JPH05229097A - Screen printing method - Google Patents

Abstract

PURPOSE:To dispense with the alignment work of a printing screen to an object to be printed by a worker and to enable efficient printing of high accuracy regardless of the skillfulness of the worker. CONSTITUTION:Temporary printing is applied to a substrate 5 in a reference state using a printing screen 2 and the pattern temporarily printed on the substrate 5 is photographed by cameras 11A, 11B to be confirmed and the angle of rotation from the reference state of the substrate 5 and the correction quantities of the substrate 5 in X- and Y-directions necessary for the alignment of the printing screen 2 and the substrate 5 are calculated on the basis of the image confirmation result to correct and control the posture of the substrate 5 in final printing to align the printing screen 2 and the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing method suitable for printing a conductor or protective coat pattern on an object to be printed such as a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
In the screen printing device, the position of the printing pattern formed on the screen every time the plate is changed (screen exchange) (the pattern for screen printing in which a large number of minute holes are formed) is set on the printing object such as a printed wiring board. On the other hand, there is a problem that the plate-making alignment work for aligning the plate-making position is required, and the plate-making alignment work has to rely on a skilled worker. In particular, when it is desired to perform high-precision printing with a screen printing apparatus, the plate making matching work becomes more and more difficult, a high degree of skill is required, and the setup work time becomes long.

In view of the above points, the present invention eliminates the need for the operator to align the printing screen with respect to the material to be printed, and enables a highly accurate and efficient printing regardless of the skill of the operator. The purpose is to provide a printing method.

[0004]

In order to achieve the above object, in the screen printing method of the present invention, temporary printing is performed on a printing medium in a standard state using a printing screen, and the printing medium is temporarily printed. The image of the pattern is recognized, and based on the result of the image recognition, the rotation angle from the reference state of the printing object and X, which are necessary for the alignment between the printing screen and the printing object,
The correction amounts in the Y direction and the Y direction are calculated, and the posture of the printing object in the main printing is corrected and controlled to align the printing screen and the printing object.

[0005]

In the screen printing method of the present invention, the material to be printed is temporarily printed by using the printing screen to be used before mass production, and the pattern temporarily printed on the material to be printed is recognized as an image to be printed. The amount of rotation and position correction of the printing medium required for alignment with the printing screen is calculated, and the printing medium and the printing screen are aligned during mass production. For this reason, it is possible to automate the troublesome plate-making matching work between the material to be printed and the screen for printing, which has traditionally depended on the skill of the operator, and it is possible to perform high-precision and high-repetition printing, and also shorten the setup time required for screen replacement. it can. If the image recognition mark is provided outside the originally required print pattern, it is possible to perform overcoat printing of a plurality of layers on one printing medium.

[0006]

Embodiments of the screen printing method according to the present invention will be described below with reference to the drawings.

1 and 2 show a screen printing apparatus used in an embodiment of the present invention. In these figures, 1 is an apparatus base and 2 is a printing screen supported at a predetermined height with respect to the base. 3 is a print head. The print head 3 has a squeegee or the like for applying a printing paste on the printing screen 2, and is driven in the Y direction with respect to the print head support frame 4 supported on the base 1 at a predetermined height. It is supposed to be done.

As shown in FIG. 3, an XY-θ table 6 is provided for positioning and holding the alumina substrate 5 as a material to be printed.
Is installed on the base 1 so as to be slidable in the X direction (perpendicular to the Y direction). Here, the XY-θ table 6 is X
Direction, Y direction movement and θ direction (rotation direction) movement, and the long air cylinder (rodless cylinder etc.) 7 shows the substrate receiving position (image processing position) shown by the solid line in FIG. ) P and the printing position Q indicated by the phantom line.

X stopped at the substrate receiving position P
On the -Y- [theta] table 6, the alumina substrate 5 before printing is supplied and placed by the supply unit 10. XY-θ table 6
Has a function of positioning and holding the supplied substrate 5. Further, the cameras 11A and 11B as image pickup means face the XY-θ table 6 at the substrate receiving position P to image the reference holes 20A and 20B as the reference marks at the upper and lower edges of the substrate 5 of FIG. It is fixedly placed at the position. The pair of reference holes 20A and 20B can be easily formed by punching with a mold before firing the alumina substrate.

On the other hand, the printed substrate 5 on the XY-θ table 6 which has moved to the printing position Q and stopped is moved to the discharging conveyor 13 and discharged.

Next, the screen printing operation using the apparatus of FIGS. 1 and 2 will be described with reference to the operation flowchart of FIG.

