JP2014123456A - Conductive fine particle and anisotropic conductive material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive fine particle allowing a check of a good connection state in visual evaluation, although being soft, and an anisotropic conductive material using it.SOLUTION: A conductive fine particle includes a resin particle and at least one conductive metal layer formed on the surface of the resin particle. The number average particle size of the resin particle is 8-50 μm; the compression elastic modulus for a displacement of the resin particle diameter of 10% is 100-3,000 N/mm; the recovery rate after compression of the resin particle to 10% of the diameter is 30% or higher; and the recovery rate is always higher than 0% and equal to or lower than 10% after compression of the resin particle to an arbitrary displacement amount in the range of 20-60% of the diameter.

Description

  The present invention relates to soft conductive fine particles.

  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, soft and highly flexible particles have been demanded in order to obtain an anisotropic conductive material having excellent connection stability.

  In particular, along with the recent miniaturization and high-density mounting of electronic components, electrodes that are connected media, substrates and films that hold the electrodes tend to be thinned, and if excessive pressure is applied during mounting, There was a problem of causing damage. 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.

  Therefore, conductive fine particles have been proposed in which soft and highly flexible resin particles are used as a base material to prevent damage to the substrate and wiring (Patent Document 1). Such conductive fine particles are characterized in that the 10% K value is not more than a certain value determined by the particle diameter of the conductive fine particles.

JP 2001-216841 A

By the way, whether or not sufficient conduction is obtained when conducting anisotropic conductive connection using conductive fine particles can be determined by measuring the initial resistance value of the connection structure obtained by anisotropic conductive connection. However, as a simpler evaluation method, a method is known in which the conductive fine particles in a connected state are visually recognized and determined. Specifically, when the conductive fine particles in the connected state sandwiched between the substrates on which the electrodes to be connected are mounted are observed with a microscope or the like, the long diameter of the contact surface of the conductive fine particles in contact with the substrate is If it is larger than the particle diameter of the conductive fine particles, it can be said that a sufficient sustained area can be secured, and the surface of the conductive fine particles is plated on the contact surface of one conductive fine particle in contact with the substrate. If all the layers are connected to one another, it can be said that conduction is secured.
However, when conducting visual evaluation of conventional conductive fine particles based on soft resin particles, the connection area is insufficient or the plating layer is cracked, confirming good conductivity. There was something I couldn't do.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide conductive fine particles that are soft and can confirm a good connection state in visual evaluation, and an anisotropic conductive material using the same. To do.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has obtained a recovery rate after compressing the particles to 10% of the diameter even if the resin particles are soft resin particles having a 10% K value in a specific range (hereinafter referred to as “recovery rate”). The recovery rate (hereinafter referred to as “20 to 60”, hereinafter referred to as “20 to 60% recovery rate”) is increased to a certain level and the particles are compressed to an arbitrary displacement amount of 20 to 60% of the diameter. It is found that conductive fine particles capable of confirming a good connection state in visual evaluation can be obtained by controlling the recovery rate (which may be referred to as “% recovery rate at the time of compression”) to always exceed 0% and 10% or less. Was completed.

That is, the conductive fine particles according to the present invention are conductive fine particles having resin particles and at least one conductive metal layer formed on the surface of the resin particles, and the number average particle diameter of the resin particles is an 8 to 50 m, the compression modulus when the diameter is 10% displacement of the resin particles is 100~3000N / mm ^2, the recovery rate after compressing the resin particles up to 10% of the diameter of 30% or more And the recovery rate after compressing the resin particles to an arbitrary displacement amount between 20 to 60% of the diameter is always more than 0% and 10% or less.

  In the present invention, a recovery rate of less than 0.10% is substantially regarded as “0.0%”. That is, if the post-compression recovery rate is in the range of less than 0.10% (for example, 0.0999%), the recovery rate is assumed to be 0.0%.

  In the conductive fine particles of the present invention, the number average particle diameter of the resin particles is preferably 10 μm or more. In the present invention, the outermost metal layer in the conductive metal layer is preferably a nickel layer or a gold layer. The resin particles in the present invention are formed from a monomer component containing a crosslinkable monomer and a non-crosslinkable monomer, and the crosslinkable monomer content in the monomer component is less than 20.0 mass%, The non-crosslinkable monomer preferably contains at least one selected from methyl (meth) acrylate and ethyl (meth) acrylate.

  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 particle size and the 10% K value are controlled, the 10% compression recovery rate is more than a certain value, and the 20 to 60% compression recovery rate is always more than 0% and less than 10%. Since the resin particles controlled in this way are used as the base material of the conductive fine particles, it becomes possible to confirm a good connection state in the visual evaluation.

