JPH08124479A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE: To enable manufacturing a high-definition shadow mask by measuring transmittance for the calculation of the aperture of each through hole bored in a shadow mask material during etching process, and adjusting etching conditions according to the calculated value. CONSTITUTION: The openings 5 of holes formed in a shadow mask 6 by photoetching are determined by measurement of transmittance so as to adjust etching conditions for a shadow mask material. A 10-W, 16-V halogen lamp is used as a projector head 14 and a circular parallel beam 20mm in diameter is applied from the small hole side. Light transmitted through the openings 5 of the holes are received by a light receiving device (silicon photocell) provided in the opposite position of the large hole side, so that the aperture of each opening 5 is calculated. The calculated value is compared with a desired value for adjustment of the etching conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask, and more particularly to a method for manufacturing a high-definition shadow mask having a small opening diameter.

[0002]

2. Description of the Related Art Conventionally, a high-definition shadow mask used for a color picture tube is manufactured, for example, by the process shown in FIG. That is, as the shadow mask material 1, for example, a roll-shaped low carbon steel plate having a plate thickness of 0.13 mm is used, and both surfaces thereof are degreased,
After surface conditioning and washing, a water-soluble photosensitive solution consisting of casein or polyvinyl alcohol and ammonium dichromate is applied to both surfaces and dried to form a photoresist film 2. Next, as shown in FIG. 3A, a positive pattern mask 13a having a small hole image is formed on one surface of the shadow mask material 1.
Then, a positive pattern mask 13b having a large hole image is closely exposed on the other surface. After that, by performing a developing treatment with hot water to dissolve the unexposed and uncured photoresist film, the shadow mask material 1 having the small circular hole resist film 2a and the large circular hole resist film 2b on the front and back sides is obtained.

After that, the resist film 2 is subjected to a hardening treatment and a burning treatment, and first-stage etching is performed from both front and back surfaces. The etching solution is a ferric chloride having a Baume concentration of 35 to 50, and spray etching is generally performed at a spray pressure of 1.5 to 3.5 kg / cm ² . In this first etching step, as shown in FIG. 3B, it is important to stop the etching progress on the way. Further, in this first etching step, there is also a method in which a protective film is attached to the surface of the shadow mask material 1 having the resist film 2b having a large circular hole, and the shadow mask material 1 is etched halfway only from the small circular hole side.

Next, as shown in FIG. 3C, an etching prevention layer 4 is formed by coating so as to completely fill the recess 3a on the side of the small circular hole formed by the preceding etching. Subsequently, as shown in FIG. 3D, a second etching step of etching the shadow mask material 1 only from the large circular hole side is performed,
An opening 5 is formed so as to penetrate from the large circular hole side to the small circular hole. Finally, the etching prevention layer 4 and the resist film 2 are peeled off,
It is washed with water and dried to obtain the high-definition shadow mask 6 shown in FIG.

In this process, it can be said that the side etching phenomenon, which cannot be avoided by the photoetching method, is suppressed on the small circular hole side. That is, by filling the etching prevention layer in the concave portion on the side of the small circular hole, the small circular hole is not side-etched in the second etching step,
An accurate small hole pattern in the first etching step can be maintained. Therefore, for example, it is possible to open a hole having a hole diameter smaller than the thickness of the material metal plate.

[0006] Usually, the aperture size of the penetrating portion of the aperture 5 in the manufactured shadow mask is manually measured by using a microscope or the like. However, the manual inspection of the aperture size has the following problems.

That is, since the measurer uses the scale provided on the lens of the microscope to read the dimensions,
There is a problem that the measurement accuracy is poor due to a reading error caused by the measurer. This is because when the scale is calibrated only up to, for example, 10 μm, each measurer reads the measurement in increments of 1 μm, and therefore the measured values differ due to individual differences and the measurement accuracy is poor. Further, since the inspection is time consuming due to manual work, work efficiency is poor, and skill is required, there is a problem that the number of inspectors cannot be easily increased. Therefore, even if you try to change the opening diameter by adjusting the etching conditions in the etching process after inspection,
Since there are variations in measurement accuracy, it is difficult to obtain correct adjustment conditions, and variations occur in the aperture size, and there is a time loss until the conditions are set.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a high-definition shadow mask which does not have the above-mentioned problems.

