JP2002162370A - Method and device for x-ray inspection of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for X-ray inspection of substrate and its usable device preventing any inspected area from overlapping as well as rapidly acquiring transfer imaging. SOLUTION: An X-ray source 23 obliquely radiating X-ray toward a horizontally-placed substrate 3 is furnished on the top of this substrate 3, and a linear X-ray sensor 25 detecting X-ray radiated from the X-ray source 23 to be transmitted through the substrate 3 is furnished on the bottom of the substrate 3, allowing relative displacement of the substrate 3 in horizontal direction opposed to both the X-ray source 23 and the linear X-ray sensor 25. Thus relatively shift the substrate 3 located between the X-ray source 23 and the linear X-ray sensor 25 in horizontal direction to image a transfer imaging of X-ray throughout the substrate 3 and then rotate the substrate 3 on a level surface by a certain angle, relatively shift the rotated substrate in horizontal direction again between the X-ray source 23 and the linear X-ray sensor 25 to image a transfer imaging of X-ray throughout the entire substrate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an inspection of a solder connection state of a mounted electronic component, for example, which makes an appearance inspection difficult.
The present invention relates to an X-ray inspection method for a substrate which enables observation using an X-ray transmission image and an X-ray inspection apparatus used therefor.

[0002]

2. Description of the Related Art In recent years, mounting of electronic components on a printed circuit board has been required to have higher and higher densities.
For example, a multilayer printed circuit board having a multilayer wiring pattern is used, or a double-sided mounting board on which electronic components are mounted at high density on both sides of the printed circuit board is used.
Also, for electronic components, a BGA (Ball Grid Array) or a CSP (Chip) in which a plurality of ball-shaped bumps made of solder or the like are provided in a vertical or horizontal lattice on the entire back surface of the LSI or a part thereof.
size package) is used. However, in such a multilayer printed board or a double-sided mounting board, it may not be possible to inspect the appearance of solder connection after mounting electronic components due to high-density mounting. Further, in the case of the connection structure using the back surface of the component, the solder ball portion inside the back surface of the component cannot be directly confirmed from the external appearance after mounting on the board. If small voids are generated in the solder balls, the reliability of the connection is affected by thermal deformation, so that inspection for finding these is important.

[0003] Therefore, conventionally, there has been proposed an X-ray inspection method for a substrate which irradiates the substrate with X-rays and obtains a transmission image of a portion to be inspected, thereby observing a solder connection portion which cannot be visually inspected. I have. In such an X-ray inspection method for a substrate, for example, X-rays are irradiated from one side of the substrate surface perpendicularly to the substrate surface, and X-rays transmitted through the substrate are provided on the other side. There is a vertical incidence type X-ray inspection method that obtains a transmission image of an inner connection portion that cannot be visually inspected from the outside by detecting with an X-ray sensor.

Further, other conventional X-ray inspection methods include:
Some are performed using a rotary X-ray inspection apparatus 61 shown in FIG. The rotary X-ray inspection apparatus 70 includes a stage 71 for holding the substrate 3 and an X-ray
An X-ray source 75 that irradiates the X-ray 73 and an X-ray sensor 77 that detects the X-ray 73 emitted from the X-ray source 75 and transmitted through the substrate 3
And an image processing unit 79 that obtains a transmission image by performing image processing on a detection signal from the X-ray sensor 77.

In the case of the rotary X-ray inspection apparatus 70, the X-rays 73 emitted from the X-ray source 75 can be emitted at a predetermined angle from different directions around the normal to the surface of the substrate 3. ing. Further, the X-ray source 75 and the X-ray sensor 77 can turn so as to draw a circular locus about the substrate normal, and operate in synchronization with each other. Conventionally, this X-ray source 75 irradiates an X-ray 73 to a local inspection target portion of the substrate 3, and an X-ray sensor 77 dedicated to a small area for detecting the X-ray 73 in the inspection target portion is provided. Had been used.

According to this, the X-ray 73 irradiated from the X-ray source 75 is detected by the X-ray sensor 77 after irradiating the solder connection portion to be inspected. FIG.
As shown in (a), the solder connection portion 81 on the surface of the substrate 3,
The solder connection portion 82 on the back surface has an X-ray absorption coefficient
Because it is larger, the transmitted image obtained by the image processing means 79 is displayed as an image darker than other portions.
The transmitted image makes it possible to inspect the connection state of the solder, which is difficult to visually recognize from the appearance.

