JP5583714B2 - 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 ensure good electrical conductivity when subjected to electrical connection despite a small particle diameter.

  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. Here, as the conductive fine particles used for the anisotropic conductive material, those obtained by coating the surfaces of the metal particles and the resin particles as the base material with a conductive metal layer are used. When an electrical connection is made with an anisotropic conductive material using such conductive particles, a sufficient contact area can be ensured for a connected body such as an electrode in order to obtain a stable connection resistance (conductivity). The idea of forming an indentation is made.

  By the way, in recent years, electronic devices have been increasingly reduced in size and functionality. Along with this, electronic components mounted on electronic devices have been miniaturized and high-density mounting has progressed, and electrodes and wirings in electronic circuits are becoming finer and narrower. Therefore, the conductive fine particles used for the anisotropic conductive material are also required to have a smaller particle diameter.

  As the conductive fine particles having a small particle diameter, for example, microspheres made of a resin or an inorganic compound and having an average particle diameter of 0.5 to 2.5 μm and a CV value of the particle diameter of 20% or less were used as a base material. Conductive fine particles have been proposed (Patent Document 1). In addition, it has been reported that in conductive particles obtained by subjecting a core made of an organic polymer to metal plating with a predetermined thickness, the hardness of the conductive particles from which good connection resistance is obtained depends on the diameter of the conductive particles. Among them, conductive particles having a particle diameter of 1 to 2 μm are disclosed (Patent Document 2).

JP 2000-30526 A JP 2003-323813 A

  However, when the particle size of the conductive fine particles is reduced, it becomes difficult to form an indentation that can secure a sufficient contact area on the connected body, and it tends to be difficult to obtain good conductivity. Therefore, as a method for forming a sufficient indentation, in the case of conductive fine particles having a small particle diameter, for example, it is conceivable to set the pressure at the time of pressure connection to be relatively high. However, in practice, when conductive particles having a small particle diameter are used and connected at a high pressure, even if the indentation forming ability is improved, the conductivity may be rather lowered.

  The present invention has been made in view of the above circumstances, and conductive fine particles that can ensure good electrical conductivity even when they are connected at a high pressure when they are electrically connected, while being fine conductive fine particles, An object is to provide an anisotropic conductive material using the same.

  The present inventors have intensively studied to solve the above problems. As a result, it was found that the conductive fine particles having a small particle diameter easily break when used for pressure connection at a high pressure, and that the breakage of the fine particles is a cause of the decrease in conductivity. If the resin particles exhibiting a behavior that does not show an inflection point in a compression displacement curve obtained in a predetermined compression test are used as a base material, a high pressure is required when electrically connecting the connected body while reducing the diameter. It has been found that good electrical conductivity can be secured even when connected, and the present invention has been completed.

That is, the conductive fine particles according to the present invention 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, and the average of the resin particles When a particle size is 1.0 μm to 2.5 μm, and a compression displacement curve showing a relationship between a load and a displacement amount in a compression direction is obtained in a compression test in which the resin particles are compressed at a load load rate of 2.2 mN / sec. In addition, the compression displacement curve is characterized by having no inflection point in a range where the displacement amount is 55% or less of the diameter of the resin particles. Furthermore, in the conductive fine particles of the present invention, it is preferable that the compression elastic modulus (10% K value) when the diameter of the resin particles is displaced by 10% is 10,000 N / mm ² or less.
In the present specification, the “inflection point” means a point where the amount of displacement in the compression direction of particles rapidly increases with respect to a minute amount of increase in load in a compression displacement curve obtained by a compression test.
The anisotropic conductive material according to the present invention is characterized in that the conductive fine particles of the present invention are dispersed in a binder resin.

  According to the conductive fine particles of the present invention, since the resin particles exhibit a behavior that does not show an inflection point in a compression displacement curve obtained by a predetermined compression test, the fine conductive particles are Good electrical conductivity can be ensured even if the connected body is electrically connected at a high pressure. Thereby, the effect that the electrical connection of the refined | miniaturized and narrowed electrode and wiring can be performed favorably is acquired.

It is a graph which shows the compression displacement curve obtained by using the resin particle (1) and (4) obtained by manufacture example 1 and 4 for a compression test.

1. Resin particles (base material)
The conductive fine particles of the present invention are composed of resin particles as a base material and at least one conductive metal layer formed on the surface of the base material.
The average particle diameter of the resin particles is a number-based average dispersed particle diameter of 1.0 μm or more, preferably 1.1 μm or more, more preferably 1.2 μm or more, and further preferably 1.3 μm or more. It is 5 μm or less, preferably 2.3 μm or less, more preferably 2.1 μm or less, and even more preferably 1.9 μm or less. The present invention aims to improve fine conductive fine particles, and if the average particle diameter of the resin particles (base material) is within the above range, fine conductive fine particles can be obtained and refined and narrowed. It can be suitably used for electrical connection of the formed electrodes and wiring.

The number-based variation coefficient (CV value) of the dispersed particle diameter of the resin particles (base material) is preferably 10.0% or less, more preferably 8.0% or less, and still more preferably 5.0. % Or less, more preferably 4.5% or less, particularly preferably 4.0% or less, and most preferably 3.0% or less. As described above, the resin particles having a small variation coefficient of the dispersed particle diameter are not only uniform in the primary particle diameter, but also have a very high monodispersibility of the primary particle diameter. Therefore, by using such resin particles as a base material, conductive fine particles having a uniform particle diameter and suppressed aggregation can be obtained.
The average dispersion particle diameter based on the number of resin particles in the present invention and the coefficient of variation thereof are values measured by a Coulter counter, and the measurement method will be described later in Examples.

  Furthermore, the resin particles are preferably those from which coarse particles have been removed. If coarse base particles are present, after forming a conductive metal layer, the coarse particles settle when stored as an anisotropic conductive material for a long period of time, causing aggregation of conductive fine particles. There is a fear. 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 particle diameter at the integrated value of 90% means the particle diameter at which the integrated value of the number is 90% in the number integrated distribution curve measured by a Coulter counter, like the average dispersed particle diameter.

