KR101738490B1 - Photosensitive paste with low temperature hardening and method for forming electrode using the same - Google Patents
Photosensitive paste with low temperature hardening and method for forming electrode using the same Download PDFInfo
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- KR101738490B1 KR101738490B1 KR1020150096294A KR20150096294A KR101738490B1 KR 101738490 B1 KR101738490 B1 KR 101738490B1 KR 1020150096294 A KR1020150096294 A KR 1020150096294A KR 20150096294 A KR20150096294 A KR 20150096294A KR 101738490 B1 KR101738490 B1 KR 101738490B1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/0047—Photosensitive materials characterised by additives for obtaining a metallic or ceramic pattern, e.g. by firing
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
Abstract
The present invention relates to a low-temperature curing photosensitive electrode paste and a method of manufacturing an electrode using the low-temperature curing photosensitive electrode paste. The conductive paste containing conductive particles having a specific shape in a low-temperature curable resin and a photosensitive organic compound is mixed at a predetermined composition ratio, Forming a coating film on the substrate to form a coating film, irradiating the coating film with light, and heat-treating the coating film at a low temperature to form an electrode and a pattern.
Description
The present invention relates to an electrode paste and a method of manufacturing an electrode using the electrode paste. More particularly, the present invention relates to an electrode paste including conductive particles having a specific shape in a low temperature curable resin and a photosensitive organic compound, And to a method of manufacturing an electrode in which the volume resistivity is increased.
Printed Electronics technology is a technology that forms a fine pattern or a conductive thin film by printing process of an electrode paste, and covers electronic circuits and electronic products manufactured through such a technique. Various printing methods such as a screen printing method, a gravure printing method, an offset printing method, a gravure offset printing method and an inkjet printing method are used as a printing process, and a screen printing method having relatively low process cost and easy mass production is most widely used . In order to carry out the printing process, an electrode paste should be prepared by mixing conductive particles, for example, a metal or a conductive carbon material, with a binder having fluidity. The electrode paste can be classified into a high temperature sintering type paste and a low temperature curing type paste. First, a high temperature sintering type paste is described. The high-temperature sinterable paste is generally prepared by mixing metal-based conductive particles and an inorganic binder (glass frit) into a polymer binder. When this is printed on a substrate and subjected to a heat treatment at a high temperature of 500 DEG C or higher, all the organic components are thermally decomposed, and finally a coating film composed of a metal and an inorganic binder is formed. The inorganic binder lowers the melting point of the metal particles and compresses between the metal particles during the heat treatment at a high temperature to increase the adhesion and adhesion of the conductive powder. If a high-temperature sintering paste is used to form an electrode, a high-performance electrode can be realized because only the metal and the inorganic binder having excellent conductivity are present in the finally formed coating film. However, It can be used only.
On the other hand, the low-temperature curable paste is produced by mixing conductive particles made of a metal or a carbon material with a polymer binder. The polymeric binder has a property of curing at a temperature of 400 ° C or less and is bonded with the conductive particles in a three-dimensional network structure under specific curing conditions so that the contact points between the conductive particles can be formed. Temperature sintering type paste, it has an advantage of being excellent in adhesion with a substrate and having a wide selection range of substrates because it realizes coating properties at a relatively low temperature of from room temperature to 400 ° C. However, There is a limitation in increasing the contact point due to difficulty in fusing between conductive particles as a result of curing at a low temperature, and there is a disadvantage that a short circuit is likely to occur because the coating film finally contains organic matter. As described above, since the curing temperature and the conductivity are complementary to each other, in order to solve this problem, it is necessary to reduce the size of the conductive particles and further increase the contact area so that the contact points between the conductive particles can be maximized even at a low temperature And the melting point of the conductive particles is lowered so that the fusion between the conductive particles can be more efficiently performed even at a low temperature.
Korean Patent Laid-Open No. 10-2008-0058787 (entitled "Photosensitive Electrode Paste and Its Production Method", hereinafter referred to as "Prior Art 1") includes a binder polymer, a photoinitiator, a monomer, a dispersant and an anti- A photosensitive organic compound composition to which at least one of a UV absorber and a plasticizer is added, and an electrode powder comprising at least one of silver, palladium, copper, and silver / palladium alloy. At this time, the electrode powder contains 75 to 90 wt% of the total photosensitive electrode paste.
The prior art 1 discloses a technique relating to a photosensitive electrode paste composition composed of a predetermined electrode powder containing a photosensitive organic compound and silver. However, in order to realize properties suitable for electrodes, an electrode powder having a high unit cost is mixed with the total paste weight And 75 to 90 wt%, which is a high manufacturing cost.
In addition, since the content of the electrode powder is high, the content of the organic material exhibiting a relatively low photosensitivity is small, and it is difficult to realize a fine pattern.
In addition, there is a third problem that the content of the organic substance that determines the adhesion with the base material is small and the coating film formed after the heat treatment shrinks, thereby lowering the conductivity.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.
