JPH036409A - Method and apparatus for inspecting printed circuit board - Google Patents

Abstract

PURPOSE:To enable accurate position alignment of the contour line of a board in a short time by determining an approximate contour line on the basis of positions of three or more sample points on the contour line. CONSTITUTION:A light from a light source 10 is applied to a printed circuit board 21 on a conveyance stage 20 and it is transmitted or reflected corresponding to the contour line of the board 21, position of holes thereof, etc. This conveyance stage 20 conveys the board 21 in a sub-scanning direction Y. The light from the board 21 is given to an image sensor 30 disposed in a main- scanning direction X and the contour line of the board 21, the positions of the holes thereof, etc. are read therein. Signals representing informations on the contour line and holes of the board 21 read in the sensor 30 are given to a processing element 40, subjected therein to a binary-coding processing and a noise-removing processing and then given to a printed circuit board inspecting circuit 50. Moreover, the results of processings by the circuit 50 are given to a display element 60 and displayed on or outputted to CRT 61 or a printer 62.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for inspecting printed circuit boards, and in particular to a method and apparatus for inspecting the number and positional deviation of through holes by photoelectric scanning. It is.

[Conventional technology]

For information on methods and devices for inspecting through holes and patterns by photoelectrically scanning printed circuit boards, see, for example, "Circuit Technology Vol. 1.3 No. 6 (1988)" P.
2. Description of the Related Art There are known methods and apparatuses for inspecting a printed circuit board by reading an image of a printed circuit board being transported using a contact type image sensor, as disclosed in Japanese Patent No. 354-P, 358.

One of the methods proposed in the above-mentioned literature and other literature is to memorize the standard data (master data) of the standard board in advance, and check the outline shape, through holes, etc. of the board to be inspected to be transported. There is a comparison method that determines the quality of a board to be inspected by comparing and collating data regarding surface shape with master data.

This type of comparison method can obtain a lot of information and make accurate pass/fail judgments by comparing the master data and the data of the test board, but it is difficult to read the test board. If becomes inaccurate, the result of the determination will also be inaccurate.

As printed circuit board patterns become denser and through holes become smaller (mini-via holes), there is a growing need for technology to reduce reading errors when carrying out comparison methods. Conveying devices using guides for positioning have also been proposed.

[Problem to be solved by the invention]

However, devices using mechanical positioning means such as guides have problems in that highly accurate positioning is difficult due to the low precision of the guides themselves and the wobbling of the substrates themselves.

Also, based on the read printed circuit board data,
A method has been proposed in which extraction, such as coordinate transformation, is performed electronically and compared with master data, but this method has problems in that the processing takes too much time and the processing results are inaccurate.

Furthermore, although the above-described method can align the outline of the substrate, there is a problem in that it cannot deal with errors caused by misalignment of patterns on the substrate.

[Purpose of the invention]

This invention has been made in consideration of the above circumstances, and its first object is to provide a printed circuit board inspection method and apparatus that can accurately align the outline of the circuit board in a short time.
The purpose of

A second object of the present invention is to provide a method and apparatus for inspecting a printed circuit board that eliminates errors caused by pattern displacement on the circuit board.

[Means to solve the problem]

The first method of inspecting a printed circuit board according to the present invention is to inspect a printed circuit board having a plurality of holes at positions based on a standard pattern on a substrate having a shape based on a standard shape constituted by a plurality of sides. In this method of inspecting a board, first, master data indicating coordinate information of a standard shape and a standard pattern is prepared.

Next, the printed circuit board is photoelectrically scanned to read the shape of the printed circuit board and the positions of the plurality of holes.

Next, the positions of three or more sample points on the outline of the printed circuit board shape are recognized, and based on the positions of these sample points, an approximate outline is obtained by linearly approximating the outline.

Furthermore, in a predetermined coordinate system, the relative positional relationship between the standard shape and the printed circuit board shape is determined based on the coordinate information of the approximate outline and the coordinate information of the corresponding sides, and the relative positional relationship is determined. Based on the coordinates of the read holes, the corresponding corrected positions are determined.

Then, by comparing the hole at the correction position and the hole on the standard pattern while using the coordinate information of the standard pattern,
This method recognizes the number and position of a plurality of holes in a printed circuit board.

The method for inspecting a printed circuit board having the second configuration according to the present invention includes determining the relative positional relationship between the standard shape and the shape of the printed circuit board by the method for inspecting the printed circuit board having the first configuration; After performing coordinate transformation on the positions of the plurality of read holes based on the above, first and second reference positions indicating the upper two predetermined holes on the standard pattern are specified.