  When the resin particle of the present invention obtains a compression displacement curve showing the relationship between the load and the displacement amount in the compression direction in a compression test in which the resin particle is compressed at a load load speed of 2.2 mN / sec, the compression displacement curve is Has no inflection point in the range of 55% or less of the diameter of the resin particles. If the resin particles exhibit such behavior, even when the particle diameter is small, it is possible to ensure good electrical conductivity during high-pressure connection. In the compression test, the resin particles are preferably not broken.

The resin particles preferably have a compressive elastic modulus (10% K value) of 10,000 N / mm ² or less when the diameter is displaced by 10% from the viewpoint of increasing the contact area with the electrode. More preferably, it is 9,000 N / mm < ² > or less, More preferably, it is 8,000 N / mm < ² > or less. When the 10% K value of the resin particles is too small, when forming a conductive metal layer to form conductive fine particles, or when dispersing in a binder resin or the like to form an anisotropic conductive material, etc. Since the resin particles may be deformed before being subjected to electrical connection and the conventional shape may not be maintained, the lower limit of the 10% K value of the resin particles is preferably 2,000 N / mm ² , more preferably 4,000 N. / Mm ² , more preferably 6,000 N / mm ² .

  The 10% K value of the resin particles can be measured by a compression test using a known fine compression tester, for example, a known fine compression tester (for example, “MCT-W500” manufactured by Shimadzu Corporation). In a compression test in which a load is applied at a load load rate of 2.2 mN / sec in the center direction of the particle at room temperature, the compression load (N) when the particle is deformed until the particle diameter is displaced by 10% The compression displacement (mm) can be measured and obtained based on the following formula.

（ここで、Ｅ：圧縮弾性率（Ｎ／ｍｍ²）、Ｆ：圧縮荷重（Ｎ）、Ｓ：圧縮変位（ｍｍ）、Ｒ：粒子の半径（ｍｍ）である。）

(Here, E: compression elastic modulus (N / mm ² ), F: compression load (N), S: compression displacement (mm), R: radius of particle (mm))

  Hereinafter, the components of the resin particles will be described. First, the resin particles may be particles composed only of an organic material such as a vinyl polymer, or an organic material such as a material (a composite material or the like) including a vinyl polymer and a polysiloxane skeleton. The particle | grains comprised with an inorganic composite material may be sufficient. For example, a resin particle composed of a material containing a vinyl polymer has an organic skeleton formed by polymerizing vinyl groups, and is excellent in elastic deformation during pressure connection. On the other hand, resin particles made of a material containing a polysiloxane skeleton are excellent in contact pressure with respect to the connected body during pressure connection. Therefore, resin particles composed of a material in which a polysiloxane skeleton and a vinyl polymer are combined are excellent in elastic deformation and contact pressure, and the connection reliability of the obtained conductive fine particles is further improved.

  As the monomer component constituting the resin particles, a vinyl monomer may be used to form an organic skeleton, and a silane monomer may be used to form a polysiloxane skeleton. Here, vinyl monomers are classified into vinyl crosslinkable monomers and vinyl noncrosslinkable monomers, and silane monomers are silane crosslinkable monomers and silane noncrosslinkable monomers. Divided into masses.

  The vinyl-based crosslinkable monomer has a vinyl group and can form a crosslinked structure, and specifically, a monomer (monomer having two or more vinyl groups in one molecule). (1)), or a monomer having one vinyl group and a functional group other than a vinyl group in one molecule (a proton functional group containing a carboxyl group, a hydroxy group or the like, or a terminal functional group such as an alkoxy group). Body (monomer (2)). However, in the case of the monomer (2), in order to form a crosslinked structure as a vinyl-based crosslinkable monomer, the reaction (bonding) of the carboxyl group, hydroxy group, alkoxy group, etc. of the monomer (2) The partner group must be present in the other monomer.

  In the present invention, the “vinyl group” means not only a carbon-carbon double bond but also a polymerizable carbon-like (meth) acryloyl group, allyl group, isopropenyl group, vinylphenyl group, isopropenylphenyl group. A substituent having a carbon double bond is also included. In the present specification, “(meth) acryloyl group”, “(meth) acrylate” and “(meth) acryl” are “acryloyl group and / or methacryloyl group”, “acrylate and / or methacrylate” and “acryl and "/ Or methacryl".

  Examples of the monomer (1) among the vinyl-based crosslinkable monomers include, for example, allyl (meth) acrylates such as allyl (meth) acrylate; ethylene glycol di (meth) acrylate, 1,4-butane Diol 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 ( ) Di (meth) acrylates such as polyalkylene glycol di (meth) acrylates such as polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate; trimethylol Tri (meth) acrylates such as propane tri (meth) acrylate; tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; hexa (meth) acrylates such as dipentaerythritol hexa (meth) acrylate; divinylbenzene , Divinylnaphthalene, and aromatic hydrocarbon-based crosslinking agents such as derivatives thereof (preferably styrenic polyfunctional monomers such as divinylbenzene); N, N-divinylaniline, divinyl ether , Divinyl sulfide, hetero atom-containing crosslinking agents such as divinyl sulfonic acid; and the like. Among these, (meth) acrylates (polyfunctional (meth) acrylate) having two or more (meth) acryloyl groups in one molecule and styrene polyfunctional monomers are preferable. Among the (meth) acrylates having two or more (meth) acryloyl groups in one molecule, (meth) acrylates having three or more (meth) acryloyl groups in one molecule are particularly preferable. Among these, acrylates having 3 or more acryloyl groups in one molecule are preferable. Among the styrenic polyfunctional monomers, monomers having two vinyl groups in one molecule such as divinylbenzene are preferable. A monomer (1) may be used independently and may use 2 or more types together.

