JP2005306699A - Glass composition for silver paste, photosensitive silver paste using the same and electrode pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly fine electric conductor pattern excellent in long term reliability with low migration by using a photosensitive silver paste which uses a glass composition developed for an electric conductive paste capable of preventing the induction of electrode migration even if used for the highly fine electric conductor pattern. <P>SOLUTION: The glass composition for a silver paste contains boron of 10 mass% or less in terms of B<SB>2</SB>O<SB>3</SB>and silica as essential components. The following equation (I) relating to a compositional ratio in terms of oxides is approved to the glass composition for the silver paste and the photosensitive silver paste involving the glass composition : B<SB>2</SB>O<SB>3</SB>mass%+ZnO mass% (including 0 mass%)≤SiO<SB>2</SB>mass% (I). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a glass composition for silver paste and a photosensitive silver paste using the glass composition, and more specifically, an electrode material obtained by firing a pattern coating film formed by a screen printing method or a photolithography method. The present invention relates to a glass composition for silver paste that can be suitably used as a photosensitive silver paste and a photosensitive silver paste formed using the glass composition.

  Conventionally, in parts such as plasma display panels, CCD sensors, and image sensors, electrodes on non-alkali glass and other various glass substrates have been formed by vapor deposition. However, in this vapor deposition method, an electrode forming member is housed in a vacuum vessel to deposit a metal film, and not only the apparatus is large and expensive, but the loading and unloading of the member is cumbersome and time is required for evacuation. There was a fault that workability was bad. Further, it is difficult to increase the thickness of the electrode by vapor deposition, and it is not suitable for reducing the resistance of the line.

On the other hand, as another method for forming the electrode pattern layer on the substrate, a paste material in which a conductive powder is mixed with a non-photosensitive organic binder, for example, a dry type or thermosetting type conductive paste is used for screen printing or the like. A method of patterning on a substrate using a printing technique and a method of forming a conductor pattern using a photosensitive conductive paste and utilizing a photolithography technique have been proposed (see, for example, Patent Documents 1 and 2). Although this technique is excellent in that a conductor pattern can be formed without going through a complicated process, migration is induced and long-term reliability cannot be obtained when it is used for forming a high-definition pattern in which the space between electrode lines is narrow. It was in the situation.
Japanese Patent Laid-Open No. 10-269848 JP-A-11-224531

  The present invention was developed in view of the above-mentioned problems of the prior art, and its main purpose is a glass for conductive paste capable of suppressing the induction of electrode migration even when used for a high-definition conductor pattern. By developing a composition and using a photosensitive silver paste using the glass composition, an object is to provide a high-definition conductor pattern having excellent long-term reliability due to low migration.

  As a result of intensive research aimed at realizing the above object, the present inventors have found that the composition of the low-melting-point glass frit contained in the conductive paste is used to induce migration in a high-definition pattern formed using the conductive paste. It was found to have an important relationship. Further, by limiting the composition ratio to a specific range, it has been found that a conductive pattern excellent in conductivity and low-definition pattern forming property due to low migration properties can be easily obtained without going through complicated steps. It came to complete.

That is, according to the present invention, a glass composition for silver paste containing boron and silica as essential components and containing 10% by mass or less of boron in a glass composition in terms of B ₂ O ₃ , and oxidizing the composition ratio thereof. There is provided a glass composition for silver paste characterized in that the following formula (I) is established in terms of physical properties.

B ₂ O ₃ mass% + ZnO mass% (including 0 mass%) ≦ SiO ₂ mass% (I)
In one aspect of the present invention, SiO ₂ content of the silver paste glass composition is preferably 8 to 30 wt%.

  According to the present invention, there is also provided a photosensitive silver paste containing silver powder, a photosensitive organic component, and the glass composition, wherein the content of the glass composition is 2 to 15 masses per 100 mass parts of the silver powder. A photosensitive silver paste that is part of the range is provided.

  Furthermore, the present invention provides an electrode pattern formed by firing the photosensitive silver paste.

  According to the present invention, it is possible to provide a photosensitive silver paste excellent in migration characteristics (migration suppression effect) even when used for a high-definition electrode pattern.

  As a conductive paste for electrodes formed on a glass substrate, in order to obtain excellent conductivity by firing at a temperature of 620 ° C. or less, preferably in an air atmosphere, selection of conductive powder is important. It is common to use silver powder which is not affected by oxidation and is relatively inexpensive among precious metals. By using a screen printing method or a photolithography method, for example, high-definition patterning of about line / space = 40/40 (μm) is possible. In such a high-definition pattern, a silver paste that is conventionally used Then, as mentioned above, there is a problem of migration and there is a limit to high definition.

