CN115298772A - Method for producing conductive composite particles, and adhesive film for circuit connection - Google Patents

Method for producing conductive composite particles, and adhesive film for circuit connection Download PDF

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Publication number
CN115298772A
CN115298772A CN202180021507.3A CN202180021507A CN115298772A CN 115298772 A CN115298772 A CN 115298772A CN 202180021507 A CN202180021507 A CN 202180021507A CN 115298772 A CN115298772 A CN 115298772A
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resin
conductive composite
particles
composite particles
conductive
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竹中启
富樫盛典
佐佐木洋
根岸芳典
松泽光晴
富坂克彦
山崎将平
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Resonac Holdings Corp
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Showa Denko KK
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/20—Compounding polymers with additives, e.g. colouring
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
    • C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
    • C08J3/07—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media from polymer solutions
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C08L25/06—Polystyrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form

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  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Conductive Materials (AREA)

Abstract

One aspect of the present invention is a method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles, the method including: a step of preparing a resin-containing solution containing conductive fine particles, a resin for constituting resin particles, and an organic solvent having compatibility with an aqueous solvent; a step of preparing an emulsion in which droplets of a resin-containing solution are dispersed in an aqueous solution by emulsification using fine pores; and a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.

Description

Method for producing conductive composite particles, and adhesive film for circuit connection
Technical Field
The present invention relates to a method for producing conductive composite particles. The present invention also relates to a conductive composite particle. The present invention also relates to an adhesive (adhesive) film for circuit connection, which contains the conductive composite particles.
Background
Typical examples of the method of assembling the liquid crystal driving IC on the Glass panel for liquid crystal display include 2 types of Chip-on-Glass (COG) assembly and Chip-on-Flex (COF) assembly. In the COG assembly, a liquid crystal driving IC is directly bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF assembly, 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.
As conductive particles used for an anisotropic conductive adhesive, conductive composite particles in which a metal layer is formed on the surface of a resin particle are mainly used.
Patent document 1 discloses a composite particle including: resin particles; and a plurality of tin-doped indium oxide particles which are embedded in the resin particles and have an average particle diameter of less than 1/2 of the particle diameter of the resin particles. Patent document 1 describes that the composite particles have a structure in which ITO (Indium Tin Oxide) particles are embedded in resin particles, and therefore, the composite particles can be used for a transparent conductive material that requires transparency while preventing damage and corrosion of a conductive layer that may occur in the composite particles.
Prior art documents
Patent document
Patent document 1: japanese laid-open patent publication No. 2012-216294
Disclosure of Invention
Technical problem to be solved by the invention
In recent years, in the field of electronic devices such as liquid crystal displays, personal computers, tablet PCs, and smart phones, electrode circuits have been made finer and smaller in area, and further, miniaturization of conductive particles has been demanded. In the technique of patent document 1, further improvement in conductivity is also required from the viewpoint of miniaturization. Therefore, a new technique capable of improving the conductivity of the conductive composite particles is desired.
Here, as a method for improving the conductivity, it is conceivable to contain conductive fine particles at a high concentration in resin particles that become cores of the conductive composite particles. That is, it is considered that by containing the conductive fine particles at a high concentration in the resin particles, conduction can be performed by the conductive fine particles contained in the resin particles, and conductivity can be improved. However, when conductive fine particles containing conductive fine particles in a high concentration in resin particles are prepared by a conventional preparation method, problems such as precipitation of particles or aggregation of resin particles due to the weight of the conductive fine particles occur, and the preparation is difficult. In particular, if the particle diameter of the conductive composite particles is to be reduced, such a problem is conspicuously caused.
Accordingly, an object of the present invention is to provide a method capable of producing conductive composite particles containing conductive fine particles at a high concentration.
Means for solving the technical problem
One embodiment of the present invention is as follows.
A method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles, the method comprising:
a step of preparing a resin-containing solution containing conductive fine particles, a resin for forming the resin particles, and an organic solvent having compatibility with an aqueous solvent;
a step of preparing an emulsion in which droplets of a resin-containing solution are dispersed in an aqueous solution by emulsification using fine pores; and
and a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
A conductive composite particle comprising a resin particle and a conductive fine particle contained in the resin particle, wherein the content of the conductive fine particle in the conductive composite particle is 40% or more.
An adhesive film for circuit connection, comprising the above-mentioned conductive composite particles and a binder resin.
Effects of the invention
According to the present invention, a method capable of producing conductive composite particles containing conductive fine particles at a high concentration can be provided.
Drawings
Fig. 1 is a schematic cross-sectional view showing an example of the configuration of the conductive composite particles according to the present embodiment.
Fig. 2 is a schematic cross-sectional view showing an example of the configuration of the conductive composite particles according to the present embodiment.
Fig. 3 is a schematic cross-sectional view showing an example of the configuration of the adhesive film for circuit connection according to the present embodiment.
Fig. 4A is a schematic cross-sectional view showing a method for manufacturing a connection structure of a circuit member using the adhesive film for circuit connection according to the present embodiment.
Fig. 4B is a schematic cross-sectional view showing a method for manufacturing a connection structure of a circuit member using the adhesive film for circuit connection according to the present embodiment, in addition to fig. 4A.
Fig. 5 is a schematic diagram showing a configuration example of the membrane emulsification system 12 used in the example.
Fig. 6A is a conceptual diagram showing the state of the fine particle-containing resin solution 15 before emulsification in the example.
Fig. 6B is a conceptual diagram showing the state of the fine particle-containing resin solution 15 at the time of emulsification or after emulsification in the example.
Fig. 7A is a conceptual diagram illustrating a state in which the organic solvent 151 elutes from the microparticle-containing emulsified particles 170 to form microparticle-containing resin particles 171 in the example.
Fig. 7B is a schematic diagram illustrating a step of heating the aqueous solution 16 by the heater 115 to promote elution of the organic solvent 151 in the example.
Fig. 8A is a conceptual diagram illustrating a state in which the polymer 150 in the fine particle-containing resin particle 171 is crosslinked by the crosslinking agent 152 in the example.
