JPH03155027A - Material plate for shadow mask - Google Patents

Abstract

PURPOSE:To improve the productivity of a shadow mask and prevent non- uniformity from being produced in the diameter of electron beam passage hole by making the surface roughness of a material plate rougher on its edges in its width direction than on its central portion in its width direction. CONSTITUTION:A material plate 20 for a shadow mask is made of a sheet metal of a strip shape of aluminum killed low carbon copper plate of specified shape and dimensions with its top and back surfaces 21a, 21b made rougher on its edges in its width direction than on its central portion in its width direction. The surface roughness is preferably changed continuously from the central portion to the edges so that a negative original may be brought into close contact with a photosensitive film formed on the surface of the shadow mask material plate 20, starting the close contact from the central portion toward the edges through a vacuum adhesion process to bring the negative original completely close to the photosensitive film within a short period of time. This enables to manufacture a shadow mask without non-uniformity in the diameter of electron beam passage hole with a favorable hole shape and to improve the productivity of the shadow mask.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to a shadow mask material plate for a shadow mask type color cathode ray tube.

(Prior Art) In general, a shadow mask type color cathode ray tube has a three-color phosphor layer that emits blue, green, and red light, which is formed on the inner surface of a panel (2) of an envelope 1), as shown in Figure 3. A shadow mask ( 4
) are provided.

On the other hand, three electron beams (7B), (7c) are placed inside the neck (6) of the funnel (5) that is integrated with the panel (2).
, (7R) is provided. Three electron beams (7B) are emitted from this electron gun (8).

(7G) and (7R) are deflected by the magnetic field of a deflection yoke (not shown) attached to the outside of the funnel (5), and the fluorescent screen (3) is scanned horizontally and vertically through the shadow mask (4). As a result, the structure is formed to display a color image.

The electron beam passing hole of the shadow mask (4) functions as a color selection electrode that selects these three electron beams (7B), (7G), and (7R) and correctly lands them on the corresponding three color phosphor layers. It is something that we have.

In order to display an image with good color purity on the phosphor screen (3), as shown in FIG. With respect to the electron beams (7B>, (7G), and (7R), it is important to reduce the number of electron beams that collide with the side wall of the electron beam passage hole (9) and reflect toward the phosphor screen.
Therefore, the aperture diameter Ds on the phosphor screen side is changed to the aperture diameter Ds on the electron gun side.
It is formed in a shape that is larger than e and has a minimum diameter portion (10) at a position close to the electron gun side port.

Traditionally, such shadow masks have been made by using a band-shaped metal thin plate, such as an aluminum guild low carbon steel plate, as a shadow mask material plate, opening electron beam passage holes (9) by photo-etching, and then cutting the holes into a predetermined size and shape. It is formed by cutting and molding.

To manufacture a shadow mask using this photoetching method, first, a strip-shaped shadow mask material plate of a predetermined width and length is cleaned, and a photosensitive agent is applied to both sides of the material plate and dried to form a photoresist film. Next, a pair of negative master plates, each having a negative pattern of electron beam passage holes formed on a glass substrate, are brought into close contact with the photoresist films (12) on both sides and exposed, thereby printing the pattern of the negative master onto each photoresist film. After that, development is performed to remove unexposed areas by spraying warm water, and water is removed using a surfactant, etc., so that a pattern corresponding to the pattern of the negative master plate is formed on both sides of the strip-shaped shadow mask material plate. Form a resist film. After drying this resist film, burning is performed to harden the resist film. The resist film is manufactured by spraying an etching solution to form a predetermined electron beam passage hole, and then peeling off the resist film using a caustic alkaline solution.

FIG. 5 shows an apparatus for vacuum contact printing in which a negative original plate is printed in close contact with the photoresist film formed on both sides of a shadow mask material plate in the manufacture of the shadow mask. This vacuum contact baking device consists of a pair of frames (
lla), (llb), and this pair of frames (lla), (llb),
A pair of negative master plates (12) placed between a) and (llb)
a), <12b) and their respective negative originals (12a)
, (12b) into vacuum packing (13a), (13
b) Vacuum line for supporting the negative original (
14), and a vacuum line (I5) for adhesion that vacuums the space formed by the frames (lla), (llb) and the negative originals (12a), (12b).

A pair of frames (lla
), (llb) <12a), (12b) separated by the retreat of the photoresist film (Ilb) on both sides.
The shadow mask material plate (17) on which B) has been formed is inserted, and a pair of negative master plates (12a),
(12b) is brought into close contact with each other and then irradiated with light from a light source (not shown).

