Fluoroscopic inspection device and fluoroscopic inspection method

Abstract

To provide a fluoroscopic inspection device and a fluoroscopic inspection method which can inspect a conduction state between a terminal and conductive foil of a through hole inner wall part to which the terminal of an electronic component is inserted.SOLUTION: A fluoroscopic inspection device comprises: a radiation source 1 which emits the radiation from the oblique lateral side to a through hole 103; incident direction change means 3, 11 which changes the incident direction of the radiation to the through hole 103; a radiation detector 4 which detects the radiation passing through the through hole 103; and an imaging circuit 6 which generates a plurality of images with the different incident directions of the radiation from the two-dimensional distribution of the detected radiation dose, constitutes one image by performing left-right inversion and / or diamond deformation of at least one of the plurality of images in a superimposed manner and removes a noise image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fluoroscopy inspection device and method for inspecting the conduction state between a conductor foil on the inner wall of a through-hole through which a terminal of an electronic component is inserted and the terminal (the solder filling rate in the through-hole and the conduction state between the conductor foil and the terminal, or the conduction state between the conductor foil and a press-fit terminal), and relates to a fluoroscopy inspection device and method for detecting and imaging radiation (X-rays, gamma rays, neutron rays, etc.) that has passed through a through-hole from an oblique side and inspecting the quality of the conduction state between the conductor foil and the terminal. [Background technology]

[0002] Conventionally, fluoroscopic inspection devices have been proposed that transmit radiation (including X-rays, gamma rays, etc.) through an object to be inspected, such as an electronic component or a circuit board on which electronic components are mounted, and detect the radiation that has transmitted through the object to detect abnormalities in the object using a radiographic image. Such fluoroscopic inspection devices are used, for example, to determine whether the mounting (soldering) state of electronic components is good or bad, for example, whether bonding wires are broken, and to perform non-destructive inspection of the patterns of internal layers of a multilayer wiring board or the like.

[0003] As described in Patent Document 1, the applicant of the present application has proposed a fluoroscopic examination device in which radially diffusing radiation (X-rays) is passed through a subject and the radiation that has passed through the subject is detected by a radiation detector having a plurality of sensing elements arranged in a line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-196983 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, with the recent trend toward higher integration and higher output (higher current) of electronic circuits, the importance of so-called through holes (through holes that penetrate the circuit board almost vertically and have conductive foil deposited on the inner peripheral wall) in circuit boards is increasing. In particular, in circuit boards used in environments exposed to severe vibrations and large temperature changes, such as automobiles, aircraft, and spacecraft, the required durability cannot be ensured unless through holes are used.

[0006] 12, a rod-shaped terminal 105 of electronic component 101 is inserted into the through-hole, and molten solder 106 is filled between terminal 105 and conductor foil 104 and solidified. Alternatively, as shown in Figures 13 and 14, a so-called press-fit terminal 107 is press-fitted into through-hole 103, and is pressed against conductor foil 104 by the elasticity of press-fit terminal 107.

[0007] Conventional fluoroscopic inspection devices can inspect the mounting (soldering) condition in a planar direction parallel to the surface of the circuit board, but cannot inspect the electrical continuity in a direction perpendicular to the surface of the circuit board, such as inside a through hole.

[0008] It should be noted that, by using computed tomography (CT), it is also possible to inspect the circuit board in a direction perpendicular to its surface. However, in computed tomography, an extremely large number of images must be taken of one object, and the amount of calculation required to process the many images taken is enormous, so the time required from taking the images to processing the images is long. Therefore, it is not practical to use computed tomography for inspection in industrial processes.

[0009] Therefore, the present invention has been proposed in consideration of the above-mentioned situation, and aims to provide a fluoroscopy inspection device and a fluoroscopy inspection method that can inspect the conductivity between the conductor foil on the inner wall of a through hole through which the terminal of an electronic component is inserted and the terminal (the solder filling rate in the through hole and the conductivity between the conductor foil and the terminal, or the conductivity between the conductor foil and the press-fit terminal). [Means for solving the problem]

[0010] In order to solve the above problems, a fluoroscopic inspection apparatus according to the present invention has any one of the following configurations.

