JP5540708B2 - Conductive paste and conductive pattern manufacturing method - Google Patents

Description

  The present invention relates to a conductive paste, particularly a photosensitive conductive paste suitable for electrodes and electronic circuit components of flat display such as a plasma display panel, a field emission display, and a fluorescent display tube, and a method for producing a conductive pattern.

  In recent years, in electronic circuit parts and displays, high definition such as high definition and light weight has been rapidly advanced, and accordingly, a technique for forming a fine conductive pattern at a low temperature is desired. As a technique for forming a fine conductive pattern, a pattern is formed on a substrate using a conductive paste composed of a conductive powder and an organic component, the organic component is volatilized by firing at 450 to 800 ° C., and the conductive powder is sintered. A method of forming a conductive pattern by doing so is known (for example, Patent Document 1). However, since heating is required at about 450 to 800 ° C., there is a problem that power consumption during the production of the conductive pattern is large and the environmental load is large. Furthermore, since heat resistance of the substrate and other members and dimensional stability due to heat are required, there are problems that the members that can be used are limited and it is difficult to achieve high performance.

  Therefore, a technique has been developed in which a conductive pattern is formed using a conductive paste at a low temperature of 250 ° C. or lower. For example, a technique of forming a pattern by screen printing and curing at a temperature of 350 ° C. or lower (for example, Patent Document 2), a technique of forming a pattern by a photolithography method and curing at about 150 ° C. (Patent Document 3), or the like. Can be mentioned.

JP 2009-75307 A JP 2009-70677 A International Publication No. WO2000 / 34830 Pamphlet

  In the above-described technique, conduction is ensured by, for example, contact between conductive powders dispersed in a cured organic component. Therefore, there is a problem that the electrical resistance in the length direction of the conductive pattern is particularly insufficient and the specific resistance increases. In addition, the technique of forming a conductive pattern using a curable conductive paste composed only of a solvent and conductive powder has a problem that high-definition pattern formation is impossible. The present invention solves such a problem, and provides a conductive paste that can be cured at a low temperature of 250 ° C. or less and that has a remarkably small specific resistance in the length direction, and a method for manufacturing the conductive pattern. Is.

  That is, the present invention comprises (A) silver flakes fused at 150 to 250 ° C., (B) an organic component composed of a compound having a 50% weight reduction temperature of 250 ° C. or higher, and (C) a 50% weight reduction temperature of 250 ° C. It is an electrically conductive paste characterized by containing the organic component which consists of the following compounds. Furthermore, it is the manufacturing method of the conductive pattern characterized by including the process of apply | coating an electrically conductive paste to a board | substrate, and the process hardened | cured at 150-250 degreeC.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrically conductive paste which can be hardened at the low temperature of 250 degrees C or less and whose specific resistance of a length direction is remarkably small, and an electrically conductive pattern can be provided.

  As a result of intensive studies on a conductive paste that can be cured at a low temperature, the inventors have found that the conductive paste can be achieved as described below.

  That is, the conductive paste of the present invention needs to contain (A) silver flakes fused at 150 to 250 ° C. (A) By containing the silver flakes fused at 150 to 250 ° C., the fluidity of the silver flakes is improved during thermosetting, and as a result, the number of contacts between the silver flakes is increased and the area of the contacts is It becomes larger and the conductivity is remarkably improved. The melting point is more preferably 150 to 200 ° C.

  Further, (A) the silver flakes are preferably single crystals. By using a single crystal, it is possible to ensure conductivity at low temperature curing.

  (A) It is preferable that the shape of silver flakes is a flake. By making it a flake shape, it can orient in a horizontal direction in a coating film, has more contacts, and can improve electroconductivity. As a specific shape, the long side in the direction perpendicular to the thickness direction is preferably within a range of 8 to 150 times the thickness. More preferably, it is 10 to 50 times. Furthermore, the short side in the direction perpendicular to the thickness direction is preferably in the range of 1 to 100 times the thickness. More preferably, it is 3 to 50 times.

