WO2017051842A1 - Conductive particles, conductive material, and connection structure - Google Patents

Abstract

Provided are conductive particles that make it easy to prevent decreases in the insulating properties of conductive particles and that make it possible to minimize the agglomeration of conductive particles. These conductive particles comprise a substrate particle and a metal layer that covers the surface of the substrate particle. The surface of the metal layer is covered by a resin and an inorganic material. The resin may contain resin particles and the inorganic material may contain inorganic particles. The conductive particles make it easy to prevent decreases in the insulating properties thereof and are unlikely to agglomerate as a result of the surface of the metal layer being covered by the resin and the inorganic material.

Description

Conductive particles, conductive materials, and connection structures

The present invention relates to conductive particles that can be used for electrical connection between electrodes, for example.

Conventionally, anisotropic conductive materials such as anisotropic conductive paste and anisotropic conductive film have been used for connection between an IC chip and a flexible printed circuit board, or connection between an IC chip and a circuit board having an ITO electrode. It is used. More specifically, the anisotropic conductive material includes a connection between a flexible printed circuit board and a glass substrate (FOG; Film on Glass), a connection between a semiconductor chip and a flexible printed circuit board (COF; Chip on Film), and a semiconductor chip. And a glass substrate (COG; Chip on Glass) and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB; Film on Board). The anisotropic conductive material is disposed, for example, between an electrode of an IC chip and an electrode of a circuit board, and further enables electrical connection between these electrodes by heating and pressurization.

The above anisotropic conductive material is generally formed by dispersing conductive particles in paste, ink or resin. In recent years, from the viewpoint of enhancing the performance of anisotropic conductive materials, development of conductive particles contained in anisotropic conductive materials has been promoted. For example, the surface of base particles can be coated with other materials. Attempts to improve the performance of conductive particles have been actively made. For example, Patent Document 1 discloses conductive particles coated with silica. By including such silica-coated conductive particles in an anisotropic conductive material, when the anisotropic conductive material is used for electrical connection between electrodes, both conduction reliability and insulation reliability are obtained. Enhanced.

JP 2014-241281 A

However, in the technique disclosed in Patent Document 1, silica is easily dropped from the conductive particles, and the silica is dropped from the conductive particles, thereby causing a decrease in the insulating properties of the conductive particles. Further, there is a problem in that the silica is easily aggregated due to the silica falling off from the conductive particles, and the monodispersity of the conductive particles is gradually impaired. From the above viewpoints, it is important to develop a technique for suppressing a decrease in insulation and agglomeration of the conductive particles contained in the anisotropic conductive material.

The present invention has been made in view of the above, and it is easy to prevent a decrease in the insulating properties of the conductive particles, and it is possible to suppress the aggregation of the conductive particles, and the conductive particles. It is an object to provide a conductive material and a connection structure having the following.

As a result of earnest research to achieve the above object, the present inventor has found that the above object can be achieved by coating particles that serve as a base material for conductive particles in combination with a resin and an inorganic material. The invention has been completed.

That is, the present invention includes, for example, the subject matters described in the following sections.
Item 1. Conductive particles comprising base particles and a metal layer covering the surface of the base particles,
Conductive particles in which the surface of the metal layer is coated with a resin and an inorganic material.
Item 2. Item 2. The conductive particle according to Item 1, wherein the resin includes resin particles.
Item 3. Item 3. The conductive particle according to Item 1 or 2, wherein the inorganic material includes inorganic particles.
Item 4. The conductive particle according to Item 1, wherein the resin includes resin particles, the inorganic material includes inorganic particles, and a ratio of an average particle diameter of the inorganic particles to the resin particles is 1/50 or more and 1 or less. .
Item 5. Item 5. The conductive particle according to Item 3 or 4, wherein the coverage of the inorganic particle is 80% or more.
Item 6. Items 1 to 5 above, wherein a resin layer coated with the resin is formed on the surface of the metal layer, and an inorganic layer coated with the inorganic material is formed on the surface of the resin layer. Electroconductive particle of any one of these.
Item 7. A conductive material comprising the conductive particles according to any one of Items 1 to 6 and a binder resin.
Item 8. A first connection object member having a first electrode on its surface;
A second connection target member having a second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member;
The material of the connecting portion includes the conductive particles according to any one of Items 1 to 6 or the conductive material according to Item 7.
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles or the conductive material.

The conductive particles according to the present invention include base particles and a metal layer that covers the surface of the base particles, and since the surface of the metal layer is coated with a resin and an inorganic material, the conductive particles It is easy to prevent the lowering of the insulating property, and the aggregation of the conductive particles hardly occurs.

An example of a connection structure provided with the electroconductive particle of this invention is shown, and it is the schematic of the cross section.

Hereinafter, embodiments of the present invention will be described in detail.

In the following description, a chemical substance including the term “(meth) acryl” means one or both of “acryl” and “methacryl”. For example, “(meth) acryl” means one or both of “acryl” and “methacryl”, and “(meth) acrylate” means one or both of “acrylate” and “methacrylate”.

In addition, in this specification, the expressions “containing” and “including” include concepts of “containing”, “including”, “consisting essentially of”, and “consisting only of”.

The conductive particles of the present embodiment include base particles and a metal layer that covers the surface of the base particles, and the surface of the metal layer is coated with a resin and an inorganic material. Such conductive particles are less likely to cause a decrease in insulation and aggregation of the conductive particles. Hereinafter, the structure of the electroconductive particle of this embodiment is explained in full detail.

Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles.

For example, when an anisotropic conductive material having conductive particles is used for COG or the like, generally, after connecting the conductive particles between the electrodes, Compress. For this reason, since the conductive particles are formed of a material that is easily deformed by the compression, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is increased. From such a viewpoint, the base particles are preferably resin particles that are easily deformable by the compression.

When the substrate particles are resin particles, various organic materials are suitably used as a material for forming the resin particles. Examples of such materials include polyethylene resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylene terephthalate, polysulfone, Polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, epoxy resin, saturated polyester resin, unsaturated polyester resin, polyphenylene oxide, polyacetal, polyimide, polyamideimide , Polyetheretherketone and polyethers Hong, urea resins.