By the way, this photo sensitivity is 11! If poor adhesion occurs between the photosensitive film (1B) and the negative masters (12a) and (12b) during close contact printing of the negative masters (12a) and (12b) to (1B>), the negative masters (12a) and (12b) will be printed on the photosensitive film (16). The original negative plate (12a).

The periphery of the pattern (12b) bleeds, making it impossible to faithfully transfer the negative pattern, and the diameter of the drilled electron beam passage hole changes and appears uneven, degrading the quality of the shadow mask.

A major reason for the poor adhesion is that the adhesion vacuum line (15) is placed outside the pair of negative master plates (12a) and (12b), and the negative master plate (12a), This is because the peripheral portion of (12b) comes into close contact with the center portion before the center portion, and the passage for suctioning the center portion is closed, and poor adhesion particularly occurs frequently in the center portion.

As a means to prevent this poor adhesion, there is a method of roughening the surface of the shadow mask material plate, but in order to make the surface rough enough to improve the adhesion state, the surface roughness Ra needs to be about 1.0 μm. However, this degree of roughness deteriorates the shape of the electron beam passage hole.

Therefore, conventionally, the surface roughness Ra of the shadow mask material plate could only be roughened to about 0.2 to 0.5 μI, and as a result, the adhesion of the negative master was poor and the time required for adhesion was long. Moreover, due to poor adhesion, the negative pattern is not faithfully transferred, and changes in the diameter of the electron beam passage hole appear unevenly, making it difficult to obtain a shadow mask of good quality.

(Problem to be solved by the invention) As mentioned above, the shadow mask of a color cathode ray tube is
A photo-etching method in which a strip-shaped thin metal plate is used as a shadow mask material plate, a photoresist film is formed on its surface, a negative master plate is closely exposed to the photoresist film, a pattern on the negative master plate is printed, the pattern is then developed, and then etched. However, due to poor adhesion between the photosensitive film and the negative master, the negative pattern is not faithfully transferred, resulting in uneven electron beam passage hole diameters.

As a means to prevent poor adhesion between the photoresist film and the negative or master plate, there is a method of roughening the surface of the shadow mask material plate, but in order to make the surface rough enough to improve the adhesion state, the surface roughness Ra should be set to 1. It is necessary to make it about 0 μ■. However, if the roughness is made to this extent, the shape of the electron beam passage hole deteriorates, so conventionally, the surface roughness R of the shadow mask material plate is
a can only be made rough to about 0.2 to 0.5 μ■, and as a result, the adhesion of the negative master plate is poor, it takes a long time to achieve adhesion, and the negative pattern is not faithful due to poor adhesion. There is a problem in that the electron beam passing holes are not transferred and appear unevenly, making it difficult to manufacture a shadow mask with good quality.

This invention was made in order to solve the above problems, and it is possible to improve the adhesion between the photoresist film and the negative master plate, shorten the time required for adhesion, and improve the productivity of shadow masks. It is an object of the present invention to provide a material plate for a shadow mask that can faithfully transfer a negative pattern without causing poor adhesion and produce a shadow mask that does not cause unevenness in the diameter of electron beam passage holes.

[Structure of the Invention] (Means for Solving the Problems) A plate material having a predetermined width and length is formed, and an electronic pattern is formed by a photoetching method in which a negative pattern is closely exposed to light on a photosensitive resin film formed on the surface of the plate material. In the shadow mask material plate forming the beam passage hole, the surface roughness of the widthwise end portions of the plate material was made rougher than the surface roughness of the widthwise center portion. Preferably, the surface roughness of the plate material varies continuously from the center in the width direction to the ends in the width direction.

(Function) As described above, the surface roughness of the ends in the width direction of the shadow mask material plate is made rougher than the surface roughness of the center part in the width direction, preferably from the center part in the width direction to the ends in the width direction. If the changes are made continuously, when the negative master is brought into close contact with the photoresist film on the surface of the shadow mask material plate by vacuum adhesion, the photoresist film and the negative master are brought into close contact from the center, and the adhesion increases toward the periphery. As a result, the negative master plate can be brought into complete contact with the photoresist film in a short time.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

FIG. 1 shows a cross-sectional view of the surface condition of a shadow mask material plate according to one embodiment. This shadow mask material board (
20) has a plate thickness of 0. It is made of a strip-shaped thin metal plate such as an aluminum killed low carbon steel plate with a width of 800 mm and a width of 800mm, and the front and back surfaces (21a) and (21b) are rougher at both ends in the width direction than in the center part in the width direction. The surface is roughened.

