JP5583654B2 - Conductive fine particles and anisotropic conductive material using the same - Google Patents

Description

  The present invention relates to conductive fine particles suitable for low-pressure connection.

  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, resin particles are generally used as a core material (base material) and a conductive metal layer such as nickel is formed on the surface of the core material because of its excellent compressibility. Is used. As a base material for such conductive fine particles, there has been a demand for particles that are soft, flexible, and have a high recovery rate in order to obtain an anisotropic conductive material having excellent connection stability.

  In particular, with recent downsizing of electronic components and high-density mounting, electrodes that are connected media and substrates that hold the electrodes also tend to be thinned. If too much pressure is applied during mounting, damage to the substrates, etc. In some cases, there was a problem of inviting. Therefore, there is a demand for anisotropic conductive materials that can be used for low-pressure mounting. As conductive fine particles, resin particles that are softer than before so that they can be easily deformed without applying excessive pressure. The base material is desired.

  Examples of the soft and highly flexible resin particles include, for example, a polysiloxane having a vinyl group and a solubility in water at 25 ° C. of 10% by mass or less, and two (meth) acryloyl groups in one molecule. A polymer fine particle obtained by polymerizing a polymerizable component having a bifunctional oligomer having a weight average molecular weight of 300 or more as an essential component is disclosed (Patent Document 1).

  However, in general, when the resin particles are softened, the recovery rate tends to decrease, and it is impossible to maintain a spherical shape during plating when forming a conductive metal layer on the surface of the obtained resin particles. Since a conductive metal layer is not formed, a sufficiently low initial resistance value cannot be obtained when subjected to anisotropic conductive connection as conductive fine particles, and there is a problem that connection stability is impaired. As a means to solve this problem, it is conceivable to increase the degree of crosslinking of the resin particles to increase the recovery rate. However, as the degree of crosslinking increases, the particle hardness increases proportionally, so it is applied to low-pressure connections. As much softness as possible cannot be obtained.

JP 2006-117850 A

  The present invention has been made in view of the above circumstances, and is based on resin particles that retain a good recovery rate while being soft, and suppresses the initial resistance value even in low-voltage connection when subjected to electrical connection. It is an object of the present invention to provide conductive fine particles that can be used, and an anisotropic conductive material using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the crosslinkable monomer (a1) having 2 or more crosslinkable groups in the molecule and 15 or less atoms between the crosslinkable groups, It is found that if the resin particles are formed from a monomer component containing n-butyl methacrylate (b), both maintenance of the recovery rate and softening can be achieved, and the resin particles are used as a base material. It was confirmed that an anisotropic conductive material using conductive fine particles can realize a sufficiently low initial resistance even in a low-voltage connection, and the present invention was completed.

  That is, the conductive fine particles according to the present invention are conductive fine particles having a base material composed of resin particles and at least one conductive metal layer formed on the surface of the base material, wherein the resin particles are: Formed from a monomer component containing a crosslinkable monomer (a1) having two or more crosslinkable groups in the molecule and 15 or less atoms between the crosslinkable groups, and n-butyl methacrylate (b) It is characterized by being.

In the conductive fine particles of the present invention, the content of the crosslinkable monomer (a1) in the monomer component total amount 100% by mass is preferably 1% by mass or more and 85% by mass or less, and the monomer component total amount The content of n-butyl methacrylate (b) in 100% by mass is preferably 15% by mass or more and 99% by mass or less, and the monomer component has two or more crosslinkable groups in the molecule and It is preferable not to contain a crosslinkable monomer (a2) having more than 15 atoms between the crosslinkable groups, and the number average particle diameter of the resin particles is preferably 10 μm or more. In the conductive fine particles of the present invention, the resin particles have a compression deformation recovery rate of 3 to 40% measured by deformation between a maximum load of 49 mN and a minimum load of 0.49 mN, and the diameter of the particles is It is preferable that the compressive elastic modulus when displaced 20% is 100 to 1500 N / mm ² .

  The anisotropic conductive material according to the present invention is characterized in that the conductive fine particles of the present invention are dispersed in a binder resin.

  According to the conductive fine particles of the present invention, since the base material is formed of the specific crosslinkable monomer (a1) and n-butyl methacrylate (b), the recovery rate can be improved while being soft, and the surface The conductive metal layer can be uniformly coated, and the initial resistance value can be kept low even in the low-voltage connection when it is used for electrical connection.

  The conductive fine particles of the present invention are composed of a base material composed of resin particles and at least one conductive metal layer formed on the surface of the base material.

1. Resin particles (base material)
In the present invention, the resin particle has a crosslinkable monomer (a1) having two or more crosslinkable groups in the molecule and 15 or less atoms between the crosslinkable groups (hereinafter referred to as “specific crosslinkable monomer (a1)”). And a monomer component containing n-butyl methacrylate (b). Resin particles composed of such a monomer component containing a predetermined monomer retain a good recovery rate while being soft, and are sufficiently low even in low-pressure connection when used as a base material for conductive fine particles. It is possible to develop a resistance value.

  Hereinafter, first, general monomers that can be used as monomer components constituting the resin particles will be described, and then the specific crosslinkable monomer (a1) and n-butyl methacrylate (essential components in the present invention among them) will be described. Now, b) will be described.