Fig. 8B is a conceptual diagram illustrating a step of heating the aqueous solution 16 by the heater 115 to cause a crosslinking reaction.
Fig. 9A is an SEM photograph showing conductive composite particles E3 produced in example 3.
Fig. 9B is an EDX spectrum of the conductive composite particle E3 produced in example 3.
Detailed Description
One aspect of the present embodiment is a method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles, the method including: a step of preparing a resin-containing solution containing conductive fine particles, a resin for forming the resin particles, and an organic solvent having compatibility with an aqueous solvent; a step of preparing an emulsion in which droplets of a resin-containing solution are dispersed in an aqueous solution by emulsification using fine pores; and a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
With the configuration of the present embodiment, a method capable of producing conductive composite particles containing conductive fine particles at a high concentration can be provided.
Further, one embodiment of the present invention is a conductive composite particle including a resin particle and a conductive fine particle contained in the resin particle, wherein a content of the conductive fine particle in the conductive composite particle is 40% or more.
The configuration of the present embodiment can provide conductive composite particles having excellent conductivity. Therefore, even when the conductive composite particles are miniaturized, sufficient conductivity can be maintained, and the conduction reliability of the adhesive film for circuit connection can be ensured.
The present embodiment will be described in detail below.
[ method for producing conductive composite particles ]
The production method according to the present embodiment relates to a method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles.
Fig. 1 is a cross-sectional view showing an example of the structure of the conductive composite particles obtained in the present embodiment. As shown in fig. 1, the conductive composite particle 10 includes a resin particle 101 and a plurality of conductive fine particles 102 contained in the resin particle 101.
The content of the conductive fine particles in the conductive composite particles may be 40 mass% or more. When the content is 40 mass% or more, the conductive fine particles are present in a high concentration in the conductive composite particles, and the conductive fine particles are in contact with each other to allow efficient conduction. The content of the conductive fine particles in the conductive composite particles may be 45 mass% or more, or may be 50 mass% or more. The content of the conductive fine particles in the conductive composite particles may be 80 mass% or less, 70 mass% or less, or 60 mass% or less. The content ratio in the present embodiment can be obtained as follows: the mass concentration of the elements constituting the conductive fine particles was measured by quantitative analysis based on SEM-EDX.
(resin-containing solution preparation Process)
The production method according to the present embodiment may include a step of preparing a resin-containing solution containing conductive fine particles, a resin for constituting the resin particles, and an organic solvent having compatibility with an aqueous solvent.
The conductive fine particles are fine particles having conductivity. Examples of the conductive fine particles include metal fine particles. The metal fine particles are particles made of metal. The metal fine particles preferably contain at least one metal selected from the group consisting of gold, silver, copper, platinum, zinc, iron, palladium, nickel, tin, chromium, titanium, aluminum, cobalt, germanium, cadmium, and alloys of these. The metal fine particles may be used alone in 1 kind, or in combination of 2 or more kinds.
From the viewpoint of easily developing good conductivity of the conductive composite particles, the average particle diameter of the conductive fine particles may be 10nm or more and 500nm or less, 20nm or more and 300nm or less, or 30nm or more and 100nm or less. The average particle diameter of the conductive fine particles may be 1/10 or less, 1/50 or less, or 1/100 or less of the average particle diameter of the conductive composite particles. Average particle diameter (D) of conductive fine particles 50 ) For example, the particle size distribution can be calculated from a volume-based particle size distribution measured by using a laser diffraction particle size distribution measuring apparatus.
The resin particles may be made of, for example, a polyethylene resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a phenol resin, an epoxy resin, or a mixture thereof. Among these, a polyethylene-based resin is preferably used. The polyethylene resin is preferably a polyacrylic resin, a polyolefin resin, or a polystyrene resin. These can be used alone in 1 kind, also can be combined with 2 or more kinds to use. The resin used to form the resin particles, i.e., the resin added to the resin-containing solution to form the resin particles, may be a monomeric resin compound or may be a polymeric polymer (also referred to as a base polymer).
The polyacrylic resin can be obtained by polymerization of a (meth) acrylic monomer, for example. Examples of the (meth) acrylic monomer include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and diethylaminoethyl methacrylate. These monomers may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The polyacrylic resin may be a copolymer obtained by copolymerization of a (meth) acrylic monomer with another monomer. Examples of the other monomer include olefin monomers such as ethylene, propylene, isobutylene, and butadiene; glycol esters of (meth) acrylic acid such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl esters such as vinyl acetate and vinyl butyrate; n-alkyl-substituted (meth) acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-methylmethacrylamide, and N-ethylmethacrylamide; nitriles such as acrylonitrile and methacrylonitrile; polyfunctional monomers such as alkanediol di (meth) acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, and trimethylolpropane triacrylate; styrene monomers such as styrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene, and alpha-methylstyrene. These other monomers may be used alone in 1 kind, or may be used in combination in 2 or more kinds.
The polyolefin-based resin can be obtained by, for example, polymerizing an olefin-based monomer (e.g., olefin). Examples of the olefin monomer include ethylene, propylene, isobutylene, and butadiene. These olefin monomers may be used alone in 1 kind, or may be used in combination of 2 or more kinds. The polyolefin-based resin may be a copolymer obtained by copolymerizing an olefin-based monomer with another monomer. Examples of the other monomer include glycol esters of (meth) acrylic acid such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl esters such as vinyl acetate and vinyl butyrate, and N-alkyl-substituted (meth) acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-methylmethacrylamide, and N-ethylmethacrylamide; nitriles such as acrylonitrile and methacrylonitrile; polyfunctional monomers such as alkanediol di (meth) acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, and trimethylolpropane triacrylate; (meth) acrylic monomers such as acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and diethylaminoethyl methacrylate; styrene monomers such as styrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene, and α -methylstyrene. These other monomers can be used alone in 1, also can be used simultaneously more than 2.
