JPH02297047A - Pattern inspecting method for printed board - Google Patents

Abstract

PURPOSE:To eliminate an effect caused by looseness or inclination in the edge of a through hole by expanding at least one of a pattern image and a hole image and obtaining an area where both images are superposed. CONSTITUTION:There is comparatively a little reflected light in a base B, where a signal at a level between threshold TH1 and threshold TH2(TH1<TH2) is generated. Since a land R is formed of metal such as copper, etc., there is much reflected light in this part, where a signal at a level equal to or above the threshold TH2 is generated. The signal at the same level is generated in a wiring pattern. There is little reflected light in the through hole H, where the signal at the level equal or below the threshold TH1 is generated. Usually, the edge E formed at the time of drilling exists between the through hole H and the land R. The looseness or the inclination exists in this part, where the level of the reflected light does not become a certain value particularly but is nearly between the threshold TH1 and the threshold TH2.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for inspecting patterns of printed circuit boards, particularly wiring patterns and through holes (including mini-via holes).
This invention relates to an inspection method for determining the quality of relative positional deviation.

[Conventional technology]

As electronic components become smaller, lighter, and more sophisticated, printed circuit board circuit patterns are also becoming smaller and more dense.
There is a demand for thinner patterns and smaller diameter through holes. In particular, as a through hole for conduction in a multilayer board,
0.5mm diameter is even smaller than the previous 0.8mm diameter
A through hole called a mini-via hole with a diameter of ~0.1 is currently used.

As through-holes become smaller in diameter, new technologies are needed in various areas such as through-hole plating, drilling, and reliability testing.

Drilling is generally less precise than photoetching processes, and through holes often deviate from the pattern. For through holes with a diameter of about 0.81,
A sufficiently large land was provided around it, so even if the through hole was slightly misaligned, the effect on the electrical reliability of the board was minimal.

However, as the diameter of through-holes has become smaller, lands have also become smaller, and the accuracy of drilling holes for through-holes in lands can no longer be guaranteed.

Therefore, a decrease in the electrical reliability of the printed circuit board due to the misalignment of the holes becomes a problem, and the importance of inspecting the misalignment of the through-holes increases.

Inspecting hole misalignment requires approaches from both electrical inspection and visual inspection.

In visual inspection, inspection machines that detect light leaking from cracks in plating are known, but as boards become more multi-layered, various problems have been pointed out. Further, it cannot be applied to inspection of pattern breakage caused by relative positional deviation between a through hole and a pattern.

Figures 16A and 16B show land R and through hole H.
It is a figure showing the relative positional relationship with. In FIG. 16A, the center 0 of the through hole H coincides with the center of the land R, resulting in a good pattern. In FIG. 16B, the center of the land R and the center O of the through hole H are shifted from each other, and a portion of the through hole H protrudes to the outside of the land R. The size of this protruding portion is determined by the aperture angle θ. When the aperture angle θ is larger than a predetermined standard, the pattern breakage is determined to be defective.

Figures 17A and 17B show the straight line portion PL of the wiring pattern.
3 is a diagram showing the relative positional relationship between the through hole H and the through hole H. FIG.

In FIG. 17A, the center 0 of the through hole is located on the center line CL of the straight portion PL, resulting in a good pattern. In FIG. 17B, the center line CL and the center O
is shifted, and a portion of the through hole H protrudes outside the straight portion PL. The size of this protruding portion is also determined by the aperture angle θ, and when the aperture angle θ is larger than a predetermined standard, the pattern breakage is determined to be defective.

As described above, the quality of pattern breakage can be determined by determining the aperture angle θ, but in many conventional inspections, this determination has been made by visual inspection using a magnifying lens or the like.

In addition, when aiming to automate the judgment, it is necessary to accurately read the image of the through hole or wiring pattern, but the opening edge of the through hole H has uneven optical reflection characteristics, wobbles, slopes, etc. This makes it difficult to accurately binarize images of through holes and lands.