Next, first and second actually measured positions indicating two predetermined holes are determined from among the positions of the plurality of holes that have been read.

Next, in a predetermined coordinate system, a relative positional relationship between the first and second actually measured positions and the first and second reference positions is determined.

Then, based on the relative positional relationship, the positions of the multiple holes are converted into coordinates, the corresponding correction position is obtained, and the hole at the correction position is compared with the hole in the standard pattern "2."
This method recognizes the number and position of a plurality of holes in a printed circuit board.

Furthermore, the printed circuit board inspection apparatus according to the present invention is configured to execute the printed circuit board inspection methods of the first and second configurations.

[Effect]

Since the approximate contour line in this invention is determined by the positions of three or more sample points on the contour line, the influence of unevenness of the contour line is removed.

Moreover, the first and second actually measured positions in this invention are
The measured position is compared with the first and second reference positions, and the deviation between the measured position and the reference position is determined, so that the deviation between the standard pattern and the pattern given by the measured data is detected.

〔Example〕

A. Overall structure and general operation FIG. 2 is a block diagram of a printed circuit board inspection apparatus to which an embodiment of the present invention is applied. Moreover, FIG. 3 is an external view of the printed circuit board inspection apparatus.

In FIG. 2, light from a light source 10 constituted by, for example, an LED array is irradiated onto a printed circuit board 21 on a transfer table 20, including the outline of the printed circuit board 21, through holes, mounting holes, etc. One is transmitted and one is reflected depending on the position of the hole. The conveyor table 20 conveys the printed circuit board 2 in parallel to the sub-scanning direction Y. Also, the light from the printed circuit board 21 is transmitted in the main scanning direction
For example, the outline of the printed circuit board 2, the position of the holes, etc. are given to the contact type image sensor 30 disposed in the
It is read there. The printed circuit board 2] moves on an X-Y coordinate system defined on the inspection device.

Signals indicating information on the outline and holes of the printed circuit board 21 read by the image sensor 30 are given to the processing unit 40, and after being subjected to binarization processing and noise removal processing, the printed circuit board inspection is performed to perform the processing described below. is applied to circuit 50. The results processed by the printed circuit board inspection circuit 50 are given to the display section 60 and displayed on the CRT 61 or printer 62.
Output.

Furthermore, the processing section 40 controls the operation of the conveyance table 20 by giving a control command to the driving section 70 .

The drive unit 70 is composed of a pulse motor, a motor controller, etc. (not shown). Furthermore, instructions to start or stop the operation of the above-described configuration are performed using an operation unit 80 that includes a panel, a keyboard, and the like.

In addition to the configuration shown in FIG. 2, FIG. 3 also shows a good product stocker 91 and a defective product stocker 92, which can be attached as options. Printed circuit boards determined to be non-defective after various inspections such as through-hole inspection are transported to a non-defective product stocker 91, and printed circuit boards determined to be defective are transported to a defective product stocker 92.

B. Data Format Next, the data format used in the printed circuit board inspection method of the present invention will be explained. FIG. 4 is a diagram showing through holes on the printed circuit board. Data reading and its format will be explained with reference to FIG.

As described above, the printed circuit board 21 is transported parallel to the sub-scanning direction Y. The image sensor 30 shown in FIGS. 2 and 3 has a configuration in which a plurality of 3 4 CCDs are arranged in the main scanning direction read. This analog value is binarized by an A/D converter (not shown) in the processing section 40 shown in FIG. 2, and becomes information indicating bright areas and dark areas.

In FIG. 4, the scanning line S away from the printed circuit board 21
In LO, data in which information indicating bright areas is continuous for all pixels is generated. This data is formatted into a run length format, and one code is generated by a combination of image data indicating a bright area and the length of the bright area.

Note that this period is an idle time in which the printed circuit board 21 is not scanned, and no particular processing related to inspection, which will be described later, is performed.

When the reading of the printed circuit board 2 begins in the scanning line SLI, three codes in run-length format are read, corresponding to two bright areas on both sides of the printed circuit board 21 and one dark area on the printed circuit board 21. generated. The coordinate information of the end of the printed circuit board 21 is given using the address of the first scanning line SLI that generates these three codes. Further, coordinate information indicating this end portion is stored in a memory area having a predetermined address, and is used in processing to be described later.

