JPH0813183A - Production of metallic mask - Google Patents

Abstract

PURPOSE:To provide a process for easily producing a metallic mask which well supplies a liquid material for printing to mask apertures by the rolling effect of the liquid material for printing at the time of printing and has the good property of the liquid material for printing to be passed and transferred from the mask apertures to the surface to be printed. CONSTITUTION:The metal mask is produced by forming a plating resist film on the surface of a conductive base material and energizing this conductive base material in a plating liquid. A material having photosensitivity (a material having a thermosetting property is equally well) is adopted for the plating resist material to be formed on the surface of the conductive base material described above. The conductive base material is subjected to a heat treatment in a method, such as IR heating, from the surface side not coated with the photosensitive plating resist between a exposure stage and developing stage. An electrodeposition layer is formed thereon after development processing and its surface is roughened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal mask suitable for printing and applying a liquid material such as cream solder to a fine soldering pad formed on a printed wiring board or the like.

[0002]

2. Description of the Related Art The following characteristics are required for current printing metal masks. (1) In order to properly fill the opening of the metal mask with the printing liquid, it is essential that the printing liquid rolls on the metal mask during squeezing. In order for the printing liquid material to roll on the metal mask, it is essential that the squeegee surface side of the metal mask has an appropriate roughness. (2) The printing liquid filled in the opening of the metal mask,
Good transfer to the substrate is required. Therefore, it is necessary that the opening diameter of the metal mask is tapered so that the surface side of the printed material is slightly wider than the squeegee surface side. In order to satisfy the above requirements (1) and (2), the current metal mask has a conductive substrate surface as a squeegee surface and a plated surface as a print surface in the manufacturing process.

That is, since the plating resist formed on the surface of the conductive base material is formed by a photographic method through an exposure / development process, the amount of light reaching the conductive base material surface side is smaller in the thickness direction. The degree of curing is low. As a result, in the subsequent developing step, the plating resist film is more easily dissolved and removed as it is closer to the surface of the conductive base material, and conversely, it is less likely to be dissolved and removed as it is further from the surface of the conductive base material. As a result, as shown in FIG. 9, the film becomes an inverted trapezoidal shape having a narrower width nearer the surface of the conductive base material and a wider width farther from the surface of the conductive base material. Therefore, in order to satisfy the requirement of (2), the conductive substrate surface is necessarily the squeegee surface and the plated surface is the print surface.

[0004]

Here, considering the requirement (1), it is necessary to form an appropriate roughness on the conductive substrate surface side of the metal mask. However, the interface between the conductive base material surface side of this metal mask and the conductive base material does not peel off during plating,
In addition, after plating, the metal mask formed must have an adhesive force that can be peeled off without applying unnecessary stress. That is, the printing liquid has a much smaller roughness than the roughness required for proper rolling during squeezing. Therefore,
After removing the metal mask from the conductive base material and removing the plating resist, the surface of the printed material surface of the metal mask and the inside of the opening are protected again by some method, and a physical or chemical treatment is applied to remove the metal mask. It is necessary to form appropriate unevenness on the squeegee surface side.

Therefore, the problem to be solved by the present invention is the incomplete supply of the printing liquid to the mask opening portion by the squeegee in the printing using the metal mask manufactured by the electroforming method. It is the poor transferability of the printing liquid from the mask opening to the printing surface. The object of the present invention is to supply the printing liquid to the mask opening by the rolling action of the printing liquid during printing, and to provide good transferability of the printing liquid from the mask opening to the surface to be printed. It is to provide a metal mask easily.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the means adopted by the present invention is to form a photosensitive plating resist (10) film on the surface of a conductive substrate (100), In the method for producing a metal mask by energizing the lever conductive substrate, the surface of the conductive substrate (100) is coated with a photosensitive plating resist (10), exposed, and then the conductive substrate ( 100) of the photosensitive plating resist is not heat-treated from the surface side, then development is performed to form the electrodeposition layer (200), and then the surface of the electrodeposition layer (200) is roughened. Is. Specifically, as the plating resist material formed on the surface of the conductive base material (100), a material having photosensitivity (which may have thermosetting property) is used, and it is used between the exposure step and the development step. In the above, heat treatment is performed from the surface of the conductive substrate (100) not covered with the photosensitive plating resist by a method such as IR heating.

[0007]

According to the manufacturing method of the present invention, the conductive substrate (100)
The surface is coated with a photosensitive plating resist (10), and then the photosensitive plating resist (10) is selectively photocured by exposing through a pattern film. At this point, the photosensitive plating resist (1
0-a) The coating has a relatively high degree of curing in the upper layer portion and a relatively low degree of curing in the lower layer portion, that is, the conductive substrate surface side. This is because the light irradiated in the exposure step is absorbed in the upper layer part of the photosensitive plating resist (10) material, and the lower the lower layer the light arrival amount is, and the light irradiated in the exposure step is the photosensitive plating resist. (10) This is because the material is slightly dispersed in the upper layer portion, and the light arrival density decreases in the lower layer.

