JP5581231B2 - Conductive fine particles and anisotropic conductive material using the same - Google Patents

Description

  The present invention relates to fine conductive fine particles, and particularly relates to conductive fine particles that can reduce the occurrence of short circuits when used for electrical connection.

  In recent years, miniaturization and high functionality of electronic devices have been increasingly progressed. Along with this, electronic components mounted on electric devices are being downsized and mounted with high density, and electrodes and wirings in electronic circuits are becoming finer and narrower. 2. Description of the Related Art Conventionally, in assembling electronic devices, a connection method using an anisotropic conductive material has been adopted to make electrical connection between a large number of opposing electrodes and wirings. An anisotropic conductive material is a material in which conductive fine particles are mixed with a binder resin, for example, anisotropic conductive paste (ACP), anisotropic conductive film (ACF), anisotropic conductive ink, anisotropic conductive. There are sheets. In addition, as the conductive fine particles used for the anisotropic conductive material, those obtained by coating the surfaces of metal particles or resin particles as a substrate with a conductive metal layer are used.

  As described above, with the progress of miniaturization and narrowing of the electrodes and wirings of electronic circuits, conductive fine particles used for anisotropic conductive materials are also required to have a smaller particle diameter. Such conductive fine particles having a small particle diameter are made of, for example, a resin or an inorganic compound, have an average particle diameter of 0.5 to 2.5 μm determined by observation with an electron microscope, and a CV value of the particle diameter of 20% or less. Conductive fine particles using microspheres as a substrate have been proposed (see Patent Document 1 (paragraphs 0009 and 0010)).

JP 2000-30526 A

  When the particle diameter of the conductive fine particles is reduced, the particle number density in a resin such as a binder resin is increased when preparing an ACP or ACF preparation composition. At this time, if the variation in the particle diameter is large, the ratio between the base material and the conductive metal layer also varies, and the variation in the specific gravity of the conductive fine particles becomes large. When preparing the ACP or ACF preparation composition, , The dispersion of the conductive fine particles in the binder resin tended to be uneven (particularly, the time from the preparation of the ACF preparation to the preparation of the ACF, the time from the adjustment of the ACP to the use) The longer it becomes, the more pronounced) Therefore, when electrical connection is performed using ACP or ACF using fine conductive fine particles, there is a problem that short-circuiting between electrodes is likely to occur.

  The present invention has been made in view of the above circumstances, and is conductive fine particles that are fine conductive fine particles, excellent in uniform dispersibility and dispersion stability in a binder resin, and can suppress the occurrence of short-circuiting during electrical connection. I will provide a.

The conductive fine particles of the present invention that have solved the above problems are conductive fine particles having a base material composed of resin particles and at least one conductive metal layer formed on the surface of the base material. The number-based average dispersed particle size of the resin particles is 1.0 to 2.5 μm, and the number-based variation coefficient of the dispersed particle size is 4.5% or less. The number average particle diameter of the conductive fine particles is preferably 1.1 μm to 2.8 μm.
In the present invention, an anisotropic conductive material containing the conductive fine particles (preferably an anisotropic conductive paste containing conductive fine particles and a binder resin. Contains conductive fine particles and a binder resin. An anisotropic conductive film formed from the composition.) Is also included.

  According to the present invention, a composition for producing an anisotropic conductive paste (ACP) or anisotropic conductive film (ACF) excellent in uniform dispersion and dispersion stability of conductive fine particles is obtained even when the conductive fine particles are reduced in size. This can reduce the occurrence of short circuits when used for electrical connection.

1. TECHNICAL FIELD The present invention aims to improve fine conductive fine particles. The resin particles used as the base material for the conductive fine particles also have a small particle size, and the number-based average dispersed particle size is 1.0 μm or more, preferably 1.1 μm or more, more preferably 1.2 μm or more, and further preferably 1 It is 0.3 μm or more, 2.5 μm or less, preferably 2.3 μm or less, more preferably 2.1 μm or less, and further preferably 1.9 μm or less. If the average dispersed particle diameter of the substrate is within this range, fine conductive fine particles can be obtained, and can be suitably used for electrical connection of electrodes and wirings that are miniaturized and narrowed.

  The resin particle (base material) has a dispersion coefficient (CV value) based on the number of dispersed particles of 4.5% or less, preferably 4.0% or less, more preferably 3.0% or less, and still more preferably. Is 2.8% or less, particularly preferably 2.5% or less. Resin particles having a small coefficient of variation of the dispersed particle size are not only uniform in primary particle size, but also have a very high monodispersibility of the primary particle size. By using resin particles having such characteristics as a base material, conductive fine particles having a uniform particle diameter and suppressed aggregation can be obtained. Therefore, when the conductive fine particles of the present invention are used, the dispersion of the conductive fine particles in the binder resin becomes good when preparing the ACP or ACF preparation composition. In the present invention, the average dispersed particle size and the like are measured by a Coulter counter, and the measuring method will be described later.

  Here, if there are coarse particles in the conductive fine particles, the coarse particles may settle when the ACP or ACF preparation composition is stored for a long period of time, which may cause aggregation of the conductive fine particles. There is. Therefore, the resin particles preferably have coarse particles removed in addition to having a uniform particle diameter. That is, the resin particle preferably has a particle diameter at an integrated value of 90% of 2.6 μm or less, more preferably 2.2 μm or less, and even more preferably 2.0 μm or less in a number-based integrated distribution curve. .

  The resin particles (base material) need only contain a resin component, and are not limited to particles composed only of organic materials, but may be particles composed of organic-inorganic composite materials. By using resin particles, conductive fine particles having excellent elastic deformation characteristics can be obtained.

