JP7463069B2 - Conductive particles, conductive material, connection structure, and method for producing connection structure - Google Patents

Description

The present invention relates to conductive particles that can be used for electrical connections between electrodes. The present invention also relates to a conductive material, a connection structure, and a method for manufacturing a connection structure that use the conductive particles.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In such anisotropic conductive materials, conductive particles are dispersed in a binder resin. In addition, as the conductive particles, conductive particles having a base particle and a conductive portion disposed on the surface of the base particle may be used.

The anisotropic conductive material is used to obtain various connection structures. Examples of connections using the anisotropic conductive material include connections between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), connections between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), connections between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and connections between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

Magnetic conductive particles may also be used as the conductive particles. The following Patent Document 1 discloses an anisotropic conductive sheet in which conductive particles are arranged at predetermined positions by applying a localized magnetic field to attract the conductive particles toward the magnetic field. In Example 1 of Patent Document 1, nickel particles made entirely of nickel are used as the magnetic conductive particles.

Patent document 2 discloses a conductive particle comprising a resin particle, a metal plating layer formed on the surface of the resin particle, and an insulating layer formed on the outer surface of the metal plating layer. The metal plating layer may be a magnetic metal plating layer containing at least one of Fe, Ni, and Co.

JP 2006-093020 A JP 2013-045565 A

In Patent Document 1, when obtaining an anisotropic conductive sheet, a magnetic field is applied and conductive particles are arranged at predetermined positions in the sheet. However, with such an anisotropic conductive sheet, it is necessary to precisely align the electrodes with the conductive particles when making a conductive connection.

Furthermore, in nickel particles formed entirely from nickel as described in Patent Document 1, when a magnetic field is applied, the weight of the particles can cause the conductive particles to move slowly. Furthermore, in a connection structure in which a conductive connection is made by nickel particles, the electrodes can be damaged. For example, the electrodes can be damaged when the nickel particles move or when the electrodes are crimped together via the nickel particles. As a result, the connection resistance after the conductive connection can be high.

Furthermore, as described in Patent Document 2, when a magnetic metal plating layer is formed using at least one of Fe, Ni, and Co and magnetized, the particles may aggregate together, and when a magnetic field is applied, they may not be accurately aligned with the electrode. As a result, a sufficient conductive connection may not be obtained.

The object of the present invention is to provide conductive particles that can be easily moved and aligned when forming an electrode section using magnetic force, and that can reduce the connection resistance after conductive connection. Another object of the present invention is to provide a conductive material, a connection structure, and a method for manufacturing a connection structure that use the conductive particles.

According to a broad aspect of the present invention, there is provided a conductive particle comprising a base particle and a conductive portion disposed on the surface of the base particle, the conductive particle having a saturation magnetization of 10 emu/g or more.

In a particular aspect of the conductive particles according to the present invention, the base particles are not metal particles.

In a particular aspect of the conductive particles according to the present invention, the base particles are resin particles or organic-inorganic hybrid particles.

In a particular aspect of the conductive particles according to the present invention, the conductive portion contains nickel, cobalt, or iron.

In a particular aspect of the conductive particles according to the present invention, the total content of nickel, cobalt and iron is 90% by weight or more in 100% by weight of the conductive portion.

In a particular aspect of the conductive particles according to the present invention, the conductive portion contains at least two of nickel, cobalt, and iron, and the content of one of the nickel content, the cobalt content, and the iron content is 51% by weight or more in 100% by weight of the conductive portion.

In a specific aspect of the conductive particle according to the present invention, the base particle has a compressive modulus of elasticity of 1000 N/mm ² or more and 30000 N/mm ² or less when compressed by 10% at 25° C.

In a particular aspect of the conductive particles according to the present invention, the particle diameter of the base particle is 1 μm or more and 10 μm or less.

In a particular aspect of the conductive particles according to the present invention, the specific gravity of the base particle is lower than the specific gravity of the conductive portion.

In a particular aspect of the conductive particles of the present invention, the conductive particles are used in a conductive connection that applies a magnetic field or magnetic force.

In a particular aspect of the conductive particle according to the present invention, the conductive particle has protrusions on the outer surface of the conductive portion.

In a particular aspect of the conductive particle according to the present invention, the conductive particle comprises an insulating material disposed on the outer surface of the conductive portion.

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

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 part connecting the first connection target member and the second connection target member, the material of the connection part being the conductive particles described above or a conductive material containing the conductive particles and a binder resin, and the first electrode and the second electrode being electrically connected by the conductive particles.

According to a broad aspect of the present invention, there is provided a method for manufacturing a connection structure, comprising a first arrangement step of arranging the above-mentioned conductive particles or a conductive material containing the conductive particles and a binder resin on the surface of a first connection target member having a first electrode on its surface, a second arrangement step of arranging a second connection target member having a second electrode on its surface on the opposite side of the conductive particles or conductive material to the first connection target member, and a step of applying a magnetic field or magnetic force before or after the second arrangement step, thereby obtaining a connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

The conductive particles according to the present invention include a base particle and a conductive portion disposed on the surface of the base particle. The conductive particles according to the present invention have a saturation magnetization of 10 emu/g or more. The conductive particles according to the present invention have the above configuration, and therefore can reduce the connection resistance after conductive connection.

FIG. 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention. FIG. 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention. FIG. 5 is a front cross-sectional view that illustrates a connection structure using conductive particles according to the first embodiment of the present invention. FIG. 6 is a front cross-sectional view for explaining a method for manufacturing the connection structure shown in FIG. FIG. 7 is a front cross-sectional view for explaining another method for manufacturing the connection structure shown in FIG.

The details of the present invention are explained below.

(Conductive particles)
The conductive particle according to the present invention includes a base particle and a conductive portion disposed on a surface of the base particle. The conductive particle according to the present invention has a saturation magnetization of 10 emu/g or more.

The conductive particles according to the present invention have the above-mentioned configuration, so that the connection resistance after conductive connection can be reduced.

The conductive particles according to the present invention have a saturation magnetization of 10 emu/g or more, so that the conductive particles can be effectively moved by applying a magnetic field or magnetic force. For example, by applying a magnetic field or magnetic force to the electrode portion, the conductive particles can be effectively moved onto or between the electrodes. As a result, the conductive particles according to the present invention have a large number of conductive particles arranged between the upper and lower electrodes that should be connected, and the connection resistance is low. In addition, horizontally adjacent electrodes that should not be connected are less likely to be electrically connected, making it less likely that short-circuit problems will occur.

In addition, simply using conductive metal particles with a high saturation magnetization amount can result in high connection resistance. The conductive particles according to the present invention are provided with the above-mentioned base particles, so that the electrodes are less likely to be damaged when the conductive particles move. Furthermore, the conductive particles according to the present invention are provided with the above-mentioned base particles, so that the electrodes are less likely to be damaged even if the conductive particles are compressed between the upper and lower electrodes. As a result, the connection resistance can be reduced.

From the viewpoint of moving the conductive particles more effectively, the saturation magnetization of the conductive particles is preferably 15 emu/g or more, more preferably 20 emu/g or more. The higher the saturation magnetization, the better. From the viewpoint of easily producing the conductive particles, the saturation magnetization of the conductive particles may be 300 emu/g or less, or may be 100 emu/g or less.

The saturation magnetization can be controlled by the type and content of metal used in the conductive portion, the thickness of the conductive portion, etc.

The saturation magnetization is measured as follows:

The amount of magnetization can be calculated by measuring the magnetic hysteresis curve of the conductive particles. A vibrating sample magnetometer (Riken Denshi Co., Ltd.'s "BHV-50") or similar device can be used. In addition, the sample can be prepared by sealing 15 mg of dried conductive particles in a sample holder without compressing them, and then measurements can be performed.

The compressive modulus (10% K value) of the base particle when compressed by 10% at 25 ° C. is preferably 1000 N / mm ² or more, more preferably 3000 N / mm ² or more, and preferably 30000 N / mm ² or less, more preferably 20000 N / mm ² or less. When the 10% K value of the base particle is the above lower limit or more and the above upper limit or less, damage to the electrode can be further suppressed, and the connection resistance can be effectively reduced. Furthermore, when forming a conductive part on the surface, aggregation can be further effectively suppressed, and the occurrence of plating cracks and plating peeling can be further effectively suppressed.

The compressive elastic modulus (10% K value) of the base particles can be measured as follows:

Using a micro-compression tester, one base particle is compressed with a smooth cylindrical indenter end face (diameter 50 μm, made of diamond) under the conditions of 25°C, a compression speed of 0.3 mN/sec, and a maximum test load of 20 mN. The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the compressive elastic modulus (10% K value) of the base particle can be calculated using the following formula. As the micro-compression tester, for example, Fischer Scope H-100 manufactured by Fischer is used. The compressive elastic modulus (10% K value) of the base particle is preferably calculated by arithmetic averaging of the compressive elastic modulus (10% K value) of 50 arbitrarily selected particles.

10% K value (N/mm ² ) = (3/2 ^1/2 ) · F · S ^{- 3/2} · R ^{- 1/2}
F: Load value (N) when the base particle is compressed and deformed by 10%
S: Compressive displacement (mm) when the base particle is compressed and deformed by 10%
R: Radius of base particle (mm)

The above compression modulus universally and quantitatively represents the hardness of the particles. By using the above compression modulus, the hardness of the base particle can be quantitatively and unambiguously represented.

From the viewpoint of effectively moving the conductive particles by a magnetic field or magnetic force and further reducing the connection resistance, it is preferable that the specific gravity of the base particle is lower than that of the conductive part. It is more preferable that the specific gravity of the base particle is 3 g/ ^cm3 or more lower than that of the conductive part. It is even more preferable that the specific gravity of the base particle is 5 g/ ^cm3 or more lower than that of the conductive part. In general, the specific gravity of the resin particles or organic hybrid particles is lower than that of the conductive part formed of a metal.

The conductive particles are suitable for use in conductive connections that apply a magnetic field or magnetic force. By applying a magnetic field or magnetic force during conductive connection, the conductive particles can be effectively moved onto or between electrodes.

The particle diameter of the conductive particles is preferably 0.1 μm or more, more preferably 1 μm or more, and preferably 1000 μm or less, more preferably 100 μm or less, and even more preferably 10 μm or less. If the particle diameter of the conductive particles is equal to or greater than the lower limit and equal to or less than the upper limit, when the conductive particles are used to connect electrodes, the contact area between the conductive particles and the electrodes becomes sufficiently large, and the conductive particles are less likely to aggregate when forming the conductive part. In addition, the gap between the electrodes connected via the conductive particles does not become too large, and the conductive part is less likely to peel off from the surface of the base particle.

The particle diameter of the conductive particles is preferably an average particle diameter, and is preferably a number average particle diameter. The particle diameter of the conductive particles is obtained, for example, by observing 50 arbitrary conductive particles with an electron microscope or optical microscope, and calculating the average value of the particle diameter of each conductive particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each conductive particle is obtained as a particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary conductive particles with a circle equivalent diameter is almost equal to the average particle diameter of a sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each conductive particle is obtained as a particle diameter of a sphere equivalent diameter. The average particle diameter of the conductive particles is preferably calculated using a particle size distribution measuring device. In terms of high measurement accuracy, the particle size distribution measuring device is preferably a laser diffraction type particle size distribution measuring device.

The coefficient of variation (CV value) of the particle diameter of the conductive particles is preferably 10% or less, more preferably 5% or less. When the coefficient of variation of the particle diameter of the conductive particles is equal to or less than the upper limit, the electrical conductivity reliability and insulation reliability between the electrodes can be more effectively improved.

The above coefficient of variation (CV value) can be measured as follows:

CV value (%) = (ρ/Dn) × 100
ρ: Standard deviation of the particle diameter of the conductive particles Dn: Average particle diameter of the conductive particles

The shape of the conductive particles is not particularly limited. The conductive particles may be spherical, may be non-spherical, or may be flat, etc.

The present invention will be described in detail below with reference to the drawings. Note that different parts in FIG. 1 and the figures described below can be interchanged.

Figure 1 is a cross-sectional view showing a conductive particle according to a first embodiment of the present invention.

The conductive particle 1 shown in FIG. 1 has a base particle 2 and a conductive portion 3. The conductive portion 3 is disposed on the surface of the base particle 2. In the first embodiment, the conductive portion 3 is in contact with the surface of the base particle 2. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive portion 3.

In the conductive particle 1, the conductive portion 3 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 a portion of the surface of the base particle. In the conductive particle, the conductive portion may be a single-layer conductive layer, or a multi-layer conductive layer composed of two or more layers.

Conductive particle 1 does not have a core material, unlike conductive particles 11 and 21 described later. Conductive particle 1 does not have protrusions on its surface. Conductive particle 1 is spherical. Conductive portion 3 does not have protrusions on its outer surface. In this way, the conductive particle according to the present invention may not have protrusions on its conductive surface and may be spherical. Also, conductive particle 1 does not have an insulating material, unlike conductive particles 11 and 21 described later. However, conductive particle 1 may have an insulating material disposed on the outer surface of conductive portion 3.

Figure 2 is a cross-sectional view showing a conductive particle according to a second embodiment of the present invention.

The conductive particle 11 shown in FIG. 2 has a base particle 2, a conductive portion 12, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 12 is disposed on the surface of the base particle 2 so as to be in contact with the base particle 2.

In the conductive particle 11, the conductive portion 12 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 a portion of the surface of the base particle. In the conductive particle, the conductive portion may be a single-layer conductive layer, or a multi-layer conductive layer composed of two or more layers.

The conductive particle 11 has a plurality of protrusions 11a on its conductive surface. The conductive portion 12 has a plurality of protrusions 12a on its outer surface. A plurality of core substances 13 are disposed on the surface of the base particle 2. The plurality of core substances 13 are embedded in the conductive portion 12. The core substances 13 are disposed inside the protrusions 11a, 12a. The conductive portion 12 covers the plurality of core substances 13. The outer surface of the conductive portion 12 is raised by the plurality of core substances 13, forming the protrusions 11a, 12a.

The conductive particle 11 has an insulating material 14 disposed on the outer surface of the conductive portion 12. At least a portion of the outer surface of the conductive portion 12 is covered with the insulating material 14. The insulating material 14 is formed from a material having insulating properties, and is an insulating particle. In this way, the conductive particle according to the present invention may have an insulating material disposed on the outer surface of the conductive portion. However, the conductive particle according to the present invention does not necessarily have to have an insulating material.

Figure 3 is a cross-sectional view showing a conductive particle according to a third embodiment of the present invention.

The conductive particle 21 shown in FIG. 3 has a base particle 2, a conductive portion 22, a plurality of core materials 13, and a plurality of insulating materials 14. The conductive portion 22 as a whole has a first conductive portion 22A on the base particle 2 side and a second conductive portion 22B on the opposite side to the base particle 2 side.

The only difference between conductive particle 11 and conductive particle 21 is the conductive portion. That is, conductive particle 11 has conductive portion 12 with a single layer structure, whereas conductive particle 21 has first conductive portion 22A and second conductive portion 22B with a two-layer structure. First conductive portion 22A and second conductive portion 22B are formed as separate conductive portions.

The first conductive portion 22A is disposed on the surface of the base particle 2. The first conductive portion 22A is disposed between the base particle 2 and the second conductive portion 22B. The first conductive portion 22A is in contact with the base particle 2. The second conductive portion 22B is in contact with the first conductive portion 22A. Thus, the first conductive portion 22A is disposed on the surface of the base particle 2, and the second conductive portion 22B is disposed on the surface of the first conductive portion 22A. The conductive particle 21 has a plurality of protrusions 21a on its conductive surface. The conductive portion 22 has a plurality of protrusions 22a on its outer surface. The first conductive portion 22A has a plurality of protrusions 22Aa on its outer surface. The second conductive portion 22B has a plurality of protrusions 22Ba on its outer surface.

Figure 4 is a cross-sectional view showing a conductive particle according to a fourth embodiment of the present invention.

The conductive particle 31 shown in FIG. 4 is a conductive particle that does not have the insulating particles 14 in the conductive particle 21 shown in FIG. 3. The conductive particle 31 is configured in the same manner as the conductive particle 21, except that it does not have the insulating particles. The conductive particle does not necessarily have to have an insulating material.

Further details about the conductive particles are described below.

(Base particle)
The material of the base particle is not particularly limited. The material of the base particle may be an organic material or an inorganic material. Examples of the base particle formed only from the organic material include resin particles. Examples of the base particle formed only from the inorganic material include inorganic particles other than metals. Examples of the base particle formed from both the organic material and the inorganic material include organic-inorganic hybrid particles. From the viewpoint of further reducing the initial connection resistance and further increasing the conduction reliability, the base particle is preferably a resin particle or an organic-inorganic hybrid particle, and more preferably a resin particle.

From the viewpoint of further suppressing damage to the electrodes and effectively lowering the connection resistance, it is preferable that the base particles are not metal particles.

The organic materials 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, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, polyether ether ketone, polyether sulfone, divinylbenzene polymer, and divinylbenzene copolymer. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene-(meth)acrylic acid ester copolymer. Since the compression characteristics of the base particles can be easily controlled within a suitable range, it is preferable that the material of the base particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group.

When the base 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.

Examples of the non-crosslinkable monomers include vinyl compounds such as styrene monomers, α-methylstyrene, and chlorostyrene; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; acid vinyl ester compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; halogen-containing monomers such as vinyl chloride and vinyl fluoride; (meth)acrylic 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 Examples of suitable (meth)acrylates include alkyl (meth)acrylate compounds such as (meth)acrylate and isobornyl (meth)acrylate; oxygen-containing (meth)acrylate compounds such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; nitrile-containing monomers such as (meth)acrylonitrile; halogen-containing (meth)acrylate compounds such as trifluoromethyl (meth)acrylate and pentafluoroethyl (meth)acrylate; α-olefin compounds include olefin compounds such as diisobutylene, isobutylene, linearene, ethylene, and propylene; and conjugated diene compounds include isoprene and butadiene.

The crosslinkable monomers include vinyl compounds such as vinyl monomers like divinylbenzene, 1,4-divinyloxybutane, and divinylsulfone; (meth)acrylic compounds such as tetramethylolmethane tetra(meth)acrylate, polytetramethylene glycol diacrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol dimethacrylate, ... Polyfunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; allyl compounds such as triallyl (iso)cyanurate, triallyl trimellitate, diallyl phthalate, diallyl acrylamide, and diallyl ether; silane compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethylenediamine, and the like. silane alkoxide compounds such as acryloxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, trimethoxysilylstyrene, γ-(meth)acryloxypropyltrimethoxysilane, 1,3-divinyltetramethyldisiloxane, methylphenyldimethoxysilane, and diphenyldimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, dimethoxyethylvinylsilane, diethoxymethylvinylsilane, diethoxyethylvinylsilane, ethylmethyldivinylsilane, methylvinyldimethoxysilane, and ethylvinyldimethoxysilane; Examples of such silane alkoxides include silane alkoxides containing polymerizable double bonds, such as silane, methylvinyldiethoxysilane, ethylvinyldiethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane; cyclic siloxanes, such as decamethylcyclopentasiloxane; modified (reactive) silicone oils, such as one-end modified silicone oil, both-end silicone oil, and side-chain silicone oil; and carboxyl group-containing monomers, such as (meth)acrylic acid, maleic acid, and maleic anhydride.

The base particles can be obtained by polymerizing the polymerizable monomer having the ethylenically unsaturated group. The polymerization method is not particularly limited, and examples thereof include known methods such as radical polymerization, ionic polymerization, polycondensation (condensation polymerization, polycondensation), addition condensation, living polymerization, and living radical polymerization. Another polymerization method is suspension polymerization in the presence of a radical polymerization initiator.

The above inorganic materials include silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass.

The base particle may be an organic-inorganic hybrid particle. The base particle may be a core-shell particle. When the base particle is an organic-inorganic hybrid particle, examples of the inorganic material of the base particle include silica, alumina, barium titanate, zirconia, and carbon black. The inorganic material is preferably not a metal. The base particle formed from silica is not particularly limited, but examples include base particles obtained by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, and then baking the resulting particles as necessary. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

The organic-inorganic hybrid particles are preferably core-shell type 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. 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.

Examples of the organic core material include the organic materials described above.

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 material from a metal alkoxide on the surface of the core by a sol-gel method, and then firing the shell-like material. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed from a silane alkoxide.

The particle diameter of the base particle can be selected in consideration of the particle diameter of the conductive particles. The particle diameter of the base particle is preferably 0.1 μm or more, more preferably 1 μm or more. The particle diameter of the base particle is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, even more preferably 50 μm or less, even more preferably 10 μm or less, and particularly preferably 3 μm or less. When the particle diameter of the base particle is equal to or greater than the lower limit, the contact area between the conductive particle and the electrode is increased, so that the reliability of conduction between the electrodes can be further improved, and the connection resistance between the electrodes connected via the conductive particle can be further reduced. Furthermore, when forming a conductive portion on the surface of the base particle by electroless plating, it is possible to make it difficult for aggregated conductive particles to be formed. When the particle diameter of the base particle is equal to or less than the upper limit, the conductive particles are easily compressed sufficiently, the connection resistance between the electrodes can be further reduced, and the gap between the electrodes can be further reduced.

It is particularly preferable that the particle diameter of the base particles is 1 μm or more and 3 μm or less. If the particle diameter of the base particles is within the range of 1 μm or more and 3 μm or less, the base particles are less likely to aggregate when forming the conductive portion on the surface of the base particles, and aggregated conductive particles are less likely to be formed.

The particle diameter of the base particles is preferably an average particle diameter, and is preferably a number average particle diameter. The particle diameter of the base particles is obtained by observing 50 arbitrary base particles with an electron microscope or optical microscope, calculating the average value of the particle diameter of each base particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each base particle is obtained as a particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary base particles with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each base particle is obtained as a particle diameter of a sphere equivalent diameter. The average particle diameter of the base particles is preferably calculated using a particle size distribution measuring device. In terms of high measurement accuracy, the particle size distribution measuring device is preferably a laser diffraction type particle size distribution measuring device. When measuring the particle diameter of the base particles in the conductive particles, for example, it can be measured as follows.

The conductive particles are added to Kulzer's Technovit 4000 so that the conductive particle content is 30% by weight, and dispersed to prepare a conductive particle testing embedding resin. An ion milling device (Hitachi High-Technologies' IM4000) is used to cut out a cross section of the conductive particles so that it passes through the center of the conductive particles dispersed in the testing embedding resin. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 25,000 times, 50 conductive particles are randomly selected, and the base particle of each conductive particle is observed. The particle diameter of the base particle in each conductive particle is measured, and the arithmetic average of these is taken to determine the particle diameter of the base particle.

(Conductive part)
The conductive particle according to the present invention includes a base particle and a conductive portion disposed on the surface of the base particle. The conductive portion preferably contains a metal. In order to control the saturation magnetization within a suitable range, a suitable metal is used to constitute the conductive portion.

Examples of metals constituting the conductive portion include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, tungsten, molybdenum, and alloys thereof. Examples of metals constituting the conductive portion include tin-doped indium oxide (ITO) and solder. Only one type of metal may be used as the conductive portion, or two or more types may be used in combination.

From the viewpoint of more easily controlling the saturation magnetization amount to a suitable range, it is preferable that the conductive portion contains nickel, cobalt, or iron. In this case, the conductive layer may contain only one of nickel, cobalt, and iron, or may contain two or more of them. The conductive portion may contain nickel, or may not contain nickel. It is preferable that the conductive portion contains at least two of nickel, cobalt, and iron. The conductive portion may contain cobalt, or may not contain cobalt. The conductive portion may contain iron, or may not contain iron.

From the viewpoint of more easily controlling the saturation magnetization amount within a suitable range, the total content of nickel, cobalt and iron in the conductive portion (100% by weight) is preferably 90% by weight or more, more preferably 95% by weight or more, even more preferably 98% by weight or more, and preferably 100% by weight or less.

From the viewpoint of more easily controlling the saturation magnetization amount to a suitable range, when the conductive portion contains nickel, the nickel content in 100% by weight of the conductive portion is preferably 5% by weight or more, more preferably 50% by weight or more, even more preferably 98% by weight or more, and preferably 100% by weight or less.

From the viewpoint of more easily controlling the saturation magnetization amount within a suitable range, when the conductive portion contains cobalt, the content of cobalt in 100% by weight of the conductive portion is preferably 5% by weight or more, more preferably 50% by weight or more, even more preferably 98% by weight or more, and preferably 100% by weight or less.

From the viewpoint of more easily controlling the saturation magnetization amount to a suitable range, when the conductive portion contains iron, the iron content in 100% by weight of the conductive portion is preferably 5% by weight or more, more preferably 50% by weight or more, even more preferably 98% by weight or more, and preferably 100% by weight or less.

From the viewpoint of more easily controlling the saturation magnetization amount to a suitable range, when the conductive part contains at least two of nickel, cobalt, and iron, the content of one of the nickel content, the cobalt content, and the iron content in 100% by weight of the conductive part is defined as the content (A). From the viewpoint of more easily controlling the saturation magnetization amount to a suitable range, the content (A) is preferably 51% by weight or more, more preferably 55% by weight or more, and even more preferably 60% by weight or more, and is preferably less than 100% by weight, and more preferably 99% by weight or less. The content (A) corresponds to the largest content of the nickel content, the cobalt content, and the iron content in 100% by weight of the conductive part.

In addition, hydroxyl groups are often present on the surface of the conductive part due to oxidation. Generally, hydroxyl groups are present on the surface of a conductive part made of nickel due to oxidation. An insulating material can be placed on the surface of such a conductive part (surface of a conductive particle) that has hydroxyl groups via chemical bonding.

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, it is preferable that the metal constituting the outermost layer contains nickel, cobalt, or iron.

The method for forming the conductive portion on the surface of the base particle is not particularly limited. Examples of the method for forming the conductive portion include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and a method for 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 a physical collision method. Examples of the physical vapor deposition method include vacuum vapor deposition, ion plating, and ion sputtering. Examples of the physical collision method include a sheeter composer (manufactured by Tokuju Kosakusho Co., Ltd.).

The thickness of the conductive part 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 0.3 μm or less. The thickness of the conductive part is the thickness of the entire conductive part when the conductive part is multi-layered. When the thickness of the conductive part is equal to or more than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles can be sufficiently deformed when connecting between the electrodes.

From the viewpoint of more easily controlling the amount of saturation magnetization within a suitable range, the thickness of the conductive portion is preferably 0.01 μm or more, more preferably 0.05 μm or more, and is preferably 5 μm or less, more preferably 1 μm or less.

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 0.1 μm or less. When the thickness of the conductive portion of the outermost layer is equal to or greater than the lower limit and equal to or less than the upper limit, the coating by the conductive portion of the outermost layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes can be sufficiently low.

The thickness of the conductive part can be measured by observing the cross section of the conductive particle, for example, using a transmission electron microscope (TEM). It is preferable to calculate the thickness of the conductive part as the average value of the thicknesses of five arbitrary conductive parts as the thickness of the conductive part of one conductive particle, and it is more preferable to calculate the average value of the thickness of the entire conductive part as the thickness of the conductive part of one conductive particle. It is preferable to determine the thickness of the conductive part by calculating the average thickness of the conductive part of each of 10 arbitrary conductive particles.

The nickel, cobalt, and iron contents can be measured using a high-frequency inductively coupled plasma optical emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer ("EDX-800HS" manufactured by Shimadzu Corporation).

(Core material and protrusions)
The conductive particles preferably have protrusions on the outer surface of the conductive part. The number of protrusions is preferably multiple. An oxide film is often formed on the surface of the electrodes connected by the conductive particles. When conductive particles having protrusions on the surface of the conductive part are used, the oxide film can be effectively removed by the protrusions by arranging the conductive particles between the electrodes and pressing them together. Therefore, the electrodes and the conductive part are in more reliable contact, and the connection resistance between the electrodes is further reduced. Furthermore, when the conductive particles have an insulating material, or when the conductive particles are dispersed in a binder resin and used as a conductive material, the protrusions of the conductive particles can more effectively remove the insulating material or binder resin between the conductive particles and the electrodes. Therefore, the connection resistance between the electrodes can be further reduced.

It is preferable that the conductive particles have a plurality of core materials that raise the surface of the conductive portion within the conductive portion to form a plurality of the protrusions within the conductive portion.

Methods for forming the protrusions include a method in which a core material is attached to the surface of a base particle, and then a conductive portion is formed by electroless plating, and a method in which a conductive portion is formed on the surface of a base particle by electroless plating, and then a core material is attached, and then a conductive portion is formed by electroless plating. In addition, the core material does not have to be used to form the protrusions.

Other methods for forming the protrusions include adding a core substance during the process of forming a conductive portion on the surface of the base particle. Alternatively, to form the protrusions, a method may be used in which, without using the core substance, a conductive portion is formed on the base particle by electroless plating, a protrusion-like plating is deposited on the surface of the conductive portion, and the conductive portion is then formed by electroless plating.

Methods for attaching a core substance to the surface of a base particle include a method in which a core substance is added to a dispersion of the base particle, and the core substance is accumulated and attached to the surface of the base particle by van der Waals forces, and a method in which a core substance is added to a container containing the base particle, and the core substance is attached to the surface of the base particle by mechanical action such as rotating the container. From the viewpoint of controlling the amount of core substance to be attached, the method for attaching a core substance to the surface of a base particle is preferably a method in which the core substance is accumulated and attached to the surface of the base particle in the dispersion.

Materials constituting the core material include conductive materials and non-conductive materials. Examples of the conductive materials include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymers include polyacetylene. Examples of the non-conductive materials include silica, alumina, and zirconia. From the viewpoint of more effectively removing the oxide film, it is preferable that the core material is hard. From the viewpoint of more effectively lowering the connection resistance between the electrodes, it is preferable that the core material is a metal.

The metal is not particularly limited. 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. From the viewpoint of more effectively lowering the connection resistance between the electrodes, the metal is preferably nickel, copper, silver, or gold. The metal may be the same as or different from the metal constituting the conductive portion (conductive layer).

The shape of the core substance is not particularly limited. The core substance is preferably in the form of a mass. Examples of the core substance include particulate masses, aggregates of multiple microparticles, and amorphous masses.

The particle diameter of the core material is preferably 0.001 μm or more, more preferably 0.05 μm or more, and is preferably 0.9 μm or less, more preferably 0.2 μm or less. When the particle diameter of the core material 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 reduced more effectively.

The particle diameter of the core material is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the core material is determined by observing 50 arbitrary core materials with an electron microscope or optical microscope and calculating the average particle diameter of each core material, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each core material is determined as the particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary core materials with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each core material is determined as the particle diameter of a sphere equivalent diameter. The average particle diameter of the core material is preferably calculated using a particle size distribution measuring device. In terms of high measurement accuracy, the particle size distribution measuring device is preferably a laser diffraction type particle size distribution measuring device.

From the viewpoint of further reducing the initial connection resistance and further increasing the reliability of electrical continuity under high temperature and high humidity, the surface area of the portion where the protrusions are present is preferably 25% or more, more preferably 30% or more, and even more preferably 50% or more of the total surface area of the outer surface of the conductive part, which is 100%. The surface area of the portion where the protrusions are present may be 95% or less, 90% or less, or 80% or less.

The number of protrusions per conductive particle is preferably 3 or more, and more preferably 5 or more. There is no particular upper limit to the number of protrusions. The upper limit of the number of protrusions can be appropriately selected taking into account the particle diameter of the conductive particles, etc. When the number of protrusions is equal to or greater than the lower limit, the connection resistance between the electrodes can be reduced even more effectively.

The number of protrusions can be calculated by observing any conductive particle with an electron microscope or optical microscope. It is preferable to determine the number of protrusions by observing 50 conductive particles with an electron microscope or optical microscope and calculating the average number of protrusions on each conductive particle.

The height of the protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, and is preferably 0.9 μm or less, more preferably 0.2 μm or less. If the 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 reduced even more effectively.

The height of the protrusions can be calculated by observing the protrusions of any conductive particle with an electron microscope or optical microscope. The height of the protrusions is preferably calculated by taking the average value of the heights of all the protrusions per conductive particle as the height of the protrusions of one conductive particle. The height of the protrusions is preferably determined by calculating the average value of the height of the protrusions of each conductive particle for 50 arbitrary conductive particles.

(Insulating material)
From the viewpoint of further increasing the conductivity, the conductive particles may not have an insulating material disposed on the outer surface of the conductive part. From the viewpoint of further increasing the insulation reliability, the conductive particles preferably have an insulating material disposed on the outer surface of the conductive part. In this case, when the conductive particles are used for connecting electrodes, short-circuiting between adjacent electrodes can be prevented more effectively. Specifically, when a plurality of conductive particles contact each other, an insulating material exists between the plurality of electrodes, so that short-circuiting between adjacent electrodes in the horizontal direction, rather than between upper and lower electrodes, can be prevented. In addition, when connecting the electrodes, the insulating material between the conductive part of the conductive particles and the electrodes can be easily removed by pressing the conductive particles with two electrodes. Furthermore, when the conductive particles have protrusions on the outer surface of the conductive part, the insulating material between the conductive part of the conductive particles and the electrodes can be more easily removed.

The insulating material may be an insulating layer or insulating particles. It is preferable that the insulating material is insulating particles, since this makes it easier to remove the insulating material when the electrodes are pressed together.

The insulating material may be the organic material described above, the inorganic material described above, or the inorganic material described above as the material for the base particle. The insulating material is preferably the organic material described above.

Other examples of the insulating material include polyolefin compounds, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, thermosetting resins, and water-soluble resins. Only one type of insulating material may be used, or two or more types may be used in combination.

The polyolefin compounds include polyethylene, ethylene-vinyl acetate copolymers, and ethylene-acrylic acid ester copolymers. The (meth)acrylate polymers include polymethyl (meth)acrylate, polydodecyl (meth)acrylate, and polystearyl (meth)acrylate. The block polymers include polystyrene, styrene-acrylic acid ester copolymers, SB-type styrene-butadiene block copolymers, and SBS-type styrene-butadiene block copolymers, as well as hydrogenated products thereof. The thermoplastic resins include vinyl polymers and vinyl copolymers. The thermosetting resins include epoxy resins, phenolic resins, and melamine resins. The crosslinked thermoplastic resins include polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, and alkoxylated pentaerythritol methacrylate. The water-soluble resins include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methylcellulose. A chain transfer agent may be used to adjust the degree of polymerization. Examples of the chain transfer agent include thiol and carbon tetrachloride.

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

The outer surface of the conductive part and the outer surface of the insulating material may each be coated with a compound having a reactive functional group. The outer surface of the conductive part and the outer surface of the insulating material may not be directly chemically bonded, but may be indirectly chemically bonded via a compound having a reactive functional group. After a carboxyl group is introduced onto the outer surface of the conductive part, the carboxyl group may be chemically bonded to a functional group on the outer surface of the insulating material via a polymer electrolyte such as polyethyleneimine.

When the insulating material is an insulating particle, the particle diameter of the insulating particle can be appropriately selected depending on the particle diameter of the conductive particle and the use of the conductive particle. The particle diameter of the insulating particle is preferably 10 nm or more, more preferably 100 nm or more, even more preferably 300 nm or more, particularly preferably 500 nm or more, and preferably 4000 nm or less, more preferably 2000 nm or less, even more preferably 1500 nm or less, particularly preferably 1000 nm or less. If the particle diameter of the insulating particle is equal to or greater than the lower limit, when the conductive particle is dispersed in the binder resin, the conductive parts of the multiple conductive particles are less likely to contact each other. If the particle diameter of the insulating particle is equal to or less than the upper limit, it is not necessary to apply too much pressure or heat to a high temperature in order to remove the insulating particles between the electrodes and the conductive particles when connecting the electrodes.

The particle diameter of the insulating particles is preferably an average particle diameter, and is preferably a number average particle diameter. The particle diameter of the insulating particles is obtained by observing 50 arbitrary insulating particles with an electron microscope or optical microscope, calculating the average value of the particle diameter of each insulating particle, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle diameter of each insulating particle is obtained as a particle diameter of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle diameter of 50 arbitrary insulating particles with a circle equivalent diameter is almost equal to the average particle diameter of a sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each insulating particle is obtained as a particle diameter of a sphere equivalent diameter. The average particle diameter of the insulating particles is preferably calculated using a particle size distribution measuring device. When the particle diameter of the insulating particles in the conductive particles is measured, it can be measured, for example, as follows.

Conductive particles are added to Kulzer's Technovit 4000 so that the content is 30% by weight, and dispersed to prepare a resin for embedding conductive particles for testing. An ion milling device (Hitachi High-Technologies' IM4000) is used to cut out a cross section of the conductive particles so that it passes through the center of the dispersed conductive particles in the resin for testing. Then, using a field emission scanning electron microscope (FE-SEM) with an image magnification set to 50,000 times, 50 conductive particles are randomly selected and the insulating particles of each conductive particle are observed. The particle diameter of the insulating particles in each conductive particle is measured, and the particle diameter of the insulating particles is determined by arithmetic averaging.

The ratio of the particle diameter of the conductive particles to the particle diameter of the insulating particles (particle diameter of conductive particles/particle diameter of insulating particles) is preferably 4 or more, more preferably 8 or more, and preferably 200 or less, more preferably 100 or less. When the ratio (particle diameter of conductive particles/particle diameter of insulating particles) is equal to or more than the lower limit and equal to or less than the upper limit, the insulation reliability and conduction reliability can be more effectively improved when the electrodes are electrically connected.

(Conductive materials)
The conductive material according to the present invention includes the conductive particles 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, the connection resistance between electrodes can be more effectively reduced, and the occurrence of aggregation between the conductive particles can be more effectively suppressed. Since the conductive material uses the conductive particles described above, the insulation reliability between the electrodes can be more effectively improved.

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.

The binder resin may be a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, an elastomer, or the like. Only one type of the binder resin may be used, or two or more types may be used in combination.

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, hydrogenated styrene-butadiene-styrene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

From the viewpoint of increasing the placement accuracy of the conductive particles and effectively reducing the connection resistance, it is preferable that the binder resin contains a thermosetting compound having a glycidyl group or a (meth)acryloyl group. The thermosetting compound may have a glycidyl group or a (meth)acryloyl group.

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, UV absorbers, lubricants, antistatic agents, and flame retardants.

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 with 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, and then added to the binder resin, and then kneaded and dispersed with a planetary mixer or the like. A method in which the binder resin is diluted with water or an organic solvent, and then the conductive particles are added, and then kneaded and dispersed with a planetary mixer or the like.

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 more than the lower limit and equal to or less than the upper limit, the insulation reliability between the electrodes can be more effectively improved, and the conduction reliability between the electrodes can be more effectively improved. The viscosity (η25) can be appropriately adjusted by the types and amounts of the blended components.

The above viscosity (η25) can be measured, for example, using an E-type viscometer (Toki Sangyo Co., Ltd.'s "TVE22L") at 25°C and 5 rpm.

The conductive material according to the present invention can be used as a conductive paste, a conductive film, and the like. When the conductive material according to the present invention is a conductive film, a film that does not contain conductive particles may be laminated on a conductive film that contains conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

In 100% by weight of the conductive material, the content of the binder resin 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.

In addition, by applying a magnetic field or magnetic force X when mixing the binder resin and the particles, the conductive particles can be concentrated at any desired position, producing a conductive material in which the conductive particles are arranged at specific locations.

The step of applying the magnetic field or magnetic force may be carried out after mixing the binder resin and the particles.

In 100% by weight of the conductive material, the content of the conductive particles 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 greater than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes can be more effectively reduced. When the content of the conductive particles is equal to or greater than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability and insulation reliability between the electrodes can be more effectively improved.

(Connection structure and method for manufacturing the connection structure)
The connection structure according to the present invention includes 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 part 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 part is the conductive particles described above, or a conductive material containing the conductive particles and a binder resin. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive particles.

The connection structure can be obtained through a process of disposing the conductive particles or the conductive material between the first connection target member and the second connection target member, and a process of conductively connecting the conductive particles or the conductive material by thermocompression bonding. When the conductive particles have the insulating material, it is preferable that the insulating material is detached from the conductive particles during the thermocompression bonding.

When the conductive particles are used alone, the connection portion itself is a conductive particle. That is, the first connection target member and the second connection target member are connected by the conductive particles. The conductive material used to obtain the connection structure is preferably an anisotropic conductive material.

The method for manufacturing a connection structure according to the present invention includes a first arrangement step of arranging the conductive particles described above or arranging a conductive material containing the conductive particles and a binder resin on the surface of a first connection target member having a first electrode on its surface. The method for manufacturing a connection structure according to the present invention includes a second arrangement step of arranging a second connection target member having a second electrode on its surface on the opposite side of the conductive particles or conductive material to the first connection target member. The method for manufacturing a connection structure according to the present invention includes a step of applying a magnetic field or magnetic force before or after the second arrangement step. The method for manufacturing a connection structure according to the present invention obtains a connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

Figure 5 is a front cross-sectional view that shows a schematic diagram of a connection structure using conductive particles according to a first embodiment of the present invention.

The connection structure 51 shown in FIG. 5 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second connection target members 52 and 53. The connection portion 54 is formed by hardening a conductive material containing conductive particles 1. Note that in FIG. 5, the conductive particles 1 are shown in a simplified diagram for convenience of illustration. Instead of the conductive particles 1, other conductive particles such as conductive particles 11 and 21 may be used.

The first connection target member 52 has a plurality of first electrodes 52a on its surface (upper surface). The second connection target member 53 has a plurality of second electrodes 53a on its surface (lower surface). The first electrode 52a and the second electrode 53a are electrically connected by one or more conductive particles 1. Therefore, the first and second connection target members 52 and 53 are electrically connected by the conductive particles 1.

The connection structure 51 can be obtained, for example, as follows:

A first connection target member 52 having a first electrode 52a on its surface (upper surface) is prepared. As shown in FIG. 6(a), a conductive material 61 is placed on the surface of the first connection target member 52 on which the first electrode 52a is provided (first placement process). The conductive material 61 includes conductive particles 1. After the conductive material 61 is placed, the conductive particles 1 are placed both on the first electrode 52a (line) and on the area (space) where the first electrode 52a is not formed.

Methods for disposing the conductive material include, but are not limited to, application with a dispenser, screen printing, and ejection with an inkjet device.

A second connection target member 53 having a second electrode 53a on its surface (lower surface) is prepared. Next, as shown in FIG. 6(b), in the conductive material 61 on the surface of the first connection target member 52, a second connection target member 53 is placed on the surface of the conductive material 61 (or conductive particles 1) opposite the first connection target member 52 (second placement process). The second connection target member 53 is placed on the surface of the conductive material 61 from the second electrode 53a side. At this time, the first electrode 52a and the second electrode 53a are opposed to each other.

As shown in FIG. 6(c), a magnetic field or magnetic force X is applied in the second arrangement step. It is preferable to apply the magnetic field or magnetic force to the first electrode 52a portion. It is preferable to apply the magnetic field or magnetic force to the second electrode 53a portion. By applying the magnetic field or magnetic force, the conductive particles 1 are gathered on the first electrode 52a. Furthermore, by applying the magnetic field or magnetic force, the conductive particles 1 are gathered between the first electrode 52a and the second electrode 53a. As a result, the number of conductive particles 1 arranged between the first electrode 52a and the second electrode 53a increases.

From the state shown in FIG. 6(c), a thermocompression bonding process can be performed to obtain the connection structure 51 shown in FIG. 5.

Alternatively, the connection structure 51 can be obtained, for example, as follows:

A first connection target member 52 having a first electrode 52a on its surface (upper surface) is prepared. As shown in FIG. 7(a), a conductive material 61 is placed on the surface of the first connection target member 52 on which the first electrode 52a is provided (first placement process). The conductive material 61 includes conductive particles 1. After the conductive material 61 is placed, the conductive particles 1 are placed both on the first electrode 52a (line) and on the area (space) where the first electrode 52a is not formed.

As shown in FIG. 7(b), a magnetic field or magnetic force X is applied in the first arrangement step. By applying the magnetic field or magnetic force, the conductive particles 1 gather on the first electrode 52a. As a result, the number of conductive particles 1 arranged on the first electrode 52a increases.

A second connection target member 53 having a second electrode 53a on its surface (lower surface) is prepared. Next, as shown in FIG. 7(c), in the conductive material 61 on the surface of the first connection target member 52, a second connection target member 53 is placed on the surface of the conductive material 61 (or conductive particles 1) opposite the first connection target member 52 (second placement process). The second connection target member 53 is placed on the surface of the conductive material 61 from the second electrode 53a side. At this time, the first electrode 52a and the second electrode 53a are opposed to each other.

From the state shown in FIG. 7(c), a thermocompression bonding process can be performed to obtain the connection structure 51 shown in FIG. 5.

The step of applying the magnetic field or magnetic force may be performed before the first arrangement step or before the second arrangement step, or may be performed after the second arrangement step. From the viewpoint of further improving the arrangement accuracy of the conductive particles, it is preferable that the step of applying the magnetic field or magnetic force is performed before the first arrangement step or after the second arrangement step.

After the second arrangement step and the step of applying the magnetic field or magnetic force, it is preferable to carry out a thermocompression bonding step. By thermocompression bonding a laminate of the first connection target member, conductive particles or conductive material, and the second connection target member, a connection structure with excellent connection reliability can be obtained.

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 temperature of the thermocompression bonding are equal to or greater than the lower limit and equal to or less than the upper limit, the electrical conductivity reliability and insulating reliability between the electrodes can be further improved. In addition, when the conductive particles have the insulating particles, the insulating particles can be easily detached from the surface of the conductive particles during conductive connection.

When the conductive particles have the insulating particles, the insulating particles present between the conductive particles and the first and second electrodes can be eliminated when the laminate is heated and pressurized. For example, when the laminate is heated and pressurized, the insulating particles present between the conductive particles and the first and second electrodes are easily detached from the surface of the conductive particles. When the laminate is heated and pressurized, some of the insulating particles may be detached from the surface of the conductive particles, causing the surface of the conductive part to be partially exposed. The exposed part of the surface of the conductive part comes into contact with the first and second electrodes, thereby electrically connecting the first and second electrodes through the conductive particles.

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. It is preferable that the first and second connection target members are electronic components.

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

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

Example 1
(1) Preparation of Conductive Particles As base particles A, divinylbenzene copolymer resin particles ("Micropearl SP-203, particle diameter 3 μm" manufactured by Sekisui Chemical Co., Ltd.) were prepared.

10 parts by weight of base particles A were dispersed in 100 parts by weight of an alkaline solution containing 5% by weight of palladium catalyst liquid using an ultrasonic disperser, and the solution was filtered to extract base particles A. Next, base particles A were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of base particles A. The base particles A with activated surfaces were thoroughly washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain suspension (1A).

One part by weight of metallic nickel slurry (average particle diameter 150 nm) was added to the above suspension (1A) over a period of 3 minutes to obtain a particle mixture suspension (1B) containing base particles A to which a core substance was attached.

A nickel plating solution (2) (pH 10) was also prepared, containing 50 g/L of nickel sulfamate, 70 g/L of glycine, 30 g/L of boric acid, and 300 g/L of hydrazine sulfate.

While stirring the suspension (1B) at 80°C, the nickel plating solution (2) was gradually added dropwise to perform electroless pure nickel plating. The mixture was then stirred until the pH stabilized, and the hydrogen bubbling was confirmed to have stopped, yielding the suspension (3) after electroless pure nickel plating.

Then, the suspension (3) was filtered to extract the particles, which were then washed with water and dried. Conductive particles were obtained in which a conductive portion (thickness 51 nm) of high purity Ni was disposed on the outer surface of the base particle. These conductive particles comprise metallic nickel particles as the core material.

Example 2
Conductive particles were obtained in the same manner as in Example 1, except that the thickness of the conductive layer was changed from 51 nm to 80 nm.

Example 3
The same suspension (1B) as in Example 1 was placed in a solution containing 25 g/L of nickel sulfate, 15 ppm of thallium nitrate, and 10 ppm of bismuth nitrate to obtain a particle mixture (4).

A boron-containing nickel plating solution (5) (pH 8.0) was also prepared, containing 100 g/L nickel sulfate, 30 g/L dimethylamine borane, 15 g/L sodium citrate, 25 ppm thallium nitrate, and 10 ppm bismuth nitrate.

While stirring the particle mixture (4) at 60°C, the boron-containing nickel plating solution (5) was gradually added dropwise to perform electroless nickel plating. The mixture was then stirred until the pH stabilized, and the suspension after electroless boron-containing nickel plating (6) was obtained.

Then, the suspension (6) was filtered, washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension (7) of boron-containing nickel-plated particles.

Furthermore, by performing electroless pure nickel plating in the same manner as in Example 1, conductive particles were obtained in which a conductive portion (thickness 19 nm) of boron-containing Ni was arranged on the surface of the base particle, and a conductive portion (thickness 51 nm) of high-purity Ni was arranged on the outer surface.

Example 4
Conductive particles were obtained in the same manner as in Example 1, except that electroless nickel plating was performed using suspension (1A) to obtain conductive particles without a core material, and the thickness of the conductive layer was changed from 51 nm to 55 nm.

Example 5
Conductive particles were obtained in the same manner as in Example 1, except that the metallic nickel particle slurry was changed to a titanium oxide particle slurry (average particle diameter 150 nm) and the thickness of the conductive layer was changed from 51 nm to 52 nm. The conductive particles comprise titanium oxide particles as a core material.

Example 6
Except for changing the metallic nickel particle slurry to an alumina particle slurry (average particle diameter: 150 nm), conductive particles were obtained in the same manner as in Example 1. The conductive particles include alumina particles as a core material.

(Example 7)
The same suspension (1B) as in Example 1 was placed in a solution containing 20 g/L of cobalt sulfate and 20 g/L of sodium citrate to obtain a particle mixture (9).

A boron-containing cobalt plating solution (10) (pH 8.0) containing 70 g/L of cobalt sulfate, 50 g/L of dimethylamine borane, and 60 g/L of sodium citrate was also prepared.

While stirring the particle mixture (9) at 60°C, the boron-containing cobalt plating solution (10) was gradually added dropwise to perform electroless cobalt plating. The mixture was then stirred until the pH stabilized, and the bubbling was confirmed to have stopped, yielding a suspension (11) after electroless boron-containing cobalt plating.

Then, the suspension (11) was filtered, washed with water, and dried to obtain conductive particles in which the conductive portion of Co-B (thickness 55 nm) was arranged on the outer surface of the base particle.

(Example 8)
The same suspension (1B) as in Example 1 was placed in a solution containing 20 g/L of nickel sulfate and 20 g/L of sodium citrate to obtain a particle mixture (12).

A boron-containing nickel-cobalt plating solution (13) (pH 9.0) was also prepared, containing 70 g/L nickel sulfate, 70 g/L cobalt sulfate, 70 g/L dimethylamine borane, 10 g/L sodium citrate, and 60 g/L sodium gluconate.

While stirring the particle mixture (12) at 60°C, the boron-containing nickel-cobalt plating solution (13) was gradually added dropwise to perform electroless nickel-cobalt plating. The mixture was then stirred until the pH stabilized, and the suspension after electroless boron-containing nickel-cobalt plating (14) was obtained.

Then, the suspension (14) was filtered, washed with water, and dried to obtain conductive particles in which Ni-Co-B conductive portions (thickness 62 nm) were arranged on the outer surface of the base particle.

Example 9
The same suspension (1B) as in Example 1 was placed in a solution containing 20 g/L of nickel sulfate and 20 g/L of sodium citrate to obtain a particle mixture (15).

A boron-containing nickel-iron plating solution (16) (pH 10.0) was also prepared, containing 70 g/L nickel sulfate, 40 g/L iron sulfate, 70 g/L dimethylamine borane, 10 g/L sodium citrate, and 100 g/L sodium gluconate.

While stirring the particle mixture (15) at 60°C, the boron-containing nickel iron plating solution (16) was gradually added dropwise to perform electroless boron-containing nickel iron plating. The mixture was then stirred until the pH stabilized, and the suspension after electroless boron-containing nickel iron plating (17) was obtained.

Then, the suspension (17) was filtered, washed with water, and dried to obtain conductive particles in which Ni-Fe-B conductive portions (thickness 54 nm) were arranged on the outer surface of the base particle.

Example 10
The same suspension (1B) as in Example 1 was placed in a solution containing 20 g/L of cobalt sulfate and 20 g/L of sodium citrate to obtain a particle mixture (18).

A boron-containing cobalt-iron plating solution (19) (pH 9.0) was also prepared, containing 80 g/L of cobalt sulfate, 30 g/L of iron sulfate, 70 g/L of dimethylamine borane, 10 g/L of sodium citrate, and 100 g/L of sodium gluconate.

While stirring the particle mixture (18) at 60°C, the boron-containing cobalt iron plating solution (19) was gradually added dropwise to perform electroless boron-containing cobalt iron plating. The mixture was then stirred until the pH stabilized, and the suspension after electroless boron-containing cobalt iron plating (20) was obtained.

Then, the suspension (20) was filtered, washed with water, and dried to obtain conductive particles in which a conductive portion (thickness 51 nm) of Co-Fe-B was arranged on the outer surface of the base particle.

(Example 11)
(1) Preparation of Silicone Oligomer 1 part by weight of 1,3-divinyltetramethyldisiloxane and 20 parts by weight of 0.5% by weight p-toluenesulfonic acid aqueous solution were placed in a 100 ml separable flask placed in a warm bath. After stirring at 40°C for 1 hour, 0.05 parts by weight of sodium bicarbonate was added. Then, 10 parts by weight of dimethoxymethylphenylsilane, 49 parts by weight of dimethyldimethoxysilane, 0.6 parts by weight of trimethylmethoxysilane, and 3.6 parts by weight of methyltrimethoxysilane were added and stirred for 1 hour. Then, 1.9 parts by weight of 10% by weight potassium hydroxide aqueous solution was added, and the mixture was heated to 85°C and stirred for 10 hours while reducing the pressure with an aspirator. After the reaction was completed, the mixture was returned to normal pressure and cooled to 40°C, 0.2 parts by weight of acetic acid was added, and the mixture was left to stand in a separatory funnel for 12 hours or more. The lower layer after the two-layer separation was taken out and purified with an evaporator to obtain a silicone oligomer.

(2) Preparation of silicone particle material (including organic polymer) 0.5 parts by weight of tert-butyl-2-ethylperoxyhexanoate (polymerization initiator, NOF Corp.'s "Perbutyl O") was dissolved in 30 parts by weight of the obtained silicone oligomer to prepare solution A. In addition, 0.8 parts by weight of a 40% by weight aqueous solution of triethanolamine lauryl sulfate (emulsifier) and 80 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol (polymerization degree: about 2000, saponification degree: 86.5 to 89 mol%, Nippon Synthetic Chemical Industry Co., Ltd.'s "Gosenol GH-20") were mixed in 150 parts by weight of ion-exchanged water to prepare aqueous solution B. After putting the above-mentioned solution A into a separable flask placed in a warm bath, the above-mentioned aqueous solution B was added. Then, emulsification was performed by using a Shirasu Porous Glass (SPG) membrane (average pore size about 1 μm). Then, the temperature was raised to 85° C., and polymerization was performed for 9 hours. The entire amount of the particles after polymerization was washed with water by centrifugation and freeze-dried. After drying, the particle aggregates were pulverized in a ball mill until the desired ratio (average secondary particle size/average primary particle size) was achieved, yielding silicone particles (base particle B) with a particle size of 3.0 μm.

Except for changing the base particle A to the base particle B and changing the thickness of the conductive layer from 51 nm to 52 nm, the same procedure as in Example 1 was used to obtain conductive particles having a conductive portion of high purity Ni disposed on the outer surface of the base particle.

Example 12
Base particles C, which differ from base particles A only in particle size, were prepared. The particle size of base particles C was 10.0 μm.

Except for changing the base particle A to the base particle C and changing the thickness of the conductive layer from 51 nm to 90 nm, the same procedure as in Example 1 was used to obtain conductive particles having a conductive portion of high purity Ni disposed on the outer surface of the base particle.

(Example 13)
Base particles D, which differ from base particles A only in particle size, were prepared. The particle size was 1.5 μm.

Except for changing the base particle A to the base particle D and changing the thickness of the conductive layer from 51 nm to 32 nm, the same procedure as in Example 1 was used to obtain conductive particles having a conductive portion of high purity Ni disposed on the outer surface of the base particle.

(Example 14)
A 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube and temperature probe was prepared. Ion-exchanged water was placed in the separable flask, and a monomer composition containing 100 mmol of methyl methacrylate, 1 mmol of N,N,N-trimethyl-N-2-methacryloyloxyethyl ammonium chloride and 1 mmol of 2,2'-azobis(2-amidinopropane) dihydrochloride was weighed out so that the solid content was 5% by weight. The mixture was then stirred at 200 rpm and polymerized at 70°C for 24 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was freeze-dried to obtain insulating particles having ammonium groups on the surface, an average particle size of 220 nm and a CV value of 10%.

The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of insulating particles.

10 g of the conductive particles obtained in Example 1 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtering through a 10 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles with insulating particles attached.

Observation with a scanning electron microscope (SEM) revealed that only one coating layer of insulating particles had been formed on the surface of the conductive particles. Image analysis was used to calculate the coverage area of the insulating particles (i.e., the projected area of the particle diameter of the insulating particles) relative to an area of 2.5 μm from the center of the conductive particles, and the coverage rate was 30%.

(Comparative Example 1)
The suspension (1A) of Example 1 was placed in a solution containing 25 g/L of nickel sulfate, 15 ppm of thallium nitrate, and 10 ppm of bismuth nitrate to obtain a particle mixture (21).

A nickel-phosphorus plating solution (22) (pH 5.5) containing 100 g/L nickel sulfate, 60 g/L sodium hypophosphite, 15 g/L sodium citrate, 25 ppm thallium nitrate, and 10 ppm bismuth nitrate was prepared.

The nickel-phosphorus plating solution (22) was gradually added dropwise to the particle mixture (21) at 50°C in which the particles were dispersed, and electroless nickel-phosphorus plating was performed. The mixture was then stirred until the pH stabilized, and the cessation of foaming was confirmed, yielding a suspension (23) after electroless nickel-phosphorus plating. The suspension (23) was then filtered, washed with water, and dried to obtain conductive particles in which a Ni-P conductive portion (thickness 59 nm) not containing a core material was arranged on the outer surface of the base particle.

(Comparative Example 2)
Conductive particles were obtained in the same manner as in Example 1, except that the base particle A was changed to metallic nickel-phosphorus particles (manufactured by Hitachi Metals Neomaterial Co., Ltd., average particle diameter 20 μm) and the thickness of the conductive layer was changed from 51 nm to 49 nm.

(evaluation)
(1) 10% K Value of Base Particle The 10% K value of the base particles (excluding metal particles) used for the conductive particles was measured using a Fisherscope H-100 manufactured by Fisher Instruments by the method described above.

(2) Saturation magnetization The saturation magnetization was measured using the obtained conductive particles. The magnetization was calculated by measuring the magnetic hysteresis curve of the conductive particles. A vibrating sample magnetometer (Riken Denshi Co., Ltd., "BHV-50") was used as the device. In addition, 15 mg of dried conductive particles was sealed in a sample holder without compression to prepare a sample, and the measurement was performed.

(3) Sedimentation velocity (transport characteristics of conductive particles)
0.5 g of conductive particles were placed in a 30 mL vial. 30 mL of pure water was then filled in the vial, and the vial was ultrasonically treated for 30 seconds to disperse the conductive particles. The vial in which the conductive particles were dispersed was placed on a magnet with a surface area larger than the bottom surface of the vial, and was left to stand until the conductive particles had completely settled.

After settling, the vial was rotated 180 degrees and turned upside down while still in close contact with the magnet, and the time it took for the particles that were not retained by the magnetic surface to reach the bottom was measured.

[Settling velocity criteria]
○○: Particles do not settle even after 10 minutes or more. ○: Time required for settling particles to reach the bottom is 5 minutes or more but less than 10 minutes. ×: Time required for settling particles to reach the bottom is less than 5 minutes.

(4) Damage to the electrodes Preparation of anisotropic conductive film:
30 parts by weight of a phenoxy compound (Inchem's "PKHC"), which is a thermosetting compound, was added to a mixed solvent of 35 parts by weight of PGMEA and 35 parts by weight of methyl ethyl ketone, and stirred at room temperature for 24 hours to obtain a 30% by weight dispersion of the phenoxy compound. Next, 30 parts by weight of the dispersion, 30 parts by weight of an epoxy compound (DIC's "EPICLON HP-4032D"), which is a thermosetting compound, 30 parts by weight of an imidazole microcapsule curing agent (Asahi Kasei's "Novacure HXA3922"), which is a latent type thermosetting agent, and 1 part by weight of a silane coupling agent (Shin-Etsu Chemical's "KBM-403") were mixed. The conductive particles were added to the obtained mixture so that the content of the conductive particles was 10% by weight in the obtained conductive film (100% by weight), and then methyl ethyl ketone was further added so that the solid content was 50% by weight, and the mixture was stirred at 2000 rpm for 5 minutes using a planetary stirrer to obtain a conductive paste. The obtained conductive paste was applied onto a polyethylene terephthalate that had been subjected to a release treatment, and the solvent was dried to obtain an anisotropic conductive film having a thickness of 20 μm.

Fabrication of connection structure:
A glass substrate was prepared having an electrode pattern with an L/S of 20 μm/20 μm (a composite electrode in which a TiO electrode part with a thickness of 0.35 μm, an AlTi electrode part with a thickness of 1.0 μm, and an IZO electrode part with a thickness of 0.1 μm were laminated in this order) on the upper surface. Also, a semiconductor chip was prepared having a gold electrode pattern with an L/S of 20 μm/20 μm (gold electrode thickness 20 μm) on the lower surface.

An anisotropic conductive film was placed on the upper surface of the glass substrate to form an anisotropic conductive film layer. Next, the semiconductor chip was laminated on the upper surface of the anisotropic conductive film layer so that the electrodes faced each other. Thereafter, a pressure heating head was placed on the upper surface of the semiconductor chip while adjusting the temperature of the head so that the temperature of the anisotropic conductive film layer was 130°C, and a pressure of 70 MPa was applied per total area of the connection portion of the bump electrodes to obtain a connection structure.

Using the resulting connection structure, the damage to the electrodes was judged according to the following criteria. The reason for comparing the damage to the electrodes depending on whether the particles were crushed or not is that if the particles are not crushed and are in contact with the electrode, there is a high possibility that they are digging into the electrode and damaging the electrode, but conversely, if the particles are crushed, there is a low possibility that they are digging into the electrode and damaging the electrode.

[Criteria for determining electrode damage]
○: Particles are crushed and in contact with the electrode. ×: Particles are not crushed and in contact with the electrode.

(5) Connection Resistance Using the connection structure obtained in the evaluation of electrode damage in (4) above, the connection resistance between the electrodes was measured by a four-terminal method. The initial connection resistance was also judged according to the following criteria. The connection resistance is preferably 10Ω or less, more preferably 5.0Ω or less, even more preferably 3.0Ω or less, and particularly preferably 1.5Ω or less. The connection resistance was judged according to the following criteria.

[Connection resistance criteria]
○○: Connection resistance is 1.0 Ω or less. ○: Connection resistance is more than 1.0 Ω and less than 5.0 Ω. ×: Connection resistance is more than 5.0 Ω.

Details and results are shown in Tables 1 and 2 below.

REFERENCE SIGNS LIST 1...Conductive particle 2...Base particle 3...Conductive portion 11...Conductive particle 11a...Protrusion 12...Conductive portion 12a...Protrusion 13...Core material 14...Insulating material 21...Conductive particle 21a...Protrusion 22...Conductive portion 22a...Protrusion 22A...First conductive portion 22Aa...Protrusion 22B...Second conductive portion 22Ba...Protrusion 31...Conductive particle 51...Connection structure 52...First connection target member 52a...First electrode 53...Second connection target member 53a...Second electrode 54...Connection portion 61...Conductive material X...Magnetic field or magnetic force

Claims (13)

A base particle;
A conductive portion disposed on a surface of the base particle,
the conductive portion is formed of only one layer, and the one layer of the conductive portion is a layer containing nickel, cobalt, or iron, or the conductive portion is formed of a plurality of layers, and the outermost layer of the conductive portion is a layer containing nickel, cobalt, or iron,
The total content of nickel, cobalt and iron in the conductive portion is 90% by weight or more,
Conductive particles having a saturation magnetization of 10 emu/g or more (excluding conductive particles having another conductive layer on the outside of a layer containing nickel, cobalt or iron) . The conductive particle according to claim 1, wherein the substrate particle is not a metal particle. The conductive particles according to claim 1, wherein the base particles are resin particles or organic-inorganic hybrid particles. the conductive portion contains at least two of nickel, cobalt, and iron;
The conductive particle according to any one of claims 1 to 3, wherein the content of one of nickel, cobalt, and iron is 51% by weight or more in 100% by weight of the conductive portion. The conductive particle according to any one of claims 1 to 4, wherein the base particle has a compressive modulus of elasticity of 1000 N/mm2 ^or more and 30000 N/mm2 or less when compressed by 10% at ²⁵ °C. The conductive particles according to any one of claims 1 to 5, wherein the particle diameter of the base particle is 1 μm or more and 10 μm or less. The conductive particle according to any one of claims 1 to 6, wherein the specific gravity of the base particle is lower than the specific gravity of the conductive portion. The conductive particles according to any one of claims 1 to 7, which are used for conductive connections that apply a magnetic field or magnetic force. The conductive particle according to any one of claims 1 to 8, having protrusions on the outer surface of the conductive portion. The conductive particle according to any one of claims 1 to 9, comprising an insulating material disposed on the outer surface of the conductive portion. A conductive material comprising the conductive particles according to any one of claims 1 to 10 and a binder resin. a first connection target member having a first electrode on a surface thereof;
a second connection target member having a second electrode on a surface thereof;
a connection portion connecting the first connection target member and the second connection target member, the material of the connection portion being the conductive particles according to any one of claims 1 to 10, or a conductive material containing the conductive particles and a binder resin,
A connection structure, wherein the first electrode and the second electrode are electrically connected by the conductive particles. A first arrangement step of arranging the conductive particles according to any one of claims 1 to 10, or arranging a conductive material containing the conductive particles and a binder resin, on a surface of a first connection target member having a first electrode on a surface thereof;
a second arrangement step of arranging a second connection target member having a second electrode on a surface of the conductive particles or the conductive material opposite to the first connection target member;
applying a magnetic field or magnetic force before or after the second positioning step;
A method for manufacturing a connection structure, comprising obtaining a connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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