JP2006177760A - X-ray inspection apparatus, X-ray inspection method, and X-ray inspection program - Google Patents

Abstract

PROBLEM TO BE SOLVED To inspect a large number of inspection objects at high speed.
In inspecting an inspection object by X-rays, X-rays are output from a fixedly arranged X-ray source to a predetermined solid angle range, and a plurality of inspection objects arranged in a plane are arranged as described above. A detector having a detection surface inclined with respect to an axis perpendicular to the plane of movement of the inspection object while moving in a plane within the X-ray output range and changing the position of the inspection object An X-ray image acquired by a plurality of detectors arranged at a plurality of positions included in the solid angle and acquired by a different detector from the acquired plurality of X-ray images. A plurality of X-ray images including the same inspection target product are extracted, and the inspection target product is inspected based on these X-ray images.
[Selection] Figure 1

Description

  The present invention relates to an X-ray inspection apparatus, an X-ray inspection method, and an X-ray inspection program.

Conventionally, the quality of an inspection target product is determined by irradiating the inspection target product with X-rays and analyzing the obtained transmission image (see, for example, Patent Document 1). In this document, a θ table is disposed on an XY stage, an X-ray source and a camera are rotated in a plane orthogonal to the XY stage (Patent Document 1, FIG. 1), and XY. A technique (Patent Document 1 and FIG. 2) for rotating an X-ray source and a camera around an axis orthogonal to the stage is disclosed.
JP 2000-356606 A

  In the conventional X-ray inspection apparatus described above, it has been difficult to inspect a large number of inspection objects at high speed. That is, in order to inspect the inspection target product in detail, it is necessary to acquire a plurality of X-ray images obtained by photographing the inspection target product from different directions, and to perform an appearance inspection and a three-dimensional structure analysis. In the conventional technique, in order to photograph the inspection target product from different directions, the inspection target product is arranged at a predetermined position, and the X-ray source and the camera are rotated. The process of arranging the products one by one at a predetermined position and taking a plurality of shots from different directions was repeated. Therefore, it takes a very long time to inspect a large number of inspection objects such as a large number of solder bumps connecting the IC chips.

  Also, since the X-ray source normally generates X-rays using a high voltage, the apparatus becomes large and heavy. Thus, in order to move a large and heavy X-ray source, a large-scale apparatus is required and much time is required to complete the movement. Therefore, in the conventional method of inspecting the inspection target products one by one, the time loss due to the movement of the X-ray source or the like increases as the number of the inspection target products increases, and high-speed inspection cannot be performed.

It should be noted that it is extremely important to implement a large number of products to be inspected at high speed in the case where all parts are inspected. In other words, it is not sufficient to conduct sampling surveys on some parts, such as automobile mounted parts, and for products that require 100% inspection, the production efficiency will decrease unless the inspection target product is inspected at high speed. End up.
The present invention has been made in view of the above problems, and an object thereof is to provide an X-ray inspection apparatus, an X-ray inspection method, and an X-ray inspection program capable of inspecting a large number of inspection objects at high speed.

  In order to achieve the above object, according to the first aspect of the present invention, a plurality of X-ray images are acquired while changing the position of the inspection object, and X-ray images acquired by different detectors are the same inspection object. A plurality of X-ray images including are extracted. Since these X-ray images are obtained by photographing X-ray images from different directions for the same inspection target product, the inspection target product can be obtained by inspecting the inspection target product based on these X-ray images. Can be inspected in detail.

  That is, the plane moving means moves the inspection object so that the inspection object is arranged in the field of view of the detector when acquiring the X-ray image. In the present invention, only the specific inspection object is moved. Instead of moving by a plane moving means to take an image with a specific detector, a plurality of inspection objects are moved to be imaged by any or all of the plurality of detectors. Accordingly, an X-ray image of a certain inspection object is acquired by a certain detector, and at the same time, an X-ray image of another inspection object is acquired by another detector. By repeating this, it is possible to acquire X-ray images taken from different directions for a specific inspection object.

  Therefore, if an X-ray image taken from a different direction for a specific inspection target product is extracted and analyzed by the target product inspection means, the specific inspection target product can be analyzed in detail. Further, in the above configuration, since one X-ray image is not acquired by one imaging operation, but a plurality of X-ray images are acquired by one imaging operation, X-ray images are efficiently acquired. The data can be collected and the inspection can be performed at high speed.

  Further, in the present invention, an X-ray source that outputs X-rays in a predetermined solid angle range is fixedly arranged, and the inspection target product is moved in a plane within the solid angle range to obtain an X-ray image. Take a picture. Therefore, in the present invention, an X-ray image of a product to be inspected can be acquired without moving a large and heavy X-ray source, and inspection can be performed at high speed.

  Here, the X-ray output means is not limited as long as the X-ray source is fixedly arranged and can output X-rays within a predetermined solid angle range. The X-ray source may be configured so as not to move when inspecting the inspection target product, and may be installed so as not to move relative to the floor or the inspection line when the X-ray inspection apparatus is installed in a factory or the like. . The X-ray output range may be a range that includes the detection surfaces of a plurality of detectors in the X-ray image acquisition means. That is, an X-ray source is used for taking an X-ray image by using an X-ray tube that irradiates a wide range of X-rays instead of using an X-ray tube with a limited irradiation range that has been conventionally used. It suffices to be able to prevent the angle from changing or moving.

