JPH05204151A - Photopolymerizable conductive paste composition - Google Patents

Abstract

PURPOSE:To form a thick film fine pattern high in conductivity with a paste containing a metallic powder in high concentration by using a photoradical generator comprising a thioxanthone type dyestuff and amine compound. CONSTITUTION:This composition is obtained by adding 10-300 pts.wt. of a polyfunctional monomer capable of radical polymerization and 0.1-10 pts.wt. of the photoradical generator to 50 pts.wt. of a binder polymer to impart photosensitivity and mixing 20-500 pts.wt. of the conductive metallic powder with 5 pts.wt. of this photosensitive resin composition. The photoradical generator is composed of the thioxanthone type dyestuff, such as 2,4-diethylthioxanthone or 2,4-dimethylthioxanthone, and the amine compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photopolymerizable conductive paste composition for patterning by photolithography and forming a metal conductor layer by a subsequent firing step.

[0002]

2. Description of the Related Art Conventionally, a non-photosensitive paste material in which an inorganic binder is mixed with an organic powder is screen-printed to obtain a patterned thick film insulator, resistor or conductor layer on a high density multilayer circuit board. It has been practiced to form a pattern on a substrate by using a printing technique such as the above, and to scatter the organic binder in the subsequent firing step.

However, in the screen printing method, an insulator having a line width of 100 μm or less, which is industrially stable,
It has been difficult to form patterns such as resistors and conductors. Further, near this limit, there is a problem that the screen plate making accuracy is poor and an error is likely to occur, which makes it difficult to increase the pattern density. Therefore, research has been conducted on a photosensitive paste in which a photosensitive resin composition and an inorganic powder are mixed for the purpose of obtaining a high-density pattern that exceeds the limit of the screen printing method. In particular, the conductor paste material, which has a high demand for fine wiring patterns, is important,
With the formation of finer patterns, it is required that the formed patterns have higher electrical conductivity.
Regarding the conductive paste composition, studies have been conducted on a photosensitive conductive paste composition in which a photosensitive resin and a metal powder are mixed (for example, JP-A-54-121967 and JP-A-54-13591). JP-A-59-14314
9 publication, European Patent Application Publication No. 414167).

In order to obtain a metal pattern having high electric conductivity, high dimensional stability and low residual carbon content, it is necessary to contain a high concentration of metal powder. However, in general, a system containing metal powder has low light transmittance, and it is difficult to form a pattern using a photosensitive conductive paste material containing metal powder in a high concentration. For example, JP-A-54-121967 and JP-A-54-13591 mentioned above.
In JP-A-59-143149 and JP-A-59-143149, in the description of the examples in which the metal powder was contained, the system containing the most metal powder was 45% by weight. The inventor of the present invention also added a copper powder 7 to a photosensitive resin component composed of polymethylmethacrylate, a bifunctional acrylate monomer and a benzyldimethylketal polymerization initiator described in the above patent.
An attempt was made to form a pattern in a copper paste composition containing 0% by weight by photolithography, but the pattern could not be formed due to insufficient curability in the depth direction of the exposed portion.

European Patent Application Publication No. 4141
No. 67, in the description of the example in which 82 wt% of copper powder is contained, a sheet resistance value of 4 is obtained at a film thickness of about 10 μm.
Although mΩ / □ is obtained, this value is about half the electric conductivity of bulk copper. The inventor
It is considered that it is necessary to add a metal powder in a higher concentration in order to obtain fine patternon having higher electric conductivity, and as shown in Comparative Example 4, European Patent Application Publication No. 414167. An attempt was made to make a fine pattern having a very high electric conductivity by using a photosensitive resin system similar to that containing 90% by weight of copper powder. However, in this system, the contrast between the exposed and unexposed areas was poor and a fine pattern could not be formed.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a photopolymerizable paste composition containing a metal powder in a high concentration, capable of forming a thick film fine pattern having a very high electric conductivity. To aim.

[0007]

Means for Solving the Problems As a result of earnest studies on the photosensitive resin composition, the present inventors have found that the use of a photo-radical generator composed of a thioxanthone dye and an amine compound as a photo-radical generator leads to a remarkable improvement. Even in a paste containing a metal powder at a high concentration, it was newly found that it is possible to form a fine pattern having electric conductivity comparable to that of bulk metal, and as a result of research, the present invention has been completed. I arrived. The present invention is based on the discovery that a composition containing a photoradical generator comprising a thioxanthone dye and an amine compound is extremely effective as a photopolymerizable conductive paste.

