JPH11135904A - Thick film electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the curling of an electrode at its edges. SOLUTION: An electrode is formed of thick film conductor material which at least contains conductive powder and glass frit, where in the electrode has a two-layered structure composed of an upper layer 13 whose main component is conductor powder and a lower layer 12 whose main component is glass frit. The edge of the electrode is less curled due to the tension of glass frit contained in the lower layer 12. As the upper layer 13 is small in glass frit content, the electrode is improved in wettability to electrode repairing solder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a thick-film electrode arranged in a pattern on various display substrates such as a circuit board, a multilayer wiring substrate and an LCD, and more particularly to a plasma display panel (hereinafter referred to as a PDP). And a thick-film electrode suitable for the above-mentioned electrode.

[0002]

2. Description of the Related Art In general, a PDP has a structure in which a pair of electrodes arranged regularly on two opposite glass substrates are provided, and a gas mainly composed of Ne, Xe, or the like is sealed between the electrodes. Then, a voltage is applied between these electrodes,
By generating a discharge in a minute cell around the electrode, each cell emits light to perform display. In order to display information, regularly arranged cells are selectively caused to emit light. There are two types of PDPs, a direct current type (DC type) in which the electrodes are exposed to the discharge space, and an alternating current type (AC type) in which the electrodes are covered with an insulating layer. And a refresh driving method and a memory driving method.

FIG. 1 shows a configuration example of an AC type PDP. This figure shows the front plate and the back plate separated from each other. As shown in the figure, two glass substrates 1 and 2 are arranged in parallel and opposed to each other, and both become the back plate. The barriers 3 provided on the glass substrate 2 in parallel to each other are held at a constant interval. On the back side of the glass substrate 1 serving as a front plate, composite electrodes composed of a sustain electrode 4 which is a transparent electrode and a bus electrode 5 which is a metal electrode are formed in parallel with each other, and a dielectric layer 6 is covered thereover. The protective layer 7 (MgO layer) is further formed thereon. On the front side of the glass substrate 2 serving as a back plate, address electrodes 8 are formed parallel to each other and located between the barriers 3 so as to be orthogonal to the composite electrodes, and a dielectric layer 9 is formed thereon. The phosphor 10 is provided so as to cover the wall surface of the barrier 3 and the cell bottom surface. The AC type PDP is of a surface discharge type, and has a structure in which an AC voltage is applied between composite electrodes on a front panel to discharge by an electric field leaking into a space. In this case, since the alternating current is applied, the direction of the electric field changes according to the frequency. Then, the phosphor 10 emits light by the ultraviolet light generated by the discharge, and the light transmitted through the front plate is visually recognized by the observer.

In the back plate of the PDP as described above, an address electrode 8 is formed on a glass substrate 2, a dielectric layer 9 is formed so as to cover the electrode 8 if necessary, and then a barrier 3 is formed. It is manufactured by providing a phosphor 10 between the barriers 3. As a method of forming the address electrode 8, a method of forming an electrode material film on the glass substrate 2 by a vacuum evaporation method, a sputtering method, a plating method, a thick film method, and the like, and patterning the film by a photolithography method, A method of patterning by screen printing using a paste is known. The dielectric layer 9 is formed by screen printing, film lamination, or the like. The barrier 3 is formed by overprinting by screen printing or a sand blast method, and the fluorescent surface of the phosphor 10 is formed of red (R), green (G), and blue (B) between the barriers 3 by screen printing or the like. It is formed by selectively filling a phosphor paste of three colors or by a photolithography method using a photosensitive phosphor paste.