[Problem to be solved by the invention]

As described above, the conventional printed circuit board pattern inspection method relies on human visual inspection, which has the problems of inconsistent judgment criteria depending on the subjectivity of the inspector and poor inspection efficiency.

Further, in the technology intended to automate inspection, there is a problem in that it is difficult to binarize the opening edge of a through hole, and it is difficult to accurately determine the opening angle.

[Purpose of the invention]

The present invention has been made in consideration of the above circumstances, and aims to provide a printed circuit board pattern inspection method that enables automation of printed circuit board pattern inspection and accurate aperture angle determination. purpose.

[Means to solve the problem]

A pattern inspection method for a printed circuit board having a first configuration according to the present invention photoelectrically scans the printed circuit board and detects the relative relationship between the wiring pattern and the through hole on the printed circuit board based on image data read for each pixel. A printed circuit board pattern inspection method for determining the positional relationship of
Based on the read image data, a pattern image showing the wiring pattern and a hole image showing the through hole are obtained.

Next, at least one of the pattern image and the hole image is subjected to an enlargement process to obtain at least one of the corresponding enlarged pattern image and enlarged hole image.

A spatial relationship between any one of the enlarged pattern image and the enlarged hole image, between the enlarged pattern image and the hole image, and between the pattern image and the enlarged hole image, corresponding to this enlargement process. Find the overlapping area between images based on .

Furthermore, a first position indicating the position of the center of gravity of the overlapping region and a second position indicating the center position or the position of the center of gravity of the hole image or enlarged hole image are determined.

Then, the amount of deviation between the first position and the second position is determined, and the amount of deviation is compared with a predetermined reference distance to determine the relative positional relationship.

Moreover, the pattern of the printed circuit board of the second configuration according to the present invention is
The turn inspection method performs a first enlargement process on a hole image to obtain a first enlarged hole image, and performs a second enlargement process on the hole image with a different enlargement rate from the first enlargement process to obtain a second enlarged hole image. Seeking an enlarged hole image.

Then, a ring-shaped image corresponding to the difference between the first enlarged hole image and the second enlarged hole image is obtained, and an overlapping area between the enlarged pattern image and the ring-shaped image is obtained.

[Effect]

In the present invention, the overlapping area is formed by performing an enlargement process on at least one of a pattern image and a hole image to obtain at least one of the corresponding enlarged pattern image and enlarged hole image, and then forming an enlarged pattern image corresponding to the enlargement process. Based on the spatial relationship between any one of the enlarged hole image, the enlarged pattern image and the hole image, and the pattern image and the enlarged hole image,
Therefore, by finding the amount of deviation between the first position of the overlapping region and the second position of either the hole image or the enlarged hole image, and comparing it with a predetermined reference distance,
The relative positional relationship between the wiring pattern and the through hole is grasped.

In the following description, for convenience, the first position will be referred to as barycenter coordinates, and the second position will be referred to as center coordinates.

〔Example〕

A. Overall configuration and general operation FIG. 2 is a block diagram showing the overall configuration of a pattern inspection apparatus to which an embodiment of the present invention is applied.

On the stage 10 is a printed circuit board to be inspected]1
is placed. The printed circuit board 11 is conveyed in the transport direction Y while its image is read by the reading device 20 in each line direction X. The reading device 20 has a plurality of CODs each having several thousand elements arranged in series in the line direction X, and reads the pattern of the printed circuit board 11 pixel by pixel. The read image data is sent to the binarization circuit 21
a, 21. sent to b. The binarization circuit 21a generates a hole image original signal H1so, which will be described later, and the binarization circuit 21b generates a pattern image original signal PIS, which will be described later. Both signals H1s and PIS0 are input to the through-hole inspection circuit 30.

The through-hole inspection circuit 30 has a function described later, inspects the relative positional relationship between the through-hole and the wiring pattern (including lands), and provides the result to the central processing unit (MPU or CPU) 50.

The MPU 50 controls the entire device via a control system 51. The control system 51 generates an XY address and the like for specifying the address of data obtained in the through-hole inspection circuit 30. The XY address is also given to the stage drive system 52 to control the transport mechanism of the stage 10.

