JP2014207193A - Electroconductive particulates and anisotropic electroconductive material using the same - Google Patents

Abstract

An object of the present invention is to provide conductive fine particles that are excellent in indentation forming ability and obtain a large connection area with a small pressure, and an anisotropic conductive material using the same.
The conductive fine particles of 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. The number average particle diameter is 2.4 μm or more, and the compression elastic modulus (10% K value) when the resin particles are displaced by 10% with respect to the diameter, the compression elastic modulus when the resin particles are displaced by 20% (20% K). Value), and the relationship between the compression elastic modulus (30% K value) when displaced by 30% satisfies the following formula: 10% K value> 20% K value> 30% K value, and 10% K value of the resin particles Is 7,000 N / mm ² or more.
[Selection figure] None

Description

TECHNICAL FIELD The present invention relates to conductive fine particles that are excellent in indentation forming ability and obtain a large connection area with a small pressure, and an anisotropic conductive material using the same.

  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.

  As the conductive fine particles used for anisotropic conductive connection, generally used are those in which resin particles are used as a base material and a conductive metal layer such as nickel is formed on the surface of the base material because of excellent compression deformability. Is done. The conductive fine particles are required to have various compressive deformation characteristics depending on the application, but the compressive deformation characteristics of the conductive fine particles are strongly influenced by the characteristics of the resin particles serving as the base material. Therefore, the importance of the resin particle design technology in increasing the functionality of the conductive fine particles is increasing.

In recent years, in the electrical connection between a large number of opposing electrodes and wirings, electronic components mounted on electrical devices have been downsized and mounted with high density, and the electrodes and wirings in electronic circuits have become even finer pitches. In the flow. As the fine pitch of electrodes and wirings in electronic circuits has progressed, the conductive fine particles used for anisotropic conductive materials can reliably achieve low-resistance electrical connection even with fine particle sizes. Is required.
As a method of increasing the connection area ratio, indentation forming ability (specifically, slightly deformed when connecting) so that the adhesion between the conductive metal layer and the connected body (electrode) is sufficiently maintained in the connected state. A method (for example, Patent Document 1) has been proposed that improves the characteristic of forming an indentation at the time.

In Patent Document 1, the resin particles used as the base material for the conductive fine particles are compressed when the diameter of the resin particles is displaced by 10% while the number-based average dispersed particle diameter is as fine as 1.0 μm to 2.5 μm. By setting the elastic modulus (10% K value) to 12,000 N / mm ² or more, it is possible to improve the indentation forming ability for the connection medium, and as a result, a sufficiently low initial resistance value can be expressed and stable connection can be achieved. Conductive fine particles capable of maintaining the state are disclosed.

  In addition, as electronic parts have become thinner, electrodes and wiring boards are shifting to thinner glass and polymer films, and the conductive fine particles used for anisotropic conductive materials have a lower pressure. However, it is also important to ensure a large connection area by deforming at a high deformation rate. As an effective means for obtaining such conductive fine particles, there is known a method of forming conductive fine particles having excellent flexibility by constituting base particles with highly flexible resin particles (Patent Document 2). .

Patent Document 2, the substrate to become the resin particles of the conductive fine particles, 10% K value is less than 50 kgf / mm ² or more 250 kgf / mm ^2, the recovery rate after compression deformation, and from 15 to 100% In particular, conductive fine particles having characteristics have been proposed. It is disclosed that the conductive fine particles have an appropriate compressive deformability and a deformation recovery rate, and therefore have excellent connection reliability.

International Publication WO2012 / 102199 Japanese Patent Fair 9-185069

In Patent Document 1, the number average dispersion particle diameter is 1.0 μm to 2.5 μm, and the compression elastic modulus (10% K value) when the diameter is displaced by 10% is 12,000 N. By using resin particles that are largely controlled at / mm ² or more as a base material, the ability to form indentations on the connection medium can be enhanced, and as a result, a sufficiently low initial resistance value can be exhibited and a stable connection state can be maintained. Conductive particulates that can be made are disclosed. However, in a larger particle diameter range, even if the 10% K value is increased to 12,000 N / mm ² or more, it is considered that the surface curvature decreases as the particle diameter increases. The present inventors have found that the diameter decreases compared to the case of diameter.

  In addition, the conductive fine particles proposed in Patent Document 2 are based on soft resin particles, and are excellent in securing a high deformation rate at a low pressure. However, since the hardness is too small, The indentation forming ability is not sufficient and the adhesion with the electrode surface is insufficient, and the resistance value may not be sufficiently reduced. Further, conventionally conductive fine particles having gold as the outermost layer of the conductive metal layer have been used in order to reduce the resistance value. However, in the trend of resource saving and cost reduction, it is necessary to develop conductive fine particles that can achieve low resistance even when the amount of gold used is reduced and the outermost layer is a base metal layer such as nickel or copper. The present invention has been made in view of the above circumstances, and even when the particle diameter is equal to or larger than a predetermined value, it has excellent indentation ability and has a large deformation ratio even at a low pressure, thereby ensuring a large connection area. It is an object to provide a conductive fine particle and an anisotropic conductive material using the same.

In order to solve the above-mentioned problems, the present inventor has intensively studied the influence of the compression deformation characteristics and particle diameter of the resin particles serving as the base material on the connection characteristics (particularly the electric resistance value) of the conductive fine particles. In the region where the average particle diameter of the resin particles as the substrate is 2.5 μm or less, if the compression elastic modulus (10% K value) when the compression rate is 10% is 12,000 N / mm ² or more, the indentation forming ability is excellent. Although it has already been proposed that a sufficiently low initial resistance value can be achieved, it can be seen that there is a limit to reducing the connection resistance value simply by increasing the 10% compression modulus in the region where the particle diameter is larger. I found out. Further, in the case of resin particles having a predetermined particle diameter or more, if the 10% K value is 12,000 N / mm ² or less but has a predetermined value or more, the compression ratio is higher (about 30%). By reducing the elastic modulus as the compressibility increases, the conductive fine particles having excellent indentation ability and a large deformation rate even at a low pressure can be obtained. The use of conductive fine particles for anisotropic conductive connection has found that it has excellent adhesion to a medium to be connected even at low pressure and can be connected with a large contact area, and a sufficiently low resistance connection can be obtained. did.

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 number of the resin particles The average particle diameter is 2.4 μm or more, and the compression elastic modulus (10% K value) when the resin particles are displaced by 10% relative to the diameter, the compression elastic modulus when the resin particles are displaced by 20% (20% K value). ), The relationship of the compression modulus (30% K value) when displaced by 30% satisfies the following formula: 10% K value> 20% K value> 30% K value, and the 10% K value of the resin particles is , 7,000 N / mm ² or more.

  In the conductive fine particles of the present invention, it is preferable that the compression rate at which the compression elastic modulus is minimized is 30% or more when measured in a range where the compression rate of the resin particles is 10 to 50% of the diameter. The resin particles are preferably vinyl polymer particles. The outermost layer of the conductive metal layer is preferably a nickel layer. 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 present invention, the number average particle diameter is 2.4 μm or more, and the relationship between the compressive elastic modulus at 10%, 20%, and 30% displacement is 10% K value> 20% K value> 30% K value. Resin particles that are satisfied and have a 10% K value controlled to be 7,000 N / mm ² or more are used as the base material of the conductive fine particles, so that they are excellent in indentation forming ability and large deformation even at low pressure. By having the ratio, the conductive fine particles can ensure a large connection area. By using the conductive fine particles, a stable conductive connection with a low connection resistance value is possible.

In the following description, unless otherwise specified, “%” means “% by mass”, “parts” means “parts by mass”, and “A to B” representing a range means “A or more and B or less”. To do.
The conductive fine particles of the present invention are composed of a base material made of resin and at least one conductive metal layer formed on the surface of the base material.

