JPH0615718B2 - Method for manufacturing shed mask - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a shadow mask for a color cathode ray tube.

[Technical background of the invention and its problems]

The color cathode ray tube has a shadow mask that faces a fluorescent surface formed inside the front surface of the envelope and has a large number of through holes regularly arranged inside thereof. This shadow mask is used for forming a fluorescent screen, and controls so that the electron beam emitted from the electron gun is correctly incident on the fluorescent screen.

Conventionally, this shadow mask is manufactured by coating a photosensitive resin on both sides of a metal plate having a thickness of about 0.15 mm, and exposing the resin film through a pair of negatives having a pattern corresponding to the through holes of the shadow mask. By baking and developing, a resist film having an opening region corresponding to the through hole is formed. After a while,
It is formed by simultaneously spraying an etching solution on both sides of this metal plate.

In order to form the required shadow mask, the pair of negative patterns have different sizes, and the through holes formed in the metal plate are etched from one surface and a small recessed hole from the other surface. The large recesses have a shape penetrating at their bottoms.

In a color cathode ray tube generally used for reproduction of color broadcasting, the through holes of the shadow mask are larger than the plate thickness of the metal plate, and can be easily manufactured by the double-sided simultaneous etching method. However, as a shadow mask used for a display that requires a higher resolution, a high-definition shadow mask having a through hole smaller than the thickness of a metal plate is used because of the side etching which is inevitably generated. Is extremely difficult to manufacture.

Japanese Examined Patent Publication (Kokoku) No. 57-26345 discloses a method for manufacturing such a high definition shadow mask. In this method, the etching is divided into two steps, front and rear, and in the preceding step, the metal plate is etched from both sides until the small concave hole on one surface becomes approximately the same size as the corresponding portion of the through hole of the required shadow mask. After that, an etching resistance layer is formed on one surface so that the small recesses are filled with an etching resistant agent, and in a subsequent stage, etching is performed only from the other surface to penetrate the recesses on both surfaces. In this method, the small concave holes formed in the etching in the former stage are filled with an anti-etching agent to prevent the progress of the etching in the latter stage, and only the large concave holes are etched in the latter stage, so the size of the through hole is large. The required shadow mask is obtained with less side etching of the small recesses involved.

In addition, in Japanese Patent Publication No. 51-9035, etching is performed before and after 2
Divided into stages, in the previous stage, one surface (small concave hole side) is pasted with a protective sheet such as rubber or organic film to prevent etching, and only the surface of the other large concave hole side is etched, and then, A method is disclosed in which the protective sheet is peeled off and etched from both sides to form through holes. In this method, only the large concave holes are etched in the previous stage to reduce the plate thickness of the portion where the through holes are formed, and then the etching is performed from both sides in the subsequent stage, so the through holes are formed in a metal plate thinner than the actual metal plate. This is the same as in the case, and the required shadow mask can be obtained by reducing the side etching of the small concave hole.

Therefore, when manufacturing a high-definition shadow mask in which the through holes are smaller than the plate thickness, the plate thickness and the size of the through holes can be kept constant by using the equipment capable of performing the etching in two steps before and after as described above. As long as the above conditions are satisfied, the required shadow mask can be continuously manufactured by keeping the etching conditions, that is, the feed rate of the metal plate, the temperature of the etching solution, the specific gravity, and the concentration constant. However, if the through holes have the same size but different plate thicknesses, for example, if the plate thickness becomes thicker, the feed rate of the metal plate may be reduced and the etching time may be lengthened in response to the increased etching amount. It is necessary to change the composition of the etching solution to increase the etching rate.