That is, the present invention is as follows. 1. 20 to 50 parts of metal powder based on 5 parts by weight of a photosensitive resin composition composed of the following three components (A), (B) and (C).
A photopolymerizable conductive paste composition comprising 0 parts by weight, wherein the photoradical generator as the component (C) comprises a thioxanthone dye and an amine compound. (A): 50 parts by weight of binder polymer (B): 10 to 300 polyfunctional radically polymerizable monomers
Parts by weight (C): 0.1 to 10 parts by weight of photoradical generator In the photopolymerizable conductive paste composition of the present invention (hereinafter referred to as paste composition), metal powder is contained in a high concentration of 83% by weight or more. However, patterning by photolithography is possible. In addition, this paste material made it possible to form a metal fine pattern having extremely high electrical conductivity in the firing process following exposure and development.

In the present invention, a polyfunctional radically polymerizable monomer and a photoradical generator are added to a binder polymer to impart photosensitivity, and a conductive metal powder is added to a photosensitive resin composition formed from the above compound. The present invention provides a mixed photopolymerizable conductive paste composition. Further, a conductor layer containing a metal as a main component is formed by a step of exposing and developing this composition and a step of baking thereafter.

The photosensitive resin composition in the present invention comprises three components of a binder polymer, a polyfunctional radically polymerizable monomer and a photoradical generator. The details will be described below. The binder polymer used in the present invention is a high molecular weight substance for forming an interpenetrating network structure with a polyfunctional radical-polymerizable monomer, an acrylic type, an amide type,
Imide type, polyalkylene glycol type, styrene type,
Various high molecular weight substances such as epoxy type and polyolefin type can be used. Although not particularly limited, a polymer formed from one or more ethylenically unsaturated compounds,
A polymer characterized by containing at least 1 mol% of a monomer unit of an ethylenically unsaturated compound having one or more carboxyl groups is particularly preferable. Although various compounds can be used as the ethylenically unsaturated compound, a monomer that is easily depolymerized or decomposed by heat to form a polymer in which carbon and other substances hardly remain is preferable.

As examples of the monomer unit which can be used in the present invention, various polymerizable vinyl monomers can be used, and examples thereof include compounds represented by the following chemical formula 1 and cyclic acid anhydride type compounds such as maleic anhydride. it can.

[0012]

[Chemical 1]

[Wherein R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atom, halogen atom, carboxyl group, ester group, amino group, acyl group, alkoxy group, hydroxyl group, acetoxy group, lower alkyl group, A phenyl group, or a lower alkyl group substituted with a halogen atom, a carboxyl group, an ester group, a hydroxyl group, a substituent such as an amino group,
Alternatively in Formula chromatography COOR ₅ Matawa CONHR ₅ [wherein, R ₅ is a hydrogen atom, an acyl group, an alkyl group having 1 to 18 carbon atoms, or ester group of the alkyl group, hydroxy group,
Substituted products with an allyl group, an acyl group, an ethylene oxide group, a carboxylic acid anhydride group, an acryl group, a methacryl group, or the like, or a formula (CH ₂ —CHR ₆ —O) _n R ₇ (in the formula, R
₆ is hydrogen or a methyl group, R ₇ is an alkyl group having 1 to 4 carbon atoms, n = 1 to 9)], or a substituent such as a halogen atom, an alkyl group, a haloalkyl group, a carboxyl group or a hydroxyl group. Represents a phenyl group substituted with. ] Specific examples thereof include the following monomers. Methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, lauryl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate,
Methacrylates or acrylates such as stearyl acrylate, 2-hydroxymethacrylate, 2-hydroxymethylmethacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, glycidylmethacrylate, styrene, chloromethylstyrene, α-methylstyrene, hydroxystyrene, Examples thereof include ethylene, vinyl chloride and vinyl acetate.

Of these, polymers containing methylmethacrylate, styrene and α-methylstyrene are particularly preferable because they have particularly excellent thermal decomposability even when fired in a non-oxidizing atmosphere. As an ethylenically unsaturated compound having a carboxyl group which is an example of the unsaturated compound represented by the above chemical formula 1, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and the like are preferable. is there.

Substituents that readily react with H ₂ O or alkalis to form carboxylic acids or carboxylates, such as various carboxylic acid anhydride groups, also exhibit the same effect as the carboxyl group. Examples thereof include the above-mentioned carboxyl group obtained by reacting a lower fatty acid anhydride, a lower fatty acid halide or the like with a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid. Mention may be made of carboxylic acid anhydrides of ethylenically unsaturated compounds. Alternatively, a cyclic acid anhydride type compound such as maleic anhydride can be used.