[0011] The fluoroscopic inspection device according to the first aspect of the present invention comprises: A fluoroscopic inspection device for inspecting a conductive state between a conductor foil formed on an inner peripheral wall of a through hole that penetrates a circuit board substantially vertically and a terminal inserted into the through hole, a radiation source that generates radiation and irradiates the radiation obliquely from a side of the through hole; an incidence direction changing means for changing an incidence direction of the radiation into the through hole; a radiation detector for detecting radiation transmitted through the through hole; a signal processing means for imaging a two-dimensional distribution of the radiation amount detected by the radiation detector and generating a plurality of images of the radiation from different incident directions; an image processing means for performing left-right inversion and / or rhombus transformation on at least one of the multiple images generated by the signal processing means, and superimposing the multiple images to form a single image; Equipped with The image processing means, when the plurality of images are superimposed, uses only pixels at corresponding positions that have high brightness due to a high transmittance of the radiation to construct the single image, thereby removing noise images caused by foreign matter overlapping the through hole. It is characterized by the above.

[0012] A fluoroscopy inspection apparatus according to a second aspect of the present invention is the fluoroscopy inspection apparatus according to the first aspect of the present invention, The plurality of images having different radiation incident directions are two, three, or four images. It is characterized by the above.

[0013] A fluoroscopy inspection apparatus according to a third aspect of the present invention is the fluoroscopy inspection apparatus according to the first or second aspect of the present invention, The radiation generated by the radiation source is irradiated radially, The incident direction changing means changes the incident direction of the radiation into the through hole by moving the through hole within an irradiation range of the radiation or by moving the radiation source. It is characterized by the above.

[0014] A fluoroscopy inspection apparatus according to a fourth aspect of the present invention is the fluoroscopy inspection apparatus according to the first or second aspect of the present invention, The radiation generated by the radiation source is irradiated radially, The incident direction changing means changes the incident direction of the radiation into the through hole by rotating the through hole within the irradiation range of the radiation. It is characterized by the above.

[0015] A fluoroscopic inspection method according to a fifth aspect of the present invention comprises: 1. A fluoroscopy inspection method for inspecting a conductive state between a conductor foil formed on an inner peripheral wall of a through hole that penetrates a circuit board substantially vertically and a terminal inserted into the through hole, comprising: irradiating the through hole from an oblique lateral direction with radiation, detecting the radiation that has passed through the through hole, and imaging a two-dimensional distribution of the radiation dose; a direction of incidence of the radiation into the through hole is changed, and the radiation transmitted through the through hole is detected to form an image of a two-dimensional distribution of the radiation dose; At least one of the plurality of images having different radiation incidence directions is flipped left and right and / or transformed into a rhombus, and then these plurality of images are superimposed. Among the pixels at corresponding positions, only pixels having high brightness due to high radiation transmittance are used to construct one image, thereby removing noise images due to foreign matter overlapping the through hole. It is characterized by the above.

[0016] A fluoroscopy inspection method according to a sixth aspect of the present invention is a fluoroscopy inspection method according to the fifth aspect of the present invention, The plurality of images having different radiation incident directions are two, three, or four images. It is characterized by the above. Effect of the Invention

[0017] The fluoroscopy inspection device and fluoroscopy inspection method according to the present invention can provide a fluoroscopy inspection device and a fluoroscopy inspection method that can inspect the electrical continuity between the conductor foil on the inner wall of a through hole through which the terminal of an electronic component is inserted and the terminal. [Brief description of the drawings]

