JP2001165636A - Method and device for detecting pattern defect of printed board wiring pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem for detecting the defect of a minute pattern that was difficult in a printed wiring board wiring pattern defect detecting method using comparative inspection method because the image of a wiring pattern to be inspected is apt to shift from the image of a reference pattern. SOLUTION: A preceding profile vector and a following profile vector are determined from at least three profile points moving along the profile line of a wiring pattern (S16). The defect of the wiring pattern is detected from the angle between the preceding profile vector and the following profile vector (S18). Since the comparison of the wiring pattern to be inspected with the other reference pattern is dispensed with, the defect of a minute pattern can be detected in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a wiring pattern defect of a printed circuit board for detecting a defect of a wiring pattern of the printed circuit board.

[0002]

2. Description of the Related Art A comparative inspection method (pattern matching method) is widely used as a method for detecting a wiring pattern defect such as a defect or a projection of a wiring pattern on a printed circuit board. The comparative inspection method is CCD (Charge-Coupl).
ed Device) This is a method of comparing the image of the wiring pattern to be inspected obtained by an imaging device such as a camera with an image of a known standard pattern to detect a defect in the wiring pattern.

[0003]

In such a comparative inspection method, it is necessary to accurately position an image of a wiring pattern to be inspected with a standard pattern image. However, since a positioning error easily occurs when reading a wiring pattern on a printed circuit board, an image of a wiring pattern to be inspected is shifted from an image of a standard pattern, and it is difficult to detect a defect in a fine pattern.

Further, since the image of the wiring pattern to be inspected is directly compared with the standard pattern image, there is a problem that the inspection time becomes long.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a method and apparatus for detecting a defect in a printed circuit board wiring pattern which can detect a defect in a fine pattern in a short inspection time.

[0006]

A first aspect of the present invention is a method of detecting a defect in a wiring pattern of a printed circuit board, which detects a defect in the wiring pattern of the printed circuit board. And moving at least three contour points along the contour line to form a preceding contour vector connecting the preceding two contour points, and two contour points following the preceding contour point. Determining a connecting contour vector to be connected, and determining that there is a wiring pattern defect when an angle between the preceding contour vector and the following contour vector deviates from a reference value. .

According to the first aspect of the present invention, a leading contour vector and a following contour vector are obtained from at least three contour points moving along the contour of a wiring pattern, and a difference between the leading contour vector and the following contour vector is determined. Detect the defect of the wiring pattern from the angle. Since there is no need to compare the wiring pattern to be detected with other standard patterns, it is possible to detect a fine pattern defect in a short time.

According to a second aspect of the present invention, there is provided the printed circuit board wiring pattern defect detecting method according to the first aspect of the present invention, wherein the step of obtaining the preceding contour vector and the following contour vector comprises moving along the contour line. Three contour points, the preceding contour vector connects the first contour point and the second contour point, and the following contour vector connects the second contour point and the third contour point. Features.

In the second invention, the number of contour points is three, the preceding contour vector connects the first contour point and the second contour point, and the following contour vector is connected to the second contour point and the third contour point. And the number of contour points is minimized, which is suitable for detecting a defect in a wiring pattern.

[0010] A third aspect of the present invention is the printed circuit board wiring pattern defect detecting method according to the first or second aspect of the present invention, wherein the printed board wiring pattern defect detecting method comprises the steps of: Obtaining the position data of the wiring pattern defect from the position data of the contour point when the angle between the vector and the vector deviates from the reference value.

In the third aspect of the present invention, in addition to the determination that there is a wiring pattern defect, position data of the wiring pattern defect can be obtained, which is suitable for specifying the wiring pattern defect position.

According to a fourth aspect of the present invention, there is provided the printed circuit board wiring pattern defect detecting method according to the first or second aspect of the present invention, wherein the step of determining that there is a wiring pattern defect includes the step of determining whether or not the preceding contour vector has the defect. After the angle between the trailing contour vector deviates from the reference value, the contour points are moved until the angle returns to the reference value.After the angle deviates from the reference value, the contour points move until the angle returns to the reference value. Wiring pattern defect information is obtained from the position data of the contour point.