  Examples of the organic material constituting the resin particles include polyolefins such as polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyisobutylene, and polybutadiene; vinyl heavy resins such as styrene resins, acrylic resins, and styrene-acrylic resins. Polyesters such as polyethylene terephthalate and polyethylene naphthalate; polycarbonates; polyamides; polyimides; phenol formaldehyde resins; melamine formaldehyde resins; melamine benzoguanamine formaldehyde resins; urea formaldehyde resins; Examples of the organic-inorganic composite material include a material containing the organic material and a polysiloxane skeleton (for example, a material in which a polysiloxane skeleton and a vinyl polymer are combined). The material which comprises these resin particles may be used independently, and 2 or more types may be used together.

  Among the materials constituting the resin particles, those containing a vinyl polymer and / or a polysiloxane skeleton are preferable. A material containing a vinyl polymer has an organic skeleton formed by polymerizing vinyl groups, and is excellent in elastic deformation during pressure connection. In particular, a vinyl polymer containing divinylbenzene as a polymerization component has little decrease in particle strength after coating with a conductive metal. In addition, the material containing the polysiloxane skeleton has excellent contact pressure with respect to the connected body during pressure connection. In particular, a material in which a polysiloxane skeleton and a vinyl polymer are combined is preferable because it is excellent in elastic deformability and contact pressure, and the connection reliability of the obtained conductive fine particles becomes more excellent.

  The vinyl polymer is obtained by polymerizing a vinyl group-containing monomer (radical polymerization), and the “vinyl group” includes not only a carbon-carbon double bond but also a (meth) acryloxy group, an allyl group, isopropenyl. Substituents having a polymerizable carbon-carbon double bond such as a group, vinylphenyl group and isopropenylphenyl group are also included. In this specification, “(meth) acryloxy group”, “(meth) acrylate” and “(meth) acryl” are “acryloxy group and / or methacryloxy group”, “acrylate and / or methacrylate” and “acryl and / Or methacryl ".

  The vinyl group-containing monomer includes a monomer (1) having one vinyl group in the molecule, one vinyl group in the molecule and a functional group other than the vinyl group (a protic hydrogen such as a carboxyl group or a hydroxyl group). Monomer having a terminal group such as a containing group and an alkoxy group) (2) a crosslinkable vinyl group-containing monomer having three or more vinyl groups in one molecule (hereinafter referred to as “crosslinkable vinyl”). Sometimes referred to as a “group-containing monomer”). These monomers (1) to (3) may be used alone or in combination of two or more. Among these, the monomer (1) and / or the crosslinkable vinyl monomer (3) are preferable.

  Examples of the monomer (1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Alkyl (meth) acrylates; cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cycloundecyl (meth) a Cycloalkyl (meth) acrylates such as relate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate; phenyl (meth) acrylate, benzyl (meth) acrylate, tolyl (meth) ) Aromatic ring-containing (meth) acrylates such as acrylate and phenethyl (meth) acrylate; alkyl such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, and pt-butylstyrene And styrene monofunctional monomers such as halogen group-containing styrenes such as styrenes, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene. A monomer (1) may be used independently and may use 2 or more types together. Among these, styrene monofunctional monomers are preferable, and styrene is more preferable.

  Examples of the monomer (2) include monomers having a carboxyl group such as (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Monomers having hydroxy groups such as hydroxy group-containing (meth) acrylates such as butyl (meth) acrylate, hydroxy group-containing styrenes such as p-hydroxystyrene; 2-methoxyethyl (meth) acrylate, 3-methoxybutyl Examples include (meth) acrylates, alkoxy group-containing (meth) acrylates such as 2-butoxyethyl (meth) acrylate, and monomers having an alkoxy group such as alkoxystyrenes such as p-methoxystyrene. A monomer (2) may be used independently and may use 2 or more types together. Here, a carboxyl group, a hydroxy group, an alkoxy group, and the like can form a crosslinked structure when a group serving as a reaction (bonding) partner is present in another monomer.

  Examples of the monomer (3) (crosslinkable vinyl group-containing monomer) include allyl (meth) acrylates such as allyl (meth) acrylate; ethylene glycol di (meth) acrylate and 1,4-butanediol. Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,3-butylene di (meth) Alkanediol di (meth) acrylate such as acrylate; diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentadecaethylene glycol di (meth) acrylate, penta contactor ethylene Glycol di (meta Di (meth) acrylates such as polyalkylene glycol di (meth) acrylate such as acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate; trimethylolpropane tri Tri (meth) acrylates such as (meth) acrylate; Tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; Hexa (meth) acrylates such as dipentaerythritol hexa (meth) acrylate; Divinylbenzene, divinyl Aromatic hydrocarbon crosslinking agents such as naphthalene and derivatives thereof (preferably styrenic polyfunctional monomers such as divinylbenzene); N, N-divinylaniline, divinyl ether, Vinyl sulfide, hetero atom-containing crosslinking agents such as divinyl sulfonic acid; and the like. These crosslinkable vinyl group-containing monomers may be used alone or in combination of two or more. Among these, a monomer having two or more (meth) acryloyl groups in one molecule and a styrene polyfunctional monomer are preferable. Among the monomers having two or more (meth) acryloyl groups in one molecule, a monomer having two or more acryloyl groups in one molecule is preferable, and a monomer having two acryloyl groups in one molecule is preferable. More preferred are dimers (diacrylates), more preferred are alkanediol diacrylates and polyalkylene glycol diacrylates, and particularly preferred are alkanediol diacrylates. Of the styrenic polyfunctional monomers, divinylbenzene is preferred.

  The vinyl polymer includes, as a constituent, the monomer (1); the crosslinkable vinyl group-containing monomer (3); the monomer (1) and the crosslinkable vinyl The aspect containing group-containing monomer (3) is preferable. Specifically, an embodiment containing a styrene monofunctional monomer as a constituent component, an embodiment containing a styrene monofunctional monomer and a monomer having two or more (meth) acryloyl groups in one molecule, a styrene monofunctional An embodiment containing a monomer and a styrenic polyfunctional monomer is preferred. Among these, an embodiment including a styrene monofunctional monomer and a styrene polyfunctional monomer is preferable.