However, if the feeding speed of the metal plate is slowed down, in the method of Japanese Patent Publication No. 57-26345, the amount of etching in the preceding stage increases, and the small concave holes that determine the size of the through holes become too large. In order to avoid this, the opening area of the resist film must be made small so that excessive side etching does not occur even if the feed rate is slowed, and for that purpose, the negative pattern must be made small. , Negative quality deteriorates. Further, the ratio of the exuded portion of the photosensitive resin after baking and development to the open area increases, and mask unevenness occurs because the size and shape of the through holes are not constant. Furthermore, when the anti-etching agent is embedded after the etching of the previous stage, the resist film protruding above the small recessed holes by the side etching hinders the filling of the anti-etching agent, and the through-hole shape becomes irregular. Therefore, in order to form a required shadow mask, it is necessary to reduce the side etching of the small concave hole and increase the etching of the latter stage in the former stage etching regardless of the plate thickness.

Further, in the method disclosed in Japanese Patent Laid-Open No. 51-9035, since the amount of etching in the subsequent stage is increased, the side etching of the small concave holes becomes too large. Therefore, in order to form the required through holes, it is necessary to reduce the opening area of the resist film on the small recess side. However, in order to do this, Japanese Patent Publication No. 57-2
As in the case of Japanese Patent No. 6345, the negative pattern must be made small, and as a result, the mask quality is degraded. Therefore, in order to form a required shadow mask, it is necessary to increase the etching of the large concave holes in the front stage and decrease the side etching of the small concave holes in the double-sided etching in the rear stage.

However, in the etching apparatuses disclosed in the above-mentioned publications, since the etching chamber ratio of the front stage and the rear stage is constant, the etching ratio of the front stage and the rear stage cannot be changed only by changing the feed rate of the metal plate. In order to make the etching ratio of the former stage and the latter stage variable, for example, a shield plate may be attached to the chamber so that the etching chamber length can be changed. However, such an etching apparatus has a high manufacturing cost. Moreover, since the effective chamber length is changed, the utilization efficiency of the device is poor. In addition, the temperature of the etching solution supplied to each etching chamber, the specific gravity,
If an attempt is made to change the etching ratio between the former stage and the latter stage by changing the concentration or the like, it takes a long time to change the etching ratio, and etching must be stopped during that period, resulting in a significant decrease in production efficiency.

[Object of the Invention]

An object of the present invention is to obtain a method capable of easily producing a shadow mask of a color cathode ray tube, particularly a high definition shadow mask having through holes smaller than the plate thickness dimension.

[Outline of Invention]

After forming a resist film having a large number of regularly arranged opening areas on both sides of a metal plate, and the size of the opening area of one surface is different from the size of the opening area of the other surface. In a method of manufacturing a shadow mask in which the metal plate is etched to form through holes in a large number of opposed open areas, the etching is divided into two stages, the etching ratio of the former stage and the latter stage is the etching solution. By changing the temperature, the required shadow mask can be easily manufactured.

Example of Invention

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

A steel plate wound in a hoop shape having a constant width and a constant length is degreased and washed while being rewound, and a photosensitive resin is applied to both surfaces of the steel plate and dried to form a photosensitive resin film. After that, the photosensitive resin on both sides is exposed by closely contacting a pair of negatives having different patterns of different sizes formed at corresponding positions, and after baking the negative pattern on the resin film, it is developed. A resist film is formed on both surfaces of the steel sheet, the resist films facing each other and having open areas of different sizes.

The method of forming the resist films on both sides of the steel plate is the same as that of the conventional shadow mask and is known, and therefore a more detailed description thereof will be omitted.