  As the monomer component constituting the resin particles, only a so-called vinyl monomer may be used, or a so-called silane monomer may be used in combination with the vinyl monomer. 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, when a silane monomer is used, a polysiloxane skeleton is formed by hydrolytic condensation reaction of the silane monomer to form a polysiloxane skeleton. 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-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 vinyl group in one molecule and a functional group other than vinyl group (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, the reaction (bonding) of the carboxyl group, hydroxy group, alkoxy group, etc. of the monomer (2) The partner group must be present in the other monomer.

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

  Examples of the monomer (1) among the vinyl-based crosslinkable monomers include, for example, allyl (meth) acrylates such as allyl (meth) acrylate; ethylene glycol di (meth) acrylate, 1,4-butane Diol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,3-butanediol di Alkanediol di (meth) acrylate such as (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) ac Rate, pentadecaethylene glycol di (meth) acrylate, pentacontactor ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, etc. Di (meth) acrylates such as polyalkylene glycol di (meth) acrylate; tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate; tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; Hexa (meth) acrylates such as dipentaerythritol hexa (meth) acrylate; aromatic hydrocarbon crosslinks such as divinylbenzene, divinylnaphthalene, and derivatives thereof (Preferably styrene-type polyfunctional monomers such as divinylbenzene); N, N-divinyl aniline, divinyl ether, divinyl sulfide, hetero atom-containing crosslinking agents such as divinyl sulfonic acid; and the like. A monomer (1) may be used independently and may use 2 or more types together.

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

The vinyl non-crosslinkable monomer is a monomer having one vinyl group in one molecule (monomer (3)) or other than the vinyl group possessed by the monomer (2). The monomer (2) when the other monomer which has a group which reacts with a functional group does not exist in a monomer component is mentioned.
Examples of the monomer (3) among the vinyl non-crosslinkable monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, stearyl Alkyl (meth) acrylates such as (meth) acrylate and 2-ethylhexyl (meth) acrylate; cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate Cycloalkyl (meth) acrylates such as rate, cycloundecyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate; phenyl (meth) acrylate, benzyl Aromatic ring-containing (meth) acrylates such as (meth) acrylate, tolyl (meth) acrylate, phenethyl (meth) acrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p Styrene monofunctional monomers such as alkyl styrenes such as -t-butylstyrene, halogen group-containing styrenes such as o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; A monomer (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 cross-linked structure (first form) with a skeleton; Forming a cross-linked structure (second form) between a polysiloxane skeleton and a polysiloxane skeleton; Cross-linked structure between an organic polymer skeleton and a polysiloxane skeleton Those forming (third form). Of these, silane-based crosslinkable monomers capable of forming the third type of 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 silane-based crosslinkable monomers that can form the third form include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, and 3-methacrylic monomer. Having a (meth) acryloyl group such as loxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane; vinyltrimethoxysilane, Those having a vinyl group such as vinyltriethoxysilane and p-styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) Those having an epoxy group such as trimethoxysilane; 3-aminopropyltrimethoxysilane, those having an amino group such as 3-aminopropyltriethoxysilane; and the like. 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.

  Among the above vinyl-based crosslinkable monomers, vinyl-based non-crosslinkable monomers, silane-based crosslinkable monomers, and silane-based non-crosslinkable monomers, the monomer component in the present invention has predetermined conditions. The specific crosslinkable monomer (a1) which is a vinyl-based crosslinkable monomer or silane-based crosslinkable monomer and n-butyl methacrylate (b) which is a vinyl-based noncrosslinkable monomer are essential. . By including both the specific crosslinkable monomer (a1) and n-butyl methacrylate (b), it becomes possible to express a good recovery rate while appropriately softening the resin particles.

The specific crosslinkable monomer (a1) is a vinyl crosslinkable monomer or a silane crosslinkable monomer which is a crosslinkable monomer having two or more crosslinkable groups (vinyl group, alkoxy group, etc.) in the molecule. Among them, the number of atoms between the crosslinkable groups is 15 or less. Here, the number of atoms between the crosslinkable groups means the number of atoms existing between the two crosslinkable groups (when there are a plurality of atomic chains connecting the crosslinkable groups, the atoms in the shortest atomic chain) Number), atoms constituting the crosslinkable group itself and atoms taken into the polymer chain (main chain) when crosslinked (for example, carbon atom of carbon-carbon double bond (C = C), alkoxy group Oxygen atoms, silicon atoms bonded with alkoxy groups, etc.) are not counted. If the number of atoms between the crosslinkable groups exceeds 15, a spherical shape cannot be maintained during plating when forming the conductive metal layer, and a uniform conductive metal layer is not formed. As a result, the connection stability cannot be obtained. The number of atoms between the crosslinkable groups of the specific crosslinkable monomer (a1) is preferably 12 or less, and the lower limit thereof is preferably 4 or more, and more preferably 6 or more. When three or more crosslinkable groups are present, the number of atoms between them must satisfy the above in all combinations of two crosslinkable groups selected from these crosslinkable groups.
In the specific crosslinkable monomer (a1), another branched chain or a substituent may be bonded to the atomic chain between the crosslinkable groups in which 15 or less atoms are linked, and the branched chain has a ring. It may be formed. In particular, the atomic chain between the crosslinkable groups is preferably composed of continuous carbon atoms and / or oxygen atoms.

