JP2703279B2 - Manufacturing method of shadow mask - Google Patents

Description

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

(Prior Art) In general, a shadow mask type color picture tube has a shadow mask in which a large number of beam apertures are arranged at a predetermined pitch and arranged in close proximity to a phosphor screen. This shadow mask concentrates the three electron beams corresponding to red, blue and green from the electron gun near one beam aperture, and correctly applies it to the phosphor screen painted differently to correspond to red, blue and green. It is one of the important members that have a so-called color selection function that reproduces a color image by shooting.

Therefore, when the distortion of the beam aperture shape of the shadow mask, the distortion of the arrangement of the beam aperture and the corresponding phosphor, and the distortion of a certain distance between the shadow mask and the phosphor screen exceed the permissible ranges, all of the distortions of the color purity are lost. This will cause a serious problem in characteristics such as deterioration. Each beam aperture of the shadow mask generally has a cross-sectional shape as shown in FIG. 2 in order to secure a certain amount of passing of the obliquely incident electron beam. That is, the opening 2 (hereinafter, referred to as a large hole) on the phosphor screen side of the strip-shaped metal thin plate 1 is formed so as to have an area approximately three times as large as the opening 3 (hereinafter, referred to as a small hole) on the electron gun side. ing.

Such a shadow mask is conventionally manufactured through the following steps.

First, as shown in FIG. 3 (a), a photosensitive resin layer, for example, a resist film 4 containing a photosensitive agent is formed on both surfaces of a strip-shaped metal thin plate 1 which is a material for a shadow mask. Next, a predetermined portion of the resist film 4 is exposed through a mask pattern corresponding to a predetermined opening area, and the large hole 2 and the small hole 3 to be opened as shown in FIG. A part of the resist film 4 is removed to expose the material surface.

Next, if the material is mainly composed of iron, the second
Etching is performed using an etching solution containing iron chloride as a main component, and a predetermined opening is formed as shown in FIG. 3 (c).

Thereafter, a flat mask obtained by removing the remaining resist film is formed to obtain a finished product.

(Problems to be Solved by the Invention) By the way, in a predetermined hole shape as shown in FIG. 2, it is the etching from the side of the small hole 3 that is most involved in the accuracy control of the minimum hole diameter. Requires that the etching from the side of the large hole 2 be controlled. Also, needless to say, the etching amount on the large hole 2 side must be larger than the etching amount on the small hole 3 side. Under these conditions, the etching hole area on the large hole 2 side is about three times as large as the etching hole area on the small hole 3 side. Exchange efficiency is good,
The etching rate and the amount become large, and the above conditions are satisfied for the time being.

However, since the etching rate and amount on the side of the large hole 2 are large, side etching also proceeds, and the eaves 5 of the resist film 4 floating from the metal sheet 1 as shown in FIG. The insulated portion 5 often peels or breaks due to fatigue of the etching solution. As a result,
Since etching proceeds further in the portion where the resist film 4 is destroyed, a hole shape distortion is generated, and the quality of the shadow mask is degraded. Such a tendency is more remarkable in a shadow mask having a reduced aperture pitch and diameter for a high-definition color picture tube, and the more the thickness of the thin metal plate 1 is, the greater the etching amount is.

In addition, the variation in the size of the exposed portion of the thin metal plate 1 directly affects the size of the shadow mask, resulting in a decrease in the quality of the shadow mask. One cause of the variation in the size of the exposed portion is a variation in the thickness of the resist film 4. This is because light that has passed through the baked pattern diffuses in the resist film 4 formed on the metal thin plate 1.
When the film thickness is large, the size of the exposed portion obtained after exposure and development is small. Therefore, it is important that the film thickness of the resist film 4 is uniform under a constant exposure condition.

