JPH0447419B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a shadow mask, and in particular, a thick shadow mask material with a plate thickness of 0.20 to 0.40 mm is used, and a ferric chloride solution is sprayed in the etching process. The present invention relates to a method of manufacturing a shadow mask in which fine and precise electron beam passage holes are formed by blowing the hole.

[Technical background of the invention]

In recent years, television receivers have been used as one of the components of video and audio equipment.
A simple and functional design is also required. For this reason, the color cathode ray tubes incorporated in television receivers are also changing from spherical screens to nearly flat screens, with no cut-offs in the image at the four corners of the screen, making them easier to view.

On the other hand, as is well known, the most important characteristic of the shadow mask built into a color cathode ray tube is that the electron beam emitted from the electron gun passes through the electron beam passage hole of the shadow mask, and each color faithfully forms a phosphor screen. The goal is to accurately hit the emitting phosphor layer. However, as time passes after the shadow mask is switched on, the temperature of the shadow mask increases due to the impact of the electron beam, causing thermal expansion.As a result, the positions of the electron beam spots and the phosphor layer no longer match, resulting in so-called Mislanding occurs, causing a color shift phenomenon.

This color shift phenomenon is more severe in the case of a flat color cathode ray tube than in a spherical color cathode ray tube, and there is a problem in that the color shift phenomenon is easily caused even by minute deformation of the shadow mask.

For example, conventional spherical, 19V, mini-net type
The inner surface of the face plate of a 90° deflection color cathode ray tube is flat with a radius of approximately 800 mm, 20 V,
The inner surface of the face plate of the mini network type 90° deflection color cathode ray tube has a radius of approximately 1350mmR.
The curvature of the shadow mask is also determined according to the radius of the inner surface of the face plate, and the radius of the former is approximately 760.
mmR, the latter is approximately 1300mmR.

According to experiments conducted by the present inventors, the thickness of such a shadow mask can be significantly increased from approximately 0.18 mm to approximately 0.30±0.10 mm to reduce the amount of deformation caused by thermal expansion of the shadow mask. It was also confirmed that it is possible to make the material strong against physical impact force.

However, when corroding such a thick shadow mask material, there are the following difficulties. That is, since it takes approximately twice as long to corrode the fine electron beam passage holes through the shadow mask material as in the conventional method, both main surfaces of the shadow mask material 1 are coated as shown in FIGS. 1 to 4. After forming exposed portions with diameters d ₁ and d ₂ in the photoresist films 2 and 3, respectively, in an etching process, holes are formed from shallow holes 4 ₁ and 5 ₁ to slightly deeper holes 4 ₂ and 5 ₂ and even deeper. When the holes 4 ₃ and 5 ₃ are bored and the electron beam passing hole 6 having the opening diameters D ₁ and D ₂ is bored, side wall corrosion occurs in the direction of the arrow 7 due to the corrosive liquid, resulting in D Large eaves _{2 1} , 3 ₁ of the photosensitive films 2 , ₃ at 1 - d ₁ and D ₂ - d ₂ are generated, and the eaves 2 ₁ , 3 ₁ are deformed or damaged by the impact force caused by the spray of the corrosive liquid. There is a problem in that the shape of the electron beam passage hole 6 is ultimately deteriorated and the shadow mask becomes defective.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems, and is suitable for use in flat color cathode ray tubes.
The object of the present invention is to provide a method for manufacturing a shadow mask which has a plate thickness of 0.20 to 0.40 mm and is capable of forming fine and precise electron beam passage holes of good quality.

[Summary of the invention]

That is, in the present invention, a long shadow mask material having a predetermined thickness and having a photoresist film remaining on both main surfaces except for the small hole forming part and the large hole forming part is moved and sprayed in an etching bath. In a method for manufacturing a shadow mask in which an electron beam passage hole is formed by spraying a corrosive liquid with a predetermined impact force,
The film thickness is 8 to 12 μm on both main surfaces of the 0.4 mm shadow mask material, excluding the small hole forming area and the large hole forming area.
The etching tank is divided into a first etching tank and a second etching tank from the traveling direction of the shadow mask material, and the impact force applied to the photoresist film in the first etching tank is set at 5 to 10 g/m. A corrosive liquid is sprayed on both main surfaces of the shadow mask material at a pressure of 2.5 to 5 g/cm ² in the second corrosive bath ^.
The method is characterized in that electron beam passage holes are formed by spraying an etchant onto both main surfaces of the shadow mask material.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIGS. 5 to 11.

