JP2001113850A - Screen printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print ink from a printing plate in a method of forming a fine pattern using a printing plate or applying an ink to a projection (a rib-shaped partition wall of a plasma display) using a solid printing plate. Reduce the amount. SOLUTION: By performing screen printing using a printing plate having a plurality of overlapping screen mesh structures, a discharge amount from a screen mesh opening on a printing medium side is controlled to form a desired printing ink application shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing plate used in a printing process, and more particularly to fine pattern printing.

[0002]

2. Description of the Related Art In a substrate for a display device such as a substrate for a plasma display panel or an anode substrate of a fluorescent display tube, or a substrate for an electronic device such as a thick film wiring substrate or an image sensor, a film having a desired function is formed on the substrate. For example, a rib-like partition, a conductor wiring, a resistor, and the like are provided. For forming these films, for example, a screen printing plate on which a predetermined pattern is drawn is used. The printing is performed using a thick-film screen printing method in which a printing ink arranged on a screen is scanned in one direction to apply the printing ink to the surface of a substrate, which is a printing object.

The configuration of a screen printing plate used in the above-described screen printing method will be described. For example, a screen in which a predetermined pattern is formed on a rectangular frame is attached with a predetermined tension. There is a method of attaching the screen, a method of forming the screen for pattern formation from itself and attaching directly, or a method of joining another screen around the screen to be patterned and attaching it to the frame,
The former is called the direct upholstered version (normal version), and the latter is called the combination upholstered version. The screen may be formed of a mesh woven from a stainless steel, amorphous, polyester, or tetron based wire, and a pattern formed by exposing and developing a photosensitive emulsion, or a metal sheet. And a metal mask for pattern formation by etching or electroforming. In addition, in the above-mentioned wire rod,
As a reinforcement treatment for increasing the tensile strength, for example, additional processing such as pressing (calender) or plating (resist dies) is performed as necessary.

[0004]

With respect to screen printing, generally, a printing screen is arranged at a predetermined distance (plate gap) from a printing substrate, and the printing screen is temporarily moved according to the pressing force of a squeegee when the printing ink is scanned. Is brought into contact with the printing medium. At this time, the printing ink receives a force to be rotated on the screen by the squeegee, and at the same time, a part of the ink passes through the mesh opening and is applied to the printing medium. At this time, the amount of printing ink applied to the printing medium is determined by the shape of the mesh and the thickness of the embedded emulsion.

When a high-definition pattern is formed on a printing medium, an excessive amount of the printing ink applied to a desired pattern causes ink dripping or bleeding after application (FIG. 1). In addition, the irregularities caused by the screen mesh wire and the opening may be left on the pattern after application (FIG. 2). Considering the shape of the printing ink after being applied to the substrate, it is necessary to reduce the amount of application as the pattern becomes finer (FIG. 3).

For example, in a plasma display panel, a so-called front substrate on which a pair of discharge electrodes, a dielectric layer and a protective film are formed, an address electrode for selecting a lighting cell, a dielectric layer, and radiation are emitted by the discharge. And a so-called back substrate on which a phosphor that emits light upon receiving ultraviolet light is formed, and the peripheral portions of both substrates are sealed via a rib-shaped partition wall that regulates a discharge region. As one method of forming the ribs, there is a screen printing method in which, for example, a partition printing paste is laminated and printed on a substrate using a thick film screen printing plate on which a predetermined pattern is drawn.

Next, a conceptual diagram of a rib-like partition formed by a screen printing method is shown (FIG. 4). In addition, a solid screen plate can be used for the lamination printing of the rib-shaped partition upper layer. In laminating printing, it is conceivable to increase the thickness of the lamination at one time in order to reduce the number of times of printing, but the partition wall formed by this method has the top opening shape with the mesh opening of the screen plate used for laminating printing. Irregularities resulting from the wire material occur (FIG. 5). If this unevenness is large, it causes noise due to crosstalk between adjacent cells during discharge light emission and poor contact between the counter substrate and the top of the partition. For this reason, it is desirable to reduce the film thickness laminated at a time in lamination printing in the upper layer part of the partition wall, so as to reduce unevenness generated at the top part of the partition wall.

As a method for solving the above-mentioned problems of crosstalk and noise, a structure in which opposing substrates are joined to each other via a partition has been proposed. An adhesive layer for the purpose of bonding to the opposing substrate is formed on the top of the rib-shaped partition formed by various methods, and the front substrate and the back substrate are joined via the rib-shaped partition and the adhesive layer. (Fig. 6).