  The polysiloxane skeleton is obtained by hydrolytic condensation of a silane monomer, and examples of the silane monomer include non-crosslinkable silane monomers and crosslinkable silane monomers. Examples of the non-crosslinkable silane monomer include bifunctional silane monomers such as dialkylsilane such as dimethyldimethoxysilane and dimethyldiethoxysilane; and trialkylsilane such as trimethylmethoxysilane and trimethylethoxysilane. And monofunctional silane-based monomers.

  The crosslinkable silane monomer can form a crosslinked structure. The cross-linked structure formed by the cross-linkable silane monomer includes one that cross-links an organic polymer skeleton (for example, a vinyl polymer skeleton) and an organic polymer skeleton (first form); One that crosslinks a polysiloxane skeleton (second form); one that crosslinks an organic polymer skeleton and a polysiloxane skeleton (third form).

  Examples of those that can form the first form include dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane. Examples of what can form the second form include tetrafunctional silane monomers such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane; methyltrimethoxysilane, methyltriethoxysilane And trifunctional silane monomers such as ethyltrimethoxysilane and ethyltriethoxysilane. Examples of those that can form the third form include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, And those having a vinyl group such as 3-methacryloxyethoxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane;

  Here, the polysiloxane skeleton preferably has a skeleton derived from a polymerizable polysiloxane having a radical-polymerizable carbon-carbon double bond (for example, a vinyl group or a (meth) acryloyl group). That is, the polysiloxane skeleton is a crosslinkable silane monomer (preferably having a (meth) acryloyl group, more preferably 3-methacryloxy) capable of forming at least the third form of the crosslinked structure as a constituent component. It preferably contains a polysiloxane skeleton formed by hydrolysis and condensation of propyltrimethoxysilane).

  The resin particles have a content of a crosslinkable monomer (crosslinkable vinyl group-containing monomer, crosslinkable silane monomer) of 5% by mass or more in all monomer components constituting the polymer. More preferably, it is 10 mass% or more, More preferably, it is 15 mass% or more, 80 mass% or less is preferable, More preferably, it is 70 mass% or less, More preferably, it is 60 mass% or less.

  Examples of the method for producing the resin particles having the predetermined average particle diameter and coefficient of variation include a method of classifying the resin particles after synthesizing them by a seed polymerization method. By employing a seed polymerization method for the synthesis of resin particles, resin particles having a small particle size distribution can be synthesized. And by classifying the resin particles after synthesis and removing coarse particles, the average particle diameter and the coefficient of variation can be adjusted to a desired range.

  The seed polymerization method includes a seed particle preparation step, an absorption step, and a polymerization step. For example, when synthesizing particles composed only of an organic material, seed particles may be prepared from the vinyl monomer, and particles composed of an organic material and a material having a polysiloxane skeleton are synthesized. In that case, seed particles (polysiloxane particles) may be prepared from the silane monomer.

  As a method for preparing seed particles from a vinyl monomer, a conventionally used method can be employed, and examples thereof include soap-free emulsion polymerization and dispersion polymerization. In this case, the monomer component constituting the seed particles is preferably a styrene monofunctional monomer such as styrene.

  Examples of a method for preparing seed particles (polysiloxane particles) from a silane monomer include a method of hydrolyzing in a solvent containing water and performing condensation polymerization. As the silane monomer, the above-mentioned crosslinkable silane monomer and non-crosslinkable silane monomer can be used. When a polysiloxane skeleton and a vinyl polymer are combined, a crosslinkable silane monomer having a radical polymerizable group is used as the silane monomer, and polymerizable polysiloxane particles (radical polymerizable Particles having a polysiloxane skeleton having a group) may be prepared. Hydrolysis and polycondensation can employ any method such as batch, split, and continuous. In the hydrolysis and condensation polymerization, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst.

  In the solvent containing water, an organic solvent can be contained in addition to water and the catalyst. Examples of the organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone, Examples thereof include ketones such as methyl ethyl ketone; esters such as ethyl acetate; (cyclo) paraffins such as isooctane and cyclohexane; aromatic hydrocarbons such as benzene and toluene. These may be used alone or in combination of two or more.

  In the hydrolytic condensation, anionic, cationic and nonionic surfactants and polymer dispersants such as polyvinyl alcohol and polyvinylpyrrolidone can be used in combination. These may be used alone or in combination of two or more. Hydrolytic condensation is performed by mixing a silane monomer as a raw material and a solvent containing a catalyst, water, and an organic solvent, and then at a temperature of 0 ° C. to 100 ° C., preferably 0 ° C. to 70 ° C., for 30 minutes or more. It can carry out by stirring for 100 hours or less.

  In the absorption step, the monomer component is absorbed by the seed particles. The method of absorption is not particularly limited as long as it proceeds in the presence of the monomer component in the presence of seed particles. Therefore, the monomer component may be added to the solvent in which the seed particles are dispersed, or the seed particles may be added to the solvent containing the monomer component. Especially, it is preferable to add a monomer component in the solvent which disperse | distributed seed particle | grains previously like the former. In particular, the method of adding the monomer component to the reaction solution without taking out the seed particles obtained in the hydrolysis and condensation step from the reaction solution (seed particle dispersion) does not complicate the process and increases productivity. It is preferable because it is excellent.

  In the absorption step, the timing of adding the monomer component is not particularly limited, and may be added all at once, may be added in several times, or may be fed at an arbitrary rate. In addition, when adding the monomer component, either the monomer component alone or the monomer component solution may be added, but the monomer component is previously added to water or an aqueous medium with an emulsifier. It is preferable to mix the emulsified and emulsified liquid with the seed particles because absorption into the seed particles is performed more efficiently.

