Inspection device

Abstract

Provided is an inspection apparatus capable of estimating a dose irradiated to an object at the time of inspection without irradiating radiation and measuring a radiation dose using a dosimeter. In an inspection apparatus (1) having a storage section (34) and a radiation dose calculation section (50), the radiation dose calculation section (50) performs the following steps: a first step of calculating a dose at the time of irradiation of radiation from a radiation generator (22) to acquire an image, based on a reference dose stored in the storage section (34); a second step of calculating a dose at the time of a change in relative position of the radiation generator (22) and the object; a third step of calculating a total value of a dose irradiated to the object; and a fourth step of outputting the total value.

Description

Technical Field

[0001] This invention relates to an inspection device. Background Technology

[0002] As an inspection device for measuring the solder shape on the surface or back of a substrate, there is an X-ray inspection device using a tomographic synthesis method (see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-026334 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The following problem exists in such an inspection device: although the object being inspected is irradiated with X-rays, the dose of X-rays irradiated to the object during the inspection cannot be known without using a dosimeter to measure the radiation dose.

[0008] The present invention was made in view of the following problem, and its object is to provide an examination device that can estimate the dose irradiated to the subject during examination without irradiation with X-rays or other radiation and without using a dosimeter to measure the radiation dose.

[0009] Solution for solving the problem

[0010] To solve the above problems, the inspection apparatus of the present invention changes the relative position of a radiation source and an object to be inspected and irradiates the object with radiation from the radiation source, acquires an image of the object to inspect it, and the inspection apparatus includes: a storage unit that stores a dose irradiated from the radiation source to a predetermined position relative to the radiation source as a reference dose; and a calculation unit that calculates the dose irradiated to the object during the inspection, the calculation unit performing the following steps: a first step, based on the reference dose stored in the storage unit, calculating the dose irradiated to the object during the period when the relative position of the radiation source and the object is fixed and the image is acquired, or The process involves four steps: First, calculating the dose irradiated onto the subject by means of the relative position of the radiation source and the subject during the period of changing the relative position while acquiring the image; second, calculating the dose irradiated onto the subject based on the reference dose stored in the storage unit, according to the relative position of the radiation source and the subject during the period of changing the relative position of the radiation source and the subject; third, calculating the total dose irradiated onto the subject by means of the sum of the dose calculated in the first step and the dose calculated in the second step; and fourth, outputting the total value calculated in the third step.

[0011] The effects of the invention

[0012] According to the inspection apparatus of the present invention, it is possible to estimate the dose irradiated onto the subject during inspection without the need for exposure to radiation such as X-rays. Attached Figure Description

[0013] Figure 1 This is an explanatory diagram illustrating the structure of the inspection device involved in the embodiment.

[0014] Figure 2 This is an explanatory diagram illustrating the functional blocks processed by the control unit of the aforementioned inspection device.

[0015] Figure 3 It is a flowchart used to illustrate the inspection process.

[0016] Figure 4 This is a flowchart illustrating the process of radiation dose calculation.

[0017] Figure 5 This is an explanatory diagram used to illustrate the types of radiation generators (X-ray sources). (a) represents a transmission type X-ray source, and (b) represents a reflection type X-ray source.

[0018] Figure 6This is an explanatory diagram used to illustrate the distribution of radiation dose. (a) shows the distribution of radiation dose at shooting position 1, (b) shows the radiation dose when stationary, and (c) shows the radiation dose when moving.

[0019] Figure 7 This is an explanatory diagram used to illustrate the distribution of radiation dose. (a) to (c) represent the radiation dose at various locations within the range of movement.

[0020] Figure 8 This is an explanatory diagram used to illustrate the distribution of radiation dose at shooting location 2.

[0021] Figure 9 This is an explanatory diagram illustrating the distribution of radiation dose when moving from shooting position 1 to shooting position 2. (a) shows the case where the radiation generator is always producing radiation, and (b) shows the case where the radiation generator is only producing radiation at the shooting position.

