JP5732144B2 - X-ray inspection apparatus and X-ray inspection method - Google Patents

Description

  The present invention relates to an X-ray inspection apparatus and an X-ray inspection method, and more particularly to an X-ray inspection apparatus and an X-ray inspection method for inspecting a state of a connection portion between a component and a substrate.

  Conventionally, an X-ray inspection apparatus that inspects the state of a connection portion between a component and a substrate is known. Such an X-ray inspection apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-145359.

  In the above-mentioned JP 2010-145359 A, an X-ray source that irradiates X-rays on a substrate on which components are mounted, and an X-ray detector (X-ray imaging) that detects and images X-rays irradiated on the substrate. Part) and an operation part (control part) for inspecting the state of the connection part between the component and the substrate. In the X-ray inspection apparatus described in Japanese Patent Application Laid-Open No. 2010-145359, the calculation unit acquires a plurality of tomographic images having a horizontal cross section parallel to the surface of the substrate at intervals, and the acquired plurality of images. On the basis of the tomographic image, the state of the connection portion between the component and the substrate is inspected.

JP 2010-145359 A

  However, in the X-ray inspection apparatus described in Japanese Patent Application Laid-Open No. 2010-145359, the tomographic images of horizontal sections parallel to the surface of the substrate are acquired at intervals, and thus intersect with the surface of the substrate. There is an inconvenience that it is difficult to accurately grasp the connection shape of the direction connection portion with a small number of images. For this reason, there is a problem that it is difficult to accurately inspect the state of the connection portion between the component and the substrate in the direction intersecting the surface of the substrate with a small number of images.

  The present invention has been made in order to solve the above-described problems, and one object of the present invention is to image a state of a connection portion between a component and a substrate in a direction intersecting the surface of the substrate. It is an object to provide an X-ray inspection apparatus and an X-ray inspection method that can accurately inspect by the number of sheets.

An X-ray inspection apparatus according to a first aspect of the present invention includes an X-ray source that irradiates a substrate on which a component is mounted with X-rays, an X-ray imaging unit that captures an image based on the X-rays irradiated on the substrate, and A control unit that inspects the state of the connection part between the component and the board, and the control part includes a target connection part and is in a direction intersecting a target surface that intersects the surface of the board , and The connection shape of the connection part between the component and the substrate on the target surface is obtained by performing coordinate conversion of the image on the imaging surface intersecting with the target surface imaged by irradiating X-rays from the obliquely upward direction of the target surface to the image of the target surface Is configured to get.

  In the X-ray inspection apparatus according to the first aspect of the present invention, as described above, the control unit irradiates X-rays from the direction intersecting the target surface that includes the target connection unit and intersects the surface of the substrate. The target surface that intersects the surface of the board is configured to acquire the connection shape of the connection part between the component and the board on the target surface by converting the image on the imaging surface captured in this way into the image of the target surface. Based on the connection shape of the connection portion between the component and the substrate in FIG. 1, it is possible to accurately grasp the change in the connection shape of the connection portion in the direction intersecting the surface of the substrate. Thereby, the state of the connection part between the component and the board in the direction intersecting the surface of the board can be accurately inspected with a small number of images.

  In the X-ray inspection apparatus according to the first aspect described above, preferably, the control unit obtains a cross-sectional image of the connection unit in the target surface intersecting the surface of the substrate based on the captured image, thereby connecting the connection unit. It is configured to acquire a shape. If comprised in this way, the state of the connection part of the components and board | substrate in the direction which cross | intersects with respect to the surface of a board | substrate can be test | inspected easily and accurately using the cross-sectional image of the connection part in the acquired object surface. .

  In the X-ray inspection apparatus according to the first aspect, preferably, the control unit is configured to acquire the connection shape of the connection unit on the target surface that intersects substantially perpendicularly to the surface of the substrate. If comprised in this way, the state of the connection part of the components and board | substrate in the direction which cross | intersects substantially perpendicular | vertical with respect to the surface of a board | substrate can be test | inspected easily and accurately.

  In the X-ray inspection apparatus according to the first aspect, preferably, the target surface is a surface including a lead provided on a component and solder. With this configuration, it is possible to easily inspect the connection state between the component leads and the solder in the direction intersecting the surface of the substrate. Further, when the entire shape in the longitudinal direction of the lead can be grasped by one target surface, it is possible to easily and accurately inspect the connection state between the lead and the solder over the entire longitudinal direction of the lead with one cross-sectional image on the target surface. it can.

  In the X-ray inspection apparatus according to the first aspect, preferably, the control unit intersects the surface of the substrate based on a plurality of images captured by irradiating X-rays from a plurality of directions intersecting the target surface. It is configured to acquire the connection shape of the connection part by removing the noise of the cross-sectional image of the connection part on the surface. With this configuration, the noise of the cross-sectional image of the connection portion on the target surface that intersects the surface of the substrate is removed, so the clear cross-sectional image without noise is used to The state can be inspected more accurately. Note that noise refers to an image other than the inspection object that appears in the cross-sectional image.

  In this case, preferably, the control unit is configured to remove the noise of the cross-sectional image on the target surface and synthesize a plurality of images to obtain the connection shape of the connection unit. If comprised in this way, since a part without a noise can be extracted and synthesize | combined from several images, the noise of the cross-sectional image in an object surface can be removed easily.

  In the configuration for capturing the plurality of images, preferably, the control unit compares the X-ray transmission amounts of the plurality of images and synthesizes a portion where the X-ray transmission amount is large, thereby obtaining a cross-sectional image on the target surface. It is comprised so that the obstruction as a noise in may be removed. If comprised in this way, since the obstruction with which the transmitted amount of X-rays becomes small is removed by the synthesis | combination of a several image, the noise of the cross-sectional image in an object surface can be removed more easily.

  In the X-ray inspection apparatus according to the first aspect, preferably, the control unit specifies a target surface based on a planar image obtained by imaging the substrate by the X-ray imaging unit from a direction substantially perpendicular to the surface of the substrate. Is configured to do. If comprised in this way, the target surface which cross | intersects the surface of a board | substrate can be easily specified based on the plane image imaged with the X-ray imaging part. Further, even when the connection part is hidden behind a part or the like and cannot be seen, the connection part can be confirmed by the transmitted X-ray, so that the target surface including the connection part can be reliably identified.