[0005]

The address electrodes in the above-mentioned PDP have a thickness of about 5 to 15 μm. Conventionally, when such a thick film electrode is formed in a pattern, a screen printing method has been mainly used. The screen printing method has an advantage that a paste material that can be used is less restricted and a thick film pattern that is difficult to obtain by other printing methods is easily formed. However, in view of the enlargement and high definition of the formed pattern, the screen printing method has low dimensional accuracy, and when forming a plurality of types of thick film patterns, there is a problem in the consistency of each pattern, and further, a screen mesh is used. Therefore, there is a limit in the resolution. Therefore, a thick film pattern forming method by a photolithography method with high dimensional accuracy has been attracting attention. In this method, a surface coated with a paste containing a photosensitive material is covered with a pattern mask, and exposure is performed. And
Unexposed portions are removed by immersion in a developing solution to form an electrode pattern. However, there is a problem that the ends of the electrodes formed in a pattern are curled. This is because UV light transmission is hindered by inorganic powder in the thick film electrode material during exposure, curing of the photosensitive resin becomes insufficient as the film proceeds in the film thickness direction, and the uncured portion is scraped off during development, This is because the cross-sectional shape becomes an inverted trapezoidal shape. Then, since the shaved portion is warped up by firing, curling occurs. The curled electrode end has a problem that it is easily chipped by a slight external force, and depending on the method of use, current concentration and electric field concentration are likely to occur on the curled portion, which is a cause of impairing the reliability as an electrode .

The present invention has been made in view of the above problems, and an object of the present invention is to provide a thick-film electrode capable of reducing the curl at the end.

[0007]

In order to achieve the above object, a thick film electrode of the present invention is an electrode formed of a thick film conductor material containing at least a conductive powder and a glass frit, It has a two-layer structure comprising an upper layer mainly composed of conductive powder and a lower layer mainly composed of glass frit.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Since the thick-film conductor material used in the present invention is finally fired at a temperature higher than the softening point of the glass frit, the conductive powder contained in the conductor material is stable in the firing step. Need to be. Materials that can be used as the conductive powder include Au, Ag, Pt, Pd, Ni, and A.
l, Cr, Ag-Pd and the like can be listed.

[0009] The glass frit contained in the thick film conductor material must be selected according to the substrate to be used. That is, when the substrate is glass, the softening point is selected from the range of 300 to 600 ° C, and when the substrate is alumina, the softening point is selected from the range of 300 to 800 ° C.
If the softening point of the glass frit exceeds the above range, it is necessary to increase the baking temperature more than this range, and it is easy to induce thermal deformation exceeding the allowable range of the substrate in the baking step, which is not preferable. The glass frit has a softening point of 30.
A temperature of 0 ° C. or less is not preferable because the glass frit is fused before the thermoplastic resin or the like decomposes and volatilizes, causing defects such as voids in the layer.

The photosensitive resin used for imparting photosensitivity to the conductive material comprises an alkali developing type binder polymer, a reactive polymer and a photopolymerization initiator. If necessary, a sensitizer, a polymerization terminator, a chain transfer agent, an antifoaming agent, a leveling agent, a dispersant, a plasticizer, a stabilizer and the like are added.

As the alkali-developable binder polymer, acrylic acid, methacrylic acid, a dimer of acrylic acid,
Itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid, one or more of these acid anhydrides, methyl acrylate, methyl methacrylate, ethyl acrylate,
Ethyl methacrylate, n-propyl acrylate, n
-Propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-
Butyl acrylate, tert-butyl methacrylate, n-pentyl acrylate, n-pentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, 2- Octyl acrylate, 2-octyl methacrylate, n-decyl acrylate, n-decyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, styrene, α-methylstyrene, N-vinyl-2-pyrrolidone and the like Copolymers of at least one kind having an acid value of 50 to 200 mgKOH / g, and the like. It is not limited to al (2
Or more species may be mixed). Further, a polymer obtained by adding an ethylenically unsaturated compound having a glycidyl group or a hydroxyl group to the above copolymer, and having an acid value of 50 to 200 mgKOH /
g of polymer (two or more of them may be mixed). Further, one or more kinds of non-alkali developing type polymers may be blended with these polymers. Examples of the non-alkali developing type polymer include polyvinyl alcohol, polyvinyl butyral, acrylate copolymer, methacrylate copolymer, polyethylene, α
-Methylstyrene polymer, 1-vinyl-2-pyrrolidone polymer, and copolymers thereof.

