JP6927933B2 - Conductive particles, conductive materials and connecting structures - Google Patents

Description

The present invention relates to conductive particles having base particles and a conductive layer arranged on the surface of the base particles. The present invention also relates to a conductive material and a connecting structure using the above conductive particles.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material, conductive particles are dispersed in the binder resin.

In order to obtain various connection structures, the anisotropic conductive material may be used, for example, for connecting a flexible printed circuit board and a glass substrate (FOG (Film on Glass)) or connecting a semiconductor chip and a flexible printed circuit board (COF (COF). It is used for Chip on Film)), connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

As an example of the conductive particles used in the anisotropic conductive material, Patent Document 1 below describes a conductive layer formed of copper, a copper alloy, silver or a silver alloy, and a conductive layer formed on the conductive layer. , And conductive particles having a surface layer formed of nickel or a nickel alloy are disclosed. Further, in the examples of Patent Document 1, the resin particles, the conductive layer covering the surface of the resin particles and formed of copper, and the conductive layer formed on the conductive layer and formed of nickel. Described are conductive particles having a surface layer and a surface layer formed of nickel having protrusions on the outer surface.

Japanese Unexamined Patent Publication No. 2013-206823

When the electrodes are connected to each other using conventional conductive particles as described in Patent Document 1 to obtain a connecting structure, when the connecting structure is exposed to the presence of an acid, the electrodes are connected to each other. Connection resistance may increase.

Further, when the surface layer of the conductive particles is nickel, an oxide film is likely to be formed on the surface layer. Further, an oxide film may be formed on the surface of the electrode. In the conventional conductive particles as described in Patent Document 1, if an oxide film is formed on the surface layer or an oxide film is formed on the surface of the electrodes, the oxide film sufficiently thrusts at the time of connection between the electrodes. It may not be broken and the initial connection resistance may increase.

An object of the present invention is that when a connecting structure is obtained by electrically connecting electrodes with conductive particles, the initial connection resistance can be lowered, and the connecting structure is exposed to the presence of an acid. It is to provide conductive particles that can keep the connection resistance low even if it is done.

The present invention also provides a conductive material and a connecting structure using the above conductive particles.

According to a broad aspect of the present invention, the substrate particles, the first conductive layer arranged on the surface of the substrate particles and formed of silver or copper, and the outside of the first conductive layer. are arranged on the surface, and a second conductive layer formed of nickel, said second conductive layer comprises nickel and boron and Tan Holdings Ten or molybdenum, conductive particles are provided NS.

In a specific aspect of the conductive particles according to the present invention, the nickel content in the second conductive layer is 50% by weight or more and 99% by weight or less.

In a specific aspect of the conductive particles according to the present invention, the content of tungsten or molybdenum in the second conductive layer is 0.1% by weight or more and 5.0% by weight or less.

In a specific aspect of the conductive particles according to the present invention, the content of boron in the second conductive layer is 0.1% by weight or more and 5.0% by weight or less.

In certain aspects of the conductive particles according to the present invention, the second conductive layer has a plurality of protrusions on the outer surface.

In a specific aspect of the conductive particles according to the present invention, the thickness of the second conductive layer is 0.1 times or more and 10 times or less the thickness of the first conductive layer.

In a particular aspect of the conductive particles according to the present invention, the first conductive layer is a copper layer formed of copper.

In certain aspects of the conductive particles according to the present invention, the substrate particles are resin particles or organic-inorganic hybrid particles.

In certain aspects of the conductive particles according to the present invention, the substrate particles are the organic-inorganic hybrid particles.

In a specific aspect of the conductive particles according to the present invention, the outer surface of the second conductive layer is rust-proofed.

In certain aspects of the conductive particles according to the present invention, the conductive particles further comprise an insulating material disposed on the outer surface of the second conductive layer.

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

According to a broad aspect of the present invention, a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, and the above. It is provided with a connecting portion connecting the second connection target member, and the connecting portion is formed of the above-mentioned conductive particles or a conductive material containing the conductive particles and a binder resin. Provided is a connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

The conductive particles according to the present invention are the base particles, the first conductive layer arranged on the surface of the base particles and formed of silver or copper, and the outside of the first conductive layer. are arranged on the surface, and so and a second conductive layer formed by nickel and boron and Tan Holdings Ten or molybdenum, between the electrodes by the conductive particles according to the present invention electrically connected When the connection structure is obtained, the initial connection resistance can be lowered, and even if the connection structure is exposed in the presence of an acid, the connection resistance can be kept low.

FIG. 1 is a cross-sectional view showing conductive particles according to the 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 schematically showing a connection structure using conductive particles according to the first embodiment of the present invention.

The details of the present invention will be described below.

(Conductive particles)
The conductive particles according to the present invention are the base particles, the first conductive layer arranged on the surface of the base particles and formed of silver or copper, and the outside of the first conductive layer. It includes a second conductive layer that is disposed on the surface and is made of nickel. The conductive particle according to the present invention, the second conductive layer comprises nickel and boron and Tan Holdings Ten or molybdenum. The first conductive layer is a silver layer formed of silver or a copper layer formed of copper. The second conductive layer is a nickel layer formed of nickel (also referred to as a nickel layer when boron and tungsten or molybdenum are contained), and specifically, a nickel-boron-tungsten / molybdenum layer.

By adopting the above-described configuration of the conductive particles according to the present invention, the initial connection resistance is lowered when the electrodes are electrically connected to each other using the conductive particles according to the present invention to obtain a connection structure. be able to. In addition, the connection resistance can be kept low even when the resulting connection structure is exposed in the presence of acid. In particular, when conductive particles are used for electrical connection between electrodes, the conductive particles are generally compressed. The compression of the conductive particles may cause cracks in the second conductive layer. Even if the second conductive layer is cracked, the connection resistance can be effectively kept low as a result of suppressing corrosion in the second conductive layer.

Further, when the surface layer of the conductive particles is a nickel layer, an oxide film is likely to be formed on the nickel layer. In addition, an oxide film may be formed on the surface of the electrode. In the present invention, the nickel layer is hard because the nickel layer contains nickel, boron, tungsten or molybdenum. Therefore, the initial connection resistance can be lowered because the oxide film can be satisfactorily penetrated at the time of connection between the electrodes.

Further, in the conductive particles according to the present invention, a silver layer or a copper layer is arranged inside the nickel layer, and the silver layer and the copper layer are relatively soft. In conductive particles in which a nickel layer is arranged on the outer surface of a silver layer or a copper layer, there is generally a problem that it is difficult for the protrusions to sufficiently penetrate the oxide film. In contrast, by forming a nickel layer formed by nickel and boron and Tan Holdings Ten or molybdenum, as a silver layer or a copper layer on the inner side of the nickel layer it has been disposed, upon connection between the electrodes The oxide film can be sufficiently penetrated, and the initial connection resistance can be effectively lowered. When a nickel layer is formed on the outer surface of a silver layer or a copper layer, the inclusion of boron and tungsten or molybdenum in the nickel layer plays a major role in obtaining the effects of the present invention. Further, when the conductive layer inside the nickel layer is a silver layer or a copper layer, the effect of reducing the connection resistance is improved as compared with the case where the conductive layer inside the nickel layer is a conductive layer other than the silver layer or the copper layer. It will be quite large.

Also, the copper layer is relatively harder than the silver layer. Therefore, when the copper layer is provided inside the nickel layer rather than the silver layer, the protrusions penetrate the oxide film more effectively and the initial connection resistance becomes lower.