According to the fourth aspect of the present invention, since it is possible to obtain wiring pattern defect information, it is suitable for analyzing the cause of a wiring pattern defect and the like.

According to a fifth aspect of the present invention, there is provided the printed wiring board defect detection method according to the fourth aspect, wherein the wiring pattern defect information includes a position, a width and / or a depth of the wiring pattern defect. It is characterized by the following.

According to a sixth aspect of the present invention, there is provided a printed wiring board defect detecting apparatus for detecting a defective wiring pattern on a printed circuit board, comprising: an imaging device for capturing an image of the wiring pattern; An image processing apparatus for extracting a contour line of the wiring pattern from the image data; a preceding contour vector for moving at least three contour points along the contour line to connect two preceding contour points; A pattern defect that determines a wiring pattern defect when an angle between the preceding contour vector and the following contour vector deviates from a reference value by obtaining a following contour vector connecting two contour points that follow the point. A determination device.

In a sixth aspect of the present invention, a leading contour vector and a following contour vector obtained from at least three contour points moving along the contour of a wiring pattern are used.
The pattern defect determination device determines whether or not the wiring pattern has a defect. Since there is no need to compare the wiring pattern to be detected with other standard patterns, it is possible to detect a fine pattern defect in a short time.

According to a seventh aspect of the present invention, there is provided the printed circuit board wiring pattern defect detecting apparatus according to the sixth present invention, wherein the printed circuit board wiring pattern defect detecting apparatus is configured to determine the leading contour vector and the following contour vector. The position data of the wiring pattern defect is obtained from the position data of the contour point when the angle between them deviates from the reference value, and the position data of the wiring pattern defect is marked on the wiring pattern defect position of the wiring pattern from the obtained position data of the wiring pattern defect. And a marking device for performing the following.

In the seventh aspect of the present invention, since the defect position of the wiring pattern can be marked, the defect position can be easily indicated to, for example, an operator who is detecting the defect.

[0019]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 shows a printed circuit board wiring pattern defect detecting apparatus 100 according to this embodiment. Stand 1
A movable arm 16 provided with a CCD camera 12 and a marker 14 at the tip is provided on the top. The movable arm 16 is mounted on the transport rails 18 and 20 and can move in two orthogonal directions (directions X and Y in FIG. 1). Printed circuit board 22 for which a defect is to be detected
Are placed on the stage 24. This stage 2
4 is a board transfer rail 26 provided on the gantry 10.
The printed board 22 is transported within the movable range of the movable arm 16 by moving the stage 24 in the direction X of FIG. An image processing apparatus for processing the image of the wiring pattern of the printed circuit board 22 obtained by the CCD camera 12 is provided in the gantry 10, and the presence or absence of a wiring pattern defect is determined based on the image of the wiring pattern sent from the image processing apparatus from the image processing apparatus. And an image processing unit 28 including a pattern defect determining device for determining the pattern defect.

Next, a method for detecting a wiring pattern defect on the printed circuit board 22 using the defect detection apparatus 100 will be described.

FIG. 2 is a flowchart showing a method for detecting a wiring pattern defect according to the present embodiment. First, the printed board 22 is transported by the board transport rail 26 into the operation range of the movable arm 16. The data of the wiring of the printed circuit board 22 is given to the movable arm 16 in advance. Based on this data, the movable arm 16 moves and C
The CD camera 12 is moved over the wiring pattern on the printed circuit board 22 (S10). FIG. 3 shows a field of view 30 of the CCD camera 12 with respect to the wiring pattern of the printed circuit board 22 in the process of S10. CCD camera 12
Can accommodate a part of the wiring pattern 32 in the field of view 30. After the defect is detected in a certain field of view, the CCD camera 12 moves to detect a defect in another part of the wiring pattern 32.

Next, the printed circuit board 2 is
An image of the second wiring pattern 32 is taken (S12). The captured image of the wiring pattern 32 is stored in the image processing unit 2.
8, and the contour of the wiring pattern 32 is extracted (S14). FIG. 4A shows a photographed image of the wiring pattern 32.
(B) shows image data obtained from the photographed wiring pattern 32. In FIG. 4B, a plurality of squares indicate each pixel. The image of the wiring pattern 32 shown in FIG.
The image data is black (0) or white (1) shown in FIG. Here, black (0) indicates an area without wiring, and white (1) indicates an area with wiring. In this image data, the boundary between black (0) and white (1) is the position of the contour line. The coordinates of each point corresponding to this boundary are stored in the contour information table.

