JP2021097040A - Coated particle and conductive material containing the same - Google Patents

Abstract

To provide coated particles having improved adhesion between insulative particles and conductive particles.SOLUTION: There are provided coated particles where the surface of conductive particles having a metal film formed on the surface of core material particles is coated with insulative particles. In the insulative particles, the surface of silica particles is surface-treated with a silane coupling agent having a mercapto group. The core material particles are preferably a composite material of a resin or an organic matter and an inorganic matter, and the metal film is preferably at least one film selected from nickel, palladium, gold, a nickel alloy, a palladium alloy and a metal alloy.SELECTED DRAWING: None

Description

The present invention relates to coated particles in which conductive particles are coated with an insulating layer and a conductive material containing the same.

The conductive particles in which a metal such as nickel or gold is formed on the surface of the resin particles are used as a conductive material such as a conductive adhesive, an anisotropic conductive film, and an anisotropic conductive adhesive.
In recent years, with the further miniaturization of electronic devices, the circuit width and pitch of electronic circuits have become smaller and smaller. Along with this, as the conductive particles used in the above-mentioned conductive adhesive, anisotropic conductive film, anisotropic conductive adhesive and the like, those having a small particle size are required. When conductive particles having such a small particle size are used, the blending amount of the conductive particles must be increased in order to improve the connectivity. However, when the blending amount of the 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 the counter electrodes, and it is difficult to obtain insulation in that direction. ing. In order to solve this problem, insulating coated conductive particles are used in which the surface of the conductive particles is coated with an insulating substance to prevent the metal layers of the conductive particles from coming into contact with each other.

For example, in Patent Document 1, particles having a surface made of a conductive metal are used as nuclei, and the surface thereof is partially modified with organic particles made of an organic compound containing a functional group having a binding property to the metal. The coated particles are described, and it is described that the organic compound has a positive or negative charge.
Further, Patent Document 2 describes coating particles similar to those in Patent Document 1. In the same document, the coating particles form a single-layer coating layer by chemically bonding the insulating fine particles to particles having a surface made of a conductive metal via a functional group having a binding property to the metal. It is stated that it is. According to the same document, the coated particles having such a configuration are obtained by thermocompression bonding the coated particles between the electrodes to melt, deform or peel the insulating fine particles, thereby exposing the metal surface of the metal-coated particles between the electrodes. It is stated that continuity is possible and connectivity is obtained. Patent Documents 1 and 2 exemplify ammonium groups and sulfonium groups as the functional groups.

Further, in Patent Document 3, the surface of the metal-coated particles is described by applying insulating resin fine particles having a heteroelement or functional group having a binding force to the metal on the surface to the surface of the metal-coated particles and then heating the particles. It is described that anisotropic insulating conductive particles having an insulating layer having no particle shape can be obtained.

International Publication No. 2002/035555 Pamphlet International Publication No. 2003/025955 Pamphlet International Publication No. 2005/109448 Pamphlet

In the conductive particles coated with the insulating particles, it has been an issue to improve the adhesion between the insulating particles and the conductive particles. Since the adhesion between the insulating particles and the conductive particles is important for conducting conduction between the counter electrodes (hereinafter, also simply referred to as connection reliability) while obtaining insulation in a direction different from that of the counter electrode. Further, there is a demand for the development of coated particles having excellent adhesion between insulating particles and conductive particles.

Therefore, an object of the present invention is to provide coated particles having improved adhesion between insulating particles and conductive particles, and a conductive material containing the same.

As a result of intensive studies in view of the above circumstances, the present inventors have made that the insulating particles are silica in the coated particles in which the surface of the conductive particles in which the metal film is formed on the surface of the core material is coated with the insulating particles. The present invention is completed by finding that when the surface of the particles is surface-treated with a silane coupling agent having a mercapto group, the coated particles have excellent adhesion between the insulating particles and the conductive particles. Arrived at.

That is, the first invention to be provided by the present invention is a coating particle in which the surface of a conductive particle in which a metal film is formed on the surface of a core material particle is coated with an insulating particle, and the insulating particle. However, the coated particles are characterized in that the surface of the silica particles is surface-treated with a silane coupling agent having a mercapto group.

The second invention to be provided by the present invention is a conductive material containing the coated particles of the first invention and an insulating resin.

The coated particles of the present invention have excellent adhesion to conductive particles due to the silane coupling agent having a mercapto group existing on the surface of the silica particles used as the insulating particles.
Such coated particles of the present invention can have high connection reliability.

Hereinafter, the present invention will be described based on preferred embodiments.
The coated particles of the present embodiment are coated particles in which the surface of conductive particles having a metal film formed on the surface of core material particles is coated with insulating particles, and the insulating particles cover the surface of silica particles. It is characterized in that it is surface-treated with a silane coupling agent having a mercapto group.

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

The core material particles of the conductive particles may be inorganic or organic without particular limitation. Examples of the inorganic core material particles include metal particles such as gold, silver, copper, nickel, palladium, and solder, alloys, glass, ceramics, silica, metal or non-metal oxides (including hydrous substances), and aluminosilicates. Examples thereof include metal silicates, metal carbides, metal nitrides, metal carbonates, metal sulfates, metal phosphates, metal sulfides, metal acid salts, metal halides and carbons. On the other hand, examples of the organic core particles include thermoplastics such as natural fibers, natural resins, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polybutene, polyamide, polyacrylic acid ester, polyacrylic nitrile, polyacetal, ionomer, and polyester. Examples thereof include resins, alkyd resins, phenol resins, urea resins, benzoguanamine resins, melamine resins, xylene resins, silicone resins, epoxy resins, diallyl phthalate resins and the like. These may be used alone or in combination of two or more. Further, a composite material of an organic substance and an inorganic substance can also be used. Examples include styrene silica composite resin, acrylic silica composite resin, crosslinked alkoxyryl polymer-acrylic resin, polyorganosiloxane-silica and the like. Among these, a resin or a composite material of an organic substance and an inorganic substance is a composite material of a resin or an organic substance and an inorganic substance in that the specific gravity is smaller than that of the core material particles made of metal, it is difficult to settle, the dispersion stability is excellent, and the electrical connection is easily maintained due to the elasticity of the resin. Core material particles composed of are preferable. Further, the composite material of the organic substance and the inorganic substance may have a core-shell structure.

