Conductive particles, conductive materials and connection structures

Abstract

Provided are conductive particles which enable effective removal of oxide films on the surfaces of the conductive particles and the surfaces of electrodes and effective improvement in conduction reliability at the time of electrical connection between the electrodes.　Conductive particles according to the present invention each comprise: a conductive particle body; a plurality of flux-containing particles; and a flux film. The conductive particle body includes a base material particle, and a conductive part disposed outside the base material particle. The flux-containing particles are arranged outside the conductive particle body, and the flux film is disposed outside the conductive particle body.

Description

[Technical Field]

[0001] The present invention relates to conductive particles using a flux, and also to a conductive material and a connection structure using the conductive particles. [Background technology]

[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] When electrically connecting electrodes of a flexible printed circuit board and electrodes of a glass epoxy board using the anisotropic conductive material, for example, an anisotropic conductive material containing conductive particles is placed on the glass epoxy board. Next, a flexible printed circuit board is laminated, and the resulting laminate is heated and pressurized. This hardens the anisotropic conductive material, electrically connecting the electrodes via the conductive particles and obtaining a connection structure.

[0005] In the conductive particles and the anisotropic conductive material, an oxide film may form on the surface of the conductive portion of the conductive particles depending on storage conditions before conductive connection, etc. Furthermore, an oxide film may also form on the surface of the electrodes to be conductively connected. The presence of this oxide film increases the connection resistance and reduces the electrical reliability of the conductively connected connection structure. To remove the oxide film on the surface of the conductive particles and electrodes, a flux may be blended into the anisotropic conductive material or placed on the surface of the conductive particles.

[0006] Patent Document 1 listed below discloses a conductive adhesive composition containing (A) conductive particles containing a metal having a melting point of 220°C or less, (B) a thermosetting resin, and (C) a flux activator, where the average particle size of the flux activator (C) is 15 μm or less.

[0007] Patent Document 2 below discloses an anisotropic conductive film having metal particles in an insulating film. In this anisotropic conductive film, the metal particles are regularly arranged in a plan view, and flux is arranged so as to be in contact with or in proximity to at least one of the ends of the metal particles on the front surface side of the anisotropic conductive film or the back surface side of the anisotropic conductive film. In the metal particles of Patent Document 2, flux is in contact with or in proximity to the ends of the metal particles. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2012 / 102077A1 [Patent Document 2] WO2016 / 114160A1 Summary of the Invention [Problem to be solved by the invention]

[0009] When a conductive connection is made using a conductive material containing conductive particles, the upper electrodes are electrically connected to the lower electrodes, and the conductive connection is made. The conductive particles are preferably disposed between the upper and lower electrodes, but are preferably not disposed between adjacent horizontal electrodes. The adjacent horizontal electrodes are preferably not electrically connected.

[0010] In conventional conductive materials such as those described in Patent Documents 1 and 2, the entire flux is quickly activated on the surface of the conductive particles or electrodes due to heating and pressure during conductive connection, and the flux's activity is easily lost early. As a result, the oxide film on the surface of the conductive particles may not be sufficiently removed. As a result, the connection resistance between the upper and lower electrodes to be connected may increase, and the conductivity reliability may decrease.

[0011] An object of the present invention is to provide conductive particles that can effectively remove oxide films from the surfaces of the conductive particles and the surfaces of electrodes, and that can effectively improve the reliability of electrical conduction when electrodes are electrically connected. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles. [Means for solving the problem]

[0012] According to a broad aspect of the present invention, there is provided a conductive particle comprising a conductive particle body, a plurality of flux-containing particles, and a flux film, wherein the conductive particle body comprises a base particle and a conductive portion disposed on the outside of the base particle, the flux-containing particles are disposed on the outside of the conductive particle body, and the flux film is disposed on the outside of the conductive particle body.

[0013] In a specific aspect of the conductive particle according to the present invention, the flux-containing particle includes a particle body and flux, and the particle body is a resin particle.

[0014] In a specific aspect of the conductive particles according to the present invention, the material of the resin particles contains a polymerizable monomer, and a homopolymer of the polymerizable monomer has a glass transition temperature of 80° C. or higher.

[0015] In a specific aspect of the conductive particle according to the present invention, the flux-containing particle does not have a breaking point in a compression-displacement curve when a maximum test load of 3.3 mN is applied to the flux-containing particle for 10 seconds.

[0016] In a specific aspect of the conductive particle according to the present invention, the conductive portion contains tin.

[0017] In a specific aspect of the conductive particles according to the present invention, the ratio of the particle size of the conductive particles to the particle size of the flux-containing particles is 3 or more and 500 or less.

[0018] In a specific aspect of the conductive particles according to the present invention, the conductive particles have a particle diameter of 1 μm or more and 50 μm or less.

[0019] In a specific aspect of the conductive particles according to the present invention, when a conductive particle-containing liquid in which 3 parts by weight of the conductive particles are added to 100 parts by weight of ethanol is subjected to ultrasonic treatment at 20°C and 40 kHz for 5 minutes, the residual rate of the flux-containing particles calculated by the following formula (1) is 99% or less.

[0020] Residual rate of flux-containing particles (%) = (coverage rate of flux-containing particles after ultrasonic treatment / coverage rate of flux-containing particles before ultrasonic treatment) × 100 Equation (1)

[0021] According to a broad aspect of the present invention, there is provided a conductive material including the conductive particles described above and a binder resin.

[0022] 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 conductive particles, and the first electrode and the second electrode are electrically connected by the conductive particle body. [Effects of the Invention]

[0023] The conductive particle according to the present invention comprises a conductive particle body, a plurality of flux-containing particles, and a flux film. In the conductive particle according to the present invention, the conductive particle body comprises a base particle and a conductive portion disposed on the outside of the base particle. In the conductive particle according to the present invention, the flux-containing particles are disposed on the outside of the conductive particle body, and the flux film is disposed on the outside of the conductive particle body. Because the conductive particle according to the present invention has the above configuration, it is possible to effectively remove oxide films on the surfaces of the conductive particles and the electrodes, and to effectively improve the reliability of electrical connection when electrodes are electrically connected. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view that schematically shows a connection structure using conductive particles according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described in detail below.

[0026] (Conductive particles) The conductive particle according to the present invention comprises a conductive particle body, a plurality of flux-containing particles, and a flux film. In the conductive particle according to the present invention, the conductive particle body comprises a base particle and a conductive portion disposed on the outside of the base particle. In the conductive particle according to the present invention, the flux-containing particles are disposed on the outside of the conductive particle body, and the flux film is disposed on the outside of the conductive particle body.

[0027] The conductive particles according to the present invention have the above-mentioned configuration, and therefore can effectively remove the oxide film on the surface of the conductive particles (specifically, the surface of the conductive portion of the conductive particles) and the surface of the electrodes, and can effectively improve the reliability of conductivity when the electrodes are electrically connected.

