JP2013030439A - Conductive fine particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive fine particle which is a micro conductive fine particle, has excellent dispersibility into a binder resin, and is capable of suppressing occurrence of a short circuit in electrical connection.SOLUTION: A conductive fine particle of the present invention includes: a base material comprising resin particles; and at least one conductive metal layer formed on a surface of the base material. The resin particles have a number average particle size in a range of 1.0-2.5 μm, and a content (on a number basis) of fine particles of 0.10% or less, the fine particles having a particle size in a range of 0.25-0.70 μm.

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. As such conductive particles having a small particle size, for example, a microsphere made of a resin or an inorganic compound and having an average particle size of 0.5 to 2.5 μm and a particle size CV value of 20% or less is used as a base material. The conductive fine particles used have been proposed (see Patent Document 1 (paragraphs 0009 and 0010)).

  By the way, resin particles are used for applications such as anti-blocking agents and liquid crystal panel spacers, and those applications are required to have a uniform particle size. Therefore, for example, when producing resin particles by the seed polymerization method, in the step of absorbing the monomer component into the seed particles, the shape of the stirring blade for stirring the reaction liquid, the peripheral speed is controlled, and the monodisperse resin A method for obtaining particles has been proposed (Patent Document 2).

JP 2000-30526 A JP-A-2005-272779

However, conductive fine particles having a small average particle size (for example, an average particle size of 1.0 μm to 2.5 μm) are used in electrical connection as compared with conventional conductive fine particles having an average particle size of about 5 μm. There is a problem that the occurrence rate of short circuit becomes high. As a result of studies by the present inventors, it has been found that this problem is caused by fine particles having a very small particle size (for example, a particle size of 0.70 μm or less).
That is, in order to reduce the particle diameter of the conductive fine particles, it is necessary to prepare resin particles having a small average particle diameter as the base material. When producing resin particles having a small average particle diameter, it is difficult to remove fine particles by conventional classification techniques, and fine particles are likely to be mixed. Therefore, when conductive fine particles are produced using such resin particles, conductive fine particles based on fine particles are also generated. And the conductive fine particle which makes a microparticle a base material has the ratio of the plating mass with respect to the total mass, and becomes high specific gravity and high hardness.
By the way, when the particle diameter of the conductive fine particles is reduced, the particle number density in ACP or ACF increases, and the viscosity of the mixture tends to increase when preparing the ACP or ACF preparation composition. Therefore, it is necessary to apply a high shearing force at the time of preparation. At this time, metal particles that cause a short circuit are generated by the conductive fine particles based on the fine particles. Specifically, since the conductive fine particles based on fine particles have a high specific gravity and high hardness, the metal layer of other conductive fine particles is damaged, and metal wear pieces are generated. In addition, the metal layer itself of the conductive fine particles based on the fine particles may be broken, resulting in metal fragments.
As described above, in the conductive fine particles having a small average particle diameter, when the resin particles as the base material contain fine particles of a predetermined size, there is a problem that the occurrence rate of short circuit becomes high when used for electrical connection. I found out.

  The present invention has been made in view of the above circumstances, and provides conductive fine particles that are fine conductive fine particles and can suppress the occurrence of short-circuiting during electrical connection when used as an anisotropic conductive material. .

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 average particle diameter of the resin particles is 1.0 μm to 2.5 μm, and the content (number basis) of fine particles having a particle diameter in the range of 0.25 μm to 0.70 μm is 0.10%. It is characterized by the following. The number average particle diameter of the conductive fine particles is preferably 1.1 μm to 2.8 μm.
Further, in the present invention, resin particles used for the base material of conductive fine particles, the number average particle diameter is 1.0 μm to 2.5 μm, and the particle diameter is in the range of 0.25 μm to 0.70 μm. Resin particles having a content of fine particles (number basis) of 0.10% or less; anisotropic conductive material containing the conductive fine particles (preferably containing conductive fine particles and a binder resin) An anisotropic conductive paste.) Is also included.

