JP3520798B2 - Conductive paste for plasma display and plasma display and its substrate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive powder and a conductive paste used for forming a circuit pattern, and particularly to a conductive powder and a conductive paste for forming electrodes of a plasma display and a plasma display substrate. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a screen printing method has been used as a method for forming a circuit of a conductor on the surface of a circuit board. In this screen printing method, a conductive paste is mixed with an organic component such as an organic resin and a component such as glass for adhering a conductor and a substrate to each other by printing a conductive paste on the substrate surface by screen printing to form a conductor circuit in a predetermined pattern. Is forming.

In recent years, circuit board materials have been required to have smaller size, thinner film, higher density, higher definition, and higher reliability, and accordingly, improvement of pattern processing technology has been desired. Especially plasma display panel (PDP)
Unlike the circuit board, the electrode part of the circuit board is diagonal 2
There is a demand for pattern formation accuracy on a large substrate exceeding 0 to 40 inches, and high definition and thinning on that.

A surface discharge type PDP having a three-electrode structure suitable for color display includes a plurality of electrode pairs formed of a pair of display electrodes formed on one glass substrate and adjacent to each other in parallel.
There is a plurality of address electrodes that are formed so as to be orthogonal to the electrode pairs, which are formed on the other glass substrate that is arranged with a slight gap from this glass substrate.

The address electrodes have been formed by printing a silver paste or the like on a glass substrate by a screen printing method using a screen printing plate having a corresponding pattern and then firing it. However, in the screen printing method, it is difficult to make the width of the electrode pattern finer than 100 μm even if the size of the screen mesh, the pattern accuracy, and the printing conditions are optimized, and the electrode cross-sectional shape is “kamaboko”. However, there was a limit to fine patterning. Compared to the “rectangle”, the “kamaboko shape” has a smaller cross-sectional area even with the same thickness, resulting in higher resistance. Furthermore, in the screen printing method, the accuracy of the printing plate is
Since it depends on the precision of plate making, the dimensional error of the pattern becomes large when the printing plate becomes large. Therefore, it is technically difficult to manufacture a high-definition PDP having a large area of 25 inches or more.

In the surface discharge type PDP, the rear glass substrate is provided with address electrodes and barrier ribs, and then the phosphor layer is formed. The partition wall is formed on the address electrode by the following method. That is, after printing and drying the silver paste to be the electrode, the insulating glass paste for the partition wall is printed 10 to 15 times so as to have a desired height and printed and dried. After that, the silver paste and the insulating glass paste can be simultaneously fired to form the address electrodes and the partition walls. However, as the size of the PDP becomes larger, when the alignment for the partition is performed with one end of the glass substrate as a reference, a large positional deviation occurs between the address electrode and the partition due to the accumulation of errors at the other end of the glass substrate. . For this reason, a rear glass substrate for a high-definition plasma display cannot be obtained, and the increase in size is extremely limited, and it is necessary to solve the problem.

As a method for improving the drawbacks of these screen printing methods, Japanese Patent Laid-Open No. 206538/1989 and Japanese Patent Laid-Open No.
-296534 and JP-A-63-205255
After firing the insulating paste as described in Japanese Patent Publication No.
There are proposals for improving the electrode formation by printing and firing a conductive paste, using a photolithography technique for electrode formation, and patterning the conductive paste using a photoresist. In addition, it was not sufficient as a technique for obtaining an electrode that simultaneously satisfies the requirements of low resistance and large size.

Further, Japanese Patent Laid-Open No. 63-392504,
JP-A-2-268870, JP-A-3-17169
No. 0 and Japanese Unexamined Patent Publication (Kokai) No. 3-180092, a composition of an electrically conductive paste is studied, and a so-called photosensitive electrically conductive paste containing a photosensitive resin as an organic component in the electrically conductive paste is used to form a fine pattern by a photolithography technique. There have been proposed those which are intended to be made more efficient and those which are made to have an optimized metal powder diameter, but these techniques have not been sufficient as an electrode which simultaneously satisfies fine pattern formation, low resistance and large size. Further, JP-A-3-163
In Japanese Patent Laid-Open No. 727 and Japanese Patent Laid-Open No. 5-2715776, electrodes formed by a photosensitive conductive paste method are proposed as electrodes for a plasma display panel, but in addition to low resistance, high adhesion strength with a substrate is provided. It was not enough as an electrode.