  (A) As for the particle diameter of silver flakes, it is preferable that a center particle diameter is 0.1-12 micrometers. By setting it as this range, while being able to improve the dispersibility to a photosensitive organic component, the jaggedness of a pattern edge can be suppressed. More preferably, it is 0.3-7 micrometers. Here, the central particle size refers to a 50% particle size in a volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size distribution measuring device.

  Moreover, it is also preferable from a viewpoint of compatibility improvement to surface-treat the surface of (A) silver flakes as needed. The type of surface treatment is not particularly limited and can be appropriately selected depending on the component (B) or component (C).

  As such (A) silver flakes, for example, M612 (center particle diameter 6 to 12 μm, thickness 0.1 to 0.2 μm, melting point 250 ° C.), M27 (center particle diameter 2 to 7 μm, thickness 0.1 to 0.1) 0.15 μm, melting point 200 ° C., M13 (center particle diameter 1 to 3 μm, thickness 0.1 μm, melting point 200 ° C.), N300 (center particle diameter 0.3 to 0.6 μm, thickness 0.1 μm or less, melting point 150 ° C. ) (Both manufactured by Toxen Industries Co., Ltd.). These silver flakes may be used alone or in combination. In particular, in order to improve the filling rate, it is also preferable to use, for example, a combination of relatively large silver flakes such as M27 and M13 and (A) silver flakes having a small particle diameter such as N300 among the silver flakes described above.

  The electrically conductive paste of this invention needs to contain (B) the organic component which consists of a compound whose 50% weight reduction | decrease temperature is 250 degreeC or more. By containing the component (B), the dispersion of the silver flakes (A) can be improved to stabilize the paste, and the strength of the coating film can be made sufficient. Furthermore, since the component (B) has photosensitivity, a high-definition conductor pattern can be formed using a photolithography method. Here, the 50% weight reduction temperature represents the temperature at which the weight reaches 50% of the initial weight when the temperature is increased from room temperature at 10 ° C./min in the atmosphere.

  (B) A polymer can be contained as an organic component. The polymer is preferably a polymer having a function as a binder for satisfactorily dispersing silver flakes during pattern formation. Examples of polymers preferably used include acrylic resins, cellulose resins, epoxy resins, melamine resins, phenol resins, urea resins, polyimide resins, polyamide resins, polyimide amide resins, polycarbonate resins, vinyl chloride resins, polyethylene, polypropylene, and the like. Although it is mentioned, it is not limited to these.

  As described above, the conductive paste of the present invention is particularly preferably photosensitive. By having photosensitivity, a photolithographic method can be used for pattern formation, so that a finer pattern can be easily formed. In order to impart photosensitivity to the conductive paste of the present invention, it is preferable that the polymer has a high affinity for a developer such as an alkali or water. Such polymers include those having acidic groups in the side chain and / or terminal. Examples of the acidic group include, but are not limited to, a hydroxyl group, a phenol group, a carboxyl group, a sulfonyl group, and a phosphate group. The content of acidic groups is 40 to 200 mg / g in terms of polymer acid value. The polymer acid value referred to here is the weight of KOH required to neutralize 1 g of the polymer. By setting the polymer acid value within this range, it is possible to obtain a polymer having sufficient alkali solubility and excellent storage stability.

  In the present invention, it is preferable to use an ethylenically unsaturated acid such as an ethylenically unsaturated carboxylic acid as a copolymerization component of the polymer in order to introduce an acidic group into the side chain of the polymer. Specific examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, and acid anhydrides thereof. Among these, when a polymer having an alkali-soluble group is prepared by using radical polymerization, anionic polymerization, or cationic polymerization which can easily prepare a polymer, it is preferable to use highly reactive acrylic acid or methacrylic acid.