  In this case, preferably, the control unit is configured to specify a target surface including the connection unit by acquiring a position of the connection unit in plan view based on a planar image captured by the X-ray imaging unit. If comprised in this way, since the position of the connection part in planar view on the surface of a board | substrate can be acquired based on the plane image imaged with the X-ray imaging part, the target surface which cross | intersects the surface of a board | substrate can be more easily Can be specified.

  The X-ray inspection apparatus according to the first aspect preferably further includes an optical imaging unit that images the substrate with visible light, and the control unit is configured to transmit the optical imaging unit from a direction that intersects the surface of the substrate substantially perpendicularly. The target surface is specified based on a planar image obtained by imaging the substrate. If comprised in this way, the target surface which cross | intersects the surface of a board | substrate can be easily specified based on the plane image imaged with the optical imaging part.

  In this case, preferably, the control unit is configured to specify a target surface including the connection unit by acquiring the position of the connection unit in plan view based on the planar image captured by the optical imaging unit. If comprised in this way, since the position of the connection part in planar view on the surface of a board | substrate can be acquired based on the planar image imaged by the optical imaging part, the target surface which cross | intersects the surface of a board | substrate can be more easily Can be identified.

  In the X-ray inspection apparatus according to the first aspect, preferably, the control unit is configured to inspect the state of the connection part based on the dimension of the connection shape of the connection part on the target surface. If comprised in this way, the state of the connection part of the components and board | substrate in the direction which cross | intersects with respect to the surface of a board | substrate can be test | inspected quantitatively and accurately based on the dimension of a connection shape.

  In the X-ray inspection apparatus according to the first aspect, preferably, the component and the substrate are connected by a plurality of connection portions, and the control unit is not parallel to any of the plurality of target surfaces including the target connection portion. X-rays are emitted from an X-ray source from the direction, and an image is picked up by an X-ray imaging unit. If comprised in this way, since the connection shape in the target surface of many connection parts can be acquired by one imaging by an X-ray imaging part, compared with the case where the connection shape of a connection part is acquired individually. The number of X-ray irradiations can be reduced.

  In the X-ray inspection apparatus according to the first aspect, preferably, the control unit irradiates the X-ray from the four or eight directions intersecting the target surface with the X-ray source and images the X-ray imaging unit. It is configured. If comprised in this way, the cross-sectional image of the connection part in a target surface with a sufficient precision can be acquired based on the image imaged by irradiating X-rays from multiple directions. In addition, the number of times of X-ray irradiation can be reduced as compared with CT (Computer Tomography) that irradiates many X-rays for imaging one image. Thereby, since the burden of an X-ray source can be made small, the lifetime of an X-ray source can be lengthened.

An X-ray inspection method according to a second aspect of the present invention includes a step of irradiating a substrate on which a component is mounted with an X-ray, a step of capturing an image based on the X-ray irradiated on the substrate, a component and a substrate, The step of inspecting the state of the connecting portion, and the step of inspecting the state of the connecting portion is a direction intersecting the target plane that includes the target connecting portion and intersects the surface of the substrate , and By converting the image on the imaging surface that intersects the target surface imaged by irradiating X-rays from the diagonally upward direction of the target surface to the target surface image, the connection shape of the connection part between the component and the substrate on the target surface is changed. Including the step of obtaining.

  In the X-ray inspection method according to the second aspect of the present invention, as described above, imaging is performed by irradiating X-rays from a direction intersecting a target surface that includes the target connection portion and intersects the surface of the substrate. By converting the image on the surface into the image of the target surface, and providing the connection shape of the connection part between the component and the substrate on the target surface, the component and the substrate on the target surface intersecting the surface of the substrate Based on the connection shape of the connection portion, the change in the connection shape of the connection portion in the direction intersecting the surface of the substrate can be accurately grasped. Thereby, the state of the connection part between the component and the board in the direction intersecting the surface of the board can be accurately inspected with a small number of images.

  In the X-ray inspection method according to the second aspect, preferably, the step of inspecting the state of the connection portion acquires a cross-sectional image of the connection portion on the target surface intersecting the surface of the substrate based on the captured image. The process of acquiring the connection shape of a connection part is included. If comprised in this way, the state of the connection part of the components and board | substrate in the direction which cross | intersects with respect to the surface of a board | substrate can be test | inspected easily and accurately using the cross-sectional image of the connection part in the acquired object surface. .

  In the X-ray inspection method according to the second aspect, preferably, the step of inspecting the state of the connection portion is a step of acquiring the connection shape of the connection portion on the target surface that intersects substantially perpendicularly to the surface of the substrate. including. If comprised in this way, the state of the connection part of the components and board | substrate in the direction which cross | intersects substantially perpendicular | vertical with respect to the surface of a board | substrate can be test | inspected easily and accurately.

  In the X-ray inspection method according to the second aspect, preferably, the target surface is a surface including a lead provided on the component and solder. With this configuration, it is possible to easily inspect the connection state between the component leads and the solder in the direction intersecting the surface of the substrate. Further, when the entire shape in the longitudinal direction of the lead can be grasped by one target surface, it is possible to easily and accurately inspect the connection state between the lead and the solder over the entire longitudinal direction of the lead with one cross-sectional image on the target surface. it can.

  In the X-ray inspection method according to the second aspect, preferably, the step of inspecting the state of the connecting portion is based on a plurality of images captured by irradiating X-rays from a plurality of directions intersecting the target surface. Removing the noise of the cross-sectional image of the connection portion on the target surface intersecting the surface of the surface to obtain the connection shape of the connection portion. With this configuration, the noise of the cross-sectional image of the connection portion on the target surface that intersects the surface of the substrate is removed, so the clear cross-sectional image without noise is used to The state can be inspected more accurately.

  In the X-ray inspection method according to the second aspect, preferably, in the step of inspecting the state of the connection portion, the noise of the cross-sectional image on the target surface is removed by combining a plurality of images, and the connection shape of the connection portion Including the step of obtaining If comprised in this way, since a part without a noise can be extracted and synthesize | combined from several images, the noise of the cross-sectional image in an object surface can be removed easily.

  According to the present invention, as described above, the state of the connection portion between the component and the substrate in the direction intersecting the surface of the substrate can be accurately inspected with a small number of images.

