JPH1194762A - Beer-like pore shape inspecting instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspecting instrument of the shape of beer-like pores which enables automatic inspection of the shape of the beer-like pores with higher reliability in a short time as formed in an insulation layer when a printed circuit board is formed by a buildup method. SOLUTION: Information on luminance characteristic which an image of 3×3 dots with some pixels as center pixels has is extracted as such of the pixels from an image of a surface where beer-like pores are formed of a printed circuit board and feature information a notice area has is extracted from these pieces of luminance characteristic information. A detection of beer-like pores as candidate defect is performed by a radial judgment based on the feature information and then, the presence of the defect as candidate beer-like pores is determined by a microscopic judgment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a via hole shape inspection apparatus for inspecting the shape of a via hole formed in an insulating layer when a printed board is formed by a build-up method.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a printed circuit board,
2. Description of the Related Art A build-up method is known in which a printed circuit board having a multilayer wiring layer is formed by alternately forming wiring layers and insulating layers on a core material made of an insulator.

FIG. 16 is a schematic perspective view showing a part of an example of a printed circuit board formed by a build-up method.

In FIG. 16, 1 is a core material made of polyimide or the like, and 2 and 3 are insulating layers made of polyimide or the like.
Is a wiring layer made of copper foil, 7 and 8 are via holes, and insulating layers 2 and 3, wirings 4, 5, and 6 and via holes 7 and 8 are wiring layer 4, insulating layer 2, via hole 7, wiring The layer 5, the insulating layer 3, the via hole 8, and the wiring layer 6 are formed in this order.

Generally, the insulating layers 2 and 3 are formed to have a thickness of several tens of μm, and the via holes 7 and 8 are formed in the insulating layers 2 and 3 respectively.
Is formed so as to have a diameter of about twice the thickness of

The build-up method has an advantage that a high-density wiring layer can be formed as compared with the conventional method. However, since the lower wiring layer and the upper wiring are connected to each other, the build-up method requires an insulating layer. It is necessary to form a via hole and form a metal film inside the via hole.

Here, the process of forming a via hole in the insulating layer is generally performed using a photosensitive insulating material.
In order to manufacture a high quality printed circuit board, via holes must be accurately formed.

FIG. 17 is a schematic perspective view showing a part of a printed circuit board in the process of being formed.
Is a core material, 11 is a wiring layer, 12 is an insulating layer, 13 is a precisely formed via hole, 14 is a via hole having the remaining insulating material 15 at the bottom, 16 is a small diameter via hole, and 17 is a via hole. Is the part to be formed.

In the case where the insulating material remains 15 at the bottom like the via hole 14, the diameter of the via hole is small like the via hole 16, or there is no via hole in the portion 17 where the via hole is to be formed. Causes a serious problem that the connection between the wiring layer 11 and the wiring layer formed on the insulating layer 12 cannot be achieved.

Therefore, when forming a printed circuit board by the build-up method, if a via hole is formed in the insulating layer, it is necessary to inspect the shape of the via hole before forming a metal film inside the via hole. There is. Conventionally, such via hole shape inspection has been performed visually.

[0011]

However, in the inspection of the shape of a via hole by visual inspection, a large amount of time is required for the inspection, and it is difficult to find a defect in a minute via hole, and the reliability is low. There was a point.

In view of the above, the present invention automatically performs a highly reliable shape inspection in a short time on the shape of a via hole formed in an insulating layer when a printed board is formed by a build-up method. It is an object of the present invention to provide a via hole shape inspection device that can perform the inspection.

[0013]

According to a first aspect of the present invention, there is provided a via hole shape inspection apparatus according to the first aspect, wherein a via hole formed in an insulating layer is formed when a printed board is formed by a build-up method. A via hole shape inspection device for inspecting the shape of a hole, wherein a plurality of illuminating means for illuminating a via hole forming surface from obliquely above so as to illuminate the entire bottom portion of the via hole if the via hole is normal, An imaging unit that captures an image of the hole forming surface in the vertical direction and outputs an image signal of the via hole forming surface, and each pixel is determined based on a luminance state of each pixel of the image of the via hole forming surface obtained through the imaging unit. A luminance characteristic information extraction circuit for extracting luminance characteristic information of an image of a predetermined size as a central pixel as luminance characteristic information of a central pixel of the image of a predetermined size, and a luminance characteristic extracted by the luminance characteristic information extracting circuit Attention d from information A feature information extraction circuit for extracting the feature information included in the A, based on the feature information feature information extraction circuit is extracted, it is that and a defect via hole detection circuit for detecting a defect via hole.