In the scanning line SL2, the bright part in the hole H1 is recognized, and five codes are generated. A label LA=1 is given to hole H1 to distinguish it from other holes.

The X coordinate X8□ of the starting point and the X coordinate XE1 of the ending point of the hole H1 are provisionally registered as a starting pixel address LE and an ending pixel address TE, respectively. Furthermore, the diameter DIA=TE-LE in the X-axis direction is calculated and provisionally registered.

In the scanning line SL3, the bright portion in the hole H2 is also recognized, and processing regarding the hole H2 also begins.

Furthermore, the X coordinates x x of the start and end points of hole H1 on scanning line SLB and scanning line 5L82''
X coordinates XSl of the start and end points of hole H1 on E2 2
' The magnitude relationship between xEl is 5 x > x, x < x, and E2 E
l 32 5L (XE2 XEL) X (XS2 X5t) <
A relationship of 0 holds true. Since the above relationship is established between the coordinates of the start point and the end point, it is recognized that these points belong to the same hole H1.

Also, the diameter DIA is calculated for each scanning line and updated to take a larger value. At the scanning line SL3, the diameter DIA of the hole H1 takes the maximum value, and the diameter of the hole H1 in the X-axis direction is determined. Furthermore, the pixel address LE and pixel address TE at this time are registered as the starting point and ending point regarding the hole H1.

In the scanning line SL5, the hole H1 is no longer recognized. Therefore, the previous scanning line SL4 is the hole H.
This is the final scan line for 1.

Main scanning is continuously performed on the hole H1 from the first scanning line SLI to the scanning line SL4. The number of consecutive main scans LC corresponds to the diameter of the hole H in the Y-axis direction.

In addition, when scanning for hole H1 is completed, the X coordinate XC and Y coordinate YC of the center are also determined from the coordinate information of the starting point and ending point on the scanning line SL that gives the maximum diameter DIA, for example, and the final Data regarding the hole H1 is configured as shown in Table 1 below.

Table 1 Similar data is also generated for other holes such as hole H2. Furthermore, in the scanning line SL6 immediately before the scanning line SL7 where the idle time starts again, the scanning line S
As with LI, the edge of the printed circuit board 21 is recognized, and all data regarding the outline can be obtained.

C1 Outline Line Approximation Process 7 8 Next, the outline line approximation process performed by software in the printed circuit board inspection circuit 50 shown in FIG. 2 will be described. 1st A
The figure is a flowchart 1 showing the processing procedure of outline approximation processing according to an embodiment of the present invention. Further, FIG. 5 is a diagram showing how a printed circuit board that is transported in an inclined state is scanned. In the example shown in FIG. 4, the scanning line and the outline of the printed circuit board were parallel to each other, but generally the printed circuit board is conveyed with an inclination as shown in FIG.

In step 31.1 of FIG. 1A, once the scanning of the printed circuit board to be processed has been completed, its central region is established. In the example shown in FIG. 5, scanning starts when the apex of the printed circuit board 21 crosses under the scanning line SL located at the position of the image sensor 30, and ends when the apex B crosses the line. Printed circuit board 21 from apex to apex B
The length in the Y-axis direction is divided into four, and the two central areas having a length of L/4 are combined to form the central area MA.

If the angle of inclination θ is not extremely large, the central region MA includes the central portions of the upper side AB and the lower side CD.

In step S12, a predetermined number of sample points are set on each of the upper and lower sides included in the central region.

FIG. 6 is an enlarged view of the central portion of side AB shown in FIG. The outline line OL generally has unevenness,
The outline line OL shown in FIG. 6 also forms four parts. Three or more sample points P are placed at equal intervals in the Y-axis direction on the outline line OL.
1 to P9 are set. Note that the coordinates of the sample points P1 to P9 are given, for example, by data formatted in run length format in the X direction.

In step 813, the sample points on the upper and lower sides set in step S12 are approximated by straight lines to obtain a first-order approximate outline. In FIG. 6, sample points P1 to P9
is approximated by the least squares method to obtain the first-order approximate outline OL
I is required. Sample points P1 to P3. P7 to P9 exist almost on the true outline line OLO, but sample point P4
~P6 is located on the fourth part and is shifted toward the inner side of the printed circuit board 21. Therefore, the approximate outline OLI is set to be shifted inward from the true outline OLO.