It is the perspective view which showed the external appearance of the X-ray inspection apparatus by 1st Embodiment of this invention. It is the front view which looked at the inside of the X-ray inspection apparatus by 1st Embodiment of this invention from the front side. It is the top view which looked at the inside of the X-ray inspection apparatus by 1st Embodiment of this invention from the upper surface side. It is the block diagram which showed the structure on the control of the X-ray inspection apparatus by 1st Embodiment of this invention. It is a flowchart for demonstrating the board | substrate inspection process of the X-ray inspection apparatus by 1st Embodiment of this invention. It is a figure for demonstrating the case where the X-ray of the X-ray inspection apparatus by 1st Embodiment of this invention is irradiated from the direction (directly above) perpendicular | vertical to the surface of a board | substrate. It is a figure for demonstrating the case where the X-ray of the X-ray inspection apparatus by 1st Embodiment of this invention is irradiated from the direction (slant top) which inclines on the surface of a board | substrate. It is a figure for demonstrating the irradiation direction of the X-ray of the X-ray inspection apparatus by 1st Embodiment of this invention. It is the perspective view which showed the components and board | substrate which the X-ray inspection apparatus by 1st Embodiment of this invention inspects. It is a figure for demonstrating the target surface and projection surface of the X-ray inspection apparatus by 1st Embodiment of this invention. It is a figure for demonstrating the calculation procedure of the position in the target surface of the X-ray inspection apparatus by 1st Embodiment of this invention. It is a figure for demonstrating the calculation procedure and the synthesis | combination method of the image of the X-ray inspection apparatus by 1st Embodiment of this invention. It is a flowchart for demonstrating the board | substrate inspection process of the X-ray inspection apparatus by 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
With reference to FIGS. 1-12, the structure of the X-ray inspection apparatus 100 by 1st Embodiment of this invention is demonstrated.

  The X-ray inspection apparatus 100 according to the first embodiment of the present invention includes a circuit board (substrate 10) (see FIG. 9) on which an electronic component (component 10a) such as a QFP (Quad Flat Package) (see FIG. 9) is mounted. It is a board inspection apparatus that performs various inspections such as a solder bonding state inspection of a component 10a on a board 10 as an inspection object.

  As shown in FIG. 2, the X-ray inspection apparatus 100 covers the base 1, the substrate transport unit 2, the X-ray source 3, the X-ray imaging unit 4, the optical imaging unit 5, and the X-ray source 3. It mainly includes a shielding wall 6 and an exterior cover 7 (see FIG. 1) provided outside the shielding wall 6.

  As shown in FIG. 2, a substrate transport unit 2, an X-ray source 3, an X-ray imaging unit 4, an optical imaging unit 5, and a shielding wall 6 are installed on the base 1. Further, in the base 1, a controller 12 that controls the entire X-ray inspection apparatus 100 including the substrate transport unit 2, the X-ray source 3, the X-ray imaging unit 4, and the optical imaging unit 5, and a power source that supplies power The part 13 etc. are arranged. On the base 1, a pair of support bases 11 are disposed at both ends in the X direction and extend over substantially the entire length of the base 1 in the Y direction. A support beam 31 that supports the X-ray source 3 is installed on the pair of support tables 11. The controller 12 is an example of the “control unit” in the present invention.

  As shown in FIG. 2, the board | substrate conveyance part 2 contains a pair of conveyor 21 extended along a X direction. The pair of conveyors 21 can support the substrate 10 from both sides in the Y direction and transport it in the X direction. At the time of substrate inspection, the substrate 10 is moved above the base 1 (Z1 direction) by a clamping mechanism (not shown). ) Can be held (fixed) at a predetermined position. The pair of conveyors 21 is installed on the base 1 via a pair of guide rails 22 extending in the X direction and a pair of guide rails 23 extending in the Y direction. The pair of conveyors 21 can be moved in the X direction along the guide rail 22 by an X-axis motor and an X-axis ball screw (not shown), and the Y direction along the guide rail 23 by a Y-axis motor and a Y-axis ball screw (not shown). Can be moved to. Thereby, the board | substrate conveyance part 2 (a pair of conveyor 21) is comprised so that a movement on the base 1 in a horizontal direction (X direction and Y direction) is possible.

  When carrying the substrate 10, the substrate transport unit 2 moves the end 21 a on the X1 direction side of the conveyor 21 to the carry-in entrance A, and removes the substrate 10 from an upstream transport line (not shown) provided outside. At the time of inheriting and unloading, the end 21b on the X2 direction side of the conveyor 21 is moved to the unloading port B so that the substrate 10 can be transferred to a downstream transfer line (not shown). . Thus, the board | substrate conveyance part 2 is comprised so that the board | substrate 10 which is a test object may be conveyed through the internal area | region covered with the shielding wall 6. FIG. In addition, the pair of conveyors 21 has a variable interval in the Y direction according to the size of the substrate 10 by a motor and a ball screw (not shown) and a guide rail.

  As shown in FIG. 2, the X-ray source 3 is arranged at a position above (Z1 direction) the substrate transport unit 2 and emits X-rays to the substrate 10 arranged below (Z2 direction). It is configured. The X-ray source 3 is attached to the support beam 31 so as to be movable in the vertical direction (Z direction) by a drive mechanism (not shown). The support beam 31 extends in the X direction and both ends are fixed on the pair of support bases 11.

  The X-ray imaging unit 4 is disposed at a position below the X-ray source 3 and the substrate transport unit 2 and has a function of detecting X-rays transmitted through the substrate 10 and capturing an X-ray image. The X-ray imaging unit 4 is configured to be movable in the horizontal direction (X direction and Y direction in FIG. 3) by the moving mechanism 41 on the lower side of the substrate transport unit 2. Accordingly, the substrate transport unit 2 and the X-ray imaging unit 4 are moved horizontally to adjust the relative positional relationship between the X-ray source 3, the substrate 10, and the X-ray imaging unit 4, thereby making the direction perpendicular to the surface of the substrate 10. In addition to (directly upward direction), it is possible to image the substrate 10 by irradiating X-rays from a direction inclined to the surface of the substrate 10 (an oblique direction).