According to the first aspect of the present invention, if the via hole is a normal via hole, the via hole forming surface is obliquely illuminated from above and the via hole forming surface is illuminated so that the entire bottom surface of the via hole can be illuminated. Image is taken from the vertical direction, luminance characteristic information of an image of a predetermined size with each pixel as a central pixel is extracted as luminance characteristic information of a central pixel of the image of a predetermined size, and a via hole is extracted from the luminance characteristic information. Since the feature information is extracted and the defective via hole is detected based on the feature information,
With respect to the shape of the via hole formed in the insulating layer, a highly reliable shape inspection can be automatically performed in a short time.

According to a second aspect of the present invention, in the first aspect of the present invention, in the first aspect, the plurality of illuminating means illuminate the via hole forming surface from a diagonally upper left side.
Illuminating means and a second illuminating means for illuminating the via hole forming surface from obliquely right above.

According to a third aspect of the present invention, there is provided a via hole shape inspection apparatus according to the third aspect, wherein the first and second illuminating means are arranged such that the first and second illuminating means are linearly illuminated on the via hole forming surface. It is to collect light.

According to a fourth aspect of the present invention, there is provided a via hole shape inspection apparatus according to the fourth aspect of the present invention, wherein the plurality of illuminating means are the wavelengths which the insulating layer easily absorbs. It is intended to illuminate a light beam containing a large number of light beams.

According to a fifth aspect of the present invention, there is provided a via hole shape inspection apparatus according to the fifth aspect, wherein the plurality of illumination means have a wavelength of 400 [nm] or less in the first, second, or third aspect. Is used as illumination light.

According to a sixth aspect of the present invention, there is provided a via hole shape inspection apparatus according to the sixth aspect, wherein the luminance characteristic information extracting circuit is the first, second, third, fourth, or fifth aspect. An image cutout circuit for sequentially cutting out an image of a predetermined size with each pixel as a central pixel from the image of the via hole forming surface, and an image cutout circuit for obtaining luminance characteristic information of the image of a predetermined size cut out by the image cutout circuit. And a luminance characteristic information calculating circuit that calculates based on the luminance of the pixels in the extracted image of a predetermined size.

In the present invention, the seventh invention (the via hole shape inspection apparatus according to claim 7) includes the first, second, third, fourth, and fifth aspects.
Alternatively, in the sixth aspect, the luminance characteristic information includes a luminance average value obtained by averaging luminance of all pixels in an image of a predetermined size, a maximum luminance difference between pixels in an image of a predetermined size, The number of pixels in a predetermined direction that can be regarded as having the same luminance as the center pixel in the image, the luminance difference in each direction between pixels at the outer edge in an image of a predetermined size, the average luminance value in each direction in an image of a predetermined size, or That is, it includes an average luminance value in a predetermined radial direction in an image of a predetermined size.

[0021] In the present invention, the eighth invention (via hole shape inspection apparatus according to claim 8) includes first, second, third, fourth, fifth, and fifth aspects.
In the sixth or seventh aspect, the characteristic information extracting circuit includes: a luminance characteristic information selecting circuit for selecting luminance characteristic information necessary for calculating characteristic information of the attention area from the luminance characteristic information extracted by the luminance characteristic information extracting circuit; And a characteristic information calculation circuit that calculates characteristic information of the area of interest from the luminance characteristic information output from the characteristic information selection circuit.

According to a ninth aspect of the present invention, there is provided a via hole shape inspection apparatus according to the ninth aspect of the present invention, wherein the first, second, third, fourth, fifth, sixth, seventh or eighth aspect of the present invention is provided. In the defect via hole detection circuit, the distribution state of the characteristic information in the radial direction from the center of the via hole is measured, and the distribution state information of the characteristic information in the radial direction from the center of the via hole is compared with the reference information to determine the defect state. It is provided with a radial determination circuit for detecting a candidate via hole and a macro determination circuit for determining the presence or absence of a defect in the defect candidate via hole based on the situation around the defect candidate via hole.

In the present invention, the tenth invention (the via hole shape inspection apparatus according to the tenth aspect) includes first, second, third, fourth,
In the fifth, sixth, seventh, eighth, or ninth inventions, the center position of the via hole detected from the feature information is compared with the center position of the via hole included in the design information to determine the position of the via hole. Is provided with a via hole presence / absence determination circuit for determining the presence / absence of a hole.

[0024]

FIG. 1 is a conceptual diagram of one embodiment of the present invention. In FIG. 1, reference numeral 20 denotes a printed circuit board which is a target of a via hole shape inspection in the middle of being formed by the build-up method, and 20A denotes a via hole forming surface of the printed circuit board 20.

An image sensing unit 21 senses an image on the via hole forming surface 20A of the printed circuit board 20.
Reference numeral 22 denotes an image signal processing unit that processes an image signal obtained from the image sensing unit 21 to detect a defective via hole.

