KR20160029369A - Graphene Coated Conductive particles, and conductive materials including the same - Google Patents

Abstract

Provided are a conductive particle which comprises a resin fine particle, a conductive particle having a coating layer on the surface of the resin fine particle, and a graphene layer formed on the surface of the resin fine particle; and an anisotropic conductive material using the same. The conductive particle of the present invention has excellent long-term reliability through reducing increase rate of contact resistance by having the graphene layer.

Description

Graphene-coated conductive particles and conductive materials containing the same,

TECHNICAL FIELD The present invention relates to conductive particles coated with graphene, and more particularly to conductive particles used in anisotropic conductive materials such as anisotropic conductive film (ACF).

The conductive particles may be used in a dispersed form mixed with a curing agent, an adhesive, or a resin binder, for example, an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive ink, And is widely used for anisotropic conductive connection materials such as anisotropic conductive sheets.

For example, anisotropic conductive connection materials are used for flat panel display panel assemblies such as Liquid Crystal Display (LCD), Active Matrix Organic Light Emitting Diode (AMOLED) and Plasma Display Panel (PDP) It is used for electrical connection between Driver Integrated Circuit (IC) for driving, connection of driving module and electrode of TSP (Touch Screen Panel).

The conductive particles used in such an anisotropic conductive connection material are metal particles such as nickel, copper, silver, and gold, carbon powder such as carbon powder, carbon fiber, carbon flake, etc., And composite particle.

The metal system is mainly used for a PDP or a PCB which requires a large current density and a high current, rather than a field requiring a fine pitch or high precision because the entire particle has conductivity and a wide particle size distribution.

The carbon-based particles have a lower electrical conductivity than the metal-based particles and have a large particle size distribution.

On the other hand, the composite particles are conductive particles most widely used at present, since the electric conductivity is about the midway between the above-mentioned metal system and carbon system and the distribution of the fine particles can be produced very narrowly.

The composite conductive particles may be formed by forming an alloy plating layer such as Ni-P or Ni-B or Ni-PW or Ni-BW on a spherical resin by an electroless plating method or a vacuum deposition or painting method, Precious metals such as gold, silver, palladium, and platinum may be used in the outermost layer for the purpose of preventing corrosion and increasing electrical conductivity.

Since the outermost noble metal accounts for 30-90% of the material cost of the conductive particles, it has been trying to reduce or not use it in the past. In Patent Document 10-2006-7027262, Ni-P is plated on Ni-P to provide a double-plated layer (conductive layer). In Patent Publication No. 10-2009-7026447, a low melting point metal is plated And how to do it. Japanese Patent Application Laid-Open No. 11-43005, Japanese Patent Application Laid-Open Nos. 10-2001-7010643, and 10-2011-7008427 disclose a method of imparting protrusions to the surfaces of conductive particles. Recently, Japanese Patent Application Laid-Open No. 2005-221027, Japanese Patent Application Laid-Open No. 2005-221026, and Japanese Patent Application Laid-Open No. 10-2010-0140039 propose controlling the physical properties of particles. That is, the above methods propose a method of using a noble metal such as gold, a method of using a small amount of gold, and a method of introducing a projection. However, in recent years, the use of protruding conductive particles, which have reduced material cost and little fluctuation in performance, is used, and the amount of conductive particles that do not use a noble metal at the outermost periphery is increasing.

The most vulnerable part of the conductive particles not using the noble metal at the outermost layer is reliability. This is because the absence of noble metals with low reactivity at the outermost layer reduces the reliability over time due to the corrosion of the conductive metal layer. In order to overcome this, anti-corrosive coating may be applied. Although reliability is improved after coating with rust preventive agent, adhesion of ACF resin to ACF film is lowered or aggregation of conductive particles is found, resulting in a large number of defective products in actual application.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and one aspect of the present invention is to provide a conductive particle having excellent long-term reliability and low rate of connection resistance increase.

Another aspect of the present invention is to provide a connecting material such as an anisotropic conductive film using the above-mentioned conductive particles.

The conductive particles, which are one embodiment of the present invention, include resin fine particles; A first coating layer provided on a surface of the resin fine particles; And a graphene layer provided on a surface of the first coating layer.

The graphene layer may be a layer coated with Reduced Graphene (RG), Reduced Graphene Oxide (RGO), Graphene, or Graphene Oxide.

The material of the resin fine particles may be a copolymer of any one or more monomers selected from the group consisting of a styrenic monomer, an acrylic monomer, a divinylbenzene monomer, and a modified monomer thereof.

The material of the first coating layer may be one of a single metal selected from the group consisting of Au, Ag, Ni, Cu, Sn, Zn, Ti and Co or a single metal selected from the group consisting of Ni, Sn, Ag, Cu, A single metal selected from the group consisting of Au, Ag, Ni, Cu, Sn, Zn, Ti and Co, or a single metal selected from the group consisting of Ni , Sn, Ag, Cu, Pb, Zn, Co, W, P, B and Au.

The conductive particles according to another embodiment of the present invention further include a second coating layer composed of one or more metals selected from the group consisting of Au, Pt, Ag and Pd between the first coating layer and the graphene layer Or the first coating layer may be a first coating layer having protrusions on the outer surface thereof.