[0018] [Figure 1] 1 is a side view showing a configuration of a fluoroscopic inspection apparatus according to the present invention for carrying out a fluoroscopic inspection method according to the present invention. [Diagram 2] 1 is a perspective view showing the principle of a fluoroscopic inspection device according to the present invention; [Diagram 3] FIG. 2 is a plan view showing a first image (a) and a second image (b) obtained in the fluoroscopy inspection apparatus according to the present invention. [Figure 4] 5A and 5B are plan views showing a third image (a) and a fourth image (b) obtained in the fluoroscopy inspection apparatus according to the present invention. [Diagram 5] FIG. 2 is a plan view showing a first image (a) and a second image (b) that is flipped horizontally. [Figure 6] FIG. 11 is a plan view showing a third image (a) and a fourth image (b) that are flipped horizontally. [Figure 7] FIG. 11 is a plan view showing a fifth image (a) in which a first image and a second image reversed horizontally are superimposed, and a sixth image (b) in which a third image and a fourth image reversed horizontally are superimposed. [Figure 8] 13A is a plan view showing a fifth image deformed into a rhombus (a) and a sixth image deformed into a rhombus (b). FIG. [Figure 9] FIG. 13 is a plan view showing a seventh image obtained by superimposing a fifth image deformed into a rhombus and a sixth image deformed into a rhombus. [Figure 10] FIG. 13 is a diagram illustrating left-right reversal. [Figure 11] FIG. 13 is a diagram illustrating rhombus deformation. [Figure 12] 4 is a cross-sectional view showing a through hole to which a terminal of an electronic component is soldered. FIG. [Figure 13] 1 is a cross-sectional view showing a through hole into which a so-called press-fit terminal (1) is press-fitted. [Figure 14] 1 is a cross-sectional view showing a through hole into which a so-called press-fit terminal (2) is press-fitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] First Embodiment FIG. 1 is a side view showing the configuration of a fluoroscopic inspection apparatus according to the present invention for carrying out a fluoroscopic inspection method according to the present invention.

[0021] This fluoroscopic inspection device is a fluoroscopic inspection device that inspects the conduction state (solder filling rate in the through hole and the conduction state between the conductor foil and the terminal, or the conduction state between the conductor foil and the press-fit terminal) between a conductor foil that penetrates a circuit board substantially vertically and a terminal inserted into the through hole. As shown in FIG. 1, this fluoroscopic inspection device has an X-ray tube 1 that generates radiation, for example, an X-ray beam X, and serves as a radiation source that irradiates a circuit board 102 (through hole 103) on which an electronic component 101 is mounted. As shown in FIG. 12, this X-ray tube 1 irradiates the X-ray beam X from an oblique side to the through hole 103 that penetrates the circuit board 102 substantially vertically and has a conductor foil 104 that is formed on the inner wall. This X-ray tube 1 is controlled by an X-ray control device 2. The X-ray control device 2 is controlled by a control device 10. The X-ray beam X emitted from the X-ray tube 1 and transmitted through the circuit board 102 (through hole 103) is detected by the X-ray detector 4, which is a radiation detector.

[0022] FIG. 12 is a cross-sectional view showing a through hole to which a terminal of an electronic component is soldered.

[0023] 12, a rod-shaped terminal 105 of electronic component 101 is inserted into through hole 103, and molten solder 106 is filled between terminal 105 and conductor foil 104 and solidified. If the volume filling rate of molten solder 106 is less than a predetermined value (e.g., 80%), the electrical continuity between terminal 105 and conductor foil 104 is determined to be poor. Also, if there are air bubbles in molten solder 106 at a predetermined air bubble rate (e.g., 3%) or more, the electrical continuity between terminal 105 and conductor foil 104 is determined to be poor.

[0024] FIG. 13 is a cross-sectional view showing a through hole into which a so-called press-fit terminal (1) is press-fitted. FIG. 14 is a cross-sectional view showing a through hole into which a so-called press-fit terminal (2) is press-fitted.

[0025] 13 and 14, a so-called press-fit terminal 107 is pressed into through-hole 103, and the elasticity of press-fit terminal 107 causes it to be crimped to conductor foil 104. Press-fit terminal 107 is made of an elastic conductor such as beryllium copper, and has a bulge or protrusion on its side for crimping to conductor foil 104. If press-fit terminal 107 deforms out of a predetermined shape and the contact area and contact pressure with conductor foil 104 are less than predetermined values, the electrical continuity between press-fit terminal 107 and conductor foil 104 is determined to be poor.

[0026] A circuit board 102 on which electronic components 101 are mounted is placed on a movement operation mechanism (XY stage) 3 serving as an incident direction changing means. This movement operation mechanism 3 moves the circuit board 102 in a direction crossing the X-ray beam X within the irradiation range of the X-ray beam X. The circuit board 102 is moved in two axial directions indicated by arrow A in FIG. 1 or rotated as indicated by arrow B by the movement operation mechanism 3. The movement operation mechanism 3 may also move the X-ray detector 4 instead of the circuit board 102. The X-ray generator 1 or the X-ray detector 4 is moved by a movement operation mechanism 11 serving as an incident direction changing means.