The CRT 60 receives instructions from the MPU 50 and displays various calculation results, such as a hole image. The keyboard 70 is used to input various commands to the MPU 50.

The option section 80 includes a defect confirmation device 81. A defective product removing device 82, a defective position marking device 83, and the like are arranged. The defect confirmation device 81 is a device for enlarging and displaying a detected defect on, for example, a CRT. Moreover, the defective product removal device 82 removes the defective printed circuit board 1.
1- is detected, the device transports the printed circuit board 11 to a tray for defective products or the like. The defect position marking device 83 is a device for directly marking a defective portion on the printed circuit board 1 or at a point on the sheet corresponding to the defective portion. These devices are installed as needed.

B. Reading optical system FIG. 3 shows the stage 10. shown in FIG. Printed circuit board 1
1 is a diagram illustrating an example of a reading optical system configured by a reading device 1, a reading device 20, and the like.

In FIG. 3, the light from the light source 22 is transmitted to the half mirror 2.
3 and is irradiated onto the printed circuit board 11 on the stage 10. On the printed circuit board 11, there are a base B serving as a base, a wiring pattern P, a through hole H, and a land R around it. The reflected light from the printed circuit board 11 passes through the half mirror 23, and further enters the CCD 24 provided in the reading device 20 via the lens 25. The CCD 24 is connected to the base B, the wiring pattern P, and the through hole H on the printed circuit board 11 that is sent in the transport direction Y.
, the reflected light from lands R, etc. are read line by line.

Fig. 4A is a graph showing the signal waveform read on the line A-A' in Fig. 3, and Fig. 4B is a graph showing the signal waveform near the line A-A' read by the device in Fig. FIG. 3 is a diagram showing an example of a pattern obtained by

As shown in FIG. 4A, there is relatively little reflected light at the base B, and a signal having a level between the threshold values THI and TH2 (THI<TH2) is generated. Since the land R is formed of metal such as copper, a lot of light is reflected at this portion, and a signal having a level equal to or higher than the threshold value TH2 is generated. Note that a signal of the same level is generated in the wiring pattern P as well. Furthermore, in the through hole H, there is almost no reflected light, and a signal with a level below the threshold value THI is generated. Furthermore, between the through hole H and the land R, there is usually an edge (E mouth edge) E formed during drilling. There are wobbles and inclinations in this part, and the reflected light level in this part does not take a particularly constant value, but is approximately between the threshold value THI and the threshold value TH2.

FIG. 4B shows the A-A′ read as described above.
It is a figure which shows the pattern near a line. The signal from the reading device 20 is binarized in binarization circuits 21a and 21b using, for example, threshold values TH1 and TH2, respectively. The binarization circuit 21a generates a hole image H1 indicating the through hole H, and the binarization circuit 21b generates a pattern image PI indicating the land R and the wiring pattern P. These two images H1 and PI are used as signals necessary for processing to be described later. Base B and edge E are not particularly binarized, but edge E has land R and through hole H.
Therefore, when grasping the relative positional relationship between the land R and the through hole H, processing of the edge E, which is a gap region, is important.

FIG. 5 is a diagram showing another example of the reading optical system.

Similar to the example shown in FIG. 3, the light from the light source 22a is irradiated onto the CCD 24 in the reading device 20 as reflected light via the half mirror 23 and the lens 25. In this example, a light source 22b is further provided on the back side of the stage 10, and the light passing through the through hole H is also transmitted to the CCD 2.
4.

Therefore, in the through hole H, the signal level is the highest, in the land R1 wiring pattern P, the signal level is medium, and in the base B and edge E, the signal level is relatively low.

Furthermore, as another example, two or more rows of CCD24 are prepared,
The light source 22a may detect the land R and the wiring pattern P, the light source 22b may detect only the through hole H, and the data may be separately output to the subsequent binarization circuit.

C. Through-hole inspection circuit FIG. 1A is a block diagram showing the internal configuration of the through-hole inspection circuit 30 shown in FIG.
3 is a flowchart showing a processing procedure of a printed circuit board pattern inspection method performed using the circuit shown in the figure.