In the image sensing section 21, 2
Reference numeral 3 denotes a lamp (for example, a xenon lamp, a halogen lamp, and a mercury lamp) containing a large amount of light ranging from blue light to ultraviolet light, 24 denotes a reflecting mirror that reflects light emitted backward from the lamp 23 forward, and 25 denotes a reflecting mirror It is a condenser lens that collects light emitted forward and reflected light from the reflection mirror 24.

Reference numeral 26 denotes a bundle of optical fibers for transmitting the light condensed by the condenser lens 25, and reference numeral 27 denotes a line light source by arranging the output ends of the individual optical fibers of the bundle of optical fibers 26 in a line. The illumination light emission head 28 is a cylindrical lens that condenses the illumination light emitted from the illumination light emission head 27 in a line.

Reference numeral 29 denotes a lamp (for example, a xenon lamp, a halogen lamp, or a mercury lamp) including many light rays from blue light to ultraviolet light, like the lamp 23. Reference numeral 30 denotes light emitted backward from the lamp 29. And 31 is a condenser lens for condensing the light emitted forward from the lamp 29 and the reflected light from the reflection mirror 30.

Reference numeral 32 denotes a bundle of optical fibers for transmitting the light collected by the condenser lens 31, and reference numeral 33 denotes a line light source by arranging the output ends of the individual optical fibers of the bundle of optical fibers 31 in a line. The constituent illumination light emitting heads 34 are cylindrical lenses that converge the illumination light emitted from the illumination light emitting head 33 in a line.

In one embodiment of the present invention, a lamp 23, a reflection mirror 24, a condenser lens 25, an optical fiber bundle 26,
Illuminating light emitting head 27 and cylindrical lens 28
Thus, a first illuminating means for illuminating the via hole forming surface 20A of the printed board 20 from diagonally upper left is configured.

A lamp 29, a reflecting mirror 30, a condenser lens 31, a bundle 32 of optical fibers, an illumination light emitting head 3
3 and the cylindrical lens 34, the printed circuit board 20
A second illumination means for illuminating the via hole forming surface 20A from obliquely right above is formed.

Reference numeral 35 denotes a light receiving lens for receiving the light reflected in the vertical direction due to scattering among the light reflected from the via hole forming surface 20A of the printed circuit board 20, and 36 denotes a printed circuit board via the light receiving lens 35. 20 via hole forming surfaces 2
This is a one-dimensional CCD camera for imaging 0A. Note that a two-dimensional CCD camera can also be used.

FIGS. 2 and 3 are schematic perspective views for explaining the operation of the image sensing unit 21. A part of the printed circuit board 20 being formed is cut out.

2 and 3, reference numeral 38 denotes a core material, 3
Reference numeral 9 denotes a wiring layer, reference numeral 40 denotes an insulating layer, and reference numeral 41 denotes a via hole. In one embodiment of the present invention, illumination light is applied to the via hole forming surface 20A of the printed circuit board 20 from diagonally upper left and diagonally upper right. I am trying to do it.

Here, an insulating layer 40 made of polyimide or the like is used.
Has a property of absorbing light rays from blue light to ultraviolet light well, and as shown in FIG. 2, the illumination light 42 radiated to the insulating layer 40 from the upper left and the insulating layer from the upper right. Most of the illumination light 43 applied to the light 40 is absorbed by the insulating layer 40, and a small amount is reflected by the insulating layer 40.

Since the surface of the insulating layer 40 is usually mirror-like, among the illuminating lights 42 applied to the insulating layer 40 from diagonally upper left, the illuminating light not absorbed by the insulating layer 40 is diagonally right. Among the illumination light 43 that is reflected upward and illuminates the insulating layer 40 from diagonally right above, the illumination light that is not absorbed by the insulating layer 40 is reflected diagonally upward and left. The reflected light is received by the light receiving lens 35.
Will not be received.

When the insulating layer 40 is made of polyimide, the polyimide has a wavelength of 400 [nm].
As it absorbs the following ultraviolet rays well,
A light source that emits ultraviolet light having a wavelength of 400 [nm] or less is most suitable.

On the other hand, since the surface of the wiring layer 39 is not a mirror-like surface but a scattering surface, the illumination irradiating the exposed surface 39 A of the wiring layer 39 which is the bottom surface of the via hole 41. The lights 44 and 45 are scattered on the exposed surface 39A of the wiring layer 39, and the reflected lights 46 and 47 scattered in the vertical direction are received by the light receiving lens 35.

Further, as shown in FIG.
When the illumination light 49 is radiated only obliquely from the upper left to the via hole forming surface 20A of 0, a shadow 50 is generated on the bottom surface of the via hole 41 near the wall that is invisible from the illumination light 49 side,
When the illumination light 51 is applied to the via hole forming surface 20A of the printed circuit board 20 only from the obliquely upper right side, a shadow 52 is formed on the bottom surface of the via hole 41 near the wall which is not visible from the illumination light 51 side.