[0022] Figure 10 It is an explanatory diagram used to illustrate the distribution of total radiation dose when photographing the entire area being inspected.

[0023] Figure 11 This is an explanatory diagram illustrating the distribution of radiation dose when taking pictures while moving the substrate holder and the detector. (a) shows the case where the radiation generator always generates radiation, and (b) shows the case where the radiation generator only generates radiation at the shooting position.

[0024] Figure 12 This is an illustration of radiation dose with and without a filter, (a) representing the absence of a filter and (b) representing the presence of a filter.

[0025] Figure 13 This is an explanatory diagram showing an example of the calculated radiation dose output. Detailed Implementation

[0026] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 As shown, the inspection device 1 according to this embodiment is configured to have a control unit 10, a monitor 12, and an imaging unit 32, which are processing devices such as personal computers (PCs). In addition, the imaging unit 32 also includes a line quality modification unit 14, a radiation generator drive unit 16, a substrate holding unit drive unit 18, a detector drive unit 20, a radiation generator 22, a substrate holding unit 24, and a detector 26.

[0027] Radiation generator 22 is a device (radiation source) that generates radiation such as X-rays, for example, by colliding accelerated electrons with a target material such as tungsten or diamond. Regarding the radiation in this embodiment, X-rays are described, but the invention is not limited to this. For example, the radiation may also be alpha rays, beta rays, gamma rays, ultraviolet light, visible light, or infrared light. Furthermore, the radiation may also be microwaves or terahertz waves.

[0028] The substrate holding section 24 holds the substrate, which is the object to be inspected. Radiation generated by the radiation generator 22 is irradiated onto the substrate held on the substrate holding section 24, and the detector 26 captures the radiation that has passed through the substrate as an image. Hereinafter, the radiation transmission image of the substrate captured by the detector 26 will be referred to as a "transmission image". Furthermore, as described later, in this embodiment, the substrate holding section 24 holding the substrate and the detector 26 are moved relative to the radiation generator 22 to acquire multiple transmission images, thereby generating a reconstructed image.

[0029] The transmission image captured by detector 26 is sent to control unit 10, where it is reconstructed into a three-dimensional image containing the solder joints using known techniques such as filtered-backprojection (FBP). The reconstructed image or transmission image is then stored in memory within control unit 10 or in external memory (not shown). Hereinafter, the image reconstructed from the transmission image into a three-dimensional image containing the solder joints is referred to as a "reconstructed image." Additionally, an image cut from the reconstructed image at an arbitrary cross-section is referred to as a "cross-sectional image." Such reconstructed images and cross-sectional images are output to monitor 12. Furthermore, monitor 12 displays not only the reconstructed image or cross-sectional image but also the inspection results of the solder joint status, which will be described later. Also, as mentioned above, the reconstructed image in this embodiment is reconstructed from a planar image captured by detector 26, and is therefore also referred to as a "planar CT."

[0030] The line quality modification unit 14 modifies the line quality of the radiation generated by the radiation generator 22. The line quality of the radiation is determined by the voltage applied to accelerate electrons colliding with the target (hereinafter referred to as "tube voltage") and the current that determines the number of electrons (hereinafter referred to as "tube current"). The line quality modification unit 14 is a device that controls these tube voltages and tube currents. This line quality modification unit 14 can be implemented using known technologies such as transformers or rectifiers.

[0031] Here, the quality of the radiation is determined by its brightness and hardness (spectral distribution). Increasing the tube current increases the number of electrons colliding with the target, thus increasing the number of photons produced. As a result, the brightness of the radiation increases. For example, in components such as capacitors, there are parts that are thicker than others; to capture a transmission image of these parts, high-brightness radiation is required. In this case, the brightness of the radiation is adjusted by changing the tube current. Furthermore, increasing the tube voltage increases the energy of the electrons colliding with the target, resulting in higher energy (spectral density) radiation. Generally, the higher the energy of the radiation, the greater its penetrating power through matter, making it less easily absorbed. Transmission images captured using such radiation have reduced contrast. Therefore, the contrast of the transmission image can be adjusted using the tube voltage.

