X-ray inspection method using an X-ray inspection device, and X-ray inspection device

Abstract

To provide an X-ray inspection method using an X-ray inspection apparatus and the X-ray inspection apparatus which can correct fluctuations in luminance of an X-ray transmission image more accurately even in a case where sensitivity to the X-ray in an imaging unit deteriorates over time, and luminance of an X-ray transmission image of metal is significantly reduced in comparison with the luminance of the X-ray transmission image of the air.SOLUTION: An X-ray inspection method having an imaging step of generating a photographed image of an inspection object and a calibration step of adjusting luminance of a photographed image further includes a projection correction step of adjusting luminance of a photographed image by multiplying a prescribed constant number by a value obtained by dividing a value obtained by subtracting an offset value from an object value by a value obtained by subtracting the offset value from a gain value, and acquiring new luminance by using a prescribed coefficient uniquely relevant to a difference between an influence of sensitivity reduction of an imaging unit to the object value and an influence of the sensitivity reduction of the imaging unit to the gain value relative to the adjusted luminance of the photographed image.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an X-ray inspection method using an X-ray inspection apparatus, and to an X-ray inspection apparatus. [Background technology]

[0002] Conventionally, there is a known X-ray inspection apparatus that inspects an object to be inspected using an X-ray transmission image obtained by irradiating the object with X-rays from an irradiation unit, and the apparatus comprises a sensor for measuring the amount of X-rays from the irradiation unit and a degradation degree calculation unit for calculating the degree of degradation of the irradiation unit based on the amount of X-rays measured by the sensor. By using this X-ray inspection apparatus and X-ray inspection method, the degree of degradation of the irradiation unit that irradiates with X-rays can be calculated, and for example, the lifespan of the irradiation unit can be predicted (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-173372 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] According to the invention disclosed in Patent Document 1, in an X-ray inspection apparatus, the sensitivity of the imaging unit to X-rays deteriorates over time due to continuous irradiation of the imaging unit with X-rays from the irradiation unit. Generally, the object to be inspected described in Patent Document 1 contains metal, and since metal has a higher X-ray absorption rate than air, if the sensitivity of the imaging unit to X-rays deteriorates over time, the brightness of the X-ray transmitted image of metal will decrease significantly compared to the brightness of the X-ray transmitted image of air during long-term operation. As a result, fluctuations occur in the brightness of the obtained X-ray transmitted image.

[0005] To explain in more detail, the brightness of the obtained X-ray transmission image is PJ ij The brightness of the X-ray transmission image projected onto the object being imaged is determined by the Object ij, set the luminance of the X-ray transmission image of air to Gain ij Then, PJ ij can be expressed by the following equation (1).

Equation

[0006] According to the above equation (1), since the difference in the degree of decrease between Gain ij and Object ij is not considered, it is difficult to accurately measure the luminance of the obtained X-ray transmission image (hereinafter, the "obtained X-ray transmission image" will simply be referred to as the "X-ray transmission image") in a method for calculating the degree of deterioration of the irradiation unit that irradiates X-rays. Therefore, in order to accurately measure the luminance of the X-ray transmission image, a method of performing correction to reduce the variation in the luminance of the X-ray transmission image is required.

[0007] The present invention has been made in view of the above problems, and even when the sensitivity of the imaging unit to X-rays deteriorates over time during long-term operation and the luminance of the X-ray transmission image in which the imaging object, which is the inspection target, is projected decreases significantly compared to the luminance of the X-ray transmission image of air, it is possible to more accurately correct the variation in the luminance of the X-ray transmission image. The ultimate object is to provide an X-ray inspection method using an X-ray inspection apparatus and an X-ray inspection apparatus.​​