The hole image original signal HIS and the pattern image original signal P generated by the binarization circuits 21a and 21b in FIG.
ISo is provided to noise filters 32a and 32b via an interface 31, respectively. The noise filters 32a and 32b perform smoothing processing and the like to remove noise and generate a hole image signal HIS and a pattern image signal PIS, respectively. This process and the above 2
The value conversion process corresponds to step Sll in FIG. 1B.

The hole image signal HIS is provided to the hole image enlargement block 33. Hole image enlargement block 3
3, as shown in FIG.
A second enlarged hole image H1 obtained by enlarging the original hole image HI by 0 steps and a second enlarged hole mouth image HI obtained by enlarging it by n−i steps are generated based on S. In addition, if n>i, tomorrow,
Both are positive integers. This enlarging process is performed, for example, by a spatial filter that uses one pixel in each of the upper, lower, right, left, and diagonal directions of the original enlarged portion as a new enlarged portion each time the image is enlarged by one step. As enlargement is repeated, the proportion of the defective portion LP of the original image H1 in the overall image decreases, and the shape of the figure becomes more regular. This process is performed in step S1 in FIG. 1B.
Corresponds to 2.

Furthermore, enlarged hole images H1 and Hl.

Based on the mutual difference between n 11-1 , a ring-shaped image R1 is obtained as shown in FIG. This process is performed by inputting signals indicating the first and second enlarged hole images H1 and H1 to the inputs of the exclusive OR circuit in the hole image enlargement block 33. As described above, the ring image signal RIS representing the ring-shaped image R1 is generated. FIG. 7 is a diagram schematically showing the shape of the ring-shaped image R1 and the binarized signal levels (L, H). In addition,
The number of stages n and the subtraction number i can be set by software. This process also corresponds to step 813 in FIG. 1B.

On the other hand, the pattern image signal PIS is applied to the pattern enlargement block 34. In the pattern enlargement block 34, as shown in FIG.
An enlarged pattern image P■ is generated by enlarging the original pattern image PI based on m steps. In this enlargement process as well, (1) Missing portions and wobbles in the pattern image PI are corrected. Note that the number of stages m is a positive integer that can be set using software. Further, this process corresponds to step S14 in FIG. 1B.

Furthermore, the ring image signal RIS inputted from the hole image enlarging block 33 and the signal indicating the enlarged pattern image PI are manually inputted to the AND circuit in the pattern image enlarging block 34 to generate a ring-shaped image R.
An overlapping area (2) corresponding to an overlapping area between 1 and the enlarged pattern image PI generates an image signal WIS.

FIG. 9 is a diagram schematically showing this overlapping region WR corresponding to a normal through hole. Ring-shaped image R1
The entire area is included in the enlarged pattern image PI, and the overlapping region WR and ring-shaped image R1 match. As shown in FIG. 4B mentioned above, the through hole H
and the land R, there existed an area E that was not binarized, but the enlarging process of the hole image H1 caused the edge E to move from the inside, and the enlarging process of the pattern image PI moved the edge E from the outside. Each degenerates from If the mutual sum of the number of enlarged steps n-i and m is set to a predetermined number of steps or more corresponding to the maximum width of the edge E, the edge E will not be recognized in the enlarged image as shown in FIG. 9, but will instead be an overlapping area. A WR is generated. Note that this process corresponds to step 815 in FIG. 1B.

The first enlarged hole image H1° generated by the hole enlargement block 33 is input to the line delay 38. The line delay 38 has one line with the number of pixels corresponding to the number of elements of the CCD, and stores data for 48 lines in the upper half of the work area WA as shown in FIG. 10, for example. This data is sequentially updated each time one line is read. Further, the center line is used as an address indicating the area being processed as the virtual center AC. Line delay 38 generates Hall identification signal H8 containing these data.

The center determination block 35 reads the hole identification signal H5 and the ring image signal RIS generated by the hole enlargement block 33, and determines whether the virtual center AC meets the requirements for becoming the center of the actual enlarged hole image H1. I do. Then, the result is sent to the ring recognition signal RA.
It is given to the center of gravity calculation block 36 as S. Note that this center determination will be described in detail later.

In addition, the center determination block 35 reads the ring image signal RIS, finds two points of intersection between the virtual center AC and the ring-shaped image R1, and further finds the midpoint of the two intersections, thereby generating a ring-shaped image. Calculate the center coordinates (X, Yl 1) of R1. These center coordinates (X, Yl) are given to the center of gravity shift determination block 37.

Further, the overlapping area image signal WIS generated by the pattern enlargement block 34 is input to the center of gravity calculation block 36. The center of gravity calculation block 36 calculates the coordinates (X, Y) of the center of gravity of the overlapping region WR based on the signal WIS, and provides it to the center of gravity shift determination block 37 in synchronization with the ring recognition signal RAS. The center of gravity coordinates (X, Y, . . . ) are given by the following equations (la) and (lb) using the total number of pixels N in the overlapping region WR and the coordinates X1°Y of each pixel.

X - ΣX1/N ... (1a) Y - ΣY,
/N (1b) Note that the origin for each of the above coordinate values can be set arbitrarily. Furthermore, the above series of processes corresponds to step S16 in FIG. 1B.

The barycenter shift determination block 37 manually determines the center coordinates (X, Yl) of the ring-shaped image RI and the barycenter coordinates (X, Y) of the overlapping region W R, and calculates the relative center coordinates of the hole image H1 and the pattern image PI. The positional relationship is determined as follows.

First, the magnitude relationship between the center coordinates (X, Y), the center of gravity coordinates (X2°, and a predetermined judgment reference distance) is determined. For example, whether the positional relationship is good (OK) or bad (NG) can be determined using the following formula (2a
), (2b).

D>d OK=.(2a) D≦d NG...(2b) FIG. 11 is a diagram showing an example of the overlapping region WR when there is a positional shift. If the positional shift is large, a portion of the enlarged pattern image PI will be interrupted, and furthermore, a portion of the ring-shaped image RI will protrude outside the enlarged pattern PI. Therefore, the deviation amount d becomes larger than the predetermined determination reference pressure #D, and the positional relationship is determined to be poor (NG).

The center of gravity shift determination block 37 performs such a good/bad (O
K/NG) signal is output as a center of gravity shift determination signal AS. Note that the above series of processing is performed in step S1 in FIG. 1B.
7.

In addition, in the actual circuit configuration, in order to perform real-time processing, the center is determined based on the virtual center AC, and the center of gravity shift determination as described above is also performed. The center coordinates (X, Y) of

(1) Moreover, by being given a plurality of different center coordinates (X, Yl), a plurality of center-of-gravity shift determination signals AS indicating different results may be given. These data are subjected to labeling processing, which will be described in detail later, in the center of gravity shift determination block 37, and a center of gravity shift determination signal AS for that hole is specified.

This determination signal AS is input to the comprehensive defect determination block 39. There, a comprehensive determination of the type and degree of the defect is made in consideration of the defect signal ES from another inspection circuit (not shown) that inspects other inspections, such as inspecting clogging of through holes.

The processing result is given to the interface 31 via the defect store block 40, and further read out to the outside by a pass line (not shown).

Through the series of processes described above, the relative positional relationship between the through hole and the pattern is determined.

D. Center Determination and Labeling Process Next, a process for specifying the address of the calculation result of center-of-gravity shift determination will be described. First, center determination processing for determining whether the virtual center is the actual center position will be explained. This process is carried out by the center determination block 3 shown in FIG. 1A.
It will be held at 5.

Figure 12A shows the enlarged hole image H1 and the virtual center AC.
and a diagram showing the positional relationship with the true center position RC,
FIG. 12B is a diagram showing the calculation principle of center determination.

