1251, the major axis center of gravity position calculation unit 4252, the contour shape image creation unit 4253, and the vertical projection image creation unit 1254. The image forming unit 4255 and the circularity image forming unit 4256 are provided.

[0102] The function of the reference plane specifying unit 1251 of the X-ray inspection system 4 is similar to that of the X-ray inspection systems of the other embodiments, but the processing performed by the major axis centroid position calculation unit 4252 on the three-dimensional data of the range specified by the reference plane specified by the reference plane specifying unit 1251 differs from that of the X-ray inspection systems of the other embodiments. Specifically, while the area centroid position calculation unit 1252 of the X-ray inspection systems of the other embodiments calculates the area and centroid position of the solder in each horizontal tomographic plane, the major axis centroid position calculation unit 4252 performs binarization processing on each horizontal tomographic image in the range between the board-side reference plane and the component-side reference plane, and calculates the "major axis" and centroid position of the solder in each horizontal tomographic plane. Here, the major axis can be, for example, the length of the major axis when the binarization result is approximated as an ellipse.

[0103] Then, the contour image creation unit 4253 creates a contour image showing the contour shape of the solder in the observation plane desired by the user based on the calculated "half-value of the major axis" of the solder in each horizontal section and the center of gravity position. A contour image created in this way can show the appropriate contour shape even for solder joints with pillow defects.

[0104] Furthermore, the vertical projection image creation unit 1254 creates a vertical projection image by projecting the binarized image of each horizontal cross section processed by the major axis centroid position calculation unit 4252 in the depth direction of the observation plane desired by the user.

[0105] Furthermore, the circularity calculation unit 4255 calculates the circularity of the solder in each horizontal plane. Specifically, the circularity is calculated by: 4×area÷(π×major axis) 2 Then, the circularity image creation unit 4256 creates a circularity image showing a curve obtained by plotting the calculated circularity in a two-dimensional graph area with the position of each horizontal cross section as one axis and the circularity as the other axis.

[0106] 16A and 16B show examples of a contour shape image, a vertical projection image, and a circularity image in this embodiment. FIG. 16A shows an image of a solder joint with a pillow defect, and FIG. 16B shows examples of a contour shape image, a vertical projection image, and a circularity image of the solder joint. As shown in FIG. 16B, the horizontal axis of the circularity image represents the position of each horizontal cross section (relative to the board-side reference surface) and the vertical axis represents circularity (%). The horizontal axis of the contour shape image in this embodiment represents the ratio (%) of the half-value of the major axis to the land radius, and the left and right plot positions are determined based on the center of gravity of each horizontal cross section. While each image shown in FIG. 16B shows the entire area between the board-side reference surface and the component-side reference surface of the solder joint, each image in this embodiment can also be displayed with the component side and the board side of the solder joint separated.

[0107] The non-defective product standard calculation unit 421 calculates a single non-defective product standard for the solder at the inspection target location from three-dimensional data of the non-defective product created based on an X-ray image of the non-defective component mounting board. Here, except for the fact that the parameter used in calculating the standard is the "major axis" rather than the "area" of the solder in each horizontal section, the non-defective product standard calculation unit 421 has the same function as the non-defective product standard calculation unit 221 in other embodiments, and therefore a detailed description thereof will be omitted.

[0108] In this embodiment, the contour shape image creation unit 4253 creates a contour shape image in which a non-defective reference profile, which is a plot of the non-defective reference calculated by the non-defective reference calculation unit 421, is superimposed on the contour shape of the solder at the inspection target location (see FIG. 16B). When the non-defective reference profile is superimposed, the magnitude relationship between the profile value indicating the contour shape of the inspection target location and the non-defective reference profile value is compared at each cross-sectional position, and parts that do not satisfy the non-defective reference can be highlighted.

[0109] The non-defective roundness calculation unit 424 calculates the non-defective roundness, which is another standard for the solder at the inspection target location, from three-dimensional data of the non-defective product created based on an X-ray image of the non-defective component mounting board. The non-defective roundness calculation unit 424 also calculates a circularity upper limit approximation curve that indicates the upper limit of the circularity of the solder as a non-defective product, and a circularity lower limit approximation curve that indicates the lower limit.

[0110] The circularity image creation unit 4256 creates a circularity image by plotting the circularity of the solder at the inspection target location in a two-dimensional graph area with the horizontal cross-section position of the solder as one axis and the circularity as the other axis. In addition, a non-defective product circularity profile, in which the non-defective product circularity calculated by the non-defective product circularity calculation unit 424 is plotted, may be superimposed on the circularity image.

