JPH07260427A - Method and apparatus for detecting positioning mark - Google Patents

Abstract

PURPOSE:To detect the central position highly accurately by irradiating a positioning mark with a light beam having directivity, differentiating the variation of density extracted from an image being picked up, and then calculating the maximum value position of differentiated value. CONSTITUTION:A shutter 6a is opened at first for a through hole 2 and a light is projected only from an illuminator 4a before an image data is picked up for the illumination in Y direction by means of a TV camera 3. Subsequently, an image data for the illumination in X direction is picked up using a shutter 6b and an illuminator 4b. The through hole 2 receives highest quantity of light at the edge part thereof facing the illuminator and an image processor 5 calculates the address data of the maximum variation in the quantity of light thus determining the positional coordinates at the edge part. Center of the positional coordinates of through hole 2 is then determined based on two image data obtained by opening/closing the shutters 6a, 6b thus determining the central position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning mark detecting method and device for positioning marks (hereinafter referred to as target marks) provided on a substrate for aligning a ceramic substrate or the like, and more particularly to a circle. The present invention relates to a positioning mark detection method and apparatus for recognizing a shape of a shape target mark by an image processing apparatus and detecting a center position.

[0002]

2. Description of the Related Art Conventionally, various printed wiring boards (PWB: Printed Wiring) used in electronic devices or communication devices have been used.
ing Board, or PCB: Printed Circuit Board (hereinafter referred to as PWB or PCB), is an essential component for interconnecting electronic components and wiring patterns. Higher density and higher accuracy are being promoted.

In particular, the recent multi-layer / high-density technology is remarkable, especially in the case of a multi-layer ceramic substrate,
A layer has appeared, and the wiring pattern interval on the substrate is 0.1 mm or less, and the hole diameter of the through hole is generally 0.1 mmΦ or less.

In such a multilayer substrate, the drawing of wiring patterns and the formation of through-hole positions for connection between layers must be performed with extremely high precision.

Therefore, in the manufacturing stage of the PWB or PCB, the displacement of the wiring pattern drawing device or the through-hole forming device from a certain reference point is eliminated as much as possible, and this displacement is accurately detected. Therefore, there is a need for a technology for promptly making the correction.

Usually, a PWB or a PCB is provided with a target mark so that the position can be detected.
The position of this target mark is detected and the positional deviation is corrected.

However, as described above, electronic devices are becoming smaller and higher in density, and the size of PWBs or PCBs is also becoming finer. As a result, the size of target marks becomes extremely small. ing.

Therefore, the technique of detecting such a minute target mark and correcting the positional deviation based on the result is becoming more difficult.

As a technique for detecting the minute target mark and correcting the positional deviation, an image of the target mark is acquired in a non-contact manner by using an image pickup device such as a television camera, and the obtained image is 2 Various methods have been proposed in which the shape of a target mark is recognized using an image processing technique such as a binarization process, the center position of the target mark is calculated, and the positional deviation from the reference point is corrected.

For example, as an example of the method of detecting the center of a circular target mark, the techniques disclosed in Japanese Patent Laid-Open No. 63-237180 and Japanese Patent Laid-Open No. 2-227785 are known.

FIG. 8 is a diagram showing an example of image data acquired by an image pickup device according to the prior art disclosed in Japanese Patent Laid-Open No. 63-237180 and Japanese Patent Laid-Open No. 2-227785.

FIG. 8 shows image data obtained by photographing a through hole (not shown) as a circular target mark provided on a ceramic substrate (not shown). .

In FIG. 8A, 80 is image data obtained by an image pickup device (not shown), 81 is a through hole as a circular target mark, and 82 is a central position of the through hole 81.

The illumination direction of the illumination device (not shown) is the direction indicated by the arrow in the figure.

FIGS. 8B, 8C, and 8D are light amount profile data 83 in which changes in the light amount at the XX 'portion in the image data 80 shown in FIG. 8A are plotted.
Is.

FIG. 8B is a diagram showing an example in which the through hole 81 can be normally detected, and FIG. 8C shows a contrast between the background portion of the image data 80 and the through hole 81 lowered. FIG. 8D is a diagram showing an example of
Through hole 8 due to uneven illumination and uneven illumination
It is a figure which shows the example in which the light amount change of the edge part of 1 became non-uniform.