  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 recovery rate after compression of the resin particles to 10% of the diameter (recovery rate at 10% compression) is 30% or more, and the resin particles are arbitrarily displaced between 20 to 60% of the diameter. It is important that the recovery rate after compression to the amount (20 to 60% compression recovery rate) is always more than 0% and 10% or less. When the resin particles have such a recovery rate characteristic, the major axis of the contact surface of the conductive fine particles that are in contact with the substrate at the time of pressure connection is larger than the particle diameter of the conductive fine particles before connection. At the same time, since all the plating layers on the surface of the conductive fine particles are connected to each other at the contact surface with the substrate, a good connection state can be confirmed in the visual evaluation. The recovery rate is the ratio (percentage) of the recovery displacement amount when the compressive stress is unloaded to the compression displacement amount, and the detailed measurement method will be described later. In the present invention, for example, by forming resin particles with a specific monomer component to be described later, the recovery rate characteristics (recovery rate at 10% compression of 30% or more, and always more than 0% and 10% or less 20%). ˜60% recovery rate during compression).

  In the present invention, the 10% compression recovery rate may be 30% or more, preferably 32% or more, and more preferably 35% or more. If the 10% compression recovery rate is in this range, a sufficient repulsive force can be expressed at the initial stage of pressure connection, and the initial resistance can be further increased.

In the present invention, the recovery rate during compression of 20 to 60% is always 10% or less. In this way, the recovery rate over the final stage of the pressure connection is always kept below a certain level, so it becomes easy to deform, so it is possible to expand the connection area and suppress cracking of the plating layer, etc. A good connection state can be confirmed by visual recognition. On the other hand, the recovery rate at 20 to 60% compression always exceeds 0%. When the recovery rate becomes 0%, the resistance value tends to increase with time, and connection reliability is impaired.
In the present invention, whether the 20% to 60% compression rate of the resin particles is always more than 0% and not more than 10% is determined by the compression rate between 20% to 60% of the diameter (that is, displaced by compression). Measure the recovery rate by changing the displacement amount as a percentage of the particle diameter before compression (for example, 20% compression, 30% compression, 40% compression, 50% compression, 60% compression of diameter) Judgment) from those continuous transitions.

In the present invention, the recovery rate can be measured, for example, using a known fine compression tester (for example, “MCT-W500” manufactured by Shimadzu Corporation) as follows. That is, when measuring the recovery rate after compressing the particles to a% of the diameter, in a compression test in which a load is applied in the direction of the center of the particle, the particle diameter is first increased by applying a load at a constant load speed. The compressive load (a% compressive load value) at the time of a% displacement is measured in advance, and the displacement amount (that is, a% of the particle diameter) when compressed to the compressive load value is defined as the maximum displacement amount L1. When the particles are compressed so that the a% compression load value becomes the maximum load at a constant load load speed, and then the load is reduced to the minimum load of 0.049 mN at the same unload load speed as the load load speed. The displacement amount between the maximum load and the minimum load is obtained as the recovery displacement amount L2. What is necessary is just to calculate based on the following formula from the maximum displacement amount L1 and the recovery displacement amount L2 thus obtained. Although the calculated value may be a negative value, in the present invention, the recovery rate in such a case is assumed to be “0.0%”. Specifically, as described in the examples described later, the load load speed (unload load speed) can be measured at about 0.441 N / sec. The test particles subjected to the compression test are limited to untested particles, and the compression test is not performed again using particles once subjected to the compression test. 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.
Recovery rate (%) = (L2 / L1) × 100

The resin particles in the present invention have a compression elastic modulus (10% K value) of 100 to 3000 N / mm ² when the particle diameter is displaced by 10%. If the 10% K value of the resin particles is within the above range, it is soft, but it maintains a spherical shape during the plating process when forming the conductive metal layer on the surface of the resin particles, so that it is a uniform conductive metal. Since a layer can be formed, the initial resistance value can be kept low even in a low-voltage connection when subjected to electrical connection. If the 10% K value of the resin particles is less than 100 N / mm ² , the particles become too soft and difficult to maintain a spherical shape during plating, etc., while if it exceeds 3000 N / mm ² , the particles become too hard. Therefore, the connection area becomes insufficient in the low-voltage connection, and the resistance value at the initial connection becomes high. 10% K value of the resin particles is preferably 300N / mm ² or more, more preferably 700 N / mm ² or more, more preferably 1000 N / mm ² or more, and most preferably 1200 N / mm ² or more, preferably 2950N / mm ² or less, more preferably 2900N / mm ² or less, more preferably 2500N / mm ^2, and most preferably not more than 2000N / mm ^2. In the present invention, for example, the 10% K value can be controlled within the above range by forming resin particles with a specific monomer component described later.

  The 10% K value of the resin particles can be measured by a compression test using a known fine compression tester, for example, a known fine compression tester (for example, “MCT-W500” manufactured by Shimadzu Corporation). In a compression test in which the particle is deformed until the particle diameter is displaced by 10% in a compression test in which a load is applied in the center direction of the particle at a load load rate of 0.441 N / sec at room temperature, the compression load (N) and the compression displacement (Mm) can be measured and determined 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.