  According to the present invention, even when the conductive fine particles are reduced in size, it is possible to reduce the occurrence of a short circuit when an anisotropic conductive material containing the conductive fine particles is 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 of the conductive fine particles have a small particle size, and the number-based average particle size is 1.0 μm or more, preferably 1.1 μm or more, more preferably 1.2 μm or more, and still more preferably 1. It is 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 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 content (number basis) of fine particles having a particle diameter in the range of 0.25 μm to 0.70 μm of 0.10% or less, preferably 0.05% or less. More preferably, it is 0.02% or less, and still more preferably 0.01% or less. By using the resin particles having such characteristics as the base material, the content of the conductive fine particles based on the fine particles can be reduced when forming the conductive metal layer. When such conductive fine particles are used, generation of metal pieces can be suppressed when preparing an ACP or ACF preparation composition. Therefore, ACP and ACF using the conductive fine particles of the present invention suppress the occurrence of a short circuit during electrical connection. In the present invention, the average particle size and the like are measured by a Coulter counter, and the measuring method will be described later.
Moreover, in this invention, a microparticle is a particle | grain with a particle diameter of 0.25 micrometer-0.70 micrometer detected by the particle diameter measurement after giving a predetermined ultrasonic dispersion process. That is, particles that are present in an independently dispersed state when a predetermined ultrasonic dispersion treatment is performed and that are firmly attached to other particles after the ultrasonic dispersion treatment are excluded.

  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 the crosslinkable vinyl group-containing 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, and a styrene polyfunctional monomer is 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 polyfunctional monomer; a monomer having two or more (meth) acryloyl groups in one molecule and a styrene monofunctional monomer An embodiment containing a styrene monofunctional monomer and a styrene polyfunctional monomer is more preferred, and an embodiment comprising a styrene monofunctional monomer and a styrene polyfunctional monomer is particularly preferred.

  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, Those having a (meth) acryloyl group such as 3-methacryloxyethoxypropyltrimethoxysilane; those having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane; and the like.

  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 resin particles having the predetermined average particle diameter and fine particle content include, for example, a monomer component used in the absorption step in a seed polymerization method including a seed particle preparation step, an absorption step, and a polymerization step. And a method of controlling the ratio (de / ds) between the droplet diameter (ds) of the monomer component and the number average particle diameter (de) of the seed particles in the emulsion. By controlling the droplet diameter of the monomer component and increasing the total droplet surface area of the monomer component, the absorption efficiency of the monomer component into the seed particles can be increased, so the content of fine particles Can be reduced. As a method for reducing the content of fine particles, classification (for example, sieving) can also be employed. However, since the fine particles are likely to adhere to the surface of the particles having a relatively large particle size, it is difficult to reduce the content to 0.10% or less by classification.

  In the seed polymerization method, for example, in the case of synthesizing particles composed only of an organic material, seed particles may be prepared from the vinyl monomer, which is composed of an organic material and a material having a polysiloxane skeleton. In the case of synthesizing particles, 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.

  Here, in order to reduce the amount of fine particles in the resin particles, when adding the monomer component, the monomer component is preliminarily dispersed in water or an aqueous medium with an emulsifier, and in the emulsion The volume average particle diameter of the droplet diameter of the monomer component is 0.8 μm or more, preferably 1.0 μm or more, more preferably 1.2 μm or more, 10 μm or less, preferably 5.0 μm or less, more preferably 3.0 μm. Control to: In addition, what is necessary is just to adjust the stirring speed etc. at the time of emulsion liquid adjustment suitably for control of a droplet diameter. Although the stirring method is not specifically limited, For example, a homomixer etc. may be used.

  At this time, the ratio (de / ds) between the droplet diameter (ds) of the monomer component and the number average particle diameter (de) of the seed particles is 5.0 or less, preferably 4.5 or less, more preferably Is 3.0 or less. By setting the ratio (de / ds) within the above range, the content of fine particles of the obtained resin particles can be reduced.

  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 average particle diameter based on the number of the resin particles after synthesis is 1.0 μm or more, preferably 1.1 μm or more, more preferably 1.2 μm or more, further preferably 1.3 μm or more, preferably 2.5 μm or less, preferably It is 2.3 μm or less, more preferably 2.1 μm or less, and even more preferably 1.9 μm or less.

  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, silver, copper, and tin are preferable because of excellent conductivity. In addition, nickel, nickel alloy, copper, copper alloy, silver, silver alloy, tin, and tin alloy are preferable from the viewpoint of inexpensiveness. Among them, nickel, nickel alloy (Ni-P, Ni-B, Ni-Zn, Ni-Sn) are preferable. Ni-W, Ni-Co, Ni-Ti) and the like are preferable. The conductive metal layer may be a single layer or multiple layers. In the case of multiple layers, for example, combinations of nickel / gold, nickel / palladium, nickel / palladium / gold, nickel / silver and the like are preferable.