The first cause of the decrease in the contrast of the detected image as shown in FIG. 8C is that the amount of illumination light is low, and a high brightness lamp such as a mercury lamp is required to increase the amount of light.

The second cause is that, for example, when the size of the through hole as the circular target mark becomes small, the detection magnification of the image pickup device must be increased, resulting in the contrast of the detected image. Will be reduced.

[0019]

However, in the above-mentioned prior art, the through hole 8 as the target mark is used.
In the case where the density of the illumination light amount in 1 changes, or when it is necessary to increase the detection magnification of the imaging device as the through hole 81 becomes smaller, that is, as shown in FIG. If the contrast of the
Since the detected image data 80 is unstable and the image after the binarization process is deformed, the through hole 8
There was a problem that the center position 82 of 1 could not be obtained accurately.

Further, the use of a high-intensity lamp for increasing the light quantity has problems in terms of maintainability and economy.

Further, the smaller the target mark is, the shorter the working distance to the image pickup device is. Therefore, as in the case of a ring light (a ring-shaped light emitting body which gives an even amount of light to an illuminated object). However, there is a problem that a uniform and uniform illumination method cannot be adopted.

An object of the present invention is to provide a positioning mark detecting method and device for detecting the center position of a target mark with high accuracy when detecting a minute target mark even when the contrast of the detected image is lowered. To do.

[0023]

The outline of a typical one of the inventions disclosed in the present application will be briefly described as follows.

That is, a light beam having directivity is irradiated to the positioning mark set on the XY plane from an obliquely upward direction, and the positioning mark irradiated by the light beam is photographed from directly above the positioning mark. Then, a reference point in a line segment direction perpendicular to the irradiation direction of the light beam of the captured image is set, and a density change of the image in the line segment direction from the set reference point is extracted, The extracted density change is differentiated, the two maximum point positions of the differentiated values are calculated, and the midpoint position of the calculated two maximum point positions is determined to be the center position of the positioning mark. It is a thing.

Further, when a light beam having directivity with respect to the positioning mark placed on the XY plane is projected on the XY plane, it is irradiated from an obliquely upward direction having a positional relationship of 45 degrees with the positioning mark. Irradiation means, photographing means for photographing the positioning mark irradiated by the irradiation means from directly above the positioning mark, and X-axis direction and Y-axis direction on the XY plane of the image photographed by the photographing means. A reference point setting means for setting a reference point, extraction means for extracting a density change of the image in the X-axis direction and the Y-axis direction from the reference point set by the reference point setting means, and extraction by the extraction means. A differentiating means for differentiating the density change, and two maximum point positions for each of the X-axis direction and the Y-axis direction among the differential values differentiated by the differentiating means. And the maximum point position calculating means, in which and a center position calculating means for calculating the center position of the positioning mark from a total of four maximum point position calculated by the maximum point position calculating means.

[0026]

According to the above-mentioned means, a light beam having directivity is irradiated from an obliquely upward direction to the positioning mark installed on the XY plane, and the positioning mark irradiated by the light beam is emitted from the positioning mark. An image is taken from directly above, a reference point in a line segment direction perpendicular to the irradiation direction of the light rays of the image is set, and a density change of the image from the set reference point in the line segment direction is set. The extracted density change is differentiated, the two maximum point positions of the differentiated values are calculated, and the midpoint position of the calculated two maximum point positions is calculated to be the center position of the positioning mark. Therefore, even if the positioning mark is minute, the center position of the positioning mark can be detected with high accuracy from the obtained image.

Further, when a light beam having directivity with respect to the positioning mark set on the XY plane is projected on the XY plane, it is irradiated from an obliquely upward direction having a positional relationship of 45 degrees with the positioning mark. Irradiation means, photographing means for photographing the positioning mark irradiated by the irradiation means from directly above the positioning mark, and X-axis direction and Y-axis direction on the XY plane of the image photographed by the photographing means. A reference point setting means for setting a reference point, extraction means for extracting a density change of the image in the X-axis direction and the Y-axis direction from the reference point set by the reference point setting means, and extraction by the extraction means. A differentiating means for differentiating the density change, and two maximum point positions for each of the X-axis direction and the Y-axis direction among the differential values differentiated by the differentiating means. Since the maximum point position calculation means and the central position calculation means for calculating the central position of the positioning mark from a total of four maximum point positions calculated by the maximum point position calculation means are provided, the positioning mark is minute. Moreover, even if the contrast of the image is lowered, the center position of the positioning mark can be detected with high accuracy.