  As such an X-ray source, for example, a transmission type open tube may be employed. That is, in a transmissive open tube, X-rays are generated by electrons colliding with a thin target, and almost all directions (solid angle 2π) are within the output range when the X-rays pass through the target and are output to the outside. Become. Of course, in most cases, the solid angle 2π is not necessary as an irradiation range for imaging the object to be inspected, and an X-ray source that irradiates X-rays with solid angles including at least the detection surfaces at the plurality of positions may be employed. However, the larger the solid angle, the more products to be inspected to which the present invention can be applied, and the versatility becomes higher.

  The plane moving means only needs to be able to move the inspection object two-dimensionally, and can be constituted by a so-called XY stage or the like. In the present invention, since there is no need to rotate the inspection target product, the X-ray source and the inspection target product can be brought close to each other. Therefore, it is possible to easily acquire an X-ray image having a large magnification on the detection surface of the X-ray image acquiring means, and it is possible to perform a highly accurate inspection.

  In the X-ray image acquisition unit, it is only necessary that the X-rays output from the X-ray output unit and the X-rays transmitted through the inspection object can be acquired on a detection surface at a plurality of positions. As these detection means, for example, a sensor that measures the intensity of X-rays using a two-dimensionally arranged CCD can be employed. The detection surface may be inclined at a predetermined angle with respect to an axis perpendicular to the plane of movement of the inspection target product, as long as the inclination angle is determined so as to face the focal point of the X-ray source. .

  For inspection by the target product inspection means, the cross-sectional area, volume, shape, presence / absence of bridges in soldering, etc. are inspected based on the transmission image, or reconstruction operation is performed based on multiple transmission images. Various configurations such as calculating an image and determining pass / fail such as soldering can be employed. In addition, when acquiring a plurality of transmission images for the inspection target product and performing the reconstruction calculation, the configuration of the present invention is not adopted, and the configuration in which one inspection target product is sequentially moved to the field of view of a plurality of detectors is adopted. Then, since the inspection time becomes very long, if the present invention is applied to a configuration in which a reconstruction operation is performed and a tomogram is analyzed, the effect of reducing the inspection time is further increased.

  If a plurality of X-ray images taken from different directions are used, the above-described reconstruction calculation can be performed. However, when this reconstruction calculation is performed, a predetermined symmetry with respect to the inspection target product is obtained. It is preferable to take an X-ray image from a position having For example, the detection surface may be disposed at a position (hereinafter referred to as a rotation position) assuming that the detection surface is rotated about an axis perpendicular to the moving plane of the inspection target product. More specifically, a straight line connecting the focal point of the X-ray source and the center of the X-ray irradiation range is used as an axis, and the rotational position may be assumed on the circumference of a predetermined radius centered on this axis.

  As described above, if the detection surfaces are arranged at a plurality of rotational positions, the inspection object can be photographed from a rotationally symmetric position, and three-dimensional in consideration of the rotational symmetry of the photographed X-ray image. It becomes possible to analyze the structure. In this configuration, X-ray images are acquired at a plurality of rotational positions, but the inspection target product is not rotated in order to acquire X-ray images. Accordingly, it is possible to inspect the inspection object by simply moving the inspection object in a plane with a simple configuration, and the processing can be performed at high speed even when inspecting a large number of inspection objects. .

  In the present invention, the efficiency of imaging processing is improved by acquiring a plurality of X-ray images by a single imaging operation, thereby increasing the inspection speed. For this purpose, a configuration in which the visual field size of the detector is set to a unit moving amount by the plane moving means is preferable. That is, the inspection is performed while moving by the unit moving amount by the plane moving unit, and this unit moving amount is set to the length in the moving direction of the region included in the field of view of the detector.

  According to this configuration, each time the plane is moved by the plane moving means, the area included in the field of view of the detector is switched within the plane of movement of the inspection object, and the area adjacent to this area is The area that was outside is included in the field of view. Therefore, when a plurality of inspection target products exist over an area exceeding the field of view of one detector, it is possible to efficiently image all the inspection target products by a small number of movements. Of course, at the time when the imaging of all the inspection target products is completed by one detector, the imaging of all the inspection target products is not necessarily completed by other detectors, but a plurality of detections are performed at least for one imaging. If the inspection object can be photographed with the detector, the photographing work can be made more efficient than the case of sequentially photographing with all detectors.

  Furthermore, in order to improve the efficiency of the imaging process by acquiring a plurality of X-ray images by one imaging operation, and thereby to increase the inspection speed, a plurality of inspection objects arranged on a straight line It is particularly preferable to apply the present invention. That is, as in the fourth aspect, the X-ray images can be simultaneously acquired by different detectors with respect to two different ones of the plurality of inspection target products arranged. In this configuration, by moving the inspection object in the direction of the straight line by the plane moving means, X-ray images can be simultaneously acquired by different detectors for two other inspection objects.

  Accordingly, by repeating the imaging of the X-ray image by the X-ray image acquisition means and the movement of the inspection object by the plane moving means, a plurality of X-ray images can be acquired while acquiring at least two X-ray images for each imaging. X-ray images of the inspection target product can be acquired. For this reason, it is possible to efficiently acquire a plurality of X-ray images for a large number of products to be inspected, and to perform inspection at high speed.

  In this configuration, by moving the inspection object in a certain direction, different inspection objects are arranged in the field of view of the plurality of detectors, and by further movement, different inspection objects are again in the field of view of the plurality of detectors. It only needs to be arranged. Therefore, as long as the inspection object can be arranged in the field of view of the detector, the inspection object only needs to be linearly arranged along the moving direction, and it is not essential that the inspection object is strictly aligned. Absent.