  Among the vinyl crosslinkable monomers, those corresponding to the specific crosslinkable monomer (a1) include, for example, ethylene glycol di (meth) acrylate, 1 , 4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,3 -Alkanediol di (meth) acrylate such as butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) Polyalkylene glycol such as acrylate (Meth) acrylates, aliphatic vinyl monomers such as trimethylolpropane tri (meth) acrylate; aromatic such as divinylbenzene vinyl monomer; and the like. When the monomer (2) is a crosslinkable monomer, those exemplified as the monomer (2) above ((meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 2- Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, p-hydroxystyrene, 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, p- Methoxystyrene) all corresponds to the specific crosslinkable monomer (a1).

  Examples of the silane crosslinkable monomer that correspond to the specific crosslinkable monomer (a1) include those exemplified as the silane crosslinkable monomer capable of forming the first form, In addition to those exemplified as the silane-based crosslinkable monomer capable of forming the second form, 3-methacryloxypropyltrimethoxysilane, exemplified as the silane-based crosslinkable monomer capable of forming the third form, 3 -Methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane and the like.

  The specific crosslinkable monomer (a1) is preferably the monomer (1) if it is a vinyl crosslinkable monomer, and can form the third form if it is a silane crosslinkable monomer. It is good to be. As the specific crosslinkable monomer (a1), an aliphatic vinyl monomer is particularly preferable among vinyl crosslinkable monomers, and alkanediol di (meth) acrylate is more preferable. Specific examples of the particularly preferable specific crosslinkable monomer (a1) include ethylene glycol di (meth) acrylate (number of atoms between crosslinkable groups: 6), trimethylolpropane tri (meth) acrylate (number of atoms between crosslinkable groups). : 7), 1,6-hexanediol di (meth) acrylate (number of atoms between crosslinkable groups: 9), triethylene glycol di (meth) acrylate (number of atoms between crosslinkable groups: 12), tripropylene glycol And di (meth) acrylate (number of atoms between crosslinkable groups: 15). On the other hand, among the silane-based crosslinkable monomers, those having a (meth) acryloyl group are preferable as the specific crosslinkable monomer (a1), more preferably 3-methacryloxypropyltrimethoxysilane (between the crosslinkable groups). Number of atoms: 5), 3-methacryloxypropylmethyldimethoxysilane (number of atoms between crosslinkable groups: 5), vinyltrimethoxysilane (number of atoms between crosslinkable groups: 0), especially 3-methacryloxypropyl Trimethoxysilane is preferred.

  The content of the crosslinkable monomer (a1) is preferably 1% by mass or more and 85% by mass or less in 100% by mass of the total amount of monomer components. More preferably, it is 2.5 mass% or more, More preferably, it is 4 mass% or more, More preferably, it is 70 mass% or less, More preferably, it is 55 mass% or less. When the content of the crosslinkable monomer (a1) is in the above range, it becomes easy to control the softness and recovery rate of the resin particles to a desirable range.

  The content of n-butyl methacrylate (b) is preferably 15% by mass or more and 99% by mass or less in 100% by mass of the total amount of the monomer components. More preferably, it is 30 mass% or more, More preferably, it is 50 mass% or more, Furthermore, it is good also as 70 mass% or more, More preferably, it is 98 mass% or less, More preferably, it is 97 mass% or less. When the content of n-butyl methacrylate (b) is in the above range, it becomes easy to control the softness and recovery rate of the resin particles to a desirable range.

  In addition to the specific crosslinkable monomer (a1) and n-butyl methacrylate (b), the monomer component in the present invention is a crosslinkable monomer that does not correspond to the specific crosslinkable monomer (a1) (vinyl-based crosslinkable monomer). Body, a silane-based crosslinkable monomer), that is, a crosslinkable monomer (a2) having two or more crosslinkable groups in the molecule and having more than 15 atoms between the crosslinkable groups. The above-described non-crosslinkable monomer (the monomer (3) and the silane non-crosslinkable monomer among vinyl monomers) may be contained. However, the content of the crosslinkable monomer (a2) is desirably as small as possible. Specifically, the content is preferably 10% by mass or less, more preferably 5% by mass or less in 100% by mass of the total amount of monomer components. More preferably, it is 1% by mass or less, most preferably not contained. That is, a preferred embodiment of the monomer component in the present invention is an embodiment consisting of only the specific crosslinkable monomer (a1) and n-butyl methacrylate (b), or the specific crosslinkable monomer (a1) and n-butyl methacrylate ( This is an embodiment consisting of b) and a non-crosslinkable monomer.

  The resin particles have a compression deformation recovery rate (sometimes referred to simply as “recovery rate” in this specification) measured by deforming between a maximum load of 49 mN and a minimum load of 0.49 mN of 3 to 40%. It is preferable. The compression deformation recovery rate is more preferably 3.5% or more, further preferably 3.9% or more, more preferably 35% or less, and further preferably 25% or less. When the compression deformation recovery rate of the resin particles is within the above range, the spherical shape can be reliably maintained at the time of plating when forming the conductive metal layer on the surface of the resin particles, and a uniform conductive metal layer can be formed. Since it can be formed, the initial resistance value can be kept low even in the low voltage connection when it is used for electrical connection. In the present invention, the compression deformation recovery rate can be controlled within the above range by forming the resin particles with the monomer components described above.

