JP2012119326A - Conductive particle, manufacturing method for the same, manufacturing method for insulation coated conductive particle, and anisotropic conductive adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive adhesive film which can sufficiently prevent poor connection in connection of a circuit electrode in which pitch is narrowed and area is narrowed, to provide a method for manufacturing an insulation coated conductive particle capable of realizing the anisotropic conductive adhesive film, to provide a conductive particle capable of obtaining the insulation coated conductive particle, and to provide a method for manufacturing the conductive particle.SOLUTION: A conductive particle includes a gold layer with average film thickness of 300 Å or less formed on a nickel layer as the outermost layer, and an elemental composition ratio (Ni/Au) of nickel to gold on a surface of the conductive particle by X-ray photoelectron spectroscopy analysis is 0.4 or less.

Description

  The present invention relates to conductive particles, a method for producing the same, a method for producing insulating coated conductive particles, and an anisotropic conductive adhesive film.

  The method of mounting the liquid crystal driving IC on the glass panel for liquid crystal display can be roughly classified into two types, COG (Chip-on-Glass) mounting and COF (Chip-on-Flex). In COG mounting, an IC for liquid crystal is directly bonded onto a glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. The anisotropic conductivity here means conducting in the pressurizing direction and maintaining insulation in the non-pressurizing direction.

  In recent years, with the increase in definition of liquid crystal display, gold bumps, which are circuit electrodes of a liquid crystal driving IC, have been reduced in pitch and area. Under such circumstances, it becomes a problem that the conductive particles of the anisotropic conductive adhesive flow out between adjacent circuit electrodes and cause a short circuit. In addition, when conductive particles flow out between adjacent circuit electrodes, the number of conductive particles in the anisotropic conductive adhesive captured between the gold bump and the glass panel decreases, and the connection resistance between the opposing circuit electrodes is reduced. Raising and causing poor connections also becomes a problem.

  Therefore, as a method for solving these problems, a method for preventing deterioration of bonding quality in COF mounting or COF mounting by forming an insulating adhesive on at least one side of the anisotropic conductive adhesive (see Patent Document 1). See), a method of coating the entire surface of the conductive particles with an insulating coating (see Patent Document 2), and a method of coating the surface of the conductive particles with insulating child particles (see Patent Documents 3 and 4). Has been proposed.

JP-A-8-279371 Japanese Patent No. 2779409 Japanese Patent No. 2748705 International Publication No. 03/02955 Pamphlet

  However, in the method of forming an insulating adhesive layer on one side of the anisotropic conductive adhesive layer as in Patent Document 1, when the bump area is less than 3000 μm 2, in order to obtain stable conductivity between opposing circuit electrodes If sufficient anisotropic conductive particles are contained in the anisotropic conductive adhesive composition, insulation between adjacent electrodes will not be sufficient. In addition, as in Patent Document 2, the method of covering the entire surface of the conductive particles with an insulating coating can increase the insulation between adjacent electrodes, but the conductivity between the facing circuit electrodes is low. There is still room for improvement.

  Further, in the method of coating the surface of the conductive particles with the insulating particles, it is preferable to use a resin made of a resin such as acrylic as the insulating particles in order to ensure adhesion between the insulating particles and the conductive particles. is necessary. For this reason, when the circuit is thermocompression bonded, the resin-made insulating particles are melted to cover the entire surface of the conductive particles, and in the same manner as the method of covering the entire surface of the conductive particles with the insulating film, The conductivity between the circuit electrodes facing each other becomes insufficient.

  Patent Documents 3 and 4 describe inorganic oxides having relatively high hardness and high melting temperature as insulating child particles. As a method for coating conductive particles with such an inorganic oxide, for example, in Patent Document 4, silica having an isocyanate group on the surface is prepared by treating the silica surface with 3-isocyanatopropyltriethoxysilane, Then, the metal surface particles having the gold plating layer as the outermost layer were treated with 2-aminoethanethiol to form conductive particles having amino groups as functional groups on the metal surface, and the amino groups of the conductive particles and the silica A method of obtaining insulating coated conductive particles by reacting with an isocyanate group is described. In such a method, it is desirable that the particle surface is completely covered with gold. However, in recent years, the gold film thickness tends to be reduced from the viewpoint of cost reduction. When the average film thickness of gold is 300 mm or less, it is difficult for gold to completely cover the metal inside gold (usually nickel). In this case, it becomes difficult to control the coverage of the insulator particles. In addition, in the above conventional insulating coated conductive particles, when ultrasonic dispersion is applied, the coverage of the insulating particles decreases, and both insulation between circuit electrodes and conductivity between opposing circuit electrodes are sufficiently ensured. The present inventors have found that connection failure may occur.

  The present invention has been made in view of the above-described problems of the prior art, and it is possible to realize an anisotropic conductive adhesive that can sufficiently prevent poor connection in the connection of circuit electrodes with a narrow pitch and a small area. It is an object of the present invention to provide a method for producing insulating coated conductive particles, a conductive particle capable of obtaining such insulating coated conductive particles, and a method for producing the same. Another object of the present invention is to provide an anisotropic conductive adhesive film that can sufficiently prevent connection failure in connection of circuit electrodes having a narrow pitch and a small area.

  In order to solve the above problems, the present invention provides a conductive particle having a gold layer with an average film thickness of 300 mm or less formed on a nickel layer as an outermost layer, the surface of the conductive particle by X-ray photoelectron spectroscopy analysis, Provided is a conductive particle having a gold elemental composition ratio (Ni / Au) of 0.4 or less.

  According to the conductive particle of the present invention, a strong functional group can be sufficiently formed on the surface of the conductive particle by having the above configuration. According to such conductive particles of the present invention, it is possible to obtain insulating coated conductive particles that are firmly coated with a sufficient amount of insulator particles. According to the insulating coated conductive particles, even when ultrasonic dispersion is applied, both insulation between circuit electrodes and conduction between opposing circuit electrodes can be sufficiently ensured. An anisotropic conductive adhesive that can sufficiently prevent poor connection can be effectively realized in the connection of pitched and narrowed circuit electrodes.

  The conductive particles of the present invention preferably have a particle size of 4.0 μm or less from the viewpoint of maintaining insulation. When the particle diameter exceeds 4.0 μm, short-circuit defects tend to occur.

  The present invention is also a method for producing a conductive particle of the present invention, the step of forming a nickel layer by performing nickel plating on the surface of the core particle, and the step of forming a gold layer by applying gold plating on the nickel layer And a process for removing nickel present on the surface of the formed gold layer.

  In the method for producing conductive particles of the present invention, nickel present on the surface of the gold layer can be removed with an aqueous solution containing cyan or EDTA.

  The present invention also comprises contacting the outermost layer surface of the conductive particles of the present invention with a compound having a predetermined functional group and at least one group selected from the group consisting of a mercapto group, a sulfide group and a disulfide group, A functional group-containing conductive particle comprising: a step of obtaining a functional group-containing conductive particle having a predetermined functional group formed on the surface of the outermost layer of the conductive particle; and a step of bringing the functional group-containing conductive particle into contact with an insulator particle. A first method for producing insulating coated conductive particles whose surface is coated with the above insulator particles is provided.

  According to the first manufacturing method of the insulating coated conductive particles of the present invention, even when ultrasonic dispersion is performed by performing the above-described series of steps on the conductive particles of the present invention, the circuit Insulating coated conductive particles that can sufficiently ensure both the insulation between the electrodes and the conductivity between the opposing circuit electrodes can be obtained. In addition, according to the obtained insulating coated conductive particles, it is possible to effectively realize an anisotropic conductive adhesive that can sufficiently prevent connection failure in connection of circuit electrodes having a narrow pitch and a small area.