Resin particles (base material)
The resin particles in the present invention have a compressive modulus (10% K value) of 7000 N / mm ² or more when displaced by 10% with respect to the particle diameter. When the 10% K value of the resin particles is within the above range, when subjected to electrical connection, an indentation is easily formed on the surface of an electrode or the like as a connected medium at a stage where the compression rate is low. Therefore, a connection state with excellent adhesion to the electrode is obtained, and a stable connection resistance is easily obtained. If the 10% K value of the resin particles is less than 7000 N / mm ² , the indentation forming ability is insufficient, and stable connection may not be obtained. 10% K value of the resin particles is preferably 7500N / mm ² or more, more preferably 8000 N / mm ² or more, still more preferably 8250N / mm ² or more. On the other hand, the upper limit is not particularly limited, but if the 10% K value is too high, the electrode or the substrate may be damaged, preferably 20000 N / mm ² or less, more preferably 18000 N / mm ² or less, Preferably it is 17000 N / mm ² or less. In particular, when the 10% K value of the resin particles is in the range of 8500 N / mm ² or more and 15000 N / mm ² or less, an effect that a good indentation can be obtained without damaging the electrode and the substrate is obtained.

The resin particles in the present invention have a compressive elastic modulus (10% K value) when the diameter is displaced by 10%, a compressive elastic modulus (20% K value) when the diameter is displaced by 20%, and a compression when the diameter is displaced by 30%. The relationship of elastic modulus (30% K value) satisfies the following formula: 10% K value> 20% K value> 30% K value.

When the conductive fine particles are used as electrical contacts, it is usually preferable to connect in a state of a high compression rate (for example, about 30%) in order to ensure a large connection area. The compression rate is the ratio (percentage) of the amount of displacement displaced by compression to the particle diameter before compression. For example, a state where the compression rate is 30% is synonymous with a state where the state is displaced by 30% with respect to the diameter.
By using the resin particles satisfying the above relation as a base material, a high compression rate state, that is, a large connection area can be easily secured and a low resistance connection can be easily obtained, and the compression rate is high. However, since an excessive pressure is not exerted between the conductive fine particles serving as the electrical contacts and the connected medium, the distance between the connections is kept stable, and the connection resistance value is likely to be kept constant. Further, even when the connected medium is a thin film glass or polymer film as a substrate, deformation of the substrate and generation of cracks are easily suppressed.

When the 10% K value is within the above range, strong adhesion to the electrode is ensured, and further, the above relational expression is satisfied, so that the state of high compression rate, that is, the connection state with a large contact area is stably maintained. Will be.
Furthermore, it is preferable that the resin particles in the present invention have a compression modulus of 30% or more when the compression modulus is minimized when the compression modulus is measured in a range of 10 to 50%. By using conductive fine particles based on such resin particles, stable connection with a higher compressibility, that is, with a larger contact area is possible. It is easy to obtain a high conductive connection. The upper limit of the compression rate at which the compression modulus is minimized is not particularly limited, but is preferably 50% or less from the viewpoint of effectively expanding the contact area.

The value of the 30% K value of the resin particles in the present invention is not particularly limited, but is preferably 2000 N / mm ² or more from the viewpoint of achieving both the exclusion property of the binder resin and a wide contact area with the electrode. . More preferably at 2500N / mm ² or more, still more preferably 2700N / mm ² or more. On the other hand, the upper limit is preferably 7000 N / mm ² or less from the viewpoint of obtaining a wide contact area with the electrode. More preferably at 6500N / mm ^2, more preferably not more than 6000 N / mm ^2.

  Further, the ratio of the 30% K value to the 10% K value (30% K value / 10% K value) of the resin particles in the present invention is not particularly limited, but both indentation and a wide contact area with the electrode are achieved. From the viewpoint, it is preferably 0.3 or more. More preferably, it is 0.32 or more, More preferably, it is 0.35 or more. On the other hand, the upper limit is preferably 0.90 or less. More preferably, it is 0.80 or less, More preferably, it is 0.75 or less.

  The compression elastic modulus at each compression rate such as 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, Shimadzu). In a compression test in which a load is applied at a load load rate of 2.2295 mN / sec at room temperature at a room temperature using a mill (“MCT-W500”, etc.), the particles are deformed until they are displaced by 10% with respect to the particle diameter. Compressive load (N) and compression displacement (mm) at the time of measurement can be measured and obtained based on the following formula. In addition, it is preferable to perform the said measurement at room temperature, More specifically, it is preferable to perform in 25 degreeC constant temperature atmosphere.

（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))

The number average particle diameter of the resin particles in the present invention is 2.4 μm or more. If the number average particle diameter of the resin particles is within the above range, different kinds of anisotropic conductive paste, anisotropic conductive film, anisotropic conductive adhesive, anisotropic conductive ink, etc. required for a wide range of applications. It can be applied to an isotropic conductive material. The upper limit is not particularly limited, but is preferably 50 μm or less, more preferably 25 μm or less, still more preferably 12 μm or less, and particularly preferably 9 μm or less from the viewpoint that the effects of the present invention are remarkably exhibited. If the number average particle diameter of the resin particles is within the above range, it can be suitably used for electrical connection of electrodes and wiring in semiconductor mounting used for, for example, touch panels and LEDs.

Furthermore, when the conductive fine particles are fine (specifically, the number average particle diameter is 6 μm or less), the effect of the present invention becomes more remarkable. Therefore, the number average particle diameter of the resin particles is preferably 5.0 μm or less, more preferably 4.0 μm or less, still more preferably 3.5 μm or less, and even more preferably 3.2 μm or less.
Further, the lower limit is preferably 2.5 μm or more, more preferably 2.55 μm or more, and further preferably 2 from the viewpoint of securing a contact area with an electrode that can provide good conductivity even with a metal having low electrical conductivity. .6 μm or more.

  The number-based variation coefficient (CV value) of the resin particles is preferably 10.0% or less, more preferably 8.0% or less, still more preferably 5.0% or less, and still more preferably. It is 4.0% or less, particularly preferably 3.0% or less. As described above, the resin particles having a small variation coefficient of the particle diameter not only have the same 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 lower limit of the CV value of the resin particles is usually 0.5% or more.

  In addition, the number average particle diameter and the coefficient of variation of the particle diameter of the resin particle in the present invention are values measured by a Coulter counter method, and the measurement method will be described later in Examples.

  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.

The material which comprises the resin particle in this invention is not specifically limited. For example, amino resins such as melamine formaldehyde resin, melamine-benzoguanamine-formaldehyde resin, urea formaldehyde resin; vinyl polymers such as styrene resin, acrylic resin, styrene-acrylic resin; polyethylene, polypropylene, polyvinyl chloride, polytetrafluoro Polyolefins such as ethylene, polyisobutylene, and polybutadiene; polyesters such as polyethylene terephthalate and polyethylene naphthalate; polycarbonates; polyamides; polyimides; phenol formaldehyde resin; The material which comprises these resin particles may be used independently, and 2 or more types may be used together.
Among these, a vinyl polymer and an organopolysiloxane are preferable, and a vinyl polymer is particularly preferable because the resin particles having the above-described compression deformation characteristics are easily obtained. That is, as the resin particles, particles containing a vinyl polymer (also referred to as vinyl polymer particles) and particles containing an organopolysiloxane (also referred to as organopolysiloxane particles) are preferable, and particles including a vinyl polymer are particularly preferable.