The low melting point glass frit used for the silver paste has a softening point (hereinafter referred to as “SP value”) and the amount of addition greatly affecting the adhesion and resistance value of the conductive paste such as the silver paste. As is known, the present inventors focused on the low melting point glass frit from the viewpoint of low migration, and as a result, it was found that the influence of the three components described below is large in suppressing migration. That is, increasing the component ratio (parts by mass) of SiO ₂ is effective in suppressing migration, while B ₂ O ₃ and ZnO significantly deteriorate migration when the component ratio is increased. Further, as a result of verifying the composition ratios of these components, the present inventors have found that the migration characteristics are the best at the composition ratio satisfying the following formula (I), and have completed the present invention.

B ₂ O ₃ mass% + ZnO mass% (including 0 mass%) ≦ SiO ₂ mass% (I)
_However, B 2 _{O 3} is 10 wt% or less.

  Hereinafter, the glass composition for silver paste of the present invention, and the photosensitive silver paste and electrode pattern using the glass composition will be described in detail.

  The glass composition for silver paste of the present invention is characterized in that boron and silica are essential components, and further, the following formula (I) is established in terms of oxide with respect to the composition ratio.

B ₂ O ₃ mass% + ZnO mass% (including 0 mass%) ≦ SiO ₂ mass% (I)
The SiO ₂ component has an inhibitory effect on migration in the silver paste, and its content is not particularly limited as long as it satisfies the formula (I), but it is preferably blended in the range of 8 to 30% by mass. If it is less than 8% by mass, the migration characteristics deteriorate, while if it exceeds 30% by mass, the softening point becomes too high, and for example, baking onto a glass substrate at a temperature of 620 ° C. or less may be difficult.

B ₂ O ₃ and ZnO are adversely affect components in the migration characteristics when the content rate increases, it is necessary to satisfy the formula (I) for that content.

B ₂ O ₃ is used as an essential component in the present invention in order to lower the softening point of the glass composition. The preferred softening point for the glass composition of the present invention is 400 to 590 ° C., and it is preferable to adjust the amount of B ₂ O ₃ added so that the softening point falls within this range. However, if the B ₂ O ₃ content exceeds 10% by mass, the degree of deterioration of the migration characteristics increases, and therefore the content does not exceed 10% by mass. B ₂ O A preferred content of ₃ to 8 wt%, more preferably less than 2-6% by weight.

  Although ZnO is not an essential component, it is a constituent element of the formula (I) as described above. Further, if the content exceeds 12% by mass, the glass may become unstable due to crystallization, and further, the migration characteristics are deteriorated and yellowing is caused when baked at a high temperature. %.

The glass composition of the present invention may be a lead-based or bismuth-based glass composition, and is preferably blended in the range of 40 to 90% by mass in terms of Pb ₂ O ₃ or Bi ₂ O ₃ . If the amount is less than 40% by mass, the adhesive strength of the conductor film to the substrate is not sufficient when the silver paste is baked on the glass substrate, whereas if it exceeds 90% by mass, the softening point of the glass frit becomes too low and the paste debinding is performed. As a result, the sinterability of the conductor film is lowered, and the adhesive strength with the substrate may be lowered. In the glass composition of the present invention used as a material for silver paste, the preferred softening point is 400 to 590 ° C. from the viewpoint of the adhesiveness and resistance value of the silver paste, and the preferred compounding ratio in the silver paste is the paste. It is 2-15 mass parts with respect to 100 mass parts of silver powder in.

The glass composition of the present invention may further contain BaO and Al ₂ O ₃ , and preferable contents are 0 to 20% by mass of BaO, 0 to 5% by mass of Al ₂ O ₃ , more preferably 0. .5 to 2.5% by mass. If the BaO content exceeds 20% by mass, the glass composition may have an excessively large expansion coefficient, which is not preferable. If the Al ₂ O ₃ content exceeds 5% by mass, the softening point of the glass composition increases. When the silver paste is baked on the glass substrate, the adhesive strength of the conductor film to the substrate may be insufficient, which is not preferable.

In addition, verification by the present inventors revealed that alkali metal oxides such as Na ₂ O, Li ₂ O, and K ₂ O other than the above components can also be involved in inducing migration in a high-definition pattern, Therefore, it is preferable that an alkali metal oxide is not contained in the glass composition of the present invention, and even when it is contained, it is preferable that the content is low. Moreover, since an alkali component can react with the silver powder in a silver paste and a glass substrate may yellow, it is preferable not to contain from a viewpoint of suppressing yellowing.