In order to solve the above-mentioned problems, the present invention provides a conductive powder comprising 50 to 70 wt% of a conductive powder having a specific surface area of 1.3 m 2 / g or larger, 5 to 25 wt% of a photosensitive organic compound, and 5 to 25 wt% of a thermosetting resin. Further, the photosensitive organic compound of the present invention is characterized by being an acrylic resin, and may further comprise at least one resin selected from the group consisting of a polyester resin and a cellulose resin. In addition, the conductive paste may further include a polyfunctional acrylate-based monomer as a photo-curing agent, and may further include a photoinitiator and a heat curing agent.
The thermosetting resin of the present invention may contain at least one resin selected from the group consisting of an acrylic resin, an epoxy resin, a urethane resin and a phenol resin. In addition, the electrode paste of the present invention may further include at least one additive selected from the group consisting of a UV absorbent, a rheology modifier, a dispersant, a stabilizer, a defoaming agent, and a wetting agent.
The present invention also relates to a method of manufacturing a thin film capacitor, comprising the steps of: i) preparing a substrate; ii) applying a low temperature curable electrode paste according to the present invention to the substrate; iii) drying the applied electrode paste to form a coating film; iv) Exposing the coating film to light, and v) heat-treating the coated film.
In addition, a touch panel manufactured using the low-temperature curing type electrode paste according to the present invention is provided.
The low-temperature curing type electrode paste according to the present invention can be produced by using the conductive particles having a predetermined specific surface area and increasing the specific surface area and using the conductive powder having a small total content (70 wt% or less based on the total paste weight) It has a first effect. Further, a second effect that a photosensitive pattern with a narrow line width (20 μm or less) can be realized by increasing the content of the binder resin relatively, a third effect that can increase the adhesion to the substrate, and a third effect 4 effect.
With respect to the first effect, particles having a predetermined particle size range in order to increase the contact area between the conductive particles are used. When protrusions are formed on the particle surfaces and compared with particles having the same size, conductive particles having a large specific surface area (Volume resistance ≤ 100 mu OMEGA cm) suitable for electrodes including a conductive powder having a smaller content than that of the prior art can be realized.
With respect to the second effect and the third effect, by decreasing the content of the conductive powder in the total weight of the entire paste, the content of the photosensitive organic compound and the thermosetting resin which provide the adhesive property is increased, Electrode can be formed. In addition, as the content of the photosensitive organic compound that provides the photosensitive property increases, it is possible to realize a photosensitive pattern having a superior sensitivity characteristic and a narrow line width as compared with the prior art.
Further, in relation to the fourth effect, since a thermosetting resin capable of forming a three-dimensional network structure by curing at a low temperature is used, the substrate to which the electrode paste is applied is devoid of an inorganic material having high temperature, It is possible to expand into a polymer material, thereby making it possible to realize a flexible electrode.
Further, the present invention has the external effect that the content of the conductive powder having a relatively high unit price is lowered and the low-temperature curable resin is used in the process so that the manufacturing cost can be reduced and the process efficiency can be increased.
It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.
FIG. 1 is a SEM photograph of a silver particle having protrusions formed on a surface of the conductive powder according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing an electrode according to an embodiment of the present invention.
3 is a schematic view of an electrode according to an embodiment of the present invention.
4 is an SEM photograph of silver particles having no protrusions on the surface.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.
Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.
The present invention relates to a low-temperature curing photosensitive electrode paste, which comprises 50 to 70 wt% of conductive powder, 5 to 25 wt% of a photosensitive organic compound, and 5 to 25 wt% of a thermosetting resin as main components and contains a photocuring agent, a photoinitiator, And further comprising In addition, the electrode paste of the present invention may further include at least one selected from the group consisting of a heat curing agent, a UV absorber, a rheology modifier, a dispersant, a stabilizer, a defoaming agent, and a wetting agent.
Hereinafter, each composition will be described in detail.
The conductive powder of the present invention may be a mixture of one metal selected from the group consisting of Ag, Au, Cu, Pt, Sn, Ni, Al, W, Mo, Sb, Cr, Pb and Ti, Or alloys thereof. Depending on the kind and content of the conductive powder, the properties of the coating film may vary. Conductive materials such as metals may be used as conductive powders, but some metals are easily oxidized to form oxides, resulting in an excessively high resistance, . Preferably, the conductive powder may be at least one of Ag, Au, and Pt, which is not easily oxidized and has a low specific resistance. Particularly, Ag has the lowest resistivity among the metals described above and is inexpensive in terms of performance and economy It can be a preferable metal. In addition, the conductive powder of the present invention may contain a metal oxide semiconductor such as zirconium oxide, nickel oxide, aluminum oxide, tin oxide, ITO, and antimony oxide, which exhibits high conductivity in addition to the above-mentioned metal, Carbon-based materials including carbon black, fiber, and carbon black may also be used, or they may be mixed with the above-described metals.