Wherein the material of the protrusions is at least one of a single metal selected from the group consisting of Au, Ag, Ni, Cu, Sn, Zn, Ti and Co or a single metal selected from the group consisting of Ni, Sn, Ag, Cu, Pb, Zn, P, B, and Au.

A method for producing conductive particles, which is one aspect of the present invention, comprises: a resin microparticle-forming step of producing a core with a resin by using a polymerization reaction; A first coating layer forming step of forming conductive particles by forming a first coating layer on the resin fine particles using an oxidation-reduction reaction; And a graphene layer forming step of coating the surfaces of the conductive particles with graphene using a chemical reaction using a reducing agent.

In the first coating layer forming step, resin fine particles formed in the resin fine particle forming step are dispersed in a first coating solution in which a metal salt is dissolved, and a second coating solution in which a reducing agent is dissolved is further added, Forming the coating layer or adding the second coating liquid at a rate of 20 to 25 ml / min and increasing the charging rate by 0.2 to 10% to form a first coating layer having protrusions on the outer surface.

The first coating layer forming step further includes a surface treatment step of forming an activation nuclei on the surface of the resin fine particles, wherein the surface treatment step comprises a reaction for adsorbing an ionic substance having a reducing power on the surface of the resin fine particles, Reduction reaction in which activation nuclei are formed on the surface of the resin fine particles adsorbed with the substance.

Wherein the graphene layer forming step comprises the steps of: preparing reduced graphene oxide; And coating the reduced graphene oxide with conductive particles using the reduced graphene oxide, wherein the reduced graphene oxide is prepared by oxidizing graphite to produce graphite oxide ; Removing the graphite oxide layer and separating it to form graphene oxide (GO) in a state of being dispersed in an aqueous solution; And a reducing step of reducing the graphene oxide to produce reduced graphene oxide (RGO).

The step of coating the conductive particles with the reduced graphene oxide may include the step of dispersing the reduced graphene oxide in a solvent and then adding the conductive particles and reacting to form a graphene layer on the surface of the conductive particles.

The present invention also provides an anisotropic conductive connection material using the conductive particles, wherein the insulating resin layer; And conductive particles dispersed in the insulating resin layer, wherein the connection resistance increase rate after 1,000 hours of 85 ° C / 85% test is 1.5 or less.

The conductive particles according to one aspect of the present invention include a graphene layer on the outer periphery, so that the rate of increase in connection resistance is low during long-term use, and the long-term reliability of the circuit including the conductive particles according to the present invention can be secured.

In addition, the anisotropic conductive material according to another aspect of the present invention is excellent in long-term reliability of electronic equipment using the anisotropic conductive bonding material by using conductive particles having a low rate of connection resistance increase.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a SEM photograph of a conductive particle having a projection according to an embodiment of the present invention. FIG.
2 is a SEM photograph of the conductive particles according to the embodiment of the present invention.

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is defined solely by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise stated.

Throughout this specification and claims, the word "comprise", "comprises", "comprising" means including a stated article, step or group of articles, and steps, , Step, or group of objects, or group of steps, unless the context clearly indicates otherwise, and unless otherwise stated, refers to an object, step, or group of objects, Steps, or groups of things, and steps in addition to steps, steps, and steps.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. Any feature that is specifically or advantageously indicated as being advantageous may be combined with any other feature or feature that is indicated as being preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

The conductive particle according to an embodiment of the present invention includes a resin coating, a first coating layer provided on the surface of the resin fine particles, and a graphene layer provided on the surface of the first coating layer. Also, the first coating layer may have a projection on the surface.

The resin fine particles are composed of a polymer of a monomer. The material is not limited, but it is preferable to use a copolymer obtained by polymerizing monomers such as styrene type, acrylic type, divinylbenzene type, modified monomers thereof, or mixed monomers of the monomers.

For example, ethyl acrylate, methyl acrylate, butyl acrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, isooctyl acrylate, methyl methacrylate, nucleic acid diol diacrylate , Monomers such as styrene, methylstyrene, ethylstyrene, and divinylbenzene may be used singly or in combination of two or more.

The resin microparticles act as a damper that prevents the direct contact between the upper and lower electrodes and prevents the upper and lower electrodes from breaking during bonding by bonding the anisotropic conductive film (ACF). The average diameter of the resin fine particles is preferably 2.3 to 24.5 mu m.

The resin microparticles may be spherical in shape, acting as a core of conductive particles, but are not limited thereto, and may be in various forms.

Sn, Ag, Cu, Pb, Zn, Ti, and Co, or a single metal selected from the group consisting of Au, Ag, Ni, Sn, Pb, Sn-Cu, Sn-Zn, Ni-P, Ni-B, Ni-W, and Ni are selected from the group consisting of Co, W, P, B and Au. But may also be composed of alloys such as -PW, Ni-B, Ni-WB, Ni-Co, Ni-P-Co, Ni-B-Co, Ni-Cu, Ni-P- have.

The thickness of the first coating layer is preferably 0.03 to 0.3 mu m. When the thickness is less than 0.03 탆, the resistance increases sharply and the signals in the circuit can not be transmitted smoothly. On the other hand, when the thickness is more than 0.3 탆, the initial connection resistance is decreased, but the reliability of the product is adversely affected. The thickness of the first coating layer is preferably 0.05 to 0.25 mu m, and more preferably 0.08 to 0.20 mu m.