However, in one embodiment of the present invention,
Since the illumination lights 49 and 51 are simultaneously illuminated obliquely from above and below the via hole forming surface 20A of the printed circuit board 20, if the via hole 41 is a normal via hole, the entire bottom surface can be illuminated. Although the brightness of the bottom portion near the wall of the via hole 41 is darker than the brightness of the central portion,
Complete shadows 50 and 52 do not occur on the bottom surface of the via hole 41.

Therefore, according to the embodiment of the present invention, the image obtained by the one-dimensional CCD camera 36 has a dark image in the portion of the insulating layer 40 and a bright image in the portion of the wiring layer 39A on the bottom surface of the via hole 41. Thus, an image signal having a large difference in strength between the wiring layer portion and the insulating layer portion can be obtained.

FIG. 4 is a diagram showing the relationship between the shape of the via hole and the image signal output from the one-dimensional CCD camera 36.
FIG. 4A is a schematic perspective view showing a part of the printed circuit board 20 in the process of being formed, and FIG. 4B is a view showing a P-P output from the one-dimensional CCD camera 36 when the PP line is a horizontal line.
It is a waveform diagram which shows the image signal along the -P line.

In FIG. 4A, 56 is a wiring layer, 57 is a precisely formed via hole, and 58 is the remaining insulating material 59 at the bottom.
4B, there is a via hole having a small diameter, and 60 is a via hole having a small diameter.
In the figure, reference numeral 61 denotes an image signal corresponding to the via hole 57;
Is an image signal corresponding to the via hole 58, and 63 is an image signal corresponding to the via hole 60.

As described above, in the embodiment of the present invention, in the case of the via hole 58 having the remaining insulating material 59 at the bottom, the intensity of the image signal in the portion where the insulating layer 59 exists becomes weak, and In the case of the small via hole 60, the signal width becomes narrow, and in any case, the image signal is not obtained as obtained in the case of the normal via hole 57.

FIG. 5 is a block circuit diagram showing the configuration of the image signal processing section 22. In FIG. 5, reference numeral 65 denotes an A / D converter for converting an analog image signal output from the one-dimensional CCD camera 36 into an 8-bit digital image signal.

Reference numeral 66 denotes an image of 3 dots (horizontal direction) × 3 dots (vertical direction) including each pixel based on the digital image signal output from the A / D converter 65. This is a luminance characteristic information extraction circuit that extracts the luminance characteristic of the pixel as luminance characteristic information of each pixel.

Reference numeral 67 denotes a characteristic information extraction circuit for extracting characteristic information of the area of interest from luminance characteristic information of each pixel extracted by the luminance characteristic information extraction circuit 66. Reference numeral 68 denotes characteristic information extracted by the characteristic information extraction circuit 67. Is a defective via-hole detection circuit that detects a defective via-hole based on.

In the luminance characteristic information extraction circuit 66, reference numeral 69 denotes a line memory unit for enabling a digital image signal output from the A / D converter 65 to be grasped as a three-line image. As shown in FIG. 6, reference numeral 69 denotes a configuration in which line memories 71, 72, and 73 are connected in cascade.

The line memories 71, 72, 73
Each of them is constituted by a shift register having the same number of bits as the number of pixels of the horizontal line in the direction of transmitting the digital pixel signal.

In FIG. 5, reference numeral 75 denotes an image cutout circuit for cutting out a 3 × 3 dot image including each pixel from the digital image signal of 3 lines stored in the line memory section 69. It is configured as shown separately in FIGS. 6 and 7.

In FIG. 6, in the image cutout circuit 75,
77, 78, and 79 are registers for storing pixel signals of a 3 × 3 dot image; 80, 81, and 82 are also registers for storing pixel signals of a 3 × 3 dot image; and 83 is a 0 ° direction including a central pixel. This is a register for storing digital pixel signals.

In FIG. 7, in the image cutout circuit 75, 84, 85 and 86 are registers for storing pixel signals in the 45 ° direction including the central pixel, and 87, 88 and 89 are registers in the 90 ° direction including the central pixel. A register for storing pixel signals,
Reference numerals 90, 91 and 92 are registers for storing pixel signals in the 135 ° direction including the central pixel.

In FIG. 5, reference numeral 94 denotes a luminance characteristic information calculation circuit for calculating luminance characteristic information of an image cut out by the image cut-out circuit 75. The luminance characteristic information calculation circuit 94 is shown in FIGS. 6 and 7. It is configured as shown separately.

In FIG. 6, in a luminance characteristic information calculating circuit 94, a 96 calculates a luminance average value obtained by averaging the luminance of all the pixels in the cut-out image from the pixel signals stored in the registers 77, 78 and 79. Is a luminance average value calculating circuit.

Reference numeral 97 denotes a difference between the luminance of the pixel having the maximum luminance and the luminance of the pixel having the minimum luminance from the pixel signals stored in the registers 80, 81, and 82, that is, the maximum luminance between pixels included in the cut-out image. It is a maximum luminance difference calculation circuit between pixels for calculating a difference.