  Examples of other copolymerizable components that can be polymerized with the copolymerized component include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n- Pentyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, allyl acrylate, butoxyethyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, heptadecafluorodecyl acrylate, 2-hydroxyethyl acrylate, isobonyl Acrylate, 2-hydroxypropyl acrylate, isodexyl acrylate, isooctyl acrylate, lauryl acrylate Relate, stearyl acrylate, phenoxyethyl acrylate, 2-methoxyethyl acrylate, octafluoropentyl acrylate, trifluoroethyl acrylate, acrylamide, aminoethyl acrylate, phenyl acrylate, benzyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, 2-naphthyl acrylate , Thiophenol acrylate, benzyl mercaptan acrylate, a monomer in which 1 to 5 of the aromatic ring hydrogen atoms are substituted with chlorine or bromine, or styrene, p-methylstyrene, o-methylstyrene, m- Methyl styrene, chlorinated styrene, brominated styrene, α-methyl styrene, chlorinated α-methyl styrene, brominated α-methyl styrene, chloromethyl Styrene, hydroxy styrene, carboxymethyl styrene, vinyl naphthalene, vinyl anthracene, vinyl carbazole, and those that were changed to methacrylate acrylate of the above compounds. In this invention, these can be used 1 type or in combination of 2 or more types.

  The polymer having an acidic group preferably further has an ethylenically unsaturated group in the side chain. Photosensitivity can be imparted to the polymer by having an ethylenically unsaturated group in the side chain. Since the polymer component in the photocurable photosensitive composition has photosensitivity, the crosslink density of the exposed portion in the coating film increases, so that the developer resistance is enhanced. As a result, the contrast of solubility in the developing solution between the exposed portion and the unexposed portion is improved, so that a high-definition pattern can be formed with high accuracy. Furthermore, toughness can be imparted to the cured film after curing.

  As a method for introducing an ethylenically unsaturated bond, an ethylenically unsaturated compound having a glycidyl group or an isocyanate group, an acrylic acid chloride, a methacrylic acid chloride, or a mercapto group, an amino group, a hydroxyl group or a carboxyl group in the polymer There are methods in which carboxylic acids such as allyl chloride and maleic acid are reacted. As a preferred method for introducing an ethylenically unsaturated group in a simple manner, a method for reacting a glycidyl unsaturated compound having a glycidyl group or an isocyanate group with an acidic group of a polymer side chain will be described below.

  Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl (meth) acrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, crotonic acid glycidyl ether, and isocrotonic acid glycidyl ether. In particular, glycidyl (meth) acrylate is preferably used.

  Examples of the ethylenically unsaturated compound having an isocyanate group include (meth) acryloyl isocyanate and (meth) acryloylethyl isocyanate. Further, the ethylenically unsaturated compound having a glycidyl group or an isocyanate group, acrylic acid chloride, methacrylic acid chloride or allyl chloride is preferably added in an amount of 0.05 to 0.95 molar equivalent to the acidic group in the polymer. More preferably, it is 0.1-0.9 molar equivalent. When the addition amount is less than 0.05 molar equivalent, the photosensitive properties are poor, and it is difficult to form a high-definition pattern. When the addition amount is greater than 0.95 molar equivalent, the number of residual acidic groups becomes insufficient, and the solubility of the unexposed area is low. Since it tends to decrease, it is not preferable.

  The weight average molecular weight of the polymer having an acidic group is preferably 5,000 to 100,000, more preferably 8,000 to 40,000. By setting the weight average molecular weight of the polymer within this range, it is possible to impart desired fluidity to the conductive paste, and it is possible to achieve both resistance to the developer in the unexposed area and solubility in the developer in the exposed area.

  Furthermore, it is also preferable to contain a photoreactive compound as the organic component (B) composed of a compound having a 50% weight loss temperature of 250 ° C. or higher. The content of the photoreactive compound is preferably 5 to 60% by weight, more preferably 20 to 40% by weight in the component (B). By setting the content of the photoreactive compound within this range, (A) the developer solubility contrast can be sufficiently maintained even when there is an exposure light shielding effect by the silver flakes, and the storage stability is good. A conductive paste can be obtained.