  In the present invention, a position sensor may be employed as in claim 5 in order to accurately calculate the unit movement amount. That is, if the relative positional relationship between the focal point in the X-ray output unit and the inspection object is detected by the position sensor, the relative relationship between the detection surface in the X-ray image acquisition unit and the focal point in the X-ray detection unit. From the relationship, the size of the region included in the field of view of the detector can be accurately calculated. If the size of the area can be accurately calculated, the length along the direction in which the inspection target product is moved in the area can be accurately calculated. Therefore, it is possible to accurately carry out movement control in the plane moving means.

  Here, the position sensor only needs to be able to detect the relative positional relationship between the focal point in the X-ray output means and the inspection object, and for example, a distance parallel to the axis vertically upward from the focal point ( The relative positional relationship may be detected by height) or the like. Of course, in addition to the configuration that directly detects the relative positional relationship between the inspection target product and the focal point, the relative positional relationship between the substrate on which the inspection target product is placed and the focal point is detected. The relative positional relationship may be acquired in consideration of the thickness of the substrate or the like, or the thickness of the substrate or the like may be considered negligible.

  In this invention, since the structure which can test | inspect at high speed as mentioned above is employ | adopted, it is preferable to comprise so that an inspection can be implemented in-line in inspection lines, such as a factory. Therefore, as in claim 6, if a transport mechanism that sequentially transports a plurality of products to be inspected to the X-ray output range in the plane moving means, a large number of products to be inspected can be inlined. Become. As a result, it is possible to provide an X-ray inspection apparatus suitable for application to an inspection target product that requires 100% inspection.

  In the present invention, it is also possible to increase the speed by preventing unnecessary inspection. That is, when the inspection result based on the X-ray detected by the parallel X-ray detection means does not satisfy a predetermined standard as in claim 7, the inspection based on the X-rays detected by a plurality of detectors in the X-ray detection means. If it is configured to perform the inspection, inspection is performed with a plurality of X-ray images only when necessary. Therefore, inspection can be performed at high speed.

  Here, it is only necessary to determine whether or not inspection based on a plurality of detectors in the X-ray detection means is unnecessary based on a predetermined criterion. Therefore, as the predetermined standard, either or both of a standard indicating that the inspection target product is clearly a non-defective product and a standard indicating that the inspection target product is clearly a defective product can be employed. More specifically, a standard may be set in advance for the intensity of the X-ray image acquired by the parallel X-ray detection means and the cross-sectional area, volume, and shape of the inspection target product obtained from the X-ray image.

  Although the case where the present invention is realized as an apparatus has been described above, the present invention can also be applied to a method for realizing such an apparatus. As an example, the invention according to claim 8 is configured to realize the method corresponding to claim 1. Of course, the substantial operation is the same as that of the apparatus described above. A method corresponding to claims 2 to 7 can also be configured. Such an X-ray inspection apparatus may be realized by itself, applied to a certain method, or used in a state where the same method is incorporated in another device. Not only this but various aspects are included. Therefore, it can be changed as appropriate, such as software or hardware.

  In the case of software for controlling the above method as an embodiment of the idea of the invention, it naturally exists and is used also on the recording medium on which the software or software is recorded. As an example, the invention according to claim 9 is configured to realize the function corresponding to claim 1 by software. Of course, software corresponding to claims 2 to 7 can also be configured.

  The software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium that will be developed in the future. The duplication stages such as the primary replica and the secondary replica are the same without any question. In addition, even when the communication apparatus is used as the supply device, the present invention is not changed. Further, even when a part is software and a part is realized by hardware, the idea of the invention is not completely different, and a part is stored on a recording medium and is appropriately changed as necessary. It may be in a form that is read.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of the present invention:
(2) X-ray inspection process:
(3) Other embodiments:

(1) Configuration of the present invention:
FIG. 1 is a schematic block diagram of an X-ray inspection apparatus 10 according to the present invention. In this figure, the X-ray inspection apparatus 10 includes an X-ray generator 11, an XY stage 12, X-ray detectors 13 a to 13 d, and a transport device 14, and each part is controlled by a CPU 25. That is, the X-ray inspection apparatus 10 includes an X-ray control mechanism 21, a stage control mechanism 22, an image acquisition mechanism 23, a transport mechanism 24, a CPU 25, an input unit 26, an output unit 27, and a memory 28 as a control system including a CPU 25. Yes. In this configuration, the CPU 25 can execute a program (not shown) recorded in the memory 28, control each unit, and perform predetermined arithmetic processing.

  The memory 28 is a storage medium capable of storing data, and inspection position data 28a and imaging condition data 28b are recorded in advance. The inspection position data 28a is data indicating the position of the product to be inspected, and in the present embodiment, is data indicating the position of the bump disposed on the substrate. The imaging condition data 28b is data indicating conditions when X-rays are generated by the X-ray generator 11, and includes an applied voltage to the X-ray tube, imaging time, and the like. The memory 28 only needs to be able to store data, and various storage media such as a RAM, an EEPROM, and an HDD can be employed.

  The X-ray control mechanism 21 can generate predetermined X-rays by referring to the imaging condition data 28b and controlling the X-ray generator 11. The X-ray generator 11 is a so-called transmissive open tube, and outputs X-rays from the focal point F, which is the output position of the X-rays, in almost all directions, that is, in the range of the solid angle 2π. The X-ray generator 11 is fixedly arranged in the X-ray inspection apparatus 10. That is, the position and angle of the X-ray generator 11 are not changed and are not moved while being fixed in the apparatus.