Further, in the conductive particles according to the present invention, when the resin particles or the organic-inorganic hybrid particles are arranged inside the first conductive layer, the resin particles and the organic-inorganic hybrid particles are relatively soft. Conductive particles in which the base particles are resin particles or organic-inorganic hybrid particles generally have a problem that it is difficult for the protrusions to sufficiently penetrate the oxide film. On the other hand, by forming a nickel layer formed of nickel, boron, tongue ten or molybdenum, even if the base particles are resin particles or organic-inorganic hybrid particles, an oxide film is formed at the time of connection between the electrodes. It can be sufficiently penetrated and the initial connection resistance can be effectively lowered. When the base particles are resin particles or organic-inorganic hybrid particles, the inclusion of nickel, boron, tungsten or molybdenum in the nickel layer plays a major role in obtaining the effects of the present invention. Further, when the base material particles are resin particles or organic-inorganic hybrid particles, the effect of reducing the connection resistance is considerably larger than when the base material particles are not resin particles or organic-inorganic hybrid particles.

From the viewpoint of further lowering the initial connection resistance by penetrating the oxide film through the protrusions, in the conductive particles according to the present invention, the second conductive layer may have a plurality of protrusions on the outer surface. preferable. From the viewpoint of further lowering the initial connection resistance by penetrating the oxide film with the protrusions, in the conductive particles according to the present invention, the average height of the protrusions is the protrusion of the second conductive layer. It is preferable that the thickness is larger than the thickness of the portion without.

It is preferable that the average height B of the protrusions is larger than the thickness A of the portion of the second conductive layer without the protrusions. However, the average height B of the protrusions may be equal to or less than the thickness A of the portion of the second conductive layer without the protrusions. The average height B of the protrusions is the average height of a plurality of protrusions per conductive particle. The thickness A of the portion of the second conductive layer without the protrusion is the average thickness of the portion of the second conductive layer without the protrusion per one conductive particle.

From the viewpoint of further lowering the initial connection resistance and further suppressing the increase in the connection resistance in the presence of acid, the average height B of the protrusions is the portion of the second conductive layer without the protrusions. It is more preferably 1.1 times or more the thickness A, and further preferably 2.2 times or more. From the viewpoint of suppressing the protrusions from being excessively broken, further reducing the variation in connection resistance, and further improving the connection reliability, the average height B of the protrusions is the absence of the protrusions of the second conductive layer. The thickness A of the portion is preferably 6 times or less, and more preferably 3 times or less.

The height of the protrusion is a virtual line (broken line shown in FIG. 1) of the conductive portion on the line connecting the center of the conductive particle and the tip of the protrusion (broken line L1 shown in FIG. 1) assuming that there is no protrusion. L2) The distance from the top (on the outer surface of the spherical conductive particle assuming that there is no protrusion) to the tip of the protrusion is shown. That is, in FIG. 1, the distance from the intersection of the broken line L1 and the broken line L2 to the tip of the protrusion is shown.

From the viewpoint of further lowering the initial connection resistance and further suppressing the increase in the connection resistance in the presence of acid, the thickness of the second conductive layer is 0.1 of the thickness of the first conductive layer. It is preferably twice or more, more preferably 0.5 times or more, preferably 15 times or less, and more preferably 10 times or less.

The thickness of the first conductive layer is the average of the thickness of the entire first conductive layer per one conductive particle. The thickness of the second conductive layer is the average of the thickness of the entire second conductive layer per one conductive particle.

Hereinafter, the present invention will be clarified by explaining specific embodiments and examples of the present invention with reference to the drawings.

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

The conductive particles 1 shown in FIG. 1 include base particles 11, a first conductive layer 12, a second conductive layer 13, a plurality of core substances 14, and a plurality of insulating substances 15. The first conductive layer 12 is made of silver or copper. The second conductive layer 13 is made of nickel and contains nickel, boron, tungsten or molybdenum. In the conductive particles 1, a multi-layered conductive layer is formed. The base particle 11 is, for example, a resin particle.

The first conductive layer 12 is arranged on the surface of the base particle 11. The first conductive layer 12 is in contact with the base particles 11. The first conductive layer 12 is arranged between the base particle 11 and the second conductive layer 13. The second conductive layer 13 is arranged on the outer surface of the first conductive layer 12. The second conductive layer 13 is in contact with the first conductive layer 12. The conductive particles 1 are coated particles in which the surface of the base particle 11 is coated with the first conductive layer 12 and the second conductive layer 13.

The conductive particles 1 have a plurality of protrusions 1a on the conductive surface. The first conductive layer 12 and the second conductive layer 13 have a plurality of protrusions 12a and 13a on the outer surface. A plurality of core substances 14 are arranged on the surface of the base particle 11. The plurality of core substances 14 are embedded in the first conductive layer 12 and the second conductive layer 13. The core material 14 is arranged inside the protrusions 1a, 12a, 13a. The first conductive layer 12 and the second conductive layer 13 are coated with a plurality of core substances 14. The outer surfaces of the first conductive layer 12 and the second conductive layer 13 are raised by the plurality of core substances 14, and protrusions 1a, 12a, and 13a are formed. As described above, the conductive particles according to the present invention have protrusions on the conductive surface. Further, the conductive particles according to the present invention have protrusions on the outer surface of the second conductive layer. The core material is preferably arranged inside or inside the second conductive layer. The core material may be arranged inside or inside the first conductive layer. When the core material is arranged inside or inside the first conductive layer, the core material is arranged inside the second conductive layer.

The conductive particles 1 have an insulating material 15 arranged on a conductive surface. The conductive particles 1 have an insulating substance 15 arranged on the outer surface of the second conductive layer 13. At least a part of the outer surface of the second conductive layer 13 is covered with the insulating material 15. The insulating substance 15 is formed of an insulating material and is an insulating particle. As described above, the conductive particles according to the present invention preferably have an insulating substance arranged on the outer surface of the second conductive layer.

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

The conductive particles 1A shown in FIG. 2 include base particles 11, a first conductive layer 12A, a second conductive layer 13, and a plurality of insulating substances 15. The first conductive layer 12A is made of silver or copper.

The conductive particles 1A do not have a core substance. The first conductive layer 12A has a first portion and a second portion that is thicker than the first portion. Therefore, the first conductive layer 12A has protrusions 12Aa on the outer surface. The portion excluding the plurality of protrusions 1Aa and 12Aa is the first portion of the first conductive layer 12A. The plurality of protrusions 1Aa and 12Aa are the second portion where the thickness of the first conductive layer 12 is thick.

Like the conductive particles 1A, the conductive particles according to the present invention do not necessarily have to use a core material in order to form a plurality of protrusions on the outer surface of the second conductive layer.

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

The conductive particles 1B shown in FIG. 3 include base particles 11, a first conductive layer 12B, a second conductive layer 13B, and a plurality of core substances 14. The first conductive layer 12B is made of silver or copper. The second conductive layer 13B is made of nickel and contains nickel, boron, tungsten or molybdenum.

The conductive particles 1B have a plurality of protrusions 1Ba on the conductive surface. The first conductive layer 12B has no protrusions on the outer surface. The outer shape of the first conductive layer 12B is spherical. The second conductive layer 13B has a plurality of protrusions 13Ba on the outer surface. A plurality of core substances 14 are arranged on the outer surface of the first conductive layer 12B. The plurality of core substances 14 are embedded in the second conductive layer 13B. The core material 14 is arranged inside the protrusions 1Ba and 13Ba. The second conductive layer 13B is coated with a plurality of core substances 14. The outer surface of the second conductive layer 13B is raised by the plurality of core substances 14, and the protrusions 1Ba and 13Ba are formed.

Like the conductive particles 1B, the conductive particles according to the present invention do not have to have protrusions on the outer surface of the first conductive layer.

The conductive particles 1B do not have an insulating substance on the outer surface of the second conductive layer 13B. The conductive particles according to the present invention do not necessarily have an insulating substance arranged on the outer surface of the second conductive layer.

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

The conductive particles 1C shown in FIG. 4 include base particles 21, a first conductive layer 12, a second conductive layer 13, a plurality of core substances 14, and a plurality of insulating substances 15. The conductive particles 1C have a plurality of protrusions 1Ca on the conductive surface.