  The optical imaging unit 5 is arranged at a position above the substrate transport unit 2 (Z1 direction) and below the X-ray source 3 (Z2 direction). The optical imaging unit 5 includes a camera 51 and a light 52, as shown in FIG. The optical imaging unit 5 is configured to irradiate light (visible light) with a light 52 onto the substrate 10 disposed below (Z2 direction) and to capture an optical image with the camera 51. The optical imaging unit 5 is attached to the support base 11 so as to be movable in the X direction by a drive mechanism (not shown). Thereby, the optical imaging unit 5 is moved to the Z2 direction side (directly below) of the X-ray source 3, and the X-ray image is captured by the X-ray imaging unit 4 and the optical image is captured by the optical imaging unit 5 at the same time. It is possible.

  The shielding wall 6 has a substantially rectangular box shape covering an area on the base 1 including the X-ray source 3 (see FIG. 2). The shielding wall 6 is configured to cover the periphery of the X-ray source 3 and shield the X-rays in order to prevent leakage of the X-rays emitted from the X-ray source 3 to the outside. A shielding material (not shown) is also provided on the upper surface of the base 1, and the internal space surrounded by the base 1 and the shielding wall 6 is shielded. The shielding wall 6 is constituted by a plurality of plate-like wall members 61 attached to a support frame (not shown) installed on the pair of support bases 11. The wall member 61 includes a lead-like shielding material made of lead.

  As shown in FIG. 1, the exterior cover 7 has a box shape that is one size larger than the shielding wall 6 so that the box-shaped shielding wall 6 can be accommodated therein. The exterior cover 7 is provided separately from the shielding wall 6 and is configured to be removable with the shielding wall 6 attached. The exterior cover 7 includes a plurality of plate-like cover members (side cover members 71a and 71b and a top cover member 71c) (see FIG. 1).

  Further, as shown in FIG. 1, a slide-type opening / closing door 8 is provided on each of the front surface 100a and the rear surface 100b of the X-ray inspection apparatus 100, and the inside of the apparatus can be opened and closed. Each of the two open / close doors 8 includes an exterior member 8a on the outer surface and a shielding member (not shown) that shields X-rays arranged on the inner surface side. For this reason, the two opening / closing doors 8 are configured to function as a part of the shielding wall 6 that shields X-rays and to function as a part of the exterior cover 7. Each of the two opening / closing doors 8 is configured to enter a gap between the exterior cover 7 and the shielding wall 6 when opened.

  Further, as shown in FIG. 2, the left and right side surfaces 100 c of the X-ray inspection apparatus 100 are provided with shutter portions 9 for opening and closing the carry-in entrance A and the carry-out exit B, respectively. The board | substrate 10 can be carried in / out by the board | substrate conveyance part 2 (a pair of conveyor 21) through opening of the shutter part 9. FIG.

  The controller 12 is configured to control the entire X-ray inspection apparatus 100. The controller 12 is configured to inspect the state of the connecting portion 10b (the portion where the lead 10c and the solder 10d are joined) (see FIG. 10) between the component 10a and the substrate 10. Further, as shown in FIG. 4, the controller 12 is connected to the display unit 14, the X-ray source 3, the X-ray imaging unit 4, and the optical imaging unit 5. The controller 12 includes a display processing unit 12a, a program switching processing unit 12b, a program storage unit 12c, an inspection determination processing unit 12d, an image processing unit 12e, a device control calculation processing unit 12f, an equipment specific data storage unit 12g, and a motor control unit. 12h and an external input / output control unit 12i.

  The display processing unit 12a is configured to cause the display unit 14 to display the operating state, operation information, X-ray image, optical image, inspection result, and the like of the X-ray inspection apparatus 100. The program switching processing unit 12b is configured to read a program for controlling various operations of the X-ray inspection apparatus 100 from the program storage unit 12c and perform switching processing. In addition to the program, the program storage unit 12c stores board data such as the size of the board 10 to be inspected, the component mounting position, and circuit information. The inspection determination processing unit 12d is connected to the connection part 10b between the component 10a and the substrate 10 based on the connection shape of the connection part 10b between the component 10a and the substrate 10 on the target surface (see FIG. 10) acquired by the image processing unit 12e. It is comprised so that the inspection of the state may be performed. Specifically, the inspection determination processing unit 12d determines the dimensions of the connection shape (the length in the longitudinal direction and the short direction of the solder 10d) of the connection portion 10b between the component 10a and the substrate 10 and the transmission of X-rays in the solder portion. The amount (the color density of the image) is measured, and the connection state of the connection unit 10b is inspected.

  Here, in the first embodiment, the image processing unit 12 e is configured to irradiate the substrate 10 with X-rays from the X-ray source 3 and to capture an X-ray image with the X-ray imaging unit 4. Specifically, as shown in FIG. 6, the image processing unit 12 e irradiates X-rays from the X-ray source 3 from the side (Z1 direction) that intersects the surface of the substrate 10 substantially perpendicularly. The line imaging unit 4 is configured to capture a planar image of the substrate 10. Further, as shown in FIG. 7, the image processing unit 12e irradiates the surface of the substrate 10 with X-rays from the X-ray source 3 from the direction of the angle α (in the oblique upward direction) upward (Z1 direction), The X-ray imaging unit 4 is configured to capture an X-ray image of the substrate 10. Further, when the image processing unit 12e shoots an image by irradiating X-rays from an obliquely upward direction, as shown in FIG. 8, in the plan view, 45 degrees, 78 degrees, 123 degrees, and 135 degrees with respect to the X1 direction. The X-ray source 3 emits X-rays from eight directions of 225 degrees, 258 degrees, 303 degrees, and 315 degrees, and the X-ray imaging unit 4 captures an X-ray image of the substrate 10.

  As shown in FIG. 9, the component 10 a (for example, QFP) has a substantially rectangular shape in plan view, and is arranged so that the sides extend in the X direction and the Y direction with respect to the substrate 10. Further, the lead 10c is provided so as to extend in the Y direction from two sides extending in the X direction of the component 10a, and the lead 10c is provided so as to extend in the X direction from two sides extending in the Y direction of the component 10a. It has been. Further, the lead 10c of the component 10a is fixed to the substrate 10 with solder 10d (see FIG. 10) at the connection portion 10b. Thereby, with respect to the lead 10c extending in the Y direction in plan view, the target surface including both the lead 10c and the solder 10d in the connection portion 10b to be inspected is a surface perpendicular to the surface of the substrate 10, and It is possible to set a surface extending in the Y direction (direction of 90 degrees with respect to the X1 direction). In addition, with respect to the lead 10c extending in the X direction in plan view, the target surface including both the lead 10c and the solder 10d in the connection portion 10b to be inspected is a surface perpendicular to the surface of the substrate 10 and X It is possible to set a surface extending in a direction (a direction of 0 degrees with respect to the X1 direction). By setting the target surface in this way, the direction of X-ray irradiation when capturing an X-ray image (45 degrees, 78 degrees, 123 degrees, 135 degrees, 225 degrees, 258 degrees, 303 degrees with respect to the X1 direction). 8 directions (degrees and 315 degrees) is a direction that intersects (is not parallel to) any of the plurality of target surfaces with respect to the plurality of leads 10c.

