JP6478308B2 - Conductive particles, conductive materials, and connection structures - Google Patents

Description

  The present invention relates to conductive particles in which a conductive layer is arranged on the surface of base particles, and more particularly to conductive particles that can be used for electrical connection between electrodes, for example. The present invention also relates to a conductive material and a connection structure using the conductive particles.

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

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

  For example, when the electrode of the semiconductor chip and the electrode of the glass substrate are electrically connected by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the glass substrate. Next, the semiconductor chips are stacked, and heated and pressurized. Accordingly, the anisotropic conductive material is cured, and the electrodes are electrically connected through the conductive particles to obtain a connection structure.

  As an example of the conductive particles, the following Patent Document 1 discloses a conductive material in which a nickel conductive layer or a nickel alloy conductive layer is formed on the surface of spherical base particles having an average particle diameter of 1 to 20 μm by an electroless plating method. Sex particles are disclosed. The conductive particles have minute protrusions of 0.05 to 4 μm on the outermost layer of the conductive layer. The conductive layer and the protrusion are substantially continuously connected.

  Patent Document 2 below discloses conductive particles in which an alloy plating film containing nickel, copper, and phosphorus is formed on the surface of core material particles by an electroless plating method.

JP 2000-243132 A JP 2006-52460 A

  In the conventional conductive particles as described in Patent Documents 1 and 2, a plurality of conductive particles may aggregate. When electrodes are connected using a plurality of aggregated conductive particles, a short circuit between the electrodes may occur.

  Moreover, in the electroconductive particle of the Example of patent document 1, the electroconductive layer containing nickel and phosphorus is formed. In many cases, an oxide film is formed on the surfaces of the electrodes connected by the conductive particles and the conductive layer of the conductive particles. When conductive particles having a conductive layer containing nickel and phosphorus are connected between the electrodes, the conductive layer containing nickel and phosphorus is relatively soft. It may not be sufficiently eliminated, and the connection resistance may increase.

  Moreover, when the thickness of the conductive layer containing nickel and phosphorus as described in Patent Document 1 is increased in order to reduce the connection resistance, the connection target member or the substrate may be damaged by the conductive particles.

  The conductive particles described in Patent Document 2 have a problem that migration tends to occur on the outer surface of the alloy plating film. For example, when exposed to harsh conditions such as high temperature and high humidity or long-term continuous use, migration occurs on the outer surface of the conductive layer, resulting in poor conduction between electrodes or high connection resistance between electrodes. It becomes.

  An object of the present invention is to provide conductive particles capable of suppressing aggregation and further suppressing migration from occurring on the outer surface of a conductive layer, and a conductive material and a connection structure using the conductive particles. .

  A limited object of the present invention is to improve the adhesion between the base particles and the conductive layer, and when used for connection between the electrodes, the conductive particles capable of reducing the connection resistance between the electrodes, and It is to provide a conductive material and a connection structure using the conductive particles.

  According to a wide aspect of the present invention, there is provided a base material particle, a conductive layer disposed on the surface of the base material particle, and containing nickel, at least one of boron and phosphorus, and copper. And the copper content in the entire region on the outer surface side of the conductive layer thickness 1/3 is the central region of the conductive layer thickness 1/3 and the inner surface of the conductive layer thickness 1/3 A conductive particle is provided that is less than the copper content in the entire region of 2/3 thickness including the region on the side.

  On the specific situation with the electroconductive particle which concerns on this invention, content of nickel in the whole area | region of the outer surface side of the thickness 1/3 of the said conductive layer is the center area | region of the thickness 1/3 of the said conductive layer, and It is larger than the nickel content in the entire region having a thickness of 2/3 including the region on the inner surface side of the conductive layer having a thickness of 1/3.

  On the specific situation with the electroconductive particle which concerns on this invention, copper content in the whole area | region of the outer surface side of the thickness 1/3 of the said conductive layer is the whole center area | region of the thickness 1/3 of the said conductive layer. Less than the copper content in

  On the specific situation with the electroconductive particle which concerns on this invention, nickel content in the whole area | region of the outer surface side of the thickness 1/3 of the said conductive layer is the whole center area | region of the thickness 1/3 of the said conductive layer. More than the nickel content in

  In a specific aspect of the conductive particles according to the present invention, the content of copper in the entire central region of the conductive layer thickness ３ is the entire region on the inner surface side of the conductive layer thickness １ ／. More than the copper content.