[0032] The radiation generator drive unit 16 has a drive mechanism such as a motor (not shown) that enables the radiation generator 22 to move up and down along an axis passing through its focal point (the direction of this axis is defined as the "Z-axis direction"). This allows for changing the irradiation field by altering the distance between the radiation generator 22 and the object under inspection (substrate) held on the substrate holder 24, and also changing the magnification of the transmission image captured by the detector 26. Furthermore, the position of the radiation generator 22 in the Z-axis direction is detected by the generator position detection unit 23 and output to the control unit 10.

[0033] The detector drive unit 20 also has a drive mechanism such as a motor (not shown) to rotate the detector 26 along the detector rotation track 30. Additionally, the substrate holding unit drive unit 18 also has a drive mechanism such as a motor (not shown) to move the substrate holding unit 24 parallel to the plane on which the substrate rotation track 28 is provided. Furthermore, the substrate holding unit 24 is configured to rotate and move along the substrate rotation track 28 in conjunction with the rotational movement of the detector 26. Therefore, it is possible to capture multiple transmission images with different projection directions and angles while changing the relative positional relationship between the substrate held by the substrate holding unit 24 and the radiation generator 22.

[0034] Here, the rotation radii of the substrate rotation track 28 and the detector rotation track 30 are not fixed, but can be freely changed. This allows for arbitrary adjustment of the irradiation angle of the radiation irradiating the components disposed on the substrate. Furthermore, the track surfaces of the substrate rotation track 28 and the detector rotation track 30 are orthogonal to the aforementioned Z-axis direction. If the orthogonal directions in these track surfaces are defined as the X-axis and Y-axis directions, the positions of the substrate holding unit 24 in the X-axis and Y-axis directions are detected by the substrate position detection unit 29 and output to the control unit 10, and the positions of the detector 26 in the X-axis and Y-axis directions are detected by the detector position detection unit 31 and output to the control unit 10.

[0035] The control unit 10 controls all operations of the aforementioned inspection device 1. Next, using... Figure 2 The functions of the control unit 10 are explained. Furthermore, although not shown in the diagram, the control unit 10 is connected to input devices such as a keyboard and mouse.

[0036] The control unit 10 includes a storage unit 34, a cross-sectional image generation unit 36, a substrate inspection surface detection unit 38, a pseudo-cross-sectional image generation unit 40, and an inspection unit 42. Furthermore, although not shown, the control unit 10 also includes an imaging control unit that controls the operation of the line quality modification unit 14, the radiation generator drive unit 16, the substrate holding unit drive unit 18, and the detector drive unit 20. These functional blocks are implemented through the cooperation of hardware such as a CPU that performs various arithmetic operations, RAM used as a workspace for data storage or program execution, and software. Therefore, these functional blocks can be implemented in various forms through a combination of hardware and software.

[0037] The storage unit 34 stores information such as the imaging conditions for capturing transmission images of the substrate and the design of the substrate as the object to be inspected. The storage unit 34 also stores transmission images or reconstructed images (cross-sectional images, pseudo-cross-sectional images) of the substrate, as well as the inspection results of the inspection unit 42 described later. The storage unit 34 also stores the speed at which the radiation generator drive unit 16 drives the radiation generator 22, the speed at which the substrate holding unit drive unit 18 drives the substrate holding unit 24, and the speed at which the detector drive unit 20 drives the detector 26.

[0038] The cross-sectional image generation unit 36 ​​generates a cross-sectional image based on multiple transmission images acquired from the storage unit 34. This can be achieved using known techniques such as the FBP method or the maximum likelihood estimation method. Different reconstruction algorithms result in different properties of the reconstructed image or different reconstruction times. Therefore, it is also possible to pre-prepare multiple reconstruction algorithms or parameters used in the algorithms and allow the user to select them. This provides the user with the freedom to prioritize either shortening the reconstruction time or prioritizing good image quality even if it takes longer. The generated cross-sectional image is output to the storage unit 34 and recorded therein.