Means for Solving the Problem

[0008] The present disclosure for solving the above problems is an imaging step of generating an imaging image of the test object by irradiating the imaging unit with X-rays through the test object from an irradiation unit, a calibration step of adjusting the luminance of the imaging image generated in the imaging step, and is an X-ray inspection method having a gain value which is the luminance of the imaging image that can be obtained by imaging in a state where the X-rays are directly irradiated from the irradiation unit to the imaging unit without arranging anything between the irradiation unit and the imaging unit, an object value which is the luminance of the imaging image that can be obtained by imaging in a state where the X-rays are irradiated from the irradiation unit through the test object to the imaging unit, an offset value which is the luminance of the imaging image that can be obtained by imaging in a state where nothing is arranged between the irradiation unit and the imaging unit and the X-rays are not irradiated, and using in the calibration step, by multiplying a value obtained by subtracting the offset value from the object value by a predetermined constant and dividing the result by a value obtained by subtracting the offset value from the gain value, the luminance of the imaging image is adjusted, further having a projection correction step of obtaining a new luminance by using a predetermined coefficient that is uniquely related to the difference between the influence of the sensitivity decrease of the imaging unit on the object value and the influence of the sensitivity decrease of the imaging unit on the gain value with respect to the luminance of the imaging image adjusted in the calibration step, characterized by including an X-ray inspection method.

[0009] In the projection correction process, it is possible to reduce fluctuations in the brightness of the object under inspection by obtaining a new brightness using a predetermined coefficient that is uniquely related to the difference between the effect of decreased sensitivity of the imaging unit on the object value and the effect of decreased sensitivity of the imaging unit on the gain value. Specifically, the gain value can be considered as the brightness of the image of air, and since the object under inspection used in the X-ray inspection method in this disclosure can be considered to include metal, the object value can be considered as the brightness of the image onto which the object being imaged is projected. When the sensitivity of the imaging unit to X-rays deteriorates over time, the brightness of the image of metal decreases significantly compared to the brightness of the image of air. That is, the degree of decrease in the gain value and the object value is different at this time. The effect of the difference in the degree of decrease in the gain value and the object value can be ignored in the projection correction process by using a predetermined coefficient. As a result, the brightness of the image can be obtained with even greater accuracy in the projection correction process compared to the brightness of the image adjusted in the calibration process.

[0010] Furthermore, the present disclosure may also provide an X-ray inspection method characterized by further comprising: a CT image generation step of generating a CT image of the object to be inspected based on the new brightness acquired in the projection correction step; and a determination step of determining the state of the object to be inspected based on the CT image generated in the CT image generation step. By generating a CT image of the object to be inspected in the CT image generation step, it becomes easier to check the object to be inspected from all angles, and in the determination step, it becomes easier to determine the state of the object to be inspected.

[0011] Furthermore, the present disclosure may also provide an X-ray inspection method characterized by further comprising a display step for displaying the result of the determination step. This allows for visual or numerical determination of whether the condition of the object being inspected is good or not.

[0012] Furthermore, in this disclosure, the predetermined coefficient is such that no decrease in the sensitivity of the imaging unit occurs. An X-ray inspection method may also be used, characterized in that the brightness after the calibration process is obtained for a predetermined object to be inspected for correction, whose initial brightness, which is the brightness in the state, is known, and the brightness is determined based on the difference between the obtained brightness after the calibration process and the initial brightness. According to this, an optimal predetermined coefficient can be determined and the brightness of the captured image can be obtained with greater accuracy.

[0013] Furthermore, in this disclosure, the X-ray inspection method may also be characterized in that the corrective inspection object is a plurality of metals formed on a substrate. The coefficient determined using this corrective inspection object can also be used for inspecting actual products.

[0014] Furthermore, in this disclosure, the initial brightness of the image of the object to be inspected for correction is also characterized in that the initial brightness of the metals included in the image among the plurality of metals is the average value of the initial brightness of the metals included in the image. This makes it easier to determine the initial brightness regardless of the number of metals included in the image.

