JPH0963473A - Manufacture of shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shadow mask which has a resist with a trapezoidal cross section and does not cause halation on a screen edge by keeping a photolithography mask face with a resistor 10μm-1mm apart in a resist exposure in a manufacture process of the shadow mask. SOLUTION: Reflection of an irradiated electron beam can be prevented by setting the side face 5 of an iron belt part 1 in a slit 2 to a slope. To manufacture an aperture grill with trapezoidal cross-section, the cross section of a resist layer having the film thicker than that of an iron electroplating to be formed is formed into a trapezoidal shape. When the iron electroplating is performed using a conductor on which a resist layer having this shape is formed, an iron film grows using the resist as a mold so that the cross section of the iron electroplating film peeled from the conductor becomes almost a trapezoidal shape. When a photoresist is exposed, a clearance 7 is opened between a photolithography mask 6 and the photoresist layer 13. Though the exposure 8 is made with a parallel light, it is diffracted at a light shielding part 9 so that the resist cross section becomes a trapezoidal shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask used for a picture tube for a color display, and more particularly to a method for manufacturing an aperture grill.

[0002]

2. Description of the Related Art There are shadow masks for general televisions and high-definition shadow masks used for high-vision and industrial displays. This high-definition shadow mask is required to have a dimensional accuracy of about several μm. Usually, the electron beam passage hole is a round hole, an ellipse, or a lattice shape, but there is also a shadow mask called an aperture grill having a slit in a stripe shape. It is used in the Trinitron system. A display using an aperture grill has less heat distortion than a display using an ordinary shadow mask. In addition, the screen surface has a two-dimensional surface using an aperture grill, whereas the normal shadow mask method has a three-dimensional surface, and thus has a large distortion. Due to these advantages, shadow masks are overwhelmingly supported in high-definition displays. Therefore, the shadow mask of the aperture grill method will be mainly described here.

Conventionally, the aperture grill used in the Trinitron system has a resist layer formed on a steel plate,
After the stripe-shaped slit shape was patterned, etching was performed with a ferric chloride solution to form a large number of slits, and then the resist layer was removed to produce the etching method.

However, the aperture grille for a display, which requires a high-precision and high-definition screen, requires an extremely fine slit width and interval, so that dimensional precision often occurs and the product yield is high. Attempts have been made to manufacture aperture grilles by electroforming rather than low etching. In the aperture grill by electroforming, after forming a resist layer on the conductor and patterning the stripe-shaped slit shape, the exposed conductor surface is plated with electric iron to form a large number of slits, and then the conductor is peeled off. And manufacture.

In the aperture grill thus produced, the longitudinal section of the iron strip portion forming the stripe slit is rectangular. When this is mounted in a cathode ray tube and an image is taken, a phenomenon called halation occurs in which the color of the image becomes whitish or the outline is blurred at the edge of the screen, and the image quality deteriorates. Halation is a particular problem for high definition displays.

Halation occurs when the electron beam hits the side surface of the iron strip portion of the aperture grille and is diffusely reflected to cause a plurality of phosphors to emit light. This occurs at the edge of the screen because at the edge, the angle between the trajectory of the electron beam and the side surface of the iron strip of the aperture grille becomes large.
This is because the electron beam is easy to hit.

In order to prevent this halation, a method has been considered in which the cross section of the iron strip portion of the aperture grill has a two-layer structure and the eaves are provided on the side surfaces of the iron strip portion so that the electron beam does not hit the side surface.

[0008] Such halation is a problem that occurs even in a normal type shadow mask other than the trinitron system. However, although halation on the aperture grille occurs only at the screen edge that is perpendicular to the slit direction, it can occur in any direction of the cathode ray tube with a normal shadow mask, so the normal shadow mask is more suitable. The problem is big.

[0009]

Thus, although the halation can be eliminated by the method of providing the eaves, the aperture grill has a two-layer structure as shown in FIG.
The steps of resist patterning and plating have to be repeated twice, which is almost twice as much as the labor required for an ordinary aperture grill without an eaves.

Also, the electron beam may be diffusely reflected on the side surface of the eaves portion to cause halation. In order to prevent this, it is necessary to reduce the area of the side surface of the eaves. However, when the eaves are made thin, the strength of the eaves part is reduced, so that there is a problem that the surface of the aperture grill is easily wavy and the image quality is deteriorated.

