Coated particles, coated particle production method, resin composition, and connection structure

Abstract

The present invention provides coated particles with which it is possible to suppress particle aggregation, and to increase conduction reliability and increase insulation reliability when electrically connecting electrodes.　Coated particles according to the present invention each comprise an insulative-particle-including conductive particle, and a coating portion. Each insulative-particle-including conductive particle is composed of a conductive particle and a plurality of insulative particles disposed on the surface of the conductive particle. Each conductive particle is composed of a base particle and a conducting portion disposed on the surface of the base particle. The coating portion covers at least part of the surface of the conducting portion and at least part of the surface of the insulative particles. The material forming the coating portion includes polymerizable monomers, and the polymerizable monomers include crosslinkable monomers. The crosslinkable monomer content accounts for 10.0 wt% or more of 100 wt% of all the polymerizable monomers.

Description

Coated particles, method for producing coated particles, resin composition, and connection structure

[0001] The present invention relates to coated particles using conductive particles with insulating particles, a method for producing the coated particles, and a resin composition and connection structure using the coated particles.

[0002] Anisotropic conductive materials, such as anisotropic conductive pastes and anisotropic conductive films, are widely known, and in such anisotropic conductive materials, conductive particles are dispersed in a binder resin.

[0003] The anisotropic conductive material is used to obtain various connection structures, such as a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), a connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

[0004] In some cases, the conductive particles may be conductive particles with insulating particles disposed on the surfaces of the conductive particles, and a coating portion may be formed on the surfaces of the conductive particles with insulating particles to prevent the insulating particles from detaching from the conductive particle bodies before conductive connection.

[0005] Conductive particles with insulating particles having a coating portion on the surface are disclosed in Patent Documents 1 and 2 listed below.

[0006] Patent Document 1 below discloses a conductive particle with insulating particles (coated particle) comprising a conductive particle body having a conductive layer on its surface, an insulating resin layer (coating) covering the surface of the conductive particle body, and a plurality of insulating particles arranged on the surface of the conductive particle body. In Patent Document 1, the average thickness of the resin layer is 1 / 6 or less of the average particle diameter of the conductive particle body, and the average particle diameter of the insulating particles is 1.5 to 3.5 times the average thickness of the resin layer.

[0007] Furthermore, Patent Document 2 below discloses a conductive particle with insulating particles (coated particle) comprising a conductive particle body with insulating particles and a coating coating the surface of the conductive particle body with insulating particles. The conductive particle body with insulating particles comprises a conductive particle having a conductive portion at least on its surface, and a plurality of insulating particles arranged on the surface of the conductive particle. In Patent Document 2, the conductive particle has a plurality of protrusions on the outer surface of the conductive portion, and the average height of the protrusions is 0.05 μm or more and 0.5 μm or less. Furthermore, Patent Document 2 also discloses that the coating has a first coating portion covering the conductive particle and a second coating portion covering the surface of the insulating particle, and the ratio of the thickness of the first coating portion to the average particle diameter of the insulating particle is 2 / 3 or more and 3 or less.

[0008] JP 2011-187332 A JP 2016-085988 A

[0009] In the case of conventional coated particles such as those disclosed in Patent Documents 1 and 2, when a coating is formed on the surface of the conductive particles with insulating particles, the particles tend to aggregate in the dispersion, and therefore the surface may not be sufficiently coated with the coating, and the coating may detach from the surface. As a result, when electrodes are electrically connected by the conductive particles, it may be difficult to improve the insulation reliability.

[0010] Furthermore, when an anisotropic conductive material is used that is prepared using conductive particles with insulating particles or coated particles that have undergone aggregation and a binder resin, the particles may not be uniformly arranged between the upper and lower electrodes that should be connected after the anisotropic conductive material is applied, and as a result, it may be difficult to sufficiently improve the electrical conductivity reliability. Furthermore, the presence of agglomerated particles may easily cause short circuits between laterally adjacent electrodes that should not be connected, which may reduce the insulation reliability between laterally adjacent electrodes.

[0011] An object of the present invention is to provide coated particles that can suppress particle aggregation and, when electrically connecting electrodes, can improve conduction reliability and insulation reliability. Another object of the present invention is to provide a method for producing the coated particles, a resin composition using the coated particles, and a connection structure.

[0012] According to a broad aspect of the present invention, there is provided a coated particle comprising a conductive particle with insulating particles and a coating portion, wherein the conductive particle with insulating particles has a conductive particle and a plurality of insulating particles arranged on the surface of the conductive particle, the conductive particle has a base particle and a conductive portion arranged on the surface of the base particle, the coating portion coating at least a portion of the surface of the conductive portion and at least a portion of the surface of the insulating particle, the material of the coating portion containing a polymerizable monomer, the polymerizable monomer containing a crosslinkable monomer, and the content of the crosslinkable monomer in 100% by weight of the polymerizable monomer is 10.0% by weight or more.

[0013] In a specific aspect of the coated particles according to the present invention, the crosslinkable monomer includes divinylbenzene.

[0014] In a specific aspect of the coated particle according to the present invention, the polymerizable monomer includes a compound represented by the following formula (1):

[0015]

[0016] In the formula (1), X1 represents a hydroxyl group, an alkoxy group, or an alkyl group having 1 to 12 carbon atoms, and X2 represents an organic group containing an unsaturated bond, and the organic group containing an unsaturated bond contains a (meth)acryloyl group.

[0017] In a specific aspect of the coated particle according to the present invention, the polymerizable monomer includes a non-crosslinkable monomer, and the non-crosslinkable monomer includes styrene.

[0018] In a specific aspect of the coated particles according to the present invention, the insulating particles are resin particles.

[0019] In a specific aspect of the coated particles according to the present invention, the insulating particles include a polymer.

[0020] In a specific aspect of the coated particle according to the present invention, the ratio of the thickness of the coating to the particle diameter of the insulating particle is 1 / 2 or less.

[0021] In a specific aspect of the coated particle according to the present invention, the area of ​​the portion covered by the coating portion is 80% or more of the total surface area (100%) of the conductive particle with insulating particles.

[0022] According to a broad aspect of the present invention, there is provided a method for producing the above-mentioned coated particles, which includes a step of polymerizing the material of the coating portion in a dispersion liquid in which the conductive particles with insulating particles are dispersed in a dispersion medium, thereby forming the coating portion on the surface of the conductive portion of the conductive particle and on the surface of the insulating particle, thereby obtaining the coated particle.

[0023] In a specific aspect of the method for producing coated particles according to the present invention, the method for producing coated particles includes a step of arranging the conductive portion on the surface of the base particle to obtain a conductive particle, and a step of arranging a plurality of the insulating particles on the surface of the conductive portion of the conductive particle to obtain a conductive particle with insulating particles.

[0024] According to a broad aspect of the present invention, there is provided a resin composition comprising the coated particles described above and a binder resin.

[0025] According to a broad aspect of the present invention, there is provided a connection structure comprising a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member, wherein the material of the connection portion contains the above-mentioned coated particles, and the first electrode and the second electrode are electrically connected by the conductive particles.

[0026] The coated particle according to the present invention comprises a conductive particle with insulating particles and a coating portion. In the coated particle according to the present invention, the conductive particle with insulating particles comprises a conductive particle and a plurality of insulating particles disposed on the surface of the conductive particle. In the coated particle according to the present invention, the conductive particle comprises a base particle and a conductive portion disposed on the surface of the base particle. In the coated particle according to the present invention, the coating portion coats at least a portion of the surface of the conductive portion and at least a portion of the surface of the insulating particle. In the coated particle according to the present invention, the material of the coating portion contains a polymerizable monomer, and the polymerizable monomer contains a crosslinkable monomer, and the content of the crosslinkable monomer in 100% by weight of the polymerizable monomer is 10.0% by weight or more. Because the coated particle according to the present invention has the above configuration, particle aggregation can be suppressed, and when electrodes are electrically connected, electrical connection reliability and insulation reliability can be improved.