[0111] Furthermore, when the non-defective product roundness profile is superimposed, the profile value indicating the roundness of the inspection target point is compared with the non-defective product roundness profile value at each cross-sectional position, and areas that do not meet the criteria for a non-defective product can be highlighted in both the roundness image and the vertical projection image (see Figure 16B). For pillow defects, roundness is generally used as the standard for determining whether the product is good or bad, given the shape characteristics of the pillow, so if the roundness standard is not met, it is desirable to highlight the area in the vertical projection image as well.

[0112] The inspection standard value calculation unit 422 calculates the match rates (upper match rate and lower match rate in this embodiment) between the roundness upper limit approximation curve and the roundness lower limit approximation curve indicating the lower limit calculated by the non-defective product roundness calculation unit 424 and an approximation curve based on an average roundness value calculated from the area and major axis of each horizontal cross section for each land in the non-defective product three-dimensional data. The average roundness value of each horizontal cross section for each land in the non-defective product three-dimensional data may be calculated by the non-defective product roundness calculation unit 424 or by the inspection standard value calculation unit 422. That is, the inspection standard value calculation unit 422 has the same functional components as the inspection standard value calculation unit 321 in the X-ray inspection system 3, except that the parameter used is roundness instead of area, and therefore a detailed description thereof will be omitted.

[0113] The inspection standard setting unit sets the upper and lower match rates calculated by the inspection standard value calculation unit 422 as the inspection standards for the component (or the land of the component). Alternatively, or in addition to this, the upper limit approximation curve and the lower limit approximation curve calculated by the non-defective product standard calculation unit 421 may be set as the inspection standards.

[0114] According to the X-ray inspection system 4 of this embodiment, even if a defective product such as a defective pillow is involved, the user can easily confirm the difference in contour shape between a non-defective product and a defective product.

[0115] <Other> The above-described embodiments merely exemplify the present invention, and the present invention is not limited to the specific embodiments described above. Various modifications and combinations of the present invention are possible within the scope of the technical concept thereof. For example, in the above-described embodiments, the inspection terminal is configured to include a display unit. However, the inspection terminal may not include a display unit, and a screen including a confirmation image may be displayed on a separate display unit connected to the inspection terminal via wired or wireless communication.

[0116] Furthermore, the confirmation image creation unit 425 of the fourth embodiment may further include an area centroid position calculation unit 1252. That is, a conformance standard for area, a conformance standard for major axis, and a conformance standard for roundness may be calculated, and an approximate curve for each conformance standard may be displayed on the confirmation image.

[0117] In addition, in each of the above embodiments, the confirmation images include vertical projection images, but the confirmation images do not necessarily have to include vertical projection images. That is, the X-ray inspection system may not include a vertical projection image creation unit.

[0118] Furthermore, at least a part of the data server in each of the above embodiments may be provided as storage means in the inspection terminal. Conversely, in each of the above examples, the X-ray inspection system may be provided as an integrated device, that is, a CT scanner and a console integrated together. In each of the above examples, inspection of the board (determination of pass / fail) may be performed at any time between steps S102 and S109, and the inspection results may be displayed together on the confirmation screen displayed in step S110.

[0119] <Additional Notes> An inspection system (1) for a component mounting board on which electronic components are surface-mounted, the electronic component has metal bumps formed on the bottom surface of the package for soldering to the component mounting substrate, X-ray generating means (111) for irradiating the component mounting board with X-rays; X-ray imaging means (112) for capturing an image of X-rays transmitted through the component mounting board; a three-dimensional data creation means (123) that creates three-dimensional data of an area including at least a solder joint between the component mounting board and the electronic component using information on a plurality of X-ray images taken by the X-ray photography means; a confirmation image creation means (125) for creating a confirmation image showing the shape of the solder at the solder joint as a two-dimensional shape of an observation surface desired by a user using the three-dimensional data; and a display means (122) for displaying the image created by the confirmation image creation means. [Explanation of symbols]

[0120] 1, 2, 3, 4... X-ray inspection system 9. X-ray inspection equipment 11. X-ray equipment 12, 22, 32, 42... Inspection terminal 13. Data Server 111, 92...X-ray source 112, 93... X-ray camera 113 Stage 125, 425...Confirmation image creation section 921, 931...X Stage 922, 932...Y stage C1, C2...Circular orbit O...Component mounting board

Claims

1. An inspection system for a component mounting board on which electronic components are surface-mounted, comprising: the electronic component has metal bumps formed on the bottom surface of the package for soldering to the component mounting substrate, X-ray generating means for irradiating the component mounting board with X-rays; an X-ray imaging means for capturing an image of X-rays transmitted through the component mounting board; a three-dimensional data creation means for creating three-dimensional data of an area including at least a solder joint between the component mounting board and the electronic component, using information on a plurality of X-ray images taken by the X-ray imaging means; a confirmation image creation means for creating a confirmation image that shows the shape of the solder at the solder joint as a two-dimensional shape of an observation surface desired by a user, using the three-dimensional data; a display means for displaying a screen including the confirmation image created by the confirmation image creation means, The confirmation image creating means a reference plane specifying means for specifying, in the three-dimensional data, a component-side reference plane which is a horizontal tomographic position serving as a reference on the electronic component side in the solder joint, and a board-side reference plane which is a horizontal tomographic position serving as a reference on the component-mounting board side; At least one of a horizontal tomographic solder area calculation means for calculating the area and center of gravity of the solder of each horizontal tomographic layer that constitutes the three-dimensional data between the component-side reference surface and the board-side reference surface, or a horizontal tomographic solder major axis calculation means for calculating the major axis and center of gravity of the solder of each horizontal tomographic layer that constitutes the three-dimensional data between the component-side reference surface and the board-side reference surface; and at least one of a first profile image creating means for creating a first profile image showing a contour shape of the solder on the observation surface based on the area and the center of gravity of the solder on each horizontal cross section, and a second profile image creating means for creating a second profile image showing a contour shape of the solder on the observation surface based on the half-value of the major axis of the solder on each horizontal cross section and the center of gravity of the solder on each horizontal cross section, The confirmation image includes at least one of the first profile image and the second profile image. Inspection system.

2. a first non-defective product standard calculation means for calculating a first non-defective product standard relating to the area of ​​each horizontal cross section of the solder based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component-mounted board that is a non-defective product, the confirmation image creation means includes the horizontal tomographic solder area calculation means and the first profile image creation means, the first profile image creation means creates the first profile image showing the contour shape of the solder and the first non-defective product standard; 2. The inspection system of claim 1.

3. the first conforming product standard calculation means calculates a first upper limit approximation curve indicating an upper limit of the area of ​​each horizontal layer of the solder as a conforming product and a first lower limit approximation curve indicating a lower limit of the area of ​​each horizontal layer of the solder based on the one or more conforming product three-dimensional data; the first profile image creating means creates the first profile image showing at least one of a first upper limit profile created based on the first upper limit approximation curve and a first lower limit profile created based on the first lower limit approximation curve superimposed on the contour shape of the solder; 3. The inspection system according to claim 2.

4. a storage means for storing an inspection standard for determining whether the solder joints on the component mounting board are good or bad; a first inspection standard initial value calculation means for calculating, based on the one or more non-defective product three-dimensional data, a first upper limit side coincidence rate, which is a coincidence rate between an approximation curve based on an average value of areas in each horizontal cross section of the solder of the non-defective product, and the first upper limit side coincidence rate, and a first lower limit side coincidence rate, which is a coincidence rate between the approximation curve based on an average value of areas in each horizontal cross section of the solder of the non-defective product, and the first upper limit side coincidence rate. a first inspection standard setting means for setting the first upper limit side coincidence rate and the first lower limit side coincidence rate as at least a part of the inspection standard, 4. The inspection system according to claim 3, wherein:

5. the first conforming product standard calculation means calculates the first conforming product standard for the electronic component side and the component mounting board side, with a predetermined position between the component-side reference surface and the board-side reference surface of the solder joint as a boundary; the first profile image creation means creates the first profile image, which indicates the first conforming standard on the electronic component side for the contour shape of the solder joint portion on the electronic component side, and which indicates the first conforming standard on the component mounting board side for the contour shape of the solder joint portion on the component mounting board side.

5. An inspection system according to claim 2, wherein the inspection system comprises:

6. a second non-defective product standard calculation means for calculating a second non-defective product standard relating to the major axis of each horizontal cross section of the solder based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component-mounted board that is a non-defective product, the confirmation image creating means includes the horizontal tomographic solder long diameter calculating means and the second profile image creating means, the second profile image creating means creates the second profile image showing the contour shape of the solder and the second non-defective product standard; 6. An inspection system according to claim 1, wherein the inspection system comprises:

7. the second conforming product standard calculation means calculates a second upper limit approximation curve indicating an upper limit of the major axis of each horizontal layer of the solder as a conforming product and a second lower limit approximation curve indicating a lower limit of the major axis of each horizontal layer of the solder, based on the one or more conforming product three-dimensional data; the second profile image creating means creates the second profile image showing at least one of a second upper limit profile created based on the second upper limit approximation curve and a second lower limit profile created based on the second lower limit approximation curve superimposed on the contour shape of the solder; 7. The inspection system according to claim 6, wherein:

