JPS63191948A - Through hole inspection device - Google Patents

Abstract

PURPOSE:To reduce the whole size of an inspection device by providing an illumination means for illumination in a slanting direction from one end part, a detecting means for scattered light from the other end part, and a means which detects a defect in a through hole according to the intensity of the scattered light in the through hole. CONSTITUTION:The illumination means 10 consists of a semiconductor laser 101, a collimator lens 102, and a focus lens 103 and projects a laser spot 7 slantingly at an angle theta to the axial direction of the internal wall plating layer 2a of the through hole 2 of a printed board 1. The scattered light detecting means 11 consists of an objective 111 and a photodiode 112, and the intensity of the scattered light 8 which is incident on one end part of the internal wall plating layer 2a of the through hole 2 and reflected by the plating layer 2a is detected by the photodiode 112 which slants by an angle phi. If the plating layer 2a has a defect 2b, the intensity of the scattered light 8 decreases, so the intensity of this scattered light 8 is detected to decides whether or not the through hole 2 has a defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to, for example, a disconnection that exists in a plating layer applied to the inner surface of a through hole in a printed board.

The present invention relates to a through-hole inspection device that optically detects defects such as pinholes, and particularly relates to a through-hole inspection device that is inexpensive and suitable for improving reliability.

[Conventional technology]

Conventionally, through-holes have been formed in double-sided printed boards and multilayer printed boards on which electronic components are mounted for electrical connection between front and back printed wiring formed on these boards and between printed wiring in each layer.

The above-mentioned through hole is formed by forming a wiring pattern made of, for example, copper foil on both sides of the board, then forming a layer of, for example, copper on the inner wall of the through hole by electroless plating, and then layering, for example, a solder layer by electroplating. are completed by laminating them.

However, as the diameter of the through hole becomes smaller, it becomes difficult to form a plating layer on the inner wall, which tends to cause poor conduction. In addition, due to incomplete plating, pinholes, cracks, etc. may occur in some parts, and poor conductivity may occur after parts are mounted and operation begins. Such defects are difficult to detect at the beginning and appear as damage to the device during actual operation, often leading to extremely serious accidents. To prevent this, it is important to detect and eliminate such potential defects in advance.

Conventionally, a method as shown in FIG. 10, for example, has been used as a method for detecting minute defects such as wire breaks and cuts on the inner wall of a through hole as described above. That is, as shown in the figure, a parallel light beam 3 is projected onto the surface of the printed circuit board 1 on which the through hole 2 is formed, and the parallel light beam 3 is directly projected onto the through hole 2 to be inspected.
A light shielding roller 4 is provided to prevent the image from being projected. The parallel light beam 3 projected onto the printed board 1 is
It invades the inside of the printed board 1 and spreads while scattering.

When the inside of the through hole 2, which is shielded from light by the light shielding roller 4, is observed by a detection optical system consisting of a lens 5 and a line sensor 6, it is found that the defect 2b does not exist in the plating layer 2a formed on the inner wall of the through hole 2. If the plating layer 2a has a defect 2b, the printed board 1 is in a dark state, that is, no light is detected.
The light diffused inside the through hole 2 leaks from the defect 2b into the through hole 2, and as a result, the inside of the through hole 2 becomes a bright state, that is, a state where light can be detected. In this way,
The printed circuit board 1 is moved so that all the through holes to be inspected pass between the light shielding roller 4 and a detection optical system consisting of a lens 5 and a line sensor 6, and during this time, the leakage light into each through hole 2 is detected. The presence of the defect 2b is detected by detecting its presence or absence. Incidentally, related devices of this type are introduced, for example, in Japanese Patent Application Laid-open No. 75241/1983 and in the October 1985 issue of Electronic Materials, pages 127 to 130.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has the following problems.

In other words, (1) First problem: As shown in FIG. 11(a), if defects such as a severe decrease in the thickness of the inner wall plating N2a of the through hole 2 or poor surface roughness occur, the through hole 2
The light leaking inward cannot be detected at all, so it may be overlooked.

(2) Second problem As shown in FIG. 11(b), the wiring pattern 1b of each layer of the multilayer printed board 1 obstructs the progress of light inside the printed board 1, causing leakage into the through hole 2. The light becomes extremely weak.

Furthermore, even when the number of layers in a multilayer printed board increases, the light leaking into the through hole 2 becomes extremely weak.

As a result, there is a problem that the inspection speed decreases.

