JP3166984B2 - Inspection method and device for through hole filling condition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a through-hole formed on a printed wiring board (including a wiring board formed of ceramic or the like) for electrically connecting front and back wirings and the like.
The present invention relates to a through hole filling state inspection method and apparatus for inspecting each hole, and in particular, a defect filling state of an electrically conductive substance as a filler in each through hole and its defect type can be identified. The present invention relates to a method and an apparatus for inspecting a filled state of through-holes, which are detected in a state where they are set.

[0002]

2. Description of the Related Art In a multilayer wiring board made of ceramics or the like, a large number of through-holes are formed on the board for electrical connection between front and back printed wirings formed on the board or between printed wirings of each layer. Holes (through-holes) are generally formed, and each of the through-holes is filled with a substance having good electrical conductivity (generally, fine metal particles such as tungsten W, molybdenum Mb, and copper Cu). Thus, electrical connection between front and back printed wirings and between printed wirings of each layer is achieved. By the way, as a method for inspecting the filled state of the through hole of the green sheet used for the ceramic multilayer wiring board, a method described in, for example, JP-A-63-241344 has been known. In this case, while the inspected substrate surface is illuminated obliquely, reflected light from the inspected substrate surface is detected, that is, an image of the inspected substrate surface is detected and extracted from the image. From the contrast between the light and dark and the shadow image between the substrate and the filling material, a defect in the filling state of the filling material is determined for each through hole.

[0003]

However, in the case of the above publication, specularly reflected light from a part of the surface of the metal fine particles as the filler is detected brightly, and the entire filler is not necessarily uniformly darkened. In some cases, it may be erroneously detected that the through hole has an insufficient filling defect or the like, even though the filling state in the through hole is normal. In order to avoid such erroneous detection, even if the whole filling is not always detected as dark uniformly, if the filling state is permitted to be normal, foreign substances such as dust may be added to the filling. In this case, the defective through-hole could not be detected as a defect even when the substrate was adhered or the substrate was mixed with debris. In addition to such inconveniences, in the case of the above-mentioned publication, since the size of the entire filler in the detected image is reduced, a defective through hole in which the filler is insufficient is detected. Even through holes with a slightly smaller diameter, which can be accepted as normal, have been erroneously detected as insufficient filling defects.

[0004] A first object of the present invention is to determine whether or not foreign matter is attached to or mixed with a filler in a filling state in each of the through holes, regardless of the diameter of the through hole. Either a scattering defect in which the filler is scattered on the substrate surface around the through hole, a bleeding defect in which the filler protrudes from the upper surface of the through hole to the nearby substrate surface, or a defect without a through hole in which the through hole is not formed. Another object of the present invention is to provide a through hole filling state inspection method and apparatus capable of reliably detecting a defect type in an identified state. A second object of the present invention is to provide a defect in which the filler is in an insufficiency state, a partial lack of the filler, or a lack of the filler, from the filling state of the filler in each through hole, regardless of the diameter of the through hole. It is an object of the present invention to provide a through-hole filling state inspection method and apparatus capable of reliably detecting any of the concavo-convex defects protruding from the substrate surface while the defect type is identified. A third object of the present invention is to provide a method for determining the presence or absence of a foreign matter, a defect, a bleeding defect, a defect without a through-hole, a defect without a through-hole, an irregular defect, regardless of a diameter of a through-hole, from a filling state of a filler in each through-hole. An object of the present invention is to provide a method and an apparatus for inspecting a filled state of through holes which can reliably detect any one of the defects in a state where the type of the defect is identified and economically. A fourth object of the present invention is to provide a method for detecting the presence or absence of a foreign substance, a scattering defect, a bleeding defect, a defect without a through hole, a defect without a defect, an irregularity, regardless of the diameter of the through hole, from the filling state of the filler in each through hole. It is an object of the present invention to provide a through hole filling state inspection method and apparatus capable of reliably and promptly detecting any one of the defects in a state where the defect type is identified.

[0005]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a circuit board having a large number of through-holes filled with a filling material illuminated by linearly polarized illumination light obliquely from above. A polarization component in the same direction as the polarization direction of the illumination light is shielded, and an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light is detected from above or obliquely upward, and a through image is obtained from the optical image. Based on a first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a hole, a through hole and an image portion corresponding to the vicinity of the through hole are extracted, and the image portion detected from the image portion is extracted. Based on the total area S _H1 and perimeter l at
Foreign matter, contamination defects, scattering defect, bleeding defect, when one of the through-hole without a defect is detected in a state where the defect type is identified, the presence or absence of the area S _H1, the area S _H1
Of the ratio of the area S _H1 to the circumference l ²
In the state where the defect type is identified from the magnitude relationship with the design value
This is achieved by being detected . Further, as the through hole filling state inspection device, an illumination means for illuminating a circuit board formed with a large number of through holes filled with a filler from obliquely upward with linearly polarized illumination light, and a polarization of the linearly polarized illumination light An optical image detecting means for blocking a polarization component in the same direction as the direction and detecting an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light from above or obliquely upward, and the optical image detection means Based on a first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a through hole from the optical image detected in the above, a through hole and an image portion corresponding to the vicinity of the through hole are extracted. Area S as a whole in the image part detected from the image part
Based on _H1 and perimeter l, presence or absence of the area S _H1, said surface
The magnitude relationship between the design value of the product S _H1 and the area S _H1 and the perimeter l ²
Defect detection means for detecting any of foreign matter attachment / mixing defects, scattering defects, blurring defects, and defects without through-holes in a state where the defect type is identified, by determining a magnitude relationship with a design value of the ratio of At least.

A second object of the present invention is to illuminate a circuit board having a large number of through-holes filled with a filler material from an obliquely upward direction with illumination light, and to display an optical image of the illumination light on the illumination light emission side. , A second threshold value V _H2 for extracting an image portion corresponding to a wall portion of a through-hole irradiated with illumination light from the optical image, and the illumination light in the vicinity of the through-hole and the through-hole. Is extracted based on each of the third threshold values V _H3 for extracting the image portion corresponding to the portion not irradiated with the through hole, and the image portion corresponding to the vicinity of the through hole is extracted, and the image portion detected from the image portion is extracted. State in which any one of the insufficient defect and the irregularity defect is identified based on the presence or absence of each of the areas S _H2 and S _H3 as a whole, or the magnitude relationship with the reference value of each of the areas S _H2 and S _H3 Is detected by In is achieved. Further, as the through hole filling state inspection apparatus, an illumination means for illuminating a circuit board having a large number of through holes filled with a filling material with illumination light from obliquely above, and an optical image of the illumination light as illumination light An optical image detecting means for detecting the obliquely upper side of the emission side, and a second threshold value for extracting an image portion corresponding to a wall portion of the through hole irradiated with illumination light from the optical image detected by the optical image detecting means. V _H2 , based on each of the third threshold values V _H3 for extracting an image portion corresponding to a through hole and a portion of the vicinity of the through hole where illumination light is not irradiated,
A through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and the presence or absence of each of the areas _SH2 and _SH3 as a whole in the image portion detected from the image portion, or each of the areas _SH2 and _SH3 This is achieved by including at least a defect detection unit that detects any of a missing defect and a concave / convex defect in a state where the defect type is identified based on a magnitude relationship with a reference value.