  As the photoreactive compound, a compound containing a carbon-carbon unsaturated bond having photocuring can be used. For example, alcohols (for example, ethanol, propanol, hexanol, octanol, cyclohexanol, glycerin, trimethylolpropane, Pentaerythritol) acrylic acid or methacrylic acid ester, carboxylic acid (eg, propionic acid, benzoic acid, acrylic acid, methacrylic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, citric acid, etc.) and glycidyl acrylate , Glycidyl methacrylate, allyl glycidyl, or reaction products with tetraglycidyl methexylylene diamine, amide derivatives (eg acrylamide, methacrylamide, N-methylol acrylamide, methylene bisacryl Bromide, etc.), there may be mentioned reaction products of epoxy compounds with acrylic acid or methacrylic acid, it is preferred to use at least some polyfunctional compounds having two or more functional. By using such a polyfunctional compound, the conductive paste of the present invention can be efficiently cross-linked, and pattern processing with high definition becomes possible. Examples of such polyfunctional compounds include butanediol diacrylate, hexanediol diacrylate, nonanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, and polyethylene glycol diacrylate. , Propylene glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, glycerin diacrylate, 2-hydroxy-3-acryloyloxypropyl acrylate, dimethylol-tricyclo Decane diacrylate, bisphenol A diacrylate, ethylene oxide Examples thereof include side-modified bisphenol A-diacrylate, propylene oxide-modified bisphenol A-diacrylate, and the like. Examples of 3 to 6 functional compounds include trimethylolpropane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate (above, trifunctional compound), pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, (Tetrafunctional compound), dipentaerythritol hexaacrylate (hexafunctional compound), and the like. In these polyfunctional compounds, some or all of the acrylic groups may be replaced with methacrylic groups. Particularly preferred in the present invention are 3-6 functional compounds. By using a 3-6 functional compound, as mentioned above, cross-linking of the conductive paste can be made dense, and pattern processing with sufficiently high definition becomes possible. In the present invention, one or more of these can be used.

  In the conductive paste of the present invention, a polymerization initiator can be preferably used. Examples of the ultraviolet light-sensitive polymerization initiator include 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl- [4- (methylthio) phenyl] -2-morphol. Linopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2,2-dimethoxy-1,2-diphenylethane-1-one, bis (2 , 4,6-trimethylbenzoyl) -phenylphosphine oxide, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dihydroxy-2-phenylacetophenone, 2,2-dimethoxy-2-phenyl Acetophenone, 2,2-diethoxy-2-fur Sulfonyl acetophenone, and the like. In the present invention, one or more of these can be used. The polymerization initiator is added in the range of 0.05 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, with respect to 100 parts by mass of the total amount of the photosensitive monomer, photosensitive oligomer and photosensitive polymer. is there. If the amount of the polymerization initiator is too small, the photosensitivity will be poor, and if the amount of the polymerization initiator is too large, the residual ratio of the exposed area may be small.

  Visible light-sensitive polymerization initiators include a combination of a cationic dye that absorbs in the near ultraviolet and a borate anion, a combination of a silver halide sensitized with a near infrared sensitizing dye and a reducing agent, At least one radical generator such as titanocene, iron arene complex, organic peroxide, hexaaryl, biimidazole, N-phenylglycine, diaryliodonium salt and, if necessary, 3-substituted coumarin, cyanine dye, merocyanine And sensitizing dyes such as dyes, thiazole dyes, and pyrylium dyes.

  One or more of these can be used in the conductive paste of the present invention. The polymerization initiator (B) is preferably contained within the range of 0.1 to 30% by weight, more preferably 5 to 20 in the organic component composed of the compound having a 50% weight reduction temperature of 250 ° C. or higher. % By weight. By setting the content of the polymerization initiator within this range, (A) even under light shielding by silver flakes, the photoreaction rate of the conductive paste can be sufficiently increased and a sufficient degree of polymerization can be obtained.