(3) Third problem: Since the test target is a printed board that has translucency, it cannot be applied to an object to be inspected that does not have translucency, so the scope of application is limited.

(4) Fourth problem: If the through-hole spacing changes due to a change in the type of printed circuit board, the delay speed must be changed each time. It is difficult to set a delay amount for a through hole formed at a certain position.

Also, if the speed at which the printed board is moved changes,
It is difficult to detect the position of the through hole while maintaining high reliability.

(5) Fifth problem: If the printed board has warps or undulations, the line sensor may be affected by defocusing, and the light-shielding roller that blocks light from one end of the through-hole will not come into close contact with the printed board accurately. As a result, light may enter the through hole and cause erroneous judgments.

To prevent this, it is necessary to newly provide a defocus detection mechanism.

However, the conventional apparatus requires a defocus detection mechanism having an optical system completely separate from the defect determination mechanism, which causes problems such as an increase in the size of the entire apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a through-hole inspection device that has a simple configuration, is capable of automatically detecting through-holes at high speed, and with high reliability.

[Means for solving problems]

The first to third problems mentioned above are the illumination means that illuminates the inside of the through hole from an oblique direction at one end thereof, the scattered light detection means that detects the scattered light from the other end of the through hole in an oblique direction,
This is achieved by providing a defect detection means for detecting a defect in the through-hole based on the intensity of the scattered light from the scattered light detection means. position detection for detecting the position of the through hole based on the intensity of transmitted light that, when incident on one end of the inner wall of the through hole, is reflected only once, directly passes through the through hole, and exits from the other end; The fifth problem is achieved by providing a defocus detecting means for detecting defocus based on the position where the illumination light spots on the member having the through hole.

[Effect]

The through-hole inspection device according to the present invention has the principle of
As shown in the figure, when illumination light 7 is incident on one end of the through hole 2 from an illumination means (not shown) disposed obliquely at an angle θ with respect to the axial direction of the through hole 2, the illumination light 7 propagates along the inner wall of the through hole 2 while repeatedly reflecting on the inner wall plating layer 2a of the through hole 2 and reaches the other end.

If the wire breaks in the middle of the inner wall of through hole 2 above.

If there is a defect 2b such as a pinhole, the plating layer 2a is not formed due to air bubbles or the like, or the thickness of the plating layer 2a is extremely thin, so the scattered light 8 becomes weaker and the intensity of the scattered light 80 decreases. becomes smaller.

Therefore, by detecting the intensity of the scattered light from the other end of the inner wall of the through hole 2, the presence or absence of the defect 2b on the inner wall of the through hole 2 can be detected based on its strength.

In addition, the illumination light 7 from the illumination means enters one end of the inner wall of the through hole 2, is reflected only once, passes through the through hole 2, and detects the transmitted light 9a emerging from the other end. The position of the through hole 2 can be detected. At the same time, if the through hole 2 is present, the transmitted light 9a from the other end will be large, and if the through hole 2 is not present, the transmitted light 9a will not come out from the other end, so based on the position information of the through hole 2, It can be determined whether the scattered light 8 has propagated through the inner wall of the through hole 2 or has passed through other areas.

Further, when the illumination light 7 from the illumination means is a slit light or a spot light and enters one end of the inner wall of the through hole 2, if the printed board 1 has warpage or undulation, the illumination light 7 shown in FIG. As shown in bl, the vertical movement amount ΔZ of the surface 1a of the printed board 1 corresponds to the amount Δ
The spot position of the illumination slit light 7 changes by l, so by detecting the spot position of the illumination slit light 7, the vertical amount ΔZ of the printed board 1 can be detected, and the amount of movement of the illumination slit light 7 can be detected. Δ
By moving the printed board 1 up and down in accordance with i, the positional relationship between the illumination means, the scattered light detection means, the position detection means, and the printed board 1 can always be maintained constant.

Therefore, the through-hole inspection device according to the present invention has 1
Defect inspection by common use of two illumination means,
Since the position of the through-hole and the defocus can be detected, the configuration is simple, the overall shape of the device can be made smaller, and the cost can be lowered.In addition, one end of the through-hole can be shielded from light as in the conventional method. Since a mechanism to do this is required, it is possible to prevent a decrease in the reliability of contact with the printed board.

