JP2003043676A - Photosensitive silver paste and image display using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive silver paste for forming a high-precision fine electrode pattern which is not obtained by a conventional electrode pattern forming method. SOLUTION: The photosensitive silver paste comprises an alkali-soluble resin (A), a crosslinkable monomer (B) having an unsaturated double bond, a photopolymerization initiator (C), silver powder (D), glass frit (E) and an organic solvent (F) and the amount of the crosslinkable monomer (B) is 40-150 pts.wt. based on 100 pts.wt. alkali-soluble resin (A) in the silver paste. An image display using the silver paste is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive silver paste and an image display device using the same.

[0002]

2. Description of the Related Art Conventionally, in various electronic parts such as a plasma display panel, an image display device such as a liquid crystal display device, and a thermal head, it is necessary to pattern fine electrodes, for example, a screen printing method, vapor deposition, sputtering or plating. A conductive film formed by the above method is etched by a photolithography method to form a pattern, or a pattern formed by a method such as pattern printing using a screen is dried and baked to form an electrode.

Among these methods, the method of forming a pattern by etching can form a highly accurate pattern, but it has a drawback that the cost is high because of the etching process. On the other hand, the printing method using the screen plate is advantageous because it is possible to form a pattern on the substrate corresponding to the large screen of the image display device at a relatively low cost, but if there is dust in the paste, it may occur during pattern creation. Also remains, which causes disconnection after firing.

[0004]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a photosensitive silver paste which has an excellent pattern forming ability with less disconnection.

[0005]

Means for Solving the Problems Alkali-soluble resin (A), crosslinkable monomer having unsaturated double bond (B), photopolymerization initiator (C), silver powder (D), glass frit (E), organic A photosensitive silver paste comprising a solvent (F), 40 to 150 parts by weight of a crosslinkable monomer (B) having an unsaturated double bond with respect to 100 parts by weight of an alkali-soluble resin in the silver paste, and photopolymerization. 1 initiator (C)
5 to 50 parts by weight, silver powder (D) is 400 to 1500 parts by weight, glass frit (E) is 1 to 60 parts by weight, and organic solvent (F) is 50 to 250 parts by weight. It is a photosensitive silver paste that has been subjected to a filtration process after each preparation. Further, the image display device is manufactured by using the above-mentioned photosensitive silver paste.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The alkali-soluble resin (A) used in the present invention is a binder resin for a paste, and is preferably alkali-soluble in order to enable development with an ordinary alkaline developer.

To give a concrete example, an acrylic copolymer having an acidic group such as carboxylic acid and an ethylenically unsaturated group is preferable, and as the acidic group component, acrylic acid, methacrylic acid, succinic acid 2 -Methacryloyloxyethyl, 2-acryloyloxyethyl succinate, 2-methacryloyloxyethyl phthalate, 2-acryloyloxyethyl phthalate and the like, as the ethylenically unsaturated component, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl. Methacrylate, n-
Propyl acrylate, n-propyl methacrylate,
Isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, t
ert-butyl methacrylate, allyl acrylate,
Examples thereof include allyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl metalylate and the like.

The crosslinkable monomer (B) having an unsaturated double bond of the present invention is a compound having at least one ethylenically unsaturated double bond. It reacts with the radicals generated from the photopolymerization initiator upon irradiation with light to reduce the solubility in an alkali developing solution to form a pattern. As specific examples, allyl acrylate, benzyl acrylate, butoxyethyl acrylate, butoxyethylene glycol acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, 2-ethylhexyl acrylate, glycerol acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2- Hydroxypropyl acrylate, isobonyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxy acrylate, methoxyethylene glycol acrylate, phenoxyethyl acrylate, stearyl acrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-
Pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,3-propanediol diacrylate, 1,4-cyclohexanediol diacrylate, 2,2-dimethylolpropane diacrylate, glycerol diacrylate, tripropylene glycol diacrylate Acrylate, glycerol triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethylene oxide modified pentaerythritol triacrylate, ethylene oxide modified pentaerythritol tetraacrylate, propylene oxide modified pentaerythritol tetraacrylate, propylene oxide modified penta Erythritol triacrylate, Triethylene glycol diacrylate, polyoxyethylene propane triacrylate, butylene glycol diacrylate,
1,2,4-butanetriol triacrylate, 2,
2,4-trimethyl-1,3-pentanediol diacrylate, 1,10-decanediol dimethyl acrylate, pentaerythritol hexaacrylate and the above acrylates replaced by methacrylates,
γ-methacryloxypropyltrimethoxysilane, 1-
Examples include vinyl-2-pyrrolidone and the like. You may use the said crosslinkable monomer in combination of 2 or more types. The amount of the crosslinkable monomer (B) having an unsaturated double bond is preferably 40 to 150 parts by weight based on 100 parts by weight of the alkali-soluble resin. If it is less than 40 parts by weight, the crosslinkability is poor and the resolution is poor, and if it exceeds 150 parts by weight, the viscosity is remarkably lowered and the silver powder precipitates during storage, causing aggregation, which is not preferable.