  The conductive paste of the present invention preferably further contains (B) a dispersant as an organic component comprising a compound having a 50% weight loss temperature of 250 ° C. or higher. By containing a dispersing agent, the dispersibility to the organic component of silver flakes improves, and the jaggedness of an edge can be improved at the time of conductive pattern formation. Furthermore, there is an effect that the contact point between the silver flakes in the conductive pattern is increased and the resistance becomes low.

  As the dispersant, a base dispersant, an acid dispersant, a neutral dispersant and the like are preferably used. Examples of the base dispersant include Solsperse 20000 (trade name, manufactured by Fuji Film Imaging Colorant Co., Ltd.). As an acid dispersant, those having a phosphate anchor include Solsperse 41000 (trade name, manufactured by Fuji Film Imaging Colorant Co., Ltd.), Adeka Coal PS, CS, TS series (trade name, manufactured by Asahi Denka Co., Ltd.) NOPCOSPERTH 092 (trade name, San Nopco Co., Ltd.), ADEKA COAL P, EC series (trade name, manufactured by Asahi Denka Co., Ltd.) having sulfonic acid anchors, Solsperse 3000 having carboxylic acid anchors (Trade name, manufactured by Fuji Film Imaging Colorant Co., Ltd.), Floren G-700, G-700 DMEA (trade name, Kyoeisha Chemical Co., Ltd.) and the like. Neutral dispersants include alcohol / oxyethylene-based Adekatol LA, LO, DB series (trade name, manufactured by Asahi Denka Co., Ltd.) and oxyethylene copolymer-based Adeka Pluronic series (trade name, Asahi Denka Co., Ltd.) And Adeka Estor series (trade name, manufactured by Asahi Denka Co., Ltd.).

  The amount of the dispersant added is preferably (B) an organic component composed of a compound having a 50% weight loss temperature of 250 ° C. or higher, preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, and still more preferably Is 1 to 3% by weight. By setting the addition amount within this range, it is possible to prevent a decrease in sensitivity during pattern formation and improve the dispersibility of the conductive paste.

  The conductive paste of the present invention further contains (C) an organic component composed of a compound having a 50% weight loss temperature of 250 ° C. or less. (C) The dispersibility of silver flakes can be improved by containing an organic component composed of a compound having a 50% weight reduction temperature of 250 ° C. or less. Further, removal of the component (C) during drying of the coating film causes volume shrinkage, and there is also an effect of increasing the contact between the silver flakes and improving the conductivity. (C) As an organic component composed of a compound having a 50% weight loss temperature of 250 ° C. or less, a commonly used solvent can be used. For example, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, dioxane, acetone , Cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, benzyl alcohol, 3-methoxy-3-methyl-1-butanol, 2,2,2-trimethyl-1,3-pentanediol monoisobutyrate, terpineol, butyl Carbitol, butyl carbitol acetate, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, bromobenzene, chlorobenzene, dibromobenzene, dichlorobenzene, bromobenzoic acid, chlorobenzoic acid, etc. Organic solvent mixture containing one or more of these are used. (C) It is preferable that content of the organic component which consists of a compound whose 50% weight reduction | decrease temperature is 250 degrees C or less is 5-30 weight part with respect to 100 weight part of (A) silver flakes. (C) By setting the content of the organic component composed of a compound having a 50% weight reduction temperature of 250 ° C. or less within this range, the dispersibility can be improved and the volume shrinkage during drying of the coating film can be sufficiently achieved. Can be maintained at the optimum viscosity for coating.

  Next, although the method to manufacture a conductive pattern using the electrically conductive paste of this invention is demonstrated, this invention is not limited to this.

  The conductive paste of the present invention is preferably pre-kneaded with a revolving mixer etc. after preparing each component to have a predetermined composition, and then subjected to main kneading using a kneading device such as a three-roller. Disperse and prepare homogeneously. In addition, it is also preferable to appropriately filter and degas the conductive paste after the main kneading.

  Next, a substrate is prepared. In the present invention, since curing is sufficiently promoted at a low curing temperature, resin substrates such as polyimide, phenol resin, epoxy resin, polyether ether ketone resin, and polyether sulfone resin are added in addition to the conventional glass, metal, and ceramic substrates. Can be used. By using these resin substrates, the member can be reduced in weight and flexibility.