  The emulsifier is not particularly limited. For example, an anionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkyl Nonionic surfactants such as amines, glycerin fatty acid esters, and oxyethylene-oxypropylene block polymers are preferable because they can stabilize the dispersed state of the seed particles after absorbing the seed particles and monomer components. These emulsifiers may be used alone or in combination of two or more.

  Moreover, when emulsifying and dispersing the monomer component with an emulsifier, it is preferable to use water or a water-soluble organic solvent that is 0.3 to 10 times the mass of the monomer component. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol; acetone And ketones such as methyl ethyl ketone; esters such as ethyl acetate;

  The absorption step is preferably performed in the temperature range of 0 ° C. to 60 ° C. with stirring for 5 minutes to 720 minutes. These conditions may be set as appropriate depending on the type of seed particles and monomers used, and these conditions may be used alone or in combination of two or more. In the absorption process, for determining whether the monomer component has been absorbed by the seed particles, for example, before adding the monomer component and after completion of the absorption step, observe the particles with a microscope and absorb the monomer component. It can be easily determined by confirming that the particle size is increased.

  In the polymerization step, the monomer component absorbed by the seed particles is subjected to a polymerization reaction. Here, when the seed particles are a polymerizable polysiloxane, the absorbed monomer component and the radical polymerizable group of the polymerizable polysiloxane skeleton are polymerized to form a polysiloxane skeleton and a vinyl polymer. Combine. Although the polymerization method is not particularly limited, for example, a method using a radical polymerization initiator can be mentioned, and the radical polymerization initiator is not particularly limited. For example, a peroxide-based initiator, an azo-based initiator, etc. It can be used. These radical polymerization initiators may be used alone or in combination of two or more.

  The reaction temperature at the time of performing radical polymerization is preferably 40 ° C or higher, more preferably 50 ° C or higher, preferably 100 ° C or lower, more preferably 80 ° C or lower. If the reaction temperature is too low, the degree of polymerization does not increase sufficiently and the mechanical properties of the composite particles tend to be insufficient. On the other hand, if the reaction temperature is too high, aggregation between particles occurs during the polymerization. It tends to happen easily. The reaction time for performing radical polymerization may be appropriately changed according to the type of polymerization initiator to be used, but is usually preferably 5 minutes or more, more preferably 10 minutes or more, and preferably 600 minutes or less. More preferably, it is 300 minutes or less. When the reaction time is too short, the degree of polymerization may not be sufficiently increased, and when the reaction time is too long, aggregation tends to occur between particles.

  The number-based average dispersed particle size of the resin particles after synthesis is preferably 1.1 μm or more, more preferably 1.2 μm or more, still more preferably 1.3 μm or more, and preferably 3.0 μm or less, more preferably 2 0.8 μm or less, more preferably 2.7 μm or less. The number-based variation coefficient of the dispersed particle diameter is preferably 10% or less, more preferably 9% or less, and still more preferably 7% or less.

  The method of classifying the resin particles synthesized as described above is not particularly limited. For example, sieving with an electroforming sieve, etc .; filtration using a filter such as a membrane filter, a pleat filter, or a ceramic membrane filter; mass difference and fluid resistance Known devices that classify by the interaction of differences (gravity classifiers whose principle is gravity difference such as particle fall velocity, etc., the principle of the balance between centrifugal force and air drag by free vortex or semi-free vortex (semi-free) Vortex centrifugal classification, classification using centrifugal classification with a rotating blade based on the balance of centrifugal force generated by a rotating flow created by a rotating classification blade (rotor) and drag by air; and the like. Among these, classification using an electric sieve is preferable from the viewpoint of classification accuracy and productivity.

  In the case of classification using an electric sieve, it is preferable that a dispersion in which resin particles are dispersed in a liquid medium is passed through the electric sieve. Examples of the liquid medium include water; alcohols such as methanol, ethanol, propanol and butanol; hydrocarbons such as hexane and octane; aromatic hydrocarbons such as benzene, toluene and xylene; These may be used alone or in combination of two or more. Among these, alcohols and hydrocarbons are preferable, and methanol and hexane are more preferable. In order to improve the dispersibility of the resin particles, various dispersants may be added to the liquid medium.

  The amount of the liquid medium used is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, still more preferably 500 parts by mass or more, and preferably 10,000 parts by mass or less, relative to 100 parts by mass of the resin particles. Preferably it is 5000 mass parts or less, More preferably, it is 2000 mass parts or less. The method for dispersing the resin particles in the liquid medium is not particularly limited, for example, a method of dispersing by irradiating ultrasonic waves; a method of dispersing by a normal dispersing device, a high speed stirring device, a shearing dispersing device such as a colloid mill or a homogenizer, and the like. And the like.

  The dispersion liquid temperature at the time of passing the electroformed sieve is not particularly limited and may be appropriately adjusted according to the liquid medium to be used, but is usually 0 ° C to 100 ° C. The liquid temperature of the dispersion is naturally less than the boiling point of the liquid medium. What is necessary is just to change the dimension of the sieve hole of an electroforming sieve according to the desired average particle diameter and a coefficient of variation. By performing classification using an electric sieve, coarse particles can be removed, and the coefficient of variation of the particle diameter of the resin particles can be reduced.

  The conductive fine particles of the present invention have at least one conductive metal layer formed on the substrate (resin particle) surface. The metal constituting the conductive metal layer is not particularly limited. For example, gold, silver, copper, platinum, iron, lead, aluminum, chromium, palladium, nickel, rhodium, ruthenium, antimony, bismuth, germanium, tin, cobalt Indium, nickel-phosphorous, nickel-boron and other metals and metal compounds, and alloys thereof. Among these, gold, nickel, palladium, and silver are preferable because of excellent conductivity. Moreover, nickel, nickel alloy (Ni-Au, Ni-Pd, Ni-Pd-Au, Ni-Ag) etc. are preferable at an inexpensive point. The conductive metal layer may be a single layer or multiple layers. In the case of multiple layers, for example, a combination of nickel-gold, nickel-palladium, nickel-palladium-gold, nickel-silver, etc. Is preferred.