When an organic substance is used as the core material particles, it is easy to maintain the shape of the core material particles in the anisotropic conductive connection process and that the glass transition temperature does not have a glass transition temperature or the glass transition temperature exceeds 100 ° C. It is preferable because the shape of the core material particles can be easily maintained in the step of forming the film. Further, when the core material particles have a glass transition temperature, the glass transition temperature is 200 ° C. or less, which means that the conductive particles tend to soften in the anisotropic conductive connection and the contact area becomes large, so that conduction can be easily obtained. Is preferable. From this viewpoint, when the core material particles have a glass transition temperature, the glass transition temperature is more preferably more than 100 ° C. and 180 ° C. or lower, and particularly preferably more than 100 ° C. and 160 ° C. or lower.

When an organic substance is used as the core material particles, when the organic substance is a highly crosslinked resin, the glass transition temperature is hardly observed even if the measurement is attempted to 200 ° C. by the method described in the following Examples. In the present specification, such particles are also referred to as particles having no glass transition point, and in the present invention, such core material particles may be used. As a specific example of the core material having no glass transition temperature as described above, it is possible to obtain by copolymerizing the monomer constituting the organic substance exemplified above in combination with a crosslinkable monomer. it can. Crosslinkable monomers include tetramethylene di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide di (meth) acrylate, and tetraethylene oxide. (Meta) acrylate, 1,6-hexanedi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, trimeterol propantri (meth) acrylate, tetramethylol methanedi (meth) Meta) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, tetramethylolpropanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol di (meth) acrylate, glycerol tridi (meth) Polyfunctional (meth) acrylates such as meta) acrylates, polyfunctional vinyl monomers such as divinylbenzene and divinyltoluene, vinyltrimethoxysilane, trimethoxysilylstyrene, γ- (meth) acryloxipropyltrimethoxysilane, etc. Examples thereof include silane-containing monomers, triallyl isocyanurate, diallyl phthalate, diallyl acrylamide, diallyl ether and the like. Especially in the field of COG (Chip on Glass), core material particles made of such a hard organic material are often used.

The shape of the core material particles is not particularly limited. Generally, the core material particles are spherical. However, the core material particles may have a shape other than a spherical shape, for example, a fibrous shape, a hollow shape, a plate shape, or a needle shape, and may have a large number of protrusions on the surface thereof or an irregular shape. In the present invention, spherical core material particles are preferable in terms of excellent filling property and easy coating of metal.

There is a range of particle size distributions measured by the method described above for powders consisting of core particles. Generally, the width of the particle size distribution of powder is represented by the coefficient of variation represented by the following formula (1).
Coefficient of variation (%) = (standard deviation / average particle size) x 100 (1)
A large coefficient of variation indicates a wide range of distribution, while a small coefficient of variation indicates a sharp particle size distribution. In the present invention, it is preferable to use the core material particles having a coefficient of variation of 30% or less, particularly 20% or less, particularly 10% or less. The reason for this is that when the conductive particles of the present invention are used as the conductive particles in the anisotropic conductive film, there is an advantage that the effective contribution ratio for connection is high.

The other physical properties of the core material particles are not particularly limited, but when the core material particles are resin particles, the value of K defined by the following formula (2) is 100 N / at 20 ° C. It is preferably in the range of mm ^{2 to} 100,000 N / mm ² and the recovery rate after 10% compression deformation is in the range of 1% to 100% at 20 ° C. This is because by satisfying these physical property values, the electrodes can be sufficiently brought into contact with each other without damaging the electrodes when they are crimped to each other.
K value (N / mm ² ) = (3 / √2) x F x S ^-3/2 x R- ^{1 / 2} ... (2)
[Here, F and S represented by the calculation formula (2) are the load values (N) at 10% compression deformation of the microspheres as measured by the microcompression tester MCTM-500 manufactured by Shimadzu Corporation), respectively. Compressive displacement (mm), R is the radius (mm) of the microsphere]

The shape of the conductive particles depends on the shape of the core material particles, but is not particularly limited. For example, it may be fibrous, hollow, plate-shaped or needle-shaped, but spherical ones are preferable in terms of excellent filling property and connectivity.

Further, the surface of the conductive particles may be smooth. Alternatively, the conductive particles may have a plurality of protrusions protruding from the surface thereof. It is preferable that the protrusions are a continuum made of the same material as the metal film because the conductivity is further improved. More specifically, the metal film has a flat portion and a plurality of protrusions protruding from the flat portion and forming a continuum from the flat portion, and the flat portion and the protrusion are the same. It is preferably composed of the above materials. A "continuum" is a portion in which a protrusion and a flat portion of a metal film are formed by a single process, and a portion such as a seam that impairs the sense of unity between the flat portion and the protrusion of the metal film is formed. It means that it does not exist. However, with respect to the protrusions, the protrusions are composed of a particle connecting body in which a plurality of particles made of a material constituting the metal film are connected in a row, and it is permissible to observe grain boundaries between the particles. Will be done. Therefore, for example, a core particle for forming a protrusion, for example, a non-metal inorganic substance such as a metal, a metal oxide, or graphite, a conductive polymer, or the like is attached to the surface of the core material particle, and the protrusion is formed by using the core particle as a starting point of growth. Is not included in the continuum referred to in the present invention because the flat portion and the protrusion are not formed by a single step. However, it should be noted that the conductive particles having protrusions formed by adhering such core particles to the core material particles and using the core particles as a starting point of growth are also within the scope of the present invention.

When the conductive particles have the protrusions having the above-mentioned structure, the protrusions can penetrate the oxide film formed on the surface of the electrode when the electrode is made conductive, and the connection resistance can be reduced.

It is preferable that the height H of the protrusion is 20 nm or more on average, particularly 50 nm or more. The number of protrusions depends on the particle size of the conductive particles, but is preferably 1 to 20000, particularly 5 to 5000, per particle from the viewpoint of further improving the conductivity of the conductive particles. .. The aspect ratio of the protrusions is preferably 0.5 or more, more preferably 1 or more. A large aspect ratio of the protrusions is advantageous because it can easily break through the oxide film described above.
Further, when the anisotropic conductive film is formed by using the conductive particles, it is considered that if the aspect ratio of the protrusions is large, the resin exclusion property is high and the conductivity is high. The aspect ratio is a value defined by the ratio of the height H of the protrusion to the length D of the base of the protrusion, that is, H / D.

As described above, the aspect ratio of the protrusions is such that the length D of the base of the protrusions of the conductive particles itself is preferably 5 to 500 nm, particularly preferably 10 to 400 nm, and the height H of the protrusions is 5 to 500 nm. In particular, it is preferably 10 to 400 nm.