[0007]

However, in the above-described X-ray inspection method using the vertical incidence method, for example, in the case of a double-sided mounting substrate or a multilayer substrate, as shown in FIG. When the connecting portions 81 and 82 are present on a straight line connecting the X-ray source and the X-ray sensor, the solder connecting portions 81 and 82 may overlap with each other, and it may be difficult to visually determine the inspection target portion based on the transmission image. Was. Further, in the inspection method using the rotary X-ray inspection apparatus 70 shown in FIG. 14, an X-ray source 75 for irradiating a small area on the substrate 3 with X-rays, Since the X-ray sensor 77 for detecting a line is used, when the number of inspection portions is large, the substrate 3, the X-ray source 75, and the X-ray sensor 77 need much time to move.
In order to inspect the entire substrate, it is necessary to repeatedly perform movement and X-ray detection over the entire surface of the substrate 3, and there is a problem that high-speed inspection cannot be performed.

The present invention has been made in view of the above circumstances, and provides an X-ray inspection method for a substrate and an X-ray inspection apparatus used for the same, which can prevent the inspection target portions from overlapping each other and can obtain a transmission image at a high speed. The purpose is to do.

[0009]

According to a first aspect of the present invention, there is provided a method of inspecting an X-ray of a substrate, comprising the steps of:
An X-ray source for emitting X-rays obliquely to the substrate is provided above the horizontally arranged substrate, and the X-ray source is provided below the substrate.
A linear X-ray sensor for detecting X-rays emitted from the source and transmitted through the substrate is provided, and the substrate is moved relative to the X-ray source and the linear X-ray sensor in the horizontal direction, so that the X of the substrate that captures X-ray transmission images
In the X-ray inspection method, after relatively moving the substrate disposed between the X-ray source and the linear X-ray sensor in the horizontal direction and capturing an X-ray transmission image over the entire surface of the substrate, The substrate is rotated at a predetermined angle on a horizontal plane, and the rotated substrate is relatively moved again in the horizontal direction between the X-ray source and the linear X-ray sensor, and X-rays are emitted over the entire surface of the substrate. Is characterized in that a transmission image is captured.

In this method of inspecting a substrate for X-rays, the substrate is relatively moved in the horizontal direction, X-rays are transmitted through the entire surface, and then rotated by a predetermined angle on a horizontal plane. Are relatively moved in the horizontal direction. Accordingly, the probability that the inspection target portions overlap or the inspection target portion and the non-inspection target portion overlap with each other is reduced as compared with the case where X-rays are transmitted through the substrate from only one direction. This makes it possible to easily obtain a transmission image of the portion to be inspected without any overlap, thereby enabling highly accurate inspection. Further, a transmission image of the entire inspection target portion can be obtained at a higher speed than a conventional method in which a transmission image of the entire substrate is obtained at one time, and transmission images of a small area are obtained by the number of inspection target portions.

According to a second aspect of the present invention, the substrate is irradiated with X-rays sequentially from a plurality of X-ray sources provided in different directions around the normal of the substrate.

In this method of inspecting a substrate for X-rays, the substrate is irradiated with X-rays sequentially from a plurality of X-ray sources, so that the X-rays are sequentially irradiated from different directions around the normal of the substrate, and from multiple directions at once. A transmission image by the incident X-ray can be obtained.

According to a third aspect of the present invention, in the X-ray inspection method for a substrate, a plurality of transmission images for the substrate are captured by irradiating the substrate with X-rays obliquely from different directions around a normal line of the substrate. An image is synthesized to obtain a planar image at an arbitrary thickness position of the substrate.

In this X-ray inspection method for a substrate, a plurality of transmission images of the substrate are captured by obliquely irradiating X-rays from different directions, and these transmission images are combined to obtain an arbitrary thickness of the substrate. A planar image at a position can be extracted. Thereby, for example, the degree of solder attachment to the solder connection portion of the mounted electronic component can be easily inspected.

According to a fourth aspect of the present invention, in the X-ray inspection method for a substrate, the plurality of planar images are image-processed so as to be arranged hierarchically in the order of the thickness of the substrate. It is characterized by being obtained by synthesizing a stereoscopic image.

In this X-ray inspection method for a substrate, a plurality of transmission images obtained by irradiating X-rays from different angles are image-processed so as to be arranged hierarchically in the order of the thickness of the substrate, and a plurality of planes arranged hierarchically in the order of the thickness. A three-dimensional image of the substrate can be obtained by synthesizing from the image, whereby the part to be inspected can be visually recognized in three dimensions, and the detailed shape of the part to be inspected can be easily confirmed.

According to a fifth aspect of the present invention, there is provided an X-ray inspection method comprising: providing an X-ray source for emitting X-rays obliquely from above a horizontally arranged substrate to the substrate; A linear X-ray sensor for detecting the generated X-rays is provided below the substrate, and the substrate is horizontally moved relative to the X-ray source and the linear X-ray sensor, so that the X-rays are oblique to the substrate. In the X-ray inspection method for a substrate that captures an irradiation transmission image, the X-ray emitted from the X-ray source is linearly irradiated onto the substrate so as to coincide with the center of a circumcircle of the horizontally arranged substrate. And moving the X-ray source on a circumference centered on a vertical axis passing through the center of the circumcircle, and moving the linear X-ray sensor along the X-ray linear irradiation area. Rotate and move in synchronization with the movement of the X-ray source And detecting transmitted X-rays transmitted through the substrate at a plurality of points, characterized in that a transmitted image over the entire surface of the substrate.