[0007] The third object is to inspect the filling state of through-holes relating to the foreign matter adhering / mixing defect, the scattering defect, the bleeding defect, and the defect having no through-hole, and the inspection of the through-hole filling state relating to the insufficient defect and the irregularity defect. Are achieved in a time-sharing manner in succession. Further, as the through-hole filling state inspection device, an illuminating means for selectively illuminating a circuit board having a large number of through-holes filled with a filling material from obliquely above with either illumination light or linearly polarized illumination light. And an optical image of the illumination light, a polarization component in the same direction as the polarization direction of the linearly polarized illumination light is shielded, and any one of an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light. An optical image detecting means for selectively detecting the obliquely upper part of the illumination light emitting side, and a defect type of any of the insufficient defect and the irregularity defect is identified from the optical image of the illumination light detected by the optical image detecting means. A defect detection means for detecting any one of a foreign matter attachment / mixing defect, a scattered defect, a blurred defect, and a defect without a through hole from the optical image of the polarized light component in a state where the defect type is identified. It is accomplished by configuring to include the at Ku.

[0008] The fourth object is the same as above.
Inspection of through-hole filling state for mixed defects, scattering defects, blurring defects, defects without through-holes,
This is achieved by performing the inspection of the through hole filling state relating to the irregularity defect at the same time in parallel. Further, as the through hole filling state inspection device, an illumination means for illuminating a circuit board formed with a large number of through holes filled with a filler from obliquely upward with linearly polarized illumination light, and a polarization of the linearly polarized illumination light A first optical image detecting means for blocking a polarization component in the same direction as the direction and detecting an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light from above or obliquely upward; A second optical image detecting means for detecting an optical image of the linearly polarized illumination light from an obliquely upper side of the illumination light emitting side in parallel with the detection, and a foreign matter adhering from the optical image detected by the first optical image detecting means.・ Mixed defects,
While any one of the scattering defect, the bleeding defect, and the defect without through hole is detected in a state where the defect type is identified, the second defect is detected.
And a defect detection unit that detects any of the missing defect and the unevenness defect from the optical image detected by the optical image detection unit in a state where the defect type is identified.

[0009]

When a linearly polarized illumination light is illuminated from obliquely above a circuit board having a large number of through holes filled with a filler, a polarization component of a polarization direction orthogonal to the polarization direction of the linearly polarized illumination light is obtained. After detecting the optical image from above or obliquely above, a first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a through hole from the optical image.
When an image portion corresponding to a through hole and the vicinity of the through hole is extracted based on the
_{From H1} and perimeter l, foreign matter adhesion / mixing defect, scattering defect,
Either a bleeding defect or a defect without a through hole is detected in a state where the defect type is identified.
That is, the presence or absence of the area S _H1, the magnitude relationship between the design value of the area S _H1, by determining the magnitude relationship between the design value of the ratio of the area S _H1 and perimeter l ^2, they defects identified defect type It can be detected in a state where it is performed.

Further, in a state in which illumination light is illuminated from obliquely above a circuit board having a large number of through holes filled with a filler, an optical image of the illumination light is obliquely displayed from obliquely above the illumination light emission side. After the detection, the second threshold value V _H2 for extracting the image portion corresponding to the wall portion of the through-hole irradiated with the illumination light from the optical image, the illumination light in the vicinity of the through-hole and the illumination hole is irradiated. Based on each of the third threshold values V _H3 for extracting an image part corresponding to a non-existent part, a through hole and an image part corresponding to the vicinity of the through hole are extracted, and the presence or absence of each of the areas S _H2 and S _H3 in the image part Alternatively, by determining the magnitude relationship between the reference values of the areas S _H2 and S _H3 , these defects can be detected in a state where the defect type is identified.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. First, before specifically describing the present invention, its theoretical background will be described as follows. That is, in a multilayer wiring board generally formed of ceramics or the like, a large number of through holes are formed in the board in order to electrically connect front and back printed wiring formed on the board or between each layer printed wiring. It has already been mentioned that, in place, the through-holes are filled with filler. By the way, the filling state of the filler in each through hole is not always in a good state, and the filler is formed so as to protrude from the surface of the ceramic or the like as the base material, or is insufficiently filled below the base material surface. Or a part of the filler is missing, or the filler may be excessively formed on the substrate surface. These defects hinder the electrical connection as the primary purpose, and their existence greatly reduces the reliability of the printed wiring board itself. Therefore, the presence or absence of these defects is strictly inspected before mounting electronic components. It is what you need.

Here, the defective filling state of the filler in the through hole, that is, the type of the defective through hole will be described. As shown in FIG. 3, FIG. 4, and FIG.
Defects without through-holes, foreign matter adhering / mixing defects, scattering defects, insufficient defects, unevenness defects (general term for concave and convex defects)
Since there is a possibility that these defects often occur, it is necessary to detect these defects with high accuracy. More specifically, “image detection by oblique illumination” in FIG. 3 refers to the defect detection method by oblique illumination according to the related art described in Japanese Patent Application Laid-Open No. 63-241344, and ,
"Polarized illumination / polarized light detection" refers to polarized illumination / light according to the present invention.
It shows a defect detection method by polarization detection. As shown in the figure, a detected image signal, a binary image, and a defect determination example in each case are also shown.
Even if the filling state is normal, in the case of "image detection by oblique illumination", the oblique illumination light is regularly reflected from a part of the surface of the metal fine particles as a filler,
In the detected image signal, a luminescent spot due to the specular reflection light may occur as a large signal level. Therefore, assuming that the image signal is binarized by the threshold value V _Ha , a part of the image corresponding to the filler as a result of the binarization processing appears as an image similar to the base material level. It is to become. Therefore, if the defect is determined by comparing the areas, the relationship between the area Sa in the image portion corresponding to the filler and the reference value S ₀ is often S
a ≒ S ₀ becomes Sa <S ₀ not to the results, despite the filling state is normal, it is that there may be a case of erroneously determined it as a defective through hole.
Further, when forming through holes in the base material, if the base material waste is mixed into the filling material or a foreign substance adheres to the filling material, it may cause conduction failure, but in such a case, Also,
The detected image signal and the binary image are the same as those in the case of the normal filling state in which the luminescent spot is generated.
Therefore, if the normal filling state in which the bright spot is generated is treated as a normal filling state without causing a defect, the filling state in which foreign matter is attached or mixed may be erroneously detected as the normal filling state. That is. As to the scattering defect, if a bright spot is generated as in the case of the normal filling state, the relationship between the area Sa and the reference value S ₀ does not necessarily satisfy Sa> S ₀ , but may be Sa ≒ S _0. Therefore, there is a possibility that the battery is erroneously detected as a normal filling state.