The resin particles can also be obtained by polymerizing one or more kinds of various polymerizable monomers having an ethylenically unsaturated group. In this case, it is possible to design and synthesize resin particles having physical properties at the time of compression suitable for anisotropic conductive materials. In this case, the hardness of the base particle can be easily controlled within a suitable range. From such a viewpoint, the material of the resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer and / or a crosslinkable monomer. These monomers are mentioned.

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; (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 ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; acids such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate Atom-containing (meth) acrylates; Nitrile-containing monomers such as (meth) acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether; Vinyl acetates such as vinyl acetate, vinyl butyrate, vinyl laurate and vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol 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) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane, etc. Can be mentioned.

The crosslinkable and non-crosslinkable monomers are not limited to the monomers listed above, but may be other polymerizable monomers, for example, known polymerizable monomers.

The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include suspension polymerization in the presence of a radical polymerization initiator, and polymerization by swelling monomers together with a radical polymerization initiator using non-crosslinked seed particles (so-called seed weight). Legal).

When the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, examples of the inorganic material that is a material of the substrate particles include silica and carbon black. This inorganic substance is preferably not a metal. The particles formed from the silica are not particularly limited. For example, after forming a crosslinked polymer particle by hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups, firing may be performed as necessary. The particle | grains obtained by performing are mentioned. Examples of the organic / inorganic hybrid particles include organic / inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

When the base particles are metal particles, examples of the metal that is a material of the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the substrate particles are preferably not metal particles.

The average particle diameter of the base material particles is not particularly limited. For example, the average particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, still more preferably 1.5 μm or more, particularly preferably 2 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, still more preferably 100 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm or less. it can. When the average particle diameter of the base particles is equal to or more than the above lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is further increased and the conductive particles are connected via the conductive particles. The connection resistance between the electrodes is further reduced. Furthermore, when forming a metal layer on the surface of a base particle by electroless plating, it becomes difficult to aggregate and it becomes difficult to form the aggregated electroconductive particle. When the average particle diameter of the substrate particles is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes can be further reduced, and the interval between the electrodes can be further narrowed. .

The average particle diameter of the substrate particles is particularly preferably 0.1 μm or more and 5 μm or less. When the average particle diameter of the substrate particles is in the range of 0.1 or more and 5 μm or less, even when the distance between the electrodes is small and the metal layer is thick, small conductive particles can be obtained. From the viewpoint of being able to obtain even smaller conductive particles even when the distance between the electrodes can be further reduced, or even if the thickness of the metal layer is increased, the average particle size of the base particles is The thickness is preferably 0.5 μm or more, more preferably 2 μm or more, and preferably 3 μm or less. From the viewpoint of further improving the conduction reliability, the average particle diameter of the base material particles is 2.5 μm or more.

The average particle diameter of the base material particles indicates a number average particle diameter. The average particle diameter can be measured using, for example, a Coulter counter (manufactured by Beckman Coulter).

In addition, the form of the base material particle | grains mentioned above is an example for using for the electroconductive particle of this embodiment, and the other well-known base material particle | grains used as electroconductive particle are the electroconductive particle of this embodiment. It can also be applied to.

The metal layer is a layer formed so as to cover the surface of the substrate particles.

The thickness of the metal layer is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, particularly preferably 50 nm or more, preferably 1000 nm or less, more preferably 800 nm or less, still more preferably 500 nm or less, particularly preferably 400 nm or less, most preferably 300 nm or less. When the thickness of the metal layer is not less than the above lower limit, the conductivity of the conductive particles is further improved. When the thickness of the metal layer is not more than the above upper limit, the difference in coefficient of thermal expansion between the base particle and the metal layer becomes small, and the metal layer becomes difficult to peel from the base particle. The metal layer may be formed in multiple layers, and the thickness of the metal layer in this case refers to the thickness of the entire metal layer formed in the multilayer.

Examples of the method for forming the metal layer on the surface of the substrate particles include a method for forming the metal layer by electroless plating and a method for forming the metal layer by electroplating. In addition, as a method for forming the metal layer on the surface of the substrate particles, a known method may be adopted.

The metal layer is formed of a material containing a metal, and the type of the metal 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, and alloys thereof. Further, tin-doped indium oxide (ITO) may be used as the metal. The metal layer may be formed of only one kind of metal or may be formed of two or more kinds of metals.

In addition, the form of the metal layer mentioned above is an example for using for the electroconductive particle of this embodiment, In addition, the well-known metal layer used as electroconductive particle is applied to the electroconductive particle of this embodiment. You can also

In the conductive particles of the present embodiment, for example, the substrate particles may have a plurality of protrusions on the surface. For example, in COG or the like, an oxide film is often formed on the surface of an electrode connected by conductive particles. Therefore, when conductive particles having protrusions are used, the oxide film can be effectively removed by the protrusions by placing the conductive particles between the electrodes and pressing them. As a result, the electrode and the conductive particles are more reliably in contact with each other, and the connection resistance between the electrodes is further reduced. Furthermore, since the insulating layer between the conductive particles and the electrode is effectively eliminated by the protrusion, the conduction reliability between the electrodes is increased. In addition, an insulating layer here shows the layer formed with the resin and inorganic material which are formed in electroconductive particle so that it may mention later. In addition, when the conventional conductive particles coated with silica as in Patent Document 1 have protrusions, the problem of silica falling off can become even more serious. When the substrate particles have protrusions, the above problem can be solved. From this viewpoint, it is preferable to have protrusions.

As a method for forming the protrusions, a core material is attached to the surface of the base particle, and then a metal layer is formed by electroless plating, and a metal layer is formed on the surface of the base particle by electroless plating. Thereafter, a method of attaching a core substance and further forming a metal layer by electroless plating may be used. Furthermore, as another method for forming the protrusion, after forming the first metal layer on the surface of the base particle, a core substance is disposed on the first metal layer, and then the second metal layer is formed. Examples thereof include a method of forming a metal layer, and a method of adding a core substance in the middle of forming the metal layer on the surface of the base particle.