[0009]

That is, according to the present invention, at least one surface of a plate-shaped shadow mask metal material having a resist film on which both surfaces are partially exposed according to a predetermined pattern is etched. Then, a first etching step of forming a concave portion on at least this one surface of the metal exposed portion, and an etching prevention layer is applied to one surface having the concave portion formed in the first etching step, and the concave portion is formed. A step of filling the inside with an etching prevention layer, and etching a surface opposite to the surface on which the etching prevention layer is provided, and a circular concave hole leading from this opposite surface to a concave portion formed on the one surface. In the production of a high-definition shadow mask having at least a second etching step for forming and a film peeling step for removing the etching prevention layer and the resist film, After the film process, the concave hole portion is irradiated with light from one surface of the shadow mask material, and a light receiving device is provided at a position opposite to the other surface of the shadow mask material. The light transmittance is measured, and the opening diameter of the recessed hole is determined based on the fact that the ratio of the area of the opening per unit area is proportional to the light transmittance. The above problem is solved by providing a method for manufacturing a shadow mask, which is characterized in that adjustment is performed.

As the irradiation light used in the present invention, it is desirable to use a light source having a property of not transmitting to a shadow mask material such as infrared rays, ultraviolet rays, or high frequency fluorescent lamps.

Next, the irradiation light is preferably parallel light in order to accurately measure the light transmittance, and the light irradiation to the shadow mask material may be performed from either the large hole or the small hole surface.

The present invention will be described in detail below with reference to the drawings. FIG. 1 illustrates an essential part of an embodiment of the present invention, and shows a cross-section of a shadow mask 6 having a circular hole formed in the above-mentioned (conventional method). In the present invention, the light projecting head 14 is used from one side of the shadow mask 6 to irradiate the concave holes in a certain area with light. Next, the light receiving device 15 is provided on the other opposite surface, and the light transmitting device receives the light transmitted through the concave hole of the shadow mask 6 to measure the light transmittance of the shadow mask 6.

The light transmittance described here is defined as follows. That is, in FIG. 1, if there is no aperture in the shadow mask 6 and the light emitted from the light projecting head 14 is completely shielded and no light is incident on the light receiving device 15, the light transmittance is 0. %. Next, when no object is placed between the light projecting head 14 and the light receiving device 15 under the same conditions and all the irradiation light enters the light receiving device, the light transmittance is 100%.
Next, as shown in FIG. 1, a shadow mask 6 having an opening 5 was placed, and the ratio of the transmitted light was expressed in%, which was defined as the light transmittance. As the light receiving device 15 for measuring the above-mentioned light transmittance, for example, a device that can measure the light intensity value of a photoelectric tube or the like by changing it into a current can be used.

Here, the present inventors pay attention to the fact that the light transmittance of the shadow mask 6 measured above is proportional to the ratio of the area occupied by the openings to the area of the region where the shadow mask is irradiated with light. did.

This will be further described with reference to the drawings. FIG. 2 is an enlarged plan view showing a part of a region where the shadow mask 6 is irradiated with light. The circular pattern in FIG. 2 shows the openings 5 penetrating both sides of the shadow mask 6, and the other portion is the shadow mask 6, which is a region that becomes a light-shielding portion during light irradiation. Note that the shape of the concave portion around the opening 5 is omitted for easy viewing of the drawing.
The positive pattern mask 13 used in the above-mentioned (Prior art) has the vertical pitch V between each circular pattern when it is formed.
And a horizontal pitch H is determined. The apertures manufactured by using this positive pattern also have the relationship of the vertical pitch V and the horizontal pitch H with the adjacent apertures. As a result, the individual openings are included in the rectangular regions (hereinafter, referred to as cells) each having the length V and the width (H / 2), which are shown by the diagonal lines in FIG.

Here, it can be considered that the cells 16 are gathered in the light irradiation region on the shadow mask 6. Therefore, the ratio of the area occupied by the openings in the area of the light irradiation region can be translated into the ratio of the openings 5 occupied in one cell 16. For example, a light transmittance of 0% means that the cell 16 has no holes and does not transmit any light, and a light transmittance of 100% means that the cells 16 are all holes and all light is transmitted. Is shown.

