JP2001236882A - Manufacturing method for shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To offer a manufacturing method for a shadow mask having penetrating holes on the surrounding skirt of the screen part, capable of making periphery of both screen part and skirt with a high accuracy and in a desired shape. SOLUTION: This manufacturing method for a shadow mask, comprising the screen with plural penetrating parts and the surrounding skirt with perforated holes, and having the minimum manufacturing processes for forming a resist film on a thin metal plate, etching the part of the thin metal plate exposing on the openings of the resist film and stripping the resist. A dummy pattern is additionally formed to restrain the contact of the etching liquid for the thin metal plate surface with the inside of the openings on the resist film in the penetrating holes of the skirt.

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 shadow mask to be incorporated in a color picture tube or the like.
In particular, the present invention relates to a method of manufacturing a shadow mask in which a through hole is formed in a skirt portion on the outer periphery of an image surface portion.

[0002]

2. Description of the Related Art A shadow mask incorporated in a color picture tube or the like is generally manufactured by using a photo-etching method. Hereinafter, an example of a method for manufacturing a shadow mask using a photoetching method will be briefly described. First, the surface of a thin metal plate made of iron or an iron alloy is cleaned and leveled. Next, photosensitive resin (photoresist) is applied and dried on both surfaces of the metal thin plate 51 to form a photosensitive layer 52 (see FIG. 5A).

[0005] Next, the photosensitive layer 52 is subjected to pattern exposure through a pattern exposure mask having a predetermined light-shielding pattern (in most cases, two masks on the front and back sides).
2, a resist layer 53 having an opening 54 exposing the surface of the metal sheet 51 is formed according to a predetermined pattern. In many cases, the opening 54a for the small hole pattern is formed on one surface of the thin metal plate, and the opening 54b for the large hole pattern is formed on the other surface (FIG. 5).
(B)).

Next, the first stage etching is performed from both sides of the metal sheet 51. It is common to use a ferric chloride solution as an etching solution. The first-stage etching dissolves and removes the thin metal sheet portion exposed from the opening 54 formed in the resist layer 53. In the method of manufacturing a shadow mask using an etching prevention layer (varnish layer) described later, at the time of the first stage etching, the small hole recess 55 is formed on one surface of the metal thin plate, and the large hole recess is formed on the other surface. Recess 56
It is important to stop the etching halfway so that is formed (see FIG. 5C).

[0005] Next, after applying a resin liquid by roller coating, gravure coating or the like, the resin liquid is dried and cured to form an etching prevention layer 57. In many cases,
The etching prevention layer 57 fills the small hole recess 55,
It is formed on the formation surface side of the small hole concave portion (see FIG. 5D). Next, the second stage etching is performed on the metal sheet 51. The second-stage etching enlarges the large-hole concave portion, and forms a penetrating portion penetrating the small-hole concave portion 55 (see FIG. 5E). Next, the resist layer 53 is formed using an alkaline aqueous solution or the like.
After the etching prevention layer 57 is removed, the metal thin plate is cut, unnecessary metal thin plate portions are removed, and the like, and a shadow mask 300 is obtained (see FIG. 5F).

In the above-described method for manufacturing a shadow mask,
Although the method of forming the etching prevention layer and forming the penetrating portion by two-stage etching has been described, when the thickness of the thin metal plate is small, one step is performed without forming the etching prevention layer.
A desired penetration may be formed by stepwise etching. In any case, in manufacturing a shadow mask using a photoetching method, a resist layer forming step, an etching step using an etchant, and a step of removing a resist layer or the like can be said to be essential steps.

FIG. 4 schematically shows a shadow mask 200 manufactured by using a photo-etching method. The shadow mask 200 has an image in which a plurality of through-holes or through-holes are formed in a predetermined arrangement and pattern shape for correctly guiding an electron beam emitted from an electron gun to a fluorescent screen when incorporated in a color picture tube or the like. The main portion is constituted by the surface portion 41 and the skirt portion 42 on the outer periphery of the image surface portion 41. In the following description, a through hole or a through line formed in the image surface portion 41 is referred to as a through portion 43. The skirt portion 42 is a part that is pre-pressed in accordance with the shape of the color picture tube before being incorporated into the color picture tube.