The metal film in the conductive particles has conductivity, and examples of the constituent metals include gold, platinum, silver, copper, iron, zinc, nickel, tin, lead, antimony, bismuth, cobalt, and indium. Examples thereof include metals such as titanium, antimony, bismuth, germanium, aluminum, chromium, palladium, tungsten and molybdenum, alloys thereof, and metal compounds such as ITO and solder. Of these, gold, silver, copper, nickel, palladium or solder are preferable because they have low resistance, and in particular, nickel, palladium, gold, nickel alloys, palladium alloys or gold alloys are preferable because they have high bondability with insulating particles. Used. The metal in the conductive particles may be used alone or in combination of two or more. The nickel alloy also contains nickel-phosphorus, nickel-boron, and nickel-boron-phosphorus, and the palladium alloy also contains palladium-phosphorus and palladium-boron.

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 consisting of multiple layers, especially when a metal film is formed by the electroless plating method, the base layer is nickel or a nickel alloy, and the outermost layer is nickel, palladium, gold, a nickel alloy, or a palladium alloy. Alternatively, a gold alloy is preferable from the viewpoint of reducing the connection resistance.

Further, the thickness of the metal film on the surface of the core material particles is preferably 0.001 μm to 2 μm, particularly preferably 0.005 to 1 μm.

As a method for forming a metal film on the surface of the core material particles, a dry method using a vapor deposition method, a sputtering method, a mechanochemical method, a hybridization method, etc., an electrolytic plating method, a wet method using an electrolytic plating method, etc. are used. Can be mentioned. Further, these methods may be combined to form a metal film on the surface of the core material particles, but the conductive particles having the metal film formed on the surface of the core material particles by electroless plating make the particle surface uniform and dense. It is preferable in that it can be coated with.

The average particle size of the conductive particles is preferably 0.1 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less. When the average particle size of the conductive particles is within the above range, it is easy to ensure continuity between the counter electrodes without causing the obtained coated particles to cause a short circuit in a direction different from that between the counter electrodes. In the present invention, the average particle size of the conductive particles is an average value of the particle size measured using a scanning electron microscope (SEM). When the conductive particles are spherical in the scanning electron microscope image, the particle diameter measured by using SEM is the diameter of the circular conductive particle image. When the insulating particles are not spherical, the particle size measured by SEM refers to the largest length (maximum length) of the line segments traversing the image of the conductive particles.

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

Further, as the conductive particles, those having a small amount of impurity ions such as alkali metal ions, halogen ions and organic acid ions to be eluted are preferable from the viewpoint of suppressing corrosion of the electrodes and the like.

(Insulating particles)
The insulating particles used in the present invention have the surface of the silica particles surface-treated with a silane coupling agent having a mercapto group.

Examples of the silica particles that can be used include those produced by growing particles from sodium silicate or an active silicic acid solution, those produced using an organic silicon compound as a raw material, vapor phase silica, and sedimentation property. Silica or the like can be used.

The preferred physical properties of the silica particles are such that the average particle size determined by the dynamic light scattering method is 5 to 500 nm, preferably 10 to 300 nm. When the average particle size of the silica particles is in the above range, the insulating particles are easily adsorbed in a state of being uniformly dispersed on the particle surface of the conductive particles.

The silane coupling agent having a mercapto group for surface-treating the silica particles is a silica compound having a mercapto group and a hydrolyzable group, and is preferably represented by the following general formula (1).
R ¹ Si (OR ² ) ₃ (1)
(In the formula, R ¹ is a hydrocarbon group having 1 to 8 carbon atoms having 1 to 3 mercapto groups, an alicyclic hydrocarbon group having 1 to 3 mercapto groups, and 1 to 3 mercapto groups. Indicates an aromatic hydrocarbon group having 6 to 8 carbon atoms. R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 8 carbon atoms, or carbon. an aromatic hydrocarbon group having 6 to 8. Incidentally, R ^2, each may be also different groups in the same group.)

Specific examples of the compound include 3-mercaptopropyltrimethoxysilane, 2-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and the like.

The coating amount of the silane coupling agent having a mercapto group is 0.1 to 10% by mass, preferably 1 to 5% by mass, which is preferable from the viewpoint that the surface of the silica particles can be uniformly coated.

Further, the coating of the silica particles of the silane coupling agent having a mercapto group is 0.8 × 10 ^{-24 to} 6.6 × 10 ^-24 mol, preferably 3.3 × 10 ^{per 1 nm 2 of the specific surface area of the silica particles.} It is preferably ^-24 × 6.6 × 10 ^{-24 mol.}

The method of surface-treating the silica particles with a silane coupling agent having a mercapto group can be carried out by a wet method or a dry method.

When the surface treatment of silica particles with a mercapto group-containing silane coupling agent is performed by a wet method, the surface treatment methods include 1) the silica particles in a solvent containing the mercapto group-containing silane coupling agent at a desired concentration. A method of immersing and heating if necessary to promote the reaction between the silica particles and the silane coupling agent having a mercapto group, and then spray-drying with the solvent, or solid-liquid separation and then drying. 2) Silica particles A silane coupling agent having a mercapto group is added to the dispersion liquid containing the solvent and the solvent, and the mixture is heated to 50 to 100 ° C. to carry out the reaction, and then spray-dried together with the solvent, or solid-liquid separation and then drying. The method of doing this can be mentioned.
As the solvent that can be used in the wet method, alcohols such as methanol, ethanol and propanol, or a mixed solvent of these alcohols and water can be used. As the silica particles, a commercially available silica sol can be used. In the case of an aqueous silica sol, alcohol is added to prepare a mixed solution of alcohol and water. For example, in 2) above, this mixed solution has a mercapto group. A silane coupling agent can be added and used as a dispersion.

When the surface treatment of silica particles with a silane coupling agent having a mercapto group is performed by a dry method, the surface treatment method is to use a silane coupling agent having a mercapto group and silica particles in a henschel mixer, an air flow crusher, or the like. Examples include a method of mixing by a dry method using mechanical means, or a method of diluting a silane coupling agent having a mercapto group with a solvent, mixing the diluent and silica particles, and heating and drying the obtained mixture. Be done.

In the present invention, from the viewpoint that monodisperse insulating particles can be easily obtained and those having a high coverage of coated particles can be easily obtained, the insulating particles obtained by the method 2) of the wet method. Is preferably used.

(Coating particles)
As a method of coating the insulating particles on the particle surface of the conductive particles, a wet method or a dry method can be used.

As a dry method, it is prepared by a mechanical means in which a strong shearing force acts. As the equipment used in the dry method, equipment such as a high speed mixer, a super mixer, a turbosphere mixer, an Erich mixer, a Henschel mixer, a hybridization system, a Nauter mixer, a ribbon blender, a jet mill and a cosmomizer is used. be able to.