  The stage control mechanism 22 is connected to the XY stage 12, and controls the XY stage 12 based on the inspection position data 28a. The transport mechanism 24 controls the transport device 14 to transport the substrate 12 a to the XY stage 12. That is, the substrate 12a can be conveyed in one direction by the conveying device 14, the bumps on the substrate 12a can be inspected by the XY stage 12, and the substrate 12a after the inspection can be conveyed by the conveying device 14 continuously. It is configured as follows.

  As described above, the inspection position data 28a specifies the position of the bump on the substrate, and the stage control mechanism 22 moves the substrate 12a by a predetermined unit movement amount when continuously photographing the bump. The XY stage 12 is controlled. That is, the unit movement amount is determined based on one imaging range (field of view) in the X-ray detectors 13a to 13d, and is the length of the region on the substrate 12a included in the field of view, which is XY. The length along the moving direction of the stage 12 is a unit moving amount.

  The image acquisition mechanism 23 is connected to the X-ray detectors 13a to 13d, and acquires X-ray images of the inspection target product based on the detection values output from the X-ray detectors 13a to 13d. The X-ray detectors 13a to 13d in the present embodiment include two-dimensionally distributed sensors, and can generate X-ray image data indicating a two-dimensional X-ray distribution from the detected X-rays. In the present embodiment, when the substrate 12a is disposed at a certain position, bumps may be included in the field of view of the plurality of detectors among the X-ray detectors 13a to 13d. First, X-ray image data is generated by the plurality of detectors.

  The output unit 27 is a display that displays the X-ray image and the like, and the input unit 26 is an operation input device that accepts user input. That is, the user can execute various inputs via the input unit 26, and various calculation results obtained by the processing of the CPU 25, X-ray image data, pass / fail judgment results of the inspection target product, and the like are output to the output unit 27. Can be displayed.

  The CPU 25 can execute predetermined arithmetic processing according to various control programs stored in the memory 28, and in order to inspect the inspection target product, the transport control unit 25a, the X-ray control unit 25b, and the stage control shown in FIG. The calculation in the part 25c, the image acquisition part 25d, and the quality determination part 25e is performed. The transport control unit 25a controls the transport mechanism 24 to supply the substrate 12a to the XY stage 12 at an appropriate timing, and also drives the transport device 14 at an appropriate timing to transfer the inspected substrate 12a to the X-Y stage 12. -Remove from Y stage 12.

  The X-ray control unit 25 b acquires the imaging condition data 28 b and controls the X-ray control mechanism 21 to output predetermined X-rays from the X-ray generator 11. The stage control unit 25 c acquires the inspection position data 28 a, calculates coordinate values for sequentially placing unexposed bumps in the field of view of the X-ray detectors 13 a to 13 d, and supplies the coordinate values to the stage control mechanism 22. As a result, the stage control mechanism 22 moves the XY stage 12 so that this coordinate value is included in any of the visual fields of the X-ray detectors 13a to 13d. The image acquisition unit 25d records the X-ray image data acquired by the image acquisition mechanism 23 in the memory 28. The pass / fail determination unit 25e performs predetermined arithmetic processing based on the recorded X-ray image data, and determines whether the product to be inspected is a good product or a defective product.

(2) X-ray inspection process:
In the present embodiment, the quality of the inspection target product is determined according to the flowchart shown in FIG. In the present embodiment, a large number of substrates 12 a are transported by the transport device 14, and the bumps on the substrate 12 a are sequentially inspected on the XY stage 12. For this reason, at the time of inspection, first, at step S100, the transfer control unit 25a issues an instruction to the transfer mechanism 24, and the transfer device 14 transfers the substrate 12a to be inspected onto the XY stage 12.

  Next, the stage control unit 25c moves the bump to be inspected to an appropriate position. In the present embodiment, a plurality of bumps for connecting the chip to the substrate 12a are provided on the substrate 12a, and the XY stage 12 is controlled in order to sequentially inspect all the bumps.

  FIG. 3 is a diagram showing a relationship between the substrate 12a and the X-ray detector in the present invention, and FIG. 4 is a diagram showing a configuration example of bumps and a unit movement amount. In these figures, the plane of movement by the XY stage 12 is the xy plane, and the direction perpendicular to this plane is the z direction. FIG. 3 is a view of the zx plane, and in the present embodiment, the X-ray detectors 13a to 13d are arranged with reference to the axis A directed vertically upward from the focal point F of the X-ray generator 11. is doing. That is, the X-ray detectors 13a to 13d are arranged so that the center of the detection surface is located on the circumference of the radius R centering on the axis A. The detection surfaces of the X-ray detectors 13a to 13d are oriented so as to be perpendicular to a straight line l connecting the center of each detection surface and the focal point F.

  Specifically, the detection surfaces of the X-ray detectors 13a to 13d are inclined with respect to the axis A, and a predetermined angle (inclination angle) α is given to the xy plane and the detection surface. Further, the X-ray detectors 13a to 13d are arranged such that the distances between adjacent detectors are all the same, and the radius R connecting the axis A and the center of the detection surface is rotated. If the radius R is rotated 90 degrees from the center of a certain detection surface, it coincides with the center of the adjacent detection surface.