On the other hand, when the conductive powder is mixed with an organic / inorganic binder and made into a paste, resistance higher than the inherent resistance of the metal is obtained. This is due to the interface resistance between the particles and increases the contact area between the conductive particles, The electrode paste must be prepared in such a manner as to minimize the interfacial resistance by adjusting the shape and size of the conductive particles.
Hereinafter, the relationship between the shape and size of the conductive particles and the film properties will be described in more detail. First, the relationship between the size and the film property will be described. When the particles constituting the conductive powder are controlled to have micro / nano size and the particle size distribution is uniformly produced, the contact area between the conductive particles can be increased to reduce the interfacial resistance. Further, it is preferable to control the size of the metal in the bulk state with micro / nano particles because the melting point is very high (Ag: 961.78 캜, Pt: 1768.3 캜, Au: 1064.18 캜) . However, when the size of the particle size is too small, coagulation between the particles is easy, so that the uniformity of the paste is lowered and the specific gravity of the particles is so small that the compactness of the pattern may be deteriorated in implementing the pattern using the paste . In addition, particles having a small particle size can increase the contact point to lower the interface resistance, but the resistance may increase due to the increase in the content of the organic material in order to prevent aggregation thereof. On the other hand, when the particle size is too large, it is difficult to realize a narrow line width pattern when the electrode pattern is implemented in addition to the problem that the interfacial resistance increases, and the linearity of the pattern may be deteriorated. In the present invention, the particle size of the particles forming the conductive powder is limited to 0.1 to 10 μm, and more preferably, the conductive particles may be 0.5 to 2 μm.
Next, the relationship between the particle shape and the film property will be described. The particles constituting the conductive powder can increase the contact points between the conductive particles in the same manner as described above, and can further enhance the coating properties by controlling the shape to minimize the interfacial resistance. When spherical particles forming point contact are used as the conductive powder, sintering at a high temperature (500 캜 or higher) together with the inorganic binder can realize a resistance value usable for electrodes due to fusion between particles, but when sintering at a low temperature There is a limitation in achieving high conductivity due to limited fusion between the particles. In order to overcome such a problem, flake-type particles can be used for surface contact to increase the conductivity. However, flake-shaped particles have another problem in that it is difficult to produce fine particles with small particle diameters due to the nature of the shape, and it is difficult to realize fine patterns. For this reason, the present invention uses spherical particles having a predetermined average particle size range and having protrusions on the surface thereof as the conductive powder. The protrusions on the surface can increase the contact area between the particles and make it possible to manufacture a low temperature curing type electrode paste having excellent conductivity in a smaller amount than the conventional conductive powder content. Also, instead of reducing the content of the conductive powder, the content of the organic material is increased, so that it is easy to realize a fine pattern under low temperature curing conditions and the adhesion to a substrate can be increased. The conductive particles on which the protrusions of the present invention are formed are characterized by having a specific surface area of 1.3 m 2 / g or larger when compared with spherical particles of the same size. The reason for this limitation is that the effect of increasing the conductivity and adhesion due to the increase of the specific surface area of the particles is insufficient under the condition lower than the above value.
Next, the photosensitive organic compound of the present invention may be an acrylic resin, and may further include at least one resin selected from the group consisting of a polyester resin and a cellulose resin. In the present invention, the photosensitive organic compound provides adhesion to a substrate and forms a three-dimensional network structure together with the conductive particles by light (particularly UV), thereby enhancing the contact points between the conductive particles and realizing coating properties . The binder resin also serves to impart a predetermined viscosity to the paste. The photosensitive organic compound is one of the important elements in the electrode paste composition because the chemical resistance, the adhesiveness, the heat resistance, and the stability of the coating are determined depending on the kind and content thereof. In the present invention, the photosensitive organic compound is contained in an amount of 5 to 25 wt% based on the total weight of the electrode paste composition, and more preferably 5 to 15 wt% of the photosensitive organic compound. When the paste is contained in an amount lower than the lower limit described above, when the electrode and the electrode pattern are implemented using the paste, the printing efficiency is significantly lowered. When the paste is contained in an amount higher than the upper limit, The formation of contact points between particles is not easy and the interface resistance may increase. The present invention may further include a photo-curing agent and a photoinitiator to further enhance the photosensitivity of the photosensitive organic compound.