In the present invention, the compression deformation recovery rate is first constant in, for example, a compression test in which a load is applied in the center direction of particles using a known micro-compression tester (for example, “MCT-W500” manufactured by Shimadzu Corporation). The amount of displacement when compressing to a maximum load of 49 mN at a load load speed of 1 was obtained as the maximum displacement amount L1, and then the load was reduced to a minimum load of 0.49 mN at a removal load speed similar to the load load speed. The displacement amount between the maximum load and the minimum load is obtained as a recovery displacement amount L2, and is a value calculated based on the following equation. Specifically, as described in the examples described later, the load load speed (unload load speed) can be measured at about 2.23 mN / sec.
Compression deformation recovery rate (%) = (L2 / L1) × 100

  The resin particles preferably have a compression rate of 30 to 80% when compressed to the maximum load (49 mN) when determining the compression deformation recovery rate, more preferably 40% or more, and even more preferably 45. % Or more, more preferably 75% or less, and still more preferably 70% or less. When the compression ratio is in the above range, the resin particles are moderately soft, but it is easy to maintain a good recovery rate. The compression rate is based on the formula: (A / B) × 100 (%), where A is the maximum displacement L1 when determining the compression deformation recovery rate, and B is the number average particle diameter (μm) of the resin particles. Calculated.

The resin particles preferably have a compression elastic modulus (20% K value) of 100 to 1500 N / mm ² when the particle diameter is displaced by 20%. 20% K value of the resin particles, more preferably 300N / mm ² or more, more preferably 500 N / mm ² or more, more preferably 800 N / mm ² or more, and more preferably not more than 1480N / mm ^2. When the 20% K value of the resin particles is within the above range, the conductive particles are soft and uniform in shape while maintaining the spherical shape during plating when forming the conductive metal layer on the surface of the resin particles. Since the layer can be formed, the initial resistance value can be kept low even in the low-voltage connection when the layer is used for electrical connection. When 20% K value of the resin particles is less than 100 N / mm ^2, tend to be difficult to maintain a spherical shape, such as during plating too soft particles, while when it exceeds 1500 N / mm ^2, the particles The connection area becomes insufficient in the low pressure connection because it becomes too hard, and there is a possibility that the resistance value at the initial stage of the connection becomes high. In the present invention, the 20% K value can be controlled within the above range by forming the resin particles with the monomer components described above.

  The 20% K value of the resin particles can be measured by a compression test using a known fine compression tester, for example, a known fine compression tester (for example, “MCT-W500” manufactured by Shimadzu Corporation). In a compression test in which the particle is deformed until the particle diameter is displaced by 20% in a compression test in which a load is applied to the center of the particle at room temperature at a load loading speed of 19.37 mN / sec at room temperature, the compression load (N) and the compression displacement (Mm) can be measured and determined based on the following formula.

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

The resin particles have a compressive modulus (10% K value) of 200 N / mm ² or more and 3000 N / mm ² or less when the diameter of the particles is displaced by 10%, so that it is easy to realize a low initial resistance value. Is preferable. When 10% K value of the resin particles is less than 200 N / mm ^2, tend to be difficult to maintain a spherical shape, such as during plating too soft particles, whereas, if it exceeds 3000N / mm ^2, the particles The connection area becomes insufficient in the low pressure connection because it becomes too hard, and there is a possibility that the resistance value at the initial stage of the connection becomes high. 10% K value of the resin particles is more preferably 1000 N / mm ² or more, more preferably 1500 N / mm ² or more, more preferably 1800 N / mm ² or more, and more preferably not more than 2900N / mm ^2. The 10% K value of the resin particles can be obtained in the same manner as the 20% K value described above (that is, in the same manner except that the particle diameter is displaced by 10%).

  The resin particles preferably have a breaking point load, which is a load value when the particles are broken by applying a load in the center direction of the particles, 100 mN or more, more preferably 110 mN or more, and further up to 490 mN. It is preferable that there is no breaking point between them (that is, the breaking point load is 490 mN or more). When the breaking point load is within the above range, the resin particles have appropriate softness. The breaking point load can be measured by the same apparatus and measurement method as the measurement of the 20% K value.

  The resin particles preferably have a compressive fracture deformation rate of 50% or more, more preferably 60% or more, which is the deformation rate of the particles when the particles are broken by applying a load toward the center of the particles. Furthermore, it is preferable that even if it is compressed to 70%, it does not have a breaking point (that is, the compression fracture deformation rate is 70% or more). If the compression fracture deformation rate is within the above range, the resin particles have appropriate softness. The compressive fracture deformation rate is determined by measuring the amount of displacement (μm) when the particles are broken by the same apparatus and measurement method as in the measurement of the 20% K value. The diameter (μm) is B, and is calculated based on the formula: (A / B) × 100 (%).

  The number average particle size of the resin particles is not particularly limited, but the number-based average dispersed particle size is preferably 10 μm or more, more preferably 13 μm or more, further preferably 15 μm or more, and 50 μm or less. More preferably, it is 45 micrometers or less, More preferably, it is 40 micrometers or less. 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.

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.
The number average particle diameter of the resin particles and the coefficient of variation of the particle diameter in the present invention are values measured by a Coulter counter, 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.