Polystyrene-based resins can be obtained, for example, by polymerization of styrene-based monomers. Examples of the styrene monomer include styrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene, and α -methylstyrene. The styrene-based monomers may be used alone in 1 kind or in combination of 2 or more kinds. The polystyrene-based resin may be a copolymer obtained by copolymerizing a styrene-based monomer with other monomers. Examples of the other monomer include olefin monomers such as ethylene, propylene, isobutylene, and butadiene; glycol esters of (meth) acrylic acid such as ethylene glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl esters such as vinyl acetate and vinyl butyrate, and N-alkyl-substituted (meth) acrylamides such as N-methylacrylamide, N-ethylacrylamide, N-methylmethacrylamide, and N-ethylmethacrylamide; nitriles such as acrylonitrile and methacrylonitrile; polyfunctional monomers such as alkanediol di (meth) acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, and trimethylolpropane triacrylate; (meth) acrylic monomers such as acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, diethylaminoethyl methacrylate, and the like. These other monomers may be used alone in 1 kind, or may be used in combination in 2 or more kinds.
The resin-containing solution may further comprise a crosslinking agent for crosslinking the base polymer. The crosslinking agent is not particularly limited, and a known crosslinking agent can be suitably used. Examples of the crosslinking agent include compounds having at least 2 unsaturated bonds (e.g., vinyl groups). Examples of such a compound include divinylbenzene, divinylnaphthalene, divinyl ether, divinylsulfone, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1, 3-butanediol dimethacrylate, 1, 6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate and polypropylene glycol dimethacrylate. The crosslinking agent can be used alone in 1, also can be combined with more than 2 to use.
The resin-containing solution can contain a reaction initiator for polymerization and/or crosslinking, as necessary. The reaction initiator is not particularly limited, and can be appropriately selected and used according to the resin or the crosslinking agent contained in the resin-containing solution. The reaction initiator may have thermal responsiveness or photo responsiveness from the viewpoint of easy operability of the reaction. The reaction initiator is preferably added to the resin-containing solution, but is not particularly limited thereto, and may be added to the aqueous solution, or may be added to both the resin-containing solution and the aqueous solution. In general, a large amount of reaction initiator is used for both the polymerization reaction and the crosslinking reaction. Examples of the reaction initiator include organic peroxides such as benzoyl peroxide, lauroyl peroxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, 3, 5-trimethylhexanoyl peroxide, ethyl tert-butylperoxy-2-hexanoate, and di (tert-butyl) peroxide; azo compounds such as 2,2' -azobisisobutyronitrile, 1' -azobiscyclohexanecarbonitrile, and 2,2' -azobis (2, 4-dimethylvaleronitrile). The reaction initiator may be used alone in 1 kind, or may be used in combination of 2 or more kinds.
From the viewpoint of uniformly dispersing the conductive fine particles in the resin-containing solution, the resin-containing solution may contain a dispersant having an action of dispersing the conductive fine particles in an organic solvent. The uniform dispersion in the resin-containing solution is associated with the uniform dispersion phase in the conductive composite particles, and as a result, the conductivity of the conductive composite particles can be improved. As the dispersant, for example, a commercially available dispersant can be suitably used. Examples of the dispersant include ESLEAM (registered trademark, NOF CORPORATION), MEGAFACE (registered trademark, DIC CORPORATION), MALIALIM (registered trademark, NOF CORPORATION), and POLYFLOW (registered trademark, KYOEISHA CHEMICAL co., LTD). The dispersant may be used alone in 1 kind, or may be used in combination of 2 or more kinds.
The organic solvent is not particularly limited as long as it is compatible with an aqueous solvent and can dissolve the resin used. The organic solvent can be appropriately selected in consideration of the resin used and the compatibility with the aqueous solvent. Examples of the organic solvent include Tetrahydrofuran (THF), methyl Ethyl Ketone (MEK), acetone, methanol, ethanol, N-propanol, isopropanol, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and a mixture thereof. Among them, ethanol, n-propanol, isopropanol, acetone, or THF is preferable. The organic solvent can be used alone in 1 kind, can also be combined with more than 2 kinds.
(emulsification Process)
Next, the production method according to the present embodiment may include a step of preparing an emulsion in which droplets of the resin-containing solution are dispersed in the aqueous solution by emulsification using the fine pores. Specifically, the emulsion may be prepared by releasing the resin-containing solution into an aqueous solution through fine pores.
Examples of the emulsification method using the fine pores include a membrane emulsification method using a porous membrane and a microchannel emulsification method, but are not particularly limited thereto. The membrane emulsification method (SPG membrane emulsification method) using a Porous membrane is an emulsification method in which an oil phase is dispersed in an aqueous phase through pores of a Porous membrane (for example, shirasu Porous Glass: SPG (Shirasu Porous Glass) membrane) while applying a pressure to the oil phase. By using this method, an emulsion having a uniform particle diameter can be obtained. The microchannel emulsification method is an emulsification method in which an oil phase is pressurized using a plurality of plate groove type microchannel arrays or through-hole type microchannel arrays, and the oil phase is dispersed in an aqueous phase through pores of the microchannels. The membrane emulsification method and the microchannel emulsification method can produce emulsified droplets having a smaller particle size distribution than other emulsification methods. It is considered that the particle diameter of the emulsified liquid droplets produced by the membrane emulsification method is about 3 times the pore diameter of the fine pores of the filter, and the particle diameter can be adjusted by changing the pore diameter.
Examples of the aqueous solvent include water and a mixed medium of water and a water-soluble solvent (e.g., a lower alcohol).
The aqueous solution may contain a surfactant or a dispersion stabilizer in order to stably form droplets.
Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a zwitterionic surfactant. Examples of the anionic surfactant include fatty acid oils such as sodium oleate and potassium castor oil salt, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzene sulfonate such as sodium dodecylbenzenesulfonate, alkylnaphthalene sulfonate, alkane sulfonate, dialkyl succinate sulfonate such as sodium dioctyl succinate, alkenyl succinate (dipotassium salt), alkyl phosphate ester salts, formalin sulfonate condensate, polyoxyethylene alkylphenyl ether sulfate ester salts such as polyoxyethylene lauryl ether sodium sulfate, polyoxyethylene alkyl sulfate ester salts such as polyoxyethylene lauryl ether sodium sulfate, and lauryl sulfate triethanol. Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride. Examples of the nonionic surfactant include hydrocarbon nonionic surfactants such as polyethylene glycol alkyl ethers, polyethylene glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines and amides, polyether-modified silicon nonionic surfactants such as silicon polyoxyethylene adducts and polyoxypropylene adducts, and fluorine nonionic surfactants such as perfluoroalkyl glycols. Examples of the zwitterionic surfactant include a hydrocarbon surfactant such as lauryl dimethyl amine oxide, a phosphate surfactant, and a phosphite surfactant. Among the above surfactants, anionic surfactants are also preferable from the viewpoint of dispersion stability during the reaction. The surfactant may be used alone in 1 kind, or may be used in combination with 2 or more kinds.
The dispersion stabilizer is not particularly limited, but examples thereof include polyvinyl alcohol, polycarboxylic acid, cellulose (hydroxyethyl cellulose, carboxymethyl cellulose, etc.), and polyvinylpyrrolidone. In addition, an inorganic water-soluble polymer compound such as sodium tripolyphosphate can also be used. Among them, polyvinyl alcohol or polyvinyl pyrrolidone is preferable.
As described above, the aqueous solution may contain a reaction initiator for the polymerization reaction and/or the crosslinking reaction, if necessary.
(conductive composite particle formation step)
Next, the manufacturing method according to the present embodiment may include a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
The reaction temperature can be appropriately selected according to the kind of the resin or the reaction initiator to be added. The reaction temperature can be 30-110 ℃ or 50-100 ℃. After the reaction is completed, the aqueous solution can be removed from the reaction solution by centrifugation, if necessary. The obtained conductive composite particles can be washed with water, a solvent, or the like, and then dried, if necessary.
The production method according to the present embodiment may further include a step of heating the aqueous solution to promote elution of the organic solvent into the aqueous solution before the polymerization reaction and/or the crosslinking reaction occurs. The particle size of the resin particles can be reduced by eluting the organic solvent into the aqueous solution.
Through the above steps, conductive composite particles containing conductive fine particles at a high concentration can be efficiently produced.
As a method other than the production method according to the present embodiment, which can be considered when producing the conductive composite particles, for example, a method of emulsifying a resin solution containing conductive fine particles by an emulsifier such as a homogenizer or an ultrasonic processor can be considered. However, when conductive composite particles containing conductive fine particles at a high concentration are produced by such a conventional method, problems such as precipitation of the particles or agglomeration of resin particles due to the weight of the conductive fine particles occur. In particular, if the particle diameter of the conductive composite particles is to be reduced, such a problem is conspicuously caused. Further, the shearing force applied to the resin solution is not uniform, and therefore the particle size distribution of the produced conductive composite particles tends to be extremely large.
In the production method according to the present embodiment, it is preferable to use a polymer after polymerization, which is a base polymer, as the resin to be added to the resin-containing solution. By using the base polymer as the resin, conductive composite particles containing conductive fine particles at a high concentration can be produced with a smaller particle diameter. The reason for this will be described below. For example, as a method for producing resin particles by a membrane emulsification method, a method of emulsifying and polymerizing a resin solution film containing a monomer is reported in j.appl.polymer sci., vol.51, no.1, pp.1-11 (1994). The particle diameter of the emulsion droplets before polymerization prepared by this method is generally about three times the pore diameter of the filter, and the particle diameter of the resin particles obtained after polymerization is almost the same as the particle diameter of the emulsion droplets before polymerization. Therefore, when resin particles having a small particle size are produced using a monomer as a material, a filter having a small pore size needs to be used. However, it is difficult to manufacture a filter having a small pore diameter, and pressure resistance generated when a monomer flows through the pores becomes large. Therefore, in the method of emulsifying a monomer film, it is sometimes difficult to produce fine resin particles. On the other hand, in the production method according to the present embodiment, when the base polymer is used as the resin to be added to the resin-containing solution, the organic solvent contained in the emulsified droplets is eluted into the aqueous solution after the membrane emulsification. In addition, the elution can be promoted by heating. Then, the polymer in the emulsified liquid droplets aggregates and becomes particles as the dissolution proceeds, and therefore resin particles smaller than the pore diameter of the filter can be produced. Further, since small resin particles can be formed without using a filter having a small pore diameter, there are advantages in that: when the resin-containing solution is emulsified, clogging due to fine particles is less likely to occur. In addition, the following advantages are provided: the particle diameter of the resin particles can be controlled by adjusting the concentration of the resin, not just the pore diameter of the filter. In addition, when the resin-containing solution is emulsified as described above, a microchannel may be used. Emulsification using microchannels is characterized by the ability to produce emulsified droplets of very uniform size. However, since a minute flow path of a microchannel is used, clogging of the flow path due to a material or a product is likely to occur. Therefore, when a resin-containing solution in which a base polymer is dissolved in an organic solvent is used as a material, resin particles having a smaller flow path width than the microchannel can be produced. Therefore, there is an advantage that the flow path is not easily clogged. For the above reasons, it is preferable to use a polymer after polymerization, which is a base polymer, as the resin to be added to the resin-containing solution. Examples of the base polymer include, as described above, polyethylene-based resins, polyimide-based resins, polyamide-based resins, polyamideimide-based resins, phenolic-based resins, epoxy-based resins, and mixtures thereof. Among them, the base polymer is preferably a polyethylene resin. As the polyethylene resin, a polyacrylic resin, a polyolefin resin, a polystyrene resin, or a mixture thereof can be preferably used. The base polymer may be used alone in 1 kind, or may be used in combination with 2 or more kinds.
In one embodiment, the resin-containing solution may contain the base polymer as a resin and a crosslinking agent for crosslinking the base polymer. By including the crosslinking agent, conductive composite particles which crosslink the base polymer and have appropriate strength/hardness can be obtained. The crosslinking agent is not particularly limited, and examples thereof include the compounds having at least 2 unsaturated bonds (e.g., vinyl group).
[ conductive composite particles ]
Fig. 1 is a cross-sectional view showing an example of the configuration of the conductive composite particles according to the present embodiment. As shown in fig. 1, the conductive composite particle 10 includes a resin particle 101 and a plurality of conductive fine particles 102 contained in the resin particle 101.