[0027] Fig. 1 is a cross-sectional view showing a coated particle according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view showing a coated particle according to a second embodiment of the present invention. Fig. 3 is a cross-sectional view showing a coated particle according to a third embodiment of the present invention. Fig. 4 is a cross-sectional view schematically showing a connection structure using the coated particle according to the first embodiment of the present invention.

[0028] The present invention will be described in detail below.

[0029] (Coated Particles) The coated particles according to the present invention comprise conductive particles with insulating particles and a coating portion. In the coated particles according to the present invention, the conductive particles with insulating particles comprise conductive particles and a plurality of insulating particles disposed on the surfaces of the conductive particles. In the coated particles according to the present invention, the conductive particles comprise base particles and conductive portions disposed on the surfaces of the base particles. In the coated particles according to the present invention, the coating portions coat at least a portion of the surface of the conductive portions and at least a portion of the surface of the insulating particles. In the coated particles according to the present invention, the material of the coating portion contains a polymerizable monomer, and the polymerizable monomer contains a crosslinkable monomer. In the coated particles according to the present invention, the content of the crosslinkable monomer in 100% by weight of the polymerizable monomer is 10.0% by weight or more.

[0030] Conventional coated particles use a non-crosslinkable monomer as the coating material, and therefore, when a coating is formed on the surface of the insulating particle-attached conductive particle, the particles (insulating particle-attached conductive particles) tend to aggregate in the dispersion, which can result in insufficient coating of the surface of the insulating particle-attached conductive particle. As a result, when electrodes are electrically connected by the conductive particles, it can be difficult to improve insulation reliability due to the insulating particles being detached from the surface of the conductive particle. Furthermore, if the particles aggregate during coating formation, the resulting coated particles also tend to be in an aggregated state.

[0031] Furthermore, when an anisotropic conductive material is used that is prepared using conductive particles with insulating particles or coated particles that have undergone aggregation and a binder resin, the particles are not uniformly arranged between the upper and lower electrodes that should be connected after the anisotropic conductive material is applied, and as a result, it may be difficult to sufficiently improve the electrical conductivity reliability. Furthermore, the presence of agglomerated particles may easily cause short circuits between laterally adjacent electrodes that should not be connected, and may reduce the insulation reliability between laterally adjacent electrodes.

[0032] On the other hand, the coated particles according to the present invention have the above-mentioned configuration, and therefore can suppress particle aggregation, and when electrodes are electrically connected, can improve the conductivity reliability and the insulation reliability.

[0033] Specific embodiments of the present invention will be described below with reference to the drawings. Note that different parts in Fig. 1 and the following figures are interchangeable. For convenience of illustration, the size and thickness of each component in Fig. 1 and the following figures may differ from the actual size and thickness.

[0034] FIG. 1 is a cross-sectional view showing a coated particle according to a first embodiment of the present invention.

[0035] 1 includes a conductive particle 2 with insulating particles and a coating portion 3. In the coated particle 1, the conductive particle 2 with insulating particles includes a conductive particle 11 and a plurality of insulating particles 12 arranged on the surface of the conductive particle 11. In the coated particle 1, the conductive particle 11 includes a base particle 21 and a conductive portion 22 arranged on the surface of the base particle 21.

[0036] In the coated particle 1, the coating portion 3 coats the surface of the conductive particle 11 (surface of the conductive portion 22) and the surface of the insulating particle 12. In the coated particle 1, the coating portion 3 is disposed on the surface of the conductive particle 11 (surface of the conductive portion 22) and on the surface of the insulating particle 12, and is in contact with the conductive particle 11 (conductive portion 22) and the insulating particle 12. In the coated particle 1, the coating portion 3 coats the surface of the conductive particle 2 with insulating particles.

[0037] In the coated particle 1, the insulating particle 12 is arranged on the surface of the conductive particle 11. In the coated particle 1, the insulating particle 12 is arranged on the surface of the conductive portion 22 and is in contact with the conductive portion 22.

[0038] The conductive portion 22 covers the surface of the base particle 21. In the conductive particle 11, the surface of the base particle 21 is covered with the conductive portion 22. The conductive particle 11 has the conductive portion 22 on the surface.

[0039] In the coated particle 1, the conductive portion 22 is a conductive layer. The conductive portion 22 is a single-layer conductive layer. In the conductive particle, the conductive portion may cover the entire surface of the base particle, or the conductive portion may cover only a portion of the surface of the base particle.

[0040] The coated particles 1 can be obtained, for example, by polymerizing the material of the coating portions 3 in a dispersion liquid using conductive particles 2 with insulating particles (conductive particles 11 with insulating particles 12 attached) before the coating portions 3 are disposed thereon, thereby forming the coating portions 3. The polymerization can be carried out in a dispersion liquid in which the conductive particles 2 with insulating particles are dispersed in a dispersion medium. Furthermore, the coated particles 1A and 1B described below can also be obtained in the same manner as the coated particles 1.

[0041] FIG. 2 is a cross-sectional view showing a coated particle according to a second embodiment of the present invention.

[0042] 2 includes a conductive particle 2A with insulating particles and a coating portion 3A. In the coated particle 1A, the conductive particle 2A with insulating particles includes a conductive particle 11A and a plurality of insulating particles 12A arranged on the surface of the conductive particle 11A. In the coated particle 1A, the conductive particle 11A includes a base particle 21A and a conductive portion 22A arranged on the surface of the base particle 21A.

[0043] In the coated particle 1A, the coating portion 3A coats the surface of the conductive particle 11A (the surface of the conductive portion 22A) and the surface of the insulating particle 12A. In the coated particle 1A, the coating portion 3A is disposed on the surface of the conductive particle 11A (the surface of the conductive portion 22A) and on the surface of the insulating particle 12A, and is in contact with the conductive particle 11A (the conductive portion 22A) and the insulating particle 12A. In the coated particle 1A, the coating portion 3A coats the surface of the insulating particle-attached conductive particle 2A.

[0044] In coated particle 1A, insulating particle 12A is disposed on the surface of conductive particle 11A. In coated particle 1A, insulating particle 12A is disposed on the surface of conductive portion 22A and is in contact with conductive portion 22A.

[0045] In the coated particle 1A, the conductive portion 22A is a two-layer conductive layer. The conductive portion 22A includes a first conductive portion 22AA and a second conductive portion 22AB. In the conductive portion 22A, the first conductive portion 22AA is layered on the surface of the base particle 21A, and the second conductive portion 22AB is layered on the surface of the first conductive portion 22AA.

[0046] The structure of the conductive portion is different between the coated particle 1 and the coated particle 1A. The conductive portion may be a single conductive layer or multiple conductive layers.

[0047] FIG. 3 is a cross-sectional view showing a coated particle according to a third embodiment of the present invention.

[0048] 3 includes a conductive particle 2B with insulating particles and a coating portion 3B. In the coated particle 1B, the conductive particle 2B with insulating particles has a conductive particle 11B and a plurality of insulating particles 12B arranged on the surface of the conductive particle 11B. In the coated particle 1B, the conductive particle 11B has a base particle 21B, a conductive portion 22B arranged on the surface of the base particle 21B, and a plurality of core materials 23B arranged on the surface of the base particle 21B.