  Since the sensors are distributed over a predetermined area on the detection surface arranged in this manner, an X-ray image can be acquired by including a predetermined region of the xy plane in the visual field at a time. That is, the broken line connecting the end of the detection surface and the focal point F is the field of view, and the region FOV having a length L on the substrate 12a shown in FIG. In the present embodiment, the distance between the region FOVs is also a length L, and an X-ray image can be efficiently acquired as will be described later.

  FIG. 4 is an example of bumps arranged on the substrate 12a, and shows a state in which the xy plane is viewed from the z-axis direction. The solid rectangle shown in FIG. 4 indicates the size of the chip connected to the substrate by the bump, and the pass / fail judgment is performed in a state where the chip is connected to the substrate 12a via the bump. In the present embodiment, the direction along the x-axis and the direction along the y-axis shown in the drawing are moving directions of the substrate 12a by the XY stage 12. Also, the broken-line rectangle shown in FIG. 4 is the field of view in the X-ray detectors 13a to 13d, and each of the regions FOVa, FOVb, FOVc, and FOVd corresponds to the field of view of the X-ray detectors 13a to 13d. The length L of one side of FOVa to FOVd corresponds to the unit movement amount.

  That is, in the X-ray detectors 13a to 13d, since the bumps in the region FOV are photographed by one photographing, the length L is used as the unit movement amount when the bumps are moved in the negative direction of the x axis. For example, it is possible to photograph all the bumps arranged in the x-axis direction with the minimum number of photographing times. Further, in order to photograph all the bumps related to the same chip, the movement of the unit movement amount is repeated so that the bumps are scanned by the respective regions FOVa to FOVd. Of course, when the bumps are not included in the field of view of the X-ray detectors 13a to 13d, or after the photographing of the bumps arranged in the x-axis direction is finished, the XY stage 12 is moved by a movement amount different from the unit movement amount. It is possible to make it. In FIG. 4, two areas of the visual field for photographing the bumps are shown. Of course, in the present embodiment, the bumps on the substrate 12 a move, and the visual field area does not move.

  In order to perform imaging as described above, in the present embodiment, the stage control unit 25c moves a bump that is a product to be inspected in steps S105 to S130 shown in FIG. For this purpose, the XY stage 12 is controlled with reference to the inspection position data 28a so that the bumps are arranged at predetermined setting positions (step S105). Here, the set position is a position determined in advance for scanning a plurality of bumps specified by the inspection position data 28a. When scanning in a certain direction, the bump should be arranged first. Position. For example, a process is performed in which the lower left bump shown in FIG. 4 is imaged and then scanned in the x-axis direction, moved in the y-axis direction after scanning in the x-axis direction, and further scanned in the negative x-axis direction. In the case of repetition, the position C1 in FIG. 4 is the first set position, and the position C2 is a set position when scanning is further performed in the negative x-axis direction after the first scan in the x-axis direction is completed.

  When the bump is moved to the set position, X-ray images are taken by the X-ray detectors 13a to 13d under the control of the X-ray control unit 25b and the image acquisition unit 25d (step S110). Here, X-ray images are simultaneously captured by all detectors in which bumps are included in the visual field regions FOVa to FOVd corresponding to the X-ray detectors 13a to 13d, respectively. Needless to say, if the field of view FOVa to FOVd corresponding to each of the X-ray detectors 13a to 13d includes bumps of different chips, and both are inspected products, even if the bumps on both chips are photographed. good.

  In the present embodiment, different inspection objects are simultaneously photographed by different X-ray detectors as described above, so that X-ray images can be acquired efficiently. In any case, when an X-ray image is captured in step S110, the image acquisition unit 25d associates the coordinates indicating the visual field center of the X-ray detectors 13a to 13d that acquired the X-ray image with the X-ray image. Then, it is stored in the memory 28 (step S115). That is, in the present embodiment, since the arrangement of the bumps is determined in advance, if the coordinates indicating the center of the visual field are associated with the X-ray image, it is possible to uniquely identify the bump in the visual field. .

  Next, the stage control unit 25c determines whether or not all the bumps to be inspected have been imaged by the X-ray detectors 13a to 13d (step S120). If it is not determined in step S120 that all the bumps to be inspected have been shot, it is further determined whether or not all the bumps arranged in the same movement direction have been shot (step S125). If it is not determined in step S125 that all the bumps arranged in the same movement direction have been photographed, the stage control unit 25c moves XY so as to move the unit movement amount along this movement direction. The stage 12 is controlled (step S130). And the process after said step S110 is repeated.

  If it is determined in step S125 that all the bumps arranged in the same moving direction have been photographed, the processes in and after step S105 are repeated. That is, the same processing is repeated by moving the substrate 12a so that the bumps are arranged at the setting positions for photographing the unphotographed area. For example, if scanning is performed as in the example described with reference to FIG. 4, all the bumps are photographed by movement parallel to the x-axis direction, and then moved in the x-axis direction and y-axis direction as necessary. Bumps are arranged at predetermined setting positions. Thereafter, X-ray image capturing is repeated while sequentially controlling the XY stage 12 according to the unit movement amount in the x-axis direction.

  If it is determined that all the bumps to be inspected are photographed in step S120 by the above processing, the quality determination unit 25e performs a quality determination process in steps S135 to S150. In the present embodiment, the coordinates of the bumps that are inspection objects are individually specified (step S135). At this time, bumps may be automatically designated in a predetermined order, or a user may designate bumps to be inspected via the input unit 26.