Reference numeral 98 denotes a 0 ° direction measurement for calculating the number of pixels in the 0 ° direction having a luminance that can be regarded as the same as the luminance of the center pixel from the pixel signals in the 0 ° direction stored in the register 83 as a length measurement value. This is a long value calculation circuit.

In FIG. 7, a luminance characteristic information calculating circuit 94
In 99, the number of pixels in the 45 ° direction having the luminance that can be regarded as the same as the luminance of the center pixel is calculated from the pixel signals in the 45 ° direction stored in the registers 84, 85, and 86 as the length measurement value. This is a measurement value calculation circuit.

Also, 100 is a register 87, 88, 89
Is a 90 ° direction measurement value calculation circuit that calculates the number of pixels in the 90 ° direction having a luminance that can be regarded as being the same as the luminance of the central pixel from the 90 ° direction pixel signal stored in the 90 ° direction measurement value.

Reference numeral 101 denotes registers 90, 91 and 92.
Is a 135 ° direction length measurement value calculation circuit that calculates, as a length measurement value, the number of 135 ° direction pixels having luminance that can be regarded as being the same as the luminance of the central pixel from the 135 ° direction pixel signal stored in.

As described above, in one embodiment of the present invention, the luminance characteristic information of the cut-out image includes a luminance average value, a maximum luminance difference between pixels, a 0 ° direction measurement value, a 45 ° direction measurement value, and a 90 ° direction measurement value. The length measurement value in the 135 ° direction and the length measurement value in the 135 ° direction are extracted. In addition, a luminance difference in each direction between pixels at the outer edge of the cut image may be extracted.

Here, when a large image such as 17 × 17 dots is cut out, the luminance average value in each direction or the luminance in all directions is measured using a radial length measuring sensor as shown in FIG. When the average value is obtained, the load on the circuit can be reduced. In particular, when the average luminance value for each direction is obtained, a defect existing only in one direction can be detected.

In FIG. 8, reference numeral 103 denotes a 0 ° direction sensor system for sensing a 0 ° image, 104 denotes a 45 ° direction sensor system for sensing a 45 ° image, and 105 denotes a 9 sensor.
A 90 ° direction sensor system for sensing an image in a 0 ° direction, and 106 is a sensor for sensing an image in a 135 ° direction.
This is a 35 ° direction sensor system.

In FIG. 5, reference numeral 108 denotes a luminance characteristic information memory for storing the luminance characteristic information calculated by the luminance characteristic information calculating circuit 94. Although the calculated value may be stored as it is, the luminance characteristic information calculating circuit 94
May be stored such that the number of bits is reduced by quantizing the calculated value of.

FIG. 9 is a conceptual diagram showing a part of the luminance characteristic information memory 108 and the whole image 109. In FIG. 9, in the luminance characteristic information memory 108, reference numeral 110 denotes a luminance average value storage unit that stores a luminance average value, and 111 denotes a pixel-to-pixel maximum luminance difference storage unit that stores a pixel-to-pixel maximum luminance difference.

Reference numeral 112 denotes a 0 ° direction measurement value storage unit that stores a 0 ° direction measurement value, 113 denotes a 45 ° direction measurement value storage unit that stores a 45 ° direction measurement value, and 114 denotes a 90 ° direction measurement value. 90 ° direction measurement value storage unit for storing the measurement value, 115
Is a 135 ° direction measurement value storage unit that stores the 135 ° direction measurement value.

Here, the luminance characteristic information memory 108 has a storage unit corresponding to each pixel of the whole image 109,
In the whole image 109, for example, the luminance characteristic information of the cut image in the range of X2 in the horizontal direction and the range of Y2 in the vertical direction is stored in the portion indicated by the arrow A1 as the luminance characteristic information of the central pixel, and X3 in the horizontal direction. And the luminance characteristic information of the partial image in the range of Y3 in the vertical direction is stored in the part indicated by the arrow A2 as the luminance characteristic information of the central pixel.

As described above, the luminance characteristic information memory 108
Is configured to store the luminance characteristic information of the cut-out image as luminance characteristic information of the center pixel in a storage unit provided corresponding to each pixel.
10 to 115 respectively form an image of the luminance characteristic information.

In the feature information extraction circuit 67, 1
Reference numeral 19 denotes a luminance characteristic information selection circuit for selecting luminance characteristic information from the luminance characteristic information memory 108. The luminance characteristic information selection circuit 119, as shown in FIG. It operates to select the corresponding luminance characteristic information by designating the coordinates X, Y, and Z.

In the characteristic information extracting circuit 67 in FIG. 5, reference numeral 120 denotes a characteristic information calculating circuit for calculating characteristic information of the area of interest from the luminance characteristic information selected via the luminance characteristic information selecting circuit 119. The feature information calculation circuit 120 calculates feature information as shown in FIGS. 11 and 12, for example.