Normal resist coating is performed by a flow method as shown in FIG. 4 or a dipping and pulling method as shown in FIG.
In the flow method, the strip-shaped metal thin plate 1 is erected vertically, and a resist material 13 is dripped from above onto both surfaces of the metal thin plate 1, and then passed through a drying furnace 15 to form the resist film 4. However, the thickness of the upper portion is smaller than that of the lower portion due to the influence of gravity, and it is inevitable that a film thickness difference occurs in the plate width direction. In order to eliminate this difference in film thickness, for example, even if using a drying furnace having a temperature distribution to promote the drying of the upper part quickly,
Even if the transport speed of the metal sheet 1 and the viscosity of the resist liquid are variously changed, it is impossible to obtain a uniform film thickness.

On the other hand, in the immersion pulling method, the metal sheet 1 is
After being immersed, the resist material 13 on the metal sheet 1 pulled up in the vertical direction flows down by gravity until it is dried and completely fixed, so that the resist film 13 in the length direction of the metal sheet 1 Thickness fluctuation occurs. To suppress this,
Resist material viscosity, metal sheet pulling speed, drying temperature distribution,
Although the suction air volume and the like are adjusted, it is impossible to obtain a uniform resist film thickness.

On the other hand, considering the resist film thickness,
When the plate thickness is increased, the proportion of the above-described resist film eaves portion 5 increases in proportion to the increase in the etching time, and naturally, the time that the portion is exposed to the sprayed etching solution is prolonged. As a result, the resist film eaves 5
Is more likely to be destroyed, and the damaged portion is further etched to cause a large defect. Therefore, in order to improve the mechanical strength of the resist film 4, measures are taken to increase the resist film thickness.

However, in the conventional method, the influence of gravity is inevitable, and the above-mentioned conditions must be changed significantly. Therefore, it is impossible to easily and uniformly increase the resist film thickness in a mass production line.

In consideration of the required resist film thickness on the small hole 3 side and the large hole 2 side, the shadow mask hole size is generally determined by the material exposed portion size on the small hole 3 side. In order to obtain an accurate exposed portion, it is desired that the resolution of the resist film 4 be good. It goes without saying that the resolution depends on the characteristics of the resist material 13 itself, but also depends on the film thickness. The thinner the resist film, the higher the resolution. Therefore, unless the eaves portion 5 of the resist film formed by the etching is destroyed during the etching, it is preferable that the resist film thickness is as small as possible, especially on the small hole 3 side. For example, JP-A-60-70
In the two-stage etching method proposed in Japanese Patent Publication No. 185, since the etching time on the side of the small hole 3 is short, even if the resist film thickness is small, the eaves portion 5 of the resist film does not break during the etching. As a result, the resist film thickness can be reduced, and does not significantly affect the quality of the shadow mask.

Various other means have been proposed to manufacture a high-definition shadow mask as described above, but it is desirable that the resist film on the small hole 3 side is thinner than the resist film on the large hole 2 side. However, it is extremely difficult and impossible to form a uniform resist film with a different film thickness on the small hole 3 side and the large hole 2 side by the flow method and the immersion pulling method, which are conventional techniques. Close to.

The present invention provides a method of manufacturing a shadow mask capable of freely changing the film thickness on both main surfaces of a continuous strip-shaped metal sheet and forming a uniform film thickness in the width direction and the longitudinal direction of the continuous strip-shaped metal sheet. The purpose is to provide.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a first step of forming a photosensitive resin layer by applying a photosensitive resin liquid and drying after cleaning both main surfaces of a continuous strip-shaped metal thin plate with degreasing water. A shadow mask comprising: a second step of forming a predetermined fine hole pattern in the photosensitive resin layer by photographic exposure; and a third step of forming fine holes in the continuous strip metal sheet by etching. In the manufacturing method, the first step is to transport the continuous strip-shaped metal sheet in the horizontal direction, first apply the photosensitive resin liquid to one main surface as a first application, and then apply the applied surface. Drying upward, then turning the continuous strip-shaped metal sheet, applying the photosensitive resin liquid to the other main surface as a second application, and then drying the second applied surface upward. Shadow mask manufacturing method Is the law.

