JPH01251536A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE:To obtain a high precision shadow mask with middle to high fine grains by, after exposing a photo-sensitive membrane to light having a prescribed pattern and developing it, washing it with an organic solvent with a polar radical and having a vapor pressure higher than that of water. CONSTITUTION:A photosensitive solution with a water soluble polymer as a membrane-forming agent is applied onto the surface of a shadow mask material and dried to form a photo-sensitive membrane. Then, this photo-sensitive membrane, after being exposed to light having a prescribed pattern and developed, is washed with an organic solvent with an polar radical and having a vapor pressure higher than that of water. As the organic solvent with a polar radical is so soluble in water that it is readily replaced with the developing solution, and also provided with a vapor pressure higher than that of water so that it rapidly evaporates, thereby suppressing development of blurring of the photo-sensitive membrane to minimum. With this procedure it is possible to produce a high precision shadow mask with middle to high fine grains.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for manufacturing a shadow mask used in a color cathode ray tube.

(Prior Art) Shadow masks used in color cathode ray tubes are generally manufactured using photolithography.

In particular, the production of medium-definition and high-definition shadow masks involves degreasing, washing with water, application of photosensitive liquid, drying, exposure, development, hardening, washing with water, draining, burning, skin exposure, first corrosion, washing with water, and drying. This process is carried out through many steps such as first varnish application, drying, second corrosion, washing with water, peeling, washing with water, and drying.

An example of a method for manufacturing the medium-definition and high-definition shadow masks described above will be described below.

First, both main surfaces of the shadow mask material made of pure mild steel plate, amber material, etc. are cleaned by degreasing, washing and drying, and then a photosensitive liquid containing casein and ammonium dichromate as main components is applied to both main surfaces. It is coated and dried at 90° C. for about 2.5 minutes to form a photoresist film with a thickness of about 6 μm. Next, a predetermined negative master plate is brought into close contact with both of the photoresist films, and exposed for about 30 seconds from a position of about 1 m using a mercury lamp of 5.5V.

In this exposure process, in the exposed area of the photosensitive film, hexavalent chromium compounds are reduced to trivalent chromium compounds by a photochemical reaction of dichromate, and this trivalent chromium compound combines with casein, a film-forming agent. Cures by crosslinking and becomes insoluble in water.

Next, hot water at about 45° C. is sprayed onto the photoresist film for about 1 minute to dissolve and remove the photoresist film in the unexposed area, that is, the position where the electron beam passage hole is formed.

Thereafter, a so-called hardening process is performed in which both main surfaces are wiped with about 0.5 to 5% by weight of chromic anhydride and washed with water so that the resist in unexposed areas does not bleed out as much as possible.

In this hardening process, unreacted casein after development is forcibly hardened with chromic anhydride or ammonium dichromate, thereby suppressing subsequent oozing.

Next, a surfactant (for example, Drywell [product name], etc.)
Drain quickly with a 0.2% solution of and burn uniformly at about 150°C.

Thereafter, after development, a roughening process is performed to remove the slight amount of resist remaining in the unexposed areas and to reproduce the same dimensions as the original negative pattern on the material as accurately as possible.

This skin-exfoliating treatment can be performed, for example, by treating with a skin-exfoliating solution consisting of a mixture of oxalic acid, hydrogen peroxide, and concentrated sulfuric acid, or after treating with a skin-exfoliating solution consisting of a mixture of potassium permanganate and caustic soda solution. This is done by processing.

The ingredients in these skin care solutions include a buffering agent, a cleaning agent for the material,
Acts as a decomposition agent for eluted casein.

After the bare surface treatment, both main surfaces are washed with water and subjected to a first corrosion treatment.

Thereafter, the resist on the electron gun side hole diameter is once removed, and after drying, varnish coating is applied and drying is performed again.

Next, a second corrosion process is performed from the pore diameter side of the phosphor screen, and after a final peeling, washing, and drying process, a medium-definition or high-definition shadow mask with a large number of electron beam passage holes is obtained. It will be done.

Incidentally, in recent years, with the development of various monitors and display tubes, the electron beam passage hole in the shadow mask has become extremely fine, and the quality of its cross-sectional shape is also required to have strict dimensional accuracy. .