[0039] The substrate inspection surface detection unit 38 determines the position (cross-sectional image) of the surface on the substrate that is to be inspected (e.g., the surface of the substrate) from among the multiple cross-sectional images generated by the cross-sectional image generation unit 36. Hereinafter, the cross-sectional image showing the inspection surface of the substrate will be referred to as an "inspection surface image". Details regarding the inspection surface image detection method will be described later.

[0040] The pseudo-cross-section image generation unit 40 images a predetermined number of cross-section images consecutively stacked from the cross-section image generation unit 36, thereby imaged a region of the substrate thicker than the cross-section image. The number of stacked cross-section images is determined by the thickness of the substrate region reflected in the cross-section image (hereinafter referred to as "slice thickness") and the slice thickness of the pseudo-cross-section image. For example, if the slice thickness of the cross-section image is 50 μm and the height of the BGA solder ball (hereinafter referred to as "solder") (e.g., 500 μm) is to be set as the slice thickness for the pseudo-cross-section image, then 500 / 50 = 10 cross-section images can be stacked. In this case, the inspection surface image determined by the substrate inspection surface detection unit 38 is used to determine the position of the solder.

[0041] The inspection unit 42 inspects the solder bonding state based on the cross-sectional image generated by the cross-sectional image generation unit 36, the inspection surface image determined by the substrate inspection surface detection unit 38, and the pseudo-cross-sectional image generated by the pseudo-cross-sectional image generation unit 40. Since the solder that bonds the substrate and the component is located near the substrate inspection surface, by inspecting the inspection surface image and the cross-sectional image of the area reflecting the radiation generator 22 side relative to the inspection surface image, it is possible to determine whether the solder has properly bonded the substrate and the component.

[0042] Here, "solder bonding condition" refers to whether a proper conductive path has been created between the substrate and the component through solder bonding. The inspection of the solder bonding condition includes bridging inspection, melting state inspection, and void inspection. "Bridge" refers to an undesirable conductive path formed between conductors due to solder bonding. "Melting state" refers to whether the bonding between the substrate and the component is insufficient due to inadequate solder melting, i.e., whether it is "floating." "Void" refers to a poor solder bonding condition caused by air bubbles within the solder joint. Therefore, the inspection unit 42 includes a bridging inspection unit 44, a melting state inspection unit 46, and a void inspection unit 48.

[0043] The detailed operation of the bridging inspection unit 44, the molten state inspection unit 46, and the hole inspection unit 48 will be described later. The bridging inspection unit 44 and the hole inspection unit 48 perform bridging and hole inspections respectively based on the pseudo-cross-section image generated by the pseudo-cross-section image generation unit 40. The molten state inspection unit 46 inspects the molten state of the solder based on the inspection surface image determined by the substrate inspection surface detection unit 38. Furthermore, the inspection results of the bridging inspection unit 44, the molten state inspection unit 46, and the hole inspection unit 48 are recorded in the storage unit 34.

[0044] Figure 3This is a flowchart illustrating the process from capturing a transmission image and generating a reconstructed image, to determining the inspection surface image and inspecting the solder joint status. The processing in this flowchart, for example, begins when the control unit 10 receives an instruction to start the inspection from an input device not shown.

[0045] As described above, the control unit 10 sets the irradiation field of the radiation emitted by the radiation generator 22 via the radiation generator drive unit 16, changes the imaging position by moving the substrate holding unit 24 via the substrate holding unit drive unit 18 and moving the detector 26 via the detector drive unit 20, sets the line quality of the radiation generator 22 via the line quality change unit 14 and irradiates the substrate with radiation to capture a transmission image, and generates a reconstructed image based on the multiple transmission images captured in this way via the cross-sectional image generation unit 36 ​​and the pseudo-cross-sectional image generation unit 40 (step S100).