  In addition, the harder the conductive metal layer, the more likely that a short circuit occurs due to the fine particles in the resin particles. Therefore, the harder the conductive metal layer, the more pronounced the short-circuit suppressing effect by reducing the fine particles. Examples of the conductive metal layer made of such a hard material include a nickel layer and a nickel alloy layer. In addition, since generation | occurrence | production of a short circuit is suppressed, so that a conductive metal layer is softer, when nickel is employ | adopted as a metal which comprises a conductive metal layer, it is preferable to set it as a nickel alloy, especially Ni-P alloy, Ni -B alloys are preferred. When these nickel alloys are employed, the P content in the Ni-P alloy and the B content in the Ni-B alloy are preferably 4% by mass or more, more preferably 5% by mass or more, and still more preferably. It is 6 mass% or more. The higher the P or B content, the softer the nickel alloy layer, and the occurrence of short circuit is further suppressed. Further, the P content of the Ni—P alloy is preferably 15% by mass or less, and the B content of the Ni—B alloy is preferably 10% by mass or less. The smaller the P content and B content, the lower the electrical resistance value of the metal layer. Note that the P and B contents in the nickel alloy can be controlled by adjusting the P and B concentrations in the electroless nickel plating solution and the pH of the plating solution.

  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, when the conductive fine particles are used as the anisotropic conductive material, stable electrical connection can be maintained and the mechanical properties of the polymer particles can be sufficiently obtained. You can save it. When the thickness of the metal layer is 0.08 μm or more and 0.2 μm or less, the effect of using resin particles having a predetermined value or less of 0.25 to 0.70 μm in the present invention is preferable. .

  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.

  Further, the conductive fine particles of the present invention may have a smooth surface or an uneven shape. In the case where the conductive fine particles are used for the anisotropic conductive material, it is preferable to have a plurality of protrusions on the surface in that the binder resin can be effectively removed to connect to the electrode. By having the protrusion, connection reliability when the conductive fine particles are used for connection between the electrodes can be improved.

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 an 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, for example, thermoplastic resins such as acrylic resin, ethylene-vinyl acetate resin, styrene-butadiene block copolymer; monomers and oligomers having a glycidyl group, and curing agents 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. Average particle size <Drop size of monomer component in emulsion>
The particle size of 30000 droplets was measured in the range of 0.7 μm to 10 μm with a particle size distribution measuring device (“Coulter Multisizer III type” manufactured by Beckman Coulter, Inc.), and the volume average particle size was determined.
<Resin particles>
The particle size of 30000 particles was measured by a particle size distribution measuring device (“Coulter Multisizer III type” manufactured by Beckman Coulter, Inc.), and the number average particle size was determined.
<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. Fine particle content 0.05 parts of resin particles are mixed with 2.5 parts of a 10% aqueous solution of ether type nonionic surfactant (“Emulgen (registered trademark) 430” manufactured by Kao Corporation) and 15 parts of ion-exchanged water. A dispersion was prepared by ultrasonic dispersion in the solution. For ultrasonic dispersion, 2 L of water is placed in a tank (total volume of 9.5 L) of an ultrasonic cleaner, and a beaker containing 17.55 g of the dispersion is immersed therein, and ultrasonic waves (output 180 W, frequency 42 kHz) are used. Was irradiated for 10 min.
This dispersion was analyzed with a flow type particle image analyzer (manufactured by Sysmex Corporation, “FPIA-3000”) with a total count of 100,000, and a circularity of 0.95 or more and a range of 0.25 μm to 200 μm. The total particle number A (pieces) was determined.
Subsequently, the total number B (particles) of fine particles having a particle diameter of 0.25 μm or more and 0.70 μm or less was determined, and the particle content b (ppm) was determined by the following formula. Further, the total number C (particles) of particles having a particle diameter of more than 0.70 μm and D / 2 μm or less is obtained with the number average particle diameter of the resin particles being D, and the content c (ppm) of the particles is obtained by the following formula. It was.
Fine particle content b (ppm) = 1000000 × (B / A)
Particle content c (ppm) = 1000000 × (C / A)

1-3. Conductive metal layer thickness Using a flow-type particle image analyzer ("FPIA-3000", manufactured by Sysmex Corporation), the particle diameter of 3000 resin particles and 3000 conductive particles are measured. The number average particle diameter X (μm) 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

1-4. ACP test 20 parts by mass of conductive fine particles and 100 parts by mass of epoxy resin (manufactured by Mitsubishi Chemical, “JER828”) as a binder resin and 2 parts of a curing agent (manufactured by Sanshin Chemical Co., Ltd., “Sun-Aid (registered trademark) SI-150”) Part 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. The test piece 100 pieces were subjected to a continuity test to determine the presence or absence of a short, and the ratio of occurrence of the short was obtained and evaluated in three stages. Specifically, “A” indicates that no short occurred, “B” indicates that the short occurrence rate is less than 5%, and “C” indicates that the short occurrence rate is 5% or more.

