JPH11126557A - Light shielding film and method of forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good-shaped film without discoloring by impurity such as an electrode or dust by baking a layer made of a polyimide resin precursor with a desired shape pattern at a specific range of temperature to form a lightproof film. SOLUTION: By burning a layer made of a polyimide resin precursor with a desired shape pattern at 400-600 deg.C, a lightproof film is formed. Due to this burning, at least a surface layer of the polyimide resin layer is carbonized and becomes black. The polyimide resin precursor for forming a lightproof film means so called polyamic acid which is formed by providing dehydration reaction between aromatic tetracarboxylic acid and aromatic diamine. As the aromatic tetracarboxylic acid, pyromellitic acid, biphenyl tetracarboxylic acid, or benzophenone tetracarboxylic acid is used, and as the aromatic diamine, oxydianiline, paraphenylene diamine, or benzophenone diamine is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light-shielding film and a method for forming the same. The light-shielding film and the method for forming the same according to the present invention
It can be suitably used for forming a light shielding film (black matrix or black stripe) of a flat display panel, for example, a plasma display panel (hereinafter, PDP).

[0002]

FIG. 1 is a schematic perspective view showing a basic structure of a PDP 1. As shown in FIG. The PDP 1 in FIG. 1 is a surface discharge type PDP having a three-electrode structure of a matrix display type called a reflection type. This PDP 1 includes a pair of glass substrates 11 and 21 facing each other with a discharge space 30 interposed therebetween.

On the inner surface of the glass substrate 11 on the front side, a pair of linear display electrodes X and Y parallel to generate a surface discharge along the substrate surface are provided with a matrix display line L.
Each pair is arranged. The display electrodes X and Y are each composed of a wide linear transparent electrode 41 and a narrow linear metal electrode (bus electrode) 42.
The display electrodes X and Y are covered with a dielectric layer 17,
On the surface of the dielectric layer 17, a protective film 18 is formed.

On the other hand, the inner surface of the glass substrate 21 on the rear side is
The address electrodes A are arranged at a constant pitch so as to be covered with the base layer 22 and to be orthogonal to the display electrodes X and Y on the base layer 22. The address electrode A is covered with a dielectric layer 24. On the dielectric layer 24, a plurality of linear partitions 29 are provided one by one between the address electrodes A. Further, the phosphor layers 2 of three primary colors of RGB (red, green, blue) are coated so as to cover the surface of the dielectric layer 24 and the side faces of the partition wall 29.
8R, 28G and 28B are provided.

FIG. 4 is a schematic sectional view of the PDP 1. As shown in FIG. 4, in the PDP 1, the front glass substrate 11
A light-shielding film 45 that blocks light so as to be in direct contact with the inner surface of the display electrode is provided with a non-discharge portion (non-display portion) S between a pair of display electrodes called a reverse slit.
2 is provided for each. The light-shielding film 45 forms a stripe-like light-shielding pattern on the entire display screen,
The phosphor layers 28R, 28G, and 28B are hidden between the lines L, so that the display contrast can be increased.

Here, as a method of forming a light-shielding film (black stripe), for example, a method described in JP-A-9-129142 can be mentioned. This publication discloses a method for forming a light-shielding film by forming an insulating film by depositing a dark-colored insulating material such as chromium oxide or silicon oxide on a substrate by sputtering, and then patterning the insulating film by photolithography. A method of forming a light-shielding film by applying a photoresist layer containing a black pigment such as iron or cobalt oxide by a printing method, and then exposing and developing the same to form a light-shielding film; and screen a low-melting glass paste containing a black pigment. A method for forming a light-shielding film by applying and baking by a printing method is described.

[0007]

The light-shielding film formed by the above-mentioned conventional method contains a metal oxide.
When it comes into contact with the electrode constituting the DP, there is a fear that it undergoes a reducing action and causes discoloration. In addition, the contamination of the material of the light-shielding film with dust or other impurities may cause the light-shielding film to be discolored.

When patterning a photoresist layer containing a black pigment, patterning is difficult because the black pigment deteriorates light transmittance. Accordingly, it has been desired to provide a light-shielding film having a good shape that does not discolor due to an electrode or impurities such as dust, and a method for forming the same.