  The present invention also comprises contacting the outermost layer surface of the conductive particles of the present invention with a compound having a predetermined functional group and at least one group selected from the group consisting of a mercapto group, a sulfide group and a disulfide group, A step of obtaining a functional group-containing conductive particle having a predetermined functional group formed on the surface of the outermost layer of the conductive particle, and contacting the functional group-containing conductive particle with the polymer electrolyte, the surface of the functional group-containing conductive particle is a polymer. A step of obtaining polymer electrolyte-coated conductive particles coated with an electrolyte; and a step of bringing the polymer electrolyte-coated conductive particles and insulator particles into contact with each other. A second method for producing insulating coated conductive particles coated with the insulating particles is provided.

  According to the second method for producing insulating coated conductive particles of the present invention, even if ultrasonic dispersion is performed by applying the above-described series of steps to the conductive particles of the present invention, a circuit is provided. Insulating coated conductive particles that can sufficiently ensure both the insulation between the electrodes and the conductivity between the opposing circuit electrodes can be obtained. In addition, according to the obtained insulating coated conductive particles, it is possible to effectively realize an anisotropic conductive adhesive that can sufficiently prevent connection failure in connection of circuit electrodes having a narrow pitch and a small area.

  In the second method for producing insulating coated conductive particles of the present invention, polyamines can be used as the polymer electrolyte.

  Moreover, it is preferable that the said polyamine is a polyethyleneimine from a viewpoint of a high charge density.

  In the first and second methods for producing insulating coated conductive particles of the present invention, the predetermined functional group is preferably any one of a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group.

  Moreover, it is preferable that the said insulator particle | grains are inorganic oxides. Furthermore, the inorganic oxide is preferably silica particles.

  The present invention also provides an anisotropic conductive adhesive composition comprising insulating coated conductive particles obtained by the production method of the first or second production method of insulating coated conductive particles of the present invention, and an insulating resin composition. An anisotropic conductive adhesive film characterized in that an object is formed into a film.

  According to the present invention, in the connection of circuit electrodes having a narrow pitch and a small area, a method for producing insulating coated conductive particles capable of realizing an anisotropic conductive adhesive that can sufficiently prevent connection failure, and its Thus, it is possible to provide a conductive particle and a method for producing the same, which can obtain such insulating coated conductive particles. In addition, according to the present invention, an anisotropic conductive adhesive film can be provided that can sufficiently prevent poor connection in connection of circuit electrodes having a narrow pitch and a small area.

It is sectional drawing of the anisotropic conductive adhesive film concerning one Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the circuit connection body connected using the anisotropic conductive adhesive film concerning one Embodiment of this invention. It is sectional drawing of the circuit connection body connected using the anisotropic conductive adhesive film concerning one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  First, the conductive particles of the present invention will be described. The conductive particle of the present invention is a conductive particle having a gold layer with an average film thickness of 300 mm or less formed on a nickel layer as an outermost layer, and the elemental composition of nickel and gold on the surface of the conductive particle by X-ray photoelectron spectroscopy analysis The ratio (Ni / Au) is 0.4 or less.

  Examples of the conductive particles include those obtained by coating core particles with metal by plating.

  As the core particles, any of metal core particles, organic core particles, and inorganic core particles can be used, but organic core particles are preferably used from the viewpoint of conduction reliability.

  The material of the organic core particles is not particularly limited, and examples thereof include acrylic resins such as polymethyl methacrylate and polymethyl acrylate, and polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene.

  When the organic core particles are coated by plating or the like, examples of the metal include gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium, and the like. And metal compounds such as ITO and solder.

  The structure of the metal layer covering the organic core particles is not particularly limited, but in the present invention, a two-layer structure in which the outermost layer is a gold layer and a nickel layer is provided inside thereof is preferable. A metal layer such as copper may be further provided inside the nickel layer.

  The nickel / gold two-layer structure can be formed, for example, by a method in which the surface of the organic core particle is subjected to electroless nickel plating and then subjected to displacement gold plating. A sputtering method, a vapor deposition method, or the like can be given as a forming method other than plating, but the plating method is preferable when film thickness control at a level of several hundreds of millimeters is taken into consideration. The thickness of the nickel layer is not particularly limited, but is preferably in the range of 100 to 2000 mm, and more preferably in the range of 500 to 1000 mm.

  The step of forming a nickel layer on the surface of the organic core particles by nickel plating can be performed by first applying a palladium catalyst to the surface of the organic core particles before applying nickel plating, and then applying electroless nickel plating.

  Components constituting the electroless nickel plating solution include, for example, water-soluble nickel salts such as nickel sulfate and nickel chloride, reducing agents such as sodium hypophosphite, sodium borohydride, dimethylamine borane and hydrazine, citric acid And amino acids such as tartaric acid, hydroxyacetic acid, malic acid, lactic acid, gluconic acid and glycine, amines such as ethylenediamine and alkylamine, other ammonium, EDTA and pyrophosphoric acid.

  After completion of electroless nickel plating, it is preferable to perform water washing efficiently in a short time. The shorter the washing time, the more difficult it is to form an oxide film on the nickel surface. Usually, after completion of electroless nickel plating, filtration is performed using a membrane filter or the like. In this case as well, it is preferable to perform filtration quickly in order to prevent oxidation of nickel.

  Subsequently, a gold layer having an average film thickness of 300 mm or less is formed on the nickel layer by displacement gold plating. The displacement gold plating can be performed by immersing the particles after the nickel plating step in a displacement gold plating solution. Examples of the composition of the displacement gold plating solution include electroless plating solution containing trisodium ethylenediaminetetraacetate, disodium citrate and potassium gold cyanide and adjusted to pH with sodium hydroxide.

  In recent years, from the viewpoint of cost reduction, there is a tendency to reduce the film thickness of gold and suppress the cost, but it becomes easy to achieve the cost reduction requirement by making the average thickness of the gold layer 300 mm or less. .

  By the way, when a gold layer having an average film thickness of 300 mm or less is formed by displacement gold plating, nickel tends to be exposed on the gold plating surface. For commercially available conductive particles having a gold plating layer with a thickness of 300 mm or less, the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles (the ratio of nickel when the gold ratio is 1) is X-ray photoelectron As measured by spectroscopic analysis (ESCA), it has been found by the present inventors that all of them show a value exceeding 0.4 as shown in Table 2. In this specification, the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles refers to a value obtained by ESCA conditions shown in Table 1.

  As shown in Table 2, the commercially available gold-plated particles have a considerably large Ni / Au ratio on the surface. On the other hand, the conductive particles of the present invention require that the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles by X-ray photoelectron spectroscopy is 0.4 or less.

  Examples of a method for reducing the Ni / Au ratio on the surface of the conductive particles include the following methods.

  First, one of the factors that does not increase the gold coverage in displacement gold plating is oxidation of the nickel surface on which gold plating is applied. Therefore, shortening the water washing time after nickel plating (specifically, within 120 seconds at room temperature) and shortening the filtration time are examples of methods for lowering the Ni / Au ratio. In addition, cleaning the nickel layer surface with a cleaning solution containing EDTA or cyan after nickel plating is also effective as a method for reducing the above problem.

  Moreover, since substitution gold plating deposits gold | metal | money, melt | dissolving the nickel layer already formed, a nickel layer is apt to be formed on a gold film by all means. Therefore, it is effective to provide a step of dissolving the eluted nickel after the displacement gold plating.