Next, based on the contour information table, contour points along the contour are determined, and a preceding contour vector and a following contour vector are determined (S16).

FIG. 5 shows contour points, preceding contour vectors, and following contour vectors determined along the contour. The coordinates of three points along the contour are extracted from the contour information table. These three points are moved in the same direction along the contour line. For example, when three contour points are located at the positions of As1, A1, and Ae1, the vectors connecting the contour points at the positions of As1 and A1 are the preceding contour vectors s1, A1.
The vector connecting the contour points at the positions of Ae1 and Ae1 is the following contour vector t1. When three contour points are located at positions As2, A2, and Ae2, a vector connecting the contour points at positions As2 and A2 is a preceding contour vector s2,
The vector connecting the contour points at the positions of A2 and Ae2 is the following contour vector t2.

As described above, the vector connecting the two preceding contour points is the preceding contour vector, and the vector connecting the two contour points that follow the two preceding contour points is the following contour vector.

Next, it is determined whether there is a wiring pattern defect (S18).

When there is a contour point at a position where there is no wiring pattern defect, the angle between the preceding contour vector and the following contour vector becomes a certain value (reference value).

For example, a position where there is no wiring pattern defect and the outline is substantially straight, for example, A in FIG.
When three points s1, A1, and Ae1 are located, the angle θ between the leading contour vector s1 and the following contour vector t1 is:
As shown in FIG. 6A, the angle is about 0 degrees.

When three contour points are located at the corners of the wiring pattern as shown by As2, A2, and Ae2 in FIG. 5, a preceding contour vector s2 connecting As2 and the contour point at the position of A2, The angle θ between A2 and the following contour vector t2 connecting the contour points at the positions of Ae2 is about 90 degrees as shown in FIG. 6B.

As described above, when the angle θ between the preceding vector and the following vector is about 0 ° or 90 °, there is no defect in the wiring pattern, and if each contour point is not at the defective position of the wiring pattern. judge.

However, when three contour points are moved along the contour line and the contour point comes to a position where a wiring pattern defect exists, a preceding contour vector connecting the two preceding contour points and a preceding contour point The angle with the following contour vector connecting the two contour points that follow the contour value deviates from the reference value.

For example, when three contour points are located at the wiring pattern defect position 50, such as As3, A3, and Ae3 in FIG. The angle θ between the following contour vector t3 connecting the contour points at the positions of A3 and Ae3 is about 45 degrees, which is a value deviating from the reference value of 0 or 90 degrees.

When the angle between the preceding contour vector and the following contour vector deviates from the reference value, it is determined that the wiring pattern is defective and the contour point is located at the wiring pattern defect position.

As described above, whether or not the wiring pattern has a defect can be determined based on whether or not the angle between the preceding contour vector and the following contour vector deviates from the reference value.

The processing of S16 and S18 is preferably performed by the pattern defect determination device in the image processing unit 28.

In the process of S18, each contour point is further moved, and from the coordinates of each contour point until the angle θ returns to the reference value, the wiring pattern defect position, defect width, defect depth, etc. Pattern defect information can be obtained.

For example, the terminal point of the pattern defect portion 50,
For example, when three contour points are located at As4, A4, and Ae4 in FIG. 5, the angle θ between the leading contour vector s4 and the following contour vector t4 is about 0 degrees, and the contour point is a pattern defect portion. It is almost the same as the angle before included in 50. In this manner, the coordinates of the contour points in the pattern defect portion 50 can be known, so that information such as the position, width, and depth of the pattern defect can be obtained.

After it is determined in step S18 that the wiring pattern is defective, the movable arm marker 14 shown in FIG.
Then, a mark is made on the defective portion (S20).

Thereafter, it is determined whether or not there is a next inspection pattern (S22).
Returning to the process of 0, if there is no next inspection pattern, the pattern defect detection is terminated.