The steel plate on which the resist film is formed is then etched. FIG. 3 shows the etching apparatus. This etching device is used to sequentially perform the first stage etching in the running direction of the steel plate (1).
(2), water washing (3a), resist film peeling (4), water washing (3b), drying (5
a), anti-etching agent coating (6), drying (5b), post-etching (7) chambers are provided, and a plurality of chambers are provided above the pre-etching chamber (2) and below the post-etching chamber (7). Individual etchant spray nozzles (8a), (8b)
However, a plurality of water spray nozzles (9) are provided above and below the water washing chambers (3a) and (3b), and a plurality of stripping solution spray nozzles are provided above the resist film stripping chamber (4). (10) is provided. Also the drying chamber (5a),
A heat source (11) is provided above and below (5b), and an etching resistant coating device (12) is installed in the etching resistant coating chamber (6). As the anti-etching agent, milk casein, polyvinyl alcohol, epoxy-based dispersion liquid, alkyd resin or a mixed solution thereof is used, and as the coating device (12), knife coat, roller coat, spray coat, dip coat, An apparatus suitable for the physical properties of the etching resistant agent used, such as bar coat, is installed. The long steel plate (1) is guided by a roller (not shown) and travels in each chamber with one surface having a small opening area formed upward. This steel plate (1) moves from the previous etching chamber (2) to the etching resistant material application chamber (6).
In order to protect the other surface where the large open area is formed, the long protective film is placed in front of the pre-etching chamber (2) and behind the etchant-resistant coating device (6). A device (14) for supplying (13) to bring it into close contact with the other surface and peeling it off is provided.

The etching chambers (2) and (7) in the front and rear stages are
As shown in Fig. 1, each etching tank (1
Have 6). The etchant in these tanks (16) is pumped to the nozzles (8a) or (8b) in the etching chamber (2) or (7) by the pump (17), and each nozzle (8a), (8b)
The etching liquid sprayed from the above is returned to the tank (16) from the bottom of each chamber (2), (7). Also, on the outlet side of the pump (17), the pump (17)
A bypass (18) is provided for returning a part of the etching liquid pumped by the tank to the tank (16). Above nozzle (8
The etching solution supplied to (a) or (8b) is passed through the heat exchanger (19) provided in the etching solution circuit immediately before entering the etching chamber (2) or (7), and the bypass (18). The etching liquid flowing back to the tank (16) passes through the heat exchanger (20) provided in the middle of the bypass (18).
The temperature is adjusted by. These heat exchangers (19), (20) are
As shown in FIG. 2, it is configured to exchange heat with steam or cold water supplied through valves (21a) and (21b) that are opened and closed by a control signal sent from a control device (not shown). , The temperature of the etching liquid supplied to the nozzle (8a) or (8b), in the arithmetic processing unit of the control device,
In order to carry out the required etching, the specified etching solution temperature previously obtained by experiments etc. and the tank (1
Calculate the difference in the temperature of the etching solution in the tank obtained from the temperature sensor (22) attached to the heat exchanger (1).
9) Specified etchant flow rate through the chamber
The flow rate of steam or cold water required for heating or cooling is calculated from the supply amount of the etching solution to (2) or (7), and the valve is based on the control signal sent from the control unit constituting the control device. Open and close (21a) or (21b),
And a temperature sensor mounted on the outlet side of the heat exchanger (19)
The output of (23) is fed back to the control device. The temperature of the etching solution in the tank (16) is
Although kept constant by (20), if the heat exchanger (19) is controlled at the same time as the heat exchanger (19) is controlled based on the same control signal, the load on the heat exchanger (19) is lightened, More precise temperature control becomes possible. The specified flow rate of the etching solution flowing through the heat exchanger (19) is determined by opening and closing the valves provided in the etching solution circuit, for example, the valves (24a) and (24b), by a flow meter provided in the circuit. Can be done at. Further, in the above control device, the difference between the specified etching solution flow rate and the etching solution flow rate flowing through the flowmeter is calculated,
It is optional to control the valves (24a), (24b) and the like to automatically open and close based on the difference.

In the etching solution refluxed from the etching chamber (2) or (7), ferrous chloride is increased and the etching ability is lowered. Therefore, in order to return this to ferric chloride having etching ability, the tank Chlorine gas is injected into (16). Further, water is added to control the increase in specific gravity due to dissolution of the steel sheet (1), and hydrochloric acid is added to supplement the consumption of free hydrochloric acid in the etching solution. The etching chamber (2) or (7) shown in FIG. 1 has nozzles (8a) and
(8b) is provided, these are (25a), (25b) placed in front of it, by appropriately opening and closing, the etching chamber of the front stage (2) or the etching chamber of the rear stage
It is obvious that it will have the same function as (7).