  Examples of the step include an aqueous solution containing cyan or EDTA (ethylenediaminetetraacetic acid or a salt thereof), preferably an aqueous solution containing 0.01 to 0.1 mol / liter of EDTA or 0.01 to 0.1. A method of washing the gold plating surface with an aqueous solution containing mol / liter cyanide ions (such as sodium cyanide) can be mentioned. Thereby, nickel existing on the gold layer can be removed.

  Further, a step of removing nickel existing on the gold layer surface by plasma or other physical methods may be provided.

  By the means as described above, the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles can be reduced to 0.4 or less.

  The conductive particles of the present invention comprise, in a later step, a gold layer that is the outermost layer, a compound having at least one group selected from the group consisting of a mercapto group, a sulfide group, and a disulfide group and a predetermined functional group. By bringing it into contact, it is possible to form a strong functional group on the particle. When nickel is present on the particle surface, it is difficult to form a strong functional group on the particle, but according to the conductive particle of the present invention, the elemental composition ratio of nickel and gold on the surface (Ni / Au) Is 0.4 or less, a sufficient amount of strong functional groups can be formed on the surface of the conductive particles. When the elemental composition ratio (Ni / Au) of nickel and gold exceeds 0.4, the problem of exfoliation of the insulator particles tends to occur when the insulating coated conductive particles coated with the insulator particles are produced. .

  The particle diameter of the conductive particles of the present invention is preferably smaller than the minimum distance between the electrodes of the substrate to be connected, and when there is a variation in the height of the electrodes, it is preferably larger than the variation in the height. From such a viewpoint, the particle size of the conductive particles of the present invention is preferably in the range of 1 to 10 μm, more preferably in the range of 1 to 5 μm, still more preferably in the range of 2.0 to 4.0 μm, and 2.0 A range of ˜3.5 μm is particularly preferred.

  Next, the insulating coated conductive particles and the manufacturing method thereof according to the present invention will be described.

  The insulating coated conductive particles according to the present invention can be obtained by coating the conductive particles of the present invention with insulating particles.

  As the insulator particles, inorganic oxide fine particles are preferable. When organic fine particles are used, it is difficult to obtain stable characteristics because the insulator particles are easily deformed in the step of producing the anisotropic conductive adhesive.

  The inorganic oxide fine particles are preferably oxides containing silicon, aluminum, zirconium, titanium, niobium, zinc, tin, cerium, and magnesium. These can be used alone or in admixture of two or more.

  From the viewpoint of insulation reliability, the inorganic oxide fine particles preferably have an alkali metal ion and alkaline earth metal ion concentration of 100 ppm or less in the dispersion solution. As such inorganic oxide fine particles, for example, those produced by hydrolysis reaction of metal alkoxide, so-called sol-gel method, can be suitably used.

  As for the size of the inorganic oxide fine particles, the particle diameter measured by the specific surface area conversion method by the BET method or the X-ray small angle scattering method is preferably 20 nm to 500 nm. If the particle diameter of the inorganic oxide fine particles is smaller than 20 nm, the inorganic oxide fine particles adsorbed on the conductive particles are less likely to act as an insulating film, and a short circuit is likely to occur in part. On the other hand, when the particle diameter of the inorganic oxide fine particles is larger than 500 nm, it is difficult to obtain the conductivity in the pressurizing direction of the connection circuit.

  Among the above oxides, water-dispersed colloidal silica (SiO 2) is preferable because of excellent insulating properties and controlled particle size. As such inorganic oxide fine particles, for example, Snowtex, Snowtex UP (manufactured by Nissan Chemical Industries, Ltd.), Quatron PL series (manufactured by Fuso Chemical Industries, Ltd.) and the like are commercially available. Further, water-dispersed colloidal silica (SiO2) has the advantage that it has excellent bonding properties with conductive particles because it has a hydroxyl group on the surface, in addition to the features that the particle diameter is easily adjusted and is inexpensive.

  The hydroxyl group on the surface of the inorganic oxide can be modified to an amino group, a carboxyl group, or an epoxy group with a silane coupling agent or the like. However, when the particle size of the inorganic oxide is less than 500 nm, modification is difficult. Tend to be. Oxides such as silica are liable to cause a problem that they are aggregated during centrifugation or filtration after modification with a functional group. Therefore, it is desirable that the inorganic oxide fine particles having the above particle diameter are coated on the conductive particles without modifying the functional group.

  By the way, a hydroxyl group is generally known as a group capable of forming a strong bond with a functional group such as a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group. Examples of the bonding mode between the hydroxyl group and the functional group include a covalent bond by dehydration condensation and a hydrogen bond. In the present invention, a method is preferred in which these functional groups are formed on the surface of the conductive particles to obtain the functional group-containing conductive particles, and then the functional group-containing conductive particles are coated with the insulator particles to obtain the insulating coated conductive particles. .

  As a first embodiment of the method for producing such insulating coated conductive particles, the outermost layer surface of the conductive particles of the present invention, at least one group selected from the group consisting of mercapto groups, sulfide groups and disulfide groups and a predetermined A step of obtaining a functional group-containing conductive particle in which a predetermined functional group is formed on the surface of the outermost layer of the conductive particle, and contacting the functional group-containing conductive particle with the insulator particle And a step of obtaining insulating coated conductive particles obtained by coating the surfaces of the functional group-containing conductive particles with the insulator particles.

  As another preferred second embodiment, the outermost layer surface of the conductive particles of the present invention, at least one group selected from the group consisting of a mercapto group, a sulfide group and a disulfide group and a predetermined functional group are provided. A functional group-containing conductive particle in which a predetermined functional group is formed on the surface of the outermost layer of the conductive particle, the functional group-containing conductive particle and the polymer electrolyte are contacted, A functional group-containing conductive particle comprising: a step of obtaining a polymer electrolyte-coated conductive particle whose surface is coated with a polymer electrolyte; and a step of bringing the polymer electrolyte-coated conductive particle into contact with an insulator particle. A method of obtaining insulating coated conductive particles whose surface is coated with the polymer electrolyte and the insulator particles.

  Since the conductive particles of the present invention have a gold layer as the outermost layer, a compound having any one of a mercapto group, a sulfide group, and a disulfide group that forms a coordinate bond with gold is used to form a hydroxyl group on the gold surface. A predetermined functional group such as a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group can be formed. Specific examples of such a compound include mercaptoacetic acid, 2-mercaptoethanol, methyl mercaptoacetate, mercaptosuccinic acid, thioglycerin, and cysteine.

  Since the nickel / gold ratio on the surface of the conductive particle of the present invention is 0.4 or less, the functional group can be firmly formed on the surface of the conductive particle.

  The method for bringing the outermost layer surface of the conductive particles of the present invention into contact with the above compound is not particularly limited. For example, a compound such as mercaptoacetic acid is dispersed in an amount of about 10 to 100 mmol / l in an organic solvent such as methanol or ethanol. And the method of disperse | distributing the electrically-conductive particle of this invention in that is mentioned.