The wet method is a method in which the insulating particles and the conductive particles are brought into contact with each other under stirring through a solvent to adhere the insulating particles to the surface of the conductive particles. Examples of the solvent that can be used include water, acetone, methanol, ethanol, and a mixed solvent thereof. The temperature at which the insulating particles and the conductive particles are brought into contact with each other is not particularly limited, but is 5 to 100 ° C., preferably 10 to 50 ° C., and is sufficient even near room temperature (25 ° C.). The coated particles of the present invention can be obtained by recovering the solid content from the solvent by a conventional method, washing and drying if necessary.

Further, a compound having a functional group (A) having reactivity with a metal film in conductive particles and a functional group (B) having reactivity with a mercapto group in insulating particles in the same molecule (hereinafter, "" The coated particles of the present invention may be obtained by a method of performing a first step of reacting a "reactive compound") with a metal film of conductive particles and then a second step of reacting with insulating particles.
Examples of the functional group (A) include a silane group, a silanol group, a carboxylki group, an amino group, an ammonium group, a nitro group, a hydroxyl group, a carbonyl group, a thiol group, a sulfonic acid group, a sulfonium group, a borate group and an oxazoline. Examples include a group, a pyrrolidone group, a phosphoric acid group, a nitrile group and the like.
Examples of the functional group (B) include an epoxy group, an amino group, a halide group, a hydroxyl group, a carboxylic acid halide group, a carboxylic acid anhydride group, a group having a carbon-carbon double bond, a cyclic ether group, and a cyclic thioether group. Examples thereof include an isocyanato group and an isothiocyanato group.

The first step can be performed by a known method, and examples thereof include the methods described in WO2003 / 025955 pamphlet, Japanese Patent Application Laid-Open No. 2001-342377, and Japanese Patent Application Laid-Open No. 2003-26813.

The second step can be performed wet or dry.

As a dry method, it is prepared by a mechanical means in which a strong shearing force acts. As the equipment used in the dry method, equipment such as a high speed mixer, a super mixer, a turbosphere mixer, an Erich mixer, a Henschel mixer, a hybridization system, a Nauter mixer, a ribbon blender, a jet mill and a cosmomizer is used. be able to.

In the wet method, the insulating particles and the conductive particles coated with the reactive compound are brought into contact with each other under stirring through a solvent, and the surface of the conductive particles coated with the reactive compound is insulated. This is a method of adhering particles. Examples of the solvent that can be used include water, acetone, methanol, ethanol, and a mixed solvent thereof. The temperature at which the insulating particles and the conductive particles coated with the reactive compound are brought into contact with each other is not particularly limited, but is 5 to 100 ° C., preferably 10 to 50 ° C., even near room temperature (25 ° C.). It is enough. The coated particles of the present invention can be obtained by recovering the solid content from the solvent by a conventional method, washing and drying if necessary.

The coating particles according to the present invention have an insulating particle coverage of 30% or more, preferably 30 to 100%, particularly 30 to 80%, and the coating particles are used to electrically connect the upper and lower electrodes. It is preferable from the viewpoint that the electrical reliability becomes excellent when connected.

The coverage was calculated by counting the number n of insulating particles adhering to the conductive particles by SEM and calculating the coverage from the following formula. The coverage used for the evaluation is an average value of 20 coated particles.
Coverage (%) = (n / N) x 100
N: Number of insulating particles when the insulating particles are closely packed on the surface of the conductive particles N = 4π (R + r) ² / 2√3r ²
(R: radius of conductive particles (nm), r: radius of insulating particles (nm))

As the coating particles according to the present invention, silica particles treated with a silane coupling agent having a mercapto group are used as insulating particles. The silane coupling agent having a mercapto group is a silica compound having a mercapto group and a hydrolyzable group, and the hydrolyzable group of the silica compound easily reacts with the silica particles, and the silica compound is formed with the silica particles. Join. On the other hand, the mercapto group is firmly bonded to the metal film of the conductive particles or the functional group (B) of the reactive compound. Therefore, the coated particles of the present invention have excellent adhesion between the insulating particles and the conductive particles.

Further, as the coating particles according to the present invention, as the conductive particles, those obtained by surface-treating the conductive particles with a hydrophobic agent can be used. When the hydrophobizing agent is present on the surface of the conductive particles, the affinity with the insulating particles is excellent, and the coverage of the insulating particles can be further increased.
Examples of the hydrophobizing agent include benzotriazole-based compounds, titanate-based coupling agents, higher fatty acids or derivatives thereof, phosphoric acid esters, phosphite esters, and the like. These may be used alone or in combination of two or more as required.

In this case, the insulating particles may be 1) bonded to the conductive particles via a hydrophobic agent existing on the particle surface of the conductive particles, and 2) not via a hydrophobic agent. The conductive particles may be directly bonded to the particle surface, or the above 1) and 2) may be mixed and bonded.

（式中、Ａ₁、Ａ₂は同一の又は異なるアルキル基、アリール基、ハロゲン原子、水酸基、アミノ基又はカルボキシル基を示し、ｐ１、ｑ１は同一の又は異なる０〜２の整数を示す。）
前記一般式（２）の式中のＡ₁及びＡ₂は、アルキル基、アリール基、ハロゲン原子、水酸基、アミノ基又はカルボキシル基を示す。該アルキル基としては、メチル基、エチル基、プロピル基、ブチル基等の炭素数が１〜５のものが好ましい。該アリール基としては、フェニル基、トリル基、キシリル基、ナフチル基が好ましい。該ハロゲン原子としては、塩素、臭素、ヨウ素が挙げられる。前記一般式（２）中のｐ１及びｑ１は、同一の又は異なる０〜２の整数を示す。また、Ａ₁とＡ₂は同一の基でも異なる基であってもよい。 The benzotriazole-based compound is preferably represented by the following general formula (2).

(In the formula, A ₁ and A ₂ represent the same or different alkyl group, aryl group, halogen atom, hydroxyl group, amino group or carboxyl group, and p1 and q1 represent the same or different integers 0 to 2.)
_{A 1} and A _{2 in} the formula of the general formula (2) represent an alkyl group, an aryl group, a halogen atom, a hydroxyl group, an amino group or a carboxyl group. The alkyl group preferably has 1 to 5 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group. As the aryl group, a phenyl group, a tolyl group, a xsilyl group, and a naphthyl group are preferable. Examples of the halogen atom include chlorine, bromine and iodine. P1 and q1 in the general formula (2) represent the same or different integers of 0 to 2. Further, A ₁ and A ₂ may be the same group or different groups.