On the other hand, when there is no defect in the wiring pattern,
Returning to the process of S10, the CCD camera is moved again to detect a defect in another portion of the wiring pattern.

As described above, in the printed board wiring pattern defect detection method according to the present embodiment, since it is not necessary to compare the wiring pattern to be detected with other standard patterns, the defect of the fine pattern can be detected in a short time. Can be detected.

In the process of S16 for determining a contour point along the contour line based on the contour line information table and obtaining the leading contour vector and the following contour vector, the contour point moves four or more along the contour line. May be.

When four outline points are given along the outline, for example, Bs1, Bm1, Bm shown in FIG.
When three contour points are located at the positions of 1, Be1, Bs
A vector connecting the contour points at positions 1 and Bm1 may be defined as a preceding contour vector s1, and a vector connecting the contour points at positions B1 and Be1 may be defined as a following contour vector t1. Further, a vector connecting the contour points at the positions Bs1 and Bm1 may be defined as a preceding contour vector, and a vector connecting the contour points at the positions Bm1 and B1 may be defined as a following contour vector.

It is preferable that the reference value is appropriately set according to the shape of the wiring pattern.

In order to improve the efficiency, it is not always necessary to accurately calculate the angle between the preceding contour vector and the following contour vector.

Next, a method for obtaining the angle between the preceding contour vector and the following contour vector without performing an accurate calculation will be described.

FIG. 8A shows a direction vector indicating the direction of the preceding contour vector or the following contour vector instead of the angle. One direction vector indicates one of the directions obtained by dividing 360 degrees from a certain reference point into 32 equal parts. FIG. 8 (b) shows the direction of the preceding contour vector or the following contour vector from the coordinate changes of the two contour points.
A conversion table represented by the direction vector shown in FIG.

The coordinates of the three contour points are As3 (X1, Y
1), A3 (X2, Y2) and Ae3 (X3, Y3), first, the difference (X2) in the X coordinate between As3 and A3
−X1) and the difference (Y2−Y1) between the Y coordinates are obtained, and the direction vector is obtained from the conversion table of FIG. 8B. Similarly, A
The difference between the X coordinate (X3-X2) and the difference between the Y coordinates (Y3-Y2) between A3 and Ae3 is determined, and the direction vector is shown in FIG.
It is determined from the conversion table of (b). Then, the difference between the respective direction vectors is defined as the angle between the preceding contour vector and the following contour vector.

According to FIG. 8A, when there is no defect in the wiring pattern and the angle between the preceding contour vector and the following contour vector is 0 degree, the difference between the direction vectors is 0. Further, when there is no defect in the wiring pattern, the contour point is at a corner of the wiring pattern, and the angle between the preceding contour vector and the following contour vector is 90 degrees, the difference between the direction vectors is 8.

For example, if the coordinates of three contour points are As3
When (1, -1), A3 (1, 0), and Ae3 (0, 0), the difference between the X coordinates between As3 and A3 is 0, and the difference between the Y coordinates is 1. This direction is the direction 24 from FIG.
Becomes Also, the difference in the X coordinate between A3 and Ae3 is-
The difference between the Y and Y coordinates is 1, and this direction is the direction 20 from FIG. 8B. Therefore, the difference between the direction vectors is 4
Thus, it can be determined that the wiring pattern has a defect.

As described above, it is possible to determine that there is a pattern defect without necessarily performing an accurate angle calculation.

In the present embodiment, when there are a plurality of wiring patterns, pattern defects are detected for each of the wiring patterns. Performing pattern defect detection only for a wiring having a defect after the identification is also effective in shortening the inspection time.

[0054]

As described above, according to the present invention, a defect in a wiring pattern is detected by using a leading contour vector and a following contour vector obtained from at least three contour points moving along the contour of the wiring pattern. To detect. Since there is no need to compare the wiring pattern to be detected with other standard patterns, it is possible to detect a fine pattern defect in a short time.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a printed circuit board wiring pattern defect detection apparatus according to an embodiment.

FIG. 2 is a flowchart illustrating a method of detecting a printed circuit board wiring pattern defect according to the embodiment;

FIG. 3 is a diagram showing a position of a CCD camera with respect to a specific wiring pattern on a printed circuit board.