  As the powder particle diameter of the glass composition of the present invention, from the viewpoint of resolution, an average measured using a laser diffraction scattering type particle size distribution measuring device such as Microtrac or a particle size distribution measuring device using a laser Doppler method. The particle diameter is preferably 10 μm or less, and may be crystalline or non-crystalline.

  The glass composition of the present invention is used together with silver powder and an organic component as a silver paste material, and can suppress the occurrence of migration in a high-definition electrode pattern formed by using a screen printing method or a photolithography method. It is what.

  The organic component includes an organic binder, and the organic binder functions as a binder for each component before firing, or as a material for imparting photocurability and developability to the composition. This organic binder may be either photosensitive or non-photosensitive and includes a resin having a carboxyl group. Specifically, any of a carboxyl group-containing photosensitive resin itself having an ethylenically unsaturated double bond and a carboxyl group-containing resin not having an ethylenically unsaturated double bond can be used. Examples of the resin (which may be either an oligomer or a polymer) that can be suitably used include the following.

(1) a carboxyl group-containing resin obtained by copolymerizing (a) an unsaturated carboxylic acid and (b) a compound having an unsaturated double bond;
(2) A carboxyl group-containing photosensitive resin obtained by adding an ethylenically unsaturated group as a pendant to a copolymer of (a) an unsaturated carboxylic acid and (b) a compound having an unsaturated double bond;
(3) (a) a saturated or unsaturated carboxylic acid is reacted with a copolymer of (c) a compound having an epoxy group and an unsaturated double bond and (b) a compound having an unsaturated double bond; A carboxyl group-containing resin obtained by reacting the generated secondary hydroxyl group with (d) a polybasic acid anhydride;
(4) A carboxyl group obtained by reacting (f) a compound having a hydroxyl group with a copolymer of (e) an acid anhydride having an unsaturated double bond and (b) a compound having an unsaturated double bond Containing resin;
(F) a compound having a hydroxyl group and an unsaturated double bond is added to a copolymer of (e) an acid anhydride having an unsaturated double bond and (b) a compound having an unsaturated double bond. Carboxyl group-containing photosensitive resin obtained by reaction;
(6) A carboxyl group-containing photosensitive resin obtained by reacting (g) an epoxy compound and (h) an unsaturated monocarboxylic acid and reacting the resulting secondary hydroxyl group with (d) a polybasic acid anhydride;
(7) (b) An epoxy group of a copolymer of a compound having an unsaturated double bond and glycidyl (meth) acrylate, (i) having one carboxyl group in one molecule, and an ethylenically unsaturated bond A carboxyl group-containing resin obtained by reacting an organic acid not having a hydrogen atom and reacting the resulting secondary hydroxyl group with (d) a polybasic acid anhydride;
(8) (j) a carboxyl group-containing resin obtained by reacting a hydroxyl group-containing polymer with (d) a polybasic acid anhydride;
(9) Obtained by further reacting (c) a compound having an unsaturated double bond with a carboxyl group-containing resin obtained by reacting (j) a hydroxyl group-containing polymer with (d) a polybasic acid anhydride. Carboxyl group-containing photosensitive resin.

  In addition, a printing type resin can be used as the organic component. Examples of the resin include cellulose resins such as nitrocellulose, ethyl cellulose, and hydroxyethyl cellulose; acrylic resins such as polybutyl acrylate and polymethacrylate; Polymers; polyvinyl alcohol; polyvinyl butyral and the like can be mentioned, and these can be used alone or in admixture of two or more.

  The photosensitive organic component including the carboxyl group-containing photosensitive resin as described above, and the non-photosensitive organic component including the carboxyl group-containing resin or the printing type resin may be used alone or in combination. Even in this case, it is preferable that the organic binder containing them is blended in a proportion of 5 to 50% by mass of the total amount of the composition. When the blending amount of these resins is less than the above range, the distribution of the resin in the formed coating film is likely to be non-uniform, and it is difficult to obtain sufficient photocurability and photocuring depth. Patterning by mechanical exposure and development becomes difficult. On the other hand, if the amount is larger than the above range, it is not preferable because the pattern is liable to be distorted or the line width is reduced during firing.