2. Conductive fine particles In the conductive fine particles of the present invention, at least one conductive metal layer is formed on the surface of the substrate (resin particles). The metal constituting the conductive metal layer is not particularly limited. For example, gold, silver, copper, platinum, iron, lead, aluminum, chromium, palladium, nickel, rhodium, ruthenium, antimony, bismuth, germanium, tin, cobalt Indium, nickel-phosphorous, nickel-boron and other metals and metal compounds, and alloys thereof. Among these, gold, nickel, palladium, silver, copper, and tin are preferable because they become conductive fine particles having excellent conductivity. Further, in terms of inexpensiveness, nickel, nickel alloy (Ni-Au, Ni-Pd, Ni-Pd-Au, Ni-Ag, Ni-P, Ni-B, Ni-Zn, Ni-Sn, Ni-W, Ni—Co, Ni—W, Ni—Ti); copper, copper alloy (Cu and Fe, Co, Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, Ag, Alloy with at least one metal element selected from the group consisting of Au, Bi, Al, Mn, Mg, P, B, preferably an alloy with Ag, Ni, Sn, Zn); Silver, silver alloy (Ag And Fe, Co, Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, 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. Of these, nickel and nickel alloys are preferred. The conductive metal layer may be a single layer or multiple layers. In the case of multiple layers, for example, a combination of nickel-gold, nickel-palladium, nickel-palladium-gold, nickel-silver, etc. Is preferred.

The thickness of the conductive metal layer is preferably 0.010 μm or more, more preferably 0.030 μm or more, 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 no conductive metal layer is formed” means that when the surface of any 10,000 conductive fine particles is observed using an electron microscope (magnification 1000 times), It means that the crack of the conductive metal layer and the exposure on the surface of the resin particles are not substantially visually observed.

The number average particle diameter of the conductive fine particles of the present invention is preferably 10 μm or more, more preferably 13.5 μm or more, further preferably 14 μm or more, further preferably 15 μm or more, particularly preferably 16 μm or more, and preferably 51 μm or less. More preferably, it is 46 micrometers or less, More preferably, it is 41 micrometers or less, More preferably, it is 36 micrometers or less. If the number average particle diameter is within this range, it can be suitably used for electrical connection of miniaturized and narrowed electrodes and wirings.
The number average particle size of the conductive fine particles was determined using a flow type particle image analyzer (“FPIA (registered trademark) -3000” manufactured by Sysmex Corporation), and was based on the number average particle size of 3000 particles. Is preferably adopted.

The conductive fine particles of the present invention 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. Manufacturing method First, the manufacturing method of the said resin particle used as a base material is demonstrated.
The method for producing the resin particles is not particularly limited as long as the above-described monomer component is polymerized. Conventionally known methods such as emulsion polymerization, suspension polymerization, dispersion polymerization, seed polymerization, sol-gel seed polymerization method, etc. Can be adopted. In view of easy control of the particle diameter of the resin particles and easy obtaining of resin particles having a small particle size distribution, for example, a method of classifying the resin particles after synthesis by a seed polymerization method is preferably employed.

  The seed polymerization method is a method of obtaining resin particles through a seed particle preparation step, an absorption step in which the seed particle absorbs the monomer component, and a polymerization step in which the monomer component absorbed in the seed particle is polymerized. The method and conditions in each step are not particularly limited as long as a known seed polymerization method is appropriately employed. For example, the following methods are preferably employed.

  In the seed particle preparation step, when synthesizing resin particles composed only of an organic material, the seed particles are prepared by a method such as soap-free emulsion polymerization or dispersion polymerization using the vinyl monomer. Good. In this case, it is preferable to use a styrene monofunctional monomer such as styrene as the vinyl monomer. On the other hand, when synthesizing particles composed of an organic material and a material having a polysiloxane skeleton, a solvent containing water (for example, alcohols, ketones, esters, ( The seed particles (polysiloxane particles) may be prepared by hydrolysis and condensation polymerization in a mixed solvent of an organic solvent such as cyclo) paraffins and aromatic hydrocarbons and water. In this case, it is preferable to use the silane crosslinkable monomer corresponding to the specific crosslinkable monomer (a1) as the silane monomer to form polymerizable polysiloxane particles. In the hydrolysis and polycondensation, basic catalysts such as ammonia, urea, ethanolamine, tetramethylammonium hydroxide, alkali metal hydroxide, and alkaline earth metal hydroxide can be preferably used as the catalyst. If necessary, an anionic, cationic or nonionic surfactant or a polymer dispersant such as polyvinyl alcohol or polyvinylpyrrolidone can be used in combination.

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

When emulsifying and dispersing the monomer component with an emulsifier, examples of the emulsifier include anionic surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters. , Dispersion state of seed particles after nonionic surfactant such as polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene-oxypropylene block polymer absorbs monomer component Is preferably used in that it can be stabilized. In addition, the amount of water or aqueous medium used for emulsification and dispersion is usually 0.3 to 10 times the mass of the monomer component.
In the absorption process, for determining whether the monomer component has been absorbed by the seed particles, for example, before adding the monomer component and after completion of the absorption step, observe the particles with a microscope and absorb the monomer component. It can be easily determined by confirming that the particle size is increased. 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.
Absorption magnification = (total mass of monomer components 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.

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

After the synthesis, the resin particles classified as necessary are usually dried and optionally subjected to firing. Although drying temperature is not specifically limited, Usually, it is the range of 50 to 250 degreeC.
As described above, the resin particles are prepared so as to satisfy the above-described ranges with respect to the average particle diameter, the coefficient of variation of the particle diameter, and the like.