  In the first embodiment, the image processing unit 12e converts the X-ray image on the captured imaging surface (projection surface) into an image of the target surface, thereby connecting the component 10a and the substrate 10 on the target surface. The connection shape 10b (see FIG. 12) is calculated (acquired). Here, as shown in FIG. 10, when an X-ray image is captured by the X-ray imaging unit 4 by irradiating X-rays from a direction that is not parallel to the target surface that intersects the surface of the substrate 10 substantially perpendicularly, a projection plane is obtained. The image taken in is taken as an X-ray image. As shown in FIG. 11, in the xyz coordinate system, the xy plane is a projection plane (captured X-ray image), and the point P (x1, y1, 0) on the projected xy plane is perpendicular to the xy plane. A method for calculating the point Q (x2, y2, z2) on the target surface by coordinate transformation will be described. X-rays are irradiated from the direction of angle α (for example, 45 degrees) with respect to the xy plane. X-rays are emitted in the direction of angle β with respect to the positive x-axis direction. Therefore, x1 and y1 of the point P are expressed as in Expression (1) and Expression (2). Further, since the target surface is a surface perpendicular to the xy plane, it is expressed as Expression (3).

なお、ａおよびｂは、接続部１０ｂにおけるリード１０ｃの平面位置に基づいて算出される。対象面がｘ軸と平行であればａ＝０となり、対象面がｙ軸と平行であればｂ＝０となる。また、点Ｑは、対象面上の点なので、点Ｑの座標を式（３）に代入すると、式（４）が導かれる。

In addition, a and b are calculated based on the planar position of the lead 10c in the connecting portion 10b. If the target surface is parallel to the x axis, a = 0, and if the target surface is parallel to the y axis, b = 0. Further, since the point Q is a point on the target surface, when the coordinates of the point Q are substituted into the equation (3), the equation (4) is derived.

  When a matrix is used to solve Equation (1), Equation (2), and Equation (4) simultaneously, Equation (5) is derived.

  Here, the determinant D of the matrix of Expression (5) is as shown in Expression (6). When D ≠ 0, the simultaneous equations have solutions. That is, the simultaneous equations have solutions when the target surface represented by the equation (3) and the X-ray irradiation direction are not parallel. When D ≠ 0, Equation (7) is derived by applying an inverse matrix from the left side of both sides of Equation (5) to obtain the coordinates of the point Q on the target surface.

  The image processing unit 12e calculates the coordinates on the target surface from the projection points of the X-ray image projected by the connection unit 10b as described above, and acquires the X-ray transmission point on the target surface of the connection unit 10b. The image processing unit 12e calculates coordinates on the target surface for all projection points corresponding to the X-ray image connection unit 10b, and calculates (acquires) a cross-sectional image on the target surface of the connection unit 10b.

  Further, as shown in FIG. 12, the image processing unit 12e has a plurality of directions of angle β1, angle β2, angle β3, angle β4... With respect to the X1 direction (45 degrees, 78 degrees, 123 degrees with respect to the X1 direction). , 135 degrees, 225 degrees, 258 degrees, 303 degrees, and 315 degrees) from the plurality of X-ray images captured by the X-ray imaging unit 4 by irradiating the X-ray from the X-ray source 3 respectively. Calculate (acquire) a cross-sectional image of the target surface 10b. In addition, since X-rays are irradiated and imaged from different directions with respect to the X1 direction, the shapes of the lead 10c and the solder 10d in the connection portion 10b of the plurality of X-ray images are different from each other in the plurality of X-ray images. In addition, the shape and position of the obstacle 10e reflected in the plurality of X-ray images are also different from each other in the plurality of X-ray images. In addition, since the lead 10c and the solder 10d in the connection portions 10b of the plurality of cross-sectional images are calculated on the same target surface, they have the same shape. On the other hand, since the obstacle 10e reflected in the plurality of cross-sectional images does not exist on the same target surface, the shapes and positions of the plurality of cross-sectional images are different from each other.

  Further, as shown in FIG. 12, the image processing unit 12e is configured to obstruct obstacles based on a plurality of cross-sectional images of the connection unit 10b on the target surface calculated from X-ray images captured by irradiating X-rays from a plurality of directions. 10e is removed to obtain a composite image. Specifically, the image processing unit 12e compares the calculated X-ray transmission amounts of the plurality of cross-sectional images, and selects (extracts) a portion with a larger X-ray transmission amount (a portion with a lighter color). By combining them, the obstacle 10e in the cross-sectional image is removed. If there is the obstacle 10e, the amount of X-ray transmission is smaller than the other, so that the color of the image becomes darker. The obstacle 10e is an example of “noise” in the present invention.

  The image processing unit 12 e is configured to irradiate the substrate 10 with light (visible light) from the light 52 of the optical imaging unit 5 and to capture an optical image with the camera 51.

  The apparatus control arithmetic processing unit 12f (see FIG. 4) is configured to read out information related to the specifications of the X-ray inspection apparatus 100 from the equipment specific data storage unit 12g and to control the entire X-ray inspection apparatus 100. . The device control arithmetic processing unit 12f is configured to perform control for driving a drive motor or the like via the motor control unit 12h. In addition, the apparatus control arithmetic processing unit 12f accepts an operation by a user from an external input / output device (not shown) via the external input / output control unit 12i, and the X-ray inspection apparatus 100 performs the operation based on the user's operation. It is configured to perform control.

  Next, with reference to FIG. 5, the control of the substrate inspection process by the controller 12 of the X-ray inspection apparatus 100 will be described. The board inspection by the X-ray inspection apparatus 100 is performed as part of a process for manufacturing a mounting circuit board for an electronic component (component 10a) while the board 10 is being transported by a transport line.