[0046] Next, the substrate inspection surface detection unit 38 of the control unit 10 receives a transmission image or a reconstructed image (cross-section image) from the cross-section image generation unit 36, and determines an inspection surface image from the transmission image or the reconstructed image (cross-section image) (step S102). The bridging inspection unit 44 obtains a pseudo-cross-section image from the pseudo-cross-section image generation unit 40, which reflects the solder ball and has the same slice thickness as the solder ball, and checks whether bridging exists (step S104). If no bridging is detected ("No" in step S106), the melt state inspection unit 46 obtains an inspection surface image from the substrate inspection surface detection unit 38 and checks whether the solder has melted (step S108). If the solder has melted ("Yes" in step S110), the hole inspection unit 48 obtains a pseudo-cross-section image from the pseudo-cross-section image generation unit 40 that partially reflects the solder ball, and checks whether holes exist (step S112). If no voids are found (No in step S114), the void inspection unit 48 determines that the solder joint is normal (step S116) and outputs this information to the storage unit 34. Conversely, if bridging is detected (Yes in step S106), if the solder has not melted (No in step S110), or if a void exists (Yes in step S114), the bridging inspection unit 44, the melting state inspection unit 46, and the void inspection unit 48 determine that the solder joint is abnormal (step S118) respectively, and output this information to the storage unit 34. When the solder state is output to the storage unit 34, the processing in this flowchart ends.

[0047] Furthermore, the control unit 10 of the inspection apparatus 1 includes a radiation dose calculation unit 50, which calculates the amount (dose or radiation dose) of radiation (X-rays) irradiated onto the inspected object (substrate) during inspection through calculation. In X-ray inspections of inspected objects such as electronic substrates and electronic components, the radiation dose calculation unit 50 does not actually use a dosimeter to measure the radiation dose. Instead, it uses the control unit 10, which is a personal computer (PC) or a device embedded with some computing mechanisms, to simulate the operation of the inspection apparatus 1 (the relative movement of the substrate holding unit 24 relative to the radiation generator 22) to calculate the radiation dose.

[0048] The radiation dose calculation unit 50 calculates the radiation dose of the subject placed on the substrate holding unit 24 based on information related to the radiation generator 22 stored in the storage unit 34 beforehand. Specifically, the value (reference dose) measured as follows is stored in the storage unit 34 in association with the position (coordinate) in the Z-axis direction, and the values ​​of tube voltage and tube current, etc. This value (reference dose) is measured by setting the tube voltage and tube current of the radiation generator 22 to predetermined values ​​by the line quality change unit 14 and placing the dosimeter at a predetermined position directly below the radiation generator 22 (a predetermined position on the axis (Z-axis) of the focal point of the radiation generator 22). For example, the dosimeter is placed at the predetermined position, and multiple values ​​are measured by increasing the tube voltage by 10kV and the tube current by 50μA, and then stored in the storage unit 34. Furthermore, the dose measured in advance is not only measured directly below the radiation generator 22, but also, for example, measured at multiple points along the X-axis and Y-axis directions from the measurement point directly below it. By using planar approximation or linear interpolation to determine the relationship between tube voltage and tube current and dose, the amount of information required for pre-measurement can be reduced. Furthermore, since the radiation dose to the object being inspected decreases inversely proportional to the square of the distance between the object being inspected (substrate holding portion 24) and the radiation generator 22, by calculating the attenuation of the X-ray dose directly below and around the radiation generator 22, pre-measurement can be performed only at a predetermined location directly below the radiation generator 22.