The conductive particles 1 shown in FIG. 1 use the base particles 11, whereas the conductive particles 1C shown in FIG. 4 use the base particles 21. The base particle 21 has a core 21X and a shell 21Y arranged on the surface of the core 21X. The base particle 21 is a core-shell particle. The base particle 21 is, for example, an organic-inorganic hybrid particle.

As described above, in the conductive particles according to the present invention, the base particles can be appropriately changed.

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

The conductive particles 1D shown in FIG. 5 include base particles 11, a first conductive layer 12D, a second conductive layer 13D, and a plurality of insulating substances 15. The first conductive layer 12D is made of silver or copper. The second conductive layer 13D is made of nickel and contains nickel, boron, tungsten or molybdenum.

The conductive particles 1D have an insulating material 15 disposed on a conductive surface. The conductive particles 1D have an insulating substance 15 arranged on the outer surface of the second conductive layer 13D.

The conductive particles 1D have no core material. The conductive particles 1D are spherical. The conductive particles 1D have no protrusions on the outer surface. The outer shapes of the first conductive layer 12D and the second conductive layer 13D are spherical. The first conductive layer 12D and the second conductive layer 13D have no protrusions on the outer surface.

Protrusions do not necessarily have to be formed in the conductive particles according to the present invention, such as the conductive particles 1D. The conductive particles according to the present invention may be spherical.

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

[Base particles]
Examples of the base material particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The base material particles may have a core and a shell arranged on the surface of the core, or may be core-shell particles. The base material particles are preferably base particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles.

The base material particles are more preferably resin particles or organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles. The use of these preferred substrate particles provides conductive particles that are even more suitable for electrical connection between the electrodes.

When connecting the electrodes using the conductive particles, the conductive particles are placed between the electrodes and then crimped to compress the conductive particles. When the base particle is a resin particle or an organic-inorganic hybrid particle, the conductive particle is easily deformed at the time of crimping, and the contact area between the conductive particle and the electrode becomes large. Therefore, the connection resistance between the electrodes becomes even lower.

Various organic substances are preferably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, vinylidene chloride, polyisobutylene and polybutadiene; acrylic resins such as polymethylmethacrylate and polymethylacrylate; poly. Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Polymers obtained by polymerizing one or more of various polymerizable monomers having an oxide, a polyacetal, a polyimide, a polyamideimide, a polyether ether ketone, a polyether sulfone, and an ethylenically unsaturated group can be used. Can be mentioned. Since resin particles having arbitrary physical characteristics at the time of compression suitable for a conductive material can be designed and synthesized, and the hardness of the base material particles can be easily controlled within a suitable range, a resin for forming 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 includes a non-crosslinkable monomer and a crosslinkable monomer. And can be mentioned.

Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; and methyl ( Meta) 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) Alkyl (meth) acrylates such as meta) acrylates and isobornyl (meth) acrylates; oxygen atoms such as 2-hydroxyethyl (meth) acrylates, glycerol (meth) acrylates, polyoxyethylene (meth) acrylates and glycidyl (meth) acrylates. Contains (meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate, etc. Classes: 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. Can be mentioned.

Examples of the crosslinkable monomer include tetramethylol methanetetra (meth) acrylate, tetramethylol methanetri (meth) acrylate, tetramethylol methanedi (meth) acrylate, trimethyl propanetri (meth) acrylate, and dipenta. Elythritol hexa (meth) acrylate, dipenta erythritol 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 acrylates, (poly) tetramethylene glycol di (meth) acrylates, 1,4-butanediol di (meth) acrylates; triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, Examples thereof include silane-containing monomers such as diallyl phthalate, diallyl acrylamide, diallyl ether, γ- (meth) acryloxipropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

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 a method of suspension polymerization in the presence of a radical polymerization initiator, a method of swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles, and the like.

When the base material particles are inorganic particles other than metal particles or organic-inorganic hybrid particles, examples of the inorganic material for forming the base material particles include silica, alumina, barium titanate, zirconia, and carbon black. .. It is preferable that the inorganic substance is not a metal. The particles formed of the silica are not particularly limited, but for example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, firing is performed if necessary. Examples include particles obtained by doing so. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed of a crosslinked alkoxysilyl polymer and an acrylic resin.

The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell arranged on the surface of the core. It is preferable that the core is an organic core. It is preferable that the shell is an inorganic shell. From the viewpoint of effectively reducing the connection resistance between the electrodes, the base particle is preferably an organic-inorganic hybrid particle having an organic core and an inorganic shell arranged on the surface of the organic core.

Examples of the material for forming the organic core include the resin for forming the resin particles described above.

Examples of the material for forming the inorganic shell include the above-mentioned inorganic substances for forming the base particles. The material for forming the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell-like material by a sol-gel method on the surface of the core and then firing the shell-like material. The metal alkoxide is preferably a silane alkoxide. The inorganic shell is preferably formed of silane alkoxide.

The particle size of the core is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less. .. When the particle size of the core is at least the above lower limit and at least the above upper limit, more suitable conductive particles can be obtained by electrical connection between the electrodes, and the base particles can be suitably used for the use of the conductive particles. Become. For example, when the particle size of the core is at least the above lower limit and at least the above upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large when the electrodes are connected using the conductive particles, and the contact area between the conductive particles and the electrodes becomes sufficiently large. Aggregated conductive particles are less likely to be formed when the conductive layer is formed. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer does not easily peel off from the surface of the base particles.

The particle size of the core means the diameter when the core is spherical, and means the maximum diameter when the core has a shape other than the spherical shape. Further, the particle size of the core means the average particle size of the core measured by an arbitrary particle size measuring device. For example, a particle size distribution measuring machine using principles such as laser light scattering, change in electrical resistance, and image analysis after imaging can be used.

The thickness of the shell is preferably 100 nm or more, more preferably 200 nm or more, preferably 5 μm or less, and more preferably 3 μm or less. When the thickness of the shell is not less than the above lower limit and not more than the above upper limit, more suitable conductive particles can be obtained by electrical connection between the electrodes, and the base material particles can be suitably used for the use of the conductive particles. .. The thickness of the shell is the average thickness per base particle. The thickness of the shell can be controlled by controlling the sol-gel method.

When the base material particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, it is preferable that the base material particles are not metal particles.

The particle size of the base particles is particularly preferably 0.1 μm or more and 5 μm or less. When the particle size of the base material particles is within the range of 0.1 to 5 μm, small conductive particles can be obtained even if the distance between the electrodes is small and the thickness of the conductive layer is increased. From the viewpoint of obtaining smaller conductive particles even if the distance between the electrodes is further reduced or the thickness of the conductive layer is increased, the particle size of the base material particles is preferably 0.5 μm or more. , More preferably 2 μm or more, preferably 3 μm or less.

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

The compressive elastic modulus (10% K value) when the base particles are compressed by 10% is preferably 2500 mN / mm ² or more, more preferably 5000 mN / mm ² or more, preferably 10000 mN / mm ² or less, more preferably 7000 mN. / Mm ² or less. When the 10% K value is equal to or higher than the lower limit and lower than the upper limit, the connection resistance between the electrodes becomes even lower.

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

Using a microcompression tester, the substrate particles are compressed on the smoothing indenter end face of a cylinder (diameter 100 μm, made of diamond) under the conditions of 25 ° C., a compression rate of 0.3 mN / sec, and a maximum test load of 20 mN. At this time, the load value (N) and the compressive displacement (mm) are measured. From the obtained measured values, the compressive elastic modulus can be calculated by the following formula. As the microcompression tester, for example, "Fisherscope H-100" manufactured by Fisher Co., Ltd. is used.

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

The compressive elastic modulus universally and quantitatively represents the hardness of the substrate particles. By using the compressive elastic modulus, the hardness of the base particle can be expressed quantitatively and uniquely.