First, temporary printing is carried out using the printing screen 2 used in mass production and the alumina substrate 5 as the object to be printed (the same as in mass production). Ie, step #
The alumina substrate 5 is supplied from the supply unit 10 and placed on the XY-θ table 6 stopped at the substrate receiving position P at 1. Then, in step # 2, the XY-θ table 6
The substrate 5 is positioned and fixed on the top. The board positioning at this time is, for example, as shown in FIG. 5, a straight line connecting the pair of reference holes 20A and 20B formed in the board 5 coincides with the Y direction (in other words, the moving direction of the XY-θ table 6). Is X
(Orthogonal to the direction) (the posture of FIG. 5 becomes the reference state of the substrate 5). In step # 3, the reference holes 20A and 20B of the substrate 5 in the reference state of FIG. 5 are imaged by the cameras 11A and 11B, respectively, and the reference holes 20A are received by the image processing device which receives the video output of the cameras 11A and 11B. ，
The position of 20B is recognized (for example, the position of each reference hole is stored in a fixed XY coordinate system). In FIG. 5, the fields of view of the cameras 11A and 11B are indicated by frames 12A and 12B.

Thereafter, in step # 4, the air cylinder 7 is actuated, and the action moves the XY-θ table 6 from the substrate receiving position P to the printing position Q, and the substrate 5 on the XY-θ table 6 is moved. Will be located below the print head 3 and the printing screen 2. After the movement of the XY-θ table 6 is completed, the print head 3 executes the printing operation in step # 5. That is, the print head 3 moves in the Y direction with respect to the print head support frame 4, and the squeegee of the print head presses the printing screen 2 onto the substrate 5 to apply the printing paste onto the printing screen 2. Spread out. As a result, the printing paste is screen-printed on the substrate 5 according to the predetermined printing pattern of the printing screen 2.

Here, as shown in FIG. 6, the printing screen 2 has image recognition mark forming pattern portions 22A and 22B in a fixed positional relationship in addition to the originally required printing pattern portion 21 (manufacturing). Sometimes they can be formed at the same time.). The pair of image recognition mark forming pattern portions 22A and 22B have the same spacing as the pair of reference holes 20A and 20B, and when printed correctly on the substrate 5, the reference holes 20A and 20B are formed as shown in FIG. The image recognition marks 23A, 2 are located at the right side position which is translated by the distance L1 in the X direction.
Design so that 3B is located.

After executing the screen printing at the printing position Q, the XY-θ table 6 is returned to the substrate receiving position P in step # 6. Then, the image processing of step # 7 is executed. That is, as shown in FIG. 8, the XY-θ table 6 is arranged so that the actually printed image recognition marks 23A and 23B fall within the visual fields 12A and 12B (shown by solid line frames in FIG. 8) of the cameras 11A and 11B. The position of the X direction is adjusted and the images 11A and 11B are used to image the image recognition marks 23A and 23B. As shown in FIG. 7, if the alignment of the printing screen 2 and the substrate 5 is accurate, the image recognition marks 23A and 23B are separated from the reference holes 20A and 20B by the distance L in the X direction.
It should move to the right side position by parallel translation by one, but it is normal that the alignment is not completed at the stage of temporary printing. As shown in FIG. 8, the reference hole 20 on the straight line in the Y direction is shown.
Image recognition marks 23A and 23B are printed at positions deviated from the original positions with respect to A and 20B. Using the image recognition result of the positions of the image recognition marks 23A and 23B, the substrate 5 is moved by the XY-θ table 6 with respect to the printing screen 2 for alignment. Therefore, in the image processing device that receives the video output of the cameras 11A and 11B, the correction rotation amount Δθ of the XY-θ table 6 for making the reference holes 20A and 20B parallel to the image recognition marks 23A and 23B. , The distance between the image recognition marks 23A and 23B and the reference holes 20A and 20B is L after the rotation of Δθ.
A correction amount ΔX in the X direction and a correction amount ΔY in the Y direction required to make the value 1 are calculated. Position is indicated by 20A "20B").

The correction in the X and Y directions is carried out after the rotation of Δθ, because the positions of the reference holes 20A and 20B in the X and Y directions are further changed by the rotation of the XY-θ table 6. Is.

After the correction rotation amount Δθ and the correction amounts ΔX and ΔY of the XY-θ table 6 necessary for plate making of the printing screen 2 and the alumina substrate 5 are calculated by the above-mentioned temporary printing, mass production is executed. First, in step # 11, the alumina substrate 5 is supplied from the supply unit 10 and placed on the XY-θ table 6 stopped at the substrate receiving position P. Then, in step # 12, the substrate 5 is positioned and fixed on the XY-θ table 6. The substrate positioning at this time is initially set so that the straight line connecting the pair of reference holes 20A and 20B formed in the substrate 5 as shown in FIG. In step # 13, the camera 1
After confirming that the substrate 5 is in the reference state of FIG. 5 by imaging the reference holes 20A and 20A of the substrate 5 with 1A and 11B, only the corrected rotation amount Δθ calculated in the temporary printing process is used for the XY-θ table. 6 is rotated and then moved by the correction amounts ΔX and ΔY. After these corrections, it is confirmed whether the cameras 11A and 11B have been appropriately corrected.