First, prepare a long piece of 0.3 mmt mild steel plate as a shadow mask material, and after cleaning both main surfaces,
To this shadow mask material, a photosensitive solution containing milk casein as a main component, that is, ammonium dichromate as a sensitizer was added to the casein in an amount of about 1% by weight, and the specific gravity was adjusted to 1.040 (previously 1.028). Apply by vertical pulling method using dip method, approx.
Dry for about 10 minutes in an atmosphere of 100℃, approximately 10μm
A photoresist film with a thickness (previously 5 μm) is formed. Next, in the exposure process, the hole width d ₃ shown in FIG.
is 0.060mm (previously 0.115mm), bridge width b ₁ is
The small hole side negative pattern 10 ₁ is 0.235 mm (previously 0.200 mm), and the hole width d ₄ shown in Fig. 6 as the large hole is 0.410.
A large-hole side negative pattern 10 ₂ with a bridge width b ₂ of 0.150 mm (previously 0.125 mm) and a bridge width b 2 of 0.150 mm (previously 0.405 mm) was brought into close contact with the photoresist film and heated from a distance of about 1 m using a 5KW mercury lamp for about 1 minute. Perform exposure. Then about 40℃
Developed with warm pure water for 1 minute at a spray pressure of 1 kg/ ^cm2 , dried for 2 minutes in an atmosphere of 150°C,
Burn in an atmosphere of 200℃ for 1.5 minutes. In this way, a shadow mask material 11 with the photoresist films 12 and 13 remaining on both main surfaces shown in FIG. 7 except for the small hole forming part with the hole width d ₃ and the large hole forming part with the hole width d ₄ is prepared. To manufacture.

Next, the etching process will be explained with reference to FIGS. 8 to 11. Erosion is performed while moving the long shadow mask material 11 in its longitudinal direction. The corrosion equipment includes a first corrosion tank 21 and a second corrosion tank 2 from the direction of movement of the shadow mask material 11 shown by the arrow 20.
2. Consists of a water washing tank 23, and in the first corrosion tank 21, the impact force applied to the photoresist films 12, 13 is set at 5 to 10 g/
cm ² and spray the corrosive liquid from the spray nozzle 21a onto both main surfaces of the shadow mask material 11.
The holes are drilled from shallow holes 14 ₁ and 15 ₁ shown in the figure to slightly deeper holes 14 ₂ and 15 ₂ shown in FIG. 10. As you can see from the figure, in this corrosion process, arrow 17 ₁
The side wall corrosion in the direction does not progress much, and the photoresist film 12,1
Since the eaves 12 ₁ and 13 ₁ of No. 3 do not come out much, the impact force exerted on the photoresist films 12 and 13 by the corrosive liquid sprayed from the spray nozzle 21a is 5 to 10 g/cm ^{2 .}
However, the photoresist films 12 and 13 having a film thickness of about 10 μm can withstand the problem sufficiently. This impact force of 5 to 10 g/cm ² was applied using EX-430 manufactured by Niikura Kogyo, with a spray pressure of 1.5 to 2.5 kg, and a distance between the nozzle 21a and the shadow mask material 11.
Obtained at 300mm. Corrosion in this case occurs at a liquid temperature of 67°C.
This is carried out for about 6 minutes using a ferric chloride solution with a specific gravity of 1.467.

In the next second corrosion tank 22, from the slightly deeper holes 14 ₂ and 15 ₂ shown in FIG. 10 to the even deeper hole 1 shown in FIG.
Drill up to 4 ₃ , 15 ₃ to form electron beam passage hole 16
form. At this time, the side wall corrosion progresses in the _two directions of the arrow 17, and the eaves 12 2 , 1 of the photoresist films ₁₂ , 13
3 ₂ will gradually come out, so spray nozzle 22
From a, the impact force exerted by the etchant on the photosensitive film was lowered to 2.5 to 5 g/cm ² , which is about half of that in the first etch tank, and the etchant with the same composition and temperature was sprayed on both main surfaces of the shadow mask material 11 for about 6 minutes. to finish the corrosion process.