[Conductive layer]
The first conductive layer is made of silver or copper. The first conductive layer includes not only a case where only silver or copper is used as a metal, but also a case where silver and another metal are used, and a case where copper and another metal are used. The first conductive layer may be a silver alloy layer or a copper alloy layer.

The first conductive layer may be a silver layer formed of silver or a copper layer formed of copper. Since the effect of the present invention can be obtained even more effectively, the first conductive layer is preferably a copper layer formed of copper.

Examples of the metal other than silver in the silver layer and the metal other than copper in the copper layer include gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, palladium, chromium, and the like. Examples thereof include titanium, antimony, bismuth, tarium, germanium, cadmium, silicon, tungsten, molybdenum, tin-doped indium oxide (ITO) and solder. Only one of these metals may be used, or two or more of these metals may be used in combination.

The first conductive layer preferably contains silver or copper as a main metal. The content of silver or copper (silver content or copper content) is preferably 50% by weight or more in 100% by weight of the first conductive layer. The content of silver or copper in 100% by weight of the first conductive layer is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 99% by weight or more. When the content of silver or copper is at least the above lower limit, the electrodes and the conductive particles come into contact with each other more appropriately, and the connection resistance between the electrodes becomes even lower.

Another conductive layer may be arranged between the first conductive layer and the second conductive layer. It is preferable that the second conductive layer is laminated on the outer surface of the first conductive layer so that the second conductive layer is in contact with the outer surface.

The second conductive layer is made of nickel. The second conductive layer includes not only the case where only nickel is used as the metal but also the case where nickel and another metal are used. The second conductive layer may be a nickel alloy layer.

Examples of the metal other than nickel, tungsten and molybdenum in the second conductive layer include gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, palladium, chromium, titanium, antimony and bismuth. Examples thereof include tarium, germanium, cadmium, silicon, tin-doped indium oxide (ITO) and solder. Only one of these metals may be used, or two or more of these metals may be used in combination.

The second conductive layer preferably contains nickel as a main metal. The nickel content is preferably 50% by weight or more in 100% by weight of the second conductive layer. In 100% by weight of the second conductive layer, the nickel content is preferably 75% by weight or more, more preferably 85% by weight or more, still more preferably 95% by weight or more, and preferably 99% by weight or less. When the nickel content is at least the above lower limit, the oxide film on the surface of the electrodes is removed more effectively, and the connection resistance between the electrodes is further lowered.

The second conductive layer contains boron. In 100% by weight of the second conductive layer, the content of boron is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 10% by weight or less, and more preferably 5.0% by weight or less. be. When the boron content is not more than the lower limit and the upper limit, the resistance of the second conductive layer is further lowered, and the second conductive layer further contributes to the reduction of the connection resistance. The second conductive layer may contain phosphorus.

The second conductive layer contains tungsten or molybdenum. The second conductive layer may contain tungsten or molybdenum. When the second conductive layer contains nickel, boron, tungsten or molybdenum, the second conductive layer and protrusions can be made even harder, and the initial connection resistance can be effectively lowered.

The content of tungsten or molybdenum (tungsten content or molybdenum content) in 100% by weight of the second conductive layer is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, preferably 0.2% by weight or more. It is 5.0% by weight or less, more preferably 2.5% by weight or less. When the content of tungsten or molybdenum is not more than the lower limit and the upper limit, the second conductive layer is effectively hardened, and the second conductive layer further contributes to the reduction of the connection resistance.

Another conductive layer may be arranged on the outer surface of the second conductive layer. It is preferable that the second conductive layer is arranged on the outermost surface of the conductive layer in the conductive particles. The conductive surface layer of the conductive particles is preferably the second conductive layer.

The nickel content is preferably 40% by weight or more, more preferably 60% by weight, in 100% by weight of the entire conductive layer of the conductive particles and in 100% by weight of the first conductive layer and the second conductive layer. % Or more, preferably 92% by weight or less, more preferably 80% by weight or less. When the nickel content is at least the above lower limit, the oxide film on the surface of the conductive particles and the surface of the electrodes is removed more effectively, and the connection resistance between the electrodes is further lowered.

Silver or copper content (silver content or copper content) in 100% by weight of the entire conductive layer in the conductive particles and in 100% by weight of the total of the first conductive layer and the second conductive layer. Is preferably 5% by weight or more, more preferably 10% by weight or more, preferably 60% by weight or less, and more preferably 25% by weight or less. When the content of silver or copper is at least the above lower limit, the electrodes and the conductive particles come into contact with each other more appropriately, and the connection resistance between the electrodes becomes even lower.

The method for forming the conductive layer is not particularly limited. Examples of the method for forming the conductive layer include a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating a metal powder or a paste containing a metal powder and a binder on the surface of particles. Can be mentioned. Of these, the electroless plating method is preferable because the conductive layer can be easily formed. Examples of the method by physical vapor deposition include methods such as vacuum deposition, ion plating, and ion sputtering.

The thickness of the first conductive layer is preferably 5 nm or more, more preferably 15 nm or more, preferably 100 nm or less, and more preferably 40 nm or less. When the thickness of the first conductive layer is not less than the above lower limit and not more than the above upper limit, the electrodes and the conductive particles come into contact with each other more appropriately, and the connection resistance between the electrodes becomes even lower.

The thickness of the second conductive layer is preferably 36 nm or more, more preferably 60 nm or more, preferably 295 nm or less, and more preferably 130 nm or less. When the thickness of the second conductive layer is not less than the above lower limit and not more than the above upper limit, the oxide film on the surface of the electrode is removed more effectively, and the connection resistance between the electrodes is further lowered.

The total thickness of the conductive layer and the total thickness of the first conductive layer and the second conductive layer are preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, and particularly preferably 41 nm or more. It is most preferably 50 nm or more, preferably 1000 nm or less, more preferably 800 nm or less, even more preferably 500 nm or less, still more preferably 400 nm or less, particularly preferably 395 nm or less, and most preferably 300 nm or less. When the thickness of the entire conductive layer and the total thickness of the first conductive layer and the second conductive layer are at least the above lower limit, the conductivity of the conductive particles becomes even better. When the thickness of the entire conductive layer and the total thickness of the first conductive layer and the second conductive layer are equal to or less than the above upper limit, the difference in the coefficient of thermal expansion between the base particles and the conductive layer becomes small. The conductive layer is less likely to peel off from the base particles.

The thickness of the conductive layer can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM).

The particle size of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, still more preferably 5 μm or less. When the particle diameter of the conductive particles is equal to or greater than the above lower limit and equal to or less than the above upper limit, the contact area between the conductive particles and the electrodes becomes sufficiently large and the conductive layer is formed when the electrodes are connected using the conductive particles. It becomes difficult for agglomerated conductive particles to be formed when the particles are formed. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer does not easily peel off from the surface of the base particles.

The particle size of the conductive particles indicates the diameter when the conductive particles are spherical, and indicates the maximum diameter when the conductive particles are not spherical.

The conductive particles according to the present invention preferably have a plurality of protrusions on the conductive surface. The second conductive layer preferably has a plurality of protrusions on the outer surface. The first conductive layer preferably has a plurality of protrusions on the outer surface. An oxide film is often formed on the surface of the electrode connected by the conductive particles. By using the conductive particles having the conductive protrusions, the oxide film is effectively removed by the protrusions by arranging the conductive particles between the electrodes and then crimping them. Therefore, the electrodes and the conductive particles can be brought into contact with each other more reliably, and the connection resistance between the electrodes can be lowered. Further, when the conductive particles have an insulating substance on the surface, or when the conductive particles are dispersed in the resin and used as a conductive material, the protrusions of the conductive particles provide insulation between the conductive particles and the electrode. Substances or resins can be effectively eliminated. Therefore, the continuity reliability between the electrodes can be improved.