The first coating layer may be a first coating layer having protrusions on the outer surface. The height of the projection is not particularly limited, but the height of the projection is preferably 50 nm to 500 nm. When the height of the projection is less than 50 nm or exceeds 500 nm, the connection resistance value tends to increase because the effect of breaking the metal oxide layer and the binder resin is weakened, and the height of the projection is more preferably 150 to 350 nm. The shape of the projection is not particularly limited. Fig. 1 shows SEM photographs of the conductive particles having protrusions.

The protrusions may be made of the same material as the first coating layer or may be made of different materials. The protrusions may be made of a single metal such as Au, Ag, Cu, Ni, Ti, Bi, Sb or Sn- Cu, Sn-Zn, Ni-P, Ni-B, Ni-W, Ni-PW, Ni-B, Ni-WB, Ni- Ni-P-Cu, Ni-B-Cu, and the like. Preferred metals are Ni, Au, Ag, Pd, Pt, Ti, W, Co, Cu and the like.

The second coating layer may further include a noble metal such as Ag, Au, Pt, or Pd on the surface of the conductive particle on which the first coating layer or the first coating layer with the projection is formed on the surface of the resin fine particles. By further including the second coating layer, the conductivity of the conductive particles can be increased and the effect of preventing oxidation can be obtained. The second coating layer may be formed on the entire surface.

The graphene layer is formed on the surface of the first coating layer, the first coating layer having protrusions on the outer surface or the second coating layer. Fig. 2 shows SEM photographs of the conductive particles including the graphene layer. Graphene is a material that has a thermal conductivity of 50% or more higher than carbon nanotubes and has a two-dimensional planar structure formed by periodically arranging hexagonal ring structures formed of carbon atoms. Graphene also has excellent thermal stability, has a thermal conductivity twice as high as diamond, more than 200 times higher than steel, and 100 times more current than copper and an electrical conductivity that is 50 times faster than silicon Conductive particles coated with graphene may exhibit low connection resistance.

The graphene layer may be coated with Reduced Graphene (RG) Reduced Graphene Oxide (RGO), Graphene, Graphene Oxide, or the like. The coating method can form a graphene layer by a method such as general painting, coating on an aqueous solution, chemical vapor deposition (CVD), electroplating and the like.

The size of the conductive particles according to the present invention is not limited, but it is preferable that the conductive particles have an average diameter of 2.5 to 25 μm. When the size of the conductive particles is less than 2.5 占 퐉, the roughness of the electrode surface is 2.5 占 퐉 in the present technology. Therefore, in ACF bonding, the electrode is not contacted in the form of electrode-conductive particle- There is a problem that an electrode is broken by applying an excessive force to the electrode, and when it is more than 25 m, there is a problem that it can not be used for ACF.

The average diameter of the conductive particles is a mode value measured using a particle size analyzer (BECKMAN MULTISIZER TM3), wherein the number of conductive particles measured is preferably 75,000.

One embodiment of the method for producing conductive particles, which is another aspect of the present invention, includes a resin fine particle forming step, a first coating layer forming step, and a graphene layer forming step. The conductive particle manufacturing method of the present invention may further comprise a second coating layer forming step.

The resin microparticle forming step is a step of forming a core of conductive particles with a resin, and resin microparticles can be produced by a method such as dispersion polymerization, emulsion polymerization, suspension polymerization and the like. In the case of suspension polymerization, it is impossible to prepare resin fine particles of uniform size, and resin fine particles having a very uniform size of emulsion polymerization can be produced. However, in order to produce resin fine particles of several micrometer size, various steps must be performed. Therefore, it is preferable to prepare uniform resin microparticles having a size of several micrometers in a single process through dispersion polymerization.

In the present invention, a suspension prepared by adding the above-mentioned monomer and dispersion stabilizer to a solvent is prepared, and then a polymerization agent is added, stirred, and heated to proceed a polymerization reaction to form resin fine particles. The reaction temperature is preferably from 60 to 70 ° C, and the reaction time is preferably from 10 to 15 hours.

As the solvent, water, deionized water, a polar solvent such as DMSO, THF, DMF or alcohol, or a monomer or a mixture of a non-polar solvent and a monomer and a polymer can be used. Preferably, deionized water or a mixed solution of deionized water and alcohol is used.

As the dispersion stabilizer, polyvinyl pyrrolidone, polyvinyl acetate, hydroxypropyl-cellulose butyl acrylate and the like can be used.

Examples of the polymerization agent include a persulfate-based polymer such as calcium persulfate, ammonium persulfate and sodium persulfate, a peroxide-based polymer such as hydrogen peroxide, benzol peroxide and lauryl peroxide, azobisisobutyronitrile (AIBN), azo An azo-based polymer such as bisformamide can be used.

The weight ratio of the monomer, dispersion stabilizer and polymerization agent to be added to the solvent is preferably 25 to 35: 1 to 5: 0.1 to 0.5. The fine particles formed in the suspension are filtered, washed, classified and dried to produce resin fine particles.

