JPH05205633A - Method for forming fluorescent screen of plasma display panel - Google Patents

Abstract

PURPOSE:To form accurately and easily a fluorescent screen irrespective of material used to an electrode or a cell barrier. CONSTITUTION:A phosphor slurry 3 consisting of photosensitive resin compound with a phosphor dispersed is applied to a surface on which fluorescent screen is to be formed, wherein the resin compound is formed from casein and organic hardening agent. This is subjected to the exposure, development, and baking processes and a fluorescent screen 7 is formed in the specified place. Thereby the photolithographic process for formation of fluorescent screen can be done without being affected by the material to electrode 2 or cell barrier. This permits the use of a conventional paste for electrode or one for cell barrier which has been resiricted for the reason of difficulty in formation of fluorescent screen due to products or residues. When a low melting point glass is included in the phosphor slurry 3, no limitation is imposed on its sort to be selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a fluorescent screen on a plasma display panel (hereinafter referred to as PDP) which is a self-luminous flat panel display using gas discharge.

[0002]

2. Description of the Related Art FIG. 2 shows one configuration example of a conventional DC PDP. As shown in the figure, in this DC type PDP, a flat plate-shaped front plate 11 and a rear plate 12 made of glass are arranged in parallel and opposite to each other, and both are provided between them. It is held at a constant interval by the cell barrier 13. Further, an anode 14 is formed on the back side of the front plate 11, a cathode 15 is formed on the front side of the back plate 12 so as to be orthogonal to the anode 14, and a fluorescent screen is provided on both sides of the anode 14. 16 are formed adjacent to each other. In this DC type PDP, the anode 14
By applying a predetermined voltage from a DC power supply between the cathode 15 and the cathode 15 to form an electric field, each cell 17 as a display element including the front plate 11, the rear plate 12, and the cell barrier 13 is formed.
The discharge is performed inside the. Then, the fluorescent surface 16 on the back side of the front plate 11 is caused to emit light by the ultraviolet rays generated by this discharge, and the observer visually recognizes this light transmitted through the front plate 11.

FIG. 3 shows an example of the structure of a conventional AC type PDP. As shown in FIG.
As in the case of the DC type PDP, the C type PDP has a flat plate-like front plate 21 and a rear plate 22 made of glass, which are arranged in parallel and opposite to each other, and are provided between them. The cell barrier 23 holds the cells at regular intervals. Further, in this AC type PDP, two electrodes 24 and 25 orthogonal to each other are formed on the front surface side of the back plate 22 with the dielectric layer 26 interposed therebetween, and further on the front surface side thereof, the dielectric layer 27 and the protective layer 28. And a fluorescent screen 29 is formed on the back side of the front plate 21. In this AC type PDP, two electrodes 2
By applying a predetermined voltage from an AC power supply between 4 and 25 to form an electric field, the front plate 21 is discharged inside each cell 30 as a display element composed of the back plate 22 and the cell barrier 23. Done. Then, the fluorescent surface 29 on the back side of the front plate 21 is caused to emit light by the ultraviolet rays generated by this discharge, and the observer visually recognizes this light transmitted through the front plate 21.

Here, there are a matrix shape and a line shape as the shape of the cell barrier, for example, DC.
In the case of the type PDP, FIG. 4 is a matrix type and FIG. 5 is a line type. 4 and 5, 31 is a front plate arranged on the observer side, 32 is a back plate, 33 is a cell barrier, 34 is an anode, and 35 is a cathode. Further, although those shown in these figures are examples in which the cell barrier 33 is formed on the back plate 32 when forming the PDP, the cell barrier 33 may be formed on the front plate 31 in some cases.

The DC type or A having the above-mentioned structure
The phosphor screen of the C-type PDP is generally formed by a photolithography method. Specifically, after applying a photosensitive phosphor slurry to the back surface of the front plate, a photomask corresponding to the pattern of the phosphor screen is used. It is formed by exposing it to light, developing it, and baking it. As the phosphor slurry, a mixture containing a phosphor and polyvinyl alcohol (PVA) and a diazonium compound as a photosensitive resin, or a mixture containing a phosphor and PVA and a dichromic acid compound as a photosensitive resin is mainly used. The antifoaming agent and the surfactant may be added depending on the case.

Further, in the PDP as described above, there is also known one in which a fluorescent screen is formed on the wall surface of the cell barrier, and one in which the fluorescent screen is formed across both the front plate and the wall surface of the cell barrier. The fluorescent screen in this case is also formed by the photolithography method.