Next, the conductive base material (100) is heat-treated from the side not covered with the photosensitive plating resist, so that the conductive base material (100) can be directly heated without heating the material of the photosensitive plating resist (10). To heat. The heat transferred to the conductive base material (100) is gradually transferred to the photosensitive plating resist (10) layer, and further advances the curing of the part where the photo-curing has progressed due to the exposure process of the photosensitive plating resist (10). Will be made.
By appropriately controlling the heating time here, the lower layer portion of the photosensitive plating resist (10), that is, the surface of the conductive substrate (100), can be treated without advancing the curing degree of the upper layer portion of the photosensitive plating resist (10). The degree of hardening on the side can also be advanced. Further, if the heating temperature is too high, it is not preferable because the photosensitive plating resist (10) also starts to cure at a portion other than the portion where photocuring has progressed by the exposure step.

Next, the uncured photosensitive plating resist (10) is removed by performing a development treatment, and the shape of the remaining photosensitive plating resist (10-a) is closer to that of the conductive substrate (100) side. The shape becomes wider, that is, a trapezoid. This is because the photosensitive plating resist (1
The shape of the part of (0) where photo-curing started is a trapezoidal shape, although the degree of hardening differs, and the lack of this degree of hardening is due to the surface of the conductive base material (100) not covered with the photosensitive plating resist. This is due to the fact that it was supplemented by heat treatment from the side.

Next, by energizing the conductive base material (100) on which the photosensitive plating resist (10-a) is formed in a plating solution, the photosensitive plating resist (1
The electrodeposition layer (200) is deposited on the portion where the (0) is dissolved and removed to form a metal mask. The shape of the opening (the portion where the photosensitive plating resist is not removed by dissolution) (220) of this metal mask has a shape in which the width becomes wider toward the conductive base material (100) side,
It becomes a so-called trapezoid. That is, the electrodeposition layer (20
0) The front side is the squeegee surface for printing, and the conductive substrate (10
0) The surface side can be used as the printing surface.
Then, the surface of the electrodeposition layer (200) is subjected to a roughening treatment to form irregularities suitable for use as a squeegee surface during printing.

Examples of the roughening treatment that can be used here include the following. (1) Electrodeposited layer (200) surface is plated with coarse precipitation particles (210)
Give. Specifically, immediately before the end of the electrodeposition layer forming the metal mask, the plating current density is increased or transferred to a plating solution with a low concentration of deposited metal ions in the plating solution, and the same plating current density as before is used. There is a method such as plating with. It is also possible to perform plating so that needle-like crystals are deposited. (2) The surface of the electrodeposition layer (200) is chemically roughened by etching to form irregularities. (3) The surface of the electrodeposition layer (200) is subjected to a dry or wet polishing treatment to be physically roughened to form irregularities. According to the method of the present invention as described above, the mask opening (210) by the rolling action of the printing liquid during printing.
Good supply of printing liquid to the mask opening (21
It is possible to easily provide a metal mask having excellent transferability of the printing liquid from the (0) to the printing surface.

[0012]

【Example】

(Example 1) Next, the present invention will be described according to manufacturing steps. (1) Stainless steel plate (SUS304) that is a conductive base material (1
The surface of (00) is polished with a buffing machine (Fig. 1). The purpose of this polishing is to improve the adhesion between the resist material formed later and the stainless steel plate. Further, not only the stainless steel plate but also other conductive base materials can be used. (2) Laminate or apply the photosensitive plating resist material (10) to the polished stainless steel plate (Fig. 2). As the photosensitive plating resist material (10), either a dry flume type or a liquid type can be used, but in the present embodiment, a dry film type (dry film manufactured by Mitsubishi Rayon: FRA-517) is used in consideration of workability. Was used. Since this dry film has a thickness of 50 μm, in this embodiment, the lamination process was repeated 4 times to obtain a desired thickness of 200 μm.

(3) A stainless steel plate (1) having a photosensitive plating resist material (10) formed by laminating a dry film
The exposed film with the desired negative pattern is vacuum-bonded to (00) and exposed by baking with an ultraviolet lamp (Fig. 3).
It was placed in a heating furnace and heated from the surface of the stainless steel plate (100) on which the photosensitive plating resist material (10) was not formed. Atmosphere temperature 90
The conditions were 10 ° C. and 10 minutes. (4) Next, development, washing with water and drying were carried out to form a desired resist material for openings (10-a) (FIG. 4). (5) Next, electroforming was performed using a nickel sulfamate / cobalt sulfamate alloy plating bath. The composition and plating conditions of the nickel sulfamate / cobalt sulfamate alloy plating bath are shown below. Nickel Sulfamate 450 ± 50 g / l Cobalt Sulfamate 15 ± 3 g / l Boric Acid 30 ± 5 g / l Nickel Chloride 5 ± 1 g / l Additive Electroform at a current density of 4 A / dm ² in the appropriate bath. By doing so, the electrodeposition layer (200) serving as a metal mask is formed on the stainless steel plate not covered with the photosensitive plating resist material (10-a). The thickness of the electrodeposited layer (200) at this point is 175 μm
The degree is (Fig. 5).