  In a specific aspect of the conductive particles according to the present invention, the content of nickel in the entire region on the inner surface side of the thickness 1/3 of the conductive layer is the entire region in the center of the thickness 1/3 of the conductive layer. More than the nickel content in

  In a specific aspect of the conductive particles according to the present invention, the content of nickel is 49% by weight or more and 99% by weight or less in the entire region on the outer surface side of the thickness 1/3 of the conductive layer. Content is 0.1 weight% or more and 50 weight% or less.

  In a specific aspect of the conductive particle according to the present invention, a region having a thickness of 2/3 including a central region of the conductive layer having a thickness of 1/3 and a region on the inner surface side of the conductive layer having a thickness of 1/3. Overall, the nickel content is 29 wt% or more and 89 wt% or less, and the copper content is 10 wt% or more and 75 wt% or less.

  In a specific aspect of the conductive particles according to the present invention, the content of nickel is 1 wt% or more and 79 wt% or less in the entire central region of the thickness 1/3 of the conductive layer, and the content of copper Is 20% by weight or more and 98% by weight or less.

  In a specific aspect of the conductive particle according to the present invention, the content of nickel is 49% by weight or more and 99% by weight or less in the entire region on the inner surface side of the thickness ３ of the conductive layer, Content is 0.1 weight% or more and 50 weight% or less.

  On the specific situation with the electroconductive particle which concerns on this invention, the said conductive layer contains nickel, boron, and copper, and the said conductive layer does not contain or contains phosphorus.

  In a specific aspect of the conductive particles according to the present invention, the conductive layer contains boron, and the content of boron in 100% by weight of the entire conductive layer is 0.05% by weight or more and 4% by weight or less. is there.

  On the specific situation with the electroconductive particle which concerns on this invention, the said conductive layer has a processus | protrusion on an outer surface.

  In a specific aspect of the conductive particles according to the present invention, the conductive layer contains no or contains phosphorus, and the content of phosphorus in 100% by weight of the entire conductive layer is less than 0.5% by weight. is there.

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

  According to a wide aspect of the present invention, a first connection target member, a second connection target member, and a connection portion connecting the first connection target member and the second connection target member. A connection structure is provided in which the connection portion is formed of the above-described conductive particles or is formed of a conductive material containing the conductive particles and a binder resin.

  In the conductive particles according to the present invention, a conductive layer containing at least one of nickel, boron, and phosphorus and copper is disposed on the surface of the base particle, and the thickness of the conductive layer is 1/3. The copper content in the entire region on the outer surface side is 2/3 of the thickness including the center region of the conductive layer thickness １ ／ and the inner surface side region of the conductive layer thickness １ ／. Since it is less than the copper content in the entire region, aggregation of a plurality of conductive particles can be suppressed. Furthermore, in the electroconductive particle which concerns on this invention, it can suppress that a migration generate | occur | produces on the outer surface of an electroconductive layer.

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 the second embodiment of the present invention. FIG. 3 is a cross-sectional view showing conductive particles according to the third embodiment of the present invention. FIG. 4 is a front cross-sectional view schematically showing a connection structure using conductive particles according to the first embodiment of the present invention. FIG. 5 shows the region on the outer surface side of the conductive layer thickness 1/3, the central region of the conductive layer thickness 1/3, and the thickness of the conductive layer in the conductive particles according to the third embodiment of the present invention. It is a schematic diagram for demonstrating the area | region of the inner surface side of 1/3.

  Details of the present invention will be described below.

  The electroconductive particle which concerns on this invention has a base material particle and the electroconductive layer arrange | positioned on the surface of this base material particle. The conductive layer contains nickel, at least one of boron and phosphorus, and copper. The conductive layer is a nickel-boron / phosphorus-copper conductive layer. “Boron / Phosphorus” means that at least one of boron and phosphorus is included. In the conductive particles according to the present invention, the copper content in the entire region R1 on the outer surface side of the conductive layer thickness 1/3 is equal to the central region R2 of the conductive layer thickness 1/3 and the conductive layer. Less than the copper content in the entire region R2, R3 having a thickness of 2/3 including the region R3 on the inner surface side having a thickness of 1/3.

  Nickel makes the conductive layer relatively hard. Copper makes the conductive layer relatively soft. Copper lowers the magnetism of the conductive layer than nickel. Nickel lowers the connection resistance between the electrodes connected by the conductive layer than copper.