  Examples of the monomer (2) among the vinyl-based crosslinkable monomers include, for example, monomers having a carboxyl group such as (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, 2- Monomers having hydroxy groups such as hydroxy group-containing (meth) acrylates such as hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate, hydroxy group-containing styrenes such as p-hydroxystyrene; 2-methoxy A single group having an alkoxy group such as an alkoxy group-containing (meth) acrylate such as ethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, or an alkoxystyrene such as p-methoxystyrene. And the like. A monomer (2) may be used independently and may use 2 or more types together.

The vinyl non-crosslinkable monomer is a monomer having one vinyl group in one molecule (monomer (3)) or other than the vinyl group possessed by the monomer (2). The monomer (2) when the other monomer which has a group which reacts with a functional group does not exist in a monomer component is mentioned.
Examples of the monomer (3) among the vinyl non-crosslinkable monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and 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 Alkyl (meth) acrylates such as (meth) acrylate and 2-ethylhexyl (meth) acrylate; cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate Cycloalkyl (meth) acrylates such as rate, cycloundecyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate; phenyl (meth) acrylate, benzyl Aromatic ring-containing (meth) acrylates such as (meth) acrylate, tolyl (meth) acrylate, phenethyl (meth) acrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p Styrene monofunctional monomers such as alkyl styrenes such as -t-butyl styrene and ethyl vinyl benzene, and halogen group-containing styrenes such as o-chloro styrene, m-chloro styrene and p-chloro styrene; Among these, it is preferable to use a (meth) acrylate monofunctional monomer or a styrene monofunctional monomer, and in the case of a (meth) acrylate monofunctional monomer, an alkyl (meth) acrylate such as methyl (meth) acrylate is more preferable. Of the monofunctional monomers, styrene is more preferable. A monomer (3) may be used independently and may use 2 or more types together.

  The vinyl polymer preferably includes the vinyl crosslinkable monomer (1) as a constituent component. Among them, the vinyl noncrosslinkable monomer (3) and the vinyl crosslinkable monomer are preferable. The aspect containing (1) is preferable. Specifically, an embodiment containing a monomer having two or more (meth) acryloyl groups in one molecule as a constituent component is preferable, and further, having two or more (meth) acryloyl groups in one molecule. An embodiment including a monomer and a styrene polyfunctional monomer, and an embodiment including a styrene monofunctional monomer and a monomer having two or more (meth) acryloyl groups in one molecule are preferable.

  The polysiloxane skeleton is formed by hydrolyzing a silane monomer and generating a siloxane bond by a condensation reaction. In particular, when a silane crosslinkable monomer is used as a silane monomer, a crosslinked structure is formed. Can do. Examples of the crosslinked structure formed by the silane-based crosslinking monomer include those that crosslink an organic polymer skeleton (for example, a vinyl polymer skeleton) and an organic polymer skeleton (first form); a polysiloxane skeleton; One that crosslinks a polysiloxane skeleton (second form); one that crosslinks an organic polymer skeleton and a polysiloxane skeleton (third form).

  Examples of the silane-based crosslinkable monomer that can form the first form include dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane. Examples of the silane crosslinkable monomer that can form the second form include tetrafunctional silane monomers such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane; methyltrimethoxy Examples thereof include trifunctional silane monomers such as silane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. Examples of silane-based crosslinkable monomers that can form the third form include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacrylic monomer. Having a (meth) acryloyl group such as loxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane; vinyltrimethoxysilane, Those having a vinyl group such as vinyltriethoxysilane and p-styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) Those having an epoxy group such as trimethoxysilane; 3-aminopropyltrimethoxysilane, those having an amino group such as 3-aminopropyltriethoxysilane; and the like. These silane crosslinking monomers may be used alone or in combination of two or more.

Examples of the silane-based non-crosslinkable monomer include bifunctional silane-based monomers such as dimethyldimethoxysilane and dialkylsilane such as dimethyldiethoxysilane; and trialkylsilanes such as trimethylmethoxysilane and trimethylethoxysilane. And monofunctional silane-based monomers. These silane non-crosslinkable monomers may be used alone or in combination of two or more.
In particular, the polysiloxane skeleton is preferably a skeleton derived from a polymerizable polysiloxane having a radical-polymerizable carbon-carbon double bond (for example, a vinyl group such as a (meth) acryloyl group). That is, the polysiloxane skeleton has, as a constituent component, a silane-based crosslinkable monomer (preferably having a (meth) acryloyl group, more preferably 3-methacryloxy) capable of forming the crosslinked structure of the third form. A polysiloxane skeleton formed by hydrolysis and condensation of propyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and vinyltrimethoxysilane) is preferable.

  In addition to the organic materials and organic-inorganic composite materials described above, the resin particles include, for example, polyolefin-based vinyl polymers such as polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyisobutylene, and polybutadiene; polyethylene terephthalate, Polyester such as polyethylene naphthalate; polycarbonate; polyamide; polyimide; phenol formaldehyde resin; melamine formaldehyde resin; melamine benzoguanamine formaldehyde resin; urea formaldehyde resin;

  In order for the resin particles not to have an inflection point in the compression displacement curve obtained in the compression test as described above, for example, the total amount of monomer components (100 What is necessary is just to adjust content of all the crosslinkable monomers (namely, the said vinyl type crosslinkable monomer and the said silane type crosslinkable monomer) with respect to (mass%) to 35 mass% or less. Thereby, it becomes the resin particle which does not have an inflection point also in the said compression test, and does not destroy. The content of the total crosslinkable monomer with respect to the total amount of the monomer components is more preferably 30% by mass or less, and further preferably 25% by mass or less. Thereby, it becomes the resin particle which does not destroy also in the above-mentioned compression test. However, if the content of the total crosslinkable monomer with respect to the total amount of the monomer components is too small, the 10% K value may not be controlled within a predetermined range. 5 mass% is preferable and, as for the minimum of content of all the crosslinkable monomers, 10 mass% is more preferable.

  Furthermore, in order for the resin particles not to have an inflection point in the compression displacement curve obtained by the compression test as described above, as the crosslinkable monomer, a silane crosslinkable monomer, and / Or a chain having two vinyl groups in one molecule and a main chain part in which 10 or more atoms are connected between carbon-carbon double bonds (C = C) of both vinyl groups. It is preferable to use a vinyl-based crosslinkable monomer having an intervening unit (hereinafter referred to as “specific vinyl-based crosslinkable monomer”). Silane-based crosslinkable monomers are preferable in that they can impart moderate hardness. Further, the specific vinyl-based crosslinkable monomer is preferable in that it can appropriately impart flexibility. The silane crosslinkable monomer and / or the specific vinyl crosslinkable monomer is preferably 80% by mass or more, more preferably 90% by mass or more, in 100% by mass of the total crosslinkable monomer. More preferably, it is 95% by mass or more, and particularly preferably 100% by mass.

  Moreover, when the monomer component which comprises the said resin particle contains a non-crosslinkable monomer, the said resin particle will not have an inflection point in the compression displacement curve obtained by the said compression test as mentioned above. Therefore, it is preferable to use a styrene monomer or a (meth) acrylate monomer as the non-crosslinkable monomer, and a (meth) acrylate monomer is more preferable. That is, a form in which the non-crosslinkable monomer is a (meth) acrylate monomer or a form in which a (meth) acrylate monomer and a styrene monomer are used in combination is preferable.

  In the specific vinyl-based crosslinkable monomer, the main chain portion in which 10 or more atoms are connected may be bonded to another branched chain, and the main chain portion does not form a ring. Absent. Preferably, the main chain portion is composed of a series of carbon atoms and / or oxygen atoms. The number of atoms constituting the main chain portion in the specific vinyl-based crosslinkable monomer is preferably 30 or less. It should be noted that the carbon atoms of the carbon-carbon double bond (C = C) itself are not counted in the number of atoms that continuously form the main chain portion. For example, in the case of 1,6-hexanediol dimethacrylate, the number of atoms that continuously form the main chain portion is 10, and in the case of triethylene glycol dimethacrylate, the number of atoms that continuously form the main chain portion. Is twelve.

  The shape of the resin particles (base material) is not particularly limited, and may be any of a spherical shape, a spheroid shape, a confetti shape, a thin plate shape, a needle shape, an eyebrow shape, etc., and a spherical shape is preferable. A true spherical shape is particularly preferable.

2. Conductive fine particles In the conductive fine particles of the present invention, at least one conductive metal layer is formed on the surface of the substrate (resin particles). 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 they become conductive fine particles having excellent conductivity. Further, in terms of inexpensiveness, nickel, nickel alloy (Ni-Au, Ni-Pd, Ni-Pd-Au, Ni-Ag, Ni-P, Ni-B, Ni-Zn, Ni-Sn, Ni-W, Ni—Co, Ni—W, Ni—Ti); copper, copper alloy (Cu and Fe, Co, Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, Ag, Alloy with at least one metal element selected from the group consisting of Au, Bi, Al, Mn, Mg, P, B, preferably an alloy with Ag, Ni, Sn, Zn); Silver, silver alloy (Ag And Fe, Co, Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, Ag, Au, Bi, Al, Mn, Mg, P, B An alloy with at least one metal element, preferably Ag-Ni, Ag-Sn, A -Zn); tin, tin alloy (for example, Sn-Ag, Sn-Cu, Sn-Cu-Ag, Sn-Zn, Sn-Sb, Sn-Bi-Ag, Sn-Bi-In, Sn-Au, Sn- Pb and the like) are preferable. Of these, nickel and nickel alloys are preferred. 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 0.010 μm or more, more preferably 0.030 μm or more, further preferably 0.050 μm or more, preferably 0.20 μm or less, more preferably 0.18 μm or less, More preferably, it is 0.15 micrometer or less, More preferably, it is 0.12 micrometer or less, Most preferably, it is 0.080 micrometer or less. In the conductive fine particles of the present invention in which the resin particles as the base material have a fine particle diameter, when the conductive metal layer has a thickness within the above range, the conductive fine particles are used as an anisotropic conductive material. Stable electrical connection can be maintained.

  The conductive metal layer only needs to cover at least a part of the surface of the resin particles, but the surface of the conductive metal layer has no substantial cracks or conductive metal layer. Is preferably absent. Here, “substantially cracked or a surface on which no conductive metal layer is formed” means that when the surface of any 10,000 conductive fine particles is observed using an electron microscope (magnification 1000 times), It means that the crack of the conductive metal layer and the exposure on the surface of the resin particles are not substantially visually observed.

  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, still more preferably 2.3 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.

  The number average particle size of the conductive fine particles was determined using a flow type particle image analyzer (“FPIA (registered trademark) -3000” manufactured by Sysmex Corporation), and was based on the number average particle size of 3000 particles. Is preferably adopted.

  The conductive fine particles of the present invention obtain a compression displacement curve showing the relationship between the load and the amount of displacement in the compression direction in a compression test similar to the resin particles described above, that is, a compression test in which compression is performed at a load load rate of 2.2 mN / sec. The compression displacement curve preferably has no inflection point in a range in which the displacement is 55% or less of the diameter of the resin particles. If the conductive fine particles themselves are particles exhibiting such behavior, even when the particle diameter is small, it is possible to ensure good conductivity during high-pressure connection. In addition, the judgment whether it has an inflection point can be performed similarly to the resin particle, for example.

The conductive fine particles of the present invention preferably have a compressive elasticity modulus (10% K value of the conductive fine particles) of 15,000 N / mm ² or less, more preferably 12,000 N when the diameter is displaced by 10%. / Mm ² or less, more preferably 9,000 N / mm ² or less. The 10% K value of the conductive fine particles is preferably 1,000 N / mm ² or more, more preferably 2,000 N / mm ² or more, and further preferably 3,000 N / mm ² or more. If the 10% K value of the conductive fine particles is within this range, even if the conductive fine particles are dispersed in a binder resin or the like in order to obtain an anisotropic conductive material, the conductive particles can maintain their original shape before being used for electrical connection. The 10% K value of the conductive fine particles can be measured in the same manner as the 10% K value of the resin particles.