Since the effect of the present invention is excellent, the number of protrusions (number of protrusions) on the outer surface of the second conductive layer per conductive particle is preferably 3 or more, more preferably 5 or more, and more preferably. It is 10 or more, more preferably 20 or more. The upper limit of the number of the protrusions is not particularly limited. Since the effect of the present invention is excellent, the number of protrusions on the outer surface of the conductive layer per conductive particle is preferably 1000 or less, more preferably 500 or less, still more preferably 300 or less.

The average height of the plurality of protrusions in the second conductive layer is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, and 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 lowered.

[Core material]
By embedding the core substance in the conductive layer, it is easy for the conductive layer to have a plurality of protrusions on the outer surface. However, in order to form protrusions on the outer surface of the conductive particles and the conductive layer, it is not always necessary to use the core material, and it is preferable not to use the core material. It is preferable that the conductive particles do not have a core substance for raising the outer surface of the conductive layer. It is preferable that the conductive layer does not contain a core substance for raising the outer surface of the conductive layer. When the core material is used, it is preferable that the core material is arranged inside or inside the conductive layer.

As a method of forming the above-mentioned protrusions, a method of forming a conductive layer by electroless plating after adhering a core material to the surface of the base material particles, and a method of forming a conductive layer by electroless plating on the surface of the base material particles. , A method of adhering a core material and further forming a conductive layer by electroless plating, a method of adding a core material in the middle of electroless plating, and a method of forming a conductive layer by electroless plating.

As a method of arranging the core substance, for example, the core substance is added to a dispersion liquid such as base particles, and the core substance is accumulated and adhered to the surface of the base particles by, for example, van der Waals force. Examples thereof include a method in which a core substance is added to a container containing base particles and the like, and the core substance is attached to the surface of the base particles and the like by a mechanical action such as rotation of the container. Among them, since it is easy to control the amount of the core substance to be adhered, a method of accumulating and adhering the core substance on the surface of the base material particles or the like in the dispersion liquid is preferable.

Examples of the substance constituting the core substance include 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 and the like. Examples of the non-conductive substance include silica, alumina, barium titanate and zirconia. Among them, metal is preferable because the conductivity can be increased and the connection resistance can be effectively lowered. The core material is preferably metal particles.

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 tin-lead. Examples thereof include alloys composed of two or more kinds of metals such as alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys and tungsten carbide.

The material of the core substance is preferably an inorganic substance that does not contain nickel. However, the material of the core material may be nickel. Specific examples of the material of the core material include titanium oxide (Mohs hardness 4), barium titanate (Mohs hardness 4.5), nickel (Mohs hardness 5), silica (Silicon dioxide, Mohs hardness 6-7), and zirconia. (Mohs hardness 8 to 9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10) and the like can be mentioned. The material of the core material is preferably titanium oxide, barium titanate, nickel, silica, zirconia, alumina, tungsten carbide or diamond, and more preferably nickel, silica, zirconia, alumina, tungsten carbide or diamond. , Zirconia, alumina, tungsten carbide or diamond is more preferred. From the viewpoint of further lowering the initial connection resistance, the Mohs hardness of the material of the core material is preferably larger than the Mohs hardness of silver, and more preferably larger than the Mohs hardness of copper. When the first conductive layer is a silver layer, the Mohs hardness of the material of the core material is preferably higher than the Mohs hardness of silver, and when the first conductive layer is a copper layer, the core It is more preferable that the Mohs hardness of the material of the substance is larger than the Mohs hardness of copper. From the viewpoint of further lowering the initial connection resistance, the Mohs hardness of the material of the core material is preferably 4 or more, more preferably 5.5 or more, still more preferably 6 or more, and particularly preferably 7.5 or more. .. From the viewpoint of further suppressing the increase in connection resistance in the presence of acid, the core substance is preferably formed of an inorganic substance containing no metal.

From the viewpoint of effectively reducing the connection resistance between the electrodes, the Mohs hardness of the material of the core material is preferably equal to or higher than the Mohs hardness (5) of nickel, and is larger than the Mohs hardness of nickel. preferable. The absolute value of the difference between the Mohs hardness of the core material and the Mohs hardness of nickel is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.5 or more, and particularly preferably 1 or more. , Most preferably 2 or more. The material of the core material is the main material (50% by weight or more) constituting the core material, and is the material most contained in the core material.

The shape of the core substance is not particularly limited. The shape of the core material is preferably lumpy. Examples of the core material include particulate lumps, agglomerated lumps in which a plurality of fine particles are aggregated, and amorphous lumps.

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

The "average diameter (average particle size)" of the core substance indicates a number average diameter (number average particle size). 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.

[Insulating material]
The conductive particles according to the present invention preferably include an insulating substance arranged on the outer surface of the conductive layer. In this case, if conductive particles are used for the connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, an insulating substance exists between the plurality of electrodes, so that it is possible to prevent a short circuit between the electrodes adjacent to each other in the lateral direction rather than between the upper and lower electrodes. By pressurizing the conductive particles with the two electrodes at the time of connection between the electrodes, the insulating substance between the conductive layer of the conductive particles and the electrodes can be easily removed. When the conductive particles have a plurality of protrusions on the outer surface of the conductive layer, the insulating substance between the conductive layer of the conductive particles and the electrodes can be easily removed.

The insulating material is preferably insulating particles because the insulating material can be more easily removed during crimping between the electrodes.

Specific examples of the insulating resin that is the material of the insulating material include polyolefins, (meth) acrylate polymers, (meth) acrylate copolymers, block polymers, thermoplastic resins, crosslinked products of thermoplastic resins, and thermosetting. Examples include sex resins and water-soluble resins.

Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer and the like. 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-acrylic acid ester copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin and the like. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide, methyl cellulose and the like. Of these, a water-soluble resin is preferable, and polyvinyl alcohol is more preferable.

Examples of the method of arranging the insulating substance on the surface of the conductive layer include a chemical method and a physical or mechanical method. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, an emulsion polymerization method, and the like. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion method, spraying method, dipping and vacuum deposition methods. Among them, since the insulating substance is difficult to be detached, the method of arranging the insulating substance on the surface of the conductive layer via a chemical bond is preferable.

The outer surface of the conductive layer and the surface of the insulating particles may each be coated with a compound having a reactive functional group. The outer surface of the conductive layer and the surface of the insulating particles may not be directly chemically bonded, or may be indirectly chemically bonded by a compound having a reactive functional group. After introducing a carboxyl group into the outer surface of the conductive layer, the carboxyl group may be chemically bonded to a functional group on the surface of the insulating particles via a polyelectrolyte such as polyethyleneimine.

The average diameter (average particle diameter) of the insulating substance can be appropriately selected depending on the particle diameter of the conductive particles, the use of the conductive particles, and the like. The average diameter (average particle size) of the insulating substance is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, and more preferably 0.5 μm or less. When the average diameter of the insulating substance is at least the above lower limit, it becomes difficult for the conductive layers of the plurality of conductive particles to come into contact with each other when the conductive particles are dispersed in the binder resin. When the average diameter of the insulating particles is not more than the above upper limit, it is not necessary to make the pressure too high in order to eliminate the insulating substance between the electrodes and the conductive particles when connecting the electrodes, and the temperature becomes high. There is no need to heat it.

The "average diameter (average particle size)" of the insulating substance indicates a number average diameter (number average particle size). The average diameter of the insulating substance is determined by using a particle size distribution measuring device or the like.

[Rust prevention treatment]
From the viewpoint of suppressing corrosion of the conductive particles and further lowering the connection resistance between the electrodes, it is preferable that the outer surface of the second conductive layer is rust-proofed.

From the viewpoint of further enhancing the conduction reliability, the outer surface of the second conductive layer is preferably rust-proofed with a compound having an alkyl group having 6 to 22 carbon atoms. From the viewpoint of further enhancing the conduction reliability, it is preferable that the outer surface of the second conductive layer is rust-proofed with an alkylphosphoric acid compound or an alkylthiol. By the rust preventive treatment, a rust preventive film can be formed on the surface of the second conductive layer.