[0015] Furthermore, this disclosure is, An irradiation unit that irradiates the object to be inspected with X-rays, An imaging unit that senses the X-rays irradiated from the irradiation unit and generates an image of the object to be inspected, An X-ray inspection apparatus comprising: a calibration unit that adjusts the brightness of the image generated by the imaging unit, Without placing anything between the irradiation unit and the imaging unit, the gain value is the brightness of the captured image that can be acquired by imaging while the X-rays are directly irradiated from the irradiation unit to the imaging unit, The object value, which is the brightness of the captured image, is obtained by imaging the captured image while the X-rays are irradiated from the irradiation unit through the object to be inspected to the imaging unit, Using the offset value, which is the brightness of the captured image obtained by imaging without placing anything between the irradiation unit and the imaging unit and without irradiating with X-rays, The calibration unit adjusts the brightness of the captured image by multiplying the value obtained by subtracting the offset value from the object value by the value obtained by subtracting the offset value from the gain value by a predetermined constant. The X-ray inspection apparatus may further include a projection correction unit that acquires a new brightness using a predetermined coefficient uniquely related to the difference between the effect of the decrease in sensitivity of the imaging unit on the object value and the effect of the decrease in sensitivity of the imaging unit on the gain value, with respect to the brightness of the captured image adjusted by the calibration unit.

[0016] The projection correction unit can reduce fluctuations in the brightness of the object under inspection by acquiring a new brightness using a predetermined coefficient that is uniquely related to the difference between the effect of the reduced sensitivity of the imaging unit on the object value and the effect of the reduced sensitivity of the imaging unit on the gain value. As a result, the brightness of the captured image can be acquired with even greater accuracy in the projection correction process compared to the brightness of the captured image adjusted in the calibration process.

[0017] Furthermore, the present disclosure may also provide an X-ray inspection apparatus that further comprises a CT image generation unit that generates a CT image of the object to be inspected based on the new brightness acquired by the projection correction unit, and a determination unit that determines the state of the object to be inspected based on the CT image generated by the CT image generation unit. The CT image generation unit generates a CT image of the object to be inspected, making it easier to view the object from any angle, and the determination unit makes it easier to determine the state of the object to be inspected.

[0018] Furthermore, this disclosure further includes a display unit that displays the result determined by the determination unit. An X-ray inspection device characterized by the above may be used. With this device, it is possible to visually or numerically determine whether the condition of the object being inspected is good or not.

[0019] Furthermore, in this disclosure, the predetermined coefficient may be determined based on the difference between the acquired brightness after adjustment by the calibration unit and the initial brightness, for a predetermined object to be inspected for correction, whose initial brightness is known when the sensitivity of the imaging unit has not decreased. This allows for the determination of an optimal predetermined coefficient and the acquisition of brightness in the captured image with greater accuracy.

[0020] Furthermore, in this disclosure, the X-ray inspection apparatus may be characterized in that the corrective inspection object is a plurality of metals formed on a substrate. Examples of corrective inspection objects include metals such as tungsten formed on a substrate. The coefficient determined using this corrective inspection object can also be used for inspecting actual products.

[0021] Furthermore, in this disclosure, the X-ray inspection apparatus may be characterized in that the initial brightness of the image of the object to be inspected for correction is the average value of the initial brightness of the metals included in the image among the plurality of metals. This makes it easy to measure the initial brightness regardless of the number of metals included in the image.

[0022] Furthermore, the means for solving the above problems can be used in combination with each other as much as possible. [Effects of the Invention]

[0023] According to the present invention, in an X-ray inspection method using an X-ray inspection apparatus, and in an X-ray inspection apparatus, even when the sensitivity of the imaging unit to X-rays deteriorates over time due to long-term operation, and the brightness of the X-ray transmitted image of the metal object being inspected decreases significantly compared to the brightness of the X-ray transmitted image of air, it is possible to reduce fluctuations in the brightness of the X-ray transmitted image with greater accuracy. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 is a functional block diagram showing an example of an X-ray inspection apparatus according to an embodiment. [Figure 2] Figures 2A to 2C are schematic diagrams illustrating the types of brightness used by the calibration unit in the embodiment to adjust the brightness of the X-ray transmitted image of the solder, and the method for obtaining said brightness. [Figure 3] Figure 3 is a flowchart showing the procedure for an X-ray inspection method using an X-ray inspection apparatus according to an embodiment. [Figure 4] Figures 4A and 4B are schematic diagrams that supplementarily illustrate the X-ray inspection method using the X-ray inspection apparatus according to the embodiment. [Modes for carrying out the invention]

[0025] [Examples of application] The following outlines some examples of applications of this disclosure, using some drawings. This disclosure can be applied to an X-ray inspection apparatus 1 as shown in Figure 1. Furthermore, by using the X-ray inspection apparatus 1, this disclosure can be applied to the process shown in the flowchart of Figure 3.