  The conductive fine particles of the present invention may have an insulating resin layer on at least a part of the surface. That is, the aspect which provided the insulating resin layer further on the surface of the said electroconductive metal layer may be sufficient. When the insulating resin layer is further laminated on the conductive metal layer on the surface in this way, it is possible to prevent the lateral conduction that is likely to occur when a high-density circuit is formed or when a terminal is connected.

  The insulating resin layer is not particularly limited as long as the insulating property between the particles of the conductive fine particles can be secured, and the insulating resin layer can be easily collapsed or peeled off by a certain 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 cross-linked products thereof; epoxy resins, phenol resins, amino resins (melamine resins, etc.) And the like; and water-soluble resins such as polyvinyl alcohol and mixtures thereof.

  The insulating resin layer may be a single layer or a plurality of layers. For example, a single or a plurality of film-like layers may be formed, or a layer in which particles having insulating, granular, spherical, lump, scale or other shapes are attached to the surface of the conductive metal layer. Further, it may be a layer formed by chemically modifying the surface of the conductive metal layer, or a combination thereof. The thickness of the insulating resin layer is preferably 0.01 μm to 1 μm, more preferably 0.02 μm to 0.5 μm, still more preferably 0.03 μm to 0.4 μm. When the thickness of the insulating resin layer is within the above range, the electrical insulation between the particles becomes good while maintaining the conduction characteristics by the conductive particles.

3. Manufacturing method First, the manufacturing method of the said resin particle used as a base material is demonstrated.
The method for producing the resin particles is not particularly limited, and examples thereof include emulsion polymerization, suspension polymerization, dispersion polymerization, seed polymerization, sol-gel seed polymerization method, and the like. For example, a method in which resin particles are synthesized by seed polymerization and then classified is preferably employed. By employing a seed polymerization method for the synthesis of resin particles, resin particles having a small particle size distribution can be obtained. Furthermore, the average particle diameter can be adjusted to a desired range by classifying the synthesized resin particles and removing coarse particles.

The seed polymerization method is a method of obtaining resin particles through a seed particle preparation step, an absorption step in which the seed particle absorbs the monomer component, and a polymerization step in which the monomer component absorbed in the seed particle is polymerized. The method and conditions in each step are not particularly limited as long as a known seed polymerization method is appropriately employed. For example, the following methods are preferably employed.
In the seed particle preparation step, when synthesizing resin particles composed only of an organic material, the seed particles are prepared by a method such as soap-free emulsion polymerization or dispersion polymerization using the vinyl monomer. Good. In this case, it is preferable to use a styrene monofunctional monomer such as styrene as the vinyl monomer. On the other hand, when synthesizing particles composed of an organic material and a material having a polysiloxane skeleton, a solvent containing water (for example, alcohols, ketones, esters, ( The seed particles (polysiloxane particles) may be prepared by hydrolysis and condensation polymerization in a mixed solvent of an organic solvent such as cyclo) paraffins and aromatic hydrocarbons and water. In this case, it is preferable to use a silane crosslinkable monomer having a radical polymerizable group as the silane monomer to form polymerizable polysiloxane particles. In the hydrolysis and polycondensation, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst. If necessary, an anionic, cationic or nonionic surfactant or a polymer dispersant such as polyvinyl alcohol or polyvinylpyrrolidone can be used in combination.

  The method for absorbing the monomer component in the seed particles in the absorption step is not particularly limited. For example, the monomer component may be added to a seed particle dispersion in which the seed particles are previously dispersed in a solvent. The seed particles may be added to the solvent containing the monomer component. In particular, in the former method, the reaction solution obtained by polymerization, hydrolysis, or condensation may be used as a seed particle dispersion as it is. From the viewpoint of simplification and productivity. The monomer component may be added alone, or may be added as a solution dissolved in a solvent, but in order to efficiently absorb the seed particles, water or an aqueous medium ( For example, it is preferable to add as an emulsified liquid by emulsifying and dispersing in a water-soluble organic solvent such as alcohols, ketones and esters, or a mixed solvent of these with water).

When emulsifying and dispersing the monomer component with an emulsifier, examples of the emulsifier include anionic surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters. , Dispersion state of seed particles after nonionic surfactant such as polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene-oxypropylene block polymer absorbs seed particles and monomer components Is preferably used in that it can be stabilized. In addition, the amount of water or aqueous medium used for emulsification and dispersion is usually 0.3 to 10 times the mass of the monomer component.
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.

  The polymerization method employed in the polymerization step is not particularly limited, and for example, a known method such as a method using a radical polymerization initiator (for example, a peroxide-based initiator, an azo-based initiator, etc.) can be used. 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 tends to occur during the polymerization. There is. 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. If the reaction time is too short, the degree of polymerization may not be sufficiently increased, and if the reaction time is too long, aggregation tends to occur between particles. In such a polymerization step, when the seed particles are polymerizable polysiloxane particles, in the polymerization step, the absorbed monomer component and the radical polymerizable group of the polymerizable polysiloxane skeleton are polymerized, A polysiloxane skeleton and a vinyl polymer are combined.

  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 resin particles synthesized as described above are preferably subjected to classification so as to have a predetermined particle diameter. The classification method is not particularly limited, for example, sieving with an electroforming sieve, etc .; filtration using a filter such as a membrane filter, a pleat filter, a ceramic membrane filter, etc .; a known apparatus for classification by the interaction of mass difference and fluid resistance difference ( Gravity classifier based on the principle of gravity difference such as particle fall velocity, (half) free vortex centrifugal classification based on the balance of centrifugal force and air drag by free vortex or semi-free vortex, rotating classification blade (rotor) Classification using a centrifugal classification with rotating blades based on the balance between the centrifugal force generated by the generated rotating flow and the drag force caused by air. Among these, classification using an electric sieve is preferable from the viewpoint of classification accuracy and productivity.