[0028] In conventional conductive particles and conductive materials, the entire flux component is quickly activated on the surface of the conductive particles or electrodes due to heat, pressure, etc. during conductive connection, and the flux activity is easily lost early. As a result, the oxide film on the surface of the conductive particles may not be sufficiently removed. As a result, the connection resistance between the upper and lower electrodes to be connected may increase and the conductivity reliability may decrease.

[0029] After extensive research, the inventors have found that the above-mentioned problems can be solved by using conductive particles having a specific configuration. With the conductive particles according to the present invention, the oxide films on the surfaces of the conductive particles and the electrodes can be effectively removed by the flux film during the initial stage of conductive connection, such as by heating and pressurizing during conductive connection. Furthermore, with the conductive particles according to the present invention, the flux gradually leaks from the flux-containing particles due to heating and pressurizing during conductive connection, effectively removing the oxide films on the surfaces of the conductive particles and the electrodes. Furthermore, with the present invention, the flux gradually leaks from the flux-containing particles even after conductive connection, thereby removing the oxide films on the surfaces of the conductive particles and the electrodes. As a result, the reliability of electrical continuity between the upper and lower electrodes to be connected can be effectively improved.

[0030] Furthermore, in the conductive particles according to the present invention, when a conductive connection is made, a vertical mounting stress is applied to the conductive particles, which causes the flux-containing particles to easily detach from the upper and lower surfaces of the conductive particle body. This makes it difficult for the flux-containing particles to remain between the conductive particle body and the electrode, thereby effectively improving the reliability of electrical connection between the upper and lower electrodes that should be connected. Furthermore, when a conductive connection is made, a horizontal stress is not applied to the conductive particles, which makes it difficult for the flux-containing particles to detach from the horizontal surfaces of the conductive particle body. As a result, the conductive particles according to the present invention effectively improve the reliability of insulation between horizontally adjacent electrodes that should not be connected.

[0031] Therefore, in the present invention, when the electrodes are electrically connected, the reliability of conduction and insulation can be effectively improved.

[0032] Furthermore, since the present invention has the above-mentioned configuration, the amount of flux can be reduced compared to conventional conductive particles and conductive materials. In the present invention, a small amount of flux can effectively remove oxide films on the surfaces of the conductive particles and the electrodes, and when electrodes are electrically connected, the reliability of conductivity can be effectively improved.

[0033] The conductive particles are dispersed in a binder resin and are suitably used to obtain a conductive material.

[0034] 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. For example, the thickness of the flux film may be quite thin.

[0035] FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention.

[0036] The conductive particle 1 shown in FIG. 1 includes a conductive particle body 11, a plurality of flux-containing particles 12, and a flux film 13. In the conductive particle 1, the conductive particle body 11 includes a base particle 21 and a conductive portion 22 arranged outside the base particle 21. In the conductive particle 1, the flux-containing particle 12 is arranged outside the conductive particle body 11. In the conductive particle 1, the flux film 13 is arranged outside the conductive particle body 11. The conductive portion 22 is arranged on the surface of the base particle 21 and in contact with the base particle 21. In the conductive particle 1, the flux-containing particle 12 is arranged on the surface of the conductive particle body 11 (conductive portion 22) and in contact with the conductive particle body 11 (conductive portion 22). In the conductive particle 1, the flux film 13 is arranged on the surface of the conductive particle body 11 (conductive portion 22) and in contact with the conductive particle body 11 (conductive portion 22).

[0037] The conductive portion 22 covers the surface of the base particle 21. The conductive particle body 11 is a coated particle in which the surface of the base particle 21 is coated with the conductive portion 22. The conductive particle body 11 has the conductive portion 22 on the surface.

[0038] In the conductive 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.

[0039] In the conductive particle 1, the flux film 13 covers the surface of the conductive particle body 11 (the surface of the conductive portion 22) and the surface of the flux-containing particle 12.

[0040] The conductive particle 1 can be obtained, for example, by forming the flux film 13 by a flux treatment using a conductive particle body 11 to which flux-containing particles 12 are attached before the flux film 13 is disposed. In addition, conductive particles 1B and conductive particles 1C, which will be described later, can also be obtained in the same manner as the conductive particle 1.

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

[0042] The conductive particle 1A shown in FIG. 2 includes a conductive particle body 11A, a plurality of flux-containing particles 12A, and a flux film 13A. In the conductive particle 1A, the conductive particle body 11A includes a base particle 21A and a conductive portion 22A arranged on the outside of the base particle 21A. In the conductive particle 1A, the flux-containing particle 12A is arranged on the outside of the conductive particle body 11A. In the conductive particle 1A, the flux film 13A is arranged on the outside of the conductive particle body 11A. The conductive portion 22A is arranged on the surface of the base particle 21A and is in contact with the base particle 21A. In the conductive particle 1A, the flux-containing particle 12A is arranged on the surface of the conductive particle body 11A (conductive portion 22A) via the flux film 13A. In the conductive particle 1A, the flux-containing particle 12A is arranged on the surface of the flux film 13A. The flux-containing particle 12A is not in contact with the conductive particle body 11A but is in contact with the flux film 13A. In the conductive particle 1A, the flux film 13A is disposed on the surface of the conductive particle body 11A (conductive portion 22A) and is in contact with the conductive particle body 11A (conductive portion 22A). In the conductive particle 1A, the flux film 13A covers only the surface of the conductive particle body 11A (surface of the conductive portion 22A). In the conductive particle 1A, the flux film 13A does not cover the surface of the flux-containing particle 12A. In the conductive particle 1A, the flux film 13A is disposed between the conductive particle body 11A and the flux-containing particle 12A.

[0043] The conductive particle 1 and the conductive particle 1A differ in the configuration of the flux-containing particle and the flux film. The flux film may or may not be present between the flux-containing particle and the conductive portion. The flux film may or may not cover the surface of the flux-containing particle.

[0044] The conductive particle 1A can be obtained, for example, by using a conductive particle body 11A before the flux-containing particle 12A and the flux film 13A are arranged, forming a flux film 13A by flux processing, and then attaching the flux-containing particle 12A to the flux film 13A.

[0045] FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention.

[0046] The conductive particle 1B shown in FIG. 3 includes a conductive particle body 11B, a plurality of flux-containing particles 12B, and a flux film 13B. In the conductive particle 1B, the conductive particle body 11B includes a base particle 21B and a conductive portion 22B arranged outside the base particle 21B. In the conductive particle 1B, the flux-containing particle 12B is arranged outside the conductive particle body 11B. In the conductive particle 1B, the flux film 13B is arranged outside the conductive particle body 11B. The conductive portion 22B is arranged on the surface of the base particle 21B and is in contact with the base particle 21B. In the conductive particle 1B, the flux-containing particle 12B is arranged on the surface of the conductive particle body 11B (conductive portion 22B) and is in contact with the conductive portion 22B. In the conductive particle 1B, the flux film 13B is disposed on the surface of the conductive particle body 11B (conductive portion 22B) and is in contact with the conductive particle body 11B (conductive portion 22B).