[0026] Figure 1 is a functional block diagram showing an example of an X-ray inspection apparatus 1 to which this disclosure can be applied. In this application example, the X-ray inspection apparatus 1 includes, as an example of hardware configuration, an irradiation unit 10, an X-ray camera 11, a data management server 12, a computing unit 13, and a User Interface (UI) 14. The arrows shown in Figure 1 indicate that each component of the X-ray inspection apparatus 1 (showing both hardware and functional configurations) is connected via a wireless or wired communication line. This indicates that they are interconnected.

[0027] When measuring the brightness of the X-ray transmission image of an object to be inspected using the X-ray inspection apparatus 1, first a support such as a stage (not shown) is placed between the irradiation unit 10 and the X-ray camera 11, the object to be inspected is placed on the support, and X-rays are irradiated from the irradiation unit 10 to the X-ray camera 11 through the object to be inspected. Examples of the X-ray camera 11 include an X-ray image intensifier, an amorphous silicon camera, and an X-ray fluorescence camera. In addition, an example of an object to be inspected in this disclosure is solder 21 formed on a substrate 2, which is an actual product, and an X-ray transmission image of the solder 21 is acquired using the X-ray inspection apparatus 1, and it is determined from the acquired X-ray transmission image whether or not the soldering has been done properly. Here, the X-ray camera 11 corresponds to the imaging unit in this disclosure, and the X-ray transmission image corresponds to the captured image in this disclosure.

[0028] Over time, the sensitivity of the X-ray camera 11 to X-rays (hereinafter, "sensitivity of the X-ray camera 11 to X-rays" is simply referred to as "sensitivity") deteriorates, and the brightness of the X-ray transmitted image of the solder 21 fluctuates in accordance with this deterioration of sensitivity. To reduce this fluctuation in the brightness of the X-ray transmitted image, when measuring the brightness of the X-ray transmitted image, a coefficient corresponding to the deterioration of sensitivity is added to or subtracted from the brightness of the X-ray transmitted image that has already been measured (corresponding to the projection correction process S103 shown in Figure 3 below). To determine this coefficient, a jig is used in place of the solder 21 in the actual product, with multiple metal parts 31 formed on the jig substrate 3. Details are explained in Figures 4A and 4B below.

[0029] X-rays are irradiated onto the solder 21 from the irradiation unit 10, and the transmitted light is received by the light-receiving surface of the X-ray camera 11, thereby generating an X-ray transmission image of the solder 21. The generated X-ray transmission image is supplied to and stored in the data management server 12. In addition to the X-ray transmission image of the solder 21, the data management server 12 also stores data related to the sensitivity of the X-ray camera 11 and data obtained from the components of the computing unit 13, which will be described below.

[0030] The calculation unit 13 of the X-ray inspection apparatus 1 is broadly composed of a calibration unit 130, a projection correction unit 131, a CT image generation unit 132, and a judgment unit 133, etc. The calibration unit 130 may acquire the X-ray transmission image of the solder 21 stored in the data management server 12 from the data management server 12, or it may acquire the X-ray transmission image of the solder 21 directly from the X-ray camera 11. After acquiring the X-ray transmission image of the solder 21, the calibration unit 130 adjusts the brightness of the X-ray transmission image of the solder 21 based on the brightness shown in Figures 2A to C below. Details will be explained in the calibration process S102 shown in Figure 3 below.

[0031] The projection correction unit 131 adds or subtracts a predetermined coefficient from the brightness of the X-ray transmitted image of the solder 21 adjusted by the calibration unit 130. Details will be explained in the projection correction step S103 shown in Figure 3 below. The CT image generation unit 132 and the judgment unit 133 will be explained in the embodiment.