Next, FIG. 9 shows the basic configuration of the illumination means, scattered light detection means, and defect detection means, which are common parts of the through-hole inspection apparatus according to the present invention, that is, the case where one of the above means is installed for one through-hole. This is explained by:

As shown in FIG. 9, the illumination means rule is that the semiconductor laser 101
, colmeter lens 102 , and focus lens 10
A laser spot 7 focused to a diameter of several μm to several tens of μm is directed toward one end of the inner wall plating layer 2a of the through hole 2 of the printed board 1 at an angle θ with respect to the axial direction of the through hole 2. It is irradiated at an angle. Incidentally, the incident angle θ of the laser spot 7 on the through hole 2 is set such that the laser spot 7 is irradiated onto the plating layer 2a.
An”” (aspect ratio), it is possible to select any angle θ. However, the above aspect ratio is the diameter of the through hole 2/thickness of the printed board 1.

The scattered light detection means is composed of an objective lens 111 and a photodiode 112, and detects the scattered light 8 obtained as a result of being incident on one end of the inner wall plated layer 2a of the through hole 2 and reflected by the plated layer 2a. The photodiode 112, which is inclined at an angle ψ with respect to the axial direction of the through hole 2 toward the other end of the inner wall plated layer 2a of the hole 2, detects the intensity. In other words, the through hole 2
If there is a defect 2b in the inner wall plating layer 2a, scattered light 8
Since the intensity of the scattered light 8 becomes weak, by detecting the intensity of the scattered light 8, it can be determined whether the through hole 2 is defective or normal. Note that the scattered light detection angle ψ is reflected only once on the plated layer 2a and directly passes through the through hole 2.
It is necessary that ψ<tan"' (aspect ratio) so as not to detect the passing light (not shown) exiting from the other end of the inner wall. Also, the scattered light detecting means must be located only at a position parallel to the plane of the paper. The position may be perpendicular to the plane of the paper, or any position that looks into the through hole 2. This is because the scattered light 8 from the through hole 2 is directed in the normal direction of the printed board 1. This is because it is symmetrical with respect to the axis of the through hole 2.

For example, when the diameter of the through hole 2 is φ350 μm and θ−ψ=45°, the positioning of the printed board 1 is ±12
0 μm (350 μm4) is sufficient, which is a sufficiently achievable value.

The defect detection means (2), whose detailed structure will be described later, discriminates between defective through holes and normal through holes based on the output signal from the photodiode 112 of the scattered light detection angle.

Note that in FIG. 9 above, a semiconductor laser 101 is used for illumination.
Although a case is shown in which the illumination light source is used, the present invention is not limited thereto, and any light source that can be used as an illumination light source, such as a He-Ne laser, may be used.

Further, although a case is shown in which a photodiode 112 is used as the scattered light detection means, the present invention is not limited to this, and any spot type detector such as a photomultiplier may be used.

〔Example〕

1 to 6 showing one embodiment of the present invention will be described below.

In FIG. 1, Retsu is an illumination means, Dan is a scattered light detection means,
Hi is a defect detection means, U is a position detection means, and shell is a defocus detection means.

The illumination means is composed of a semiconductor laser 101 and three cylindrical lenses 104, 105, and 106, and its optical axis is inclined at an angle θ with respect to the axial direction of the through hole 2. For example, the slit length is 40 mm, the slit is Laser slit light 7 having a width of 50 μm is simultaneously irradiated onto one end of the inner wall of a large number of through holes 2 formed in a printed board 1.

Further, as shown in FIG. 2, the cylindrical lens 104 on the semiconductor laser 101 side is connected to the semiconductor laser 1
The spot of the illumination laser beam 7 from 01 is spread in one direction,
The cylindrical lens 105 located in the center converts the illumination laser beam 7 into a parallel beam, and the cylindrical lens 106 located on the printed board 1 side converts the illumination laser beam 7 into a parallel beam.
It is formed so that the light is condensed into a slit shape and simultaneously irradiates a plurality of through holes 2. Incidentally, the inclination angle θ of the optical axis of the illumination laser beam 7 is set such that the illumination laser beam 7 is irradiated onto the inner wall plating layer 2a of the through hole 2.
>tan-'C aspect ratio (through-hole diameter/thickness of printed board)], any angle can be selected.

The scattered light detection means is composed of an objective lens 111 and a linear image sensor 112, and the optical axis is inclined by an angle ψ with respect to the axial direction of the through hole 2. The illumination laser beams 7 simultaneously incident on one end of the inner wall of the through-hole 2 are reflected by the inner wall plating layer 2a of the through-hole 2, become scattered light 8, and move to the other end of the linear image sensor via the objective lens 111. 112 , the linear image sensor 112 simultaneously detects the intensity of the scattered light 8 from within the multiple through holes 2 . That is, if there is a defect 2b in the inner wall plating layer 2a of the through hole 2, the incident light 7 reflected on the inner wall plating layer 2a of the through hole is not reflected by the defect 2b, so that the other end of the inner wall of the through hole 2 The intensity of the scattered light 8 that enters the objective lens 111 becomes weaker.