[0049] use Figures 4 to 13 This will explain the processing of the radiation dose calculation unit 50. For example... Figure 4As shown, when the radiation dose calculation process begins, firstly, the radiation dose calculation unit 50 of the control unit 10 reads the inspection information from the storage unit 34 (step S200). Here, the inspection information refers to the size of the object being inspected (the size of the substrate), or the position, name, and size of the components mounted on the substrate. Next, the radiation dose calculation unit 50 reads the imaging conditions (X-ray imaging conditions during the inspection) from the storage unit 34 (step S202). Here, the imaging conditions refer to the tube voltage, tube current, exposure time, magnification (the distance between the radiation generator 22, the substrate holding unit 24, and the inspector 26), the tilt angle in planar CT (the angle relative to the axis passing through the focal point of the radiation generator 22), and the number of transmission image images taken in the CT calculation.

[0050] Furthermore, the radiation dose calculation unit 50 acquires the type (ray source type) of the designated radiation generator 22 (step S204). Here, the ray source type refers to the type of X-ray source that serves as the radiation generator 22, or information about the physical filter installed on the X-ray source. Moreover, the type of ray source can be pre-stored in the storage unit 34 and retrieved from the storage unit 34, or it can be acquired using an input device such as a keyboard or mouse (not shown). For example, the type of X-ray source is as follows: Figure 5 As shown in (a), X-rays are generated by a tungsten target and the generated X-rays pass directly through a tungsten transmission X-ray source, or as shown in (a). Figure 5 As shown in (b), this is a reflective X-ray source that generates X-rays by reflecting them from a tungsten target. Furthermore, the type of filter is determined by information such as the filter material (e.g., zinc) or the thickness (e.g., 100 μm or 200 μm, etc.) when it is plate-shaped. In addition, the filter is not limited to plate-shaped types; it can also be a bowtie filter, a collimator, or an aperture filter, among other non-uniform thickness filters.

[0051] return Figure 4As described above, the radiation dose calculation unit 50 simulates the action of moving the substrate holding unit 24 along the substrate rotation track 28 and taking pictures, and calculates the radiation dose at this time. Specifically, the radiation dose calculation unit 50 calculates the radiation dose when taking one transmission image in the simulated area, adds it to the total radiation dose (total value of radiation dose) (step S206), determines whether there is a next shooting location (step S208), and if it is determined that there is a next shooting location ("yes" in step S208), calculates the radiation dose during the period of moving to the next shooting location, adds it to the total radiation dose (step S210), and returns to step S206 to repeat the process. The radiation dose during the movement can be calculated by accumulating the radiation dose at a specific location within a small time period in units of small time. Regarding the calculation of radiation dose, it is based on the imaging conditions and the reference dose stored in the storage unit 34, and is calculated according to the relative position of the radiation generator 22 and the subject being examined.

[0052] Figure 6 Figure (a) illustrates the radiation dose calculated for a specific shooting position (e.g., shooting position 1) in step S206. The black rectangle represents the outline of the object being inspected (printed circuit board, etc.), which is the target area for calculating the radiation dose in the radiation dose calculation process. Additionally, the dashed rectangles represent electronic components mounted on the object being inspected, and the concentric white circular areas represent the radiation dose. Here, the higher the radiation dose, the whiter it appears.

[0053] Here, the exposure time during imaging is set to 100 milliseconds. When the device moves a distance of tens of millimeters in milliseconds during the movement, and the substrate holding section 24 and detector 26 are stopped while imaging is performed, the radiation dose distribution is as follows: Figure 6 As in (b), the distribution of radiation dose during the minute period of movement of the substrate holding portion 24 and the detector 26 is as follows: Figure 6 As in (c). In this way, the radiation dose during the movement of the substrate holding part 24 and the detector 26 is less than the radiation dose during the stop of the substrate holding part 24 and the detector 26.

[0054] in addition, Figure 7 Figures (a) to (c) illustrate the radiation dose calculated during the movement when it is determined in step S208 that a next imaging location exists. As described above, the individual radiation doses calculated for the locations (3 locations) moved at predetermined time intervals (tiny time intervals) are shown.