[0009]

According to the present invention, a light-shielding film is formed by firing a layer of a polyimide resin precursor having a desired shape in a pattern at 400 to 600 ° C. A method for forming a film is provided. Further, according to the present invention, there is provided a light-shielding film formed by the above method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method for forming a light-shielding film according to the present invention,
First, a layer made of a polyimide resin precursor having a desired shape pattern is formed. As a method for forming a pattern having a desired shape, any method generally used in the art can be used. For example, after a paste containing a polyimide resin precursor is applied by a known method, a photoresist is applied thereon, and the photoresist is exposed and developed using a mask in which a pattern having a desired shape is formed. Etching a precursor of a polyimide resin using a photoresist, a method of forming a pattern of a desired shape by removing the photoresist, or a paste containing a precursor of a polyimide resin into which a photosensitive functional group has been introduced. After application, using a mask on which a pattern of a desired shape is formed, a method of forming a pattern of a desired shape by exposing and developing a precursor of a polyimide resin, or a resin having another photosensitive property and a polyimide resin. After applying the paste containing the precursor, using a mask in which a pattern of a desired shape is formed, the precursor of the polyimide resin And a method of forming a pattern of a desired shape by exposure and development thereof.

The precursor of the polyimide resin for forming the light-shielding film is not particularly limited, and any known precursor can be used. The precursor of the polyimide resin means a so-called polyamic acid formed by a dehydration reaction between a tetracarboxylic acid and a diamine.
Here, the tetracarboxylic acid and the diamine may be any combination of aromatic and aromatic, aliphatic and aliphatic, aliphatic and aromatic, and aromatic and aliphatic. Of these, a combination of an aromatic tetracarboxylic acid and an aromatic diamine is preferred.
For example, examples of the aromatic tetracarboxylic acid include pyromellitic acid, biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid, and derivatives thereof. Examples of the aromatic diamine include oxydianiline, paraphenylenediamine, benzophenonediamine, and derivatives thereof. When a functional group exhibiting photosensitivity is introduced into the precursor of the polyimide resin itself, the functional group includes, for example, an acryloyl group. More specific examples of the precursor of the polyimide resin include ZFPI-5000 manufactured by Zeon Corporation and UR-5100 manufactured by Toray Industries, Inc.

Other photosensitive resins include:
For example, ester acrylate, urethane acrylate,
Examples include, but are not limited to, resins having an acryloyl group such as epoxy acrylate, melamine acrylate, and acrylic resin acrylate. The paste containing the precursor of the polyimide resin may contain an organic solvent in order to adjust the viscosity at the time of application.

Next, in the present invention, a layer made of a polyimide resin precursor is fired at 400 to 600 ° C. to form a light-shielding film. By this baking, at least the surface layer of the polyimide resin layer is carbonized and turns black. When the temperature is lower than 400 ° C., the carbonization of the layer made of the polyimide resin precursor becomes insufficient, and when the temperature is higher than 600 ° C., the carbonization of the layer made of the polyimide resin precursor is undesirably advanced because carbonization may progress too much. . The firing is preferably performed for 5 to 30 minutes. However, depending on the type and firing conditions of the polyimide resin precursor used, only the surface layer is carbonized,
The inside may be made of a polyimide resin formed by dehydration and ring closure of a precursor of the polyimide resin, but the present invention includes such a form.

The method for forming a light-shielding film of the present invention is used for forming a stripe-like light-shielding film formed between non-display lines of a PDP matrix display type PDP, LCD, EL, etc., and a black matrix of a CRT. be able to. Among them, it is preferable to use it for forming a stripe-shaped light-shielding film such as a PDP disposed between the electrodes so as to be in contact therewith.

Next, an example of a PDP to which the method for forming a light-shielding film of the present invention can be suitably used will be described with reference to FIG. Note that the configuration in FIG. 1 is an example, and the present invention is not limited to this, and can be applied to any type of PDP such as an AC type or a DC type as long as the PDP has a partition wall. FIG. 1 shows a general indirect discharge type (A
FIG. 2 is a schematic perspective view of a (C-type) surface discharge type PDP, and shows a PDP having a three-electrode structure, which belongs to a reflection type when classified according to the arrangement of phosphor layers.