In step S14, the first-order approximate outline set in step 813 is extended over the entire range of the upper and lower sides. FIG. 7 is a diagram showing an extension of the approximate outline shown in FIG. 6.

In step S15, sample points are set over the entire range of each side, and the sample points are classified into two groups based on the arrangement relationship with the first-order approximate outline. In the example shown in FIG. 7, sample point P4. P26 etc. are classified into group G2 inside the printed circuit board 21 when viewed from the approximate outline OLI,
The other sample points are classified into a group G1 outside the printed circuit board 21 when viewed from the approximate outline line OL1.

In step S16, a second-order approximate straight line is determined using sample points belonging to a group containing a larger number of sample points from among the groups classified by the first-order approximate contour line. In the example shown in FIG. 7, sample point P4.
True outline OL included in group G2, such as P26
Sample points relatively far from O are excluded. and,
Since the quadratic approximate straight line OL2 is obtained using sample points relatively close to the true outline OLO included in group G1, the approximate outline OL2 is closer to the true outline OLO.
is obtained.

In step S17, step S15 and step S
It is determined whether the process corresponding to step 16 has been performed a predetermined number of times (n times). By repeating the process of steps 15 and 16, sample points in the four small parts such as sample point P14 in FIG. 7 are also eliminated, and the approximate outline converges toward the true outline OLO, resulting in In other words, an n-th approximate outline line OLn (not shown) which is very close to the true outline line OLO is obtained.

In step 318, the n-th approximated outline OLn obtained as described above is used as the final approximated outline for subsequent processing.

Although we have explained an example of excluding the sample points on the four parts, sample points on the convex parts are also excluded in the same way, and even if both the four parts and the convex parts are included, the approximate outline line will not converge to the true outline line. As a result, a sufficiently close approximate outline can be obtained.

After the directions of the upper side AB and lower side CD in FIG. 5 are determined as described above, the directions of the right side DA and left side BC are determined next. FIG. 1B is a flowchart 1 showing the processing procedure for determining the position of the right side, which is performed after the processing shown in FIG. 1A. Further, FIG. 8 is a diagram showing how the position of the right side is determined.

First, in step S21 in FIG. 1B, a reference point is set near the end (=1) of the upper side given by the approximate outline line OLn near n, and a temporary right side is set perpendicular to the upper side from there.

In FIG. 8, a reference point K is set on the upper side AB, and a temporary right side is set from there. In FIG. 8, it is assumed that the nth-order approximate outline OLn and the true outline OLO are sufficiently close, and that vertices A and B exist on the approximate outline OLn.

In step S22, sample points are set on the right side, and distances between each of the sample points and the temporary right side are determined. In FIG. 8, sample points Q1 to Q5 are set at equal intervals in the X direction on the right side DA, and the distances d1 to d5 from the sample points Q1 to Q5 to the temporary right side are
seek. Note that the number of sample points is an arbitrary number.

In step 23, a sample point that gives the maximum distance to the tentative right side is determined from among the sample points and is set as a reference sample point. In FIG. 8, since the distance d2 is the maximum, the sample point Q2 becomes the reference sample point.

In step S24, a straight line passing through the reference sample point and perpendicular to the upper side is determined, and the point of intersection with the upper side is determined as a new vertex. In FIG. 8, a straight line L1 passing through the reference sample point Q2 and perpendicular to the straight line AB is determined.

Further, the intersection point A' between the straight line L1 and the straight line AB is recognized as a new vertex A' instead of the vertex A.

In step S25, the upper side and right side are reset using the newly found vertices as the end points of each straight line.

One end point and directionality of the upper and lower sides are determined.

In FIG. 8, the vertex A' becomes the end point of the straight lines Ll and AB, and the directions of the upper side A'B and the right side A'Q2 are determined.

The above-described processing is also performed on the lower and left sides to determine the lower left vertex C' as shown in FIG.

Also, let the intersection of the right side and the lower side be the vertex D/, and the intersection of the left side and the upper side be the vertex B'. Since the right and left sides were determined using the sample point with the maximum distance from the tentative right and left sides as the reference sample point, in most cases the newly found vertices A' to D' are smaller than the original vertices A to D. located on the outside. In this way, it is possible to eliminate the effects of missing parts such as roundness at each vertex of the printed circuit board and concave portions on each side, and to accurately restore the standard shape of the printed circuit board. Therefore, for example, it is possible to accurately mask a region within a predetermined distance dO from the outline of the printed circuit board as shown in FIG. 9 to prevent processing such as inspection from being performed.