As a method of attaching the core substance to the surface of the base particle, for example, a core substance is added to the dispersion of the base particle, and the core substance is applied to the surface of the base particle by, for example, van der Waals force. Examples thereof include a method of accumulating and adhering, and a method of adding a core substance to a container containing base particles and attaching the core substance to the surface of the base particles by a mechanical action such as rotation of the container. Among these, from the viewpoint that it is easy to control the amount of the core substance to be attached, a method in which the core substance is accumulated on the surface of the substrate particles in the dispersion and attached is preferable.

The material of the core substance includes a conductive substance and a non-conductive substance. Examples of the conductive substance include metals, metal oxides, conductive non-metals such as graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the nonconductive material include silica, alumina, and zirconia. Especially, a metal is preferable at the point which can raise electroconductivity and can make connection resistance low effectively. The core substance is preferably metal particles.

Examples of the metal include gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and tin-lead. Examples thereof include alloys composed of two or more metals such as alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and tungsten carbide. Of these, nickel, copper, silver or gold is preferable. The metal that is the material of the core substance may be the same as or different from the metal that is the material of the metal layer. The material of the core substance preferably includes nickel. Examples of the metal oxide include alumina, silica and zirconia.

The shape of the core substance is not particularly limited. The shape of the core substance is preferably a lump. Examples of the core substance include a particulate lump, an agglomerate in which a plurality of fine particles are aggregated, and an irregular lump.

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

The average diameter (average particle diameter) of the core substance indicates a number average diameter (number average particle diameter). The average diameter of the core material is obtained by observing 50 arbitrary core materials with an electron microscope or an optical microscope and calculating an average value. When measuring the average diameter of the core substance in the conductive particles, for example, the average diameter of the core substance can be measured as follows. The conductive particles are added to and dispersed in “Technobit 4000” manufactured by Kulzer so that the content is 30% by weight, and an embedded resin for inspecting conductive particles is produced. The cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass through the vicinity of the center of the dispersed conductive resin in the embedded resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 50,000 times, 20 conductive particles were randomly selected, and 50 protrusions of each conductive particle were selected. Observe. The diameter of the core substance in the obtained conductive particles is measured, and arithmetically averaged to obtain the average diameter of the core substance.

The average height of the protrusions in the conductive particles is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average height of the protrusions is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes is effectively reduced.

When measuring the average height of the protrusions in the conductive particles, for example, the average height of the protrusions can be measured as follows. The conductive particles are added to and dispersed in “Technobit 4000” manufactured by Kulzer so that the content is 30% by weight, and an embedded resin for inspecting conductive particles is produced. The cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass through the vicinity of the center of the dispersed conductive resin in the embedded resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 50,000 times, 20 conductive particles were randomly selected, and 50 protrusions of each conductive particle were selected. Observe. The height from the bottom of the protrusion to the top of the protrusion is taken as the height of the protrusion, and the arithmetic average is taken as the average height of the protrusion.

As described above, if the core substance is embedded in the metal layer, the protrusion can be easily formed on the outer surface of the metal layer.

The surface of the metal layer is further coated with a resin and an inorganic material. That is, the surface of the metal layer includes a layer formed by coating with a resin and an inorganic material. Hereinafter, a layer formed by coating with a resin and / or an inorganic material may be referred to as an “insulating layer”.

Examples of the resin include insulating resin materials. Specifically, polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked thermoplastic resins, A thermosetting resin, a water-soluble resin, etc. are mentioned. In addition, the same resin as the resin forming the base particle may be used.

Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic ester copolymer.

Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate.

Examples of the block polymer include polystyrene, styrene-acrylate copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof.

Examples of the thermoplastic resin include the resins exemplified above, and other vinyl polymers and vinyl copolymers.

Examples of the thermosetting resin include epoxy resins, phenol resins, and melamine resins.

Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, and methylcellulose. Of these, polyvinyl alcohol is more preferable as the water-soluble resin.

The shape of the resin is not particularly limited. For example, the shape of the resin can be made particulate. That is, the resin preferably contains resin particles. Hereinafter, the resin particles are sometimes referred to as insulating resin particles. When the resin contains insulating resin particles, the average particle diameter of the insulating particles can be made smaller than the average particle diameter of the conductive particles. Specifically, the average particle diameter of the insulating resin particles is preferably 0.01 μm or more, more preferably 0.1 μm or more, preferably 1.0 μm or less, more preferably 0.5 μm or less. By adjusting the average particle diameter of the insulating resin particles to the above range, the insulating particles are unlikely to come off when the binder is dispersed, and particle contact can be prevented. Moreover, since it is effectively eliminated when connecting the electrodes, a low resistance can be ensured. In addition, the average particle diameter of insulating resin particle here is the same definition as the average particle diameter of the base material particle | grains mentioned above.

The insulating particles can be prepared, for example, by (co) polymerizing one or more monomers having an unsaturated double bond. Examples of the monomer having an unsaturated double bond include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth). Acrylate, glycidyl (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (Meth) acrylates such as (meth) acrylate and 1,4-butanediol di (meth) acrylate; vinyl ethers; vinyl chloride; styrene compounds such as styrene and divinylbesen, acrylonitrile, etc. That. In addition, the monomer may be a known polymerizable monomer. Of these, (meth) acrylic acid esters are preferably used.

Further, the resin is not in the form of particles but may be in the form of a film, for example. When the resin is in the form of a film, the thickness is preferably 10 nm or more, more preferably 100 nm or more, preferably 1000 nm or less, more preferably 500 nm or less. By adjusting the thickness of the insulating resin to the above range, it is difficult for the insulating particles to come off when the binder is dispersed, and particle contact can be prevented. Moreover, since it is effectively eliminated when connecting the electrodes, a low resistance can be ensured.