Next, conductive fine particles are obtained by forming a conductive metal layer on the resin particles (base material) obtained as described above and further forming an insulating resin layer as necessary.
The formation method of the conductive metal layer and the formation method of the insulating resin layer are not particularly limited. For example, the conductive metal layer is plated on the substrate surface by an electroless plating method, an electrolytic plating method, or the like; Or a method of forming a conductive metal layer by a physical vapor deposition method such as vacuum vapor deposition, ion plating, or ion sputtering; Among these, the electroless plating method is particularly preferable in that a conductive metal layer can be easily formed without requiring a large-scale apparatus.

4). Anisotropic conductive material The anisotropic conductive material of the present invention comprises the conductive fine particles of the present invention dispersed in a binder resin. The form of the anisotropic conductive material is not particularly limited, and examples thereof include various forms such as an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive, and an anisotropic conductive ink. By providing these anisotropic conductive materials between opposing substrates or between electrode terminals, good electrical connection can be achieved. The anisotropic conductive material using the conductive fine particles of the present invention includes a conductive material for a liquid crystal display element (conductive spacer and composition thereof). Suitable applications of the anisotropic conductive material include touch panel input, LED use, and the like, and particularly suitable for touch panel mounting.

The binder resin is not particularly limited as long as it is an insulating resin. For example, thermoplastic resins such as acrylic resins, ethylene-vinyl acetate resins, styrene-butadiene block copolymers; monomers and oligomers having a glycidyl group; Examples thereof include a curable resin composition that is cured by a reaction with a curing agent such as isocyanate; a curable resin composition that is cured by light or heat;
The anisotropic conductive material of the present invention can be obtained by dispersing the conductive fine particles of the present invention in the binder resin to obtain a desired form. For example, the binder resin and the conductive fine particles are separately provided. You may connect by making electroconductive fine particles exist with a binder resin between the base material to be used and connecting between electrode terminals.

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

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

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

1. Physical property measurement method Various physical properties were measured by the following methods.
<Number average particle diameter and coefficient of variation (CV value) of seed particles and resin particles>
In the case of resin particles, 0.1% of resin particles are added to 1% of polyoxyethylene alkyl ether sulfate ammonium salt (“Hitenol (registered trademark) N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier. A dispersion obtained by adding 20 parts of an aqueous solution and ultrasonically dispersing for 10 minutes is used as a measurement sample. In the case of seed particles, a dispersion obtained by hydrolysis and condensation reaction is added to a polyoxyethylene alkyl ether sulfate ammonium salt ( Using a sample diluted with a 1% aqueous solution of “Hitenol (registered trademark) N-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as a measurement sample, using a particle size distribution analyzer (“Coulter Multisizer Type III” manufactured by Beckman Coulter, Inc.) The particle diameter (μm) of 30000 particles was measured to determine the number average particle diameter. For the resin particles, the standard deviation of the particle diameter based on the number as well as the number average particle diameter was obtained, and the coefficient of variation (CV value) of the particle diameter was calculated according to the following formula.
Variation coefficient of particles (%) = 100 × (standard deviation of particle diameter / number average particle diameter)

<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

<10% K value and 20% K value 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 (19.37 mN / sec) toward the center of the particle in the “standard surface detection” mode, and the compression displacement becomes 10% of the particle diameter Load value (mN) and the displacement amount (μm) at that time, and the load value (mN) when the compression displacement reached 20% of the particle diameter and the displacement amount (μm) at that time were measured. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value. Then, the obtained load value (mN) is converted into a compressive load (N), the obtained displacement amount (μm) is converted into a compressive displacement (mm), and the average particle diameter (μm) of the resin particles is used to calculate the particle size. The radius (mm) was calculated and calculated based on the following formula using these.

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

<Compression deformation recovery rate and compression rate of resin particles>
Using a micro-compression tester (“MCT-W500” manufactured by Shimadzu Corporation), a circular flat plate indenter with a diameter of 50 μm is used for one particle dispersed on a sample stage (material: SKS flat plate) at room temperature (25 ° C.). Using (material: diamond), in the “soft surface detection” mode, compress to the maximum load (49 mN) at a constant load speed (2.23 mN / sec) toward the center of the particle, and the amount of displacement (μm) at that time Was measured, and this was taken as the maximum displacement L1. Next, the displacement (μm) between the maximum load and the minimum load when the load is reduced to the minimum load (0.49 mN) at a constant unloading speed (2.23 mN / sec) is measured. Was the recovery displacement L2. The compression deformation recovery rate was calculated from the maximum displacement amount L1 and the recovery displacement amount L2 based on the following equation. The compression rate was calculated based on the formula: (A / B) × 100 (%), where A is the maximum displacement L1 and B is the number average particle diameter (μm) of the resin particles. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value.
Compression deformation recovery rate (%) = (L2 / L1) × 100

<Fracture point load and compressive fracture deformation rate of resin particles>
The load value (mN) and displacement amount (μm) when the particle was broken by applying a load toward the center of the particle at room temperature (25 ° C.) by the same apparatus and measurement method as the measurement of the 10% K value. The load value (mN) when the particles were measured was determined as the breaking point load (mN). The compressive fracture deformation rate is calculated based on the formula: (A / B) × 100 (%), where A is the amount of displacement (μm) when the particles are broken, and B is the number average particle diameter (μm) of the resin particles. did.