  The thickness of the conductive metal layer is preferably 0.01 μm or more, more preferably 0.03 μm or more, further preferably 0.05 μm or more, preferably 0.20 μm or less, more preferably 0.18 μm or less, More preferably, it is 0.15 μm or less. When the thickness of the conductive metal layer is within the above range, stable electrical connection can be maintained when the conductive fine particles are used as the anisotropic conductive material.

  In addition, the conductive fine particles of the present invention have a uniform dispersion of the conductive fine particles because the dispersion of the specific gravity of the conductive fine particles is suppressed by suppressing the dispersion of the particle diameter of the resin particles as the base material. In addition, there is an effect that an ACP or ACF preparation composition having excellent dispersion stability can be obtained. Furthermore, in the conductive fine particles of the present invention, variation in specific gravity can be achieved by reducing the thickness of the conductive metal layer and reducing the specific gravity (true specific gravity) of the metal layer constituting the conductive metal layer. The conductive fine particles are further suppressed, and the above-described effects are further improved. The effect of reducing the thickness of the conductive metal layer and the effect of reducing the specific gravity (true specific gravity) of the metal constituting the conductive metal layer are not only to reduce the specific gravity of the conductive fine particles, but also to variations in particle diameter. The effect of suppressing the variation in specific gravity of the conductive fine particles in synergy with the effect of suppressing the conductive fine particles, and the effect of improving the dispersion (stability) of the conductive fine particles in the composition are further improved.

From such a viewpoint, the thickness of the conductive metal layer is preferably less than 0.12 μm, and preferably 0.10 μm or less. Similarly, the metal constituting the conductive metal layer is preferably composed of a metal having a true specific gravity of 10,000 kg / m ³ or less. For example, as the metal having such true specific gravity, for example, nickel, nickel alloy, copper, copper alloy, tin, and tin alloy are preferable. When the conductive metal layer is composed of multiple layers, it should be composed of a metal (preferably nickel, nickel alloy, copper, copper alloy, tin, tin alloy) having a true specific gravity of at least one layer of 10,000 kg / m ³ or less. preferable. When providing a metal layer having a true specific gravity exceeding 10,000 kg / m ³ such as gold, the thickness of the metal layer is preferably less than 0.02 μm, and more preferably 0.01 μm or less.

  The method for forming the conductive metal layer is not particularly limited, for example, a method in which the surface of the substrate is plated by an electroless plating method, an electrolytic plating method, or the like; physical properties such as vacuum deposition, ion plating, ion sputtering on the surface of the substrate A method of forming a conductive metal layer by a general vapor deposition method; Among these, the electroless plating method is particularly preferable in that a conductive metal layer can be easily formed without requiring a large-scale apparatus.

  The number average particle diameter of the conductive fine particles of the present invention is preferably 1.1 μm or more, more preferably 1.2 μm or more, further preferably 1.3 μm or more, particularly preferably 1.4 μm or more, and 2.8 μm or less. Is preferably 2.6 μm or less, more preferably 2.4 μm or less, and particularly preferably 2.2 μm or less. If the number average particle diameter is within this range, it can be suitably used for electrical connection of miniaturized and narrowed electrodes and wirings.

2. Resin-coated conductive fine particles The conductive fine particles of the present invention may further have an insulating resin layer on the surface of the conductive metal layer. The insulating resin layer is not particularly limited as long as the insulating property between the particles of the conductive fine particles can be ensured, and the insulating resin layer can be easily collapsed or peeled off by a constant pressure and / or heating. For example, polyolefins such as polyethylene; (meth) acrylate polymers and copolymers such as polymethyl (meth) acrylate; thermoplastic resins such as polystyrene; and particularly cross-linked products thereof; heat such as epoxy resins, phenol resins, and melamine resins Curable resins; water-soluble resins such as polyvinyl alcohol and mixtures thereof.

  However, when the insulating resin layer is too hard as compared with the resin particles serving as the base material, the resin particles themselves may be destroyed before the insulating resin layer is destroyed. Therefore, it is preferable to use uncrosslinked or relatively low degree of crosslinking resin for the insulating resin layer.

  The insulating resin layer may be a single layer or a plurality of layers. For example, single or multiple film-like layers; layers with insulating particles, spheres, lumps, scales and other shapes attached to the surface of the conductive fine particles; and the surface of the conductive fine particles is chemically modified Or a layer formed by doing so. The thickness of the resin insulating layer is preferably 0.01 μm to 1 μm, more preferably 0.1 μm to 0.5 μm. When the thickness of the resin insulating layer is within the above range, the electrical insulation between the particles is good while maintaining the conduction characteristics by the conductive fine particles.

3. Anisotropic Conductive Material The conductive fine particle of the present invention is also suitable as a constituent material of the anisotropic conductive material, and the anisotropic conductive material using the conductive fine particle of the present invention is also preferable implementation of the present invention. This is one aspect. Electrical connection can be achieved by providing anisotropic conductive materials between opposing substrates or between electrode terminals. The anisotropic conductive material using the conductive fine particles of the present invention includes a conductive material for a liquid crystal display element (conductive spacer and composition thereof).