  Also, for example, the surface of a conductive layer containing nickel and boron has high magnetism, and when electrodes are electrically connected, the electrodes adjacent to each other in the lateral direction are connected due to the influence of conductive particles aggregated by magnetism. There is a tendency to be easily. In the electroconductive particle which concerns on this invention, since the said conductive layer contains copper, the magnetism of the surface of the said conductive layer becomes quite low. For this reason, it can suppress that several electroconductive particle aggregates. Therefore, when the electrodes are electrically connected, it is possible to prevent the electrodes adjacent in the lateral direction from being connected by the aggregated conductive particles. That is, a short circuit between adjacent electrodes can be prevented.

  Further, in the present invention, the copper content in the entire region R1 on the outer surface side of the conductive layer thickness 1/3 is equal to the central region R2 of the conductive layer thickness 1/3 and the thickness 1 of the conductive layer. Since the content of copper in the entire region R2, R3 having a thickness of 2/3 including the region R3 on the inner surface side of / 3 is smaller than that, the aggregation of a plurality of conductive particles is more effectively suppressed. And the short circuit between the electrodes can be more effectively prevented.

  Further, in the present invention, the copper content in the entire region R1 on the outer surface side of the conductive layer thickness 1/3 is equal to the central region R2 of the conductive layer thickness 1/3 and the thickness 1 of the conductive layer. Since the content of copper in the entire region R2, R3 having a thickness of 2/3 including the region R3 on the inner surface side of / 3 is smaller than that of the region R3, migration can be suppressed from occurring on the outer surface of the conductive layer. When the electrodes are connected using the conductive particles according to the present invention, even when exposed to severe conditions such as high temperature and high humidity or long-term continuous use, the conduction between the electrodes can be maintained well, and the connection resistance Can be kept low.

  Furthermore, in the electroconductive particle which concerns on this invention, since the said electroconductive layer contains nickel, when connecting between electrodes by electroconductive particle, the connection resistance between electrodes becomes low. When the content of nickel in 100% by weight of the entire conductive layer (the entire region R1, R2, R3) in the conductive particles according to the present invention is 50% by weight or more, the connection resistance between the electrodes becomes considerably low.

  In addition, in the conductive particles having a nickel conductive layer that does not contain boron, the nickel conductive layer that does not contain boron is too soft, and the oxide film on the surface of the electrode and conductive particles can be sufficiently eliminated when connecting the electrodes. Therefore, the connection resistance tends to increase. For example, in a conductive particle having a conductive layer containing nickel and phosphorus, the oxide film on the surface of the electrode and the conductive particle cannot be sufficiently eliminated, and the connection resistance tends to increase. In particular, when the content of phosphorus in 100% by weight of the entire conductive layer is 0.5% by weight or more, the connection resistance tends to increase.

  On the other hand, if the thickness of the conductive layer containing nickel and phosphorus is increased in order to reduce the connection resistance, the connection target member or the substrate may be damaged by the conductive particles.

  On the other hand, when the conductive layer contains nickel and boron, the hardness of the conductive layer is relatively high, so that the connection resistance between the electrodes can be reduced. When connecting the electrodes, the oxide film on the surfaces of the electrodes and the conductive particles can be eliminated, and the connection resistance can be lowered.

  Accordingly, the conductive layer preferably contains boron. That is, the conductive layer preferably includes nickel, boron, and copper. Moreover, it is preferable that the said conductive layer contains nickel, boron, and copper, and the said conductive layer does not contain or contains phosphorus.

  When the conductive layer contains nickel, boron, and copper, the hardness of the conductive layer can be maintained sufficiently high. For this reason, the oxide film on the surface of an electrode and electroconductive particle can fully be excluded, and connection resistance can be made low enough. That is, both suppression of aggregation of conductive particles and reduction in connection resistance between electrodes can be achieved. In particular, when the conductive layer contains nickel, boron, and copper, and the conductive layer has protrusions on the outer surface, the oxide film on the surface of the electrode and conductive particles can be more effectively eliminated, and the connection resistance Can be further reduced.

  Further, since the conductive layer contains nickel, boron, and copper, the hardness of the conductive layer can be maintained sufficiently high. As a result, even if an impact is applied to the connection structure connecting the electrodes by the conductive particles. , Conduction failure is less likely to occur. That is, the impact resistance of the connection structure can be increased.

From the viewpoint of further reducing the connection resistance and further improving the connection reliability between the electrodes, the compression elastic modulus (10% K value) when the conductive particles are compressed by 10% is preferably 7000 N / mm ² or more. More preferably, it is 8000 N / mm ² or more.

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

  Using a micro-compression tester, the conductive particles are compressed under the conditions of 25 ° C., compression speed of 2.6 mN / sec, and maximum test load of 10 gf on the end face of a cylindrical indenter (diameter 50 μm, made of diamond). The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the conductive particles are 10% compressively deformed (N)
S: Compression displacement (mm) when the conductive particles are 10% compressively deformed
R: radius of conductive particles (mm)

  Hereinafter, the present invention will be clarified by describing 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.