Hereinafter, each will be described in detail. In the present invention, the photosensitive organic compound contains an acrylic resin as a main component, and the acrylic resin is widely used as a binder resin because of its low cost and easy control of physical properties. Specific examples thereof include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, secondary-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, Acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, glycidyl acrylate, Methacryloxypropyl acrylate, isopropyl acrylate, ethyl acrylate, isopropyl acrylate, ethyl acrylate, isopropyl acrylate, ethyl acrylate, isopropyl acrylate, Acrylate, 2-hydroxyethyl acrylate, 2-hydro City may be a polymer or copolymer consisting of acrylate, aminoethyl acrylate monomer selected from at least one first group consisting of acrylate. Further, it may be a polymer or copolymer composed of at least one monomer selected from the group consisting of a methacrylate monomer in which a part or all of the acrylate contained in the acrylate monomer is substituted with methacrylate, and the acrylate An acrylic resin prepared by copolymerizing a monomer and a methacrylate monomer may be possible. Further, in the case of including the post-exposure development step in the production of the electrode, an acrylic resin having a hydroxyl group or a carboxyl group in the molecule may be used for the purpose of facilitating the development by mainly developing with an acid or an aqueous alkali solution. Specifically, when developing with an aqueous alkali solution, the photosensitive organic compound is preferably an acrylic resin having a carboxyl group, and specific examples thereof include acrylic acid, methacrylic acid, fumaric acid, maleic acid, vinyl acetic acid and an anhydride thereof. Or more of the above compounds may be polymers prepared by copolymerization reaction with the above-mentioned acrylate-based monomer or methacrylate-based monomer. In the present invention, a cellulose resin or a polyester resin may be mixed with the photosensitive organic compound in order to improve the rheology and leveling property in addition to the acrylic resin to impart uniform coating property to the substrate. Examples of the cellulose resin include methyl cellulose, ethyl cellulose, n-propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, 2-hydroxyethyl cellulose, hydroxybutyl methyl cellulose, cellulose nitrate, cellulose acetate, cellulose triacetate, Carboxymethylcellulose, carboxymethylcellulose, carboxyethylmethylcellulose, and the like. In the case of mixing a polyester resin, it may be preferable to use a copolymer of a polyester resin and an acrylic resin in view of the pattern realization by photosensitive, and specifically it may be a polyester acrylate oligomer resin .
Next, the electrode paste of the present invention may further include a photo-curing agent for promoting the reaction of forming the three-dimensional network structure by increasing the photosensitivity of the photosensitive organic compound and irradiating light. The photo-curing agent may be an acrylate-based monomer containing an ethylenic unsaturated bond in the molecule, more preferably a polyfunctional acrylate-based monomer. This is characterized by imparting plasticity to the acrylic resin. In addition, the acrylate monomer is mainly present in a liquid state and can act as a diluent, and it is possible to facilitate the adhesion strength and the viscosity of the paste to the substrate. Specific examples thereof include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexane Diol dimethacrylate, trimethylol trimethacrylate, trimethylol propane triceta acrylate, pentaerythritol trimethacrylate, ditrimethylol propane tetramethacrylate, and dipentaerythritol hexyl methacrylate. The photocuring agent may be contained in an amount of 1 to 10 wt% based on the amount of the photosensitive organic compound. However, when the amount of the photocuring agent is less than 1 wt%, the effect expected by adding the photocuring agent is insufficient. The content of the conductive powder is relatively decreased and the resistance of the electrode can be increased.
Further, the electrode paste of the present invention may further comprise a photoinitiator which initiates a reaction in which the photosensitive organic compound forms a three-dimensional network structure by exposure. When the light is irradiated, the photoinitiator forms a free radical and reacts with the reactive unsaturated group included in the molecular structure of the binder resin and the photo-curing agent to initiate a reaction to form a three-dimensional network structure. Examples of the substance that performs such a role include benzophenones and peroxides, which are not limited to the following materials, but include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, Methyl-4- (methylthio) benzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2- 2-methylphenyl) -1-butanone, bis (2,6-dimethoxybenzoyl) ) -2,4,4-trimethylpentylphosphine oxide, and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. In addition, it is preferable that the photoinitiator is included in the photosensitive organic compound in an amount of 1 to 10 wt%, but it is not limited thereto. However, if it is added in an amount of less than 1 wt%, the effect to be expected may be insufficient, and when 10 wt% or more is added, the resistance may increase because the content of the conductive powder is relatively decreased.
Next, the thermosetting resin of the present invention will be described in detail. The thermosetting resin of the present invention may comprise at least one resin selected from the group consisting of an acrylic resin, an epoxy resin, a urethane resin and a phenol resin. When the above-mentioned thermosetting resin is added, the adhesion to the substrate can be increased more than when the binder resin is used alone. In addition, the thermosetting resin serves to disperse the conductive powder and cures under a predetermined curing condition so that the coating film characteristics can be realized. In addition, the heat curing agent of the present invention is characterized by being cured at a temperature of 100 to 190 ° C, more preferably forming a three-dimensional network structure at a temperature of 140 ° C or less, The energy cost and the manufacturing time can be shortened. Considering the ease of controlling physical properties and economical aspects of the above-mentioned thermosetting resin, it is preferable to use an acrylic resin and an epoxy resin. However, it is preferable to use an epoxy resin having excellent chemical resistance and hardness and having a high curing speed May be more preferable. However, since the epoxy resin has a property of being hard and fragile, it may be preferable to use a urethane resin when stretchability is required. The thermosetting resin may be contained in an amount of 5 to 25 wt%, more preferably 5 to 15 wt% with respect to the total weight of the electrode paste. If the content is less than 5 wt%, the degree of curing is insufficient and the contact point between the conductive particles can not be formed. When the content exceeds 25 wt%, the organic material encloses the conductive particles and the contact points between the conductive particles are insufficient, . In addition, it may be preferable that the thermosetting resin is contained less than the photosensitive organic compound. The reason for this is that the probability of the thermosetting resin remaining in the coating film after the heat treatment is higher than that of the thermoplastic organic compound. Accordingly, the photosensitive organic compound and the thermosetting resin may be contained as the binder of the conductive particles, but it is preferable that the content of the thermosetting resin does not exceed the content of the photosensitive organic compound in order to realize the high conductivity coating film.