  As the vinyl polymer particles, both particles made of only a vinyl polymer and particles made of a vinyl polymer and other components other than the vinyl polymer are preferable. The other component is preferably a polysiloxane component. The vinyl polymer referred to in the present invention includes all those formed by polymerizing (radical polymerization) vinyl monomers (vinyl group-containing monomers). On the other hand, the polysiloxane component is a component having a polysiloxane skeleton, and the polysiloxane skeleton can be formed by (hydrolysis) condensation of a silane monomer.

  Therefore, the vinyl polymer particles can be obtained by polymerizing a monomer containing a vinyl monomer, but in a preferred embodiment, the monomer used as a raw material is only a vinyl monomer. Further, a silane monomer may be used. When a silane monomer is used, vinyl polymer particles having a polysiloxane component can be obtained by condensation or hydrolysis and condensation.

  Furthermore, the resin particles in the present invention are not particularly limited in terms of structure as long as they have the above-described compression deformation characteristics, but those made into vinyl polymer particles having a specific core-shell structure have the above-described compression deformation characteristics. It is preferable because excellent resin particles are easily obtained. That is, as a preferred embodiment of the resin particles in the present invention, the resin particle has a core-shell structure composed of a core and a shell covering the core, the core has a form with a high hardness of a predetermined value or more, and the shell is specified. Examples include a form containing a vinyl polymer (hereinafter also referred to as core-shell type vinyl polymer particles).

The core-shell type vinyl polymer particles will be described.
In the core-shell type vinyl polymer particles, the core preferably has a compressive elastic modulus (10% K value) of 14,000 N / mm ² or more when displaced by 10% with respect to the core diameter.
The material for such a core is not limited, but is preferably composed of a vinyl polymer-containing form or organopolysiloxane, and includes a vinyl polymer from the viewpoint of easily forming a shell with a required thickness. More preferably, it is in the form.
Although details will be described later, when the core is in a form containing a vinyl polymer, a monomer component containing a vinyl monomer (if necessary, a silane monomer) is converted into a conventionally known polymerization method (silane). When using a monomer, it can be obtained by (hydrolysis and) condensation reaction). On the other hand, the shell preferably contains a vinyl polymer obtained by polymerizing a monomer component containing a specific vinyl monomer, which will be described in detail later.

<About the core>
In the present invention, the core preferably has a compressive elastic modulus (10% K value) of 14,000 N / mm ² or more when displaced by 10% with respect to the core diameter.
As described above, the core is preferably composed of a vinyl polymer-containing form or organopolysiloxane. First, a form containing a vinyl polymer will be described.
In the form in which the core contains a vinyl polymer, general monomers that can be used as monomer components constituting the core will be described. In addition, the monomer component which comprises a core is the meaning of the monomer component used as the raw material for forming a core, and shall have the same meaning about the same expression. For example, in the description of the shell, the monomer component constituting the shell means a monomer component that is a raw material for forming the shell.

  As the monomer component constituting the core, as long as the above-described conditions are satisfied, only a so-called vinyl monomer may be used, or a so-called silane monomer may be used in combination with the vinyl monomer. May be. When a vinyl monomer is used, a vinyl group is polymerized to form an organic skeleton, and the organic skeleton can exhibit excellent elastic deformation when connected under pressure. On the other hand, if a silane monomer is used, a polysiloxane skeleton is formed by condensation or hydrolysis / condensation reaction of the silane monomer to form a polysiloxane skeleton. On the other hand, a high contact pressure can be developed.

  Vinyl monomers are divided into vinyl crosslinkable monomers and vinyl noncrosslinkable monomers, and silane monomers are silane crosslinkable monomers and silane noncrosslinkable monomers. And divided. The vinyl monomers are classified into (meth) acrylic monomers, styrene monomers and other monomers as described later. 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".

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

Examples of the monomer (1) among the vinyl-based crosslinkable monomers include, for example, (meth) acrylic monomer (1), styrene monomer (1), and other monomers ( 1).
As the (meth) acrylic monomer (1), allyl (meth) acrylates such as allyl (meth) acrylate; ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1, Alkanediol di, such as 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,3-butanediol di (meth) acrylate (Meth) acrylate; diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentadeca ethylene Polyalkylene glycol di (meth) such as recall di (meth) acrylate, pentacontaector ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate ) Di (meth) acrylates such as acrylate; Tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate; Tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; Dipentaerythritol hexa (meth) ) Hexa (meth) acrylates such as acrylate.

Examples of the styrene monomer (1) include aromatic hydrocarbon crosslinking agents such as divinylbenzene, divinylnaphthalene, and derivatives thereof (preferably styrene polyfunctional monomers such as divinylbenzene).
Examples of the other monomer (1) include heteroatom-containing crosslinking agents such as N, N-divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfonic acid.
These monomers (1) may be used independently and may use 2 or more types together.

Examples of the monomer (2) among the vinyl crosslinking monomers include (meth) acrylic monomer (2) and styrene monomer (2).
Examples of the (meth) acrylic monomer (2) include (meth) acrylic acid, carboxymethyl (meth) acrylate, carboxyethyl (meth) acrylate, carboxypropyl (meth) acrylate, carboxybutyl (meth) acrylate, Monomers having a carboxy group such as carboxypentyl (meth) acrylate; hydroxy group-containing (meth) such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate Monomers having hydroxy groups such as acrylates; aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, aminobutyl (meth) acrylate, aminopentyl (meth) acrylate, etc. Minoalkyl (meth) acrylates, methylaminomethyl (meth) acrylate, ethylaminomethyl (meth) acrylate, methylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, methylaminopropyl (meth) acrylate, ethylaminopropyl Alkylaminoalkyl (meth) acrylates such as (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dialkylaminoalkyl such as diethylaminopropyl (meth) acrylate ( Monomers having an amino group such as (meth) acrylates; 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxy Examples include alkoxy group-containing (meth) acrylates such as siethyl (meth) acrylate.

Examples of the styrene monomer (2) include monomers having a hydroxy group such as hydroxy group-containing styrenes such as p-hydroxystyrene; monomers having an alkoxy group such as alkoxystyrenes such as p-methoxystyrene. Examples include a polymer.
These monomers (2) may be used alone or in combination of two or more.
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 (meth) acrylic monomer (3) and styrene monomer (3).
Examples of the (meth) acrylic monomer (3) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t- Butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, Alkyl (meth) acrylates such as dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth ) Acrylates, cyclooctyl (meth) acrylates, cycloundecyl (meth) acrylates, cyclododecyl (meth) acrylates, isobornyl (meth) acrylates, 4-tert-butylcyclohexyl (meth) acrylates and other cycloalkyl (meth) acrylates And aromatic ring-containing (meth) acrylates such as phenyl (meth) acrylate, benzyl (meth) acrylate, tolyl (meth) acrylate, and phenethyl (meth) acrylate.

  Examples of the styrene monomer (3) include alkyl styrenes such as styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, ethyl vinyl benzene, and pt-butyl styrene. Styrene monofunctional monomers such as halogen group-containing styrenes such as o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; These monomers (3) may be used independently and may use 2 or more types together.

  The silane crosslinkable monomer has two or more crosslinkable groups (alkoxy group, vinyl group, etc.) in the molecule, and an organic polymer skeleton (for example, a vinyl polymer skeleton) and an organic polymer. Forming a crosslinked structure (first form) with a skeleton; Forming a crosslinked structure (second form) between a polysiloxane skeleton and a polysiloxane skeleton; Organic polymer skeleton (for example, vinyl polymer skeleton) ) And a polysiloxane skeleton forming a crosslinked structure (third form). Of these, silane-based crosslinkable monomers capable of forming the third form of the crosslinked structure are preferred.

  Examples of the silane-based crosslinkable monomer that can form the first form include dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane. These silane crosslinking monomers may be used alone or in combination of two or more.

  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. These silane crosslinking monomers may be used alone or in combination of two or more.