Preferred specific compounds of the benzotriazole-based compound represented by the general formula (2) include, for example, benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole, 4-ethylbenzotriazole, and 5-ethylbenzotriazole. , 4,5-dimethylbenzotriazole, 4,6-dimethylbenzotriazole, 5,6-dimethylbenzotriazole, 4,5-diethylbenzotriazole, 4,6-diethylbenzotriazole, 5,6-diethylbenzotriazole, 4 -Phenylbenzotriazole, 5-phenylbenzotriazole, 4-chlorobenzotriazole, 5-chlorobenzotriazole, 4-carboxybenzotriazole, 5-carboxybenzotriazole, 4,5-dicarboxybenzotriazole, 4,6-dicarboxyl Benzotriazole and the like can be mentioned.

Examples of titanate-based coupling agents include those represented by the following formula (i) or formula (ii).
(B ¹ O) Ti (OB ² ) (OB ³ ) (OB ⁴ ) (i)
(In the formula, B ¹ is an alkyl group, and B ^{2 to} B ⁴ are an alkyl group, a group in which a methylene group other than the terminal in the alkyl group is substituted with an oxygen atom, an alkenyl group, and a group other than the terminal in the alkenyl group, respectively. groups a methylene group is replaced by an oxygen atom, an alkanoyl group, a group selected from dialkyl pyrophosphate group and benzene sulfonyl group. However, B ² any one or more of .about.B ⁴ is an alkanoyl group, dialkyl pyrophosphate group Alternatively, it is an alkylbenzene sulfonyl group. B ¹ and B ² may be combined to form a ring.)

(B ⁵ O) Ti (OB ⁶ ) (OB ⁷ ) (OB ⁸ ) · [P (OB ⁹ ) ₂ OH] ₂ (ii)
(In the formula, B ^{5 to} B ⁸ are an alkyl group, a group in which a methylene group other than the terminal in the alkyl group is substituted with an oxygen atom, an alkenyl group, or a methylene group other than the terminal in the alkenyl group is substituted with an oxygen atom, respectively. B ⁹ is an alkyl group.)
May two or three groups of B ¹ .about.B ⁴ in the formula (i) mentioned above are the same, B ¹ ~B ⁴ may all be different. May two or three groups of B ⁵ .about.B ⁸ in the compounds represented by formula (ii) are the same, B ⁵ .about.B ⁸ may all be different. Two existing B ⁹ may be different may be the same. In the compound represented by the formula (i), the preferable number of the alkanoyl group, the dialkylpyrophosphate group or the alkylbenzenesulfonyl group is 1 to 3, more preferably 2 to 3, and particularly preferably 3.

Examples of the alkyl group mentioned above include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl grave, n-pentyl group, isopentyl group, 2 -Methylbutyl group, 1-methylbutyl group, n-hexyl group, isohexyl group, 3-methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, heptyl group, octyl group, isooctyl group, 2-ethylhexyl group, 3 , 7-Dimethyloctyl group, nonyl group, decyl group, undecyl group, dodecyl group, lauryl group, tetradecyl group, hexadecyl group, octadecyl group (including stearyl group), nonadecil group, eicosyl group, triacontyl group, tetracontyl group, etc. Can be mentioned. Examples of the alkenyl group include a group in which one or more carbon-carbon single bonds of the above alkyl group are changed to a carbon-carbon double bond.

The group in which the methylene group other than the terminal in the alkyl group is substituted with an oxygen atom is not an alkoxy group but a group in which the methylene groups in the alkyl group are interrupted by an oxygen atom. The same group can be mentioned for a group in which a methylene group other than the terminal in the alkenyl group is replaced with an oxygen atom.

Alkyl groups represented by B ^{1 to} B ⁴ and B ^{5 to} B ⁸ , groups in which a methylene group other than the terminal in the alkyl group is substituted with an oxygen atom, an alkenyl group, and a methylene group other than the terminal in the alkenyl group. The number of carbon atoms of the group substituted with an oxygen atom is preferably 3 to 40, more preferably 3 to 32. The ^{alkanoyl group represented by B 2 to} B ⁴ preferably has 2 to 40 carbon atoms. The alkyl group of the dialkylpyrophosphate group represented by B ^{2 to} B ⁴ is preferably one having 3 to 40 carbon atoms. The alkyl group of the alkylbenzenesulfonyl group represented by B ^{2 to} B ⁴ is preferably one having 3 to 40 carbon atoms. As the ^{alkyl group represented by B 9} , those having 3 to 40 carbon atoms are preferable.

Examples of the ring formed by B ¹ and B ² together include a ring in which -CH _2- CH _{2- or -CH 2-} COO- or the like is composed of an oxygen atom and a titanium atom in the formula (i).

Each group represented by the above formula (i) or formula (ii) may be substituted with a substituent. Examples of the substituent in that case include a halogen atom, an epoxy group, an amino group, a vinyl group, an acrylic group, an isocyanate group, and a mercapto group.

Specific examples of the titanate-based coupling agent used in the present invention include isopropyltriisostearoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraisopropyl (dioctylphosphite) titanate, and tetraisopropylbis. (Dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, Examples thereof include bis (dioctylpyrophosphate) ethylene titanate, and these can be used alone or in combination of two or more.
These titanate-based coupling agents are commercially available, for example, from Ajinomoto Fine-Techno Co., Ltd.

The higher fatty acid is preferably a saturated or unsaturated linear or branched mono- or polycarboxylic acid, more preferably a saturated or unsaturated linear or branched monocarboxylic acid. More preferably, it is a saturated or unsaturated linear monocarboxylic acid. The fatty acid preferably has 7 or more carbon atoms. The derivative refers to a salt or amide of the fatty acid.

The fatty acid or its derivative used in the present invention preferably has 7 to 23 carbon atoms, and more preferably 10 to 20 carbon atoms. Examples of such fatty acids or derivatives thereof include saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid and arachidonic acid, or these. Examples include metal salts and amides. Metal salts of fatty acids include alkali metals, alkaline earth metals, transition metals such as Zr, Cr, Mn, Fe, Co, Ni, Cu and Ag, and salts of metals other than transition metals such as Al and Zn. , And preferably a polyvalent metal salt such as Al, Zn, W, V or the like. The fatty acid metal salt can be a mono-form, a di-form, a tri-form, a tetra-form, or the like, depending on the valence of the metal. The fatty acid metal salt may be any combination thereof.