In addition, the electrode paste of the present invention may further include a thermosetting agent to increase the thermosetting efficiency. The thermosetting agent acts to bridge the thermosetting resin to form a three-dimensional network structure. Specific examples thereof include dicyandiamide, diethylamino propylamine, and the like. The thermosetting agent is not limited to the above-described material, and any of the curing agents capable of promoting the curing of the thermosetting resin within the temperature range defined in the electrode manufacturing process of the present invention may be used. In the present invention, the heat treatment temperature is limited to a range of 90 to 190 ° C. If curing occurs at a temperature lower than the lower limit, storage stability is deteriorated. If the electrode is manufactured at a temperature exceeding the upper limit, The manufacturing cost may increase and the selectivity of the substrate may be limited.
In addition, the conductive paste of the present invention may comprise at least one material selected from the group consisting of a UV absorber, a rheology modifier, a dispersing agent, a stabilizer and a defoaming agent. Each material will be described in detail below.
First, the UV absorber suppresses light scattering upon exposure and minimizes the phenomenon of curing to a portion that is not needed, thereby realizing a high-resolution pattern. Further, the dispersant and the stabilizer are added to prevent aggregation by weakening the surface energy of the conductive particles and to disperse evenly in the paste, and the surfactant can perform the above-described role. The rheology modifier is an additive that can increase the leveling of the paste. Rheology and leveling properties in printing are very important factors. When an electrode is manufactured using a paste having poor rheology characteristics, some defects such as orange peel, mesh mark, and pinhole are increased in the coating film, resulting in deterioration of conductivity. Therefore, it is desirable to include a rheology modifier in order to minimize defects when producing the electrode paste. The defoaming agent of the present invention is an additive for suppressing bubbles present in a paste. When an electrode is formed using a paste and a pattern is formed, holes are formed on the electrode surface when bubbles are present, irregularities occur on the electrode surface, And short-circuiting, it may be preferable to add a predetermined defoaming agent in terms of increasing the performance of the electrode. It is preferable that the above-mentioned additive is in the range of 0.1 to 10 wt% based on the total weight of the electrode paste. When the additive content is less than 0.1 wt%, the effect that can be realized by incorporating the additive is insufficient. When the additive content is more than 10 wt%, the organic material content in the electrode paste is increased and the film properties may be deteriorated.
In addition, the electrode paste of the present invention may contain a solvent for diluting the binder and dispersing the conductive powder in a more uniform manner, and the solvent may be selected from the group consisting of α- or β-terpineol, N-methylpyrrolidone (N butyl cellosolve, ethyleneglycol monobutyl ether acetate, ethyl carbitol, ethyl citalolacetate, butyl carbitol, ethyl carbitol acetate, But are not limited to, ethoxyethyl acetate, ethylcellosolve, ethyl cellosolve acetate, butyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether Propylene glycol monomethyl ether acetate, gamma-butyrolactone, methylethyl ketone, Dipropylene glycol methyl ether, and the like. However, it is not limited thereto, and any of them may be possible as long as it is non-reactive with the solute and can act as a diluent. However, it is preferable that rapid drying is possible but volatility is not too great. If the volatility is too high, the solvent may volatilize before the coating is formed using the paste, so that the viscosity of the paste may rise sharply, the solvent may volatilize during electrode formation using the electrode paste, Because. In addition, when the terminal of the solvent is substituted with an alkyl group or an acetate group, the permeability of the solvent is excessively increased, and there is a possibility of penetrating the substrate and parts of the silicon material, thereby deteriorating the deterioration of the substrate and the durability of the parts The permeability of the solvent should also be considered. The content of the solvent may be varied depending on the type and content of the composition and the desired viscosity, and may be generally 5 to 20 wt% based on the total weight of the paste.