The molecular weight of the binder polymer used is not particularly limited, but a polymer having a weight average molecular weight (hereinafter referred to as molecular weight) of 10 to 3,000,000 is usually used. When a low molecular weight polymer having a molecular weight of less than 1000 is used, the retention of the conductive powder is deteriorated, which is not preferable. or,
When the molecular weight exceeds 3,000,000, the solubility in a solvent and a developing solution deteriorates, which becomes a problem in the preparation process and the development process of the paste composition. Preferably the molecular weight is 10,000 to 30
0,000 polymers, particularly preferably a molecular weight of 60,000 to 100
10,000 polymers, more preferably 100,000 to 100 in molecular weight
Any polymer can be selected. Further, it is preferable to use a polymer having a uniform molecular weight distribution in order to improve the developing characteristics.

In the binder polymer used in the present invention, the use of a polymer having 1 mol% or more of a carboxyl group-containing monomer unit is preferable because it improves the development characteristics of a fine pattern. The developer used in the developing step varies depending on the content of the carboxyl group-containing monomer unit in the binder polymer. The content of the carboxyl group-containing monomer unit in the polymer in order to use the aqueous developer cannot be generally stated because it depends on the balance with the radical-polymerizable monomer, but 5 mol% or more,
Preferably 10 mol% or more, particularly preferably 15 mol%
That is all. When the content of the carboxyl group-containing monomer unit is less than 5 mol%, it is not preferable because it is hardly soluble in the aqueous developer. Further, when developing with a polar organic solvent, the upper limit of the content of the carboxyl group-containing monomer unit is not particularly limited, but when developing with a nonpolar organic solvent, the content of the carboxyl group-containing monomer unit is 10 mol. % Or less, preferably 5 mol% or less. 1
If the content of the carboxyl group-containing monomer unit is more than 0 mol%, it becomes insoluble in the nonpolar organic solvent, which is not preferable.

The polyfunctional radical-polymerizable monomer used in the present invention is a compound containing in the molecule two or more functional groups that undergo a radical polymerization reaction by the action of a photoradical generator. Examples thereof include compounds containing an acryl group, a methacryl group, an acrylamide group, a maleic acid ester, an allyl group, a vinyl ether, a vinylamino group, an acetylenically unsaturated group and the like in the molecule. These compounds undergo a polymerization reaction by the action of a photoradical generator, form an interpenetrating network structure with the binder polymer, and thereby gelate to form a polymerization composition that is insoluble in a developer.

Although various compounds can be used as the radical-reactive monomer, a polyfunctional acrylate or polyfunctional methacrylate monomer is preferable because it has particularly high polymerizability and easily gels. For example, diethylene glycol diacrylate, triethylene glycol diacrylate,
Polyethylene glycol diacrylate such as tetraethylene glycol diacrylate, or polyurethane diacrylates and their corresponding methacrylates, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolmethane triacrylate, and the structure are shown in Chemical formula 2. Ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate whose structure is shown in Chemical formula 3, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, whose structure is shown in Chemical formula 4 Tetramethylolmethane tetraacrylate, ethylene oxy having the structure shown in Chemical formula 5 De-modified phosphoric acid triacrylate,
A polyfunctional acrylate represented by epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, or the like, or a methacrylate monomer corresponding thereto can be selected. Further, polyfunctional acrylates in which an acrylate group is introduced by subjecting a polymer containing a carboxyl group such as polymethacrylic acid, polyacrylic acid and polymaleic acid to butanediol monoacrylate, polyethylene glycol acrylate and the like to esterification and amidation reaction can be used.

In particular, a photopolymerizable conductive paste composition having high photopolymerization sensitivity was obtained in a system using bifunctional, trifunctional and tetrafunctional monomers. These polyfunctional radial polymerizable monomers may be used alone or as a mixture. The photosensitive resin composition in the present invention may contain a monofunctional monomer. The content is 50% by weight or less, preferably 30% by weight of the total amount of the polyfunctional radically polymerizable monomer.
It is below. When the monofunctional monomer is contained in an amount of more than 50 parts by weight, the formation of an interpenetrating network structure with the polymer in the exposed portion of the paste composition becomes insufficient, resulting in deterioration of gelation, which is not preferable.