The content of the conductive fine particles in the conductive composite particles may be 40 mass% or more, or may be in the above range. The content in the present embodiment can be calculated by measuring the weight concentration of the elements constituting the conductive fine particles by quantitative analysis using SEM-EDX and calculating the content from the result.
As shown in fig. 2, the conductive composite particle according to the present embodiment may include a conductive layer 105 as an outermost layer. Fig. 2 is a schematic cross-sectional view showing the conductive composite particle 11 having the conductive layer 105 on the resin particle 101 as the outermost layer. The conductive layer 105 can cooperate with the conductive fine particles 102 present in the resin particles 101 to further improve the conductivity of the conductive composite particles. Further, since the strength of the conductive composite particles can be increased, damage to the conductive composite particles due to pressure applied during pressure bonding can be suppressed. Even if the conductive layer is broken, the portions of the conductive layer separated by the breakage are electrically connected through the conductive fine particles in the resin particles, and therefore, the decrease in conductivity is less likely to occur. The conductive layer may be a single layer or 2 or more layers.
The conductive layer is preferably a metal layer comprising a metal. The metal constituting the metal layer is not particularly limited, but examples thereof include gold, silver, copper, platinum, zinc, iron, tin, aluminum, cobalt, indium, palladium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof.
The method of forming the conductive layer is not particularly limited, and examples thereof include an electroless plating method, an electroplating method, a physical vapor deposition method, and a method of applying a slurry containing a metal powder to the surface of the resin particles. As the physical vapor deposition method, for example, vacuum vapor deposition, ion plating, or ion sputtering can be used. As a method for forming the conductive layer, an electroless plating method is preferable.
From the viewpoint of miniaturization, the thickness of the conductive layer may be 10nm or more and 300nm or less, or 50nm or more and 200nm or less. The thickness of the conductive layer can be determined, for example, as follows: the cross section of the conductive composite particles was observed using a Transmission Electron Microscope (TEM).
From the viewpoint of miniaturization, the average particle diameter of the conductive composite particles may be 0.1 μm or more and 20 μm or less, 0.5 μm or more and 10 μm or less, or 1.0 μm or more and 5.0 μm or less.
The CV value of the particle diameter (diameter) of the conductive composite particles may be 15% or less, 10% or less, 7% or less, or 5% or less. When the CV value of the conductive composite particles is 15% or less, the electrical connection reliability can be further improved. In the present specification, the CV value (coefficient of variation) of the particle diameter refers to a ratio of a standard deviation of the particle diameter to an average value of the particle diameter expressed by percentage.
[ adhesive film for Circuit connection ]
The adhesive film for circuit connection according to the present embodiment includes the conductive composite particles and a binder resin. Fig. 3 is a schematic cross-sectional view showing an example of the configuration of the adhesive film for circuit connection according to the present embodiment. The circuit connecting adhesive film 40 includes an insulating adhesive resin 20 and conductive composite particles 10 uniformly dispersed in the adhesive resin 20.
As the binder resin, for example, a thermosetting resin, a curing agent, a thermosetting resin composition containing a film-forming polymer, or the like can be used.
The thermosetting resin is not particularly limited, but an epoxy resin is preferably used from the viewpoint of heat resistance. As the epoxy resin, various epoxy compounds having 2 or more glycidyl groups in the molecule can be used, and examples thereof include bisphenol type epoxy resins, novolak type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, alicyclic type epoxy resins, glycidyl amine compounds, glycidyl ether compounds and glycidyl ester compounds. The thermosetting resin may be used alone in 1 kind, or may be used in combination with 2 or more kinds.
As the epoxy resin, impurity ions (Na) are added + 、Cl - Etc.) or hydrolyzable chlorine to 300ppm or less, electromigration is easily prevented.
The curing agent is not particularly limited, but for example, a latent curing agent can be used.
Examples of the latent curing agent include imidazole compounds, hydrazide compounds, boron trifluoride-amine complexes, sulfonium salts, aminimides, polyamine salts, and dicyanodiamines.
The film-forming polymer is not particularly limited as long as it can contribute to the film shape of the adhesive film for circuit connection. Examples of the film-forming polymer include thermoplastic resins such as phenoxy resins, polyester resins, and polyamide resins.
In order to increase stress after bonding or to improve adhesiveness (adhesiveness), butadiene rubber, acrylic rubber, styrene-butadiene rubber, silicone rubber, or the like may be mixed in the binder resin.
An inorganic filler can be blended in the binder resin. As the inorganic filler, for example, a filler formed of silica, magnesia, bentonite, alumina, or boron nitride can be used.
In addition, in the binder resin, a radical polymerizable resin and a photocurable resin composition containing a photopolymerization initiator such as an organic peroxide can be used instead of the thermosetting resin and the curing agent.
The adhesive film for circuit connection can be produced, for example, as follows. First, if necessary, a thermosetting resin composition containing an epoxy resin, an acrylic rubber, a latent curing agent, and a film-forming polymer is dissolved or dispersed in an organic solvent and liquefied to prepare a composition for forming an adhesive resin. Next, the conductive composite particles are dispersed in the binder resin-forming composition to prepare a liquid binder composition for circuit connection. The organic solvent may be one which can dissolve the resin component and has a boiling point of 50 to 150 ℃ at normal pressure. Examples of such an organic solvent include toluene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, and butyl acetate.
The liquid adhesive composition for circuit connection can be used as it is for connecting circuit members, but is preferably used by being formed into a film. The adhesive film for circuit connection can be produced by: the adhesive composition for circuit connection is applied to a releasable film, and after removing the organic solvent at a temperature equal to or lower than the activation temperature of the curing agent, the adhesive composition is peeled from the releasable film. In this case, the adhesive film for circuit connection can also be referred to as a layer provided on the releasable film and containing the conductive composite particles and a binder resin in which the conductive composite particles are dispersed (i.e., a binder resin layer containing the conductive composite particles). As the mold releasing film, a resin film such as a fluororesin film, a polyethylene terephthalate film, or a polyolefin film is suitably used. The adhesive film for circuit connection is simple and convenient from the viewpoint of workability.
The adhesive film for circuit connection of the above embodiment may be an anisotropic conductive adhesive film, or may be a conductive adhesive film having no anisotropic conductivity.
[ connecting Structure ]
The connection structure of the circuit member according to the present embodiment includes: a 1 st circuit component having a 1 st circuit electrode formed on a main surface of a 1 st circuit substrate; a 2 nd circuit component having a 2 nd circuit electrode formed on a main surface of a 2 nd circuit substrate; and a connecting portion interposed between the 1 st circuit member and the 2 nd circuit member. The 2 nd circuit member is disposed such that the 2 nd circuit electrode is opposed to the 1 st circuit electrode. The connection portion includes the conductive composite particle according to the present embodiment.
Fig. 4A and 4B are schematic cross-sectional views showing a method for manufacturing a connection structure of a circuit member using the adhesive film for circuit connection according to the present embodiment.
First, as shown in fig. 4A, the 1 st circuit board 4 on which the 1 st circuit electrode 5 is formed and the 2 nd circuit board 6 on which the 2 nd circuit electrode 7 is formed are prepared, and the adhesive film 40 for circuit connection is disposed therebetween. At this time, the position is adjusted so that the 1 st circuit electrode 5 and the 2 nd circuit electrode 7 face each other. Then, the 1 st circuit board 4 and the 2 nd circuit board 6 are laminated while applying pressure and heat in a direction in which the 1 st circuit electrode 5 and the 2 nd circuit electrode 7 face each other, thereby obtaining a connection structure 42 shown in fig. 4B. The connection structure 42 is electrically connected by a cured product of the circuit-connecting adhesive film 40.
Examples of the 1 st circuit board 4 and the 2 nd circuit board 6 include a glass substrate, a tape substrate such as polyimide, a bare chip such as a driver IC, and a rigid package substrate.
Examples
Hereinafter, the present embodiment will be described more specifically by way of examples. However, the present embodiment is not limited to the following examples.
Example 1: production of conductive composite particles E1
(Process a: preparation of suspension of conductive Fine particles)
Nickel fine particles (made by EMJapan Co., ltd., average particle diameter: 40 nm) and a dispersant (ESLEAM (registered trademark) C-2093I, made by NOF CORPORATION) were added to tetrahydrofuran, which is an organic solvent compatible with water, and mixed by a bead mill (product name: MSC-50, NIPPON COKE & ENGINEERING CO., LTD) using zirconia particles (φ 0.015 mm) to obtain a suspension. Further, since the particle size of the nickel fine particles is very small, when the nickel fine particles are added to an organic solvent without a dispersant, aggregates having a size of tens of μm are formed. Therefore, in example 1, from the viewpoint of preventing aggregation of the nickel fine particles and well dispersing the nickel fine particles, the above-mentioned dispersant was added, and further, a strong dispersing treatment using a bead mill was performed.
The content of the nickel fine particles in the suspension was 20 mass%. The content of the dispersant was 2 parts by mass with respect to 100 parts by mass of the nickel fine particles. Mixing using a bead mill was carried out for 60 minutes.
(Process b: preparation of Fine particle-containing resin solution)
To the suspension of conductive fine particles prepared in the process a, polystyrene (product name: polystyrene (MW 800-5,000), manufactured by polysciences inc), divinylbenzene and benzoyl peroxide were added and stirred to prepare a fine particle-containing resin solution. Further, divinylbenzene acts as a crosslinking agent for polystyrene, and benzoyl peroxide acts as a polymerization initiator. Agitation of the solution was carried out for 15 minutes using an ultrasonic cleaner.
The content of polystyrene in the microparticle-containing resin solution was 10% by mass. The content of divinylbenzene in the fine particle-containing resin solution was 3 mass%. The content of benzoyl peroxide in the fine particle-containing resin solution was 0.04% by mass.
(step c: preparation of aqueous solution)
Polyvinyl alcohol was added to pure water and stirred to prepare an aqueous solution. Polyvinyl alcohol functions as a dispersion stabilizer to stabilize the emulsion. Stirring of the solution was carried out for 15 minutes using a magnetic stirrer.
The content of polyvinyl alcohol in the aqueous solution was 1%.
(step d: emulsification of the fine particle-containing resin solution)
The fine particle-containing resin solution prepared in step b was emulsified using the membrane emulsification system 12 shown in fig. 5. The method will be described below with reference to fig. 5 to 8.
Fig. 5 is a schematic diagram for explaining the configuration of the membrane emulsification system 12. The membrane emulsification system 12 comprises: a syringe 110 for holding the fine particle-containing resin solution 15; a liquid feed pump (not shown); an aqueous solution holding container 111 for holding an aqueous solution 16; a filter 112 having pores and held in the aqueous solution holding container 111; a connection tube 113 connecting the syringe 110 and the filter 112; a stirring tool 114 disposed at the bottom of the aqueous solution holding container 111 for causing the aqueous solution 16 to flow; and a heater 115 for heating the aqueous solution 16. The fine particle-containing resin solution 15 contained in the syringe 110 is sent into the filter 112 through the connection tube 113 by the liquid sending pump. The filter 112 has numerous pores on the surface, and the fine particle-containing resin solution 15 is sprayed from the pores into the aqueous solution 16 in the aqueous solution holding container 111 to form an emulsion. The emulsion is of the oil-in-water type.
Specifically, in the present example, a syringe pump (flow rate: 15 mL/h) was used as the liquid feeding pump, a PTFE tube was used as the connecting tube 113, a porous glass membrane (pore size: 3 to 10 μm) was used as the filter, and an overhead stirrer (rotation rate: 500 rpm) was used as the stirring tool 114. The amount of the liquid to be fed to the fine particle-containing resin solution 15 was 10mL, and the amount of the aqueous solution was 300mL.
