JPH08199374A - Production of shadow mask - Google Patents

Abstract

PURPOSE: To provide a producing method of a slot type shadow mask having a bridge part narrow in width and thick in the thickness direction by separating etching for a small recessed part from etching for large recessed part and carrying out three-step etching whose two steps are applied to the large recessed part. CONSTITUTION: A 1st resist pattern 15 and a 2nd resist pattern 13 are formed respectively on resist films formed at least the front and back surfaces of a metallic thin film 2. The small recessed part 16 is formed on the back surface by etching an opening part 14 of the resist pattern 15 on the back surface and an etching resistant layer 17 is formed on the whole back surface. The large recessed part 18 is formed on the front surface by etching an opening part of the resist pattern 13 on the front surface, a 3rd resist pattern 19 covering the peripheral part of the large recessed part 18 is formed and a hole penetrating to the recessed part of the back surface is formed by etching a metal exposed part at the center part of the recessed part 18 of the front surface. The shadow mask is formed by removing the resist pattern 13, 19 on both surfaces and the etching resistant layer 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a shadow mask for a color cathode ray tube, and more particularly to a slot type shadow mask having a narrow bridge portion, a high transmittance without reducing the thickness, and a high strength. The present invention relates to a manufacturing method for forming a shadow mask by etching.

[0002]

2. Description of the Related Art In a striped color cathode ray tube, three continuous stripes are vertically formed on the inner surface of a panel on which an image is displayed in a direction perpendicular to a scanning line of an electron beam emitted from an electron gun.
A fluorescent film is formed by arranging a large number of rows of color fluorescent stripes, arranged in a predetermined pattern so as to face the fluorescent surface, and formed into a large number of slot-shaped parts connected by a bridge portion so as to maintain mechanical strength. A shadow mask having a through hole is attached. As shown in FIG. 3, the through-hole 1 of the shadow mask reduces the electron beam that collides with the shadow mask and is reflected in the direction of the fluorescent screen. Therefore, the electron gun on the opposite side of the opening 1a on the surface facing the fluorescent screen. Opening 1b on the surface facing
It is formed larger.

Conventionally, a general shadow mask has been manufactured by a two-step etching method as disclosed in JP-A-63-286588. That is, this 2
As shown in FIGS. 4A to 4D, the step etching method is performed by exposing the metal thin plate 2 on both sides with exposed portions 3 corresponding to the through holes of the shadow mask.
After forming resist patterns 4a and 4b having a and 3b (FIG. 4a), a protective film 5 is attached to the resist pattern 4a side of the surface for forming a large opening (FIG. 4b) to form a small opening. The small-area exposed portion 3b side of the back surface for etching is etched to form a small recess 6 (FIG. 4c). After that, the resist pattern 4b on the side of the exposed portion 3b having the small area is peeled off, and a varnish made of epoxy resin is applied to the entire back surface of the metal thin plate 2 from which the resist pattern 4b is peeled off to form the etching resistance layer 7. , A protective film 5 attached to the large-area exposed portion 3a side of the surface
Is peeled off, and an etching solution is sprayed on the exposed side 3a having a large area until it penetrates the small concave portion 6 so that the large concave hole 8 is formed by anisotropic etching in the depth direction (FIG. 4d).
Then, the etching resistance layer 7 and the resist film 4a are removed, and etching is performed until the protrusion of the through hole becomes the same as the opening size on the small hole side, so that a shadow mask having the through hole 1 as shown in FIG. 3 is obtained. .