Next, the viscosity of the paste will be described. Viscosity is an important factor in implementing electrodes using pastes. In the case of the electrode paste, the viscosity varies depending on the shear stress, and this plays a very important role in the step of printing the paste to be described later on the substrate and the pattern forming step. In the case of using a paste having a too low viscosity, it is difficult to apply the paste with a predetermined thickness because of high fluidity and spreadability of the paste, and it is difficult to realize a narrow line width because of the property of spreading the pattern. In addition, when a paste having an excessively high viscosity is used, the fluidity and spreadability of the paste are too low, which makes it difficult to apply the paste to the substrate. Accordingly, the paste is prepared by controlling the content of the composition so as to have a predetermined viscosity according to the method of applying the paste to the substrate and the line width of the pattern to be implemented, and at the same time, considering the characteristic of the fluid viscosity depending on the temperature and the shear stress, . Also, on the side of the conductive particles, the size and shape of the conductive particles must be taken into consideration since the sizes of the conductive particles are small and the surface area is large, the input between the particles may increase and the viscosity may increase.
Further, the present invention provides a method of manufacturing an electrode using a low-temperature curing photosensitive electrode paste. The electrode manufacturing method includes the steps of: i) preparing a substrate, ii) applying an electrode paste to the substrate, iii) drying the applied electrode paste to form a coating film, iv) exposing the dried coating film, v ) The step of forming an electrode by heat treatment of the exposed coating film is regarded as a main manufacturing step, and the volume resistance of the electrode manufactured through this step is not more than 100 μ? · Cm.
Hereinafter, each step will be described in detail. First, in the step of manufacturing a substrate, any of an organic material and an inorganic material substrate may be used. Unlike the conventional high temperature sintering type paste, since the paste of the present invention can realize excellent coating film characteristics under the condition of 100 to 190 캜, more preferably 100 to 150 캜 or less, no deformation is caused in the above-mentioned temperature range , And any substrate that is adhesive to the binder resin of the present invention. For example, the substrate may be a glass substrate that is conventionally used in general use, and may be a plastic substrate including PET, PEN, and polyimide substrates having flexibility. In addition, a surface-treated plastic substrate may be used for increasing the adhesiveness to the paste and for the purpose of coating. In the case of adopting a plastic substrate, it is advantageous in that it can be made lighter as well as flexible, and can be made thinner.
Next, step ii) of the present invention is a step of applying a paste to a substrate, and the paste can be applied through a screen printing method which is low in manufacturing cost and easy in mass production. In addition, techniques such as spin coating, blade coating, spray coating, slot die coating, and ink jet coating are available. Gravure printing, offset printing and gravure offset printing can be performed simultaneously with the application of a paste and the formation of a pattern It can also be used. The viscosity of the paste is preferably 50 to 200 Pa · s to obtain a general film thickness (10 to 20 μm) by applying the coating solution to the substrate by a screen printing method. When the blade coating method or the slot die coating method is used, And a small value of 2 to 20 Pa · s may be preferable. However, the present invention is not limited to the above-described conditions, and it is specified that the paste composition can be modified to any extent according to the composition and content of the paste, the application method and the specification of the apparatus used for application.
Next, the step iii) of the present invention is a step of volatilizing the solvent contained in the applied electrode paste to form a coating film. The drying process is generally carried out in a heating furnace and is carried out at a temperature of 90 DEG C or lower for 5 to 10 minutes ≪ / RTI >
Next, the step iv) of the present invention may further comprise a step of exposing the dried coating film, and a step of baking the photomask before the step iv). In addition, in the case of including the step of baking the photomask, the step of iv) includes a developing step of removing the unexposed area by using a developing solution, and further including such a step, the electrode formed in step v) And a predetermined pattern is formed. In addition, the patterned electrode can be applied to a display electrode, a touch panel or the like, and the electrode having no pattern can be used as an electrode of an energy storage device.
Next, the step (v) of the present invention is a step of heat treating the exposed coating film to increase the contact point between the conductive particles, and the heat treatment is performed at a temperature of 100 to 190 ° C.
FIG. 3 shows a schematic view of an electrode manufactured by the manufacturing method according to the present invention. The
In addition, the electrode manufactured by the above-described manufacturing method can exhibit excellent adhesion between the coating film and the substrate even though the content of the conductive particles is 70 wt% or less with respect to the total weight of the paste and is cured at a low temperature of 140 캜 or less, cm or less, and is capable of realizing a fine pattern of 20 μm or less. Hereinafter, examples and comparative examples will be described.
Hereinafter, the effects of the present invention will be described in detail with reference to specific examples of the present invention.
[Example 1]
(Acrylic resin containing unsaturated bonds, Mw: 33000) and 10 wt% of resin 3 (epoxy acrylate, Mw: 15000) as a photosensitive resin were mixed in a ratio of 65 wt% Dipropylene glycol methyl ether, and stirred to prepare a paste. This is printed on a glass substrate using a 305 mesh screen of polyester and heated and dried at a temperature of 80 DEG C for 10 minutes to form a coating film. Next, exposure was performed using a photomask capable of implementing a line width of 20 mu m, wherein the exposure level was 300 mJ / cm < 2 & gt ;. Next, the substrate is developed with Na 2 CO 3 aqueous solution at room temperature for 15 seconds to remove the non-cured region. Next, the substrate was heat-treated at 140 ° C for 6 minutes to prepare an electrode on the substrate.