  Examples of the silane-based crosslinkable monomer that can form the third form include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacrylate. 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. A silane type crosslinkable monomer may be used independently and may use 2 or more types together.

  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.

  As the monomer component constituting the core of the present invention (hereinafter also referred to as monomer A), it can be appropriately selected from the above-mentioned vinyl monomers and silane monomers, and is particularly limited. Although not done, the preferable form which comprises a core is demonstrated.

The core in the present invention preferably has a high degree of crosslinking represented by the following formula, specifically 70% or more.
Crosslinking degree (%) = (content of crosslinkable monomer / mass of monomer A) × 100
The degree of crosslinking, that is, the content of the crosslinkable monomer (hereinafter also referred to as crosslinkable monomer A) with respect to the total amount of monomer components (total amount of monomer A) constituting the core on a mass basis is 70% or more. It is preferable that the above 10% K value is easily secured.
In the core of the present invention, the degree of crosslinking is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more. The upper limit is not particularly limited, and may be 100%.

  The crosslinkable monomer A can be arbitrarily selected from the range of the exemplified vinyl crosslinkable monomer and silane crosslinkable monomer. Among these, the above-mentioned styrene crosslinkable monomer and / or silane crosslinkable monomer are preferably used. Among the styrenic crosslinkable monomers, a preferred monomer is divinylbenzene. Among the silane crosslinkable monomers, the silane crosslinkable monomer corresponding to the third form is preferable, those having a (meth) acryloyl group or an epoxy group are more preferable, and having a (meth) acryloyl group. More preferred. Among these, it is particularly preferable to use a silane crosslinkable monomer having a trifunctional (meth) acryloyl group. Examples of the silane-based crosslinkable monomer having a trifunctional (meth) acryloyl group include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3 -Acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane are mentioned. A form using only a styrene-based crosslinkable monomer as the crosslinkable monomer A and a form using a styrene-based crosslinkable monomer and a silane-based crosslinkable monomer together are one of preferred forms.

  In calculating the degree of crosslinking, the monomer (2) (styrene monomer (2), (meth) acrylic monomer (2), other monomer (2)) When another monomer having a group capable of reacting with a functional group other than the vinyl group contained in the body (2) is present in the monomer component, it is treated as a crosslinkable monomer A, and such a monomer. Is not included in the crosslinkable monomer A.

  In addition, when the said core contains a polysiloxane component, 1 mass part or more is preferable with respect to 100 mass parts of silane monomers, More preferably, 2 mass parts or more, More preferably, it is 5 mass parts or more, 1000 mass parts or less are preferable, More preferably, it is 500 mass parts or less, More preferably, it is 100 mass parts or less.

  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 a silane-based crosslinkable monomer (preferably having a (meth) acryloyl group) capable of forming at least the third form (crosslinking between vinyl polymer and polysiloxane) as a constituent component. More preferably, it is a polysiloxane skeleton formed by hydrolysis and condensation of 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane).

  When the core is an organopolysiloxane particle, the organopolysiloxane particle is one or two of silane monomers (silane crosslinkable monomer, silane noncrosslinkable monomer) that do not contain a vinyl group. What is necessary is just to be obtained by (co) hydrolytic condensation of the above. Examples of the silane monomer not containing a vinyl group include trifunctional silane monomers such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and phenyltrimethoxysilane. Di- or trialkoxysilanes having an epoxy group such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; Examples thereof include di- or trialkoxysilanes having an amino group such as propyltrimethoxysilane and 3-aminopropyltriethoxysilane.

10% K value of the core is preferably at 14,000N / mm ² or more, more preferably 16,000N / mm ² or more, whereas, the upper limit is not particularly limited, usually, 40,000 N / mm ² or less is preferable, more preferably 30,000 N / mm ² or less, and still more preferably 25,000 N / mm ² or less. By setting the 10% K value of the core within the above range, it becomes easy to control the 10% K value of the resin particles serving as the base material of the conductive fine particles of the present invention to the above-described preferable range. The 10% K value of the core can be measured by the same method as the 10% K value of the resin particles.

In the present invention, the variation coefficient of the particle diameter of the core is 10% or less, preferably 8% or less, more preferably 6% or less, and further preferably 5% or less. By reducing the coefficient of variation of the core, it is possible to suppress variations in mechanical characteristics when the conductive fine particles are formed. The lower limit of the coefficient of variation of the particle diameter of the core is not particularly limited, but is preferably 1% or more, more preferably 1.5% or more, and further preferably 2.0% or more.
In the present invention, the number average particle size of the core may be appropriately selected according to the particle size of the conductive fine particles and the resin particles as the base material, but it is usually preferably 0.5 μm or more and 49 μm or less. More preferably, it is 1.0 micrometer or more, More preferably, it is 1.5 micrometers or more. Further, it is more preferably 24 μm or less, and further preferably 10 μm or less.

In order to obtain resin particles used for fine conductive fine particles (number average particle diameter of 6 μm or less), the number average particle diameter of the core of the present invention is preferably 4.5 μm or less, more preferably 3.5 μm or less. More preferably, it is 3.0 μm or less, preferably 1.0 μm or more, more preferably 1.5 μm or more, and further preferably 1.8 μm or more.
The number average particle size of the core and the coefficient of variation of the particle size are values based on the number measured by a Coulter counter, as in the case of the resin particles, and the measurement method will be described later in the examples.

1-2. Shell In the core-shell type vinyl polymer particle which is a preferred form of the resin particle in the present invention, the shell is a specific vinyl monomer as a monomer component constituting the shell, that is, the formula (1)

（式中、Ｒ^１は水素原子またはメチル基、Ｒ^２は置換基を有していてもよい炭素数４以上の炭化水素基を表す）で表されるビニル系非架橋性単量体（以下、ビニル系単量体（Ｓ）ともいう）を含むことが好ましい。硬質なコアを被覆するシェルが、ビニル系単量体（Ｓ）を含む単量体成分の重合により形成されるビニル重合体を含むことにより、前述した圧縮変形特性を備えた樹脂粒子とすることができる。

(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrocarbon group having 4 or more carbon atoms which may have a substituent) (hereinafter referred to as a non-crosslinkable monomer) And a vinyl monomer (S)). The shell covering the hard core includes a vinyl polymer formed by polymerization of a monomer component containing a vinyl monomer (S), thereby forming resin particles having the above-described compression deformation characteristics. Can do.

As the monomer component constituting the shell (hereinafter also referred to as monomer B), other monomer components may be used as long as the vinyl monomer (S) described above is included. It can be appropriately selected from vinyl monomers and silane monomers, and is not particularly limited.
Examples of the vinyl monomer (S), the compound R ² is an alkyl group having 4 or more carbon atoms in the (1), R ² is compounds and R ² is a cycloalkyl group having 4 or more carbon atoms aromatic It is preferably at least one selected from the group consisting of compounds that are hydrocarbon groups containing a ring.

Examples of the compound in which R ² is an alkyl group having 4 or more carbon atoms include alkyl (meth) acrylates exemplified for the (meth) acrylic monomer (3), and alkyl having 4 or more carbon atoms in the alkyl chain. (Meth) acrylates (also referred to as alkyl (meth) acrylates having 4 or more carbon atoms) are preferably used. For example, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, Examples include octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like.

As the compound in which R ² is a cycloalkyl group having 4 or more carbon atoms, among the cycloalkyl (meth) acrylates exemplified in the (meth) acrylic monomer (3), the cycloalkyl chain has 4 carbon atoms. The above cycloalkyl (meth) acrylates (also referred to as cycloalkyl (meth) acrylates having 4 or more carbon atoms) are preferably used. For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cycloundecyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) ) Acrylate and the like.