In the example shown in FIG. 11, the characteristic information calculating circuit 1
Reference numeral 20 selects, via the luminance characteristic information selection circuit 119, the luminance average value stored in the storage unit corresponding to the attention area of the luminance average value storage unit 110 of the luminance characteristic information memory 108, and selects the maximum value and the minimum value. The difference from the value is calculated as feature information of the area of interest.

In the example shown in FIG. 12, the feature information extraction circuit 1
20 selects the 0 ° direction measurement value stored in the storage unit corresponding to the attention area of the 0 ° direction measurement value storage unit 112 of the luminance characteristic information memory 108 via the luminance characteristic information selection circuit 119; These average values are calculated as feature information of the area of interest.

As described above, the characteristic information calculation circuit 120
In the case of a normal via hole, luminance characteristic information of a pixel that would have the same value is selected, and this is processed so as to easily detect a defect candidate via hole to obtain feature information.

In FIG. 5, in a defective via hole detecting circuit 68, a center 121 detects the center of the via hole from the characteristic information calculated by the characteristic information calculating circuit 120, and emits the characteristic information from the center of the via hole. Is a radial determination circuit that measures the distribution state information of the radial direction and compares the distribution state information in the radial direction with the reference information to detect a defect candidate via hole.

Here, in the case of a normal via hole, the brightness distribution is such that the periphery is dark and the center is bright, so that the center of the via hole in the characteristic information such as the average brightness and the degree of change in brightness. Of the distribution state information in the radial direction is measured.

In the case of a normal via hole, the inclination characteristic of the brightness change is the same toward the center on the same radius, so that only the value of the brightness change in the direction toward the center is extracted. , Their values should be the same.

Reference numeral 122 denotes a macro judgment circuit for judging the presence / absence of a defect candidate via hole from the situation around the defect candidate via hole detected by the radial judgment circuit 121. The macro judgment circuit 122 includes a radial judgment circuit. Circuit 12
1 is provided with a defect evaluation memory for storing the peripheral situation information of the defect candidate via hole detected by the defect evaluation via hole 1.

FIG. 13 is a block circuit diagram showing a part of the radial determination circuit 121. In FIG. 13, reference numeral 124 denotes average value information of the measured values output from the characteristic information calculation circuit 120, and reference numeral 125 denotes the characteristic information calculation circuit 120. Is the density gradient information output from.

Reference numeral 126 denotes the center of the via hole from the average value information 124 and the density gradient information 125, and is used to detect the center address of the via hole used to determine the presence or absence of the via hole and to detect the defect candidate via hole. This is a via hole center detection circuit that outputs information on the center position of the via hole.

Further, 127 is CAD data, and 128 is C data.
The center address of the via hole included in the AD data 127;
A via hole is compared with an address of a via hole detected by the via hole center detection circuit 126 to determine the presence or absence of a via hole at a position designated by CAD data and a position not designated by CAD data on the via hole forming surface 20A of the printed circuit board 20. This is a hole presence / absence determination circuit.

FIG. 14 is a diagram showing a first configuration example of the macro decision circuit 122. In FIG. 14, reference numeral 129 denotes a defect evaluation memory for storing peripheral situation information of a defect candidate via hole,
Reference numeral 30 denotes a CPU (central processing unit) that transfers the situation around the defect candidate via hole to the defect evaluation memory 129 and determines whether there is a defect in the defect candidate via hole.

FIG. 15 is a diagram showing a second configuration example of the macro decision circuit 122. In FIG. 15, reference numeral 131 denotes a defect evaluation memory for storing the peripheral situation information of the defect candidate via hole,
Reference numeral 32 denotes a DSP (digital signal processor) that transfers the situation around the defect candidate via hole to the defect evaluation memory 129 and determines whether there is a defect in the defect candidate via hole.

The CPU 130 and DSP 132
Instead of using a dedicated circuit, the macro decision circuit 122
Can also be configured.

As described above, according to the embodiment of the present invention, the illumination light is simultaneously applied to the via hole forming surface 20A of the printed circuit board 20 from diagonally above right and left. And lighting so that you can
As the illuminating light, a light beam including many light beams from blue light to ultraviolet light which the insulating layer easily absorbs is used, and an image of the via hole forming surface 20A of the printed circuit board 20 is taken in a vertical direction. An image signal having a large difference in strength between the wiring layer portion and the insulating layer portion can be obtained.