  Subsequently, the conductive paste of the present invention is applied on the substrate. As a coating method, it can apply | coat using methods, such as screen printing, a bar coater, a roll coater, a die coater, a blade coater, a spin coater, and can be dried as needed. The coating thickness can be determined in consideration of the thickness of the desired conductive pattern and the contraction rate of the conductive paste. The coating thickness can be adjusted by the number of coatings, the screen mesh, the viscosity of the conductive paste, etc., but is usually about 1 to 30 μm. Drying is performed using a hot air dryer, an IR dryer, a hot plate, or the like, for example, drying at 60 to 150 ° C. for 0.5 to 30 minutes to form a conductive paste coating film.

Next, the produced conductive paste coating film is exposed. Exposure is selectively performed through a photomask. Examples of the light source used at this time include near ultraviolet rays, ultraviolet rays, electron beams, X-rays, and laser beams. Although exposure conditions vary depending on the coating thickness, exposure is usually performed for 0.01 to 30 minutes using a light source with an output of 1 to 100 mW / cm ² .

  After the exposure, development is performed by utilizing the difference in solubility between the exposed portion and the non-exposed portion in the developer. Usually, the immersion method, the spray method, the brush method, and the like are performed. As the developer, an alkaline aqueous solution is preferably used. As the alkaline aqueous solution, sodium hydroxide, sodium carbonate, potassium hydroxide aqueous solution and the like, and as the organic alkali, a general amine compound can be used. Specific examples include tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, monoethanolamine, and diethanolamine. The density | concentration of aqueous alkali solution is 0.05-5 mass% normally, More preferably, it is 0.1-1 mass%. If the alkali concentration is too low, it is difficult to remove the soluble portion, and if the alkali concentration is too high, the pattern may be peeled off or corroded. The development temperature during development is preferably 20 to 50 ° C. in terms of process control.

  Finally, heat treatment is performed at 150 to 250 ° C. to impart conductivity to form a conductive pattern. For the heat treatment, a hot plate, a hot air dryer, an IR dryer, or the like is preferably used, and the heat treatment may be performed at a desired temperature, or a one-stage or multi-stage program may be set up. Although it may be performed under an inert atmosphere such as nitrogen, sufficient conductivity can be obtained even in air by using the conductive paste of the present invention. Thus, conductivity is imparted to form a conductive pattern.

The composition of the photosensitive conductive paste preferably used is shown below.
(Example of photosensitive conductive paste)
Polymer: A product obtained by adding 0.4 equivalent of glycidyl methacrylate to a carboxyl group of a copolymer of acrylic acid / methyl acrylate / styrene = 40/30/30 (weight average molecular weight 27000, acid value 100) , 50% weight reduction temperature 393 ° C.) 100 parts by weight Monomer: Trimethylolpropane triacrylate (manufactured by Kyoeisha Chemical Co., Ltd. “TPA330”, 50% weight reduction temperature 417 ° C.) 50 parts by weight Photopolymerization initiator 25 parts by weight of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (manufactured by Ciba Specialty Chemicals, “IC369”, 50% weight reduction temperature 322 ° C.) Solvent: γ -400 parts by weight of butyrolactone (50% weight loss temperature 146 ° C.) conductive powder: silver flakes (Tokusen "M-13" manufactured by Kogyo Corporation, 1920 parts by weight

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to this. Using the conductive paste of the present invention, conductive patterns with various finenesses were produced.

