JPH09251129A - Mirror for in-hole inspection and apparatus for in-hole inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily execute in-hole inspection of the through- hole formed on a substrate by forming the front end of a rod to be inserted into the aperture of this through-hole to a truncated pyramid or truncated cone shape and forming the slope of the front end as a mirror finished surface. SOLUTION: The front end of a mirror 14 for in-hole inspection is inserted into the through-hole 12 from one of the aperture. The mirror 14 for in-hole inspection is constituted by forming the front end of the rod 14a made of glass or metal to the truncated cone shape 14b and mirror finishing the surface of the truncated cone shape 14b. The projection of the entire circumference of the wall surface in the hole in the prescribed position of the through-hole 12 on the slope of the truncated cone shape 14b is made possible by forming the front end in such a manner. A CCD camera 16 is mounted above the other aperture of the through-hole 12. Since illumination light is cast from the other aperture of the through-hole 12, the peripheral edge of the circular shape 15 at the peak of the truncated cone shape 14b is distinctly projected and the image processing of the image of the inside wall surface in the hole with this projection as a reference is easily executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-hole inspection mirror and an in-hole inspection device. More specifically, the present invention relates to a hole inner wall surface of a through hole that penetrates through a substrate such as a wiring board on which a conductor pattern is formed. The present invention relates to an in-hole inspection mirror used for inspection and an in-hole inspection device.

[0002]

2. Description of the Related Art A multi-layer wiring board having copper conductor patterns formed in multiple layers has a large number of through holes 100 penetrating the board, as shown in FIG. The conductor patterns 102a, 102b, 102c, etc., which are arranged in multiple layers via an insulating layer made of glass-epoxy resin, are exposed on the inner wall surface of the through hole 100, and the exposed surface of each conductor pattern is exposed. Is plated with gold or the like to protect the conductor pattern. However, in the plating layer applied to the exposed surface of the conductor pattern exposed on the inner wall surface of the hole, a missing portion 104 may occur as shown in FIG. When a wiring substrate having such a missing portion 104 is used as a substrate for mounting a semiconductor device or a substrate such as a semiconductor element mounting package on which a semiconductor element is mounted, oxidation of the conductor pattern progresses from the missing portion 104 and the semiconductor May cause equipment failure. For this reason, it is necessary to inspect the state of the inner wall surface of the through hole. Usually, the inner diameter of the through hole is 1.0 mm or less and the length is about 4 to 5 mm. The entire surface of the inner wall surface of the hall cannot be inspected by any observation.

As an inspection apparatus for inspecting the hole inner wall surface of a through hole having a small diameter and a large aspect ratio (length / inner diameter) as described above, Japanese Patent Application Laid-Open No. 62-164012 discloses an inspection apparatus shown in FIG. Is proposed. The inspection apparatus shown in FIG. 8 has a through hole 108 penetrating the substrate 106.
In addition, the inclined surface 11 in which the tip of the rod 110a is inclined obliquely
The in-hole inspection mirror 110 formed in 0b is inserted, and the laser light transmitted through the half mirror 112 is reflected by the inclined surface 110b and projected onto the inner wall surface of the hole.
On the other hand, the laser light reflected by the inner wall surface of the hole is
The image is analyzed by being reflected by 10b and the half mirror 112 and incident on the CCD camera 114.

[0004]

According to the inspection apparatus shown in FIG. 8, the inner wall surface of a through hole having a small diameter and a large aspect ratio can be inspected, and a through hole having a defective portion can be detected in advance. It is possible to prevent a failure of a semiconductor device or the like that can be obtained in advance. However, in the inspection apparatus shown in FIG. 8, since the reflection surface of the in-hole inspection mirror 110 inserted into the through hole 108 is the inclined surface 110b that is inclined obliquely, in order to inspect the entire inner wall surface of the hole, Bar 11 of mirror 110 for inspection in hall
It is necessary to rotate 0a in the through hole 108 and move it up and down as shown in FIG. As described above, in order to impart the rotational movement and the vertical movement to the in-hole inspection mirror 110, a driving means for each movement is required.
Therefore, when a plurality of in-hole inspection mirrors 110 are used to inspect the inner wall surfaces of the plurality of through holes 108 in a short time, each in-hole inspection mirror 1 is used.
It is necessary to give rotational movement and vertical movement to 10, which further complicates the inspection apparatus. In addition, in-hole inspection mirror 110
It is necessary to make a part of the inner wall surface of the hole reflected on the inclined surface 110b continuous while rotating at a predetermined position to make the entire circumference of the inner wall surface of the hole continuous at a predetermined position, and the image processing is also complicated. Therefore, an object of the present invention is to provide an in-hole inspection mirror and an in-hole inspection device that can easily perform in-hole inspection of through holes formed in a substrate.