Further, since the upper side A'B' and the lower side C'D' are strictly approximated by the least squares method, they are almost parallel, and the quadrilateral A'B'C''D' is almost rectangular.

Therefore, the tilt angle θ can also be accurately determined. Note that the upper side A
When the inclinations of 'B' and the lower side C' and D' are different, the angle θ may be obtained by averaging the two inclination angles. Note that the angle θ obtained as described above is used in the comparison and determination process described later.

D. Comparison and Judgment Process Next, a comparison and judgment process will be described in which the master data and the measured data are compared to determine whether the printed circuit board is good or bad. FIG. 1C is a flowchart showing the procedure of the comparison and determination process, and this process is performed after the outline approximation process shown in FIGS. 1A and 1B is performed. Further, FIG. 10 is a diagram showing the state of the comparison and determination processing. This process is also performed by the printed circuit board inspection circuit 50.

In step S31 in FIG. 1C, the vertices are aligned between the outline of the mask data and the approximate outline of the actual measurement data described above. Here, the master data indicates the designed outline of the printed circuit board, the positions of through holes, and mounting holes, and provides the standard shape and standard pattern of the printed circuit board. Further, the master data is stored in a predetermined memory area (not shown) in the printed circuit board inspection circuit 50. In Figure 10, the master data vertices AO-D
The approximate contour line ABCD is translated in parallel so that the upper right vertex AO in O coincides with the upper right vertex A' of the approximate contour line of the actual measurement data.

In step S32, rotational movement is performed around the matched vertex in a direction to correct the tilt angle.

In FIG. 10, the approximate outline line A'BC'D' is rotated by the inclination angle θ around the vertex A' (AO),
Each of the master data vertices AO-Do and the vertex A'
The coordinates of the measured data are transformed so that each of D' to D' closely matches each other.

In step S51, the hole position and shape data of the measured data after coordinate transformation and the hole position of the master data,
The presence or absence of poles, the number of poles, and the quality of the shape are determined by comparing with the shape data.

In FIG. 10, the hole H3 of the measured data corresponding to the hole HO of the master data is coordinate-transformed by rotation and moved near the hole HO.

Furthermore, as shown in FIG. 11, the master data hole H
A square having a predetermined length DX on one side with O as the center is assumed, and if the center of the hole H3 exists within the square, it is determined that a hole corresponding to the hole HO exists. length D
As X becomes smaller, the criteria become stricter, and there is a higher possibility that it will be determined that there is no corresponding hole. Also, length D
As X becomes larger, the criteria for determination become looser, but the possibility of misidentifying an adjacent hole with the hole in question increases.

The setting of this criterion is specified by the operator according to the printed circuit board to be processed. In this way, it is determined whether the number of holes matches the master data and the measured data. Furthermore, these two holes HO, H3
Fruit 71+11 showing hole H3 by comparing the shapes of
It is also determined whether the radius of the data is 1 [ordinary]. Note that each data shown in Table 1 mentioned above is used for this coordinate transformation and comparison determination.

In addition, if the number of holes is smaller in the actual measurement data, the position of the hole that is clogged or has a defective shape is detected.

In step S52, the results of the comparison and determination as described above are displayed as output 1. For example, if the numbers of holes do not match, the position of the defective hole is displayed on the display. The operator can easily detect a defective hole from among a large number of holes by visually inspecting the area on the printed circuit board at that location.

If the process shown in FIG. 1C is performed as described above, when the deviation in the relative positional relationship between the outline of the printed circuit board and the pattern is small, it is possible to accurately compare and determine holes.

In cases where the relative positional relationship between the outline of the printed circuit board and the pattern cannot be ignored, or when you want to more accurately compare and judge high-density printed circuit boards, further reconvert the coordinates as shown below. conduct.

FIG. 1D is a flowchart showing the processing procedure for re-converting coordinates, and FIG. 12 is a diagram showing the state of re-converting coordinates.

First, in FIG. 1D, the process up to step S32 in FIG. 1C is performed, and as shown in FIG.
and vertices AO to Do are made to almost match. Then, in step S41, two holes on the master data are identified, and two corresponding holes on the measured data are found using, for example, the squares shown in FIG. 11 mentioned above. 1st
In FIG. 2, for example, the hole HA closest to the vertex AO and the hole HB furthest from the vertex AO are specified on the master data, and the corresponding holes Ha and Hb on the measured data are determined.