At this time, the silver powder particles are spherical particles having protrusions formed on their surfaces. The shape of the silver particles was SEM photograph shown in Fig. 1, and the average particle size of the silver particles was 0.8 mu m.
Further, in order to use it for evaluating the adhesion force, an electrode in which no pattern was formed under the same conditions was prepared except that the step of exposure and development without using a photomask was omitted.
[Example 2]
An electrode was produced under the same conditions except that Resin 4 (urethane acrylate Mw: 20,000) was used as a thermosetting resin.
[Example 3]
A silver paste was prepared under the same conditions except that Resin 2 (acrylic resin, Mw: 20,000) was used as the photosensitive resin.
[Comparative Example 1]
An electrode was produced under the same conditions as in Example 1, except that spherical silver particles having no protrusions on the surface and having an average particle size of 0.3 mu m were used as the conductive powder. For the shape of the silver particles, see the SEM photograph shown in Fig. 4 (a).
Further, in order to use it for evaluating the adhesion force, an electrode in which no pattern was formed under the same conditions was prepared except that the step of exposure and development without using a photomask was omitted.
[Comparative Example 2]
An electrode was produced under the same conditions as in Example 1, except that spherical silver particles having an average particle size of 0.5 占 퐉 were used as the conductive powder. For the shape of silver particles, see the SEM photograph shown in Fig. 4 (b).
[Comparative Example 3]
An electrode was produced under the same conditions as in Example 1, except that spherical silver particles having an average particle size of 1.0 占 퐉 were used as the conductive powder. For the shape of silver particles, see the SEM photograph shown in Fig. 4 (c).
[Experimental Example 1]
In order to evaluate the conductivities of Examples 1 to 3 and Comparative Examples 1 to 3, the resistance of the electrodes was measured using a 4-point probe, and is shown in Table 1 as volume resistance.
In addition, in order to evaluate the adhesion of Examples 1 to 3 and Comparative Examples 1 to 3, 10 lines were horizontally and vertically crossed at intervals of 1 mm on electrodes having no pattern formed thereon to form crosscuts The adhesive strength was evaluated by the number of peeled crosscuts when the adhesive tape was peeled off, and the results are shown in Table 1. (Bottom: more than 20 pieces, middle: less than 10 pieces, upper: no pieces)
In order to confirm the printability of Examples 1 to 3 and Comparative Examples 1 to 3, a three-dimensional microscopic measurement was carried out to determine whether the intended line width (20 m) was implemented. (Implemented: O, not implemented: X)
Example 1
Example 2
Example 3
Comparative Example 1
Comparative Example 2
Comparative Example 3
The shape of silver particles
A
A
A
B
C
D
Of silver particles
Average particle diameter [占 퐉]
0.8
0.8
0.8
0.3
0.5
1.0
Volumetric resistance [μΩ · cm]
51
70
65
74000
7460
10460
Adhesion
Prize
Prize
Prize
medium
Prize
Prize
Implementing fine patterns
O
O
O
O
O
O
A: spherical silver particles with protrusions formed on the surface
B, C, and D: spherical silver particles having no protrusions on their surfaces
Referring to Table 1, it can be confirmed that Examples 1 to 3 exhibit volume resistivities of 100 占 占 cm m or less. As described above, it is known that as the average size of the conductive particles is in the range of 0.5 to 2 占 퐉, the contact area between the conductive particles increases as the size decreases, and the interfacial resistance decreases. In Experimental Example 1, The volume resistivity of Comparative Example 2 is smaller than that of Comparative Example 2. [ It can be seen that the interface between the silver particles is greatly increased by the protrusions formed on the surface of the silver particles used in Examples 1 to 3, and the interface resistance is reduced. In addition, the volume resistivity differences in Examples 1 to 3 can be considered to be caused by the difference in the types of the photosensitive resin and the thermosetting resin used, and even if a resin having a different composition is applied, Respectively.
As a result of evaluating the adhesion to base material, Examples 1 to 3 and Comparative Examples 2 to 3 showed excellent adhesion, Comparative Example 1 showed that although the same binder as in Example 1 was included in the same amount, Respectively. Silver particles of the present invention having a large specific surface area due to the shape of the powder can be seen to be more firmly bonded to the photosensitive resin and the thermosetting resin and to exhibit excellent adhesion.
[Example 4]
Electrode was prepared under the same conditions as in Example 1, except that the silver powder was added in an amount of 55 wt%.
[Comparative Example 4]
Electrode was prepared under the same conditions as in Example 1, except that the silver powder was added in an amount of 40 wt%.
