JPH03178187A - Method for making screen printing on printed wiring board - Google Patents

Abstract

PURPOSE:To eliminate defective screen printing and reduce the screen printing cost so as to improve the productivity by performing screen printing on a specific dummy board and, after removing the ink on the dummy board by washing, screen printing again on another board to be printed. CONSTITUTION:After screen printing is performed on a board to be printed, the screen printing is performed on a dummy board having a adhesive printing surface and almost the same thickness as the board to be printed has. After printing, the ink on the dummy board is removed by washing and the screen printing is performed on another board to be printed. Since the dummy board having the adhesive surface is used, the dust or dirt from wastes or paper is not produced as in the case using the wastes or paper impregnated with a solvent is used, when the ink 5 moved to the back of the emulsion 3 formed on the plate is removed. Therefore, the printing cost can be reduced and the productivity can be improved, since defective printing can be prevented and no wasteful paper or a film provided with an adhesive layer is required, further, the dummy board is used repeatedly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for screen printing printed wiring boards.

2. Prior Art In conventional screen printing for printed wiring boards, ink gets on the back side of the emulsion on the plate, causing bleeding during printing.
The method shown in the figure was used.

In other words, in Fig. 3, 1 is the plate frame, 2 is the plate, and 3 is plate 2.
The emulsion formed on the plate 2, 5 the ink that has spread behind the emulsion 3 formed on the plate 2, 10 a rag soaked in a solvent, 11 the operator, 9 the substrate to be printed, 7 the printing This is the stage of the machine. In the method shown in FIG. 3, the ink 5 on the back side of the emulsion 3 formed on the plate 2 was removed by wiping with a cloth 10 soaked in a solvent.

In FIG. 4, 1 is the plate frame, 2 is the plate, 3 is the emulsion formed on the plate 2, 4 is the squeegee, and 5 is the ink that has spread to the back of the emulsion 3 formed on the plate 2. , 12 is paper, 9 is a substrate to be printed, and 7 is a stage of a printing machine. The ink 5 that has spread to the back side of the emulsion 3 formed on the plate 2 is printed by inserting paper 12 between the plate 2 and the printing substrate 9.
had been removed.

Furthermore, in Fig. 5, 1 is the plate frame, 2 is the plate, and 3 is the plate 2.
4 is the emulsion formed on the top, 4 is the squeegee, 5 is the ink that has spread to the back of the emulsion 3 formed on the plate 2, 13 is the film, 14 is the adhesive layer formed on the film 13, 9 is the adhesive layer formed on the film 13 The printed substrate 7 is a stage of a printing machine. In the method shown in FIG.
The adhesive layer 14 is a film 13 formed on at least one side.
It was removed by printing with the plate placed on the plate 2 side.

Problems to be Solved by the Invention However, in such a conventional screen printing method for printed wiring boards, when removing the ink 5 that has spread to the back of the emulsion 3 formed on the plate 2, it is necessary to use the cloth 10 or paper. 1
Dust and dirt are generated from 2. The generated dirt and dust may adhere to the plate 2, and during the next printing, the ink may not pass through only the areas where the dirt or dust has adhered, or the ink may smear along the adhered dirt or dust. There was a problem in that it caused printing defects.

In addition, when removing the ink 5 that has spread to the back of the emulsion 3 formed on the plate 2 by wiping it with a rag 10 soaked in a solvent, the solvent that has soaked into the rag 10 will seep out and the plate There was a problem that it mixed with the ink above and had a negative effect on the ink.

Furthermore, when removing the ink 5 that has spread behind the emulsion 3 formed on the plate 2 onto the paper 12 by printing and transferring, the adhesiveness between the paper 12 and the ink is insufficient. Another problem was that the ink 5 that had spread to the back of the emulsion 3 formed on the plate 2 could not be completely removed.

In addition, when removing the ink 5 that has spread to the back side of the emulsion 3 formed on the plate 2 by printing on the film 13 having the adhesive layer 14 formed on at least one side or on the paper 12, printing is performed. Since the film 13 or the paper 12 cannot be recycled, they must be disposed of, resulting in an increase in cost.

