JPH058368A - Mask for screen printing and preparation thereof - Google Patents

Abstract

PURPOSE:To enhance the abrasion resistance and printing dimensional stability of a mask for screen printing and to realize fine line printing. CONSTITUTION:A mesh holding layer 2 hard to dissolve in a developing solution and having viscoelasticity is formed to the surface of an electroforming matrix 1 and a mesh 3 having conductivity is laminated to the mesh holding layer 2 and a photoresist film 6 of a desired printing pattern is formed on the mesh 3. An electroforming metal membrane 7 is formed to the surface not covered with the photoresist film 6 of the mesh 3 and, finally, the mesh 3 and the electroforming metal membrane 7 are peeled off from the electroforming matrix 1. By this method, a mask for screen printing wherein the electroforming metal membrane 7 having a large number of opening parts 8 formed thereto in a desired printing pattern is formed to the single surface of the mesh 3 and the mesh 3 is exposed to the opening parts 8 as it is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, ICs and LSIs.
TECHNICAL FIELD The present invention relates to a screen-printing mask that is preferably used for screen-printing printed wiring and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a screen printing mask of this type, for example, as shown in FIG. 5A, a mesh 3 made of polyethylene terephthalate, stainless steel or the like is coated with a desired printing pattern of a photosensitive resin 10 or a mask. ,
As shown in FIG. 6 (B), a thin metal foil 11 such as stainless steel or nickel is arranged on the stainless steel mesh 3, both are integrally connected by electroplating, and the metal foil 11 is opened by etching to form a desired printing pattern. 12 is formed (literature unknown). According to the latter, since the print pattern is made of the metal foil 11, the chemical resistance and abrasion resistance are superior to the former print pattern of the photosensitive resin 10. Further, when the printing pattern is the photosensitive resin 10, it is pushed into the mesh 3 as shown in FIG. 5B by the squeegee printing pressure during continuous printing to change the printing thickness, or the edge 10a thereof is broken. The pattern edge 1 formed by the metal foil 11 is likely to deteriorate in printing quality.
1a does not have such a problem, and since all of them are integrally formed of a metal body, the dimensional change due to the printing pressure of the squeegee is extremely small, and relatively accurate sharp printing can be achieved. .

[0003]

However, in the screen printing mask in which the printing pattern is formed by the metal foil 11 as shown in FIG. 6B, the metal foil 11 is not formed as shown in FIG. 6A. Since it is integrally connected to the stainless steel mesh 3 by electroplating, as shown in FIG. 6B, the wire of the mesh 3 exposed in the opening 12 of the print pattern is plated with 13 to increase the wire diameter. The aperture ratio is reduced by the amount of the plating 13 attached, the passage of the ink paste becomes poor, and it is difficult to adjust the total thickness of the mask. Also, since it is single-sided etching, the aspect ratio (total thickness / opening width) cannot be made high, patterning (line width) is limited, and it is difficult to obtain a mask cross-sectional shape that is right angle, and the aperture ratio is reduced. Was.

The present invention has been made to solve these problems, and by electroforming the metal in the screen printing mask in which the print pattern formed on one surface of the mesh is made of metal, as described above. Wear resistance,
It is possible to secure printing dimensional stability, the mask cross section rises vertically, the passability of ink and paste (dischargeability) can be improved with a high aperture ratio, and fine line printing is possible. An object of the present invention is to provide a screen printing mask whose thickness can be easily adjusted, and a manufacturing method thereof.

[0005]

As shown in FIG. 1, a screen printing mask of the present invention is an electroformed metal thin film having a large number of openings 8 patterned into a desired printing pattern by electroforming. 7 is formed on one side of the mesh 3 and the mesh 3 is exposed in the opening 8 as the cloth.

Further, according to the present invention, when manufacturing such a mask for screen printing, as shown in FIGS. 2 (A) to 2 (G), the manufacturing process is first performed on the surface of the electroformed mold 1. A mesh holding layer 2 that is sparingly soluble and has viscoelasticity in a photoresist film forming developer described later is formed so as to be peelable. Then, a conductive mesh 3 is arranged on the mesh holding layer 2. Next, a photoresist 4 is arranged on the mesh 3, and then a print pattern film 5 is placed on the photoresist 4, baked and developed to form a photoresist film 6 having a print pattern. At this time, the mesh holding layer 2 is not melted by the developing solution and is left attached to the surface of the electroformed mother die 1 to keep holding the entire lower surface of the mesh 3. Then, an electroformed metal thin film 7 is formed on the surface of the mesh 3 not covered with the photoresist film 6 by electroforming. Finally, the mesh 3 and the electroformed metal thin film 7 are separated from the electroformed master 1.

[0007]

Since the mesh 3 exposed in the opening 8 of the screen printing mask 9 is covered with the photoresist film 6 during electroforming, the electroformed metal is covered with the mesh 3 in the opening 8.
Since the wire diameter of the mesh 3 does not change and the cloth 3 remains unchanged, the aperture ratio of the mask increases.

The total thickness of the mask can be easily adjusted by changing the thickness of the photoresist film 6 and adjusting the electroforming height.

The viscoelastic mesh-holding layer 2 can be adhered to the surface of the electroformed mold 1 without floating, and the mesh-holding layer 2 can be kept in close contact with the mesh 3 without moving. To be done.

Since the photoresist film 6 adheres integrally to the mesh holding layer 2 with the mesh 3 interposed, the photoresist film 6 does not float or peel off on the mesh 3 and the electrodeposited metal is It can be well prevented from wrapping around the back surface of the photoresist film 6.

Since the mesh holding layer 2 has flatness, the flatness of the electroformed metal thin film 7 at the time of electroforming is increased.

[0012]

According to the present invention, since the mask material comprises the mesh 3 and the electroformed metal thin film 7, it is excellent in abrasion resistance and printing dimensional stability.

Since the mesh 3 exposed in the opening 8 is covered with the photoresist film 6 and electroforming is performed, a mask having a high aperture ratio can be obtained, and the ink paste can pass smoothly, and the screen with high accuracy can be obtained. Enables printing.

Further, since the total thickness of the mask can be easily adjusted by changing the thickness of the photoresist film 6, various kinds of screen printing masks having different thicknesses can be easily obtained.

Since a high aspect ratio can be obtained by electroforming, a fine patterning (line width) can be obtained, and a mask cross-sectional shape can be obtained at a right angle, a liquid crystal display which is required to have high dimensional accuracy. It is possible to realize fine line printing such as electrodes for printing and printed wiring for hybrid IC.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 3, the screen printing mask 9 of the present invention has an electroformed metal thin film 7 having a large number of openings 8 patterned by electroforming in a desired print pattern on one side of the mesh 3. The mesh 3 is exposed in the opening 8 of the electroformed metal thin film 7 as the cloth. In the screen printing, the mask 9 is attached to the screen frame, the surface side of the electroformed metal thin film 7 is brought into close contact with a printing object such as a wiring board, and the ink paste is placed on the surface side of the mesh 3 and a squeegee is applied to open it. It is ejected from the portion 8 and adhered to the printing object.

FIGS. 2A to 2H show process charts for obtaining such a screen printing mask by electroforming. When electroforming a screen printing mask, first,
As shown in FIG. 2A, a stainless electroformed mold 1
The mesh holding layer 2 (25 to 50 μm thick) is releasably laminated or applied on the surface of the. The mesh holding layer 2 is poorly soluble in the developer used in the subsequent photoresist film forming step, and has good adhesion to the surface of the electroforming mold 1 and to the mesh 3 described later. A material having both excellent viscosity and elasticity, for example, laminated with a solvent type dry film resist such as PHT-142F manufactured by Hitachi Chemical Co., Ltd., or OP-2 manufactured by Tokyo Ohka Kogyo Co., Ltd. A liquid photoresist such as the resist RS is applied and dried.

Then, as shown in FIG. 2B, a stainless mesh 3 (20 μm) is formed on the mesh holding layer 2.
Laminate # 325 with a wire diameter or # 400 with a 20 μm wire diameter. This mesh 3 needs to be made of a conductive material so that it also serves as an electrode (cathode) during electroforming, but in addition to stainless steel mesh, for example, nickel electroformed one or polyethylene terephthalate, etc. For example, a synthetic fiber mesh plated with nickel may be used.

Then, as shown in FIG. 2C, an alkali type photoresist 4 (thickness: 50 to 75 μm) dissolved in an alkali developing solution is laminated or applied on the mesh 3. As the photoresist 4, for example, Dialon 307 manufactured by Mitsubishi Rayon Co., Ltd. or 301 manufactured by Nippon Alpha Co., Ltd. is used. At this time, since the mesh holding layer 2 is laid under the mesh 3,
It is possible to press the mesh 3 against the mesh holding layer 2 with the photoresist 4 so that the mesh 3 is well adhered. However, when the material of the mesh holding layer 2 is not a photoresist and another material is selected, the photoresist 4 is a solvent type photoresist, for example, OP-2 resist RS manufactured by Tokyo Ohka Kogyo Co., Ltd. Etc. can also be used.

Next, as shown in FIG. 2 (D), a desired screen printing mask pattern film (negative type) 5 is brought into close contact with the photoresist 4, and each process of baking, developing and drying is performed. Then, a photoresist film 6 having a desired pattern is formed as shown in FIG. At this time, since the mesh holding layer 2 is hardly soluble in the developing solution, it is left without being removed from the electroforming mold 1. This is,
As a comparative example, as shown in FIG. 7A, when the mesh 3 is directly laminated on the surface of the electroformed mold 1 and the photoresist film 6 is formed thereon, a part 6a of the photoresist film 6 is The mesh 3 causes a problem that it is easily floated or peeled off from the surface of the electroforming mold 1. However, in this embodiment, since the mesh holding layer 2 is laid and the mesh 3 is placed thereon, such a case occurs. There is no problem, and the photoresist film 6 can be formed well.

Next, when the electroforming mother die 1 is immersed in an electrodeposition bath, for example, a nickel sulfamate bath to perform nickel electroforming, it is covered with a photoresist film 6 of a mesh 3 as shown in FIG. An electroformed metal thin film 7 is formed on the surface not covered. At the time of this electroforming, as shown in FIG. 4, the mesh 3 having conductivity is used as an electrically conductive material to connect the electroconductive holder 14 to the electrode (cathode) 15.
Will grow from. Since the photoresist film 6 is in close contact with the mesh holding layer 2 during this electroforming, nickel does not wrap around to the back side of the photoresist film 6 (where the opening 8 is formed). The mask cross-sectional shape can be obtained. As shown in FIG. 7 (B), when the part 6a of the photoresist film 6 is floated or peeled off from the surface of the electroforming mold 1 by the mesh 3 as in the comparative example described above. Nickel wraps around the floating or peeling portion, a thin piece E is formed on the electroformed metal thin film 7 as shown in FIG. 7C, the aperture ratio changes, and the aspect ratio decreases. Instead of nickel electroforming, nickel-cobalt alloy may be used for electroforming.

After electroforming, the surface of the electroformed metal thin film 7 is polished to a smooth surface so that a good contact state with the object to be printed can be obtained. At this time, since the photoresist film 6 is attached to the electroformed mold 1 with the mesh holding layer 2 having viscoelasticity interposed, it is easy to polish and high flatness can be obtained. As shown in FIG. 7 (A), this is the mesh 3 directly on the surface of the electroformed mold 1.
When laminating is performed, the mesh 3 easily slides on the surface of the electroformed mold 1 by the polishing pressure at the time of polishing, making it difficult to polish and making it difficult to obtain flatness.

After polishing, the photoresist film 6 is removed with a sodium hydroxide solution or a commercially available photoresist removing solution as shown in FIG. 2G, and then the mesh holding layer is provided as shown in FIG. 2H. 2 is separated from the electroformed metal mold 1 together with the electroformed metal thin film 7 and the mesh 3.

After peeling, the mesh holding layer 2 is removed. For example, when the mesh holding layer 2 is a solvent type resist, it can be dissolved and removed with methylene chloride or the like. Thus, a product of the screen printing mask 9 in which the electroformed metal thin film 7 having a large number of openings 8 formed in a desired printing pattern as shown in FIGS. 1 and 3 is formed on one side of the mesh 3 is obtained. You can

The material of the mesh holding layer 2 is
Any adhesive may be used as long as it is not exposed to the developer for forming the photoresist film, and an adhesive sheet such as a rubber adhesive tape may be used in addition to the solvent type resist as in the above embodiment. When an adhesive sheet is used as the mesh holding layer 2, the material of the photoresist film 6 may be either an alkali type resist or a solvent type resist.

[Brief description of drawings]

FIG. 1 is a perspective view of a part of a screen printing mask.

FIG. 2 is a manufacturing process diagram.

FIG. 3 is a partial cross-sectional view of a screen printing mask.

FIG. 4 is a front view showing a mother die during electroforming.

FIG. 5 is a partial cross-sectional view of a conventional screen printing mask.

FIG. 6 is a manufacturing process diagram of another conventional screen printing mask.

FIG. 7 is a manufacturing process diagram of a screen printing mask showing a comparative example.

[Explanation of symbols]

1 Electroforming mother die 2 mesh retention layer 3 mesh 4 photoresist 5 Printing pattern film 6 Photoresist film 7 Electroformed metal thin film 8 openings 9 Screen printing mask

Claims (2)

[Claims] 1. An electroformed metal thin film 7 having a large number of openings 8 patterned into a desired printing pattern by electroforming is formed on one side of a mesh 3, and the mesh 3 is formed in the openings 8 of a cloth. A mask for screen printing, which is exposed as it is. 2. A step of removably forming a mesh holding layer 2 having viscoelasticity on the surface of an electroformed mold 1, a step of disposing a conductive mesh 3 on the mesh holding layer 2, and a mesh. The photoresist 4 of the mesh 3 and the photoresist 4 is placed on the photoresist 3 and then the printed pattern film 5 is placed on the photoresist 4 and baked and developed to form a photoresist film 6 of the printed pattern. The step of forming an electroformed metal thin film 7 on the surface not covered with the film 6 by electroforming, and the step of peeling the mesh 3 and the electroformed metal thin film 7 from the electroformed mother die 1, the mesh holding layer 2 Is a method of manufacturing a mask for screen printing, which is made of a material that is hardly soluble in a developing solution for forming a photoresist film.