Further, in JP-A-7-320533, the tap density and particle size of the conductive fine powder are optimized, and fine patterning is performed by using a photosensitive conductive paste using the conductive fine powder. However, if the conductive fine powder has a particle size of 2 μm or less, a large amount of light is scattered, and even a portion covered with a mask is photo-cured and a good circuit pattern cannot be formed. It is necessary to increase the thickness to 2 to 8 μm, and when the conductor thickness is reduced, pinholes are generated, and thinning cannot be achieved.

[0010]

It is an object of the present invention to form a fine pattern on a circuit pattern to be formed, an electrode of a plasma display, or a substrate for a plasma display, to reduce the thickness and to reduce the resistance. It is to provide a conductive powder and a conductive paste that can be formed.

[0011]

That is, the present invention has an average particle diameter of 0.5 to 2 μm and a tap density of 3 to 7 g /
cm ³ and further has a specific surface area of 0.4 to 1.5 m ² / g
That the conductive powder and the organic component are essential components.
It is a characteristic conductive paste for plasma displays .

The present invention also relates to the above plasma display.
(1) A substrate for plasma display or a plasma display characterized by using a conductive paste for a.

[0013]

[0014]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The conductive powder is usually mixed with an organic component, an adhesive component with a substrate, etc., and used for forming a circuit pattern in the form of a conductive paste. Therefore, the optimization of the conductive powder is performed together with the design of the conductive paste used.

At present, the method of forming a circuit pattern using a photolithography technique using a photosensitive conductive paste containing a photosensitive component in the conductive paste can form a highly precise pattern with the highest accuracy. Method, and the inventors of the present invention, for this photosensitive conductive paste,
The optimization was performed by taking into consideration the conductive powder used therein. As a result, the points to be considered in the circuit pattern formation by the photolithography method are that the lower part of the applied paste can be exposed and that the photo-curing spread to the part covered by the mask is small. It was concluded that this is achieved by the balance between the conductive powder that does not pass through the surface and that scatters on the surface and the organic component that acts as a light path.

Conventionally, as described in JP-A-7-320533, fine powder having a conductive powder of 2 μm or less causes a large amount of scattering, and even a portion covered with a mask is photo-cured, which is excellent. It has been considered that circuit patterns cannot be formed.

However, the inventors of the present invention can solve the above-mentioned problems by ensuring the dispersibility of even a conductive powder having a particle size of 2 μm or less and preparing and using a photosensitive conductive paste with a reduced amount of organic components. I got the conclusion. Therefore, in the present invention, the average particle diameter, the tap density, and further the specific surface area are selected as parameters showing the good dispersibility of the conductive powder, and the conductive powder is optimized by the parameters.

Therefore, the conductive powder of the present invention must have an average particle size of 0.5 to 2 μm. Here, the average particle diameter is measured using a laser type particle size distribution measuring device (Microtrac 9320-X100, a measurement sample is obtained by adding about 0.5 g of conductive powder to about 100 ml of pure water, and the dispersion condition is Measurement shall be performed at 380 μA for 5 minutes.

By using a conductive powder having an average particle size of 2 μm or less for the conductive paste, there are no defects such as pinholes and disconnections even with a thin thickness of 1 to 4 μm.
It is possible to obtain a low resistance circuit pattern. When the average particle size is larger than 2 μm, the surface of the paste coating film becomes rough, and pinholes and disconnections occur in thin films with a thickness of 4 μm or less, and the yield of circuit pattern formation decreases. The thickness of the circuit pattern is to be measured by a stylus type roughness meter (for example, surface roughness measuring instrument SE-3300 manufactured by Kosaka Laboratory Ltd.).

If the average particle size is smaller than 0.5 μm,
Since the cohesiveness is very high, it is difficult to obtain a paste in a state where powder is highly dispersed. Further, when using the photolithography technique, it is difficult to form a fine circuit pattern due to obstacles such as light scattering.