As shown in FIG. 12A, the virtual center AC and the center position RC
are not generally agreed upon. As shown in FIG. 12B, a line HL perpendicular to the virtual center AC is provided at the intersection of the virtual center AC and the enlarged hole image H1, and an area S above the virtual center AC and an area S below the virtual center AC are defined. By calculating the difference area sa, the deviation between the virtual center AC and the center position RC is given. This difference area S 2 is given, for example, by counting the number of pixels included therein.

In addition, as shown in Fig. 13, the size of the minimum difference area when there is a deviation of one pixel or less between the virtual center AC and the center position RC is defined as the area C, which is the basis for the following judgment. do. If the criterion for center determination is C>S3, the center is determined only when the virtual center AC and the center position RC closely match, but if there is wobble in the shape of the image HI, the virtual center AC Even when the center position RC coincides with the center position RC, the difference area S 2 will not become very small, and there is a possibility that it will be determined that there is no center. Therefore, it is better to set the standard for center determination to about 20≧S to ensure that one of the virtual centers AC is determined to be the center.

Next, labeling processing will be explained. This process is performed in the center of gravity shift determination block 37 shown in FIG. 1A. When the center determination process described above is performed, for example, as shown in FIG. 14, a plurality of virtual centers AC-AC3 are n
It may be determined that the center is 1. When determining the center of gravity shift for each of the virtual centers A Ci to A Ca, the center coordinates (X, Y
) are different, the center of gravity shift determination results may also be different.

For example, a case will be described in which the center of gravity shift determination signal AS is good (OK) at the virtual center AC2 closest to the actual center position, and bad (NG) at the other virtual centers AC and AC3.

First of all, the data that is ultimately required is only the good (OK) signal, and the other bad (NG) signals are the virtual center AC,
This is generated because AC3 is deviated from the true center position RC. It is also necessary to indicate in the data, together with the OK/NG signal, that the three virtual centers AC-AC3 are lines related to the same hole image HI.

First, when the virtual center A Ct is determined to be the center, its starting point Xsl and ending point X are determined. 1 and the center point X by simply averaging the coordinates. Find ■. This process is performed using the center coordinates (x,
This process is similar to the process for determining y).

Next, moving to the virtual center AC2, the center point xc2 is found from the starting point xs2' and the ending point X. X of this center point
The coordinates are between the X coordinates of point x
If sl' el, the same image H1
It is determined that the virtual center AC is related to the virtual center AC. And the center point X. Data indicating the coordinates of 2 is the center point X. Replace with data indicating the coordinates of 1. Furthermore, virtual center AC3
Starting point X Ending point X. 3 and the center point X found from
s3'
The same process is performed for c3, and the center point X is obtained. Replace with the coordinate data of ■. In this way, the coordinates of the virtual center AC-AC3 regarding the image H■ are the center point X. Represented by ■. Also,
Judgment results for those virtual centers AC-AC3 (O
K/NG), the subsequent circuit is configured so that if even one of them is good (OK), a good (OK) signal is output for the image H1 as a whole. FIG. 15 shows the flow of the above processing.

E. Modified Example In the example described above, both the hole image H■ and the pattern image PI are enlarged, but if at least one of the hole image H1 and the pattern image PI is enlarged, an overlapping region WR is formed. , and similar center-of-gravity shift determination processing can be performed.

Moreover, it is sufficient to select "1" as the subtraction number i for forming the ring-shaped image R1, but a number greater than or equal to "2" may be selected.

In addition, the work area WA for pixels in the upper and lower 48 lines.
The number of lines is arbitrary.

Furthermore, by changing the setting of the reference area C for center determination to a predetermined coefficient, even one defect (NG) can be detected in the labeling process.
If there is a signal, the entire device may be determined to be defective (NG).

Furthermore, if there is a mounting hole other than a through hole in the printed circuit board, this mounting hole can be excluded from inspection and not inspected, or even if inspected, it can be determined not to be defective (NG). To do this, data such as the position, shape, and size of the mounting hole may be input in advance.

〔Effect of the invention〕

As described above, according to the present invention, at least one of the pattern image and the hole image is enlarged to find the overlapping area of the two images. By determining the amount of deviation between the center of gravity of the overlapping area and the center or center of gravity of the hole image or enlarged hole image, and comparing it with a predetermined reference distance, the wiring pattern and The relative positional relationship with the through hole is grasped.

