JP2000233488A - Substrate alignment method in screen printing - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a method of aligning a substrate in screen printing that can improve the positional accuracy by correctly aligning the substrate. SOLUTION: In a substrate alignment method in screen printing for aligning a substrate 6 with a mask plate provided with a pattern hole, two recognition marks 6a and 6b provided at diagonal positions on the substrate 6 are provided. The position deviation angle Δθ in the rotational direction of the substrate 6 is obtained by recognizing the position of the electrode portion 6c on the substrate 6 where the position correction accuracy is most required. The amounts Δx and Δy are obtained, and the position of the substrate 6 is corrected based on the positional deviation amounts Δx and Δy and the positional deviation angle Δθ. As a result, it is possible to improve the position accuracy of the predetermined portion that requires the position correction accuracy most.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning a substrate in a screen printing, which aligns the substrate with a mask plate in the screen printing.

[0002]

2. Description of the Related Art In an electronic component mounting process, screen printing is used as a method for printing cream solder, conductive paste, or the like on a substrate. In this method, a mask plate having a pattern hole opened according to a portion to be printed is brought into contact with a substrate, a paste is supplied onto the mask plate, and a squeegee is slid, so that the squeegee slides on the substrate through the pattern hole. Prints the paste. In this screen printing, it is necessary to accurately align the substrate with the mask plate. For this reason, a recognition mark for position detection is provided on the substrate, and after the substrate is carried into the screen printing device, the amount of displacement of the substrate is detected by optically recognizing these recognition marks. The substrate is positioned after correcting the shift amount.
Conventionally, two-point recognition marks provided near the diagonal positions of the substrate have been widely used as recognition marks, and by recognizing these two points, the amount of displacement of the substrate in the orthogonal coordinate axis direction and the position in the rotation direction are recognized. The shift angle was calculated.

[0003]

However, since the substrate is made of a material such as resin which expands and contracts due to heat and external force, the substrate is deformed in the manufacturing process. Moreover, the deformation is not necessarily uniform over the entire substrate, and may cause partial deformation. For this reason, the relative positional relationship between the two recognition marks provided at diagonal positions of the substrate and each part within the substrate is not necessarily constant.

[0004] However, the part to be originally aligned, that is, the part where it is desired to ensure the most accurate alignment is usually another part inside the substrate and separated from the diagonal position. However, conventionally, since the position correction of the entire substrate is performed based on the position detection results of the two recognition marks provided at the diagonal positions, a portion requiring the highest position accuracy is not always correctly aligned, and the required position accuracy is not necessarily obtained. There was a problem that was not secured.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of positioning a substrate in screen printing, which can improve the positional accuracy by correctly positioning the substrate.

[0006]

According to a first aspect of the present invention, there is provided a method of positioning a substrate in screen printing, comprising: bringing a mask plate provided with pattern holes into contact with the substrate; supplying a paste onto the mask plate; Is a method of positioning a substrate in screen printing in which paste is printed on the substrate by sliding the substrate, and by recognizing characteristic points formed at two points remote from each other on the substrate, the position of the substrate in the rotation direction of the substrate is recognized. A position shift angle is obtained, and a specific feature point of a predetermined portion on the substrate is recognized to obtain a position shift amount of the predetermined portion in the orthogonal coordinate axis direction, and the position of the substrate is corrected based on the position shift amount and the position shift angle. To do.

According to a second aspect of the present invention, there is provided a method of aligning a substrate in screen printing, wherein the specific feature points are a plurality of feature points.

According to the present invention, a feature point provided at two mutually distant points on a substrate is recognized, a positional deviation angle in the rotational direction of the board is obtained, and a specific feature point at a predetermined portion of the board is recognized. By calculating the amount of displacement of the predetermined portion in the direction of the orthogonal coordinate axes, the position accuracy of the predetermined portion requiring the highest position correction accuracy can be improved.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the screen printing apparatus, FIG. 3 (a) is a plan view of the same board, and FIG. FIG. 4 is a block diagram showing a configuration of a control system of the screen printing apparatus. FIG. 5 is a flowchart of substrate alignment in the screen printing apparatus.
(B) is an explanatory view of the positioning of the substrate.