The first coating layer forming step is a step of coating the surface of the resin fine particles with a metal and means a process of depositing a metal for forming the first coating layer on the surface of the resin fine particles by an electrochemical oxidation-reduction action. The first coating layer forming step according to the present invention is not only easy to control the thickness of the coating layer but also has good corrosion resistance, minimizes the content of impurities, and can easily form an alloy layer. The first coating layer forming step may be a first coating layer forming step including protrusions on the outer surface.

More specifically, resin fine particles are dispersed in a first coating solution in which a solvent, a metal salt, a complexing agent and a stabilizer are dissolved, and the pH is adjusted. Thereafter, a second coating solution containing a solvent, a reducing agent and a stabilizer is further added by a metering pump The conductive particles having the first coating layer formed on the surface of the resin fine particles are produced. The first coating liquid and the second coating liquid, in which the metal salt and the reducing agent are respectively dissolved, are separately prepared, whereby the coating liquid can be stabilized and prevented from being decomposed.

Any solvent that dissolves a metal salt, a complexing agent, a stabilizer, or a reducing agent can be used without limitation, and it is preferable to use deionized water.

The metal salt contained in the first coating liquid can provide metal ions to be coated on the resin fine particles and the metal ions to be coated can form a coating layer on the surface of the resin fine particles. A metal-containing salt used as the material of the above-mentioned first coating layer can be used.

The complexing agent contained in the first coating liquid controls the rate of formation of the coating layer and prevents spontaneous decomposition of the coating layer, thereby providing a composition having excellent solution stability. The complexing agent is preferably included in an amount of 2 to 3 parts by weight based on 100 parts by weight of the metal salt, and sodium acetate can be used.

The stabilizer contained in the first coating liquid is a substance used to maintain the pH of the coating liquid which changes during the formation of the coating layer. Since the pH is affected by the degree of coating and the thickness of the coating layer, the pH of the coating liquid can be maintained It is preferable that the substance is added. The stabilizer is preferably contained in an amount of 0.001 to 0.002 parts by weight based on 100 parts by weight of the metal salt, and may be a lead (Pb) or cadmium (Cd)) compound.

A first coating liquid containing a surfactant may be used for improving the interfacial property between the resin fine particles and the first coating layer and for preventing pit formation. When a surfactant is contained, it is preferable that the surfactant is included in an amount of 1 to 2 parts by weight based on 100 parts by weight of the metal salt.

The pH of the first coating liquid is preferably 5.0 to 10.0. When the pH is in the range of 5.0 to 10.0, the coating speed is fast, the coating is efficiently performed, and a metal which is not easily precipitated by the kind of the metal ion can be more easily precipitated.

The reducing agent contained in the second coating liquid is a substance capable of reducing metal ions to be coated, such as a hypophosphite such as sodium hypophosphite, potassium hypophosphite and ammonium hypophosphite, a borohydride salt, dimethylamine borane and hydrazine And may include any one or more selected.

The stabilizer contained in the second coating liquid may be lead (Pb) or cadmium (Cd)) compound, and it is preferable that the stabilizer is contained in an amount of 0.0001 to 0.0005 parts by weight based on 100 parts by weight of the reducing agent contained in the second coating liquid.

In the first coating layer forming step, the resin fine particles and the first coating liquid are added to the reactor and the dispersion is treated for 5 to 10 minutes to adjust the pH to 6 to 7, and the temperature of the reactor is maintained at 60 to 70 ° C, At a rate of 20 to 25 ml / min, while maintaining the reaction for 20 to 25 minutes, thereby preparing conductive particles having a first coating layer formed on the surface of the resin fine particles.

The first coating layer forming step may further include a surface treatment step. The surface treatment step is a step of forming an activation nucleus for formation of a coating layer in the first coating layer formation step, and an activation nucleus to be attached to the reduced metal particle is formed on the resin fine particle surface. The surface treatment step includes a reaction for adsorbing an ionic substance having a reducing power to the surface of the resin particles and an oxidation-reduction reaction for forming an activation nucleus on the surface of the resin particles to which the ionic substance is adsorbed. The surface treatment step may further include an etching treatment using an alkali solution or an acid solution before the adsorption reaction.

The first coating layer forming step may include forming a first coating layer having protrusions on the outer surface thereof. The method of forming the first coating layer having the projections can form the projections by adjusting the application speed of the second coating liquid. The projections are formed by increasing the charging speed of the second coating liquid to 0.2 to 10%.

The step of forming the second coating layer is not particularly limited, and the techniques of general sputtering, plating and vapor deposition can be used.

Methods for obtaining graphene in the graphene layer formation step include a scotch tape method, a chemical vapor deposition (CVD) method, an epitaxial method using a silicon carbide insulator, a chemical method using a reducing agent, and the like .

The Scotch tape method is a method of obtaining a thinner graphene layer by sticking graphite to a scotch tape, taking out multiple layers, and removing a new scotch tape. In the chemical vapor deposition method, methane and hydrogen are flowed to the surface of Ni and Cu maintained at 1000 ° C to form a single layer or multiple layers of graphene. The silicon carbide epitaxial method is a technique for stacking monocrystalline layers one by one and is used to impart semiconducting properties to the graphene layer. The chemical method using a reducing agent is somewhat disadvantageous in terms of conductivity since the impurity content remains, but it is preferable to use a chemical method using a reducing agent in view of mass production. This will be described in detail below.