  When the user starts the board manufacturing operation, in step S1, the controller 12 reads a program necessary for the inspection of the program storage unit 12c. In addition, the controller 12 reads information such as the size and position of the board 10 and the component 10a to be inspected from the program storage unit 12c. In step S2, the controller 12 reads the number N of examination sites. Specifically, the controller 12 reads the number of visual fields necessary for the inspection based on the substrate data. For example, when the part 10a mounted on the substrate 10 shown in FIG. 9 is inspected, when the field of view is divided into four parts, N = 4.

  In step S <b> 3, the controller 12 carries in the substrate 10. Specifically, after opening the shutter unit 9, the controller 12 moves the conveyor 21 to the carry-in entrance A to receive and carry in the substrate 10. In step S4, the controller 12 sets J = 1 in order to perform imaging and examination of the first field of view of the examination site. In step S5, the controller 12 captures nine X-ray images. Specifically, the controller 12 is a single plane that images (see FIG. 6) by irradiating X-rays from the X-ray source 3 from the side (Z1 direction) that intersects the surface of the substrate 10 substantially perpendicularly. An image and a direction (diagonally upward direction) (see FIG. 7) at an angle α (for example, 45 degrees) upward (Z1 direction) with respect to the surface of the substrate 10, and 45 degrees with respect to the X1 direction in plan view, The X-ray source 3 irradiates X-rays from eight directions of 78 degrees, 123 degrees, 135 degrees, 225 degrees, 258 degrees, 303 degrees, and 315 degrees (see FIG. 8) and images eight images. .

  In step S6, the controller 12 acquires the height position (position in the Z direction) of the lead 10c of the component 10a to be inspected. Specifically, the controller 12 determines the height position of the lead 10c of the component 10a from the position of the lead 10c and the height position of the surface of the substrate 10 of the eight X-ray images captured by irradiating X-rays from obliquely above. (Position in Z direction) is acquired. In step S7, the controller 12 calculates (acquires) eight cross-sectional images. Specifically, the controller 12 is a position in plan view of the lead 10c of the connecting portion 10b to be inspected based on a planar image captured by irradiating X-rays from a direction substantially perpendicular to the surface of the substrate 10 (directly above). And a plane parallel to the Z direction in the direction in which the lead 10c extends in the plane (XY plane) direction is specified as the target plane. Thereafter, the controller 12 performs eight cross sections of the connection portion 10b between the component 10a and the substrate 10 on the target surface based on the target surface and the eight X-ray images captured by irradiating X-rays from obliquely above. Each image is calculated.

  In step S8, the controller 12 synthesizes a composite image from the eight cross-sectional images as shown in FIG. Thereby, the controller 12 acquires one composite image from which the obstacle 10e of the cross-sectional image on the target surface is removed. In step S9, the controller 12 performs a dimensional inspection. Specifically, the controller 12 measures the dimensions of the connection shape of the connection portion 10b between the component 10a and the substrate 10 (the length in the longitudinal direction and the short direction of the solder 10d) and the X-ray transmission amount (image) of the solder portion. Is measured from the composite image, and the connection state of the connection portion 10b is inspected.

  In step S10, the controller 12 records the inspection result. This completes the process of imaging and inspecting the first field of view of the examination site. Next, in step S11, the control unit sets J = J + 1. In step S12, the controller 12 determines whether J is greater than N. That is, it is determined whether imaging and inspection for the number of visual fields necessary for the inspection are completed. If J is N or less, the process returns to step S5. If J is greater than N, the process proceeds to step S13.

  In step S <b> 13, the controller 12 discharges the substrate 10. Specifically, after opening the shutter unit 9, the controller 12 moves the conveyor 21 to the carry-out port B and carries out the substrate 10. Then, it returns to step S3.

  In the first embodiment, as described above, the controller 12 is imaged by irradiating X-rays from a direction intersecting a target surface that includes the target connection portion 10b and intersects the surface of the substrate 10 substantially perpendicularly. By converting the image on the imaging surface (projection surface) to the image of the target surface, the surface of the substrate 10 is configured to acquire the connection shape of the connection portion 10b between the component 10a and the substrate 10 on the target surface. Based on the connection shape of the connection portion 10b between the component 10a and the substrate 10 on the target surface that intersects the substrate 10 substantially vertically, the change in the connection shape of the connection portion 10b in the direction substantially perpendicular to the surface of the substrate 10 is accurate. I can grasp it well. Thereby, the state of the connection portion 10b between the component 10a and the substrate 10 in a direction substantially perpendicular to the surface of the substrate 10 can be accurately inspected with a small number of images.

  In the first embodiment, the controller 12 acquires a cross-sectional image of the connection portion 10b on the target surface that intersects the surface of the substrate 10 substantially perpendicularly based on the captured image, thereby connecting the connection shape of the connection portion 10b. By using the cross-sectional image of the connection part 10b on the acquired target surface, the component 10a and the connection part 10b of the connection part 10b in the direction intersecting substantially perpendicularly to the surface of the board 10 are obtained. The state can be easily and accurately inspected.

  In the first embodiment, the controller 12 synthesizes a plurality of images picked up by irradiating X-rays from eight directions intersecting the target surface, so that the target surface intersects the surface of the substrate 10 substantially perpendicularly. By removing the obstacle 10e from the cross-sectional image of the connecting portion 10b and acquiring the connection shape of the connecting portion 10b, a portion without the obstacle 10e can be extracted from a plurality of images and synthesized. The obstacle 10e in the cross-sectional image on the target surface can be easily removed. Thereby, the state of the connection portion 10b between the component 10a and the substrate 10 can be inspected with higher accuracy.

  In the first embodiment, the controller 12 compares the X-ray transmission amounts of the eight images and synthesizes the portion where the X-ray transmission amount is large, thereby obstructing the obstacle in the cross-sectional image on the target surface. By configuring so as to remove the object 10e, the obstacle 10e that reduces the amount of X-ray transmission is removed by synthesizing eight images, so that the obstacle 10e in the cross-sectional image on the target surface can be more easily removed. Can be removed.