  After the synthesis, the resin particles classified as necessary are usually dried and optionally subjected to firing. For baking, for example, if a large amount of silane-based crosslinking monomer is used, the condensation reaction of the silane-based crosslinking monomer may not sufficiently proceed at the post-polymerization stage. It is recommended to apply to the particles. Here, the conditions and method of the heat treatment such as drying and baking may be appropriately set according to a conventional method.

As described above, the resin particles have an average particle diameter (number-based average dispersed particle diameter) in the range of 1.0 μm or more and 2.5 μm or less, preferably in the range of the preferable average particle diameter as the base material particle described above. Prepared to satisfy.
Next, conductive fine particles are obtained by forming a conductive metal layer on the resin particles (base material) obtained as described above and further forming an insulating resin layer as necessary.
The formation method of the conductive metal layer and the formation method of the insulating resin layer are not particularly limited. For example, the conductive metal layer is plated on the substrate surface by an electroless plating method, an electrolytic plating method, or the like; Or a method of forming a conductive metal layer by a physical vapor deposition method such as vacuum vapor deposition, ion plating, or ion sputtering; 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.

4). Anisotropic conductive material The anisotropic conductive material of the present invention comprises the conductive fine particles of the present invention dispersed in a binder resin. The form of the anisotropic conductive material is not particularly limited, and examples thereof include various forms such as an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive, and an anisotropic conductive ink. By providing these anisotropic conductive materials between opposing substrates or between electrode terminals, good electrical connection can be achieved. 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 binder resin is not particularly limited as long as it is an insulating resin. For example, thermoplastic resins such as acrylic resins, ethylene-vinyl acetate resins, styrene-butadiene block copolymers; monomers and oligomers having a glycidyl group; Examples thereof include a curable resin composition that is cured by a reaction with a curing agent such as isocyanate; a curable resin composition that is cured by light or heat;
The anisotropic conductive material of the present invention can be obtained by dispersing the conductive fine particles of the present invention in the binder resin to obtain a desired form. For example, the binder resin and the conductive fine particles are separately provided. You may connect by making electroconductive fine particles exist with a binder resin between the base material to be used and connecting between electrode terminals.

  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. Physical property measurement method Various physical properties were measured by the following methods.
<Average particle diameter of seed particles and resin particles>
In the case of resin particles, 1% of polyoxyethylene alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd. “Hitenol (registered trademark) N-08”) as an emulsifier is added to 0.005 part of resin particles. A dispersion obtained by adding 20 parts of an aqueous solution and ultrasonically dispersing for 10 minutes is used as a measurement sample. In the case of seed particles, a dispersion obtained by hydrolysis and condensation reaction is added to a polyoxyethylene alkyl ether sulfate ammonium salt ( Using a sample diluted with a 1% aqueous solution of “Hitenol (registered trademark) N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as a measurement sample, using a particle size distribution analyzer (“Coulter Multisizer Type III” manufactured by Beckman Coulter, Inc.) The particle diameter (μm) of 30000 particles was measured, and the number-based average dispersed particle diameter was determined.

<Film thickness of conductive metal layer>
Using a flow type particle image analyzer (“FPIA (registered trademark) -3000” manufactured by Sysmex Corporation), the number average particle diameter X (μm) of 3000 base particles (resin particles) and the number of 3000 conductive fine particles The average particle size Y (μm) was measured. The measurement was performed by adding 17.5 parts of a 1.4% aqueous solution of polyoxyethylene oleyl ether (“Emulgen (registered trademark) 430” manufactured by Kao Corporation) as an emulsifier to 0.05 parts of the particles, After dispersing for 10 minutes. And the film thickness of the electroconductive metal layer was computed according to the following formula.
Conductive metal layer thickness (μm) = (Y−X) / 2

<10% K value and compressive fracture strength of resin particles>
Using a micro-compression tester (“MCT-W500” manufactured by Shimadzu Corporation), a circular flat plate indenter with a diameter of 50 μm is used for one particle dispersed on a sample stage (material: SKS flat plate) at room temperature (25 ° C.). Using (material: diamond), in the “standard surface detection” mode, a load was applied toward the center of the particle at a constant load speed (2.2295 mN / sec) and a maximum test force of 29.4 mN. Then, the load value (mN) when the diameter of the particle is displaced by 10% and the displacement amount (μm) at that time, and the load value (mN) when the particle breaks due to deformation and the displacement amount (μm) at that time Was measured. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value.
The 10% K value is obtained by converting the obtained load value (mN) into a compression load (N), converting the obtained displacement amount (μm) into a compression displacement (mm), and calculating the average particle diameter (μm) of the resin particles. ) Was used to calculate the particle radius (mm) and calculated based on the following formula.

（ここで、Ｅ：圧縮弾性率（Ｎ／ｍｍ²）、Ｆ：圧縮荷重（Ｎ）、Ｓ：圧縮変位（ｍｍ）、Ｒ：粒子の半径（ｍｍ）である。）
圧縮破壊強度は、粒子が破壊したときの荷重値（ｍＮ）である。

(Here, E: compression elastic modulus (N / mm ² ), F: compression load (N), S: compression displacement (mm), R: radius of particle (mm))
The compressive fracture strength is a load value (mN) when the particles are broken.

2. 2. Production of conductive fine particles 2-1. Preparation of substrate particles (resin particles) (Production Example 1)
In a four-necked flask equipped with a condenser, thermometer, and dripping port, add 2000 parts of ion-exchanged water, 24 parts of 25% aqueous ammonia, and 400 parts of methanol. 40 parts of 3-methacryloxypropyltrimethoxysilane is added as a forming monomer), and hydrolysis and condensation reactions of 3-methacryloxypropyltrimethoxysilane are performed to form polymerizable polysiloxane particles (seed particles) having a methacryloyl group. A dispersion was prepared. The number-based average dispersed particle size of the polysiloxane particles was 0.81 μm.