[0027] The control device 10 changes the incident direction of the X-ray beam X into the through hole 103 by moving any two of the circuit board 102, the X-ray tube 1, and the X-ray detector 4 using the movement operation mechanisms 3, 11.

[0028] The X-ray detector 4 detects the two-dimensional distribution of the radiation dose (X-ray dose) that has passed through the through hole 103. A commonly used image pickup tube type can be used as this X-ray detector 4. This type of X-ray detector 4 detects based on the principle of scanning with an electron beam and reading out the electric charge that has been charged in proportion to the X-ray dose in the sensing portion.

[0029] Since the X-ray beam X is emitted from the X-ray tube 1 and spreads radially, it spreads even after passing through the circuit board 102 and is detected by the X-ray detector 4. Therefore, the X-ray detector 4 detects an enlarged transmitted image of the hole 103. The magnification at this time is determined by the ratio between the distance from the X-ray tube 1 to the hole 103 and the distance from the X-ray tube 1 to the X-ray detector 4, and is, for example, about 8 to 10 times.

[0030] The X-ray detector 4 is connected to a detector controller 5 and is controlled by the detector controller 5, and the detected radiation intensity information is amplified by the detector controller 5. The radiation intensity information amplified by the detector controller 5 is supplied to an imaging circuit 6 which serves as a signal processing means and an image processing means. The imaging circuit 6 is controlled by a control device 10, and images the two-dimensional distribution of the radiation amount detected by the X-ray detector 4, generates an image signal, and sends it to a display device 7. The display device 7 displays an image according to the image signal sent from the imaging circuit 6.

[0031] In this manner, in this fluoroscopic inspection device, the circuit board 102 is scanned with X-rays, and each of the through holes 103 formed in the circuit board 102 is fluoroscopically inspected in sequence.

[0032] The imaging circuit 6 removes noise images caused by other electronic components, etc. overlapping the hole 103 by superimposing an image based on the amount of transmitted radiation when the X-ray beam X is irradiated into the hole 103 from a first direction and an image based on the amount of transmitted radiation when the X-ray beam X is irradiated into the hole 103 from a second or subsequent direction.

[0033] The number of images with different incidence directions of the X-ray beam X is preferably two images spaced at 180° intervals, three images spaced at 120° intervals, or four images spaced at 90° intervals. However, the angle intervals and the number of images are not limited in any way. The number of images required to remove noise images varies depending on the shape and arrangement of other electronic components, etc., and may be two images spaced at 60° intervals (±30°), 90° intervals (±45°), or 120° intervals (±60°). With three or four images, almost all noise images can be removed.

[0034] FIG. 10 is a diagram for explaining left-right reversal. FIG. 11 is a diagram for explaining the rhombus deformation.

[0035] When overlapping multiple images, at least one of the multiple images is subjected to left-right flipping and / or rhombus transformation before being overlapped. Here, left-right flipping means reversing the left-right of the image as shown in FIG. 10, which is equivalent to creating a mirror image. Here, rhombus transformation means increasing (or decreasing) only the vertical axis value (or horizontal axis value) of each pixel position in proportion to the horizontal axis value (or vertical axis value), as shown in FIG. 11. In other words, it is a transformation in which the coordinates (x, y) of an arbitrary pixel are changed to the coordinates (x, y+ax) (∵a: gradient).

[0036] When multiple images are superimposed, one image is constructed by using only pixels at corresponding positions that have high brightness due to high transmittance of the X-ray beam X. By superimposing the images in this manner, noise in the image caused by foreign objects (other electronic components, etc.) overlapping the through hole 103 is eliminated.