  As shown in FIG. 1, the conductive particles 1 include base material particles 2, a conductive layer 3, a plurality of core substances 4, and a plurality of insulating substances 5.

  The conductive layer 3 is disposed on the surface of the base particle 2. The conductive layer 3 includes nickel, at least one of boron and phosphorus, and copper. In the present embodiment, the conductive layer 3 includes nickel, boron, and copper. The conductive particle 1 is a coated particle in which the surface of the base particle 2 is coated with the conductive layer 3.

  The conductive particle 1 has a plurality of protrusions 1a on a conductive surface. The conductive layer 3 has a plurality of protrusions 3a on the outer surface. A plurality of core substances 4 are arranged on the surface of the base particle 2. A plurality of core materials 4 are embedded in the conductive layer 3. The core substance 4 is disposed inside the protrusions 1a and 3a. The conductive layer 3 covers a plurality of core materials 4. The outer surface of the conductive layer 3 is raised by the plurality of core materials 4 to form protrusions 1a and 3a.

  The conductive particles 1 have an insulating substance 5 disposed on the outer surface of the conductive layer 3. At least a part of the outer surface of the conductive layer 3 is covered with the insulating material 5. The insulating substance 5 is made of an insulating material and is an insulating particle. Thus, the electroconductive particle which concerns on this invention may have the insulating substance arrange | positioned on the outer surface of an electroconductive layer. However, the conductive particles according to the present invention do not necessarily have an insulating substance.

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

  The conductive particles 11 shown in FIG. 2 include base material particles 2, a second conductive layer 12 (another conductive layer), a conductive layer 13 (first conductive layer), a plurality of core substances 4, and a plurality of Insulating material 5.

  Only the conductive layer is different between the conductive particles 1 and the conductive particles 11. That is, the conductive particle 1 has a single-layered conductive layer, whereas the conductive particle 11 has a two-layered second conductive layer 12 and conductive layer 13.

  The conductive layer 13 is disposed on the surface of the base particle 2. A second conductive layer 12 (another conductive layer) is disposed between the base particle 2 and the conductive layer 13. Therefore, the second conductive layer 12 is disposed on the surface of the base particle 2, and the conductive layer 13 is disposed on the surface of the second conductive layer 12. The conductive layer 13 contains nickel, at least one of boron and phosphorus, and copper. The conductive layer 13 has a plurality of protrusions 13a on the outer surface. The conductive particles 11 have a plurality of protrusions 11a on the conductive surface.

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

  The conductive particles 21 shown in FIG. 3 have base material particles 2 and a conductive layer 22. The conductive layer 22 is disposed on the surface of the base particle 2. The conductive layer 22 contains nickel, at least one of boron and phosphorus, and copper.

  The conductive particles 21 do not have a core substance. The conductive particles 21 do not have protrusions on the surface. The conductive particles 21 are spherical. The conductive layer 22 has no protrusion on the surface. Thus, the electroconductive particle which concerns on this invention does not need to have a processus | protrusion, and may be spherical. Further, the conductive particles 21 do not have an insulating material. However, the conductive particles 21 may have an insulating material disposed on the surface of the conductive layer 22.

  In the conductive particles 1, 11, 21, the copper content in the entire region R 1 on the outer surface side of the thickness 1/3 of the conductive layers 3, 13, 22 is the thickness 1/3 of the conductive layers 3, 13, 22. Is less than the copper content in the entire region R2, R3 having a thickness of 2/3, including the region R2 in the center of the region and the region R3 on the inner surface side of the thickness 1/3 of the conductive layers 3, 13, 22.

  5, the region R1 on the outer surface side of the thickness 1/3 of the conductive layer 22 in the conductive particles 21 shown in FIG. 3, the region R2 at the center of the thickness 1/3 of the conductive layer 22, and the conductive layer 22 are shown. The region R3 on the inner surface side having a thickness of 1/3 is shown. Regions R1, R2, and R3 obtained by dividing the conductive portion 22 of the conductive particle 21 shown in FIG. 3 into three in the thickness direction are specifically shown in FIG. 5, but the conductive particles 1 and 11 shown in FIGS. The regions R1, R2, and R3 are regions obtained by dividing the conductive portions 3 and 13 into three in the thickness direction.

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

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. Of these, substrate particles excluding metal particles are preferable, and resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles are preferable. The base particle may be a core-shell particle including a core and a shell disposed on the surface of the core.