  When the coordinates of individual bumps are designated, the X-ray image data recorded in the memory 28 is referred to, and the bumps of the designated coordinates are determined based on the coordinates of the center of the field of view associated with each X-ray image. An included X-ray image is acquired (step S140). In the present embodiment, four X-ray images captured by each of the X-ray detectors 13a to 13d are acquired. Then, the specified bumps are acquired from the four X-ray images, and pass / fail judgment is performed (step S145).

  Here, it is only necessary to determine whether or not the bump is good. For example, the cross-sectional area, volume, shape, and presence / absence of a bridge in soldering are inspected based on an X-ray image. If the inspection result is good, the bump at the designated coordinate is set as a non-defective product, and if the inspection result is defective, the bump at the specified coordinate is set as a defective product. In the pass / fail judgment, by setting a reference threshold value, a reference shape, etc. in advance in the cross-sectional area, shape, etc., the inspection may be performed automatically, or an X-ray image is displayed on the output unit 27. A visual inspection may be performed.

  In step S150, it is determined whether or not the above quality determination has been completed. If it is not determined that the determination has been completed, step S135 and subsequent steps are repeated. That is, the pass / fail judgment process is repeated by designating the coordinates of the undecided bumps. In step S150, it is only necessary to determine the end of the pass / fail determination based on a predetermined criterion. For example, if a defect is determined for a certain bump, the pass / fail determination is completed based on the fact that a defective product is included at that time, and if all the bumps are determined to be good, the pass / fail determination is ended as a non-defective product. . If it is determined in step S150 that the pass / fail determination has been completed, the inspection has been completed for a product to be inspected on a certain substrate. Therefore, the processes in and after step S100 are repeated to perform inline inspection of the product to be inspected. repeat.

  As described above, in this embodiment, the X-ray generator 11 is fixedly arranged and the position and angle are not changed. In other words, an X-ray generator 11 that outputs X-rays in almost all directions (solid angle 2π) is adopted, and a plurality of X-ray detectors 13a to 13d and the XY stage 12 are combined to form X at a plurality of angles. Line images can be acquired. Therefore, it is not necessary to move the large and heavy X-ray generator 11, and the driving part for acquiring a plurality of X-ray images is only the XY stage 12. As a result, it is possible to inspect a certain inspection object at a very high speed, and it is possible to inspect a large number of inspection objects at a high speed by combining with a mechanism that continuously conveys the inspection object. is there.

  Furthermore, while moving by the XY stage 12, X-ray images of different inspection objects are simultaneously photographed by the plurality of X-ray detectors 13a to 13d, and X-ray images acquired by different detectors are the same. A plurality of X-ray images including the inspection target product are extracted to inspect the inspection target product. Accordingly, a certain inspection target product is moved to one of the fields of view of the X-ray detectors 13a to 13d, photographed, moved again to the field of view of the other X-ray detectors 13a to 13d, and imaging is performed sequentially. The X-ray image required at a very high speed can be completed compared with the configuration to be performed. Therefore, it is possible to inspect a large number of inspection objects at high speed.

(3) Other embodiments:
In the present invention, it is sufficient that a plurality of X-ray images including the same inspection target product can be acquired from the X-ray images acquired simultaneously by a plurality of detectors to inspect the inspection target product. Various configurations can be employed. For example, since the plurality of X-ray detectors 13a to 13d are arranged at a plurality of rotational positions, the X-ray images acquired by the X-ray detectors 13a to 13d have rotational symmetry, and image analysis is possible. Although there is an advantage that it is easy, the arrangement of the detectors is not limited to such an arrangement. Of course, the arrangement of the X-ray detectors 13a to 13d is not limited to the above arrangement, and the number is not limited to four.

  Further, a configuration may be adopted in which the tilt angles and positions of the X-ray detectors 13a to 13d can be freely changed, and these tilt angles and positions are changed according to the inspection object. As described above, if the tilt angle or the position is changed, the size of the visual field regions FOVa to FOVd is changed, so that the above-described unit movement amount can be changed. Further, the regions FOVa to FOVd do not need to be adjacent to each other as shown in FIG. 4 and may be separated from each other.

  In this case, the distance between the region FOVa and the region FOVc and the distance between the region FOVb and the region FOVd are preferably integer multiples of the length L. In particular, if each distance is an odd multiple of the length L, a region FOVb and a region FOVd exist in a direction parallel to the x axis, a region FOVa and a region FOVc exist in a direction parallel to the y axis, and The region can be arranged in a state of four-fold rotational symmetry with respect to the axis A extending from the focal point F. Moreover, the bump located between each area | region can be image | photographed by the scanning of integral multiple of the unit movement amount, and can image | photograph efficiently. As described above, it is preferable that the distance between the regions is an integral multiple of the length L, which is a unit movement amount, but of course, even if it is not an integral multiple, by adopting the configuration according to the present invention, the X can be efficiently obtained. It is possible to acquire a line image.

  In addition, you may employ | adopt the structure for grasping | ascertaining a unit movement amount correctly. As a configuration for this, for example, it is possible to adopt a configuration in which the height sensor acquires the height of the bump to be inspected, that is, the distance between the focal point F of the X-ray generator 11 and the bump in the z direction. . The height sensor may be any sensor that measures this distance, and various sensors can be used.

  FIG. 5 shows a configuration when a height sensor is added to the configuration shown in FIG. In FIG. 5, the height sensor 15 is disposed below the substrate 12a, and includes a laser output device 15a and a line sensor 15b. The laser output device 15a can output laser light toward the substrate 12a, and the line sensor 15b is a sensor that detects the laser light reflected by the substrate 12a. The line sensor 15b includes a plurality of sensors arranged along a certain direction, and the horizontal component of the output direction of the laser light and the direction in which the line sensor is arranged coincide with each other.