The chemical method using a reducing agent includes preparing reduced graphene oxide (RGO) and coating the conductive particles with reduced graphene oxide.

The step of preparing reduced graphene oxide includes an oxidation step of oxidizing graphite of layer structure with an oxidizing agent (strong acid) to produce a graphite oxide containing a hydrophilic group, a step of separating graphite oxide after washing the graphite oxide A stripping step of producing a single layer of graphene oxide (GO) dispersed in an aqueous solution, and a step of preparing a reduced graphene oxide (RGO) using a reducing agent Reduction step.

As the graphite in the oxidation step, graphite classified by the pulverization process can be used. As the oxidizing agent (strong acid), sulfuric acid, nitric acid, hydrochloric acid and the like can be used, and as the hydrophilic group, a hydroxyl group, an epoxide group, a carboxyl group and a lactate group Oxygen functional groups. After the classified graphite is stirred in an aqueous solution of strong acid and stirred at 50 to 80 ° C for 4 to 4.5 hours, potassium permanganate is added for smooth oxidation and the graphite is oxidized by holding at 60 to 65 ° C for 12 to 13 hours.

In the peeling step, ultrasonic waves can be used to smooth the layer separation after cleaning with hydrogen peroxide water and deionized water, using a centrifuge.

In the reduction step, reduced graphene oxide (RGO) having a concentration of 0.5 to 2% wt% can be prepared by adding a reducing agent such as hydrazine or ammonia at 80 to 85 ° C for 1 to 4 hours.

In the step of coating the conductive particles with reduced graphene oxide (RGO), the reduced graphene oxide (RGO) is dispersed in a solvent, and then the conductive particles are added and reacted to form a graphene layer on the surface of the conductive particles. (RGO) or graphene oxide (GO), which can be coated by using not only reduced graphene oxide but also graphene oxide (GO) or graphene Is preferable in terms of simplification of the manufacturing process and cost reduction.

In the case of reduced graphene oxide (RGO) or graphene oxide (GO), a local dipole of oxide and carbon in the hydrophilic groups hydroxyl, epoxide, carboxyl and lactate is formed. In this case, the (-) side of the oxide has a (-) group, the carbon side has a (+) side and the (-) side of the oxide has an affinity with a metal. Since the size of the GO is several nanometers, the specific surface area is very large and the coating is carried out by van der Waals force.

The conductive particles according to the present invention can be used as an anisotropic conductive film such as anisotropic conductive film (ACF), anisotropic conductive paste, anisotropic conductive ink, and anisotropic conductive sheet And an anisotropic conductive film using the conductive particles according to the present invention will be specifically described below as an embodiment.

 There is provided an anisotropic conductive film (ACF) comprising conductive particles and an insulating resin according to the present invention.

The insulating resin depends on the physical properties of the anisotropic conductive film (ACF). The insulating resin can be divided into a curable resin and a plastic resin depending on heat and / or change of the molecular structure depending on the light. The curable resin can also be classified into a thermosetting resin and a photo-curable resin depending on an energy source that causes curing, and the photo-curable resin can be classified into an ultraviolet ray curable resin and an infrared ray curable resin depending on the type of light. The anisotropic conductive film (ACF) usually includes a thermosetting resin. However, the present embodiment is not limited thereto, and the anisotropic conductive film (ACF) may include a photo-curable resin such as an ultraviolet curable resin.

The thermosetting (thermoplastic) resin is easier to cure and easier to manage the curing structure as compared to the photo-curable (photo-plastic) resin. However, the thermosetting resin (tentative resin) is disadvantageous in that it requires damage to other parts due to the use of thermal energy or a relatively long processing time. As the thermosetting resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a Novolak type epoxy resin, a phenol resin, a urea resin, a melamine resin, an unsaturated polyester resin, a resorcinol resin and the like may be used. As the thermoplastic resin, a saturated polyester resin, a vinyl resin, an acrylic resin, a polyolefin resin, a polyvinyl acetate (PVA) resin, a polycarbonate resin, a cellulose resin, a ketone resin, and a styrene resin may be used. The anisotropic conductive film (ACF) may contain a content of a minimum of about 10% and a maximum of about 40% and 50%, respectively, of the thermosetting resin and the thermoplastic resin.

The anisotropic conductive film (ACF) according to the present invention may further include various kinds of additives including a curing agent. Currently, packaging companies require an anisotropic conductive film (ACF) having a low-temperature fast curing property (for example, a bonding temperature of the pressure bonding is 80 DEG C or less and a bonding temperature of the compression bonding is about 180 DEG C or less). The curing agent is a material for allowing the above-mentioned thermosetting resin or the like to be cured quickly even at a low temperature, and may be included in an amount of about 0.1 to 10%. There is no particular limitation on the kind of the curing agent as long as it is a substance that helps cure at a low temperature such as a thermosetting resin. For example, an azo compound or an organic peroxide may be used. The anisotropic conductive film (ACF) may further include a coupling aid and a tackifier.

The content of the conductive particles contained in the anisotropic conductive film may be 3 to 30% by weight based on the insulating resin.