However, recently, in a high-definition color cathode ray tube such as a display tube, there is an increasing demand for finer shadow masks. for that purpose,
It is necessary to reduce the through holes of the shadow mask and the arrangement pitch thereof, and it is easier to manufacture the shadow mask plate if the plate thickness is smaller. However, for the cathode ray tube, it is necessary to increase the plate thickness in order to maintain the mechanical strength in order to increase the molding accuracy of the shadow mask as the area ratio of the transmission holes increases and the size increases. Therefore, in order to process the connecting portion of the shadow mask to be narrow and thick, as shown in FIGS. 5A to 5C, in JP-A-2-298283, the first step is half-etched from both sides to form a large recess. 9 and small recesses 10 (FIG. 5a),
A second resist film 11 is formed on the periphery of the large concave portion 9 and the small concave portion on the back surface is covered with the etching resistance layer 7 (see FIG. 5).
b), the large recess 9 is etched in two steps to form the small recess 1 on the back surface.
A method of manufacturing a shadow mask through 0 (FIG. 5c) is disclosed. On the other hand, since the bridge part in the slot type shadow mask is a non-transmissive part of the electron beam, a shadow part is generated on the display screen, so that the focus characteristic of the electron beam is improved and the beam spot diameter is reduced, Since the difference in brightness and darkness becomes large on the screen and the influence of moire fringes becomes remarkable, it is necessary to design the bridge width as small as possible, for example, about 10 to 20% of the pitch in the slot hole longitudinal direction.

[0005]

Therefore, if the bridge width is designed to be the minimum width that maintains the mechanical strength of the shadow mask, even if anisotropic etching is adopted in the above two-step etching, When the large recess is formed, this bridge part is etched and the plate thickness of the bridge part becomes thin, and there is a problem that the mechanical strength cannot be maintained.To prevent this, widening the bridge width reduces the electron beam transmittance. However, there is a problem that the display characteristics are deteriorated. Further, in the method of half-etching the first stage etching from both sides, both sides are etched at the same time. Therefore, etching having anisotropy in the depth direction, for example, etching solution is sprayed on the etching surface to perform etching in the depth direction. There is a problem that it is difficult to control the etching to the bridge portion because a method of increasing the amount cannot be adopted. The object of the present invention is to solve the above problems.
A method for manufacturing a shadow mask having a narrow bridge portion and a thick bridge portion in the thickness direction is provided by separating the etching of the small recesses from the etching of the large recesses and etching the large recesses in two steps to form three-step etching. To provide.

[0006]

According to the present invention, there is provided a step of forming a first resist pattern and a second resist pattern on a resist film formed on both front and back surfaces of a metal thin plate, and a first resist pattern on the back surface. Of forming the small recessed portion on the back surface by etching the opening of the second step, forming an etching resistance layer on the entire back surface, and etching the opening of the second resist pattern on the front surface to form the large recessed portion on the front surface. And a step of forming a third resist pattern covering the periphery of the large recess formed on the front surface, and a step of etching the opening of the third resist pattern to form a hole penetrating the recess on the back surface. And a method of manufacturing a shadow mask, which comprises a step of removing the etching resistance layer and the resist pattern on both sides. A method for manufacturing a slotted shadow mask for a striped color cathode ray tube, wherein the opening size of the first resist pattern is longer in the longitudinal direction than the opening size of the second resist pattern, and the widthwise direction is shorter. Is desirable to be formed short.

[0007]