When the functional group-containing conductive particles are conductive particles having a hydroxyl group, a carboxyl group, an alkoxyl group, or an alkoxycarbonyl group, the surface potential (zeta potential) is usually negative (if the pH is neutral). On the other hand, when an inorganic oxide having a hydroxyl group is used as the insulator particles, the surface potential is usually negative. In such a case, since it is difficult to coat particles having a negative surface potential around particles having a negative surface potential, it is preferable to manufacture the insulating coated conductive particles by the method of the second embodiment.
As a more specific manufacturing method, conductive particles having functional groups (functional group-containing conductive particles) are dispersed in (1) a polymer electrolyte solution, the polymer electrolyte is adsorbed on the surface of the conductive particles, and then rinsed. (2) The polymer electrolyte-coated conductive particles obtained in the step (1) are dispersed in a dispersion solution of insulator particles such as inorganic oxide fine particles, and the insulator particles are formed on the surface of the polymer electrolyte-coated conductive particles. Insulating coated conductive particles coated with an insulating coating film in which a polymer electrolyte and insulating particles are laminated can be manufactured by performing a rinsing step after adsorbing the particles. Such a method is called an alternating lamination method (Layer-by-Layer assembly). The alternate lamination method is described in G.H. This is a method of forming an organic thin film published in 1992 by Decher et al. (Thin Solid Films, 210/211, p831 (1992)). In this method, a polycation adsorbed on a substrate by electrostatic attraction by alternately immersing the base material in an aqueous solution of a polymer electrolyte having a positive charge (polycation) and a polymer electrolyte having a negative charge (polyanion). A combination of polyanions can be laminated to obtain a composite film (alternate laminated film).

  In the alternating layering method, the film is grown by attracting the charge of the material formed on the substrate and the material having the opposite charge in the solution by electrostatic attraction, so that the adsorption proceeds and the charge is neutralized. When this occurs, no further adsorption occurs. Therefore, when reaching a certain saturation point, the film thickness does not increase any more. Lvov et al. Also applied an alternate lamination method to fine particles, using a fine particle dispersion of silica, titania, and ceria to laminate a polymer electrolyte having a charge opposite to the surface charge of the fine particles by the alternate lamination method. (Langmuir, Vol. 13, (1997) p6195-6203). By using this method, silica fine particles having a negative surface charge and polydiallyldimethylammonium chloride (PDDA) or polyethyleneimine (PEI), which are polycations having the opposite charge, are alternately laminated to form silica. It is possible to form a fine particle laminated thin film in which fine particles and a polymer electrolyte are alternately laminated.

  As shown in the steps (1) and (2) above, after the particles to be treated are immersed in a dispersion of insulator particles such as polymer electrolyte solution or inorganic oxide fine particles, dispersion of insulator particles having opposite charges is performed. Before immersing in the liquid or polymer electrolyte solution, it is preferable to wash away the excess polymer electrolyte solution or the dispersion of the insulator particles by rinsing with only the solvent.

  Examples of the solvent used for such rinsing include water, alcohol, and acetone. From the viewpoint of removing an excessive polymer electrolyte solution or dispersion of insulator particles, it is preferable to use ion-exchanged water (so-called ultrapure water) having a specific resistance of 18 MΩ · cm or more. The polymer electrolyte and the insulator particles adsorbed on the particles to be treated are not peeled off in this rinsing step.

  Also, by performing the above-described rinsing, the polymer electrolyte is brought into a dispersion of insulator particles such as inorganic oxide fine particles, and the insulator particles such as inorganic oxide fine particles are brought into the polymer electrolyte solution. This can be prevented. In addition, when cations and anions are mixed in the solution by being brought in, aggregation or precipitation of the insulator particles such as the polymer electrolyte and the inorganic oxide fine particles may occur.

  Examples of the polymer electrolyte solution used in this embodiment include a polymer electrolyte dissolved in water or a mixed solvent of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include methanol, ethanol, propanol, acetone, dimethylformamide, acetonitrile, and the like.

  As the polymer electrolyte, a polymer that is water-soluble or soluble in a mixed solution of water and an organic solvent, is ionized in an aqueous solution, and has a functional group having a charge in the main chain or side chain. it can. Such a polymer is preferably a polycation. Polycations having a positively charged functional group such as polyamines such as polyethyleneimine (PEI), polyallylamine hydrochloride (PAH), polydiallyldimethylammonium chloride (PDDA) , Polyvinyl pyridine (PVP), polylysine, polyacrylamide, and a copolymer containing at least one of these monomer units.

  Among the above polycations, polyethyleneimine is preferably used because it has a high charge density and a strong binding force with the functional group-containing conductive particles.

  The molecular weight of the polymer electrolyte cannot be determined unconditionally depending on the type of polymer electrolyte used, but is generally about 500 to 200,000.

  In addition, in order to avoid electromigration and corrosion, the polymer electrolyte has alkali metal (Li, Na, K, Rb, Cs) ions, alkaline earth metal (Ca, Sr, Ba, Ra) ions, halide ions. Those not containing (fluorine ion, chloride ion, bromine ion, iodine ion) are preferred.

  The concentration of the polymer electrolyte in the polymer electrolyte solution is preferably about 0.01 to 10% by mass. The pH of the polymer electrolyte solution is not particularly limited.

  By using the above-mentioned polymer electrolyte solution, the surface of the conductive particles of the present invention in which the functional group is formed can be uniformly coated with the insulator particles without any defects, and the insulation between the narrow pitch circuit electrodes is opposed. Insulating coated conductive particles that can sufficiently ensure both electrical conductivity between circuit electrodes can be realized more effectively.

  In this embodiment, by adjusting the type, molecular weight, and concentration of the polymer electrolyte adsorbed on the surface of the functional group-containing conductive particles, the ratio of the surface where the functional group-containing conductive particles are covered with the insulator particles, That is, the coverage can be controlled.

  Specifically, when a polymer electrolyte with a high charge density such as polyethyleneimine is used, the coverage of the insulator particles tends to be high, and a polymer electrolyte with a low charge density such as polydiallyldimethylammonium chloride was used. In such a case, the coverage tends to be low. Moreover, when the molecular weight of the polymer electrolyte is large, the coverage tends to be high, and when the molecular weight of the polymer electrolyte is small, the coverage tends to be low. From the viewpoint of bonding strength, the molecular weight of the polymer electrolyte is preferably 10,000 or more. Furthermore, when the polymer electrolyte is used at a high concentration, the coverage tends to be high, and when the polymer electrolyte 4 is used at a low concentration, the coverage tends to be low.

  When the coverage is high, the insulation between adjacent circuit electrodes on the same substrate tends to be high, and the conductivity between opposing circuit electrodes tends to decrease. When the coverage is low, the conductivity is low. Tends to be high, and the insulating properties tend to decrease.

  The insulator particles preferably cover the surface of the functional group-containing conductive particles or the polymer electrolyte-coated conductive particles in a single layer. When a plurality of layers of insulating particles are laminated on the surface of the functional group-containing conductive particles or polymer electrolyte-coated conductive particles, it tends to be difficult to control the amount of the insulating particles stacked. The coverage of the surface of the functional group-containing conductive particles or polymer electrolyte-coated conductive particles by the insulator particles is preferably in the range of 20 to 100%, more preferably in the range of 30% to 60%.

  The bonding strength between the insulating particles and the functional group-containing conductive particles or the polymer electrolyte-coated conductive particles can be further enhanced by heating and drying the insulating coated conductive particles produced as described above. In addition, it is preferable to perform the heating in vacuum from the viewpoint of preventing rust of the metal. The reason why the bonding force is increased is that a chemical bond between a functional group such as a carboxyl group on the surface of the functional group-containing conductive particle and a hydroxyl group on the surface of the insulating particle is newly formed, or a functional group-containing conductive particle It is possible to use a product obtained by dehydration condensation between a functional group such as a carboxyl group on the surface of the polymer electrolyte and a functional group such as an amino group of the polymer electrolyte-coated conductive particles. It is preferable to perform the heat drying of the insulating coated conductive particles at 60 ° C. to 200 ° C. for 10 to 180 minutes. When the temperature is lower than 60 ° C. or when the heating time is shorter than 10 minutes, the insulator particles tend to peel off, and when the temperature is higher than 200 ° C. or when the heating time is longer than 180 minutes, the insulating particles are insulated. The coated conductive particles tend to be deformed.