As the compound in which R ² is a hydrocarbon group containing an aromatic ring, the aromatic ring-containing (meth) acrylates exemplified for the (meth) acrylic monomer (3) are preferably used. Examples thereof include phenyl (meth) acrylate, benzyl (meth) acrylate, tolyl (meth) acrylate, phenethyl (meth) acrylate, and the like.

  As described above, the vinyl monomer (S) is preferably an alkyl (meth) acrylate having 4 or more carbon atoms, a cycloalkyl (meth) acrylate having 4 or more carbon atoms, or an aromatic ring-containing (meth) acrylate. However, among these, alkyl (meth) acrylates having 4 or more carbon atoms or cycloalkyl (meth) acrylates having 4 or more carbon atoms are preferable. In particular, it is preferably selected from alkyl (meth) acrylates having branched alkyl chains and cycloalkyl (meth) acrylates because of its excellent effect of increasing the hardness of resin particles at the initial stage of compression deformation. Preferred examples of alkyl (meth) acrylates with branched alkyl chains include t-butyl (meth) acrylate, sec-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. . As the cycloalkyl (meth) acrylates, any of the above-described exemplary compounds can be preferably used. Among these, t-butyl (meth) acrylate and cycloalkyl (meth) acrylate are preferable.

  Although the content rate of a vinyl-type monomer (S) is not specifically limited, It is preferable that the content rate of this monomer is 30 mass% or more with respect to 100 mass% of monomer component total amount which forms a shell. More preferably, it is 40 mass% or more, More preferably, it is 50 mass% or more. The upper limit is not particularly limited and may be 100% by mass, but is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% by mass or less.

The shell in the present invention preferably contains a crosslinkable monomer from the viewpoint of imparting appropriate resilience characteristics, and the degree of crosslinking represented by the following formula is preferably in the range of 5% to 70%.
Crosslinking degree (%) = (content of crosslinkable monomer / mass of monomer B) × 100
The degree of crosslinking, that is, the content of the crosslinkable monomer (hereinafter also referred to as crosslinkable monomer B) relative to the total amount of monomer components (total amount of monomer B) constituting the shell on a mass basis is within the above range. It is particularly preferable that the relationship between the compression elastic moduli at the respective compression rates (10% K value> 20% K value> 30% K value) is easily secured. In the shell of the present invention, the degree of crosslinking is more preferably 10% or more and 60% or less, and further preferably 15% or more and 50% or less.

  The crosslinkable monomer B can be arbitrarily selected from the ranges of the vinyl crosslinkable monomer and the silane crosslinkable monomer exemplified above. In particular, it preferably contains a vinyl-based crosslinkable monomer. The content of the vinyl-based crosslinkable monomer is preferably 5% by mass or more and 70% by mass or less with respect to the total of 100% by mass of the monomer B. More preferably, it is 10 mass% or more, More preferably, it is 15 mass% or more, More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less. When the content of the vinyl-based crosslinkable monomer is within the above range, the resulting shell is excellent in solvent resistance and binder elimination.

In the calculation of the degree of crosslinking, the monomer (2) (the styrene monomer (2), the (meth) acrylic monomer (2)) is a vinyl group possessed by the monomer (2). In the case where another monomer having a group capable of reacting with other functional groups is present in the monomer component, it is treated as a crosslinkable monomer B, and in the absence of such a monomer, the crosslinkable monomer It is not included in the polymer B.
When the shell contains a polysiloxane component, the amount of the vinyl monomer used is preferably 100 parts by mass or more, more preferably 250 parts by mass or more, even more preferably 100 parts by mass of the silane monomer. Is 500 parts by mass or more, preferably 2000 parts by mass or less, more preferably 1500 parts by mass or less, and still more preferably 1200 parts by mass or less.
A preferable form of the polysiloxane skeleton (for example, a skeleton derived from a polymerizable polysiloxane having a radically polymerizable carbon-carbon double bond) is the same as that described in the case of the core.

Furthermore, the ratio of the shell thickness to the core diameter (shell thickness / core diameter) is preferably 5/100 or more and 50/100 or less. Within such a range, the characteristics of the core particles and the characteristics of the shell are easily combined. More preferably, they are 10/100 or more and 40/100 or less.
In the present invention, the thickness of the shell is, for example, preferably 100 nm or more, more preferably 150 nm or more, and further preferably 200 nm or more. Moreover, 5000 nm or less is preferable, More preferably, it is 2500 nm or less, More preferably, it is 1000 nm or less.

  In the present invention, the preferred embodiments such as the particle shape of the core-shell type vinyl polymer particles, the number average particle size, the CV value (variation coefficient) of the particle size, and the compression deformation characteristics such as the compression elastic modulus are described for the resin particles. This is the same as the range.

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).

2-1. Conductive metal layer 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-phosphorus, 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, Au, Bi, Al, Mn, Mg, P, B Alloy with one metal element, preferably Ag-Ni, Ag-Sn, Ag-Z ); 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, etc.) Etc.) are preferred.

  The conductive metal layer preferably has at least a nickel layer from the viewpoint of conductivity and connection reliability. The nickel layer may be a single layer or may be a laminate of a plurality of layers having different crystal structures and alloy compositions. Further, from the viewpoint of connection reliability, the outermost layer is preferably a nickel layer. In the conductive fine particles of the present invention, even when the conductive metal layer is composed of a nickel layer as the outermost layer, connection with a sufficiently low resistance is likely to be possible. Furthermore, it is preferable that it consists only of a nickel layer from a viewpoint of manufacturing cost suppression.

  The nickel layer may be formed directly on the base particle, or another conductive metal layer may be formed on the base particle surface as a base, and the nickel layer may be formed thereon. It is preferable to form directly on. In addition, the nickel layer as used in the field of this invention means the layer comprised from nickel or a nickel alloy. When a nickel alloy is used, the nickel content in the nickel alloy is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. As the nickel alloy constituting the nickel layer, among the nickel alloys described above, a Ni—P alloy and a Ni—B alloy are preferable from the viewpoint of being excellent in both dispersibility of the conductive fine particles and conductivity.

  The P (phosphorus) concentration in the Ni-P alloy is preferably 15% by mass or less, more preferably 10% by mass or less. The lower the P concentration, the lower the electrical resistance value of the nickel layer. On the other hand, when the P concentration is too low, aggregation due to magnetism occurs, and the conductive fine particles tend to be difficult to disperse into the primary particles. Therefore, the P concentration is preferably 2% by mass or more, more preferably 3% by mass or more. The P concentration is preferably 10% by mass or less from the viewpoint of particularly excellent compression deformability at low pressure. The P concentration is the ratio of P mass to the total mass of Ni and P in the nickel alloy (P / (P + Ni)).

  The B (boron) concentration in the Ni-B alloy is preferably 7% by mass or less, more preferably 5% by mass or less. The lower the B concentration, the lower the electrical resistance value of the nickel layer. On the other hand, when the B concentration is too low, aggregation due to magnetism occurs, and the conductive fine particles tend to be difficult to disperse into the primary particles. Therefore, the B concentration is preferably 1.0% by mass or more, and more preferably 1.5% by mass or more. The conductive fine particles of the present invention are excellent in flexibility because they use highly flexible resin particles, but the B concentration is preferably 2.0% by mass or more from the viewpoint of excellent flexibility. The B concentration is a ratio of B mass to the total mass of Ni and B in the nickel alloy (B / (B + Ni)).

  On the other hand, when high conductivity is required, the outermost layer is preferably a metal layer composed of gold, palladium or silver, has a nickel layer on the substrate surface, and further composed of gold, palladium or silver. A form in which the metal layers to be laminated is also a more preferable form. In the laminated form, the form in which the metal element composing another conductive metal layer such as gold or palladium forms a metal layer (including an alloyed layer) mixed with nickel element is also used. This is one of the preferred forms. For example, when gold plating is performed after the nickel layer is formed, at least a part of nickel atoms constituting the nickel layer is replaced with gold, so that the conductive metal layer as described above is included. It becomes a form.