  Therefore, when the reflected laser beam fluctuates as the substrate 12a fluctuates in the vertical direction, the position where the reflected laser beam reaches the line sensor 15b also fluctuates (for example, when the substrate 12a fluctuates downward, the locus of the laser beam). Varies from a solid line to a broken line). Therefore, the position where the brightness of the reflected laser light detected by the line sensor 15b is the maximum is the arrival position of the reflected laser light, and the bump height is detected based on this arrival position. If the distance along the vertical direction between the lower surface of the substrate 12a and the focal point F is calculated by geometrically analyzing the path of the laser beam, and the height to the center of the bump and the thickness of the substrate 12a is expected, The height from the focal point F to the center of the bump can be accurately calculated.

  Of course, if the height from the upper surface of the substrate 12a to the center of the bump and the thickness of the substrate 12a are very small, these may be ignored. Even if these are ignored, the height sensor 15 causes a relatively high level when the vertical fluctuation of the substrate 12a is larger than the thickness of the substrate 12a and the height from the upper surface of the substrate 12a to the center of the bump. The height can be detected with high accuracy.

  If the position of the bump in the z direction can be calculated as described above, the size of the visual field regions FOVa to FOVd can be accurately determined from the relative positional relationship between the focal point F and the X-ray detectors 13a to 13d. Can be calculated. As a result, the unit movement amount can also be accurately calculated according to the sizes of the regions FOVa to FOVd. Therefore, the movement of the substrate 12a can be accurately controlled by the XY stage 12.

  Furthermore, a plurality of X-ray images may be acquired by the X-ray detectors 13a to 13d only when a predetermined standard is satisfied, thereby speeding up the inspection. FIG. 5 shows a configuration in which an X-ray detector 13e is added for this purpose. In other words, the X-ray detector 13e is arranged so that it is parallel to the movement plane (xy plane) of the substrate 12a and the axis A intersects the center of the detector. Such a visual field of the X-ray detector 13e is an area surrounded by the areas FOVa to FOVd in FIG.

  In this configuration, before performing the inspection by the X-ray detectors 13a to 13d, the X-ray detector 13e images a bump as a product to be inspected and performs the inspection. As this inspection, for example, an inspection that determines the cross-sectional area, volume, shape, presence / absence of a bridge in soldering, or the like of a product to be inspected based on an X-ray image can be employed. Therefore, when the inspection clearly reveals that the product is a good product or is clearly a defective product, the inspection using the X-ray detectors 13a to 13d is not performed. Only when it is not clearly determined that the product is a non-defective product or a defective product, processing based on the X-ray detectors 13a to 13d is performed in order to perform a more reliable quality determination. As a result, unnecessary inspection can be omitted, and the inspection can be performed at higher speed. In FIG. 5, the X-ray detector 13e and the height sensor 15 are shown at the same time, but it is possible to adopt a configuration including only one of them.

  Furthermore, in the above-described embodiment, it is assumed that two-dimensional analysis is performed based on a plurality of X-ray images acquired by the X-ray detectors 13a to 13d, but of course based on the plurality of X-ray images. The three-dimensional structure of the inspection target product may be analyzed. In this case, a coordinate system is set in advance including not only the coordinates on the xy plane but also the z direction, and a plurality of X-ray images are acquired in the same manner as steps S105 to S130 of FIG. Further, after the coordinates of the inspection object are designated by xy coordinates in the same manner as in step S135, a plurality of X-ray images including the designated coordinates are acquired in step S140.

  If a plurality of X-ray images can be acquired, the three-dimensional structure can be reconstructed and inspected based on various calculations in step S145. For example, a filter-corrected back projection method can be employed. In this process, first, Fourier transform is performed on any of the n X-ray images, and the result obtained by the Fourier transform is multiplied by a filter correction function in a frequency space. Furthermore, an image subjected to filter correction is obtained by performing inverse Fourier transform on this result. As the filter correction function, a function for enhancing the edge of the image can be adopted.

  Subsequently, the image after the filter correction is back-projected into a three-dimensional space along a locus on which the image is projected. That is, at the position of the XY stage 12 where each X-ray image is taken, the trajectory for acquiring the X-ray image is the focal point F of the X-ray generator 11 and the detection surfaces of the X-ray detectors 13a to 13d. It is a straight line connecting each position. Therefore, the image is back projected onto this straight line. When the above-described back projection is performed on all of the n X-ray images, the X-ray absorption coefficient distribution in the portion where the inspection target product exists in the three-dimensional space including the z direction is emphasized, and 3 of the inspection target product. A dimensional image is obtained. Of course, this process is an example, and various processes such as a process of artificially increasing the number of X-ray images by interpolation from n X-ray images can be employed.

  In any case, if a three-dimensional image of the product to be inspected is obtained, the cross-sectional area, volume and shape of the product to be inspected, the presence or absence of a bridge in soldering, etc. are inspected based on this image. Of course, it is possible to automate the inspection by setting a reference threshold value, a reference shape, or the like in advance in the cross-sectional area, the shape, or the like, or the inspection may be performed visually. In order to acquire a three-dimensional image, it is necessary to acquire a plurality of X-ray images taken from different directions. In the present invention, different inspection target products are used by a plurality of X-ray detectors 13a to 13d. X-ray images are simultaneously acquired, and a plurality of X-ray images which are X-ray images acquired by different detectors and include the same inspection target product are extracted to inspect the inspection target product. Therefore, a plurality of X-ray images necessary for acquiring a three-dimensional image can be acquired at high speed, and a three-dimensional structure can be analyzed at high speed.