Therefore, by detecting the intensity of the scattered light 8 with the linear image sensor 112, it is possible to simultaneously detect whether or not there is a defect 2b in the inner wall plating layer 2a of a large number of through holes 2.

Incidentally, the inclination angle ψ of the optical axis line is such that out of the laser light reflected from the inner wall plating layer 2b of the through hole 2, the transmitted light 9a that directly passes through the through hole 2 without being scattered and exits from the other end is not detected. ψ> ja to make it
It is necessary that the aspect ratio is n-' (aspect ratio).

The position detecting means U is composed of an objective lens 131 and a linear image sensor 132, and its optical axis is inclined by an angle ψ with respect to the axial direction of the through hole 2, and one end of the inner wall of the through hole 2 Of the laser light that has entered the inner wall plating layer 2a only once, the intensity of the transmitted light 9a that directly passes through the through-hole and exits from the other end is measured through the objective lens 131 to the linear image sensor 32.
The position data is detected and outputted to the binarization circuit 121 of the defect detection means.

Incidentally, the inclination angle η of the objective lens 131 and the linear image sensor 32 is set at η knee tan- because only the transmitted light 9a from inside the through hole 2 is directly detected.
' (aspect ratio).

Furthermore, the above-mentioned inclination angle η and O η<tari-' (aspect ratio).

The defect detection means binarizes the output from the linear image 132 of the position detection means by a binarization circuit 121, as shown in FIG. 3(b). That is,
The binarization circuit 121 is the linear image sensor 3.
There is an output only when the output from the through hole 2 is equal to or higher than a preset value, and this allows the position of the through hole 2 to be known. Based on the positional data of the through hole 2 obtained in this way, the maximum detection area generation circuit 122 generates an area where the maximum value is to be obtained from the output of the linear image 112 of the scattered light detection means, and using this tanning, After that, the maximum value of the output of the linear image sensor 112, which is also the scattered light detection means, is determined by the maximum detection circuit 123, and then the maximum value of the output of the linear image sensor 112 is binarized by the binarization circuit 124 to output a defect. The defect 2b in the through-hole 2 is detected by obtaining the value.

The focus shift detection means (2) includes the objective lens 141. Cylindrical lens 142. Linear image sensor 143° focus shift detection circuit 144 and printed board Z control circuit 1
45, and its optical axis is inclined at an angle δ equal to the inclination angle θ for the illumination means with respect to the axial direction of the through hole 2 on the other end side of the inner wall of the through hole 2, and The slit-shaped illumination laser beam 7 from the illumination means is incident on the printed board 1 and the position of the reflected light 9b is determined by the objective lens 141, the cylindrical lens 142. The defocus detection circuit 144 detects the defocus through the linear image sensor 143, and the printed board Z control circuit 145 moves the printed board 1 in the vertical Z direction according to the defocus amount (movement amount) Δβ. That is, the fourth
As shown in Figures (a) and (b), there is a wiring pattern (not shown) on the surface 1a of the printed board 1, so in order to avoid being affected by diffused reflection components due to the edges of the wiring pattern, the above-mentioned The slit-shaped laser beam reflected by the cylindrical lens 142 is focused on one point, and an image is formed on the linear image sensor 143. At this time, the surface 1a of the printed board 1 is warped.

When the linear image sensor 143 moves up and down by ΔZ due to waviness or the like, the spot position 1 at which the illumination laser beam from the illumination means is incident on one end of the inner wall of the through hole 2 of the printed board 1 is Δl= ΔZ/co
Move by sθ. By moving the printed board 1 up and down by a device (not shown) according to the amount of movement Δβ, the positional relationship between the illuminating means measuring scattered light detecting means 1 and the printed board 1 is maintained constant. and highly accurate detection. Although it has been stated that the inclination angle δ of the optical axis line is equal to the inclination angle θ of the illumination means (3), the wiring pattern 1b on the front and back surfaces of the printed board 1
If the reflectance of the substrate is significantly different from that of the base, ψ≠θ may be used. Further, the objective lens 27 used has a magnification of equal magnification (IX). Furthermore, for positioning the printed board 1, for example, the diameter of the through hole 2 is φ350 μm.
, ±120 μm (3
50 μm/4), which can be sufficiently realized.

