JP2008041319A - Method of forming conductive baked material pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a conductive baked material pattern having sufficient conductivity after baking in the method of forming the conductive baked material pattern in an atmosphere by using a resin composition containing a base metal. <P>SOLUTION: The method of forming the conductive baked material pattern is the method of forming the conductive baked material pattern by forming a pattern of the resin composition containing the base metal on a base material and by baking the pattern in the atmosphere, and a temperature elevation speed at baking is 10 °C/min. or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a fine electrode circuit is formed on a glass substrate of a plasma display panel (hereinafter abbreviated as “PDP”), a ceramic substrate for an electric circuit wiring board, or the like using a resin composition containing a base metal. The present invention relates to a method for forming a conductive fired product pattern useful for the present invention, and a conductive fired product pattern in which an electrode and an electric circuit are formed using the method.

  As a method for forming a conductive fired product pattern on a substrate such as a glass substrate, a method for forming a conductive ceramic pattern using a photolithographic technique using a photocurable composition containing silver powder has been proposed. (See Patent Document 1).

  However, in the case of a photocurable composition containing silver powder, there is a problem that silver ions diffuse into the glass substrate by firing and the glass substrate turns yellow. In addition, there is a problem that the cost of raw materials increases because noble metals are used.

On the other hand, as a method for solving such a problem, a method using a metal other than silver powder, that is, a base metal powder has been proposed. However, when the base metal powder is used, there is a problem in that the metal surface is oxidized in the firing step in the atmosphere and desired conductivity cannot be obtained.
Japanese Patent Application Laid-Open No. 2003-162049

The present invention has been made in order to solve such problems of the prior art, and its main purpose is to form a conductive fired product pattern in the air using a resin composition containing a base metal. An object of the present invention is to provide a method for forming a fired product pattern having sufficient conductivity after firing.
Another object of the present invention is to provide a conductive fired product pattern having sufficient conductivity after firing by this method of forming a fired product pattern.

The inventor has intensively studied in order to realize the above object. As a result, by setting the rate of temperature rise during firing to 10 ° C./min or more, a conductive fired product pattern having sufficient conductivity after firing is formed in the air even when a resin composition containing a base metal is used. As a result, the present invention has been completed.
That is, the method for forming a conductive fired product pattern according to the present invention is a method of forming a pattern of a resin composition containing a base metal on a base material and firing the pattern in the air to form a conductive fired product pattern. And the temperature rising rate at the time of baking is 10 degree-C / min or more, It is characterized by the above-mentioned.

  According to the forming method of the present invention, a conductive fired product pattern having sufficient conductivity after firing can be formed in the air even when a resin composition containing a base metal is used. In addition, since the rate of temperature rise during firing is increased, the firing time can be shortened, which is extremely useful in productivity.

Hereinafter, the method for forming a conductive fired product pattern according to the present invention will be described with specific examples.
First, a photocurable resin composition containing a base metal is applied on the entire surface of a substrate, then dried, exposed and developed to form a pattern.

Here, ceramic, glass, or a metal substrate can be used as the substrate.
Examples of the method for applying the photocurable resin composition on the substrate include screen printing methods, bar coaters, blade coaters, and the like. Of these, the screen printing method is preferred. In addition, what is necessary is just to laminate on a base material, when the paste is previously formed into a film form.
Stainless steel, polyester, or the like can be used as a screen mesh material used in the screen printing method.
It is preferable that the coating film of the photocurable resin composition to be formed has a wet film thickness of 5 to 50 μm. The reason for this is that if the thickness is less than 5 μm, pinholes may be formed in the coating film. On the other hand, if the thickness exceeds 50 μm, the coating film becomes thick and the solvent is difficult to evaporate and drying may be insufficient.