[0007]

However, when the phosphor screen is formed by the photolithography method described above, Ni electrodes formed by thick film printing (for example, when using 9535 or 9536D manufactured by DuPont as a paste) Is formed on a glass substrate, a PVA-based phosphor slurry is formed due to boric acid generated by oxidation of boron in the electrode paste during firing, particularly sodium borate formed by reaction with sodium contained in the glass substrate or paste. Was solidified into a gel, and patterning could not be performed accurately.

Further, as materials for forming electrodes and cell barriers, boron, copper, aluminum, titanium, zirconium,
When tin, vanadium, chromium, etc. are contained, or when aldehydes, methylol compounds, activated vinyl groups, epoxy compounds, esters, diisocyanates, etc. remain in the electrodes and cell barriers, PVA-based The phosphor slurry solidifies at the time of application, which may prevent accurate patterning or a uniform film thickness.

Further, powdered glass (generally lead borosilicate glass) having a low melting point has been mixed in the phosphor slurry in order to improve the adhesive force between the phosphor and the glass substrate. When powdered glass having a ratio of 1.5% or more is used, the PVA-based phosphor slurry causes gelation, and therefore, the low melting point glass that can be used is very limited.

As described above, there is a problem that the photolithography process for forming the fluorescent screen is obstructed depending on the type of the low melting point glass in the PVA type phosphor slurry or the material forming the electrodes and cell barriers.

The present invention has been made in order to solve such a problem, and can accurately and irrespective of the kind of the material used in the previous step and the kind of the low melting point glass mixed with the phosphor slurry. It is an object of the present invention to provide a method for forming a fluorescent screen of a PDP that can easily form a fluorescent screen.

[0012]

In order to achieve the above object, the present invention applies a phosphor slurry prepared by dispersing a phosphor in a photosensitive resin composition onto a surface on which a phosphor screen is to be formed. In the method for forming a phosphor screen of a PDP, which comprises exposing, developing, and baking steps to form a phosphor screen at a predetermined location, the photosensitive resin composition is composed of casein and an organic curing agent. Is.

It is preferable that the organic curing agent is a bisazide curing agent.

In the above method, the phosphor slurry is preferably applied by a doctor blade coating method.

When a color PDP is formed by the above method, phosphors having red, green and blue emission colors are coated with phosphor slurry, selectively exposed through a mask, and developed. Just repeat.

[0016]

According to the above-described phosphor screen forming method of the present invention, the phosphor screen is not affected by the material of the electrode or cell barrier formed on the substrate or the low melting point glass mixed in the phosphor slurry. A photolithography process of formation is performed.

[0017]

FIG. 1 is a process chart showing an embodiment of a method for forming a phosphor screen of a PDP according to the present invention, in which a phosphor screen is formed on the same surface as an electrode formed on a front plate of a DC type PDP. Is shown. Hereinafter, each step shown in FIGS. 1A to 1E will be described step by step.

First, as shown in FIG. 1A, an anode 2 is formed in a thick film or thin film state on a substrate 1 made of ceramic such as glass. Then, as shown in (b),
A phosphor slurry 3 made of a photosensitive resin composition in which a phosphor is dispersed is applied to the surface of the substrate 1 on which the phosphor surface is to be formed by an arbitrary coating method and dried. Then, as shown in (c), pattern exposure is performed with ultraviolet rays 5 through the mask 4 having a phosphor pattern, and then, as shown in (d), the phosphor layer 6 that has been developed and patterned is left, and the unexposed portion is exposed. Remove layers and dry.

Here, in the case of a color PDP, phosphors having red, green, and blue emission colors are selectively applied by coating a photosensitive resin composition containing the phosphors and through a mask of a phosphor pattern. The steps of exposing and developing to remove the unexposed portion and excess phosphor are repeated.

Finally, the phosphor layer 6 thus formed is fired to burn off the resin component of the phosphor slurry and the organic curing agent, so that the phosphor having a desired pattern as shown in FIG. Form surface 7.

In addition to the front plate on which the phosphor screen 7 is formed in this manner, a back plate on which a cathode and a cell barrier are formed is prepared, and a PDP is formed by combining these front and back plates. It

The above manufacturing steps themselves may be the same as those in the conventional method, and therefore, the electrode forming method, substrate material, coating method, developing method and baking method used may be the same as those in the conventional method. However, in the present invention,
A photosensitive resin composition containing casein and an organic curing agent is used.

As the casein, any conventionally known casein can be used.

On the other hand, examples of the organic curing agent include diazonium salts, phenyl azides, o-quinone azides,
Although any conventionally known organic curing agent such as bisazide can be used, from the viewpoint of curability, developability, baking property, etc., a bisazide curing agent is suitable, and particularly useful is 4.4. '-Diazido stylbene-2.2'disulfonic acid
Is.