A screen printing method is one of the methods for forming the adhesive layer. The printing screen plate used in this method may have a desired pattern formed thereon or may be a solid screen plate. Since this adhesive layer is spread out at the time of bonding with the counter substrate, if the layer thickness is large, the excessive adhesive material spread out covers the opening serving as a light extraction port during discharge light emission, and the opening area is reduced. (FIG. 7). This reduces the brightness of the plasma display panel. For this reason, the thickness of the adhesive layer cannot be formed beyond the minimum required amount of adhesion that contributes to the bonding with the counter substrate.

[0010] Further, unevenness of the thickness of the adhesive layer caused by the screen mesh opening and the wire also causes variation in the bonding width after the bonding of the opposing substrate (FIG. 8). For this reason, it is necessary to reduce the above-mentioned unevenness, and it is desirable to reduce the applied film thickness of the adhesive material.

Furthermore, unnecessary printing ink adheres to the side wall of the partition wall due to the printing ink for bonding discharged from the mesh opening in a portion not in contact with the top of the partition wall. Unnecessary adhesion of the printing ink to the side wall can be reduced (FIG. 9).

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to form fine lines by reducing the amount of applied ink when forming a high-definition pattern. An object of the present invention is to reduce the amount of printing ink applied to an upper layer of a protrusion such as a rib-shaped partition formed and the amount of ejection from an opening.

[0013]

In order to solve the above-mentioned problems, the following screen plate structure is proposed. This is a mesh in which wires having an elliptical cross section are woven (FIG. 10). The printing ink is placed on such a screen plate. In this state, the paste is scanned in one direction by a squeegee.Compared to the currently used mesh consisting of wires having a line cross-section on a circle, the printing ink reaches the printing material at the mesh opening. The passing distance before the movement increases. For this reason, discharge of the printing ink from the mesh opening can be suppressed by resistance of the printing ink from the wire constituting the mesh.

Further, a printing plate structure capable of obtaining the same effect as the above-described mesh structure will be described. A shape in which a plurality of meshes are stacked is configured (FIG. 11). The distance that the printing ink arranged on the upper part of the screen plate passes through the mesh opening to the printing material side is increased, and the amount of ink discharged from the opening is reduced because the presence of the wire of the overlapping mesh suppresses the ink from passing through. be able to.

Further, when screen printing is performed on the top of a projection such as a rib-shaped partition, the unevenness of the ink applied to the top of the partition due to a decrease in the discharge amount from the opening on the side of the printing material can be reduced (FIG. 12). The effect of suppressing ink adhesion to the side wall and ink dripping can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A printing ink composition is changed to reduce the amount of printing ink discharged from a screen printing plate,
If the rheology is changed in the direction of higher viscosity, the printing ink cannot rotate on the screen due to the force received from the squeegee etc. during printing, causing unevenness in the discharge from the printing screen plate mesh opening and causing blurring etc. Becomes In addition, there is also a problem that separation of the printing plate becomes worse due to high viscosity. However, if the discharge amount can be controlled by using a plurality of screen meshes, uniform printing can be performed with the current printing ink without using an ink having the above-mentioned rheological characteristics inappropriate for printability. And the discharge amount can be controlled.

The structure of a screen printing plate in which a plurality of meshes are bonded will be described below.

First, there are roughly two types of structures.

In the first type, a plurality of screen meshes are attached to one frame (FIG. 13), and in the second type, one screen mesh is attached to one frame ( FIG. 14) forms one printing screen plate by fixing the frames.

When a plurality of screen meshes are attached to a single frame, the strength of the frame must be higher than that of existing ones because the tension of all the meshes is applied to the single frame. However, since the positions of the screen meshes are always kept constant, the stability of the printing plate can be ensured.

In the case of a printing plate in which all the frames to which one screen mesh is attached are fixed, the frame itself as a printing plate becomes larger than the current one, but it is necessary to fix each frame. Has the advantage that a screen mesh to be combined can be selected according to the desired printing performance.

Next, features of the screen mesh to be combined will be described.

By using different screen mesh wire diameters and opening areas for different screen meshes, it is possible to control the discharge amount more finely (FIG. 15).

Also, if the overlapping screen meshes are attached to the frame in such a manner as to give an angle to each other,
Since the relative positions of the openings and the wire rods of the respective overlapping meshes are dispersed and spread, an effect of dispersing the deviation of the printing ink ejection amount from the openings can be obtained (FIG. 16).

Further, it is also possible to use a combination of different materials of the wire constituting the screen mesh depending on the desired printability.

The above-mentioned meshes may be all joined together by a method such as plating in an overlapping state (FIG. 17). By joining, reproducibility of screen printing can be improved.

Next, the structure of a screen printing plate for pattern printing will be described below.

An emulsion made of a resin having solvent resistance is embedded in a printing screen mesh, and a pattern is formed by a method such as exposure and development (FIG. 18A). After embedding all at once into a plurality of screen meshes attached to one frame, the pattern may be formed by a single exposure and development. By doing so, the relative positions of the overlapping screen meshes can be determined to some extent by the embedding emulsion, and the effect of pattern reproducibility during printing can be obtained.

Further, a pattern may be formed only on one of the overlapping screen meshes on the side in contact with the printing material.

With such a screen printing plate structure, it is not necessary to form a pattern on the screen mesh that does not directly contact the printing substrate, and the cost can be reduced (FIG. 18B).

Further, since no pattern is formed, it is possible to control and adjust a desired discharge property only by replacing the screen mesh.

The form of the screen printing plate of the present invention at the time of printing will be described below.

FIG. 19 shows a state in which the screen printing plate of the present invention is attached to a printing press. This printing press may be manual or automatic.

First, a case where a fine pattern is formed on a substrate will be described. The printing ink is placed on the uppermost screen mesh of the plurality of superimposed screen meshes on the side that does not contact the printing medium. In order to apply the printing ink in a uniform amount to the substrate, the printing ink is spread and spread so as to entirely cover the pattern with a scraper. At this time, the printing ink is embedded in a pattern formed by the emulsion and filled between the meshes. Thereafter, the screen printing plate is pressed by a squeegee so as to be pressed against the printing material, and the printing ink filled in the pattern is discharged to the printing material side by scanning over the pattern at an appropriate speed, and the excess printing ink is transferred to the uppermost portion. While being rotated on the screen (FIG. 20).

The printing ink filled in the pattern is ejected toward the printing object under the force applied by the scanning of the squeegee, and the mesh wire in the printing ink functions to hinder the ejection movement. Due to the structure in which a plurality of meshes are bonded together, this force acts greatly, and only a part of the filled printing ink is applied to the substrate to be printed without being applied all (FIG. 21).

In a high-definition pattern, a force that hinders the ejection of the printing ink acts greatly. In this way, the amount of applied printing ink is reduced. The ink that has not been ejected remains in the pattern of the printing screen plate, but continuous printing can be performed by refilling the printing ink with a scraper before the next printing. If you want to discharge the filled printing ink, slow down the squeegee scanning speed or reduce the angle of the squeegee with respect to the printing material to print the filled printing ink on the printing material. Can be.

Next, a case where a layer having a small thickness is formed on the top of a projection will be described by taking a rib-like partition formed on a plasma display panel as an example.

The printing screen plate used may be a solid screen, and in the following case, the case where the solid screen plate is used will be described (FIG. 2).
2). FIG. 22 shows a schematic diagram thereof. As in the case of the fine pattern formation described above, the printing ink is spread and filled between the screen meshes made of wire by the scraper. The screen mesh is pressed against the top of the partition, which is the printing material, by the squeegee and pressed. The printing ink filled between the meshes is discharged from an opening on the side of the printing material by a squeegee scanning over the printing ink. Further, the ejection of the filled ink may be promoted by using a roller instead of the squeegee (FIG. 23). At the opening in contact with the top of the partition wall, a force acts in the direction in which the printing ink is ejected from the opening by squeegeeing, but since the structure in which a plurality of meshes are overlapped, the wire rod in the printing ink is With the effect of preventing ejection,
Only a part of the filled printing ink is applied to the top of the partition wall, so that the printing film thickness can be reduced. For this reason, the unevenness of the formed printing layer can be reduced. Also, for the part not in contact with the partition top,
When the current printing screen plate is used, unnecessary printing ink adheres to the side wall of the partition wall as shown in FIG. This unnecessary printing ink may be seen to drip on the side wall. However, in the case of using the superimposed screen mesh according to the present invention, the ejection amount itself can be reduced for the above-described reason. Therefore, as shown in FIG. Can be reduced, and the dripping of ink on the side wall can be reduced.

[0039]

As described above, according to the present invention, it is possible to realize fine line pattern printing with less irregularities due to the mesh of the printing screen plate and less dripping and bleeding. Further, in the printing on the rib partition wall top portion, the film thickness is small, it is possible to form a printing layer of a uniform shape with small unevenness,
Further, unnecessary adhesion and dripping of the printing ink to the side wall can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing conventional fine line patterning.

FIG. 2 is a perspective view showing conventional fine line patterning.

FIG. 3 is a conceptual diagram when the thickness of the applied ink is reduced.

FIG. 4 is a cross-sectional view of a laminated rib-shaped partition formed by screen printing.

FIG. 5 is a perspective view of a laminated rib-shaped partition formed by screen printing.

FIG. 6 is a conceptual diagram in which two opposing substrates are joined by an adhesive member via a partition.

FIG. 7 is a sectional view showing the spread of the adhesive member.

FIG. 8 is a conceptual diagram showing a variation in an adhesive width.

FIG. 9 is a conceptual diagram showing adhesion of an adhesive member to a side wall when a conventional printing plate is used.

FIG. 10 is a sectional view showing a mesh made of a wire having an elliptical cross section;

FIG. 11 is a diagram showing a screen mesh having a structure in which a plurality of meshes (two in this example) are superimposed.

FIG. 12 is a conceptual diagram showing adhesion of an adhesive member to a side wall when a superposed mesh is used.

FIG. 13 is a diagram (cross-sectional view) showing a screen printing plate structure when a plurality of meshes are pasted on one frame.

FIG. 14 is a diagram (cross-sectional view) showing a screen printing plate structure when a plurality of meshes are attached to a frame body and the frame bodies are fixed to each other.

FIG. 15 is a conceptual diagram of a case where a plurality of meshes have a structure in which the wire diameter and the opening area are different.

FIG. 16 is a conceptual diagram when a bonding angle of each of a plurality of meshes is different.

FIG. 17 is a conceptual diagram when a plurality of meshes are joined to each other by a joining material.

18A is a conceptual diagram when an emulsion is embedded in a superimposed mesh and a pattern is drawn. FIG. 18B is a conceptual diagram when an emulsion is embedded in a superimposed mesh and a pattern is drawn.

FIG. 19 is a perspective view of a conceptual diagram of screen printing.

FIG. 20 is a sectional view of a conceptual diagram of screen printing.

FIG. 21 is a cross-sectional view of a conceptual diagram of patterning printing when a screen printing plate composed of superimposed meshes is used.

FIG. 22 is a conceptual diagram (cross-sectional view) of printing on the top of a partition wall when a screen printing plate composed of superposed meshes is used.

FIG. 23 is a conceptual diagram (perspective view) of printing using a roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mesh wire 2 Emulsion 3 Substrate to be printed 4 Printing ink 5 Rib-shaped partition wall 6 Adhesive member 7 Mesh 8 Frame 9 Joining material 10 Squeegee 11 Roller

Continuation of the front page (72) Inventor Yoshiki Sasaki 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 2C035 AA06 FD01 FE01 2H096 AA19 2H114 AB05 BA01 DA76 EA02 EA04 GA11 5E343 AA02 DD03 FF13 GG20

Claims (12)

[Claims] 1. A printing plate comprising a mesh made of a wire having an elliptical cross-sectional shape. 2. A printing plate, wherein at least two or more meshes are overlapped. 3. The printing plate according to claim 2, wherein the sizes of the opening areas of the overlapping meshes are different. 4. The printing plate according to claim 2, wherein the diameters of the respective line segments of the overlapping meshes are different. 5. The printing plate according to claim 2, wherein each of the overlapping meshes has a different tension. 6. The printing plate according to claim 2, wherein each of the overlapping mesh line segments has an angle with each other. 7. The printing plate according to claim 2, wherein the overlapping meshes are joined together. 8. The printing plate according to claim 2, wherein a pattern is drawn by embedding an emulsion made of resin in all the overlapping meshes. 9. The printing plate according to claim 8, wherein a pattern formed by embedding a resin emulsion is drawn only on the mesh in contact with the printing material. 10. The printing plate according to claim 8, wherein the same pattern is formed in all the meshes by embedding a resin emulsion. 11. The printing plate according to claim 2, wherein the printing ink is arranged on the mesh on the side not in contact with the printing material, and the ink is discharged by squeegeeing the mesh. 12. The printing plate according to claim 2, wherein the printing ink is filled in advance in the openings of the mesh, and the ink is ejected by pressing the mesh on the side not in contact with the printing object with a roller.