In step S42, the 2
A straight line connecting two holes and a straight line connecting two corresponding holes on the actual measurement data are determined.

In Figure 12, a straight line LA connecting holes HA and HB
A straight line La connecting the holes Ha and Hb is found.

In step S43, the deviation angle is determined based on the slopes of the two straight lines on the master data and the actual measurement data determined in step S42. In Figure 12, Y
The angles θ and θ between the axial direction and the straight line LA La, respectively
2 is obtained, and the deviation angle Δ■ θ (=lθ −θ2 )) is obtained.

(2) In step S44, one hole is selected from the two holes specified in step S41, and the straight line obtained in step S42 is translated in parallel so that the hole overlaps on the master data and the measured data. In Fig. 12, a straight line L is drawn so that the hole Ha overlaps with the hole HA.
A is translated in parallel to form a straight line Lb.

In step S45, rotational movement of the straight line obtained in step S44 is performed in a direction that corrects the deviation angle around the overlapping holes. In Figure 12, the hole HA
The straight line Lb is rotated by a shift angle Δθ around , so that it overlaps with the straight line LA.

Through the above processing, the hole on the straight line La becomes the straight line L
Move to the hole position above A. In addition, this parallel and rotational movement is also performed for other holes on the measured data, so the position of the hole on the master cheetah and the position of the hole on the measured data become even closer. After that, if step S51 in FIG. 1C is performed and similar comparison and determination processing is performed, more accurate comparison and determination processing can be performed.

E. Modified example In the embodiment described above, grouping was performed to obtain approximate outlines by excluding both the four parts and the convex parts, but when there are many four parts such as cuts on the printed circuit board. To do this, sample points on the inside of the printed circuit board as viewed from the first-order approximate outline are sequentially excluded, and sample points outside the first-order approximate outline are used to find the second-order approximate outline. Note that the following processing is similar to the example described above.

In addition, in the embodiment described above, the reconversion of the coordinates shown in FIG. 1D was carried out using two through holes. Coordinates may be retransformed.

〔Effect of the invention〕

As described above, according to the first configuration of the present invention, since the approximate outline is determined by the positions of three or more sample points on the outline, the influence of unevenness of the outline is removed, and the standard shape An approximate contour line that is sufficiently close to the true contour line given by is obtained, and the angle between the contour line and the side of the standard shape in a predetermined coordinate system is accurately calculated.

Therefore, it is possible to obtain a printed circuit board inspection method and apparatus that can accurately align the outline of the circuit board in a short time.

Further, according to the second configuration of the present invention, the first and second
The actual measured position is compared with the first and second reference positions, and the deviation between the actual measured position and the reference position is determined.
A deviation between the standard pattern and the pattern given by the measured data is detected, and coordinate transformation can be performed to overlap the two patterns.

Therefore, it is possible to obtain a method and apparatus for inspecting a printed circuit board that can accurately align the outline of the circuit board in a short time and eliminate errors caused by pattern misalignment.

[Brief explanation of the drawing]

FIG. 1A is a flowchart of outline approximation processing according to an embodiment of the present invention, FIG. 1B is a flowchart of right-side setting processing according to an embodiment of this invention, and FIG. 1C is a flowchart of comparison judgment processing according to an embodiment of this invention. Flowchart, FIG. 1D is a flowchart of coordinate reconversion processing according to an embodiment of the present invention, FIG. 2 is a block diagram of a printed circuit board inspection apparatus to which an embodiment of the present invention is applied, FIG. Figure 4 is a diagram showing the relationship between holes and data, Figure 5 is a diagram showing a tilted printed circuit board, Figure 6 is an enlarged view of the sides, and Figure 7 is an approximation. Figure 8 is a diagram showing the setting of the outline line, Figure 8 is a diagram showing the setting of the right side, Figure 9 is a diagram showing the masking area, Figure 10 is a diagram showing the comparison judgment process, Figure 1-1 The figure shows how the presence or absence of a hole is determined, and FIG. 12 shows how the coordinates are re-converted. 21... Printed circuit board, 30... Image sensor,
50...Printed board inspection circuit, HO-H3, HA, HB, Ha, Hb・
...Hole, θ...Tilt angle, P1 to P9...
・Sample point, OLl...1st order approximate outline line, OL2...2nd order approximate outline line,

Claims (5)