The amount of such an organic curing agent added to casein is preferably 20 wt% or more of casein.
That is, if the content is 20 wt% or less, the casein may be insufficiently cured, and film floating may occur during development. Further, when the amount of the curing agent is too large, only the surface layer is cured due to the coloring of the curing agent and curing failure occurs as a whole, or the sensitivity is remarkably lowered and the film thickness cannot be earned for the exposure amount. The phenomenon occurs.

The photosensitive resin composition used in the present invention contains the above-mentioned casein and the organic curing agent as essential components, and any other conventionally known additives can be incorporated as necessary. In the present invention, the above essential components and optional additives are mixed with water or water with a water-soluble organic solvent such as alcohol and ammonia for pH adjustment to form a coating liquid. The amount of solvent used varies depending on the type of casein used, the concentration of the phosphor and the coating method, but in general,
The range of 20 to 80 wt% is good.

Phosphors that can be used in the present invention include red as Y ₂ O ₃ : Eu, Y ₂ SiO ₅ : Eu,
_{Y 3 Al 5 O 12: Eu} , Zn 3 (PO 4) 2: Mn, Y
BO ₃ : Eu, (Y, Gd) BO ₃ : Eu, GdB
O ₃ : Eu, ScBO ₃ : Eu, LuBO ₃ : Eu and the like, and Y ₂ SiO ₅ : Ce, CaWO ₄ : P as blue
b, BaMgAl ₁₄ O ₂₃ : Eu, etc., and Z as green
n ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ : Mn, SrAl
_{13 O 19: Mn, CaAl 12} O 19: Mn, YBO 3: T
b, BaMgAl ₁₄ O ₂₃ : Mn, LuBO ₃ : Tb, G
dBO ₃ : Tb, ScBO ₃ : Tb, Sr ₆ Si ₃ O ₃
Cl ₄ : Eu, etc.

Such a phosphor may be added in an amount of about 10 to 100 parts by weight per 1 part by weight of the above casein.
More preferably, it is added in a proportion of 33 to 80 parts by weight. At this time, it should be noted that a large amount of resin causes an extremely large amount of exposure required for curing, resulting in deterioration of shape and insufficient film thickness.

To disperse the phosphor in the photosensitive resin composition, for example, a ball mill, a sand mill, a roll mill, a speed line mill or the like can be used, and the ball mill is particularly useful in the present invention.

As a method for applying a phosphor slurry composed of a photosensitive resin composition in which the above phosphor is dispersed on a substrate provided with a desired electrode, there are a doctor blade coating method, a myer bar coating method and a roll coating method. Known coating methods such as a screen coating method, a screen printing method, and a spinner coating method can be used, but the inclusion of air bubbles, the prevention of sedimentation of the phosphor, the prevention of the electrode damage due to the uneven electrode substrate, The doctor blade coating method is most suitable from the viewpoints of inclusion of bubbles and uniformity of coating amount. In particular, the electrodes on the substrate are generally formed in a stripe shape, and during coating, it is preferable to move the doctor blade along the stripes for coating. A smooth coating with a uniform film thickness can be realized without problems such as air bubble mixing, electrode damage, and coating unevenness.
The coating film formed as described above varies depending on the thickness of the electrode, but generally it is about 5 to 50 μm when dried.
A degree is preferable.

The respective steps and conditions such as drying of the coating film, curing by patterning exposure, elution of unexposed portion by development, and baking are as described above and as exemplified in the specific examples described later. There is no limitation and it may be the same as in the prior art.

Although the planar substrate of the DC type PDP has been described above, it is obvious that the same can be applied to the AC type PDP.

Next, a specific example of the above embodiment will be described in detail below.