  Next, the anisotropic conductive adhesive film of the present invention will be described.

  FIG. 1 is a cross-sectional view of an anisotropic conductive adhesive film according to an embodiment of the present invention. The anisotropic conductive adhesive film 50 of the present embodiment is different in that the insulating coated conductive particles 10 according to the present invention produced as described above are dispersed in an insulating resin composition 12 that also functions as an adhesive. A one-sided conductive adhesive composition is formed into a film. In FIG. 1, the insulating coated conductive particles 10 are obtained by coating the surface of the functional group-containing conductive particles 8 with the polymer electrolyte and the insulator particles 6, but the polymer electrolyte is not shown for convenience.

  As the resin composition 12 used in the anisotropic conductive adhesive composition according to this embodiment, a mixture of a heat-reactive resin and a curing agent can be used. Among these, it is preferable to use a mixture of an epoxy resin and a latent curing agent. As the latent curing agent, imidazole series, hydrazide series, boron trifluoride-amine complex, sulfonium salt, amine imide, polyamine salt, dicyandiamide, and the like can be used. As another embodiment of the present invention, the resin composition 12 may be a mixture of a radical reactive resin and an organic peroxide or an energy ray curable resin such as ultraviolet rays.

Epoxy resins include bisphenol-type epoxy resins derived from epichlorohydrin and bisphenol A, bisphenol F, bisphenol AD, etc., epoxy novolac resins derived from epichlorohydrin and phenol novolac or cresol novolac, and skeletons containing naphthalene rings. It is possible to use various epoxy compounds having two or more glycidyl groups in one molecule, such as naphthalene-based epoxy resin, glycidylamine, glycidyl ether, biphenyl, alicyclic, etc., alone or in combination of two or more. it can. From the viewpoint of preventing electromigration, these epoxy resins are preferably high-purity products in which impurity ions (Na ⁺ , Cl ^−, etc.), hydrolyzable chlorine, etc. are reduced to 300 ppm or less.

  In order to reduce the stress after circuit adhesion or to improve the adhesion, the resin composition 12 is mixed with butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, etc. in addition to the above-mentioned components. Can do.

  In the anisotropic conductive adhesive composition, it is preferable to blend a thermoplastic resin (film-forming polymer) such as a phenoxy resin, a polyester resin, or a polyamide resin with the resin composition 12 from the viewpoint of film-forming property. Mixing these film-forming polymers is also preferable from the viewpoint of reducing stress during curing of the reactive resin. Further, from the viewpoint of improving adhesiveness, it is more preferable that the film-forming polymer has a functional group such as a hydroxyl group. The anisotropic conductive adhesive composition may be paste-like.

  For film formation, a resin composition 12 containing an epoxy resin, acrylic rubber, and a latent curing agent is dissolved or dispersed in an organic solvent to liquefy, and the insulating coating conductive particles 10 are added and dispersed, and applied onto a peelable substrate. Then, the solvent is removed below the activation temperature of the curing agent. As the organic solvent, from the viewpoint of improving the solubility of the resin composition 12, a mixed solvent of an aromatic hydrocarbon type and an oxygen-containing type is preferable.

  The ratio of the insulating coated conductive particles 10 in the anisotropic conductive adhesive composition is the entire anisotropic conductive adhesive composition from the viewpoint of improving the insulation between adjacent electrodes and the conductivity between opposing electrodes. Is preferably 0.1 to 30% by volume, more preferably 1 to 25% by volume.

  The thickness of the anisotropic conductive adhesive film 50 is relatively determined in consideration of the particle size of the insulating coated conductive particles 10 and the characteristics of the anisotropic conductive adhesive composition, but is preferably 1 to 100 μm. -50 μm is more preferable. If the anisotropic conductive adhesive film 50 has a thickness of 1 μm or less, sufficient adhesiveness tends to be not obtained. If the thickness is 100 μm or more, a large amount of insulating coated conductive particles 10 are required to obtain conductivity between opposing circuit electrodes. This is not realistic.

  FIG. 2 is a cross-sectional view illustrating a method for manufacturing a circuit connection body connected using an anisotropic conductive adhesive film according to an embodiment of the present invention. In FIG. 2, the polymer electrolyte adsorbed on the surface of the functional group-containing conductive particles 8 is not shown for convenience.

  The first circuit member includes a first electrode 22 on the surface 21 a of the first substrate 21. The second circuit member includes a second electrode 32 on the surface 31 a of the second substrate 31. Examples of the substrate include a glass substrate, a tape substrate such as polyimide, a bare chip such as a driver IC, and a rigid package substrate.

  The above-described anisotropic conductive adhesive film 50 is interposed between the first circuit member 20 and the second circuit member 30. At this time, the first circuit member 20 and the second circuit member 30 are arranged so that the first circuit electrode 22 and the second circuit electrode 32 face each other.

  Next, while the anisotropic conductive adhesive film 50 is heated through the circuit member 20 and the circuit member 30, pressure is applied in the directions of arrows A and B in FIG. 2 to form a circuit connector. The curing treatment can be performed by a general method such as ultraviolet irradiation or heating, and the method is appropriately selected depending on the resin composition 12.

  FIG. 3 is a cross-sectional view of a circuit connection body connected using an anisotropic conductive adhesive film according to an embodiment of the present invention. The circuit connection body connected in this way has conductivity between the circuit electrode 22 and the circuit electrode 32 facing each other, and insulation between the circuit electrodes 22 adjacent to each other and between the circuit electrodes 32 on the same substrate. Excellent. In FIG. 3, the polymer electrolyte adsorbed on the surface of the functional group-containing conductive particles 8 is not shown for convenience.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

<Preparation of conductive particles>
(Conductive particles 1)
1 g of crosslinked polystyrene particles having an average particle diameter of 3.8 μm was added to 100 mL of a palladium-catalyzed solution containing 8% by mass of Atotech Nene Gantt 834 (manufactured by Atotech Japan Co., Ltd .: trade name) which is a palladium catalyst. After stirring for 30 minutes at 0 ° C., the mixture was filtered through a 3 μm membrane filter and washed with water to obtain resin fine particles provided with a palladium catalyst. Next, the resin fine particles were added to a 0.5% by mass dimethylamine borane liquid adjusted to pH 6.0 to obtain resin fine particles whose surface was activated.

  Next, the resin fine particles whose surface was activated were immersed in distilled water and ultrasonically dispersed. Then, while stirring the suspension at 50 ° C., nickel sulfate hexahydrate 50 g / L, sodium hypophosphite monohydrate 20 g / L, dimethylamine borane 2.5 g / L, and citric acid 50 g / L The electroless plating solution A having a pH of L adjusted to 7.5 was gradually added to perform electroless nickel plating of the resin fine particles. At this time, the film thickness of nickel was confirmed by sampling and atomic absorption analysis, and the addition of the electroless plating solution A was stopped when the nickel film thickness reached 700 mm. After filtration, washing with 100 mL of pure water was performed for 60 seconds to produce resin fine particles A having a 700-mm nickel film on the surface.