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, 65 parts of ion-exchanged water and 0.2 part of 25% ammonia water are added, and the monomer component (seed forming monomer) is added from the dripping port with stirring. ) 10 parts of 3-methacryloxypropyltrimethoxysilane (crosslinkable group number of atoms: 5) and 40 parts of methanol are added, and hydrolysis and condensation reaction of 3-methacryloxypropyltrimethoxysilane is carried out to produce methacryloyl. A dispersion of polymerizable polysiloxane particles (seed particles) having a group was prepared. The number-based average particle size of the polysiloxane particles was 7.0 μm.

  Next, 6.0 parts of a 20% aqueous solution of polyoxyethylene styrenated ammonium sulfate ester ammonium salt ("Hitenol (registered trademark) NF-08" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier is dissolved in 200 parts of ion-exchanged water. 200 parts of n-butyl methacrylate (n-BMA) as a monomer component (absorbing monomer) and 2,2′-azobis (2,4-dimethylvaleronitrile) (“Wako Pure Chemical Industries, Ltd. -65 ") 4.5 parts dissolved solution was added and emulsified and dispersed to prepare an emulsion of monomer component (absorbing monomer). Two hours after the start of emulsification dispersion, the obtained emulsion was added to a dispersion of polysiloxane particles (seed particles), and further stirred. One hour after the addition of the emulsified liquid, the mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were absorbed and absorbed.

  Next, 84 parts of a 10% aqueous solution of polyvinyl alcohol (Kuraray “Poval PVA-205”) was added, the reaction solution was heated to 65 ° C. under a nitrogen atmosphere, and held at 65 ° C. for 2 hours. The components were radically polymerized. The emulsion after radical polymerization was subjected to solid-liquid separation, and the resulting cake was washed with ion-exchanged water and methanol, and then vacuum-dried at 40 ° C. for 12 hours in a nitrogen atmosphere to obtain resin particles (1). Table 1 shows the physical properties of the resin particles obtained.

(Production Example 2)
Manufacturing Example 1 except that the type and amount of the absorbing monomer were changed to 195 parts of n-butyl methacrylate (n-BMA) and 5 parts of ethylene glycol dimethacrylate (number of crosslinkable atoms: 6). Resin particles (2) were obtained in the same manner as in Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 3)
Production Example 1 except that the type and amount of the absorbing monomer were changed to 180 parts of n-butyl methacrylate (n-BMA) and 20 parts of ethylene glycol dimethacrylate (number of crosslinkable atoms: 6). Resin particles (3) were obtained in the same manner as in Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 4)
In Production Example 1, except that the type and amount of the absorbing monomer were changed to 140 parts of n-butyl methacrylate (n-BMA) and 60 parts of triethylene glycol dimethacrylate (number of crosslinkable groups: 12), Resin particles (4) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 5)
In Production Example 1, except that the type and amount of the absorbing monomer were changed to 100 parts of n-butyl methacrylate (n-BMA) and 100 parts of triethylene glycol dimethacrylate (number of crosslinkable groups: 12), Resin particles (5) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 6)
In Production Example 1, except that the type and amount of the absorbing monomer were changed to 180 parts of n-butyl methacrylate (n-BMA) and 20 parts of tripropylene glycol diacrylate (number of crosslinkable atoms: 15), Resin particles (6) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 7)
In Production Example 1, the type and amount of the absorbing monomer were changed to 180 parts of n-butyl methacrylate (n-BMA) and 20 parts of 1,6-hexanediol dimethacrylate (number of crosslinkable groups: 10). Except for the above, resin particles (7) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 8)
In Production Example 1, the type and amount of the absorbing monomer were changed to 180 parts of n-butyl methacrylate (n-BMA) and 20 parts of 1,6-hexanediol diacrylate (number of crosslinkable atoms: 10). Except that, in the same manner as in Production Example 1, resin particles (8) were obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 9)
In Production Example 1, the type and amount of the absorbing monomer were 180 parts of n-butyl methacrylate (n-BMA), divinylbenzene (number of crosslinkable group atoms: 2 for o-position substitution product, 3 for m-position substitution product, In the case of p-substituted product 4) (“DVB960” manufactured by Nippon Steel Chemical Co., Ltd .: 96% divinylbenzene, 4% vinyl non-crosslinkable monomer (ethylvinylbenzene, etc.) content) Resin particles (9) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 10)
In Production Example 1, except that the type and amount of the absorbing monomer were changed to 180 parts of n-butyl methacrylate (n-BMA) and 20 parts of trimethylolpropane trimethacrylate (number of crosslinkable atoms: 7), Resin particles (10) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 11)
In Production Example 1, the type and amount used of the absorbing monomer was changed to 50 parts of ethylene glycol dimethacrylate, and the drying temperature and time were changed to 120 ° C. for 2 hours in the same manner as in Production Example 1. Comparative resin particles (11) were obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 12)
Production Example 1 except that the type and amount of the absorbing monomer were changed to 35 parts methyl methacrylate and 15 parts ethylene glycol dimethacrylate, and the drying temperature and time were changed to 120 ° C. and 2 hours in Production Example 1. In the same manner as in Example 1, comparative resin particles (12) were obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 13)
In Production Example 1, the type and amount of the absorption monomer were changed to 50 parts of methyl methacrylate and the drying temperature was changed to 80 ° C., in the same manner as in Production Example 1, except that the comparative resin particles ( 13) was obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 14)
In Production Example 1, the type and amount of the absorption monomer were changed to 200 parts of methyl methacrylate and the drying temperature was changed to 80 ° C., in the same manner as in Production Example 1, except that the comparative resin particles ( 14) was obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 15)
In Production Example 1, the type and amount of the absorbing monomer were changed to 200 parts of cyclohexyl methacrylate and the drying temperature was changed to 50 ° C., in the same manner as in Production Example 1, except that the comparative resin particles ( 15) was obtained. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 16)
In Production Example 1, the type and amount of the absorption monomer were changed to 200 parts of tert-butyl methacrylate, and the drying temperature and time were changed to 80 ° C. and 4 hours, in the same manner as in Production Example 1. Comparative resin particles (16) were obtained. Table 1 shows the physical properties of the resin particles obtained.