In recent years, as represented by a color television,
As the display screen is required to be large, the area of a shadow mask incorporated in a color picture tube is also increasing. In a shadow mask having a large area, the image surface portion naturally has a large area, and the skirt portion also has a large area. That is, the length and width of the skirt portion are increased.

As described above, before the shadow mask is incorporated into the color picture tube, press molding is performed on the skirt portion in advance. However, when press molding is performed on a shadow mask having a large area, press molding is performed on a shadow mask having a small area. It is necessary to make the press pressure higher than when performing. For this reason, in a shadow mask having a large area, deformation defects are likely to occur due to the pressure during press molding.

As means for preventing such a problem, FIG.
As shown in FIG. 3, a skirt portion 32 is formed at the same time when a penetration portion 33 for passing an electron beam is formed in the image surface portion 31 at the time of etching.
For example, a method has been proposed in which a through hole 34 having a rectangular shape or the like is formed, and the through hole 34 is deformed during press molding to reduce external pressure applied to the shadow mask and prevent deformation of the shadow mask.

However, the shape (the size in plan view) of the through hole 34 formed in the skirt portion 32 is much larger than the through portion 33 formed in the image surface portion 31. For this reason, as shown in FIG. 2, the size of the opening formed in the resist layer 23 provided on the thin metal plate prior to etching and the size of the through-hole opening 28 formed in the skirt portion are not limited to the size of the image surface portion. It is larger than the through-hole opening 24 to be provided. Here, it can be said that the etching conditions for the metal thin plate are set so as to accurately form a fine penetration portion for passing an electron beam. Therefore, at the time of etching, the etching solution excessively contacts the thin metal plate portion exposed from the through-hole opening portion 28 of the skirt portion formed in the resist layer 23, and the etching proceeds excessively. There has been a problem that the metal sheet portion under the layer is excessively etched (that is, the through hole becomes large), and a through hole having a desired shape cannot be obtained.

Conventionally, there has been known a method of covering a through-hole portion of a skirt portion with a film-like sheet as a means for forming a desired size and shape of a through-hole of the skirt portion formed by etching. That is, before the second etching of the metal thin plate, the opening portion for the skirt portion through hole of the resist layer on one surface side (for example, the surface side on which the small hole concave portion is formed) of the metal thin plate is formed into a film shape. This is a method in which the sheet is covered with a sheet so as not to be exposed to an etching solution, and excessive etching is not performed on the through-hole portion of the skirt portion during the second etching. However, the method of covering the through-hole portion with a film-like sheet prior to etching increases the cost of purchasing the sheet, increases the production cost of the shadow mask, and adds an extra step of sticking and peeling the sheet. However, it was not desirable because the production efficiency of the shadow mask was lowered.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. That is, an object of the present invention is to form a through-hole in an image surface portion and a through-hole in a skirt portion in a desired shape with high accuracy even in a shadow mask in which a through hole is formed in a skirt portion on an outer periphery of an image surface portion. It is an object of the present invention to provide a method of manufacturing a shadow mask that can perform the method.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. In the present invention, a step of forming a resist film having an opening exposing the surface of a thin metal plate on a thin metal plate; An image surface portion on which a plurality of through-holes for electron beam transmission are formed, the method including at least a step of dissolving and removing a metal sheet portion exposed from an opening of a resist film with an etching solution, and a step of removing the resist film; And a method of manufacturing a shadow mask comprising a skirt portion having a through hole formed on the outer periphery of an image surface portion, wherein an etching solution for the surface of the metal sheet is formed in an opening of a resist film formed at a through hole portion of the skirt portion. And a method of manufacturing a shadow mask, characterized in that a dummy pattern for suppressing contact with the mask is additionally formed during the formation of the resist film.

According to a second aspect of the present invention, the shadow pattern according to the first aspect, wherein the dummy pattern additionally formed in the opening of the resist film formed in the through-hole portion of the skirt portion is a lattice pattern. This is a method for manufacturing a mask.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method of manufacturing a shadow mask according to the present invention will be described.

In this embodiment, an etching prevention layer (varnish layer) 2 is formed as described in the section (prior art).
A shadow mask was manufactured by a step etching method.