Therefore, it is possible to obtain a method for inspecting patterns of printed circuit boards that enables automation of inspection of patterns of printed circuit boards and allows for accurate center-of-gravity shift determination.

[Brief explanation of the drawing]

FIG. 1A is a block diagram of a through-hole inspection circuit according to an embodiment of the present invention, FIG. 1B is a flowchart showing the processing procedure of a printed circuit board pattern inspection method according to an embodiment of the present invention, and FIG. 2 is a block diagram of a through-hole inspection circuit according to an embodiment of the present invention. A block diagram showing the overall configuration of an inspection device according to an embodiment; FIG. 3 is a diagram showing an example of a reading optical system; FIG. 4A is a diagram showing a signal waveform obtained by the device shown in FIG. 3; FIG. 4B is a diagram showing a pattern obtained by combining the signal waveforms shown in Figure 4A, Figure 5 is a diagram showing another example of the reading optical system, Figure 6 is a diagram showing an enlarged hole image, and Figure 7 is a diagram showing a ring. 8 is a diagram showing an enlarged pattern image, FIG. 9 is a diagram showing an example of an overlapping area, FIG. 10 is a diagram showing a work area, and FIG. 11 is a diagram showing another example of an overlapping area. 12A is a diagram showing the positional relationship between the virtual center, the center position, and an enlarged hole image; FIG. 12B is a diagram showing the principle of center determination processing; FIG. 13 is a diagram showing an example of the difference area; The figure shows the principle of labeling processing, Fig. 15 shows an example of the flow of labeling processing, Fig. 16A shows a good relative positional relationship between lands and through holes, and Fig. 16B shows the land and through holes. Figure 1.7A is a diagram showing a good relative positional relationship between a wiring pattern and a through hole. Figure 17B is a diagram showing a defective relationship between a wiring pattern and a through hole. FIG. 2 is a diagram showing relative positional relationships. H...Hole, R...Land, P...
Wiring pattern, Hl...Hole image, PI...
...Pattern image, Hl ...First enlarged hole image, HI'r
l-i...Second enlarged hole image, PI...
・Enlarged pattern image, R1... Ring-shaped image, WR... Overlapping area, (X, Yl)... Center coordinates (second position), ■ (X, Y2)... Center of gravity coordinates (first position) position), d...displacement amount, D...judgment reference distance, AS...center of gravity shift judgment signal,

Claims (2)

[Claims] (1) A printed circuit board pattern inspection method in which the printed circuit board is photoelectrically scanned and the relative positional relationship between the wiring pattern and the through hole on the printed circuit board is determined based on image data read for each pixel. (a) obtaining a pattern image representing the wiring pattern and a hole image representing the through hole based on the image data; and (b) at least one of the pattern image and the hole image. performing an enlargement process to obtain at least one of a corresponding enlarged pattern image and an enlarged hole image;
(c) Any one between the enlarged pattern image and the enlarged hole image, between the enlarged pattern image and the hole image, or between the pattern image and the enlarged hole image, corresponding to the enlargement process. (d) determining a first position indicating the position of the center of gravity of the overlapping area; (e) determining the hole image or (f) determining a deviation amount between the first position and the second position; (g) determining the deviation amount; A pattern inspection method for a printed circuit board, comprising the step of determining the relative positional relationship by comparing it with a predetermined reference distance. (2) The printed circuit board pattern inspection method according to claim 1, wherein step (b) comprises (b-1) performing a first enlargement process on the hole image;
(b-2) obtaining a first enlarged hole image;
(b-3) performing a second enlargement process on the hole image with a different enlargement rate from the first enlargement process to obtain a second enlarged hole image; obtaining a ring-shaped image corresponding to the difference from the second enlarged hole image, and step (c) includes: (c-1) an overlapping area between the enlarged pattern image and the ring-shaped image; A printed circuit board pattern inspection method that includes the process of determining.