The surface roughness is shown in FIG. 2 by a solid line (22) with the horizontal axis representing the distance from the center in the width direction and the vertical axis representing the roughness.

Note that the broken line (23) is the surface roughness of a conventional shadow mask material plate shown for comparison. This solid line (22
) The surface roughness of the shadow mask material plate shown in ) changes continuously and gently from the center in the width direction to both ends in the width direction. The surface roughness is about 0.3μ, which is almost the same as the surface roughness of
However, the surface roughness at both ends in the width direction is approximately 0.5 μm, whereas the surface roughness of conventional shadow mask material plates is approximately the same as that at the center. .

When the surface of the shadow mask material plate is roughened so that it is rougher at both ends in the width direction than at the center in the width direction, a photoresist film is formed on both sides of the shadow mask material plate,
The vacuum contact printing shown in FIG. 5 allows the entire surface of the negative master to be brought into close contact with the photoresist film in a short time when the negative pattern of the negative master is printed onto the photoresist film by the apparatus. In other words, if the surface roughness of the shadow mask material plate (20) is set closer to both ends in the width direction than to the center part in the width direction, even if the surface roughness is sucked by the adhesion vacuum line placed outside the negative original, Adhesion starts from the center where the surface roughness is dense, and the adhesion gradually progresses to the periphery until the ultimate degree of vacuum reaches 10=
The two can be brought into complete contact with each other in about 100 seconds using a vacuum line for adhesion of mm1g.

Therefore, when a shadow mask is manufactured using the shadow mask material plate (20), the adhesion time is shortened compared to the conventional method, and the productivity of the shadow mask can be improved. A high-quality shadow mask can be manufactured without causing unevenness in the diameter of the passage holes.

In the above embodiment, the surface roughness of the shadow mask material plate was approximately 0.3 μm at the center in the width direction and approximately 0.5 μ at both ends in the width direction, but approximately 0.2 μm at the center in the width direction. A similar effect can be obtained even if the thickness is approximately 0.7 μm at both ends in the direction. However, if the surface roughness is made denser than 0.2 μm,
The adhesion of the negative master plate decreases, and if the thickness exceeds 0.8μ, the shape of the electron beam passing hole deteriorates, so the surface roughness is rougher at both ends in the width direction than at the center in the width direction. and approximately 0.2 μm or more at the center in the width direction and approximately 0 on both sides.
．． It is preferable to set it to 7μ or less.

[Effects of the Invention] The surface roughness at the ends in the width direction of the shadow mask material plate is made rougher than the center part in the width direction, and preferably changes continuously from the center part in the width direction to the ends in the width direction. If you let
When the negative master is brought into close contact with the photoresist film on the surface of the shadow mask material plate by vacuum adhesion, the photoresist film and the negative master can be brought into close contact from the center thereof, and the adhesion can progress toward the periphery. The negative master plate can be completely converted into a photoresist film in a short time. Therefore, by distributing the surface roughness within a range that does not deteriorate the electron beam passing hole, it is possible to manufacture a shadow mask with a good hole shape without causing unevenness in the diameter of the electron beam passing hole. can be improved.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are detailed explanatory diagrams of this invention.
The figure is a cross-sectional view of a shadow mask material plate, which is one example, and Figure 2 shows a comparison of the change in surface roughness with respect to the distance from the center in the width direction with the surface roughness of a conventional shadow mask material plate. Figure 3 is a diagram showing the configuration of a color cathode ray tube, Figure 4 is a diagram showing the shape of the electron beam passage hole in the shadow mask, and Figures 5 (a) and (b) are each a diagram showing the configuration of a color cathode ray tube. FIG. 2 is a front view and a cross-sectional view showing the configuration of FIG. 20...Shadow mask material plates 21a, 21b...Both front and back sides

Claims (2)

[Claims] (1) A shadow mask consisting of a plate material of a predetermined width and length, in which electron beam passage holes are formed by a photo-etching method that includes the step of exposing a negative master plate to a photosensitive resin film formed on the surface of the plate material. A material board for a shadow mask, characterized in that the surface roughness of the ends in the width direction of the board material is rougher than the surface roughness of the center part in the width direction. (2) Claim 1 characterized in that the surface roughness of the plate material changes continuously from the center in the width direction to the ends in the width direction.
The material board for the shadow mask described.