The thickness of the resin can be measured as follows. For example, the conductive particles are added to and dispersed in “Technobit 4000” manufactured by Kulzer so that the content of the conductive particles is 30% by weight, and an embedded resin for conductive particle inspection is produced. A cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass through the vicinity of the center of the conductive particles dispersed in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 20 conductive particles are randomly selected, and an insulating resin film of each conductive particle is selected. Observe. The thickness of the insulating resin film in the obtained conductive particles is measured, and arithmetically averaged to obtain the thickness of the insulating resin film.

The resin may be a polymer electrolyte in addition to the insulating resin particles. As the polymer electrolyte, a polymer (polyanion or polycation) ionized in an aqueous solution and having a charged functional group in the main chain or side chain can be used. Examples of polyanions generally include those having a negatively charged functional group such as sulfonic acid, sulfuric acid, carboxylic acid, and the like, which are appropriately selected according to the surface potential of the conductive particles and the insulating layer. Can do. The polycation generally has a positively charged functional group such as polyamines such as PEI, polyallylamine hydrochloride (PAH), PDDA, polyvinyl pyridine (PVP), polylysine, polyacrylamide. And a copolymer containing at least one of them can be used.

The inorganic material is not particularly limited as long as it is a material formed of an inorganic substance. In the present embodiment, the inorganic material preferably contains inorganic particles.

Examples of the inorganic particles include shirasu particles, hydroxyapatite particles, magnesia particles, zirconium oxide particles, silica particles, alumina particles, and zirconia particles. In addition, as said inorganic particle, the particle | grains formed with a well-known inorganic element or an inorganic compound may be sufficient.

Examples of the silica particles include pulverized silica and spherical silica. Silica particles may have a functional group capable of chemical bonding such as a carboxyl group and a hydroxyl group on the surface.

The average particle diameter of the inorganic particles is preferably 0.001 μm or more, more preferably 0.005 μm or more, preferably 1.0 μm or less, more preferably 0.5 μm or less, and further preferably 0.2 μm or less. . By adjusting the average particle diameter of the inorganic particles to the above range, the insulating particles are unlikely to come off when the binder is dispersed, and particle contact can be prevented. Further, since it is effectively eliminated when connecting the electrodes, a low resistance can be ensured and appropriate insulation can be exhibited. In addition, the average particle diameter of an inorganic particle here is the same definition as the average particle diameter of the base material particle | grains mentioned above.

The inorganic material is not limited to inorganic particles, and may be in the form of a film formed of an inorganic compound, for example. A film formed of such an inorganic compound can be formed by, for example, a known method, but the formation method is not particularly limited.

The structure of the insulating layer (that is, a layer containing a resin and an inorganic material) is not particularly limited.

For example, the insulating layer may be formed by laminating a resin layer formed of a resin and an inorganic layer formed of an inorganic material in this order from the metal layer side. That is, in this case, a resin layer that is coated with the resin is formed on the surface of the metal layer, and an inorganic layer that is coated with the inorganic material is formed on the surface of the resin layer. It becomes. The resin layer may contain a material other than the resin, or may be composed of only the resin. The inorganic layer may contain a material other than the inorganic material, or may be composed of only the inorganic material.

As another form of the insulating layer, the insulating layer may be formed by laminating an inorganic layer formed of an inorganic material and a resin layer formed of a resin in this order from the metal layer side. That is, in this case, the surface of the metal layer is formed with an inorganic layer coated with the inorganic material, and the surface of the inorganic layer is formed with a resin layer coated with the resin. It becomes.

The exemplified insulating layer is formed in at least a two-layer structure including a resin layer and an inorganic layer, but is not limited thereto. For example, the insulating layer may be formed of a material containing a mixture of the resin and the inorganic material and have a single layer structure.

Among the above, the surface of the metal layer is formed with a resin layer coated with the resin, and the surface of the resin layer is formed with an inorganic layer coated with the inorganic material. A structure is preferred. In this case, even if the outermost inorganic layer falls off, the resin layer is present on the surface, so that the insulating property of the conductive particles is hardly lowered. In addition, the presence of the inorganic layer in the outermost layer increases the repulsive action between the conductive particles, so that the aggregation of the conductive particles hardly occurs and the monodispersity of the conductive particles is improved. In particular, when the inorganic layer includes silica particles, it is easy to improve the monodispersity of the conductive particles.

When the resin forming the insulating layer is resin particles and the inorganic material is inorganic particles, the ratio of the average particle diameter of the inorganic particles to the resin particles is preferably 1/50 or more, more preferably 1/30 or more. More preferably, it is 1/10 or more, preferably 1 or less, more preferably 1/2 or less. When the ratio of the average particle diameter of the inorganic particles to the resin particles is 1/50 or more, the insulating particles are easily aggregated and the covering property is improved. When the ratio of the average particle diameter of the inorganic particles to the resin particles is 1 or less, the adhesion between the plating surface (metal layer), the resin particles, and the inorganic particles becomes high.

For example, the average particle diameter of the resin particles can be 0.2 μm or more and 1 μm or less, and the average particle diameter of the inorganic particles can be 0.01 μm or more and 0.2 μm or less. In this case, since the thickness of the insulating layer does not become too thick, the electrical connection by the metal layer is more reliably achieved, and the adhesion between the resin particles and the inorganic particles is also increased.

The average particle diameter of the resin particles and inorganic particles indicates the number average particle diameter, and can be measured using a commercially available particle size distribution measuring device or the like. For example, it can be obtained by using a particle size distribution measuring device such as Nikkiso Microtrac “UPA-EX-150”. When measuring the average particle diameter of the resin particles and inorganic particles in the conductive particles, for example, the average particle diameter of the resin particles and inorganic particles can be measured as follows. The conductive particles are added to and dispersed in “Technobit 4000” manufactured by Kulzer so that the content is 30% by weight, and an embedded resin for inspecting conductive particles is produced. The cross section of the conductive particles is cut out using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation) so as to pass through the vicinity of the center of the dispersed conductive resin in the embedded resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 50,000 times, 20 conductive particles were randomly selected, and the average particle of each resin particle and inorganic particle Observe 50 diameters. The average particle diameters of the resin particles and the inorganic particles in the obtained conductive particles are measured, and are arithmetically averaged to obtain the average particle diameter of the resin particles and the inorganic particles.