First, the metal sheet was degreased and surface-treated. Next, a water-soluble negative photosensitive resin containing polyvinyl alcohol and ammonium bichromate as components is applied to both surfaces of the thin metal plate 51, and then the photosensitive resin is dried to form a photosensitive layer 52 (FIG. 5). (A)).

Next, pattern exposure was performed on the photosensitive layer 52 using a large hole pattern exposure mask and a small hole pattern exposure mask. That is, the mask for pattern exposure for large holes is placed on the photosensitive layer on one surface side, and the mask for pattern exposure for small holes is placed on the photosensitive layer on the other surface side so as to be in close contact with each other. To expose the photosensitive layer.

Then, development was performed by spraying warm water on the photosensitive layer to remove the unexposed and uncured portions of the photosensitive layer. Next, after the metal thin film was immersed in an aqueous solution of chromic anhydride, the remaining photosensitive layer was hardened by performing a burning treatment to obtain a resist layer 53 (see FIG. 5B).

In the above steps, openings are formed in the resist layer 53 to expose the surface of the metal sheet. Here, as a feature of the present invention, as shown in FIG. 1, as shown in FIG. 1, the inside of a through-hole opening 18 (a portion within a dotted line in FIG. 1) of a resist layer 13 formed at a portion where a through-hole is to be formed in a skirt portion. Then, a dummy pattern 19 made of a resist is additionally formed. In the present embodiment, the through hole of the skirt portion is substantially rectangular, and in the conventional manufacturing method, the opening formed in the resist layer corresponding to the portion is also substantially rectangular (the through hole opening 28 in FIG. 2). See). Naturally, a pattern for a dummy pattern is also added to a pattern exposure mask for performing pattern exposure on the photosensitive layer. The dummy pattern 19 to be additionally formed on the resist layer is formed in the opening for the skirt on both sides of the metal thin plate, and the other resist layer portion, for example, the opening formed on the resist layer at the portion corresponding to the image surface portion (opening for the penetrating portion) ) Etc. have the same arrangement and pattern shape as before

After forming the resist layer, a ferric chloride solution having a liquid temperature of 80 ° C. and a Baume concentration of 42 ° C. is used as an etching solution in the same manner as in the conventional manufacturing method, and a metal sheet is formed at a spray pressure of 19.6 N per cm ² . The first stage etching was performed from both sides. The first-stage etching formed a small hole concave portion and a large hole concave portion on the image surface portion (see FIG. 5C). Etching is also performed on a metal sheet portion of the skirt where a through hole is to be formed, so that a concave portion or a through hole is formed.

Then, an etching prevention varnish is applied to the side of the thin metal plate on which the small holes are formed to form an etching prevention layer 57 filling at least the small holes (see FIG. 5D). Next, a second-stage etching is performed from the large hole surface side to form a through hole penetrating from the large hole concave portion to the small hole concave portion (see FIG. 5E). Next, the etching prevention layer and the resist layer were stripped using an aqueous sodium hydroxide solution. Next, the metal sheet was cut, unnecessary metal sheet portions were removed, and the like to obtain a shadow mask 300 (FIG. 5).
(F)).

As described above, according to the shadow mask manufacturing method of the present invention, as shown in FIG. 1, at the through-hole portion (through-hole opening 18) to be formed in the skirt portion, the dummy is formed at the opening of the resist layer. The pattern 19 is additionally formed.
The dummy pattern 19 is provided in order to suppress the amount of the etchant that comes into contact with the surface of the metal sheet exposed from the opening during etching. At a portion where the contact of the etchant is suppressed by the dummy pattern, the etching rate is reduced. For this reason, even if the etching conditions are set to form a penetrating portion having a desired shape on the image surface portion, the etching is slowed down at the through-hole portion where the dummy pattern is added, so that the etching does not proceed excessively. Thus, a through-hole having a shape of a circle is formed.

Here, the dummy pattern additionally formed in the opening may be, for example, an island shape as long as a desired through hole can be formed by lowering the etching rate. However, when the dummy pattern is formed in an island shape, a portion of the metal sheet below the island-shaped dummy pattern remains after etching, and is separated from the metal sheet as a metal piece. When the detached metal pieces are reattached to the shadow mask as foreign matter, the foreign matter adhering portion is detected as a pseudo error at the time of inspection of the shadow mask, and the inspection efficiency is reduced. Further, the metal pieces re-adhered to the shadow mask are rubbed with the shadow mask, thereby causing scratch defects on the shadow mask.