  The form of the anisotropic conductive material is not particularly limited as long as the conductive fine particles of the present invention are used. For example, an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive is used. And various forms such as anisotropic conductive ink. The anisotropic conductive paste is obtained, for example, by making a resin composition containing conductive fine particles and a binder resin into a paste. The obtained anisotropic conductive paste is placed in, for example, a suitable dispenser, applied on the electrode to be connected with a desired thickness, and the counter electrode is superimposed on the coated anisotropic conductive paste. It is used for connection between electrodes by curing the resin by applying pressure while heating. For example, an anisotropic conductive film is made into a liquid by adding a solvent to a film-forming composition containing conductive fine particles and a binder resin, and this liquid is applied onto a film made of polyethylene terephthalate, and then the solvent is evaporated. Can be obtained. The obtained anisotropic conductive film is disposed on electrodes, for example, and is used for connection between the electrodes by superposing a counter electrode on the anisotropic conductive film and heating and compressing it.

  The anisotropic conductive material is manufactured by dispersing the conductive fine particles of the present invention in an insulating binder resin to obtain a desired form. Of course, the insulating binder resin and the conductive fine particles May be used separately to connect between substrates or between electrode terminals.

  The binder resin is not particularly limited, and is, for example, a thermoplastic resin such as an acrylic resin, an ethylene-vinyl acetate resin, a styrene-butadiene block copolymer; a monomer or oligomer having a glycidyl group, and a curing agent such as isocyanate. Examples thereof include a curable resin composition that is cured by reaction and a curable resin composition that is cured by light and heat.

  In the anisotropic conductive material of the present invention, the content of the conductive fine particles may be appropriately determined according to the use. For example, the volume of the anisotropic conductive material is preferably 1% by volume or more, more preferably Is 2% by volume or more, more preferably 5% by volume or more, preferably 50% by volume or less, more preferably 30% by volume or less, and still more preferably 20% by volume or less. If the content of the conductive fine particles is too small, it may be difficult to obtain sufficient electrical continuity. On the other hand, if the content of the conductive fine particles is too large, the conductive fine particles are in contact with each other, and anisotropy is caused. The function as a conductive material may be difficult to be exhibited.

  About the film thickness in the anisotropic conductive material of the present invention, the coating thickness of the paste or adhesive, the printed film thickness, etc., the particle diameter of the conductive fine particles of the present invention to be used and the specifications of the electrode to be connected In consideration of the above, it is preferable to appropriately set so that the conductive fine particles are sandwiched between the electrodes to be connected and the gap between the bonding substrates on which the electrodes to be connected are formed is sufficiently filled with the binder resin layer. .

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention. In the following, “part” means “part by mass” and “%” means “mass%” unless otherwise specified.

1. Evaluation method 1-1. Number-based average dispersed particle size, coefficient of variation (CV value)
<Seed particles, resin particles>
Measure the particle size of 30000 particles with a particle size distribution measuring device (Beckman Coulter, "Coulter Multisizer III type"), the number-based average dispersed particle size, the standard deviation of the dispersed particle size, and the number-based integrated distribution While obtaining the particle diameter of 90% of the integrated value in the curve, the number-based CV value (coefficient of variation) of the dispersed particle diameter was calculated according to the following formula.
Coefficient of variation of particles (%) = 100 × (standard deviation of particle diameter / number-based average dispersed particle diameter)
<Conductive fine particles>
Using a flow type particle image analyzer (manufactured by Sysmex Corporation, “FPIA (registered trademark) -3000”), the particle diameter (μm) of 3000 conductive fine particles was measured, and the number average particle diameter was determined.

1-2. Conductive metal layer thickness Using a flow type particle image analyzer (manufactured by Sysmex Corporation, “FPIA (registered trademark) -3000”), the particle diameter of 3000 resin particles and 3000 conductive particles were measured. The number average particle diameter X (μm) of the resin particles and the number average particle diameter Y (μm) of the conductive fine particles were determined. And the film thickness of the electroconductive metal layer was computed according to the following formula.
Conductive metal layer thickness (μm) = (Y−X) / 2

1-3. ACF test 10 parts by mass of conductive fine particles, 100 parts by mass of epoxy resin (manufactured by Mitsubishi Chemical, “JER828”) as a binder resin, curing agent (manufactured by Sanshin Chemical Co., Ltd., “Sun-Aid (registered trademark) SI-150”) 2 Add 100 parts by mass of toluene and 100 parts by mass of toluene, add 50 parts by mass of 1 mm zirconia beads, perform dispersion at 300 rpm for 10 minutes using two stainless steel stirring blades, and obtain the paste-like composition obtained. It was applied onto a release-treated PET film with a bar coater and dried to obtain an anisotropic conductive film. The obtained anisotropic conductive film was cut to prepare 100 test pieces.
The obtained anisotropic conductive film test piece was sandwiched between a whole surface aluminum vapor-deposited glass substrate having resistance measurement lines and a polyimide film substrate having a copper pattern formed at a pitch of 30 μm, and thermocompression bonded under a pressure bonding condition of 5 MPa and 200 ° C. Then, a continuity test was conducted to check for the presence of a short circuit. Conductivity test was performed on 100 test pieces, and the ratio of occurrence of short circuit was determined.

1-4. ACP test 20 parts by mass of conductive fine particles, 100 parts by mass of epoxy resin (manufactured by Mitsubishi Chemical, “JER828”) as a binder resin, curing agent (manufactured by Sanshin Chemical Co., Ltd., “Sun-Aid (registered trademark) SI-150”) 2 Part by mass and 50 parts by mass of toluene were added and stirred with a three roll mill to obtain an anisotropic conductive paste.
The obtained anisotropic conductive paste was sandwiched between a whole surface aluminum vapor-deposited glass substrate having resistance measurement lines and a polyimide film substrate having a copper pattern formed at a pitch of 30 μm, and thermocompression bonded under a pressure bonding condition of 5 MPa and 200 ° C. A test piece was prepared. Conductivity tests were performed on 100 test pieces, the presence or absence of a short circuit was examined, and the rate at which a short circuit occurred was determined.
Moreover, the test piece was produced as mentioned above using the anisotropic conductive paste immediately after preparation, and the anisotropic conductive paste preserve | saved at 40 degreeC after preparation for 2 weeks, respectively, and connection resistance value was calculated | required, respectively. By substituting the results obtained in the following equation, the connection resistance value increase rate was determined, and when the resistance value increase rate was less than 10%, “A” and 10% or more and less than 25% were determined as “B”.
Rate of increase (%) = 100 × (connection resistance value of the prepared test piece after storage at 40 ° C. for 2 weeks) / (connection resistance value of the prepared test piece immediately after preparation)