The raw materials used for the conductive paste are as follows.
Polymer: A product obtained by addition reaction of 0.8 equivalent of glycidyl methacrylate to a carboxyl group of a copolymer consisting of acrylic acid / methyl acrylate / styrene = 40/30/30 (molar ratio) (weight average molecular weight 29000) Acid value 100, 50% weight loss temperature 393 ° C.)
Photoreactive compound: Hexaacrylate compound (manufactured by Kyoeisha Chemical Co., Ltd., trade name “DPHA”, 50% weight loss temperature 420 ° C.)
Photopolymerization initiator: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (manufactured by Ciba Specialty Chemicals, trade name “IC369”, 50% weight loss temperature 322 ° C.)
Dispersant (I): Solsperse 41000 (trade name, phosphate dispersant, manufactured by Fuji Film Imaging Colorant Co., Ltd., 50% weight reduction temperature 301 ° C.)
Dispersant (II): Adeka Pluronic SO-135 (trade name, neutral dispersant, manufactured by Asahi Denka Co., Ltd., 50% weight reduction temperature 267 ° C.)
Solvent: γ-butyrolactone (50% weight loss temperature 146 ° C.)
・ High boiling point compound: Disparon L1980 (trade name, leveling agent, manufactured by Enomoto Kasei Co., Ltd., 50% weight reduction temperature 349 ° C.)
Conductive powder (I): Silver flake “M-13” (center particle size 1.53 μm, manufactured by Toxen Industries Co., Ltd.)
Conductive powder (II): Silver flake “N-300” (center particle diameter 0.50 μm, manufactured by Toxen Industries Co., Ltd.)
Conductive powder (III): Silver spherical powder (center particle diameter 2.50 μm)
A. Preparation of curable composition Weighing a predetermined amount of polymer, photoreactive compound, photopolymerization initiator, dispersant and solvent, stirring with a stirrer to make a uniform solution, then adding a predetermined amount of conductive powder It knead | mixed with the roller kneader and it was set as the curable composition. Table 1 shows the amount of addition used in each example and comparative example.

B. Production of Conductive Pattern A. Asahi Glass Co., Ltd. “PD-200” glass substrate (42 inches) The conductive paste prepared in (1) was applied with a screen printer and dried with a hot air dryer at 100 ° C. for 10 minutes to form a conductive paste coating film having a thickness of 10 μm. At this time, the change in weight before and after drying was measured and shown in Table 1.

Subsequently, the exposure was performed by a proximity exposure machine through a negative mask having four stripe patterns with lines / spaces of 50 μm / 50 μm, 75 μm / 75 μm, 100 μm / 100 μm, and 150 μm / 150 μm. The exposure was selected and performed in the range of 50 to 1000 mJ / cm ² according to the conductive paste to form a pattern. The pattern was cured under the conditions described in Table 1 to obtain a conductive pattern. The cured conductive pattern was observed, and the minimum line / space value at which a good pattern could be formed without disconnection or short circuit was defined as the resolution.

C. Conductive evaluation The conductive paste was pattern-printed on a glass substrate by screen printing to form a specific resistance measurement pattern having a thickness of 10 μm, a line width of 300 μm, and a length of 3744000 μm. Then, it hardened | cured on the conditions of Table 1, and measured the specific resistance using the tester. The measured values are shown in Table 1.

Example 1
In the pattern workability evaluation of the conductive paste produced using the conductive paste shown in Table 1, a pattern having a line / space of 60 μm / 60 μm or more was successfully produced. Furthermore, the specific resistance was 172 μΩ · cm.

(Example 2)
Example 1 was repeated except that the amount of solvent added was 6 parts by weight. In the pattern workability evaluation, a pattern having a line / space of 50 μm / 50 μm or more was successfully produced. Furthermore, the specific resistance was 43 μΩ · cm.

(Example 3)
Example 1 was repeated except that the amount of solvent added was 9 parts by weight. In the pattern workability evaluation, a pattern having a line / space of 40 μm / 40 μm or more was successfully produced. Furthermore, the specific resistance was 18 μΩ · cm.

Example 4
Example 1 was repeated except that the amount of organic component added was changed. In the pattern workability evaluation, a pattern having a line / space of 50 μm / 50 μm or more was successfully produced. Furthermore, the specific resistance was 21 μΩ · cm.