[Comparative Example 5]
Electrode was prepared under the same conditions as in Example 1, except that the silver powder was added in an amount of 85 wt%.
[Experimental Example 2]
In order to examine the conductivity and adhesion according to the content of silver powder, the resistance measurement and the adhesion test were carried out in the same manner as in Example 1, Example 1, Example 4 and Comparative Examples 4 to 5, .
Comparative Example 4
Example 4
Example 1
Comparative Example 5
Silver content [wt%]
40
55
65
85
Volumetric resistance [μΩ · cm]
92500
98
51
276
Adhesion
Prize
Prize
Prize
Ha
Referring to Table 2, when the silver content is 40 wt%, the main component content determining the coating film characteristics is small, and the volume resistance is the largest, and it is confirmed that the content of the component determining the coating film characteristic is small and the highest volume resistance is obtained . However, as the content increased, the volume resistivity decreased. When the content was more than 85 wt%, the volume resistance tended to increase again. This is because the content of the photosensitive resin and the thermosetting resin is relatively decreased due to the increase of the silver content. As described above, the photosensitive resin and the thermosetting resin form a medium capable of uniformly dispersing the conductive powder. If the content of the photosensitive resin and the thermosetting resin is insufficient, the cohesion between the particles becomes large, the uniformity of the formed electrode surface is lowered and the coating film characteristics may be deteriorated. In addition, the resin can fuse conductive particles while forming a three-dimensional network structure by light and heat. If the content of the resin is insufficient and the degree of fusion between silver particles is decreased, do. Therefore, the present invention limits the content of the conductive powder in the electrode paste to 50 to 70 wt%.
It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.
The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.
100: electrode
10: substrate
20: Conductive particles
30: polymer resin
Claims (18)
50 to 70 wt% of conductive powder;
5 to 25 wt% of a photosensitive organic compound; And
5 to 25 wt% of thermosetting resin;
And a control unit,
The particles of the conductive powder are spherical particles having protrusions formed on the surface thereof, and the protrusions are the same as the components of the conductive powder,
Wherein the particles of the conductive powder have a specific surface area of 1.3 m < 2 > / g or more larger than that of particles of the same size.
Wherein the particles of the conductive powder have an average particle diameter of 0.1 to 10 占 퐉.
The conductive powder may be at least one metal selected from the group consisting of Ag, Au, Cu, Pt, Sn, Ni, Al, W, Mo, Sb, Cr, Pb and Ti, Curing type photosensitive electrode paste.
Wherein the photosensitive organic compound is an acrylic resin.
Wherein the photosensitive organic compound further comprises at least one resin selected from the group consisting of a polyester-based resin and a cellulose-based resin.
Wherein the photosensitive organic compound further comprises a photo-curing agent.
Wherein the photo-curing agent is a polyfunctional acrylate monomer.
Wherein the thermosetting resin comprises at least one resin selected from the group consisting of an epoxy resin, a urethane resin, an acrylic resin, and a phenol resin.
Wherein the electrode paste further comprises a photoinitiator and a thermosetting agent.
Wherein the electrode paste further comprises at least one material selected from the group consisting of a UV absorber, a rheology modifier, a dispersant, a stabilizer, a defoamer, and a wetting agent.
i) preparing a substrate;
ii) applying the electrode paste to the substrate;
iii) drying the coated electrode paste to form a coated film;
iv) exposing the dried coating to light;
v) heat treating the coated film to form an electrode; , ≪ / RTI >
Wherein the volume resistivity of the electrode is more than 0 and not more than 100 μ? · Cm.
Further comprising the step of baking the photomask prior to the step iv) and developing after the step iv), wherein a predetermined pattern is formed on the electrode formed in the step v).
And the step (v) is performed at a temperature of 100 to 190 ° C.
In the step ii), the paste is applied to the substrate using any one of a screen printing method, a roll to roll printing method, a spin coating method, a blade coating method, a spray coating method, a slot die coating method and an ink jet coating method. Gt;
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| KR102112327B1 (en) * | 2018-12-04 | 2020-05-18 | 주식회사 엠디엠 | Method for manufacturing electronic circuit on a surface of three-dimensional structure |
| KR102217314B1 (en) * | 2020-03-18 | 2021-02-19 | 한국과학기술원 | A method of preparation of anisotropic polycrystalline thermoelectric materials, thermoelectric materials and thermoelectric devices comprising the same |
| KR102608305B1 (en) * | 2021-11-25 | 2023-11-30 | 한국화학연구원 | Positive photosensitive paste composition, electrode provided with conductive pattern using the same, and manufacturing method thereof |
| KR20230169605A (en) * | 2022-06-09 | 2023-12-18 | 충북대학교 산학협력단 | Conductive Wire Composition For Direct Ink Writing and It’s Flexible Circuit |
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| KR102097539B1 (en) * | 2018-08-29 | 2020-05-26 | 와이엠티 주식회사 | Display device with metal mesh and method for manufacturing the same |
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