In this X-ray inspection method for a substrate, the X-ray source is turned on a circle around a vertical axis passing through the center of the circumcircle of the substrate, and the linear X-ray sensor is used to move the X-ray source. The substrate is rotated in synchronization with the substrate, and X-rays are transmitted from the X-ray source to the substrate at a plurality of locations on the circumference. Therefore, by rotating the X-ray source and the linear X-ray sensor, a transmission image over the entire surface of the substrate can be obtained at high speed and with high accuracy while the substrate is not transported and remains fixed.

According to a sixth aspect of the present invention, there is provided an X-ray inspection apparatus comprising: an X-ray source for emitting X-rays obliquely to a substrate; a linear X-ray sensor for detecting X-rays emitted from the X-ray source; The X
Moving means for horizontally moving a substrate horizontally mounted between a source and the linear X-ray sensor with respect to the X-ray source and the linear X-ray sensor; A rotation unit configured to rotate the substrate mounted on the substrate by a predetermined angle on a horizontal plane; and converting an X-ray detection signal obtained by the linear X-ray sensor into an image signal to obtain a transmission image over the entire surface of the substrate. Image processing means.

In this X-ray inspection apparatus for a substrate, the substrate is relatively moved in the horizontal direction by the moving means, X-rays are transmitted through the entire surface, and then rotated by a predetermined angle on a horizontal plane by the rotating means. And the linear X-ray sensor are relatively moved in the horizontal direction by the moving means. Accordingly, the probability that the inspection target portions overlap or the inspection target portion and the non-inspection target portion overlap with each other is reduced as compared with the case where X-rays are transmitted through the substrate from only one direction. This makes it possible to easily obtain a transmission image of the portion to be inspected without any overlap, thereby enabling highly accurate inspection. Further, a transmission image of the entire inspection target portion can be obtained at a higher speed than a conventional method in which a transmission image of the entire substrate is obtained at one time, and transmission images of a small area are obtained by the number of inspection target portions.

According to a seventh aspect of the present invention, the X-ray inspection apparatus includes a plurality of X-ray sources in different directions around a normal line of the substrate, and a shutter control means for sequentially irradiating X-rays from each X-ray source. The X-ray source is provided for each of the X-ray sources.

In this X-ray inspection apparatus, the detection signal from the linear X-ray sensor is controlled by performing on / off control using a shutter so that X-rays from any one of the X-ray sources irradiate the substrate. An image can be formed by cutting each X-ray source, and transmission images can be created by incident X-rays from each direction. As a result, transmitted images in which X-rays are incident from different directions can be obtained at one time by one transfer operation of the substrate by the moving means, and quick X-ray inspection can be performed.

An X-ray inspection apparatus according to claim 8, wherein an X-ray source that emits X-rays obliquely to the substrate, a linear X-ray sensor that detects X-rays emitted from the X-ray source, The X
The X-ray source is rotationally moved on a circumference centered on a vertical axis passing through the center of a circumcircle of the substrate with respect to a substrate horizontally placed between the X-ray source and the linear X-ray sensor. Along with
Rotating means for rotating the linear X-ray sensor in synchronization with the movement of the X-ray source along the linear irradiation area of X-rays, and an X-ray detection signal obtained by the linear X-ray sensor And an image processing means for converting the image into an image signal in accordance with a rotation angle of the rotation moving means to obtain a transmission image over the entire surface of the substrate.

[0024] In this X-ray inspection apparatus, the X-ray source is swiveled on a circumference around a vertical axis passing through the center of the circumscribed circle of the substrate by the rotary movement means, and the linear X-ray sensor is provided with an X-ray sensor. The substrate is rotated in synchronization with the movement of the source, and X-rays are transmitted from the X-ray source to the substrate at a plurality of locations on the circumference. Therefore, by rotating the X-ray source and the linear X-ray sensor, a transmission image over the entire surface of the substrate can be obtained at high speed and with high accuracy while the substrate is not transported and remains fixed.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a substrate X-ray inspection method and an X-ray inspection apparatus used in the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a configuration of a first embodiment of an X-ray inspection apparatus according to the present invention, FIG. 2 is a plan view showing a part of a transmission image obtained by the X-ray inspection apparatus of FIG. 1, and FIG. FIG. 4 is an explanatory diagram for obtaining a combined transmission image of a plane having a desired height from a plurality of transmission images. FIG. 4A is a plan view showing an X-ray irradiation direction around a normal to the substrate surface, and FIG. It is sectional drawing (b).