  The carboxyl group-containing photosensitive resin and the carboxyl group-containing resin have a weight average molecular weight of 1,000 to 100,000, more preferably 5,000 to 70,000, and an acid value of 30 to 250 mgKOH / g. In the case of a carboxyl group-containing photosensitive resin, those having a double bond equivalent of 350 to 2,000, more preferably 400 to 1,500 can be suitably used. When the molecular weight of the resin is lower than 1,000, the adhesion of the film during development may be adversely affected. On the other hand, when the molecular weight is higher than 100,000, poor development is likely to occur, which is not preferable. On the other hand, when the acid value is lower than 30 mgKOH / g, the solubility in an alkaline aqueous solution is insufficient, and development failure tends to occur. Part) may occur, which is not preferable. Further, in the case of a carboxyl group-containing photosensitive resin, if the double bond equivalent of the photosensitive resin is less than 350, a residue is likely to remain at the time of baking, whereas if it is greater than 2,000, a work margin at the time of development. Is narrow, and a high exposure amount may be required at the time of photocuring.

  The photosensitive silver paste comprising silver powder and a photosensitive organic component together with the glass composition according to the present invention contains a photopolymerizable monomer in order to promote the imparting of photocurability of the composition and improve the developability. The Examples of the photopolymerizable monomer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate. Acrylate, pentaerythritol tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, trimethylolpropane propylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and methacrylates corresponding to the above acrylates; phthalic acid, adipine Acid, maleic acid, itaconic acid Examples include mono-, di-, tri- or higher polyesters of polybasic acids such as succinic acid, trimellitic acid, terephthalic acid, and hydroxyalkyl (meth) acrylate, but are limited to specific ones However, these can be used alone or in combination of two or more. Among these photopolymerizable monomers, polyfunctional monomers having two or more acryloyl groups or methacryloyl groups in one molecule are preferable.

  The blending ratio of the photopolymerizable monomer is suitably 20 to 100 parts by mass per 100 parts by mass of the organic binder. When the amount of the photopolymerizable monomer 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 amount of light in the surface layer portion is larger than that in the deep portion of the film. Since curing becomes faster, uneven curing tends to occur.

  The photosensitive silver paste of the present invention contains a photopolymerization initiator as a component for initiating a photoreaction. Specific examples of photopolymerization initiators that mainly absorb ultraviolet rays and generate radicals include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2 -Acetophenones such as phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, Aminoacetophenones such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 1-chloroanthraquinone Anthraquinones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, thioxanthones such as 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenone Benzophenones; or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6- Examples include phosphine oxides such as trimethylbenzoyldiphenylphosphine oxide and ethyl-2,4,6-trimethylbenzoylphenyl phosphinate; various peroxides, but are limited to specific ones Not be, and may be used in combination singly or two or more kinds.

  The blending ratio of the photopolymerization initiator in the paste is suitably 1 to 30 parts by mass, preferably 5 to 20 parts by mass per 100 parts by mass of the organic binder. When the amount is less than the above range, it is difficult to obtain sufficient photocurability of the paste. On the other hand, when the amount exceeds the above range, light transmission is inhibited and it is difficult to obtain deep photocurability.

  In addition, 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 dye are cured as necessary. It can be used in combination as an auxiliary agent.

The silver powder contained in the photosensitive silver paste of the present invention is a conductive powder selected in the present invention that is not affected by oxidation and can impart excellent conductivity to the paste by baking at 450 to 620 ° C. is there. Various shapes such as a spherical shape, a flake shape, and a dentrite shape can be used as the particle shape, but it is particularly preferable to use a spherical shape in consideration of optical characteristics and dispersibility. As an average particle diameter of the silver powder, a powder of 0.5 to 5.0 μm can be used as measured by a laser diffraction scattering type particle size distribution measuring device such as Microtrac or a particle size distribution measuring device using a laser Doppler method. When the average particle diameter is 0.1 μm or less, the light transmittance is deteriorated and it is difficult to draw a high-definition pattern, which is not preferable. On the other hand, when the average particle diameter is larger than 5 μm, it is difficult to obtain line edge linearity, which is not preferable. A specific surface area of 0.1 to 2.0 m ² / g can be preferably used. If the specific surface area is less than 0.1 m ² / g, there is a problem such as sedimentation during storage, which is not preferable. On the other hand, if it exceeds 2.0 m ² / g, the oil absorption increases and the fluidity of the paste is impaired. Therefore, it is not preferable.