The CV value of the resin particles and inorganic particles is preferably 20% or less. When the CV value is 20% or less, the thickness of the insulating layer becomes uniform. For example, when applying conductive particles to applications such as COG, a uniform pressure is applied when thermocompression bonding between electrodes. It becomes easy and it becomes difficult to produce poor conduction. The CV value of the particle diameter is calculated by the following formula.
CV value of particle diameter (%) = standard deviation of particle diameter / average particle diameter × 100
The particle size distribution can be measured with a particle size distribution meter or the like before coating the conductive part of the conductive particles, and can be measured with image analysis of an SEM photograph after coating.

The average thickness of the insulating layer is not limited and can be any thickness. In particular, if the average thickness of the insulating layer is larger than the thickness of the protrusions described above, the effect of the insulating layer can be sufficiently exerted, the insulating property is hardly lowered, and the aggregation of conductive particles is prevented. It becomes easy to be done.

The average thickness of the insulating layer is preferably 5 nm or more from the viewpoint that when applying conductive particles to applications such as COG, leakage is unlikely to occur and the pressure and amount of heat necessary for thermocompression bonding can be reduced. More preferably, it is 10 nm or more, preferably 1000 nm or less, more preferably 500 nm or less.

In the conductive particles of the present embodiment, when the inorganic material forming the insulating layer is inorganic particles, the coverage of the inorganic particles with respect to the conductive particles is preferably 80% or more. In this case, it is easy to prevent a decrease in the insulating properties of the conductive particles, and since the conductive particles have a more nearly spherical shape, it is easy to suppress the aggregation of the conductive particles. Monodispersity can be improved. The upper limit of the coverage of inorganic particles is 100%. Moreover, when the resin which forms the said insulating layer is a resin particle, it is preferable that the coverage of the resin particle with respect to electroconductive particle is 40% or more. The upper limit of the resin particle coverage is 100%.

In addition, a coverage here means the ratio for which the total area of the part coat | covered with the inorganic particle accounts in the whole surface area of electroconductive particle (or inner layer (for example, resin layer) of an inorganic layer). The surface area of the inner layer of the inorganic layer can be determined by calculating the surface area of the sphere by regarding the conductive particles excluding the inorganic layer as a sphere.

For example, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 20 conductive particles are randomly selected, and the surface of each conductive particle is observed. . In the obtained conductive particles, the percentage of the surface area of the portion covered with the inorganic particles with respect to the projected area of the whole particles is measured, and this is arithmetically averaged to obtain the coverage.

Also, the coverage of the inorganic layer and the resin layer can be measured by mapping analysis such as EDX attached to the SEM.

The above-described coverage can be adjusted by, for example, the amount of inorganic particles added to the base material particles, the mixing time, etc., and the method for adjusting the coverage is not particularly limited.

The above resin (for example, resin particles) and inorganic material (for example, inorganic particles) preferably have a reactive functional group capable of chemical bonding such as covalent bonding. In this case, the adhesiveness between the resin (for example, resin particles) and the inorganic material (for example, inorganic particles) becomes stronger, and it is easy to prevent them from falling off the conductive particles.

Examples of the reactive functional group include vinyl group, (meth) acryloyl group, silane group, silanol group, carboxyl group, amino group, ammonium group, nitro group, hydroxyl group, carbonyl group, thiol group, sulfonic acid group, and sulfonium. Group, boric acid group, oxazoline group, pyrrolidone group, phosphoric acid group and nitrile group. Among these, a vinyl group and a (meth) acryloyl group are preferable.

The reactive functional group can be introduced by surface treatment with a compound for introducing a reactive functional group into a resin (for example, resin particles) and an inorganic material (for example, inorganic particles). Examples thereof include a compound having a (meth) acryloyl group, a compound having an epoxy group, and a compound having a vinyl group.

Examples of the compound (surface treatment substance) for introducing a vinyl group include a silane compound having a vinyl group, a titanium compound having a vinyl group, and a phosphate compound having a vinyl group. The surface treatment substance is preferably a silane compound having a vinyl group. Examples of the silane compound having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and vinyltriisopropoxysilane.

As a compound (surface treatment substance) for introducing a (meth) acryloyl group, a silane compound having a (meth) acryloyl group, a titanium compound having a (meth) acryloyl group, and a phosphoric acid having a (meth) acryloyl group Compounds and the like. The surface treatment substance is also preferably a silane compound having a (meth) acryloyl group. Examples of the silane compound having a (meth) acryloyl group include (meth) acryloxypropyltriethoxysilane, (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltridimethoxysilane, and the like.

The method for forming the insulating layer on the surface of the metal layer is not particularly limited, and a known method can be employed. Examples of such methods include chemical methods and physical or mechanical methods. As the chemical method, there is a method in which a resin (for example, resin particles) and an inorganic material are attached to the surface of the metal layer by a hetero-aggregation method using van der Waals force or electrostatic force, and further chemically bonded as necessary. Can be mentioned. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. Among these, a method in which a resin (for example, resin particles) and an inorganic material are attached to the surface of the conductive layer through a chemical bond is preferable because an insulating substance is difficult to be detached.

In forming the insulating layer on the surface of the metal layer, it is preferable to first attach the resin to the metal layer and then attach the inorganic material to the metal layer. In this case, since the adhesion between the metal surface and the insulating layer is likely to be high, peeling of the insulating layer can be suppressed. For example, if resin particles are first attached to the metal layer and then inorganic particles are attached to the metal layer, inorganic particles having a small average particle diameter may enter between resin particles having a large average particle diameter. The insulating layer can be formed in a state where the inorganic particles are included in the resin layer. An inorganic particle layer may be further formed on the surface of the insulating layer thus formed. In this case, the insulating layer is formed of a resin layer containing inorganic particles and an inorganic layer formed of inorganic particles. The On the other hand, when the inorganic particles have a size that does not enter the voids of the resin layer, the inorganic particles do not enter the voids of the resin layer, and become an insulating layer having an inorganic layer formed on the surface of the resin layer.