[0005]

DISCLOSURE OF THE INVENTION As a result of studies to solve the above problems, the present inventor made a truncated cone surface by using a truncated cone as a tip portion inserted into a through hole of an in-hole inspection mirror. The present inventors have found that the entire circumference of the inner wall surface of the hole can be imaged at a predetermined time, that it is not necessary to rotate the inspection mirror in the hole, and that the image processing is easy, and have arrived at the present invention. That is, the present invention relates to an in-hole inspection mirror used for inspecting an inner wall surface of a through hole that penetrates a substrate such as a wiring board on which a conductor pattern is formed, and is inserted from one of the openings of the through hole. The tip of the rod is formed in a truncated pyramid shape or a truncated cone shape, and the inclined surface of the tip is formed as a mirror surface so that the inner wall surface of the hole is projected on the inclined surface formed on the side surface of the tip. It is in the inspection mirror in the hall.

Further, according to the present invention, in an in-hole inspection device used for inspecting an inner wall surface of a through hole that penetrates a substrate such as a wiring board on which a conductor pattern is formed, the through hole is inserted from one of the openings of the through hole. The tip of the rod body is formed into a truncated pyramid shape or a truncated cone shape, the inclined surface forming the side surface of the tip portion is formed into a mirror surface, and the inner wall surface of the inserted through hole is inclined. The inspection mirror projected on the surface and the inclined surface of the inspection mirror inserted into the through hole are provided with illumination means for emitting illumination light from the other opening side of the through hole, and the through hole. Board or the inspection mirror,
A moving means that moves in the long axis direction of the through hole; and a display means that displays the inner wall surface of the hole projected from the other opening side of the through hole to the inclined surface of the inspection mirror. It is located in the hall inspection system.

In the present invention, by setting the diameter of the rod body of the portion inserted into the through hole to 30 to 90% of the diameter of the through hole to be inserted, the in-hole inspection mirror is attached to the inner wall surface of the through hole. Can be inserted without contact. Further, by setting the inclination angle of the inclined surface forming the side surface of the truncated pyramid or truncated cone-shaped tip portion to 30 to 60 °, the inner wall surface of the hole in the widest possible range is reduced in the inclined surface of the tip portion. It can be captured with distortion. Further, by making the display means display means for displaying the processed image processed by the image processing means, the image of the inner wall surface of the hole projected on the inclined surface of the inspection mirror input from the input means, The inner wall surface of the hall can be displayed as an image that can be easily inspected. Here, the "through hole" in the present invention means both a through hole that penetrates the substrate and a through hole that electrically connects between the conductor patterns formed in multiple layers in the substrate, The “frustum of a pyramid or the shape of a truncated cone” does not necessarily mean that the bottom surface and the top end surface are parallel to each other, and may be a shape in which the top end surface exists with respect to the bottom surface.