  The mixing ratio of the silver powder is suitably 45 to 90 parts by mass with respect to 100 parts by mass of the photosensitive silver paste. When the blending ratio of the conductive powder is less than the above range, sufficient conductivity cannot be obtained in the conductor pattern formed using such a paste. On the other hand, when the amount exceeds the above range, This is not preferable because the adhesiveness deteriorates.

Further, for the purpose of adjusting the color tone, a black pigment made of a metal oxide or a composite metal oxide containing one or more of Fe, Co, Cu, Cr, Mn, Al, Ru, Ni as a main component, four Black materials such as cobalt trioxide (Co ₃ 0 ₄ ), ruthenium oxide, and lanthanum composite oxide can also be added.

  Furthermore, the photosensitive silver paste of the present invention includes an acid compound such as phosphoric acid, phosphate ester, carboxylic acid-containing compound, silicone-based, acrylic-based defoaming, etc. to ensure storage stability as necessary. Other additives such as a leveling agent, a thixotropy imparting agent for adjusting fluidity, and a silane coupling agent for improving the adhesion of the film can also be blended. Furthermore, if necessary, a known and commonly used antioxidant for preventing oxidation of the conductive metal powder, a thermal polymerization inhibitor for improving the thermal stability during storage, and a substrate during firing. Fine particles such as metal oxide, silicon oxide, boron oxide, and low-melting glass as a binding component can also be added. In addition, inorganic powders such as silica, bismuth oxide, aluminum oxide, and titanium oxide, organic metal compounds, metal organic acid salts, metal alkoxides, and the like can be added for the purpose of adjusting firing shrinkage.

  The photosensitive silver paste of the present invention is obtained by blending the above-described essential components and optional components in a predetermined ratio and uniformly dispersing them in a kneader such as a three roll or blender. The photosensitive silver paste of the present invention thus obtained is formed as a conductor pattern on the substrate through the following steps, for example. Such a conductor pattern can be suitably used as an electrode pattern on a front substrate and / or a rear substrate of a plasma display panel.

  (1) First, the photosensitive silver paste of the present invention is applied to a substrate, for example, a glass substrate serving as a front substrate of a plasma display panel (PDP), by an appropriate coating method such as a screen printing method, a bar coater, or a blade coater. In order to obtain a touch-drying property, the organic solvent is evaporated by drying at about 60 to 120 ° C. for about 5 to 40 minutes in a hot air circulating drying furnace or a far infrared drying furnace, and a tack-free coating is applied. Get a membrane.

  Here, the base material is not limited to a specific one, but for example, a heat resistant substrate such as a glass substrate or a ceramic substrate can be used.

  Note that the paste can be formed into a film in advance. In this case, the film may be laminated on the substrate.

(2) Next, the dry coating film formed on the substrate is subjected to pattern exposure and developed. As the exposure step, contact exposure or non-contact exposure using a negative mask having a predetermined exposure pattern is possible. As the exposure light source, a halogen lamp, a high-pressure mercury lamp, a laser beam, a metal halide lamp, a black lamp, an electrodeless lamp, or the like is used. The exposure amount is preferably about 50 to 1000 mJ / cm ² .

  As the development process, a spray method, an immersion method, or the like is used. Developers include aqueous alkali metal solutions such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and sodium silicate, and aqueous amine solutions such as monoethanolamine, diethanolamine and triethanolamine, especially about 1.5% by mass or less. A dilute alkaline aqueous solution having a concentration of 1 is preferably used, as long as the carboxyl group of the carboxyl group-containing resin in the composition is saponified and the uncured part (unexposed part) is removed. It is not limited to. Moreover, it is preferable to perform washing with water and acid neutralization in order to remove an unnecessary developer after development.

  (3) A predetermined conductor pattern is obtained by baking the pattern of the obtained photosensitive silver paste to remove the organic component contained in the paste.

  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.

(Synthesis example of organic binder)
A flask equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser is charged with diethylene glycol monoethyl ether acetate as a solvent and azobisisobutyronitrile as a catalyst, heated to 80 ° C. in a nitrogen atmosphere, and methacrylic acid. And a monomer prepared by mixing methyl methacrylate with a molar ratio of methacrylic acid: 0.4 mol and methyl methacrylate: 0.6 mol over about 2 hours, and after stirring for another hour, the temperature was raised to 115 ° C. and the mixture was lost. A resin solution was obtained.

  After cooling this resin solution, tetrabutylammonium bromide was used as a catalyst, 95-105 ° C., 30 hours, butyl glycidyl ether: 0.4 mol, addition reaction with the equivalent amount of carboxyl group of the obtained resin And cooled.