[0032] Figures 2A to 2C are schematic diagrams illustrating the types of brightness used by the calibration unit 130 to which this disclosure is applicable to adjust the brightness of the X-ray transmitted image of the solder 21, and the method for obtaining said brightness. Figure 2A is a schematic diagram illustrating the method for obtaining a gain value, which is a type of brightness. The gain value is the brightness of the X-ray transmitted image that can be obtained by imaging with X-rays directly irradiated from the irradiation unit 10 to the X-ray camera 11, without placing anything such as a substrate 2 between the irradiation unit 10 and the X-ray camera 11. In Figure 2A, since only air is being imaged, an X-ray transmitted image with brightness corresponding to the brightness of the air can be obtained. That is, the gain value can be considered as the brightness of the X-ray transmitted image of air.

[0033] Figure 2B is a schematic diagram illustrating a method for obtaining object values, which are a type of brightness. Object values ​​are the brightness of the X-ray transmission image obtained by irradiating the X-ray camera 11 with X-rays transmitted from the irradiation unit 10 through the solder 21. In Figure 2B, the object values ​​change depending on the substrate 2 (more precisely, the material and number of solder 21 formed on the substrate 2). Note that in the X-ray transmission image in Figure 2B, only one solder 21 is shown for simplicity, but normally multiple solder 21 are imaged.

[0034] Figure 2C is a schematic diagram illustrating a method for obtaining an offset value, which is a type of brightness. The offset value is the brightness of the X-ray transmission image that can be obtained by imaging without placing anything such as a substrate 2 between the irradiation unit 10 and the X-ray camera 11, and without irradiating X-rays from the irradiation unit 10. The offset value is the brightness due to the effect of dark current, and in the X-ray transmission image of Figure 2C, the proportion of black pixels is large, and the brightness of the X-ray transmission image is low.

[0035] By using the above gain value, object value, and offset value, it is possible to adjust the brightness of the X-ray transmitted image of the solder 21 in the calibration process S102 shown in Figure 3 below. In the following, the gain value, object value, and offset value are referred to as Gain ij , and Object ij , and Offset ij It should be written as follows.

[0036] Figure 3 is a flowchart showing the procedure of an X-ray inspection method using an X-ray inspection apparatus 1 to which this disclosure is applicable. In this flowchart, first, X-rays are irradiated onto the metal part 21 from the irradiation unit 10, and the transmitted light is received by the light-receiving surface of the X-ray camera 11 to generate an X-ray transmission image of the solder 21 (S101). Here, S101 corresponds to the imaging step in this disclosure. Next, the calibration unit 130 performs Gain ij , and Object ij , and Offset ijBased on this, the brightness of the X-ray transmitted image of the solder 21 is adjusted (S102). Here, S102 corresponds to the calibration step in this disclosure. In the calibration step S102, the Gain shown in equation (1) above ij ―Offset ij The average of is replaced by a constant C. This allows for the luminance PJ of the X-ray transmission image. ij This can be simplified and expressed by the following equation (2).

number

[0037] Next, the projection correction unit 131 adjusts the brightness PJ of the X-ray transmission image that was adjusted in the calibration process S102. ij A predetermined coefficient is added to or subtracted from the right-hand side of the above equation (2) (S103). Here, S103 corresponds to the projection correction step in this disclosure. The predetermined coefficient is defined as Coefficient (Coefficient may be a positive or negative value), and the luminance PJ of the X-ray transmitted image in the projection correction step S103 is calculated. ij This can be expressed by the following equation (3).

number

[0038] [Examples] The X-ray inspection method using the X-ray inspection apparatus 1 according to the embodiments of this disclosure, and the X-ray inspection apparatus 1, will be described in more detail below with reference to the drawings (including the drawings that were described in the above application examples). However, the X-ray inspection method using the X-ray inspection apparatus 1 according to the embodiments of this disclosure, and the X-ray inspection apparatus 1, are not intended to be limited to the following configurations.

[0039] <Functional Configuration> Now, let's return to the explanation of Figure 1. Since the X-ray inspection apparatus 1 according to this embodiment has the same configuration as the X-ray inspection apparatus 1 described in the application example, a detailed explanation of the contents described in the application example will be omitted. In addition, in this specification, the same reference numerals are used to describe the same components.

