JP2003330164A - Photosensitive silver paste and image display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive silver paste for forming a high-precision fine electrode pattern by solving problems in a conventional electrode pattern forming method. <P>SOLUTION: The photosensitive silver paste consists of an alkali-soluble resin (A), a crosslinkable monomer (B) having an unsaturated double bond, a photopolymerization initiator (C), silver powder (D), glass frit (E) containing ≥50 wt.% bismuth oxide and an organic solvent (F), wherein the amount of the crosslinkable monomer (B) is 40-150 pts.wt. based on 100 pts.wt. alkali- soluble resin in the electroconductive resin paste. <P>COPYRIGHT: (C)2004,JPO

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 form a fine electrode pattern, 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 a screen plate is advantageous because it is possible to form a pattern on a substrate corresponding to a large screen of an image display device at a relatively low cost, but it is useful for forming a fine pattern of 50 μm or less. There was a limit in accuracy. For these reasons, a photosensitive silver paste for solving the problems of the conventional electrode pattern forming method and forming a highly precise fine electrode pattern has come to be used for forming an electrode of an image display device. Since these pastes are fired, glass frit is usually added to improve the sinterability. Many of these glass frits contain lead oxide for sintering at a low temperature of 400 ° C to 600 ° C. However, due to the recent increasing awareness of environmental issues, there is a growing movement to eliminate lead components. Furthermore, lead oxide tends to become ions in the paste, which accelerates the polymerization of the acrylic monomer, which may increase the viscosity during storage. Therefore, there is an increasing need for a glass frit that does not contain lead oxide and can be fired at a low temperature.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photosensitive silver paste which does not contain lead oxide as a sintering aid and to which is added a glass frit which can be fired at 450 ° C to 550 ° C. is there.

[0005]

[Means for Solving the Problems] Alkali-soluble resin (A), crosslinkable monomer having unsaturated double bond (B), photopolymerization initiator (C), silver powder (D), and bismuth oxide in an amount of 50% by weight or more. A photosensitive conductive resin paste comprising a glass frit (E) and an organic solvent (F) containing
40 to 150 parts by weight of the crosslinkable monomer (B) having an unsaturated double bond and 100 parts by weight of the photopolymerization initiator (C) with respect to 100 parts by weight of the alkali-soluble resin in the conductive resin paste.
5 to 60 parts by weight, silver powder (D) is 400 to 1500 parts by weight, glass frit (E) containing 50% by weight or more of bismuth oxide is 1 to 60 parts by weight, and organic solvent (F) is 50 to 25 parts by weight.
It is a photosensitive silver paste in the range of 0 parts by weight. More preferably, it is a photosensitive silver paste in which the photopolymerization initiator (C) is dimethylbenzyl ketal or 4-dimethylaminobenzoic acid. Further, it is an image display device manufactured 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, methoxy ethylene 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 40 to 150 parts by weight with respect to 100 parts by weight of the alkali-soluble resin. If it is less than the lower limit, the crosslinkability is poor and the resolution is poor.

The photopolymerization initiator (C) used in the present invention
Are preferably dimethylbenzyl ketal and 4-dimethylaminobenzoic acid for obtaining 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, pt-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, methylene Anthrone, 4-azidobenzalacetophenone, 2,6-bis (p-azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-
1,2-Butadione-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 sulfonyl chloride, quinoline sulfonyl chloride, N
-Phenylthioacdrine, 4,4-azobisisobutyronitrile, diphenyldisulfide, benzthiazole sulfide, triphenylphosphine, camphorquinone and the like, but two or more kinds may be used in combination.
The total amount of the photocrosslinking initiator (C) is the alkali-soluble resin 1
It is 15 to 60 parts by weight per 00 parts by weight. If it is less than the lower limit value, the resolution becomes poor, and if it exceeds the upper limit value, 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 400 to 1500 parts by weight per 00 parts by weight. If it is less than the lower limit, there is a problem in conductivity after firing, and if it exceeds the upper limit, there is a problem in photoreactivity, which is not preferable.

Glass frit (E) used in the present invention
Is composed mainly of bismuth oxide, has a function of helping the sintering of silver after firing, and is environmentally friendly because it does not contain lead oxide, and it can be fired at a temperature of 450 ° C to 550 ° C. Found. The glass frit used in the present invention contains 50% or more of bismuth oxide, and other components include boron oxide, zinc oxide, tin oxide, aluminum oxide, silicon oxide, cerium oxide, zirconium oxide, lithium oxide, Sodium oxide, magnesium oxide,
It contains one or more oxides such as barium oxide. The amount of glass frit is 10
It is 1 to 60 parts by weight per 0 parts by weight. If the amount is less than the lower limit, sintering cannot be performed, resulting in low conductivity, and if the amount exceeds the upper limit, the viscosity increases greatly during storage under light-shielding.