Furthermore, no matter which conventional method is used, if the substrates to be printed are automatically fed sequentially and screen printing is performed, it is necessary to stop the automatic feeding of the substrates to be printed once and place the substrates on the plate 2. It is necessary to remove the ink 5 that has spread to the back side of the emulsion 3 formed on the surface of the emulsion 3, which causes a problem in that productivity is greatly reduced.

In order to solve the above problems, the present invention aims to provide a screen printing method for printed wiring boards that is free from screen printing defects, is low in cost, and has high productivity.

Means for Solving the Problems In order to achieve the above object, the present invention provides a method in which after screen printing is performed on a substrate to be printed, the surface to be printed has adhesiveness and has approximately the same thickness as the substrate to be printed. Screen printing is performed on a dummy substrate, then the ink on this dummy substrate is cleaned and removed, and then screen printing is performed again on another substrate to be printed.

Alternatively, a method may be adopted in which the substrates are automatically fed one after another, the dummy substrate is supplied at intervals of every several to several hundred substrates to be printed, and screen printing is performed continuously.

Therefore, according to the present invention, when removing the ink that has spread to the back of the emulsion formed on the plate, since the adhesive dummy substrate is used, it is necessary to use a rag or paper soaked in a solvent. This eliminates the generation of dirt and dust from the rag or paper, which is the case when using paper, and can prevent printing defects caused by these. Further, the paper or the film on which the adhesive layer is formed is not disposable, and the dummy substrate is reused after the printed ink is washed and removed, so printing costs can be reduced. Further, since no solvent is used when removing the ink, the solvent does not mix with the ink and does not adversely affect the ink. Furthermore, the adhesion between the ink and the adhesive dummy substrate is sufficient, and the ink that has spread behind the emulsion formed on the plate can be completely removed. Automatically supplies adhesive dummy substrates to the printing machine.

Because it can be discharged, the ink that has spread behind the emulsion formed on the plate can be removed with almost no reduction in productivity.

EXAMPLE Hereinafter, a case where an adhesive rubber is used as an adhesive dummy substrate in a screen printing method for a printed wiring board according to an embodiment of the present invention will be described with reference to FIGS. 1a, b, and c.

In Figures 1a, b, and c, l is the plate frame, 2 is the plate, 3 is the emulsion formed on the plate 2, 4 is the squeegee, and 5 is the back side of the emulsion 3 formed on the plate 2. The spinning ink, 6 is the adhesive rubber, and 7 is the stage of the printing press.

In FIG. 1a, a sticky rubber 6 is placed between the plate 2 and the stage 7 of the printing press. In Figure 1, Squeegee 4
is printed on the adhesive rubber 6 by squeezing. At this time, if the adhesive rubber is used as is, the adhesive rubber 6 is in tighter contact with the stage 7 of the printing press than with the plate 2, so even after printing, the adhesive rubber 6 is still attached to the printing press. It's on stage 7. And in Figure 1C,
After printing is completed, the plate 2 is raised and the sticky rubber 6 that is in close contact with the stage 7 of the printing machine is removed. At this time, the ink 5 that has spread to the back side of the emulsion 3 formed on the plate 2 does not remain on the emulsion 3 formed on the plate 2, but is transferred onto the adhesive rubber 6. After printing, the adhesive rubber 6 that is removed is cleaned and removed from the ink using a solvent such as 1.1.1-trichloroethane, butyl cellosolve, xylene, etc., and is reused after being sufficiently dried. By the above method, the ink 5 that has spread to the back side of the emulsion 3 formed on the plate 2
can be completely removed.

At this time, suitable materials for the adhesive rubber 6 include urethane rubber and butadiene rubber.