[0021]

[Chemical 2]

[0022]

[Chemical 3]

[0023]

[Chemical 4]

[0024]

[Chemical 5]

[0025]

[Chemical 6]

The photoradical generator of the present invention comprises a thioxanthone dye and an amine compound, and is added in an amount of 0.1 to 10 parts by weight based on 50 parts by weight of the binder polymer (A). If the amount of the photo radical generator added is less than 0.1 parts by weight, the photocurability of the paste composition is low and it is not preferable.
Further, even if it is added in excess of 10 parts by weight, the photocurability is not improved, and conversely the curability is lowered, which is not preferable.
The thioxanthone dye used as the photoradical generator of the present invention is a compound having a thioxanthone structure in the molecule, and for example, the compound represented by the following chemical formula 7 can be used. Among the compounds, for example, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dipropylthioxanthone, and the like. Derivatives can be mentioned. These can be used alone or as a mixture of two or more kinds.

[0027]

[Chemical 7]

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atom, halogen atom, carboxyl group, ester group, acyl group, alkoxy group, hydroxyl group, acetoxy group,
A lower alkyl group or a lower alkyl group substituted with a substituent such as a halogen atom, a carboxyl group, an ester group, a hydroxyl group, an amino group or a phenyl group is shown. Further, aliphatic and aromatic amines are used as the amine compound which is an essential component used in combination with the thioxanthone dye. For example, triethylenetetramine, triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethylmethacrylate, 4,4'-dimethylaminobenzophenone, 4,
4'-diethylaminophenone, 4,4'-diethylaminobenzophenone, ethyl 4-dimethylaminobenzoate, (n-butoxy) ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate and the like can be mentioned. Particularly, aromatic compounds such as 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminophenone, ethyl 4-dimethylaminobenzoate, (n-butoxy) ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate. Amine is preferred. The amine compound is 0.1 to 1 with respect to 1 part by weight of the thioxanthone dye.
It can be added in an amount of 0 part by weight, preferably 0.5 to 5 parts by weight. Addition outside the above range is not preferable because it does not contribute to the improvement of the photocurability of the paste composition.

The proportion of the binder polymer and the polyfunctional radically polymerizable monomer in the photosensitive resin composition used in the present invention is important for the pattern forming characteristics of the photopolymerizable conductive paste composition. It is desirable that each ratio be in the following range. Binder polymer: 50 parts by weight Polyfunctional radically polymerizable monomer: 10 to 300 parts by weight If the amount of the polyfunctional radically polymerizable monomer exceeds 300 parts by weight, it becomes difficult to maintain a good viscosity as a paste composition. Further, the pattern formability in the exposure and development steps is deteriorated, which is not preferable. On the other hand, when the amount of the polyfunctional radical-polymerizable monomer is 10 parts by weight or less, the difference in solubility between the exposed portion and the unexposed portion in the developing step decreases, and the pattern formability deteriorates, which is not preferable. Preferably 20 to 100 parts by weight, more preferably 30 to 80 parts by weight of a polyfunctional radically polymerizable monomer is added to the binder polymer.

If desired, a thermal polymerization inhibitor, a solvent, an anticorrosive agent for preventing surface oxidation and the like can be added. As the thermal polymerization inhibitor, conventionally known hydroquinone, methylhydroquinone, t-butylcatechol, pyrogallol, phenol and its derivatives, salts of copper or iron and the like can be used. Thermal polymerization can be suppressed by adding about 0.01 to 1 part by weight to the photosensitive resin composition 100.

Further, glass frit or the like can be added in order to improve the adhesiveness to the substrate after firing.
The amount added is preferably 5% by weight or less of the metal powder. Addition of more than 10% by weight is not preferable because it causes a decrease in electric conductivity after firing. The addition of a solvent is carried out to adjust the paste viscosity when the photopolymerizable conductive paste composition of the present invention is applied onto a substrate, and the boiling point of the solvent is 60 to 260 ° C. for good operability. .. Those having a temperature of 60 ° C. or lower have high volatility, which causes a problem that viscosity is increased during kneading of the paste and storage stability is lowered. Further, if a material having a temperature of 260 ° C. or higher is used, the drying becomes insufficient, and it becomes difficult to bring it into close contact with the mask surface during exposure. Suitable solvents include, for example, n
-Methylpyrrolidone, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate and other high boiling point polyhydric alcohol derivatives, xylene and other high boiling point aromatic compounds, ketones, esters, terpenes There is.