In order to strictly control the dimensional accuracy of the shadow mask manufactured in the above manufacturing process, it is necessary to reproduce the original negative pattern dimensions as faithfully as possible to the shadow mask original plate. In particular, in the manufacturing process mentioned above, the development hardening process immediately after the developing process is performed to prevent the resist from bleeding out, and the exposing process after the burning process also removes the resist remaining on the material. Because they are performed for the purpose of removal, they are both important processes for strictly controlling dimensional accuracy, that is, for faithfully reproducing the original pattern dimensions on the material. Incorporating one or the other into the manufacturing process has been considered essential when manufacturing medium-definition and high-definition shadow masks.

(Problems to be Solved by the Invention) However, the conventional shadow mask manufacturing method including the hardening process and the skin exposure process has the following problems.

■ During the hardening process, when wiping with approximately 0.5 to 5% chromic acid anhydride to prevent unexposed areas of the resist from seeping out, traces of the coating (a phenomenon in which the resist does not penetrate) occur. This tends to cause unevenness and appears as unevenness during the corrosion process.

■ It is very difficult to control the concentration of chromic anhydride because the photosensitive film brings development water into this process.

■ If the treatment liquid is disposable, problems will arise in terms of pollution treatment and wastewater treatment.

■ In the exposure process, if you try to completely remove the remaining resist, the exposed resist film will also be uniformly attacked, resulting in film thinning phenomenon and damage to the photoresist film due to chemical and mechanical damage. It becomes weak, and deformed holes, scratches, etc. are likely to occur, resulting in a very low yield.

In other words, while the conventional shadow mask manufacturing method that performs hardening and skinning processes accurately reproduces the dimensions of the original pattern on the material, it suffers from the above-mentioned difficulties and drawbacks in hardening and skinning processes. There was a problem that this occurred.

The present invention has been made to solve the problems of the hardening process and the skin exposure process in the conventional shadow mask manufacturing method, and eliminates the need for the hardening process and skin exposure process. It is an object of the present invention to provide a method for manufacturing a shadow mask that enables manufacturing of a high-definition shadow mask with high accuracy.

[Structure of the Invention] (Means for Solving the Problems) The method for manufacturing a shadow mask of the present invention is to apply a photosensitive solution containing a water-soluble polymer as a film-forming agent to the surface of a shadow mask material, dry it, and expose it to light. The method is characterized in that a film is formed, then a predetermined pattern is exposed on this photosensitive film, developed, and then washed using an organic solvent having a polar group having a higher vapor pressure than water.

The organic solvent used in the present invention includes methanol,
Examples include alcohols such as ethanol and propatool, ketones such as methyl ethyl ketone, and ethers such as methyl ethyl ether. These may be used alone or in combination of two or more, but if necessary, 50 parts by weight
The following water may be added to raise the flash point for use.

It should be noted that this step may be carried out under an inert gas such as nitrogen to avoid the risk of fire.

Among these organic solvents, ethyl alcohol is most suitable for the present invention because it is less dangerous, less toxic, and relatively inexpensive.

In addition, in the present invention, by running the material vertically in the developing process, the developing water is quickly washed away, and the time to develop the unexposed areas is approximately twice that of the conventional method. It is desirable to make it about twice the conventional value.

(Function) In the manufacturing method of the present invention, since the organic solvent having a polar group is dissolved in water, it is quickly replaced by the developer, and since its vapor pressure is higher than that of water, it is quickly volatilized and prevents bleeding of the photosensitive film. Dashi is kept to a minimum.

Therefore, all of the conventional problems are solved or improved, and it is possible to manufacture a high-definition shadow mask with good dimensional accuracy that is no different from those that have been subjected to hardening treatment or surface exposure treatment.

(Example) Hereinafter, the present invention will be described as a 13' circular hole type shadow mask (
Pitch 0.2711% Electron gun side hole diameter 0.130sv,
An example applied to manufacturing a phosphor screen side hole diameter (0.25+1 m) will be described in detail.