The steel sheet (1) having the resist film formed on both surfaces is etched as follows.

The steel plate (1) running with one surface on which a small opening area is formed faces up, as shown in FIG. 4 (A), first before entering the etching chamber (2) of the previous stage. That is, the protective film (13) is attached to the other surface where the large opening area (27) is formed, and the etching chamber (2) of the previous stage is attached.
to go into. The steel plate (1) that has entered the etching chamber (2) in the preceding stage is sprayed with an etching solution adjusted to a specified temperature by a heat exchanger (19) from a spray nozzle (8a) provided on the upper part of the steel plate (1), (B) As shown in the figure, a small concave hole of a predetermined size corresponding to the small opening area (28) on one surface
(29) is formed. In this etching in the former stage, the other surface is not etched because it is protected by the protective film (13).

The steel sheet (1) that has passed through the etching chamber (2) in the previous stage is then washed with water while passing through the water washing chamber (3a), and the resist provided on one surface thereof in the next resist film stripping chamber (4). The membrane (30) is removed. The steel plate (1) from which the resist film (30) on this one surface has been removed is used in the next washing chamber.
It is washed again with water in (3b) and then dried in the next drying chamber (5a). The dried steel plate (1) was then subjected to the etching-resistant agent application chamber (6) in such a manner that the above-mentioned one surface had a uniform film thickness and was completely filled in the small recesses (29). Is applied and dried in the next drying chamber (5b). When exiting the etch resistant coating chamber (6), the steel plate (1)
The protective film (13) covering the other side of the is separated.

A steel plate (1) on which an anti-etching agent was applied to the one surface and the protective film (13) covering the other surface was removed
Next, in the subsequent etching chamber (7), from the spray nozzle (8b) provided in the lower part of the etching chamber, an etching solution adjusted to a specified temperature by a heat exchanger (19) independently of the preceding etching. Is sprayed, and as shown in (C), a large concave hole (31) corresponding to the large open area (27) formed on the other surface is formed. The large concave hole (31) penetrates the bottom of the small concave hole (29) formed on one surface at the bottom. The steel plate (1) that has finished the etching of the latter stage is
After that, the anti-etching agent coating (3
2) and the resist film (33) formed on the other surface are removed, and as shown in (D), a through hole (3
It becomes the required shadow mask with 4).

As described above, the etching of the shadow mask is divided into two steps, that is, before and after, and the etching ratio of the former stage and the latter stage is changed depending on the temperature of the etching solution, so that the required shadow mask can be easily manufactured. In addition, a heat exchanger (19) was installed in front of each etching chamber (2), (7) so that the temperature of the etching solution could be changed instantaneously. The shadow mask can be continuously manufactured without stopping the etching.

Next, another embodiment will be described.

As shown in FIG. 5, the etching apparatus used in this embodiment is sprayed from a spray nozzle (36a) provided in the lower part of the etching chamber (2) in the front stage, and in the etching chamber (7) in the rear stage. The spray nozzles (36b) and (36c) provided on both the upper and lower sides are used for spraying. The steel plate (1) is protected by a protective film (13) with one surface having a small opening area facing upward and before entering the etching chamber (2) in the preceding stage. This state is shown in FIG. 6 (A). In the former etching chamber (2), the chamber is the same as in the previous embodiment.
The etching solution adjusted to the specified temperature by the heat exchanger provided in front of (2) is sprayed from the bottom,
(B) As shown in the figure, a large recessed hole (37) of a predetermined size corresponding to the large open area (27) formed on the other surface of the steel plate (1)
Is formed. The protective film (13) is separated from the steel plate (1) before it enters the etching chamber (7) in the next subsequent stage. In the latter etching chamber (7), the etching solution adjusted to the specified temperature by the heat exchanger is sprayed simultaneously from the upper and lower parts of the etching chamber (7), and the steel plate (1)
Is etched from both sides to form required through holes (34) as shown in FIG. The resist films (30) and (33) on both surfaces of the steel plate (1) are then peeled and removed.