The rust preventive film is preferably formed of a compound having an alkyl group having 6 to 22 carbon atoms (hereinafter, also referred to as compound A). The outer surface of the second conductive layer is preferably surface-treated with the compound A. When the number of carbon atoms of the alkyl group is 6 or more, rust is less likely to occur on the outer surface of the second conductive layer. When the number of carbon atoms of the alkyl group is 22 or less, the conductivity of the conductive particles becomes high. From the viewpoint of further increasing the conductivity of the conductive particles, the number of carbon atoms of the alkyl group in the compound A is preferably 16 or less. The alkyl group may have a linear structure or a branched structure. The alkyl group preferably has a linear structure.

The compound A is not particularly limited as long as it has an alkyl group having 6 to 22 carbon atoms. The compound A has a phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, a disulfide ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, and an alkyl group having 6 to 22 carbon atoms. It is preferably at least one selected from the group consisting of an alkoxysilane, an alkylthiol having an alkyl group having 6 to 22 carbon atoms, and a dialkyldisulfide having an alkyl group having 6 to 22 carbon atoms. That is, the compound A having an alkyl group having 6 to 22 carbon atoms is at least one selected from the group consisting of a phosphoric acid ester or a salt thereof, a phosphite ester or a salt thereof, an alkoxysilane, an alkylthiol and a dialkyldisulfide. Is preferable. By using these preferable compounds A, it is possible to make the second conductive layer more resistant to rust. From the viewpoint of making rust less likely to occur, the compound A is preferably a phosphoric acid ester or a salt thereof, a phosphite ester or a salt thereof, or an alkylthiol, and the phosphoric acid ester or a salt thereof. Alternatively, it is more preferably a phosphite ester or a salt thereof. As the compound A, only one kind may be used, or two or more kinds may be used in combination.

The compound A preferably has a reactive functional group capable of reacting with the outer surface of the second conductive layer. The compound A preferably has a reactive functional group capable of reacting with the insulating substance. The rust preventive film is preferably chemically bonded to the second conductive layer. The rust preventive film is preferably chemically bonded to the insulating substance. It is more preferable that the rust preventive film is chemically bonded to both the second conductive layer and the insulating substance. Due to the presence of the reactive functional groups and the chemical bonds, the rust-preventive film is less likely to peel off, and as a result, rust is less likely to occur on the second conductive layer, and from the surface of the conductive particles. The insulating material becomes more difficult to detach unintentionally.

Examples of the phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include phosphoric acid hexyl ester, phosphoric acid heptyl ester, phosphoric acid monooctyl ester, phosphoric acid monononyl ester, and phosphoric acid monodecyl ester. Organophosphate monoundecyl ester, phosphate monododecyl ester, phosphate monotridecyl ester, phosphate monotetradecyl ester, phosphate monopentadecyl ester, phosphate monohexyl ester monosodium salt, phosphate monoheptyl ester monosodium Salt, monooctyl phosphate monosodium salt, mononoyl phosphate monosodium salt, monodecyl phosphate monosodium salt, monoundecyl phosphate monosodium salt, monododecyl phosphate monosodium salt, phosphate Examples thereof include monotridecyl ester monosodium salt, phosphoric acid monotetradecyl ester monosodium salt and phosphate monopentadecyl ester monosodium salt. The potassium salt of the above-mentioned phosphoric acid ester may be used.

Examples of the phosphorous acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include phosphorous acid hexyl ester, phosphorous acid heptyl ester, phosphorous acid monooctyl ester, phosphorous acid monononyl ester, and sub-phosphate. Phosphorous acid monodecyl ester, phosphorous acid monoundecyl ester, phosphorous acid monododecyl ester, phosphorous acid monotridecyl ester, phosphorous acid monotetradecyl ester, phosphorous acid monopentadecyl ester, phosphorous acid monohexyl Phosphorous acid monosodium salt, phosphorous acid monoheptyl ester monosodium salt, phosphorous acid monooctyl ester monosodium salt, phosphorous acid monononyl ester monosodium salt, phosphorous acid monodecyl ester monosodium salt, phosphorous acid monoun Phosphorous acid monododecyl ester monosodium salt, phosphorous acid monotridecyl ester monosodium salt, phosphorous acid monotetradecyl ester monosodium salt, phosphorous acid monopentadecyl ester monosodium salt, etc. Can be mentioned. The potassium salt of the above phosphite ester may be used.

Examples of the alkoxysilane having an alkyl group having 6 to 22 carbon atoms include hexyltrimethoxysilane, hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, and nonyltri. Methoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane, undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane Examples thereof include silane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, and pentadecyltriethoxysilane.

Examples of the alkyl thiol having an alkyl group having 6 to 22 carbon atoms include hexyl thiol, heptyl thiol, octyl thiol, nonyl thiol, decyl thiol, undecyl thiol, dodecyl thiol, tridecyl thiol, tetradecyl thiol and pentadecyl. Examples thereof include thiols and hexadecylthiols. The alkyl thiol preferably has a thiol group at the end of the alkyl chain.

Examples of the dialkyl disulfide having an alkyl group having 6 to 22 carbon atoms include dihexyl disulfide, diheptyl disulfide, dioctyl disulfide, dinonyl disulfide, didecyl disulfide, diundecyl disulfide, didodecyl disulfide, ditridecyl disulfide, and ditetra. Examples thereof include decyl disulfide, dipenta decyl disulfide and dihexadecyl disulfide.

(Conductive material)
The conductive material according to the present invention includes the above-mentioned conductive particles and a binder resin. The conductive particles are preferably dispersed in the binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. It is preferable that the conductive particles and the conductive material are circuit connection materials, respectively.

The binder resin is not particularly limited. As the binder resin, a known insulating resin is used.

Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. Only one kind of the binder resin may be used, or two or more kinds may be used in combination.

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, and polyamide resins. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin, unsaturated polyester resin and the like. 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 additive of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogen additives for styrene block copolymers and the like can be mentioned. 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, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a photostabilizer. It may contain various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

The conductive material according to the present invention can be used as a conductive paste, a conductive film, or the like. When the conductive material according to the present invention is a conductive film, a film containing no conductive particles may be laminated on the conductive film containing the 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 99% by weight. It is 99% by weight or less, more preferably 99.9% by 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 improved.

The content of the conductive particles in 100% by weight of the conductive material is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 80% by weight or less, more preferably 60% by weight or less. It is even more preferably 40% by weight or less, further preferably 20% by weight or less, and particularly 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 increased.

(Connection structure)
A connection structure can be obtained by connecting the members to be connected using the conductive particles or a conductive material containing the conductive particles and a binder resin.

The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members, and the connection portion has the above-mentioned conductivity. It is preferably a connection structure formed of particles or a conductive material containing the above-mentioned conductive particles and a binder resin. When conductive particles are used, the connecting portion itself is the conductive particles. That is, the first and second connection target members are connected by the conductive particles.

FIG. 6 schematically shows a connection structure using conductive particles according to the first embodiment of the present invention in a cross-sectional view.

The connection structure 51 shown in FIG. 6 connects a first connection target member 52, a second connection target member 53, and a connection portion 54 connecting the first and second connection target members 52 and 53. Be prepared. The connecting portion 54 is formed by curing a conductive material containing the conductive particles 1. In FIG. 6, the conductive particles 1 are shown schematicly for convenience of illustration. Conductive particles 1A, 1B, 1C, 1D and the like may be used instead of the conductive particles 1.

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

The method for manufacturing the connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, the conductive material is arranged between a first connection target member and a second connection target member, and after obtaining a laminate, the laminate is heated and pressurized. The method and the like can be mentioned. The pressurizing pressure is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The heating temperature is about 120 to 220 ° C.

Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors and diodes, and electronic components such as printed circuit boards, flexible printed circuit boards, glass epoxy boards and circuit boards such as glass substrates. The connection target member is preferably an electronic component. The conductive particles are preferably used for electrical connection of electrodes in electronic components.

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 member to be connected is a flexible printed substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material of 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 specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

(Example 1)
The surface of divinylbenzene copolymer resin particles (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd.) having a particle size of 3.0 μm is coated with silica (inorganic shell, thickness 250 nm) using a condensation reaction by a sol-gel reaction. A coated core-shell type organic-inorganic hybrid particle (base particle A, 10% K value: 8500 mN / mm ² ) was prepared.

The organic-inorganic hybrid particles were etched and washed with water. Next, organic-inorganic hybrid particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst, and the mixture was stirred. Then it was filtered and washed. Organic-inorganic hybrid particles were added to a 0.5 wt% dimethylamine borane solution having a pH of 6, to obtain organic-inorganic hybrid particles to which palladium was attached.

The organic-inorganic hybrid particles to which palladium was attached were stirred in 300 mL of ion-exchanged water for 3 minutes and dispersed to obtain a dispersion liquid. Next, 1 g of a silica particle slurry (average particle size of silica as a core substance of 100 nm) was added to the dispersion liquid over 3 minutes to obtain organic-inorganic hybrid particles to which the core substance was attached.

A copper layer (thickness X40 nm) was formed on the surface of the organic-inorganic hybrid particles by electroless copper plating using the organic-inorganic hybrid particles to which the core substance was attached.

Next, an electroless nickel plating treatment is performed using an inorganic electrolytic nickel plating solution containing nickel sulfate, sodium tungstate, and a reducing agent, dimethylamine borane, to obtain a nickel layer (thickness) on the outer surface of the copper layer. Y80 nm) was formed. In this way, conductive particles were obtained. The thickness A of the nickel layer in the portion of the obtained conductive particles having no protrusions was 80 nm, and the average height B of the protrusions was 100 nm. The number of protrusions was 75.

(Example 2)
Divinylbenzene copolymer resin particles having a particle size of 3.5 μm (base particle B, “Micropearl SP-203” manufactured by Sekisui Chemical Industry Co., Ltd., 10% K value: 7000 mN / mm ² ) were prepared. The number of protrusions was 75.

Conductive particles were obtained in the same manner as in Example 1 except that the base particles were changed to the resin particles.

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that the copper plating solution used for the electroless copper plating treatment was changed to a copper plating solution containing sodium titanate when forming the copper layer.

(Example 4)
Conductive particles were obtained in the same manner as in Example 1 except that an electroless nickel plating solution containing nickel sulfate, sodium molybdate, and a reducing agent, dimethylamine borane, was used to form the nickel layer. ..

(Example 5)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness Y of the nickel layer and the thickness A of the nickel layer in the portion without protrusions were changed to 50 nm.

(Example 6)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness Y of the nickel layer and the thickness A of the nickel layer in the portion without protrusions were changed to 95 nm.

(Example 7)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness X of the copper layer was changed to 5 nm.

(Example 8)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness X of the copper layer was changed to 10 nm.

(Example 9)
Conductive particles were obtained in the same manner as in Example 1 except that the thickness X of the copper layer was changed to 300 nm.

(Example 10)
Conductive particles were obtained in the same manner as in Example 1 except that the average particle size of the core substance contained in the silica particle slurry was changed to 240 nm and the average height B of the protrusions was changed to 240 nm.

(Example 11)
Conductive particles were obtained in the same manner as in Example 1 except that the average particle size of the core substance contained in the silica particle slurry was changed to 300 nm and the average height B of the protrusions was changed to 300 nm.

(Example 12)
Conductive particles were obtained in the same manner as in Example 1 except that the silica particle slurry was changed to a nickel particle slurry (average particle diameter of nickel as a core substance of 100 nm).

( Reference example 13)
The organic-inorganic hybrid particles of Example 1 were used. Conductive particles were obtained in the same manner as in Example 1 except that no protrusions were formed by using the organic-inorganic hybrid particles to which the silica particle slurry was not attached.

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

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

10 g of the conductive particles obtained in Example 1 was dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 6 hours. After filtering with a 3 μm mesh filter, the mixture was further washed with methanol and dried to obtain conductive particles to which insulating particles were attached.

When observed with a scanning electron microscope (SEM), only one coating layer of insulating particles was formed on the surface of the conductive particles. When the covering area of the insulating particles (that is, the projected area of the particle diameter of the insulating particles) was calculated with respect to the area 2.5 μm from the center of the conductive particles by image analysis, the covering ratio was 30%.

(Comparative Example 1)
Conductive particles were obtained in the same manner as in Example 1 except that the nickel layer was not formed, that is, only the copper layer was formed on the surface of the organic-inorganic hybrid particles.

(Comparative Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the copper layer was not formed, that is, only the nickel layer was formed on the surface of the organic-inorganic hybrid particles.

(Comparative Example 3)
Conductive particles were obtained in the same manner as in Example 2 except that the nickel layer was not formed, that is, only the copper layer was formed on the surface of the resin particles.

(Comparative Example 4)
Conductive particles were obtained in the same manner as in Example 2 except that the copper layer was not formed, that is, only the nickel layer was formed on the surface of the resin particles.

(Comparative Example 5)
Conductive particles were formed in the same manner as in Example 1 except that an electroless nickel plating solution containing nickel sulfate and a reducing agent dimethylamine borane and not containing sodium tungstate was used when forming the nickel layer. Got

(Comparative Example 6)
Conductive particles were formed in the same manner as in Example 2 except that an electroless nickel plating solution containing nickel sulfate and a reducing agent dimethylamine borane and not containing sodium tungstate was used when forming the nickel layer. Got

(Example 15)
A core-shell type organic in which the surface of divinylbenzene copolymer resin particles having a particle size of 1.75 μm is coated with silica (inorganic shell, thickness 250 nm) using a condensation reaction by a sol-gel reaction instead of the base particle A. Conductive particles were obtained in the same manner as in Example 1 except that inorganic hybrid particles (base particle C, 10% K value: 6000 mN / mm ^{2) were used.} The number of protrusions was 40.

( Reference example 16)
A core-shell type organic in which the surface of divinylbenzene copolymer resin particles having a particle size of 9.5 μm is coated with silica (inorganic shell, thickness 250 nm) using a condensation reaction by a sol-gel reaction instead of the base particle A. Conductive particles were obtained in the same manner as in Example 1 except that inorganic hybrid particles (base particle D, 10% K value: 4500 mN / mm ^{2) were used.} The number of protrusions was 750.

(Example 17)
The conductive particles obtained in Example 1 (before the rust preventive treatment) were dispersed in 2-ethylhexyl azide phosphate, and then the conductive particles were taken out to make the outer surface rust preventive. Obtained particles.

(Example 18)
Conductive particles were obtained in the same manner as in Example 1 except that the content of tungsten in the nickel plating layer in the obtained conductive particles was changed to 5% by weight.

(Example 19)
Conductive particles were obtained in the same manner as in Example 1 except that the content of tungsten in the nickel plating layer in the obtained conductive particles was changed to 0.1% by weight.

(Example 20)
Conductive particles were obtained in the same manner as in Example 1 except that the content of tungsten in the nickel plating layer in the obtained conductive particles was changed to 5.5% by weight.

(Example 21)
Conductive particles were obtained in the same manner as in Example 1 except that the content of tungsten in the nickel plating layer in the obtained conductive particles was changed to 0.05% by weight.