The X-ray inspection apparatus 20 used in the X-ray inspection method for a substrate according to the present embodiment includes an X-ray source 23, a linear X-ray sensor 25, a moving unit 27, and a rotating unit 29.
And an image processing means 31 as main components of the configuration.

The X-ray source 23 is arranged above the substrate 3,
The emitted X-rays 33 are defined with respect to the normal to the surface of the substrate 3 so that the X-rays are emitted from the X-ray emission port 35 and the transmitted X-rays from the substrate 3 are detected by the linear X-ray sensor 25. And is emitted downward at an angle of.

The linear X-ray sensor 25 is, for example, a scintillator type line sensor, and converts the X-rays 33 emitted from the X-ray source 23 and transmitted through the substrate 3 in a direction perpendicular to the moving direction of the moving means 27. The detection is performed by the arranged X-ray detection elements.

The moving means 27 is connected to the X-ray source 23
It is provided between the line sensor 25 and the substrate 3 is placed horizontally so as to be movable in the directions A and B in FIG. The moving means 27 includes an X-ray source 23 and a linear X-ray sensor 25.
And the substrate 3 may be relatively moved. Contrary to the configuration of the present embodiment, the substrate 3 is fixed, and the X-ray source 23 and the linear X-ray sensor are fixed to the fixed substrate 3. 25 may be moved in the horizontal direction of FIG.

Further, a rotating means 29 is attached to the moving means 27, and the rotating means 29 can rotate the mounting table or the like of the moving means 27 to rotate the mounted substrate 3 by a predetermined angle on a horizontal plane. It has become. The rotating means 29 includes the X-ray source 23 and the linear X-ray sensor 25.
And the substrate 3 may be relatively rotated. Contrary to the configuration of the present embodiment, the substrate 3 is fixed, and the X-ray source 23 and the linear X-ray sensor are fixed to the fixed substrate 3. 25 may rotate around the normal of the substrate 3.

The image processing means 31 converts an X-ray detection signal obtained by the linear X-ray sensor 25 into an image signal, and displays a transmission image of the substrate 3.
Therefore, the X-ray inspection apparatus 20 can irradiate the substrate 3 with X-rays in an oblique direction and display an image of the transmitted X-rays by the image processing means 31.

Next, an X-ray inspection method for the substrate 3 using the X-ray inspection apparatus 20 configured as described above will be described. The X-ray inspection apparatus 20 emits an X-ray 33 that spreads in a fan shape obliquely downward from the X-ray source 23 provided above the substrate 3,
Line X arranged along the direction of spread of X-rays below
The transmitted X-ray transmitted through the substrate 3 is detected by the line sensor 25.

In such an X-ray irradiation state, the X-ray source 23
When the substrate 3 is moved in the direction of arrow A in FIG. 1 by the moving means 27 between the X-ray sensor 25 and the linear X-ray sensor 25, the entire surface of the substrate 3 is irradiated with X-rays and the transmission X from the substrate 3 is transmitted. A line is detected. Thereafter, the substrate 3 is rotated by a predetermined angle on a horizontal plane by the rotating means 29. This rotation can be performed at an arbitrary angle. In the present embodiment, for example, the rotation of the substrate 3 is reversed so that the vertical and horizontal directions are reversed (two-dot chain line in FIG. 1).
Rotated at an angle of 0 °. Next, the rotated substrate 3
Is again moved in the horizontal direction between the X-ray source 23 and the linear X-ray sensor 25 again, and the entire surface of the substrate 3 is irradiated with X-rays 33 from different directions to detect transmitted X-rays.

Here, the steps of moving and rotating the substrate 3 are as follows.
For example, the substrate 3 is introduced from the right side of FIG.
Is moved to obtain a transmission image first, and then the procedure of rotating the substrate 3 to the left in FIG. 1 and moving the substrate 3 in the A direction to obtain the next transmission image again becomes efficient. In this way, the transmitted image obtained by obliquely irradiating the substrate 3 with X-rays from different directions on the outward path and the return path of the substrate 3 is shown in FIG.
(B), the probability that the inspection target part overlaps with another inspection target part or the inspection target part overlaps with the inspection target part is reduced. FIG. 2 is an enlarged view of a part of the substrate 2.