2. 2. Production of conductive fine particles 2-1. Production Example 1
Resin particles In a four-necked flask equipped with a cooling tube, thermometer, and dropping port, 2200 parts of ion-exchanged water, 24 parts of 25% ammonia water, and 200 parts of methanol are placed, and 3-methacryloxypropyl is added from the dropping port with stirring. 100 parts of trimethoxysilane was added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane was performed to prepare an emulsion of polysiloxane particles (polymerizable polysiloxane particles) having a methacryloyl group. The number-based average dispersed particle size of the polysiloxane particles was 0.83 μm.

Next, 7.5 parts of a 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 300 parts of ion-exchanged water. In the dissolved solution, 150 parts of styrene, 150 parts of divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd., “DVB960”), 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: “ V-65 ") 4.5 parts dissolved solution was added, and using a high-speed emulsifying disperser (Primics Co., Ltd.," TK homomixer Mark II Model 2.5 "), the motor rotation speed was 8000 rpm and the stirring time was 5 minutes. Emulsified dispersion of monomer components was prepared by emulsifying and dispersing under conditions. When the droplet diameter of the monomer component in the obtained emulsion was measured, the volume average particle diameter was 3.55 μm.
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, 20 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ester ammonium salt was added, and the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and held at 65 ° C. for 2 hours. Radical polymerization was performed. 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 120 ° C. for 2 hours in a nitrogen atmosphere. 1 was obtained. This resin particle No. The number average particle size of No. 1 was 1.54 μm.

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, 10 parts of the catalyzed resin particles on which palladium nuclei were formed were added to 500 parts of ion-exchanged water and subjected to ultrasonic treatment for 10 minutes to sufficiently disperse the particles to obtain a fine particle suspension. Separately, nickel sulfate hexahydrate concentration is 50 g / L, sodium hypophosphite monohydrate concentration is 20 g / L, sodium citrate concentration is 50 g / L, and pH is 7.5 with aqueous sodium hydroxide. An electroless nickel plating solution adjusted to 1 was prepared. While stirring the fine particle suspension at 50 ° C., 100 parts of the electroless nickel plating solution was gradually added, and electroless nickel plating of the base particles was performed until the film thickness became 0.1 μm. After the nickel plating layer was formed, gold displacement plating was performed to form a 0.02 μm gold layer. Thereafter, after washing with ion-exchanged water, alcohol substitution was performed and vacuum drying was performed. 1 was obtained. Conductive fine particles No. As a result of dissolving the plating film 1 with aqua regia and analyzing with an inductively coupled plasma optical emission spectrometer (ICP, manufactured by Shimadzu Corporation: “ICPE-9000”), the phosphorus content in the nickel plating layer was 7.2%. there were.

2-2. Production Example 2
Resin particle Nos. Were prepared in the same manner as in Production Example 1 except that the monomer component emulsion was changed to a high-speed emulsification disperser with a motor speed of 10,000 rpm and a stirring time of 7 minutes. 2 was produced. The volume average particle size of the monomer component droplet size in the emulsion was 2.32 μm. This resin particle No. The number average particle size of No. 2 was 1.54 μm. 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
Resin particle Nos. Were prepared in the same manner as in Production Example 1 except that the emulsion preparation of the monomer component was changed to 4000 rpm for the motor speed of the high-speed emulsification disperser and 3 minutes for the stirring time. 3 was produced. The volume average particle size of the monomer component droplet size in the emulsion was 8.28 μm. This resin particle No. The number average particle size of No. 3 was 1.53 μm. 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
Resin particles No. 1 were prepared in the same manner as in Production Example 3 except that 100 parts of resin particles obtained after polymerization were subjected to ultrasonic dispersion by adding 400 parts of ion exchange water and then subjected to centrifugation at 2000 rpm for 5 minutes. 4 was produced. This resin particle No. 4 had a number average particle diameter of 1.54 μm. 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
Preparation apparatus and adjustment conditions for the emulsion of monomer components were changed to a high-speed emulsion disperser (Primics Co., Ltd. “TK homomixer Mark II Model 20”), the motor rotation speed was 8000 rpm, and the stirring time was changed to 10 minutes. Except that, the resin particle No. 5 was produced. The volume average particle size of the monomer component droplet size in the emulsion was 1.10 μm. This resin particle No. The number average particle size of No. 5 was 1.55 μm. 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
Resin particles In a four-necked flask equipped with a condenser, thermometer, and dripping port, are charged 2000 parts of ion-exchanged water, 24 parts of 25% aqueous ammonia, and 400 parts of methanol, and 3-methacryloxypropyl from the dripping port with stirring. 100 parts of trimethoxysilane was added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane was performed to prepare an emulsion of polysiloxane particles (polymerizable polysiloxane particles) having a methacryloyl group. The number-based average dispersed particle size of the polysiloxane particles was 1.02 μm.