According to the present invention, the tip portion of the rod body forming the in-hole inspection mirror is formed into a truncated pyramid shape or a truncated cone shape, so that the entire circumference at a predetermined position of the hole inner wall surface is inclined. The image can be projected on the surface, and the rotation driving means for rotating the inspection mirror in the hall can be eliminated. Therefore, it is sufficient to provide a moving means for moving the substrate or the in-hole inspection mirror along the long axis direction of the through hole,
The inspection device in the hall can be simplified. Also, when performing image processing of the image of the inner wall surface of the hole projected on the inclined surface of the tip, since the tip is a truncated pyramid or a truncated cone,
It can be easily processed based on the peripheral edge of the top end face that can be clearly projected. As a result, a plurality of hole inspection mirrors can be simultaneously inserted into the through holes of the substrate, and the inspection of the inner wall surface of each hole can be performed easily and in a short time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings. FIG. 1 is an explanatory diagram for explaining the outline of the in-hole inspection device of the present invention. In FIG. 1, the substrate 10
A tip portion of the in-hole inspection mirror 14 is inserted from one of the openings of the through hole 12 into the through hole 12 penetrating therethrough. A CCD camera 16 used as an input means to the display means is mounted above the other opening of the through hole 12, and a distance between the CCD camera 16 and the in-hole inspection mirror 14 is maintained at a predetermined distance so that the hole is always provided. Both of them are fixed at a predetermined position so that the CCD camera 16 is focused on the internal inspection mirror 14. Therefore, moving means (described later) for moving the substrate 10 in the major axis direction of the through hole 12 (direction of arrow A) is provided. A magnifying lens 17 that magnifies the tip of the in-hole inspection mirror 14 is attached to the tip of the CCD camera 16.

The in-hole inspection mirror 14 shown in FIG.
As shown in (a) and (b), a rod body 1 made of glass or metal
The shape of the tip of 4a is a truncated cone 14b, and the surface of the truncated cone 14b is mirror-finished. The mirror finish may be performed simply by polishing, or may be performed by mirror vapor deposition such as aluminum vapor deposition. This mirror finish may be performed only on the inclined surface of the truncated cone 14b. In this case, the top end surface of the truncated cone 14b is not mirror-finished, but the boundary between the top end surface and the inclined surface can be sufficiently recognized in the image projected on the display means. In this way, by making the tip of the rod 14a the truncated cone 14b, the entire circumference of the hole inner wall surface at a predetermined position of the through hole 12 can be projected on the inclined surface of the truncated cone 14b. In addition, the CCD camera 16
Is mounted above the other opening of the through hole 12, the upper surface of the truncated cone 14b is projected in the image projected via the CCD camera 16 as shown in FIG. 2 (a). There is. Moreover, the illumination light passes through the holes 12
Since the light is emitted from the other opening, the peripheral edge of the top circular portion 15 of the truncated cone 14b is clearly projected, and when performing image processing of the image of the inner wall surface of the hole projected on the inclined surface of the truncated cone 14b. In addition, image processing can be easily performed based on the peripheral edge of the top circular portion 15.

As shown in FIG. 1, the rod body 14a constituting the in-hole inspection mirror 14 can be inserted into the inner wall surface of the through hole 12 in a non-contact state.
It is preferable that the inner wall surface of the hole 2 can be prevented from being damaged. For this purpose, it is preferable that the diameter B [Fig. 2 (a)] of the rod 14a is 30 to 90%, especially about 80% of the diameter of the through hole to be inserted. Here, the diameter B of the rod 14a is 30%
If it is less than this, the image of the inner wall surface of the hole projected on the inclined surface of the truncated cone 14b tends to be unclear, while if the diameter B of the rod 14a exceeds 90%, the through hole 12
When the rod 14a is inserted therein, the rod 14a tends to easily contact the inner wall surface of the through hole 12.
Further, in order to project the widest possible range of the inner wall surface of the hole on the inclined surface of the truncated cone 14b with a small distortion, the inclination angle α of the inclined surface of the truncated cone 14b shown in FIG. It is preferably 45 °.

FIG. 4 shows the change in the visual field width on the inner wall surface side of the hole when the inclination angle α of the inclined surface of the truncated cone 14b is changed while keeping the visual field width on the CCD camera 16 side constant. In FIG. 4, FIG. 4A shows the case where the inclination angle α is 45 °. In this case, the inner wall surface of the hole projected on the inclined surface is just beside the inclined surface, and the widths C and C on the inner wall surface side of the hole are
The visual field width D on the CD camera 16 side corresponds to 1: 1. On the other hand, as shown in FIGS. 4B and 4C, the inclination angle α is 45
When the angle is larger or smaller than 0 °, the inner wall surface of the hole projected on the inclined surface is obliquely above or obliquely below the inclined surface, and the width C on the inner wall surface side of the hole is larger than the visual field width D on the CCD camera 16 side. Becomes Therefore, as shown in FIG.
In FIG. 4C, the inclined surface of the truncated cone 14b is shown in FIG.
Compared with the case of (a), a wide range of the hole inner wall surface is projected. However, in the case of FIGS. 4B and 4C, the inclination angle α
When the angle becomes less than 30 ° or exceeds 60 °, it tends to be troublesome to specify the position of the inner wall surface of the hole projected on the inclined surface, and the peripheral edge of the visual field width D on the CCD camera 16 side The vicinity of the part tends to be easily distorted. Further, the processing of the truncated cone 14b tends to be difficult.