2-2. Production of conductive fine particles (formation of conductive metal layer)
Example 1
The resin particles (1) used as a base material are subjected to etching treatment with sodium hydroxide, then sensitized by contacting with a tin dichloride solution, and then activated by immersing in a palladium dichloride solution. Palladium nuclei were formed by the method (sensitizing-activation method). Next, 2 parts of resin particles with palladium nuclei formed were added to 400 parts of ion-exchanged water, and after ultrasonic dispersion treatment, the resulting resin particle suspension was heated in a 70 ° C. hot bath. By adding 300 parts of electroless plating solution (“Schumer (registered trademark) S680” manufactured by Nippon Kanisen Co., Ltd.) separately heated to 70 ° C. with the suspension thus heated, electroless nickel is added. A plating reaction was caused. After confirming that the generation of hydrogen gas was completed, solid-liquid separation was performed, followed by washing with ion exchange water and methanol in that order, and vacuum drying at 100 ° C. for 2 hours to obtain nickel-plated particles. Next, the obtained nickel plating particles were added to a displacement gold plating solution containing potassium gold cyanide, and the nickel layer surface was further subjected to gold plating to obtain conductive fine particles. The film thickness of the conductive metal layer in the obtained conductive fine particles was as shown in Table 1.

(Examples 2 to 10, Comparative Examples 1 to 6)
Conductive fine particles were produced in the same manner as in Example 1 except that the resin particles shown in Table 1 were used as the substrate. The film thickness of the conductive metal layer in the obtained conductive fine particles was as shown in Table 1.

3. Preparation and Evaluation of Anisotropic Conductive Material Using conductive fine particles obtained in Examples and Comparative Examples, an anisotropic conductive material (anisotropic conductive paste) was prepared by the following method, and the initial resistance value was The method was evaluated. The evaluation results are shown in Table 1.
That is, using three rolls, 100 parts of epoxy resin (“JER828” manufactured by Mitsubishi Chemical Corporation) as a binder resin and 1 part of conductive fine particles and a curing agent (“Sun-Aid (registered trademark) SI manufactured by Sanshin Chemical Co., Ltd.) -150 ") and 2 parts of toluene and 100 parts of toluene were stirred and dispersed for 10 minutes to obtain a conductive paste.
The obtained anisotropic conductive paste was sandwiched between an entire aluminum vapor-deposited glass substrate having resistance measurement lines and a polyimide film substrate having a copper pattern formed at a pitch of 100 μm, under pressure bonding conditions of 2 MPa and 150 ° C. A connection structure was obtained by thermocompression bonding and curing the binder resin.

  And the initial resistance value between electrodes was measured about the obtained connection structure, and the case where initial resistance value was 5 ohms or less was evaluated as "(circle)" and 5 ohms as "x".

  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 an anisotropic conductive paste for touch panel mounting, for example.

Claims (7)

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 resin particle contains a crosslinkable monomer (a1) having two or more crosslinkable groups in the molecule and 15 or less atoms between the crosslinkable groups, and n-butyl methacrylate (b). mer is formed from the components, and the monomer conductive fine particles content, characterized in der Rukoto least 47.6 wt% of the components total in 100 wt% n-butyl methacrylate (b).   The conductive fine particles according to claim 1, wherein the content of the crosslinkable monomer (a1) in the total amount of the monomer components of 100% by mass is 1% by mass or more and 85% by mass or less. The conductive fine particles according to claim 1 or 2, wherein the content of n-butyl methacrylate (b) in the monomer component total amount of 100% by mass is 99% by mass or less.   The monomer component does not contain a crosslinkable monomer (a2) having two or more crosslinkable groups in the molecule and having more than 15 atoms between the crosslinkable groups. The electroconductive fine particles as described.   The conductive fine particles according to claim 1, wherein the resin particles have a number average particle diameter of 10 μm or more. The resin particles have a compression deformation recovery rate measured by deformation between a maximum load of 49 mN and a minimum load of 0.49 mN of 3 to 40%, and a compression elastic modulus when the particle diameter is displaced by 20%. conductive fine particle according to any one of claims 1 to 5 but is 100~1500N / mm ^2.   An anisotropic conductive material comprising the conductive fine particles according to claim 1 dispersed in a binder resin.