(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 8 to 50 μm. 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. Examples of the touch panel include connection between a touch panel lead-out circuit and a flexible printed wiring board (FPC). The number average particle diameter of the resin particles is preferably 8.0 μm or more, more preferably 8.5 μm or more, further preferably 9 μm or more, further preferably 10 μm or more, preferably 40 μm or less, more preferably 30 μm or less, and further The thickness is preferably 25 μm or less, and particularly preferably 19 μm or less from the viewpoint of corresponding to the narrowing of electrodes and wiring.

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.

In the present invention, the resin particles are preferably formed from a monomer component containing a crosslinkable monomer and a non-crosslinkable monomer. The resin particles are usually formed by a polymerization reaction and / or a condensation reaction of the monomer component.
The crosslinkable monomer constituting the resin particle is not particularly limited as long as it is crosslinkable. Specifically, the crosslinkable monomer includes a vinyl crosslinkable monomer containing at least a vinyl group, a silicon atom and a hydrolyzable group ( In addition to hydrolyzable groups such as alkoxy groups (alkoxysilyl groups), hydroxy groups (silanol groups are also included) and / or silane crosslinkable monomers containing vinyl groups, and the like. If a monomer having a vinyl group is used, a skeleton in which vinyl groups are polymerized (also referred to as a vinyl polymer skeleton) is formed, and this skeleton contributes to excellent elastic deformation during pressure connection. On the other hand, if a silane monomer having a hydrolyzable group is used, a polysiloxane skeleton is formed by a siloxane bond generated by a hydrolysis condensation reaction, and this skeleton contributes to a high contact pressure with respect to the connected object at the time of pressure connection. To do.
The resin particles in the present invention are preferably resin particles containing the vinyl polymer skeleton from the viewpoint that the particles having the recovery rate characteristics of the present invention can be easily produced and the recovery rate characteristics can be easily controlled.

  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".

  Specifically, the vinyl-based crosslinkable monomer is a monomer having two or more vinyl groups in one molecule (vinyl monomer (1)), or one in one molecule. Monomer (vinyl monomer (2)) having a vinyl group and a functional group other than vinyl group (protic hydrogen-containing group such as carboxyl group and hydroxy group, terminal functional group such as alkoxy group). It is done. However, in the case of the vinyl monomer (2), in order to form a crosslinked structure as the vinyl crosslinking monomer, the vinyl monomer (2) has a carboxyl group, a hydroxy group, an alkoxy group, etc. It is necessary that a group to be a reaction (binding) partner exists in another monomer.

  Examples of the vinyl monomer (1) among the vinyl crosslinking monomers include, for example, allyl (meth) acrylates such as allyl (meth) acrylate; 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) acrylate , Decaethylene glycol di ( ) Acrylate, pentadecaethylene glycol di (meth) acrylate, pentacontahector 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 polyalkylene glycol di (meth) acrylates; 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 carbonization such as divinylbenzene, divinylnaphthalene and derivatives thereof Motokei crosslinking agent (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. The vinyl monomer (1) may be used alone or in combination of two or more.

  Examples of the vinyl monomer (2) among the vinyl crosslinking monomers include, for example, a monomer having a carboxyl group such as (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, Monomers having hydroxy groups such as hydroxy group-containing (meth) acrylates such as 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate, and hydroxy group-containing styrenes such as p-hydroxystyrene; 2 Alkoxy groups such as alkoxy group-containing (meth) acrylates such as methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, and alkoxystyrenes such as p-methoxystyrene And the like. The vinyl monomer (2) may be used alone or in combination of two or more.

  Specific examples of the silane crosslinkable monomer include a monomer having two or more vinyl groups in one molecule (silane monomer (1)), a hydrolyzable group in one molecule ( Monomers (silane monomer (2)) having three or more hydrolyzable groups such as alkoxy groups (alkoxysilyl groups) as well as hydroxy groups (silanol groups)) in one molecule. Decomposable groups (including hydrolyzable groups such as alkoxy groups (alkoxysilyl groups) as well as hydroxy groups (silanol groups)) and groups capable of binding to vinyl-based crosslinkable monomers (vinyl groups, the above-mentioned vinyl groups) A monomer (silane-based monomer (3)) having 3 or more monomers (groups which are reaction (bonding) partners) such as a carboxyl group, a hydroxy group, and an alkoxy group in the monomer (2). . Of these, the silane monomer (3) is preferable.

  Examples of the silane monomer (1) among the silane crosslinkable monomers include dimethyldivinylsilane, methyltrivinylsilane, tetravinylsilane, and the like. Silane monomer (1) may be used independently and may use 2 or more types together.

  Examples of the silane monomer (2) among the silane crosslinkable monomers include, for example, tetrafunctional silane monomers such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetrabutoxysilane. Examples of the polymer include trifunctional silane monomers such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. A silane monomer (2) may be used independently and may use 2 or more types together. The silane monomer (2) can be used alone or in the form of a (partial) hydrolysis and / or condensate with another silane monomer.