In the present invention, the metal powder is gold,
Silver, platinum, palladium, copper, aluminum, nickel,
A metal such as tungsten alone or an alloy powder, a metal powder whose surface is coated with another metal, or the like can be used. In particular, gold, silver, platinum, palladium, copper alone or an alloy powder, or a copper powder coated with a noble metal such as gold, silver, platinum or palladium can be preferably used.

The surface of the copper-based metal powder having a small particle size is easily oxidized, and the oxygen content in the metal is large. When a powder having a high oxygen content is used, the viscosity of the paste may increase during paste preparation or storage, and the paste state may not be retained. In order to avoid such a problem, it is preferable to use a metal powder having an oxygen content of 2% by weight or less, preferably 0.5% by weight, more preferably 0.2% by weight or less due to surface oxidation. It is effective. In order to obtain a metal powder having a lower oxygen content, reduction treatment of the surface oxide layer by firing in a reducing gas atmosphere is effective.

The ratio of the metal powder to the photosensitive resin composition is
20 to 500 parts by weight of metal powder, preferably 25 to 300 parts by weight, based on 5 parts by weight of the total amount of the photosensitive resin composition,
More preferably, it can be selected in the range of 25 to 95 parts by weight.
When the proportion of the metal powder is 20 parts by weight or less, the packing density is not sufficient, the metal powders do not sinter well during firing, and the electrical conductivity is as high as that of bulk metal. It is not possible to form a conductor layer having sufficient strength. Further, it is not preferable because a film having a large amount of residual carbon is formed because the organic component cannot be sufficiently scattered. Further, volume shrinkage becomes remarkable in the firing step, which causes a problem that dimensional stability is lowered.
On the other hand, if the ratio of the metal powder exceeds 500 parts by weight, the pattern cannot be formed because the content of the photosensitive resin composition is too small.

The metal powder may have any shape such as spherical shape, columnar shape, and flaky shape. The particle size of the powder varies depending on the size and film thickness of the pattern of the conductor layer to be formed. Generally, when forming a pattern having a line width of about 100 μm, a particle size of 50 μm or less can be used. In particular, in order to obtain a pattern having a line width of about 50 μm, the particle size of the powder used is usually 0.01 to 10 μm, preferably 0.1 to 10 μm. It Further, a powder having a particle size distributed in this range can be used, but 0.4 to 5 μm
It is preferable to use a powder containing 80 wt% or more of particles having the above particle size. If particles smaller than 0.01 μm are used,
Base metals such as copper are easily oxidized and it becomes difficult to form a highly conductive pattern. Moreover, in order to obtain a pattern of about 50 μm, when particles larger than 20 μm are used, the resolution of the pattern is low. It is also possible to use a powder which has been subjected to a surface treatment such as coating a copper-based metal powder whose surface is easily oxidized with a polymer or the like.

The photopolymerizable conductive paste composition of the present invention can be applied to a substrate by a usual method using screen printing, a roll coater, a doctor blade or the like. The thickness of the paste composition applied on the substrate is not particularly limited, but it is preferably 50 μm or less in order to obtain a pattern of about 50 μm.

The photopolymerizable conductive paste composition is applied to a substrate, dried and then exposed using near-ultraviolet rays or ultraviolet rays. Considering the operability of the adjustment and patterning process of the photopolymerizable conductive paste composition, it is preferable to use a compound having a spectral sensitivity in the near-ultraviolet or the wavelength range of the ultraviolet region as a photoradical generator. It is preferable to use a light source that emits side light. For example, ultra high pressure mercury lamp, high pressure mercury lamp, xenon lamp,
Alternatively, a light source such as a laser that emits light in this wavelength range can be used.

Among the binder polymers used in the present invention, when a carboxyl group-containing binder polymer is used, the dispersibility of the metal powder in the photosensitive resin composition is extremely high. Therefore, when developing with a water-based developer or an organic solvent-based developer after exposure, the unexposed portion of the metal powder loosens out of the system in the form of fine particles, and even in a composition containing a high concentration of metal powder, the rate at which it loosens The development characteristics are far superior to those obtained when a conventional photosensitive resin composition using a binder polymer containing no carboxyl group in the photosensitive resin composition is developed with an organic solvent.