As the reactive monomer, a compound containing at least one polymerizable carbon-carbon unsaturated bond can be used, and specific examples thereof include allyl acrylate, benzyl acrylate, butoxyethyl acrylate, and butoxyethylene glycol acrylate. , Cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, glycerol acrylate, glycidyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobonyl acrylate, isodexyl acrylate, isooctyl acrylate , Lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, pheno Phenoxyethyl acrylate, stearyl acrylate, ethylene glycol diacrylate,
1,4 butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,3-propanediol diacrylate, 1,4-cyclohexanediol diacrylate, 2,2-dimethylol Propane diacrylate, glycerol diacrylate, tripropylene glycol diacrylate, glycerol triacrylate, trimethylolpropane triacrylate, polyoxyethylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triethylene glycol diacrylate, Polyoxypropyltrimethylolpropane triacrylate, butylene glycol diacrylate, 1,2,4-buta Triol triacrylate,
2,2,4-trimethyl-1,3-pentanediol diacrylate, diallyl fumarate, 1,10-decanediol dimethyl acrylate, dipentaerythritol hexaacrylate, and the above acrylate changed to methacrylate, γ-methacrylate Roxypropyltrimethoxysilane, 1-vinyl-2-pyrrolidone, and the like. In the present invention, these monomers can be used as one kind or a mixture of two or more kinds or as other compounds.

As the photopolymerization initiator, benzophenone,
methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamine) benzophenone, α-amino acetophenone,
4,4-dichlorobenzophenone, 4-benzoyl-4
-Methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophonone, 2,2-
Dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, p-tert-butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyldimethylketal, Benzylmethoxyethyl acetal, benzoin methyl ether, benzoin butyl ether, anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibensuberone, methyleneanthrone, 4-azidobenzylacetophenone, 2,6 -Bis (p-azidobenzylidene)
Cyclohexane, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-
1,2-butadione-2- (o-methoxycarbonyl)
Oxime, 1-phenyl-propanedione-2- (o-
Ethoxycarbonyl) oxime, 1,3-diphenyl-
Propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, Michler's ketone, 2-methyl- [4- (methylthio) phenyl] -2
-Morpholino-1-propane, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, naphthalenesulfonyl chloride, quinoline sulfonyl chloride, n-phenylthioacridone, 4,4-azo Bisisobutyronitrile, diphenyl disulfide, benzothiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide,
Examples include a combination of a photoreducing dye such as tribromophenyl sulfone, benzoin peroxide, eosin, and methylene blue with a reducing agent such as ascorbic acid and triethanolamine. In the present invention, these photopolymerization initiators are
Species or two or more can be used.

Inorganic component (conductive powder, glass frit, etc.) and photosensitive resin component (negative type) in thick film conductor material
Is 5 to 100 parts by weight, preferably 5 to 40 parts by weight of the photosensitive resin component based on 100 parts by weight of the inorganic component. If the amount is less than this, patterning cannot be performed. On the other hand, if the amount is too large, the film does not become dense after firing and has no characteristics.

Examples of the organic solvent include anones such as methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, xylene and cyclohexane, methylene chloride, 3-methoxybutyl acetate,
Examples include ethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ether acetates, and terpenes such as α- or β-terpineol (two or more types may be mixed). ).

[0016]

【Example】

(Example 1) In this example, soda lime glass was used as a glass substrate. Then, a conductive material having the following composition A is applied twice on the entire surface of the substrate by a screen printing method, irradiated with ultraviolet rays through a predetermined mask, and developed with a 1% aqueous solution of sodium carbonate. Baking was performed at a temperature 20 to 150 ° C. higher than the softening point of the frit to form a thick film electrode having a dry film thickness of 25 μm. If the firing temperature is higher than the softening point of the glass frit by 20 ° C. or less, a two-layer structure is not formed. If the firing temperature is higher than 150 ° C., the substrate is deformed. It is necessary to bake inside.