Next, 7.5 parts of a 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 300 parts of ion-exchanged water. In the dissolved solution, 250 parts of styrene, 250 parts of divinylbenzene (“DVB960” manufactured by Nippon Steel Chemical Co., Ltd.), 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd .: “ V-65 ") A solution in which 7.5 parts were dissolved was added, and a high-speed emulsification disperser (Primics Co., Ltd.," TK homomixer Mark II Model 2.5 ") was used. The motor rotation speed was 10,000 rpm and the stirring time was 10 minutes. Emulsified dispersion of monomer components was prepared by emulsifying and dispersing under conditions. When the droplet diameter of the monomer component in the obtained emulsion was measured, the volume average particle diameter was 2.45 μm.
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, 30 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt was added, and the reaction solution was heated to 65 ° C. under a nitrogen atmosphere and held at 65 ° C. for 2 hours. Radical polymerization was performed. 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 120 ° C. for 2 hours in a nitrogen atmosphere. 6 was obtained. This resin particle No. The number average particle size of 6 was 2.15 μm. 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
Resin particle No. obtained in Production Example 2 2 was 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, 10 parts of the catalyzed resin particles on which palladium nuclei were formed were added to 500 parts of ion-exchanged water and subjected to ultrasonic treatment for 10 minutes to sufficiently disperse the particles to obtain a fine particle suspension. Separately, nickel sulfate hexahydrate concentration is 50 g / L, sodium hypophosphite monohydrate concentration is 20 g / L, sodium citrate concentration is 50 g / L, and pH is 11.0 with sodium hydroxide aqueous solution. An electroless nickel plating solution adjusted to 1 was prepared. While stirring the fine particle suspension at 50 ° C., 100 parts of electroless nickel plating solution was gradually added, and electroless nickel plating of the base particles was performed until the film thickness became 0.1 μm. After the nickel plating layer was formed, gold displacement plating was performed to form a 0.02 μm gold layer. Thereafter, after washing with ion-exchanged water, alcohol substitution was performed and vacuum drying was performed. 7 was obtained. Conductive fine particles No. 7 was dissolved with aqua regia and analyzed with an inductively coupled plasma emission spectrometer (ICP, manufactured by Shimadzu Corporation: “ICPE-9000”). As a result, the phosphorus content in the nickel plating layer was 3.8%. there were.

2-8. Production Example 8
Resin particle No. obtained in Production Example 5 5 was subjected to the same electroless plating as in Production Example 7 to obtain conductive fine particles.

  Table 1 shows the number average particle diameter and fine particle content of the base particles and the evaluation results of the conductive fine particles obtained in each production example.

The conductive fine particles of Production Examples 1, 2, and 5 to 8 contain fine particles having a resin particle number average particle diameter of 1.0 μm to 2.5 μm and a particle diameter of 0.25 μm to 0.70 μm. This is the case when the amount is 0.10% or less. All of the ACPs using these have a low occurrence rate of short circuit during electrical connection. Further, from the evaluation results of these conductive fine particles, the content of particles having a particle diameter of more than 0.70 μm and D / 2 μm or less (D is the number average particle diameter of resin particles) may not affect the occurrence rate of short circuit. Recognize.
Production Examples 3 and 4 are cases in which the fine particle content of the resin particles exceeds 0.10%, but in both cases, the occurrence rate of short-circuiting at the time of electrical connection is caused by the peeling of the fine particle plating layer during paste production. Became high.

  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 number average particle diameter of the resin particles is 1.0 μm to 2.5 μm, and the content (number basis) of fine particles having a particle diameter in the range of 0.25 μm to 0.70 μm is 0.10% or less. Conductive fine particles characterized in that.   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.   The number average particle diameter is 1.0 μm to 2.5 μm, and the content (number basis) of fine particles having a particle diameter in the range of 0.25 μm to 0.70 μm is 0.10% or less. Characteristic resin particles for conductive fine particle substrates.   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.