8. a storage means for storing an inspection standard for determining whether the solder joints on the component mounting board are good or bad; a second inspection standard initial value calculation means for calculating, based on the one or more non-defective product three-dimensional data, a second upper limit side coincidence rate, which is a coincidence rate between an approximation curve based on the average values ​​of the major axes of the horizontal tomograms of the solder of the non-defective product and the second upper limit approximation curve, and a second lower limit side coincidence rate, which is a coincidence rate between the approximation curve based on the average values ​​of the major axes of the horizontal tomograms of the solder of the non-defective product and the second upper limit approximation curve; and second inspection standard setting means for setting the second upper limit side coincidence rate and the second lower limit side coincidence rate as at least a part of the inspection standard, 8. The inspection system according to claim 7, wherein:

9. the second conforming product standard calculation means calculates the second conforming product standard for the electronic component side and the component mounting board side, with a predetermined position between the component-side reference surface and the board-side reference surface of the solder joint as a boundary; the second profile image creation means creates the second profile image, which indicates the second conforming standard on the electronic component side for the contour shape of the solder joint portion on the electronic component side, and which indicates the second conforming standard on the component mounting board side for the contour shape of the solder joint portion on the component mounting board side.

9. An inspection system according to any one of claims 6 to 8, characterized in that it comprises:

10. The confirmation image creation means includes the horizontal fault solder long diameter calculation means and the second profile image creation means, a horizontal plane solder roundness calculation means for calculating the roundness of the solder of each horizontal plane constituting the three-dimensional data between the component-side reference plane and the board-side reference plane; and a third profile image creating means for creating a third profile image that displays a circularity profile in which the circularity is plotted in a two-dimensional graph area with the horizontal cross-sectional position as one axis and the circularity as the other axis.

10. An inspection system according to any one of claims 1 to 9, characterized in that

11. a third non-defective product standard calculation means for calculating a third upper limit approximation curve indicating an upper limit of the circularity of the solder as a non-defective product and a third lower limit approximation curve indicating a lower limit thereof, based on one or more non-defective product three-dimensional data created based on an X-ray image of one or more of the solder joints of the component-mounted board as a non-defective product; a storage means for storing an inspection standard for determining whether the solder joints on the component mounting board are good or bad; a third inspection standard initial value calculation means for calculating a third upper limit side coincidence rate, which is a coincidence rate between an approximation curve of the average circularity calculated from the average values ​​of the area and major axis in each horizontal cross section of the solder of the non-defective product and the third upper limit approximation curve, and a third lower limit side coincidence rate, which is a coincidence rate between the approximation curve of the average circularity calculated from the average values ​​of the area and major axis in each horizontal cross section of the solder of the non-defective product, and the third upper limit approximation curve, based on the one or more non-defective product three-dimensional data; and a third inspection standard setting means for setting the third upper limit side coincidence rate and the third lower limit side coincidence rate as at least a part of the inspection standard.

11. The inspection system of claim 10.

12. The confirmation image creating means a vertical projection image creation means for performing binarization processing on each horizontal tomographic image between the component-side reference plane and the board-side reference plane of the three-dimensional data, and creating a vertical projection image by projecting the binarized result in a depth direction of an observation plane desired by a user; The verification image includes the vertical projection image. Inspection system according to any one of claims 1 to 11, characterized in that it comprises:

13. The method further includes an inspection standard acquisition means for acquiring an inspection standard related to quality determination of the solder joints on the component mounting board, the confirmation image creation means, when there is a part of the two-dimensional shape that is determined to be defective in light of the inspection standard, highlights and displays the part that is determined to be defective; Inspection system according to any one of claims 1 to 12, characterized in that it comprises:

14. the confirmation image creation means creates a first confirmation image showing the shape of the solder of the entire solder joint, a second confirmation image showing only the shape of the solder on the electronic component side of the solder joint, a third confirmation image showing only the shape of the solder on the component mounting board side of the solder joint, and a fourth confirmation image showing the second confirmation image and the third confirmation image simultaneously; the display means displays a screen including any one of the first to fourth confirmation images. Inspection system according to any one of claims 1 to 13, characterized in that it comprises:

15. An inspection information processing terminal comprising the three-dimensional data creation means and the confirmation image creation means, and constituting at least a part of the inspection system according to any one of claims 1 to 14.

16. A program for causing a computer to function as the inspection information processing terminal according to claim 15.

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