The tap density of the electroconductive powder of the present invention must be ³ to 7 g / cm ³ , preferably ^{3 to 5} g / cm ³ , and more preferably 4 to 5 g / cm ³ . The smaller the tap density, the lower the density of the conductive powder of the circuit pattern to be formed, and the higher the resistance, the more easily defects such as pinholes occur. Where 3 g / cm ³
When it becomes smaller, pinholes and disconnections occur in the formed circuit pattern, and the yield of circuit pattern formation decreases.

Further, as the tap density increases, the resistance can be reduced, but when the photolithography technique is used, the transmittance of ultraviolet rays used for photosensitization to the lower portion of the paste becomes poor. Therefore, tap density is 7g / cm ³
If it becomes larger, it becomes difficult to form a circuit pattern when the photolithography technique is used.

The tap density is ³ to 7 g / cm ³ , preferably ^{3 to 5} g / cm ³ , and more preferably 4 to 5 g / cm ^3.
Within the range, the ultraviolet transmittance is good and the accuracy of the circuit pattern to be formed is improved. Furthermore, a paste coating property is good and a dense coating film can be obtained.

The shape of the conductive powder is not particularly limited,
Since the resistance becomes lower when a more precise conductor film is formed,
Granular or spherical particles are preferred.

Further, in the present invention, the specific surface area of the conductive powder is preferably 0.4 to 1.5 m ² / g. When the specific surface area is 0.4 m ² / g or more, the circuit pattern accuracy is particularly excellent, and when the specific surface area is 1.5 m ² / g or less, light scattering is small when the photolithography technique is used, and the paste is used. Curing progresses sufficiently to the lower part, and peeling does not occur during development.

The conductive powders are Ag, Au, Pd, N
It is preferable to contain at least one selected from the group of i and Pt in an amount of 50% by weight or more, and 600 ° C. on a glass substrate.
A metal powder having a low theoretical resistance value that can be baked at the following temperatures is preferable. These can be used alone, as an alloy or as a mixed powder.

Among these metal powders, those containing 70% by weight or more of Ag can be preferably used from the viewpoint of cost and calcination property, and Ag alone is more preferable. As an example of the mixed powder, for example, Ag (80 to 98) -Pd
(20-2), Ag (90-98) -Pd (10-2)
-Pt (2-10), Ag (85-98) -Pt (15
.About.2) (the above parentheses represent% by weight) or the like, and a binary or ternary mixed metal powder can be used.

The conductive powder of the present invention can be produced, for example, by a wet reduction method, and can be produced by controlling the particle size by the reduction time and controlling the tap density by the washing conditions after the reduction. .

Next, the conductive paste will be described. The conductive paste of the present invention contains the conductive powder and the organic component as essential components.

Examples of the organic component include a cellulose derivative and an acrylic polymer having good thermal decomposability, but the organic component is not limited to this, and other soluble polymers may be used.

In particular, it is preferable that the organic component is a photosensitive conductive paste containing a photoreactive compound. In the case of a conductive paste having no photosensitivity, patterning is performed by using a screen printing method for forming a circuit pattern or an etching method using a photoresist. On the other hand, in the case of a conductive paste having photosensitivity, patterning can be performed in the steps of pattern exposure and development. The firing step is an essential step in any case.

As the photoreactive compound, an active carbon-
Examples thereof include compounds having a carbon double bond, and monofunctional and polyfunctional compounds having vinyl groups, allyl groups, acrylate groups, methacrylate groups, and acrylamide groups as functional groups are applied.

Above all, it is preferable to use an acrylic acid ester compound or a methacrylic acid ester compound as the photoreactive compound. Among the above-mentioned photoreactive compounds, various types of acrylic acid ester compounds and methacrylic acid ester compounds have been developed, so it is necessary to select them from the viewpoints of reactivity, developability and thermal decomposability. Because it is possible.

As the photoreactive compound, there are a photoinsolubilizing type compound and a photosolubilizing type compound, both of which can be used. In the present invention, however, they are easy to handle and have various quality designs. A photoinsolubilization type is preferably used. Preferred examples include those containing functional monomers, oligomers, and polymers having one or more unsaturated groups in the molecule.