According to the embodiment of the present invention, even if the via hole is normal, the bottom surface close to the wall becomes darker than the center, but the print obtained through the one-dimensional CCD camera 36 is obtained. From the image of the via hole forming surface 20A of the substrate 20, luminance characteristic information of a 3 × 3 dot image centered on each pixel is extracted as luminance characteristic information of each pixel, and the characteristic of the via hole is extracted from the luminance characteristic information. Since the information is extracted and the radial judgment and the macro judgment are performed based on this characteristic information, a highly reliable shape inspection is automatically performed in a short time with respect to the shape of the via hole formed in the insulating layer. be able to.

Further, according to the embodiment of the present invention, since the via hole presence / absence determination circuit 128 is provided, the position specified by the CAD data and the position not specified by the CAD data on the via hole forming surface 20 A of the printed circuit board 20. , The presence or absence of a via hole can be determined, and excess or deficiency of the via hole can be detected.

[0086]

As described above, according to the first invention (via hole shape inspection apparatus according to claim 1) of the present invention, if the via hole is normal, the entire bottom surface of the via hole can be illuminated. In addition, while illuminating the via hole forming surface from obliquely above, the via hole forming surface is imaged in the vertical direction, and luminance characteristic information of an image of a predetermined size with each pixel as a central pixel is an image of a predetermined size. Is extracted as luminance characteristic information of the center pixel of the pixel, characteristic information of the via hole is extracted from the luminance characteristic information, and a defective via hole is detected based on the characteristic information. About the shape of the hole,
A highly reliable shape inspection can be automatically performed in a short time.

According to the second aspect of the present invention (the via hole shape inspection apparatus according to the second aspect), the same effect as that of the first aspect can be obtained, and the minimum number of illuminating means can be achieved. If the via hole is normal, the entire bottom surface of the via hole can be illuminated, and the device can be simplified.

According to the third aspect of the present invention, the same effect as in the second aspect can be obtained, and the one-dimensional line sensor can be used as the image pickup means. When used, imaging can be easily performed.

In the present invention, the fourth or fifth invention (Claim 4)
According to the via hole shape inspection device described in (5), the same effect as in the first, second, or third invention can be obtained, and the light passes through the insulating layer, is scattered by the wiring layer, and is again in the insulating layer. , And the generation of light rays that go upward in the vertical direction can be suppressed, so that an image signal having a large difference in intensity between the wiring layer portion and the insulating layer portion can be obtained.

According to the sixth aspect of the present invention (via hole inspection apparatus according to claim 6), the first, second, third, and fourth aspects of the present invention are provided.
Alternatively, the same effect as that of the fifth invention can be obtained, and the luminance characteristic information extraction circuit can be made simple.

According to the seventh aspect of the present invention, the same effect as the first, second, third, fourth, fifth or sixth aspect of the present invention is obtained. Can be obtained, and the detection accuracy of the defective via hole can be improved.

According to the eighth aspect of the present invention, the first, second, third, fourth and fourth via hole inspection apparatuses are provided.
The same effects as those of the fifth, sixth, or seventh invention can be obtained, and the feature information extracting circuit can have a simple configuration.

According to the ninth aspect of the present invention, the first, second, third, fourth, fifth, sixth, seventh or eighth aspect of the invention is directed to a via hole shape inspection apparatus according to the ninth aspect. The same effect as that of the present invention can be obtained, and the defective via hole detection circuit can have a simple configuration.

According to the tenth aspect of the present invention, the first, second, third, and third via hole inspection apparatuses are provided.
The same effect as that of the fourth, fifth, sixth, seventh, eighth, or ninth invention can be obtained, and excess or deficiency of via holes on the via hole forming surface of the printed circuit board can be detected.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment of the present invention.

FIG. 2 is a schematic perspective view for explaining an operation of an image sensing unit provided in one embodiment of the present invention.

FIG. 3 is a schematic perspective view for explaining an operation of an image sensing unit provided in one embodiment of the present invention.

FIG. 4 is a view showing a shape of a via hole and 1 provided in an embodiment of the present invention.
FIG. 4 is a diagram illustrating a relationship with an image signal output from a two-dimensional CCD camera.

FIG. 5 is a block circuit diagram illustrating a configuration of an image signal processing unit included in an embodiment of the present invention.

FIG. 6 illustrates a line memory unit according to an embodiment of the present invention;
FIG. 3 is a block circuit diagram illustrating a part of an image cutout circuit and a part of a luminance characteristic information calculation circuit.

FIG. 7 is a block circuit diagram illustrating a part of an image cutout circuit and a part of a luminance characteristic information calculation circuit included in an embodiment of the present invention.

FIG. 8 is a conceptual diagram illustrating an example of a radial image sensor.

FIG. 9 is a conceptual diagram showing a part and an entire image of a luminance characteristic information memory included in an embodiment of the present invention.

FIG. 10 is a conceptual diagram illustrating a selection operation of a luminance characteristic information selection circuit included in an embodiment of the present invention.

FIG. 11 is a conceptual diagram for describing an operation example of a feature information calculation circuit included in an embodiment of the present invention.