[Specific Example] On a glass substrate to be a front plate,
A Ni electrode (9536D, manufactured by DuPont) by a screen printing method was used to print Ni electrodes with a width of 150 μm and a pitch of 500 μm, and after drying, baking was performed at 580 ° C. in the atmosphere to form an anode. After cleaning the substrate, a phosphor having a green emission color (Zn ₂ S manufactured by Kasei Optonix Co., Ltd.)
iO ₄ : Mn): 30.0 wt%, casein sulfate: 8.
21 wt%, pure water: 60.8 wt%, borax: 0.5 wt
%, Sodium citrate: 0.035 wt%, Deltop 100: 0.21 wt%, 28% ammonia water: 0.
4.4'-Diazido stylbene-2.2 'in a mixture of 245%
A phosphor slurry prepared by adding 55 wt% of casein to disulfonic acid (A-066, manufactured by Shinko Giken Co., Ltd.)
It is coated on the entire surface with a blade coater at 30 ° C. so as to cover the electrode, dried at room temperature and then 350 n through a mask.
52.5mJ / cm ^{2 of} ultraviolet rays with the maximum wavelength near m
It was exposed by irradiating with the irradiation amount of. At this time, irradiation was performed from the back surface side of the substrate so that a fluorescent screen was not formed on the electrodes. Then, the substrate was spray-developed with water to remove the unexposed portion. Then, it dried at 120 degreeC and hardened. Subsequently, a cell having a fluorescent surface having a blue emission color (phosphor: BaMgAl ₁₄ O ₂₃ : Eu) and a cell having a fluorescent surface having a red emission color (phosphor: (Y, Gd) BO ₃ : E)
The above steps are similarly repeated for u), and the resin component (casein) in the slurry and the curing agent (4.4'-Diazido stylbene-2.2'disulf) are obtained by baking at 440 ° C for 30 minutes.
onic acid) was burned off, and red on the substrate excluding the electrodes,
Phosphor screens which were separately painted in green and blue were formed.

By combining the front plate having the phosphor screen and the rear plate having the cathode and the cell barrier separately, a matrix color PDP in which the three primary colors of red, green and blue are visually recognized is formed. PD created in this way
In P, a phosphor screen is formed on the back side of the front plate, and this phosphor screen is excited by ultraviolet rays generated by plasma discharge to emit light, and an observer visually recognizes the transmitted light of the phosphor screen.

Needless to say, a PDP having a line-shaped cell barrier as shown in FIG. 5 can also be formed by the same process.

[0037]

As described above, the method for forming a phosphor screen of a plasma display panel according to the present invention comprises a phosphor slurry prepared by dispersing a phosphor in a photosensitive resin composition containing casein and an organic curing agent. Since it was used to form a phosphor screen at a predetermined place by the photolithography method, regardless of the material of the electrode or cell barrier used in the previous step,
It is possible to form a fluorescent screen that is accurately patterned and has a uniform film thickness. Therefore, it becomes possible to use a ready-made electrode paste or cell barrier paste, the use of which has been restricted due to difficulty in forming a fluorescent screen due to products and residues.

Even when a low melting point glass is mixed with the phosphor slurry in order to improve the adhesive force between the fluorescent substance and the glass substrate, the components in the low melting point glass do not interfere with the photolithography process. The range of low-melting glass that can be formed is widened.

Further, by applying the phosphor slurry by the doctor blade coating method in combination with the above method, even if the substrate is a large size, for example, a meter size, and the surface of the substrate is roughened by electrodes, It is possible to realize a coating having a uniform film thickness over the whole.

Color display is also possible by selectively forming the phosphor screen with phosphors having red, green and blue emission colors.

[Brief description of drawings]

FIG. 1 is a process chart showing an embodiment of a phosphor screen forming method of a plasma display panel according to the present invention.

FIG. 2 is a partial cross-sectional view showing an example of a DC type plasma display panel.

FIG. 3 is a partial cross-sectional view showing an example of an AC type plasma display panel.

FIG. 4 is a partially cutaway perspective view showing a DC type plasma display panel in which a cell barrier has a matrix shape, with a front plate and a rear plate thereof being separated from each other.

FIG. 5 is a partially cutaway perspective view showing a DC type plasma display panel having linear cell barriers with a front plate and a rear plate separated from each other.

[Explanation of symbols]

 1 substrate 2 electrode 3 phosphor slurry 4 mask 5 ultraviolet ray 6 phosphor layer 7 phosphor surface

Claims (4)

[Claims] 1. A phosphor slurry in which a phosphor is dispersed in a photosensitive resin composition is applied to a surface on which a phosphor screen is to be formed, and the phosphor screen is exposed at a predetermined position through exposure, development and baking steps. A method for forming a phosphor screen of a plasma display panel, wherein the photosensitive resin composition is composed of casein and an organic curing agent. 2. The method for forming a fluorescent screen of a plasma display panel according to claim 1, wherein the organic curing agent is a bisazide curing agent. 3. The coating of the phosphor slurry is performed by a doctor blade coating method.
Or a method for forming a phosphor screen of a plasma display panel according to item 2; 4. The phosphors having red, green and blue emission colors are repeatedly coated with phosphor slurry, selectively exposed through a mask, and developed, respectively. 4. The method for forming a phosphor screen of a plasma display panel according to item 3.