Specific examples of the organic component containing the photoreactive compound include a photosensitive component selected from at least one selected from a photosensitive monomer, a photosensitive oligomer and a photosensitive polymer, and a photopolymerization initiator and a necessary component. A sensitizer may be included.

Further, regardless of the presence or absence of photosensitivity, a plasticizer, a thickener, a dispersant,
Other additives can be added as needed. Organic components added to the conductive paste and additives composed of various organic components affect the characteristics of circuits and electrodes in relation to the debinding property, so the type and amount of the organic components depend on their thermal decomposability. It is important to consider and select.

The conductive paste of the present invention preferably contains 0.5 to 5% by weight of glass frit in order to enhance the adhesion of the conductor to the glass substrate, and 1 to 3% by weight.
It is more preferable to contain. It is preferable that the amount of glass frit is small in order to reduce the resistance and the thickness of the circuit pattern. Since the glass frit is insulative, when the content exceeds 5% by weight, the resistance increases, and film peeling may occur due to the difference in thermal expansion coefficient between the conductive powder and the glass frit. Further, if it is less than 0.5% by weight, it is difficult to obtain a strong adhesive strength between the circuit pattern and the glass substrate.

Although the circuit pattern adheres to the substrate without adding glass frit, the adhesive strength is weak and the circuit pattern is easily peeled off by vibration, impact or the like. In particular, in a low temperature firing substrate such as a glass substrate, since the firing is performed at 600 ° C. or lower, the conductive powder may not be completely sintered and the adhesion may be insufficient.

That is, the glass frit has an effect of enhancing the adhesive force between the conductor and the substrate interface and is an important component because it is a sintering aid for sintering the conductive powder.

The conductive paste of the present invention can be particularly preferably used for forming electrodes of a plasma display panel or a substrate for a plasma display. At this time, the glass frit powder in the conductive paste contains an oxide that deteriorates the discharge characteristics of plasma. It is preferable to be substantially free of alkali metal oxides and / or alkaline earth metals such as sodium, lithium oxide, potassium oxide, barium oxide and calcium oxide. This is because the alkali metal component and alkaline earth metal in the glass frit react with silver in the electrode to cause yellowing. As a cause of this, it is presumed that silver undergoes an ion exchange reaction with an alkali metal or an alkaline earth metal, and silver colloids to cause yellowing. In the present invention, the main constituent components of the conductive paste are (a) conductive powder, (b) photosensitive organic component, and (c) glass frit. Here, the photosensitive organic component refers to a monomer, an oligomer, a polymer and a photopolymerization initiator. However, it suffices that at least one of the monomer, oligomer, and polymer contains a photoreactive compound. Illustrating a preferable composition range of these components, the conductive powder is 80 to 90% by weight, the glass frit is 1 to 3% by weight, the total amount of the monomer, oligomer and polymer is 9 to 15% by weight, and the photopolymerization initiator is a monomer. , 30% by weight based on the total amount of the oligomer, polymer and polymer. The photosensitive conductive paste having a composition in such a range transmits ultraviolet light well during exposure, fully exerts the function of photocuring, increases the film strength of the exposed portion during development, and provides fine resolution. The circuit pattern which it has can be formed. Furthermore, the adhesive strength of the conductor after firing is also high.

The conductive paste of the present invention includes, for example, the above-mentioned conductive powder, organic component and glass frit, and if necessary, a sensitizer, a plasticizer, a dispersant, a stabilizer and a thixotropic agent (thickening agent). Agent), an ultraviolet absorber, an organic or inorganic suspending agent, an organic solvent, etc. to form a slurry of the mixture, and after uniformly mixing the slurry adjusted to have a predetermined composition with a stirrer such as a homogenizer, It can be produced by uniformly dispersing with a three-roller or a kneader.

In order to prevent gelation of the conductive paste, it is effective to add benzotriazole to the conductive paste. In particular, it is more effective if the glass frit is surface-treated with benzotriazole and then mixed with the conductive paste.