[0055] and, Figure 8 The radiation dose at the next shooting position (shooting position 2) calculated in step S206 is shown.

[0056] Figure 9 (a) indicates the radiation dose when images were taken at the two locations (image location 1 and image location 2) while the radiation generator 22 was generating radiation and the image was repeatedly taken and moved. Figure 6 (a) and Figure 8 ) and radiation dose during movement ( Figure 7 The cumulative radiation dose obtained from (a) to (c) is as follows. Furthermore, the radiation dose when radiation generator 22 is stopped generating radiation during movement (when radiation generator 22 is generating radiation only at the shooting position) is as follows: Figure 9 (b) like that.

[0057] Figure 10 The diagram shows the distribution of the total radiation dose when photographing and moving repeatedly over the entire area to be inspected while radiation generator 22 is generating radiation. Thus, by calculating the total radiation dose during both photographing and movement in a single inspection, it is possible to determine not only the radiation dose during photographing but also the radiation dose during movement.

[0058] Furthermore, the above process was described based on a structure where the substrate holding section 24 is stopped while imaging is performed and the image is moved to the next imaging location. However, even in a structure where imaging is performed while the substrate holding section 24 remains in a moving state, the total radiation dose can still be calculated using the same method. In this case, as described above, the total radiation dose can be calculated by accumulating the radiation dose at a specific location over a minute time interval. Figure 11 The radiation dose under this condition is shown in (a). Additionally, in the case where the radiation generator 22 is not irradiated with X-rays while the substrate holding part 24 is moving, as in... Figure 11 As shown in (b), the radiation dose during the movement was 0.

[0059] Furthermore, in the calculation of radiation dose during imaging in step S206 and the calculation of radiation dose during movement in step S210, it is also possible to correct for non-uniformity or unevenness corresponding to the angle relative to the radiation generator 22 based on the radiation dose calculated based on the position (distance) of the substrate holding part 24 relative to the radiation generator 22. For example, in such cases... Figure 5 As shown in (a), when X-rays are passed through a plate-shaped filter 22a with a thickness of 100 μm, the passing length for the subject directly below is 100 μm, but in the 45-degree direction, the passing length becomes... The length is 141 μm, which is twice the length of the original, so the difference in length is corrected. Figure 12 (a) represents the radiation dose in the absence of filter 22a. In contrast, Figure 12 (b) represents the radiation dose when filter 22a is configured. Thus, the further outward the filter is, the longer the transmission distance, and the greater the attenuation of X-rays, resulting in a lower radiation dose. On the other hand, in the case of a beryllium window with low X-ray absorption, there is almost no absorption in the tilt direction, so no correction is required.

[0060] In addition, in the calculation of radiation dose in steps S206 and S210, the entire area of ​​the substrate (the area where the substrate is placed in the substrate holding part 24) that is the simulation object is divided into partial areas of a specific size (e.g., 1 mm), the radiation dose of each partial area is calculated, and the total radiation dose of each partial area is added together, thereby obtaining the distribution of the total radiation dose on the object being inspected.

[0061] return Figure 4 If the radiation dose calculation unit 50 determines that there is no next imaging position (No in step S208), it performs the above-mentioned total radiation dose analysis process (step S212). For example, as described above, when the entire area of ​​the substrate is divided into partial areas and the total radiation dose of each partial area is calculated, the process of determining the distribution of radiation dose is performed. In addition, by calculating the sum of the total radiation dose of the partial areas within the area of ​​each component disposed on the substrate, the radiation dose (total value) of each component can be calculated. For example, in Figure 10 Based on the area and radiation dose distribution of the components shown by the dashed lines, the total radiation dose of each component is calculated.

[0062] Finally, the radiation dose calculation unit 50 outputs the analysis results (calculation results) (step S214). The output destination can be either the storage unit 34 or the monitor 12. Figure 13 This is an example of outputting analysis results on screen 12a of monitor 12. For example, the entire area of ​​the substrate can be displayed as area 12b on the screen, and the distribution of radiation dose can be displayed as contour lines according to a specified radiation dose. At this time, the area with the most radiation can be displayed in red, the area with the least radiation can be displayed in blue, and the other areas can be displayed in other colors. Alternatively, the radiation dose can also be displayed as a numerical value.