[0028]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

FIG. 1 is a block diagram showing an embodiment of a schematic configuration of an embodying device for realizing a positioning mark detecting method to which the present invention is applied.

In FIG. 1, reference numeral 1 is a ceramic substrate, 2 is through holes which are target marks for positioning, and they are provided at four corners of the ceramic substrate 1.

Positioning mark detecting apparatus 10 of this embodiment
0 is a TV camera 3 provided above the through hole 2.
And illumination devices 4a and 4b for illuminating the through hole 2,
An image processing device 5 that processes an image obtained from the TV camera 3, shutters 6a and 6b provided in the lighting devices 4a and 4b, and a shutter control device 7 that controls the opening / closing timing of the shutters 6a and 6b. And a control device 8 for controlling the image processing device 5 and the shutter control device 7.

FIG. 2 is a diagram showing the positional relationship between the ceramic substrate and the illuminating device in the positioning mark detecting method of this embodiment.

As shown in FIG. 2, the illumination device 4a illuminates from the Y direction and the illumination device 4b from the X direction on the center line of the through hole 2 in the upper left corner of the ceramic substrate 1 shown in FIG. The image (not shown) is taken almost directly above the through hole 2.

By the illumination of the illumination devices 4a and 4b, an image A14 in the Y direction and an image B15 in the X direction are obtained, and a large amount of light is applied to the sides opposite to the illumination direction. This portion is the edge portion 16 of the through hole 2.

Note that the edge portion 16 is exaggerated in FIG. 2 in order to make the contents of the description easy to understand.

FIG. 3 is a diagram showing image data and light amount profile data according to the positioning mark detection method of this embodiment.

FIG. 3A shows image data 9 detected by the TV camera 3 (not shown), and 13 is the center position of the through hole 2.

FIG. 3B is a diagram showing the light amount profile data 11 obtained by illumination from the Y direction.
1) shows the light amount profile data 11 of the XX ′ portion in the image data 9, and FIG.
The light intensity profile data 11 of the YY ′ portion in FIG.

FIG. 3C is a diagram showing the light amount profile data 11 obtained by illumination from the X direction.
1) shows the light amount profile data 11 of the XX ′ portion in the image data 9, and FIG.
The light intensity profile data 11 of the YY ′ portion in FIG.

Here, by switching the opening and closing of the shutters 6a and 6b, the light amount profile data 11 of FIGS. 3B and 3C is switched. That is, the illumination device 4a (not shown) illuminates in the Y direction to obtain the light amount profile data 11 in FIGS. (B-1) and (B-2), and the illumination device 4b (not shown).
Illumination from the X direction by (C-1), (C-
The light intensity profile data 11 of 2) is obtained.

The light intensity profile data 11 here is actually a plot of the degree of light and shade of an image, and the light and shade of this image corresponds to the magnitude (brightness) of the light intensity. .

Although not shown in FIG. 3, the position of the TV camera 3 is set as a reference for position detection, that is, substantially directly above the through hole 2, as described above.
The deviation amount from the center of the TV camera 3 is adjusted to be the positional deviation amount of the through hole 2.

The illumination devices 4a and 4 used in this embodiment are
b is a lighting method in which a lens is attached to a light projecting port and light having directivity such as spot light or slit light (a spot light of 2 to 3 mmΦ is used in the experiment of the inventor) is projected. .

Hereinafter, with reference to FIGS. 1, 2 and 3,
A method of detecting the center position 13 of the through hole 2 will be described.

The center position 13 of the through hole 2 is detected by
First, the shutter 6a is opened by the shutter control device 7 (at this time, the shutter 6b is closed), and the lighting device 4a.
Image data 9 obtained by illumination from the Y direction is acquired by the TV camera 3 shown in FIG.