The present inventors have studied this point, and have found that the dummy pattern 19 has a lattice shape (mesh shape) in plan view as shown in FIG. By making the dummy pattern 19 additionally formed in the opening into a grid shape (mesh shape), the contact of the etchant with the surface of the thin metal plate is suppressed by the grid pattern, and the flow of the etchant is suppressed by the grid pattern. Is done. As a result, the etching rate at the opening decreases. Further, by forming the lattice pattern, the metal portion covered with the dummy pattern becomes thin. At the metal portion covered with the dummy pattern, etching is performed from both sides of the lattice. In addition to the narrow covering portion, the metal is dissolved and removed below the lattice pattern, so that there is no metal residue.

That is, by forming the dummy pattern in a lattice shape (mesh shape), the detachment of the metal piece due to the dummy pattern addition and formation does not occur, so that adhesion of foreign matter and defective defects can be prevented. The lattice-shaped dummy pattern loses its support because the lower portion of the thin metal plate is dissolved and removed, and drops off from the thin metal plate during the first-stage etching.

Although the embodiment of the shadow mask of the present invention has been described above, the present invention is not limited to the above description and drawings, and various modifications may be made based on the spirit of the present invention. It goes without saying. That is, it can be said that the shape of the lattice-shaped dummy pattern additionally formed inside the opening may be appropriately set according to the material or thickness of the thin metal plate, the etching conditions, the size and shape of the opening, and the like. Further, the shape of the through hole formed in the skirt portion is not limited to a rectangular shape, and may be an elliptical shape according to the specifications of the shadow mask.

[0029]

As described above, according to the method of manufacturing a shadow mask of the present invention, an image surface portion having a plurality of penetrating portions for transmitting an electron beam and a skirt having a through hole formed on the outer periphery of the image surface portion. Even with a shadow mask having
Both the through-hole for electron beam transmission and the through-hole in the skirt can be accurately formed in a desired shape.
Further, in the manufacturing method of the present invention, it is not necessary to attach the film-like sheet to the through-hole portions performed in the conventional manufacturing method, which increases the production cost of the shadow mask.
Further, the problem that the manufacturing process is complicated is solved.

[0030]

[Brief description of the drawings]

FIG. 1 is a partially enlarged plan view schematically showing a main part of a resist layer formed by a shadow mask manufacturing method of the present invention.

FIG. 2 is a partially enlarged plan view schematically showing an example of a resist layer formed by a conventional shadow mask manufacturing method.

FIG. 3 is an explanatory plan view showing an example of a shadow mask in which a through hole is formed in a skirt portion.

FIG. 4 is an explanatory plan view showing an example of a shadow mask.

5A to 5F are explanatory views showing an example of a method of manufacturing a shadow mask in the order of steps.

[Brief description of reference numerals]

 19 ··· Dummy pattern 24 ··· Opening for through portion 18 and 28 ··· Opening for through hole 31 and 41 ··· Image surface 32 and 42 ··· Skirt 33 and 43 ··· Through-hole 34 ··· Through-hole 51 ··· Metal thin plate 52 ··· Photosensitive layer 13, 23, 53 ··· Resist layer 54 ··· Opening 55 ··· Small hole recess 56 Large hole recess 57 Etching prevention layer 100, 200, 300 Shadow mask

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masakazu Hashimoto 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F-term (reference) 5C027 HH07 HH08

Claims (2)

[Claims] A step of forming a resist film having an opening exposing the surface of the metal sheet on the sheet metal; and a step of dissolving and removing a portion of the metal sheet exposed from the opening of the resist film with an etching solution. And at least a step of stripping the resist film, a shadow mask comprising an image surface portion having a plurality of through-holes for electron beam transmission formed thereon, and a skirt portion having a through-hole formed on the outer periphery of the image surface portion. The method of manufacturing, wherein a dummy pattern for suppressing contact of an etchant with the surface of the thin metal plate is additionally formed in the opening of the resist film formed in the through-hole portion of the skirt when the resist film is formed. Manufacturing method of mask. 2. The method according to claim 1, wherein the dummy pattern is a lattice pattern.