Then, a pipe doctor or a reverse coater may be used to apply the photosensitive resin liquid, and the thickness of the photosensitive resin layer may be different between the two main surfaces.

The drying of the photosensitive resin applied for the first time is dried by a heat source facing both main surfaces of the continuous strip-shaped metal sheet,
The drying of the photosensitive resin applied for the second time is performed by drying the photosensitive resin film on both sides independently by drying with a heat source facing only the surface of the continuous strip-shaped metal sheet on which the photosensitive resin is applied for the second time. Control can be performed with high accuracy, and the heat fogging phenomenon can be prevented.

(Operation) In the present invention, the continuous strip-shaped sheet metal is transported in the horizontal direction,
After applying the photosensitive resin liquid to one of the main surfaces, the coated surface is dried with the coated surface facing upward, then the metal sheet is turned over, and after applying the photosensitive resin liquid to the other main surface, the surface is removed. By drying the photosensitive resin upward, the photosensitive resin after application is not adversely affected by gravity, so that the thickness of the photosensitive resin can be controlled with high accuracy.

In addition, the pre-stage drying is performed from at least one main surface side of the metal sheet, and the post-stage drying is performed from the second main surface side coated with the photosensitive resin. The heat fogging phenomenon can be prevented without receiving the heat.

Furthermore, by cooling the main surface side on which the photosensitive resin is formed for the first time during the subsequent drying, the heat fogging phenomenon can be further prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The apparatus used in the method for manufacturing a shadow mask according to the present invention is configured as shown in FIG.
Set of backup rollers 11, 11 ', two sets of resist material 1
Dams 14 and 14 'for storing 3 and 13', coating means 2
Sets of pipe doctors 12, 12 ', two sets of drying ovens 15, 15',
And a turn roller 10 for reversing the continuous strip-shaped metal sheet 1
It consists of In the first-stage drying furnace 15, a heater 16 is provided at a position facing both main surfaces of the metal sheet, and in the second-stage drying furnace 15 ', a heater 16' is provided at a position facing the upper surface of the metal sheet. Is installed. In order to manufacture a shadow mask using such an apparatus, first, a continuous high-temperature alkaline solution of 80 ° C. or higher is sprayed on a continuous strip-shaped metal sheet 1 made of iron, which is a material for a shadow mask, in a degreasing chamber (not shown). Then, the rolling oil and rust-preventive oil applied to the surface are degreased.

Thereafter, the surface of the metal sheet 1 is cleaned by rinsing with a rinsing chamber (not shown).

Next, the sheet metal 1 with the clean surface exposed is conveyed in the horizontal direction as shown in the figure, and is first turned over via the backup roller 11. A pipe doctor 12 is provided above the backup roller 11, and a dam 14 for storing a resist material 13 is provided on the supply side of the metal sheet 1.

The resist material 13 is a photosensitive resin solution prepared by adding about 1% by weight of milk caseinate and ammonium bichromate to milk caseinate and adjusting the viscosity to 100 cps at night.

Then, the resist material 13 applied to the surface of the metal sheet 1
Can be changed by appropriately selecting the distance between the pipe doctor 12 and the metal sheet 1. Therefore, the pipe doctor 12 is configured to be movable up and down so that the distance between the pipe doctor 12 and the metal sheet 1 can be freely changed. Resist material
The viscosity of 13 is 10 cps to 1000 cps, preferably 12 to 200 cps. If the viscosity is less than 10 cps, the coating surface is not stable, and the coating tends to be uneven due to the fluctuation of the metal sheet during drying. When the viscosity is further low, the solid content is so small that it is difficult to increase the film thickness, and the amount of water is large and the drying time is too long.