〔The invention's effect〕

Since the etching of the shadow mask is divided into two steps, front and rear, the etching ratio of the front and rear stages is changed according to the temperature of the etching solution, so the required shadow mask, such as a shadow mask with through holes smaller than the plate thickness, can be easily manufactured. can do.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an etching liquid circuit of an etching chamber, FIG. 2 is a configuration diagram of a heat exchanger as one of the configurations, and FIG.
FIG. 4 is a block diagram showing an embodiment of an etching apparatus, FIG.
(A) to (D) are explanatory views of an etching method using the etching apparatus shown in FIG. 3, FIG. 5 is a configuration diagram showing another embodiment of the etching apparatus, and FIGS. 6 (A) to (C) are drawings. It is explanatory drawing of the etching method using the 5th illustrated etching apparatus. (1) …… Steel plate (2) …… Previous etching chamber (3a), (3b) …… Water washing chamber (4) …… Resist film stripping chamber (5a), (5b) …… Drying chamber (6)… … Etching agent coating chamber (7) …… Post-stage etching chambers (8a), (8b) …… Spray nozzle (13) …… Protective film, (16) …… Etching tank (17) …… Pump, (18 ) …… Bypass (19) …… Heat exchanger, (20) …… Heat exchanger (22) …… Temperature sensor, (23) …… Temperature sensor (27) …… Large open area, (28)… … Small open area (29) …… Small recess, (30) …… Resist film (31) …… Large recess, (33) …… Resist film (34) …… Through hole

Claims (5)

[Claims] 1. A resist film having a large number of regularly arranged aperture areas on both sides of a metal plate, the size of the aperture area on one surface being different from the size of the other aperture area. After that, in the method of manufacturing a shadow mask in which the metal plate is etched to form through holes in a large number of opening areas facing each other, the etching is divided into two steps, front and rear, and an etching ratio between the front step and the rear step is set. A method for producing a shadow mask, which is characterized in that the temperature of the etching solution is changed. 2. The two stages of front and rear etching are performed in separate etching chambers each having an independent etching tank, and the temperature of the etching solution supplied from the etching tanks to the etching chambers is different in each etching chamber. The method for producing a shadow mask according to claim 1, wherein the heat mask is adjusted before entering. 3. The temperature of the etching solution supplied to the etching chamber is the difference between the temperature of the etching solution in the etching tank and the designated etching solution temperature, with the temperature of the etching solution on the outlet side of the heat exchanger as a feedback signal, and The method of manufacturing a shadow mask according to claim 2, wherein the heat exchanger is adjusted by automatically controlling the heat exchanger based on the amount of the etching solution supplied to the etching chamber. 4. A part of the etching liquid supplied from the etching tank to the etching chamber via the heat exchanger is etched at the inlet side of the heat exchanger via a heat exchanger different from the heat exchanger. The method for producing a shadow mask according to claim 2, wherein the temperature of the etching liquid in the etching tank is adjusted by returning to the tank. 5. The temperature of the etching solution supplied to the etching chamber is the etching solution in the etching tank using the temperature of the etching solution on the outlet side of the heat exchanger interposed between the etching tank and the etching chamber as a feedback signal. The heat exchanger for adjusting the temperature of the etching solution flowing back to the etching tank from the difference between the temperature and the specified etching solution temperature and the amount of the etching solution supplied to the etching chamber is automatically controlled and adjusted. A method for manufacturing a shadow mask according to claim 4.