[0047] In the conductive particle 1B, the conductive portion 22B is a two-layer conductive layer. The conductive portion 22B includes a first conductive portion 22BA and a second conductive portion 22BB. In the conductive portion 22B, the first conductive portion 22BA is disposed on the outer side of the base particle 21B, and the second conductive portion 22BB is disposed on the outer side of the first conductive portion 22BA. In the conductive portion 22B, the first conductive portion 22BA is layered on the surface of the base particle 21B, and the second conductive portion 22BB is layered on the surface of the first conductive portion 22BA.

[0048] The conductive particle 1 and the conductive particle 1B have different configurations of the conductive part. The conductive part may be a single conductive layer or multiple conductive layers.

[0049] FIG. 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention.

[0050] The conductive particle 1C shown in FIG. 4 includes a conductive particle body 11C, a plurality of flux-containing particles 12C, and a flux film 13C. In the conductive particle 1C, the conductive particle body 11C includes a base particle 21C, a conductive portion 22C arranged on the outside of the base particle 21C, and a plurality of core materials 23C arranged on the outside of the base particle 21C. The conductive portion 22C coats the base particle 21C and the core material 23C. Because the conductive portion 22C coats the core material 23C, the conductive particle body 11C has a plurality of protrusions 11Ca on its surface. The surface of the conductive portion 22C is raised by the core material 23C, forming a plurality of protrusions 11Ca.

[0051] Conductive particle 1 and conductive particle 1C differ in whether a core material is used or not, and in whether protrusions are present on the conductive particle body. The conductive particle body may or may not have protrusions on the surface.

[0052] Other details of the conductive particles will be described below.

[0053] 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.

[0054] The particle diameter of the conductive particles is preferably 1 μm or more, more preferably 10 μm or more, and preferably 50 μm or less, more preferably 40 μm or less. When the particle diameter of the conductive particles is above the lower limit and below the upper limit, when electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and agglomerated conductive particles are less likely to form when forming a conductive portion. In addition, the gap between the electrodes connected via the conductive particle body is not too large, and the conductive portion is less likely to peel off from the surface of the base particle.

[0055] The particle diameter of the conductive particle body is preferably 1 μm or more, more preferably 10 μm or more, and preferably 50 μm or less, more preferably 40 μm or less. If the particle diameter of the conductive particle body is above the above lower limit and below the above upper limit, when electrodes are connected using the conductive particles, the contact area between the conductive particle body and the electrode is sufficiently large, and aggregated conductive particle bodies are unlikely to form when forming the conductive part. Furthermore, the gap between the electrodes connected via the conductive particle body is not too large, and the conductive part is unlikely to peel off from the surface of the base particle.

[0056] The particle diameters of the conductive particles and the conductive particle bodies are preferably average particle diameters, and the average particle diameter indicates a number-average particle diameter. The particle diameters of the conductive particles and the conductive particle bodies can be determined, for example, by observing 50 random conductive particles with an electron microscope or an optical microscope and calculating the average particle diameter of each conductive particle and each conductive particle body, or by performing laser diffraction particle size distribution measurement.

[0057] From the viewpoint of more effectively improving the reliability of conduction between electrodes, the coefficient of variation (CV value) of particle diameters of the conductive particles and the conductive particle bodies 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 ρ: Standard deviation of the particle diameter of the conductive particles or the conductive particle body Dn: average particle diameter of conductive particles or conductive particle bodies

[0060] The shapes of the conductive particles and the conductive particle bodies are not particularly limited, and may be spherical, may be a shape other than spherical, or may be flat or the like.

[0061] <Base material 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.

[0062] 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.

[0063] 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.

[0064] 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 2-hydroxyethyl (meth)acrylate, 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.

[0065] 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. To ensure that the flux-containing particles maintain their shape 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.

[0066] 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.

[0067] When the base particles are inorganic particles other than metals or organic-inorganic hybrid particles, examples of inorganic materials for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black. Preferably, the inorganic material is not metal. Examples of particles formed from silica include particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, followed by firing as necessary. Examples of organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

[0068] 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.

[0069] Examples of the material for the organic core include the materials for the resin particles described above.

[0070] 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.

[0071] 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.

[0072] The particle diameter of the base particle is preferably 0.5 μm or more, more preferably 9.5 μm or more, and preferably 49.95 μm or less, more preferably 39.95 μm or less. When the particle diameter of the base particle is equal to or greater than the lower limit and equal to or less than the upper limit, the distance between the electrodes becomes small, and even if the thickness of the conductive part is increased, small conductive particles can be obtained. Furthermore, when the conductive part is formed on the surface of the base particle, aggregation is unlikely to occur, and aggregated conductive particles are unlikely to be formed.

[0073] 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.

[0074] The particle diameter of the base particles is preferably an average particle diameter, and the average particle diameter indicates a number-average particle diameter. The particle diameter of the base particles is determined using a particle size distribution measuring device or the like. The particle diameter 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 diameter of the base particles in the conductive particles, for example, it can be measured as follows.

[0075] The conductive particles were added to Kulzer's Technovit 4000 so that the content was 30 wt % and dispersed to prepare a resin embedding body for testing containing conductive particles. An ion milling machine (Hitachi High-Technologies Corporation's IM4000) was used to cut out a cross section of the conductive particles so that it passed through the center of the conductive particles dispersed in the resin embedding body for testing. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 25,000x, 50 conductive particles were randomly selected and the substrate particles of each conductive particle were observed. The particle diameter of the substrate particles in each conductive particle was measured, and the arithmetic average was calculated to determine the particle diameter of the substrate particles.

[0076] <Core substance and protrusions> The conductive particle body preferably has protrusions on the outer surface of the conductive portion. It is preferable that there are multiple protrusions. Generally, an oxide film is often formed on the surface of an electrode that contacts the conductive particle body. When a conductive particle body having protrusions on the surface of the conductive portion is used, the protrusions can effectively remove the oxide film during conductive connection. This ensures more reliable contact between the electrode and the conductive portion, sufficiently increasing the contact area between the conductive particle body and the electrode, and more effectively reducing the connection resistance. Furthermore, when the conductive particles are dispersed in a binder and used as a conductive material, the protrusions on the conductive particle body can more effectively remove the binder between the conductive particle body and the electrode. This allows the contact area between the conductive particle body and the electrode to be sufficiently increased, and more effectively reducing the connection resistance. The conductive particle body preferably has a core material on the outside of the base particle. The conductive particle body preferably has a core material on the surface of the base particle.

[0077] Methods for forming protrusions on the surface of the conductive particle body include the following: 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. A method in which a conductive portion is formed on the surface of a base particle by electroless plating, and then a core substance is attached, and then a conductive portion is formed by further electroless plating. A method in which a conductive portion is formed on the surface of a base particle by electroless plating, and then protrusions having the same composition as the conductive portion are formed by further electroless plating.

[0078] 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.

[0079] The conductive particle may have a first conductive portion on the outside of the base particle and a second conductive portion on the outside of the first conductive portion. In this case, 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. The minor axis of the core material is preferably 0.05 μm or more and preferably 0.5 μm or less. The conductive particle is preferably obtained by forming a first conductive portion on the surface of a base particle, then attaching a core material to the surface of the first conductive portion, and then forming a second conductive portion on the surfaces of the first conductive portion and the core material.

[0080] The material constituting the core material includes conductive materials and non-conductive materials. The conductive material includes, for example, conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. The conductive polymer includes polyacetylene. The non-conductive material includes silica, alumina, and zirconia. From the viewpoint of improving the electrical conductivity reliability, the material constituting the core material is preferably a metal. The core material is preferably a metal particle.

[0081] 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. Among 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).

[0082] 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 particulate masses, aggregates formed by aggregating multiple microparticles, and amorphous masses.

[0083] 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 greater than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes can be effectively reduced.

[0084] <Conductive part> In the present invention, the conductive particles have conductive portions on their surfaces, and the conductive portions are disposed on the surfaces of the base particles.

[0085] The conductive portion preferably contains a metal. The metal constituting the conductive portion is not particularly limited. Examples of the metal include tin, gold, silver, copper, 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. The metal may be used alone or in combination of two or more.

[0086] From the viewpoint of further improving the conduction reliability, the conductive portion preferably contains tin, nickel, copper or gold, more preferably contains tin or nickel, and further preferably contains tin.

[0087] From the viewpoint of further improving the conduction reliability, it is preferable that the conductive portion contains tin as the main metal. From the viewpoint of further improving the conduction reliability, it is preferable that the tin content is 10% by weight or more in 100% by weight of the conductive portion. From the viewpoint of further improving the conduction reliability, it is preferable that the tin content is 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 in 100% by weight of the conductive portion. The tin content may be 100% by weight (total amount) in 100% by weight of the conductive portion.

[0088] 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, or gold, more preferably tin or nickel, and even more preferably tin. When the metal constituting the outermost layer is one of these preferred metals, the connection resistance between electrodes is further reduced. Furthermore, when the metal constituting the outermost layer is gold, corrosion resistance is further improved.

[0089] The area (coverage) of the conductive portion relative to the total surface area (100%) of the base particle is preferably 80% or more, more preferably 90% or more. There is no particular upper limit to the coverage. The coverage may be 99% or less. When the coverage is equal to or greater than the lower limit and equal to or less than the upper limit, electrical connection reliability can be further effectively improved when electrodes are electrically connected.

[0090] The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.5 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 is more effectively improved, and the conductive particles do not become too hard, allowing the conductive particles to be sufficiently deformed when connecting electrodes.

[0091] 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.

[0092] The thickness of the conductive portion can be measured by observing the cross section of the conductive particle using, for example, a transmission electron microscope (TEM).

[0093] 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.).

[0094] <Flux-containing particles> The conductive particles include flux-containing particles. The flux-containing particles are arranged outside the conductive particle body. The flux-containing particles are arranged on the surface of the conductive particle body. The flux-containing particles are arranged on the surface of the conductive part. The flux-containing particles may be arranged on the surface of the conductive particle body or the conductive part via a flux film or the like. The flux-containing particles may be in contact with the surface of the conductive particle body, or may not be in contact with the surface of the conductive part. The flux-containing particles may be in contact with the surface of the conductive part, or may not be in contact with the surface of the conductive part.

[0095] The flux-containing particle preferably includes a particle body and flux.

[0096] Examples of the particle body include inorganic particles excluding metal particles, resin particles, organic-inorganic hybrid particles, and metal particles. The particle body is preferably an inorganic particle excluding metal particles or a resin particle, and more preferably a resin particle.

[0097] Examples of the inorganic particles other than the metal particles include silica, alumina, titania, etc. Examples of the silica include porous silica.

[0098] 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. Since the hardness of the resin particles can be easily controlled within a suitable range, the material of the resin particles preferably contains a polymerizable monomer, and more preferably is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group.

[0099] 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.

[0100] 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 2-hydroxyethyl (meth)acrylate, 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.

[0101] 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 the polyfunctional (meth)acrylate compound 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.

[0102] 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.

[0103] The glass transition temperature of the homopolymer of the polymerizable monomer is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 80°C or higher, and preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 200°C or lower. When the glass transition temperature of the homopolymer of the polymerizable monomer is above the lower limit and below the upper limit, the flux gradually leaks from the flux-containing particles due to the application of heat and pressure during conductive connection. As a result, the oxide coatings on the surfaces of the conductive particles and the electrodes can be more effectively removed, and the electrical connection reliability can be more effectively improved when the electrodes are electrically connected. The glass transition temperature of the homopolymer of the polymerizable monomer that is most abundant by weight among the polymerizable monomers in the resin particle material is preferably above the lower limit and below the upper limit.

[0104] The flux is not particularly limited. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, phosphoric acid, a phosphoric acid derivative, an organic halide, hydrazine, an amine compound, a molten salt, an organic acid, and rosin. Only one type of the flux may be used, or two or more types may be used in combination.

[0105] Examples of the amine compound include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, and benzotriazole.

[0106] The molten salt may be ammonium chloride or the like.

[0107] From the viewpoint of more effectively improving the electrical conductivity reliability, the flux is preferably an organic acid or pine resin, and more preferably pine resin.

[0108] The organic acid is preferably an organic acid having two or more carboxyl groups, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0109] The rosin is a rosin containing abietic acid as a main component. Examples of the rosin include abietic acid and acrylic-modified rosin. From the viewpoint of more effectively improving the electrical conductivity reliability, the rosin is preferably abietic acid.

[0110] The melting point (activation temperature) of the flux is preferably 10°C or higher, more preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and is preferably 200°C or lower, more preferably 190°C or lower, even more preferably 160°C or lower, even more preferably 150°C or lower, and even more preferably 140°C or lower. When the melting point of the flux is above the lower limit and below the upper limit, the flux effect is more effectively exerted, and the conductive particles are more efficiently arranged on the electrode. The melting point (activation temperature) of the flux is preferably 80°C or higher and 190°C or lower, and particularly preferably 80°C or higher and 140°C or lower.

[0111] Examples of the flux having a melting point (active temperature) of 80°C or higher and 190°C or lower include dicarboxylic acids such as succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and suberic acid (melting point 142°C), benzoic acid (melting point 122°C), and malic acid (melting point 130°C).

[0112] The boiling point of the flux is preferably 300° C. or lower.