From the above, when the measured value of the light transmittance of the concave portion in the light irradiation region is T%, the opening diameter D of the opening 5 can be obtained by the following mathematical formula.

That is, the area A of the opening is (Equation 1).

[0019]

[Equation 1]

Next, the area B of the cell 16 becomes (Equation 2).

[0021]

[Equation 2]

Next, as described above, the equation (3) holds from the fact that the light transmittance T is proportional to the ratio of the area occupied by the openings 5 in the area of the cell 16.

[0023]

(Equation 3)

Therefore, the aperture diameter D is obtained from (Equation 4) from (Equation 1), (Equation 2) and (Equation 3).

[0025]

[Equation 4]

At the edge of the light irradiation area, some cells 16 are included in the light irradiation area and are not completely included in the light irradiation area. Therefore, a slight measurement error may occur in the aperture diameter D obtained by the above equation. May occur. Therefore, in order to average this error and reduce it as much as possible, as many cells 16 as possible should be placed in the light irradiation area.
That is, it is preferable that the light irradiation region is large to some extent. However, in the shadow mask, the pattern pitch and the aperture diameter may be different between the central portion and the peripheral portion, and it is conceivable that if the irradiation light region is made too large, the measurement error will rather increase. Therefore, it is desirable to appropriately set the light irradiation region in consideration of the specifications such as the pattern pitch of the shadow mask and the size of the pattern. By the way, in the examples described below, the light irradiation area was actually changed to perform measurement, and the light irradiation area was empirically set to a circle having a diameter of 20 mm, as a value with which the measurement error is small and the present invention can be sufficiently implemented practically. .

Next, when the aperture diameter D of the aperture 5 measured by the above method is different from the target value, the following etching conditions are adjusted. For example, when the aperture diameter D is smaller than the target value, in order to increase the etching amount of the shadow mask material, for example, when the etching means is a spray method, there is a method of increasing the spray pressure,
Also, a method of lengthening the etching time may be used. On the contrary, when the opening diameter D is larger than the target value, in order to decrease the etching amount contrary to the above, for example, when the etching means is the spray method, the spray pressure is weakened or the etching time is reduced. One method is to shorten it.

[0028]

According to the present invention, the accurate measurement of the aperture diameter of the aperture opened in the shadow mask by the etching process can be performed in a short time based on the measurement of the light transmittance.
The setting for adjusting the etching conditions in the etching process can be efficiently performed. As a result, the conventional manufacturing method, that is, the method of manually measuring the opening diameter of the opening and then adjusting the etching conditions of the etching step, the correct adjustment conditions can be obtained due to the variation in the measurement accuracy. Therefore, it is possible to prevent variation in the aperture size due to failure of the opening and time loss until the adjustment condition is set.

[0029]

EXAMPLE An example will be described below with reference to FIG. The shadow mask material 1 was a long metal plate supplied from a winding roll, and was a low expansion amber material having a plate thickness of 0.13 mm. The shadow mask material 1 having the small-hole resist film 2a and the large-hole resist film 2b on the front and back sides was obtained by performing the steps already described in (Prior Art).

Then, the shadow mask material 1 is passed through the first etching chamber 7 shown in FIG. 1, and ferric chloride having a Baume concentration of 40 is etched from the spray nozzles 8 installed above and below at a spray pressure of 2.0 kg / cm ² . As a liquid, it was sprayed and the front and back of the shadow mask material 1 were subjected to a certain etching to form recesses 3a and 3b as shown in FIG. 4 (b).

Next, with respect to the shadow mask material 1 which has passed through the first etching chamber 7, for example, a roll coater 9 was used to apply an etching prevention layer 4 to the small hole surface as shown in FIG. 4 (c).

The shadow mask material 1 on which the etching prevention layer 4 had been applied was passed through the second drying / curing area 10 and passed through the second etching chamber 11. The spray nozzle in the second etching chamber 11 sprays the etching liquid from the large hole side, that is, from the lower side.
Ferric chloride with a Baume concentration of 40 was sprayed as an etching solution at 2.0 kg / cm ² . In this way, a through hole communicating from the large hole side to the small hole was opened in the concave portion to obtain the state shown in FIG. 4 (d).