First, the structure of the screen printing apparatus will be described with reference to FIGS. In FIG. 1, a board positioning unit 1 serving as a board positioning means includes an X-axis table 2 and a Y-axis table 2.
The θ axis table 4 on the moving table composed of the axis table 3
Are stacked, and a Z-axis table 5 is further disposed thereon. On the Z-axis table 5, a substrate holding unit 7 for holding a substrate 6 by a clamper 8 is provided.
The substrate 6 to be printed is carried into the substrate positioning unit 1 by the carry-in conveyor 14 shown in FIG. By driving the substrate positioning unit 1, the position of the substrate 6 can be adjusted. The printed substrate 6 is carried out by the carry-out conveyor 15.

A screen mask 10 is provided above the substrate positioning section 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11. The substrate 6 is positioned with respect to the mask plate 12 by the substrate positioning unit 1 and abuts from below. A squeegee unit 13 is arranged on the screen mask 10 so as to be able to reciprocate in the horizontal direction. With the substrate 6 in contact with the lower surface of the mask plate 12, the mask plate 1
2, the squeegee of the squeegee unit 13 is brought into contact with the surface of the mask plate 12 and is slid, so that the pattern holes 12 a formed in the mask plate 12 are provided on the surface of the substrate 6. (Figure 2
Cream solder is printed.

Above the screen mask 10, a camera 20 as an image pickup means is provided. As shown in FIG. 2, the camera 20 is horizontally moved in the XY directions by the X-axis table 21 and the Y-axis table 22. That is, the X-axis table 21 and the Y-axis table 22 are moving means. The camera 20 captures an image of each recognition mark as a feature point provided on the substrate 6 and a specific position correction site. Then, based on the image data obtained by the imaging, the positions of the respective recognition marks and the specific position correction site are obtained.

As shown in FIG. 3A, the substrate 6 is provided with recognition marks 6a and 6b, which are characteristic points, at diagonal positions. The electrode portion 6c as a predetermined portion located on the inner side of the substrate 6 is a mounting portion on which electronic components such as QFPs which require the highest positional accuracy on the substrate 6 are mounted.
The specific position correction part has a higher priority in position correction. As shown in FIG. 3B, the electrode portion 6c is composed of a plurality of electrodes. In order to correct the position of the entire electrode portion 6c on average with high accuracy, two land portions p at diagonal positions are used.
Images of a and pb are taken as specific feature points of the position detection target, and a middle point 6p of the two detected land portions pa and pb is set as a representative point of the electrode portion 6c. Here, an example is shown in which two land portions pa and pb are recognized as specific feature points, but one of the lands may represent the electrode portion 6c.

Next, the configuration of a control system of the screen printing apparatus will be described with reference to FIG. In FIG.
U30 is an overall control unit that performs overall control of each unit described below. The recognition mark position storage unit 31 stores the positions of the recognition marks 6a and 6b of the substrate 6 and the positions of the electrode parts 6c. The print position data storage unit 32 calculates the positional shift amount between the substrate 6 and the mask plate 12 obtained by recognizing the recognition marks 6a and 6b and the electrode portions 6c, that is, the substrate 6 is stored in the mask plate 12 during printing. A position correction amount to be corrected at the time of positioning is stored. The recognition parameter storage unit 33 recognizes parameters necessary for specifying the recognition marks 6a and 6b and the electrode parts 6c provided on the substrate 6 as characteristic parts by image recognition, that is, recognition of the shape and dimensions of the recognition mark and the land. The parameters and the illumination data when the recognition marks 6a and 6b and the electrode part 6c are imaged by the camera 20 are stored.

The image processing section 34 detects the positions of the recognition marks 6a and 6b and the electrode portions 6c by performing image processing on image data obtained by imaging the substrate 6 with the camera 20. Here, the recognition marks 6a and 6b and the recognition parameters indicating the shape and size of the electrode part 6c are read from the recognition parameter storage unit 33, and the reference patterns of the recognition marks 6a and 6b and the electrode 6c are automatically generated. The position of the recognition marks 6a and 6b and the positions of the electrode portions 6c are detected by performing a position search process while performing pattern matching on the obtained image data. The table driving unit 35 drives the X-axis table 2, the Y-axis table 3, the θ-axis table 4, the Z-axis table 5, and the X-axis table 21 and the Y-axis table 22 for moving the camera.