On the other hand, FIG. 2 shows an outline of a filling state detection method using polarized light illumination / polarized light detection and oblique illumination / oblique light detection according to the present invention. In this case, the light beam from the point light source 10 is converted into a parallel light beam by a condenser lens (not shown), and then is passed through the polarizing plate 14, thereby illuminating the circuit board 1 with linearly polarized light as linearly polarized illumination light. It has become. At that time, since the illumination light is irregularly reflected on the circuit board 1 composed of fine particles, the polarization direction of the reflected light is uniformly disturbed despite being linearly polarized by the polarizing plate 14. I have.
However, the reflection of the illumination light from the surface of the metal fine particles filled as the filler 1a in the through-hole is specular reflection, and the polarization direction of the reflected light is the same as the polarization direction of the polarizing plate 14. Therefore, when the polarizing plate 15 is arranged so that its polarization direction is orthogonal to that of the polarizing plate 14 on the illumination system side and the image is detected by the sensor 13a via the objective lens 12b, the reflected light from the surface of the metal fine particles As a result, the filler 1a is detected as blackish in the detected image, while the reflected light from the circuit board 1 passes through the polarizer 15 almost as it is, and the circuit board 1 itself is detected as whitish in the detected image. Things.

With the above-described polarized illumination / polarized light detection method,
Bleeding defects, defects without through holes, foreign matter attachment / mixing defects, and scattering defects can be detected. The details will be described below. That is, FIG. 3 shows the polarized light illumination / polarized light detection according to the present invention in the case where the filling state of the through-hole is a normal state, a foreign matter attached / mixed state, and a scattering state, respectively. In the detection method, bright spots from the filler are reliably shielded from light,
The image portion corresponding to the filler is black, and the image portion corresponding to the circuit board itself is white, so that an image having a clear black-white contrast can be detected. Therefore, in the binary image obtained by binarizing the detected image signal with the threshold value V _Hb , the area Sb in the image portion corresponding to the filling is Sb ≒ when the filling state is normal.
S ₀ (S ₀ : reference value). Also, the area Sb
And by obtaining the Sb / (lb) ² from perimeter lb, in the case of generally circular normal filling conditions outer shape, Sb / (lb) ²
≒ 1 / 4π (about 0.0796). However, in the case where foreign matter is attached or mixed into the filling material, the circular shape as the outer shape is reduced and the perimeter lb is increased as compared with the normal filling state.
(lb) ² is such that Sb / (lb) ² <１ ／ π.
Further, in the case of the scattered state, the relationship between the area Sb where the circular shape is lost and the perimeter lb due to the scattered filler is as follows.
Sb / (lb) ² <１ ／ π. Further, regarding the blur defect shown in FIG. 4, in the binary image obtained by binarizing the detected image signal with the threshold value V _H1 , the area S _H1 of the image portion corresponding to the filling material is S _H1 > S _H10
( _SH10 : reference value). Further, for a defect without a through-hole in which the through-hole is not processed in the through-hole forming process, S _H1 ≒ 0, so that a blurring defect, a defect without a through-hole, The foreign matter adhesion / mixing defect and the scattering defect can be detected in a state where the type is reliably identified by analyzing the area and the perimeter of the image portion corresponding to the important object.

As described above, bleeding defects, defects without through holes, foreign matter adhering / mixing defects, and scattering defects can be detected by polarized light illumination and a polarized light detection method. The defect can be detected by oblique illumination and oblique detection shown in FIG. As shown in FIG. 2, the circuit board 1 is illuminated with linearly polarized illumination light (ordinary non-polarized illumination light is also possible), but the image on the circuit board 1 is emitted as it is via the objective lens 12b. This is detected by a sensor 13b arranged on the side. FIG. 5 shows an example of the oblique illumination / oblique detection according to the present invention when the filling state of the through hole is a normal state, an insufficient state, a concave state, and a convex state, and a determination example thereof. In the case of oblique illumination / oblique detection, the illumination light is specularly reflected on the wall surface of the through hole related to the lack defect, and the image at that portion is uniform. The illumination light is detected brighter than the surface of the substrate where the illumination light is irregularly reflected, and is obtained as a high-level signal. On the other hand, in the case of an irregularity defect, the image corresponding to the shadow caused by the irregularity portion of the filling is obtained as a small brightness and a low level as compared with the filling in a normal filling state. It has become. Therefore, the second threshold value V _H2 for extracting an image portion corresponding to the wall portion of the through hole irradiated with the illumination light, and the image portion corresponding to the through hole and the portion near the through hole where the illumination light is not irradiated near the through hole. Third for extraction
From the detected image based on each of the threshold values V _H3 , a through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and the areas S _H2 and S _H3 as a whole in the image portion detected from the image portion are extracted. By determining the presence / absence or the reference value (sufficiently small positive value) S _H20 , S _{H30 of} each of the areas S _H2 and S _H3 , the defect type is identified as either an insufficient defect or an unevenness defect. It can be detected in a state where it is performed.

Although the theoretical background of the present invention has been described above, the present invention will be specifically described as follows. That is, first, a description will be given of a through-hole filling state inspection apparatus according to the present invention. FIG. 1 shows an example of the configuration. In this case, the stage
An X stage 3 is placed on the stage 2 and a Y stage 4 is placed on the X stage 3 so that the XY stage can be moved independently in the X and Y directions. -Is configured. The circuit board 1 to be inspected is positioned and mounted on the Y stage 4, and the X stage 3 and the Y stage 4 are each provided with an X-axis driving unit 5 as an external driving device and a Y stage 4.
By being driven by the shaft drive unit 6, they are moved in the X and Y directions, respectively. This X, Y
The inspection position on the circuit board 1 is moved to X, Y
Although the direction can be updated, the movement amount in each of the X stage 3 and the Y stage 4 is measured by the X axis length measuring device 7 and the Y axis length measuring device 8, respectively, in order to actually measure the inspection position. It is supposed to be.