[Claims] (1) A method of inspecting a printed circuit board in which a plurality of holes are provided at positions based on a standard pattern on a board having a shape based on a standard shape constituted by a plurality of sides, the method comprising: (a) the above-mentioned (b) photoelectrically scanning the printed circuit board to read the shape of the printed circuit board and the positions of the plurality of holes; (c) a step of recognizing the positions of three or more sample points on an outline line of the shape of the printed circuit board; (d) a step of determining an approximate outline line by linearly approximating the outline line based on the positions of the sample points; (e) In a given coordinate system,
(f) determining a relative positional relationship between the standard shape and the shape of the printed circuit board based on the coordinate information of the approximate outline and the corresponding coordinate information of the side; and (f) the relative position. (g) converting the coordinates of the read positions of the plurality of holes based on the relationship to obtain the corresponding correction positions; (g) using the coordinate information of the standard pattern, converting the holes at the correction positions and the standard A method for inspecting a printed circuit board, comprising the step of recognizing the number and position of a plurality of holes in the printed circuit board by comparing the holes with holes on a pattern. (2) The method for inspecting a printed circuit board according to claim 1, wherein step (d) comprises: (d-1) determining a first approximation straight line that approximates the positions of three or more sample points by the least squares method; (d-2) forming the plurality of sample points into a first group containing a relatively large number of sample points based on the arrangement relationship between the first approximation straight line and each of the three or more sample points; (d-3) determining a second approximation straight line that approximates the position of the sample points included in the first group; (d-4) A method for inspecting a printed circuit board, including the step of determining an approximate outline line based on the second approximate straight line. (3) A method for inspecting a printed circuit board in which a plurality of holes are provided at positions based on a standard pattern on a board having a shape based on a standard shape constituted by a plurality of sides, the method comprising: (a) (b) photoelectrically scanning the printed circuit board to read the shape of the printed circuit board and the positions of the plurality of holes; (c) a step of recognizing the positions of three or more sample points on an outline line of the shape of the printed circuit board; (d) a step of determining an approximate outline line by linearly approximating the outline line based on the positions of the sample points; (e) In a given coordinate system,
determining a first relative positional relationship between the standard shape and the shape of the printed circuit board based on coordinate information of the approximate outline line and coordinate information of the side corresponding thereto;
f) coordinating the read positions of the plurality of holes based on the first relative positional relationship to obtain a corresponding first corrected position; The first showing two holes
and (h) determining first and second actually measured positions indicating the predetermined two holes from among the positions of the plurality of holes at the first correction position. (i) determining a second relative positional relationship between the first and second actually measured positions and the first and second reference positions; (j) determining the second relative position; Based on the relationship, the first
(k) converting the coordinates of the positions of the plurality of holes at the correction positions to obtain a corresponding second correction position; and (k) converting the coordinates of the holes at the second correction position using the coordinate information of the standard pattern. A method for inspecting a printed circuit board, comprising: recognizing the number and position of a plurality of holes in the printed circuit board by comparing the holes with holes on the standard pattern. (4) An apparatus for inspecting a printed circuit board in which a plurality of holes are provided at positions based on a standard pattern on a board having a shape based on a standard shape constituted by a plurality of sides, comprising: (a) the above-mentioned (b) an image sensor that photoelectrically scans the printed circuit board to read the shape of the printed circuit board and the positions of the plurality of holes; c) sampling means for recognizing the positions of three or more sample points on the outline of the shape of the printed circuit board; (d) determining an approximate outline by linearly approximating the outline based on the positions of the sample points; (e) positional relationship determination for determining the relative positional relationship between the standard shape and the shape of the printed circuit board based on the coordinate information of the approximate outline and the corresponding coordinate information of the side; (f) a correction means for converting coordinates of the read positions of the plurality of holes based on the relative positional relationship to obtain a corresponding correction position; (g) a hole at the correction position and the correction means; A printed circuit board inspection device comprising: recognition means for recognizing the number and position of a plurality of holes in the printed circuit board by comparing the holes with holes on a standard pattern. (5) The printed circuit board inspection apparatus according to claim 4, wherein the means (a) includes: (a') specifying first and second reference positions indicating two predetermined holes on the standard pattern; identifying means is added to the image sensor (b); (b') detection means for determining first and second actually measured positions indicating the predetermined two holes from among the read positions of the plurality of holes; and to the means (e), (e') positional relationship determining means for determining the relative positional relationship between the first and second actually measured positions and the first and second reference positions is added. Printed circuit board inspection equipment.