The photopolymerization initiator (C) used in the present invention
It is preferable to contain dimethylbenzyl ketal and 4-dimethylaminobenzoic acid as essential components in order to obtain a pattern with high sensitivity. In addition to this combination, a photopolymerization initiator used in ordinary negative type photolithography may be further added. For example, benzophenone, methyl o-benzoylbenzoate,
4,4-bis (dimethylamine) benzophenone, 4,
4-bis (diethylamine) benzophenone, α-aminoacetophenone, 4,4-dichlorobenzophenone,
4-benzoyl-4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p-t-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-
Chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl-methoxyethyl acetal, benzoin, benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-
t-Butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzosuberone, methyleneanthrone, 4
-Azidobenzalacetophenone, 2,6-bis (p-
Azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-
Methoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-ethoxycarbonyl) oxime,
1,3-Diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, Michler's ketone, 2-methyl- [4- (methylthio ) Phenyl] -2-morpholino-1-propanone,
Naphthalene sulphonyl chloride, quinoline sulphonyl chloride, N-phenylthioacdrine, 4,4
-Azobisisobutyronitrile, diphenyl disulfide, benzthiazole sulfide, triphenylphosphine, camphorquinone and the like, but two or more kinds may be used in combination. The addition amount of the photocrosslinking initiator (C) is preferably 15 to 60 parts by weight per 100 parts by weight of the alkali-soluble resin. If it is less than 15 parts by weight, the reactivity is poor and the resolution becomes poor, and if it exceeds 60 parts by weight, there is a problem in storage stability, which is not preferable.

The silver powder (D) of the present invention is used to impart conductivity. The amount of silver powder is 1
It is preferably 400 to 1500 parts by weight per 00 parts by weight. If it is less than 400 parts by weight, there is a problem in conductivity after firing, and if it exceeds 1500 parts by weight, there is a problem in reactivity, and the resolution may deteriorate, which is not preferable. The particle size of the silver powder used is preferably 0.5 to 5.0 μm.

Glass frit (E) used in the present invention
Is for sintering silver after firing. The glass frit amount is 1 to 6 per 100 parts by weight of the alkali-soluble resin.
It is preferably 0 part by weight. If it is less than 1 part by weight, it cannot be sintered and the conductivity is low. The particle size of the glass frit used is preferably 0.1 to 3.0 μm.

The organic solvent (F) used in the present invention is used to make the paste have a desired viscosity and improve workability such as screen printing. Specific examples include alcohol solvents such as ethyl alcohol, isopropyl alcohol and n-propyl alcohol, cellosolve solvents such as methoxy alcohol and ethoxy alcohol, carbitol solvents such as methoxyethoxy ethanol and ethoxyethoxy ethanol, ethyl acetate. , Ester solvents such as butyl acetate, methyl methoxypropionate and ethyl lactate, cellosolve acetate solvents such as methoxyethyl acetate, ethoxyethyl acetate and ethyl cellosolve acetate, carbitol acetates such as methoxyethoxyethyl acetate and ethoxyethoxyethyl acetate Solvent, ethylene glycol dimethyl ether,
Ether-based solvents such as diethylene glycol dimethyl ether and tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-
Aprotic amide solvents such as 2-pyrrolidone, lactone solvents such as γ-butyrolactone, aromatic hydrocarbon solvents such as toluene, xylene and naphthalene, n-heptane, n-hexane and n-octane aliphatic hydrocarbons. Examples include organic solvents such as system solvents. The amount of the organic solvent is preferably 50 to 250 parts by weight with respect to 100 parts by weight of the alkali-soluble resin. When it is less than 50 parts by weight, the viscosity is too high and the film thickness becomes thin, so that pinholes may easily occur. On the contrary, when it exceeds 250 parts by weight, the viscosity is too low and silver powder precipitates during storage. It is not preferable because it aggregates.