  Further, in the first embodiment, the position of the controller 12 in the plan view of the connection unit 10b is determined based on the plane image obtained by imaging the substrate 10 by the X-ray imaging unit 4 from the direction that intersects the surface of the substrate 10 substantially perpendicularly. By acquiring the signal, the target surface including the connecting portion 10b is specified, so that the target surface that intersects the surface of the substrate 10 substantially perpendicularly based on the planar image captured by the X-ray imaging unit 4 can be easily obtained. Can be identified. Further, even when the connection part 10b is hidden behind the component 10a or the like and cannot be seen, the connection part 10b can be confirmed by the transmitted X-rays, so that the target surface including the connection part 10b can be reliably identified.

  Moreover, in 1st Embodiment, the controller 12 is comprised with respect to the surface of the board | substrate 10 by comprising so that the state of the connection part 10b may be test | inspected based on the dimension of the connection shape of the connection part 10b in an object surface. The state of the connection portion 10b between the component 10a and the substrate 10 in a direction that intersects substantially vertically can be inspected quantitatively and accurately based on the dimensions of the connection shape.

  In the first embodiment, the controller 12 irradiates X-rays from the X-ray source 3 from a direction that is not parallel to any of the plurality of target surfaces including the target connection unit 10 b and causes the X-ray imaging unit 4 to display an image. By configuring so as to capture an image, it is possible to acquire more connection shapes on the target surface of the connection unit 10b with a single imaging by the X-ray imaging unit 4, and thus individually acquire the connection shape of the connection unit 10b. The number of X-ray irradiations can be reduced as compared with the case of doing so.

  Further, in the first embodiment, the controller 12 is configured to irradiate X-rays from the X-ray source 3 from eight directions intersecting the target surface and to capture an image by the X-ray imaging unit 4, so that multidirectional The cross-sectional image of the connecting portion 10b on the target surface with high accuracy can be acquired based on the image picked up by irradiating X-rays. In addition, the number of times of X-ray irradiation can be reduced as compared with CT (Computer Tomography) that irradiates many X-rays for imaging one image. Thereby, since the burden of X-ray source 3 can be made small, the lifetime of X-ray source 3 can be lengthened.

(Second Embodiment)
Next, the configuration of the X-ray inspection apparatus 100 according to the second embodiment of the present invention will be described with reference to FIG. In the second embodiment, unlike the first embodiment in which the target surface is specified based on an X-ray image captured by irradiating X-rays from a direction substantially perpendicular to the surface of the substrate 10 (directly above), the substrate An example in which a target surface is specified based on an optical image captured by irradiating light (visible light) from a direction substantially perpendicular to the surface of 10 (directly above) will be described.

  Here, in the second embodiment, after setting J = 1 in step S4 of FIG. 13, the controller 12 captures one optical image in step S21. Specifically, the controller 12 irradiates visible light from the light 52 (see FIG. 4) of the optical imaging unit 5 from the direction (Z1 direction) that intersects the surface of the substrate 10 substantially perpendicularly (Z1 direction). A planar image of the substrate 10 is picked up by the five cameras 51. In step S22, the controller 12 captures eight X-ray images. Specifically, the controller 12 is directed upward (Z1 direction) with respect to the surface of the substrate 10 in an angle α (for example, 45 degrees) direction (obliquely upward direction) (see FIG. 7), and in the plan view, the X1 direction. X-rays are emitted from the X-ray source 3 from eight directions of 45 degrees, 78 degrees, 123 degrees, 135 degrees, 225 degrees, 258 degrees, 303 degrees and 315 degrees (see FIG. 8). Take a line image. Then, it progresses to step S6.

  In the second embodiment, the controller 12 obtains the height position (position in the Z direction) of the lead 10c of the component 10a to be inspected in step S6, and then calculates eight cross-sectional images in step S23 ( get. Specifically, the controller 12 is a position in plan view of the lead 10c of the connecting portion 10b that is inspected based on a planar image captured by irradiating visible light from a direction substantially perpendicular to the surface of the substrate 10 (directly above). And a plane parallel to the Z direction in the direction in which the lead 10c extends in the plane (XY plane) direction is specified as the target plane. Thereafter, the controller 12 performs eight cross sections of the connection portion 10b between the component 10a and the substrate 10 on the target surface based on the target surface and the eight X-ray images captured by irradiating X-rays from obliquely above. Calculate the image. Then, the process proceeds to step S8.

  In addition, the other structure of 2nd Embodiment is the same as that of the said 1st Embodiment.

  As described above, also in the configuration of the second embodiment, as in the first embodiment, it is possible to accurately grasp the change in the connection shape of the connection portion 10b in the direction intersecting the surface of the substrate 10. Therefore, the state of the connection portion 10b between the component 10a and the substrate 10 in the direction intersecting the surface of the substrate 10 can be accurately inspected with a small number of images.

  Furthermore, in the second embodiment, as described above, the controller 12 is connected to the connection unit 10b based on a planar image obtained by imaging the substrate 10 by the optical imaging unit 5 from a direction substantially perpendicular to the surface of the substrate 10. By configuring the target surface including the connection unit 10b by acquiring the position in plan view, the target surface that intersects the surface of the substrate 10 based on the planar image captured by the optical imaging unit 5 can be easily obtained. Can be identified.

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first and second embodiments, the example in which the present invention is applied to the X-ray inspection apparatus constituting the circuit board production line is shown, but the present invention is not limited to this. For example, the present invention may be applied to an X-ray inspection apparatus that is provided outside a circuit board production line and is used alone.

  In the first and second embodiments, the X-ray inspection apparatus includes an X-ray source, an X-ray imaging unit, and an optical imaging unit. However, the present invention is not limited to this. In the present invention, the X-ray inspection apparatus may not include an optical imaging unit.

  Further, in the first and second embodiments, eight directions of 45 degrees, 78 degrees, 123 degrees, 135 degrees, 225 degrees, 258 degrees, 303 degrees, and 315 degrees with respect to the X1 direction in plan view (FIG. 8). In the above example, the X-ray source irradiates X-rays to capture eight X-ray images, but the present invention is not limited to this. In the present invention, X-rays are irradiated from eight directions other than 45 degrees, 78 degrees, 123 degrees, 135 degrees, 225 degrees, 258 degrees, 303 degrees and 315 degrees with respect to the X1 direction, and eight X-ray images are obtained. X-ray images may be taken by irradiating X-rays from nine or more directions or seven or less directions (for example, four directions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees with respect to the X1 direction). May be imaged. In this case, it is preferable to irradiate X-rays from a direction intersecting a plurality of target surfaces.