As the phosphoric acid ester and the phosphite ester, those having an alkyl group having 6 to 22 carbon atoms are preferably used.
Examples of the phosphoric acid ester include phosphoric acid hexyl ester, phosphoric acid heptyl ester, phosphoric acid monooctyl ester, phosphoric acid monononyl ester, phosphoric acid monodecyl ester, phosphoric acid monoundecyl ester, phosphoric acid monododecyl ester, and phosphorus. Examples thereof include acid monotridecyl ester, phosphoric acid monotetradecyl ester, and phosphoric acid monopentadecyl ester.
Examples of the phosphite ester include hexyl phosphite ester, heptyl phosphite ester, monooctyl phosphite ester, monononyl phosphite ester, monodecyl phosphite ester, monoundecyl phosphite ester, and the like. Examples thereof include phosphite monododecyl ester, phosphite monotridecyl ester, phosphite monotetradecyl ester, and phosphite monopentadecyl ester.

In the present invention, the hydrophobizing agent is preferably a triazole-based compound or a titanate-based coupling agent, and is particularly benzotriazole, because it has an excellent affinity with insulating particles and has a high effect of increasing the coverage of insulating particles. , 4-Carboxybenzotriazole, isopropyltriisostearoyl titanate, tetraisopropyl (dioctylphosphite) titanate are particularly preferred.

In the present invention, the hydrophobizing agent may be present on the surface of the conductive particles, in which case it may be present on the entire surface of the conductive particles or only on a part of the surface. Good. Further, the hydrophobizing agent may form a layer that covers a part or the whole of the surface of the conductive particles.
Further, the hydrophobizing agent may be present on the surface of the conductive particles as a condensate thereof.

The method for surface-treating the conductive particles with a hydrophobic agent is not particularly limited, and a known method can be used. One example thereof is a method of mixing conductive particles and a hydrophobic agent in a solvent.

Examples of the solvent include water and an organic solvent, and a mixed solvent of water and an organic solvent may be used. Examples of the organic solvent include toluene, methanol, ethanol, propanol, butanol, isobutyl alcohol, acetone, methyl ethyl ketone, tetrahydrofuran, acetonitrile, N-methylpyrrolidone, dimethylformamide and the like. The concentration of the hydrophobizing agent is 0.01 to 20% by mass in the dispersion liquid in which the conductive particles and the hydrophobizing agent are added to the solvent. The concentration of the conductive particles in this dispersion is 1 to 50% by mass.

The treated dispersion is filtered and, if necessary, dried to obtain conductive particles having a hydrophobic agent on the surface.

Further, as a method of coating the insulating particles on the particle surface of the conductive particles surface-treated with the hydrophobic agent, the same method as the method of coating the insulating particles on the particle surface of the conductive particles described above is used. be able to.

The coated particles of the present invention utilize, for example, an anisotropic conductive film (ACF), a heat seal connector (HSC), and an electrode of a liquid crystal display panel for driving by utilizing the insulating property between the coated particles and the connectivity between the counter electrodes. It is suitably used as a conductive material for connecting to a circuit board of an LSI chip. In particular, it is suitably used as a conductive filler for a conductive adhesive.

The conductive adhesive is disposed between two substrates on which a conductive substrate is formed, and is preferably used as an anisotropic conductive adhesive that adheres and conducts the conductive substrate by heating and pressurizing. .. This anisotropic conductive adhesive contains the conductive particles of the present invention and an adhesive resin. The adhesive resin can be used without particular limitation as long as it is insulating and is used as an adhesive resin. It may be either a thermoplastic resin or a thermosetting resin, and it is preferable that the adhesive performance is exhibited by heating. Such adhesive resins include, for example, a thermoplastic type, a thermosetting type, an ultraviolet curable type and the like. Further, there are a so-called semi-thermosetting type, a composite type of a thermosetting type and an ultraviolet curable type, which show intermediate properties between a thermoplastic type and a thermosetting type. These adhesive resins can be appropriately selected according to the surface characteristics of the circuit board or the like to be adhered and the usage pattern. In particular, an adhesive resin composed of a thermosetting resin is preferable because it has excellent material strength after bonding.

Specific examples of the adhesive resin include ethylene-vinyl acetate copolymer, carboxyl-modified ethylene-vinyl acetate copolymer, ethylene-isobutyl acrylate copolymer, polyamide, polyimide, polyester, polyvinyl ether, polyvinyl butyral, and polyurethane. , SBS block copolymer, carboxyl-modified SBS copolymer, SIS copolymer, SEBS copolymer, maleic acid-modified SEBS copolymer, polybutadiene rubber, chloroprene rubber, carboxyl-modified chloroprene rubber, styrene-butadiene rubber, isobutylene- One or two selected from isoprene copolymer, acrylonitrile-butadiene rubber (hereinafter referred to as NBR), carboxyl-modified NBR, amine-modified NBR, epoxy resin, epoxy ester resin, acrylic resin, phenol resin, silicone resin, etc. Examples thereof include those prepared by using the one obtained by the above combination as a main agent. Of these, as the thermoplastic resin, styrene-butadiene rubber, SEBS, etc. are preferable because they have excellent reworkability. As the thermosetting resin, an epoxy resin is preferable. Of these, epoxy resins are most preferable because they have high adhesive strength, excellent heat resistance and electrical insulation, low melt viscosity, and can be connected at low pressure.

As the epoxy resin, a generally used epoxy resin can be used as long as it is a polyvalent epoxy resin having two or more epoxy groups in one molecule. Specific examples include novolac resins such as phenol novolac and cresol novolac, polyhydric phenols such as bisphenol A, bisphenol F, bisphenol AD, resorcin, and bishydroxydiphenyl ether, ethylene glycol, neopentyl glycol, glycerin, and trimethylolpropane. , Polyhydric alcohols such as polypropylene glycol, polyamino compounds such as ethylenediamine, triethylenetetramine, aniline, polyhydric carboxy compounds such as adipic acid, phthalic acid, isophthalic acid, etc., and epichlorohydrin or 2-methylepicrolhydrin. A glycidyl type epoxy resin is exemplified. In addition, aliphatic and alicyclic epoxy resins such as dicyclopentadiene epoxiside and butadiene dimer epoxiside can be mentioned. These can be used alone or in admixture of two or more.

As the various adhesive resins described above, it is preferable to use high-purity products in which impurity ions (Na, Cl, etc.) and hydrolyzable chlorine are reduced, from the viewpoint of preventing ion migration.

The amount of conductive particles used in the anisotropic conductive adhesive is usually 0.1 to 30 parts by mass, preferably 0.5 to 25 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the adhesive resin component. It is a department. When the amount of the conductive particles used is within this range, it is possible to suppress an increase in connection resistance and melt viscosity, improve connection reliability, and sufficiently secure anisotropy of connection.