Further, as an additive to the above components, a sensitizer,
Polymerization inhibitor, leveling agent, dispersant, defoaming agent, thickener,
A suspending agent or the like can be added if necessary.

The photosensitive silver paste of the present invention is prepared by weighing and mixing components of the composition excluding silver powder and glass frit in a room such as a yellow room, which is shielded from ultraviolet rays, and then using a three-roll mill or a stirrer. Make a uniform varnish.
The varnish is filtered through a mesh of 0.1 to 10 μm, and silver powder and glass frit are added to the varnish in a room such as a yellow room where ultraviolet rays are blocked, and mixed with a triple roll or a kneader to form a paste. To do. Paste is 10-1
Filter through a 00 μm mesh. The viscosity of the paste is adjusted with an organic solvent according to the application, but usually 1000 to 3
About 10,000 cps is preferable.

When the electrode pattern of the plasma display is formed using the photosensitive silver paste of the present invention, it is usually 5 to 30 μm on the glass substrate by a method such as screen printing.
Applied in the thickness of.

Then, the coating film on the substrate is heated and dried at 50 to 120 ° C. for about 10 to 30 minutes, and then ultraviolet rays are irradiated through a desired mask by a photolithography method to photo-cur the exposed portion. The light source used at this time includes ultraviolet rays, electron beams, X-rays and the like, and among them, ultraviolet rays are preferable. Usually, a high pressure mercury lamp is used. The usual exposure amount is preferably about 50 to 1000 [mJ / cm ² ] in consideration of productivity and the like.

Next, the unexposed portion is dissolved and removed with an alkaline developer to form a pattern. The development includes a dipping method and a spray method, but the latter is used for forming a fine pattern. Usually, an alkaline aqueous solution is used as the developing solution, but a metallic alkaline aqueous solution such as sodium hydroxide, calcium hydroxide or sodium carbonate, or an organic alkaline aqueous solution such as tetramethylammonium hydroxide, monoethanolamine or diethanolamine can also be used. A usual alkaline aqueous solution is often used at a concentration of about 0.1 to 2.0 wt%.

Next, the obtained pattern is baked in air to completely oxidize and evaporate the alkali-soluble resin, the crosslinkable monomer, the photopolymerization initiator and the organic solvent, which are photosensitive organic components. The temperature condition is 450 to 550 ° C. for 15 to 60 minutes, and the silver component is fusion-baked on the glass substrate.

When an electrode pattern is formed using the photosensitive silver paste of the present invention, the thickness of the conductive film after firing is 5 to 10
It is possible to form a fine pattern having a minimum line width of about 20 μm in μm. By using them, an image display device with high reliability and high image can be manufactured. As a method for manufacturing the image display device, a conventionally known method can be used.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. <Example 1> 100 parts by weight of a methyl methacrylate / methacrylic acid (molar ratio: 90/10) copolymer (1) as an alkali-soluble resin and ethylene oxide-modified trimethylolpropane acrylate 8 as an acrylic monomer.
0 parts by weight, 15 parts by weight of dimethylbenzyl ketal as the photopolymerization initiator (1), 12 parts by weight of 4-dimethylaminobenzoic acid as the photopolymerization initiator (2), and a photopolymerization initiator (3)
As an example, a varnish containing 10 parts by weight of isopropylthioxanthone and 150 parts by weight of γ-butyrolactone was prepared in a yellow room using a three-roll mill, and filtered with a 5 μm filter. Thereafter, in the yellow room, 800 parts by weight of silver (1) and 20 parts by weight of glass frit (1) were added to this varnish component to prepare a silver paste using a three-roll, and the silver paste was filtered with a 25 μm filter. . Various properties of this paste were evaluated and the results shown in Table 1 were obtained.