On the other hand, the inspection position on the circuit board 1 is obliquely illuminated by linearly polarized illumination light from a linearly polarized parallel light source (consisting of a point light source 10 and a condenser lens 11) 9 via a polarizing plate 14. However, the image at the inspection position is detected by the line sensor 13a from above vertically through the polarizing plate 15 and the objective lens 12a. At this time, while the polarizing plate 15 is provided so that the polarization direction is orthogonal to the polarizing plate 14, the plane formed by the optical axes of the illumination system and the image detection system is set perpendicular to the detection target surface, The image detection area of the line sensor 13a is also set perpendicular to the plane. The image at the inspection position is obliquely above the parallel light source 9 and detected by the line sensor 13b via the objective lens 12b. In addition, when a mercury lamp or a xenon lamp is used as the point light source 10 and the light from the point light source 10 is used as illumination light of a parallel light beam by the condenser lens 11, when the diffraction phenomenon is suppressed as much as possible, the light can be generated in the filler and its vicinity. A shadow having a possibility is more easily detected as an image.

Therefore, in the above configuration, if the circuit board 1 is horizontally moved in a direction that is not parallel to the detection longitudinal direction of the line sensors 13a and 13b,
a, 13b are supplied to the image detection circuits 16, 1
7 is obtained as a multi-valued image signal by A / D conversion processing, and further illuminated by shading correction circuits (for example, the same as those disclosed in JP-A-58-153328) 18 and 19. Unevenness, line sensors 13a, 13
b After the sensitivity unevenness in each is digitally corrected,
It is provided to the value conversion circuits 20, 21, 22 and the histogram creation circuits 23, 24. In each of the histogram creating circuits 23 and 24, the frequency distribution of the actually detected image signal level is calculated so that the above-described three types of threshold values V _H1 , V _H2 and V _H3 are optimally obtained.
The calculation results are subjected to predetermined arithmetic processing by the microcomputer 25 as the overall control arithmetic processing unit, so that optimum threshold values _VH1 , _VH2 , and _VH3 are obtained. Based on each of these thresholds V _H1 , V _H2 , V _H3 ,
The binarization circuits 20, 21, 22 perform binarization processing on the multi-level image signal to obtain a two-dimensional binarized image signal. Of these, the two-dimensional binarized image signal from the binarizing circuit 20 is processed in a predetermined manner by each of the contour extracting circuit 26 and the projection distribution creating circuit 28. In the contour extraction circuit 26, pixels constituting the contour line of the filler in the through-hole are extracted from the two-dimensional binary image signal, and the extracted pixels are sequentially summed up by the perimeter calculation circuit 46. As a result, the final total value is obtained by calculating the entire perimeter of the contour line. The projection distribution creating circuit 28 creates a projection distribution by projecting the two-dimensional binary image signal in the X direction or the Y direction, and the area calculation circuit 31 based on the projection distribution creates an image corresponding to the filler. The total area of the image corresponding to the filler is calculated by summing up the number of pixels constituting. On the other hand, the two-dimensional binarized image signals from the binarizing circuits 21 and 22 are input to the projection distribution creating circuits 29 and 30, respectively.
Based on the projection distribution, the area in the image portion corresponding to the through-hole wall portion is calculated in the area calculation circuit 32, while the area in the image portion corresponding to the shadow portion caused by the unevenness of the filler is calculated. It is calculated by the circuit 33.

In the coordinate generating circuit 34, the scanning position on the sensor is determined via one of the image detecting circuits 16 and 17 based on the scanning clock from one of the line sensors 13a and 13b which are currently involved in image detection. While the coordinates are being created, the coordinate measuring circuit 35 also uses the circuit sensors by the line sensors 13a and 13b based on the X and Y movement amounts from the X-axis measuring device 7 and the Y-axis measuring device 8, respectively. 1, the actual inspection position coordinates are detected. From the detected actual inspection position coordinates, the microcomputer 25 can know the actual inspection position at that time.
When the position of the through hole to be inspected is updated based on the design data from the floppy disk 37,
While monitoring the position to become the desired actual inspection position,
When the X-axis drive unit 5 and the axis drive unit 6 are drive-controlled via the XY drive control unit 36, each of the X stage 3 and the Y stage 4 is moved by a desired amount. More specifically, in the actual inspection of the through hole filling state, the through hole filling state inspection is performed while the reciprocating movement of the circuit board 1 is controlled with respect to the parallel light source 9 as shown by the arrow A. And the entire surface is scanned. The floppy disk 37 also stores various design data (position coordinates, through-hole diameter, pitch, etc.) for each of the through-holes formed on the circuit board 1. The design data is read out to the microcomputer 25 as necessary, and the design data is read out.
Thus, each of the X stage 3 and the Y stage 4 is driven as desired. Among these design data, the position coordinates for each through-hole were
The data stored in the through-hole coordinate memory 38 and the outputs from the coordinate generating circuit 34 and the coordinate length measuring circuit 35 are compared with the contents of the through-hole coordinate memory 38 and the comparison circuit 39. Are compared. At the time when the comparison result of the coincidence is obtained from the comparison circuit 39, since an image of a desired through-hole has been detected, each time a through-hole image is detected, the area calculation circuits 31, 32,. The area and the perimeter are calculated by activating the 33 and the perimeter calculating circuit 46, respectively. The area value and the perimeter value from each of the area calculation circuit 31 and the perimeter calculation circuit 46 are taken into the microcomputer 25, and after the calculation of area / (perimeter) ² is performed, the calculation result is obtained. Is compared with various reference values set by the microcomputer 25 by the comparison circuit 40 to determine the quality of the filling state and to identify the defect type. Further, the area calculation circuits 31, 32, 3
Similarly, the area value from each of the micro computer 2
5 and the comparison circuit 4
The comparison in 1, 42, and 43 determines whether the filling state is good or bad and identifies the defect type. The pass / fail judgment result and the defect type identification result from each of the comparison circuits 40, 41, 42, and 43 are converted to through-holes.
Are stored in the determination result memory 44 after being associated with the corresponding position coordinates, and are stored under the control of the microcomputer 25 from the determination result memory 44, and are stored in the printer. At 45, visible recording is enabled.