2. 2. Production of conductive fine particles 2-1. Production Example 1
Resin particles In a four-necked flask equipped with a condenser, thermometer, and dripping port, 1800 parts of ion-exchanged water, 24 parts of 25% aqueous ammonia, and 600 parts of methanol are added, and 3-methacryloxypropyl is added from the dripping port with stirring. 120 parts of trimethoxysilane was added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane was performed to prepare an emulsion of polysiloxane particles having a methacryloyl group (polymerizable polysiloxane particles). The number-based average dispersed particle size of the polysiloxane particles was 1.85 μm.

  Then, 1.2 parts of 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd .: “Hytenol (registered trademark) NF-08”) as an emulsifier is added with 120 parts of ion-exchanged water. A solution in which 120 parts of styrene and 2.4 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd .: “V-65”) were dissolved was added to the dissolved solution, An emulsion of monomer components was prepared by emulsifying and dispersing. Two hours after the start of the reaction, the obtained emulsion was added to an emulsion of polysiloxane particles (seed particles) and further stirred. One hour after the addition of the emulsified liquid, the mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were enlarged by absorbing the monomer.

  Next, 4.8 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt was added, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere, and kept at 65 ° C. for 2 hours. The components were radically polymerized. The emulsion after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol, and then vacuum-dried at 80 ° C. for 12 hours under a nitrogen atmosphere. 1 was obtained. This resin particle No. The number-based average dispersed particle size of 1 was 2.50 μm, and the coefficient of variation (CV value) was 6.5%.

Electroless plating Resin particles were etched with sodium hydroxide and then sensitized with a tin dichloride solution. Further, activation with a palladium dichloride solution was performed to form palladium nuclei. Next, the catalyzed resin particles with palladium nuclei formed are immersed in an electroless nickel plating bath to form a nickel plating layer until the film thickness reaches 0.09 μm, followed by gold displacement plating and 0.01 μm gold A layer was formed. Thereafter, after washing with ion-exchanged water, alcohol substitution was performed and vacuum drying was performed. 1 was obtained.

2-2. Production Example 2
Resin particle No. obtained in Production Example 1 1 was classified with an electroformed sieve (size of sieve hole: 3.5 μm), whereby a resin particle No. 1 having a number-based average dispersed particle diameter of 2.48 μm and a coefficient of variation of 4.5% was obtained. 2 was obtained. In the classification, 100 g of resin particles were put in 1000 g of methanol, and sufficiently dispersed by irradiating ultrasonic waves, and then passed through an electric sieve. The obtained resin particle No. 2 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-3. Production Example 3
The resin particle No. 2 is classified with an electric sieve (size of sieve hole: 3.0 μm), thereby obtaining a resin particle No. 2 having a number-based average dispersed particle diameter of 2.46 μm and a coefficient of variation of 2.9%. 3 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 3 was electrolessly plated in the same manner as in Production Example 1 to obtain conductive fine particles.

2-4. Production Example 4
The resin particle No. 3 is classified with an electroformed sieve (size of sieve hole: 3.5 μm), thereby obtaining a resin particle No. having a number-based average dispersed particle diameter of 2.45 μm and a coefficient of variation of 2.4%. 4 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 4 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-5. Production Example 5
Except that the amounts of ion-exchanged water and methanol used were changed to 2000 parts of ion-exchanged water and 400 parts of methanol, the same operation as in Production Example 1 was carried out to obtain polysiloxane particles (number-based average dispersed particle size of 1.49 μm). Got. Monomer as in Production Example 1 except that the obtained polysiloxane particles were used as seed particles and the monomer component to be absorbed was changed to 60 parts of styrene and 60 parts of divinylbenzene (DVB960 manufactured by Nippon Steel Chemical Co., Ltd.). The body was absorbed and polymerized. The number-based average dispersed particle size of the obtained resin particles was 2.01 μm, and the coefficient of variation (CV value) was 6.7%. Thereafter, the obtained resin particles are classified with an electric sieve (size of sieve holes: 2.8 μm), whereby the number-based average dispersed particle diameter is 1.97 μm, and the coefficient of variation (CV value) is 4.3%. Resin particle No. 5 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 5 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-6. Production Example 6
The resin particle No. 5 is classified with an electric sieve (size of sieve holes: 2.4 μm), thereby obtaining a resin particle No. 1 having a number-based average dispersed particle size of 1.93 μm and a coefficient of variation (CV value) of 2.7%. 6 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 6 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-7. Production Example 7
The resin particle No. No. 6 was classified with an electric sieve (size of sieve hole: 2.2 μm), whereby a resin particle No. having a number-based average dispersed particle size of 1.92 μm and a coefficient of variation (CV value) of 2.3% was obtained. 7 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 7 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-8. Production Example 8
Except having changed the usage-amount of ion-exchange water and methanol into 2200 parts of ion-exchange water, and 200 parts of methanol, operation similar to manufacture example 1 was performed and the polysiloxane particle | grain (number average particle diameter 0.85 micrometer) was obtained. . The obtained polysiloxane particles were used as seed particles to carry out monomer absorption and polymerization in the same manner as in Production Example 1. The number-based average dispersed particle diameter of the obtained resin particles was 1.15 μm, and the coefficient of variation (CV value) was 7.2%. Thereafter, the obtained resin particles are classified with an electric sieve (size of sieve holes: 1.7 μm), whereby the number-based average dispersed particle diameter is 1.12 μm, and the coefficient of variation (CV value) is 4.4%. Resin particle No. 8 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 8, electroless plating was performed in the same manner as in Production Example 1 except that the thickness of the nickel plating layer was changed to 0.10 μm and the thickness of the gold plating layer was changed to 0.02 μm to obtain conductive fine particles. .