[0040] The CT image generation unit 132 corrects the brightness PJ of the new X-ray transmission image described in equation (3) of the above application example, which has been corrected by the projection correction unit 131 through geometric processing using Computed Tomography (CT). ij Based on this, a CT image (a type of 3D image) of the solder 21 is generated from the X-ray transmission image. The CT image generation unit 132 generates the CT image by repeatedly performing a process of absorbing X-rays from the X-ray transmission image multiple times.

[0041] The determination unit 133 determines the state of the solder 21 based on the CT image generated by the CT image generation unit 132. For example, the determination unit 133 measures the thickness of the solder 21 based on the CT image and determines whether the solder 21 is properly formed on the substrate 2 based on the measurement result. The determination unit 133 may also measure other parameters besides the thickness of the solder 21.

[0042] Furthermore, the UI14 is configured to include a display unit 140, such as a monitor or display. The display unit 140 displays the result determined by the judgment unit 133. For example, the judgment unit 133 may determine the state of the solder 21 based on the CT image, and the display unit 140 may display the characters "OK" or "NG" according to the result. In addition, the display unit 140 may display the X-ray transmission image generated by the X-ray camera 11 or the brightness PJ of the X-ray transmission image adjusted by the calibration unit 130. ij The projection correction unit 131 corrects the brightness PJ of the X-ray transmission image. ij It may also be possible to visualize and display such information.

[0043] Furthermore, the UI14 may include an input unit (not shown) for inputting information to the arithmetic unit 13, such as a keyboard or mouse. The arithmetic unit 13 may also be configured to include the UI14.

[0044] <Flowchart> Now, let's return to the explanation of Figure 3. The CT image generation unit 132 adjusts the brightness PJ of the new X-ray transmission image corrected in the projection correction step S103. ij Based on this, a CT image of the solder 21 is generated from the X-ray transmission image (S104). Here, S104 corresponds to the CT image generation step in this disclosure. The determination unit 133 determines the state of the solder 21 based on the CT image generated in the CT image generation step S104 (S105). Here, S105 corresponds to the determination step in this disclosure. The display unit 140 displays the measured values ​​determined by the determination unit 133. The result is displayed (S106). Here, S106 corresponds to the display step in this disclosure.

[0045] <X-ray inspection method> FIGS. 4A and 4B are schematic diagrams for supplementarily explaining the X-ray inspection method using the X-ray inspection apparatus 1 according to the embodiment. The luminance PJ of the X-ray transmission image obtained in the calibration step S102 ij For the purpose of correcting, that is, for the purpose of obtaining the Coefficient in the projection correction step S103, hereinafter, instead of the solder 21 formed on the substrate 2, the metal part 31 formed on the jig substrate 3 as a jig is used as the inspection object for correction in the present disclosure. The metal part 31 is mainly composed of, for example, tungsten or the like, and is formed by analogy with the solder 21 in the actual product. In the present embodiment, the shape of the metal part 31 is, for example, a sphere, and the diameter is about 1 mm.

[0046] Note that the luminance in the state where the deterioration of the sensitivity does not occur in the X-ray transmission image of the metal part 31 is known. Hereinafter, this ideal luminance is referred to as the initial luminance. In FIG. 4A, the portion surrounded by the dotted line indicates the imaging range when the X-ray camera 11 images the metal part 31. Here, it is assumed that nine metal parts 31 are formed on the jig substrate 3, and five of the metal parts 31 are included in the imaging range. In this case, the X-ray transmission image includes five metal parts 31, and the average value of the initial luminance of the pixels at the location where the five metal parts 31 are included in the X-ray transmission image is regarded as the initial luminance of the X-ray transmission image of the metal part 31. For example, when the number of pixels in each of the five metal parts 31 in the X-ray transmission image is twenty, the number of pixels at the location where the five metal parts 31 are included is one hundred, and the average value of the luminance of the one hundred pixels is regarded as the initial luminance of the X-ray transmission image of the metal part 31.

[0047] Figure 4B is a schematic diagram illustrating how the projection correction unit 131 determines the coefficient. The coefficient and the average value of the initial brightness of the solder 21 (hereinafter simply referred to as "initial brightness") are correlated with each other. For example, if the coefficient is set to x and the initial brightness to y, and three points (e.g., points A1, A2, and A3) are plotted on a coordinate plane to represent the correlation between the initial brightness and the coefficient corresponding to the initial brightness, a graph and a mathematical formula (e.g., a straight line y=ax+b) representing the correlation between the initial brightness and the coefficient will be displayed on the display unit 140.