As described above, the shading correction circuit 1
The multi-valued image signals from 8 and 19 are converted into binarizing circuits 20 and 2
1, 22 have been binarized based on the threshold V _H1, V _H2, V _H3 respectively in each, their threshold V _H1,
The method for optimally setting V _H2 and V _H3 will be described below with reference to FIG. That is, as shown in FIG.
Using the circuit board to be inspected, from the detected image signals (multi-valued image signals) from each of the line sensors 13a and 13b, the brightness frequency distribution of the entire circuit board 1 is obtained before the through hole filling state inspection. As shown in FIG. 6B, the histograms are obtained by the histogram creation circuits 23 and 24, respectively. Microcomputer - from motor 25, the lightness frequency distribution, as shown in FIG. 6 (b), on the signal level H _min of the packing corresponding to the circuit board corresponding signal level H _max is determined, these signal levels H _The threshold values V _H1 , V _H2 , and V _H3 are set as optimal functions by calculation as functions of _max and H _min .

The threshold values V _H1 , V set as described above
_H2 and _VH3 perform the binarization processing, respectively.
Three types of two-dimensional binarized image signals are obtained from the binarization circuits 20, 21, 22. From these image signals, furthermore, the area corresponding to the filling, the area corresponding to the shadow portion, the area corresponding to the wall surface of the through hole and the perimeter of the filling are determined, and whether the filling state is good or bad is determined. The defect determination described above is performed, and these pass / fail judgments and defect identification will be specifically described as follows. That is, FIG. 4 shows one type of binary image for various filling states after the binarization processing at the threshold value V _H1 . (Indicated by diagonal lines) S _H1 and its perimeter l are obtained, and the defect determination and the defect type identification are performed. FIG. 5 shows two types of binary images for various filling states after the binarization processing using the threshold values V _H2 and V _H3 . As illustrated, the binary image according to the threshold V _H2, sul - Ho - corresponding to Le walls, bright area S _H2 at the positive reflected in part has been required, in the area S _H2 Insufficient defects are detected by their existence. Further, from the binary image related to the threshold value V _H3 , an area S _H3 corresponding to the filler and a shadow that may have been generated in the vicinity thereof is obtained, and an unevenness defect is detected based on the presence of the area S _H3. It has become something. In particular,
Defect judgment and defect type identification are performed by areas S _H10 and S _H when the normal filling state is binarized by threshold values V _H1 , V _H2 and V _H3.
H20, S _H30 and perimeter as a reference value of l _0, 4, as shown as a determination example in FIG. 5, which is intended to be determined in as follows.

That is, in the case of polarized light illumination / polarized light illumination detection, the normal condition is: S _H1 ≒ S _H10 , S _H1 / l ² ≒ S _H10 / l ₀ ² ≒ 1/4
π = 0.0796 Bleeding: S _H1 > S _H10 No through-holes: S _H1 ≒ 0 Adhering / mixing of foreign matter: S _H1 / l ² <１ ／ π Scattering defect: S _H1 / L ² <1 / 4π. On the other hand, in the case of oblique illumination / oblique detection, normal ... _SH2 < _SH20 , _SH3 < _SH3 deficiency ... _SH2 > _SH20 , _SH3 < _SH30 concave ... _SH2 < _SH20 , _SH3 > S _H30 convex... S _H2 <S _H20 , S _H3 > S _H30 , and the reference values S _H20 , S _H30 are actually sufficient if they are set to extremely small values.

By the way, in the above example, the area is calculated from the projection distribution. A specific example of the calculation method will be described with reference to FIG. 100 are projected in the horizontal and vertical directions, respectively, to form projection distributions 101 and 102. The area of the filler is determined by the number of pixels constituting one of the projection distributions 101 and 102. By summing up,
It can be easily calculated. The number of pixels constituting the binary image 100 may be directly counted without creating a projection distribution. Further, the perimeter can be easily calculated by detecting the contour of the binary image 100 and counting the number of pixels constituting the contour. FIG. 8 shows an example of a specific circuit configuration of the contour extraction circuit 26 for extracting pixels forming a contour from the binarized image signal 103. In this case, the shift register group 1
Reference numeral 04 denotes a configuration in which three shift registers corresponding to the length of one horizontal scanning line in each of the line sensors 13a and 13b are connected in series.
Are sequentially shifted into the shift registers, while the final-stage shift output from each of the shift registers is shifted into the local extraction memory 105 including a serial-in / parallel-out shift register. . In the local extraction memory 105 and its peripheral circuits, at least one of the parallel bit outputs P ₁ , P ₂ , P ₃ , and P ₄ from the specific plurality of flip-flops is at least logic “0”. N
AND gate - after being detected by the bets 106, AND gate between the parallel bit output P ₀ from a particular flip-flop - has become what is logical in bets 107. Since the position of each of the parallel bit outputs P ₁ , P ₂ , P ₃ , and P ₄ is located above, below, and to the left and right of that of the parallel bit output P ₀ , when a contour line is detected, an AND gate is set. 10
The contour detection signal 108 as seven outputs is obtained as logic "1".