  Further, 0.26 mol of tetrahydrophthalic anhydride was added to the OH group of the obtained resin under the conditions of 95 to 105 ° C. and 8 hours, cooled, and taken out to obtain an organic binder A having a solid content of 55%. It was.

(Composition Examples 1-5, Comparative Composition Examples 1-4)
Using the organic binder A obtained as described above, the glass composition shown in Table 1 was blended at the composition ratio shown below as a glass composition, stirred with a stirrer, and then kneaded with a three-roll mill to obtain a paste. Then, a photosensitive silver paste (Composition Example 1) was produced. Further, composition examples 2 to 5 and comparative composition examples 1 to 4 were prepared using glass powders B to H shown in Table 1 in the range of 22 to 55 parts in place of glass powder A. These glass powders A to H are those having an average particle diameter in the range of 1.2 to 3.4 μm measured with a laser diffraction / scattering particle size distribution analyzer: LMS-30 (manufactured by Seishin Enterprise Co., Ltd.). did.

(Composition Example 1)
Organic binder A 180.0 parts Trimethylolpropane triacrylate 45.0 parts 2-Benzyl-2-dimethylamino-1-
(4-morpholinophenyl) -butanone 10.0 parts isopropylthioxanthone 1.0 part dipropylene glycol monomethyl ether 90.0 parts silver powder A ^* 550.0 parts glass powder A 38.5 parts phosphate ester 2.0 Part Defoamer (BYK-354: Big Chemie Japan Co., Ltd.) 1.0 part * Average particle diameter (laser diffraction scattering type particle size distribution analyzer: measured with Microtrac HRA): 2.0 μm, specific surface area (BET1 (Measured by the dot method): 0.42 m ² / g was used.

  With respect to each of the photosensitive conductive pastes of Composition Examples 1 to 5 and Comparative Composition Examples 1 to 4 thus obtained, the migration characteristics were evaluated by detecting the insulation resistance value and the presence or absence of dentlite generation. The evaluation method is as follows.

Specimen creation:
Each photosensitive silver paste for evaluation was applied on the entire surface of a glass substrate using a 180 mesh polyester screen, and then dried at 90 ° C. for 20 minutes in a hot air circulation drying oven to provide good touch drying properties. A good coating was formed. Next, using a metal halide lamp as a light source, pattern exposure was performed through a negative mask so that the integrated light amount on the dried coating film was 300 mJ / cm ^2, and then 0.5 mass% Na ₂ CO _{3 at} a liquid temperature of 30 ° C. Development was performed using an aqueous solution and washed with water. Next, the substrate on which the coating film pattern was formed in this manner was heated to 570 ° C. at 5 ° C./min in an air atmosphere and baked at 570 ° C. for 30 minutes to obtain a test piece on which a conductor pattern was formed. Created.

(Insulation resistance value)
Exposure / development was performed with a comb pattern of L / S = 120/80 μm, patterning was performed, and the process was performed until baking. A UV curable moisture-proofing agent was applied to the pattern and cured to prepare an evaluation piece. Then, it processed for 144 hours, applying DC80V in a 65 degreeC, 95% RH constant temperature high humidity tank, the insulation resistance value after a process was measured, and insulation deterioration was evaluated. The insulation resistance value is a measured value after 1 minute at an applied voltage of 500V.

(Dent light evaluation)
The presence or absence of the occurrence of silver dentlite between the comb-shaped electrodes after the evaluation of the test piece for which the insulation deterioration was evaluated was confirmed.

These evaluation results are shown in Table 2.

  From Table 2, it was found that the silver paste according to the present invention is excellent in migration characteristics even when used in a high-definition conductor pattern.

Claims (4)

A glass composition for silver paste containing boron and silica as essential components and containing 10% by mass or less of boron in a glass composition in terms of B ₂ O ₃ , and the following formula ( A glass composition for silver paste, wherein I) is satisfied.
B ₂ O ₃ mass% + ZnO mass% (including 0 mass%) ≦ SiO ₂ mass% (I) SiO ₂ content is 8-30 wt%, the silver paste glass composition according to claim 1.   A photosensitive silver paste comprising silver powder, a photosensitive organic component, and the glass composition according to claim 1, wherein the content of the glass composition is 2 to 15 parts by mass with respect to 100 parts by mass of the silver powder. Photosensitive silver paste in the range of parts by mass.   The electrode pattern formed by baking the photosensitive silver paste of Claim 3.