[0048] In the graph of Figure 4B, for example, suppose the initial brightness at point A1 was 150. In contrast, with sensitivity degradation occurring, the brightness PJ of the X-ray transmission image, which is the same X-ray transmission image used to plot point A1, is adjusted by the calibration unit 130. ij Let's assume it was 148. In this case, the initial brightness and the brightness PJ of the X-ray transmission image adjusted by the calibration unit 130. ij A coefficient equivalent to the difference of 2 is determined. The coefficient determined in this way can be used in the projection correction step S103 when measuring the brightness of the X-ray transmitted image of the actual product.

[0049] For example, if point A2 is a point on the y-axis (intercept), then the coefficient at point A2 is 0, and in the projection correction process S103, the brightness PJ of the X-ray transmission image ij Since no correction is needed, the luminance at point A2 can be determined to the desired value.

[0050] The configuration of the X-ray inspection apparatus 1 shown in this embodiment may also be applied to other inspection apparatuses that use X-rays, such as an X-ray CT scanner.

[0051] <Note 1> By irradiating the imaging unit (11) with X-rays from the irradiation unit (10) through the object to be examined (21), , an imaging step (S101) to generate an image of the object to be inspected, An X-ray inspection method comprising a calibration step (S102) for adjusting the brightness of the image generated in the imaging step, Without placing anything between the irradiation unit and the imaging unit, the gain value is the brightness of the captured image that can be acquired by imaging while the X-rays are directly irradiated from the irradiation unit to the imaging unit, The object value, which is the brightness of the captured image, is obtained by imaging the captured image while the X-rays are irradiated from the irradiation unit through the object to be inspected to the imaging unit, Using the offset value, which is the brightness of the captured image obtained by imaging without placing anything between the irradiation unit and the imaging unit and without irradiating with X-rays, In the calibration step, the brightness of the captured image is adjusted by multiplying the value obtained by subtracting the offset value from the object value by the value obtained by subtracting the offset value from the gain value by a predetermined constant. An X-ray inspection method further comprising a projection correction step (S103) in which a new brightness is obtained using a predetermined coefficient uniquely related to the difference between the effect of the decrease in sensitivity of the imaging unit on the object value and the effect of the decrease in sensitivity of the imaging unit on the gain value, with respect to the brightness of the captured image adjusted in the calibration step.

[0052] <Note 2> An irradiation unit (10) that irradiates X-rays through the object to be inspected (21), An imaging unit (11) that senses the X-rays irradiated from the irradiation unit and generates an image of the object to be inspected, An X-ray inspection apparatus (1) comprising a calibration unit (130) that adjusts the brightness of the captured image generated by the imaging unit, Without placing anything between the irradiation unit and the imaging unit, the gain value is the brightness of the captured image that can be acquired by imaging while the X-rays are directly irradiated from the irradiation unit to the imaging unit, The object value, which is the brightness of the captured image, is obtained by imaging the captured image while the X-rays are irradiated from the irradiation unit through the object to be inspected to the imaging unit, Using the offset value, which is the brightness of the captured image obtained by imaging without placing anything between the irradiation unit and the imaging unit and without irradiating with X-rays, The calibration unit adjusts the brightness of the captured image by multiplying the value obtained by subtracting the offset value from the object value by the value obtained by subtracting the offset value from the gain value by a predetermined constant. X-ray inspection apparatus (1) further comprises a projection correction unit (131) that acquires a new brightness using a predetermined coefficient uniquely related to the difference between the effect of the decrease in sensitivity of the imaging unit on the object value and the effect of the decrease in sensitivity of the imaging unit on the gain value, with respect to the brightness of the captured image adjusted by the calibration unit. [Explanation of Symbols]

[0053] 1: X-ray inspection equipment 10: Irradiation area 11: X-ray camera 12: Data management server 13: Arithmetic device 130: Calibration section 131: Projection Correction Unit 132:CT image generation section 133: Judgment Department 14: UI 140: Display section 2: Circuit board 21: Solder 3: Jig substrate 31: Metal parts