The viscosity of the conductive paste includes conductive powder, composition / type of glass frit, organic component, thixotropic agent,
It is adjusted by the addition ratio of an organic solvent, a plasticizer, etc., but the range is 1,000 to 150,000 cps (centipoise). For example, the coating on a glass substrate can be performed by a screen printing method, a bar coater, a roller coater, or an applicator.
In order to obtain a film thickness of 2 to 10 μm by applying twice, 1,000 to 100,000 cps is preferable.

Next, a method for forming a circuit pattern using the conductive paste of the present invention will be described with reference to an example. First,
A film such as a negative film having a circuit pattern or a mask such as a chrome mask is formed by a photolithography method after a film obtained by applying a conductive paste on a substrate is heated at 70 to 120 ° C. for 20 to 60 minutes to be dried to evaporate solvents. UV light is applied to expose the photosensitive conductive paste by photocuring.

After the exposure, development is carried out by utilizing the difference in solubility between the exposed portion and the unexposed portion in the developing solution. In the developer,
A solution in which an organic component in the photosensitive paste, particularly an oligomer or a polymer can be dissolved is used.

The circuit pattern formed from the coating film of the conductive paste through the steps of exposure and development is then fired in a firing furnace to thermally decompose and remove organic components, and at the same time melt the glass frit to melt the glass substrate. The circuit pattern is formed by ensuring the close contact with.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this. Incidentally, the concentration in the examples is% by weight unless otherwise specified.

Example 1 As the conductive powder, a silver powder having an average particle diameter of 1.5 μm, a monodisperse spherical shape, a specific surface area of 1.2 m ² / g and a tap density of 4 g / cm ³ was used.

88 parts by weight of conductive powder, glass frit 3
Parts by weight, 7 parts by weight of photosensitive polymer (X-4007), 4 parts by weight of photosensitive monomer (trimethylolpropane triacrylate), photopolymerization initiator (2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholino-propanone-1) 1.6 parts by weight, sensitizer (DETX-S) 0.
8 parts by weight, plasticizer (dibutyl phthalate) 0.5 parts by weight, thixotropic agent (2- (2-butoxyethoxy))
SiO ₂ dissolved in ethyl acetate (concentration 15%))
3 parts by weight and 10 parts by weight of an organic solvent (γ-butyrolactone) were dissolved / mixed / dispersed and uniformly kneaded with a three-roller to prepare a photosensitive silver paste. Paste viscosity is 600
It was 0 cps.

The composition of the glass frit used for the paste (expressed as oxide,%) was bismuth oxide (85), silicon oxide (7.5), boron oxide (2.3), zinc oxide (2.1). And aluminum oxide (1.1). This glass frit was used after being treated with benzotriazole. The amount of benzotriazole used for the treatment was 4.5% based on the glass frit.

The characteristics of glass frit have a glass transition point of 4
The temperature was 60 ° C., the softening point was 540 ° C., the average particle size was 0.8 μm, the top size was 3.9 μm, and α ₅₀ to ₄₀₀ 73 × 10 ⁻⁷ / K.

25 cm × 35 cm of this photosensitive conductive paste
A cm square glass substrate was applied by a screen printing method. A 350-mesh polyester screen printing plate was used for coating, and the printing conditions were examined.
Various types of coating films were prepared. Next, the coating film is 40 ° C. at 40 ° C.
Dry for minutes.

Circuit pattern (stripe pattern, pitch 14
Approximately 30 with an ultra-high pressure mercury lamp with an output of 15 mW / cm ² through a negative type photomask having a line width of 0 μm and a line width of 50 μm).
UV exposure for 2 seconds was performed.

The development was carried out by showering with a 0.2% aqueous solution of monoethanolamine at 30 ° C. to remove the unexposed portion. Then, the remaining developing solution was washed away with a pure water shower and dried at 80 ° C. for 20 minutes.

The firing was carried out by raising the temperature at a rate of 250 ° C./hour and maintaining the maximum temperature of 590 ° C. for 15 minutes.

In this manner, a good circuit pattern having a pitch of 140 μm and a line width of 50 μm without any pinhole or disconnection was obtained. The thickness was 1.8 μm and 3 μm, respectively, and the conductor had a rectangular cross section. The specific resistance value was 3 μΩ · cm.

Example 2 Circuit pattern (striped) pitch used during exposure,
A circuit pattern was formed in the same manner as in Example 1 except that a negative photomask having different line widths was used.