Examples and Comparative Examples

Example 1

Dissolve 15 g of PVP-30K as a dispersion stabilizer in 1,600 g of deionized water. 85 g of ethylene glycol dimethacrylate and 85 g of divinylbenzene monomer were added and stirred to prepare a suspension. To the suspension, 1.5 g of Benzoyl peroxide, which is a polymerization agent, is added and mixed well by stirring. The monomer suspension is heated to 85 캜 to carry out the polymerization reaction, and the reaction is completed by keeping it for 12 hours. After completion of the synthesis, the fine particles in the suspension were subjected to filtration, washing, classification, and drying to prepare resin fine particles having an average particle size of 3.0 탆.

Sn ²⁺ ions are adsorbed on the surface of the resin fine particles by using a solution obtained by dissolving hydrochloric acid (HCl) and tin chloride (SnCl ₂ ) in deionized water after etching the produced resin fine particles with an alkali solution or an acid solution, The catalytic treatment for forming the activated nucleus was carried out by the oxidation and reduction reaction of the following reaction formula with the solution in which hydrochloric acid and palladium chloride (PdCl ₂ ) were dissolved to perform the surface treatment of the resin fine particles.

[Reaction Scheme]

Sn ²⁺ + Pd ²⁺ -> Sn ⁴⁺ + Pd ⁰

Next, 2200 ml of deionized water, 190 g of nickel sulfate as a Ni salt, 5 g of sodium acetate as a complexing agent, 0.002 g of Pb-acetate as a stabilizer and 3 g of PEG-400 as a surfactant were dissolved in a 3 L reactor in this order to prepare a first coating solution. 20 g of the surface-treated resin fine particles were placed in the first coating liquid and dispersed for 5 minutes using a homogenizer. After the dispersion treatment, the pH was adjusted to 6.5 using ammonia water.

300 ml of deionized water, 240 g of sodium hypophosphite as a reducing agent and 0.001 g of Pb-acetate as a stabilizer were dissolved in order to obtain a second coating liquid.

The temperature of the 3L reactor was maintained at 65 占 폚, and the second coating liquid was introduced at a rate of 20 ml / min by a metering pump while stirring at 250 rpm. The second coating liquid was fully charged and the reaction was maintained for 20 minutes to prepare conductive particles having an average particle diameter of 3.32 mu m including the resin fine particles and the first coating layer.

The graphite having been mechanically pulverized was classified using a 20 mesh sheave. 10 g of the classified graphite was stirred for 4 hours in an aqueous solution containing 500 g of deionized water and 15 g of sulfuric acid. 5 g of potassium permanganate was added to the stirred solution to oxidize the graphite and treated at 60 DEG C for 12 hours. After that, 5 g of hydrogen peroxide was added, washed with deionized water and centrifugal separator, and then graphene oxide was prepared by using ultrasonic waves. The prepared graphene oxide was put into 15 g of hydrazine in a reaction vessel at 80 ° C to prepare a graphene solution.

0.2 g of the prepared graphene solution was dispersed in 300 g of ethanol and 10 g of deionized water and conductive particles containing the resin fine particles and the first coating layer thus prepared were added and reacted at a speed of 120 rpm for 24 hours to obtain resin fine particles, Was prepared.

Example 2

The conductive particles including the resin fine particles and the first coating layer prepared in Example 1 were subjected to Au substitution plating to produce conductive particles having Au at the outermost periphery to prepare conductive particles further comprising a second coating layer. The prepared conductive particles were coated with a graphene layer in the same manner as in Example 1.

Example 3

In Example 1, the second coating liquid was supplied by a metering pump at a rate of 20 ml / min for 5 minutes, and the remainder was charged at 25 ml / min to obtain a resin fine particle and an average including a first coating layer having protrusions with an average height of 220 nm on the outer surface Thereby producing conductive particles having a diameter of 3.31 mu m. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Example 4

The outermost portions of the conductive particles including the resin fine particles prepared in Example 3 and the first coating layer having protrusions on the outer surface were subjected to Au substitution plating to prepare conductive particles further comprising a second coating layer. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Example 5

30 g of PVP-30K as a dispersion stabilizer is dissolved in 1,600 g of deionized water. 115 g of a polystyrene monomer and 35 g of a methyl methacrylate monomer were added thereto and stirred to prepare a suspension. To the suspension, 1.5 g of Benzoyl peroxide, which is a polymerization agent, is added and mixed well by stirring. The monomer suspension is heated to 85 캜 to carry out the polymerization reaction, and the reaction is completed by keeping it for 12 hours. After the synthesis is completed, the fine particles in the suspension are filtered, washed, classified and dried to obtain resin fine particles having an average particle size of 9.8 mu m.