[0049] In coated particle 1B, coating portion 3B coats the surface of conductive particle 11B (surface of conductive portion 22B) and the surface of insulating particle 12B. In coated particle 1B, coating portion 3B is disposed on the surface of conductive particle 11B (surface of conductive portion 22B) and on the surface of insulating particle 12B, and is in contact with conductive particle 11B (conductive portion 22B) and insulating particle 12B. In coated particle 1B, coating portion 3B coats the surface of insulating particle-attached conductive particle 2B.

[0050] In coated particle 1B, insulating particle 12B is disposed on the surface of conductive particle 11B. In coated particle 1B, insulating particle 12B is disposed on the surface of conductive portion 22B and is in contact with conductive portion 22B.

[0051] In coated particle 1B, conductive portion 22B coats base particle 21B and core material 23B. Because core material 23B is coated with conductive portion 22B, coated particle 1B, conductive particle 2B with insulating particles, and conductive particle 11B have a plurality of protrusions 11Ba on their surfaces. The surface of conductive portion 22B is raised by core material 23B, forming a plurality of protrusions 11Ba.

[0052] The difference between the coated particles 1 and the coated particles 1B is whether a core substance is used or not, and whether protrusions are present or not. The coated particles may or may not have protrusions on the surface.

[0053] Other details of the coated particles will be described below.

[0054] In this specification, "(meth)acrylate" refers to acrylate and methacrylate, "(meth)acrylic" refers to acrylic and methacrylic, and "(meth)acryloyl" refers to acryloyl and methacryloyl.

[0055] The particle diameter of the coated particles is preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 2.0 μm or more, and preferably 20 μm or less, more preferably 10 μm or less, even more preferably 5.0 μm or less. If the particle diameter of the coated particles is above the above lower limit and below the above upper limit, when electrodes are connected using the coated particles, the contact area between the coated particles and the electrodes is sufficiently large, and agglomerated coated particles are less likely to form when forming a conductive portion. In addition, the gap between the electrodes connected via the coated particles is not too large, and the conductive portion is less likely to peel off from the surface of the base particle.

[0056] The particle size of the coated particles is preferably an average particle size. The average particle size means a number-average particle size. The particle size of the coated particles can be determined, for example, by observing 50 random coated particles with an electron microscope or an optical microscope and calculating the average particle size of each coated particle, or by performing laser diffraction particle size distribution measurement.

[0057] In order to more effectively exert the effects of the present invention, the coefficient of variation (CV value) of the particle diameter of the coated particles is preferably 10% or less, more preferably 5% or less.

[0058] The coefficient of variation (CV value) can be measured as follows.

[0059] CV value (%) = (ρ / Dn) × 100, where ρ is the standard deviation of the particle diameter of the coated particles, and Dn is the average particle diameter of the coated particles.

[0060] The shape of the coated particles is not particularly limited, and may be spherical, or may be a shape other than spherical, such as flat.

[0061] The coated particles are dispersed in a binder resin and are suitably used to obtain a resin composition.

[0062] Other details of the coated particles will be described below.

[0063] <Base Particles> Examples of the base particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particles may be core-shell particles having a core and a shell disposed on the surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

[0064] Examples of materials for the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonate, polyamide, phenol-formaldehyde resin, melamine-formaldehyde resin, benzoguanamine-formaldehyde resin, urea-formaldehyde resin, phenolic resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamide-imide, polyether ether ketone, polyether sulfone, and divinylbenzene polymer. The divinylbenzene polymer may be a divinylbenzene copolymer. Examples of the divinylbenzene copolymer include a divinylbenzene-styrene copolymer and a divinylbenzene-(meth)acrylic acid ester copolymer. The material of the resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group, since this allows the hardness of the resin particles to be easily controlled within a suitable range.

[0065] When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

[0066] Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; alkyl (meth)acrylate compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; and alkyl (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate and glycerol (meth)acrylate. nitrile-containing monomers such as (meth)acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acid ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

[0067] Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol Examples of suitable crosslinkable monomers include polyfunctional (meth)acrylate compounds such as 1,4-butanediol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane. From the viewpoint of maintaining the shape of the resin particles even at the glass transition temperature of the resin particles, the crosslinkable monomer is preferably (poly)ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, or dipentaerythritol poly(meth)acrylate.

[0068] The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method, such as a suspension polymerization method in the presence of a radical polymerization initiator, or a method in which non-crosslinked seed particles are used to swell and polymerize the monomer together with the radical polymerization initiator.

[0069] When the base particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, the inorganic material for forming the base particles can be silica, alumina, barium titanate, zirconia, carbon black, etc. Preferably, the inorganic material is not metal. Examples of the particles formed by silica include particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then optionally baking the particles. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed by crosslinked alkoxysilyl polymer and acrylic resin.

[0070] The organic-inorganic hybrid particles are preferably core-shell organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. The core is preferably an organic core. The shell is preferably an inorganic shell. From the viewpoint of effectively reducing the connection resistance between electrodes, the base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell disposed on the surface of the organic core.

[0071] Examples of the material for the organic core include the materials for the resin particles described above.

[0072] Examples of materials for the inorganic shell include the inorganic substances listed as materials for the base particle described above. The material for the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a shell-like substance from a metal alkoxide on the surface of the core by a sol-gel method and then firing the shell-like substance. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

[0073] When the base particles are metal particles, examples of the metal that is the material of the metal particles include silver, copper, nickel, silicon, gold, and titanium.

[0074] The particle diameter of the base particle is preferably 0.5 μm or more, more preferably 1.0 μm or more, and preferably 10 μm or less, more preferably 5.0 μm or less. When the particle diameter of the base particle is equal to or greater than the above lower limit and equal to or less than the above upper limit, the distance between the electrodes becomes small, and even if the thickness of the conductive portion is increased, small conductive particles (coated particles) can be obtained. Furthermore, when the conductive portion is formed on the surface of the base particle and the coating portion is arranged, aggregation is less likely to occur, and aggregated conductive particles with insulating particles and coated particles are less likely to be formed.

[0075] The shape of the base particles is not particularly limited, and may be spherical, or may be a shape other than spherical, such as flat.

[0076] The particle size of the base particles refers to the number average particle size. The particle size of the base particles is determined using a particle size distribution measuring device or the like. The particle size of the base particles is preferably determined by observing 50 random base particles under an electron microscope or optical microscope and calculating the average value. When measuring the particle size of the base particles in the coated particles, it can be measured, for example, as follows.

[0077] The coated particles were added to Kulzer's Technovit 4000 so that the content of the coated particles was 30% by weight, and dispersed to prepare an embedding resin for testing containing the coated particles. A cross section of the coated particles was cut out using an ion milling device (Hitachi High-Technologies Corporation's IM4000) so as to pass through the vicinity of the center of the coated particles dispersed in the embedding resin for testing. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 coated particles were randomly selected, and the base particle of each coated particle was observed. The particle diameter of the base particle in each coated particle was measured, and the arithmetic average was calculated to obtain the particle diameter of the base particle.

[0078] <Core Material and Protrusions> The coated particles preferably have protrusions on the outer surface of the conductive portion. The number of protrusions is preferably multiple. The conductive particles preferably have protrusions on the outer surface of the conductive portion. The number of protrusions is preferably multiple. Generally, an oxide film is often formed on the surface of an electrode that comes into contact with the coated particles. When coated particles having protrusions on their surfaces are used, the protrusions can effectively remove the oxide film during conductive connection. This ensures more reliable contact between the electrode and the coated particles, allowing the contact area between the coated particles and the electrode to be sufficiently increased, and further effectively reducing connection resistance. Furthermore, when the coated particles are dispersed in a binder resin and used as a resin composition or conductive material, the protrusions of the coated particles can more effectively remove the binder resin between the coated particles and the electrode. This allows the contact area between the coated particles and the electrode to be sufficiently increased, and further effectively reducing connection resistance.