<Coating and printing> The above paste was applied on a glass substrate (500 mm) using a 325 mesh screen.
Square, 3 mm thick) to 400 mm square and apply at 70 ° C for 30
A solid film having a thickness of 12 μm was obtained by minute drying.

<Exposure and development> 1 is applied to the coating film prepared above.
50 [mJ / c] up to 50-300 [mJ / cm ² ] using a mask having a test pattern of 0-100 μm
m ² ], the ultraviolet rays of each step were irradiated. Then 0.5 wt%
The product was spray-developed with an aqueous sodium carbonate solution to remove the unexposed portion and washed with water.

<Baking> The coating film printed on the glass substrate was baked in air at 500 ° C. for 60 minutes to form an electrode pattern. <Evaluation> The film thickness, resolution and specific resistance of the baked coating film were measured and evaluated. The film thickness was measured with a surface roughness meter, and the resolution was observed with a metallographic microscope. The specific resistance was calculated from the film thickness by measuring the sheet resistance. The storage stability was evaluated by the number of days until the paste viscosity was increased by 50% with respect to the initial viscosity by allowing the paste to stand at 23 ° C. in the dark. Aggregation of silver powder was evaluated by the number of days from the date of preparation to the confirmation of aggregates. The pinhole is 30 mm at 70 ° C with paste applied on a 400 mm square.
It was dried for a minute, baked at 500 ° C. for 60 minutes without forming a pattern, and counted through light.

<Examples 2 to 5, Comparative Examples 1 to 13> A photosensitive silver paste was prepared by the same method and operation as in Example 1 except for the composition shown in Table 1, and evaluated in the same manner as in Example 1. I went. The evaluation results are shown in Tables 1 and 2.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

After applying the photosensitive silver paste of the present invention onto a substrate, it is possible to form a highly precise fine pattern with high sensitivity by photolithography without spreading around, and after firing. The conductivity of the obtained electrode is also good. Furthermore, it is suitable for long-term storage because the silver powder does not sink easily when stored at room temperature. As a result, low resistance, excellent conductivity, and high resolution of 50 μm or less can be achieved.
It can be obtained at an exposure dose of [mJ / cm ² ] or less, and is useful for forming a pattern electrode of an image display device represented by a plasma display.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01B 1/22 H01B 1/22 AF term (reference) 2H025 AA01 AA02 AB17 AC01 AD01 BC14 BC32 BC42 CA01 CA27 CB13 CB14 CB43 CB52 CC03 CC08 CC09 FA01 FA03 FA17 FA29 4J011 AA05 CB00 CC07 CC10 DA02 FA07 FB01 PA03 PA15 PA69 PB22 PB27 PB40 PC02 PC08 QA03 QA13 QA17 QA22 QA39 QA43 SA21 AA25 SA01 SA02 A01 WAA 29 A01 A23 A01 WAA 22 UA27 A01 WAA 22 A01 WAA 22 A01 BA40 DB06 DB09 DB11 DB36 FA05 GA07 GA08 5G301 DA03 DA32 DA42

Claims (2)

[Claims] 1. An alkali-soluble resin (A), a crosslinkable monomer (B) having an unsaturated double bond, a photopolymerization initiator (C), a silver powder (D), a glass frit (E), an organic solvent (F). Which is a photosensitive silver paste consisting of 100 parts by weight of the alkali-soluble resin (A) in the silver paste,
The crosslinkable monomer (B) having an unsaturated double bond is 40 to
150 parts by weight, photopolymerization initiator (C) 15 to 60 parts by weight, silver powder (D) 400 to 1500 parts by weight, glass frit (E) 1 to 60 parts, organic solvent (F) 50 to 25.
The photosensitive silver paste is 0 parts by weight, and is subjected to a filtration step after the varnish is formed and after the paste is formed. 2. An image display device manufactured using the photosensitive silver paste according to claim 1.