The PDP 1 of FIG. 1 has a pair of substrates 11 and 21.
Are arranged facing each other. As the substrate, a glass substrate, a quartz substrate, a silicon substrate, or the like can be used. A pair of display electrodes X and Y are formed in parallel on the substrate 11 for each line L of the matrix display.
And a dielectric layer 17 for alternating current (AC) driving for maintaining discharge by a wall electrode is formed on the substrate 11 so as to cover Y and Y.
Further, a protective film 18 is formed on the dielectric layer 17. The dielectric layer can be generally formed by applying and firing a low-melting glass paste. The protective film is
Generally, it is made of MgO or the like.

On the other hand, the substrate 21 is covered with a base layer 22, and a plurality of stripe-shaped address electrodes A are formed on the base layer 22 at positions orthogonal to the display electrodes X and Y in plan view. A dielectric layer 24 is laminated on the substrate 21 so as to cover the address electrodes A. Here, the address electrode is made of Ag, Au, Al, Cu, Cr, a laminate thereof (for example, Cr / Cu / Cr), or the like, and is formed by combining a film forming method such as a sputtering method and a vapor deposition method with an etching method. , A desired number, thickness, width and spacing.

Further, a plurality of stripe-shaped barrier ribs 29 are formed between adjacent address electrodes A and in parallel with the address electrodes A. Next, the adjacent partition 29
Phosphor layers 28R, 28R on the side surfaces of
G and 28B are formed. Reference numeral 30 denotes a discharge space in which a desired discharge gas is sealed.

Here, the phosphor layers 28R, 28G and 28
B denotes a partition wall 29 on the substrate 21 opposite to the display electrodes X and Y in order to avoid impact due to ions generated by surface discharge.
It is provided between them. The phosphor layers 28R, 28G and 28B generally emit light by converting vacuum ultraviolet light generated by surface discharge of the main discharge cells into visible light. Light emitted from the phosphor layers 28R, 28G, and 28B passes through the dielectric layer 17 and the substrate 11 and is emitted to the outside. That is, in the PDP 1, the outer surface of the substrate 11 is the display surface D.

The display electrodes X and Y are connected to the phosphor layers 28R, 28
G and 28B are disposed on the display surface side, so that the surface discharge is wide and the light shielding of display light is minimized. And a narrow metal electrode (bus electrode) 42. The transparent electrode is made of a metal oxide such as ITO (indium oxide + tin oxide) and nesa (tin oxide), for example.
By combining a film forming method such as vapor deposition and an etching method, a desired number, thickness, width, and interval can be formed. On the other hand, the bus electrodes are made of Ag, Au, Al, Cu, C
r and a laminate thereof (for example, Cr / Cu / Cr), etc., and are formed in a desired number, thickness, width and interval by combining a film forming method such as a sputtering method and a vapor deposition method with an etching method. Can be.

As described above, the PDP 1 covers the display electrodes X and Y, and has the substrate 1 having the dielectric layer 17 for maintaining discharge.
1 (front substrate) and a substrate 21 (back substrate) having a partition wall 29 for partitioning the discharge space 30. Next, FIG. 2 shows a schematic cross-sectional view of the front substrate of FIG. 1 cut in a direction perpendicular to the display electrodes X and Y. As can be seen from FIG.
5 is formed between a pair of adjacent display electrodes X and Y. Therefore, the non-light emitting area between the display lines can be made inconspicuous, and the display contrast can be improved. Further, since the light-shielding film of the present invention is made of carbide, it does not contain a metal oxide, and does not cause discoloration due to contact with an electrode constituting a PDP. Further, even if impurities such as dust are mixed in the material of the light-shielding film, no discoloration of the light-shielding film occurs. Furthermore,
Since no pigment is used to make the shading film black,
The patterning is not hindered by the pigment, and the formation of the light-shielding film is easy.

Further, as another embodiment, there is a shape of a light shielding film as shown in FIG. The light shielding film in FIG. 3 has a rib shape. As can be seen from FIG. 3, a step can be formed in the dielectric film by forming the light-shielding film into a rib shape. Therefore, the light emission characteristics of the discharge space 30 defined by the pair of display electrodes X and Y and the address electrode A can be improved. The step formed on the dielectric film is preferably 1 to 10 μm.