Next, the shutter 6b is opened by the shutter control device 7 (at this time, the shutter 6a is closed) to illuminate only the illumination device 4b, and the TV camera 3 shown in FIG. Image data 9 is acquired.

Thus, the two image data 9 from the X and Y directions can be obtained.

As can be seen from FIG. 2, the lighting devices 4a, 4a,
The through hole 2 illuminated by b becomes brighter because the edge portion 16 facing the direction of illumination receives the largest amount of light.

Therefore, looking at the light amount profile data 11 of the image data 9 in the same direction as the illumination direction, the edge portion 16 of the through hole 2 capable of obtaining the specular reflected light is shown in FIG. These waveforms cannot be used as data for obtaining the center position 13 of the through hole 2 because of the waveforms shown in C-1).

However, the light amount profile data 11 of the image data 9 in the direction perpendicular to the illumination direction is shown in FIG.
As shown in (B-1) and (C-2), the waveform and the position of the through hole 2 to be recognized are well represented. Therefore, these waveforms are used as data for determining the center position 13 of the through hole 2. To use.

From the light amount profile data 11 shown in FIGS. 3B-1 and 3C-2, since the maximum value of the change in the light amount is the edge portion 16 of the through hole 2, the address data of this maximum value is obtained. The position coordinates of the edge portion 16 can be obtained by the calculation by the image processing device 5.

The circled portion E17 shown in FIGS. 3 (B-1) and (C-2) is the point where the change in the light amount is maximum.

Therefore, the two image data 9 obtained by opening and closing the shutters 6a and 6b are obtained, and two good light amount profile data 11 are obtained from these two image data 9 to obtain the edge portion of the through hole 2. 16
The four position coordinates can be obtained, and the center position 13 can be calculated by finding the midpoint of the four position coordinates.

However, in the above method, the shutters 6a, 6
Since the opening and closing of b is controlled and the image data 9 in each illumination light is detected by the TV camera 3, the detection time is delayed, and in order to store the two image data 9, many image memories are required. You will need it.

Therefore, as shown in FIG. 4, only the illuminating device 4a is installed at a position moved by 45 degrees with respect to the coordinates for detecting the position of the through hole 2.

FIG. 4 is a diagram showing the positional relationship between the ceramic substrate and the illuminating device in the case where one illuminating device is used in this embodiment.

FIG. 4A is a plan view showing the positional relationship between the illuminating device 4a and the ceramic substrate 1, and FIG.
[Fig. 4] is a side view seen from the direction of arrow B in Fig. 4 (A).

As shown in FIG. 7A, the lighting device 4a is
The ceramic substrate 1 is installed at a position of 45 degrees with respect to the line XX ′, and as shown in FIG.
It is installed at an angle of about 10 to 45 degrees with respect to the plane.
(Experiments by the inventor have shown that good image data 9 can be obtained when the angle with respect to the side surface of the ceramic substrate 1 is approximately 45 degrees).

In the positional relationship as shown in FIG. 4, the shutter 6a of the illumination device 4a is opened, the TV camera 3 (not shown) captures an image, and the position of the through hole 2 is detected from one image data 9. Light amount profile data 11 in the vertical direction (Y direction) and the horizontal direction (X direction) of coordinates
To get.

FIG. 5 is a diagram showing image data and light amount profile data when one illumination device is used in this embodiment.

As shown in FIG. 5, image data 9 (FIG. 5 (A)) obtained by one illumination device (not shown) by illuminating from an angle of 45 degrees to the upper left.
From the light intensity profile data 11 in the XX ′ part
(FIG. 5 (B)) and the light intensity profile data 11 (FIG. 5 (C)) in the YY ′ portion can be obtained.

As a result, the problems of the switching operation of the shutters 6a and 6b by the shutter control device 7 and the detection time such as the number of times of image pickup and the number of image memories can be solved.

However, at this time, since a certain amount of illumination light is required, the illumination device 4a shown in FIG. 4 is provided with a condenser lens having a higher condensing property, and the edge portion 16 of the through hole 2 to be detected is detected. It is necessary to secure the necessary and sufficient amount of illumination light.