The combination of mask pitch and line width is (pitch, line width) = (150, 15), (220,
80) and (430, 200) (unit: μm).

In all cases, a good circuit pattern as the mask was obtained.

Example 3 The same as Example 1 except that silver particles having an average particle size of 1.4 μm, a specific surface area of 1.4 m ² / g and a tap density of 5.5 g / cm ³ were used as the conductive powder. A circuit pattern was formed.

Pitch 1 with no pinholes or disconnections
A good circuit pattern having a line width of 40 μm and a line width of 50 μm was obtained. The thickness was 1.8 μm and 3 μm, respectively, and the cross section of the conductor was substantially rectangular and slightly reverse tapered. The specific resistance value was 3 μΩ · cm.

Example 4 An AC (alternating current) type plasma display panel was produced by the following procedure.

First, the photosensitive conductive paste used for producing the back plate was prepared.

As the conductive powder, a monodisperse sphere having an average particle diameter of 1.5 μm, a specific surface area of 1.2 m ² / g, and a tap density of 4 g
/ Cm ³ of silver powder was used.

88 parts by weight of conductive powder, 3 glass frit
Parts by weight, 7 parts by weight of photosensitive polymer (X-4007), 4 parts by weight of photosensitive monomer (trimethylolpropane triacrylate), photopolymerization initiator (2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholino-propanone-1) 1.6 parts by weight, sensitizer (DETX-S) 0.
8 parts by weight, plasticizer (dibutyl phthalate) 0.5 parts by weight, thixotropic agent (2- (2-butoxyethoxy))
SiO2 dissolved in ethyl acetate (15% concentration))
3 parts by weight and 10 parts by weight of an organic solvent (γ-butyrolactone) were dissolved / mixed / dispersed and uniformly kneaded with a three-roller to prepare a photosensitive silver paste. Paste viscosity is 600
It was 0 cps.

The composition of the glass frit used in the paste (expressed in oxide,%) was bismuth oxide (85), silicon oxide (7.5), boron oxide (2.3), zinc oxide (2.1). And aluminum oxide (1.1). This glass frit was used after being treated with benzotriazole. The amount of benzotriazole used for the treatment was 4.5% based on the glass frit. The characteristics of the glass frit are as follows: glass transition point 460 ° C., softening point 540 ° C., average particle size 0.8 μm, top size 3.9 μm and α50.
˜40073 × 10 −7 / K.

This photosensitive conductive paste was used as 340 × 260.
It was applied to a 2.8 mm size glass substrate (PD-200; manufactured by Asahi Glass Co., Ltd.) by a screen printing method. Apply 3
A 50-mesh polyester screen printing plate was used to prepare a coating film having a thickness of 6 μm. Next, the coating film 8
It was dried at 0 ° C. for 40 minutes.

Circuit pattern (stripe pattern, pitch 14
Approximately 30 with an ultra-high pressure mercury lamp with an output of 15 mW / cm ² through a negative type photomask having a line width of 0 μm and a line width of 50 μm).
UV exposure for 2 seconds was performed.

The development was carried out in a shower of a 0.2% aqueous solution of monoethanolamine at 30 ° C. to remove the unexposed portion. Then, the remaining developing solution was washed away with a pure water shower and dried at 80 ° C. for 20 minutes.

The firing was carried out by raising the temperature at a rate of 250 ° C./hour and maintaining the maximum temperature of 590 ° C. for 15 minutes.

Thus, a good electrode having a pitch of 140 μm and a line width of 50 μm without pinholes or disconnection was obtained. The thickness was 3 μm, and the cross section of the conductor was rectangular. The specific resistance value was 3 μΩ · cm.

After the dielectric paste was applied to the thus-formed glass substrate with electrodes by screen printing,
Firing was performed at 550 ° C. to form a dielectric layer having a thickness of 10 μm.