In addition to the conductive particles and the adhesive resin described above, additives known in the art can be added to the anisotropic conductive adhesive. The blending amount can also be within the range known in the art. Other additives include, for example, tackifiers, reactive aids, epoxy resin hardeners, metal oxides, photoinitiators, sensitizers, hardeners, vulcanizers, anti-deterioration agents, heat resistant additives, heat. Examples thereof include conduction improvers, softeners, colorants, various coupling agents, and metal deactivators.

Examples of the tackifier include rosin, rosin derivative, terpene resin, terpenephenol resin, petroleum resin, kumaron-inden resin, styrene resin, isoprene resin, alkylphenol resin, xylene resin and the like. Examples of the reactive auxiliary agent, that is, the cross-linking agent, include polyols, isocyanates, melamine resins, urea resins, utropines, amines, acid anhydrides, and peroxides. The epoxy resin curing agent can be used without particular limitation as long as it has two or more active hydrogens in one minute. Specific examples thereof include polyamino compounds such as diethylenetriamine, triethylenetetramine, metaphenylenediamine, dicyandiamide, and polyamideamine; and organic acid anhydrides such as phthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and pyromellitic anhydride. Substances: Novolac resins such as phenol novolac and cresol novolak can be mentioned. These can be used alone or in admixture of two or more. In addition, a latent curing agent may be used if necessary. Examples of the latent curing agent that can be used include imidazole-based, hydrazide-based, boron trifluoride-amine complex, sulfonium salt, amineimide, polyamine salt, dicyandiamide and the like, and modified products thereof. These can be used alone or as a mixture of two or more.

The anisotropic conductive adhesive is manufactured using a manufacturing apparatus commonly used in the art. For example, conductive particles, an adhesive resin, and if necessary, a curing agent and various additives are blended, and when the adhesive resin is a thermosetting resin, it is mixed in an organic solvent, and when it is a thermoplastic resin, it is bonded. It is produced by melt-kneading at a temperature equal to or higher than the softening point of the agent resin, specifically preferably at about 50 to 150 ° C. The anisotropic conductive adhesive thus obtained may be applied or may be applied in the form of a film.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.
<Preparation of insulating particle sample>
(Insulating particles 1)
To a reaction vessel, 34.1 g of methanol was added to 44.1 g of an aqueous silica sol (SiO ₂ : 22.7% by mass, water: 77.3% by mass) to obtain a dispersion liquid. Next, 0.15 g of 3-mercaptopropyltrimethoxysilane was added to the dispersion under stirring, and the mixture was stirred as it was for 20 minutes. Then, the reaction vessel was heated to 60 ° C. and stirred for 3 hours to complete the reaction.
After completion of the reaction, the solid content was collected by filtration, the solid content was washed with methanol, dried at 120 ° C. under vacuum for 12 hours, and the surface of the silica particles was surface-treated with 3-mercaptopropyltrimethoxysilane. Insulating particles were obtained.
As the aqueous silica sol, a commercially available particle size having a particle size of 219 nm obtained by a dynamic light scattering method was used.

(Insulating particles 2)
To a reaction vessel, 35.9 g of methanol was added to 55.9 g of an aqueous silica sol (SiO ₂ : 22.7% by mass, water: 77.3% by mass) to obtain a dispersion liquid. Next, 0.39 g of 3-mercaptopropyltrimethoxysilane was added to the dispersion under stirring, and the mixture was stirred as it was for 20 minutes. Then, the reaction vessel was heated to 60 ° C. and stirred for 3 hours to complete the reaction.
After completion of the reaction, the solid content was collected by filtration, the solid content was washed with methanol, dried at 120 ° C. under vacuum for 12 hours, and the surface of the silica particles was surface-treated with 3-mercaptopropyltrimethoxysilane. Insulating particles were obtained.
As the aqueous silica sol, a commercially available particle size having a particle size of 144 nm obtained by a dynamic light scattering method was used.

(Insulating particles 3)
100 ml of pure water was put into a 200 ml four-necked flask equipped with a stirring blade. Then, 30.00 mmol of styrene monomer, 0.03 mmol of 4- (vinylbenzyl) triethylammonium chloride, and 0.50 mmol of 2,2'-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator were added. Nitrogen was aerated for 15 minutes to expel dissolved oxygen, then the temperature was raised to 60 ° C. and held for 6 hours to allow the polymerization reaction to proceed. The dispersion liquid of the polymerized fine particles was passed through a SUS sieve having an opening of 150 μm to remove aggregates. Fine particles were precipitated in the dispersion liquid from which the agglomerates had been removed by a centrifuge, and the supernatant liquid was removed. Pure water was added to the obtained solid content and washed to obtain spherical fine particles of poly (styrene / 4- (vinylbenzyl) triethylammonium chloride). The average particle size of the obtained fine particles was 272 nm.

<Preparation of conductive particle sample>
As the conductive particles, the following commercially available conductive particles were used.
The average particle size of the conductive particles is obtained by arbitrarily extracting 200 particles from a scanning electron microscope (SEM) photograph (magnification: 100,000 times), measuring their particle sizes, and averaging the average values. The particle size was used.

(Conductive particles 1)
Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel film with a thickness of 0.125 μm and an average particle diameter of 3 μm were prepared on the surface of the spherical resin particles. The resin particles were made of a crosslinkable acrylic resin, and the glass transition temperature was 120 ° C.
The average particle size was arbitrarily extracted from a scanning electron microscope (SEM) photograph (magnification: 100,000 times), the particle size was measured, and the average value was taken as the average particle size.

(Conductive particles 2)
The surface of the spherical resin particles has 1,030 protrusions having an average height of 0.1 μm, an average base length of 0.197 μm, and an aspect ratio of 0.5, and has a thickness of 0. Ni-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a nickel film of 125 μm and having an average particle diameter of 3 μm were prepared. The resin particles were made of a crosslinkable acrylic resin, and the glass transition temperature was 120 ° C. The average particle size was measured by the same method as for the conductive particle 1.

(Conductive particles 3)
Gold-plated particles (manufactured by Nippon Kagaku Kogyo Co., Ltd.) having a gold-nickel conductive layer on the surface of the spherical resin particles and having an average particle diameter of 4.6 μm were used. The resin particles were made of a crosslinkable acrylic resin, and the glass transition temperature was 120 ° C.
The average particle size was arbitrarily extracted from a scanning electron microscope (SEM) photograph (magnification: 100,000 times), the particle size was measured, and the average value was taken as the average particle size.

{Examples 1 to 6}
An insulating particle dispersion was prepared by adding pure water so that the concentration of the insulating particles obtained above was 10,000 ppm based on the solid content concentration and the total concentration was 20 ml. 50 mg of each of the conductive particle samples was added to this dispersion, and the mixture was stirred at room temperature (25 ° C.) for 15 hours.
Next, the solid content was separated from the stirred dispersion by a membrane filter having a mesh size of 10 μm, washed with water and dried, and this was used as a coated particle sample.

{Comparative example 1}
Pure water and NaCl were added so that the insulating particles 3 obtained above had a solid content concentration of 10,000 ppm, a NaCl concentration of 25 mmol, and a total of 20 ml to prepare an insulating particle dispersion. 50 mg of the conductive particle sample 1 was added to this dispersion, and the mixture was stirred at room temperature (25 ° C.) for 15 hours.
Next, the solid content was separated from the stirred dispersion by a membrane filter having a mesh size of 10 μm, washed with water and dried, and this was used as a coated particle sample.

(Evaluation of coverage)
From the coated particles obtained in Examples and Comparative Examples, the difference in coverage when the insulating particles were coated on the conductive particles was evaluated. The results are shown in Table 1. The coverage was determined by the following method.

<Measurement method of coverage>
The number N of insulating particles when the insulating particles were densely packed on the surface of the conductive particles was calculated by the following formula.
N = 4π (R + r) ² / 2√3r ²
(R: radius of conductive particles (nm), r: radius of insulating particles (nm))
The number n of the insulating particles adhering to the conductive particles was counted by SEM, and the coverage was calculated from the following formula. The results are shown in Table 1.
Coverage (%) = (n / N) x 100
The coverage used for the evaluation was an average value of 20 conductive particles.

(Evaluation of adhesion)
1 g of the coated particles obtained in Examples and Comparative Examples was added to 100 mL of pure water, and ultrasonic treatment was performed for 2 minutes under the condition of an oscillation frequency of 24 kHz with an ultrasonic device (VS-D100 manufactured by VELVO-CLEAR). The coverage of the coated particles was calculated by the same method as the evaluation of the coverage, the degree of adhesion was calculated by the following formula to evaluate the adhesion, and the results are shown in Table 1. The higher the value of the degree of adhesion, the less the insulating particles fall off due to the ultrasonic treatment, which means that the adhesion between the conductive particles and the insulating particles is high.
Adhesion (%) = (coverage after sonication / coverage before sonication) x 100

{Example 7}
100 ml of pure water was added to the conductive particles 2 (5 g) obtained above, and the mixture was stirred to obtain a dispersion liquid of the conductive particles 2. 10 ml of an aqueous solution of 1 mass% benzotriazole was put into this dispersion and stirred for 5 minutes to perform surface treatment. Then, it was filtered through a membrane filter having a mesh size of 2.0 μm, and the conductive particles 2 having a layer of benzotriazole on the surface were recovered. After washing the recovered conductive particles 2 with pure water, 100 ml of pure water was added to obtain a dispersion liquid of the conductive particles 2 having a benzotriazole layer on the surface.
The insulating particles 1 obtained above were put into this dispersion, and the particles were stirred at room temperature (25 ° C.) for 15 hours. After charging the insulating particles 1, the solid-liquid content concentration of the insulating particles 1 in the dispersion was 10,000 ppm on a mass basis. The supernatant was removed, washed with pure water, and vacuum dried at 50 ° C. to obtain a coated particle sample. Further, with respect to the obtained coated particle sample, the covering ratio and the degree of adhesion were evaluated in the same manner as in Examples 1 to 6, and the results are shown in Table 2.

{Example 8}
Toluene (25 ml) was added to the conductive particles 2 (5 g) obtained above, and the mixture was stirred to obtain a dispersion liquid of the conductive particles 2. 0.1 g of isopropyltriisostearoyl titanate (manufactured by Ajinomoto Fine-Techno, Plenact KR-TTS) was added to this dispersion and stirred at room temperature for 20 minutes for surface treatment. Then, the particles were filtered through a membrane filter having a mesh size of 2.0 μm, and the conductive particles 2 having a layer of a titanate-based coupling agent on the surface were recovered. 100 ml of a mixed solution of ethanol: pure water = 75:25 was added to the recovered conductive particles 2 on a mass basis to obtain a dispersion liquid of the conductive particles 2 having a titanate-based coupling agent layer on the surface.
The insulating particles 1 obtained above were put into this dispersion, and the particles were stirred at room temperature (25 ° C.) for 15 hours. After charging the insulating particles 1, the solid-liquid content concentration of the insulating particles 1 in the dispersion was 10,000 ppm on a mass basis. The supernatant was removed, washed with pure water, and vacuum dried at 50 ° C. to obtain a coated particle sample. Further, with respect to the obtained coated particle sample, the covering ratio and the degree of adhesion were evaluated in the same manner as in Examples 1 to 6, and the results are shown in Table 2.

<Evaluation of conductivity>
An insulating adhesive 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 was mixed with 15 parts by mass of a coated particle sample obtained in Examples to obtain an insulating paste. This paste was applied onto 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-forming film was placed between a glass substrate on which aluminum was vapor-deposited on the entire surface and a polyimide film substrate on which copper patterns were formed at a pitch of 50 μm, and electrical connection was made. By measuring the conduction resistance between the substrates, the conductivity of the coated particles was evaluated at room temperature (25 ° C., 50% RH). It can be evaluated that the lower the resistance value, the higher the conductivity of the coated particles. The conductivity evaluation of the coated particles is "very good" when the resistance value is less than 2Ω (indicated by "○" in Table 3), and "good" when the resistance value is 2Ω or more and less than 5Ω. (Indicated by "Δ" in Table 3), and those having a resistance value of 5Ω or more were evaluated as "defective" (indicated by "x" in Table 3). The results are shown in Table 3.

Claims (8)

A silane coupling agent in which the surface of conductive particles having a metal film formed on the surface of core material particles is coated with insulating particles, and the insulating particles have a mercapto group on the surface of the silica particles. Coated particles characterized by being surface-treated with. The coated particles according to claim 1, wherein the core material particles are a resin or a composite material of an organic substance and an inorganic substance. The coating particle according to any one of claims 1 and 2, wherein the metal film is at least one film selected from nickel, palladium, gold, a nickel alloy, a palladium alloy, and a gold alloy. The coated particle according to any one of claims 1 to 3, wherein the conductive particle has a plurality of protrusions on the metal film. The coated particle according to any one of claims 1 to 4, wherein the silane coupling agent having a mercapto group is mercaptopropyltrimethoxysilane. The coated particle according to any one of claims 1 to 5, wherein the conductive particle is surface-treated with a hydrophobic agent. The coated particle according to claim 6, wherein the hydrophobic agent is a benzotriazole-based compound or a titanate-based coupling agent. A conductive material containing the coating particles according to any one of claims 1 to 7 and an insulating resin.