<Composition A> Conductive powder: 65 parts by weight Ag (average particle diameter: 1 μm, spherical) Glass frit: Glass frit containing Bi ₂ O ₃ , B ₂ O ₃ , SiO ₂ as a main component (softening point) 500 ° C.) 5 parts by weight Binder polymer: 9 parts by weight of n-butyl methacrylate / 2-hydroxypropyl methacrylate / methacrylic acid copolymer (6/2/2 (molar ratio)) Monomer: 8 parts by weight of pentaerythritol tri / tetraacrylate Part Photopolymerization initiator: Irgacure-369 (manufactured by Ciba Specialty Chemicals) 1 part by weight Organic solvent: 3-methoxybutyl acetate 20 parts by weight

The thick film electrode manufactured as described above has a two-layer structure as shown in FIG. That is, the electrode on the glass substrate 11 is a lower layer 1 mainly composed of glass frit.
2 and an upper layer 13 mainly composed of conductive powder. In such a thick film electrode, the curl at the end of the electrode was reduced by the tension of the glass frit included in the lower layer 12, and the electrode was not easily chipped by an external force. Further, when the adhesion of the electrode repair solder was examined, the glass frit content of the upper layer 13 was lower than that of a normal one-layer structure, so that the solder coatability was improved.

Embodiment 2 In this embodiment, soda lime glass was used as a glass substrate. And first, FIG.
As shown in (a), a paste mainly composed of glass frit having the following composition B is pattern-printed on the substrate 11 by a screen printing method, and then baked at 600 ° C.
1 was formed. Subsequently, as shown in FIG. 3B, a conductive material having the same composition A as that used in Example 1 was printed on the entire surface of the substrate 11 on which the underlayer 21 was patterned by a screen printing method. After forming the layer 22, FIG.
As shown in (c), ultraviolet light was irradiated through a predetermined mask M. In this embodiment, the line width of the conductor layer 22 is
1, but may be smaller than the underlayer 21. Thereafter, as shown in FIG. 3 (d), the film is developed with a 1% aqueous solution of sodium carbonate, and baked at 600 ° C.
A thick film electrode 23 as shown in FIG.

<Composition B> Glass frit: lead borosilicate glass (softening point: 500 ° C.) 70 parts by weight Aggregate: Al ₂ O ₃ 15 parts by weight Thermoplastic resin: ethyl cellulose 3 parts by weight Organic solvent: butyl carbitol acetate 12 parts by weight Department

The thick film electrode 23 manufactured as described above is also shown in FIG.
Has a two-layer structure as shown in FIG. That is, the underlying layer becomes the lower layer 24 and the conductor layer becomes the upper layer 25. In the thick-film electrode 23 having such a two-layer structure, the curl at the electrode end is reduced by the tension of the glass frit included in the lower layer 24, and the electrode is hardly chipped by an external force. Also,
When the adhesion of the solder for electrode repair was examined, the upper layer 25
Has a lower glass frit content than a normal one-layer structure, so that the solder coatability has been improved.

Embodiment 3 In this embodiment, soda lime glass was used as a glass substrate. And first, FIG.
As shown in (a), a conductive material having the same composition A as that used in Example 1 was applied on the substrate 11 by a die coating method and dried to form a conductive layer 31. Subsequently, FIG.
As shown in (b), ultraviolet light was irradiated through a predetermined mask M. Thereafter, as shown in FIG. 4C, the film was developed with a 1% aqueous solution of sodium carbonate, and then fired at 600 ° C. to form a thick film electrode 32 as shown in FIG. 4D. The firing temperature is 20 to 150 ° C. from the softening point of the glass frit.
Use a high temperature. That is, if the temperature is higher than the softening point of the glass frit by 20 ° C. or less, a two-layer structure is not formed, and
If the temperature is higher than 50 ° C., the substrate is deformed. Therefore, it is necessary to perform firing in a temperature range higher by 20 to 150 ° C. than the softening point of the glass frit.

The thick film electrode 32 manufactured as described above is also shown in FIG.
Has a two-layer structure as shown in FIG. That is, the thick film electrode 32 on the glass substrate 11 was divided into a lower layer 33 mainly composed of glass frit and an upper layer 34 mainly composed of conductive powder. In such a thick film electrode 32, the curl at the end of the electrode was reduced by the tension of the glass frit included in the lower layer 33, and the electrode was not easily chipped by an external force. Further, when the adhesion of the electrode repair solder was examined, the glass frit content of the upper layer 34 was lower than that of a normal single-layer structure, so that the solder coatability was improved.