A weak alkaline aqueous solution is preferred as the aqueous developer. As an example of the alkaline developer, an inorganic alkali such as sodium carbonate, sodium hydroxide, potassium hydroxide or ammonia and an organic alkali aqueous solution such as hydroxytrimethylammonium, 2-hydroxyethyltrimethylammonium, organic amines such as ethanolamine are used. can do. The concentration of the alkaline aqueous solution is
It is 0.1% by weight or more and 5% by weight or less, preferably 0.3% by weight or more and 2% by weight or less. Even if an alkaline aqueous solution having a concentration higher than 5% by weight is used, the developing rate is not improved and
The use of an aqueous solution diluted with less than wt% is not preferable because the developing speed becomes slow. After rinsing the unexposed area with an alkaline aqueous solution, a rinse step of removing excess alkaline solution with water is effective.

As the organic solvent type developer, any solvent can be used so long as it dissolves the photosensitive resin composition used in the present invention. The developing method used in the present invention may be a conventional method. For example, a dipping method of immersing in a developing solution, a spraying method of spraying the developing solution and the like can be mentioned. Particularly, the spray developing method is extremely effective for forming a fine pattern.

In the present invention, a metal pattern having high electric conductivity can be obtained through a step of firing the paste composition pattern formed in the developing step. The step of baking means a step of scattering the photosensitive resin composition in the paste composition and sintering the metal powder. In the case of a copper-based metal that easily oxidizes, firing in a non-oxidizing atmosphere is preferable. As the gas for forming the non-oxidizing atmosphere,
An inert gas such as nitrogen, helium, argon or neon can be used, and the oxygen concentration must be kept at 100 ppm or less, preferably 50 ppm or less. In the case of a metal that is easily oxidized, a reducing gas such as hydrogen or carbon monoxide or a mixed gas with the above-mentioned inert gas can be used. The baking temperature varies depending on the type of the photosensitive resin composition used, but it is necessary to be at least a decomposition temperature of the photosensitive resin composition or more in order to scatter organic components. Further, since the metal powders sinter each other when the temperature of the metal used is higher than the sintering temperature, a conductor layer having high electrical conductivity can be obtained. Therefore, the firing temperature varies depending on the photosensitive resin composition and the type of metal,
Usually in the range of 300 to 1200 ° C, preferably 400 to
A range of 1000 ° C is used.

[0042]

EXAMPLES The present invention will be specifically described by the following examples and comparative examples, but the present invention is not limited thereto. The weight average molecular weight shown in the following examples was measured using the following GPC (gel permeation chromatography). GPT: manufactured by JASCO, (pump: TRI ROTAR-V, column: Shodex A-800P (pre-column), A-80M x 2 series,
Eluent: A calibration curve was prepared using THF and a standard polystyrene sample, and the weight average molecular weight was measured. )

[0043]

Example 1 To 50 parts by weight of a binder polymer having a molecular weight of 130,000 and consisting of 65 mol% of methyl methacrylate, 25 mol% of methacrylic acid and 10 mol% of butyl acrylate, an ethylene oxide-modified trimellilol propane acrylate represented by the following chemical formula 8 was expressed. 50 parts by weight, 2,
1.5 parts by weight of 4-diethylthioxanthone, 3.5 parts by weight of ethyl 4-dimethylaminobenzoate, and 135 parts by weight of n-methylpyrrolidone were stirred to obtain a photosensitive resin composition.

[0044]

[Chemical 8]

With respect to 5 parts by weight of this photosensitive resin composition,
45 parts by weight of copper powder having an average particle size of 3 μm was kneaded with a three-roll mill to obtain a photopolymerizable conductive paste composition. The oxygen concentration in the copper powder used was 0.15% by weight as a result of measurement using an oxygen / nitrogen simultaneous analyzer (EMGA-650, manufactured by Horiba, Ltd.). This paste composition was applied onto an alumina ceramics substrate using a roll coater and dried in an oven at 70 ° C. The film thickness after drying was 20 μm. Next, light of a 250 W ultra-high pressure mercury lamp was irradiated for 600 seconds in a nitrogen atmosphere through an exposure mask, and heat treatment was performed at 70 ° C. for 15 minutes. Then 1% by weight
Spray development was performed using an aqueous solution of sodium carbonate as a developer. The photomask used for forming the pattern is shown in FIG. In this pattern, it was possible to pattern up to a line width of 40 μm. This was kept at 500 ° C. for 1 hour in a nitrogen atmosphere, and further baked at 900 ° C. for 30 minutes. The pattern remaining on the substrate had a thickness of 15 μm and had the luster of metallic copper. Further, in the same manner as the above method, the line width is 1 mm, the length is 40 mm, and the film thickness after firing is 13 μm.
When a line pattern was formed and the volume resistivity was measured, it was 2.6 μΩ · cm. This was a value close to 1.7 μΩ · cm, which is the volume resistivity of metallic copper.