  The thickness of the conductive metal layer is preferably 0.010 μm or more, more preferably 0.030 μm or more, still more preferably 0.050 μm or more, preferably 0.30 μm or less, more preferably 0.25 μm or less, More preferably, it is 0.20 micrometer or less, More preferably, it is 0.15 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 thickness of the conductive metal layer can be measured, for example, by a method described later in Examples.

  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 the conductive metal layer is not formed” means that the surface of any 10,000 conductive fine particles is observed using a scanning electron microscope (magnification 1000 times). Furthermore, it means that the crack of the conductive metal layer and the exposure of the resin particle surface are not substantially visually observed.

  In addition, although the thickness of the said nickel layer is not specifically limited, For the same reason as the thickness of the said electroconductive metal layer, 0.005 micrometer or more and 0.3 micrometer or less are preferable. More preferably, it is 0.01 micrometer or more, More preferably, it is 0.05 micrometer or more, More preferably, it is 0.07 micrometer or more. The upper limit side is more preferably 0.25 μm or less, further preferably 0.2 μm or less, and still more preferably 0.12 μm or less.

2-2. Conductive fine particles The number average particle diameter of the conductive fine particles of the present invention is preferably 51 μm or less, more preferably 26 μm or less, still more preferably 13 μm or less, and even more preferably 10 μm or less.
Furthermore, when the conductive fine particles are fine (specifically, the number average particle diameter is 6 μm or less), the effect of the present invention becomes more remarkable. Therefore, the number average particle diameter is preferably 6.0 μm or less, more preferably 5.0 μm or less, still more preferably 4.0 μm or less, and even more preferably 3.5 μm or less.

Further, the lower limit is preferably 2.5 μm or more, more preferably 2.6 μm or more, and further preferably 2 from the viewpoint of securing a contact area with an electrode that can provide good conductivity even with a metal having low electrical conductivity. .65 μm or more.
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 may have a smooth surface or an uneven shape, but preferably have a plurality of protrusions from the viewpoint 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.

  As a method of forming protrusions on the surface of the conductive fine particles, (1) after obtaining base particles having protrusions on the surface using a phase separation phenomenon of a polymer in a polymerization step in base particle synthesis A method of forming a conductive metal layer by electroless plating; (2) electroless after depositing inorganic particles such as metal particles and metal oxide particles or organic particles made of an organic polymer on the surface of the substrate particles; A method of forming a conductive metal layer by plating; (3) after performing electroless plating on the surface of the substrate particles, and attaching organic particles made of inorganic particles or organic polymers such as metal particles and metal oxide particles; (4) Utilizing the self-decomposition of the plating bath during the electroless plating reaction, depositing a metal that forms the core of the protrusion on the surface of the substrate particles, and further performing the electroless plating , Protrusion How the conductive metal layer to form a conductive metal layer which becomes continuous film comprising; and the like.

  The height of the protrusion is preferably 20 nm to 1000 nm, more preferably 30 nm to 800 nm, still more preferably 40 nm to 600 nm, and particularly preferably 50 nm to 500 nm. When the height of the protrusion is within the above range, the connection reliability is further improved. The height of the protrusion is determined by observing 10 arbitrary conductive fine particles with an electron microscope. Specifically, for the protrusions on the periphery of the conductive fine particles to be observed, the height of any ten protrusions per conductive fine particle is measured, and the measured value is obtained by arithmetic averaging. The number of the protrusions is not particularly limited, but preferably has at least one protrusion on any orthographic projection surface when the surface of the conductive fine particles is observed with an electron microscope from the viewpoint of ensuring high connection reliability. , More preferably 5 or more, still more preferably 10 or more.

  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. However, when the insulating resin layer is too hard compared to the base particle, the base particle itself 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, 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. Production Method As a production method example of the resin particles of the present invention, a preferred method for producing core-shell type vinyl polymer particles will be described. The resin particles of the present invention are not limited to core-shell type vinyl polymer particles. For example, vinyl polymer particles that are not of the core-shell type can be produced according to the core forming method described below.
As a manufacturing method of core-shell type vinyl polymer particles, a core is formed, and then a shell is formed so as to cover the core.

3-1. Core production method The core production method is not particularly limited as long as the above-described core monomer component is polymerized. Emulsion polymerization method, suspension polymerization method, dispersion polymerization method, first seed polymerization method A conventionally known method such as a sol-gel seed polymerization method can be employed. For example, a method of synthesizing the core by the first seed polymerization method is preferably employed in that the core particle diameter can be easily controlled and a core having a small particle size distribution is easily obtained.

  The first seed polymerization method obtains a core through a seed particle preparation step, an absorption step in which the core monomer component is absorbed in the seed particle, and a polymerization step in which the core monomer component absorbed in the seed particle is polymerized. Is the method. 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 the silane crosslinkable monomer corresponding to the crosslinkable monomer 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 causing the seed particles to absorb the core monomer component in the absorption step is not particularly limited. For example, the core monomer component may be added to a seed particle dispersion in which the seed particles are previously dispersed in a solvent. Alternatively, seed particles may be added to the solvent containing the core monomer component. In particular, in the former method, the reaction solution obtained by polymerization, hydrolysis, or condensation is used as a seed particle dispersion as it is. However, it is preferable from the viewpoint of simplification of the process and productivity. The core monomer component may be added alone or as a solution dissolved in a solvent. However, in order to efficiently absorb the seed particles, water or an aqueous medium is used in advance using an emulsifier. It is preferable to add as an emulsified liquid by emulsifying and dispersing in (for example, a water-soluble organic solvent such as alcohols, ketones and esters or a mixed solvent of these with water). It is preferable to use at least the vinyl monomer as the core monomer component to be absorbed, and the above-described preferred modes (monomer type, content rate, degree of crosslinking, etc.) are obtained as the monomer component constituting the core. More preferably, it is selected and used.

When emulsifying and dispersing the core 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 acids. Dispersion of seed particles after nonionic surfactants such as esters, polyoxysorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, oxyethylene-oxypropylene block polymers absorb the monomer components It is preferably used in that the state 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 core 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. Thus, it can be easily determined by confirming that the particle size is increased. In addition, in order to obtain the resin particle in this invention, although the absorption rate shown by a following formula is not specifically limited, It is preferable that it is 1.0 to 50 times, More preferably, it is 2 It is 0.0 times or more and 30 times or less, more preferably 3.0 times or more and 20 times or less.
Absorption capacity = (total mass of core monomer component to be absorbed) / (mass of seed particles)

  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 process, when the seed particles are polymerizable polysiloxane particles, the absorbed monomer component and the radically polymerizable group of the polymerizable polysiloxane skeleton are polymerized to form a polysiloxane skeleton and a vinyl polymer. And compound.

3-2. Shell Formation Method By forming a shell on the core so as to cover the core, resin particles that are core-shell particles can be obtained. The method for forming the shell is not particularly limited as long as the above-described monomer component is polymerized, and examples thereof include an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a second seed polymerization method, and a sol-gel seed polymerization method. A conventionally known method can be employed. For example, a method of forming a shell by the second seed polymerization method is preferably employed in that the control of the shell film thickness is easy and resin particles having a uniform film thickness and a small particle size distribution are easily obtained.

  The second seed polymerization method is a method of obtaining core-shell particles through a coating step in which a shell monomer component is coated on the core surface and a polymerization step in which the shell monomer component is polymerized on the core surface.