Embodiment 4 In this embodiment, soda lime glass was used as a glass substrate. And first, FIG.
As shown in (a), a paste mainly composed of a glass paste having the same composition B as that used in Example 2 is applied on the entire surface of the substrate 11 by a die coating method, and then baked at 600 ° C. to form an underlayer. 41 was formed. Subsequently, as shown in FIG. 5B, a conductive material having the same composition A as used in Example 1 was printed on the entire surface of the substrate 11 on which the underlayer 41 was patterned by a screen printing method. After the formation of the layer 42, as shown in FIG. 5C, ultraviolet rays were irradiated through a predetermined mask M. After that, as shown in FIG.
To form a thick film electrode 43 as shown in FIG.

The thick film electrode 43 manufactured as described above is also shown in FIG.
Has a two-layer structure as shown in FIG. That is, the thick film electrode 43 on the glass substrate 11 was divided into a lower layer 44 mainly composed of glass frit and an upper layer 45 mainly composed of conductive powder. In such a thick film electrode 43, the curl of the electrode end was reduced by the tension of the glass frit included in the lower layer 44, and the electrode was hardly chipped by an external force. Further, when the adhesiveness of the solder for electrode repair was examined, the glass frit content of the upper layer 45 was lower than that of a normal single-layer structure, so that the solder coatability was improved.

(Embodiment 5) In this embodiment, the glass substrate 1
A paste having the same two-layer structure was formed in the same manner as in Example 4 except that the paste of the composition B was applied over the entire surface by a die coating method, and was then simply dried without baking to form the underlayer 41. Produced. That is, the base layer 41 is fired simultaneously with the firing of the patterned conductor layer 42. The method of this embodiment is different from that of the fourth embodiment in that
The number of firing steps is reduced by one, which is preferable in terms of energy saving.

In each of the above embodiments, a photosensitive electrode material was used. However, it was confirmed that solder adhesion was improved even with a normal printing type electrode material. Therefore, the present invention is not limited to the electrode material having photosensitivity, but can be applied to ordinary printing pastes.

[0028]

As described above, according to the present invention, the curl at the edge of the electrode is reduced by forming a two-layer structure of an upper layer mainly composed of conductive powder and a lower layer mainly composed of glass frit. Since the electrodes are less likely to be chipped, the yield can be improved. In addition, since the glass frit content of the upper layer is small, the wettability of the electrode repair solder is improved.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing an example of a configuration of an AC type plasma display panel in a state where a front plate and a back plate are separated from each other.

FIG. 2 is a sectional view showing an example of a thick film electrode according to the present invention.

FIG. 3 is a process chart showing an example of a procedure for manufacturing a thick film electrode according to the present invention.

FIG. 4 is a process chart showing another example of a procedure for manufacturing a thick film electrode according to the present invention.

FIG. 5 is a process chart showing still another example of a procedure for manufacturing a thick film electrode according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front plate 2 Back plate 3 Barrier 4 Sustain electrode 5 Bus electrode 6 Dielectric layer 7 Protective layer 8 Address electrode 9 Dielectric layer 10 Phosphor 11 Glass substrate 12 Lower layer 13 Upper layer 21 Underlayer 22 Conductor layer 23 Thick film electrode 24 Lower layer 25 Upper layer 31 Conductor layer 32 Thick film electrode 33 Lower layer 34 Upper layer 41 Underlayer 42 Conductor layer 43 Thick film electrode 44 Lower layer 45 Upper layer

Claims (2)

[Claims] 1. An electrode formed of a thick-film conductive material containing at least a conductive powder and a glass frit, comprising: an upper layer mainly composed of a conductive powder and a lower layer mainly composed of a glass frit. A thick-film electrode having a two-layer structure. 2. A thick-film electrode formed on a glass substrate of a plasma display panel, comprising a thick-film conductor material containing at least a conductive powder and a glass frit, and comprising a conductive powder as a main component. A thick-film electrode for a plasma display panel, which has a two-layer structure including an upper layer to be formed and a lower layer mainly composed of glass frit.