Next, an example of a specific configuration of the projection distribution creating circuits 28, 29 and 30 for creating a projection distribution for each through hole will be described with reference to FIG. 13b, (n + 1) shift registers corresponding to the length of one horizontal scanning line in each of the 13b are connected in series.
Are sequentially input to the shift registers, while the final shift output from each of the shift registers is directly input to the addition / subtraction circuit 111, and n
The data is input to the addition / subtraction circuit 111 via a shift register group 110 composed of a plurality of n-bit length shift registers. The addition / subtraction circuit 111 is also supplied with the intermediate addition / subtraction result from the horizontal projection distribution memory 112, so that the final shift output from the shift register group 109 and the intermediate addition / subtraction result from the horizontal projection distribution memory 112 are obtained every pixel period. Of the shift register group 11
The final shift output from 0 has been reduced, and the addition / subtraction result is used as the intermediate addition / subtraction result in the horizontal projection distribution memory 112.
Is stored temporarily. On the other hand, in the addition / subtraction circuit 113, the (n + 1) -th (n + 1) -th order is obtained from the addition result of the final output from the first shift register in the shift register group 109 and the intermediate addition / subtraction result from the vertical projection distribution memory 114 every pixel period. The final output from the shift register is reduced, and the result of the addition / subtraction is temporarily stored in the vertical projection distribution memory 114 as an intermediate addition / subtraction result. The vertical projection distribution memory 114 has a capacity corresponding to the length of one horizontal scanning line, and the counter 116 counts the number of scanning clocks 115, so that the count value is shifted by the first shift in the shift register group 109. The read / write address i indicating the position on the horizontal scanning line of the final output from the register acts on the vertical projection distribution memory 114. In such a case, the horizontal projection distribution memory 112, P _Y (j)
(j = 1,... n), n on the horizontal scanning line
Since two binarized signals having a distance of +1 pixel are added or subtracted, the result of adding the binarized signals for n pixels therebetween is temporarily stored. Similarly, also in the vertical projection distribution memory 114, P _X (k), the addition result of the binarized signals over n horizontal scanning lines is temporarily stored. That is, as shown in FIG. 10, if the final output position of the first shift register in the shift register group 109 on the two-dimensional screen 117 is (i, j), the horizontal projection distribution memory 112 has Are stored in the vertical projection distribution memory 114, and the vertical projection distribution in the area 119 is also stored in the vertical projection distribution memory 114. FIG. 11 shows an example of a specific circuit configuration of the area calculation circuits 31, 32, and 33 for calculating the area from the projection distribution (when calculating the area in the area of n × n pixels from the horizontal projection distribution memory 112). However, as will be understood from this, the area is obtained as the addition result by simply adding each of the addition and subtraction results from the horizontal projection distribution memory 112 by the addition circuit 113. Here, the timing at which the circumference length calculation circuit 46 and the area calculation circuits 31, 32, and 33 are operated will be described. As shown in FIG. 12, when the through-holes 50 are arranged at a constant pitch n, if the image detection is performed as indicated by the arrow, the position coordinates (black circles) for each through-hole 50 are assumed. Display) is a micro computer
Under the control of the data 25, the data is stored in the through-hole coordinate memory 38 in a predetermined order based on the design data from the floppy disk 37. The position coordinates read out from the through-hole coordinate memory 38 in a predetermined order are shown in FIG.
The comparison circuit 3 determines whether or not it matches the final output position of the first shift register in the shift register group 109 shown in FIG.
9, the perimeter calculation circuit 46 and the area calculation circuits 31, 32, 33 are activated each time they match. If the startup is controlled in this way,
N × n with the through-hole 50 located at the center position
From the horizontal / vertical projection distribution in the pixel area, not only the area and perimeter of the filler in the through hole 50 but also the diameter thereof can be obtained. Through-hole 50
Even if there are several types of pitches,
When the position coordinates indicated by black circles shown in FIG. 12 are stored in the wheel coordinate memory 38 based on the design data, the through-holes 50 appearing in a predetermined order regardless of the pitch of the through-holes 50. For each, the image can be processed.

FIG. 13 also shows a histogram creation circuit 2
3 and 24 show the schematic configuration. As described above, the image signal from each of the line sensors 13a and 13b is obtained as a multilevel image signal by the A / D conversion processing in each of the image detection circuits 16 and 17, and as shown in FIG. Using the valued image signal 122 as a read / write address, the address content is read from the histogram memory 121, the content is updated by +1 by the adder circuit 123, and the updated content is stored again at the address.
When such processing is repeated, the frequency distribution (brightness distribution) of the image signal level over the entire circuit board 1 can be easily obtained.

Finally, a description will be given of the configuration of another example of the through-hole filling state inspection apparatus according to the present invention. In the through-hole filling state inspection apparatus shown in FIG. 1, the circuit board 1 is polarized and illuminated in order to realize a high-speed inspection, and its image is simultaneously detected by the polarization detection system and the oblique detection system. However, even if a high-speed inspection cannot be performed, various defects shown in FIGS. 4 and 5 can be detected only by the oblique detection system. That is, in FIG. 1, a binarization circuit 20 connected to the line sensor 13a is connected to a stage subsequent to the shading correction circuit 19 to utilize only the line sensor 13b, and the polarization plate 15 is disposed below the lens 12b. It is sufficient that at least one of the polarizing plates 14 and 15 is detachably disposed in the optical path. When detecting various defects shown in FIG. 4, the polarizing plates 14 and 15 are polarized illumination / polarization detecting systems arranged in the optical path. On the other hand, when detecting various defects shown in FIG. The inspection may be performed in a state where any one of 15 is removed from the optical path. Therefore, each through-hole on the circuit board 1 needs to be inspected twice. However, since only one detection system is required, the configuration is simplified and the through-hole is economically reduced. The hole filling state can be inspected.

[0027]

As described above, according to the first and fifth aspects, regardless of the diameter of the through hole, the foreign matter adheres to the filler from the filling state of the filler in each through hole.
Or foreign matter adhering / mixing defect mixed, scattered defect where the filler is scattered on the substrate surface around the through hole, bleeding defect where the filler protrudes from the top of the through hole to the nearby substrate surface, and a through hole are formed either without through hole defects that are not reliably detected obtained in a state where the defect type is identified, also in the case of claims 2 and 6, regardless of the diameter of the through hole, in each through hole In the state where the defect type is identified, from the filling state of the filling, any one of an incomplete defect in which the filling is in an insufficient state, a partially missing filling, or an uneven defect in which the filling is protruding from the substrate surface. Claims 3 and 7
In the case of, regardless of the diameter of the through hole, any one of the foreign matter attachment / mixing defect, scattering defect, bleeding defect, defect without through hole, insufficient defect, and irregularity defect is determined from the filling state of the filler in each through hole. In the state where the defect type is identified, it can be reliably detected economically. Furthermore, according to the fourth and eighth aspects, the filling state of the filler in each through-hole regardless of the diameter of the through-hole. From, foreign matter adhesion / mixing defect, scattering defect, blurring defect, defect without through hole,
Any of the insufficient defect and the irregularity defect can be reliably and promptly detected in a state where the defect type is identified.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a through-hole filling state inspection apparatus according to the present invention.

FIG. 2 is a diagram showing an outline of a filling state detection method by polarized illumination / polarized light detection and oblique illumination / oblique detection according to the present invention.

FIG. 3 is a diagram illustrating polarized light illumination / polarized light detection according to the present invention when the through hole is filled in a normal state, a foreign matter adhering / mixed state, and a scattering state, respectively, and oblique illumination according to the prior art. Figure in comparison with image detection by

FIG. 4 is a diagram showing polarized illumination / polarized light detection according to the present invention and a determination thereof when the filling state of the through hole is a normal state, a bleeding state, a state without a through hole, a foreign substance mixed state, and a scattering state, respectively. Figure showing an example

FIG. 5 is a diagram showing oblique illumination / oblique detection according to the present invention and a determination example thereof when the state of filling the through-hole is a normal state, an insufficient state, a concave state, and a convex state, respectively.

FIGS. 6A and 6B are diagrams for explaining a method for optimally setting a threshold value for binarization processing; FIGS.