  In the coating step, the method for coating the shell monomer component on the core surface is not particularly limited. For example, the shell monomer component may be added to a core dispersion in which the core is dispersed in a solvent in advance. However, the core may be added to the solvent containing the shell monomer component. In particular, in the former method, it is possible to simplify the process by directly using the reaction liquid obtained by polymerizing the core as the core dispersion liquid. From the viewpoint of productivity. The shell monomer component may be added alone or as a solution dissolved in a solvent, but an emulsifier is used to efficiently coat the shell monomer component on the core surface. It is preferable to pre-emulsify and disperse in water or an aqueous medium and add as an emulsion. It is preferable to use at least the vinyl monomer (S) described above as the shell monomer component to be coated on the core surface, and the preferable modes described above as the monomer component constituting the share (type of monomer, content rate) It is more preferable to select and use such that the degree of crosslinking, etc.).

As the aqueous medium, the same aqueous medium used in the first seed polymerization method can be used. When the shell monomer component is emulsified and dispersed with an emulsifier, the first seed is used as an emulsifier. The same emulsifier as that used in the polymerization method can be used.
In the coating process, it is easy to determine whether the shell monomer component is dispersed on the core surface and the core is coated with the shell monomer component because the reaction solution is an emulsion and no precipitation occurs. I can judge. In order to obtain the core-shell type vinyl polymer particles in the present invention, the coating magnification represented by the following formula is not particularly limited, but is preferably 0.01 times or more and 20 times or less, More preferably, they are 0.03 times or more and 15 times or less, More preferably, they are 0.05 times or more and 10 times or less.
Covering magnification = (total mass of shell monomer components to be coated) / (total mass of core)
The polymerization method in the polymerization step after the coating step is not particularly limited. For example, a known method such as a method using a radical polymerization initiator (for example, a peroxide-based initiator, an azo-based initiator, or the like) can be used. The reaction temperature and reaction time in the method can be appropriately selected within the same range as described.

  After the synthesis, the core-shell type vinyl polymer particles are usually dried and optionally subjected to a heat treatment (firing). Although a drying temperature is not specifically limited, Usually, it is the range of 40 to 250 degreeC. As described above, the resin particles are prepared so as to satisfy the above-described ranges with respect to the number average particle size, the coefficient of variation of the particle size, and the like. When the core is made of organopolysiloxane particles, core-shell type vinyl polymer particles can be obtained by carrying out in the same manner as the shell forming method.

3-3. Method for forming conductive metal layer A conductive metal layer is formed on resin particles (base material), and an insulating resin layer is further formed as necessary, whereby conductive fine particles are obtained. 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 anisotropic conductive material is preferably used for connection mounting (COG) between an IC chip and a glass substrate with wiring, or for connection mounting (FOG) between a flexible printed circuit board with wiring and a glass substrate with wiring. .

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

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical 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.

<Number average particle diameter / coefficient of variation (CV value) of seed particles, core and resin particles>
In the case of resin particles and core, 0.005 part of resin particles or core is added to polyoxyethylene alkyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd. “Hitenol (registered trademark) N-08” as an emulsifier. 20 parts of a 1% aqueous solution of 1) and dispersed for 10 minutes with ultrasonic waves are used as measurement samples. In the case of seed particles, the dispersion obtained by hydrolysis and condensation reaction is treated with polyoxyethylene alkyl ether sulfate. Using a sample diluted with a 1% aqueous solution of an ester ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Hytenol (registered trademark) N-08”) as a measurement sample, a particle size distribution measuring device (Beckman Coulter, “Coulter Multisizer III” The particle size (μm) of 30000 particles was measured by “type”), and the number average particle size was determined. The standard deviation of the particle diameter based on the number of resin particles and cores was calculated by calculating the coefficient of variation (CV value) of the particle diameter according to the following formula.
Variation coefficient of particles (%) = 100 × (standard deviation of particle diameter / number average particle diameter)
The film thickness of the shell was calculated according to the following formula.
Shell film thickness (μm) = (Number average particle diameter of resin particles (μm) −Number average particle diameter of core particles before performing shell coating (μm)) / 2

<10% K value, 20% K value, 30% K value, 40% K value, etc. 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) and applying a load at a constant load speed (2.2295 mN / sec) toward the center of the particle in the “standard surface detection” mode, and the compression displacement becomes 10% of the particle diameter The load value (mN) and the amount of displacement (μm) at that time, and the load value (mN) at each displacement and the amount of displacement (μm) at that time were measured when the compression displacement was in the range of 10% to 50% of the particle diameter. . The obtained load value (mN) is converted into a compression load (N), the obtained displacement (μm) is converted into a compression displacement (mm), and the particle diameter is calculated from the number average particle diameter (μm) of the resin particles. (Mm) was calculated, and using these, the compression elastic modulus (10% K value, 20% K value, 30% K value, 40% K value, etc.) at each displacement was calculated based on the following formula. The measurement was performed on 10 different particles for each sample, and the averaged value was measured for the compressive elastic modulus (10% K value, 20% K value, 30% K value, 40%) at each displacement of each resin particle. K value). Further, a relative ratio of the compression elastic modulus (each K value) at each displacement obtained, for example, 20% K value / 10% K value (K20 / K10) or the like was calculated. Further, a displacement at which the K value is minimized (hereinafter referred to as a minimum compression rate) and a compression elastic modulus at the displacement (hereinafter referred to as a K value minimum value) were obtained from the compression displacement curve.

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

<10% K value of core particles>
The compression deformation characteristics of the core particles were determined in the same manner as the measurement method for the 10% K value of the resin particles, and the 10% K value was also determined in the same manner as the 10% K value of the resin particles.

<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. In addition, 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) to 0.25 parts of the particles and ultrasonically. 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

<Phosphorus content (%)>
4 ml of aqua regia was added to 0.05 g of conductive fine particles, and the metal layer was dissolved and separated by stirring under heating. Using the obtained filtrate as a sample, the contents of nickel and phosphorus were analyzed using an inductively coupled plasma emission spectrometer (ICP, manufactured by Shimadzu Corporation: “ICPE-9000”). The ratio of the mass of phosphorus to the total mass of nickel and phosphorus was determined as the phosphorus content (%) in the conductive metal layer (nickel layer).

2. 2. Production of conductive fine particles 2-1. Production of substrate (resin particles) Production Example 1
In a four-necked flask equipped with a condenser, a thermometer, and a dripping port, 2000 parts of ion-exchanged water, 16 parts of 25% aqueous ammonia, and 1200 parts of methanol are added, and 3-methacryloxypropyltrimethoxy is added from the dripping port with stirring. Hydrolysis of the silane compound by adding a mixture of silane (Shin-Etsu Chemical Co., Ltd., “KBM503”) 28.5 parts and vinyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., “KBM1003”) 41.5 parts. Then, a condensation reaction was carried out to prepare an emulsion of polysiloxane particles (polymerizable polysiloxane particles). Two hours after the start of the reaction, the obtained emulsion of polysiloxane particles was sampled and the particle diameter was measured. The number average particle diameter was 1.80 μm.

  Next, 0.4 part of 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “Hytenol (registered trademark) NF-08”) as an emulsifier is added with 100 parts of ion-exchanged water. To the dissolved solution, 17.5 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 0.9 part was dissolved was added and emulsified and dispersed to prepare an emulsion of monomer components.

  Furthermore, after adding the emulsion of the monomer component to the prepared emulsion of polysiloxane particles and stirring for 1 hour, polyoxyethylene styrenated phenyl ether sulfate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., “ Hytenol (registered trademark) NF-08 ") 4.2 parts of 20% aqueous solution was added, and the reaction solution was heated to 65 ° C. and held for 2 hours under a nitrogen atmosphere to carry out radical polymerization of the monomer components. It was. 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 heat-treated (baked) in a nitrogen atmosphere at 320 ° C. for 1 hour to obtain core particles. The number average particle diameter of the core particles was 2.00 μm, and the coefficient of variation of the particle diameter was 3.7%.