The organic solvent (F) used in the present invention is used to make the paste have a desired viscosity to improve workability such as screen printing.
Alcohol solvents such as ethyl alcohol, isopropyl alcohol, n-propyl alcohol, cellosolve solvents such as methoxy alcohol and ethoxy alcohol, carbitol solvents such as methoxy ethoxy ethanol and ethoxy ethoxy ethanol, ethyl acetate, butyl acetate, methoxy propionic acid. Ester solvents such as methyl and ethyl lactate, methoxyethyl acetate, ethoxyethyl acetate, cellosolve acetate solvents such as ethyl cellosolve acetate, methoxyethoxyethyl acetate,
Carbitol acetate-based solvents such as ethoxyethoxyethyl acetate, ether-based solvents such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. Aprotic amide solvent, γ
-Lactone solvents such as butyrolactone, aromatic hydrocarbon solvents such as toluene, xylene, and naphthalene, and organic solvents such as n-heptane, n-hexane, and n-octane aliphatic hydrocarbon solvents. The amount of the organic solvent is 50 to 250 parts by weight based on 100 parts by weight of the alkali-soluble resin. If it is less than the lower limit, the viscosity will be too high and the film thickness will be thin, and pinholes may easily occur.On the contrary, if it exceeds the upper limit, the viscosity will be too low and silver powder will settle and agglomerate during storage. It is not preferable because

Further, a sensitizer, a polymerization inhibitor, a dispersant, a defoaming agent, a thickener, a suspending agent, a leveling agent and the like can be added as additives to the above components.

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.
Silver powder and glass frit are added to the varnish, and the paste is prepared by mixing the varnish under the same conditions as the varnish with a three-roll or kneader.

When the electrode pattern of a plasma display is formed using the photosensitive silver paste of the present invention, it is usually 5 to 30 μm on a 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 5 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 is ultraviolet light,
There are electron beams, X-rays, etc., but 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. The normal concentration of the alkaline aqueous solution is often about 0.1 to 2 wt%.

Next, the obtained pattern is baked in air to completely oxidize and evaporate the alkali-soluble resin, the crosslinkable monomer and the photopolymerization initiator, which are photosensitive organic components. The temperature conditions are 400 to 600 ° C. for 15 to 120 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 1 to 10
It is possible to form a fine pattern having a minimum line width of about 30 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 as an alkali-soluble resin, 80 parts by weight of ethylene oxide-modified trimethylolpropane acrylate as an acrylic monomer, and a photopolymerization initiator (1). Dimethylbenzyl ketal 15
A varnish was prepared by adding 20 parts by weight of photopolymerization initiator (2) 4-dimethylaminobenzoic acid, 10 parts by weight of photopolymerization initiator (3) isopropylthioxanthone, and 150 parts by weight of butyl carbitol as an organic solvent. Then, add 800 parts by weight of silver powder and 80 parts of bismuth oxide to this varnish component.
A paste was prepared by adding 20 parts by weight of a glass frit containing 10% by weight. 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 80 ° C for 10
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. For storage stability, leave it at 23 ℃
It was evaluated by the number of days until the paste viscosity increased by 50% with respect to the initial viscosity. Aggregation of silver powder was evaluated by the number of days from the date of preparation to the time when aggregates were confirmed on the bottom of the container. Pinholes are pastes applied to 400 mm square at 80 ° C.
Dry for 10 minutes at 60 ° C at 500 ℃ without creating a pattern
After baking for a minute, the number of pinholes of 10 μm or more was counted through the light.

<Examples 2 to 5, Comparative Examples 1 to 11> 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 results are shown in Table 1.

[0025]

[Table 1]

[0026]

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. It is also suitable for long-term storage. As a result, low resistance, excellent conductivity, and high resolution of 40 μm or less can be obtained with an exposure amount of 200 [mJ / cm ² ] or less, which is suitable for forming pattern electrodes such as image display devices typified by plasma displays. It is useful. In addition, the photosensitive silver paste of the present invention does not contain lead and thus is excellent in the environment, and is a photosensitive silver paste that can be baked at 450 ° C to 550 ° C.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03F 7/028 G03F 7/028 H01B 1/22 H01B 1/22 A F term (reference) 2H025 AA00 AA19 AB14 AB17 AC01 AD01 BC13 BC42 CA05 CA27 CB42 CB45 CC09 FA35 FA39 4J011 PA03 PA15 PA69 PC02 QA03 QA13 QA22 QA23 QA24 RA03 SA54 SA61 WA01 4J026 AA43 BA27 BA28 DB36 FA04 GA08 5G301 DA03 DA33 DA34 DA37 DA42 DD01

Claims (3)

[Claims] 1. A glass frit containing an alkali-soluble resin (A), a crosslinkable monomer having an unsaturated double bond (B), a photopolymerization initiator (C), a silver powder (D), and 50% by weight or more of bismuth oxide ( E), a photosensitive conductive resin paste containing an organic solvent (F), wherein the crosslinkable monomer (B) having an unsaturated double bond is added to 100 parts by weight of the alkali-soluble resin in the conductive resin paste. 40 to 150 parts by weight, photopolymerization initiator (C) 15 to 60 parts by weight, silver powder (D) 400 to 1500 parts by weight, bismuth oxide 50
A photosensitive silver paste, characterized in that the glass frit (E) is contained in an amount of 1 to 60 parts by weight, and the organic solvent (F) is included in an amount of 50 to 250 parts by weight, which are contained in an amount of at least 1% by weight. 2. The photosensitive silver paste according to claim 1, wherein the photopolymerization initiator (C) is dimethylbenzyl ketal or 4-dimethylaminobenzoic acid. 3. An image display device manufactured using the photosensitive silver paste according to claim 1.