Also, the thickness of the adhesive rubber should be the same as the substrate to be printed on, or the thickness of the substrate to be printed plus 0.
It is necessary to have no more than three cabinets. This is because when the thickness of the adhesive rubber becomes thinner than the substrate to be printed, the pressure of the squeegee during squeegeeing becomes insufficient, and the emulsion 3 formed on the plate 2
This is because it becomes impossible to completely remove the ink 5 that has spread to the back side of the ink. On the other hand, if the thickness of the adhesive rubber exceeds the thickness of the substrate to be printed plus 0.3 m or more, the squeegee pressure during squeegeeing becomes too large and a large force is applied to the plate 2, causing the image on the plate 2 to deteriorate. This is because it may cause elongation, distortion, or plate tearing. At this time, the adhesive force of the adhesive dummy board is 100g/2
300 g/25 circles from 5 m is appropriate. The adhesive force of the adhesive dummy board is 100 g / 25 rm
If the adhesive strength is too weak, the ink 5 that has spread to the back of the emulsion 3 formed on the plate 2 cannot be completely transferred onto the adhesive dummy substrate, and the ink cannot be removed. It becomes complete. On the other hand, if the adhesive force of the adhesive dummy substrate exceeds 300 g/25 m 1M, the adhesion between the adhesive rubber 6 and the emulsion 3 formed on the plate 2 becomes too strong. The emulsion 3 formed on the plate 2 is peeled off. If the emulsion 3 formed on the plate 2 is peeled off from the plate 2, the ink will pass through areas where ink should not normally pass, resulting in printing defects.

Next, other embodiments of the present invention will be described.

FIG. 2 shows another embodiment of the present invention, in which an adhesive rubber 6 is used as an adhesive dummy substrate.
This is a case where a hard plate 8 is pasted on one side of the plate.

In this case, the total thickness of the adhesive rubber 6 and the hard board 8 needs to be between the same thickness as the printed board that is actually being printed and the thickness of the printed board plus 0.3 m. .

In this case, since the adhesive rubber 6 does not bend, the substrate to be printed is automatically fed, and after screen printing, the adhesive rubber 6 is placed in the screen printing process section with adhesive like the substrate to be printed. It becomes possible to automatically supply and discharge the adhesive rubber 6, which is a dummy substrate, to the printing machine,
There is no need to remove the adhesive rubber 6 after once lifting the plate 2, and the productivity of the automatic printing line is greatly improved.

Effects of the Invention According to the present invention, when screen printing a printed wiring board,
By screen printing on the substrate to be printed and then using an adhesive dummy substrate, the ink that has spread to the back of the emulsion formed on the plate can be transferred to the screen without generating dirt or dust. Since it can be easily and completely removed, printing quality and productivity can be greatly improved.

[Brief explanation of drawings]

FIG. 1(a) shows the state immediately before the ink that has spread to the back of the emulsion formed on the plate is removed using a dummy substrate in the screen printing method for a printed wiring board according to an embodiment of the present invention. Cross-sectional view, Figure 1Cb) is a cross-sectional view showing the state when adhesive rubber is used as a dummy substrate with adhesiveness in the same method, and Figure 1(c) is a cross-sectional view showing the state in which adhesive rubber is removed using the same method. Fig. 2 is a cross-sectional view showing the state at the time of use, and Fig. 2 shows another embodiment of the present invention in which sticky rubber is used as the sticky dummy substrate and a hard board is attached to one side of the sticky rubber. Fig. 3 is a perspective view showing the conventional method of wiping ink with a cloth soaked in a solvent to remove ink, and Fig. 4 is a cross-sectional view showing the conventional method of wiping ink with a cloth soaked in a solvent. FIG. 5 is a sectional view showing a method of transferring ink onto a film on which an adhesive layer is formed. 1... version frame, 2... version, 3...
・Emulsion, 4...Squeegee, 5...Ink, 6...Adhesive rubber, 7...Stage, 8...Hard board , 9...Printed substrate.

Claims (3)

[Claims] (1) After performing screen printing on the substrate to be printed, screen printing is performed on a dummy substrate whose printing surface is adhesive and has approximately the same thickness as the substrate to be printed, and then on this dummy substrate. A method for screen printing printed wiring boards, which comprises cleaning and removing ink, and then screen printing again onto another substrate. (2) When the substrates are automatically sequentially fed and screen printing is performed, the dummy substrate is supplied to the screen printing process section at an interval of one for every several to several hundred substrates to be printed; 2. The method of screen printing a printed wiring board according to claim 1, wherein screen printing is performed continuously. (3) The screen printing method for a printed wiring board according to claim 1, characterized in that a substrate made of urethane rubber or butadiene rubber is used as the dummy substrate.