According to the above-mentioned manufacturing method, during the etching process of the through holes of the shadow mask, the etching of the small recesses is separated from the etching of the large recesses, and the etching of the large recesses is performed in two steps to enable anisotropic etching. Due to the narrow width,
Since deep through holes can be formed, there is no reduction in mechanical strength,
It is possible to obtain a shadow mask having a thick and narrow bridge portion without deterioration in screen display characteristics due to a decrease in electron beam transmittance. The slot type shadow mask having a thick and narrow bridge portion is formed by forming the opening size of the first resist pattern to be longer in the longitudinal direction and shorter in the lateral direction than the opening size of the second resist pattern. can get.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. As shown in FIGS. 1A to 1F, one embodiment of the shadow mask manufacturing method of the present invention is a thin metal plate 2 made of an amber material (Ni: 36%, balance iron) having a plate thickness of 0.18 mm.
60μ width corresponding to the through hole 1 of the shadow mask on the back surface of the
m, length 300 μm of the openings 12 and pitch 3 in the longitudinal direction.
A first resist pattern 13 having an arrangement of 60 μm is formed, and a second resist pattern 15 having oval openings 14 having a width of 120 μm and a length of 260 μm arranged at the same pitch is formed on the surface (FIG. 1a). Then, a protective film 5 is attached to the front surface side (FIG. 1b), and the back surface side is anisotropically etched to form a small recess 16 having a depth of 45 μm (FIG. 1).
c). After that, the first resist pattern 13 on the back surface side is peeled off, a varnish made of epoxy resin is applied to the entire back surface of the metal thin plate 2 to form an etching resistance layer 17 (FIG. 1d), and further, it is attached to the front surface side. The attached protective film 5 is peeled off, and a large concave portion 18 having a depth of 80 μm is formed on the front surface side by, for example, half etching having anisotropy such as spraying an etching solution (FIG. 1e). Further, after forming a third resist pattern 19 that covers the peripheral portion of the large recess 18 with a width of 20 μm (FIG. 1f), the front surface side is etched until it penetrates the small recess 16 on the back surface side, and etching is performed. By removing the resistance layer 17 and the second resist patterns 15 and 19, a shadow mask having through holes as shown in FIG. 2 is obtained. According to the method for manufacturing a shadow mask of this embodiment, since a bridge portion having a narrow width as shown in FIG. 2 and having a reduced plate thickness can be formed, mechanical strength is not deteriorated, and electron A slot-type shadow mask having a high beam transmittance can be obtained.

An example of manufacturing a slot shadow mask having an opening on the front surface side of 120 μm, an opening on the back surface side of 60 μm and a bridge width of about 60 μm by using anisotropic etching has been described above. Is not limited to the above example, and it goes without saying that the bridge width can be designed to an optimum value depending on the material of the shadow mask, the plate thickness, the slot pitch, the opening size, etc., and the combination of the anisotropic etching methods can be freely selected. Yes.

[0010]

According to the present invention, during the etching process of the through holes of the shadow mask, the etching of the small recesses is separated from the etching of the large recesses, and the etching of the large recesses is performed in two steps, thereby performing three-step etching. , A narrow and deep through hole can be formed, so that there is no deterioration in mechanical strength, and there is no deterioration in screen display characteristics due to a decrease in electron beam transmittance, and a shadow mask having a thick and narrow bridge portion is obtained. be able to. The slot type shadow mask having a thick and narrow bridge portion is formed by forming the opening dimension of the first resist pattern to be longer in the longitudinal direction and shorter in the lateral direction than the opening dimension of the second resist pattern. Is obtained.

[Brief description of drawings]

1A to 1F are explanatory views of steps of a method for manufacturing a shadow mask according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a shadow mask manufactured by the manufacturing method of the present invention.

FIG. 3 is a sectional view of a main part of a conventional shadow mask.

4A to 4D are process explanatory diagrams of a conventional shadow mask manufacturing method.

5A to 5D are process explanatory diagrams of another conventional method for manufacturing a shadow mask.

[Explanation of symbols]

 2 Metal thin plate 5 Protective film 12, 14 Opening 13 First resist pattern 15 Second resist pattern 16 Small recesses 17 Etching resistance layer 18 Large recesses 19 Third resist pattern

Claims (2)

[Claims] 1. A step of forming a first resist pattern and a second resist pattern on a resist film formed on both surfaces of a thin metal plate, and an opening of the first resist pattern is etched to form a small recess on the back surface. A step of forming an etching resistance layer on the entire back surface, and etching the opening of the second resist pattern to form a large recess on the surface, and a peripheral portion of the large recess formed on the surface. A step of forming a third resist pattern to be covered, a step of etching the opening of the third resist pattern to form a hole penetrating the small recess on the back surface, and removing the etching resistance layer and the resist pattern on both sides. A method of manufacturing a shadow mask, which comprises: 2. A method of manufacturing a slot type shadow mask for a stripe type color cathode ray tube, wherein an opening size of the first resist pattern is longer in a longitudinal direction than an opening size of the second resist pattern. The shadow mask manufacturing method according to claim 1, wherein the widthwise direction is formed to be short.