In forming the insulating layer on the surface of the metal layer, the resin particles and the inorganic particles can be attached to the metal layer by the same method, but it is not necessarily required to be attached to the metal layer by the same method. For example, the resin particles may be attached to the insulating layer by hetero-aggregation and chemically bonded to the surface of the metal layer, and the inorganic particles may be physically coated on the surface of the resin layer by a method such as hybridization.

In addition, the surface of the metal layer and the insulating layer may not be directly chemically bonded, but may be indirectly chemically bonded by a compound having a reactive functional group. For example, after introducing a carboxyl group to the surface of the metal layer, the carboxyl group may be chemically bonded to a functional group on the surface of the insulating layer via a polymer electrolyte such as polyethyleneimine. The polymer electrolyte that can be used here can be the same as the polymer electrolyte described above.

The conductive particles according to the present embodiment include base particles and a metal layer that covers the surface of the base particles, and the surface of the metal layer is covered with a resin and an inorganic material. It can be a material having a large coating amount of the insulating layer compared to the particles. Thereby, since the insulation of electroconductive particle improves, it is easy to prevent a fall of insulation. Moreover, since the coating amount of the insulating layer in the conductive particles is large, aggregation of the conductive particles is easily suppressed, and as a result, the monodispersity of the conductive particles is also improved. In particular, when the outermost layer of the conductive particles is silica particles, aggregation of the conductive particles is more easily suppressed.

And, when the conductive particles are applied to, for example, COG and the electrodes are connected, a short circuit between adjacent electrodes can be suppressed. Specifically, even if a plurality of conductive particles are in contact with each other between the electrodes, the presence of an insulating material (insulating layer) between the plurality of electrodes suppresses a short circuit between electrodes adjacent in the lateral direction. You can also. In addition, by pressurizing the conductive particles with the two electrodes at the time of connection between the electrodes, the insulating substance (insulating layer) existing between the conductive portion (metal layer) of the conductive particles and the electrode can be easily obtained. Eliminated. And when an electroconductive particle has a processus | protrusion on the surface of a metal layer, an insulating substance (insulating layer) is excluded much more easily.

The conductive particles of the present embodiment have an insulating layer containing a resin and an inorganic material, and thus have an appropriate hardness and an appropriate recoverability after compression. Therefore, the electroconductive particle of this embodiment can be used especially suitably for COG in which hardness and recoverability are calculated | required.

Specifically, in the conductive particles of this embodiment, the stress at 10% compression (10% K value) is preferably 3000 or more and 15000 N / mm ² or less, and the recovery rate is preferably 30% or more and 80% or less. Thus, the electroconductive particle of this embodiment is a material which is excellent also in hardness and a recoverability by having the above-mentioned insulating layer. In particular, when the conductive particles of the present embodiment are applied to COG, the stress at 10% compression (10% K value) is preferably 5000 or more and 12000 N / mm ² or less, and the recovery rate is 40. % Or more and 70% or less is preferable.

The 10% K value of the conductive particles can be measured as follows. Using a micro-compression tester, one conductive particle is compressed with a smooth indenter end face of a cylinder (diameter 50 μm, made of diamond) under the condition that a maximum test load of 90 mN is applied for 30 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.
K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the conductive particles are 10% compressively deformed (N)
S: Compression displacement (mm) when the conductive particles are 10% compressively deformed
R: radius of conductive particles (mm)
The recovery rate is determined by adding the maximum test load of 10 mN to one particle and then unloading the load in the same apparatus as described above. The compression displacement L1 (mm) and the recovery displacement L2 (mm) at this time are measured. It can obtain | require with the following formula from the obtained measured value.
Recovery rate (%) = (L2 / L1) × 100
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 conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

The binder resin is not particularly limited. As the binder resin, a known insulating resin is used. The binder resin preferably includes a thermoplastic component (thermoplastic compound) or a curable component, and more preferably includes a curable component. Examples of the curable component include a photocurable component and a thermosetting component.

The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent.

Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin.

Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, polyamide resin, and the like.

Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent.

Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogenated products of styrene block copolymers.

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

In addition to the conductive particles and the binder resin, the conductive material includes, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer. Various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant may be contained.

The conductive material can be used as a conductive paste and a conductive film. When the conductive material is a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes 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% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably It is 99.99 weight% or less, More preferably, it is 99.9 weight% or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further increased.

In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight. Hereinafter, it is more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is not less than the above lower limit and not more than the above upper limit, the conduction reliability between the electrodes is further enhanced.

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the conductive particles described above or using a conductive material including the conductive particles described above and a binder resin.

As shown in FIG. 1 as an example, the connection structure 81 connects the first connection target member 82, the second connection target member 83, and the first connection target member and the second connection target member. It is preferable that the material that includes the connecting portion 84 and that forms the connecting portion is the conductive particle 1 described above or a conductive material that includes the conductive particle 1 and the binder resin described above. It is preferable that the connection part is a connection structure formed of the above-described conductive particles or a conductive material including the above-described conductive particles and a binder resin. When the conductive particles are used alone, the connection part itself is the conductive particles. That is, the first and second connection target members are connected by the conductive particles. The conductive material used for obtaining the connection structure is preferably an anisotropic conductive material.

The first connection object member preferably has a first electrode 82a on the surface. The second connection object member preferably has a second electrode 83a on the surface. It is preferable that the first electrode 82 a and the second electrode 83 a are electrically connected by the conductive particles 1.

The manufacturing method of the connection structure is not particularly limited. As an example of a method of manufacturing a connection structure, a method of placing the conductive material between a first connection target member and a second connection target member to obtain a laminate, and then heating and pressurizing the laminate Etc. The pressure of the pressurization is about 9.8 × 10 ⁴ or more and 4.9 × 10 ⁶ Pa or less. The heating temperature is about 120 to 220 ° C. The pressure of the pressurization for connecting the electrode of the flexible printed board, the electrode arranged on the resin film, and the electrode of the touch panel is about 9.8 × 10 ⁴ or more and 1.0 × 10 ⁶ Pa or less.

Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. The conductive material is preferably a conductive material for connecting electronic components. The conductive paste is a paste-like conductive material, and is preferably applied on the connection target member in a paste-like state.

The conductive particles and the conductive material are also suitably used for touch panels. Therefore, the connection target member is preferably a flexible substrate or a connection target member in which electrodes are arranged on the surface of the resin film. The connection target member is preferably a flexible substrate, and is preferably a connection target member in which an electrode is disposed on the surface of the resin film. When the flexible substrate is a flexible printed substrate or the like, the flexible substrate generally has electrodes on the surface.

Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a silver electrode, a molybdenum electrode, and a tungsten electrode. When the connection object member is a flexible substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments.

Example 1
Divinylbenzene copolymer resin particles having a particle diameter of 3.0 μm (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd.) were prepared as base material particles for forming the metal layer . After dispersing 10 parts by weight of the resin particles in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the resin particles were taken out by filtering the solution. Next, the resin particles were added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the resin particles. The resin particles whose surface was activated were sufficiently washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension. Next, 1 g of metallic nickel particle slurry (average particle size 100 nm) was added to the dispersion over 3 minutes to obtain base particles to which the core substance was adhered. Suspension was obtained by adding the base material particle | grains to which the core substance was adhered to 500 weight part of distilled water, and making it disperse | distribute.

In addition, as a nickel plating solution for the previous process, a mixed solution of nickel sulfate 500 g / L, sodium hypophosphite 150 g / L, sodium citrate 150 g / L, and plating stabilizer 6 ml / L was adjusted to pH 8 with ammonia. A plating solution was prepared. 150 ml of this plating solution was added dropwise to the suspension A through a metering pump at an addition rate of 20 ml / min. The reaction temperature was set to 50 ° C. Then, it stirred until pH was stabilized, it confirmed that hydrogen foaming stopped, and the electroless-plating first stage process was performed.

Next, as a nickel plating solution for the latter process, a plating solution prepared by adjusting a mixed solution of nickel sulfate 500 g / L, dimethylamine borane 80 g / L and sodium tungstate 10 g / L to pH 11.0 with sodium hydroxide is prepared. did. 350 ml of this plating solution was dropped into the suspension through a metering pump at an addition rate of 10 ml / min. The reaction temperature was set at 30 ° C. Then, it stirred until pH was stabilized, it confirmed that the foaming of hydrogen stopped, and the electroless-plating late process was performed.

Thereafter, by filtering the suspension, the particles were taken out, washed with water, and dried to obtain base particles having a nickel conductive layer (metal layer) having protrusions on the surface of the resin particles.

Preparation of Resin Particles A 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a condenser tube and a temperature probe was charged with 100 mmol methyl methacrylate, 13 mmol ethylene glycol dimethacrylate, N, N, A monomer composition containing 1 mmol of N-trimethyl-N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride so that the solid content is 5% by weight. After weighing in ion-exchanged water, the mixture was stirred at 200 rpm and polymerized at 70 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, the resin was freeze-dried to obtain insulating resin particles having an average particle diameter of 250 nm and a CV value of 10%. The insulating resin particles were dispersed in ion exchange water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of insulating resin particles.

Inorganic particles Aerosil 50 (average particle size 30 nm) manufactured by Nippon Aerosil Co., Ltd. was used.

Production of Conductive Particles 10 g of the base particle on which the metal layer obtained as described above was placed was dispersed in 500 mL of ion exchange water, 4 g of an aqueous dispersion of insulating resin particles was added, and the mixture was stirred at room temperature for 6 hours. . After filtration through a 0.3 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles having insulating resin particles attached thereto. The insulating resin particles were covered by 40% of the particle surface.

10 g of the obtained conductive particles with insulating resin particles, 1.5 g of inorganic particles, and 100 g of zirconia spheres having an average particle diameter of 5 mm are put into a 1 L volume ball mill container and stirred for 5 hours at a rotation speed of 500 rpm, and then zirconia spheres. Then, insulating layer-coated conductive particles (also simply referred to as conductive particles) were obtained. The obtained conductive particles were coated so that the surface of the conductive particles was coated with insulating resin particles, and further the inorganic particles were covered from the upper part. Inorganic particles were coated on 98% of the particle surface.

(Examples 2 to 7)
Conductive particles in the same manner as in Example 1 except that the average particle size of the base particles, the average particle sizes of the insulating resin particles and the insulating inorganic particles, and the coating amount were changed as shown in Table 1 below. Was made.

(Example 8)
Conductive particles were produced in the same manner as in Example 1 except that 100 mmol of methyl methacrylate was changed to 150 mmol of isobutyl methacrylate when the resin particles were produced.

Example 9
Conductive particles were prepared in the same manner as in Example 1 except that the inorganic particles were changed to aluminum oxide C (average particle size 13 nm) manufactured by Nippon Aerosil Co., Ltd.

(Example 10)
The conductive particles, insulating resin particles, and inorganic particles obtained in Example 1 were prepared. After mixing 10 parts by weight of conductive particles and 10 parts by weight of insulating resin particles, the mixture is put into a hybridizer (manufactured by Nara Machinery Co., Ltd.) and treated for 1 hour, whereby a resin layer having a thickness of about 100 nm is formed on the surface of the conductive particles. Coated conductive particles were obtained. Next, 15 parts by weight of inorganic particles were mixed, and then charged into a hybridizer and treated for 30 minutes to obtain conductive particles in which the inorganic particles were uniformly coated on the resin layer.

(Example 11)
A nickel conductive layer (metal layer) having no protrusions on the surface of the resin particles is obtained by using base particles to which no core substance is attached without adding a metal nickel particle slurry when forming the metal layer of Example 1. The conductive particles were obtained in the same manner as in Example 1 except that the base particles with the) were disposed.

(Comparative Example 1)
Conductive particles were obtained in the same manner as in Example 1 except that the inorganic particles were not coated.