Using 35 g of the resin fine particles thus prepared, conductive particles having an average diameter of 10.1 占 퐉 including the resin fine particles and the first coating layer were produced in the same manner as in Example 1, and the conductive particles including the resin fine particles and the first coating layer Was subjected to Au substitution plating to prepare conductive particles further comprising a second coating layer. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Example 6

Using the resin microparticles prepared in Example 5, the second coating liquid in Example 1 was charged by a metering pump for 5 minutes at a rate of 20 ml / min and the rest was charged at 28 ml / min. Conductive particles including a first coating layer having projections were produced. Subsequently, Au plating was carried out to obtain conductive particles having Au at the outermost periphery, and conductive particles having an average diameter of 10.1 占 퐉, which further included the second coating layer, were prepared. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Example 7

Dissolve 15 g of PVP-30K as a dispersion stabilizer in 1,600 g of deionized water. 85 g of polystyrene monomer and 85 g of methyl methacrylate monomer were added thereto and stirred to prepare a suspension. To the suspension, 1.5 g of Benzoyl peroxide, which is a polymerization agent, is added and mixed well by stirring. The monomer suspension is heated to 85 캜 to carry out the polymerization reaction, and the reaction is completed by keeping it for 12 hours. After the synthesis is completed, the fine particles in the suspension are subjected to filtration, washing, classification, and drying to obtain fine resin particles having an average particle size of 20.1 占 퐉.

Using the prepared resin fine particles (70 g), conductive particles having an average diameter of 20.4 占 퐉 including the resin fine particles and the first coating layer were prepared in the same manner as in Example 1, and the conductive particles including the resin fine particles and the first coating layer Was subjected to Au substitution plating to prepare conductive particles further comprising a second coating layer. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Example 8

Using the resin microparticles prepared in Example 7, the second coating liquid in Example 1 was charged by a metering pump for 5 minutes at a rate of 20 ml / min and the rest was charged at 28 ml / min. Conductive particles including a first coating layer having projections were produced. Subsequently, Au plating was carried out to form conductive particles having Au at the outermost periphery, and conductive particles having an average diameter of 20.4 占 퐉, which further included the second coating layer, were prepared. Using the prepared conductive particles, a graphene layer was coated in the same manner as in Example 1.

Comparative Examples 1 to 8

Conductive particles were produced in the same manner as in Examples 1 to 8 except that the graphene layer coating was not performed.

Table 1 below shows the sizes and composition of the conductive particles produced.

division Size of resin microparticles (μm) Particle Size (μm) Presence or absence of projection Presence or absence of the second coating layer Graphene layer presence Example 1 3.0 3.32 × × ○ Example 2 3.0 3.32 × ○ ○ Example 3 3.0 3.32 ○ × ○ Example 4 3.0 3.32 ○ ○ ○ Example 5 9.8 10.1 × × ○ Example 6 9.8 10.1 ○ ○ ○ Example 7 20.1 20.4 × ○ ○ Example 8 20.1 20.4 ○ ○ ○ Comparative Example 1 3.0 3.32 × × × Comparative Example 2 3.0 3.32 × ○ × Comparative Example 3 3.0 3.32 ○ × × Comparative Example 4 3.0 3.32 ○ ○ × Comparative Example 5 9.8 10.1 × × × Comparative Example 6 9.8 10.1 ○ ○ × Comparative Example 7 20.1 20.4 × ○ × Comparative Example 8 20.1 20.4 ○ ○ ×

Experimental Example - Connection Resistance Measurement

ACF having a thickness of 25 mu m was prepared using the conductive particles prepared in Examples and Comparative Examples. At this time, the content of the conductive particles was added by adding 5 wt% to the insulating resin included in the ACF. Then, an FPCB with an inter-chip distance of 50 μm and an ITO-coated glass were bonded to each other and an environment test was conducted as one of reliability tests. The connection resistance between the electrodes was measured (hereinafter, referred to as '85 ° C / 85% test') after a certain period of use at a temperature of 85 ° C and a humidity of 85%. The initial (0 hr) connection resistance was measured, and the connection resistance after 250 hr, 500 hr, 1,000 hr 85 ° C / 85% test was measured. Table 2 and Table 3 show the connection resistance and connection resistance increase rate measured at 85 ° C / 85% test time.

division 85/85% Connection resistance (Ω) 0hr 250hr 500 hr 1,000hr Example 1 0.85 1.01 1.12 1.21 Example 2 0.74 0.84 0.96 1.01 Example 3 0.53 0.65 0.78 0.88 Example 4 0.48 0.64 0.74 0.84 Example 5 0.43 0.57 0.68 0.78 Example 6 0.38 0.49 0.57 0.68 Example 7 0.45 0.61 0.72 0.82 Example 8 0.35 0.51 0.62 0.72 Comparative Example 1 0.83 1.12 1.35 3.35 Comparative Example 2 0.72 0.89 1.5 2.96 Comparative Example 3 0.51 0.66 1.12 2.94 Comparative Example 4 0.47 0.62 1.08 2.91 Comparative Example 5 0.41 0.57 1.1 2.24 Comparative Example 6 0.34 0.45 0.89 2.05 Comparative Example 7 0.44 0.59 1.05 2.88 Comparative Example 8 0.35 0.50 0.96 2.79

division 85/85% Connection resistance increase rate with test time 250hr 500 hr 1,000hr Example 1 0.188 0.318 0.424 Example 2 0.135 0.297 0.365 Example 3 0.226 0.472 0.660 Example 4 0.333 0.541 0.750 Example 5 0.326 0.581 0.814 Example 6 0.289 0.500 0.789 Example 7 0.356 0.600 0.822 Example 8 0.457 0.771 1.057 Comparative Example 1 0.349 0.627 3.036 Comparative Example 2 0.236 1.083 3.111 Comparative Example 3 0.294 1.196 4.765 Comparative Example 4 0.319 1.298 5.191 Comparative Example 5 0.390 1.683 4.463 Comparative Example 6 0.324 1.618 5.029 Comparative Example 7 0.341 1.36 5.545 Comparative Example 8 0.429 1.743 6.971

Comparing the examples and the comparative examples, it was found that the ACF using the conductive particles containing the graphene layer showed an increase in the connection resistance after 250 hours of the 85 ° C / 85% test, that is, It can be seen that the connection resistance increase rate after 85 hours / 85% test 1,000 hours, that is, the connection resistance increase rate after long term use is significantly lower than 1.5. Thus, it can be seen that the long-term reliability of the anisotropic conductive material using the conductive particles according to the present invention is high.