FIG. 5 shows an in-hole inspection apparatus in which the CCD camera 16 and the in-hole inspection mirror 14 shown in FIGS. 1 to 4 are assembled. The in-hole inspection device shown in FIG. 5 holds the moving means 22 for moving the substrate 10 in a predetermined direction, the in-hole inspection mirror 14 for observing the inner wall surface of the through hole 12, the CCD camera 16 and the like at predetermined positions. Holding means 24 is provided on the base 20. The moving means 22 includes a Y-axis table 22a and an X-axis table 22.
b and the Z-axis 22c, the substrate 10 is horizontally fixed to the substrate fixing table 26 provided on the Z-axis 22c. Therefore, the substrate 10 can move in the Y-axis direction and the X-axis direction, and the hole inner wall surface of any through hole 12 can be inspected. When inspecting, the substrate 10 is
By moving up and down in the axial direction, the distance between the in-hole inspection mirror 14 and the magnifying lens 17 of the CCD camera 16 can be kept constant, and a sharp image with a consistent focal length can always be obtained. Therefore, the in-hole inspection mirror 14 and the magnifying lens 17 of the CCD camera 16 are fixed at predetermined positions, and the substrate 10 in which the hole inspection mirror 14 is inserted into the through hole 12 is intermittently moved upward or downward. By moving in the direction, the entire inner wall surface of the through hole 12 can be inspected with a sharp image, and the inner wall surface of the hole can be precisely inspected. The substrate 10 may be continuously moved at a low speed in the upward direction or the downward direction.

In the apparatus shown in FIG. 5, an illumination means 28 is provided in the vicinity of the CCD camera 16 supported by the arm 32, and the illumination light from the illumination means 28 is refracted by a prism 30 to serve as coaxial incident illumination. The inside of the through hole 12 is irradiated. The illumination light emitted into the through hole 12 is reflected by the inclined surface of the truncated cone 14b of the in-hole inspection mirror 14 and is emitted to the inner wall surface of the hole. In this way, by adopting the coaxial epi-illumination, the brightness of the top circular portion 15 of the truncated cone 14b becomes higher than that of the inclined surface of the truncated cone 14b, and the peripheral edge of the top circular portion 15 becomes clear. Therefore, when the image of the inner wall surface of the hole captured by the CCD camera 16 is subjected to image processing, the image processing can be easily performed with the peripheral edge of the top circular portion 15 as a reference. Further, a sensor 36 such as a limit switch is provided on the arm 34 on which the in-hole inspection mirror 14 is erected so as to prevent the mirror from being damaged, and when the substrate 10 comes into contact with the sensor 36 when it is excessively lowered. The movement of the Z axis 22c is stopped. The arm 34
A plurality of in-hole inspection mirrors 14 are erected at the tip of the, and the inner wall surface of each of the plurality of through holes 12 can be inspected by making the CCD camera 16 movable in the horizontal direction. Is.

According to the in-hole inspection apparatus shown in FIGS. 1 to 5, a defect on the hole inner wall surface of the through hole 12, for example, plating applied to the exposed surface of the conductor pattern exposed on the hole inner wall surface as shown in FIG. It is possible to easily find a defect such as a missing portion 104 in the layer, or a missing portion in the through-hole plating applied to the entire inner wall surface of the through hole 12. Therefore, it is possible to prevent a failure of a product such as a semiconductor device due to the defect on the inner wall surface of the hole. In addition, the in-hole inspection mirror 14 can be easily inspected by fixing the in-hole inspection mirror 14 at a predetermined position.
It is not necessary to give the rotational movement and the vertical movement to, and the structure of the inspection device can be simplified. In the in-hole inspection device shown in FIGS. 1 to 5, the in-hole inspection mirror 14 is fixed at a predetermined position, but the substrate 10 is fixed at a predetermined position to move the in-hole inspection mirror 14 up and down. You may inspect the entire wall surface inside the hall. In this case, it is preferable that the CCD camera 16 also moves up and down while keeping a constant distance from the in-hole inspection mirror 14. As for the in-hole inspection mirror used in the in-hole inspection device of FIGS. 1 to 5 described above, the tip of the rod 14a is a truncated cone 14b.
Although it has been described above, a truncated pyramid can also be used.