Next, a method of obtaining a plane image (cross-sectional image) of a predetermined height of the substrate 3 using the transmission images obtained by irradiating X-rays from different directions in total n times in this way will be described. I do. First, n obtained by irradiating X-rays from different directions
As shown in FIG. 3A, the transmitted images have n identical inspection target portions (solder connection portions) 15 and non-inspection target portions (metal portions) 17. These n images are not the same image, but are images in which the positional relationship between the inspection target portion 15 and the inspection target portion 17 is shifted. That is, the inspection target portion and the non-inspected portion present at a position away in the height direction of the substrate 3 by a distance h _a, the X-ray irradiation direction around the normal line of the substrate 3 side shown in FIG. 4 (a) φ, Fig. 4
When the X-ray irradiation angle with respect to the substrate 3 side as shown in (b) and theta, obtained as h _a × cosθ / sinθ only φ direction to the substrate thickness position (height) fraction of the shifted image.

Therefore, it is desired to confirm the soldering state by aligning the positions of n transmission images from the position of the reference mark which is invariable in the height direction of the substrate with reference to the position correction mark or the like on the substrate surface. The images are combined to obtain a planar image for the height. That is, for example, assuming that the height to be checked on the land is h _b , after positioning is performed using the mark based on each of the n images, the amount shifted in the φ direction by the irradiation angle θ is returned. As shown in FIG. 3B, h _b × cos θ /
The image is synthesized with the pixels shifted by sin θ. By shifting and combining the pixels of the n images in this way, the image of the cross section having the height h _b to be confirmed appears at the same position, while the other images are synthesized plane images dispersed at different positions. G is obtained. The pixel density difference of this composite plane image G, the height h _b of the cross-section of the image as shown in FIG. 3 (c), i.e., it is possible to isolate the other image and the inspection target portion 15.

By performing an inspection for determining the area, shape, and the like of the inspection target portion using the composite plane image G, the inspection target portion at an arbitrary position on the substrate 3 is affected by other non-inspection target portions. Without having to do it.

As described above, according to the X-ray inspection method of the present embodiment, after the substrate 3 is moved in the horizontal direction and X-rays are transmitted at the irradiation angle θ over the entire surface of the substrate 3, , And is again moved in the horizontal direction between the X-ray source 23 and the linear X-ray sensor 25. Therefore, as compared with the case where X-rays are transmitted through the substrate 3 from only one direction, the probability that the inspection target portions 15 or the inspection target portion 15 and the non-inspection target portion 17 overlap with each other is reduced. This makes it possible to easily obtain a transmission image of the inspection target portion 15 having no overlap, thereby enabling highly accurate inspection.
Further, a transmission image of the entire substrate 3 can be obtained at a higher speed than a conventional method in which a transmission image of the entire substrate 3 is obtained at one time, and transmission images of a small area are obtained by the number of the inspection portions 15. .

According to the above X-ray inspection apparatus 20,
Since the substrate 3 can be irradiated with X-rays at an arbitrary irradiation angle θ from an arbitrary direction φ, the inspection target portion 15 and the non-inspection target portion 17 can be irradiated.
Irradiation conditions that do not overlap with each other can be set freely from a wide angle range, and the types of substrates that can be inspected can be expanded.

Next, a modification of the first embodiment will be described. FIG. 5 is an explanatory diagram for obtaining a composite stereoscopic image from a plurality of planar images.

In this modification, a plurality of composite plane images at different thickness positions (heights) of the substrate 3 are obtained from the plurality of transmission images obtained as described above, and the plurality of composite plane images are By performing image processing so as to be hierarchically arranged in the order of thickness, a stereoscopic image is synthesized from a plurality of planar images hierarchically arranged in the order of height.

That is, as shown in FIG. 5, a composite plane image at an arbitrary height h _b of the substrate 3 is not limited to one image for one inspection target portion, but is at every arbitrary height interval Ps. By executing the X-ray irradiation respectively, an arbitrary height interval Ps
In each case, a total of m synthesized plane images G _{1 to} G _m are obtained. Then, by performing image processing for arranging the _m synthesized plane images G _{1 to} G _m at intervals Ps, the three-dimensional shape 1 in which the inspection target portion is shown as a voxel (volume pixel).
6 is obtained.

According to this X-ray inspection method, a plurality of combined plane images at different height positions on the board 3 are obtained, and a stereoscopic image of the board 3 is combined from the plurality of combined plane images arranged hierarchically in height order. Is done. As a result, the inspection target portion 15 can be visually recognized in three dimensions, and the detailed shape of the inspection target portion can be easily confirmed.

Next, a second embodiment of an X-ray inspection method for a substrate and an X-ray inspection apparatus used in the method according to the present invention will be described. 6 is a conceptual perspective view showing the configuration of the X-ray inspection apparatus of the present embodiment in which the X-ray source is located at the turning position a, FIG. 7 is an enlarged view of a main part showing the state of the front and back of the substrate shown in FIG. 8 to 11 are conceptual perspective views of an X-ray inspection apparatus in which the X-ray source is located at swiveling positions be to e. FIG. 12 is a perspective view showing an example of a board on which a plurality of corresponding components are mounted on the front and back surfaces. FIG. 13 is a plan view showing a transmission image of the substrate of FIG. 12 obtained in the second embodiment.