Thereafter, in step # 14, the air cylinder 7
The XY-θ table 6 moves from the substrate receiving position P to the printing position Q by its action, and the substrate 5 on the XY-θ table 6 moves the print head 3 and the printing screen 2 to each other.
Will be located below. After the movement of the XY-θ table 6 is completed, the print head 3 executes the printing operation in step # 15. That is, the print head 3 moves in the Y direction with respect to the print head support frame 4, and the squeegee of the print head presses the printing screen 2 onto the substrate 5 to apply the printing paste onto the printing screen 2. Spread out. As a result, the printing paste is screen-printed on the substrate 5 according to the predetermined printing pattern of the printing screen 2. Here, the reference rotation holes 20A, 2 are set to the image recognition marks 23A, 23B by moving the correction rotation Δθ and the correction amounts ΔX, ΔY of the XY-θ table 6 in advance.
0B is parallel, and the interval is equal to the design value L1. As shown in FIG. 7, screen printing can be performed without positional deviation (however, as a result of the correction rotation Δθ, the line connecting the reference holes 20A and 20B is parallel to the Y direction). It is different from Fig. 7 in that it does not happen.)

After executing the screen printing at the printing position Q, the XY-θ table 6 is returned to the substrate receiving position P in step # 16, and the printed substrate 5 is transferred onto the discharge conveyor 13 in step # 17. Is discharged. On the XY-θ table 6 which has returned to the substrate receiving position P, a new substrate 5 is supplied again in step # 11.

In the case of printing, for example, four patterns of an electrode pattern, a resistance pattern, a first coat pattern and a second coat pattern on an alumina substrate as a material to be printed,
As shown in FIG. 9, the reference holes 20A, 2 of the alumina substrate 5 are formed.
The image recognition marks 23A and 23B attached to the electrode pattern are arranged on the substrate 5 at a distance L1 on the right side in parallel with 0B.
The image recognition marks 24A, 2 attached to the resistance pattern in parallel with the reference holes 20A, 20B and with a space L2 on the left side.
4B is parallel to the reference holes 20A and 20B of the substrate 5, and the image recognition marks 25A and 25B attached to the first coat pattern are parallel to the reference holes 20A and 20B of the substrate 5 with a distance L3 on the right side. Image recognition marks 26A, 26 attached to the second coat pattern with an interval L4 on the left side
It is sufficient to design so that B is located and repeat the operation flow of FIG. 4 for each pattern.

[0021]

As described above, according to the screen printing method of the present invention, it is possible to automatically carry out plate making of the material to be printed on the printing screen by the image processing, so that the skill of the worker can be improved. It is possible to eliminate the troublesome plate-making matching that relied on, and it is possible to perform high-precision, high-repetition printing regardless of the skill of the operator.

[Brief description of drawings]

FIG. 1 is a plan view of a screen printing apparatus used in an example of a screen printing method according to the present invention.

FIG. 2 is a front view of a main part of the screen printing apparatus.

FIG. 3 is a plan view showing a substrate as an object to be printed used in an example.

FIG. 4 is an operation flowchart in the case of the embodiment.

FIG. 5 is a plan view of the substrate in the reference state.

FIG. 6 is a plan view showing a print pattern portion and an image recognition mark forming pattern portion on a printing screen.

FIG. 7 is a plan view when screen printing is ideally performed on a substrate.

FIG. 8 is an explanatory diagram showing a correction algorithm in the case of recognizing an image recognition mark after provisional printing and aligning the substrate and the printing screen.

FIG. 9 is a plan view showing the arrangement of image recognition marks and the like when four patterns are printed on a substrate.

[Explanation of symbols]

1 Device Base 2 Printing Screen 3 Printing Head 4 Printing Head Support Frame 5 Substrate 6 XY-θ Table 7 Air Cylinder 10 Supply Unit 11A, 11B Camera 13 Ejecting Conveyor 20A, 20B Reference Hole 21 Printing Pattern Part 22A, 22B Image recognition mark forming pattern portion 23A, 23B, 24A, 24B, 25A, 25B, 2
6A, 26B Image recognition mark P Substrate receiving position Q Printing position

Claims (3)

[Claims] 1. A printing screen is used to temporarily print on an object to be printed in a standard state, a pattern temporarily printed on the object to be image-recognized, and the printing screen and the object to be printed are recognized based on the image recognition result. The printing is performed by calculating the rotation angle from the reference state of the printing medium necessary for alignment with the printing medium and the correction amount in the X direction and the Y direction, and correcting and controlling the posture of the printing medium in the main printing. A screen printing method characterized by aligning a printing screen and an object to be printed. 2. The screen printing method according to claim 1, wherein at least a pair of reference marks are formed on the printing medium in order to perform image recognition of the reference state of the printing medium. 3. The screen printing method according to claim 1, wherein the printing pattern of the printing screen includes at least a pair of image recognition marks.