Further, since compatibility is required between the conventional aperture grill with a rectangular cross section of the iron strip and the aperture grill provided with the eaves, the width dimension of the iron strip and the width of the slit between the iron strips are required. The size cannot be changed. Therefore, in order to provide an eaves to the iron strip of the aperture grille, instead of adding an eaves part to a conventional iron strip with a rectangular cross-section, it is made by scraping off a part of the iron strip. There must be. Then, the cross-sectional area of the iron strip portion becomes small, and there arises a problem that the aperture grille breaks due to the tension when the aperture grille is installed on the cathode ray tube. Even if the aperture grille does not break, the aperture grill with reduced strength is easily deformed, which makes the handling troublesome.

Therefore, an object of the present invention is to prevent halation of a shadow mask produced by electroforming,
It is intended to provide a method for manufacturing a shadow mask that does not require man-hours and can prevent breakage and deformation due to deterioration of image quality and strength.

[0013]

According to the method of manufacturing a shadow mask of the present invention, a resist layer is formed on a conductor, and after patterning, the exposed conductor portion is subjected to electric iron plating.
In the method for manufacturing a shadow mask for peeling off the film of electric iron plating from the conductor, the distance (L) between the photolithographic masking surface and the register is 10 μm when the resist is exposed.
This is characterized in that the vertical section of the patterned resist is made into a trapezoidal shape by making the vertical section of the patterned resist into a trapezoidal shape by opening 1 mm from the above.

[0014]

DETAILED DESCRIPTION OF THE INVENTION
It is obtained by correctly irradiating red, green, and blue electron beams on the respective phosphor screens. Further, the shadow mask serves as a filter for the electron beam so that the electron beam is correctly irradiated on the phosphor screen. If a thin shadow mask is used, the dimensional accuracy is high, so a higher-definition image can be obtained. Thin shadow masks are manufactured by electroforming because of the problem of yield. The longitudinal section of the iron plating film of the shadow mask produced by the electroforming method is usually rectangular.

The vertical section referred to here is a surface of the shadow mask other than the aperture grill system, which is cut in the direction perpendicular to the screen. Further, in the aperture grill system, a surface obtained by cutting the surface in the scanning direction of the electron beam is defined as a vertical section in this specification.

To describe the aperture grille in particular, the thickness of the aperture grille produced by the electroforming method is 30 to 50 μm. There is no problem if the incident angle of the electron beam with respect to the normal direction of the aperture grill surface is small, but as the distance from the center of the aperture grill increases, the incident angle of the electron beam with respect to the normal direction of the aperture grill increases, so the cross-sectional shape is rectangular. In this case, the electron beam emitted to the edge of the aperture grille is reflected by the side surface of the iron strip in the slit, causing multiple phosphors to emit light at the same time, making the image color whitish and blurring the outline. Occurs.

Therefore, as shown in FIG. 1, if the side surface 5 of the iron strip portion 1 in the slit 2 is formed as an inclined surface, reflection of the irradiated electron beam can be prevented. In order to manufacture an aperture grill having a shape as shown in FIG. 1, first, a cross section of a resist layer thicker than the thickness of the electric iron plating film to be formed is formed into a trapezoidal shape. When electric iron plating is performed using a conductor on which a resist layer having such a shape is formed, the growth of the iron film is performed using the resist as a template, so the electric iron plating film peeled from the conductor. The cross section is almost trapezoidal.

Here, in order to make the cross section of the resist layer trapezoidal, a gap 7 must be provided between the photolithographic mask 6 and the photoresist layer 13 when the photoresist is exposed as shown in FIG. I have to. The exposure 8 is a normal parallel ultraviolet light, which is diffracted at the end of the light-shielding portion 9 of the mask for photoengraving and wraps around to the originally light-shielded portion to expose the photoresist. Since the diffracted light is weaker than the original exposure, it is attenuated only by exposing the surface of the resist, and does not reach a deep layer near the conductor plate 10. Therefore, the cross-sectional shape of the exposed resist 11 is trapezoidal. If the photolithographic mask and the photoresist are in close contact with each other, the light cannot enter the light-shielded portion even if there is diffraction, so the exposed resist 11
The cross-sectional shape of is not trapezoidal.