  Subsequently, it contains 0.03 mol / liter tetrasodium ethylenediaminetetraacetate, 0.04 mol / liter trisodium citrate and 0.01 mol / liter potassium gold cyanide, adjusted to pH 6 with sodium hydroxide. A plating solution was prepared, and resin fine particles A were treated with this plating solution at a liquid temperature of 60 ° C. until the average film thickness of the gold plating reached 200 mm. The treated resin fine particles A were filtered and washed with 100 mL of pure water for 60 seconds to produce resin fine particles B having an outermost layer in which a gold film having an average film thickness of 200 mm was formed on a nickel film. Next, the resin fine particle B contains 0.03 mol / liter tetrasodium ethylenediaminetetraacetate, 0.04 mol / liter trisodium citrate and 0.01 mol / liter sodium cyanide. The solution was adjusted to pH 6 and treated at 60 ° C. for 1 minute to remove nickel on the surface. Thereafter, the particles from which nickel was removed from the surface were immersed in isopropyl alcohol and dried by a vacuum drier to produce conductive particles 1.

(Conductive particles 2)
Plating solution containing 0.03 mol / liter tetrasodium ethylenediaminetetraacetate, 0.04 mol / liter trisodium citrate and 0.01 mol / liter potassium gold cyanide and adjusted to pH 6 with sodium hydroxide Except that the resin fine particles A were treated using a commercially available replacement gold plating solution containing gold potassium cyanide (IM-GoldST: manufactured by Nihon Kojun Kagaku Kagaku) instead of the resin until the average film thickness of the gold plating was 280 mm. Conductive particles 2 were produced in the same manner as particles 1.

(Conductive particles 3)
After gold plating, using a solution containing 0.03 mol / liter tetrasodium ethylenediaminetetraacetate and 0.04 mol / liter trisodium citrate, adjusted to pH 6 with sodium hydroxide, conditions at 60 ° C. for 1 minute Conductive particles 3 were produced in the same manner as the conductive particles 2 except that the surface nickel was removed.

(Conductive particles 4)
After gold plating, using a solution containing 0.04 mol / liter trisodium citrate and 0.01 mol / liter sodium cyanide, adjusted to pH 6 with sodium hydroxide, at 60 ° C. for 1 minute. The conductive particles 4 were produced in the same manner as the conductive particles 2 except that the nickel removal was performed.

(Conductive particles 5)
Conductive particles 5 were produced in the same manner as the conductive particles 1 except that 1 g of crosslinked polystyrene particles having an average particle size of 3.5 μm was used instead of 1 g of crosslinked polystyrene particles having an average particle size of 3.8 μm.

(Conductive particles 6)
Conductive particles 6 were produced in the same manner as the conductive particles 1 except that 1 g of crosslinked polystyrene particles having an average particle size of 3.0 μm was used instead of 1 g of crosslinked polystyrene particles having an average particle size of 3.8 μm.

(Conductive particles 7)
Conductive particles, except that 1 g of crosslinked polystyrene particles having an average particle size of 2.5 μm were used instead of 1 g of crosslinked polystyrene particles having an average particle size of 3.8 μm, and a φ1 μm membrane filter was used in place of the φ3 μm membrane filter. In the same manner as in Example 1, conductive particles 7 were produced.

(Conductive particles 8)
The conductive particles 8 were produced in the same manner as the conductive particles 1 except that the immersion gold plating time was adjusted so that the average thickness of the gold plating was 150 mm.

(Conductive particles 9)
In a solution containing 0.03 mol / liter tetrasodium ethylenediaminetetraacetate, 0.04 mol / liter trisodium citrate and 0.01 mol / liter sodium cyanide, adjusted to pH 6 with sodium hydroxide Conductive particles 9 were produced in the same manner as the conductive particles 1 except that the step of removing nickel on the surface at 60 ° C. for 1 minute was omitted.

(Conductive particles 10)
The conductive particles 10 were produced in the same manner as the conductive particles 1 except that the resin fine particles subjected to electroless nickel plating were filtered and then washed with 100 mL of pure water for 600 seconds.

(Conductive particles 11)
Commercially available conductive particles (AUEL00375AS: manufactured by Sekisui Chemical Co., Ltd.) obtained by applying nickel plating and gold plating with an average film thickness of 280 mm to a plastic having an average particle size of 3.75 μm were used as the conductive particles 11.

(Conductive particles 12)
The conductive particles 12 were made of commercially available conductive particles (AU203A: manufactured by Sekisui Chemical Co., Ltd.) obtained by applying nickel plating and gold plating with an average film thickness of 280 mm to a plastic having an average particle diameter of 3 μm.

(Conductive particles 13)
Commercially available conductive particles (AU203AF: manufactured by Sekisui Chemical Co., Ltd.) obtained by applying nickel plating and gold plating with an average film thickness of 280 mm to plastic having an average particle diameter of 3 μm were used as the conductive particles 13.

  For the conductive particles 1 to 13 obtained above, the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles by X-ray photoelectron spectroscopy (ESCA) was determined according to the method described below.

(Ni / Au ratio of conductive particle surface by ESCA)
Conductive particles 1 to 13 were respectively spread and spread on a planar conductive tape to obtain a measurement sample. With respect to the surface of the conductive particles in the Φ1.1 mm circle of this sample, the component ratio was observed by ESCA under the measurement conditions shown in Table 3. The number of measured particles was 10,000 or more.

  By the way, when conductive particles are measured by ESCA, components such as carbon and oxygen are detected in addition to nickel and gold. Since C and O are organic contaminants in the air, these components were ignored and the Ni / Au ratio was determined. For reference, Table 4 shows the component observation results (atomic%) for the conductive particles 11 and 12. In this case, the Ni / Au ratio of the conductive particles 11 is calculated as 0.62, and the Ni / Au ratio of the conductive particles 12 is calculated as 0.77.

  The results obtained are shown in Table 5. Table 5 also shows the particle size of the core particles and the history of the production of the conductive particles, the washing time after nickel plating, the average film thickness of gold plating, and the cleaning method after gold plating. In addition, about the average film thickness of gold plating, it computed with the following method.

(Average film thickness of gold plating)
The conductive particles were immersed in 50 vol% aqua regia to dissolve the gold plating, and then the resin particles were removed by filtration with a φ3 μm membrane filter, and the content of the gold element was measured by atomic absorption analysis. The thickness of the gold plating was converted from the obtained value and the particle size of the core particles, and this was used as the average thickness of the gold plating.

<Preparation of insulating coated conductive particles>
Using the conductive particles 1 to 13 obtained above, the insulating coated conductive particles 1 to 16 were produced according to the following procedure.

(Insulation coated conductive particles 1)
First, a reaction solution in which 8 mmol of mercaptoacetic acid was dissolved in 200 ml of methanol was prepared. Next, 1 g of conductive particles 1 was added to the reaction solution, and the mixture was stirred at room temperature for 2 hours using a three-one motor and a stirring blade having a diameter of 45 mm. After the reaction, the conductive particles were washed with methanol, and then filtered through a φ3 μm membrane filter to obtain 1 g of functional group-containing conductive particles having a carboxyl group on the surface.