Next, a method of aligning a substrate will be described with reference to the drawings in accordance with the flow chart of FIG. This alignment is performed for the purpose of detecting a relative positional shift amount between the loaded substrate and the screen mask during screen printing. First, in FIG. 1, the substrate 6 is carried in by the carry-in conveyor 14 and is positioned by the substrate positioning unit 1.

Next, the camera 20 images the recognition marks 6a and 6b and the electrode portion 6c on the substrate 6 (ST).
1). Next, the positions of the diagonal positions of the recognition marks 6a, 6b and the electrode portion 6c on the optical coordinates of the two lands pa, pb are detected, and the detection results are stored in the recognition mark position storage unit 31 (ST2). .

Next, based on the position detection results of the recognition marks 6a and 6b, as shown in FIG.
Is detected, and a displacement angle Δθ with respect to a normal angle (an angle formed by the straight line connecting points A and B) is obtained (ST3). Next, the position of the midpoint 6p of the lands pa and pb is determined from the position detection results of the lands pa and pb, and is determined as a representative point of the electrode portion 6c (ST4). Then, the positional deviation amounts Δx and Δy of the representative point 6p in the orthogonal coordinate axis direction with respect to the normal position (point P) are obtained (ST5), and the obtained Δ
x, Δ and Δθ are stored as position correction amounts (ST
6).

When the table driving unit 35 is driven to align the substrate 6, each axis is driven based on these positional correction amounts (ST7). As a result, FIG.
As shown in the figure, the representative point 6p of the electrode portion 6c which is the specific position correction portion is superimposed on the normal position point P. Therefore, high-accuracy alignment is realized in the vicinity of the electrode portion 6c where the positional accuracy is most required. After aligning the substrate 6 with the screen mask 10 in this manner,
Screen printing is performed (ST8).

By using the above alignment method,
It is possible to accurately correct the mounting position of an electronic component that requires mounting position accuracy such as QFP, and to accurately match the rotational angle of the entire substrate in the rotational direction.

[0021]

According to the present invention, the characteristic points provided at two mutually remote points on the substrate are recognized, the positional deviation angle in the rotational direction of the substrate is obtained, and the specific characteristic point at a predetermined portion of the substrate is determined. Recognition and determination of the amount of displacement in the orthogonal coordinate axis direction improve the positional accuracy of a predetermined portion requiring the greatest positional correction accuracy, and can correct the positional displacement in the rotational direction of the substrate with high accuracy. .

[Brief description of the drawings]

FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of a screen printing apparatus according to an embodiment of the present invention.

3A is a plan view of a substrate according to an embodiment of the present invention, and FIG. 3B is a partially enlarged view of the substrate according to the embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a control system of the screen printing apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart of substrate alignment in screen printing according to an embodiment of the present invention.

FIG. 6A is an explanatory diagram of a substrate alignment according to an embodiment of the present invention. FIG. 6B is an explanatory diagram of a substrate alignment according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate positioning part 6 Substrate 6a, 6b Recognition mark 6c Electrode part 6p Representative point 12 Mask plate 12a Pattern hole 13 Squeegee unit 20 Camera 31 Recognition mark position storage part 34 Image recognition part

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Seiichi Miyahara 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2C035 AA06 FA29 FB24 FB27 FB33 FD01 2C250 DA07 EB26 EB28 EB33 5E319 BB05 CD04 CD29 5E343 BB72 DD03 FF02 FF24

Claims (2)

[Claims] A mask plate provided with pattern holes is brought into contact with a substrate, a paste is supplied onto the mask plate, and a squeegee is slid to print the paste on the substrate. Recognizing a feature point formed at two mutually distant points on the substrate to determine a position shift angle in a rotation direction of the substrate and recognizing a specific feature point of a predetermined portion on the substrate. A position shift amount of the predetermined portion in the direction of the orthogonal coordinate axis, and correcting the position of the substrate based on the position shift amount and the position shift angle. 2. The method according to claim 1, wherein the specific feature points are a plurality of feature points.