(evaluation)
(0) State of protrusions Using a scanning electron microscope (SEM), the image magnification was 25,000 times for particles with a particle size of less than 4 μm, and 8000 times for particles with a particle size of 4 μm or more and less than 8 μm. In the case of particles having a particle size of 8 μm or more, the value was set to 3000 times, 10 conductive particles were randomly selected, and the protrusions of each conductive particle were observed. The number of protrusions was counted.

(1) Content of copper in 100% by weight of copper layer and content of nickel, boron or phosphorus, and tungsten or molybdenum in 100% by weight of nickel layer A particle cross section was prepared using "FIB (SMI500)" manufactured by SII. It was cut out and analyzed by EDS line using "FE-TEM (JEM-2010FEF)" manufactured by JEOL Ltd., and the contents of copper, nickel, boron or phosphorus, and tungsten or molybdenum were measured.

(2) Initial connection resistance A
Fabrication of connection structure:
It was left for 100 hours in the obtained constant temperature and humidity chamber at 85 ° C. and 85% humidity. Using the conductive particles after being left to stand, an anisotropic conductive paste was obtained as follows.

20 parts by weight of an epoxy compound (“EP-3300P” manufactured by Nagase ChemteX Corporation) which is a thermosetting compound, 15 parts by weight of an epoxy compound (“EPICLON HP-4032D” manufactured by DIC Co., Ltd.) which is a thermosetting compound, and heat. A thermosetting agent (Sun Aid "SI-60" manufactured by Sanshin Chemical Co., Ltd.) (5 parts by weight) and a filler (silica (average particle size 0.25 μm) (20 parts by weight) (20 parts by weight) were blended and further obtained. After adding the conductive particles so that the content in 100% by weight of the compound was 10% by weight, the mixture was stirred at 2000 rpm for 5 minutes using a planetary stirrer to obtain an anisotropic conductive paste.

A glass substrate having an Al—Ti 4% electrode pattern (Al—Ti 4% electrode thickness 1 μm) having an L / S of 20 μm / 20 μm on the upper surface was prepared. Further, a semiconductor chip having a gold electrode pattern (gold electrode thickness 20 μm) having an L / S of 20 μm / 20 μm on the lower surface was prepared.

An anisotropic conductive paste immediately after production was applied to the upper surface of the glass substrate so as to have a thickness of 20 μm to form an anisotropic conductive material layer. Next, the semiconductor chips were laminated on the upper surface of the anisotropic conductive material layer so that the electrodes face each other. After that, while adjusting the temperature of the head so that the temperature of the anisotropic conductive material layer becomes 170 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 3.0 MPa is applied to apply anisotropic conductivity. The material layer was cured at 170 ° C. to obtain a connecting structure.

Measurement of connection resistance:
The connection resistance between the opposing electrodes of the obtained connection structure was measured by the 4-terminal method. Further, the initial connection resistance A was determined according to the following criteria.

[Evaluation criteria for initial connection resistance A]
○ ○ ○: Connection resistance is 2.0Ω or less ○ ○: Connection resistance is more than 2.0Ω, 3.0Ω or less ○: Connection resistance is more than 3.0Ω, 5.0Ω or less △: Connection resistance is 5.0Ω More than 10Ω, △△: Connection resistance exceeds 10Ω, 15Ω or less ×: Connection resistance exceeds 15Ω

(3) Connection resistance B after exposure to the presence of acid
The connection structure obtained in the above (2) initial evaluation of the connection resistance A was left in a constant temperature and humidity chamber at 85 ° C. and 85% humidity for 100 hours. By leaving the connection structure under the above conditions, the connection portion between the electrodes in the connection structure is exposed to the presence of acid for a certain period of time due to the reaction between the water infiltrated into the binder resin and the acid contained in the binder resin. Was done. In the connection structure after being left to stand, the connection resistance between the opposing electrodes of the connection structure was measured by the 4-terminal method. In addition, the connection resistance B after being exposed to the presence of acid was determined according to the following criteria.

[Evaluation criteria for connection resistance B after exposure to the presence of acid]
○ ○ ○: Connection resistance B is less than 1 times the connection resistance A ○ ○: Connection resistance B is 1 time or more and less than 1.5 times the connection resistance A ○: Connection resistance B is 1.5 times or more the connection resistance A Less than 2 times Δ: Connection resistance B is 2 times or more and less than 5 times that of connection resistance A △△: Connection resistance B is 5 times or more and less than 10 times that of connection resistance A ×: Connection resistance B is 10 times that of connection resistance A More than double

The results are shown in Table 1 below.

Regarding variations in connection resistance among a plurality of connection structures, connection structures using conductive particles of Examples 1 to 10, 12, Reference Example 13, Examples 14 to 15, Reference Example 16, and Examples 17 to 21. Was smaller than the connection structure using the conductive particles of Example 11. It is considered that this is because, in Example 11, since the average height B / thickness A is relatively large, the connection resistance varies.

Although specific examples and reference examples in which the copper layer is formed are shown, even when the silver layer is formed instead of the copper layer, the effect of reducing the initial connection resistance and the connection resistance in the presence of acid are shown. It was confirmed that the effect of suppressing the rise was obtained. However, when the copper layer was formed, the effect of reducing the initial connection resistance and the effect of suppressing the increase of the connection resistance in the presence of acid were larger than those of the case where the silver layer was formed.

1,1A, 1B, 1C, 1D ... Conductive particles 1a, 1Aa, 1Ba, 1Ca ... Projections 11 ... Base particles 12, 12A, 12B, 12D ... First conductive layers 12a, 12Aa ... Projections 13, 13B, 13D ... Second conductive layer 13a, 13Ba ... Protrusion 14 ... Core material 15 ... Insulating material 21 ... Base particle 21X ... Core 22Y ... Shell 51 ... Connection structure 52 ... First connection target member 52a ... First electrode 53 ... Second connection target member 53a ... Second electrode 54 ... Connection portion

Claims (12)

With base particles
A first conductive layer arranged on the surface of the base particles and formed of silver or copper,
A second conductive layer arranged on the outer surface of the first conductive layer and formed of nickel ,
A core material for raising the outer surface of the second conductive layer is provided.
The second conductive layer has a plurality of protrusions on the outer surface and has a plurality of protrusions.
The Mohs hardness of the material of the core material is 4 or more, and the material has a Mohs hardness of 4 or more.
The particle size of the base particles is 0.1 μm or more and 5 μm or less.
Conductive particles in which the second conductive layer contains nickel, boron, tungsten or molybdenum. The conductive particle according to claim 1, wherein the content of nickel in the second conductive layer is 50% by weight or more and 99% by weight or less. The conductive particles according to claim 1 or 2 , wherein the content of tungsten or molybdenum in the second conductive layer is 0.1% by weight or more and 5.0% by weight or less. The conductive particle according to any one of claims 1 to 3 , wherein the content of boron in the second conductive layer is 0.1% by weight or more and 5.0% by weight or less. The conductive particle according to any one of claims 1 to 4 , wherein the thickness of the second conductive layer is 0.1 times or more and 10 times or less the thickness of the first conductive layer. The conductive particles according to any one of claims 1 to 5 , wherein the first conductive layer is a copper layer formed of copper. The conductive particles according to any one of claims 1 to 6 , wherein the base particles are resin particles or organic-inorganic hybrid particles. The conductive particles according to claim 7 , wherein the base particles are the organic-inorganic hybrid particles. The conductive particle according to any one of claims 1 to 8 , wherein the outer surface of the second conductive layer is rust-proofed. The conductive particle according to any one of claims 1 to 9 , further comprising an insulating substance arranged on the outer surface of the second conductive layer. A conductive material containing the conductive particles according to any one of claims 1 to 10 and a binder resin. A first connection target member having a first electrode on its surface,
A second connection target member having a second electrode on the surface,
The first connection target member and the connection portion connecting the second connection target member are provided.
The connecting portion is formed of the conductive particles according to any one of claims 1 to 10 , or is formed of a conductive material containing the conductive particles and a binder resin.
A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles.

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