  Next, 6.0 parts of 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt ("Haitenol (registered trademark) NF-08" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier is dissolved in 240 parts of ion-exchanged water. In this solution, 240 parts of styrene as a monomer component (absorbing monomer) and 2.8 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) (“V-65” manufactured by Wako Pure Chemical Industries, Ltd.) A solution in which was dissolved was added and emulsified and dispersed to prepare an emulsion of the monomer component (absorption monomer). Two hours after the start of emulsification dispersion, the obtained emulsion was added to a dispersion 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 absorbed and absorbed.

  Next, 14.0 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 held 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 in a nitrogen atmosphere to obtain resin particles (1). The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In addition, FIG. 1 (solid line) shows a compression displacement curve obtained in a compression test (loading load speed: 2.2295 mN / sec) when a 10% K value is measured. As is clear from FIG. 1, in the case of the resin particle (1), no inflection point is observed when the displacement is 0% to 63% of the diameter of the resin particle.

(Production Example 2)
Resin particles (2) were obtained in the same manner as in Production Example 1 except that the type of absorption monomer was changed to methyl methacrylate. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In the case of the resin particle (2), no inflection point was observed when the displacement amount was 0% to 60% of the diameter of the resin particle.

(Production Example 3)
Resin particles (3) were obtained in the same manner as in Production Example 1 except that the type of absorbing monomer was changed to tertiary butyl methacrylate. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In the case of the resin particle (3), no inflection point was observed when the displacement amount was 0% to 60% of the diameter of the resin particle.

(Production Example 4)
In preparing a dispersion of polysiloxane particles (seed particles), the amount of ion-exchanged water used is 1800 parts, the amount of methanol used is 600 parts, the type and amount of absorbing monomer is 20 parts styrene, and divinylbenzene. ("DVB960" manufactured by Nippon Steel Chemical Co., Ltd .: 96% divinylbenzene, 4% vinyl non-crosslinkable monomer (ethyl vinylbenzene etc.) containing product) 80 parts, 100 parts 1,6-hexanediol diacrylate Resin particles (4) were obtained in the same manner as in Production Example 1 except that the drying was performed by vacuum drying at 120 ° C. for 2 hours in a nitrogen atmosphere. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In addition, FIG. 1 (broken line) shows a compression displacement curve obtained by a compression test (loading speed: 2.2295 mN / sec) when a 10% K value is measured. As is clear from FIG. 1, in the case of the resin particle (4), an inflection point is observed when the displacement is 52.8% of the diameter of the resin particle.

(Production Example 5)
Into a four-necked flask equipped with a condenser, thermometer, and dripping port, 1800 parts of ion-exchanged water, 24 parts of 25% ammonia water and 600 parts of methanol are placed under stirring and the monomer component (seed formation). 40 parts of 3-methacryloxypropyltrimethoxysilane is added as a monomer), and a hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane is performed to obtain a suspension of polysiloxane particles (seed particles) having a methacryloyl group. Was prepared. The number-based average dispersed particle size of the polysiloxane particles was 0.94 μm.

  Next, 3.0 parts of 20% aqueous solution of ammonium polyoxyethylene styrenated phenyl ether sulfate (Daiichi Kogyo Seiyaku Co., Ltd. "Hitenol (registered trademark) NF-08") as an emulsifier is diluted with 200 parts of ion-exchanged water. In this solution, 100 parts of styrene and 8 parts of 1,6-hexanediol dimethacrylate as monomer components (absorbing monomers), 2,2′-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd.) A solution in which 2.0 parts of "V-65" manufactured) was dissolved was added and emulsified and dispersed to prepare an emulsion of monomer components (absorbing monomers). Two hours after the start of the emulsification dispersion, the obtained emulsion was added to the suspension of the polysiloxane particles (seed particles) and further stirred. One hour after the addition of the emulsified liquid, the obtained mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were absorbed and absorbed.

  Next, 8.0 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“Hitenol (registered trademark) NF-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to the mixed solution, The temperature was raised to 65 ° C. and held at 65 ° C. for 2 hours to perform radical polymerization of the monomer component. The reaction solution (emulsion) after radical polymerization was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and methanol, and then vacuum-dried at 120 ° C. for 2 hours in a nitrogen atmosphere to obtain resin particles (5). Obtained. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In the case of the resin particles (5), no inflection point was observed when the displacement amount was 0% to 70% of the diameter of the resin particles.

(Production Example 6)
In a four-necked flask equipped with a condenser, a thermometer, and a dropping port, 200 parts of ion-exchanged water, 685 parts of ethanol, 12 parts of polyvinylpyrrolidone (“PVP K-30” manufactured by Wako Pure Chemical Industries, Ltd.), azobisiso Radical polymerization of monomer components by adding 2.1 parts of butyronitrile (AIBN) and 100 parts of styrene, stirring, raising the temperature to 70 ° C. under a nitrogen atmosphere, and holding at 70 ° C. for 6 hours Then, the mixture was cooled to room temperature to prepare a suspension of polystyrene particles (seed particles). The number-based average dispersed particle size of the polystyrene particles was 1.29 μm.

  Next, a solution obtained by diluting 25 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“HITENOL (registered trademark) NF-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier with 500 parts of ion-exchanged water. In addition, 200 parts of triethylene glycol dimethacrylate and 300 parts of 2-ethylhexyl methacrylate as monomer components (absorbing monomers) and 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd. “ V-65 ") 6 parts dissolved solution was added and emulsified and dispersed to prepare an emulsion of monomer component (absorbing monomer). The obtained emulsion was added to the suspension of polystyrene particles (seed particles) and further stirred. Three hours after the addition of the emulsified liquid, the obtained mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polystyrene particles absorbed the absorbing monomer and became enlarged.