In each of FIGS. 2 and 3, the light-shielding film does not overlap the display electrodes X and Y. However, the light-shielding film of the present invention has no risk of discoloration by the metal constituting the electrode. A superposed configuration may be employed. And as still another aspect, on the dielectric layer of the front glass substrate, each of the RGB filters arranged so as to correspond to the phosphor of the rear substrate,
It is also possible to provide the stripe-shaped light shielding film. In this example, the emission colors of the striped RGB phosphors can be completely separated.

The thickness of the light-shielding film of the present invention is preferably 20 μm or less. If the thickness is larger than 20 μm, the gap between the adjacent discharge space via the partition wall becomes large, and there is a possibility that a discharge may occur in a discharge space where discharge is not desired. The more preferable thickness of the light-shielding film is 5 to 20 μm, particularly preferably 10 to 15 μm. The width of the light shielding film is defined by the width of the reverse slit.

[0025]

【Example】

Embodiment 1 The present invention will be further described with reference to FIG. First, an ITO film is formed on a glass substrate 11 and patterned into a desired shape by photolithography to form a transparent electrode 41.
To form Next, a resist layer having an opening at a desired position on the transparent electrode 41 is formed. Using this resist layer as a mask, Cr / Cu is formed on the transparent electrode 41 by plating.
The display electrode pairs X and Y are formed by laminating the metal electrodes 42 of / Cr.

Next, the resist layer is removed and the transparent electrode 4 is removed.
1 and a paste containing a precursor of a photosensitive polyimide (manufactured by Zeon Corporation:
ZFPI-5000). After exposing only the portion between the display electrode pair X and Y to photo-harden the photosensitive polyimide precursor in the exposed portion, the unexposed portion is removed by development. Thereafter, the glass substrate 11 is baked at 400 to 600 ° C. to form the rib-shaped light shielding film 45. This light shielding film 4
In No. 5, at least the surface layer is carbonized and turns black.

Further, by forming the dielectric layer 17 and the protective film 18 on the substrate 11 on which the light shielding film 45 is formed,
A front substrate can be formed. In the first embodiment,
Since the surface layer of the light shielding film 45 is made of at least carbide,
Even if the light-shielding film 45 contacts the metal electrode 42, the color does not change. Therefore, the degree of freedom in designing the light-shielding film is increased, and a light-shielding film of stable quality can be manufactured. Further, by forming the light-shielding film 45 into a rib shape as in the first embodiment, it is possible to improve the separation capability of the discharge space, so that the discharge can be stably performed.

[0028]

According to the light-shielding film and the method of forming the same of the present invention, the non-light-emitting region between the display lines can be made inconspicuous, and the display contrast can be improved. Furthermore, the light-shielding film of the present invention, since at least the surface layer is made of carbide,
Since no metal oxide is contained, no discoloration occurs due to contact with the electrodes constituting the PDP. Further, even if impurities such as dust are mixed in the material of the light-shielding film, no discoloration of the light-shielding film occurs. Further, since a pigment for blackening the light-shielding film is not used, the patterning is not hindered by the pigment, and the formation of the light-shielding film is easy.

Therefore, a light-shielding film of stable quality can be formed, so that the performance of an apparatus using the light-shielding film of the present invention can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a PDP.

FIG. 2 is a schematic sectional view of a front substrate of a PDP using the light-shielding film of the present invention.

FIG. 3 is a schematic sectional view of a front substrate of a PDP using the light-shielding film of the present invention.

FIG. 4 is a schematic sectional view of a PDP using a conventional light shielding film.

[Explanation of symbols]

 Reference Signs List 1 PDP 11, 21 Substrate 17, 24 Dielectric layer 18 Protective film 22 Underlayer 28R, 28G, 28B Phosphor layer 29 Partition wall 30 Discharge space 41 Transparent electrode 42 Metal electrode 45 Light shielding film X, Y Display electrode A Address electrode L line S2 Reverse slit

Claims (4)

[Claims] 1. A method for forming a light-shielding film, comprising baking a layer of a polyimide resin precursor having a desired shape in a pattern at 400 to 600 ° C. to form a light-shielding film. 2. The method according to claim 1, wherein the pattern having a desired shape is formed by exposing and developing a photosensitive resin composition containing a polyimide resin precursor. 3. A light-shielding film formed by the method according to claim 1. 4. The light-shielding film according to claim 3, wherein the light-shielding film is used as a black matrix or a black stripe of a plasma display panel.