Next, with respect to the shadow mask 6 which has passed through the film stripping chamber 12 and has been stripped, the diameters of the through holes were measured at the center and four corners of the shadow mask 6 according to the present invention.

That is, a 10 W 16 V halogen lamp was used as the projection head 14, and circular parallel light with a diameter of 20 mm was irradiated from the small hole side. Then, the light transmitted through the opening of the recessed hole,
A silicon photocell (trade name "S1336-8BQ" manufactured by Hamamatsu Photonics KK is used as a light receiving device 15 provided at a position opposite to the large hole side.
") To obtain the aperture diameter of the aperture.

Next, since the opening diameter of the opening opened in the obtained shadow mask 6 was smaller than the target value, the etching solution in the second etching chamber 11 was changed in order to increase the opening diameter of the opening. Spray pressure 0.5kg /
Adjustment was made to strengthen the cm ² . As a result, an appropriate aperture diameter was obtained for the apertures of the shadow mask 6 manufactured subsequently.

[0036]

As described above, according to the method for manufacturing a shadow mask of the present invention, it is possible to accurately measure the opening diameter of the through hole opened in the shadow mask material by the etching process.
Since it becomes possible in a short time based on the light transmittance, the setting for adjusting the etching conditions in the etching process can be efficiently performed. As a result, the conventional manufacturing method, that is, the method of manually measuring the opening diameter of the through hole and then adjusting the etching conditions in the etching step, the correct adjustment conditions are obtained due to the variation in measurement accuracy. The present invention has a practically excellent effect in obtaining a high-definition shadow mask, such that variation in the aperture size occurs without being prevented, and a time loss until setting adjustment conditions can be prevented.

[0037]

[Brief description of drawings]

FIG. 1 is a sectional view showing an essential part of an embodiment of a method for manufacturing a shadow mask of the present invention.

FIG. 2 is a plan view showing an example of calculating an aperture diameter of a shadow mask according to the present invention.

FIG. 3 is an explanatory view showing an example of a method of manufacturing a shadow mask in the order of steps.

FIG. 4 is an explanatory view showing an embodiment of a method for manufacturing a shadow mask of the present invention.

[Explanation of symbols]

 1 Shadow Mask Material 2 Resist Film 3 Recess 4 Etching Prevention Layer 5 Opening Hole 6 Shadow Mask 7 First Etching Chamber 8 Nozzle 9 Roll Coater 10 Drying / Curing Area 11 Second Etching Chamber 12 Stripping Chamber 13 Pattern Mask 14 Light Projection Head 15 Light receiving device 16 cells

Claims (3)

[Claims] 1. A metal on at least one of the surfaces of a plate-shaped shadow mask metal material having a resist film on which a metal film is partially exposed according to a predetermined pattern is etched on at least one surface. A first etching step of forming a concave portion in the exposed portion; a step of applying an etching prevention layer on one surface having the concave portion formed in the first etching step and filling the inside of the concave portion with the etching prevention layer; A second etching step of etching a surface opposite to the surface provided with the etching prevention layer to form a circular concave hole leading from this opposite surface to a concave portion formed in the one surface; In the production of a high-definition shadow mask having at least an etching prevention layer and a film removing step of removing a resist film, one of the shadow mask materials after the film removing step is used. More light is irradiated to the concave hole portion, a light receiving device to a position corresponding to the other surface of the shadow mask material provided to measure the light transmittance of the light transmitted through the concave hole,
A shadow characterized in that the opening diameter of the concave hole is determined based on the fact that the ratio of the area of the opening per unit area is proportional to the light transmittance, and then the etching conditions of the etching step are adjusted. Mask manufacturing method. 2. The method for producing a shadow mask according to claim 1, wherein infrared, ultraviolet, or high-frequency fluorescent lamp is used as the irradiation light. 3. The method for manufacturing a shadow mask according to claim 1, wherein the irradiation light is parallel light.