On the other hand, if the viscosity is 1000 cps or more, when the resist material 13 passes through the gap between the pipe doctor and the metal sheet, uniform shear stress is not applied, and the film thickness tends to vary, and the solid content is further increased. And it is difficult to control the film thickness finely. The resist material 13 is supplied from a resist supply tank (not shown) provided above the dam 14 by gravity.
The excess resist material is supplied to 14 and travels along the surface of the sheet metal 1 to the resist tray to be collected. The collected resist material goes to a resist storage tank (not shown),
It is pumped to the resist supply tank via a filter (not shown) by a pump, and is circulated.

After the resist material 13 is applied to the surface of the metal sheet 1 in this manner, heat is applied to both main surfaces of the metal sheet 1 by the infra stein heater 16 to dry the resist material 13. To form a resist film having the following thickness. In this case, the temperature of the resist film is preferably 90 ° C. or less.
When the temperature exceeds 90 ° C, fogging tends to occur.

Next, the metal sheet 1 is pulled upward through the turn roller 10, and the metal sheet 1 is inverted via the backup roller 11 '. A pipe doctor 12 'having a dam 14' is provided above the backup roller 11 '. By appropriately changing the distance between the pipe doctor 12' and the metal sheet 1, the other main surface of the metal sheet 1 is formed. After the resist material 13 is applied, heat is applied by an infra stein heater 16 'facing only the surface on which the resist material 13 is applied, and the resist material 13 is dried to form a resist film having a desired thickness. In this case, cooling the first resist film with cold air or the like is effective in preventing the first heat fogging.

As a heat source for drying, a combination of an infra fin heater and a hot air, a combination of a hot air only, a sheathed heater, a sheathed heater and a hot air, and the like may be used.

The thickness of the resist film after drying in this manner was 7.0 μm in both the first and second coatings, and there was no variation in the direction of the metal sheet 1. In the first application, the interval between the pipe doctor 12 and the metal sheet 1 was set to about 80 μm,
In the second application, the resist materials 13 and 13 'were applied at a setting of about 120 .mu.m.
m, the second film thickness was 8.4 μm, and the film thickness of the resist film could be set without changing the viscosity, the transport speed, and the drying temperature of the resist materials 13 and 13 ′ only by changing the intervals.

After forming a resist film of 7.0 μm on both sides of the metal sheet 1 having a length of about 300 m as described above, in the next exposure step, a predetermined printing pattern is used to reduce the distance from the distance of about 1 m to 5 k.
Exposure is performed for about 1 minute using a W ultra-high pressure mercury lamp. Furthermore,
The development is carried out for 1 minute in a spray system at a pressure of 1.0 kg / cm ^{2 in} hot water of about 40 ° C., dried in an atmosphere of 150 ° C. for about 2 minutes, and further burned in an atmosphere of about 200 ° C. for about 1.5 minutes.

Through the above steps, the metal sheet 1 in which the corresponding portion where the opening is to be formed is exposed, that is, the material for the shadow mask is obtained.

Next, in the etching step, for example, a liquid temperature of 67 ° C. and a specific gravity of 1.467
Using the ferric chloride adjusted as described above as an etchant, etching is performed by jetting it from a nozzle arranged at a position of about 300 mm from the resist film. After a predetermined opening is obtained by etching, wash with water and 1 kg of 90% NaOH 1.5% aqueous solution.
The remaining resist film is removed by spraying at a pressure of / cm ² for about 3 minutes, followed by washing and drying to obtain a flat mask.

The shadow mask thus obtained has desired openings and is excellent in uneven quality.

(Modification) According to the present invention, since a resist film can be formed on each side of a thin metal plate, it is easy to make the small hole side thin and the large hole side thick, for example. Also in the two-stage etching in which the etching time differs depending on the conditions, the resist film on the small hole side can be thinned and the resolution of the resist film can be increased, which is very effective.

Further, a resist film having a different composition between the large hole side and the small hole side can be formed.

In the above embodiment, the coating method using a pipe doctor was described, but in addition, a coater generally used for one-side coating, such as a knife coating method, a bar code method, and a reverse roll coating method, is used. Of course, a resist film can be formed.