Fig. 6A is a conceptual diagram showing a state of the fine particle-containing resin solution 15 before emulsification. Fig. 6B is a conceptual diagram showing the state of the fine particle-containing resin solution 15 during or after emulsification. The microparticle-containing resin solution 15 before emulsification contains a polymer 150, an organic solvent 151, a crosslinking agent 152, microparticles 153, a dispersant, and a reaction initiator. In this example, as described above, polystyrene was used as the polymer 150, tetrahydrofuran was used as the organic solvent 151, divinylbenzene was used as the crosslinking agent 152, nickel fine particles were used as the fine particles 153, and benzoyl peroxide was used as the reaction initiator.
The particulate-containing resin solution 15 is sheared and emulsified when released from the filter 112 into a liquid phase when passing through the pores of the filter 112. In this embodiment, the emulsified liquid droplets formed by emulsification are referred to as fine particle-containing emulsified particles. The fine particle-containing emulsified particles 170 contain a polymer 150, a crosslinking agent 152, fine particles 153, a dispersant, and a reaction initiator in an organic solvent 151.
(step e: elution of organic solvent from the fine particle-containing emulsified particles)
Fig. 7A is a conceptual diagram of a state in which the organic solvent 151 has eluted from the microparticle-containing emulsified particles 170 to become microparticle-containing resin particles 171.
Since the organic solvent 151 contained in the fine particle-containing emulsified particles 170 is compatible with water, the organic solvent 151 is eluted from the fine particle-containing emulsified particles 170 into the aqueous solution 16. Since the polymer 150 is insoluble in the aqueous solution 16, the polymer is aggregated in the fine particle-containing emulsified particles 170 with elution of the organic solvent 151. In this embodiment, the agglomerated particles are referred to as fine particle-containing resin particles.
As shown in fig. 7B, in step e, the aqueous solution 16 is heated at 50 ℃ for 30 minutes by the heater 115, whereby elution of the organic solvent 151 is promoted.
( Step f: cross-linking polymerization of polymer in microparticle-containing resin particle )
Fig. 8A is a conceptual diagram of a state in which the polymer 150 in the fine particle-containing resin particle 171 is crosslinked by the crosslinking agent 152.
As shown in fig. 8B, in step f, the aqueous solution 16 was heated at 70 ℃ for 8 hours by the heater 115. By heating the aqueous solution 16 to 70 ℃ with the heater 115, radicals are generated from benzoyl peroxide as a polymerization initiator, and the polymer 150 in the fine particle-containing resin particle 171 is crosslinked with the crosslinking agent 152.
Through the above steps, the conductive composite particles E1 were produced.
Example 2: production of conductive composite particles E2
Conductive composite particles E2 were produced in the same manner as in example 1, except that the amounts of the nickel fine particles and polystyrene were adjusted so that the content of the nickel fine particles in the suspension was 10 mass% and the content of the polystyrene in the fine particle-containing resin solution was 3 mass%.
Example 3: production of conductive composite particles E3
Conductive composite particles E3 were produced in the same manner as in example 1, except that the amounts of nickel fine particles and polystyrene were adjusted so that the content of nickel fine particles in the suspension was 10 mass% and the content of polystyrene in the fine particle-containing resin solution was 1 mass%.
Example 4: production of conductive composite particles E4
Conductive composite particles E4 were produced in the same manner as in example 1, except that the amounts of the nickel fine particles and polystyrene were adjusted so that the content of the nickel fine particles in the suspension was 10 mass% and the content of the polystyrene in the fine particle-containing resin solution was 0.3 mass%.
[ evaluation: SEM photograph and EDX Spectrum
Fig. 9A is a photograph based on a Scanning Electron Microscope (SEM) showing the conductive composite particles E3 produced in example 3. Fig. 9B is an EDX spectrum based on Energy Dispersive X-ray spectroscopy (EDX). SEM is SU6600 manufactured by Hitachi High-Tech Corporation, EDX is QUANTAX200 manufactured by BRUKER Corporation. From the SEM photographs and EDX spectra shown in fig. 9A and 9B, it was confirmed that conductive composite particles containing nickel fine particles at a high concentration could be produced.
[ evaluation: average particle diameter of conductive composite particles ]
The average particle diameter of each of the prepared conductive composite particles E1 to E4 was measured from SEM photographs. The particle diameter of each conductive composite particle is obtained by converting the diameter of a circle corresponding to the area of each conductive composite particle. The equivalent circle diameters of 50 conductive composite particles were measured, and the average value thereof was defined as the average particle diameter of the conductive composite particles. The results are shown in Table 1.
[ evaluation: content of conductive Fine particles
The EDX spectrum of the conductive composite particles E1 to E4 thus produced was measured by the EDX, and the content of nickel fine particles was calculated from the EDX spectrum using software incorporating the EDX apparatus. The results are shown in Table 1.
Table 1 shows the average particle diameter of the conductive composite particles and the content of the nickel fine particles, and also shows the content of the nickel fine particles in the suspension and the content of the polystyrene in the fine particle-containing resin solution.
[ Table 1]
Figure BDA0003846949650000181
The upper limit and/or the lower limit of the numerical range described in the present specification can be arbitrarily combined to define a preferable range. For example, the upper limit value and the lower limit value of the numerical range may be arbitrarily combined to define a preferable range, the upper limit values of the numerical ranges may be arbitrarily combined to define a preferable range, and the lower limit values of the numerical ranges may be arbitrarily combined to define a preferable range.
The scope of the claims following the described invention is expressly incorporated into the invention described in this specification, and each is independent of its own embodiment. The invention includes all such alternatives and equivalents as may be substituted by those claims appended hereto. Furthermore, additional embodiments derived from the independent claims and the subsequent dependent claims are also expressly incorporated into this written description.
Those skilled in the art can utilize the foregoing description to maximize the utility of the present invention. The claims and embodiments disclosed in this specification are to be considered in all respects as illustrative and exemplary only and should not be construed to limit the scope of the invention in any way. The present invention can be modified in addition to the details of the above-described embodiments without departing from the basic principle of the present invention. In other words, various modifications and improvements of the embodiments specifically disclosed in the above description are within the scope of the present invention.