[0037] In addition, as the incidence angle (depression angle) of the X-ray beam X onto the circuit board 102 is increased, the overlap of foreign objects with the through hole 103 is reduced, but the image of the through hole 103 becomes shorter, which may make it difficult to detect the conductive state between the terminal 105 and the conductor foil 104. As the incidence angle (depression angle) of the X-ray beam X is decreased, the overlap of foreign objects with the through hole 103 is increased, but the image of the through hole 103 becomes longer, which makes it easier to detect the conductive state between the terminal 105 and the conductor foil 104. In the present invention, since noise images due to foreign objects are removed, it is preferable to reduce the incidence angle (depression angle) of the X-ray beam X onto the circuit board 102 within a range that does not affect the removal of noise images.

[0038] Hereinafter, a case where the number of images with different incident directions of the X-ray beam X is four images spaced at 90° intervals will be described with examples of images that are actually obtained.

[0039] FIG. 2 is a perspective view showing the principle of the fluoroscopic inspection device according to the present invention. FIG. 3 is a plan view showing a first image (a) and a second image (b) obtained in the fluoroscopic inspection apparatus according to the present invention.

[0040] That is, as shown in FIG. 2, first, a first image is obtained based on the amount of transmitted radiation when the X-ray beam X is irradiated onto the through-hole 103 from a first direction ("45°" in FIG. 2). The first image is shown in FIG. 3(a). Six through-holes 103 are formed in a row on the circuit board 102. Next, a second image is obtained based on the amount of transmitted radiation when the X-ray beam X is irradiated onto the through-hole 103 from a second direction ("135°" in FIG. 2). The second image is shown in FIG. 3(b).

[0041] FIG. 4 is a plan view showing a third image (a) and a fourth image (b) obtained in the fluoroscopic inspection apparatus according to the present invention.

[0042] Next, a third image is obtained based on the amount of transmitted radiation when the X-ray beam X is irradiated onto the hole 103 from a third direction ("225°" in FIG. 2). The third image is shown in FIG. 4(a). Next, a fourth image is obtained based on the amount of transmitted radiation when the X-ray beam X is irradiated onto the hole 103 from a fourth direction ("315°" in FIG. 2). The fourth image is shown in FIG. 4(b). These first to fourth images include noise images due to foreign objects (other electronic components, etc.) overlapping the hole 103.

[0043] FIG. 5 is a plan view showing a first image (a) and a second image (b) that is flipped horizontally. FIG. 6 is a plan view showing the third image (a) and the fourth image (b) which are flipped horizontally.

[0044] Next, the second image is flipped horizontally as shown in Fig. 5(b). When the second image is flipped horizontally, the shape of the image of the corresponding through hole 103 coincides with that of the first image shown in Fig. 5(a). Furthermore, the third image is flipped horizontally as shown in Fig. 6(a). When the third image is flipped horizontally, the shape of the image of the corresponding through hole 103 coincides with that of the fourth image shown in Fig. 6(b).

[0045] FIG. 7 is a plan view showing a fifth image (a) in which a first image is superimposed on a second image that has been flipped horizontally, and a sixth image (b) in which a third image is superimposed on a fourth image that has been flipped horizontally.

[0046] Next, as shown in Fig. 7(a), the first image and the second image, which is flipped horizontally, are superimposed to generate a fifth image. At this time, only pixels at corresponding positions that have high brightness due to high transmittance of the X-ray beam X are used to generate the fifth image, thereby removing noise images caused by foreign objects (other electronic components, etc.). Here, if the foreign objects (other electronic components, etc.) are arranged in a row, they are sufficiently removed by superimposing the two images.

[0047] Next, as shown in Fig. 7(b), the third image is flipped horizontally and the fourth image are overlapped to form a sixth image. At this time, only pixels with high brightness among the pixels at corresponding positions are used to form the sixth image.

[0048] FIG. 8 is a plan view showing a fifth image (a) that has been subjected to rhombus deformation and a sixth image (b) that has been subjected to rhombus deformation.

[0049] Next, the fifth image is deformed into a diamond shape as shown in FIG. 8(a), and the sixth image is deformed into a diamond shape as shown in FIG. 8(b), so that the shapes of the images of the corresponding holes 103 in the fifth image and the sixth image are made to match.

[0050] FIG. 9 is a plan view showing a seventh image obtained by superimposing a fifth image that has been rhombus-shaped and a sixth image that has been rhombus-shaped.