[0113] From the viewpoint of enhancing the effect of the flux, in the conductive particles according to the present invention, the particle diameter of the flux-containing particles is preferably 100 nm or more, more preferably 200 nm or more, even more preferably 350 nm or more, and is preferably 800 nm or less, more preferably 500 nm or less, even more preferably 400 nm or less.

[0114] The particle size of the flux-containing particles is an average particle size, and the average particle size indicates a volume average particle size. The particle size of the flux-containing particles is determined using a particle size distribution measuring device or the like.

[0115] The ratio of the particle size of the conductive particles to the particle size of the flux-containing particles (particle size of conductive particles / particle size of flux-containing particles) is preferably 3 or more, more preferably 6 or more, even more preferably 16 or more, and is preferably 500 or less, more preferably 150 or less, even more preferably 100 or less, and particularly preferably 70 or less. When the ratio (particle size of conductive particles / particle size of flux-containing particles) is equal to or more than the above lower limit and equal to or less than the above upper limit, insulation reliability and conduction reliability can be more effectively improved when electrodes are electrically connected.

[0116] The ratio of the particle diameter of the conductive particle body to the particle diameter of the flux-containing particle (particle diameter of conductive particle body / particle diameter of flux-containing particle) is preferably 3 or more, more preferably 6 or more, even more preferably 16 or more, and is preferably 500 or less, more preferably 150 or less, even more preferably 100 or less, and particularly preferably 60 or less. When the ratio (particle diameter of conductive particle body / particle diameter of flux-containing particle) is equal to or more than the above lower limit and equal to or less than the above upper limit, insulation reliability and conduction reliability can be more effectively improved when electrodes are electrically connected.

[0117] In order to more effectively exert the effects of the present invention, the coefficient of variation (CV value) of particle diameters of the flux-containing particles is preferably 20% or less.

[0118] The coefficient of variation (CV value) can be measured as follows.

[0119] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of particle size of flux-containing particles Dn: average particle size of flux-containing particles

[0120] The shape of the flux-containing particles is not particularly limited. The shape of the flux-containing particles may be spherical, may be a shape other than spherical, or may be flat. From the viewpoint of more effectively exerting the effects of the present invention, the flux-containing particles are preferably spherical.

[0121] From the viewpoint of exerting the effects of the present invention more effectively, when the particle body of the flux-containing particle is a resin particle, it is preferable that the flux-containing particle maintains its particulate shape at the glass transition temperature of the homopolymer of the polymerizable monomer that is the material of the resin particle.

[0122] The flux-containing particles preferably exhibit no breaking point in a compression-displacement curve when subjected to a maximum test load of 3.3 mN for 10 seconds. In this case, the flux gradually leaks from the flux-containing particles due to the application of heat and pressure during conductive connection, thereby more effectively removing oxide coatings from the surfaces of the conductive particles and the electrodes, and more effectively improving the electrical connection reliability when the electrodes are electrically connected. Specifically, using a micro-compression tester, the flux-containing particles are compressed at 25°C with a smooth cylindrical indenter (diameter: 50 μm, made of diamond) at the end face under a maximum test load of 3.3 mN for 10 seconds. The load (N) and compression displacement (mm) are measured, and a compression-displacement curve is prepared. An example of the micro-compression tester is the "ENT-NEXUS" manufactured by Elionix.

[0123] In order to more effectively achieve the effects of the present invention, it is preferable that the flux-containing particles are not microcapsules containing flux. The particle bodies of the flux-containing particles may have a porous structure. The porous structure means a structure having a plurality of pores (fine pores).

[0124] When the distance from the surface to the center of the flux-containing particle is divided into three equal parts: a surface portion, a central portion, and a middle portion between the surface and central portions, the flux-containing particle may contain flux in the surface portion, the middle portion, or the central portion. The flux-containing particle preferably contains flux in the surface portion, more preferably in the surface and middle portions, and even more preferably in the surface, middle, and central portions. In this case, the flux gradually leaks from the flux-containing particle due to the application of heat and pressure during conductive connection, thereby more effectively removing oxide coatings from the surfaces of the conductive particles and the electrodes, and more effectively improving the reliability of electrical continuity and insulation when electrodes are electrically connected. The flux-containing particle may also contain flux in the middle and central portions.

[0125] In order to effectively improve the electrical continuity reliability and the insulating reliability, the flux-containing particle preferably contains flux in the outermost surface portion having a thickness of 10 nm from the surface toward the center of the flux-containing particle.

[0126] From the viewpoint of improving the electrical conductivity reliability, when a conductive particle-containing liquid in which 3 parts by weight of the above-mentioned conductive particles are added to 100 parts by weight of ethanol is subjected to ultrasonic treatment at 20°C and 40 kHz for 5 minutes, it is preferable that the residual rate of the flux-containing particles calculated by the following formula (1) is 99% or less.

[0127] Residual rate of flux-containing particles (%) = (coverage rate of flux-containing particles after ultrasonic treatment / coverage rate of flux-containing particles before ultrasonic treatment) × 100 Equation (1)

[0128] The coverage rate of the flux-containing particles refers to the total area of ​​the portions where the flux-containing particles are disposed relative to the total surface area of ​​the conductive particle body (100%). The coverage rate of the flux-containing particles is determined by observing the conductive particles with an electron microscope or an optical microscope and calculating the percentage of the surface area of ​​the portions where the flux-containing particles are disposed relative to the projected area of ​​the conductive particle body. The coverage rate of the flux-containing particles is preferably determined by observing 20 random conductive particles with a scanning electron microscope (SEM) and calculating the average percentage of the surface area of ​​the portions where the flux-containing particles are disposed relative to the projected area of ​​the conductive particle body.

[0129] From the viewpoint of improving the electrical conductivity reliability, the residual rate of the flux-containing particles is preferably 90% or less, more preferably 70% or less, even more preferably 65% ​​or less, and particularly preferably 60% or less. There is no particular limitation on the lower limit of the residual rate of the flux-containing particles. The residual rate of the flux-containing particles may be 0%.

[0130] Methods for keeping the residual rate of the flux-containing particles within the above-mentioned preferred range include using particles made of a material with low adhesiveness as the particle body of the flux-containing particles, and using particles with a high flux content as the particle body of the flux-containing particles.

[0131] Examples of methods for incorporating the flux into the particle bodies (methods for forming flux-containing particles) include the following methods: A method of dispersing the particle bodies in a solvent containing a low concentration of flux and allowing the flux components to adsorb; A method of spraying an organic solvent containing a high concentration of flux components onto the particle bodies to adhere the flux; A method of adding flux to the solvent used in particle production to allow the flux to be incorporated into the particle bodies. From the perspective of improving conductivity reliability, the method of incorporating the flux into the particle bodies is preferably a method of dispersing the particle bodies in a solvent containing a low concentration of flux and allowing the flux components to adsorb.

[0132] Methods for disposing the flux-containing particles on the surface of the conductive particle body 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 insulation reliability and conduction reliability when electrodes are electrically connected, the method for disposing the flux-containing particles on the surface of the conductive particle body is preferably electrostatic deposition.

[0133] The outer surfaces of the conductive part and the flux-containing particles may each be coated with a compound having a reactive functional group. The outer surfaces of the conductive part and the flux-containing particles may not be directly chemically bonded to each other, but may be indirectly chemically bonded to each other via a compound having a reactive functional group. After introducing carboxyl groups onto the outer surfaces of the conductive part, the carboxyl groups may be chemically bonded to functional groups on the outer surfaces of the flux-containing particles via a polymer electrolyte such as polyethyleneimine.

[0134] From the viewpoint of exerting the effects of the present invention more effectively, the content of the flux-containing particles in 100% by weight of the conductive particles is preferably 1% by weight or more, more preferably 1.5% by weight or more, even more preferably 2% by weight or more, even more preferably 2.5% by weight or more, and particularly preferably 3% by weight or more.

[0135] The total content of the flux in the flux-containing particles and the flux in the flux film, based on 100% by weight of the conductive particles, is preferably 1% by weight or more, more preferably 1.5% by weight or more, even more preferably 2% by weight or more, still more preferably 3% by weight or more, and particularly preferably 10% by weight or more. When the total content of the flux is equal to or more than the lower limit, the effects of the present invention can be more effectively exhibited.

[0136] The content of flux in the flux-containing particles is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, still more preferably 20% by weight or more, and particularly preferably 50% by weight or more, based on a total of 100% by weight of the content of flux in the flux-containing particles and the content of flux in the flux film described below. When the content of flux in the flux-containing particles is equal to or more than the lower limit, the effects of the present invention can be more effectively exhibited.

[0137] <Flux film> The conductive particle includes a flux film. The flux film is disposed on the outside of the conductive particle body. The flux film is disposed on the outside of the conductive portion. The flux film is disposed on the surface of the conductive particle body. The flux film is disposed on the surface of the conductive portion. The flux film may be disposed on the outside of the flux-containing particle, or may not be disposed on the outside of the flux-containing particle. The flux film may be disposed on the surface of the flux-containing particle, or may not be disposed on the surface of the flux-containing particle.

[0138] The flux in the flux film may be any of the fluxes described above. The flux in the flux film may be the same as or different from the flux in the flux-containing particles.

[0139] The area of ​​the flux film (coverage by the flux film) is preferably 40% or more, more preferably 50% or more, of the total surface area (100%) of the conductive particle body. There is no particular upper limit to the coverage. The coverage may be 99% or less. When the coverage is equal to or greater than the lower limit and equal to or less than the upper limit, the oxide coating on the surface of the conductive particle and the surface of the electrode can be more effectively removed, and when the electrodes are electrically connected, the electrical connection reliability can be more effectively improved.

[0140] The thickness of the flux film is preferably 0.5 nm or more, more preferably 1 nm or more, and is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 25 nm or less. When the thickness of the flux film is equal to or more than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability is more effectively improved, and the conductive particles do not become too hard, allowing the conductive particles to be sufficiently deformed when connecting electrodes.

[0141] The method for disposing the flux film on the surface of the conductive particle body includes physical or mechanical methods. 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 insulation reliability and conduction reliability when electrodes are electrically connected, the method for disposing the flux film on the surface of the conductive particle body is preferably dipping.

[0142] (Conductive materials) The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in the binder resin and used, and are preferably dispersed in the binder resin and used as a conductive material. The conductive material is 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 conductive material uses the conductive particles described above, it is possible to further improve the insulation reliability and conduction reliability between electrodes.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] In addition to the conductive particles and the binder resin, the conductive material may contain various additives such as fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, and flame retardants.

[0147] The method for dispersing the conductive particles in the binder resin can be a conventionally known dispersion method and is not particularly limited. Examples of the method for dispersing the conductive particles in the binder resin include the following methods: A method in which the conductive particles are added to the binder resin and then kneaded and dispersed using a planetary mixer or the like; A method in which the conductive particles are uniformly dispersed in water or an organic solvent 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 solvent or the like, then the conductive particles are added, and then kneaded and dispersed using a planetary mixer or the like.

[0148] The viscosity (η25) of the conductive material 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 conductive material 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 adjusted appropriately by changing the types and amounts of the components.

[0149] 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.

[0150] The conductive material according to the present invention can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention 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.

[0151] The content of the binder resin in 100% by weight of the conductive material 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 conductive material can be further improved.

[0152] The content of the conductive particles in 100% by weight of the conductive material 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 conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability and the insulation reliability between the electrodes can be further improved.

[0153] (Connection structure) The 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 conductive 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 particle bodies. The material of the connection portion is preferably conductive particles or a conductive material containing the conductive particles and a binder resin.

[0154] The connection structure can be obtained by a step of disposing the conductive particles or the conductive material between the first and second connection target members and a step of electrically conductively connecting them by thermocompression bonding. During the thermocompression bonding, it is preferable that the flux-containing particles detach from the conductive particles. In particular, it is preferable that the flux-containing particles detach from the conductive particles between the conductive particle body and the electrode.

[0155] FIG. 5 is a cross-sectional view that schematically shows a connection structure using conductive particles according to the first embodiment of the present invention.

[0156] The connection structure 81 shown in FIG. 5 includes a first member to be connected 82, a second member to be connected 83, and a connection portion 84 connecting the first member to be connected 82 and the second member to be connected 83. The connection portion 84 is formed from a conductive material containing conductive particles 1. The connection portion 84 is preferably formed by curing a conductive material containing a plurality of conductive particles 1. Note that in FIG. 5, the conductive particles 1 are shown schematically for ease of illustration. Instead of the conductive particles 1, conductive particles 1A, conductive particles 1B, or conductive particles 1C may be used.

[0157] 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 the conductive particle bodies 11 of one or more conductive particles 1. Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive particle bodies 11 of the conductive particles 1.

[0158] The method for manufacturing the connection structure is not particularly limited. One example of a method for manufacturing a connection structure includes placing the conductive material between a first connection target member and a second connection target member to obtain 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 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 heating temperature of the thermocompression bonding are above the lower limit and below the upper limit, the flux-containing particles and the flux film can be easily removed from the surfaces of the conductive particles during conductive connection, thereby further improving the reliability of electrical connection between electrodes. Furthermore, when the flux-containing particles are detached, the flux gradually leaks from the flux-containing particles, which more effectively removes oxide films from the surfaces of the conductive particles and the electrodes, and further effectively improves the reliability of electrical connection between electrodes. Furthermore, since the flux gradually leaks from the flux-containing particles even after the conductive connection is made, the oxide coating on the surface of the conductive particles and the surface of the electrodes after the conductive connection can also be effectively removed, and when the electrodes are electrically connected, the conductivity reliability can be further effectively improved.

[0159] When the laminate is heated and pressurized, the flux-containing particles and flux film present between the conductive particles and the first and second electrodes can be removed. For example, during the heating and pressurization, the flux-containing particles and flux film present between the conductive particles and the first and second electrodes are detached from the surfaces of the conductive particles. During the heating and pressurization, some of the flux-containing particles and flux film may be detached from the surfaces of the conductive particles, partially exposing the surfaces (conductive portions) of the conductive particle bodies. The exposed surfaces (conductive portions) of the conductive particle bodies may contact the first and second electrodes, thereby electrically connecting the first and second electrodes via the conductive particle bodies.

[0160] 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.

[0161] Examples of the electrode provided on the connection target member 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 member is a flexible printed circuit board, the electrode is preferably a gold electrode, nickel electrode, tin electrode, silver electrode, or copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, copper electrode, molybdenum electrode, silver electrode, or tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode made of aluminum alone, or an electrode 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.

[0162] 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.

[0163] The following materials were prepared:

[0164] Flux: Rosin-based flux (Arakawa Chemical Industries "KR-612", softening point: 82°C) Adipic acid benzylamine salt (melting point: 171°C)

[0165] Example 1 (1) Preparation of the conductive particle body (Preparation of base particles) Resin particles (average particle diameter 20 μm) formed from a copolymer of tetramethylolmethane tetraacrylate and divinylbenzene were prepared as base particles. 10 parts by weight of the base particles were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, and the solution was filtered to extract the base particles. Next, the base particles were added to 100 parts by weight of a solution containing 1% by weight of dimethylamine borane to activate the surface of the base particles. The surface-activated base particles were thoroughly washed with water and then added to 500 parts by weight of distilled water and dispersed to obtain dispersion liquid (A). Next, 1 g of nickel particle slurry (average particle diameter 100 nm) was added to dispersion liquid (A) over 3 minutes to obtain suspension (A) containing base particles with core materials attached.

[0166] (Formation of conductive part) A nickel plating solution (pH 8.5) containing 0.35 mol / L nickel sulfate, 1.38 mol / L dimethylamine borane, and 0.5 mol / L sodium citrate was prepared. While stirring suspension (A) at 70°C, the nickel plating solution was gradually added dropwise to suspension (A) to perform electroless nickel plating. The particles were then filtered to remove them, washed with water, and dried to form a first conductive portion (nickel-boron layer) on the surface of the base particles. Next, a tin plating solution was prepared by adjusting a mixed solution containing 15 g / L tin sulfate, 45 g / L ethylenediaminetetraacetic acid, and 1.5 g / L phosphinic acid to a pH of 8.5 with sodium hydroxide. A reduction solution was also prepared by adjusting a solution containing 5 g / L sodium borohydride to a pH of 10.0 with sodium hydroxide. The tin plating solution was gradually added dropwise to the base particles having the first conductive portion to perform electroless tin plating, followed by reduction with the reduction solution. The particles were then filtered to remove them, washed with water, and dried to obtain conductive particle bodies having a first conductive portion (nickel-boron layer, thickness 0.2 μm) and a second conductive portion (tin layer, thickness 0.25 μm).

[0167] (2) Preparation of conductive particles (Preparation of particle body (resin particle) in flux-containing particle) The following composition was placed in a 2000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way stopcock, condenser, and temperature probe. Distilled water was added to a solids content of 10 wt%. The mixture was stirred at 120 rpm and polymerized at 50°C for 5 hours under a nitrogen atmosphere. The composition contained 1080 mmol of methyl methacrylate, 10 mmol of ethylene glycol dimethacrylate, 0.5 mmol of 4-(methacryloyloxy)phenyldimethylsulfonium methyl sulfate, and 0.5 mmol of 2,2'-azobis{2-[N-(2-carboxyethyl)amidino]propane}. After the reaction was completed, the mixture was freeze-dried to obtain resin particles (particle diameter 360 nm) bearing sulfonic acid groups derived from 4-(methacryloyloxy)phenyldimethylsulfonium methyl sulfate on their surfaces.

[0168] (Preparation of Flux-Containing Particles and Conductive Particles with Flux Films) The resulting resin particles were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of resin particles (B). 10 g of the conductive particle bodies obtained in (1) was dispersed in 500 mL of distilled water, and then 1 g of dispersion (B) was added and stirred at room temperature for 8 hours. After filtering through a 3 μm mesh filter, the mixture was washed with methanol and dried to obtain conductive particles with particle bodies (resin particles). The resulting conductive particles with particle bodies were dispersed in 200 mL of ethanol to obtain dispersion (C). Dispersion (C) was then mixed with 300 mL of ethanol in which 0.5 g of rosin-based flux had been dissolved, and the mixture was stirred for 10 minutes at 50°C using ultrasonic dispersion. After filtering through a 3 μm mesh filter and drying, flux-containing particles and conductive particles with a flux film were obtained.

[0169] (3) Preparation of conductive material (anisotropic conductive paste) Seven parts by weight of the obtained conductive 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 mixed together, and the mixture was degassed and stirred for 3 minutes to obtain a conductive material (anisotropic conductive paste).

[0170] (4) Fabrication of connection structure A flexible printed circuit board was prepared with an Au electrode pattern (first electrode, electrode: Ni / Au thin film on Cu) with an L / S of 200 μm / 200 μm formed on its top surface, and another printed circuit board with an Au electrode pattern (second electrode, electrode: Ni / Au thin film on Cu) with an L / S of 200 μm / 200 μm formed on its bottom surface.

[0171] The resulting anisotropic conductive paste was applied to the printed circuit board to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the flexible printed circuit board was laminated on the anisotropic conductive paste layer with the electrodes facing each other. Thereafter, 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.

[0172] Example 2 When preparing the particle body of the flux-containing particle, the amount of methyl methacrylate in the composition was changed from 1080 mmol to 180 mmol, and 900 mmol of glycidyl methacrylate was further added to the composition. Other than the above changes, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1.

[0173] Example 3 When preparing the particle body of the flux-containing particles, 840 mmol of polystyrene and 240 mmol of lauryl methacrylate were added to the composition instead of 1080 mmol of methyl methacrylate. Other than the above changes, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1.

[0174] Example 4 When preparing the particle body of the flux-containing particle, the amount of methyl methacrylate in the composition was changed from 1080 mmol to 540 mmol, and 540 mmol of glycidyl methacrylate was further added to the composition. Other than the above changes, conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1.

[0175] Example 5 Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that the flux in the flux-containing particles and the flux film was changed to adipate benzylamine salt.

[0176] Example 6 When forming the first conductive portion, instead of the nickel plating solution, a copper plating solution was prepared by adjusting the pH to 10.5 with ammonia using a mixture of 200 g / L copper sulfate, 150 g / L ethylenediaminetetraacetic acid, 100 g / L sodium gluconate, and 50 g / L formaldehyde. While stirring the suspension (A) at 65°C, 250 ml of the copper plating solution was added dropwise to the suspension (A) at a rate of 10 ml / min to perform electroless copper plating. The mixture was then stirred until the pH stabilized. After confirming that hydrogen bubbling had stopped, the particles were filtered to remove them, washed with water, and dried to form a first conductive portion (copper layer, 0.2 μm thick) on the surface of the base particle. Conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the first conductive portion was a copper layer.

[0177] Example 7 Conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that no core material was used and no protrusions were formed in the preparation of the conductive particle body, and that only a tin layer (0.3 μm) was formed in the formation of the conductive portion.

[0178] Example 8 Conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that in producing the conductive particle body, only a nickel layer (0.3 μm) was formed as the conductive portion.

[0179] Example 9 The base particles having the first conductive portion (nickel-boron layer) obtained in Example 1 were added to 100 parts by weight of distilled water and dispersed to obtain a suspension. Thereafter, when forming the second conductive portion, instead of the tin plating solution, a reduced gold plating solution containing 0.03 mol / L of gold cyanide and 0.1 mol / L of hydroquinone as a reducing agent was prepared. While stirring the obtained suspension at 70°C, the reduced gold plating solution was gradually added dropwise to the suspension to perform reduced gold plating. The suspension was then filtered to remove the particles, which were then washed with water and dried to obtain conductive particle bodies having a first conductive portion (nickel-boron layer, 0.2 μm thick) and a second conductive portion (gold layer, 0.25 μm thick). Conductive particles, conductive materials, and connection structures were obtained in the same manner as in Example 1, except that the obtained conductive particle bodies were used.

[0180] (Comparative Example 1) Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that no flux-containing particles were disposed on the surface of the conductive particle body.

[0181] (Comparative Example 2) Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 8, except that no flux-containing particles were disposed on the surface of the conductive particle body.

[0182] (Comparative Example 3) Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 9, except that no flux-containing particles were disposed on the surface of the conductive particle body.

[0183] Comparative Example 4 Conductive particles, a conductive material, and a connection structure were obtained in the same manner as in Example 1, except that no flux film was disposed on the surface of the conductive particle body.

[0184] (evaluation) (1) Particle diameters of base particles, flux-containing particles, and conductive particles, and thicknesses of conductive portions and flux films The particle diameters of the base particle, the flux-containing particle, and the conductive particle, as well as the thicknesses of the conductive portion and the flux film, were measured using the methods described above. Each particle diameter was calculated by averaging the results of 20 measurements.

[0185] In addition, the ratio of the particle size of the conductive particles to the particle size of the flux-containing particles (particle size of conductive particles / particle size of flux-containing particles) was calculated.

[0186] (2) Presence or absence of a breaking point in the compression-displacement curve Using a micro-compression testing machine ("ENT-NEXUS" manufactured by Elionix), the flux-containing particles were compressed with a cylindrical (diameter 50 μm, made of diamond) smooth indenter end face at 25°C under the condition of applying a maximum test load of 3.3 mN for 10 seconds. The load value (N) and compression displacement (mm) at this time were measured, and a compression-displacement curve was created to confirm the presence or absence of a breaking point.

[0187] (3) Residual rate of flux-containing particles The residual rate (%) of the flux-containing particles in the obtained conductive particles was measured by the method described above.

[0188] (4) Ability to remove oxide film The conductive particles obtained were dispersed on a Cu plate using a 1% by weight aqueous sulfuric acid solution. The plate was then heated on a hot plate at 250°C for 1 minute, and then thoroughly cooled to remove the particles. The removability of the oxide film was evaluated based on the following criteria (color of the Cu plate).

[0189] [Criteria for determining oxide film removability] ○○○: The Cu plate is orange ○○: The Cu plate is reddish-orange ○: The Cu plate is purple ×: The Cu plate is silver-green.

[0190] (5) 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 the 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 applied. The conductivity reliability was evaluated according to the following criteria.

[0191] [Conductivity reliability criteria] ○○○: Connection resistance is 0.32Ω or less ○○: Connection resistance is over 0.32Ω and 0.35Ω or less ○: Connection resistance is over 0.35Ω and 0.41Ω or less ×: Connection resistance exceeds 0.41Ω

[0192] The results are shown in Tables 1 to 3 below.

[0193] [Table 1]

[0194] [Table 2]

[0195] [Table 3] [Explanation of symbols]

[0196] 1,1A,1B,1C…conductive particles 11,11A,11B,11C…Conductive particle body 11Ca…protrusion 12, 12A, 12B, 12C...Flux-containing particles 13, 13A, 13B, 13C...Flux film 21,21A,21B,21C...Base material particles 22,22A,22B,22C...Conductive part 22BA...first conductive part 22BB...Second conductive part 23C…core substance 81...Connection structure 82...First connection target member 82a...first electrode 83...Second connecting member 83a...second electrode 84...Connection

Claims

1. The conductive particle body includes a plurality of flux-containing particles and a flux film. the conductive particle body comprises a base particle and a conductive portion disposed on the outside of the base particle, the flux-containing particles are disposed outside the conductive particle body; A conductive particle, wherein the flux film is disposed on the outside of the conductive particle body.

2. the flux-containing particle includes a particle body and a flux, The conductive particle according to claim 1 , wherein the particle body is a resin particle.

3. the material of the resin particles contains a polymerizable monomer, The conductive particle according to claim 2 , wherein the glass transition temperature of the homopolymer of the polymerizable monomer is 80° C. or higher.

4. The conductive particle according to any one of claims 1 to 3, wherein the flux-containing particle does not have a breaking point in a compression-displacement curve when a maximum test load of 3.3 mN is applied to the flux-containing particle for 10 seconds.

5. The conductive particle according to any one of claims 1 to 3, wherein the conductive portion contains tin.

6. The conductive particles according to any one of claims 1 to 3, wherein the ratio of the particle diameter of the conductive particles to the particle diameter of the flux-containing particles is 3 or more and 500 or less.

7. The conductive particles according to any one of claims 1 to 3, wherein the particle diameter of the conductive particles is 1 µm or more and 50 µm or less.

8. The conductive particles according to any one of claims 1 to 3, wherein when a conductive particle-containing liquid obtained by adding 3 parts by weight of the conductive particles to 100 parts by weight of ethanol is subjected to ultrasonic treatment at 20°C and 40 kHz for 5 minutes, the residual rate of the flux-containing particles calculated by the following formula (1) is 99% or less: Residual rate of flux-containing particles (%)=(coverage rate by flux-containing particles after ultrasonic treatment / coverage rate by flux-containing particles before ultrasonic treatment)×100 (Equation 1)

9. A conductive material comprising the conductive particles according to any one of claims 1 to 3 and a binder resin.

10. a first connection target member having a first electrode on a surface thereof; a second connection target member having a second electrode on its surface; a connection portion that connects the first connection target member and the second connection target member, The material of the connection portion contains the conductive particles according to any one of claims 1 to 3, A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particle body.

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