[0063] Furthermore, after calculating the radiation dose of each component, the components can be arranged in descending order of radiation dose in area 12c of the screen and displayed together with the radiation dose. Additionally, when displaying the distribution of radiation dose on the substrate in area 12b, by overlaying an image of the substrate, the relationship between the components mounted on the substrate and the distribution of radiation dose can be visually confirmed.

[0064] As described above, the amount of radiation received by the subject during the examination is calculated by the radiation dose calculation unit 50 of the control unit 10, allowing for a preliminary estimate of the amount of radiation the subject will receive before actually being irradiated with X-rays (before the examination). The user sets the optimal radiation dose imaging conditions by repeatedly performing the following process: setting the prescribed imaging conditions (as described above, the number of transmission image shots, tube voltage, tube current, exposure time, magnification, etc. used for CT calculations), calculating the radiation dose and displaying it on the monitor 12, and changing the imaging conditions considering image quality and production cycle time, calculating the radiation dose again and displaying it on the monitor 12.

[0065] Explanation of reference numerals in the attached figures

[0066] 1: Inspection device; 10: Control unit; 22: Radiation generator (ray source); 34: Storage unit; 50: Radiation dose calculation unit (calculation unit).

Claims

1. An inspection apparatus that changes the relative position of a radiation source and an object to be inspected and irradiates the object with radiation from the radiation source, acquires an image of the object to inspect it, the inspection apparatus comprising: The storage unit stores the dose irradiated from the radiation source to a predetermined position relative to the radiation source as a reference dose. as well as The calculation unit calculates the dose irradiated onto the subject during the examination. Before inspecting the object being inspected, the computing unit reads the inspection information and imaging conditions of the object being inspected and simulates the action of moving the object being inspected along the track and taking pictures to perform the following steps: Step 1: Based on the reference dose stored in the storage unit, an estimated dose to be irradiated onto the subject is calculated according to the relative position of the radiation source and the subject during the period when the relative position of the radiation source and the subject is fixed and the image is acquired at the imaging site, or during the period when the relative position is changed and the image is acquired at the imaging site. Step 2: Based on the reference dose stored in the storage unit, and according to the relative position of the radiation source and the subject during the period when the imaging site is moved by changing the relative position of the radiation source and the subject, an estimated value of the dose irradiated to the subject is calculated. Step 3: Calculate the total estimated dose to be irradiated onto the subject based on the sum of the estimated dose calculated in Step 1 and the estimated dose calculated in Step 2. as well as Step 4: Output the total value calculated in step 3. The storage unit stores information related to the characteristics of the radiation source. When the calculation unit calculates the dose to be irradiated onto the subject in the first and second steps, it corrects the calculated dose based on information related to the characteristics of the radiation source stored in the storage unit.

2. The inspection device according to claim 1, wherein, In steps 1 and 2, the calculation unit divides the area where the subject is placed into multiple partial regions and calculates the dose for each partial region. In the third step, the calculation unit calculates the total value for each of the partial regions.

3. The inspection device according to claim 2, wherein, In the fourth step, the calculation unit outputs the distribution of the total value of the dose in the form of an image.

4. The inspection device according to claim 2, wherein, The storage unit stores information related to components installed on the object being inspected. In the fourth step, the calculation unit outputs the total value of each component based on the information related to the component stored in the storage unit, according to the total value of the dose of the partial region at the location of the component.

5. The inspection device according to claim 3, wherein, The storage unit stores information related to components installed on the object being inspected. In the fourth step, the calculation unit outputs the total value of each component based on the information related to the component stored in the storage unit, according to the total value of the dose of the partial region at the location of the component.

Images