  Examples of the silane monomer (3) among the silane crosslinkable monomers include, for example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltri Those having (meth) acryloyl groups such as methoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxyethoxypropyltrimethoxysilane One having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3 4-epoxy Kurohekishiru) those having an epoxy group such as ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, those having an amino group such as 3-aminopropyltriethoxysilane; and the like. Silane monomer (3) may be used independently and may use 2 or more types together. The silane monomer (3) can be used alone or in the form of a (partial) hydrolysis and / or condensate with another silane monomer.

  The non-crosslinkable monomer constituting the resin particle is not particularly limited as long as it can be bonded to any of the crosslinkable monomers. For example, a non-crosslinkable monomer containing a vinyl group, a silicon-containing group is contained. Non-crosslinkable monomers are included. The non-crosslinkable monomer containing a vinyl group may be a monomer having one vinyl group in one molecule (vinyl monomer (3)) or the vinyl monomer (2 And vinyl monomer (2) in the case where no other monomer having a group that reacts with a functional group other than the vinyl group is present in the monomer component. The non-crosslinkable monomer containing a silicon-containing group is more specifically a hydrolyzable group such as one or two hydrolyzable groups (alkoxy group (alkoxysilyl group)) in one molecule. In addition, it is a monomer having a hydroxy group (including a silanol group) and no other binding group (such as a vinyl group) (silane monomer (4)).

  Examples of the vinyl monomer (3) among the vinyl non-crosslinkable monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) ) Acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) ) Acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate; cyclopropyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) Cycloalkyl (meth) acrylates such as acrylate, cyclooctyl (meth) acrylate, cycloundecyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, 4-t-butylcyclohexyl (meth) acrylate; Aromatic ring-containing (meth) acrylates such as phenyl (meth) acrylate, benzyl (meth) acrylate, tolyl (meth) acrylate, phenethyl (meth) acrylate; styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene Styrene-based monofunctional monomers such as alkyl styrenes such as α-methylstyrene and p-t-butylstyrene, halogen group-containing styrenes such as o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; Is The The vinyl monomer (3) may be used alone or in combination of two or more.

  Examples of the silane non-crosslinkable monomer (silane monomer (4)) include bifunctional silane monomers such as dimethyldimethoxysilane and dialkylsilane such as dimethyldiethoxysilane; trimethylmethoxysilane. And monofunctional silane monomers such as trialkylsilane such as trimethylethoxysilane. Silane monomer (4) may be used independently and may use 2 or more types together. The silane monomer (4) can be used alone or in the form of a (partial) hydrolysis and / or condensate with another silane monomer.

  The monomer component that forms the resin particles in the present invention is composed of the above-mentioned crosslinkable monomer and non-crosslinkable monomer, but the recovery rate characteristics (recovery rate at 10% compression of 30% or more, and always 0) % To 10% or less, and the monomer component has a content of the crosslinkable monomer of less than 20.0% by mass. And it is preferable to contain at least 1 sort (s) chosen from methyl (meth) acrylate and ethyl (meth) acrylate as a non-crosslinkable monomer.

  The content rate of the crosslinkable monomer in the monomer component (this content rate may be referred to as “crosslinking degree” in this specification) is, as described above, the recovery rate characteristic of the resin particles (30% or more). 10% compression recovery rate, and more than 0%, 10-60% recovery rate during compression) is preferably less than 20.0% by mass in the monomer component, More preferably, it is 15.0 mass% or less, More preferably, it is 12.0 mass% or less. The lower limit of the content of all crosslinkable monomers in the monomer component is preferably more than 1.0% by mass, more preferably 2.0% by mass, from the viewpoint that the resin particles have excellent solvent resistance. % Or more, more preferably 4.0% by mass or more.

  The non-crosslinkable monomer contained in the monomer component is a recovery rate characteristic of resin particles (a recovery rate during compression of 30% or more and a compression rate of 20% to 60% which is always greater than 0% and 10% or less). In controlling the recovery rate, it is preferably at least one selected from methyl (meth) acrylate and ethyl (meth) acrylate (hereinafter also referred to as “specific non-crosslinkable monomer”). The specific non-crosslinkable monomer is specifically selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate.

  The content of the specific non-crosslinkable monomer is not particularly limited, but is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 90% by mass or more, and most preferably 100% in all non-crosslinkable monomers. % By mass. The content of the non-crosslinkable monomer in the monomer component corresponds to the remainder obtained by removing all the crosslinkable monomers from the monomer component.