[0079] Methods for forming protrusions on the surfaces of coated particles and conductive particles include a method in which a core substance is attached to the surface of a base particle and then a conductive portion is formed by electroless plating, and a method in which a conductive portion is formed on the surface of a base particle by electroless plating, then a core substance is attached, and then a conductive portion is formed by further electroless plating.

[0080] Examples of methods for adhering a core substance to the surface of a base particle include a method of adding a core substance to a dispersion of the base particle and accumulating and adhering the core substance to the surface of the base particle by, for example, van der Waals forces, and a method of adding a core substance to a container containing the base particle and adhering the core substance to the surface of the base particle by mechanical action such as rotating the container. Among these, the method of adhering a core substance to the surface of the base particle in a dispersion is preferred because it is easy to control the amount of core substance to be adhered.

[0081] The conductive particle may have a first conductive portion on the surface of the base particle and a second conductive portion on the surface of the first conductive portion. In this case, a core material may be attached to the surface of the base particle, or a core material may be attached to the surface of the first conductive portion. The core material is preferably coated with the second conductive portion, and more preferably coated with the first conductive portion and the second conductive portion. The conductive particle is preferably obtained by attaching a core material to the surface of the base particle, forming a first conductive portion on the surfaces of the base particle and the core material, and then forming a second conductive portion on the surface of the first conductive portion.

[0082] The material constituting the core material includes conductive materials and non-conductive materials. The conductive materials include, for example, conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. The conductive polymers include polyacetylene. The non-conductive materials include silica, alumina, and zirconia. From the viewpoint of increasing conductivity, the material constituting the core material is preferably a metal. From the viewpoint of increasing conductivity, the core material is preferably a metal particle.

[0083] Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys composed of two or more metals, such as tin-lead alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. Of these, nickel, copper, silver, and gold are preferred. The metal constituting the core material may be the same as or different from the metal constituting the conductive portion (conductive layer).

[0084] The shape of the core material is not particularly limited. The core material is preferably in the form of a mass. Examples of the core material include a particulate mass, an aggregate of multiple microparticles, and an amorphous mass.

[0085] The average height of the plurality of protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average height of the protrusions is equal to or more than the above lower limit and equal to or less than the above upper limit, the connection resistance between the electrodes can be effectively reduced.

[0086] <Conductive Portion> In the present invention, the conductive particle has a conductive portion on its surface. The conductive portion is disposed on the surface of the base particle.

[0087] The conductive portion preferably contains a metal. The metal constituting the conductive portion is not particularly limited. Examples of the metal include gold, silver, copper, tin, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, as well as alloys thereof. Furthermore, tin-doped indium oxide (ITO) may be used as the metal. Only one of the metals may be used, or two or more of them may be used in combination.

[0088] From the viewpoint of further improving the conduction reliability, the conductive portion preferably contains tin, nickel, palladium, copper or gold, more preferably contains tin or nickel, and even more preferably contains nickel.

[0089] From the viewpoint of further improving the conduction reliability, the conductive portion preferably contains nickel as the main metal. From the viewpoint of further improving the conduction reliability, the content of nickel in 100% by weight of the conductive portion is preferably 15% by weight or more, more preferably 20% by weight or more, even more preferably 25% by weight or more, and particularly preferably 30% by weight or more. From the viewpoint of further improving the conduction reliability, the content of nickel in 100% by weight of the conductive portion may be 100% by weight (total amount) or may be 90% by weight or less.

[0090] The conductive portion may be formed of one layer. The conductive portion may be formed of multiple layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of multiple layers, the metal constituting the outermost layer is preferably tin, nickel, palladium, copper, or gold, more preferably tin, nickel, palladium, or nickel, and even more preferably palladium or gold. When the metal constituting the outermost layer is one of these preferred metals, the connection resistance between the electrodes is further reduced. Furthermore, when the metal constituting the outermost layer is gold, corrosion resistance is further improved.

[0091] The area of ​​the portion covered by the conductive portion (coverage by the conductive portion) of the total surface area of ​​the base particle (100%) is preferably 80% or more, more preferably 90% or more. The upper limit of the coverage by the conductive portion is not particularly limited. The coverage by the conductive portion may be 99% or less. When the coverage by the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, the electrical connection reliability can be further effectively improved when electrodes are electrically connected.

[0092] The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, and is preferably 1.0 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or greater than the above lower limit and equal to or less than the above upper limit, the electrical conductivity reliability can be more effectively improved, and the conductive particles can be sufficiently deformed when connecting electrodes without becoming too hard.

[0093] When the conductive portion is formed of multiple layers, the thickness of the conductive portion of the outermost layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, and preferably 0.5 μm or less, more preferably 0.3 μm or less. When the thickness of the conductive portion of the outermost layer is equal to or greater than the above lower limit and equal to or less than the above upper limit, the conductive portion of the outermost layer becomes uniform, the corrosion resistance is sufficiently high, and the connection resistance between electrodes can be sufficiently low.

[0094] When the conductive portion is formed of multiple layers, the thickness of the conductive portion of the innermost layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 0.5 μm or less, more preferably 0.3 μm or less. When the thickness of the conductive portion of the innermost layer is equal to or greater than the lower limit and equal to or less than the upper limit, corrosion resistance is sufficiently high and the connection resistance between electrodes can be further reduced.

[0095] The thickness of the conductive portion can be measured by observing the cross section of the coated particle using, for example, a transmission electron microscope (TEM).

[0096] The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of methods for forming the conductive portion include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and coating the surface of the base particle with a metal powder or a paste containing a metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical collision. Examples of physical vapor deposition methods include vacuum deposition, ion plating, and ion sputtering. Furthermore, the physical collision method uses, for example, a sheeter composer (manufactured by Tokuju Manufacturing Co., Ltd.).

[0097] <Insulating Particles> The coated particles according to the present invention comprise a plurality of insulating particles arranged on the surface of the conductive particle. Because the coated particles have the above-described configuration, when the coated particles are used to connect electrodes, short-circuiting between adjacent electrodes can be prevented. Specifically, when a plurality of coated particles come into contact with each other, insulating particles are present between the plurality of electrodes, preventing short-circuiting between horizontally adjacent electrodes rather than between upper and lower electrodes. Furthermore, when connecting electrodes, applying pressure to the coated particles with the two electrodes can easily remove insulating particles between the conductive particle and the electrode. Furthermore, when the conductive particle has a plurality of protrusions on the outer surface of the conductive portion, the insulating particles between the conductive particle and the electrode can be even more easily removed.

[0098] The insulating particles are preferably polymers of a polymerizable compound. The polymerizable compound is not particularly limited. Examples of the polymerizable compound include the above-mentioned resin particle materials. From the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the insulating particles are preferably resin particles. Furthermore, from the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the insulating particles preferably contain a polymer.

[0099] From the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the molecular weight of the polymer is preferably 10,000 or more, more preferably 50,000 or more, even more preferably 100,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, even more preferably 1,000,000 or less.

[0100] From the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the material of the insulating particles preferably contains a divinylbenzene-styrene copolymer.

[0101] From the viewpoint of more effectively improving the conductivity reliability and insulation reliability when electrodes are electrically connected, the content of divinylbenzene in 100% by weight of the material of the insulating particles is preferably 1% by weight or more, more preferably 2% by weight or more, and is preferably 20% by weight or less, more preferably 15% by weight or less, and even more preferably 10% by weight or less.

[0102] Methods for disposing the insulating particles on the surface of the conductive part include chemical methods and physical or mechanical methods. Examples of the chemical methods include interfacial polymerization, suspension polymerization in the presence of particles, and emulsion polymerization. Examples of the physical or mechanical methods include spray drying, hybridization, electrostatic deposition, spraying, dipping, and vacuum deposition. From the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the method for disposing the insulating particles on the surface of the conductive part is preferably a physical method.

[0103] The particle diameter of the insulating particles can be appropriately selected depending on the particle diameter of the coated particles and the application of the coated particles. The particle diameter of the insulating particles is preferably 10 nm or more, more preferably 100 nm or more, even more preferably 200 nm or more, particularly preferably 300 nm or more, and preferably 2000 nm or less, more preferably 1000 nm or less, even more preferably 800 nm or less, particularly preferably 500 nm or less. If the particle diameter of the insulating particles is above the lower limit, multiple coated particles are less likely to aggregate when dispersed in a binder resin. If the particle diameter of the insulating particles is below the upper limit, excessive pressure and high temperature heating are not required to remove insulating particles between electrodes and conductive particles when connecting electrodes.

[0104] The particle diameter of the insulating particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the insulating particles is determined using a particle size distribution measuring device or the like. The particle diameter of the insulating particles is preferably determined by observing 50 random insulating particles with an electron microscope or optical microscope, calculating the average value, or by performing laser diffraction particle size distribution measurement. When measuring the particle diameter of the insulating particles in the coated particles, for example, it can be measured as follows.

[0105] The coated particles are added to Kulzer's "Technovit 4000" to a content of 30 wt % and dispersed to prepare an embedding resin for testing containing the coated particles. An ion milling device (Hitachi High-Technologies Corporation's "IM4000") is used to cut out a cross section of the insulating particles so as to pass through the vicinity of the center of the insulating particles among the dispersed coated particles in the embedding resin for testing. Then, a field emission scanning electron microscope (FE-SEM) is used to set the image magnification to 50,000 times, and 50 insulating particles are randomly selected and observed. The equivalent circle diameter of the insulating particles is measured as the particle diameter, and the arithmetic average of these is used to determine the particle diameter of the insulating particles.

[0106] The coated particles according to the present invention may contain two or more types of insulating particles having different particle diameters. By using two or more types of insulating particles having different particle diameters, the insulating particles having smaller particle diameters can enter the gaps between the insulating particles having larger particle diameters, thereby enabling the insulating particles to be more efficiently arranged on the surfaces of the conductive particles.

[0107] The insulating particles preferably have a particle size coefficient of variation (CV value) of 20% or less. When the coefficient of variation of the particle size of the insulating particles is equal to or less than the upper limit, the insulating particles in the obtained coated particles have a more uniform thickness, which makes it easier to apply uniform pressure during conductive connection and further reduces the connection resistance between electrodes.

[0108] The coefficient of variation (CV value) can be measured as follows.

[0109] CV value (%) = (ρ / Dn) × 100, where ρ: standard deviation of particle diameter of insulating particles, and Dn: average particle diameter of insulating particles.

[0110] The shape of the insulating particles is not particularly limited, and may be spherical, may be a shape other than spherical, or may be flat or the like.

[0111] From the viewpoint of more effectively improving the conduction reliability and insulation reliability when electrodes are electrically connected, the area of ​​the portion covered by the insulating particles (coverage rate by the insulating particles) out of the total surface area (100%) of the conductive portion is preferably 30% or more, more preferably 40% or more, and preferably 70% or less, more preferably 60% or less.

[0112] The coverage by insulating particles can be measured, for example, by the following method. Conductive particles with insulating particles are observed from one direction using a scanning electron microscope (SEM), and the coverage is calculated from the total area of ​​insulating particles within a circle at the outer periphery of the surface of the conductive portion in the observed image, relative to the total area within the circle at the outer periphery of the surface of the conductive portion. The coverage by insulating particles is preferably calculated as an average coverage by observing 20 conductive particles with insulating particles and averaging the measurement results for each conductive particle with insulating particles.

[0113] The coverage rate of the insulating particles can also be measured by mapping analysis such as EDX associated with SEM.

[0114] The coverage rate of the insulating particles can be adjusted by, for example, the amount of insulating particles added to the base particles, the mixing time, etc., and therefore, the method for adjusting the coverage rate of the insulating particles is not particularly limited.

[0115] <Coating portion> In the coated particle according to the present invention, the coating portion covers at least a portion of the surface of the conductive portion and at least a portion of the surface of the insulating particle. The coating portion covers at least a portion of the surface of the conductive particle with insulating particles. In the coated particle, the coating portion is disposed on at least a portion of the surface of the conductive portion and at least a portion of the surface of the insulating particle. In the coated particle, the coating portion is disposed on at least a portion of the surface of the conductive portion and at least a portion of the surface of the insulating particle. The coating portion may be a coating.

[0116] The coating portion does not have to be disposed between the conductive portion and the insulating particle. From the viewpoint of more effectively exerting the effects of the present invention, it is preferable that the coating portion is disposed in an area of ​​the surface of the conductive portion where the insulating particle is not disposed. In this case, the coating portion may or may not be disposed between the conductive portion and the insulating particle. The conductive portion and the insulating particle may be in direct contact without the coating portion interposed therebetween.

[0117] From the viewpoint of more effectively achieving the effects of the present invention, it is preferable that the coating portion coats the entire surface of the conductive particle with insulating particles, and from the viewpoint of more effectively achieving the effects of the present invention, it is preferable that the coating portion coats the surface of the conductive portion and the surface of the insulating particle.

[0118] The material of the covering portion includes a polymerizable monomer, and the polymerizable monomer includes a crosslinkable monomer. The material of the covering portion includes a polymerizable component, and the polymerizable component includes a crosslinkable monomer. The covering portion preferably includes a skeleton derived from a polymerizable monomer, and preferably includes a skeleton derived from a crosslinkable monomer. Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol Examples of suitable crosslinkable monomers include polyfunctional (meth)acrylate compounds such as 1,4-butanediol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane. The crosslinkable monomers may be used alone or in combination of two or more. From the viewpoints of further suppressing particle aggregation during the formation of the coating portion and satisfactorily coating the surfaces of the insulating particle-attached conductive particles, the crosslinkable monomer preferably contains divinylbenzene or (poly)ethylene glycol di(meth)acrylate, and more preferably contains divinylbenzene.

[0119] From the viewpoint of further suppressing particle aggregation when forming the coating portion and adequately coating the surface of the insulating particle-attached conductive particles, the molecular weight of the crosslinkable monomer is preferably 50 or more, more preferably 100 or more, and preferably 500 or less, more preferably 300 or less.

[0120] In the material of the coating portion, the content of the crosslinkable monomer in 100% by weight of the polymerizable monomer is 10.0% by weight or more. From the viewpoint of further suppressing particle aggregation when forming the coating portion and satisfactorily covering the surfaces of the insulating particle-attached conductive particles, the content of the crosslinkable monomer in 100% by weight of the polymerizable monomer is preferably 12% by weight or more, more preferably 15% by weight or more, and preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less.

[0121] The polymerizable monomer may include a non-crosslinkable monomer. The coating portion may include a skeleton derived from a non-crosslinkable monomer. Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; alkyl (meth)acrylate compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, and the like. Examples of suitable non-crosslinkable monomers include oxygen-containing (meth)acrylate compounds such as acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acid ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; and halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene. The non-crosslinkable monomers may be used alone or in combination of two or more. From the viewpoint of further suppressing particle aggregation during the formation of the coating portion and satisfactorily coating the surfaces of the insulating particle-attached conductive particles, it is preferred that the polymerizable monomer contains a non-crosslinkable monomer, and that the non-crosslinkable monomer contains styrene.

[0122] From the viewpoint of further suppressing particle aggregation when forming the coating portion and adequately coating the surface of the insulating particle-attached conductive particles, the molecular weight of the non-crosslinkable monomer is preferably 50 or more, more preferably 100 or more, and preferably 500 or less, more preferably 300 or less.

[0123] When the polymerizable monomer contains a non-crosslinkable monomer, the content of the non-crosslinkable monomer in 100% by weight of the polymerizable monomer is preferably 50% by weight or more, more preferably 70% by weight or more, even more preferably 75% by weight or more, and preferably 90% by weight or less, more preferably 85% by weight or less. When the content of the non-crosslinkable monomer is equal to or more than the above lower limit and equal to or less than the above upper limit, particle aggregation can be further suppressed when the coating portion is formed, and the surfaces of the insulating particle-attached conductive particles can be well coated.

[0124] Furthermore, the polymerizable monomer preferably contains a compound represented by the following formula (1): In formula (1), X1 represents a hydroxyl group, an alkoxy group, or an alkyl group having 1 to 12 carbon atoms, and X2 represents an organic group containing an unsaturated bond, the organic group containing an unsaturated bond containing a (meth)acryloyl group. When the material for the coating portion contains a compound represented by formula (1), aggregation of particles in a dispersion liquid during the formation of the coating portion can be further suppressed, and the surfaces of the insulating particle-attached conductive particles can be sufficiently coated. As a result, when electrodes are electrically connected using the coated particles, insulation reliability can be further effectively improved.

[0125]

[0126] In the above formula (1), X1 is preferably a hydroxyl group. That is, the compound represented by the above formula (1) is preferably a compound represented by the following formula (1A). In this case, the effects of the present invention can be more effectively exhibited.

[0127]

[0128] In the above formula (1A), X2 represents an organic group containing an unsaturated bond, and the organic group containing an unsaturated bond contains a (meth)acryloyl group.

[0129] Examples of the compound represented by the formula (1A) include acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol methacrylate, and acid phosphooxypolyoxypropylene glycol methacrylate. Only one type of compound represented by the formula (1A) may be used, or two or more types may be used in combination.

[0130] The compound represented by formula (1A) is preferably acid phosphooxyethyl methacrylate or acid phosphooxypolyoxyethylene glycol methacrylate, and more preferably acid phosphooxypolyoxyethylene glycol methacrylate, which further suppresses particle aggregation during the formation of the coating portion, thereby enabling the surfaces of the insulating particle-attached conductive particles to be well coated.

[0131] From the viewpoint of more effectively exerting the effects of the present invention, the thickness of the coating portion is preferably 10 nm or more, more preferably 30 nm or more, even more preferably 50 nm or more, and is preferably 500 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less.

[0132] The thickness of the coating portion can be measured by observing the cross section of the coated particle using, for example, a transmission electron microscope (TEM).

[0133] The ratio of the thickness of the coating portion to the particle diameter of the insulating particle is referred to as the ratio (thickness of coating portion / particle diameter of insulating particle). From the viewpoint of more effectively exerting the effects of the present invention, the ratio (thickness of coating portion / particle diameter of insulating particle) is preferably 1 / 20 or more, more preferably 1 / 10 or more, and is preferably 1 / 2 or less, more preferably 1 / 3 or less.

[0134] From the viewpoint of exerting the effects of the present invention more effectively, the area of ​​the portion covered by the coating portion (coverage by the coating portion) of the total surface area (100%) of the conductive particle with insulating particles is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and most preferably 100%. The coverage by the coating portion can be measured by the following method.

[0135] The conductive particles with insulating particles are observed from one direction using a scanning electron microscope (SEM), and the coverage is calculated from the total area of ​​the coated portion within the circle of the outer periphery of the surface of the conductive portion in the observed image, relative to the total area within the circle of the outer periphery of the surface of the conductive portion. The coverage by the coated portion is preferably calculated as an average coverage by observing 20 coated particles and averaging the measurement results for each coated particle.

[0136] The content of the coating moiety in 100% by weight of the coated particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and is preferably 10% by weight or less, more preferably 5.0% by weight or less, even more preferably 2.0% by weight or less, and particularly preferably 1.0% by weight or less. When the content of the coating moiety is equal to or more than the above lower limit and equal to or less than the above upper limit, aggregation of the coated particles can be more effectively suppressed.

[0137] (Method for manufacturing coated particles) The method for manufacturing coated particles according to the present invention includes a step of polymerizing the material of the coating portion in a dispersion liquid in which the conductive particles with insulating particles are dispersed in a dispersion medium, thereby forming coating portions on the surfaces of the conductive portions of the conductive particles and on the surfaces of the insulating particles, thereby obtaining coated particles.

[0138] Examples of the dispersion medium include solvents. Examples of the dispersion medium include water, methanol, ethanol, and 2-propanol. Only one type of dispersion medium may be used, or two or more types may be used in combination. From the viewpoint of further suppressing particle aggregation when forming the coating portion and satisfactorily coating the surfaces of the insulating particle-attached conductive particles, the dispersion medium is preferably water. After the coating portion is formed on the surfaces of the conductive portions of the insulating particle-attached conductive particles and on the surfaces of the insulating particles, the dispersion medium is removed as necessary.

[0139] In the method for producing the coated particles, the coating portion can be formed by polymerizing the material of the coating portion by a known method, such as a suspension polymerization method in the presence of a radical polymerization initiator, or a method in which a monomer is swelled and polymerized together with a radical polymerization initiator using non-crosslinked seed particles.

[0140] Furthermore, the method for producing coated particles according to the present invention preferably includes the steps of: arranging the conductive portion on the surface of the base particle to obtain a conductive particle; and arranging a plurality of insulating particles on the surface of the conductive portion of the conductive particle to obtain a conductive particle with insulating particles. In this case, when electrodes are electrically connected, the electrical conductivity and insulation reliability can be further effectively improved.

[0141] (Resin composition) The resin composition according to the present invention contains the coated particles described above and a binder resin. The coated particles are preferably used by being dispersed in a binder resin. The coated particles are preferably used by being dispersed in a binder resin as a resin composition. The resin composition is preferably a conductive material, more preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection between electrodes. The conductive material is preferably a conductive material for circuit connection. Since the resin composition and conductive material use the coated particles described above, when electrodes are electrically connected, the conduction reliability and insulation reliability can be further effectively improved.

[0142] The binder resin is not particularly limited. A known insulating resin is used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include a photocurable component and a thermosetting component. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent.

[0143] Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, elastomers, etc. The binder resins may be used alone or in combination of two or more.

[0144] Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, a hydrogenated product of styrene-butadiene-styrene block copolymer, and a hydrogenated product of styrene-isoprene-styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

[0145] In addition to the coated particles and the binder resin, the resin composition may contain various additives such as a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant.

[0146] The method for dispersing the coated particles in the binder resin can be a conventionally known dispersion method and is not particularly limited. Examples of the method for dispersing the coated particles in the binder resin include the following methods: A method in which the coated particles are added to the binder resin and then kneaded and dispersed using a planetary mixer or the like; A method in which the coated particles are uniformly dispersed in water or an organic dispersion medium using a homogenizer or the like, then added to the binder resin and then kneaded and dispersed using a planetary mixer or the like; A method in which the binder resin is diluted with water or an organic dispersion medium or the like, then the coated particles are added, and then kneaded and dispersed using a planetary mixer or the like.

[0147] The viscosity (η25) of the resin composition at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 400 Pa·s or less, more preferably 300 Pa·s or less. When the viscosity of the resin composition at 25°C is equal to or greater than the lower limit and equal to or less than the upper limit, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved. The viscosity (η25) can be appropriately adjusted by the types and amounts of the blended components.

[0148] The viscosity (η25) can be measured, for example, using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) under conditions of 25° C. and 5 rpm.

[0149] When the resin composition according to the present invention is a conductive material, the conductive material can be used as a conductive paste, a conductive film, or the like. When the conductive material is a conductive film, a film not containing conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

[0150] The content of the binder resin in 100% by weight of the resin composition is preferably 10% by weight or more, more preferably 30% by weight or more, even more preferably 50% by weight or more, particularly preferably 70% by weight or more, and is preferably 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target members connected by the resin composition can be further improved.

[0151] The content of the coated particles in 100% by weight of the resin composition is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and is preferably 80% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the coated particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the electrical conductivity reliability and the insulation reliability between electrodes can be further improved.

[0152] (Connection structure) A connection structure according to the present invention comprises a first connection-target member having a first electrode on its surface, a second connection-target member having a second electrode on its surface, and a connection portion connecting the first connection-target member and the second connection-target member. In the connection structure according to the present invention, the material of the connection portion contains the coated particles described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles.

[0153] The connection structure can be obtained through a process of disposing the coated particles between the first and second connection target members and a process of electrically connecting the first and second connection target members by thermocompression bonding. During the thermocompression bonding, it is preferable that the coating and the insulating particles are detached from the coated particles. Alternatively, the resin composition may be disposed in place of the coated particles.

[0154] FIG. 4 is a cross-sectional view that schematically shows a connection structure using coated particles according to the first embodiment of the present invention.

[0155] The connection structure 81 shown in Figure 4 includes a first connection target member 82, a second connection target member 83, and a connection portion 84 connecting the first connection target member 82 and the second connection target member 83. The material of the connection portion 84 includes coated particles 1. The connection portion 84 may be formed from a resin composition including the coated particles 1. The connection portion 84 is preferably formed by curing a resin composition including a plurality of coated particles 1. Note that in Figure 4, the coated particles 1 are shown schematically for ease of illustration. Instead of the coated particles 1, coated particles 1A or coated particles 1B may be used.

[0156] The first connection target member 82 has a plurality of first electrodes 82a on its surface (upper surface). The second connection target member 83 has a plurality of second electrodes 83a on its surface (lower surface). The first electrodes 82a and the second electrodes 83a are electrically connected by one or more conductive particles 11 (omitted in FIG. 4 ) in the coated particles 1. Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive portions 22 (omitted in FIG. 4 ) in the conductive particles 11 (omitted in FIG. 4 ).

[0157] The method for manufacturing the connection structure is not particularly limited. One example of a method for manufacturing a connection structure includes placing the coated particles or the resin composition between a first connection target member and a second connection target member, obtaining a laminate, and then heating and pressurizing the laminate. The pressure of the thermocompression bonding is preferably 40 MPa or more, more preferably 60 MPa or more, and preferably 90 MPa or less, more preferably 70 MPa or less. The temperature (heating temperature) of the thermocompression bonding is preferably 80°C or more, more preferably 100°C or more, and preferably 140°C or less, more preferably 120°C or less. When the pressure and temperature of the thermocompression bonding are above the lower limit and below the upper limit, the coating and the insulating particles can be easily detached from the surface of the coated particles during conductive connection, thereby further improving the reliability of electrical conduction between electrodes.

[0158] When the laminate is heated and pressurized, the coating portion and the insulating particles present between the conductive particles and the first and second electrodes can be removed. For example, when the laminate is heated and pressurized, the insulating particles present between the conductive particles and the first and second electrodes are easily detached from the surface of the insulating particle-attached conductive particles. Note that when the laminate is heated and pressurized, some of the insulating particles may detach from the surface of the insulating particle-attached conductive particles, partially exposing the surface of the conductive portion. The exposed surface of the conductive portion may come into contact with the first and second electrodes, thereby electrically connecting the first and second electrodes via the conductive particles.

[0159] The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible boards, glass epoxy boards, and glass boards. The first and second connection target members are preferably electronic components.

[0160] Examples of the electrodes provided on the connection target members include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target members are flexible printed circuit boards, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes, or copper electrodes. When the connection target members are glass substrates, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, or tungsten electrodes. When the electrodes are aluminum electrodes, they may be formed solely from aluminum, or may be electrodes in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

[0161] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0162] (Example 1) (1) Preparation of conductive particles with insulating particles Conductive particles (average particle diameter 3.0 μm, conductive portion thickness 0.15 μm) having a conductive portion in which a nickel plating layer is formed on the surface of a divinylbenzene resin particle (base particle) were prepared.

[0163] Composition A was prepared in a 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way stopcock, a condenser, and a temperature probe. Composition A contained 97 parts by weight of styrene, 3 parts by weight of divinylbenzene, 0.5 parts by weight of acid phosphooxy polyoxyethylene glycol methacrylate, and 0.1 parts by weight of 2,2'-azobis{2-[N-(2-carboxyethyl)amidino]propane}. Composition A was then weighed into distilled water to give a solids content of 10% by weight, stirred at 200 rpm, and polymerized for 24 hours at 60°C under a nitrogen atmosphere. After completion of the reaction, the mixture was freeze-dried to obtain insulating particles (divinylbenzene-styrene copolymer, average particle size 300 nm). These particles were then dispersed in 30 mL of pure water under ultrasonic irradiation to obtain a 10% by weight dispersion of insulating particles.

[0164] 10 g of the conductive particles were dispersed in 500 mL of distilled water, 1 g of the insulating particle dispersion was added, and the mixture was stirred at room temperature for 8 hours. The mixture was filtered through a 10 μm mesh filter, washed with methanol, and then dried to obtain conductive particles with insulating particles.

[0165] (2) Preparation of Coated Particles 50 g of the resulting conductive particles with insulating particles was dispersed in 500 ml of distilled water under ultrasonic irradiation to obtain a 10 wt % dispersion of conductive particles with insulating particles. To the resulting dispersion, 0.88 g (88 parts by weight) of styrene, 0.1 g (10 parts by weight) of divinylbenzene, 0.01 g (1 part by weight) of acid phosphooxy polyoxyethylene glycol methacrylate, and 0.01 g (1 part by weight) of 2,2'-azobis{2-[N-(2-carboxyethyl)amidino]propane} were added. The mixture was then stirred at 200 rpm and polymerized for 24 hours at 60°C under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered through a 10 μm mesh filter, washed with methanol, and dried to obtain coated particles in which the surfaces of conductive particles with insulating particles were coated with a coating portion.

[0166] (3) Preparation of Resin Composition (Anisotropic Conductive Paste) 7 parts by weight of the obtained coated particles, 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, 30 parts by weight of phenol novolac type epoxy resin, and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.) were blended, and the mixture was degassed and stirred for 3 minutes to obtain a resin composition (anisotropic conductive paste).

[0167] (4) Fabrication of Connection Structure A transparent glass substrate was prepared, on the top surface of which was formed an IZO electrode pattern (first electrode, Vickers hardness of the metal on the surface of the electrode) with an L / S of 10 μm / 10 μm. A semiconductor chip was also prepared, on the bottom surface of which was formed an Au electrode pattern (second electrode, Vickers hardness of the metal on the surface of the electrode) with an L / S of 10 μm / 10 μm.

[0168] The resulting resin composition (anisotropic conductive paste) was applied to the transparent glass substrate to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer with the electrodes facing each other. Then, a pressure heating head was placed on the top surface of the semiconductor chip while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer was 100°C, and a pressure of 60 MPa was applied to harden the anisotropic conductive paste layer at 100°C, thereby obtaining a connection structure.

[0169] Examples 2 to 10 and Comparative Example 2 Covered particles, resin compositions, and connection structures were obtained in the same manner as in Example 1, except that the configuration of the covered particles was changed as shown in Tables 1 to 3 below.

[0170] Comparative Example 1 Conductive particles with insulating particles were obtained in the same manner as in Example 1, except that the composition of the insulating particles was changed as shown in the following Table 3. A resin composition and a connection structure were obtained in the same manner as in Example 1, except that the obtained conductive particles with insulating particles were used instead of the coated particles.

[0171] (Evaluation) (1) Ratio (Thickness of coating portion / Particle diameter of insulating particle) The thickness of the coating portion and the particle diameter of the insulating particle were measured for the obtained coated particles using the method described above, and the ratio of the thickness of the coating portion to the particle diameter of the insulating particle (thickness of coating portion / particle diameter of insulating particle) was calculated.

[0172] (2) Detachment-preventing ability of insulating particles before conductive connection The residual rate of insulating particles was determined by the following method. A dispersion liquid prepared by dispersing 0.1 g of conductive particles with insulating particles in 5 g of toluene was shaken and stirred for 1 minute using a shaker. The coverage rate of insulating particles before and after the test was measured, and the residual rate (%) = (coverage rate after test / coverage rate before test) × 100 was calculated. The detachment-preventing ability of insulating particles before conductive connection was evaluated according to the following criteria.

[0173] [Criteria for evaluation of insulating particle detachment suppression] ○○○: The remaining rate of insulating particles is 100%. ○○: The remaining rate of insulating particles is 80% or more and less than 100%. ○: The remaining rate of insulating particles is 70% or more and less than 80%. ×: The remaining rate of insulating particles is less than 70%.

[0174] (3) Particle aggregation suppression in resin composition The obtained resin composition was applied to a transparent glass substrate to have a size of 0.5 mm length x 0.5 mm width x 30 μm thickness, and the number of particles (conductive particles with insulating particles and coated particles) that had aggregated in the resin composition was measured using an optical microscope (Keyence Corporation, "VH-Z450"). The particle aggregation suppression in the resin composition was evaluated according to the following criteria.

[0175] [Criteria for evaluating particle aggregation suppression in resin composition] ○○○: The number of aggregated particles is 4 or less. ○○: The number of aggregated particles is 5 to 6. ○: The number of aggregated particles is 7 to 9. ×: The number of aggregated particles is 10 or more.

[0176] (4) Conduction reliability (between upper and lower electrodes) The connection resistance between the upper and lower electrodes of the 20 connection structures obtained was measured using a four-terminal method. Note that, based on the relationship voltage = current × resistance, the connection resistance can be determined by measuring the voltage when a constant current is passed. The conduction reliability was evaluated according to the following criteria.

[0177] [Criteria for Continuity Reliability] ○○○: Connection resistance is greater than 1.5Ω and less than 2.0Ω ○○: Connection resistance is greater than 2.0Ω and less than 5.0Ω ○: Connection resistance is greater than 5.0Ω and less than 10Ω ×: Connection resistance is greater than 10Ω

[0178] (5) Insulation Reliability (Between Laterally Adjacent Electrodes) The 20 connection structures obtained were evaluated for the presence or absence of leakage between adjacent electrodes by measuring the resistance value with a tester. The insulation reliability was evaluated according to the following criteria.

[0179] [Insulation reliability evaluation criteria] ○○○: Resistance value is 10 ８ The number of connection structures with a resistance of 10Ω or more is 20. ８ The number of connection structures having a resistance of 10Ω or more is 18 or more and 19 or less. ８ The number of connection structures of Ω or more is 15 or more and 17 or less. ×: The resistance value is 10 ８ The number of connection structures of Ω or more is 14 or less

[0180] The compositions of the coated particles and conductive particles with insulating particles and the results are shown in Tables 1 to 3 below.

[0181]

[0182]

[0183]

[0184] REFERENCE SIGNS LIST 1, 1A, 1B... Coated particles 2, 2A, 2B... Conductive particles with insulating particles 3, 3A, 3B... Coated portion 11, 11A, 11B... Conductive particles 11Ba... Protrusions 12, 12A, 12B... Insulating particles 21, 21A, 21B... Base particles 22, 22A, 22B... Conductive portion 22AA... First conductive portion 22AB... Second conductive portion 23B... Core material 81... Connection structure 82... First member to be connected 82a... First electrode 83... Second member to be connected 83a... Second electrode 84... Connection portion

Claims

1. The conductive particles having insulating particles and a coating portion are provided, the conductive particle with insulating particles has a conductive particle and a plurality of insulating particles arranged on a surface of the conductive particle, The conductive particle has a base particle and a conductive portion disposed on a surface of the base particle, the coating portion covers at least a part of a surface of the conductive portion and at least a part of a surface of the insulating particle, the material of the covering portion contains a polymerizable monomer, the polymerizable monomer includes a crosslinkable monomer, The coated particles have a crosslinkable monomer content of 10.0% by weight or more based on 100% by weight of the polymerizable monomer.

2. The coated particle of claim 1 , wherein the crosslinkable monomer comprises divinylbenzene.

3. The coated particle according to claim 1 , wherein the polymerizable monomer comprises a compound represented by the following formula (1): 【Chemistry 1】 In the formula (1), X1 represents a hydroxyl group, an alkoxy group, or an alkyl group having 1 to 12 carbon atoms, and X2 represents an organic group containing an unsaturated bond, and the organic group containing an unsaturated bond contains a (meth)acryloyl group.

4. The coated particle described in claim 2, wherein the polymerizable monomer comprises a compound represented by the following formula (1): 【Chemistry 2】 In the formula (1), X1 represents a hydroxyl group, an alkoxy group, or an alkyl group having 1 to 12 carbon atoms, and X2 represents an organic group containing an unsaturated bond, and the organic group containing an unsaturated bond contains a (meth)acryloyl group.

5. the polymerizable monomer includes a non-crosslinkable monomer, The coated particle according to any one of claims 1 to 4, wherein the non-crosslinkable monomer comprises styrene.

6. The coated particles according to any one of claims 1 to 4, wherein the insulating particles are resin particles.

7. The coated particle of any one of claims 1 to 4, wherein the insulating particle comprises a polymer.

8. 5. The coated particle according to claim 1, wherein a ratio of a thickness of the coating portion to a particle diameter of the insulating particle is 1 / 2 or less.

9. 5. The coated particle according to claim 1, wherein an area of ​​the portion covered by the coating portion is 80% or more of a total surface area (100%) of the conductive particle with insulating particles.

10. The polymerizable monomer comprises a non-crosslinkable monomer, The coated particle according to any one of claims 1 to 4, wherein the content of the crosslinkable monomer is 10.0% by weight or more and 50% by weight or less, and the content of the non-crosslinkable monomer is 50% by weight or more and 90.0% by weight or less, in 100% by weight of the polymerizable monomer.

11. A method for producing the coated particles according to any one of claims 1 to 4, comprising the steps of: The material of the coating portion is polymerized in a dispersion liquid in which the conductive particles with insulating particles are dispersed in a dispersion medium, A method for producing coated particles, comprising a step of forming the coating portion on a surface of the conductive portion of the conductive particle and on a surface of the insulating particle to obtain coated particles.

12. A step of arranging the conductive portion on a surface of the base particle to obtain a conductive particle; and arranging a plurality of the insulating particles on the surface of the conductive portion of the conductive particle to obtain a conductive particle with insulating particles.

13. A resin composition comprising the coated particles according to any one of claims 1 to 4 and a binder resin.

14. The resin composition according to claim 13, wherein the binder resin comprises an epoxy resin.

15. a first connection target member having a first electrode on a surface thereof; a second connection target member having a second electrode on a surface thereof; a connection portion that connects the first connection target member and the second connection target member, The material of the connection portion contains the coated particles according to any one of claims 1 to 4, A connection structure, wherein the first electrode and the second electrode are electrically connected by the conductive particles.

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