[0016]

According to the present invention, since the structure of the in-hole inspection device can be simplified and the state of the hole inner wall surface of the through hole formed in the substrate can be easily inspected, defects in the hole inner wall surface can be easily made. It is discoverable. Therefore, it is possible to prevent a failure caused in the product due to such a defect.

[Brief description of drawings]

FIG. 1 is an explanatory view illustrating a state in which a hole inspection mirror of the present invention is inserted into a through hole.

FIG. 2 is a top view and a front view of the in-hole inspection mirror of the present invention.

FIG. 3 is a partial sectional view of a truncated cone of the in-hole inspection mirror shown in FIG.

FIG. 4 is an explanatory diagram for explaining a change in the visual field width on the inner wall surface side of the hole when the inclination angle α of the inclined surface of the truncated cone is changed while keeping the visual field width on the CCD camera side constant.

FIG. 5 is an explanatory diagram illustrating an outline of the in-hole inspection device of the present invention.

FIG. 6 is a partial cross-sectional view showing an example of a through hole.

FIG. 7 is an explanatory diagram illustrating a defective portion on the inner wall surface of the through hole.

FIG. 8 is an explanatory diagram for explaining an outline of a conventional in-hole inspection device.

[Explanation of symbols]

 10 substrate 12 through hole 14 in-hole inspection mirror 14a rod 14b truncated cone 15 top circular portion 16 CCD camera (camera device) 17 magnifying lens 22 moving device 28 lighting device α inclination angle

Claims (8)

[Claims] 1. An in-hole inspection mirror used for inspecting an inner wall surface of a through hole that penetrates a substrate such as a wiring substrate on which a conductor pattern is formed, and is inserted from one of the openings of the through hole. The tip of the rod is formed into a truncated pyramid shape or a truncated cone shape, and the inclined surface of the tip is formed into a mirror surface so that the inner wall surface of the hole is projected on the inclined surface forming the side surface of the tip. A hall inspection mirror that is characterized by that. 2. The in-hole inspection mirror according to claim 1, wherein the diameter of the rod at the portion inserted into the through hole is 30 to 90% of the diameter of the through hole to be inserted. 3. The inclination angle of the inclined surface formed at the tip is
The in-hole inspection mirror according to claim 1 or 2, which has an angle of 30 to 60 °. 4. An in-hole inspection apparatus used for inspecting an inner wall surface of a through hole that penetrates a substrate such as a wiring substrate having a conductor pattern formed thereon, and a rod inserted from one of the openings of the through hole. The tip of is formed in a truncated pyramid shape or a truncated cone shape,
The inclined surface forming the side surface of the tip portion is formed into a mirror surface,
Irradiation light is irradiated from the other opening side of the through hole to the inspection mirror in which the hole inner wall surface of the inserted through hole is projected on the inclined surface and the inclined surface of the inspection mirror inserted into the through hole. Illuminating means, moving means for moving the substrate having the through hole or the inspection mirror in the long axis direction of the through hole, and an inclined surface of the inspection mirror from the other opening side of the through hole An in-hall inspection device, comprising: an input unit for inputting the inner wall surface of the hole shown in FIG. 5. The display means is a display means for displaying a processed image obtained by processing the image of the inner wall surface of the hole projected on the inclined surface of the inspection mirror input from the input means by the image processing means. In-hole inspection device described. 6. The hall inspection device according to claim 4, wherein the illumination means is coaxial epi-illumination. 7. The in-hole inspection device according to claim 4, wherein the diameter of the rod body at the portion to be inserted into the through hole is 30 to 90% of the diameter of the through hole to be inserted. 8. The inclination angle of the inclined surface formed at the tip is
The in-hall inspection device according to any one of claims 4 to 7, which has an angle of 30 to 60 °.