As schematically shown in FIG. 6, an X-ray inspection apparatus 40 used in the X-ray inspection method for a substrate in this embodiment includes an X-ray source 23, a linear X-ray sensor 25, It has a mounting table 43, a rotary moving unit 45, and an image processing unit 31 as main components of the configuration.

In the above configuration, the X-ray source 23, the linear X-ray sensor 25, and the image processing means 31 can be the same as those used in the first embodiment. What is necessary is just to hold 3 on a horizontal surface.

The rotation moving means 45 adjusts the center point 37a of the linear irradiation area 37 on the substrate 3 of the X-ray 33 emitted in a fan shape from the X-ray source 23 to coincide with the center of the circumcircle of the substrate 3. The X-ray source 23 is moved on a circumference 51 around a vertical axis 49 passing through the center of a circumscribed circle. Along with this, the linear X-ray sensor 25 is configured to rotate and move along the linear irradiation area 37 of the X-ray 33 in synchronization with the movement of the X-ray source 23.

Next, a method of inspecting the substrate 3 using the X-ray inspection apparatus 40 configured as described above will be described. From the X-ray source 23 provided above the substrate 3, X-rays 33 diverging in a fan shape toward the substrate 3 are emitted downward at a predetermined angle θ with respect to the normal to the substrate 3. This X-ray 33 is applied to the linear X-ray sensor 2 disposed along the linear irradiation area 37 on the substrate 3.
5 is detected. In this state, the midpoint 37a of the linear irradiation region 37 coincides with the center of the circumscribed circle of the substrate 3,
The X-ray source 23 is moved (turned) on a circumference 51 about a vertical axis 49 passing through the center of a circumscribed circle. At the same time, the linear X-ray sensor 25 is rotated along the linear irradiation area 37 in synchronization with the movement of the X-ray source 23.

In this embodiment, the circumference 51 shown in FIG.
From the position of the point a above, as shown in FIGS.
The X-ray 33 is transmitted through the substrate 3 at a plurality of points b, c, d, and e for each rotation angle of °. By emitting such an inclined X-ray 33 while rotating it on the circumference 51, for example, as shown in FIG. When the (metal part) 17 overlaps, first, in the transmission image by X-ray emission from the point a, the upper inspection target portion 15 and the lower non-inspection target portion 17 are arranged as shown in FIG. Will be obtained.

Similarly, the turning positions b, c, d
In the transmission image by the X-ray emission from the points e and e, the upper inspection target portion 15 and the lower non-inspection target portion 17 are obtained in the arrangement relationship shown in FIGS. 8 to 11B. Become. Therefore, in the case of the substrate 3 in which the upper surface components P _{1 to} P ₈ are mounted on the upper surface shown in FIG. 12 and the lower surface component is mounted at a corresponding position on the lower surface, the upper surface component and the lower surface component in the transmission image are the same as those in FIG. Are obtained at once with the arrangement shown in FIG.

According to the X-ray inspection method of this embodiment, the X-ray source 23 is connected to the vertical axis 49 passing through the center of the circumcircle of the substrate.
, And the linear X-ray sensor 25 is rotationally moved in synchronization with the movement of the X-ray source 23, and a plurality of points a and b on the circumference 51. point c,
At points d and e, the X-ray 33 is transmitted from the X-ray source 23 to the substrate 3. Therefore, the X-ray source 23 and the linear X-ray sensor 25
Is rotated by 180 °, a transmission image over the entire surface of the substrate can be obtained at high speed and with high accuracy while the substrate 3 is not transported and is kept in a fixed state.

Next, a third embodiment of an X-ray inspection method for a substrate and an X-ray inspection apparatus used therein according to the present invention will be described. FIG. 14 is a conceptual perspective view of the X-ray inspection apparatus of the present embodiment. In the X-ray inspection apparatus 60 of this embodiment, while the plurality of X-ray sources 24a, 24b, 24c,... Are provided at different positions above the substrate 3, the rotating means of the substrate 3 can be omitted. Other configurations are the same as those of the first embodiment.

According to the X-ray inspection apparatus 60, the transmitted X-rays emitted from the X-ray source and transmitted through the substrate 3 are transferred to the linear X-ray sensor 25 while the substrate 3 is transported by the moving means 27.
And the transmitted images incident from different directions
.. Can be obtained by one transfer operation by the number of the radiation sources 24a, 24b, 24c,. As an example of a specific inspection method, a shutter provided at each of the X-ray emission ports 35 of the X-ray sources 24a, 24b, and 24c may be configured such that only X-rays from any one of the X-ray sources are controlled by the shutter control means.
On / off control is performed so as to irradiate the light. In synchronization with the on / off control of the shutter, each of the X-ray sources 24a, 24b,
The transmitted X-rays emitted from the substrate 24c and transmitted through the substrate 3 are detected by the linear X-ray sensor 25. Then, the detection signal is divided for each X-ray source by the image processing means 31 to form an image, and the light is incident from each direction. The generated X-ray transmission images are respectively created.