At this time, if the amount of illumination light is too large, the amount of specular reflection light at the edge portion 16 facing the illumination light becomes too strong, and the amount of light data in the image data 9 will be saturated. A polarizing lens is installed on the illuminating device 4a and the TV camera 3 so that the light corresponding to the amount of specular reflection light is deleted.

FIG. 6 is a diagram showing image data and differential data for detecting an edge portion in the positioning mark detecting method of this embodiment.

FIG. 6A shows the image data 9 shown in FIG.
6B is a diagram showing the light amount profile data 11 of the XX ′ portion obtained from the image data 9, and FIG. 6C shows the light amount profile data 11 with respect to FIG. It is the differential data 12 obtained by performing the differential processing.

As shown in FIGS. 6B and 6C, in the light amount profile data 11, the differential value takes the maximum value at the point of the circled portion E17 where the change in the light amount becomes the maximum, and the position coordinate where this maximum value is obtained. From, by calculating the midpoint,
The center position 13 of the through hole 2 is required.

FIG. 7 is a flow chart showing the procedure of image processing in the positioning mark detecting method of this embodiment.

As shown in FIG. 7, first, the through hole 2
The image data 9 is used as the image information of the shape of the TV camera 3
It is taken in from (not shown) and stored in the image memory in the image processing apparatus 5 (step 71).

Next, in order to grasp the shape of the through hole 2 from the captured image data 9, the reference point for extracting the light amount profile data 11 showing the light amount change is set (step 72).

If the ceramic substrate 1 is displaced, the position of the TV camera 3 (not shown) is also displaced, and as a result, the position of the through hole 2 on the image data 9 is also displaced.

Therefore, in order to obtain the position coordinates of the edge portion 16 of the through hole 2, it is necessary to macroscopically recognize the position of the through hole 2 in which the positional deviation occurs in the image data 9.

For this purpose, the projection addition processing of the image data 9 is performed, the macroscopic position is obtained from the projection data of the through hole 2, and the reference point (or reference position) from which the light amount profile data 11 is extracted is set (step). 72).

Next, the light amount profile data 11 in the XX 'direction or the YY' direction is obtained from the reference point set in step 72 (step 73).

Then, in order to obtain the maximum value portion of the light quantity indicating the position coordinates of the edge portion 16 of the through hole 2 from the light quantity profile data 11, the light quantity profile data 1
1 is differentiated to obtain two maximum absolute values of the differential data 12 (step 74).

Next, the obtained light amount profile data 11
The differential maximum value of is used as the position coordinate of the edge portion 16, the midpoint of the position coordinates of the two edge portions 16 is obtained, and the center position 13 of the through hole 2 is calculated (step 75).

By performing the above processing, the center position 13 of the through hole 2 can be accurately obtained.

In this embodiment, the ceramic substrate 1 is mainly used.
The detection of the position coordinates of the through hole 2 has been described, but this assumes a manufacturing process of the ceramic green sheet, and the technique disclosed in the present application is
The present invention is not limited to this, and can be sufficiently applied to, for example, alignment of a board when components are mounted on a PWB or a PCB, or correction of positional deviation.

In addition to the above-described positioning mark detection method and execution device, a processing device for calculating the overall position of the ceramic substrate 1 from the obtained center position of the through hole 2 and an amount of deviation from the reference position are obtained. , By adding a moving stage that corrects the amount of displacement,
It serves as a substrate position shift correction device and a positioning device.

As can be seen from the above description, according to this embodiment, when the through hole 2 to be detected (recognized) is minute and the contrast of the image is lowered by increasing the detection magnification of the TV camera 3. Even if the conventional 2
The position coordinates of the edge portion 16 of the through hole 2 which is a detection (recognition) target can be detected with high accuracy as compared with the binarized image processing method.

[0082]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

(1) The positioning marks are minute,
Moreover, even if the contrast of the detected image is lowered, the edge portion of the positioning mark to be detected can be reliably detected without causing an image processing error or erroneous recognition. The center position can be calculated with high accuracy.

By (2) and (1), it becomes possible to provide a positioning device capable of correcting the positional deviation of the ceramic substrate or the like with high accuracy.