  In the drying step, the wet coating film is dried at a drying temperature of 60 to 120 ° C. for 5 to 40 minutes using a hot air circulation drying furnace or a far infrared drying furnace, and the organic solvent is evaporated to obtain a tack-free coating film. If the drying temperature is less than 60 ° C., the solvent is difficult to evaporate, resulting in insufficient drying. On the other hand, if the drying temperature exceeds 120 ° C., a chemical reaction of the paste components occurs, and an undeveloped part is generated during development. If the drying time is less than 5 minutes, drying is insufficient, while if it exceeds 40 minutes, a chemical reaction of the paste components occurs, and an undeveloped part is generated during development.

In the exposure step, contact exposure and non-contact exposure using a negative mask having a predetermined exposure pattern are possible. As the exposure light source, a halogen lamp, a high-pressure mercury lamp, a metal halide lamp, an electrodeless lamp, or the like is used. The exposure amount is preferably about 30 to 1000 mJ / cm ² . If the exposure amount is less than 30 mJ / cm ² , the photocuring may be insufficient and the line may be chipped or cut. On the other hand, if it exceeds 1000 mJ / cm ² , line thickening or halation may occur.

  In the developing process, a spray method is used. As the developer, alkaline aqueous solutions such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, and aqueous amine solutions such as monoethanolamine, diethanolamine, and triethanolamine, particularly about 1.5% by mass or less. A dilute alkaline aqueous solution having a concentration is preferably used, but the carboxyl group of the carboxyl group-containing resin in the composition may be saponified and the uncured part (unexposed part) may be removed. It is not limited. Moreover, it is preferable to wash with water in order to remove an unnecessary developer after development. Further, the dry film thickness of the photocurable resin composition after development is preferably 2 to 30 μm. The reason for this is that if the thickness is less than 2 μm, pinholes may be formed in the coating film. On the other hand, if it exceeds 30 μm, it is difficult to remove the binder and blistering due to bubbles may occur.

Thus, the obtained pattern is baked in the atmosphere at a heating rate of 10 ° C./min or more, preferably 10 to 100 ° C./min, more preferably 30 to 100 ° C./min, about 400 to 600 ° C. A desired electrode pattern is formed by removing the organic component contained in the coating film.
Thereby, even if it uses the resin composition containing a base metal, the electroconductive fired material pattern which has sufficient electroconductivity after baking can be formed in air | atmosphere.
Here, it is not preferable that the rate of temperature increase is slower than 10 ° C./min because it is difficult to obtain conductivity. On the other hand, if the rate of temperature rise exceeds 100 ° C./min, cracking or the like tends to occur in the glass substrate, which is not preferable.
This is because if the debinding of the resin composition is completed before reaching the temperature at which the conductive powder sinters or fuses, the surface of the conductive powder is oxidized in the atmosphere, and the conductive powder is sintered or melted. This is because it is difficult to wear and it is difficult to obtain conductivity.

  In addition, as for the film thickness after baking, 1-30 micrometers is preferable. If the film thickness after firing is less than 1 μm, defects such as pinholes may be caused. On the other hand, if it exceeds 30 μm, firing curl may occur, which is not preferable.

In such a method for forming a conductive fired product pattern according to the present invention, the base metal constituting the resin composition is a metal other than a noble metal, specifically gold, platinum, silver, palladium, rhodium, indium, ruthenium, Metals other than the eight elements of osmium can be used. The conductive powder (A) containing at least a base metal in the present invention is a powder containing the above-described base metal, and an alloy composed of two or more kinds of metals and a simple substance or a mixture of two or more kinds can be used.
Moreover, when using a glass substrate as a base material, it is preferable that content of silver shall be 20 mass% or less from the surface of yellowing of a glass substrate, and content is also 20 mass about other noble metals from the surface of cost. % Or less is preferable.

  The conductive powder (A) containing such a base metal has an average particle size of 0.5 to 20 μm, preferably 1 to 15 μm. When the average particle size is smaller than the above range, the light transmittance is deteriorated and pattern formation becomes difficult. On the other hand, if it exceeds the above range, it is difficult to obtain line linearity, which is not preferable.

  The compounding quantity of the electroconductive powder containing such a base metal shall be 60-90 mass% in a resin composition, Preferably it is set as the ratio of 75-90 mass%. When the blending amount is less than the above range, sufficient conductivity of the conductive circuit pattern cannot be obtained. On the other hand, when the amount exceeds the above range, it is difficult to obtain sufficient fluidity during coating, which is not preferable.