〔The invention's effect〕

According to the present invention, when a resist film having a desired film thickness is formed on a metal thin plate, a required resist material application amount is obtained from a solid content of the resist material, and an interval corresponding to this thickness is set to a pipe doctor and a metal thin plate. It only needs to be provided between the surfaces. In other words, an arbitrary resist film thickness can be obtained by changing the interval, and if the interval is constant, the resist film thickness does not change even if the transport speed of the metal sheet changes. Further, since the application of the resist material is performed on the upper portion of the thin metal plate, there is no flow of the resist material, and even when the resist material is dried, the resist material is dried while being fixed to the surface of the thin metal plate. Therefore, the resist film thickness unevenness due to the flow of the resist material or the dripping does not occur anywhere in the width direction and the length direction of the metal sheet.

Further, in the conventional method, a resist film having a desired film thickness is formed based on a rule of thumb based on a balance between a dripping speed and a drying speed of a resist material. Just set the interval with
It has the advantage that process control is very easy.

Further, in the conventional method, in order to increase the transfer speed of the thin metal plate and increase the efficiency of forming a resist film per unit time, it is necessary to lengthen the drying oven in substantially proportion to the transfer speed. On the other hand, according to the present invention, without dripping of the resist material, the solid content of the resist material is increased, the amount of solvent is reduced, and the distance between the pipe doctor and the surface of the metal sheet is reduced, so that the drying furnace If the lengths are the same, there is an advantage that the conveying speed of the metal sheet can be greatly increased.

[Brief description of the drawings]

FIG. 1 is a schematic structural view showing a method of manufacturing a shadow mask according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing a general shadow mask, and FIGS. 3 (a), (b), ( c)
FIG. 4 is a sectional view showing a general method of manufacturing a shadow mask, and FIGS. 4 and 5 are schematic structural views showing a conventional method of manufacturing a shadow mask. 1 ... continuous strip metal sheet, 10 ... turn roller, 11,11 '... backup roller, 12,12' ... pipe doctor, 13,13 '... resist material, 14,14' ... dam 15, 15 '…… Drying oven.

Claims (2)

(57) [Claims] (1) After rinsing and degreasing both main surfaces of a continuous strip-shaped metal sheet,
A first step of forming a photosensitive resin layer by applying and drying a photosensitive resin liquid, and a second step of forming a predetermined fine hole pattern in the photosensitive resin layer by photographic exposure, A third step of forming fine holes in the continuous strip-shaped metal sheet by etching; and a third step of manufacturing a shadow mask, wherein the first step is to transport the continuous strip-shaped metal sheet in a horizontal direction, First, the photosensitive resin liquid is applied to one main surface as a first application, and then the coated surface is dried with the applied surface facing upward. Then, the continuous strip-shaped metal sheet is inverted, and the other main surface is applied as a second application. A method for manufacturing a shadow mask, comprising: applying the photosensitive resin liquid to a surface of the substrate; and drying the liquid with the second surface applied upward. 2. The method according to claim 1, wherein both main surfaces of the continuous strip-shaped metal sheet are degreased and washed with water.
A first step of forming a photosensitive resin layer by applying and drying a photosensitive resin liquid, and a second step of forming a predetermined fine hole pattern on the photosensitive resin layer by photographic exposure, A third step of forming fine holes in the continuous strip-shaped metal sheet by etching; and a third step of manufacturing a shadow mask, wherein the first step is to transport the continuous strip-shaped metal sheet in a horizontal direction, First, the photosensitive resin liquid is applied to one main surface as a first application, and then a pre-stage drying step in which the applied surface is dried with the applied surface facing upward, and then the continuous strip-shaped sheet metal is turned over. A second drying step of applying the photosensitive resin liquid to the other main surface and then drying the second coated surface with the second coated surface facing upward, wherein the first drying step includes at least one of the main steps of the continuous strip-shaped metal sheet. Facing the surface The method of manufacturing a shadow mask, characterized in that the second drying step is performed by a heat source facing only the second coated surface of the continuous strip-shaped metal sheet.