  Next, a 30% by mass polyethyleneimine aqueous solution (trade name: 30% polyethyleneimine P-70 solution, manufactured by Wako Pure Chemical Industries, Ltd.) having a weight average molecular weight of 70,000 is diluted with ultrapure water to obtain 0.3% by mass polyethyleneimine. An aqueous solution was obtained. Particles with the polymer electrolyte adsorbed on the surface by adding 1 g of the above functional group-containing conductive particles to this 0.3 mass% polyethyleneimine aqueous solution, stirring for 15 minutes at room temperature (25 ° C.), and filtering through a φ3 μm membrane filter (Base particle) was obtained. The mother particles are mixed with 200 g of ultrapure water, stirred at room temperature (25 ° C.) for 5 minutes, filtered through a 3 μm membrane filter, and 200 g of ultrapure water is obtained by filtering the obtained particles. Was washed twice to remove polyethyleneimine not adsorbed on the mother particles.

  After removing polyethyleneimine, 1 g of mother particles can be obtained by diluting a colloidal silica dispersion (concentration 20 mass%, manufactured by Fuso Chemical Industries, trade name: Quatron PL-13, average particle size 130 nm) with ultrapure water. The mixture was mixed with 0.1% by mass silica dispersion, stirred at room temperature (25 ° C.) for 15 minutes, and filtered through a membrane filter having a diameter of 3 μm. After filtration, the mother particles are placed in 200 g of ultrapure water, stirred for 5 minutes at room temperature (25 ° C.), filtered through a 3 μm membrane filter, and the mother particles are washed twice with 200 g of ultrapure water on the membrane filter. Then, excess silica was removed. Thereafter, the mother particles were dried at 80 ° C. for 30 minutes, and then heated and dried at 120 ° C. for 1 hour to obtain insulating coated conductive particles 1.

(Insulation coated conductive particles 2)
Insulating coated conductive particles 2 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 2 were used instead of the conductive particles 1.

(Insulation coated conductive particles 3)
The insulating coated conductive particles 3 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 3 were used instead of the conductive particles 1.

(Insulation coated conductive particles 4)
Insulating coated conductive particles 4 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 4 were used instead of the conductive particles 1.

(Insulation coating conductive particles 5)
Insulating coated conductive particles 5 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 5 were used instead of the conductive particles 1.

(Insulation coated conductive particles 6)
Insulating coated conductive particles 6 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 6 were used instead of the conductive particles 1.

(Insulation coating conductive particles 7)
Insulating coated conductive particles 7 are formed in the same manner as the insulating coated conductive particles 1 except that the conductive particles 7 are used instead of the conductive particles 1 and a φ1 μm membrane filter is used instead of the φ3 μm membrane filter (Millipore). Produced.

(Insulation coated conductive particles 8)
Insulating coated conductive particles 8 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 8 were used instead of the conductive particles 1.

(Insulation coated conductive particles 9)
Insulating coated conductive particles 9 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 9 were used instead of the conductive particles 1.

(Insulation coated conductive particles 10)
Insulating coated conductive particles 10 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 10 were used instead of the conductive particles 1.

(Insulation coated conductive particles 11)
The insulating coated conductive particles 11 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 11 were used instead of the conductive particles 1.

(Insulation coated conductive particles 12)
Insulating coated conductive particles 12 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 12 were used instead of the conductive particles 1.

(Insulation coated conductive particles 13)
Insulating coated conductive particles 13 were produced in the same manner as the insulating coated conductive particles 1 except that the conductive particles 13 were used instead of the conductive particles 1.

(Insulation coating conductive particles 14)
A commercially available insulating coated conductive particle (AUEL00375AS-GD: Sekisui Chemical Co., Ltd.) coated with acrylic nanoparticles after nickel plating and gold plating with an average film thickness of 280 mm are applied to a plastic having an average particle diameter of 3.75 μm. Made of the insulating coated conductive particles 14.

(Insulation coating conductive particles 15)
A commercially available insulating coated conductive particle (AU203A-GD: manufactured by Sekisui Chemical Co., Ltd.) coated with acrylic nanoparticles after nickel plating and gold plating with an average film thickness of 280 mm are applied to a plastic having an average particle diameter of 3 μm. Was used as the insulating coated conductive particles 15.

(Insulation coating conductive particles 16)
A commercially available insulating coated conductive particle (AU203AF-GD: manufactured by Sekisui Chemical Co., Ltd.) coated with acrylic nanoparticles after nickel plating and gold plating with an average film thickness of 280 mm are applied to a plastic having an average particle diameter of 3 μm. Was used as the insulating coated conductive particles 16.

<Production of anisotropic conductive adhesive film>
Example 1
100 g of phenoxy resin (Union Carbide, trade name: PKHC), acrylic rubber (40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, 3 parts by mass of glycidyl methacrylate, weight average molecular weight: 850,000) 75 g was dissolved in 300 g of ethyl acetate to obtain a solution having a resin concentration of 30% by mass. To this solution, 300 g of liquid epoxy (Eboxy equivalent 185, manufactured by Asahi Kasei Epoxy Co., Ltd., trade name: Novacure HX-3941) containing a microcapsule-type latent curing agent was added and stirred to prepare a resin composition solution.

  4 g of the insulation-coated conductive particles 1 were mixed with 10 g of ethyl acetate and ultrasonically dispersed. The ultrasonic dispersion was carried out for 1 minute under conditions of 38 kHz and 400 W using “US107” (trade name, manufactured by Fujimoto Kagaku Co., Ltd.) in a 20 L beaker. The obtained dispersion was dispersed in the resin composition solution to obtain an anisotropic conductive adhesive composition. In addition, the dispersion liquid was prepared so that insulation coating electroconductive particle might be 21 volume% with respect to the anisotropic conductive adhesive composition whole quantity.

  The anisotropic conductive adhesive composition obtained above was applied on a separator (thickness 40 μm), which was a polyethylene-treated polyethylene terephthalate film, with a roll coater, dried at 90 ° C. for 10 minutes, and an anisotropic conductive film having a thickness of 25 μm. Adhesive film was prepared.

(Example 2)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 2 were used instead of the insulating coated conductive particles 1.

(Example 3)
An anisotropic conductive adhesive film was prepared in the same manner as in Example 1 except that the insulating coated conductive particles 3 were used instead of the insulating coated conductive particles 1.

Example 4
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 4 were used instead of the insulating coated conductive particles 1.

(Example 5)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 5 were used instead of the insulating coated conductive particles 1.

(Example 6)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 6 were used instead of the insulating coated conductive particles 1.

(Example 7)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 7 were used instead of the insulating coated conductive particles 1.

(Example 8)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 8 were used instead of the insulating coated conductive particles 1.

(Comparative Example 1)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 9 were used instead of the insulating coated conductive particles 1.

(Comparative Example 2)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 10 were used instead of the insulating coated conductive particles 1.

(Comparative Example 3)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 11 were used instead of the insulating coated conductive particles 1.

(Comparative Example 4)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 12 were used instead of the insulating coated conductive particles 1.

(Comparative Example 5)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 13 were used instead of the insulating coated conductive particles 1.

(Comparative Example 6)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 14 were used instead of the insulating coated conductive particles 1.

(Comparative Example 7)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 15 were used instead of the insulating coated conductive particles 1.

(Comparative Example 8)
An anisotropic conductive adhesive film was produced in the same manner as in Example 1 except that the insulating coated conductive particles 16 were used instead of the insulating coated conductive particles 1.