Next, as the organic binder (B), a carboxyl group-containing resin, specifically, a carboxyl group-containing photosensitive resin itself having an ethylenically unsaturated double bond and an ethylenically unsaturated double bond. Any carboxyl group-containing resin can be used.
These carboxyl group-containing photosensitive resins and carboxyl group-containing resins may be used alone or in combination, but in any case, they may be blended in a proportion of 1 to 35% by mass of the total amount of the composition. preferable. When the blending amount of these polymers is less than the above range, the distribution of the resin in the film to be formed tends to be non-uniform, and it is difficult to obtain sufficient photocurability and photocuring depth, and patterning by selective exposure and development. It becomes difficult. On the other hand, when the amount is larger than the above range, it is not preferable because the pattern is distorted or the line width is easily shrunk during firing.

  The carboxyl group-containing photosensitive resin and the carboxyl group-containing resin each have a weight average molecular weight of 1,000 to 100,000, preferably 5,000 to 70,000, and an acid value of 50 to 250 mgKOH / It is preferable that it is g. Furthermore, in the case of a carboxyl group-containing photosensitive resin, those having a double bond equivalent of 350 to 2,000 g / equivalent, preferably 400 to 1,500 g / equivalent can be suitably used. When the weight average molecular weight of the resin is less than 1,000, it adversely affects the adhesion of the film during development. On the other hand, when it exceeds 100,000, development failure tends to occur, which is not preferable. When the acid value is less than 50 mg KOH / g, the solubility in an alkaline aqueous solution is insufficient and the development is likely to be poor. On the other hand, when the acid value exceeds 250 mg KOH / g, the adhesion of the film is deteriorated during development or the photocured part ( This is not preferable because dissolution of the exposed portion) occurs.

  In the present invention, the photopolymerizable monomer (C) is used for promoting the photocurability of the composition and improving the developability. Examples of the photopolymerizable monomer (C) include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylolpropane triacrylate, penta Erythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, trimethylolpropane propylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, glycerin dimethacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol Ritolol triacrylate hexamethylene diisocyanate urethane prepolymer, polyester acrylate and methacrylates corresponding to the above acrylates; polybasic acids such as phthalic acid, adipic acid, maleic acid, itaconic acid, succinic acid, trimellitic acid, terephthalic acid and the like Mono-, di-, tri- or more polyesters with hydroxyalkyl (meth) acrylates are mentioned, but not limited to specific ones, and these may be used alone or in combination of two or more. Can be used. Among these photopolymerizable monomers, polyfunctional monomers having two or more acryloyl groups or methacryloyl groups in one molecule are preferable.

  The amount of such photopolymerizable monomer (C) is suitably 20 to 250 parts by mass per 100 parts by mass of the organic binder (carboxyl group-containing photosensitive resin and / or carboxyl group-containing resin) (B). . When the blending amount of the photopolymerizable monomer (C) is less than the above range, it is difficult to obtain sufficient photocurability of the composition. On the other hand, when the amount exceeds the above range, the surface is larger than the deep part of the film. Since the photo-curing of the part is accelerated, uneven curing is likely to occur.

Specific examples of the photopolymerization initiator (D) include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2, Acetophenones such as 2-diethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2- Dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1 -Aminoacetophenones such as butanone; 2-methyla Anthraquinones such as traquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, etc. Thioxanthones; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone; or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphine oxide, bis (2,4,4) 6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl-2,4,6-trimethylbenzoylphenylphosphine Phosphine oxide such as preparative; various peroxides and the like can be used alone or in combination of two or more of these conventionally known photopolymerization initiator.
The mixing ratio of these photopolymerization initiators (D) is suitably 1 to 30 parts by mass per 100 parts by mass of the organic binder (carboxyl group-containing photosensitive resin and / or carboxyl group-containing resin) (B), Preferably, it is 5-20 mass parts.