(Example 5)
Example 1 was repeated except that the amount of solvent added was 22 parts by weight. In the pattern workability evaluation, a pattern having a line / space of 50 μm / 50 μm or more was successfully produced. Furthermore, the specific resistance was 145 μΩ · cm. In addition, since the viscosity of the produced conductive paste was low, the conductive paste was separated 3 days after the paste was produced.

(Example 6)
Example 3 was repeated except that the addition amount of the polymer, photoreactive compound, and photopolymerization initiator was changed. In the pattern workability evaluation, a pattern having a line / space of 40 μm / 40 μm or more was successfully produced. Furthermore, the specific resistance was 19 μΩ · cm.

(Example 7)
Example 3 was repeated except that Dispersant II was used as the dispersant. In the pattern workability evaluation, a pattern having a line / space of 60 μm / 60 μm or more was successfully produced. Furthermore, the specific resistance was 37 μΩ · cm.

(Example 8)
Example 3 was repeated except that no dispersant was added. In the pattern workability evaluation, a pattern having a line / space of 80 μm / 80 μm or more was successfully produced. Furthermore, the specific resistance was 92 μΩ · cm.

Example 9
Example 3 was repeated except that conductive powder I and conductive powder II were used as the conductive powder. In the pattern workability evaluation, the light transmittance was reduced by the addition of the conductive powder II, so that only the pattern having a line / space of 100 μm / 100 μm or more could be satisfactorily produced. On the other hand, since the number of contacts of the conductive powder increased, the specific resistance was very good at 15 μΩ · cm.

(Example 10)
Example 9 was repeated except that conductive powder I and conductive powder II were used as the conductive powder. In the pattern workability evaluation, the light transmittance was reduced due to an increase in the amount of conductive powder II added, so that only patterns having a line / space of 150 μm / 150 μm or more could be produced favorably. On the other hand, since the number of contacts of the conductive powder increased, the specific resistance was very good at 13 μΩ · cm (Example 11).
Example 3 was repeated except that no photoreactive compound and photopolymerization initiator were added. Since no photosensitivity was imparted, a specific resistance measurement pattern was formed by screen printing, and the specific resistance was 28 μΩ · cm.

(Comparative Example 1)
Example 3 was repeated except that the conductive powder III was used as the conductive powder. In the pattern workability evaluation, a pattern having a line / space of 40 μm / 40 μm or more could be produced satisfactorily. However, the conductive powder did not fuse at 250 ° C., and therefore did not conduct.

(Comparative Example 2)
Example 3 was repeated except that a high boiling point compound was added instead of the solvent. In the pattern workability evaluation, only a pattern having a line / space of 100 μm / 100 μm or more could be produced satisfactorily, and further, the contact of the conductive powder was insufficient, so that it did not conduct.

Claims (5)

(A) silver flakes fused at 150 to 250 ° C., (B) an organic component composed of a compound having a 50% weight reduction temperature of 250 ° C. or more, and (C) a compound having a 50% weight reduction temperature of 250 ° C. or less. 5% to 20% by weight of the organic component (C) composed of a compound having a 50% weight reduction temperature of 250 ° C. or less with respect to 100 parts by weight of the silver flakes (A) fused at 150 to 250 ° C. A conductive paste characterized by containing in the range of part . The relative silver flakes 100 parts by weight of fusing with (A) 150~250 ℃, the (B) 50% weight reduction temperature has entailment range of 15 to 40 parts by weight of an organic component comprising a compound of above 250 ° C. The conductive paste according to claim 1. The conductive paste according to claim 1 or 2, wherein the organic component (B) composed of a compound having a 50% weight reduction temperature of 250 ° C or higher has photosensitivity. Furthermore, a dispersing agent is contained as said (B) organic component which consists of a compound whose 50% weight reduction | decrease temperature is 250 degreeC or more, The electrically conductive paste of Claims 1-3 characterized by the above-mentioned. The manufacturing method of the conductive pattern characterized by including the process of apply | coating the electrically conductive paste in any one of Claims 1-4 to a board | substrate, and the process hardened | cured at 150-250 degreeC.