  In the first and second embodiments, the example in which the target surface is specified based on the X-ray image or the optical image captured from the substantially vertical direction with respect to the surface of the substrate has been described. However, the present invention is not limited to this. I can't. In the present invention, the target surface may be specified based on data such as preset positions and sizes of the board and components.

  In the first and second embodiments, an example of a configuration in which X-rays irradiated to the substrate from the X-ray source are directly imaged by the X-ray imaging unit is shown, but the present invention is not limited to this. In the present invention, X-rays irradiated onto the substrate from the X-ray source may be irradiated with a scintillator or the like to emit light, and the emitted scintillator may be imaged by the imaging unit.

  In the first and second embodiments, for convenience of explanation, the processing operation of the controller as the control unit has been described using a flow-driven flowchart that performs processing in order along the processing flow. It is not limited to this. In the present invention, the processing operation of the control unit may be performed by event-driven (event-driven) processing that executes processing in units of events. In this case, it may be performed by a complete event drive type or a combination of event drive and flow drive.

Claims (20)

An X-ray source (3) for irradiating the substrate (10) on which the component (10a) is mounted with X-rays;
An X-ray imaging unit (4) that captures an image based on the X-rays applied to the substrate;
A control unit (12) for inspecting the state of the connection part (10b) between the component and the board;
The control unit is a direction that intersects a target surface that includes the connection unit as a target and intersects the surface of the substrate , and is imaged by irradiating X-rays from an obliquely upward direction of the target surface . It is configured to acquire a connection shape of the connection portion between the component and the substrate on the target surface by performing coordinate conversion of the image on the imaging surface intersecting the target surface into an image of the target surface. X-ray inspection equipment.   The control unit is configured to acquire a connection shape of the connection unit by acquiring a cross-sectional image of the connection unit on the target surface intersecting the surface of the substrate based on the captured image. The X-ray inspection apparatus according to claim 1.   The X-ray inspection apparatus according to claim 1, wherein the control unit is configured to acquire a connection shape of the connection unit on the target surface that intersects the surface of the substrate substantially perpendicularly.   The X-ray inspection apparatus according to claim 1, wherein the target surface is a surface including a lead (10c) and solder (10d) provided on the component.   The control unit is configured to generate a noise of a cross-sectional image of the connection portion on the target surface that intersects the surface of the substrate based on the plurality of images captured by irradiating X-rays from a plurality of directions intersecting the target surface. The X-ray inspection apparatus according to claim 1, wherein the X-ray inspection apparatus is configured to acquire (10e) and obtain a connection shape of the connection portion.   The said control part is comprised so that the noise of the said cross-sectional image in the said target surface may be removed and the connection shape of the said connection part may be acquired by synthesize | combining these several images. X-ray inspection equipment.   The control unit compares X-ray transmission amounts of the plurality of images and synthesizes a portion having a large X-ray transmission amount, thereby obstructing an obstacle (as noise in the cross-sectional image on the target surface) ( The X-ray inspection apparatus according to claim 5, configured to remove 10 e).   The control unit is configured to identify the target surface based on a planar image obtained by imaging the substrate by an X-ray imaging unit from a direction substantially perpendicular to the surface of the substrate. X-ray inspection apparatus described in 1.   The control unit is configured to identify the target surface including the connection unit by acquiring a position of the connection unit in plan view based on the planar image captured by the X-ray imaging unit. The X-ray inspection apparatus according to claim 8. An optical imaging unit (5) for imaging the substrate with visible light;
The said control part is comprised so that the said target surface may be specified based on the plane image which imaged the said board | substrate with the said optical imaging part from the direction which cross | intersects substantially perpendicular | vertical with respect to the surface of the said board | substrate. X-ray inspection apparatus described in 1.   The said control part is comprised so that the said target surface containing the said connection part may be specified by acquiring the position in the planar view of the said connection part based on the said planar image imaged by the said optical imaging part. Item 11. The X-ray inspection apparatus according to Item 10.   The X-ray inspection apparatus according to claim 1, wherein the control unit is configured to inspect a state of the connection portion based on a dimension of a connection shape of the connection portion on the target surface. The component and the substrate are connected by a plurality of the connection portions,
The control unit is configured to irradiate X-rays from an X-ray source from a direction that is not parallel to any of the plurality of target surfaces including the target connection unit, and to capture the image by the X-ray imaging unit. The X-ray inspection apparatus according to claim 1.   2. The control unit according to claim 1, wherein the control unit is configured to irradiate X-rays from an X-ray source from four or eight directions intersecting the target surface and to capture the image by an X-ray imaging unit. X-ray inspection equipment. Irradiating the substrate (10) on which the component (10a) is mounted with X-rays;
Capturing an image based on X-rays applied to the substrate;
A step of inspecting a state of a connection portion (10b) between the component and the substrate,
The step of inspecting the state of the connection portion is a direction intersecting a target surface that includes the connection portion as a target and intersects the surface of the substrate , and is X- rayed from an obliquely upward direction of the target surface. The connection shape of the connection portion of the component and the substrate on the target surface is acquired by performing coordinate conversion of the image on the imaging surface that intersects the target surface captured by irradiating the image to the image of the target surface An X-ray inspection method including a process.   The step of inspecting the state of the connection portion acquires the connection shape of the connection portion by acquiring a cross-sectional image of the connection portion on the target surface intersecting the surface of the substrate based on the captured image. The X-ray inspection method according to claim 15, comprising a step of:   The X-ray according to claim 15, wherein the step of inspecting the state of the connection portion includes a step of obtaining a connection shape of the connection portion on the target surface that intersects the surface of the substrate substantially perpendicularly. Inspection method.   16. The X-ray inspection method according to claim 15, wherein the target surface is a surface including a lead (10c) and solder (10d) provided on the component.   The step of inspecting the state of the connecting portion includes the connection on the target surface intersecting the surface of the substrate based on the plurality of images captured by irradiating X-rays from a plurality of directions intersecting the target surface. The X-ray inspection method according to claim 15, further comprising a step of removing a noise (10e) in a cross-sectional image of a portion to acquire a connection shape of the connection portion.   The step of inspecting the state of the connection portion includes a step of obtaining a connection shape of the connection portion by combining the plurality of images to remove noise of the cross-sectional image on the target surface. X-ray inspection method described in 1.

Images