The photopolymerization initiator (D) is composed of N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine. It can be used in combination with one or more photosensitizers such as tertiary amines.
Furthermore, when a deeper photocuring depth is required, a titanocene photopolymerization initiator such as Irgacure 784 manufactured by Ciba Specialty Chemicals, which starts radical polymerization in the visible region, and leuco dyes are cured as necessary. It can be used in combination as an auxiliary agent.

The photocurable composition of this invention can mix | blend the glass powder of the softening point 400-600 degreeC with the quantitative ratio which does not impair the characteristic of the photocurable resin composition of this invention as needed.
The glass powder can be added at a ratio of 50 parts by mass or less, preferably 10 parts by mass or less per 100 parts by mass of the conductive powder (A)) in order to improve the adhesion with the conductor circuit after firing. The reason is that if the blending amount is larger than the above range, sufficient conduction cannot be obtained after firing, which is not preferable. The glass powder preferably has a glass transition point (Tg) of 300 to 500 ° C. and a glass softening point (Ts) of 400 to 600 ° C. When the softening point of the glass powder is lower than 400 ° C., the organic binder is likely to be encapsulated, and the remaining organic binder is decomposed, so that blisters are easily generated in the composition. From the viewpoint of resolution, it is preferable to use glass powder having an average particle size of 10 μm or less, preferably 3 μm or less.

  As the glass powder, an amorphous frit mainly composed of lead oxide, bismuth oxide, zinc oxide or the like can be preferably used.

  In the present invention, when a large amount of inorganic powder such as conductive powder or glass powder is blended with the photocurable resin composition, the storage stability of the resulting composition is poor, and the coating work is caused by gelation or fluidity deterioration. There is a tendency to get worse. Therefore, in the composition of the present invention, in order to improve the storage stability of the composition, a compound having an effect of complexing or forming a salt with a metal or oxide powder which is a component of the inorganic powder is added as a stabilizer. be able to. Stabilizers include various inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, and boric acid; various types such as formic acid, acetic acid, acetoacetic acid, citric acid, stearic acid, maleic acid, fumaric acid, phthalic acid, benzenesulfonic acid, and sulfamic acid Organic acids: phosphoric acid, phosphorous acid, hypophosphorous acid, methyl phosphate, ethyl phosphate, butyl phosphate, phenyl phosphate, ethyl phosphite, diphenyl phosphite, mono (2-methacryloyloxyethyl) acid Acids, such as various phosphoric acid compounds (inorganic phosphoric acid, organic phosphoric acid), such as a phosphate, are mentioned, It can use individually or in combination of 2 or more types.

  In the present invention, the composition is made into a paste by diluting, enabling an easy coating process, then drying to form a film, and blending an appropriate amount of an organic solvent to enable contact exposure. Can do. Specifically, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, di Glycol ethers such as propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate , Esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol, and terpineol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha, 2,2,4 -Trimethyl- 1, 3-pentanediol monoisobutyrate etc. are mentioned, These can be used individually or in combination of 2 or more types.

  Further, if necessary, known and conventional thermal polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol and phenothiazine, and known and conventional thixotropic agents such as fine silica, organic bentonite, montmorillonite and fatty acid amide. , Antifoaming agents and / or leveling agents such as silicones, fluorines and polymers, imidazole, thiazoles, triazoles, silane coupling agents and other well-known and commonly used adhesion promoters, dispersion aids, etc. Additives can be blended.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, it cannot be overemphasized that this invention is not limited to the following Example. In the following, “parts” are all parts by mass unless otherwise specified.

It mix | blended with the composition ratio shown below, after stirring with a stirrer, it kneaded with the 3 roll mill, and produced the photosensitive resin composition.
(Photosensitive resin composition)
Organic binder 250 parts Trimethylolpropane triacrylate 74 parts EO-modified trimethylolpropane triacrylate 100 parts 2-methyl-1- [4- (methylthio) phenyl]-
2-morpholinopropan-1-one 10 parts Conductive powder 2222 parts Antifoam / leveling agent (XL490-50: manufactured by Ito Oil Co., Ltd.) 5 parts

As the conductive powder, a powder having an average particle diameter (D50) of 12 μm, a composition ratio (mass%) of tin of 96.5%, silver of 3%, and copper of 0.5% was used.