Next, FIG. 5 showing another embodiment of the illumination means will be described.

In FIG. 5, the illumination means 10a is a semiconductor laser 101.
, beam expander 107. polycon mirror 108,
It is composed of an fθ lens 109 and a cylindrical lens 110, and is configured to scan a laser spot O and simultaneously irradiate one end of the inner wall of a plurality of through holes 2 formed on the printed board 1.

The cylindrical lens 110 is used to correct the inclination of the mirror surface of the polygon mirror 108, and the polygon mirror 108 and the image 1a of the print vi1 are in an imaging relationship with respect to the cylindrical lens 110.

Furthermore, when CCDs are used for the linear image sensor 112 of the scattered light detection means 11a and the linear image sensor 132 of the position detection means 13a, it is necessary to synchronize the self-scanning of the CCD with the laser scanning by the polycon mirror 108. , Naifetuji 113. Mirror 114. A photodetector 115 is used to detect tamping in which the laser beam is blocked by the knife 113;
The above-described timing is applied as a start pulse to the above-mentioned COD to drive the above-mentioned CCD.

Therefore, according to this embodiment, illumination with uniform illuminance can be performed, and thereby the scattered light detection means 11a can detect scattered light with high precision.

In this embodiment, the polygon mirror 108 is formed to scan the laser beam onto the imaging surface la of the printed board 1, but the invention is not limited to this. It is also possible to scan using a galvanometer.

Also, the cylindrical lens 104°10 shown in Figure 2
It is also possible to use a light deflection element as a method without a mechanical drive unit, similar to the method using the combination of Nos. 5 and 106. In this case, the optical deflection element uses the anisotropic black diffraction phenomenon of a single crystal of tellurium dioxide (TeOz), for example, and can diffract the laser beam and scan the laser beam.

Next, FIG. 6 (alCb
) will be explained.

Fig. 6(a) (In BL, Japanese Patent Application Laid-Open No. 59-9329
The method described in detail in No. 3 can also be applied as lighting for through-hole inspection. That is, in FIG. 6, the light emitting diode 116 is of a high output type that emits infrared light. Since the maximum sensitivity wavelength of a linear image sensor is usually around 800 nm, detection sensitivity can be maximized by using a light emitting diode of this wavelength. Further, the light emitting diodes 116 are aligned in a line along the longitudinal direction of the plurality of cylindrical lenses 117. As shown in FIG. 6(a), the light emitting diode 116 and the slit 118 are in an imaging relationship with respect to the cylindrical lens 119, and the position of the image 1a is at the position of a through hole (not shown) in the printed board 1. Set and slit 11
8 and the imaging lens 119 are in an imaging relationship.

Therefore, in this embodiment, the light emitting diode 11
The light 120 emitted from 6 can be efficiently focused to form a slit. Note that this pickpocket light is irradiated obliquely to the imaging surface 1a of the printed board 1, as shown in FIG.

Next, FIG. 7 showing still another embodiment of the illumination means will be described.

In FIG. 7, the light emitting diode 116 is connected to the slit 1.
A plurality of slits are arranged along the slit 118 and the imaging surface 1.
a has an imaging relationship with respect to the imaging lens 119. Further, the cylindrical lens 117 is inserted between the imaging lens 119 and the slit 118 so that the slit light 120 does not become uneven on the image la.

Therefore, in this embodiment, the length in the optical axis direction can be shortened.

〔Effect of the invention〕

According to the present invention, defects such as disconnections and cuts in the inner wall of a through hole provided in a printed board, the position of the through hole, and the vertical position of the printed board are automatically detected using illumination light from a single illumination means. Since it can be detected, the configuration can be simplified, the overall size of the device can be made smaller, the cost can be lowered, and automation and higher speed can be achieved.