A photosensitive partition wall forming paste was prepared by the following procedure. The materials used are as follows. (Glass powder) Composition: Li2O 7%, SiO2 22%, B2O3 32% BaO 5%, Al2O3 22%, ZnO 2% MgO 6% CaO 4% Thermophysical properties: glass transition point 491 ° C, softening point 528 ° C, thermal expansion. Coefficient 74 × 10 −7 / K (Polymer) 40% Methacrylic acid (MAA), 30%
Of the copolymer of methyl methacrylate (MMA) and 30% of styrene of 0.
40% γ-butyrolactone solution (monomer) X2-N-CH (CH3) -CH2- (O-CH2) of a photosensitive polymer having a weight average molecular weight of 43000 and an oxidation of 95, which was subjected to an addition reaction with 4 equivalents of glycidyl methacrylate (GMA). -CH (CH3)) nN-X2X: -CH2CH (OH) -CH2O-CO-C (CH3) = CH2n = 2 to 10 (photopolymerization initiator) IC-369: "Irgacure" -369 (Ciba-
Geigy product) 2-benzyl-2-dimethylamino-1
-(4-morpholinophenyl) butanone-1 (Plasticizer) DBP; Dibutyl phthalate (organic dye) Sudan IV; Azo organic dye, chemical formula C24H20N4
O, molecular weight 380.45 (solvent) γ-butyrolactone (dispersing agent) "Nobu Cosperse" 092 (manufactured by San Nopco) (stabilizing agent) 1,2,3-benzotriazole First, 0.08 part by weight of organic dye, dispersing agent 0.5 parts by weight of γ
-Adding to 8 parts by weight of butyrolactone and stirring at 50 ° C, a uniform solution was obtained. To this solution, 38 parts by weight of polymer, 15 parts by weight of monomer, 3 parts by weight of photoinitiated polymerization agent, 2 parts by weight of plasticizer, and 3 parts by weight of stabilizer were added and mixed and homogeneously dissolved. Then, this solution was filtered using a 400-mesh filter to prepare an organic vehicle. 70 parts by weight of partition wall glass powder was added to the organic vehicle and mixed and dispersed by three rollers to prepare a photosensitive paste for partition wall formation. The viscosity of the photosensitive paste was 30,000 cps.

The above-mentioned photosensitive partition wall forming paste was applied onto the dielectric layer, and after pattern formation by the photolithography method, baking was carried out at 570 ° C. for 15 minutes to obtain a pitch of 140.
Stripe-shaped partition walls having a line width of 20 μm, a line width of 20 μm, and a height of 100 μm were formed.

A phosphor paste that emits red, blue, and green is applied using a screen printing method, and then baked (500
Then, a phosphor layer was formed on the side surface of the partition wall and on the bottom of the cell formed by the partition wall and the dielectric layer to obtain a back plate.

Next, a front plate was manufactured by the following steps. First, on the same glass substrate used for the back plate,
After the ITO film is formed by the sputtering method, a resist is applied, and a thickness of 0.1 μm is obtained by exposure / development processing and etching processing.
A transparent electrode having a line width of 200 μm was formed. Further, the thickness after firing is 10 μm and the pitch is 140 μm by a photolithography method using a photosensitive silver paste made of black silver powder.
A bus electrode having a line width of 60 μm and a line width of 60 μm was formed.

Further, 20 μm of a transparent dielectric paste was applied on the substrate on which the electrodes were formed, and the paste was held at 430 ° C. for 20 minutes and baked to form a dielectric layer. Then the transparent electrode,
An electron beam vapor deposition machine was used to uniformly cover the black electrode and the dielectric layer to form a 0.5 μm thick MgO film to complete the front plate.

After the front plate and the back plate thus obtained were bonded together and sealed, the chamber was evacuated, a discharge gas of Xe5% -Ne95% was sealed therein, and a drive circuit was joined to form a plasma display panel. . When a display was performed by applying a voltage to this panel, there was no display defect due to defects such as breakage of electrodes and pinholes, and a good display state was shown.

Comparative Example 1 As conductive powder, silver particles having a specific surface area of 0.5 m ² / g, a tap density of 5 g / cm ³ and an average particle size of 3 μm were used, and printing thicknesses were set to 6, 8, and 10 μm. A circuit pattern was formed in the same manner as in Example 1 except for the above. The thickness after firing is 3, 4, and 5 μm, respectively. The circuit pattern was formed by photolithography, but the thickness after firing was 4 μm.
Pinholes were observed in the following thin film circuit patterns.
The specific resistance value of the circuit pattern having a thickness of 4 μm after firing is 5
It was μΩ · cm.