(appendix 1)
A method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles, the method comprising:
a step of preparing a resin-containing solution containing conductive fine particles, a resin for forming the resin particles, and an organic solvent having compatibility with an aqueous solvent;
a step of preparing an emulsion in which droplets of a resin-containing solution are dispersed in an aqueous solution by emulsification using fine pores; and
and a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
(appendix 2)
The method for producing conductive composite particles according to appendix 1, wherein the content of the conductive fine particles in the conductive composite particles is 40 mass% or more.
(appendix 3)
The method for producing conductive composite particles according to appendix 1 or 2, wherein the conductive composite particles have an average particle diameter of 0.1 μm or more and 20 μm or less.
(appendix 4)
The method for producing conductive composite particles according to any one of appendices 1 to 3, wherein the conductive fine particles contain metal fine particles.
(appendix 5)
The method for producing conductive composite particles according to any one of appendices 1 to 4, wherein the resin contains a base polymer.
(appendix 6)
The method for producing conductive composite particles according to appendix 5, wherein the base polymer comprises at least one selected from the group consisting of a polyacrylic resin, a polyolefin resin, and a polystyrene resin.
(appendix 7)
The method for producing conductive composite particles according to appendix 5 or 6, wherein the resin-containing solution contains a crosslinking agent for crosslinking the base polymer.
(appendix 8)
The method for producing conductive composite particles according to any one of appendices 1 to 7, comprising: and a step of accelerating elution of the organic solvent into the aqueous solution by heating before causing the polymerization reaction and/or the crosslinking reaction of the droplets of the resin-containing solution.
(appendix 9)
The method for producing conductive composite particles according to any one of appendices 1 to 8, wherein the resin-containing solution or the aqueous solution contains a reaction initiator for a polymerization reaction and/or a crosslinking reaction.
(appendix 10)
The method for producing conductive composite particles according to any one of appendices 1 to 9, wherein the resin-containing solution contains a dispersant for dispersing the conductive fine particles in an organic solvent.
(appendix 11)
The method of manufacturing conductive composite particles according to any one of appendices 1 to 10, wherein an emulsion is prepared by releasing a resin-containing solution into an aqueous solution through a pore.
(appendix 12)
Disclosed are conductive composite particles containing resin particles and conductive fine particles contained in the resin particles, wherein the content of the conductive fine particles in the conductive composite particles is 40 mass% or more.
(appendix 13)
The conductive composite particle as set forth in appendix 12, wherein
The average particle diameter of the conductive composite particles is 0.1 to 20 [ mu ] m.
(appendix 14)
The conductive composite particle according to appendix 12 or 13, wherein the resin particle comprises at least one selected from the group consisting of a polyacrylic resin, a polyolefin resin, and a polystyrene resin.
(appendix 15)
An adhesive film for circuit connection, comprising the conductive composite particles described in any one of appendices 12 to 14 and an adhesive resin.
Description of the symbols
4-1 st circuit board, 5-1 st circuit electrode, 6-2 nd circuit board, 7-2 nd circuit electrode, 10-conductive composite particles, 11-conductive composite particles, 12-film emulsification system, 15-fine particle-containing resin solution, 16-aqueous solution, 20-binder resin, 40-adhesive film for circuit connection, 42-connection structure, 101-resin particles, 102-conductive fine particles, 105-conductive layer, 110-syringe, 111-aqueous solution holding container, 112-filter, 113-connection tube, 114-stirring tool, 115-heater, 150-polymer, 151-organic solvent, 152-crosslinking agent, 153-fine particles, 170-fine particle-containing emulsified particles, 171-fine particle-containing resin particles.

Claims (15)

1. A method for producing conductive composite particles including resin particles and conductive fine particles contained in the resin particles, the method comprising:
a step of preparing a resin-containing solution containing the conductive fine particles, a resin for constituting the resin particles, and an organic solvent having compatibility with an aqueous solvent;
preparing an emulsion in which droplets of the resin-containing solution are dispersed in an aqueous solution by emulsification using fine pores; and
and a step of forming conductive composite particles by causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
2. The method for producing conductive composite particles according to claim 1,
the content of the conductive fine particles in the conductive composite particles is 40 mass% or more.
3. The method for producing conductive composite particles according to claim 1 or 2, wherein,
the average particle diameter of the conductive composite particles is 0.1-20 [ mu ] m.
4. The method for producing conductive composite particles according to any one of claims 1 to 3,
the conductive fine particles include metal fine particles.
5. The method for producing conductive composite particles according to any one of claims 1 to 4,
the resin comprises a base polymer.
6. The method for producing conductive composite particles according to claim 5,
the base polymer includes at least one selected from the group consisting of a polyacrylic resin, a polyolefin resin, and a polystyrene resin.
7. The method for producing conductive composite particles according to claim 5 or 6, wherein,
the resin-containing solution includes a crosslinking agent for crosslinking the base polymer.
8. The method for producing conductive composite particles according to any one of claims 1 to 7, comprising a step of accelerating elution of the organic solvent into the aqueous solution by heating before causing a polymerization reaction and/or a crosslinking reaction of the droplets of the resin-containing solution.
9. The method for producing conductive composite particles according to any one of claims 1 to 8,
the resin-containing solution or the aqueous solution contains a reaction initiator for a polymerization reaction and/or a crosslinking reaction.
10. The method for producing conductive composite particles according to any one of claims 1 to 9,
the resin-containing solution contains a dispersant for dispersing the conductive fine particles in an organic solvent.
11. The method for producing conductive composite particles according to any one of claims 1 to 10,
releasing the resin-containing solution into the aqueous solution through the fine pores to prepare an emulsion.
12. A conductive composite particle comprising a resin particle and a conductive fine particle contained in the resin particle, wherein,
the content of the conductive fine particles in the conductive composite particles is 40 mass% or more.
13. The conductive composite particle according to claim 12,
the average particle diameter of the conductive composite particles is 0.1-20 [ mu ] m.
14. The conductive composite particle according to claim 12 or 13,
the resin particles contain at least one selected from the group consisting of polyacrylic resins, polyolefin resins, and polystyrene resins.
15. An adhesive film for circuit connection, comprising the conductive composite particles according to any one of claims 12 to 14 and a binder resin.
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