1 is a schematic block diagram of an X-ray inspection apparatus according to the present invention. It is a flowchart of a X-ray inspection process. It is explanatory drawing explaining the structure of a X-ray inspection apparatus with a coordinate system. It is a figure which shows the structural example and unit movement amount of a bump. It is explanatory drawing explaining the structure of the X-ray inspection apparatus concerning other embodiment with a coordinate system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... X-ray inspection apparatus 11 ... X-ray generator 12 ... XY stage 12a ... Board | substrate 13a-13d ... X-ray detector 13e ... X-ray detector 14 ... Conveyance apparatus 15 ... Height sensor 21 ... X-ray control mechanism 22 ... Stage control mechanism 23 ... Image acquisition mechanism 24 ... Conveyance mechanism 25 ... CPU
25a ... Transport control unit 25b ... X-ray control unit 25c ... Stage control unit 25d ... Image acquisition unit 25e ... Pass / fail judgment unit 26 ... Input unit 27 ... Output unit 28 ... Memory 28a ... Inspection position data 28b ... Imaging condition data

Claims (9)

X-ray output means for outputting X-rays within a predetermined solid angle range from a fixedly arranged X-ray source;
Plane moving means for moving a plurality of inspection objects arranged in a plane in a plane within the output range of the X-ray;
A detector having a detection surface inclined with respect to an axis perpendicular to the plane of movement of the inspection object, and a plurality of detectors disposed at a plurality of positions included in the solid angle, and an X-ray image X-ray image acquisition means for acquiring
A plurality of X-ray images are acquired by the X-ray image acquisition unit while changing the position of the inspection target item by the plane moving unit, and are X-ray images acquired by different detectors and include the same inspection target item. An X-ray inspection apparatus comprising: an object inspection unit that inspects the inspection object based on a plurality of X-ray images. The target product inspection means acquires and inspects one or both of a transmission image and a tomographic image of the inspection target product based on the X-rays detected by the X-ray image acquisition means. Item 2. The X-ray inspection apparatus according to Item 1. The plane moving means moves with a predetermined unit moving amount when changing the position of the inspection object, and the length of the region included in the field of view of the detector in the moving direction is unit moving. The X-ray inspection apparatus according to claim 1, wherein the X-ray inspection apparatus is a quantity. The plurality of inspection target products include a plurality of inspection target products arranged in a straight line. In the X-ray image acquisition unit, X-ray images are detected by different detectors for different two of the plurality of inspection target products arranged. Can be acquired at the same time, and the plane moving means can move the inspection object in the direction of the straight line, so that an X-ray image can be simultaneously acquired for different two inspection objects by different detectors. The X-ray inspection apparatus according to claim 1, wherein: A position sensor for detecting a relative positional relationship between the focal point of the X-ray output means and the inspection object; and the plane moving means refers to a detection result of the position sensor and is included in the field of view of the detector. The X-ray inspection apparatus according to claim 1, wherein the length of the region in the moving direction is calculated. The X-ray inspection apparatus according to claim 1, wherein the plane moving unit includes a transport mechanism that sequentially transports a plurality of products to be inspected to an X-ray output range. Parallel X-ray detection means is provided that is disposed at a position included in the solid angle and detects X-rays on a detection surface that is substantially parallel to the plane of movement of the inspection object, and the object inspection means includes The inspection based on the X-rays detected by a plurality of detectors in the X-ray detection means when the inspection result based on the X-rays detected by the parallel X-ray detection means does not satisfy a predetermined standard. The X-ray inspection apparatus in any one of Claims 1-6. An X-ray inspection method for inspecting an inspection object with X-rays,
An X-ray output step of outputting X-rays from a fixedly arranged X-ray source to a predetermined solid angle range;
A plane moving step of moving a plurality of inspection objects arranged in a plane in a plane within the output range of the X-ray;
A detector having a detection surface inclined with respect to an axis perpendicular to the plane of movement of the inspection object while changing the position of the inspection object in the same plane moving step, and included in the solid angle An X-ray image acquisition step of acquiring X-ray images with a plurality of detectors disposed at a plurality of positions;
From the plurality of X-ray images acquired by the X-ray image acquisition process, a plurality of X-ray images that are acquired by different detectors and include the same inspection object are extracted, and these X-ray images are extracted. An X-ray inspection method comprising: an object inspection process for inspecting the inspection object based on the inspection object. An X-ray inspection program for inspecting an inspection object with X-rays,
An X-ray output function for outputting X-rays within a predetermined solid angle range from a fixedly arranged X-ray source;
A planar movement function for planarly moving a plurality of inspection objects arranged in a plane within the output range of the X-ray;
A detector having a detection surface inclined with respect to an axis perpendicular to the plane of movement of the inspection object, and a plurality of detectors disposed at a plurality of positions included in the solid angle, and an X-ray image X-ray image acquisition function to acquire
A plurality of X-ray images are acquired by the X-ray image acquisition function while the position of the inspection object is changed by the plane moving function, and X-ray images acquired by different detectors include the same inspection object. An X-ray inspection program for causing a computer to realize an object inspection function for inspecting an inspection object based on a plurality of X-ray images.

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