FIG. 7 is a diagram for explaining a method of calculating an area from a projection distribution;

FIG. 8 is a diagram illustrating an example of a specific circuit configuration of a contour extraction circuit for extracting pixels forming a contour line;

FIG. 9 is a diagram illustrating an example of a specific circuit configuration of a projection distribution creating circuit that creates a projection distribution;

FIG. 10 is a diagram for explaining the operation of the projection distribution creating circuit;

FIG. 11 is a diagram illustrating an example of a specific circuit configuration of an area calculation circuit that calculates an area from a projection distribution;

FIG. 12 is a diagram for explaining start timings of a perimeter calculation circuit and an area calculation circuit;

FIG. 13 is a diagram illustrating a schematic configuration of a histogram creation circuit;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Circuit board, 10 ... Point light source, 11 ... Condenser lens, 12a, 12b ... Objective lens, 13a, 13b ... Line sensor, 14, 15 ... Polarizer, 16, 17 ... Image detection circuit, 18, 19 ... Correction circuit, 20,
21, 22 ... binarization circuit, 25 ... microcomputer
26, contour extraction circuit, 28, 29, 30 projection distribution creation circuit, 31, 32, 33 area calculation circuit, 38 through-hole coordinate memory, 39, 40, 41, 42, 43
... comparison circuit, 44 ... determination result memory, 46 ... perimeter calculation circuit

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-100393 (JP, A) JP-A-59-231402 (JP, A) JP-A-63-124943 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) G01N 21/84-21/958

Claims (8)