2-9. Production Example 9
The resin particle No. 8 was classified with an electric sieve (size of the sieve hole: 1.5 μm), whereby a resin particle No. having a number-based average dispersed particle size of 1.08 μm and a coefficient of variation (CV value) of 2.8% was obtained. 9 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 9 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-10. Production Example 10
The resin particle No. No. 9 was classified with an electric sieve (size of sieve hole: 1.3 μm), so that a resin particle No. having an average dispersed particle size of 1.07 μm and a coefficient of variation (CV value) of 2.3% was obtained. 10 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 10 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-11. Production Example 11
Except that the amounts of ion-exchanged water and methanol used were changed to 1400 parts of ion-exchanged water and 1000 parts of methanol, the same operation as in Production Example 1 was carried out to obtain polysiloxane particles (number-based average dispersed particle size of 2.50 μm). Got. The obtained polysiloxane particles were used as seed particles to carry out monomer absorption and polymerization in the same manner as in Production Example 1. The number-based average dispersed particle size of the obtained resin particles was 3.38 μm, and the coefficient of variation (CV value) was 6.2%. Thereafter, the obtained resin particles are classified with an electric sieve (size of sieve holes: 4.7 μm), whereby the number-based average dispersed particle diameter is 3.34 μm and the coefficient of variation (CV value) is 3.7%. Resin particle No. 11 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 11 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

2-12. Production Example 12
Except that the amounts of ion-exchanged water and methanol used were changed to 2300 parts of ion-exchanged water and 100 parts of methanol, the same operation as in Production Example 1 was carried out to obtain polysiloxane particles (number-based average dispersed particle size 0.67 μm). Got. The obtained polysiloxane particles were used as seed particles to carry out monomer absorption and polymerization in the same manner as in Production Example 1. The obtained resin particles had a number-based average dispersed particle size of 0.91 μm and a coefficient of variation (CV value) of 7.6%. Thereafter, the obtained resin particles are classified with an electric sieve (size of sieve holes: 1.5 μm), whereby the number-based average dispersed particle diameter is 0.89 μm, and the coefficient of variation (CV value) is 4.5%. Resin particle No. 12 was obtained. In addition, classification is resin particle No. except having changed the dimension of the sieve hole of an electroformed sieve. 2 was carried out under the same conditions as when producing 2. The obtained resin particle No. 12 was subjected to electroless plating in the same manner as in Production Example 1 to obtain conductive fine particles.

  Table 1 shows the number average particle size and coefficient of variation of the base material (resin particles) and the evaluation results for the conductive fine particles obtained in each production example.

  In the conductive fine particles of Production Example 1, the number-based variation coefficient of the dispersed particle diameter of the resin particles exceeds 4.5%, but the dispersibility of the conductive fine particles in the ACF composition and ACP was poor. . Therefore, in both ACF and ACP, the occurrence rate of short circuit at the time of electrical connection was high. Moreover, since many coarse particles were included, the storage stability of ACP was inferior.

  In the conductive fine particles of Production Examples 2 to 10, the number-based average dispersed particle diameter of the resin particles is 1.0 μm to 2.5 μm, and the number-based variation coefficient of the dispersed particle diameter of the resin particles is 4.5% or less. However, both the ACF and ACP using these have a low occurrence rate of short circuit during electrical connection. Moreover, since coarse particles were removed, the storage stability of ACP was also excellent.

  The conductive fine particles of Production Examples 11 and 12 are cases in which the average dispersed particle size based on the number of resin particles is less than 1.0 μm or more than 2.5 μm, but in both ACF and ACP, The incidence of shorts was high.

  Further, the conductive fine particles of Production Example 8 are in the case where the thickness of the conductive metal layer is 0.12 μm. However, Production Example 1 in which the thickness of the conductive metal layer is 0.10 μm as compared with the conductive fine particles. It can be seen that the conductive fine particles of ˜7, 9, 10 have a low short-circuit occurrence rate (for example, the short-circuit occurrence rate in the ACF test of Production Example 2 and Production Example 5 having substantially the same coefficient of variation is It is suppressed to half of the case of 8.) That is, it can be seen that, in the conductive fine particles in which the variation coefficient of the dispersed particle diameter of the resin particles is suppressed to 4.5% or less, the occurrence rate of short circuit can be further reduced by further reducing the thickness of the conductive metal layer.

  The conductive fine particles of the present invention are suitably used for anisotropic conductive materials such as anisotropic conductive films, anisotropic conductive pastes, anisotropic conductive adhesives, anisotropic conductive inks, and the like.

Claims (5)

Conductive fine particles having a base material composed of resin particles and at least one conductive metal layer formed on the surface of the base material,
The conductive metal layer has a thickness of 0.18 μm or less;
The resin particles are used for electrical connection, wherein the number-based average dispersed particle diameter is 1.0 μm to 2.5 μm, and the number-based variation coefficient of the dispersed particle diameter is 3.0% or less. Conductive fine particles.   2. The conductive fine particles according to claim 1, wherein the conductive fine particles themselves have a number average particle diameter of 1.1 μm to 2.8 μm.   An anisotropic conductive material comprising the conductive fine particles according to claim 1.   An anisotropic conductive paste comprising the conductive fine particles according to claim 1 or 2 and a binder resin.   An anisotropic conductive film formed from a composition containing the conductive fine particles according to claim 1 or 2 and a binder resin.