  Next, 120 parts of a 10% aqueous solution of polyvinyl alcohol (“Poval (registered trademark) 205” manufactured by Kuraray Co., Ltd.) and 500 parts of ion-exchanged water are added to the mixture, and the temperature is raised to 65 ° C. in a nitrogen atmosphere. Was held for 2 hours to carry out radical polymerization of the monomer component. The reaction solution (emulsion) after radical polymerization was subjected to solid-liquid separation, and the obtained cake was washed with ion-exchanged water and methanol, and then vacuum-dried at 40 ° C. for 12 hours in a nitrogen atmosphere to obtain resin particles (6). Obtained. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In the case of the resin particles (6), no inflection point was observed when the displacement amount was 0% to 57% of the diameter of the resin particles.

(Production Example 7)
In a solution obtained by dissolving 10 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt ("Hytenol (registered trademark) NF-08" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier in 300 parts of ion-exchanged water, 100 parts of divinylbenzene (“DVB570” manufactured by Nippon Steel Chemical Co., Ltd .: 57% divinylbenzene and 43% vinyl non-crosslinkable monomer (ethylvinylbenzene etc.)) and 2,2′-azobis (2,4 -Dimethylvaleronitrile) (V-65, manufactured by Wako Pure Chemical Industries, Ltd.) in 2.0 parts was added, and the mixture was emulsified and dispersed to prepare an emulsion of monomer components. The obtained emulsified liquid is put into a four-necked flask equipped with a condenser, a thermometer, and a dripping port, diluted by adding 500 parts of ion-exchanged water, and the reaction liquid is heated to 65 ° C. under a nitrogen atmosphere. The mixture was held at 65 ° C. for 2 hours to carry out radical polymerization of the monomer component. The reaction solution (emulsion) after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol, then subjected to wet classification, and vacuum-dried at 120 ° C. for 2 hours to obtain resin particles ( 7) was obtained. The average particle diameter, 10% K value, and compressive fracture strength of the obtained resin particles were as shown in Table 1. In the case of the resin particle (7), an inflection point was observed when the displacement amount was 42.8% of the diameter of the resin particle.

2-2. Production of conductive fine particles (formation of conductive metal layer)
Example 1
The resin particles (1) used as a base material are subjected to etching treatment with sodium hydroxide, then sensitized by contacting with a tin dichloride solution, and then activated by immersing in a palladium dichloride solution. Palladium nuclei were formed by the method (sensitizing-activation method). Next, 2 parts of resin particles with palladium nuclei formed were added to 400 parts of ion-exchanged water, and after ultrasonic dispersion treatment, the resulting resin particle suspension was heated in a 70 ° C. hot bath. By adding 600 parts of electroless plating solution (“Schumar S680” manufactured by Nippon Kanisen Co., Ltd.) separately heated to 70 ° C. with the suspension heated in this way, an electroless nickel plating reaction occurs. I let you. After confirming that the generation of hydrogen gas was completed, solid-liquid separation was performed, followed by washing with ion-exchanged water and methanol in that order, and vacuum drying at 100 ° C. for 2 hours to obtain nickel-plated particles. Next, the obtained nickel plating particles were added to a displacement gold plating solution containing potassium gold cyanide, and gold plating was further performed on the surface of the nickel layer to obtain conductive fine particles. The film thickness of the conductive metal layer in the obtained conductive fine particles was as shown in Table 1.

(Examples 2-5, Comparative Examples 1-2)
Conductive fine particles were produced in the same manner as in Example 1 except that the resin particles shown in Table 1 were used as the substrate. The film thickness of the conductive metal layer in the obtained conductive fine particles was as shown in Table 1.

3. Preparation and Evaluation of Anisotropic Conductive Material Using conductive fine particles obtained in Examples and Comparative Examples, an anisotropic conductive material (anisotropic conductive film) was prepared by the following method, and the performance was evaluated by the following method. It was evaluated with.
That is, 1 part of conductive fine particles, 100 parts of an epoxy resin (“JER828” manufactured by Mitsubishi Chemical Corporation) as a binder resin, and 2 parts of a curing agent (“Sun Aid (registered trademark) SI-150” manufactured by Sanshin Chemical Co., Ltd.) Then, 100 parts of toluene was added, 50 parts of zirconia beads having a diameter of 1 mm were further added, and the mixture was stirred and dispersed at 300 rpm for 10 minutes using two stainless steel stirring blades. And the anisotropic conductive film was obtained by apply | coating and drying the obtained paste-form composition on PET film which gave the peeling process with the bar coater.

  The obtained anisotropic conductive film was sandwiched between an entire aluminum vapor-deposited glass substrate having resistance measurement lines and a polyimide film substrate having a copper pattern formed at a pitch of 20 μm, under pressure bonding conditions of 10 MPa and 150 ° C. Thermocompression bonding was performed. Then, measure the initial resistance value between the electrodes, connect when the initial resistance value A is 3Ω or less, connect when the connection resistance is “◎”, more than 3Ω and less than 5Ω, and connect when the connection resistance exceeds “O”, 5Ω. The resistance was evaluated as “x”.

  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 (3)

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 monomer component constituting the resin particles includes a crosslinking monomer of 33.3 mass% or less with respect to a total amount of 100 mass%,
The resin particles have an average particle size of 1.0 μm to 2.5 μm,
When a compression displacement curve showing the relationship between the load and the amount of displacement in the compression direction was obtained in a compression test in which the resin particles were compressed at a load load rate of 2.2 mN / sec, the amount of displacement was the resin particle Conductive fine particles characterized by having no inflection point in a range of 55% or less of the diameter. ^2. The conductive fine particle according to claim 1, wherein a compression elastic modulus (10% K value) when the diameter of the resin particle is displaced by 10% is 10,000 N / mm ² or less.   An anisotropic conductive material comprising the conductive fine particles according to claim 1 dispersed in a binder resin.

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