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 resin particles (base material). 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-Ti); copper, copper alloy (Cu and Fe, Co, Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, Ag, Au, Bi, An alloy with at least one metal element selected from the group consisting of Al, Mn, Mg, P and B, preferably an alloy with Ag, Ni, Sn, Zn); silver, a silver alloy (Ag and Fe, Co) At least one metal selected from the group consisting of Ni, Zn, Sn, In, Ga, Tl, Zr, W, Mo, Rh, Ru, Ir, Au, Bi, Al, Mn, Mg, P, and B Alloys with elements, preferably Ag-Ni, Ag-Sn, Ag-Zn); 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.) and the like are preferable. Of these, nickel and nickel alloys are preferred. The conductive metal layer may be a single layer or multiple layers. In the case of multiple layers, for example, a combination of nickel-gold, nickel-palladium, nickel-palladium-gold, nickel-silver, etc. Is preferred. It is preferable that the outermost metal layer in the conductive metal layer is a nickel layer or a gold layer because it is easy to confirm a good connection state by visual recognition. The nickel layer is a layer in which the metal constituting the metal layer is made of nickel or a nickel alloy, and the gold layer is a layer in which the metal constituting the metal layer is made of gold or a gold alloy.

  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, Most preferably, it is 0.15 micrometer or less. When the thickness of the conductive metal layer is within the above range, stable electrical connection can be maintained when the conductive fine particles are used as the anisotropic conductive material. 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 8.0 μm or more, more preferably 8.5 μm or more, further preferably 9.0 μm or more, and further preferably 10.0 μm or more and 51.0 μm or less. More preferably, it is 41.0 μm or less, more preferably 31.0 μm or less, and further preferably 26.0 μm or less. If the number average particle diameter is within this range, it can be suitably used for electrical connection of electrodes and wiring in semiconductor mounting used for, for example, touch panels and LEDs. Examples of the touch panel include connection of a touch panel lead-out circuit and a flexible printed wiring board (FPC).
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, if the insulating resin layer is too hard compared to the base particles (resin particles), the base particles themselves may be destroyed before the insulating resin layer is destroyed. Therefore, it is preferable to use an uncrosslinked or relatively low degree of crosslinking resin for the insulating resin layer.

  The insulating resin layer may be a single layer or a plurality of layers. For example, 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 to 1.0 μm, more preferably 0.02 μm to 0.5 μm, and 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.

  The conductive fine particles of the present invention 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 protrusions, when the conductive fine particles of the present invention are used for connection between the electrodes, a connection with a low initial resistance value can be easily obtained, and connection reliability can be further improved.

  As a method of forming protrusions on the surface of the conductive fine particles of the present invention, (1) In the polymerization step in the base particle synthesis, base particles having protrusions formed on the surface using the phase separation phenomenon of the polymer are used. After obtaining, a method of forming a conductive metal layer by electroless plating; (2) After attaching organic particles made of inorganic particles or organic polymers such as metal particles and metal oxide particles to the surface of the substrate particles A method of forming a conductive metal layer by electroless plating; (3) after performing electroless plating on the surface of the substrate particles, inorganic particles such as metal particles and metal oxide particles, or organic particles made of an organic polymer; (4) Utilizing the self-decomposition of the plating bath during the electroless plating reaction, depositing a metal that serves as the nucleus of the protrusion on the surface of the substrate particles, and further performing the electroless plating. By doing The method for forming a conductive metal layer a conductive metal layer including a protrusion becomes the continuous film; 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.

3. Manufacturing Method First, a method for manufacturing the resin particles as a base material will be described.
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.

  In the seed polymerization method, a part of the monomer component (seed particle forming monomer) is used as a seed particle preparation step, a seed particle is absorbed in the remainder of the monomer component (absorption monomer), and the seed particle is absorbed. In this method, resin particles are obtained through a polymerization step in which a monomer component is subjected to a polymerization reaction. 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 a vinyl crosslinkable monomer or a vinyl noncrosslinkable monomer is used as a seed forming monomer, the monomer is polymerized by a method such as soap-free emulsion polymerization or dispersion polymerization. Thus, seed particles may be prepared. In this case, it is preferable to use a styrene monofunctional monomer such as styrene as the seed forming monomer. In addition, when a silane-based crosslinkable monomer having a hydrolyzable group or a silane-based non-crosslinkable monomer is used as a seed-forming monomer, a solvent containing water (for example, alcohols, ketones, esters, The seed particles (polysiloxane particles) may be prepared by hydrolyzing the monomer in the (cyclo) paraffins, aromatic hydrocarbons or other organic solvent and water and subjecting the monomer to condensation polymerization. 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 remainder of the monomer component (absorbing monomer) in the absorption step is not particularly limited. For example, the absorption monomer is added to a seed particle dispersion in which seed particles are dispersed in a solvent in advance. Alternatively, seed particles may be added to the solvent containing the absorption monomer. In particular, in the former method, the reaction liquid obtained by polymerization, hydrolysis, or condensation may be used as a seed particle dispersion as it is. From the viewpoint of simplification of the process and productivity. The absorption monomer 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 (for example, an emulsifier is used in advance). It is preferable to add as an emulsified liquid by emulsifying and dispersing in a water-soluble organic solvent such as alcohols, ketones and esters, or a mixed solvent of these with water).