[0051] 9, the fifth image deformed into a rhombus and the sixth image deformed into a rhombus are superimposed to obtain a seventh image. Here too, only pixels at corresponding positions that have high brightness due to high transmittance of the X-ray beam X are used to obtain the seventh image, thereby removing noise images caused by foreign objects (other electronic components, etc.). In this seventh image, noise images caused by foreign objects (other electronic components, etc.) are removed, and the electrical continuity between the terminals 105, 107 in each through hole 103 and the conductor foil 104 is detected. [Industrial Applicability]

[0052] The present invention is applied to a fluoroscopy inspection device and a fluoroscopy inspection method that inspects the conductive state between the conductor foil on the inner wall of a through hole through which the terminal of an electronic component is inserted and the terminal (the solder filling rate in the through hole and the conductive state between the conductor foil and the terminal, or the conductive state between the conductor foil and the press-fit terminal), and is applied to a fluoroscopy inspection device and a fluoroscopy inspection method that detects and images radiation (X-rays, gamma rays, neutron rays, etc.) that has passed through a through hole from an oblique side and inspects whether the conductive state between the conductor foil and the terminal is good or not. [Explanation of symbols]

[0053] 1 X-ray source (radiation source) 2 X-ray control device 3, 11 Movement operation mechanism (incident direction changing means) 4. X-ray detector (radiation detector) 6 Imaging circuit (signal processing means, image processing means) 10 Control device 101 Electronic Components 102 Circuit Board 103 Through hole 104 Conductor foil 105 Terminal 106 Molten solder 107 Press-fit terminal X-ray beam (radiation)

Claims

1. A fluoroscopic inspection device for inspecting a conductive state between a conductor foil formed on an inner peripheral wall of a through hole that penetrates a circuit board substantially vertically and a terminal inserted into the through hole, a radiation source that generates radiation and irradiates the radiation obliquely from a side of the through hole; an incidence direction changing means for changing an incidence direction of the radiation into the through hole; a radiation detector for detecting radiation transmitted through the through hole; a signal processing means for imaging a two-dimensional distribution of the radiation amount detected by the radiation detector and generating a plurality of images of the radiation from different incident directions; an image processing means for performing left-right inversion and / or rhombus transformation on at least one of the plurality of images generated by the signal processing means, and superimposing the plurality of images to form a single image; Equipped with The image processing means, when the plurality of images are superimposed, uses only pixels at corresponding positions that have high brightness due to a high transmittance of the radiation to construct the single image, thereby removing noise images caused by foreign matter overlapping the through hole. A fluoroscopy inspection apparatus characterized by the above.

2. The plurality of images having different radiation incidence directions are two images, three images, or four images.

2. The fluoroscopic inspection apparatus according to claim 1.

3. The radiation generated by the radiation source is irradiated radially, The incident direction changing means changes the incident direction of the radiation into the through hole by moving the through hole within an irradiation range of the radiation or by moving the radiation source.

3. The fluoroscopic inspection apparatus according to claim 1 or 2.

4. The radiation generated by the radiation source is irradiated radially, The incident direction changing means changes the incident direction of the radiation into the through hole by rotating the through hole within the irradiation range of the radiation.

3. The fluoroscopic inspection apparatus according to claim 1 or 2.

5. 1. A fluoroscopy inspection method for inspecting a conductive state between a conductor foil formed on an inner peripheral wall of a through hole that penetrates a circuit board substantially vertically and a terminal inserted into the through hole, comprising: irradiating the through hole from an oblique lateral direction with radiation, detecting the radiation that has passed through the through hole, and imaging a two-dimensional distribution of the radiation dose; a direction of incidence of the radiation into the through hole is changed, and the radiation transmitted through the through hole is detected to form an image of a two-dimensional distribution of the radiation dose; At least one of the plurality of images having different radiation incidence directions is flipped left and right and / or transformed into a rhombus, and then these plurality of images are superimposed. Among the pixels at corresponding positions, only pixels having high brightness due to a high transmittance of the radiation are used to construct one image, thereby removing noise images due to foreign matter overlapping the through hole. A fluoroscopic inspection method comprising:

6. The plurality of images having different radiation incidence directions are two images, three images, or four images.

6. The fluoroscopic inspection method according to claim 5.

Images