Claims

1. The imaging process involves irradiating the imaging unit with X-rays from the irradiation unit through the object to be inspected, thereby generating an image of the object to be inspected. An X-ray inspection method comprising a calibration step for adjusting the brightness of the image generated in the imaging step, Without placing anything between the irradiation unit and the imaging unit, the gain value is the brightness of the image obtained by imaging while the X-rays are directly irradiated from the irradiation unit to the imaging unit, The object value, which is the brightness of the captured image, is obtained by imaging the captured image while the X-rays are irradiated to the imaging unit through the object to be inspected from the irradiation unit, Using the offset value, which is the brightness of the captured image obtained by imaging without placing anything between the irradiation unit and the imaging unit and without irradiating with X-rays, In the calibration step, the brightness of the captured image is adjusted by multiplying the value obtained by subtracting the offset value from the object value by the value obtained by subtracting the offset value from the gain value by a predetermined constant. An X-ray inspection method further comprising a projection correction step, wherein a new brightness is obtained by adding, subtracting, or multiplying the brightness of the image image adjusted in the calibration step by a predetermined coefficient determined based on the difference between the brightness after the calibration step and the initial brightness of an object to be inspected for correction, for which the initial brightness is known, which is the brightness when there is no decrease in the sensitivity of the imaging unit.

2. A CT image generation step, which generates a CT image of the object to be inspected based on the new brightness obtained in the projection correction step, The X-ray inspection method according to claim 1, further comprising a determination step of determining the state of the object to be inspected based on the CT image generated in the CT image generation step.

3. The X-ray inspection method according to claim 2, further comprising a display step for displaying the result of the determination made in the aforementioned determination step.

4. The X-ray inspection method according to claim 1, characterized in that the object to be inspected for correction is a plurality of metals formed on a substrate.

5. The X-ray inspection method according to claim 4, characterized in that the initial brightness of the image of the object to be inspected for correction is the average value of the initial brightness of the metals included in the image among the plurality of metals.

6. An irradiation unit that irradiates X-rays through the object to be inspected, An imaging unit that senses the X-rays irradiated from the irradiation unit and generates an image of the object to be inspected, An X-ray inspection apparatus comprising: a calibration unit that adjusts the brightness of the image generated by the imaging unit, Without placing anything between the irradiation unit and the imaging unit, the gain value is the brightness of the image obtained by imaging while the X-rays are directly irradiated from the irradiation unit to the imaging unit, The object value, which is the brightness of the captured image, is obtained by imaging the captured image while the X-rays are irradiated to the imaging unit through the object to be inspected from the irradiation unit, Using the offset value, which is the brightness of the captured image obtained by imaging without placing anything between the irradiation unit and the imaging unit and without irradiating with X-rays, The calibration unit adjusts the brightness of the captured image by multiplying the value obtained by subtracting the offset value from the object value by the value obtained by subtracting the offset value from the gain value by a predetermined constant. An X-ray inspection apparatus further comprising a projection correction unit that acquires a new brightness by adding, subtracting, or multiplying the brightness of the image captured by the calibration unit with a predetermined coefficient determined based on the difference between the brightness of the image captured by the calibration unit and the initial brightness of an object to be inspected for correction, for which the initial brightness is known, which is the brightness when there is no decrease in the sensitivity of the imaging unit.

7. A CT image generation unit generates a CT image of the object to be inspected based on the new brightness acquired by the projection correction unit, The X-ray inspection apparatus according to claim 6, further comprising a determination unit that determines the state of the object to be inspected based on the CT image generated by the CT image generation unit.

8. The X-ray inspection apparatus according to claim 7, further comprising a display unit that displays the result determined by the determination unit.

9. The X-ray inspection apparatus according to claim 6, characterized in that the object to be inspected for correction is a plurality of metals formed on a substrate.

10. The X-ray inspection apparatus according to claim 9, characterized in that the initial brightness of the image of the object to be inspected for correction is the average value of the initial brightness of the metals included in the image among the plurality of metals.

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