  When emulsifying and dispersing the absorption monomer with an emulsifier, examples of the emulsifier include an anionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene. Nonionic surfactants such as oxysorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, and oxyethylene-oxypropylene block polymers stabilize the dispersion of seed particles after the seed particles have absorbed the absorbing monomer. It is preferably used because it can also be used. The amount of water or aqueous medium used for emulsification and dispersion is usually 0.3 to 10 times the mass of the absorbing monomer.

In the absorption process, for determining whether or not the absorption monomer is absorbed by the seed particles, for example, before adding the absorption monomer and after completion of the absorption step, observe the particles with a microscope, and the particle size becomes larger due to absorption of the absorption monomer. It can be easily judged by confirming that 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 factor = (total mass of absorbed monomer 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 resulting particles tend to have insufficient mechanical properties. On the other hand, if the reaction temperature is too high, aggregation between particles tends to occur during polymerization. Tend. 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.

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.

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 is obtained by dispersing the conductive fine particles of the present invention in a binder resin. Such an anisotropic conductive material can sufficiently lower the initial resistance without impairing connection reliability even when subjected to pressure connection at a low pressure.
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 of resin particles, compression load value at x% compression>
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, a load is applied toward the center of the particle at a constant load speed (0.441 N / sec (0.045 kgf / sec)). The load value (10% compression load value) (mN) and the displacement amount (μm) at that time were measured. On the other hand, similarly, the load value (compression load value at the time of x% compression) (mN) when the compression displacement becomes 20%, 30%, 40%, 50% or 60% of the particle diameter was also measured. . In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value. Moreover, the said measurement was performed in 25 degreeC constant temperature atmosphere.
The 10% K value is obtained by converting the obtained 10% compressive load value (mN) into a compressive load (N), converting the displacement (μm) obtained at that time into a compressive displacement (mm), The particle radius (mm) was calculated from the average particle size (μm), 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))

<Recovery rate Rx (x = 10, 20, 30, 40, 50 and 60) at x% compression 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.). (Material: diamond), in the “soft surface detection” mode, at the constant load speed (0.441 N / sec (0.045 kgf / sec)) toward the center of the particles Compression was performed so that the compression load value became the maximum load, and the displacement amount (μm) at that time was measured, and this was defined as the maximum displacement amount L1. Next, the amount of displacement between the maximum load and the minimum load when the load is reduced to the minimum load (0.049 mN) at a constant unloading speed (0.441 N / sec (0.045 kgf / sec)) ( μm) was measured, and this was taken as a recovery displacement L2. The recovery rate was calculated based on the following equation from the maximum displacement amount L1 and the recovery displacement amount L2. The calculated value may be a negative value. In such a case, it is assumed that “0.0” is assumed. In addition, the measurement was performed on 10 different particles for each sample, and the average value was used as the measurement value. Moreover, the said compression test was done for every compression rate, and untested particle | grains were used for all the particles used for a compression test. The measurement was performed in a constant temperature atmosphere at 25 ° C.
Recovery rate (%) = (L2 / L1) × 100

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, 1003.1 parts of ion-exchanged water and 15.4 parts of 25% aqueous ammonia are added, and the monomer component (seed) is added from the dripping port with stirring. And 100.0 parts of 3-methacryloxypropyltrimethoxysilane (hereinafter also referred to as “MPTMS”) and 173.9 parts of methanol as hydrolysis monomers, and hydrolysis of 3-methacryloxypropyltrimethoxysilane, A condensation reaction was performed to prepare a dispersion of polymerizable polysiloxane particles (seed particles) having a methacryloyl group. The number-based average particle diameter of the polysiloxane particles was 4.30 μm.

  Next, 12.5 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“HITENOL (registered trademark) NF-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier is dissolved in 500 parts of ion exchange water. Divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd. “DVB960”: 96% divinylbenzene, 4% vinyl non-crosslinkable monomer (ethyl vinylbenzene, etc.)) (Hereinafter also referred to as “DVB”) 500.0 parts and 2,2′-azobis (2,4-dimethylvaleronitrile) (“V-65” manufactured by Wako Pure Chemical Industries, Ltd.) 12.0 parts A solution in which was dissolved was added and emulsified and dispersed to prepare an emulsion of the monomer component (absorption monomer). Two hours after the start of emulsification dispersion, the obtained emulsion was added to a dispersion of polysiloxane particles (seed particles), and further stirred. One hour after the addition of the emulsified liquid, the mixed liquid was sampled and observed with a microscope. As a result, it was confirmed that the polysiloxane particles were absorbed and absorbed.

  Next, 25.0 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt (“HITENOL (registered trademark) NF-08” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added, and the reaction solution was added under a nitrogen atmosphere. The temperature was raised to 65 ° C. and held at 65 ° C. 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 baked at 280 ° C. for 1 hour in a nitrogen atmosphere to obtain resin particles (1). Table 1 shows the physical properties of the resin particles obtained.

(Production Example 2)
After appropriately changing the amount of ion-exchanged water, methanol, and ammonia water to produce seed particles with a number-based average particle size of 4.94 μm, the type and amount of the absorbing monomer was divinylbenzene (manufactured by Nippon Steel Chemical Co., Ltd.). "DVB960": Divinylbenzene 96%, vinyl-based non-crosslinkable monomer (ethyl vinylbenzene etc.) 4% -containing product; DVB) 375.0 parts and styrene (hereinafter also referred to as "St") 125.0 Except having changed into the part, it carried out similarly to manufacture example 1, and obtained the resin particle (2). Table 1 shows the physical properties of the resin particles obtained.

(Production Example 3)
Divinylbenzene (“DVB960” manufactured by Nippon Steel Chemical Co., Ltd .: divinylbenzene 96%, vinyl non-crosslinkable monomer (ethyl vinylbenzene etc.) 4% containing product; DVB) 250.0 Resin particles (3) were obtained in the same manner as in Production Example 1 except that the amount of styrene (St) was changed to 250.0 parts. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 4)
The type and amount of the absorbing monomer are 800.0 parts of cyclohexyl methacrylate (hereinafter also referred to as “CHMA”) and 1,6-hexanediol dimethacrylate (hereinafter also referred to as “1.6HX”) 200.0. The resin particles (4) were obtained in the same manner as in Production Example 1, except that the drying was performed at 80 ° C. for 4 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 5)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle size of 3.24 μm, the type and amount of the absorbing monomer are set to 2000.0 parts of cyclohexyl methacrylate (CHMA). The resin particles (5) were obtained in the same manner as in Production Example 1, except that the drying was performed at 40 ° C. for 12 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 6)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle size of 3.24 μm, the type and amount of the absorption monomer are referred to as methyl methacrylate (hereinafter referred to as “MMA”). The resin particles (6) were obtained in the same manner as in Production Example 1 except that the content was changed to 2000.0 parts and dried at 80 ° C. for 4 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.
For the resin particles (6), the compression rate was further changed from 20% to 60% at appropriate intervals to obtain the recovery rate at each compression rate. there were. In Table 1 below, the recovery rates when the compression rates are 10%, 20%, 30%, 40%, 50%, and 60% are extracted and shown.

(Production Example 7)
The amount of ion-exchanged water, methanol, and ammonia water was appropriately changed to produce seed particles having a number-based average particle size of 4.57 μm, and the type and amount of absorption monomer was 750.0 parts methyl methacrylate (MMA). The resin particles (7) were obtained in the same manner as in Production Example 1, except that the drying was performed at 80 ° C. for 4 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.
For the resin particles (7), the compression rate was further changed from 20% to 60% at appropriate intervals to obtain the recovery rate at each compression rate, but both were in the range of more than 0.0% and 10% or less. there were. In Table 1 below, the recovery rates when the compression rates are 10%, 20%, 30%, 40%, 50%, and 60% are extracted and shown.

(Production Example 8)
The amount of ion-exchanged water, methanol, and aqueous ammonia was appropriately changed to produce seed particles having a number-based average particle size of 3.24 μm, and then the type and amount of absorbing monomer were changed to t-butyl methacrylate (hereinafter “tBMA”). The resin particles (8) were obtained in the same manner as in Production Example 1 except that the content was changed to 2000.0 parts and dried for 12 hours at 40 ° C. in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 9)
The amount of ion-exchanged water, methanol, and ammonia water was appropriately changed to produce seed particles having a number-based average particle size of 4.95 μm, and then the type and amount of absorption monomer were changed to 600.0 parts of styrene (St). Resin particles (9) were obtained in the same manner as in Production Example 1, except that the drying was performed at 80 ° C. for 4 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 10)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle diameter of 4.76 μm, the type and amount of the absorbing monomer are referred to as ethyl methacrylate (hereinafter referred to as “EMA”). The resin particles (10) were obtained in the same manner as in Production Example 1 except that the content was changed to 2000.0 parts and dried for 12 hours at 40 ° C. in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.
For the resin particles (10), the compression rate was further changed from 20% to 60% at appropriate intervals to obtain the recovery rate at each compression rate, but all were in the range of more than 0.0% and 10% or less. there were. In Table 1 below, the recovery rates when the compression rates are 10%, 20%, 30%, 40%, 50%, and 60% are extracted and shown.

(Production Example 11)
After appropriately changing the amount of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle size of 4.41 μm, the type and amount of the absorbing monomer was changed to 1000.0 parts of styrene (St). Resin particles (11) were obtained in the same manner as in Production Example 1, except that the drying was performed at 80 ° C. for 4 hours in a nitrogen atmosphere instead of firing. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 12)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle size of 4.76 μm, the type and amount of the absorbing monomer were changed to n-butyl methacrylate (hereinafter “nBMA”). 900.0 parts and 1,6-hexanediol dimethacrylate (1.6HX) are changed to 100.0 parts, and instead of firing, they are dried at 40 ° C. for 12 hours under a nitrogen atmosphere. Resin particles (12) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 13)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle diameter of 4.76 μm, the type and amount of the absorbing monomer were changed to n-butyl methacrylate (nBMA) 900. Except for changing to 0 part and 100.0 parts of 1,9-nonanediol diacrylate (hereinafter sometimes referred to as “1.9NDA”) and drying at 40 ° C. for 12 hours in a nitrogen atmosphere instead of firing, Resin particles (13) were obtained in the same manner as in Production Example 1. Table 1 shows the physical properties of the resin particles obtained.

(Production Example 14)
After appropriately changing the amounts of ion-exchanged water, methanol, and ammonia water to produce seed particles having a number-based average particle diameter of 4.76 μm, the type and amount of the absorbing monomer were changed to n-butyl methacrylate (nBMA) 900. Except that 0 part and 1,6-hexanediol diacrylate (hereinafter sometimes referred to as “1.6HXA”) are 100.0 parts and dried at 40 ° C. for 12 hours in a nitrogen atmosphere instead of firing. Resin particles (14) were obtained in the same manner as in Production Example 1. 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
Resin particles (6) are used as a base material, the base material is etched with sodium hydroxide, then sensitized by contacting with a tin dichloride solution, and then immersed in a palladium dichloride solution. Palladium nuclei were formed by the method of batting (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-exchanged water and methanol in that order, and vacuum drying at 100 ° C. for 2 hours to obtain nickel-plated particles. Next, the obtained nickel plating particles were added to a displacement gold plating solution containing potassium gold cyanide, and gold plating was further performed on the surface of the nickel layer to obtain conductive fine particles. The film thickness of the conductive metal layer in the obtained conductive fine particles was 0.12 μm.

(Examples 2-3, Comparative Examples 1-11)
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 0.12 μm in any example.

3. Production and Evaluation of Anisotropic Conductive Material Using conductive fine particles obtained in Examples and Comparative Examples, an anisotropic conductive material (anisotropic conductive paste) was produced by the following method, and pressure-connected The connection state was evaluated visually. The evaluation results are shown in Table 1.
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 100 μm and a glass substrate on which an aluminum pattern is formed at a pitch of 100 μm, and is thermocompression bonded under pressure bonding conditions of 4 MPa and 150 ° C. At the same time, the connection structure was obtained by curing the binder resin.

The electrode surface on the side of the glass substrate on which the ITO electrode of the obtained connection structure was wired was observed with an optical microscope (magnification: 1000 times), and the state of 10 conductive fine particles was determined according to the following criteria. The case where all of the 10 conductive fine particles were “good” was evaluated as “◯”, and the case where even one was “bad” was evaluated as “x”.
Good: When the long diameter of the contact surface of the conductive fine particles in contact with the glass substrate is larger than the particle diameter (number average particle diameter) of the conductive fine particles, and all the plating layers are connected to one on the contact surface. When the long diameter of the contact surface of the conductive fine particles in contact with the glass substrate is smaller than the particle diameter (number average particle diameter) of the conductive fine particles, or when the plating layer is torn at the contact surface

  Next, the initial resistance value between electrodes was measured for the connection structures of Examples 1 to 3 in which an evaluation of “◯” was obtained by the above visual evaluation. As a result, as predicted from the results of the visibility evaluation, the initial resistance values were all good (5Ω or less).

  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, for example, anisotropic conductive pastes and anisotropic conductive films for touch panel mounting.

Claims (5)

Conductive fine particles having resin particles and at least one conductive metal layer formed on the surface of the resin particles,
The number average particle diameter of the resin particles is 8 to 50 μm,
The compression elastic modulus when the diameter of the resin particles is displaced by 10% is 100 to 3000 N / mm ² ,
The recovery rate after compressing the resin particles to 10% of the diameter is 30% or more, and the recovery rate after compressing the resin particles to an arbitrary displacement amount between 20 to 60% of the diameter is always 0. Conductive fine particles characterized by being over 10% and up to 10%.   The conductive fine particles according to claim 1, wherein the resin particles have a number average particle diameter of 10 μm or more.   The conductive fine particles according to claim 1, wherein the outermost metal layer in the conductive metal layer is a nickel layer or a gold layer.   The resin particles are formed from a monomer component containing a crosslinkable monomer and a non-crosslinkable monomer, the crosslinkable monomer content in the monomer component is less than 20.0% by mass, and the non-crosslinkable The electroconductive fine particle as described in any one of Claims 1-3 in which a conductive monomer contains at least 1 sort (s) chosen from methyl (meth) acrylate and ethyl (meth) acrylate.   An anisotropic conductive material comprising the conductive fine particles according to any one of claims 1 to 4 dispersed in a binder resin.