[0046]

Example 2 100 parts by weight of pentaerythritol triacrylate, 3 parts by weight of isopropylthioxanthone, and 4-dimethylaminobenzoic acid were added to 50 parts by weight of a binder polymer having a molecular weight of 110,000 and composed of 95 mol% of methyl methacrylate and 5 mol% of methacrylic acid. Ethyl acidate 10
Parts by weight, ethylene glycol monoethyl ether 130
The photosensitive resin composition was obtained by stirring the parts by weight. An average particle size of 2 with respect to 5 parts by weight of this resin composition
25 parts by weight of copper powder of μm was kneaded using a three-roll mill to prepare a photopolymerizable conductive paste composition. The oxygen content of the copper powder used was 0.1% by weight as a result of measurement using the same apparatus as in Example 1. This paste composition was applied on the entire surface of a ceramic substrate using a roll coater and dried at 70 ° C. to obtain a 25 μm film. Then, a latent image was formed by exposing with a 250 W ultra-high pressure mercury lamp, which is an ultraviolet light source, through a photomask for 600 seconds in a nitrogen atmosphere with an oxygen concentration of 3 to 5%. Further, this was developed by spray development using 1,1,1-trichloroethane as a developing solution. As a result of forming an image using the photomask shown in FIG. 1, it was possible to develop up to a pattern of 40 μm. Further, it is kept at 400 ° C. for 60 minutes in a nitrogen atmosphere, the organic binder component is removed, and then the temperature is raised to 850 ° C. to sinter the particles, and a volume resistivity of 3.2 μ having a metallic copper luster.
A conductor layer of Ω · cm was obtained.

[0047]

Example 3 Photosensitive resin composition 5 having the same composition as in Example 1
Average particle size 3 with an oxygen concentration of 0.08% by weight relative to parts by weight
95 parts by weight of copper powder of μm was kneaded using a three-roll mill to obtain a photopolymerizable conductive paste composition. Using a roll coater, a ceramic substrate having a thickness of 10 μm was coated on the entire surface. Exposure, development, and baking were performed in the same manner as in Example 1. As a result, a 60 μm pattern could be obtained in the photomask pattern shown in FIG.

[0048]

Examples 4 to 6 With respect to 5 parts by weight of the same photosensitive resin composition as in Example 1, gold, silver, an alloy of palladium and silver having an average particle diameter of 1 to 5 μm (the content of palladium is 30% by weight). 25 parts by weight were mixed using a three-roll mill to obtain a photopolymerizable conductive paste composition. These paste compositions were applied in a thickness of 15 μm on a ceramic substrate. The oxygen content of these noble metal powders was 0.1% by weight or less in each case. Exposure and development were performed in the same manner as in Example 1, and formation of a 60 μm pattern in the photomask pattern was confirmed.

[0049]

Example 7 Copolymer of styrene and maleic acid monoester (manufactured by Monsanto Co., trade name, Scripset 5
50) is used as a binder polymer and has an average particle size of 3
A metallic copper pattern having a film thickness of 15 μm and a line width of 80 μm could be obtained in the same manner as in Example 1 except that the amount of the copper powder was 25 parts by weight and the exposure was performed in a nitrogen atmosphere having an oxygen concentration of 3 to 5%. ..

[0050]

Example 8 Example 8 was repeated except that 30 parts by weight of ethylene oxide-modified trimellilol propane acrylate represented by the chemical formula 8 was used and 20 parts by weight of copper powder having an average particle size of 3 μm and an oxygen content of 0.08% by weight was used. A photopolymerizable conductive paste composition was prepared under the same conditions as in No. 1 to form a metallic copper pattern. As a result, a copper pattern having a film thickness of 10 μm and a line width of 60 μm was obtained.

[0051]

Example 9 Example 8 was repeated except that 80 parts by weight of ethylene oxide-modified trimellilol propane acrylate represented by the chemical formula 8 was used and 25 parts by weight of copper powder having an average particle size of 3 μm and an oxygen content of 0.08% by weight was used. A photopolymerizable conductive paste composition was prepared in the same manner as in 1, and a metal copper pattern was formed. As a result, a copper pattern having a film thickness of 10 μm and a line width of 60 μm was obtained.