After degreasing, washing, and drying a material made of pure iron-aluminum killed steel, a photosensitive solution containing casein as a main component (photosensitizer: ammonium dichromate) is applied, and the material is dried at 90°C for about 2.5 minutes to form a film of about 6 μm. A photoresist film with the thickness of a gourd was formed. Next, a negative original plate (0.15 mm on the phosphor screen side, 0.04 av on the electron gun side, original plate making machine: Photo Plotter manufactured by Gerber) was brought into close contact with the photoresist film, and it was exposed to light using a 5 kW mercury lamp from a distance of about 1 m. Exposure was made for 40 seconds.

Next, spray with warm pure water of about 45℃ at a pressure of about 1kg/C.
The photoresist film was sprayed for about 1 minute with a gun to dissolve and remove the unexposed areas, that is, the positions where electron beam passage holes were formed. In addition,
At this time, the material was moved vertically, and the manifold with the spray nozzle attached was swung at an angle of approximately ±20" to perform spraying. After that, it was immersed in ethyl alcohol at room temperature and immediately pulled up and drained. After that, it was dried for about 30 seconds in an atmosphere of 150°C.
Subsequently, a burning process was performed for about 30 seconds in an atmosphere of 200°C.

When the surface of the material was observed after the burning process, it was confirmed that there was hardly any oozing casein, and even if there was, it was in an amount that did not affect the dimensional accuracy.

Next, the hole on the side of the phosphor screen was covered with a polystyrene film to prevent corrosion, and the hole on the side of the electron gun was allowed to corrode for about 4 minutes (
PeCfl z solution: 85°C, specific gravity 1.4BD, liquid pressure 1
kg/ci: using Steinen nozzle).

Subsequently, the resist film on the side hole of the electron gun was further coated with an alkaline solution (Na01160℃, concentration approximately 6x1, spray pressure 1kg/
c)) It was completely peeled off, washed with water, and dried. After drying, remove the film that was shielding the holes on the side of the phosphor screen, apply varnish (a mixture of 1 part casein, 1 part epoxy resin, and 1 part water) only to the electron gun side hole using a varnish coater machine, and heat it at about 140°C. It was dried in an atmosphere for about 4 minutes to form a film with a thickness of about 10 μm.

After that, the side holes of the phosphor screen were etched for about 12 minutes (Fe
Cl23 solution 62℃, specific gravity 1.485, liquid pressure 1kg/
cd: using Steinen nozzle). Then, wash with water and remove the resist (NaOH 90℃, concentration 8%, spray pressure 1k)
g/c7, processing time approximately 2 minutes), washed with water, dried, and made into a 13' circular hole type shadow mask (pitch 0.27
n+m.

Electron gun side hole diameter 0.130■, phosphor screen side hole diameter 0.25m5
+) was obtained.

It has been confirmed that the dimensional accuracy of the high-definition mask obtained in this example is within ±2 μm in the neighborhood and ±3 μm within the area of 13', and fully satisfies the function of a color picture tube. was confirmed.

In the above embodiments, an example was explained in which a material made of pure iron/aluminum guild steel was used as a shadow mask, but the present invention is not limited to such embodiments, and can of course be used as a shadow mask for general consumer use. It is also fully applicable to amber masks, which are the mainstream for FS type medium and high definition tubules.

[Effects of the Invention] As explained above, according to the method for producing a shadow mask of the present invention, the hardening process and the skin exposure process are not required, so productivity is improved and the following many advantages are achieved. effect can be obtained.

■ There are no coating marks caused by wiping with chromic anhydride during the hardening process, and therefore no unevenness occurs during the corrosion process.

■ Eliminates the problems of adjusting chromic acid anhydride and disposing of the processing solution during the hardening process.

■ The film thinning phenomenon during the exposing process is eliminated, the occurrence of deformed holes, scratches, etc. is reduced, and the yield is improved.

Claims (1)

[Claims] (1) Applying a photosensitive solution containing a water-soluble polymer as a film forming agent to the surface of the shadow mask material and drying it to form a photosensitive film;
A method for manufacturing a shadow mask, which comprises exposing the photoresist film to a predetermined pattern, developing the film, and cleaning the film using an organic solvent having a polar group having a vapor pressure higher than that of water.