FIG. 4 is a diagram showing an image of a captured wiring pattern after a binarization process has been performed;

FIG. 5 is a diagram showing three contour points defined along a contour line, a leading contour vector, and a following contour vector.

FIG. 6 is a diagram showing an angle between a preceding contour vector and a following contour vector.

FIG. 7 is a diagram showing four contour points, a preceding contour vector, and a following contour vector, which are determined along the contour line.

FIG. 8 is a direction vector table and a conversion table used when it is determined that there is a pattern defect without calculating an angle.

[Explanation of symbols]

12 CCD camera, 14 marker, 22 printed circuit board, 28 image processing unit, 100 printed circuit board wiring pattern defect detection device, A1, A2, A3, A4, A
e1, Ae2, Ae3, Ae4, As1, As2, As
3, As4, Bs1, Bm1, B1, Be1 contour points,
s1, s2, s3, s4 preceding contour vector, t1, t
2, t3, t4 Following contour vector.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2F065 AA03 AA12 AA22 AA25 AA32 AA49 AA53 BB02 CC01 DD06 FF04 JJ03 JJ19 JJ26 MM03 MM24 QQ04 QQ13 QQ25 QQ31 SS07 2G051 AA65 AB11 AC15 AC21 CA04 EA01 CD08

Claims (7)

[Claims] 1. A printed circuit board wiring pattern defect detection method for detecting a defect in a wiring pattern of a printed circuit board, comprising the steps of: extracting an outline of the wiring pattern from an image of the wiring pattern; A leading contour vector connecting at least three contour points to connect the preceding two contour points,
Determining a following contour vector connecting two contour points that follow the preceding contour point; and, when an angle between the preceding contour vector and the following contour vector deviates from a reference value, a wiring pattern defect is detected. Determining that there is a printed circuit board wiring pattern defect detecting method. 2. The printed circuit board wiring pattern defect detecting method according to claim 1, wherein in the step of obtaining the preceding contour vector and the following contour vector, three contour points moving along the contour are used. Wherein the preceding contour vector connects a first contour point and a second contour point, and the following contour vector connects a second contour point and a third contour point. Defect detection method. 3. The printed circuit board wiring pattern defect detecting method according to claim 1, wherein the printed circuit board wiring pattern defect detecting method is based on an angle between the preceding contour vector and the following contour vector. Obtaining a position data of the wiring pattern defect from the position data of the contour point when the value deviates from the value. 4. The printed circuit board wiring pattern defect detection method according to claim 1, wherein the step of determining that there is a wiring pattern defect includes an angle between the preceding contour vector and the following contour vector. After the angle deviates from the reference value, the contour points are moved until the angle returns to the reference value.After the angle deviates from the reference value, the position data of each contour point until the angle returns to the reference value is used. A method of detecting a printed circuit board wiring pattern defect, comprising obtaining pattern defect information. 5. The printed circuit board defect detection method according to claim 4, wherein the wiring pattern defect information includes a position, a width, and / or a depth of the wiring pattern defect. Wiring pattern defect detection method. 6. A printed circuit board wiring pattern defect detection device for detecting a defect in a wiring pattern of a printed circuit board, comprising: an imaging device for capturing an image of the wiring pattern; and a contour of the wiring pattern from the image of the wiring pattern. An image processing device for extracting a line, a preceding contour vector for moving at least three contour points along the contour line, and connecting two preceding contour points,
Find a trailing contour vector connecting two contour points that follow the preceding contour point, and when the angle between the leading contour vector and the trailing contour vector deviates from a reference value,
A printed circuit board wiring pattern defect detecting device, comprising: a pattern defect determining device that determines that there is a wiring pattern defect. 7. The printed circuit board wiring pattern defect detecting apparatus according to claim 6, wherein the printed circuit board wiring pattern defect detecting apparatus is configured such that an angle between the preceding contour vector and the following contour vector is set from a reference value. A marking device that obtains position data of a wiring pattern defect from the position data of the contour point at the time of departure, and marks a wiring pattern defect position of the wiring pattern from the obtained position data of the wiring pattern defect. A printed circuit board wiring pattern defect detection device, comprising: