KR20230056664A - Coated particle and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide coated particles capable of enhancing conduction reliability and insulation reliability, which include conductive particles having a metal coating formed on the surface of a core material, and insulating fine particles covering the conductive particles, comprising: A. is a coated particle that is an insulating fine particle that does not have a glass transition temperature and has a sphericity of 0.90 or more. The surface layer of the insulating fine particles is preferably a polymer containing a crosslinkable monomer component, and is also preferably a polymer containing a monomer component having a functional group having a charge.

Description

Coated particle and its manufacturing method

The present invention relates to coated particles in which conductive particles are coated on an insulating layer.

BACKGROUND ART Conductive particles having a metal coating such as nickel or gold formed on the surface of resin particles are used as conductive materials such as conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives.

BACKGROUND OF THE INVENTION [0002] In recent years, with further miniaturization of electronic devices, the circuit width and pitch of electronic circuits are becoming smaller and smaller. In connection with this, as the conductive particles used for the above-mentioned conductive adhesive, anisotropic conductive film, anisotropic conductive adhesive, etc., those having a small particle size are required. When such small-diameter conductive particles are used, the amount of conductive particles in the conductive material must be increased in order to improve the connectivity. However, when the compounding amount of conductive particles is increased, a short circuit occurs due to conduction in an unintended direction, that is, conduction in a direction different from that between opposing electrodes, and it is difficult to obtain insulation in that direction. .

In order to solve the above problem, an insulating layer-coated conductive particle is used in which the surface of the conductive particle is coated with an insulating substance having a functional group having an affinity for the metal film, and the contact between the metal film of the conductive particle is prevented. there is. In coated particles having such a structure, normally, by thermally compressing the coated particles between electrodes, the insulating layer is melted, deformed, or peeled off, thereby exposing the metal surface of the conductive particles, thereby enabling conduction between the electrodes. A technique for improving characteristics such as conduction reliability by examining constituent components of an insulating layer is known.

For example, in Patent Document 1, it is possible to reliably conduct electrical connection between substrates by means of conductive particles coated with core-shell particles whose glass transition temperature or softening temperature of the shell layer is higher than the glass transition temperature or softening temperature of the core particles. In addition, it is described that leakage between adjacent particles can be prevented. Further, in Patent Document 2, a core containing a copolymer of styrene and 2-ethylhexyl acrylate and a shell containing a copolymer of styrene and acrylic acid, having a glass transition temperature of -30 to 150 ° C., is water-soluble and dispersible. It is described that it was found that the conductive particles coated with the shell particles had excellent current feeding and insulating properties. Further, in Patent Literature 3, conductive particles coated with resin particles having a glass transition temperature of 180° C. or less and containing a copolymer of a polymerizable component essentially containing at least an alkyl (meth)acrylate and a polyvalent (meth)acrylate, It is described that it is possible to provide insulated conductive particles capable of reliably suppressing lateral conduction while maintaining good conduction between opposing electrodes.

Japanese Unexamined Patent Publication No. 2005-149764 Japanese Patent Publication No. 2006-525641 Japanese Unexamined Patent Publication No. 2012-72324

However, when the anisotropic conductive material using the conductive particles described in Patent Documents 1 to 3 is thermally compressed between electrodes, the insulating resin particles cannot maintain the desired hardness, and between the conductive layer of the conductive particles and the electrode, There was a problem that the desired conductivity could not be expressed due to the problem that the deformed insulating resin particles were mixed and remained. In order to reduce the effect on the hardness of the resin particles when heat is applied, it is conceivable to obtain harder resin particles by polymerizing by increasing the proportion of the crosslinkable monomer component in the production of the resin particles, but the proportion of the crosslinkable monomer component If is increased, the shape of the particles is distorted and control of the particle diameter becomes difficult, causing problems in insulation reliability.

Accordingly, an object of the present invention is to provide coated particles capable of improving conduction reliability and insulation reliability that have solved the above problems.

As a result of intensive research to solve the above problems, the inventors of the present invention have found that, when obtaining insulating fine particles, a non-crosslinkable monomer component is polymerized to obtain a spherical core material portion, and then a crosslinkable monomer component is added and polymerized to obtain glass. It was found that insulating fine particles having a spherical shape and a uniform particle diameter were obtained without a transition temperature and having a required hardness. And, since the insulating fine particles obtained in this way are difficult to deform during thermal compression bonding, maintain a spherical shape, and are efficiently excluded without remaining between the conductive layer and the electrode, the conductive particles coated with the insulating fine particles, It was found that it had excellent conduction reliability, and the present invention was completed.

That is, the present invention is a coated particle comprising conductive particles having a metal film formed on the surface of a core material and insulating fine particles covering the conductive particles, wherein the insulating fine particles do not have a glass transition temperature and have an insulating property of 0.90 or more in sphericity. It is to provide coated particles which are fine particles.

In addition, the present invention is a method for producing coated particles having conductive particles having a metal film formed on the surface of a core material and insulating fine particles covering the conductive particles,

A first step of polymerizing a non-crosslinkable monomer component to obtain an insulating fine particle precursor; a second step of obtaining insulating fine particles by polymerizing a polymerizable compound containing a crosslinkable monomer component in the presence of an insulating fine particle precursor; It is to provide a method for producing coated particles comprising a third step of mixing the dispersion liquid and conductive particles and adhering the insulating fine particles to the surface of the conductive particles.

ADVANTAGE OF THE INVENTION According to this invention, since it is possible to obtain coated particles coated with insulating fine particles having a spherical shape and uniform particle size and no glass transition temperature, coated particles excellent in conduction reliability and insulation reliability and a manufacturing method thereof can be provided.

1 is a SEM image of insulating fine particles obtained in Example 1.
Fig. 2 is a DSC curve obtained by differential scanning calorimetry of insulating fine particles obtained in Example 1.
3 is a SEM image of the coated particles obtained in Example 1.
4 is a SEM image of insulating fine particles obtained in Example 2.
Fig. 5 is a DSC curve obtained by differential scanning calorimetry of insulating fine particles obtained in Example 2.
6 is a SEM image of insulating fine particles obtained in Comparative Example 1.
Fig. 7 is a DSC curve obtained by differential scanning calorimetry of insulating fine particles obtained in Comparative Example 1.
8 is a SEM image of insulating fine particles obtained in Comparative Example 2.
Fig. 9 is a DSC curve obtained by differential scanning calorimetry of insulating fine particles obtained in Comparative Example 2.
10 is a SEM image of insulating fine particles obtained in Comparative Example 3.
11 is a DSC curve obtained by differential scanning calorimetry of insulating fine particles obtained in Comparative Example 3.

Hereinafter, the coated particle of this invention is demonstrated based on the preferred embodiment. The coated particles of the present invention are coated particles comprising conductive particles having a metal film formed on the surface of a core material and insulating fine particles covering the conductive particles, wherein the insulating fine particles do not have a glass transition temperature and have a sphericity of 0.90 It is characterized in that it is an insulating fine particle having the above.

As the conductive particles, known ones conventionally used for conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives can be used.

As the core material in the conductive particles, it is particulate, and even if it is an inorganic substance or an organic substance, it can be used without particular limitation. Examples of inorganic core material particles include metal particles such as gold, silver, copper, nickel, palladium, and solder, alloys, glass, ceramics, silica, oxides of metals or nonmetals (including hydrated compounds), and metals containing aluminosilicates. silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal acid salts, metal halides, and carbon. On the other hand, as organic core material particles, for example, natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid ester, polyacrylonitrile, polyacetal, ionomer, thermoplastic resins such as polyester, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, and diallylphthalate resins. These may be used independently and may be used in combination of 2 or more type.

The core material particles may be composed of a material composed of both an inorganic substance and an organic substance instead of the material composed of any one of the inorganic substance and the organic substance described above. When the core particle is composed of a material composed of both an inorganic substance and an organic substance, the existence mode of the inorganic substance and the organic substance in the core particle particle is, for example, a core composed of an inorganic substance and an inorganic substance covering the surface of the core configurations of a core-shell type, such as an aspect comprising a shell made of an organic material and an aspect comprising a core made of an organic material and a shell made of an inorganic material covering the surface of the core; In addition to these, a blend type structure in which inorganic substances and organic substances are mixed or randomly fused in one core material particle, and the like are exemplified. As the core particle composed of a material composed of both inorganic and organic substances, the above-mentioned inorganic core particle or organic core particle may be used. These core material particles may be used to constitute each of the inorganic and organic materials alone, or may be used to constitute a combination of two or more types of materials of each of the inorganic and organic materials.

The core material particles are preferably composed of an organic substance or a material composed of both an inorganic substance and an organic substance, and more preferably composed of a material composed of both an inorganic substance and an organic substance. The inorganic material includes glass, ceramic, silica, metal or nonmetal oxides (including hydrous compounds), metal silicates including aluminosilicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, and metals. Acid salts, metal halides and carbon are preferred. In addition, the organic material is a thermoplastic resin such as natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid ester, polyacrylonitrile, polyacetal, ionomer, and polyester. desirable. By using a core material made of such a material, dispersion stability between particles can be improved, and conduction can be enhanced by exhibiting appropriate elasticity at the time of electrical connection of electronic circuits.

In the case of using an organic material as the core material particle, it does not have a glass transition temperature or the glass transition temperature exceeds 100 ° C., so that the shape of the core material particle is easily maintained in the anisotropic conductive connection step or the process of forming a metal film It is preferable in that it is easy to maintain the shape of the core material particles. In addition, when the core particles have a glass transition temperature, the glass transition temperature is preferably 200° C. or lower in view of easy softening of the conductive particles in anisotropic conductive connection and a large contact area, making it easy to conduct. From this point of view, when the core material particles have a glass transition temperature, the glass transition temperature is more preferably higher than 100°C and lower than or equal to 180°C, and particularly preferably higher than 100°C and lower than or equal to 160°C. A glass transition temperature can be measured by the method described in the Example mentioned later.

In the case of using an organic substance as the core material particle, when the organic substance is a highly crosslinked resin, the glass transition temperature is hardly observed even when the measurement is attempted up to 200°C by the method described in the Examples below. In this specification, such particles are also referred to as particles having no glass transition point, and in the present invention, such core particles may be used. As a specific example of the above-described core particulate material having no glass transition temperature, it can be obtained by copolymerizing the monomers constituting the organic matter exemplified above with a crosslinkable monomer in combination. Examples of crosslinkable monomers include tetramethylene di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, and ethylene oxide di(meth)acrylate. , tetraethylene oxide (meth) acrylate, 1,6-hexanedi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimethylolpropane tri ( meth)acrylate, tetramethylolmethanedi(meth)acrylate, tetramethylolmethanetri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, tetramethylolpropanetetra(meth)acrylate, di Polyfunctional (meth)acrylates such as pentaerythritol penta(meth)acrylate, glycerol di(meth)acrylate, and glycerol tridi(meth)acrylate, polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene , vinyltrimethoxysilane, trimethoxysilylstyrene, silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, triallyl isocyanurate, diallyl phthalate, diallyl acrylamide, diallyl Monomers, such as ether, are mentioned. In particular, in the field of COG (Chip on Glass), core particles made of hard organic materials are widely used.

There is no particular restriction on the shape of the core material particles. Generally, the core material particles are spherical. However, the core material particles may be in a shape other than spherical, for example, fibrous, hollow, plate-like or acicular, and may have a large number of protrusions on their surface or may be irregular. In the present invention, spherical core particles are preferable in terms of excellent filling properties and easy coating of metal.

The shape of the conductive particles varies depending on the shape of the core particle, but is not particularly limited. For example, it may be fibrous, hollow, plate-like, or acicular, and may have projections on its surface or may be irregular. In the present invention, it is preferable to have a spherical shape or a shape having projections on the surface from the viewpoint of excellent filling properties and connectivity. When the electroconductive particle has a shape having a projection on the surface, it is preferable to have a plurality of projections on the surface, and it is more preferable to have a plurality of projections on the spherical surface. When the conductive particles have a plurality of protrusions, the core material particles may have a plurality of protrusions, or the core material particles may have no protrusions and the metal film may have a plurality of protrusions. Preferably, the core material particles do not have protrusions, and the metal film has a plurality of protrusions.

The coated particle of the present invention may have protrusions on the surface of the conductive particle in order to ensure electrical conduction. By having projections on the surface of the conductive particles, the insulating layer can be effectively pushed out by the projections when the conductive particles are compressed by electrodes during mounting. The height H of the protrusion of the conductive particles is preferably H/L of 0.1 or more when the thickness of the insulating layer is L, from the viewpoint of ensuring electrical conduction while excluding the insulating layer during mounting. Moreover, it is preferable that H/L is 10 or less from a viewpoint of obtaining insulating property in the direction different from filling property and a counter electrode. From these points, as for H/L, it is still more preferable that they are 0.2 or more and 5 or less. In these preferred ranges, the thickness L indicates the average particle diameter of insulating fine particles when the insulating layer is insulating fine particles.

It is preferable that the height H of a processus|protrusion is 20 nm or more on average, and especially 50 nm or more. The number of protrusions is preferably from 1 to 20,000, particularly from 5 to 5,000 per particle, from the viewpoint of further improving the conductivity of the conductive particles, although it also depends on the particle size of the conductive particles. Moreover, the aspect ratio of the protrusion is preferably 0.3 or more, more preferably 0.5 or more. When the aspect ratio of the protrusion is large, it is advantageous because the oxide film formed on the surface of the electrode can be easily torn. The aspect ratio is a value defined by the ratio of the height H of the projection to the length D of the base of the projection, that is, H/D. The height H of the protrusion and the length D of the base of the protrusion are average values measured for 20 different particles observed by an electron microscope, and the aspect ratio of the protrusion is the aspect ratio of the 20 different particles observed by an electron microscope. Calculate and find the average value. The length D of the base refers to the length along the surface of the conductive particle of the base of the projection in an electron microscope image.

As the aspect ratio of the projection formed on the surface of the conductive particles is as described above, the length D itself of the base of the projection is preferably 5 to 500 nm, particularly 10 to 400 nm, and the height H of the projection is 20 to 500 nm, particularly preferably 50 to 400 nm.

The metal film in the conductive particles has conductivity, and examples of the constituent metals include gold, platinum, silver, copper, iron, nickel, tin, lead, antimony, bismuth, cobalt, indium, titanium, metals such as germanium, aluminum, chromium, palladium, tungsten, and molybdenum, or alloys thereof, as well as metal compounds such as ITO and solder; and the like. Among them, gold, silver, copper, nickel, palladium or solder is preferable because of its low resistance, and in particular, nickel, gold, nickel alloy or gold alloy, when the insulating fine particles of the present invention described later have a functional group, that It is preferably used because of its high bondability to functional groups. The metal in electroconductive particle can be used 1 type or in combination of 2 or more types.

The metal film may have a single-layer structure or a laminated structure composed of a plurality of layers. In the case of a laminated structure composed of a plurality of layers, it is preferable that the outermost layer is nickel, gold, a nickel alloy, or a gold alloy. The outermost layer of the metal film preferably has a small amount of palladium, preferably 5% by mass or less, more preferably 1% by mass or less, and most preferably does not contain palladium from the viewpoint of reducing the amount of expensive noble metal.

In addition, the metal film does not have to cover the entire surface of the core material particle, and may cover only a part thereof. When only a part of the surface of the core material particle is covered, the covered portion may be continuous or, for example, may be discontinuously coated in an island shape. As for the thickness of a metal film, 0.001 micrometer or more and 2 micrometers or less are mentioned preferably.

As a method of forming a metal film on the surface of the core particle, a dry method using a vapor deposition method, a sputtering method, a mechanochemical method, a hybridization method, or the like, or a wet method using an electrolytic plating method, an electroless plating method, or the like. Moreover, you may form a metal film on the surface of a core particle|grain by combining these methods.

The average particle diameter of the conductive particles is preferably 0.1 μm or more and 50 μm or less, more preferably 1 μm or more and 30 μm or less. When the average particle diameter of the conductive particles is within the above range, the obtained coated particles do not generate a short circuit in a direction different from that between the opposing electrodes, and conduction between the opposing electrodes is easily ensured. In addition, in this invention, the average particle diameter of electroconductive particle is the average value of the particle diameter measured using the scanning electron microscope (Scanning Electron Microscope: SEM). In the case where the conductive particles are spherical in the scanning electron microscope image, the particle diameter measured using SEM is the diameter of the circular conductive particle image. When electroconductive particle is not spherical, the particle diameter measured using SEM says the largest length (maximum length) among the line segments which cross the image of electroconductive particle. This also applies to the average particle diameter of insulating fine particles described later. However, when electroconductive particle has a processus|protrusion, let the average particle diameter be the average of said maximum length with respect to a part other than a processus|protrusion.

Specifically, the average particle diameter of conductive particles is measured by the method described in Examples.

The insulating fine particles covering the conductive particles used in the present invention do not have a glass transition temperature. As a result, since the coated particles of the present invention are coated with insulating fine particles that are hardly deformed during thermal compression bonding, the insulating fine particles do not remain between the conductive layer and the electrode and are effectively eliminated. For this reason, since the connection of the coated particle of this invention with an electrode increases, the conduction reliability can be expected to improve while having the effect of preventing a short circuit in a direction different from that between opposing electrodes.

As for the measuring method of glass transition temperature, the following method is mentioned, for example.

A sample of 0.04 to 0.06 g is heated up to 200°C using a differential scanning calorimeter (for example, "STAR SYSTEM" manufactured by METTLER TOLEDO), and then cooled from the temperature to 25°C at a cooling rate of 5°C/min. Then, the sample is heated at a heating rate of 5°C/min, and the calorific value is measured. When a peak is observed, the temperature of the peak is obtained. When no peak is observed and a step difference is observed, the temperature at the intersection of the tangent line representing the maximum slope of the curve of the step portion and the extension line of the base line on the high temperature side of the step difference is obtained. at the transition temperature.

In the present invention, "not having a glass transition temperature" means that neither a peak nor a level difference is observed when differential scanning calorimetry is performed by the above method.

As for the insulating fine particles in the present invention, it is preferable that at least the surface layer thereof is made of a polymer containing a crosslinkable monomer component. When the surface layer of the insulating fine particles is a polymer containing a crosslinkable monomer component, it is possible to obtain hard insulating fine particles that do not have a glass transition temperature and can withstand high temperatures during thermal compression bonding. In addition, as for the insulating fine particles in the present invention, it is preferable that the core material portion is made of a polymer obtained by polymerizing a non-crosslinkable monomer component. When the core portion of the insulating fine particles is a polymer obtained by polymerizing a non-crosslinkable monomer component, it is easy to obtain spherical insulating fine particles having a uniform particle size. Further, the core material may be a polymer polymerized by adding a crosslinkable monomer component in an arbitrary amount in addition to the non-crosslinkable monomer component from the viewpoint of maintaining the strength of the insulating fine particles, as long as the spherical shape can be maintained. From the above, from the viewpoint of obtaining insulating fine particles having the range of sphericity described later and not having a glass transition temperature, in particular, a spherical core part composed of a polymer obtained by polymerizing a non-crosslinkable monomer component and a crosslinkable monomer component. It is made of a surface layer portion made of a polymer that does not have a glass transition temperature as a whole.

Examples of the crosslinkable monomer component constituting the insulating fine particles in the present invention include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; Allyl methacrylate, triacryl formal, triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di( meth)acrylate, 1,9-nonanedioldi(meth)acrylate, 1,10-decanedioldi(meth)acrylate, polyethylene glycoldi(meth)acrylate, neopentylglycoldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate, dimethylol-tricyclodecane diacrylate, pentaerythritol tri(meth)acrylate, pentaerythritol Tetraacrylate, dipentaerythritol hexaacrylate, neopentyl glycol acrylate benzoate, trimethylolpropane acrylate benzoate, 2-hydroxy-3-acryloyloxypropyl methacrylate, hydroxypivalic acid neopentyl glycol di Compounds having two or more polymerizable ethylenically unsaturated bonds, such as polyfunctional acrylate compounds such as acrylates, ditrimethylolpropane tetraacrylate, and 2-butyl-2-ethyl-1,3-propanediol diacrylate; can be heard You may use these individually or in combination of 2 or more types. When the insulating fine particles contain a plurality of types of crosslinkable monomer components, the presence of the structural units of the crosslinkable monomer components in the polymer may be random, alternating, or block as a copolymer.

In the present invention, the crosslinkable monomer component is divinylbenzene, allyl methacrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1 It is preferably at least one selected from 4-butanedioldi(meth)acrylate, 1,9-nonanedioldi(meth)acrylate and 1,10-decanedioldi(meth)acrylate. By having such a polymer containing a crosslinkable monomer component on at least the surface layer of the insulating fine particles, not only can the effect of preventing a short circuit in a direction different from that between the opposing electrodes be obtained, but also the insulating fine particles are formed between the conductive layer and the electrode during thermal compression bonding. It does not remain and is effectively excluded.

In the polymer constituting the insulating fine particles according to the present invention, the compounding amount of the crosslinkable monomer component in all constituent units is more than 20% by mass and 95% by mass or less, preferably 21% by mass or more and 80% by mass or less. By blending the crosslinkable monomer component within this range, insulating fine particles having no glass transition temperature and desired hardness upon thermal compression bonding can be obtained.

It is preferable that the insulating fine particles in the present invention further contain a compound containing a functional group having an electric charge. As a result, the coated particle of the present invention has high adhesion between the conductive particle and the insulating fine particle. For this reason, the coated particle of the present invention easily exerts an effect of preventing short circuit in a direction different from that between the opposing electrodes, and an improvement in insulating property in the direction can be expected. In particular, it is preferable that the surface layer of the insulating fine particles is a polymer containing a monomer component having a functional group having an electric charge.

Examples of the functional group having an electric charge include an onium-based functional group such as a phosphonium group, an ammonium group, and a sulfonium group, an amino group, and the like. Among these, it is preferably an ammonium group or a phosphonium group, more preferably a phosphonium group, from the viewpoint of improving the adhesion between conductive particles and insulating fine particles and forming coated particles having both insulation and conduction reliability at a high level.

As the functional group having an electric charge, those represented by the following general formula (1) are preferably exemplified.

[Formula 1]

(Wherein, X is a phosphorus atom, nitrogen atom, or sulfur atom, R may be the same or different, and is a hydrogen atom, a linear, branched or cyclic alkyl group, or an aryl group. n is It is 1 when X is a nitrogen atom or a phosphorus atom, and 0 when X is a sulfur atom. * is a bond.)

As a counter ion for a cationic group, a halide ion is mentioned, for example. Examples of halide ions include Cl ^- , F ^- , Br ^- , and I ^- .

In Formula (1), as a linear alkyl group represented by R, a C1-C20 linear alkyl group is mentioned, for example, Specifically, a methyl group, an ethyl group, n-propyl group, n- Butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n - Tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, etc. are mentioned.

In Formula (1), as a branched-chain alkyl group represented by R, a C3-C8 branched alkyl group is mentioned, for example, and, specifically, an isopropyl group, an isobutyl group, s-butyl group, t-butyl group, isopentyl group, s-pentyl group, t-pentyl group, isohexyl group, s-hexyl group, t-hexyl group, ethylhexyl group and the like.

In formula (1), examples of the cyclic alkyl group represented by R include cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctadecyl group. can be heard

In Formula (1), as an aryl group represented by R, a phenyl group, a benzyl group, a tolyl group, an o-xylyl group, etc. are mentioned.

In the general formula (1), R increases the adhesion between the conductive particles and the insulating fine particles, and when thermally compressed inside the anisotropic conductive film, the insulating fine particles are detached from the conductive particles and conduction is easily ensured. It is preferably an alkyl group of 1 or more and 12 or less, more preferably an alkyl group of 1 or more and 10 or less carbon atoms, and most preferably an alkyl group of 1 or more and 8 or less carbon atoms. In addition, it is also preferable that R is a linear alkyl group from the viewpoint that it is easy for the insulating fine particles to come close to and adhere to the conductive particles.

Examples of the monomer component having a functional group having an electric charge include a compound having a functional group having an electric charge and a polymerizable ethylenically unsaturated bond. Specifically, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropylacrylamide, N,N,N-trimethyl-N as polymerizable compounds having an ethylenically unsaturated bond having an onium-based functional group Compounds having an ammonium group such as -2-methacryloyloxyethylammonium chloride; compounds having a sulfonium group such as phenyldimethylsulfonium methacrylate and methyl sulfate; 4-(vinylbenzyl)triethylphosphonium chloride, 4-(vinylbenzyl)trimethylphosphonium chloride, 4-(vinylbenzyl)tributylphosphonium chloride, 4-(vinylbenzyl)trioctylphosphonium chloride, 4-( Vinylbenzyl) triphenylphosphonium chloride, 2- (methacryloyloxyethyl) trimethylphosphonium chloride, 2- (methacryloyloxyethyl) triethylphosphonium chloride, 2- (methacryloyloxyethyl) and compounds having phosphonium groups such as tributylphosphonium chloride, 2-(methacryloyloxyethyl)trioctylphosphonium chloride, and 2-(methacryloyloxyethyl)triphenylphosphonium chloride.

In this invention, it is preferable that the monomer component which has a functional group which has an electric charge is at least 1 sort(s) chosen from the compound which has the said ammonium group and the compound which has the said phosphonium group. By having a polymer containing a monomer component having a functional group having such an electric charge on at least the surface layer of the insulating fine particles, the adhesion between the conductive particles and the insulating fine particles can be improved, and the insulating fine particles can be arranged in a regular manner. Therefore, insulation and conduction can be achieved. Coated particles having a high level of reliability are obtained.

In the polymer constituting the insulating fine particles according to the present invention, the proportion of structural units to which a functional group having an electric charge is bonded among all structural units is preferably 0.01 mol% or more and 5.0 mol% or less, and is 0.02 mol% or more and 2.0 mol%. It is more preferable that it is below. Further, as one of the monomer components constituting the surface layer of the insulating fine particles, it is preferable to use a monomer having a functional group having an electric charge.

Insulating fine particles according to the present invention are polymers containing a crosslinkable monomer component at least in their surface layer, but materials constituting parts other than the surface layer, for example, the inside of the insulating fine particles, whether inorganic or organic, can be used without particular limitation. . In the case of using an inorganic substance, metal particles such as gold, silver, copper, nickel, palladium, solder, etc., alloys, glass, ceramics, silica, oxides of metals or nonmetals (including hydrated compounds), metals containing aluminosilicates silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal acid salts, metal halides, and carbon. On the other hand, when using an organic material, for example, natural fiber, natural resin, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid ester, polyacrylonitrile, polyacetal, ionomer, thermoplastic resins such as polyester, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, and diallylphthalate resins. These may be used independently and may be used in combination of 2 or more type. Among these, those made of resin materials are preferable from the viewpoints of having a smaller specific gravity than metals, less sedimentation, and excellent dispersion stability.

It is preferable that it is a polymer of the polymeric compound which has an ethylenically unsaturated bond as said resin material which comprises the part other than the surface layer of an insulating fine particle. Examples of the polymerizable compound having an ethylenically unsaturated bond include styrenes, olefins, esters, α,β unsaturated carboxylic acids, amides, and nitriles. Examples of the styrenes include nuclear substituted styrene such as styrene, o, m, p-methylstyrene, dimethylstyrene, ethylstyrene, and chlorostyrene, and styrene derivatives such as α-methylstyrene, α-chlorostyrene, and β-chlorostyrene. can be heard As olefins, ethylene, propylene, etc. are mentioned. Examples of the esters include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate, and (meth)acrylic acids such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and phenyl (meth)acrylate. esters of Examples of α,β unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, and maleic acid. Salts of these α,β unsaturated carboxylic acids are also included in α,β unsaturated carboxylic acids. As amides, acrylamide, methacrylamide, etc. are mentioned. Examples of nitriles include acrylonitrile and the like. These may be further substituted, and examples of substituents include a phosphonium group, an amino group, a quaternary ammonium group, an amide group, a sulfonium group, a sulfonic acid group, a thiol group, a carboxyl group, a phosphoric acid group, a cyano group, an aldehyde group, an ester group, and a carbonyl group. can These monomers can be used singly or in combination of two or more. In particular, a polymer containing at least one non-crosslinkable monomer component selected from styrenes, esters, and nitriles is preferable in terms of a high polymerization rate and easy spherical shape. When the polymer constituting the resin material has a plurality of types of structural units, the presence of those structural units in the polymer may be random, alternating, or block. The polymer constituting the resin material may be crosslinked or non-crosslinked. In the present invention, from the viewpoint of facilitating obtaining spherical insulating fine particles, it is preferable that the resin material constituting the portion other than the surface layer, that is, the core portion, is composed of a polymer obtained by polymerizing a non-crosslinkable monomer component.

The average particle diameter (D) of the insulating fine particles is preferably 10 nm or more and 3,000 nm or less, more preferably 15 nm or more and 2,000 nm or less. When the average particle diameter of the insulating fine particles is within the above range, the obtained coated particles do not generate a short circuit in a direction different from that between the opposing electrodes, and conduction between the opposing electrodes is easily ensured. In the present invention, the average particle diameter of the insulating fine particles is a value measured by observation using a scanning electron microscope, and is specifically measured by the method described in Examples described later.

The particle size distribution of the insulating fine particles measured by the above method has a width. In general, the width of the particle size distribution of powder is represented by a coefficient of variation (Coefficient of Variation, hereinafter also referred to as "C.V.") expressed by the following formula (1).

C.V. (%) = (standard deviation/average particle diameter) x 100... (1)

This C.V. A large value indicates that there is a width in the particle size distribution, and on the other hand, C.V. A small value indicates that the particle size distribution is sharp. The coated particles of the present embodiment are C.V. is preferably 0.1% or more and 20% or less, more preferably 0.5% or more and 15% or less, and most preferably 1% or more and 10% or less. C.V. When is within this range, there is an advantage that the thickness of the coating layer made of the insulating fine particles can be made uniform.

The sphericity of the insulating fine particles is 0.90 or more. In the present invention, sphericity means a value obtained by dividing the minor axis of the insulating fine particles by the major axis. The sphericity may be measured using a scanning electron microscope at a measurement magnification such that the number of insulating fine particles contained in one field of view is approximately 50 to 100, and the arithmetic average value based on the number may be calculated. The sphericity is preferably 0.92 or more, more preferably 0.94 or more, still more preferably 0.95 or more. The upper limit of the sphericity is not particularly limited, but is usually about 0.99. When the sphericity is within this range, insulating fine particles are efficiently removed from between the conductive layer and the electrode during thermal compression bonding, and the conduction reliability can be improved.

Next, a preferred method for producing the coated particles of the present embodiment will be described.

This manufacturing method is a first step of polymerizing a non-crosslinkable monomer component to obtain an insulating fine particle precursor;

A second step of obtaining insulating fine particles by polymerizing a polymerizable compound containing a crosslinkable monomer component in the presence of an insulating fine particle precursor;

A third step of mixing the dispersion containing the insulating fine particles with the conductive particles and adhering the insulating fine particles to the surface of the conductive particles is provided.

(Step 1)

The insulating fine particle precursor according to the production method of the present invention is a polymer obtained by polymerizing non-crosslinkable monomer components. Examples of the non-crosslinkable monomer component include a polymeric compound having an ethylenically unsaturated bond, which is a resin material constituting a portion other than the surface layer of the insulating fine particles described above. In particular, the non-crosslinkable monomer component is styrene, o-, m-, or p-methylstyrene, dimethylstyrene, ethylstyrene, chlorostyrene, vinyl acetate, methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylic acid It is preferable that it is at least 1 sort(s) chosen from propyl and phenyl (meth)acrylate. In the case of using a plurality of non-crosslinkable monomer components, examples of the preferable compositional ratio of the polymerizable compound include giving the above-mentioned preferable structural units of the polymer constituting the insulating fine particle precursor and preferable ratios thereof.

In the first step, a polymerizable compound containing a monomer component having a functional group having an electric charge may be polymerized in addition to the crosslinkable monomer component. Examples of the monomer component having a functional group having a charge include a monomer component having a functional group having a charge constituting the insulating fine particles described above.

As the polymerization method, emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, suspension polymerization, etc. may be used. Any method may be used, but in the case of soap-free emulsion polymerization, monodisperse fine particles can be produced without using a surfactant. It is preferable in that it has an advantage. In the case of soap-free emulsion polymerization, a water-soluble initiator is used as the polymerization initiator. Polymerization is preferably carried out under an inert atmosphere such as nitrogen or argon.

The polymerization time is preferably 0.3 hour or more and 20 hours or less, particularly 0.5 hour or more and 12 hours or less, from the viewpoint of obtaining particles having a spherical shape and an even particle diameter of the insulating fine particle precursor.

As a result of the above, an insulating fine particle precursor is obtained.

(2nd process)

In the second step, in the presence of the insulating fine particle precursor obtained in the first step, a polymerizable compound containing a crosslinkable monomer component is polymerized to obtain insulating fine particles. Examples of the crosslinkable monomer component include the crosslinkable monomer component constituting the above-described insulating fine particles, in particular, divinylbenzene, allyl methacrylate, ethylene glycol di(meth)acrylate, and diethylene glycol di(meth)acrylate. )Acrylates, triethylene glycoldi(meth)acrylate, 1,4-butanedioldi(meth)acrylate, 1,9-nonanedioldi(meth)acrylate and 1,10-decanedioldi(meth)acrylate It is preferable that it is at least 1 sort(s) selected from rate. In the case of using a plurality of crosslinkable monomer components, examples of the preferable compositional ratio of the polymerizable compound include the above-mentioned preferable structural units of the polymer constituting the insulating fine particles and preferable ratios thereof.

In the second step, in addition to the crosslinkable monomer component, a polymerizable compound containing a monomer component having a functional group having an electric charge may be polymerized. Examples of the monomer component having a functional group having a charge include a monomer component having a functional group having a charge constituting the insulating fine particles described above.

As a polymerization method, the method similar to the 1st process is mentioned, Emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, suspension polymerization, etc. are mentioned. In particular, soap-free emulsion polymerization is preferable from the viewpoint of being able to produce monodisperse fine particles without using a surfactant. Polymerization is preferably carried out under an inert atmosphere such as nitrogen or argon.

The polymerization time is preferably 0.3 hour or more and 20 hours or less, particularly 0.5 hour or more and 12 hours or less, from the viewpoint of obtaining spherical insulating fine particles and particles having an even particle diameter.

As a result, insulating fine particles are obtained.

(The 3rd process)

Next, insulating fine particles and conductive particles are mixed, and the insulating fine particles are adhered to the surface of the conductive particles. It is preferable to mix insulating fine particles and conductive particles in a liquid medium. Examples of the liquid medium include water, organic solvents, and mixtures thereof, and water is preferable.

When the insulating fine particles and the conductive particles are mixed in a liquid medium, the dispersion of these particles and the liquid medium preferably contains an inorganic salt, an organic salt or an organic acid in view of the ease of obtaining coated particles having a coverage of a certain level or more. As inorganic salts, organic salts or organic acids, those that dissociate anions are preferably used, and these anions include Cl ^- , F ^- , Br ^- , I ^- , SO ₄ ^2- , CO ₃ ^2- , NO ₃ ^- , COO ^- , RCOO ^- (R is an organic group) and the like are preferable. Examples of inorganic salts include NaCl, KCl, LiCl, MgCl ₂ , BaCl ₂ , NaF, KF, LiF, MgF ₂ , BaF ₂ , NaBr, KBr, LiBr, MgBr ₂ , BaBr ₂ , NaI, KI, LiI, MgI ₂ , BaI ₂ , Na ₂ SO ₄ , K ₂ SO ₄ , Li ₂ SO ₄ , MgSO ₄ , Na ₂ CO ₃ , NaHCO ₃ , K ₂ CO ₃ , KHCO ₃ , Li ₂ CO ₃ , LiHCO ₃ , MgCO ₃ , NaNO ₃ , KNO ₃ , LiNO ₃ , Mg(NO ₃ ) ₂ , Ba(NO ₃ ) ₂ , and the like may be used. Moreover, as an organic salt, sodium succinate, Na oxalate, Na acetate, Na citric acid, Na malonic acid, Na tartaric acid, Na fumarate, Na maleic acid, etc. can be used. Examples of organic acids include amino acids such as glycine, succinic acid, oxalic acid, acetic acid, citric acid, tartaric acid, malonic acid, fumaric acid, and maleic acid.

Preferred concentrations of inorganic salts, organic salts, and organic acids vary depending on the coverage area occupied by the insulating fine particles in the surface area of the conductive particles, but in a dispersion containing the insulating fine particles and the conductive particles, for example, 5 mmol A concentration of at least /L and at most 100 mmol/L is preferable because it is easy to obtain coated particles having a desirable coverage and having a single layer of insulating fine particles. From this point of view, the concentration of the inorganic salt, organic salt and organic acid in the dispersion is more preferably 7 mmol/L or more and 90 mmol/L or less, and particularly preferably 10 mmol/L or more and 80 mmol/L or less.

In mixing the insulating fine particles and the conductive particles in the liquid medium, the dispersion containing the insulating fine particles and the conductive particles may be mixed, or the dispersion containing the conductive particles and the insulating fine particles may be mixed, or the insulating fine particles and the conductive particles may be mixed in the liquid medium. Particles may be introduced individually, or a dispersion medium containing insulating fine particles and a dispersion medium containing conductive particles may be mixed. In the dispersion containing conductive particles and insulating fine particles, the conductive particles are preferably contained in an amount of 100 ppm or more and 100,000 ppm or less, more preferably 500 ppm or more and 80,000 ppm or less, based on mass.

In the dispersion containing conductive particles and insulating fine particles, the insulating fine particles are preferably contained in an amount of 10 ppm or more and 50,000 ppm or less, more preferably 250 ppm or more and 30,000 ppm or less, based on mass.

The temperature of the dispersion containing the conductive particles and the insulating fine particles is generally preferably 20 ° C. or more and 100 ° C. or less, from the viewpoint of easiness to obtain coated particles of constant quality, and 40 ° C. or more and 90 ° C. or less are particularly preferred. Within this range, the insulating fine particles adhere to the conductive particles while maintaining their shape, and it is easy to obtain a desirable contact area between the insulating fine particles and the conductive particles.

In the dispersion liquid after mixing the conductive particles, the time required for adhesion of the insulating fine particles to the conductive particles is preferably 0.1 hour or more and 24 hours or less. During this time, it is preferable to stir the dispersion. Subsequently, the solid content of the dispersion is washed and dried as necessary to obtain coated particles having insulating fine particles adhered to the surface of the conductive particles.

The coated particles obtained as described above make use of the insulating properties between the coated particles and the connectivity between the opposite electrodes due to the advantages of the conductive particles and the insulating fine particles having no glass transition temperature, and are used as conductive adhesives, anisotropic conductive films, and anisotropic conductive adhesives. It is preferably used as a conductive material such as.

Example

Hereinafter, the present invention will be described by examples. However, the scope of the present invention is not limited to these examples. The properties in the examples were measured by the following methods.

(1) Average particle diameter

200 particles were arbitrarily extracted from a scanning electron microscope (SEM) photograph (magnification: 100,000 times) of the object to be measured, their particle diameters were measured, and the average value was taken as the average particle diameter. The definition of the average particle diameter is as described above.

(2) C.V. (coefficient of variation)

From the measurement of the said average particle diameter, it calculated|required by the following formula.

C.V. (%) = (standard deviation/average particle diameter) x 100

(3) glass transition temperature

The change in calorific value from a measurement temperature of 25°C to 200°C was measured in the above procedure under a nitrogen atmosphere at a heating rate of 5°C/min with a differential scanning calorimetry device (STAR SYSTEM, manufactured by METTLER TOLEDO).

(4) sphericity

From a scanning electron microscope (SEM) photograph (magnification: 100,000 times) of the object to be measured, 200 particles are randomly extracted, their minor and major axes are measured, and the value obtained by dividing the minor axis by the major axis per particle is obtained, and the average value is converted to sphericity. did

(Example 1)

[Manufacture of phosphonium-based insulating fine particles]

1200 mL of pure water was injected|thrown-in to the 2000 mL four-necked flask equipped with the stirring blade of 60 mm in length. Then, 288 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 63.6 mmol of n-butylacrylate (manufactured by Kanto Chemical Co., Ltd.), and 2,2'-azobis (2-methylpropion) as a polymerization initiator 5.0 mmol of amidine) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries, Ltd.) was added. After nitrogen was ventilated for 15 minutes to blow out dissolved oxygen, the temperature was raised to 65°C and maintained for 6 hours to advance the polymerization reaction.

Thereafter, 108 mmol of divinylbenzene monomer (manufactured by Shin-Nittetsu Sakekin Co., Ltd.) and 2.16 mmol of 4-(vinylbenzyl)triethylphosphonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.) were added to the reaction system, and 65 The reaction was terminated after being maintained at °C for 10 hours.

The dispersion of fine particles after polymerization was sieved through a SUS sieve with a mesh of 150 μm to remove aggregates. The dispersion liquid from which the aggregates were removed was centrifuged using a centrifuge (CR-21N, manufactured by Hitachi Kogyo Co., Ltd.) at 20,000 rpm for 20 minutes to settle fine particles, and the supernatant was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles. Each characteristic of the obtained fine particles is shown in Table 1. A SEM photograph of the obtained insulating fine particles is shown in FIG. 1 . Moreover, the result of measuring the glass transition temperature is shown in FIG.

[Production of Conductive Particles Coated with Insulating Fine Particles]

Ni-plated particles (manufactured by Nippon Chemical Industries, Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120°C. 100 mL of pure water was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. 10 mL of an aqueous solution of 1% by mass of benzotriazole was introduced into this dispersion and stirred for 5 minutes to perform surface treatment. After that, it was filtered through a membrane filter having a mesh of 2.0 μm, and Ni-plated particles having a layer of benzotriazole on the surface were recovered. After washing the collected Ni-plated particles with pure water, 100 mL of pure water was added to obtain a dispersion of Ni-plated particles having a layer of benzotriazole on the surface. To this dispersion, the insulating fine particles obtained above and Na ₂ SO ₄ were charged, and this was stirred at 40°C for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol/L. After removing the supernatant liquid, it was washed with pure water and vacuum dried at 50°C to obtain conductive particles coated with insulating fine particles. A SEM photograph of the obtained coated particles is shown in FIG. 3 .

(Example 2)

[Preparation of ammonium-based insulating fine particles]

1200 mL of pure water was injected|thrown-in to the 2000 mL four-necked flask equipped with the stirring blade of 60 mm in length. Then, 288 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 63.6 mmol of n-butylacrylate (manufactured by Kanto Chemical Co., Ltd.), and 2,2'-azobis (2-methylpropion) as a polymerization initiator 5.0 mmol of amidine) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries, Ltd.) was added. After nitrogen was ventilated for 15 minutes to blow out dissolved oxygen, the temperature was raised to 65°C and maintained for 6 hours to advance the polymerization reaction.

Thereafter, 108 mmol of divinylbenzene monomer (manufactured by Shin-Nittetsu Sakekin Co., Ltd.) and 2.0 mmol of 4-(vinylbenzyl)triethylammonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.) were added to the reaction system, and the temperature was 65°C. , and maintained for 10 hours, and the reaction was terminated.

The dispersion of fine particles after polymerization was sieved through a SUS sieve with a mesh of 150 μm to remove aggregates. The dispersion liquid from which the aggregates were removed was centrifuged using a centrifuge (CR-21N, manufactured by Hitachi Kogyo Co., Ltd.) at 20,000 rpm for 20 minutes to settle fine particles, and the supernatant was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles. Each characteristic of the obtained fine particles is shown in Table 1. A SEM photograph of the obtained insulating fine particles is shown in FIG. 4 . Moreover, the result of measuring the glass transition temperature is shown in FIG.

[Production of Conductive Particles Coated with Insulating Fine Particles]

Conductive particles coated with insulating fine particles were obtained in the same manner as in Example 1.

(Comparative Example 1)

[Manufacture of phosphonium-based insulating fine particles]

1200 mL of pure water was injected|thrown-in to the 2000 mL four-necked flask equipped with the stirring blade of 60 mm in length. Then, 288 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 63.6 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), and 108 mmol of divinylbenzene monomer (manufactured by Nippon Steel & Sumitomo Metal Co., Ltd.) , 1.44 mmol of 4-(vinylbenzyl)triethylphosphonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.), and 2,2'-azobis(2-methylpropionamidine)dihydrochloride (Wako pure medicine) as a polymerization initiator 5.0 mmol of V-50 manufactured by Kogyo Co., Ltd. was added. After nitrogen was ventilated for 15 minutes to blow out dissolved oxygen, the temperature was raised to 65°C and maintained for 8 hours to advance the polymerization reaction. The dispersion of fine particles after polymerization was sieved through a SUS sieve with a mesh of 150 μm to remove aggregates. The dispersion liquid from which the aggregates were removed was centrifuged using a centrifuge (CR-21N, manufactured by Hitachi Kogyo Co., Ltd.) at 20,000 rpm for 20 minutes to settle fine particles, and the supernatant was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles. Each characteristic of the obtained microparticles|fine-particles is shown in Table 1. A SEM photograph of the obtained insulating fine particles is shown in FIG. 6 . Moreover, the result of measuring the glass transition temperature is shown in FIG.

[Production of Conductive Particles Coated with Insulating Fine Particles]

Ni-plated particles (manufactured by Nippon Chemical Industries, Ltd.) having an average particle diameter of 3 μm and having a nickel film with a thickness of 0.125 μm on the surface of spherical resin particles were prepared. The resin particles were made of a crosslinkable acrylic resin and had a glass transition temperature of 120°C. 100 mL of pure water was added to 5.0 g of the above Ni-plated particles and stirred to obtain a dispersion of Ni-plated particles. 10 mL of an aqueous solution of 1% by mass of benzotriazole was introduced into this dispersion and stirred for 5 minutes to perform surface treatment. Thereafter, it was filtered through a membrane filter having a mesh of 2.0 μm to recover Ni-plated particles having a layer of benzotriazole on the surface. After washing the collected Ni-plated particles with pure water, 100 mL of pure water was added to obtain a dispersion of Ni-plated particles having a layer of benzotriazole on the surface. To this dispersion, the insulating fine particles obtained above and Na ₂ SO ₄ were charged, and this was stirred at 40°C for 30 minutes. After adding the insulating fine particles and Na ₂ SO ₄ , the solid concentration of the insulating fine particles in the dispersion was 10,000 ppm on a mass basis, and the concentration of Na ₂ SO ₄ was 5 mmol/L. After removing the supernatant liquid, it was washed with pure water and vacuum dried at 50°C to obtain conductive particles coated with insulating fine particles.

(Comparative Example 2)

[Preparation of ammonium-based insulating fine particles]

1200 mL of pure water was injected|thrown-in to the 2000 mL four-necked flask equipped with the stirring blade of 60 mm in length. Then, 288 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 63.6 mmol of n-butyl acrylate (manufactured by Kanto Chemical Co., Ltd.), and 108 mmol of divinylbenzene monomer (manufactured by Nippon Steel & Sumitomo Metal Co., Ltd.) 2.0 mmol of 4-(vinylbenzyl)triethylammonium chloride (manufactured by Nippon Chemical Industry Co., Ltd.), and 2,2'-azobis(2-methylpropionamidine)dihydrochloride (Wako Pure Chemical Industries, Ltd.) as a polymerization initiator Preparation, V-50) 5.0 mmol was added. After nitrogen was ventilated for 15 minutes to blow out dissolved oxygen, the temperature was raised to 65°C and maintained for 8 hours to advance the polymerization reaction. The dispersion of fine particles after polymerization was sieved through a SUS sieve with a mesh of 150 μm to remove aggregates. The dispersion liquid from which the aggregates were removed was centrifuged using a centrifuge (CR-21N, manufactured by Hitachi Kogyo Co., Ltd.) at 20,000 rpm for 20 minutes to settle fine particles, and the supernatant was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles. Each characteristic of the obtained fine particles is shown in Table 1. A SEM photograph of the obtained insulating fine particles is shown in FIG. 8 . Moreover, the result of measuring the glass transition temperature is shown in FIG.

[Production of Conductive Particles Coated with Insulating Fine Particles]

Conductive particles coated with insulating fine particles were obtained in the same manner as in Comparative Example 1.

(Comparative Example 3)

[Manufacture of phosphonium-based insulating fine particles]

1200 mL of pure water was injected|thrown-in to the 2000 mL four-necked flask equipped with the stirring blade of 60 mm in length. Then, 360 mmol of styrene monomer (manufactured by Kanto Chemical Co., Ltd.), 63.6 mmol of n-butylacrylate (manufactured by Kanto Chemical Co., Ltd.), 4-(vinylbenzyl)triethylphosphonium chloride (Nippon Chemical Industry ( Co., Ltd.) 1.44 mmol, and 5.0 mmol of 2,2'-azobis (2-methylpropionamidine) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator were added. After nitrogen was ventilated for 15 minutes to blow out dissolved oxygen, the temperature was raised to 65°C and maintained for 8 hours to advance the polymerization reaction. The dispersion of fine particles after polymerization was sieved through a SUS sieve with a mesh of 150 μm to remove aggregates. The dispersion liquid from which the aggregates were removed was centrifuged using a centrifuge (CR-21N, manufactured by Hitachi Kogyo Co., Ltd.) at 20,000 rpm for 20 minutes to settle fine particles, and the supernatant was removed. Pure water was added to the obtained solid and washed to obtain spherical fine particles. Each characteristic of the obtained fine particles is shown in Table 1. A SEM photograph of the obtained insulating fine particles is shown in FIG. 10 . Moreover, the result of measuring the glass transition temperature is shown in FIG.

[Production of Conductive Particles Coated with Insulating Fine Particles]

Conductive particles coated with insulating fine particles were obtained in the same manner as in Comparative Example 1.

(Evaluation of conductivity and insulation)

<Evaluation of Continuity>

An insulating paste obtained by mixing 100 parts by mass of an epoxy resin, 150 parts by mass of a curing agent, and 70 parts by mass of toluene, and 15 parts by mass of coated particles obtained in Examples and Comparative Examples were mixed. This paste was applied on a silicone-treated polyester film using a bar coater, and then the paste was dried to form a thin film on the film. The obtained thin film formation film was placed between a glass substrate on which aluminum was vapor-deposited on the entire surface and a polyimide film substrate on which a copper pattern was formed at a pitch of 50 μm, and electrical connection was performed. Conductivity of the coated particles was evaluated at room temperature (25°C/50% RH) by measuring the conduction resistance between the substrates. The lower the resistance value, the higher the conductivity of the coated particles can be evaluated. Conductivity evaluation of the coated particles was evaluated as "very good" (indicated by the symbol "○" in Table 2) when the resistance value was less than 2 Ω, and "good" when the resistance value was 2 Ω or more and less than 5 Ω (in Table 2, Represented by the symbol "Δ"), and those having a resistance value of 5 Ω or more were designated as "defective" (indicated by the symbol "x" in Table 2). A result is shown in Table 2.

<Evaluation of insulation>

Using a micro compression tester MCTM-500 (manufactured by Shimadzu Corporation), 20 coated particles were compressed under the condition of a load speed of 0.5 mN/sec, and the coated particles of Examples and Comparative Examples were compressed, and resistance values were detected. The insulating properties of the coated particles were evaluated by measuring the compression displacement up to . The larger the compression displacement until the resistance value is detected, the higher the insulating property of the coated particles can be evaluated. In the insulation evaluation of the covered particles, those in which the arithmetic average value of the compression displacement until the resistance value was detected were 10% or more as "very good" (indicated by the symbol "○" in Table 2), and the arithmetic average value of the compression displacement Those having more than 3% and less than 10% were regarded as “good” (indicated by the symbol “Δ” in Table 2), and those having an arithmetic mean of compression displacement of 3% or less were regarded as “poor” (indicated by the symbol “x” in Table 2). indicated.). A result is shown in Table 2.

As shown in Table 2, it can be seen that the coated particles of Examples are superior in insulating property while maintaining conductivity as compared to the coated particles of Comparative Examples.

Since the coated particles of the present invention are coated particles coated with insulating fine particles having a spherical shape and no glass transition temperature, they can have high conduction reliability and insulation reliability.

Claims (13)

A coated particle having conductive particles having a metal film formed on the surface of a core material and insulating fine particles covering the conductive particles,
The coated particle wherein the insulating fine particle is an insulating fine particle having no glass transition temperature and a sphericity of 0.90 or more. According to claim 1,
A coated particle wherein the surface layer of the insulating fine particles is a polymer containing a crosslinkable monomer component. According to claim 2,
The crosslinkable monomer component is divinylbenzene, allyl methacrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol A coated particle comprising at least one selected from di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate and 1,10-decanedioldi(meth)acrylate. According to any one of claims 1 to 3,
The coated particle wherein the surface layer of the insulating fine particles is a polymer containing a monomer component having a functional group having an electric charge. According to claim 4,
The coated particle wherein the functional group is an ammonium group or a phosphonium group. According to any one of claims 1 to 5,
The coated particle wherein the coefficient of variation (CV) of the particle diameter of the insulating fine particles is 0.1% or more and 20% or less. According to any one of claims 1 to 6,
The coated particle in which the said metal film is a film comprised from at least 1 sort(s) chosen from nickel, gold, a nickel alloy, and a gold alloy. According to any one of claims 1 to 7,
The coated particle in which the said electroconductive particle has a some processus|protrusion on the surface. A conductive material comprising the coated particle according to any one of claims 1 to 8 and an insulating resin. A method for producing coated particles having conductive particles having a metal film formed on the surface of a core material and insulating fine particles covering the conductive particles, the method comprising the steps of:
A first step of polymerizing a non-crosslinkable monomer component to obtain an insulating fine particle precursor;
A second step of obtaining insulating fine particles by polymerizing a polymerizable compound containing a crosslinkable monomer component in the presence of an insulating fine particle precursor;
A method for producing coated particles comprising a third step of mixing a dispersion containing insulating fine particles with conductive particles and adhering the insulating fine particles to surfaces of the conductive particles. According to claim 10,
The non-crosslinkable monomer component is styrene, o-, m- or p-methylstyrene, dimethylstyrene, ethylstyrene, chlorostyrene, vinyl acetate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and A method for producing coated particles, which is at least one selected from phenyl (meth)acrylate. According to claim 10 or 11,
The crosslinkable monomer component is divinylbenzene, allyl methacrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol A method for producing coated particles, which is at least one selected from di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, and 1,10-decanedioldi(meth)acrylate. According to any one of claims 10 to 12,
A method for producing coated particles comprising obtaining an insulating fine particle precursor in the first step for 0.3 hours or more and 20 hours or less, and then performing the second step.

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