FIG. 12 is a conceptual diagram for describing an operation example of a feature information calculation circuit included in an embodiment of the present invention.

FIG. 13 is a block circuit diagram illustrating a part of a radial determination circuit included in an embodiment of the present invention.

FIG. 14 is a diagram illustrating a first configuration example of a macro decision circuit included in an embodiment of the present invention.

FIG. 15 is a diagram illustrating a second configuration example of the macro decision circuit included in the embodiment of the present invention.

FIG. 16 is a schematic perspective view showing a part of an example of a printed circuit board formed by a build-up method.

FIG. 17 is a schematic perspective view showing a cut-out portion of a printed circuit board being formed.

[Explanation of symbols]

 Reference Signs List 20 printed circuit board 20A via hole forming surface 21 image sensing unit 22 image signal processing unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Taniguchi 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Satoru Sakai 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Inside Fujitsu Limited (72) Inventor Hideo Okada 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited

Claims (10)

[Claims] 1. A via hole shape inspection device for inspecting the shape of a via hole formed in an insulating layer when a printed circuit board is formed by a build-up method. A plurality of illuminating means for illuminating the via hole forming surface from obliquely above so as to illuminate the entire surface; an imaging means for imaging the via hole forming surface from a vertical direction and outputting an image signal of the via hole forming surface; Based on the luminance state of each pixel of the image of the via hole forming surface obtained via the imaging unit, luminance characteristic information of an image of a predetermined size with each pixel as a central pixel is converted to the predetermined size. A luminance characteristic information extraction circuit that extracts as luminance characteristic information of the central pixel of the image; a characteristic information extraction circuit that extracts characteristic information of the area of interest from the luminance characteristic information extracted by the luminance characteristic information extraction circuit; Based on the feature information extracted by the feature information extraction circuit,
A via hole shape inspection device, comprising: a defective via hole detection circuit for detecting a defective via hole. 2. The plurality of illuminating means are a first illuminating means for illuminating the via hole forming surface from an obliquely upper left and a second illuminating means for illuminating the via hole forming surface from an obliquely upper right. The via hole shape inspection apparatus according to claim 1, wherein: 3. The via hole shape inspection apparatus according to claim 2, wherein said first and second illuminating means converge linear illumination light on said via hole forming surface. 4. A via hole shape inspection according to claim 1, wherein said plurality of illuminating means illuminate a light beam containing a large number of light beams having a wavelength which is easily absorbed by said insulating layer. apparatus. 5. A lighting device according to claim 1, wherein said plurality of illumination means have a wavelength of 400 [n].
The via hole shape inspection apparatus according to claim 1, wherein ultraviolet light below m] is used as illumination light. 6. An image extraction circuit for sequentially extracting an image of a predetermined size with each pixel as a central pixel from an image of the via hole forming surface, and a predetermined image extracted by the image extraction circuit. And a luminance characteristic information calculating circuit that calculates luminance characteristic information of the image having the size based on the luminance of pixels in the image of a predetermined size cut out by the image cutout circuit. Item 7. A via hole shape inspection apparatus according to any one of Items 1, 2, 3, 4, and 5. 7. The luminance characteristic information includes: a luminance average value obtained by averaging luminance of all pixels in the image of the predetermined size; a maximum luminance difference between pixels in the image of the predetermined size; Number of pixels in a predetermined direction that can be regarded as having the same luminance as the center pixel in the image of the same size, a luminance difference in each direction between outer edge pixels in the image of the predetermined size, and a direction difference in the image of the predetermined size. The via hole shape inspection apparatus according to claim 1, 2, 3, 4, 5, or 6, comprising an average luminance value or an average luminance value in a predetermined radial direction in the image of the predetermined size. 8. A luminance characteristic information selecting circuit for selecting luminance characteristic information necessary for calculating characteristic information of an area of interest from the luminance characteristic information extracted by the luminance characteristic information extracting circuit; 3. A feature information calculation circuit for calculating feature information of the area of interest from luminance characteristic information output from the information selection circuit.
The via hole shape inspection apparatus according to 3, 4, 5, 6, or 7. 9. The defective via hole detection circuit measures a distribution state of the characteristic information in a radial direction from the center of the via hole, and references the distribution state information of the characteristic information in a radial direction from the center of the via hole. A radial determination circuit that detects a defect candidate via hole by comparing with information; and a macro determination circuit that determines the presence or absence of a defect in the defect candidate via hole from a situation around the defect candidate via hole. Claims 1, 2, 3, 4, 5, 6, 7
Or a via hole shape inspection apparatus according to 8. 10. A via hole presence / absence determination circuit for comparing the center position of a via hole detected from the characteristic information with the center position of the via hole included in the design information to determine the presence / absence of a via hole. Claims 1, 2, 3, 4,
The via hole shape inspection apparatus according to 5, 6, 7, 8 or 9.