The features, structures, effects, and the like illustrated in the above-described embodiments can be combined and modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

Claims (22)

Resin fine particles;
A first coating layer provided on a surface of the resin fine particles; And
And a graphene layer provided on a surface of the first coating layer. The method according to claim 1,
The graphene layer is a layer coated with reduced graphene (RG), reduced graphene oxide (RGO), graphene, or graphene oxide (GO). The method according to claim 1,
Wherein the material of the resin fine particles is a copolymer of at least one monomer selected from the group consisting of a styrene monomer, an acrylic monomer, a divinylbenzene monomer, and a modified monomer thereof. The method according to claim 1,
Wherein the resin fine particles have an average diameter of 2.3 to 24.5 占 퐉. The method according to claim 1,
Sn, Ag, Cu, Sn, Zn, Ti and Co, or a single metal selected from the group consisting of Au, Ag, Ni, W, P, B, and Au. The method according to claim 1,
And the thickness of the first coating layer is 0.03 to 0.3 占 퐉. The method according to claim 1,
And a second coating layer composed of one or more metals selected from the group consisting of Au, Pt, Ag and Pd between the first coating layer and the graphene layer. The method according to claim 1,
Wherein the first coating layer is a first coating layer having projections on the outer surface thereof,
And the height of the protrusions is 50 nm to 500 nm. 9. The method of claim 8,
Wherein the material of the protrusions is at least one of a single metal selected from the group consisting of Au, Ag, Ni, Cu, Sn, Zn, Ti and Co or a single metal selected from the group consisting of Ni, Sn, Ag, Cu, Pb, Zn, P, B, and Au. 9. The method of claim 8,
And a second coating layer composed of one or more metals selected from the group consisting of Au, Pt, Ag and Pd between the first coating layer having the projections on the outer surface and the graphene layer. 11. The method according to any one of claims 1 to 10,
Wherein the conductive particles have an average diameter of 2.5 to 25 占 퐉. A resin fine particle forming step of producing a core with a resin by using a polymerization reaction;
A first coating layer forming step of forming conductive particles by forming a first coating layer on the resin fine particles using an oxidation-reduction reaction; And
And a graphene layer forming step of coating the surfaces of the conductive particles with graphene using a chemical reaction using a reducing agent. 13. The method of claim 12,
In the first coating layer forming step, resin fine particles formed in the resin fine particle forming step are dispersed in a first coating solution in which a metal salt is dissolved, and a second coating solution in which a reducing agent is dissolved is further added, Thereby forming a coating layer. 14. The method of claim 13,
The first coating layer forming step is a step of putting the second coating liquid at a rate of 20 to 25 ml / min and increasing a charging rate by 0.2 to 10% to form a first coating layer having protrusions on the outer surface, Way. 15. The method according to any one of claims 12 to 14,
The first coating layer forming step further comprises a surface treatment step of forming an activation nucleus on the surface of the resin fine particles,
Wherein the surface treatment step comprises a reaction for adsorbing an ionic material having a reducing power to the surface of the resin fine particles and an oxidation and reduction reaction for forming an activation nuclei on the surface of the resin fine particles to which the ionic material is adsorbed ≪ / RTI > 15. The method according to any one of claims 12 to 14,
Forming a second coating layer on a surface of the first coating layer having protrusions on the first coating layer or on the outer surface thereof after the first coating layer forming step and before the graphene layer forming step, Way. 13. The method of claim 12,
The graphene layer forming step may include:
Preparing reduced graphene oxide; And
And coating the conductive particles with the reduced graphene oxide. 18. The method of claim 17,
The step of preparing the reduced graphene oxide comprises:
An oxidation step of oxidizing graphite to produce graphite oxide;
Removing the graphite oxide layer and separating it to form graphene oxide (GO) in a state of being dispersed in an aqueous solution; And
And a reducing step of reducing the graphene oxide to produce reduced graphene oxide (RGO). 18. The method of claim 17,
The step of coating the conductive particles with the reduced graphene oxide is a step of dispersing the reduced graphene oxide in a solvent and then adding and reacting the conductive particles to form a graphene layer on the surface of the conductive particles By weight. Section 1 And an anisotropic conductive connection material using the conductive particles according to any one of claims 1 to 10. An insulating resin layer; And
10. An anisotropic conductive film comprising the conductive particles according to any one of claims 1 to 9 dispersed in the insulating resin layer. 22. The method of claim 21,
Wherein the anisotropic conductive film has a connection resistance increase rate of 1.5 or less after 1,000 hours of 85 ° C / 85% test.

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