As a result, transmitted images in which X-rays are incident from different directions can be obtained at one time by one transfer operation of the substrate by the moving means 27, and quick X-ray inspection can be performed. Although one linear X-ray sensor 25 is used in the configuration of the present embodiment, a configuration in which a plurality of linear X-ray sensors are provided corresponding to each of the X-ray sources 24a, 24b, 24c,. Is also good. In this case, there is no need to perform the process of separating the detection signals, and a higher speed can be achieved.

[0055]

As described above in detail, according to the method of inspecting a substrate for X-rays according to the present invention, the substrate in the horizontal direction is horizontally moved between the X-ray source and the linear X-ray sensor. After being moved to transmit X-rays over the entire surface of the substrate, this substrate is
Rotate a predetermined angle on the horizontal plane, and again
X-rays are transmitted relative to the substrate in the horizontal direction to transmit X-rays to the substrate, and a transmission image is obtained by the linear X-ray sensor. In comparison, the probability that the inspection target portions or the inspection target portion and the non-inspection target portion overlap with each other can be reduced, and a transmission image of the inspection target portion having no overlap can be obtained, and high-precision inspection can be performed. . Also, compared to the conventional method of obtaining the transmission images of the narrow area by the number of the inspection target portions, the transmission images of the entire substrate are obtained at once for each different angle, so that all the inspection targets regardless of the number of the inspection target portions are obtained. A transmission image of a part can be obtained at high speed.

According to the X-ray inspection apparatus according to the present invention, there is provided an X-ray inspection apparatus for obliquely irradiating a substrate with X-rays to obtain a transmission image, comprising: an X-ray source for emitting X-rays; A linear X-ray sensor for detecting X-rays emitted from the X-ray source;
Moving means for relatively moving a substrate placed between the source and the linear X-ray sensor; rotating means for rotating the substrate by a predetermined angle on a horizontal plane;
An image processing means for converting a line detection signal into an image signal to obtain a transmission image is provided, so that the substrate can be irradiated with X-rays in an oblique direction to the substrate surface and in any direction around the substrate normal. To reduce the probability that the portions to be inspected overlap or that the portions to be inspected and the non-inspected portions overlap,
A transmission image of the inspection target portion can be easily obtained. In addition, since the X-rays are transmitted over the entire surface of the substrate and the transmitted X-rays are detected by the linear X-ray sensor, a transmission image of the entire substrate can be obtained at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a configuration of an X-ray inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a part of a transmission image obtained by the X-ray inspection apparatus in FIG.

FIG. 3 is an explanatory diagram for obtaining a composite transmission image of a desired plane from a plurality of transmission images.

4A is a plan view showing an X-ray irradiation direction around a normal to a substrate surface, and FIG. 4B is a cross-sectional view showing an X-ray irradiation angle with respect to the substrate surface.

FIG. 5 is an explanatory diagram for obtaining a composite stereoscopic image from a plurality of planar images.

FIG. 6 is a conceptual perspective view illustrating a configuration of an X-ray inspection apparatus according to a second embodiment in which an X-ray source is located at a turning position a.

FIG. 7 is an enlarged view of a main part showing a state of the front and back of the substrate shown in FIG. 6;

FIG. 8 is a perspective view of the X-ray inspection apparatus in which the X-ray source is at the turning position b.

FIG. 9 is a perspective view of the X-ray inspection apparatus in which the X-ray source is at a turning position c.

FIG. 10 is a perspective view of the X-ray inspection apparatus in which the X-ray source is at a turning position d.

FIG. 11 is a perspective view of the X-ray inspection apparatus in which the X-ray source is at a turning position e.

FIG. 12 is a perspective view illustrating an example of a board on which a plurality of corresponding components are mounted on the front and back surfaces.

FIG. 13 is a plan view illustrating a transmission image of the substrate of FIG. 12 obtained in the second embodiment.

FIG. 14 is a conceptual perspective view illustrating a configuration of an X-ray inspection apparatus according to a third embodiment of the present invention.

FIG. 15 is a schematic configuration diagram of an X-ray inspection apparatus used in a conventional substrate X-ray inspection method.

FIG. 16 is a plan view of a transmission image obtained by the conventional device of FIG.