In FIG. 1, if the angle formed by the electron beam irradiation surface 3 and the slope 5 which is the side surface of the iron strip portion 1 is equal to or less than the angle at which the electron beam is incident on the electron beam irradiation surface 3, the iron strip side surface 5 is formed. The electron beam scattering can be completely prevented. This angle is different depending on the design of the cathode ray tube on which the aperture grill is mounted, but it is preferably 45 degrees or less and about 30 degrees if possible. However, if the angle is set even a slight amount, the diffused reflection of the electron beam can be reduced, so that the halation can be reduced. The angle can be adjusted by changing the distance between the mask and the resist.

[0020]

【Example】

(Example) An example will be described with reference to FIG. The conductor 10 is a titanium steel plate having a length of 300 mm, a width of 400 mm, and a thickness of 0.1 mm. When a resist layer 11 of a dry film having a thickness of 40 μm is formed thereon and a space between the resist layer and the photolithography mask is not provided, a colorless and transparent polyethylene sheet (not shown) having a thickness of 10 μm is provided to make the space. ), A 40 μm polyethylene sheet, a 1 mm glass plate, and a 1 cm glass plate under five conditions, a width of 450 μm and a longitudinal length of 2
A mask 6 for photoengraving having a slit of 50 mm and an interval of 150 μm was placed. Then, it was exposed to parallel ultraviolet light of 50 mJ / cm ² , developed, and patterned. Next, the exposed conductor surface was plated with electric iron under the plating solution composition and conditions shown in Table 1 to form an aperture grill with a thickness of 35 μm.

[0021]

[Table 1] Plating solution composition and conditions-Liquid composition FeCl ₂ .4H ₂ O 2.01M CaCl ₂ 1.62M saccharin 9.13mM CH ₃ (CH ₂ ) 6CH ₂ OSO ₃ Na 0.3mM ・ Plating conditions Temperature 90 ° C Cathode current density 5A / dm ² Anode Pt time 37min

The cross section of the iron strip portion of the aperture grill obtained by the above method had a shape as shown in FIG. FIG. 4 shows the relationship between the distance between the mask and the resist and the angle of the iron strip formed by the surface side between the brown and the side of the iron strip. When an aperture grill with a spacing of 10 μm was mounted in a cathode ray tube and an image was taken, no halation was seen in the image at the edge of the screen.

If the angle between the surface of the aperture grill and the side surface of the iron strip is smaller than this, the amount of the electron beam reflected by the side surface of the iron strip will be smaller. Therefore, halation will occur when an interval of 10 μm or more is provided. Not considered.
However, when the distance was 10 mm, the exposure reached the back surface of the mask, and the resist patterning failed in a part of the aperture grill.

(Conventional Example) An aperture grill was produced in the same manner as in the example except that a dry film-like resist layer was applied and a polyethylene sheet was not placed on the mask for direct photolithography. The cross section of the iron band of the obtained aperture grill was rectangular, and when this was mounted in a cathode ray tube and an image was taken, halation occurred in the image at the edge of the screen.

[0025]

According to the method of the present invention, it is possible to manufacture a shadow mask which does not cause halation on an image at the edge of a screen even when it is used in a cathode ray tube, without increasing the number of steps and without lowering the strength or causing deformation.

[Brief description of drawings]

FIG. 1 shows an aperture grill made by the method of the present invention,
It is sectional drawing of an iron strip part.

FIG. 2 is a cross-sectional view illustrating a method for manufacturing an aperture grill according to the present invention.

FIG. 3 is a cross-sectional view of an iron strip portion of an aperture grill in which a halation countermeasure is taken by a conventional method.

FIG. 4 is a relationship between the distance between the mask and the resist and the angle of the side surface of the iron strip in the resist exposure according to the embodiment of the present invention.

[Explanation of symbols]

 1 Iron Strip Part 2 Slit 3 Electron Beam Irradiation Surface Side 4 Braun Tube Surface Side 5 Iron Strip Part Side Surface 6 Photolithography Mask 7 Gap 8 Exposure 9 Light Shielding Area 10 Conductor Plate 11 Photosensitive Resist 12 Unexposed Resist 13 Photoresist Layer 14 Eaves

Claims (1)

[Claims] 1. A resist layer is formed on a conductor and after patterning, the exposed conductor portion is plated with electric iron.
In the method of manufacturing a shadow mask for peeling off the electric iron plating film from the conductor, the distance (L) between the photolithographic mask surface and the resist is 10 μm when the resist is exposed.
A method of manufacturing a shadow mask, wherein the vertical section of the patterned resist is trapezoidal by making a vertical section of the patterned resist into a trapezoidal section.