The organic binder is a carboxyl group-containing resin PB-383 (Tg = 63 ° C., acid value = 176 mgKOH / g, weight average molecular weight = 26,000) manufactured by Mitsubishi Rayon Co., 2,2,4-2, trimethyl-1, What was dissolved in 3-pentanediol monoisobutyrate to a solid content of 40 wt% was used.

(Example 1)
The photosensitive resin composition is applied onto the entire surface of a glass substrate using a 100 mesh polyester screen, and then dried at 80 ° C. for 30 minutes in a hot air circulating drying oven to form a film having good touch drying properties. Formed. Then, using the negative mask capable of forming a line pattern dimensions 4 mm × 100 mm, after the accumulated amount of the composition was exposed to a 900 mJ / cm ^2, 0.4 wt% _Na 2 CO ₃ solution temperature 30 ° C. Development was performed using an aqueous solution and washed with water. Finally, the temperature was increased at a temperature increase rate of 10 ° C./min in an air atmosphere, and firing was performed at 550 ° C. for 10 minutes to prepare a test piece.

(Example 2)
A test piece was prepared in the same manner as in Example 1 except that the rate of temperature increase was 20 ° C./min.

(Example 3)
A test piece was prepared in the same manner as in Example 1 except that the heating rate was 55 ° C./min.

(Comparative Example 1)
A test piece was prepared in the same manner as in Example 1 except that the rate of temperature increase was 2 ° C./min.

(Comparative Example 2)
A test piece was prepared in the same manner as in Example 1 except that the heating rate was 5 ° C./min.

Film thickness:
Using the above test pieces, the wet film thickness was measured with a wet film thickness meter (ERCHSEN wet gauge), and the developed film thickness and the fired film thickness were measured with a surface roughness meter (SE-30H manufactured by Kosaka Laboratory Ltd.).

Resistance value:
The resistance value was measured by a tester (HIOKI 3540 mΩ HITESTER) using the test piece.

Specific resistance value:
The specific resistance value was calculated from the obtained film thickness and resistance value according to the following formula.
Specific resistance value ρ (Ω · cm) = cross-sectional area S (cm ² ) × resistance value R (Ω) / length l (cm)
Cross-sectional area S (cm ² ) = film thickness (cm) × pattern width (cm)

These evaluation results are shown in Table 1.

As is clear from the results shown in Table 1, the fired product pattern forming method using the photocurable resin composition of the present invention forms a fired product pattern with sufficiently low resistance and specific resistance compared to the comparative example. I found that I can do it.

Claims (8)

A pattern of a resin composition containing a base metal is formed on a substrate, and the pattern is baked in the atmosphere to form a conductive fired product pattern, wherein the temperature rise rate during firing is 10 ° C./min. It is the above, The formation method of the conductive baked product pattern characterized by the above-mentioned. The forming method according to claim 1, wherein a temperature increase rate during firing is 10 to 100 ° C./min. The forming method according to claim 1, wherein the firing temperature is 400 to 600 ° C. The forming method according to claim 1, which is a method for forming a conductive fired product pattern used for a member of a plasma display panel. As the resin composition, (A) a conductive powder containing at least a base metal, (B) an organic binder, (C) a photopolymerizable monomer, and (D) a photocurable resin composition containing a photopolymerization initiator is used. The forming method according to any one of claims 1 to 4. The forming method according to claim 5, wherein the conductive powder (A) contains 80% by mass or more of a base metal. (A) Conductive powder containing at least a base metal, (B) an organic binder, (C) a photopolymerizable monomer, and (D) initiation of photopolymerization used in the method according to any one of claims 1 to 6. The photocurable resin composition containing an agent. A conductive fired product pattern obtained by the method according to any one of claims 1 to 6.