The slot width D ₃ on the electron gun side, that is, on the small hole side of the electron beam passage hole 16 drilled in this way is 0.200.
mm (same as before), slot width _D4 on the phosphor screen side, that is, large hole side, is 0.580mm (previously 0.510mm), bridge width is
0.120mm (same as conventional), side wall corrosion amount D ₃ −
d ₃ is 0.140mm (previously 0.085mm), D ₄ − _{d 4} is 0.170mm
(previously 0.105 mm), the eaves 12 ₂ and 13 ₂ are longer than the conventional one, but the second corrosion tank 22
Since the photosensitive films 12 and 13 are thick and further reduce the impact force, the eaves 12 ₂ ,
It was possible to drill an electron beam passage hole 16 with _good quality and no deformation or damage.

Next, the mask is washed in a washing tank 23 to remove the photoresist film and a flat mask is obtained.

The present invention is effective when a photoresist film having a thickness of 8 to 12 μm is formed on a shadow mask material having a thickness of 0.2 to 0.4 mm.

Furthermore, although the above embodiment has been described with respect to a rectangular electron beam passage hole, it goes without saying that the same applies to a circular electron beam passage hole.

〔Effect of the invention〕

As described above, according to the present invention, even when the thickness of the shadow mask material is increased, the photoresist film is made thicker, and furthermore, the planar collar is etched using two etching baths with different impact force conditions. It is possible to form a shadow mask suitable for cathode ray tubes with good quality, and its industrial value is extremely large.

[Brief explanation of the drawing]

1 to 4 are explanatory cross-sectional views showing a conventional method for manufacturing a shadow mask in the order of steps, and FIGS. 5 to 11 are views showing an embodiment of the method for manufacturing a shadow mask according to the present invention. Figure 6 is an explanatory diagram of the negative pattern on the small hole side, Figure 6 is an explanatory diagram of the negative pattern on the large hole side, Figure 7 is an explanatory cross-sectional view showing the relationship between the shadow mask material and the photoresist film before the corrosion process, and Figure 8 is Diagrams of the corrosion apparatus and FIGS. 9 to 11 are explanatory cross-sectional views showing the corrosion state in the corrosion process in the order of the process. 1,11...Shadow mask material, 2,3,1
2, 13...photosensitive film, 2 ₁ , 3 ₁ , 12 ₁ , 13 ₁ ,
12 ₂ , 13 ₂ ...Eaves, 4 ₁ , 5 ₁ , 14 ₁ , 15
₁ ... Shallow hole, 4 ₂ , 5 ₂ , 14 ₂ , 15 ₂ ... Slightly deep hole, 4 ₃ , 5 ₃ , 14 ₃ , 15 ₃ ... Deeper hole, 6, 16... Electron beam Passing hole section, 21...
...First corrosion tank, 22...Second corrosion tank, 23...
...Water tank.

Claims (1)

[Claims] 1. A spraying method in an etching tank while moving a long shadow mask material with a predetermined thickness, in which a photoresist film remains on both main surfaces except for small hole forming areas and large hole forming areas. In the method of manufacturing a shadow mask, in which electron beam passing holes are formed by spraying a corrosive liquid with a predetermined impact force, a small hole forming portion and a large hole forming portion are formed on both main surfaces of a shadow mask material having a thickness of 0.2 to 0.4 mm. The photoresist film with a thickness of 8 to 12 μm remains, and the etching tank is divided into a first etching tank and a second etching tank from the direction of movement of the shadow mask material. Spray the corrosive liquid on both main surfaces of the shadow mask material with an impact force of 5 to 10 g/ ^cm2 , and
In the corrosion bath, the impact force applied to the photoresist film is 2.5
A method for producing a shadow mask, which comprises: spraying a corrosive liquid on both main surfaces of a shadow mask material at a concentration of ~5 g/cm ² to form electron beam passage holes.