(57) [Claims] In a state where a circuit board having a large number of through holes filled with an electrically conductive substance is illuminated with linearly polarized illumination light from obliquely above, the polarization direction of the linearly polarized illumination light is the same. The polarized light component is shielded, and the optical image of the polarized light component in the direction orthogonal to the polarization direction of the linearly polarized illumination light is detected from above or obliquely above, and the optical image corresponds to a normal brightness portion in a through hole. Based on a first threshold value V _H1 for extracting an image portion, a through hole and an image portion corresponding to the vicinity of the through hole are extracted, and an overall area S _{H1 of the} image portion detected from the image portion is extracted.
A foreign matter adhered to or mixed in with the electrically conductive material based on the perimeter l, a scattering defect in which the electrically conductive material is scattered on the substrate surface around the through hole, and an electrically conductive material. When detecting any of the bleeding defect protruding from the upper surface of the through hole to the nearby substrate surface and the defect having no through hole in which the through hole is not formed in a state where the defect type is identified, the presence or absence of the area _SH1 is determined. , the magnitude relationship between the design value of the area S _H1, than the magnitude relationship between the design value of the ratio of the area S _H1 and perimeter l ^2,
A through hole filling state inspection method in which a defect type is detected in an identified state. 2. A circuit board having a large number of through-holes filled with an electrically conductive material is illuminated with illumination light from obliquely above, and an optical image of the illumination light is obliquely upward on an illumination light emission side. The second threshold value V _H2 for extracting the image portion corresponding to the wall portion of the through-hole irradiated with the illumination light from the optical image, and the illumination light in the vicinity of the through-hole and the through-hole is emitted from the optical image. A third threshold value V _H3 (V _H3 <V _H1 <
V _H2 , hereinafter the same) Based on each, a through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and an overall area S _H2 , in the image portion detected from the image portion is extracted.
S _H3 each presence or based on the magnitude relationship between the reference value of the area S _H2, S _H3 each missing missing defect electrically conductive material is in the filling starved, electrically conductive material is partially or electrical conductivity A through hole filling state inspection method in which any of the concave and convex defects in which the conductive substance is protruding from the substrate surface is detected in a state where the defect type is identified. 3. The same direction as the direction of polarization of the linearly polarized illumination light in a state where a circuit board having a large number of through holes filled with an electrically conductive material is illuminated from above by a linearly polarized illumination light. The polarized light component is shielded, and the optical image of the polarized light component in the direction orthogonal to the polarization direction of the linearly polarized illumination light is detected from obliquely above the illumination light emission side, and the normal brightness portion in the through hole is detected from the optical image. Based on a first threshold value V _H1 for extracting a corresponding image portion, a through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and an area S as a whole in the image portion detected from the image portion is extracted. _H1
A foreign matter adhered to or mixed in with the electrically conductive material based on the perimeter l, a scattering defect in which the electrically conductive material is scattered on the substrate surface around the through hole, and an electrically conductive material. A through-hole filling state inspection for detecting any of a blurred defect protruding from the upper surface of the through-hole into a nearby substrate surface and a defect without a through-hole in which a through-hole is not formed in a state where a defect type is identified; In a state where a circuit board formed with a plurality of through holes filled with a conductive material is illuminated with illumination light from obliquely above, an optical image of the illumination light is detected from obliquely above the illumination light emission side, and A second threshold value V _H2 for extracting an image portion corresponding to a wall portion of a through-hole irradiated with illumination light from an optical image, a through-hole and illumination near the through-hole. On the basis of each of the third threshold values V _H3 for extracting an image portion corresponding to a portion not irradiated with bright light,
A through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and the presence or absence of each of the areas _SH2 and _SH3 as a whole in the image portion detected from the image portion, or each of the areas _SH2 and _SH3 Based on the magnitude relationship with the reference value, determine whether any of the defects that are insufficiently filled with the electrically conductive material, the partially missing electrically conductive material, or the unevenness defects that the electrically conductive material protrudes from the substrate surface. , Through hole filling state inspection to detect in the state where the defect type is identified,
A through hole filling state inspection method that is performed in a time-division manner before and after. 4. The same direction as the direction of polarization of the linearly polarized illumination light in a state where a circuit board having a large number of through holes filled with an electrically conductive material is illuminated with linearly polarized illumination light from obliquely above. For detecting an optical image of a polarization component in the direction orthogonal to the polarization direction of the linearly polarized illumination light from above, and extracting an image portion corresponding to a normal brightness portion in a through hole from the optical image. first based on the threshold VH _1, it extracts the through hole and the through hole near the corresponding image portion, the area S _H1 and perimeter l as a whole in the detected said image portion from the image portion In the first place, foreign matter is adhered to or mixed with the conductive material, foreign matter is scattered on the surface of the substrate around the through hole, and the conductive material is damaged. -Through hole filling state inspection to detect any type of bleeding defect protruding from the upper surface of the substrate near the surface of the substrate or a defect without a through hole where no through hole is formed, with the type of defect identified, and electrical conductivity An optical image of the illumination light is detected from an obliquely upper position on the illumination light emission side while a circuit board having a plurality of through holes filled with a substance is illuminated with the illumination light from an obliquely upper direction. A second threshold value V _H2 for extracting an image portion corresponding to a wall portion of a through-hole irradiated with illumination light, and an image portion extraction corresponding to a through-hole and a portion near the through-hole not irradiated with illumination light. Based on each of the third threshold values V _H3 , a through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and the whole of the image portion detected from the image portion is extracted. Area S _H2 , S
_{Based on} the presence or absence of each _H3 , or the magnitude relationship with the reference value of each of the areas S _H2 and S _H3 , an insufficient defect filled with an electrically conductive material, a partial lack of an electrically conductive material, or an electrical conductivity A through-hole filling state inspection method in which the through-hole filling state inspection for detecting any of the concave and convex defects in which a substance protrudes from the substrate surface in a state where the defect type is identified is performed simultaneously and in parallel. 5. An illuminating means for illuminating a circuit board having a large number of through holes filled with an electrically conductive material from a diagonally upper part with linearly polarized illumination light, and a light source having the same polarization direction as the linearly polarized illumination light. The polarization component in the direction is shielded, and the optical image of the polarization component in the direction orthogonal to the polarization direction of the linearly polarized illumination light is detected from above or obliquely upward, and the optical image is detected by the optical image detection means. Based on a first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a through hole from an optical image, a through hole and an image portion corresponding to the vicinity of the through hole are extracted and detected from the image portion. Area S in the image portion obtained
Based on _H1 and perimeter l, presence or absence of the area S _H1, the magnitude relationship between the design value of the area S _H1, the area S _H1 and perimeter l ²
By determining the magnitude relationship between the ratio and the design value of the ratio, the foreign matter adheres to the conductive material, or the foreign material adheres or mixes in the conductive material, and the conductive material is scattered on the substrate surface around the through hole. Detects any type of scattered defect, bleeding defect in which the electrically conductive substance protrudes from the top of the through hole to the nearby substrate surface, or defect without through hole in which no through hole is formed, in a state where the defect type is identified. And a defect detection unit. 6. An illuminating means for illuminating a circuit board having a large number of through holes filled with an electrically conductive material with illumination light from obliquely above, and an optical image of the illumination light is obliquely arranged on the illumination light emission side. Optical image detecting means for detecting from above,
A second threshold value V _H2 for extracting an image portion corresponding to a wall portion of a through-hole irradiated with illumination light from the optical image detected by the optical image detection means, a through-hole, and illumination light near the through-hole; third based on each threshold VH _3, it extracts the through hole and the through hole near the corresponding image portion, the image portion is detected from the image portion of but for extraction irradiated portion not corresponding image portion of the area S _H2, S _H3 each existence as a whole in, or the area S _H2,
S _H3 based on the magnitude relationship between the respective reference values, irregular defect deficiency defects electrically conductive material is in the filling starved missing electrically conductive material part, or the electrically conductive material is in a projecting state from the surface of the substrate And a defect detection means for detecting any one of the above in a state where the defect type is identified. 7. An illuminating means for selectively illuminating a circuit board having a large number of through holes filled with an electrically conductive material from a diagonally upper side with either illumination light or linearly polarized illumination light, and the illumination. An optical image of light, a polarization component in the same direction as the polarization direction of the linearly polarized illumination light is blocked, and any one of an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light is output to the illumination light output side. An optical image detecting means for selectively detecting an obliquely upper part of the image, and an image part for extracting an image portion corresponding to a wall portion of the through-hole irradiated with illumination light from the optical image of the illumination light detected by the optical image detection means. 2 based on the threshold value V _H2 , the third threshold value V _H3 for extracting the image portion corresponding to the through hole and the portion where the illumination light near the through hole is not irradiated, and the through hole and the through hole Neighborhood-aware Extracting image areas, the area S _H2, S _H3 each existence as a whole at the image portion detected the image portion than, or based on the magnitude relationship between the reference value of the area S _H2, S _H3 respectively, Insufficient defects in which the conductive material is underfilled, partially missing conductive material, or uneven defects in which the conductive material protrudes from the substrate surface, with the defect type identified While detecting
Based on the first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a through hole from the optical image of the polarized light component, a through hole and an image portion corresponding to the vicinity of the through hole are extracted. Based on the overall area S _H1 and perimeter l of the image portion detected from the image portion, the foreign material adheres to or mixes with the electrically conductive material, and the foreign material adhered / mixed defect and the electrically conductive material pass through. Either a scattered defect scattered on the substrate surface around the hole, a bleeding defect in which the electrically conductive material protrudes from the upper part of the through hole to the nearby substrate surface, or a defect without a through hole in which no through hole is formed. A through-hole filling state inspection device configured to include at least a defect detection unit configured to detect a type in a state where the type is identified. 8. An illuminating means for illuminating a circuit board having a large number of through holes filled with an electrically conductive material from obliquely upward with linearly polarized illumination light, and having the same polarization direction as the linearly polarized illumination light. A first optical image detecting means for shielding an optical image of a polarization component in a direction orthogonal to the polarization direction of the linearly polarized illumination light from above or obliquely upward, wherein the first polarization direction is parallel to the image detection; Detecting an optical image of the linearly polarized illumination light from obliquely above the illumination light emission side.
Based on a first threshold value V _H1 for extracting an image portion corresponding to a normal brightness portion in a through hole from the optical image detected by the first optical image detecting device. And an image portion corresponding to the vicinity of the through hole is extracted, and based on the total area _SH1 and the perimeter l of the image portion detected from the image portion, the foreign matter adheres to or mixes with the electrically conductive material. Foreign matter adhesion / mixing defects, scattering defects where the conductive material is scattered on the substrate surface around the through hole, bleeding defects where the conductive material protrudes from the upper surface of the through hole to the nearby substrate surface, through hole Is detected in a state in which the defect type is identified while the defect is not formed, and the defect is directly detected from the optical image detected by the second optical image detecting means. The second threshold value V of the through hole wall portion polarized illumination light is irradiated corresponding for the image portion extracting _H2, partial response image portion extracted illumination light at the through hole and the through hole near the not irradiated Based on each of the third threshold values V _H3 , a through-hole and an image portion corresponding to the vicinity of the through-hole are extracted, and the total areas S _H2 , S _{H3 of the} image portion detected from the image portion are extracted. Based on the presence or absence of each, or the magnitude relationship between the respective reference values of the areas S _H2 and S _H3 , an insufficient defect in which the electrically conductive material is underfilled, a part of the electrically conductive material missing, or an electrically conductive material A through hole filling state inspection device comprising at least a defect detecting means for detecting any of the concavo-convex defects protruding from the substrate surface in a state where the defect type is identified.