[0052]

Example 10 As a binder polymer, a copolymer of maleic anhydride 3 mol%, styrene 3 mol% and methyl methacrylate 94 mol% was used, and the average particle size was 3 μm.
Example 2 except that copper powder having an oxygen content of 0.08 wt% and a 1 wt% choline aqueous solution was used as a developer.
In the same manner as above, a copper pattern having a film thickness of 20 μm and a line width of 60 μm was obtained.

[0053]

Example 11 Polymethylmethacrylate having a molecular weight of 360,000 was used as a binder polymer, and the average particle size was 2 μm.
A line width of 60 μm was obtained in the same manner as in Example 2 except that 1 part by weight of the silicon oxide-zinc oxide-lead oxide-based glass frit was added.
Pattern could be formed.

[0054]

[Example 12] For 5 parts by weight of the same photosensitive resin composition as in Example 1, 45 parts by weight of copper powder having a particle size distribution of 0.2 to 4 µm and an average particle size of 2 µm was mixed with an oxygen concentration of 10 ppm or less. The mixture was mixed using a three-roll mill in a nitrogen atmosphere to obtain a photopolymerizable conductive paste composition. The obtained paste composition was applied on an alumina substrate in a film thickness of 15 μm. The oxygen content of the copper powder used was 0.1% by weight or less. Exposure and development were carried out in the same manner as in Example 1 to obtain 40 μm with less undercut in the photomask pattern.
Formation of m pattern was confirmed. The volume resistivity of the metal copper thin film obtained after firing was 2 μΩ · cm.

[0055]

Comparative Example 1 A pattern formation was attempted in the same manner as in Example 2 except that polymethyl methacrylate having a molecular weight of 200,000 was used as a binder polymer and benzyl dimethyl ketal was used as a photoradical generator, but the pattern remained after spray development. I didn't.

[0056]

[Comparative Example 2] 1.5 parts by weight of benzyl as a photoradical generator and 3.5 of ethyl 4,4'-dimethylaminobenzoate
An attempt was made to form a pattern in the same manner as in Example 1 except that the parts by weight were used, but the photocurability of the surface was poor and a line width of 200
Even in the μm pattern, only very many defects were obtained.

[0057]

Comparative Example 3 2-Methyl-1-as a photo-radical generator
(4-Methylthiophenyl) -2-morpholinopropan-1-one (Ciba-Gaigi Co., Ltd., Irgacure907)
1.5 parts by weight and 3.5 parts by weight of ethyl 4,4'-dimethylaminobenzoate were used as a binder polymer to give a molecular weight of 2
A patterning was tried in the same manner as in Example 2 except that 0,000 polymethylmethacrylate was used, but the line width was 200 μm.
The following pattern could not be formed.

[0058]

Comparative Example 4 An attempt was made to form a pattern in the same manner as in Example 1 except that 5 parts by weight of benzophenone and 0.8 parts by weight of Michler's ketone were used as the photoradical generator. As a result, the solubility of the unexposed area was extremely poor, so that only a pattern having a very low contrast between the exposed area and the unexposed area was obtained, and a fine pattern with clear edges could not be obtained. .

[0059]

By using the photopolymerizable conductive paste composition of the present invention, it becomes possible to obtain a thick film fine pattern having high conductivity, which was impossible with the conventional paste.

[0060]

[Brief description of drawings]

[0061]

FIG. 1 is an explanatory diagram showing a photomask pattern used during exposure.

[0062]

[Explanation of symbols]

 20. Pattern line width (μm) 40. Pattern line width (μm) 60. Pattern line width (μm) 80. Pattern line width (μm) 100. Pattern line width (μm) 120. Pattern line Width (μm) 140. Pattern line width (μm) 160. Pattern line width (μm) 200. Pattern line width (μm) A. Twice the pattern line width B. 1.5 times the pattern line width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/40 501 7124-2H H01B 1/20 A 7244-5G H05K 1/09 D 8727-4E

Claims (1)

[Claims] 1. Metal powder 2 to 5 parts by weight of a photosensitive resin composition consisting of the following three components (A), (B) and (C):
A photopolymerizable conductive paste composition obtained by adding 0 to 500 parts by weight, wherein the photoradical generator as the component (C) comprises a thioxanthone dye and an amine compound. (A): 50 parts by weight of binder polymer (B): 10 to 300 polyfunctional radically polymerizable monomers
Parts by weight (C): 0.1 to 10 parts by weight of photoradical generator