(Comparative Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the resin particles were not coated.

(Comparative Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that neither resin particles nor inorganic particles were coated.

(Evaluation)
(1) Coverage The coverage here refers to the ratio of the total area covered by the insulating layer to the entire surface area of the conductive particles. Specifically, by observing with SEM as described above, 20 insulating layer-coated conductive particles are observed, and the total projected area of the portion covered with the insulating layer occupying the entire surface area of each conductive particle The ratio was calculated as the coverage. And the average value of 20 coverage was made into the coverage of the insulating layer covering electroconductive particle.

(2) Compressive modulus (10% K value) when conductive particles are compressed 10%
The compression modulus (10% K value) of the obtained conductive particles was measured by the above-described method using a micro compression tester (“Fischer Scope H-100” manufactured by Fischer).

(3) Recovery rate of conductive particles The recovery rate of the obtained conductive particles was measured by the above-described method using a micro compression tester (Fischer Scope H-100 manufactured by Fischer).

(4) Monodispersed phenoxy resin (“PKHC” manufactured by Union Carbide) 50 parts by weight, PGMEA 30 parts by weight and toluene 20 parts by weight were stirred and mixed for 24 hours to completely dissolve the phenoxy resin. To 10 parts by weight of the obtained dissolved resin, 0.05 part by weight of conductive particles was added and stirred with a planetary stirrer to obtain a resin composition. The obtained resin composition was applied onto polyethylene terephthalate that had been subjected to a release treatment, and the solvent was dried to obtain an anisotropic conductive film having a thickness of 10 μm. The obtained film was observed with an optical microscope, and when the equivalent of 1 million conductive particles was observed, the number of particles that were not monodispersed, that is, aggregated was counted.
[Criteria for monodispersity]
OO: Aggregated particles are less than 3.
◯: There are 3 or more and less than 10 aggregated particles.
A: There are 10 or more and less than 20 aggregated particles.
Δ: There are 20 or more and less than 30 aggregated particles.
X: There are 30 or more aggregated particles.

(5) Conductivity (between upper and lower electrodes)
The obtained conductive particles with insulating particles are added to “Strectbond XN-5A” manufactured by Mitsui Chemicals so that the content becomes 10% by weight, and dispersed using a planetary stirrer. A paste was obtained.

A transparent glass substrate having an IZO electrode pattern formed on the upper surface of an Al—Nd alloy wiring having L / S of 15 μm / 15 μm was prepared. Further, a semiconductor chip was prepared in which a gold electrode pattern having L / S of 15 μm / 15 μm was formed on the lower surface.

The obtained anisotropic conductive paste was applied on the transparent glass substrate so as to have a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer so that the electrodes face each other. After that, while adjusting the head temperature so that the temperature of the anisotropic conductive paste layer is 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 70 MPa is applied per bump area. The paste layer was cured at 185 ° C. to obtain a connection structure.

The connection resistances between the upper and lower electrodes of the 20 connection structures obtained were each measured by the 4-terminal method. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The conductivity was determined according to the following criteria.
[Conductivity criteria]
OO: The ratio of the number of connection structures having a resistance value of 3Ω or less is 90% or more.
◯: The ratio of the number of connection structures having a resistance value of 3Ω or less is 80% or more and less than 90%.
A: The ratio of the number of connection structures having a resistance value of 3Ω or less is 70% or more and less than 80%.
Δ: The ratio of the number of connection structures having a resistance value of 3Ω or less is 60% or more and less than 70%.
X: The ratio of the number of connection structures having a resistance value of 3Ω or less is less than 60%.

(6) Insulation (between adjacent electrodes in the horizontal direction)
In the 20 connection structures obtained in the above (5) conductivity evaluation, the presence or absence of leakage between adjacent electrodes was evaluated by measuring resistance with a tester. Insulation was judged according to the following criteria.
[Insulation criteria]
OO: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 90% or more.
◯: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 80% or more and less than 90%.
A: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 70% or more and less than 80%.
Δ: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 60% or more and less than 70%.
X: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is less than 60%.

Table 1 shows the coverage of insulating resin particles (or resin layers) and inorganic particles, and the 10% K value (N / mm) of the conductive particles for the conductive particles produced in each Example and Comparative Example. ² ), evaluation results of recovery rate (%), monodispersity, connection resistance value (conductivity) and insulation are shown.

As can be seen from Table 1, the conductive particles obtained in each example have a performance of any of 10% K value (N / mm ² ), recovery rate (%), monodispersity, connection resistance value, and insulation. Has also been shown to be superior. On the other hand, in the sample obtained in the comparative example, since the substrate particles are not coated with the resin and the inorganic material, aggregation is likely to occur, and the monodispersity is poor. The result was inferior to the case where the conductive particles were used.

Claims (8)

1. Conductive particles comprising base particles and a metal layer covering the surface of the base particles,
   Conductive particles in which the surface of the metal layer is coated with a resin and an inorganic material.
2. The conductive particle according to claim 1, wherein the resin includes resin particles.
3. The conductive particles according to claim 1 or 2, wherein the inorganic material includes inorganic particles.
4. 2. The conductive particle according to claim 1, wherein the resin includes resin particles, the inorganic material includes inorganic particles, and a ratio of an average particle diameter of the inorganic particles to the resin particles is 1/50 or more and 1 or less. .
5. The conductive particles according to claim 3 or 4, wherein a coverage of the inorganic particles is 80% or more.
6. A resin layer coated with the resin is formed on the surface of the metal layer, and an inorganic layer coated with the inorganic material is formed on the surface of the resin layer. Electroconductive particle of any one of these.
7. A conductive material comprising the conductive particles according to any one of claims 1 to 6 and a binder resin.
8. A first connection object member having a first electrode on its surface;
   A second connection target member having a second electrode on its surface;
   A connection portion connecting the first connection target member and the second connection target member;
   The material of the connecting portion includes the conductive particles according to any one of claims 1 to 6 or the conductive material according to claim 7.
   A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles or the conductive material.

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