[Explanation of symbols]

 3 substrate 16 three-dimensional shape 20, 40, 60 X-ray inspection device 23 X-ray source 25 linear X-ray sensor 27 moving means 29 rotating means 31 image processing means 33 X-ray 37 linear irradiation area 37a midpoint 45 rotating moving means 49 Vertical axis 51 Circumference G Composite plane image Ps interval θ X-ray irradiation angle φ X-ray irradiation direction

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuyuki Kakishima 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 2G001 AA01 AA10 BA11 CA01 DA02 DA08 FA21 GA06 GA13 HA13 JA06 JA08 JA09 JA11 KA03 LA11 MA05 PA11 PA12

Claims (8)

[Claims] An X-ray source that emits X-rays obliquely to the substrate is provided above a horizontally arranged substrate, and an X-ray emitted from the X-ray source and transmitted through the substrate is provided below the substrate. A linear X-ray sensor for detecting X-rays, and by moving the substrate relative to the X-ray source and the linear X-ray sensor in the horizontal direction, X In the X-ray inspection method, after relatively moving the substrate disposed between the X-ray source and the linear X-ray sensor in the horizontal direction and capturing a transmission image of X-rays over the entire surface of the substrate, The substrate is rotated at a predetermined angle on a horizontal plane, and the rotated substrate is again rotated with the X-ray source and the linear X
An X-ray inspection method for a substrate, characterized in that the substrate is relatively moved in a horizontal direction between the X-ray sensor and an X-ray transmission image is taken over the entire surface of the substrate. 2. The X-ray inspection method for a substrate according to claim 1, wherein the substrate is irradiated with X-rays sequentially from a plurality of X-ray sources provided in different directions around the normal line of the substrate. 3. X from different directions around the normal to the substrate.
The line is irradiated obliquely, a plurality of transmission images for the substrate are captured, and the plurality of transmission images are combined to obtain a plane image at an arbitrary thickness position of the substrate. Item 3. An X-ray inspection method for a substrate according to Item 2. 4. The image processing wherein the plurality of planar images are hierarchically arranged in the order of the thickness of the substrate, and a stereoscopic image of the substrate is obtained from the plurality of planar images hierarchically arranged in the order of the thickness. The X-ray inspection method for a substrate according to claim 3. 5. An X-ray source for emitting X-rays obliquely from above a horizontally arranged substrate to the substrate is provided, and a linear X-ray for detecting X-rays emitted from the X-ray source and transmitted through the substrate is provided.
A line sensor is provided below the substrate, and the substrate is moved in the horizontal direction relative to the X-ray source and the linear X-ray sensor, thereby obtaining an X-ray oblique irradiation transmission image of the substrate. In the X-ray inspection method, X-rays emitted from the X-ray source are linearly irradiated toward the substrate so as to coincide with the center of a circumcircle of the horizontally arranged substrate, and the X-ray source is The linear X-ray sensor is moved on a circumference around a vertical axis passing through the center of a circumscribed circle, and the linear X-ray sensor is synchronized with the movement of the X-ray source so as to be along a linear irradiation area of X-rays. A method of inspecting an X-ray of a substrate, comprising rotating the substrate, detecting transmitted X-rays transmitted through the substrate at a plurality of locations on the circumference, and capturing a transmitted image over the entire surface of the substrate. 6. An X-ray source that emits X-rays obliquely to a substrate, a linear X-ray sensor that detects X-rays emitted from the X-ray source, the X-ray source and the linear X-ray sensor. Moving means for horizontally moving a substrate mounted between the X-ray sensor and the linear X-ray sensor with respect to the X-ray source and the linear X-ray sensor; Rotating means for rotating a predetermined angle on a horizontal plane, and image processing means for converting an X-ray detection signal obtained by the linear X-ray sensor into an image signal to obtain a transmission image over the entire surface of the substrate. An X-ray inspection apparatus, characterized in that: 7. A plurality of X-ray sources are provided in different directions around a normal line of the substrate, and shutter control means for sequentially irradiating X-rays from each X-ray source is provided in each of the X-ray sources. The X-ray inspection apparatus according to claim 6, wherein: 8. An X-ray source that emits X-rays obliquely to a substrate, a linear X-ray sensor that detects X-rays emitted from the X-ray source, the X-ray source and the linear X-rays. The X-ray source is rotated on a circumference centered on a vertical axis passing through the center of a circumcircle of the substrate with respect to a substrate horizontally placed between the X-ray source and the linear X-ray. A rotating means for rotating a sensor in synchronization with the movement of the X-ray source so as to be along a linear irradiation area of X-rays; and a rotating means for transmitting an X-ray detection signal obtained by the linear X-ray sensor. An X-ray inspection apparatus comprising: an image processing unit that converts the image signal into an image signal according to a rotation angle of the substrate to obtain a transmission image over the entire surface of the substrate.