(3) Due to (1) and (2), errors due to alignment can be reduced, and the yield rate in the process of drawing a wiring pattern such as a ceramic substrate and the process of forming through holes can be improved. .

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an example of a schematic configuration of an implementation device for realizing a positioning mark detection method to which the present invention is applied.

FIG. 2 is a diagram showing a positional relationship between a ceramic substrate and a lighting device in a positioning mark detecting method of the present embodiment.

FIG. 3 is a diagram showing image data and light amount profile data according to the positioning mark detection method of the present embodiment.

FIG. 4 is a diagram showing a positional relationship between a ceramic substrate and a lighting device when one lighting device is used in the present embodiment.

FIG. 5 is a diagram showing image data and light amount profile data when one illumination device is used in the present embodiment.

FIG. 6 is a diagram showing image data and differential data for detecting an edge portion in the positioning mark detecting method of the present embodiment.

FIG. 7 is a flowchart showing a procedure of image processing in the positioning mark detecting method of the present embodiment.

FIG. 8 is an explanatory diagram for explaining a conventional positioning mark detection method.

[Description of Reference Signs] 1 ... Ceramic substrate, 2 ... Through hole, 3 ... TV camera, 4 ... Illumination device, 5 ... Image processing device, 6 ... Shutter,
7 ... Shutter control device, 8 ... Control device, 9 ... Image data, 11 ... Light amount profile data, 12 ... Differential data, 13 ... Through hole center position, 14 ... Image A, 15
... image B, 16 ... edge part, 17 ... maximum point of change in light intensity,
100 ... Positioning mark detection device.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H05K 3/46 X 6921-4E (72) Inventor Toshiro Tamura 1 Horiyamashita, Hadano, Kanagawa Co., Ltd. (72) Inventor, Megumi Mio, Horiyamashita, Hadano City, Kanagawa Prefecture (72) General-purpose computer division, Hiritsu Manufacturing Co., Ltd. (72) Inventor, Keiji Takagi, 1 Horiyamashita, Hadano City, Kanagawa Ta Engineering Co., Ltd.

Claims (3)

[Claims] 1. A light beam having directivity to a positioning mark set on an XY plane is obliquely irradiated, and the positioning mark irradiated with the light beam is photographed from directly above the positioning mark. Then, a reference point in a line segment direction perpendicular to the irradiation direction of the light beam of the captured image is set, and a density change of the image in the line segment direction from the set reference point is extracted, The extracted density change is differentiated, two maximum point positions of the differentiated values are calculated, and the midpoint position of the calculated two maximum point positions is obtained and set as the center position of the positioning mark. Detecting method for positioning mark. 2. When a light beam having directivity with respect to a positioning mark installed on an XY plane is projected on the XY plane, the light is irradiated from an obliquely upward direction having a positional relationship of 45 degrees with the positioning mark. , Photographing the positioning mark irradiated with the light beam from directly above the positioning mark,
A reference point in the X-axis direction and the Y-axis direction on the XY plane of the captured image is set, and a density change of the image in the X-axis direction and the Y-axis direction is extracted from the set reference point, Differentiating the extracted density change, calculating two maximum point positions for each of the X-axis direction and the Y-axis direction among the differentiated differential values, and obtaining the center position of the positioning mark from a total of four maximum point positions. A method for detecting a positioning mark, characterized by: 3. When a light beam having directivity with respect to a positioning mark set on an XY plane is projected on the XY plane, the light is emitted from an obliquely upward direction having a positional relationship of 45 degrees with the positioning mark. Irradiating means, a photographing means for photographing the positioning mark irradiated by the irradiating means from directly above the positioning mark, and an X-axis direction on the XY plane of the image photographed by the photographing means and a Y direction.
Reference point setting means for setting a reference point in the axial direction, extraction means for extracting a density change of the image in the X axis direction and the Y axis direction from the reference point set by the reference point setting means, and the extraction means Differentiating means for differentiating the density change extracted by, the maximum point position calculating means for calculating two maximum point positions for each of the X-axis direction and the Y-axis direction among the differential values differentiated by the differentiating means, and the maximum point position A positioning mark detecting device, comprising: a center position calculating means for calculating a center position of the positioning mark from a total of four maximum point positions calculated by the calculating means.