(6) Next, the current density was changed to 8 A / dm ² , and electroforming was continued until the thickness of the electrodeposited layer (200 + 210) was about 180 μm (FIG. 6). Then, the electrodeposition layer (200 + 2
10) was peeled from the stainless steel plate (FIG. 7), and the photosensitive plating resist material (10-a) was dissolved and removed to obtain a metal mask (FIG. 8). The surface roughness of the metal mask created in this way is
Ra = 0.40 μm and Rmax = 0.8 μm, which were within the target roughness range. Also, in a test of screen printing an actual solder paste, a uniform paste amount was applied from each opening.

(Example 2) Steps (1) to (5) are carried out in the same manner as in Example 1. (6) Next, electroforming was performed using another nickel sulfamate / cobalt sulfamate alloy plating bath. The composition and plating conditions of this nickel sulfamate / cobalt sulfamate alloy plating bath are shown below. Nickel sulfamate 230 ± 50 g / l Cobalt sulfamate 8 ± 3 g / l Boric acid 30 ± 5 g / l Nickel chloride 3 ± 1 g / l Additives Appropriate

In the above bath, electroforming was continued at a current density of 4 A / dm ² until the thickness of the electrodeposited layer (200 + 210) was about 180 μm. Then, the electrodeposition layer (200 + 210) was peeled off from the stainless steel plate, and the photosensitive plating resist material (10-a) portion was dissolved and removed to obtain a metal mask. The surface roughness of the metal mask thus prepared is Ra = 0.45 μ.
m, Rmax = 0.9 μm, which was within the target roughness range. Also, in a test of screen printing an actual solder paste, a uniform paste amount was applied from each opening.

(Example 3) Steps (1) to (5) are carried out in the same manner as in Example 1. (6) Next, electroforming was performed using another nickel sulfamate / cobalt sulfamate alloy plating bath. The composition and plating conditions of this nickel sulfamate / cobalt sulfamate alloy plating bath are shown below. Nickel sulfamate 300 ± 50 g / l Cobalt sulfamate 10 ± 3 g / l Boric acid 30 ± 5 g / l Nickel chloride 4 ± 1 g / l Additives Appropriate

In the above bath, electroforming was continued at a current density of 6 A / dm ² until the thickness of the electrodeposited layer (200 + 210) was about 180 μm. Then, the electrodeposition layer (200 + 210) was peeled off from the stainless steel plate, and the photosensitive plating resist material (10-a) portion was dissolved and removed to obtain a metal mask. The surface roughness of the metal mask thus created is Ra = 0.35μ.
m and Rmax = 0.7 μm, which was within the target roughness range. Also, in a test of screen printing an actual solder paste, a uniform paste amount was applied from each opening.

(Embodiment 4) Steps (1) to (5) are carried out in the same manner as in Embodiment 1. (6) Then, the surface of the electrodeposition layer (200) was physically polished.
This physical polishing is a wet polishing machine (jet scrub)
Then, a solution having a concentration of 20% of an abrasive (product name: Sakurandom # 200 manufactured by Nippon Cartridge Co., Ltd.) is used at a line speed of 1.0 m / min and a pressure of 2.0 kg / cm ² . Under this condition, the electrodeposition layer (200) is in contact with the abrasive for about 1 minute. Next, the electrodeposition layer (200) was peeled off from the stainless steel plate, and the photosensitive plating resist material (10-a) portion was dissolved and removed to obtain a metal mask. The surface roughness of the metal mask thus created is Ra = 0.45 μm, R
max = 0.9 μm, which was within the target roughness range. Also, in a test of screen printing an actual solder paste, a uniform paste amount was applied from each opening.

[0020]

EFFECTS OF THE INVENTION According to the manufacturing method of the present invention, the printing liquid material is well supplied to the mask opening due to the rolling action of the printing liquid material during printing, and the printing liquid material from the mask opening to the surface to be printed. It is possible to easily provide a metal mask having good transferability.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a first step of the present invention.

FIG. 2 is a partial cross-sectional view showing a second step of the present invention.

FIG. 3 is a partial cross-sectional view showing a third step of the present invention.

FIG. 4 is a partial sectional view showing a fourth step of the present invention.

FIG. 5 is a partial sectional view showing a fifth step of the present invention.

FIG. 6 is a partial cross-sectional view showing a sixth step of the present invention.

FIG. 7 is a partial sectional view showing a sixth step of the present invention.

FIG. 8 is a partial cross-sectional view of a metal mask obtained by the present invention.

FIG. 9 is a partial cross-sectional view showing a conventional construction method.

[Explanation of symbols]

 200 ・ ・ ・ Electrodeposition layer (metal mask) 210 ・ ・ ・ Conductive substrate (stainless steel plate) 220 ・ ・ ・ Opening

Claims (1)

[Claims] 1. A method for producing a metal mask by forming a photosensitive plating resist coating on the surface of a conductive base material and energizing the conductive base material in a plating solution. A photosensitive plating resist is coated, exposed, and then heat-treated from the surface of the conductive base material not coated with the photosensitive plating resist, followed by development treatment to form an electrodeposition layer, and then the surface of the electrodeposition layer is roughened. A method of manufacturing a metal mask, comprising: