CN116189963A

CN116189963A - Conductive particle, conductive material, and connection structure

Info

Publication number: CN116189963A
Application number: CN202310216345.XA
Authority: CN
Inventors: 杉本理; 胁屋武司
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2018-06-25
Filing date: 2019-06-21
Publication date: 2023-05-30
Also published as: CN112313758A; TWI820157B; KR20210022541A; TW202015074A; JPWO2020004273A1; JP7280880B2; CN112313758B; KR102647120B1; WO2020004273A1

Abstract

The invention provides a conductive particle capable of effectively reducing connection resistance between electrodes and effectively inhibiting magnetic aggregation. A conductive particle is provided with: and a conductive portion disposed on a surface of the substrate particle, wherein a ratio of a remanent magnetization to a saturation magnetization of the conductive particle is 0.6 or less.

Description

Conductive particle, conductive material, and connection structure

The present application is a divisional application of patent application having chinese application No. 201980040888.2, the invention name of "conductive particles, conductive materials, and connection structures", and having application date of 2019, 6, 21.

Technical Field

The present invention relates to conductive particles in which conductive portions are disposed on the surfaces of base particles. The present invention also relates to a conductive material and a connection structure using the conductive particles.

Background

Anisotropic conductive materials such as anisotropic conductive paste, anisotropic conductive film, and the like are widely known. In the anisotropic conductive material, conductive particles are dispersed in a binder resin. As the conductive particles, conductive particles having been subjected to an insulating treatment on the surface of the conductive layer may be used.

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

As an example of the above-mentioned conductive particles, patent document 1 below discloses a conductive particle including a masterbatch having a plating layer and insulating particles coating the surface of the masterbatch. The master batch is a particle obtained by coating the surface of the plastic core with the plating layer. The plating layer includes at least a nickel/phosphorus alloy layer. The particle size of the master batch is 2.0 μm or more and 3.0 μm or less. The saturation magnetization of the master batch is 45emu/cm ³ The following is given. The insulating particles have a particle diameter of 180nm to 500 nm.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2013-258138

Disclosure of Invention

Problems to be solved by the invention

In the above patent document 1, the saturation magnetization of the master batch is 45emu/cm ³ The following is given. However, patent document 1 only describes controlling saturation magnetization to be the same as that of the saturation magnetizationWithin a specific range, there is no description about the remanent magnetization.

Conventional conductive particles are provided with conductive metal such as nickel on the surface thereof by plating or the like, and are used for electrical connection between electrodes. In addition, in the conventional conductive particles, metals such as nickel having magnetism are magnetized in the surrounding environment, in the manufacturing process, and the like, and the conductive particles may be aggregated (magnetic aggregation). As a method for solving the above-described problems, as described in patent document 1, a method of reducing saturation magnetization by adding phosphorus to a plating layer is mentioned. However, when the phosphorus content of the plating layer increases, the resistance value of the conductive particles significantly increases, and when the electrodes are electrically connected using the conductive particles, the connection resistance between the electrodes may increase.

In addition, in the conventional conductive particles, although saturation magnetization can be reduced, it is difficult to sufficiently reduce residual magnetization. In order to suppress the magnetic aggregation of the conductive particles, it is necessary to reduce not only the saturation magnetization but also the residual magnetization. In the conventional conductive particles, it is difficult to reduce the connection resistance between electrodes and suppress the magnetic aggregation.

The purpose of the present invention is to provide conductive particles that can effectively reduce the connection resistance between electrodes and can effectively inhibit magnetic aggregation. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles.

Technical scheme for solving problems

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 a surface of the base particle, wherein a ratio of residual magnetization to saturation magnetization of the conductive particle is 0.6 or less.

In a specific aspect of the conductive particle according to the present invention, the residual magnetization is 0.02A/m or less.

In a specific aspect of the conductive particle according to the present invention, the conductive particle includes a soft magnetic portion disposed on an outer surface of the conductive portion.

In a specific aspect of the conductive particle according to the present invention, the conductive particle includes an insulating portion disposed between the conductive portion and the soft magnetic portion, and the soft magnetic portion is disposed on an outer surface of the conductive portion with the insulating portion interposed therebetween.

In a specific aspect of the conductive particle according to the present invention, a distance between the conductive portion and the soft magnetic portion is 10nm to 500 nm.

In a specific aspect of the conductive particle according to the present invention, the conductive particle includes a plurality of soft magnetic portions, and the plurality of soft magnetic portions are arranged on an outer surface of the conductive portion so as to be spaced apart from each other.

In a specific aspect of the conductive particle according to the present invention, an area of a portion of the conductive portion surface covered with the soft magnetic portion is 30% or more of an entire surface area of the conductive portion.

In a specific aspect of the conductive particle according to the present invention, an area of a portion of the conductive portion surface covered with the soft magnetic portion is 40% or more of an entire surface area of the conductive portion.

In a specific aspect of the conductive particle according to the present invention, the conductive particle includes a plurality of insulating particles disposed on an 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 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 a surface thereof, a second connection target member having a second electrode on a surface thereof, and a connection portion for connecting the first connection target member and the second connection target member together, wherein the connection portion is made of the conductive particles or a conductive material containing the conductive particles and a binder resin, and the first electrode and the second electrode are electrically connected by the conductive portion among the conductive particles.

ADVANTAGEOUS EFFECTS OF INVENTION

The conductive particles according to the present invention include a base particle and a conductive portion disposed on a surface of the base particle. In the conductive particles according to the present invention, the ratio of the remanent magnetization to the saturation magnetization is 0.6 or less. The conductive particles according to the present invention have the above-described structure, and therefore, the connection resistance between electrodes can be effectively reduced, and magnetic aggregation can be effectively suppressed.

Brief description of the drawings

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

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

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

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

Fig. 5 is a cross-sectional view showing conductive particles according to a fifth embodiment of the present invention.

Fig. 6 is a cross-sectional view showing conductive particles according to a sixth embodiment of the present invention.

Fig. 7 is a cross-sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention.

Detailed Description

The following describes the details of the present invention.

(conductive particles)

The conductive particles according to the present invention include a base particle and a conductive portion disposed on a surface of the base particle. In the conductive particles according to the present invention, the ratio of the remanent magnetization to the saturation magnetization is 0.6 or less.

The conductive particles according to the present invention have the above-described structure, and therefore, the connection resistance between electrodes can be effectively reduced, and magnetic aggregation can be effectively suppressed.

In conventional conductive particles, metals such as nickel having magnetism are magnetized in the surrounding environment, during the manufacturing process, and the like, and the conductive particles may aggregate (magnetically aggregate). As a method for suppressing aggregation (magnetic aggregation) of conductive particles, a method of adding phosphorus to a plating layer to reduce saturation magnetization, and the like can be mentioned. However, when the phosphorus content of the plating layer increases, the resistance value of the conductive particles increases significantly, and when the electrodes are electrically connected using the conductive particles, the connection resistance between the electrodes also increases.

In addition, in the conventional conductive particles, even if the saturation magnetization is lowered, the residual magnetization may not be lowered sufficiently. The inventors of the present invention found that in order to suppress the magnetic aggregation of conductive particles, it is necessary to reduce the remanent magnetization. In the conventional conductive particles, it is sometimes difficult to reduce the connection resistance between electrodes and suppress the magnetic aggregation.

The inventors of the present invention have found that the use of specific conductive particles can reduce the connection resistance between electrodes and suppress residual magnetic aggregation. The present invention has the above configuration, and therefore, the connection resistance between the electrodes can be effectively reduced, and magnetic aggregation can be effectively suppressed.

In the present invention, the use of specific conductive particles contributes significantly to the effect described above.

In the conductive particles according to the present invention, the ratio of remanent magnetization to saturation magnetization (remanent magnetization/saturation magnetization) is 0.6 or less from the viewpoint of effectively reducing the connection resistance between electrodes and effectively suppressing magnetic aggregation. The above ratio (remanent magnetization/saturation magnetization) is preferably 0.5 or less, more preferably 0.3 or less, and most preferably 0.0. The ratio (remanent magnetization/saturation magnetization) is preferably as close as 0.0 from the viewpoint of further effectively reducing the connection resistance between the electrodes and further effectively suppressing the magnetic aggregation. When the ratio (remanent magnetization/saturation magnetization) is equal to or less than the upper limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed. In addition, the lower limit of the above ratio (remanent magnetization/saturation magnetization) is not particularly limited. The above ratio (remanent magnetization/saturation magnetization) is, for example, preferably 0.001 or more, and more preferably 0.01 or more.

From the viewpoint of further effectively suppressing magnetic aggregation, the residual magnetization of the conductive particles is preferably 0.02A/m (20 emu/cm ³ ) The following is given. The residual magnetization is preferably 0.015A/m (15 emu/cm ³ ) Hereinafter, the ratio of the catalyst to the catalyst is more preferably 0.01A/m (10 emu/cm ³ ) In the following, the ratio is more preferably 0.005A/m (5 emu/cm ³ ) Most preferably 0.0000A/m (0.0 emu/cm) ³ ). From the viewpoint of further effectively suppressing the magnetic aggregation, the more the residual magnetization is close to 0.0000A/m (0.0 emu/cm) ³ ) The better. When the remanent magnetization is equal to or less than the upper limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed. The lower limit of the residual magnetization of the conductive particles is not particularly limited. For example, the residual magnetization is preferably 0.0001A/m (0.1 emu/cm) ³ ) The above.

The residual magnetization of the conductive particles can be controlled by adjusting the coating ratio of the soft magnetic body described below, for example. For example, if the coating ratio of the soft magnetic portion is increased, the residual magnetization can be reduced, and if the coating ratio of the soft magnetic portion is reduced, the residual magnetization can be increased.

From the viewpoint of further effectively suppressing magnetic aggregation, the saturation magnetization of the conductive particles is preferably 0.2A/m (200 emu/cm ³ ) The following is given. The saturation magnetization is preferably 0.1A/m (100 emu/cm ³ ) Hereinafter, the ratio of the catalyst to the catalyst is more preferably 0.08A/m (80 emu/cm ³ ) In the following, the ratio is more preferably 0.05A/m (50 emu/cm ³ ) The following is given. When the saturation magnetization is equal to or less than the upper limit, the magnetic aggregation can be further effectively suppressed. From the viewpoint of collecting magnetic force, the saturation magnetization of the conductive particles is preferably 0.001A/m (1 emu/cm ³ ) The above. The saturation magnetization is preferably 0.005A/m (5 emu/cm) ³ ) The above is more preferably in the range of 0.01A/m (10 emu/cm ³ ) As described above, the ratio of the concentration of the catalyst to the catalyst is more preferably 0.015A/m (15 emu/cm ³ ) The above. When the saturation magnetization is equal to or higher than the lower limit, the conductive particles in the anisotropic conductive material can be efficiently aligned by an external magnetic fieldAnd (5) a seed.

The saturation magnetization of the conductive particles can be controlled by adjusting the thickness of the conductive layer or the conductive portion, for example. For example, if the thickness of the conductive layer or the conductive portion is increased, the saturation magnetization may be increased, and if the thickness of the conductive layer or the conductive portion is decreased, the saturation magnetization may be decreased.

The residual magnetization and saturation magnetization of the conductive particles can be measured by a vibrating sample magnetometer (PV-300-5 manufactured by Torong scientific Co., ltd.). Specifically, it can be measured as follows.

Vibration sample magnetometers were calibrated using capsules encapsulated with nickel powder as calibration samples for the device. The conductive particles are then weighed in capsules and mounted onto a sample holder. The sample holder was set on a magnetometer body and measured at a temperature of 20 ℃ and a maximum magnetic field under pressure of 20kOe at a speed of 3 minutes/loop to obtain a magnetization curve. The residual magnetization and saturation magnetization (A/m) were obtained from the obtained magnetization curve.

The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, still more preferably 100 μm or less, still more preferably 60 μm or less, still more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably 5 μm or less. When the particle diameter of the conductive particles is equal to or larger than the lower limit and equal to or smaller than the upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large when the electrodes are electrically connected using the conductive particles, and it is difficult to form aggregated conductive particles when forming the conductive portions. In addition, the interval between the electrodes connected via the conductive particles does not become excessively large, and the conductive portion is difficult to be peeled off from the surface of the base material particles.

The particle diameter of the conductive particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the conductive particles can be obtained by, for example, observing any 50 conductive particles with an electron microscope or an optical microscope and calculating the average value of the particle diameters of the conductive particles, or by measuring the particle size distribution by laser diffraction. In observation with an electron microscope or an optical microscope, the particle diameter of each conductive particle was obtained as the particle diameter of a circular equivalent diameter meter. In observation with an electron microscope or an optical microscope, the average particle diameter in terms of a circle equivalent diameter of any 50 conductive particles was substantially equal to the average particle diameter in terms of a sphere equivalent diameter. In the measurement of the laser diffraction particle size distribution, the particle diameter of each conductive particle is determined as the particle diameter of the sphere equivalent diameter. The particle diameter of the conductive particles is preferably calculated by measuring the particle size distribution by laser diffraction.

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 in the particle diameter of the conductive particles is equal to or less than the upper limit, the conduction reliability and insulation reliability between the electrodes can be further effectively improved.

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

CV value (%) = (ρ/Dn) ×100

ρ: standard deviation of particle diameter of conductive particles

Dn: average particle diameter of conductive particles

The shape of the conductive particles is not particularly limited. The conductive particles may have a spherical shape or a flat shape other than a spherical shape.

Hereinafter, a specific embodiment of the present invention will be described with reference to the drawings.

The conductive particles 1 shown in fig. 1 include base particles 2 and conductive portions 3. In the conductive particles 1, the conductive portions 3 are conductive layers. The conductive portion 3 is coated on the surface of the base material particle 2. The conductive particles 1 are coated particles obtained by coating the surface of the base particles 2 with the conductive portions 3. The conductive particles 1 have conductive portions 3 on the surfaces thereof. In the conductive particle 1, the conductive portion 3 is a single-layer conductive portion (conductive layer). In the conductive particles, the conductive portions may be coated on the entire surface of the base particles, or the conductive portions may be coated on a part of the surface of the base particles. In the conductive particles, the conductive portion may be a single-layer conductive portion or a multi-layer conductive portion composed of 2 or more layers.

Unlike the conductive particles 51 described later, the conductive particles 1 do not include a core material. The conductive particles 1 have no protrusions on the conductive surface and no protrusions on the outer surface of the conductive portion 3. The conductive particles 1 are spherical. However, the conductive particles 1 may have a core material, may have protrusions on the conductive surface, or may have protrusions on the outer surface of the conductive portion 3.

The conductive particles may have no protrusions on the conductive surface, may have no protrusions on the outer surface of the conductive portion, and may have a spherical shape. The conductive particles 1 are not provided with insulating particles unlike the conductive particles 11, 21, 41, and 51 described later. However, the conductive particles 1 may include insulating particles disposed on the outer surface of the conductive portion 3.

The conductive particles 11 shown in fig. 2 include base particles 2, conductive portions 3, soft magnetic portions 12, and insulating particles 13. The insulating particles 13 are formed of a material having insulating properties.

Unlike the conductive particles 1, the conductive particles 11 include soft magnetic portions 12 and insulating particles 13. The conductive particles 11 include insulating particles 13 that do not contact the soft magnetic body 12.

The conductive particles may or may not include a soft magnetic portion. The conductive particles may or may not include insulating particles. In the conductive particles, the soft magnetic portion is preferably disposed on an outer surface of the conductive portion. The soft magnetic portion is preferably not in contact with the conductive portion. In the conductive particles, the insulating particles are preferably disposed on an outer surface of the conductive portion.

The conductive particles 21 shown in fig. 3 include the base particles 2, the conductive portions 3, the soft magnetic portions 12, and the insulating particles 13.

Unlike the conductive particles 11, the conductive particles 21 include an insulating portion 22 that covers the surface of the soft magnetic portion 12. The conductive particles 21 include insulating particles 13 that do not contact the soft magnetic body 12. The conductive particles 21 include insulating particles 13 that do not contact the insulating portion 22.

The insulating portion 22 is made of an insulating material. In the conductive particles 21, the insulating portion 22 covers the entire surface of the soft magnetic portion 12. Accordingly, the insulating portion 22 is disposed between the conductive portion 3 and the soft magnetic portion 12. The soft magnetic portion 12 is not in contact with the conductive portion 3. The insulating portion may be coated on at least a part of the surface of the soft magnetic portion, and may not be coated on the entire surface of the soft magnetic portion. In the conductive particles, the soft magnetic portion is preferably disposed on an outer surface of the conductive portion. The soft magnetic portion is preferably disposed on an outer surface of the conductive portion through the insulating portion. The insulating portion is preferably disposed between the conductive portion and the soft magnetic portion. The conductive particles may or may not include insulating particles.

The conductive particles 31 shown in fig. 4 include the base particles 2, the conductive portions 3, and the soft magnetic portions 12.

Unlike the conductive particles 11, the conductive particles 31 include an insulating portion 32 that covers the surface of the conductive portion 3.

The insulating portion 32 is made of an insulating material. In the conductive particles 31, the insulating portion 32 covers the entire surface of the conductive portion 3. Accordingly, the insulating portion 32 is disposed between the conductive portion 3 and the soft magnetic portion 12. The soft magnetic portion 12 does not contact the conductive portion 3. The insulating portion may be coated on at least a part of the surface of the conductive portion, and may not be coated on the entire surface of the conductive portion. In the conductive particles, the soft magnetic portion is preferably disposed on an outer surface of the conductive portion through the insulating portion. The insulating portion is preferably disposed between the conductive portion and the soft magnetic portion. The conductive particles may include insulating particles disposed on an outer surface of the conductive portion.

The conductive particles 41 shown in fig. 5 include the base particles 2, the conductive portions 3, the soft magnetic portions 12, and the insulating particles 13.

Unlike the conductive particles 11, the conductive particles 41 include an insulating portion 42 that covers the outer surface of the conductive portion 3. The conductive particles 41 include insulating particles 13 that do not contact the soft magnetic body 12. The conductive particles 41 include insulating particles 13 that do not contact the insulating portion 42.

The insulating portion 42 is made of an insulating material. In the conductive particles 41, the insulating portions 42 are insulating particles. In the conductive particles 41, an insulating portion 42 is disposed on the outer surface of the conductive portion 3, and a soft magnetic portion 12 is disposed on the outer surface of the insulating portion 42. Accordingly, the insulating portion 42 is disposed between the conductive portion 3 and the soft magnetic portion 12. The soft magnetic portion 12 is not in contact with the conductive portion 3. The insulating portion may be coated on at least a part of the surface of the conductive portion, and may not be coated on the entire surface of the conductive portion. In the conductive particles, the soft magnetic portion is preferably disposed on an outer surface of the conductive portion through the insulating portion. The insulating portion is preferably disposed between the conductive portion and the soft magnetic portion. The conductive particles may or may not include insulating particles.

The conductive particles 51 shown in fig. 6 include the base particles 2, the conductive portions 61, the soft magnetic portions 12, and the insulating particles 13.

Unlike the conductive particles 21, the conductive particles 51 include a plurality of core materials 62 coated on the surfaces of the base particles 2. The conductive portion 61 is coated on the base material particles 2 and the core material 62. Since the conductive portion 61 is coated on the core material 62, the conductive particles 51 have a plurality of protrusions 63 on the surface. In the conductive particles 51, the surface of the conductive portion 61 is raised by the core material 62, and a plurality of protrusions 63 are formed. In the conductive particles, the core material may be used or may not be used in order to form the protrusions. The conductive particles may not include the core material.

Hereinafter, other specific details of the conductive particles will be described.

Substrate particles:

the substrate particles include: resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, metal particles, and the like. The base particles are preferably base particles other than metal particles, and more preferably resin particles, inorganic particles other than metal particles, or organic-inorganic hybrid particles. The base material particle may be a core-shell particle including a core and a shell disposed on a surface of the core. The core may be an organic core and the shell may be an inorganic shell.

As the material of the resin particles, various organic substances can be preferably used. Examples of the material of the resin particles include: polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonates, polyamides, phenol formaldehyde resins, melamine formaldehyde resins, benzoguanamine formaldehyde resins, urea formaldehyde resins, phenol resins, melamine resins, benzoguanamine resins, urea resins, epoxy resins, unsaturated polyester resins, saturated polyester resins, polyethylene terephthalate, polysulfones, polyphenylene oxides, polyacetals, polyimides, polyamideimides, polyetheretherketones, polyethersulfones, divinylbenzene polymers, divinylbenzene copolymers, and the like. Examples of the divinylbenzene-based copolymer include: divinylbenzene-styrene copolymers, divinylbenzene- (meth) acrylate copolymers, and the like. Since the hardness of the resin particles can be easily controlled within a preferable range, the material of the resin particles is preferably a polymer obtained by polymerizing 1 or 2 or more kinds of polymerizable monomers having an ethylenically unsaturated group.

When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, examples of the polymerizable monomer having an ethylenically unsaturated group include a non-crosslinkable monomer and a crosslinkable monomer.

Examples of the non-crosslinkable monomer include: styrene monomers such as styrene and α -methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; alkyl (meth) acrylate compounds such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate; oxygen atom-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; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acetate compounds such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; halogen-containing monomers such as methyl trifluoro (meth) acrylate, ethyl pentafluoride (meth) acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

Examples of the crosslinkable monomer include: polyfunctional (meth) acrylate compounds such as tetramethylolmethane tetra (meth) acrylate, 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, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, (poly) tetramethyleneglycol di (meth) acrylate, and 1, 4-butanediol di (meth) acrylate; silane-containing monomers such as triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, and gamma- (meth) acryloxypropyl trimethoxysilane, trimethoxysilyl styrene, and vinyltrimethoxysilane.

The term "(meth) acrylate" refers to one or both of "acrylate" and "methacrylate". The term "(meth) acrylic" refers to one or both of "acrylic" and "methacrylic". The term "(meth) acryl" refers to one or both of "acryl" and "methacryl".

The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of the method include: a method of performing suspension polymerization in the presence of a radical polymerization initiator; and a method in which a monomer is swelled and polymerized by using non-crosslinked seed particles together with a radical polymerization initiator.

In the case where the base particles are inorganic particles or organic-inorganic hybrid particles other than metals, examples of the inorganic substance used for forming the base particles include: silica, alumina, barium titanate, zirconia, carbon black, and the like. The inorganic substance is preferably not a metal. The particles formed of the above-mentioned silicon oxide are not particularly limited, and examples thereof include particles obtained by hydrolyzing a silicon compound having 2 or more hydrolyzable alkoxysilane groups to form crosslinked polymer particles, and then firing the crosslinked polymer particles as needed. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from an alkoxysilane-based polymer obtained by crosslinking and an acrylic resin.

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

The material of the organic core may be the material of the resin particles.

Examples of the material of the inorganic shell include inorganic materials listed as the material of the base particles. The material of the inorganic shell is preferably silicon oxide. The above inorganic shell is preferably formed by the following method: the metal alkoxide is formed into a shell on the surface of the core by a sol-gel method, and then the shell is baked. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of a silane alkoxide.

When the base particles are metal particles, examples of the metal as a material of the metal particles include: silver, copper, nickel, silicon, gold, titanium, and the like.

The particle diameter of the base material particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, and preferably 100 μm or less, more preferably 60 μm or less, further preferably 50 μm or less. When the particle diameter of the base material particles is not less than the lower limit and not more than the upper limit, the inter-electrode gap becomes small, and even if the thickness of the conductive layer is made thicker, small conductive particles can be obtained. In addition, when the conductive portions are formed on the surfaces of the base particles, aggregation is less likely to occur, and aggregated conductive particles are less likely to be formed.

The particle diameter of the base material particles is particularly preferably 2 μm or more and 50 μm or less. When the particle diameter of the base material particles is in the range of 2 μm to 50 μm, aggregation is less likely to occur when conductive portions are formed on the surfaces of the base material particles, and aggregation conductive particles are less likely to be formed.

The particle diameter of the base material particles is a diameter when the base material particles are spherical, and is a maximum diameter when the base material particles are not spherical.

The particle diameter of the base material particles represents a number average particle diameter. The particle size of the base material particles is determined using a particle size distribution measuring apparatus or the like. The particle diameter of the base material particles is preferably obtained by observing any 50 base material particles with an electron microscope or an optical microscope and calculating an average value. In the case of measuring the particle diameter of the base material particles, the conductive particles can be measured, for example, as follows.

The electroconductive particles were added to "Technovit4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and the cross section was dispersed near the center of the conductive particles in the embedding resin for inspection. Then, 50 conductive particles were randomly selected by setting the image magnification to 25000 times using a field emission scanning electron microscope (FE-SEM), and the base particles of each conductive particle were observed. The particle diameters of the base particles in the respective conductive particles were measured, and the arithmetic average was performed, and the measured particle diameters were used as the particle diameters of the base particles.

Conductive part:

the conductive portion preferably includes a metal. The metal constituting the conductive portion is not particularly limited. Examples of the metal include: gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, alloys thereof, and the like. Further, as the metal, tin-doped indium oxide (ITO) may be used. The metal may be used alone or in combination of at least 2 kinds. From the viewpoint of further reducing the connection resistance between the electrodes, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable. In addition, in the present specification, the conductive portion is defined as: a powder sample was prepared using the same material as that constituting the conductive portion, and when the volume resistivity of the powder sample was measured using a "powder resistivity measurement system" manufactured by mitsubishi chemical corporation, a portion where the volume resistivity was 0.005 Ω·cm or less.

In addition, from the viewpoint of effectively improving the conduction reliability, the conductive portion and the outer surface portion of the conductive portion preferably include nickel. The content of nickel in 100 wt% of the conductive portion containing nickel is preferably 10 wt% or more, more preferably 50 wt% or more, further preferably 60 wt% or more, further preferably 70 wt% or more, and particularly preferably 90 wt% or more. The content of nickel in 100 wt% of the conductive portion containing nickel may be 97 wt% or more, 97.5 wt% or more, or 98 wt% or more.

In many cases, hydroxyl groups are present on the surface of the conductive portion due to oxidation. In general, hydroxyl groups are present on the surface of the conductive portion formed of nickel due to oxidation. The insulating particles may be disposed on the surface of the conductive portion having a hydroxyl group (the surface of the conductive particle) by chemical bonding.

The conductive portion may be formed by 1 layer. The conductive portion may be formed by a plurality of layers. That is, the conductive portion may have a laminated structure of 2 or more layers. In the case where the conductive portion is formed by a plurality of layers, the metal constituting the outermost layer is preferably gold, nickel, palladium, copper or an alloy containing tin and silver, and more preferably gold. In the case where the metal constituting the outermost layer is the above-mentioned preferable metal, the connection resistance between the electrodes is further reduced. In addition, when the metal constituting the outermost layer is gold, the corrosion resistance is further improved.

The method for forming the conductive portion on the surface of the base material particle is not particularly limited. Examples of the method for forming the conductive portion include: a method using electroless plating; a method using electroplating; a method using physical collision; a method using mechanochemical reaction; a method of physical vapor deposition or physical adsorption is utilized; and a method of applying a metal powder or a paste containing a metal powder and a binder to the surface of a base particle. The method of forming the conductive portion is preferably a method using electroless plating, electroplating, or physical impact. The method of using the physical vapor deposition includes: vacuum evaporation, ion plating, ion sputtering, and the like. In addition, in the above method using physical collision, for example, theta composer (manufactured by Deshoku corporation) or the like is used.

The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and further preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, sufficient conductivity can be obtained, and the conductive particles can be sufficiently deformed at the time of connection between the electrodes without becoming excessively hard.

In the case where the conductive portion is formed by a plurality of 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 outermost conductive portion is equal to or greater than the lower limit and equal to or less than the upper limit, the outermost conductive portion becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes can be sufficiently reduced.

The thickness of the conductive portion can be measured, for example, by observing a cross section of the conductive particle using a Transmission Electron Microscope (TEM).

The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. On the surface of the electrode connected by the conductive particles, an oxide film is formed in many cases. In the case of using conductive particles with insulating particles having protrusions on the surface of the conductive portion, the oxide film can be effectively removed by the protrusions by disposing the conductive particles between the electrodes and pressing them. Therefore, the electrode and the conductive portion are more surely in contact, and the connection resistance between the electrodes is further reduced. In addition, when the electrodes are connected, the conductive particles can be effectively removed from the insulating particles between the conductive particles and the electrodes by the protrusions of the conductive particles. Therefore, the conduction reliability between the electrodes is further improved.

As a method for forming the above-mentioned protrusion, there may be mentioned: a method of forming a conductive portion by electroless plating after attaching a core material to the surface of a base material particle; and a method in which a conductive portion is formed on the surface of the base material particles by electroless plating, then a core material is attached, and further a conductive portion is formed by electroless plating. As another method for forming the above-mentioned protrusion, there may be mentioned: a method of forming a first conductive portion on the surface of the base material particle, disposing a core material on the first conductive portion, and then forming a second conductive portion; and a method of adding a core material in the middle of forming a conductive portion (first conductive portion or second conductive portion, etc.) on the surface of the base material particle. In addition, in order to form the projections, the following method or the like may be used: the conductive portion is formed by electroless plating on the substrate particles without using the core material, and then the plating is deposited in a protruding form on the surface of the conductive portion, and the conductive portion is further formed by electroless plating.

Examples of the method for attaching the core material to the surface of the base material particle include: a method in which a core material is added to a dispersion of base particles, and the core material is aggregated and attached to the surface of the base particles by van der Waals force; and a method in which a core material is added to a container containing base particles, and the core material is attached to the surfaces of the base particles by a mechanical action caused by rotation of the container or the like. From the viewpoint of controlling the amount of the core material to be attached, the method of attaching the core material to the surface of the base material particles is preferably a method of aggregating and attaching the core material to the surface of the base material particles in the dispersion.

Examples of the substance constituting the core substance include: conductive materials, and nonconductive materials. Examples of the conductive material include: conductive nonmetallic materials such as metals, metal oxides, and graphite, and conductive polymers. The conductive polymer may be polyacetylene or the like. Examples of the nonconductive material include: silica, alumina, zirconia, and the like. The core material is preferably a metal from the viewpoint of further improving the conduction reliability between the electrodes.

The metal is not particularly limited. Examples of the metal include: metals such as gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, and cadmium, and alloys composed of 2 or more metals such as tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-lead-silver alloy, and tungsten carbide. The metal is preferably nickel, copper, silver or gold from the viewpoint of further improving the conduction reliability between the electrodes. The metal may be the same as or different from the metal constituting the conductive portion (conductive layer).

The shape of the core material is not particularly limited. The core material is preferably in the shape of a block. Examples of the core material include: particulate masses, aggregated masses formed by aggregating a plurality of fine particles, amorphous masses, and the like.

The average diameter (average particle diameter) of the core material is preferably 0.001 μm or more, more preferably 0.05 μm or more, and preferably 0.9 μm or less, more preferably 0.2 μm or less. If the average diameter of the core material is not less than the lower limit and not more than the upper limit, the connection resistance between the electrodes can be effectively reduced.

The average particle diameter of the core material is preferably an average particle diameter, and more preferably a plurality of average particle diameters. The average particle diameter of the core material can be calculated by observing any 50 core materials by using an electron microscope or an optical microscope, for example; or by measurement of the particle size distribution by laser diffraction. In observation with an electron microscope or an optical microscope, the particle diameter of each core material was obtained as the particle diameter of a circular equivalent diameter meter. In observation with an electron microscope or an optical microscope, the average particle diameter in terms of a circle equivalent diameter of any 50 core substances is substantially equal to the average particle diameter in terms of a sphere equivalent diameter. In the measurement of the laser diffraction particle size distribution, the particle diameter of each core material was obtained as the particle diameter of a sphere equivalent diameter meter. The average particle diameter of the core material is preferably calculated by measuring the particle size distribution by laser diffraction.

Insulating particles:

the conductive particles preferably include a plurality of insulating particles disposed on an outer surface of the conductive particles. In this case, if the conductive particles are used for connection between electrodes, short-circuiting between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact, insulating particles are present between the plurality of electrodes, so that it is possible to prevent a short circuit between the electrodes adjacent in the lateral direction, not between the upper and lower electrodes. When the electrodes are connected, the conductive particles are pressurized by 2 electrodes, so that the insulating particles between the conductive portions of the conductive particles and the electrodes can be easily removed. Further, in the case of conductive particles having a plurality of protrusions on the outer surface of the conductive portion, insulating particles between the conductive portion of the conductive particles and the electrode can be more easily removed.

The material of the insulating particles may be a material of the resin particles, or an inorganic material as a material of the base particles. The material of the insulating particles is preferably the material of the resin particles. The insulating particles are preferably the resin particles or the organic-inorganic hybrid particles, and may be the resin particles or the organic-inorganic hybrid particles.

Examples of the other material of the insulating particles include polyolefin compounds, (meth) acrylate polymers, (meth) acrylate copolymers, block copolymers, thermoplastic resins, crosslinked thermoplastic resins, thermosetting resins, and water-soluble resins. The insulating particles may be used alone or in combination of two or more.

Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block copolymer include polystyrene, styrene-acrylate copolymer, SB-type styrene-butadiene block copolymer, SBS-type styrene-butadiene block copolymer, and hydrogenated products of these compounds. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenolic resin, and melamine resin. Examples of the crosslinked product of the thermoplastic resin include polyethylene glycol methacrylate, alkoxytrimethylol propane methacrylate, and alkoxylated pentaerythritol methacrylate. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, and methylcellulose. In addition, a chain transfer agent may be used to adjust the degree of polymerization. Examples of the chain transfer agent include mercaptans and carbon tetrachloride.

As a method for disposing the insulating particles on the surface of the conductive portion, there may be mentioned: chemical methods, physical or mechanical methods, and the like. Examples of the chemical method include: interfacial polymerization, suspension polymerization in the presence of particles, emulsion polymerization, and the like. The physical or mechanical method may be: spray drying, hybridization, electrostatic adhesion, spraying, dipping, vacuum evaporation, and the like. In the case of electrically connecting the electrodes, the method of disposing the insulating particles on the surface of the conductive portion is preferably a physical method from the viewpoint of further effectively improving the insulation reliability and the conduction reliability.

The outer surface of the conductive portion and the outer surface of the insulating particle may be coated with a compound having a reactive functional group. The outer surface of the conductive portion and the outer surface of the insulating particle may not be directly chemically bonded, but may be indirectly chemically bonded through a compound having a reactive functional group. After the carboxyl group is introduced to the outer surface of the conductive part, the carboxyl group may be chemically bonded to the functional group of the outer surface of the insulating particle through a polyelectrolyte such as polyethylenimine.

The particle diameter of the insulating particles may be appropriately selected according to the particle diameter of the conductive particles, the use of the conductive particles, and the like. The particle diameter of the insulating particles is preferably 10nm or more, more preferably 100nm or more, further preferably 300nm or more, particularly preferably 500nm or more, and preferably 4000nm or less, more preferably 2000nm or less, further preferably 1500nm or less, particularly preferably 1000nm or less. When the particle diameter of the insulating particles is not less than the lower limit, the conductive layers of the plurality of conductive particles are not easily contacted with each other when the conductive particles are dispersed in the binder resin. When the particle diameter of the insulating particles is equal to or smaller than the upper limit, the pressure for removing the insulating particles between the electrodes and the conductive particles does not need to be excessively high, and the electrodes do not need to be heated to a high temperature when the electrodes are connected.

The particle diameter of the insulating particles is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the insulating particles is determined using a particle size distribution measuring apparatus or the like. The particle diameter of the insulating particles is preferably obtained by observing any 50 insulating particles with an electron microscope or an optical microscope and calculating an average value. In measuring the particle diameter of the insulating particles in the conductive particles, the measurement can be performed, for example, as follows.

The electroconductive particles were added to "Technovit 4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed, to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and passed near the center of the dispersed conductive particles in the embedding resin for inspection. Then, 50 conductive particles were randomly selected by setting the image magnification to 5 ten thousand times using a field emission scanning electron microscope (FE-SEM), and insulating particles of each conductive particle were observed. The particle size of the insulating particles in each conductive particle was measured, and the average value was calculated as the particle size of the insulating particles.

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

Soft magnet part:

the conductive particles preferably include soft magnetic portions disposed on an outer surface of the conductive portion. When the conductive particles include the soft magnetic portion, the residual magnetization of the conductive particles can be further effectively reduced without impairing the conductivity of the conductive portion. As a result, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed. In the present specification, the soft magnetic portion is defined as follows: which is a part magnetized under the influence of an external magnetic field but rapidly loses magnetic force once the external magnetic field is taken out. The soft magnetic body preferably has a saturation magnetization of more than 0.00A/m and a ratio of residual magnetization to saturation magnetization (residual magnetization/saturation magnetization) of less than 0.3. The saturation magnetization of the soft magnetic portion and the ratio (remanent magnetization/saturation magnetization) can be measured in the following manner. The powder sample was prepared using the same material as that constituting the soft magnetic portion described above. The powder sample was measured by using a vibrating sample magnetometer (PV-300-5 manufactured by Torong scientific Co., ltd.) in the same procedure as in the measurement of the residual magnetization and saturation magnetization of the conductive particles. The obtained saturation magnetization and residual magnetization are used to obtain the saturation magnetization and the ratio (residual magnetization/saturation magnetization) of the soft magnetic portion.

The soft magnetic part may be soft magnetic particles or a soft magnetic layer.

The conductive particles preferably include a plurality of the soft magnetic portions, in order to further effectively maintain the connection resistance between the electrodes low and to further effectively suppress the magnetic aggregation. More specifically, it is preferable that the soft magnetic portion contains soft magnetic particles and a plurality of the soft magnetic particles. As another specific embodiment, it is preferable that the plurality of soft magnetic portions in the conductive particles are present in a spot shape so that the conductive portion is exposed, and that the entire outer surface of the conductive portion is not covered with one soft magnetic portion. In the conductive particles, it is preferable that the plurality of soft magnetic portions are arranged on an outer surface of the conductive portion so as to be spaced apart from each other. The number of soft magnetic portions present in the separation is preferably 2 or more, more preferably 3 or more, still more preferably 5 or more, and particularly preferably 10 or more. The number of soft magnetic portions present in the separation may be appropriately set according to the surface area of the conductive particles, or the like.

The soft magnetic portion is not particularly limited. Examples of the material of the soft magnetic portion include pure iron, ferrosilicon, permalloy (Permalloy), fe—si—al, boldol iron cobalt alloy (permadur), electromagnetic stainless steel, amorphous solids (iron-based amorphous solids, cobalt-based amorphous solids, and the like), nanocrystals, and ferrite (manganese zinc ferrite, nickel zinc ferrite, copper zinc ferrite, cobalt ferrite, maghemite, magnetite, and the like). The soft magnetic material may be used alone or in combination of two or more.

When the soft magnetic portion is a particle, the particle diameter of the soft magnetic portion may be appropriately selected according to the particle diameter of the conductive particle, the use of the conductive particle, and the like. The particle diameter of the soft magnetic portion is preferably 5nm or more, preferably 10nm or more, and preferably 200nm or less, more preferably 100nm or less. When the particle diameter of the soft magnetic portion is equal to or larger than the lower limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed.

The particle diameter of the soft magnetic portion is preferably an average particle diameter, and more preferably a number average particle diameter. The particle diameter of the soft magnetic body is determined by a particle size distribution measuring apparatus or the like. The particle diameter of the soft magnetic portion is preferably obtained by observing any 50 insulating particles by an electron microscope or an optical microscope and calculating an average value. In measuring the particle diameter of the soft magnetic portion in the conductive particles, the measurement can be performed, for example, as follows.

The electroconductive particles were added to "Technovit 4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed, to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and passed near the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 5 ten thousand times, 50 conductive particles were randomly selected, and the soft magnetic portion of each conductive particle was observed. The particle diameter of the soft magnetic portion in each conductive particle was measured, and the soft magnetic portion was arithmetically averaged to obtain the particle diameter of the soft magnetic portion.

When the soft magnetic portion is a layer, the thickness of the soft magnetic portion may be appropriately selected according to the particle diameter of the conductive particles, the use of the conductive particles, and the like. The thickness of the soft magnetic portion is preferably 5nm or more, preferably 10nm or more, and preferably 200nm or less, more preferably 100nm or less.

The thickness of the soft magnetic portion is preferably obtained by observing any 50 insulating particles with an electron microscope or an optical microscope and calculating an average value. When the thickness of the soft magnetic portion is measured in the conductive particles, the thickness can be measured, for example, as follows.

The electroconductive particles were added to "Technovit 4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed, to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and passed near the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 5 ten thousand times, 50 conductive particles were randomly selected, and the thickness of the soft magnetic portion of each conductive particle was observed. The thickness of the soft magnetic portion in each conductive particle was measured, and the thickness was calculated as the thickness of the soft magnetic portion by arithmetic averaging.

From the viewpoint of further effectively suppressing magnetic aggregation, it is preferable that the conductive portion is separated from the soft magnetic portion. The distance between the conductive portion and the soft magnetic portion is preferably 10nm or more, more preferably 30nm or more, further preferably 50nm or more, and preferably 800nm or less, further preferably 500nm or less. When the separation distance is equal to or more than the lower limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed. The distance between the conductive portion and the soft magnetic portion may be calculated by using a field emission scanning electron microscope (FE-SEM), setting the image magnification to 5 ten thousand times, randomly selecting 50 conductive particles, measuring the distance between the conductive portion and the soft magnetic portion, and arithmetically averaging the distances to obtain the distance between the conductive portion and the soft magnetic portion. Further, when the conductive particles include an insulating portion disposed between the conductive portion and the soft magnetic portion, the thickness of the insulating portion measured by a method of measuring the thickness of the insulating portion described below may be set to be a distance separating the conductive portion and the soft magnetic portion.

The area of the portion of the surface of the conductive portion covered with the soft magnetic portion (coating ratio of the soft magnetic portion) is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more, still more preferably 30% or more, still more preferably 40% or more, particularly preferably 45% or more, and most preferably 50% or more, of the total surface area of the conductive portion. The coating ratio of the soft magnetic body may be 80% or less. When the coating ratio of the soft magnetic body is equal to or higher than the lower limit, the magnetic aggregation can be further effectively suppressed. The coating ratio of the soft magnetic portion may be 95% or less, 90% or less, 80% or less, or 70% or less from the viewpoint of further effectively maintaining the connection resistance between the electrodes.

The coating ratio of the soft magnetic body can be obtained as follows.

The conductive particles were observed from one direction using a Scanning Electron Microscope (SEM), and the total area of the soft magnetic portion in the circle of the outer peripheral portion of the surface of the conductive portion, which was occupied in the entire area in the circle of the outer peripheral portion of the outer surface of the conductive portion in the observation image, was calculated. The coating ratio of the soft magnetic portion is preferably calculated as an average coating ratio by observing 20 conductive particles and averaging the measurement results of the respective conductive particles.

Insulation part:

the conductive particles preferably include an insulating portion disposed between the conductive portion and the soft magnetic portion. In the conductive particles, the soft magnetic portion is preferably disposed on an outer surface of the conductive portion through the insulating portion. The soft magnetic portion is preferably not in contact with the conductive portion. The insulating portion is preferably disposed between the conductive portion and the soft magnetic portion. When the conductive particles satisfy the above preferred embodiments, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed.

The insulating portion is different from the insulating particles. The insulating particles are used to prevent short-circuiting between adjacent electrodes. The insulating part is used for preventing the soft magnet part from contacting with the conductive part.

The insulating portion is not particularly limited as long as it is made of an insulating material. The insulating portion may be made of an insulating resin or the like. The insulating portion may be made of a material such as the insulating particles.

The method of disposing the soft magnetic portion and the insulating portion on the outer surface of the conductive portion is not particularly limited. As a method of disposing the soft magnetic portion and the insulating portion on the outer surface of the conductive portion, a method of disposing the insulating particles on the outer surface of the conductive portion may be used. Specifically, the following method is given as a method of disposing the soft magnetic portion and the insulating portion on the outer surface of the conductive portion. The method of forming the insulating portion on the surface of the soft magnetic portion to form an insulating portion-coated soft magnetic portion, and then disposing the insulating portion-coated soft magnetic portion on the outer surface of the conductive portion (in this case, the insulating portion-coated soft magnetic portion may be formed to include a plurality of soft magnetic portions, such as "FG beads" (registered trademark) manufactured by polymun corporation). And a method in which the insulating portion is coated on the surface of the conductive portion to obtain insulating portion-coated conductive particles, and then the soft magnetic portion is disposed on the outer surface of the insulating portion-coated conductive particles. And a method in which particles are formed using the insulating portion, the soft magnetic portion is disposed on the surface of the particles, and the particles with soft magnetic portion are disposed on the outer surface of the conductive portion.

The thickness of the insulating portion is preferably 10nm or more, more preferably 30nm or more, further preferably 50nm or more, and preferably 800nm or less, further preferably 500nm or less. When the thickness of the insulating portion is equal to or greater than the lower limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed. When the insulating portion is a particle, the thickness of the insulating portion corresponds to the diameter of the particle.

The thickness of the insulating portion is preferably obtained by observing any 50 insulating particles with an electron microscope or an optical microscope and calculating an average value. In measuring the thickness of the insulating portion in the conductive particles, the thickness can be measured, for example, as follows.

The electroconductive particles were added to "Technovit 4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed, to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and passed near the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 5 ten thousand times, 50 conductive particles were randomly selected, and the thickness of the insulating portion of each conductive particle was observed. The thickness of the insulating portion in each conductive particle was measured, and the thickness was calculated as the thickness of the insulating portion by arithmetic averaging.

As a method of disposing the soft magnetic portion and the insulating portion on the outer surface of the conductive portion, when a method is employed in which the insulating portion is coated on the surface of the soft magnetic portion to obtain an insulating portion-coated soft magnetic portion, and then the insulating portion-coated soft magnetic portion is disposed on the outer surface of the conductive portion, the insulating portion-coated soft magnetic portion is preferably insulating layer-coated soft magnetic particles. The insulating layer-coated soft magnetic particles are obtained by coating the surfaces of soft magnetic particles with an insulating layer. That is, the insulating layer-coated soft magnetic particles are preferably disposed on the outer surface of the conductive portion. In this case, the average particle diameter of the insulating layer-coated soft magnetic particles is preferably 25nm or more, more preferably 50nm or more, and preferably 800nm or less, more preferably 500nm or less, and further preferably 150nm or less. When the average particle diameter of the insulating layer-coated soft magnetic particles is not less than the lower limit, the conductive layers of the plurality of conductive particles are less likely to contact each other when the conductive particles are dispersed in the binder resin, and the insulating reliability of the obtained connection structure is improved. When the average particle diameter of the insulating layer-coated soft magnetic particles is not more than the upper limit, the insulating layer-coated soft magnetic particles are less likely to fall off the surfaces of the conductive particles, and magnetic aggregation can be effectively suppressed.

The average particle diameter of the soft magnetic particles covered with the insulating layer can be measured, for example, as follows.

The electroconductive particles were added to "Technovit 4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed, to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and passed near the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 5 ten thousand times, 50 conductive particles were randomly selected, and the particle diameter of the insulating layer-coated soft magnetic particles disposed on the outer surface of the conductive layer of each conductive particle was observed. The particle diameters of the insulating layer coated soft magnetic particles in the respective conductive particles were measured, and the average particle diameters were calculated as the average particle diameters of the insulating layer coated soft magnetic particles.

(conductive Material)

The conductive material of the present invention contains the conductive particles and the binder resin. The conductive particles are preferably dispersed in a binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The above-mentioned conductive material is preferably used for electrical connection between the electrodes. The conductive material is preferably a conductive material for circuit connection. In the above-described conductive material, since the above-described conductive particles are used, the insulation reliability and the conduction reliability between the electrodes can be further improved. In the above-described conductive material, since the above-described conductive particles are used, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed.

The binder resin is not particularly limited. As the binder resin, a known insulating resin can be used. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. The curable component includes 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.

Examples of the binder resin include: ethylene resins, thermoplastic resins, curable resins, thermoplastic block copolymers, elastomers, and the like. The binder resin may be used alone or in combination of 1 or more than 2.

Examples of the vinyl resin include: vinyl acetate resin, acrylic resin, styrene resin, and the like. Examples of the thermoplastic resin include: polyolefin resins, ethylene-vinyl acetate copolymers, polyamide resins, and the like. Examples of the curable resin include: epoxy resins, polyurethane resins, polyimide resins, unsaturated polyester resins, and the like. The curable resin may be a room temperature curable resin, a thermosetting resin, a photo curable 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 copolymers, styrene-isoprene-styrene block copolymers, hydrides of styrene-butadiene-styrene block copolymers, hydrides of styrene-isoprene-styrene block copolymers, and the like. Examples of the elastomer include: styrene-butadiene copolymer rubber, acrylonitrile-styrene block copolymer rubber, and the like.

The conductive material may include, for example, in addition to the conductive particles and the binder resin: fillers, extenders, softeners, plasticizers, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, flame retardants, and the like.

The method for dispersing the conductive particles in the binder resin is not particularly limited, and any conventionally known dispersing method can be used. Examples of the method for dispersing the conductive particles in the binder resin include the following methods. The conductive particles are added to the binder resin, and then kneaded and dispersed by 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, followed by kneading and dispersion using a planetary mixer or the like. The binder resin is diluted with water, an organic solvent, or the like, and then the conductive particles are added thereto, followed by kneading with a planetary mixer or the like to disperse the mixture.

The viscosity (. Eta.25) of the conductive material at 25℃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 (η25) is equal to or higher than the lower limit and equal to or lower than the upper limit, the insulation reliability between the electrodes can be further effectively improved, and the conduction reliability between the electrodes can be further effectively improved. The viscosity (. Eta.25) can be appropriately adjusted depending on the kind and amount of the components to be blended.

The viscosity (. Eta.25) can be measured, for example, using an E-type viscometer ("TVE 22L" manufactured by Tokyo Co., ltd.) at 25℃and 5 rpm.

The conductive material of the present invention can be used in the form of a conductive paste, a conductive film, or the like. In the case where the conductive material of the present invention is a conductive film, a film containing no conductive particles may be stacked over the conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

The content of the binder resin in 100 wt% of the conductive material is preferably 10 wt% or more, more preferably 30 wt% or more, further preferably 50 wt% or more, particularly preferably 70 wt% or more, and preferably 99.99 wt% or less, more preferably 99.9 wt% or less. When the content of the binder resin is not less than the lower limit and not more than the upper limit, the conductive particles can be efficiently arranged between the electrodes, and the connection reliability of the members to be connected by the conductive material can be further improved.

The content of the conductive particles in the conductive material is preferably 0.01 wt% or more, more preferably 0.1 wt% or more, and preferably 80 wt% or less, more preferably 60 wt% or less, further preferably 40 wt% or less, particularly preferably 20 wt% or less, and most preferably 10 wt% or less, based on 100 wt% of the conductive material. When the content of the conductive particles is not less than the lower limit and not more than the upper limit, the conduction reliability and insulation reliability between the electrodes can be further improved. When the content of the conductive particles is not less than the lower limit and not more than the upper limit, the connection resistance between the electrodes can be further effectively reduced, and the magnetic aggregation can be further effectively suppressed.

(connection Structure)

The connection structure of the present invention comprises: a first connection object member having a first electrode on a surface thereof; a second connection object member having a second electrode on a surface thereof; and a connecting portion that connects the first member to be connected and the second member to be connected. In the connection structure of the present invention, the material of the connection portion is the conductive particles or a conductive material containing the conductive particles and a binder resin. In the connection structure of the present invention, the first electrode and the second electrode are electrically connected by the conductive portion in the conductive particle.

The connection structure can be obtained by the following steps: the conductive particles or the conductive material are disposed between the first member to be connected and the second member to be connected, and are electrically connected by thermocompression bonding. In the case where the conductive particles have the insulating particles, the insulating particles are preferably separated from the conductive particles when the thermocompression bonding is performed.

The connection structure 81 shown in fig. 7 includes a first member 82 to be connected, a second member 83 to be connected, and a connection portion 84 that connects the first member 82 to be connected and the second member 83 to be connected. The connection portion 84 is formed of a conductive material including conductive particles 1. The connection portion 84 is preferably formed by curing a conductive material containing a plurality of conductive particles 1. In fig. 7, the conductive particles 1 are schematically shown for convenience. The

conductive particles

11, 21, 31, 41, or 51 may be used instead of the conductive particles 1.

The first connection object member 82 has a plurality of first electrodes 82a on a surface (upper surface). The second connection object member 83 has a plurality of second electrodes 83a on a surface (lower surface). The first electrode 82a and the second electrode 83a are electrically connected by 1 or more conductive particles 1. Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive portion in the conductive particle 1.

The method for producing the connection structure is not particularly limited. As an example of a method for manufacturing the connection structure, a method in which the above-described conductive material is disposed between the first connection object member and the second connection object member to obtain a laminate, and then the laminate is heated and pressurized, and the like can be cited. The pressure of the thermocompression bonding is preferably 40mPa or more, more preferably 60mPa or more, and preferably 90mPa or less, more preferably 70mPa or less. The heating temperature of the thermocompression bonding is preferably 80 ℃ or higher, more preferably 100 ℃ or higher, and preferably 140 ℃ or lower, more preferably 120 ℃ or lower. If the pressure and temperature of the thermocompression bonding are not less than the lower limit and not more than the upper limit, the conduction reliability between the electrodes can be further improved. In addition, in the case where the conductive particles include the insulating particles, the insulating particles can be easily detached from the surfaces of the conductive particles at the time of conductive connection.

When the conductive particles include the insulating particles, the insulating particles existing between the conductive particles and the first electrode and the second electrode can be removed when the laminate is heated and pressurized. For example, when the conductive particles are heated and pressurized, the insulating particles present between the conductive particles and the first electrode and the second electrode are easily separated from the surfaces of the conductive particles. In the heating and pressurizing, a part of the insulating particles may be separated from the surface of the conductive particles, so that the surface of the conductive portion may be partially exposed. The exposed portion of the surface of the conductive portion is in contact with the first electrode and the second electrode, and the first electrode and the second electrode can be electrically connected by the conductive particles.

The first member to be connected and the second member to be connected are not particularly limited. The first and second connection target members include, specifically: electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors, and diodes, and electronic components such as resin films, printed boards, flexible flat cables, rigid and flexible boards, glass epoxy boards, and circuit boards such as glass boards. The first connection target member and the second connection target member are preferably electronic components.

Examples of the electrode provided on the connection target member include: metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. In the case where the connection target member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. In the case where the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. In the case where the electrode is an aluminum electrode, the electrode may be an electrode formed only of aluminum, or may be an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. As a material of the metal oxide layer, there can be mentioned: indium oxide doped with trivalent metal element, zinc oxide doped with trivalent metal element, and the like. Examples of the trivalent metal element include: sn, al, ga, and the like.

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

Example 1

(1) Preparation of conductive particle body

Resin particles having a particle diameter of 3 μm and formed of a copolymer resin of tetramethylolmethane tetraacrylate and divinylbenzene were prepared. 10 parts by weight of the base particles were dispersed into 100 parts by weight of an alkali solution containing 5% by weight of a palladium catalyst liquid using an ultrasonic disperser, and then the solution was filtered, whereby the base particles were taken out. Next, the substrate particles were added to 100 parts by weight of a 1 wt% dimethylamine borane solution to activate the surfaces of the substrate particles. The surface-activated base particles were sufficiently washed with water, and then 500 parts by weight of distilled water was added thereto and dispersed, thereby obtaining a dispersion. Next, 1g of nickel particle slurry (average particle diameter 100 nm) was added to the above dispersion over 3 minutes to obtain a suspension containing base particles to which a core material was attached.

A nickel plating solution (pH 8.5) containing 0.35mol/L of nickel sulfate, 1.38mol/L of dimethylamine borane and 0.5mol/L of sodium citrate was prepared.

The resulting suspension was stirred at 60 ℃, and the nickel plating solution was slowly dropped into the suspension to perform electroless nickel plating. Thereafter, the particles were removed by filtering the suspension, and then washed with water and dried to form a nickel-boron conductive layer (thickness: 0.15 μm) on the surface of the base particles, thereby obtaining conductive particles having conductive portions on the surface.

(2) Preparation of insulating layer coated Soft magnetic particles

The surface of the soft magnetic particles (soft magnetic portions) is covered with an insulating layer (insulating portion) as described below.

The composition containing the following polymerizable compound was placed in a 500mL separable flask equipped with a four-port separable cap, stirring wings, a three-way valve, a cooling tube, and a temperature probe, and then sufficiently emulsified using an ultrasonic irradiation machine. Then, the mixture was stirred at 200rpm, and polymerization was carried out at 50℃under a nitrogen atmosphere for 5 hours. The composition was composed of 200 parts by weight of distilled water, 5.2 parts by weight of iron oxide nanoparticles (component: maghemite or magnetite, manufactured by SIGMA-ALDRICH Co., ltd.) having a diameter of 30nm, and 0.1 part by weight of 2,2' -azobis {2- [ N- (2-carboxyethyl) amidino ] propane. Further, the composition contains 0.1 part by weight of polyoxyethylene lauryl ether (EMULGEN 106 manufactured by Kao corporation), 1.7 parts by weight of methyl methacrylate, and 0.1 part by weight of polyethylene glycol dimethacrylate. After the completion of the reaction, the mixture was cooled, and solid-liquid separation was performed twice with a centrifuge, excess polymerizable compound was removed by washing, and the coated portion formed of the polymerizable compound was used to obtain insulating layer-coated soft magnetic particles (particle diameter: 50 nm) in which the entire surface of the soft magnetic particles was coated.

Hereinafter, the obtained insulating layer-coated soft magnetic particles may be described as particles (a).

(3) Preparation of conductive particles (conductive particles coated with insulating layer)

The particles (a) thus obtained were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of the particles (a). 10 parts by weight of the obtained base particles (conductive particle main body) having conductive portions on the surface thereof were dispersed in 100 parts by weight of distilled water, and 1 part by weight of a 10% by weight aqueous dispersion of particles (a) was added thereto and stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the mixture was washed with methanol and dried to obtain conductive particles in which particles (A) were attached to the conductive particle bodies.

(4) Preparation of conductive Material (Anisotropic conductive paste)

7 parts by weight of the obtained conductive particles, 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, 30 parts by weight of phenol novolac type (phenol novolac) epoxy resin, and SI-60L (manufactured by Sanxinshi chemical Co., ltd.) were blended, and defoaming and stirring were performed for 3 minutes, thereby obtaining a conductive material (anisotropic conductive paste).

(5) Preparation of connection Structure

A transparent glass substrate having an IZO electrode pattern (first electrode, vickers hardness of metal of the electrode surface 100 Hv) with an L/S of 10 μm/10 μm formed on the upper surface was prepared. In addition, a semiconductor chip having an Au electrode pattern (second electrode, vickers hardness of metal of the electrode surface 50 Hv) with an L/S of 10 μm/10 μm formed on the lower surface was prepared.

The obtained anisotropic conductive paste was applied to the transparent glass substrate to a thickness of 30 μm, thereby forming an anisotropic conductive paste layer. Next, the semiconductor chip is stacked on the anisotropic conductive paste layer so that the electrodes face each other. Thereafter, while adjusting the temperature of the head (head) so that the temperature of the anisotropic conductive paste layer became 100 ℃, a pressurizing and heating head was placed on the upper surface of the semiconductor chip, and the anisotropic conductive paste layer was cured at 100 ℃ while applying a pressure of 60mPa, thereby obtaining a connection structure.

Examples 2 to 7, 10 to 12 and comparative examples 3 and 4

Conductive materials and connection structures were obtained in the same manner as in example 1, except that the types of soft magnetic portions, the coating ratios of the soft magnetic portions, the thicknesses of the insulating portions, the addition amounts of methyl methacrylate when the surfaces of the soft magnetic particles were coated with the insulating layers, and the average particle diameters of the particles (a) were set as shown in the following table.

In example 10, permalloy particles having an average particle diameter of 30nm, which were formed by a dry grinding apparatus of a hammer mill/ball mill, were used instead of the iron oxide nanoparticles. In example 12, a powder of a Ponganic Dunn cobalt-iron alloy was formed into particles having an average particle diameter of 30nm by a dry pulverizing apparatus of a hammer mill/ball mill. Meanwhile, in comparative example 4, a nickel paste having an average particle diameter of 30nm was used. In addition, the coating ratios of the soft magnetic parts of examples 2 to 7, 10 to 12 and comparative examples 3 and 4 were adjusted by changing the addition amount of the 10 wt% aqueous dispersion of the particles (a) when the conductive particles having the insulating layer coating the soft magnetic particles were prepared.

Example 8

(1) Preparation of conductive particle body

A conductive particle body was prepared in the same manner as in example 1.

(2) Preparation of insulating-coated conductive particles

The surface of the conductive particle body is covered with an insulating layer (insulating portion) as described below.

The composition containing the following polymerizable compound was placed in a 500mL separable flask equipped with a four-port separable cap, stirring wings, a three-way valve, a cooling tube, and a temperature probe, and then sufficiently emulsified using an ultrasonic irradiation machine. Then, the mixture was stirred at 200rpm, and polymerization was carried out at 50℃under a nitrogen atmosphere for 5 hours. The composition contained 200 parts by weight of distilled water, 20 parts by weight of the obtained conductive particle body, and 0.01 part by weight of 2,2' -azobis {2- [ N- (2-carboxyethyl) amidino ] propane }. Further, the composition contained 0.1 part by weight of polyoxyethylene lauryl ether (EMULGEN 106 manufactured by Kao corporation), 0.1 part by weight of methyl methacrylate, and 0.1 part by weight of polyethylene glycol dimethacrylate. After the completion of the reaction, the mixture was cooled, and the mixture was subjected to solid-liquid separation twice with a centrifuge, excess polymerizable compound was removed by washing, and soft magnetic particles were covered with an insulating layer (the thickness of the insulating layer was 50 nm) which covered the entire surface of the soft magnetic particles by a covering portion formed of the polymerizable compound.

(3) Preparation of conductive particles (conductive particles comprising insulating layer and Soft magnetic particles)

The surface of the insulating layer in the insulating portion-coated conductive particles is covered with soft magnetic particles (soft magnetic portions) as described below.

Iron oxide nanoparticles (component: manufactured by SIGMA-ALDRICH Co., ltd.) having a diameter of 30nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion. 10 parts by weight of the insulating-coated conductive particles thus obtained were dispersed in 100 parts by weight of distilled water, and a 10% aqueous dispersion of 1 part by weight of iron oxide nanoparticles was added thereto and stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the mixture was washed with methanol and dried to obtain conductive particles (conductive particles including an insulating layer and soft magnetic particles) in which iron oxide nanoparticles were attached to the insulating portion-coated conductive particles.

(4) Preparation of conductive Material (Anisotropic conductive paste)

A conductive material was obtained in the same manner as in example 1, except that the obtained conductive particles were used.

(5) Preparation of connection Structure

A connection structure was obtained in the same manner as in example 1, except that the obtained conductive material was used.

Example 9

(1) Preparation of conductive particle body

A conductive particle body was prepared in the same manner as in example 1.

(2) Preparation of Soft magnetic particle-coated insulating particles

Insulating particles were formed as follows.

The composition containing the following polymerizable compound was placed in a 500mL separable flask equipped with a four-port separable cap, stirring wings, a three-way valve, a cooling tube, and a temperature probe, and then sufficiently emulsified using an ultrasonic irradiation machine. Then, the mixture was stirred at 200rpm, and polymerization was carried out at 50℃under a nitrogen atmosphere for 5 hours. The composition comprises 200 parts by weight of distilled water, 0.2 part by weight of acid polyphosphoric acid (phosphooxy) polyoxyethylene glycol methacrylate, 0.2 part by weight of 2,2' -azobis {2- [ N- (2-carboxyethyl) amidino ] propane }, 20 parts by weight of methyl methacrylate, and 1 part by weight of polyethylene glycol dimethacrylate. After the completion of the reaction, the mixture was cooled, and the mixture was subjected to solid-liquid separation twice with a centrifuge, and excess polymerizable compound was removed by washing, whereby insulating particles (particle diameter: 300 nm) were obtained.

The surfaces of the obtained insulating particles were covered with soft magnetic particles (soft magnetic portions) in the following manner.

Iron oxide nanoparticles (component: maghemite or magnetite, manufactured by SIGMA-ALDRICH corporation) having a diameter of 30nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion. 10 parts by weight of the obtained insulating particles were dispersed in 100 parts by weight of distilled water, and 1 part by weight of a 10% by weight aqueous dispersion of iron oxide nanoparticles was added thereto and stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the mixture was washed with methanol and dried to obtain soft magnetic particles having iron oxide nanoparticles attached to the insulating particles.

(3) Preparation of conductive particles (conductive particles with Soft magnetic particles coating insulating particles)

The surface of the conductive particle body is coated with insulating particles (soft magnetic portions) coated with soft magnetic particles as described below.

The obtained insulating particles coated with soft magnetic particles were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion. 10 parts by weight of the conductive particle main body was dispersed in 100 parts by weight of distilled water, and 1 part by weight of a 10% aqueous dispersion of the soft magnetic particle-coated insulating particles was added thereto and stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the mixture was washed with methanol and dried to obtain conductive particles (conductive particles having soft magnetic particles coating the insulating particles) in which soft magnetic particles coated the insulating particles were adhered to the conductive particle main bodies.

(4) Preparation of conductive Material (Anisotropic conductive paste)

(5) Preparation of connection Structure

Comparative example 1

The conductive particle body in example 1 was prepared as conductive particles. A conductive material and a connection structure were obtained in the same manner as in example 1, except that the conductive particles were used.

Comparative example 2

(1) Preparation of conductive particle body

A conductive particle body was prepared in the same manner as in example 1.

(2) Conductive particles (preparation of Soft magnetic particle-coated conductive particles)

The surface of the conductive particle body was covered with soft magnetic particles as follows.

Iron oxide nanoparticles (component: maghemite or magnetite, manufactured by SIGMA-ALDRICH corporation) having a diameter of 30nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion. 10 parts by weight of the conductive particle body was dispersed in 100 parts by weight of distilled water, and a 10% aqueous dispersion of 1 part by weight of iron oxide nanoparticles was added thereto and stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the mixture was washed with methanol and dried to obtain soft magnetic particles having iron oxide nanoparticles attached to the conductive particle bodies.

(3) Preparation of conductive Material (Anisotropic conductive paste)

(4) Preparation of connection Structure

(evaluation)

(1) Residual magnetization and saturation magnetization of conductive particles

Vibration sample type magnetometers ("PV-300-5" manufactured by Torong scientific industries Co., ltd.) were calibrated using capsules containing nickel powder as a calibration sample of the device. The conductive particles obtained are then weighed in capsules and mounted onto a sample holder. The sample holder was placed on a magnetometer body and measured at 20℃under conditions of temperature (constant temperature), maximum magnetic field under pressure 20kOe, speed 3 minutes/loop, resulting in a magnetization curve. The residual magnetization and saturation magnetization (A/m) were determined from the obtained magnetization curve.

In addition, the ratio of the remanent magnetization to the saturation magnetization (remanent magnetization/saturation magnetization) was calculated from the measurement result.

(2) Coating ratio of soft magnetic body

The area of the conductive portion surface covered with the soft magnetic portion (the covering ratio of the soft magnetic portion) which is occupied by the entire surface area of the conductive portion of the obtained conductive particle was measured.

The coating ratio of the soft magnetic body was obtained as follows.

The obtained conductive particles were observed from one direction by an electron microscope (SEM), and the coating ratio of the soft magnetic body was calculated by observing the total area of the soft magnetic body in the outer peripheral part circle of the conductive part surface, which is occupied by the total area in the outer peripheral part circle of the conductive part surface in the image. The coating ratio of the soft magnetic portion was calculated by observing 20 conductive particles and taking the measurement result of each conductive particle as the average coating ratio after averaging.

(3) Thickness of insulating part

The thickness of the insulating portion of the obtained conductive particles was measured in the following manner.

The electroconductive particles were added to "Technovit4000" manufactured by Kulzer corporation to a content of 30 wt%, and dispersed to prepare an electroconductive particle inspection embedded resin. The cross section of the conductive particles was cut out using an ion mill (IM 4000 manufactured by Hitachi High-Technologies corporation) and dispersed near the center of the conductive particles in the embedding resin for inspection. Then, 50 conductive particles were randomly selected by setting the image magnification to 5 ten thousand times using a field emission scanning electron microscope (FE-SEM), and the base particles of each conductive particle were observed. The particle diameters of the base particles in the respective conductive particles were measured, and the arithmetic average was performed to obtain the particle diameters of the base particles.

(4) Magnetic agglomeration of conductive particles

The obtained conductive material was observed to confirm whether or not the magnetic aggregation of the conductive particles occurred. The magnetic aggregation of the conductive particles was determined under the following conditions.

[ criterion for determining magnetic aggregation of conductive particles ]

O: the conductive particles are not magnetically agglomerated

O: although the magnetic aggregation of the conductive particles slightly occurred, the suppression effect was observed

X: the conductive particles are magnetically agglomerated

(5) Connecting resistance (upper and lower electrode)

The connection resistances between the upper and lower electrodes of the obtained 20 connection structures were measured by the 4-terminal method. The connection resistance can be obtained by measuring the voltage when a certain amount of current flows, based on the relationship of voltage=current×resistance. The connection resistance was determined according to the following criteria.

[ criterion for determining connection resistance ]

O: the connection resistance is below 1.5 omega

O: the connection resistance exceeds 1.5Ω and is 2.0Ω or less

O: the connection resistance exceeds 2.0Ω and is 5.0Ω or less

Delta: the connection resistance exceeds 5.0Ω and is 10Ω or less

X: the connection resistance exceeds 10Ω

(6) Insulation reliability (electrodes adjacent in transverse direction)

In the above evaluation of the conduction reliability (5), the resistance value was measured by a tester for the 20 obtained connection structures to evaluate whether or not electric leakage was present between the adjacent electrodes. Insulation reliability was evaluated on the basis of the following criteria.

[ criterion for insulation reliability ]

O: resistance value of 10 ⁸ The number of the connection structures with the omega or more is 20

O: resistance value of 10 ⁸ The number of the connection structures is 18 or more and less than 20

O: resistance value of 10 ⁸ The number of the connection structures is 15 or more and less than 18

Delta: resistance value of 10 ⁸ The number of the connection structures is more than 10 and less than 15

X: resistance value of 10 ⁸ The number of the connection structures with the number of omega or more is less than 10

The results are shown in tables 1 and 2 below.

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The conductive particles obtained in examples 1 to 12 were suppressed in magnetic aggregation as compared with the conductive particles obtained in comparative examples 1 to 4.

The conductive particles obtained in examples 1 to 7 and 10 to 12 showed a lower connection resistance than the conductive particles obtained in example 8. This is because: in the conductive particles obtained in example 8, the conductive layer was less exposed because the entire surface of the conductive particle body was covered with the insulating portion, whereas in the conductive particles obtained in examples 1 to 7 and 10 to 12, the conductive layer was more exposed because the soft magnetic particles were covered with the insulating layer.

The conductive particles obtained in examples 1 to 7 and 10 to 12 showed a lower connection resistance than the conductive particles obtained in example 9. This is because: in the conductive particles obtained in example 9, the average particle diameter of the soft magnetic particle-coated insulating particles in which the iron oxide nanoparticles having an average particle diameter of 30nm were attached to the insulating particles having an average particle diameter of 300nm was large (average particle diameter exceeding 300 nm), whereas the average particle diameter of the insulating layer-coated soft magnetic particles was small (average particle diameter of 50 to 130 nm) in the conductive particles of examples 1 to 7 and 10 to 12. Therefore, when thermocompression bonding is performed in the process of producing the connection structure, the insulating particles are hardly detached from the surfaces of the conductive particles in the conductive particles of example 9, whereas the insulating layer-coated soft magnetic particles are easily detached from the surfaces of the conductive particles in the conductive particles of examples 1 to 7 and 10 to 12.

Symbol description

1 … conductive particles

2 … substrate particles

3 … conductive part

11 … conductive particles

12 … Soft magnetic part

13 … insulating particles

21 … conductive particles

22 … insulation part

31 … conductive particles

32 … insulation part

41 … conductive particles

42 … insulation part

51 … conductive particles

52 … insulation part

61 … conductive portions

62 … core material

63 … projection

81 and … connection structure

82 … first connection object part

82a … first electrode

83 … second connection object part

83a … second electrode

84 … connection

Claims

1. A conductive particle is provided with:

substrate particles

A conductive portion disposed on the surface of the base material particle,

the ratio of the residual magnetization to the saturation magnetization of the conductive particles is 0.6 or less.

2. The conductive particle according to claim 1, wherein,

the remanent magnetization is 0.02A/m or less.

3. The conductive particle according to claim 1 or 2, comprising a soft magnetic portion disposed on an outer surface of the conductive portion.

4. The conductive particle according to claim 3, wherein the conductive particle comprises an insulating portion disposed between the conductive portion and the soft magnetic portion,

the soft magnetic portion is disposed on an outer surface of the conductive portion through the insulating portion.

5. The conductive particle according to claim 4, wherein,

the distance between the conductive part and the soft magnetic part is 10 nm-500 nm.

6. The conductive particle according to claim 3 to 5, which comprises a plurality of the soft magnetic portions,

The plurality of soft magnetic portions are disposed on the outer surface of the conductive portion so as to be spaced apart from each other.

7. The conductive particle according to claim 3 to 6, wherein,

the area of the portion of the conductive portion surface covered by the soft magnetic portion is 30% or more of the entire surface area of the conductive portion.

8. The conductive particle according to claim 7, wherein,

the area of the portion of the conductive portion surface covered by the soft magnetic portion is 40% or more of the entire surface area of the conductive portion.

9. The conductive particle according to any one of claims 1 to 8, comprising a plurality of insulating particles disposed on an outer surface of the conductive portion.

10. An electroconductive material comprising the electroconductive particles according to any one of claims 1 to 9, and a binder resin.

11. A connection structure is provided with:

a first connection object member having a first electrode on a surface thereof,

a second connection object member having a second electrode on the surface, an

A connecting portion that connects the first connection object member and the second connection object member together,

the material of the connecting portion is the conductive particles according to any one of claims 1 to 9, or a conductive material containing the conductive particles and a binder resin;

The first electrode and the second electrode are electrically connected by the conductive portion in the conductive particle.