[Child particle coverage]
In the production of the anisotropic conductive adhesive composition, when the insulating coated conductive particles are ultrasonically dispersed in ethyl acetate, the insulator particles may be peeled off from the conductive particles. In order to investigate the degree of peeling of the insulator particles, the child particle coverage of the insulation coated conductive particles before and after ultrasonic dispersion was determined by image analysis of SEM. In addition, the child particle coverage was calculated from the following formula based on the number of the insulating child particles in the circle, in which a circle having a diameter half the diameter of the insulating coated conductive particles was drawn on the SEM image.
Coverage ratio of child particles (%) = ([projected area of insulator particles] × [number of insulator particles in measurement range] / [surface area of insulation coated conductive particles in measurement range]) × 100

[Mounting test]
Connection samples were prepared using the anisotropic conductive adhesive films of Examples 1 to 8 and Comparative Examples 1 to 8 obtained above, and the following insulation resistance measurement and conduction resistance measurement were performed on these connection samples. .

(Preparation of connection sample)
Using the produced anisotropic conductive adhesive film, a chip (1.7 mm × 17 mm, thickness: 0.5 mm) with gold bumps (area: 30 μm × 90 μm, space 10 μm, height: 15 μm, number of bumps: 362) And a glass substrate with an Al circuit (Geomatic, thickness: 0.7 mm) were connected as follows.

An anisotropic conductive adhesive film cut into a predetermined size (2 mm × 19 mm), and the surface opposite to the surface provided with the separator is an A1 circuit of a glass substrate with an Al circuit (thickness: 0.7 mm). Attached at 80 ° C. and 0.98 MPa (10 kgf / cm ² ) onto the surface of the glass substrate with an Al circuit toward the formed surface. After that, the separator is peeled off from the anisotropic conductive adhesive film attached to the glass substrate with Al circuit, and the gold bumps of the chip and the glass substrate with Al circuit are aligned through the anisotropic conductive adhesive film. went. Next, the surface on which the gold bumps of the chip are provided is directed to a surface opposite to the surface on which the glass substrate with an Al circuit of the anisotropic conductive adhesive film is attached, at 190 ° C., 40 g / bump, 10 seconds. This connection was made by heating and pressurizing under the conditions described above to obtain a connection sample.

(Insulation resistance measurement)
It is important that the anisotropic conductive adhesive film has a high insulation resistance between adjacent chip electrodes and a low conduction resistance between the facing chip electrodes / glass electrodes. Then, first, the insulation resistance measurement of each connection sample produced using the anisotropic conductive adhesive film of each example and each comparative example was performed. Twenty connection samples were prepared, and the insulation resistance between adjacent chip electrodes was measured. The minimum value of the insulation resistance and the yield (ratio of non-defective products) when the insulation resistance of 109 (Ω) or more was judged as a non-defective product were examined.

[Conduction resistance measurement]
Next, the conduction resistance of the connection body sample was measured. Fourteen connection samples were prepared, the conduction resistance between the chip electrode and the glass electrode facing each other was measured, and the average value was calculated to obtain the initial conduction resistance. Next, after each connected body sample was stored for 1000 hours under a moisture absorption condition of an air temperature of 85 ° C. and a humidity of 85%, the conduction resistance between the chip electrode and the glass electrode facing each other was measured, and the average value was calculated. The conduction resistance after storage under moisture absorption conditions (after the moisture absorption test) was determined.

  It was confirmed that the insulating coated conductive particles used in Examples 1 to 8 hardly peeled off the child particles before and after ultrasonic dispersion. In addition, it is conceivable that the reason is that since the ratio of Au on the surface of the conductive particles used for the production of the insulating coated conductive particles is high, thiol is easily chemically adsorbed on the particle surface and the insulator particles can be firmly bonded. In addition, according to the anisotropic conductive adhesive films of Examples 1 to 8, it is possible to sufficiently ensure insulation between narrow pitch electrodes and connect circuit electrodes with a high yield, and the connected electrodes absorb moisture. It was confirmed that a sufficiently low conduction resistance could be maintained after the test.

  On the other hand, it turned out that the anisotropic conductive adhesive film of Comparative Examples 1-8 tends to generate | occur | produce an insulation defect. Insulating coated conductive particles contained in the anisotropic conductive adhesive films of Comparative Examples 1 to 8 were produced using conductive particles having a nickel / gold ratio of more than 0.4 on the surface, and ultrasonic waves It was found that silica was easily peeled from the conductive particles by dispersion. Moreover, when the insulation coating electroconductive particle after mix | blending with an anisotropic conductive adhesive film was eluted with methyl ethyl ketone and SEM observation was carried out, it was also confirmed that the child particle has peeled.

  As described above, according to the present invention, an anisotropic conductive adhesive film that can sufficiently prevent poor connection in connection of circuit electrodes having a narrow pitch and a small area, and insulating coated conductive particles that can be realized. In addition, it is possible to provide a conductive particle capable of obtaining such insulating coated conductive particles and a method of manufacturing the same.

  6 ... Insulating particles, 8 ... Functional group-containing conductive particles, 10 ... Insulating coated conductive particles, 12 ... Resin composition, 20 ... First circuit member, 21 ... First substrate, 21a ... First substrate surface, 22 ... 1st circuit electrode, 30 ... 2nd circuit member, 31 ... 2nd board | substrate, 31a ... 2nd board | substrate surface, 32 ... 2nd circuit electrode.

Claims (10)

Conductive particles having a gold layer with an average film thickness of 300 mm or less formed on the nickel layer as an outermost layer,
Conductive particles characterized in that the elemental composition ratio (Ni / Au) of nickel and gold on the surface of the conductive particles by X-ray photoelectron spectroscopy is 0.4 or less.   The conductive particles according to claim 1, wherein a particle diameter of the conductive particles is 4.0 μm or less. The outermost layer surface of the conductive particles according to claim 1 or 2, and a compound having at least one group selected from the group consisting of a mercapto group, a sulfide group, and a disulfide group and a predetermined functional group, are contacted, Obtaining functional group-containing conductive particles in which the predetermined functional group is formed on the outermost surface of the conductive particles;
Contacting the functional group-containing conductive particles and the insulator particles;
A method for producing insulating coated conductive particles, wherein the surface of the functional group-containing conductive particles is coated with the insulator particles. The outermost layer surface of the conductive particles according to claim 1 or 2, and a compound having at least one group selected from the group consisting of a mercapto group, a sulfide group, and a disulfide group and a predetermined functional group, are contacted, Obtaining functional group-containing conductive particles in which the predetermined functional group is formed on the outermost surface of the conductive particles;
Contacting the functional group-containing conductive particles with a polymer electrolyte to obtain polymer electrolyte-coated conductive particles in which the surface of the functional group-containing conductive particles is coated with the polymer electrolyte;
Contacting the polymer electrolyte-coated conductive particles and the insulator particles;
A method for producing insulating coated conductive particles, wherein the surface of the functional group-containing conductive particles is coated with the polymer electrolyte and the insulator particles.   The method for producing insulating coated conductive particles according to claim 4, wherein the polymer electrolyte is a polyamine.   The method for producing insulating coated conductive particles according to claim 5, wherein the polyamine is polyethyleneimine.   The method for producing insulating coated conductive particles according to any one of claims 3 to 6, wherein the predetermined functional group is any one of a hydroxyl group, a carboxyl group, an alkoxyl group, and an alkoxycarbonyl group. .   The method for producing insulating coated conductive particles according to any one of claims 3 to 7, wherein the insulator particles are inorganic oxides.   The method for producing insulating coated conductive particles according to claim 8, wherein the inorganic oxide is silica particles. An anisotropic conductive adhesive composition comprising insulating coated conductive particles obtained by the method for producing insulating coated conductive particles according to any one of claims 3 to 9, and an insulating resin composition,
An anisotropic conductive adhesive film characterized by being formed into a film.

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