Further, unlike the conventional structure, there is no need for a mechanism for shielding one end of the through hole from light, so that it is possible to prevent a decrease in the reliability of contact with the printed board.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a through-hole inspection device as an embodiment of the present invention, FIG. 2 is an enlarged view of the illumination means 1, scattered light detection means, and defect detection means in FIG. 1, and FIG. FIG. 3 is an explanatory diagram of the defect detection means shown in the figure, in which (a) is a circuit configuration diagram; (a) is a circuit configuration diagram;
b) is an explanatory diagram showing the defect detection method, FIG. 4 is an explanatory diagram of the defocus detection means shown in FIG. 1, where (a) is a perspective view, (b) is a plan view, and FIG. 5 is an illumination FIG. 6 is a diagram showing another embodiment of the illumination means, and fa) is a plan view. (b) is a front view, FIG. 7 is a diagram showing another embodiment of the illumination means, (a) is a plan view, (b) is a front view, and FIG. 8 is a detailed view of the present invention. Figure 9 is a diagram for explaining the principle of the illumination means and scattered light detection means of the present invention, Figure 10 is a diagram explaining the problems of the conventional through-hole inspection device, and Figure 11 is the problem. Point explanatory diagram (a)
FIG. 5 is a diagram for explaining a defect in the inner wall plating layer, and FIG. 2('b) is a diagram for explaining that light is weakened by a laminated pattern. 1...Printed board, 2...Through hole, 7...
Illumination slit light, 8...scattered light, 9a...transmitted light,
9b...Reflected light, ■=--Illuminating means, D...Scattering detection means, Fertilizer...Defect detection means, ■...Position detection means, ■...Focal shift detection means. Agent Patent Attorney Tadashi Akimoto Real 1st figure illumination + 1,400,000,000 points failure of 1,400,000 points Figure 1 70 rin ← Wa i 2 through storage] Hand cuff and U number of momme muddy itching out hand throw π1 detection means Fig. 3 12ke ratio means two 123L pukoi b switch concave f-shape μ m24 z detective i otorotohaku 4 Figure (cl) (b) 7 month butsumei susozu I-ya 9b anti-mimushi 14 kog, su・re: #: Dete-yaku 141 Sentence 1 # Lens 142 Siri Soru Tonsu 143 Linyi completed image in Figure 5 Eclipse illumination means U 做RAN范Detection now Ding roi I standing 1 detection + setting Figure 6 (a> (bund electronic name) Image rabbit 116
・Nodoor 19 Gakuname Izoishishi 120 Relaxation Figure 7 (a) (b) 1q Hōmenmen 116 Keikishi 1' Ioto. 118 Nu, Su, Nodo 119 Mulberry 1 Denshi “Nonu, ゛120 Suso Sol-i L 1 Flint piece 9 Transmission light. 2 Through hole 10 Tadashi Tsutsute role 7 Praise Meiyu
11 Hatred Mukoo School Dekikan 8J & Tongue Princess
12 Missing J Saisai? Figure 10 Figure 11

Claims (1)

[Scope of Claims] 1. Illumination means for illuminating the inside of the through hole from an oblique direction at one end thereof, and the illumination light from this illumination means is reflected from the other end in an oblique outward direction while reflecting on the inner wall of the through hole. A through hole characterized in that it is provided with a scattered light detecting means for detecting the intensity of the scattered light, and a defect detecting means for detecting a defect in the through hole based on the intensity of the scattered light from the scattered light detecting means. Inspection equipment. 2. An illumination means for illuminating the inside of the through hole from an oblique direction at one end thereof, and detecting the intensity of the scattered light that is reflected from the other end in an oblique outward direction while the illumination light from this illumination means is reflected on the inner wall of the through hole. a scattered light detection means for detecting a defect in the through hole based on the intensity of the scattered light from the scattered light detection means; and a defect detection means for detecting a defect in the through hole based on the intensity of the scattered light from the scattered light detection means; When it is incident, 1
A through-hole inspection characterized in that it is provided with a position detection means for detecting the position of the through-hole based on the intensity of the transmitted light that is directly reflected inside the through-hole and exits outside from the other end after being reflected twice. Device. 3. An illumination means for illuminating the inside of the through hole from an oblique direction at one end thereof, and the intensity of the scattered light reflected from the other end in an oblique outward direction from the other end while the illumination light from this illumination means is reflected on the inner wall of the through hole. a scattered light detection means for detecting; a defect detection means for detecting a defect in the through hole based on the intensity of the scattered light from the scattered light detection means; and illumination light from the illumination means entering the member having the through hole. 1. A through-hole inspection device comprising: a defocus detection means for detecting defocus from a position where the defocus is detected. 4. The through-hole inspection device according to claim 1, 2, or 3, characterized in that the illumination light from the illumination means is configured to be condensed into a spot for illumination. 5. The through-hole inspection device according to claim 1, 2, or 3, characterized in that the illumination light from the illumination means is configured to be condensed into a slit shape for illumination. 6. The through-hole inspection device according to claim 1, 2, or 3, characterized in that the illumination light from the illumination means is configured to scan in one direction and illuminate in a slit shape. .