Disperse 100 parts of core particles in a solution in which 900 parts of methanol, 1800 parts of ion-exchanged water, 1.8 parts of 25% aqueous ammonia and 4.5 parts of 20% aqueous solution of polyoxyethylene styrenated phenyl ether ammonium sulfate are mixed. Then, 25 parts of 3-methacryloxypropyltrimethoxysilane was added and stirred for 2 hours to prepare a core particle dispersion.
In a solution obtained by dissolving 6.3 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt with 250 parts of ion-exchanged water, 175.0 parts of t-butyl methacrylate, 75.0 parts of triethylene glycol dimethacrylate, A solution in which 2.8 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved was added, and an emulsion of the monomer component emulsified and dispersed was added to the core particle dispersion, followed by stirring for 1 hour. The reaction solution was heated to 65 ° C. under a nitrogen atmosphere and held for 2 hours to perform radical polymerization of the monomer component. The 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 to obtain resin particles (1). The number average particle diameter of the resin particles (1) was 3.21 μm, and the coefficient of variation in particle diameter was 2.7%.

Production Examples 2-7, 12, 13
In Production Example 1, the core particles were synthesized in the same manner as in Production Example 1 except that the core particle diameter, shell film thickness, and the like were set as shown in Table 1, and further formed into a shell to form resin particles (2) to (7), (12), (13) were obtained.

Production Examples 8 to 11
In Production Example 3, resin particles (8) to (11) were produced in the same manner as in Production Example 3 except that the core particles were synthesized under the conditions such as the composition and particle size shown in Table 1 and shell formation was not performed. ) Respectively.

  The monomer composition constituting the core and the shell in the resin particles (1) to (13), the heat treatment temperature of the core particle, the mass ratio of the total amount of monomers constituting the shell and the core (shell / core mass ratio), etc. Regarding the production conditions, the number average particle diameter of the core particles, the number average particle diameter of the resin particles, and the film thickness of the shell, Table 10 shows 10% K value of the core particles, 10% K value of the resin particles, 20% K value, Table 2 shows the 30% K value, 40% K value, their ratio (K20 / K10 etc.), K value minimum value, and minimum compression rate.

In Table 1, the monomer components constituting the core and shell are indicated by abbreviations, and the compound names corresponding to the abbreviations are as follows.
MPTMS: 3-methacryloxypropyltrimethoxysilane VTMS; vinyltrimethoxysilane nBMA: n-butyl methacrylate tBMA: t-butyl methacrylate 1.6HXA: 1,6-hexanediol diacrylate 1.6HX: 1,6-hexanediol Dimethacrylate 3EGDMA: Triethylene glycol dimethacrylate DVB: Divinylbenzene St: Styrene

2-2. Production of conductive fine particles (formation of conductive metal layer)
Example 1
The resin particles (1) 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 30 g / L, sodium citrate concentration is 40 g / L, and pH is 7.0 with sodium hydroxide aqueous solution. An electroless nickel plating solution adjusted to 1 was prepared. While stirring the fine particle suspension at 70 ° C., 50 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. Then, after washing with ion exchange water, alcohol substitution was performed and vacuum drying was performed to obtain conductive fine particles (1). The film thickness of the conductive metal layer of the conductive fine particles (1) was 0.1 μm, and the phosphorus content in the conductive metal layer (nickel plating layer) was 5.5%.

Examples 2-7, Comparative Examples 1-6
Conductive fine particles (2) to (7) and (c1) to (c6) were produced in the same manner as in Example 1 except that the resin particles shown in Table 3 were used as the base material in Example 1. Table 3 shows the film thickness and phosphorus content of the conductive metal layer in the obtained conductive fine particles.

Example 8
Resin particles (2) were used as the base material, and the plating solution had a nickel sulfate hexahydrate concentration of 50 g / L, a sodium hypophosphite monohydrate concentration of 60 g / L, and a sodium citrate concentration of 40 g / L. Yes, conductive fine particles were prepared in the same manner as in Example 1 except that an electroless nickel plating solution whose pH was adjusted to 7.5 with an aqueous sodium hydroxide solution was used. Table 3 shows the film thickness and phosphorus content of the conductive metal layer in the obtained conductive fine particles.

<Evaluation of anisotropic conductive material>
Using conductive fine particles obtained in Examples and Comparative Examples, an anisotropic conductive material (anisotropic conductive paste) was prepared and a connection structure was prepared according to the following method. The value was evaluated. The evaluation results are shown in Table 3.
That is, using a rotating and rotating stirrer, 100 parts of an epoxy resin (“Stractbond (registered trademark) XN-5A” manufactured by Mitsui Chemicals, Inc.) as a binder resin was added to 2.0 parts of conductive fine particles and stirred for 10 minutes. And dispersed to obtain a conductive paste.
The obtained anisotropic conductive paste is sandwiched between a glass substrate on which ITO electrodes are wired at a pitch of 30 μm and a glass substrate on which an aluminum pattern is formed at a pitch of 30 μm, and is thermocompression bonded under pressure bonding conditions of 3 MPa and 170 ° C. At the same time, the connection structure was obtained by curing the binder resin.

  The initial resistance value between the electrodes of the obtained connection structure is measured. When the initial resistance value is 5Ω or less, “◎”, when 5Ω or more and 10Ω or less are “◯”, and when it exceeds 10Ω, “×”. evaluated. Further, the surface of the electrode on the side in contact with the anisotropic conductive film was observed with a metallographic microscope (magnification: 1000 times), “○” indicates that the indentation was observed, “×” indicates that the indentation was not confirmed, It was evaluated.

In all the examples, the number average particle size of the resin particles as the base material is 2.4 μm or more, 10% K value is 7,000 N / mm ² or more, 10% K value> 20% K value> 30% K value. The conductive fine particles based on resin particles satisfying the above conditions were used for anisotropic conductive connection. In any of the examples, the indentation forming ability was excellent and the initial resistance value was low. On the other hand, in the case of conductive fine particles using resin particles that do not satisfy the condition of 10% K value> 20% K value> 30% K value (Comparative Examples 1, 2 and 6), and 10% K value is 7,000 N / In the case of conductive fine particles using resin particles of less than mm ² (Comparative Examples 3 to 5), the initial resistance value was not at a satisfactory level.
Further, in the examples, a connection having a lower initial resistance value was obtained when the content of phosphorus was 10% or less than when the phosphorus content in the nickel layer was as high as 11.2%.

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

Claims (5)

Conductive fine particles having a substrate composed of resin particles and at least one conductive metal layer formed on the surface of the substrate, wherein the number average particle diameter of the resin particles is 2.4 μm or more, Compressive elastic modulus (10% K value) when the resin particles are displaced by 10% with respect to its diameter, compressive elastic modulus when displaced by 20% (20% K value), and compressive elastic modulus when displaced by 30% (30% K value) relationship satisfies the following formula: 10% K value> 20% K value> 30% K value,
Conductive fine particles, wherein the resin particles have a 10% K value of 7,000 N / mm ² or more. The conductive fine particles according to claim 1, wherein the compression rate at which the compression elastic modulus is minimized is 30% or more when measured in a range where the compression rate of the resin particles is 10 to 50% of the diameter. The conductive fine particles according to claim 1 or 2, wherein the resin particles are vinyl polymer particles.   The electroconductive fine particles as described in any one of Claims 1-3 whose outermost layer of the said electroconductive metal layer is a nickel layer. An anisotropic conductive material comprising the conductive fine particles according to claim 1 dispersed in a binder resin.