It has been found that it is difficult to form a high-performance thin film circuit pattern having a thickness of 4 μm or less when a conductive powder having an average particle diameter of 3 μm is used.

Comparative Example 2 As the conductive powder, a granular silver powder having an average particle diameter of 1.5 μm and a tap density of 2.5 g / cm ³ was used, and an attempt was made to prepare a paste in the same manner as in Example 1. With the same composition as in Example 1, since the volume of the conductive powder was increased by the difference in tap density, the amount of organic components was not sufficient and a paste was not formed.

Therefore, the components other than the conductive powder were increased 1.6 times the composition of Example 1 to prepare a paste,
In addition, the printing thickness is set to two types of 6 and 10 μm, and the first embodiment is used.
A circuit pattern was formed in the same manner as in. The thickness after firing was about 3, 5 μm, respectively. Although the circuit pattern could be formed by the photolithography method, many pinholes were observed, and the thickness after firing was 0 to 5 and 0 to 8 μm, respectively.
It was a circuit pattern lacking in uniformity and surface flatness. It has been found that it is difficult to form a high performance thin film circuit pattern having a thickness of 4 μm or less when the conductive powder having a tap density of 2.5 g / cm ³ is used. Explanation of abbreviations X-4007: Weight average molecular weight of 43,000 obtained by addition-polymerizing 0.4 equivalent of glycidyl methacrylate to a carboxyl group of a copolymer composed of 40% methacrylic acid, 30% methyl methacrylate and 30% styrene. A polymer with an acid number of 95. DETX-S: 2,4-diethylthioxanthone

[0084]

[Effects of the Invention] The conductive paste for plasma display of the present invention.
The east has an average particle size of 0.5 to 2 μm, a tap density of ³ to 7 g / cm ³ , and a specific surface area of 0.4.
Since it is ~ 1.5 m ² / g , the dispersibility is high, and the plasma display containing the conductive powder and the organic component as essential components.
(A) By using the conductive paste for circuit pattern formation, it is possible to achieve a thin film thickness of 4 μm or less, and to form a circuit pattern with low resistance without pinholes or disconnections, which is sufficiently compatible with larger plasma displays. Is. Further, by reducing the film thickness, it is possible to reduce the cost of the circuit pattern portion.

In particular, when a circuit pattern is formed by the photolithography method by incorporating a photoreactive compound as an organic component into the conductive paste to form a photosensitive conductive paste, a mask pattern for exposure is used. The same fine pattern can be formed.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01J 9/227 H01J 9/227 E (56) Reference JP-A-9-142878 (JP, A) JP-A-10-75039 ( JP, A) JP-A-8-246001 (JP, A) JP-A-10-88206 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42 H01B 1/00-1/24

Claims (8)

(57) [Claims] 1. An average particle diameter of 0.5 to 2 μm, a tap density of ³ to 7 g / cm ³ , and a specific surface area of 0.1 .
A conductive paste for a plasma display , comprising a conductive powder of 4 to 1.5 m ² / g and an organic component as essential components. 2. The conductive powder contains 50% by weight of at least one selected from the group consisting of Ag, Au, Pd, Ni and Pt.
The plasma according to claim 1 , wherein the plasma is contained.
Conductive paste for displays . 3. Purazumade of claim 1 or 2, wherein the conductive powder is characterized in that it contains 70 wt% or more of Ag
Conductive paste for displays . As wherein organic components flop according to any one of claims 1 to 3, characterized in that it contains a photoreactive compound
Conductive paste for plasma display . 5. The conductive paste for plasma display according to claim 4, wherein the photoreactive compound is an acrylic acid ester compound or a methacrylic acid ester compound. 6. The conductive paste for plasma display according to claim 1 , which is for forming electrodes of a substrate for plasma display . 7. Purazumade according to any one of claims 1 to 6
A substrate for a plasma display, characterized by using a conductive paste for a display. 8. A base for a plasma display according to claim 7.
A plasma display characterized by using a plate .