  The substrate particles are preferably resin particles formed of a resin. When connecting between electrodes using the said electroconductive particle, after arrange | positioning the said electroconductive particle between electrodes, the said electroconductive particle is compressed by crimping | bonding. When the substrate particles are resin particles, the conductive particles are easily deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes high.

  Various organic materials are suitably 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, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyethylene Polyalkylene terephthalates such as 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 oxide, polyacetal, polyimide, polya Doimido, polyether ether ketone, polyether sulfone, divinyl benzene polymer, and divinylbenzene copolymer, and the like. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the substrate particles can be easily controlled within a suitable range, the resin for forming the resin particles is obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups. A polymer is preferred.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

  Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl ( Alkyl (meth) acrylates such as meth) acrylate and isobornyl (meth) acrylate; oxygen such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate (Meth) acrylates; nitrile-containing monomers such as (meth) acrylonitrile; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether; vinyl acids such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate Esters; Unsaturated hydrocarbons such as ethylene, propylene, isoprene and butadiene; Halogen-containing monomers such as trifluoromethyl (meth) acrylate, pentafluoroethyl (meth) acrylate, vinyl chloride, vinyl fluoride and chlorostyrene Is mentioned.

  Examples of the crosslinkable monomer include tetramethylolmethane tetra (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Polyfunctional (meth) acrylates such as acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanure And silane-containing monomers such as triallyl trimellitate, divinylbenzene, diallyl phthalate, diallylacrylamide, diallyl ether, γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, vinyltrimethoxysilane It is done.

  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, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

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

  When the substrate particles are metal particles, examples of the metal for forming the metal particles include silver, copper, nickel, silicon, gold, and titanium. However, the substrate particles are preferably not metal particles.

  The particle diameter of the substrate particles is preferably 0.1 μm or more, more preferably 1 μm or more, still more preferably 1.5 μm or more, particularly preferably 2 μm or more, preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably. Is not more than 300 μm, more preferably not more than 50 μm, particularly preferably not more than 30 μm, and most preferably not more than 5 μm. When the particle diameter of the substrate particles is equal to or greater than the above lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is further increased, and the electrodes are connected via the conductive particles. The connection resistance between them becomes even lower. Further, when forming the conductive layer on the surface of the base particle by electroless plating, it becomes difficult to aggregate and the aggregated conductive particles are hardly formed. When the particle diameter is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes is further reduced, and the distance between the electrodes is further reduced. The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

  The particle diameter of the substrate particles is particularly preferably 2 μm or more and 5 μm or less. When the particle diameter of the substrate particles is in the range of 2 to 5 μm, even when the distance between the electrodes is small and the thickness of the conductive layer is increased, small conductive particles can be obtained. The particle diameter of the substrate particles may be 3 μm or less.

[Conductive layer]
The electroconductive particle which concerns on this invention is arrange | positioned on the surface of a base material particle, and has an electroconductive layer containing at least 1 sort (s) among nickel, boron, and phosphorus, and copper. Hereinafter, a conductive layer containing at least one of nickel, boron, and phosphorus and copper may be referred to as a conductive layer X. The conductive layer X is a nickel-boron / phosphorus-copper conductive layer. The conductive layer X may be directly laminated on the surface of the base particle, or may be disposed on the surface of the base particle via another conductive layer or the like.

  In the conductive particles according to the present invention, the content of copper in the entire region R1 on the outer surface side of the thickness 1/3 of the conductive layer X is equal to the central region R2 of the thickness 1/3 of the conductive layer X and the above-described region. It is less than the copper content in the entire region R2, R3 having a thickness of 2/3 including the region R3 on the inner surface side of the conductive layer X having a thickness of 1/3.

  From the viewpoint of more effectively suppressing aggregation of a plurality of conductive particles, the absolute value of the difference between the copper content in the entire region R1 and the copper content in the entire regions R2 and R3 is , Preferably 10% by weight or more, more preferably 50% by weight or more. The absolute value of the difference between the copper content in the entire region R1 and the copper content in the entire region R2, R3 may be 20% by weight or less, or 50% by weight or less. Good.

  The copper content in the entire region R1 on the outer surface side of the conductive layer X having a thickness of 1/3 is less than the copper content in the entire region R2 in the center of the conductive layer X having a thickness of 1/3. Is preferred. In this case, aggregation of a plurality of conductive particles can be further effectively suppressed, and a short circuit between the electrodes can be further effectively prevented.

  From the viewpoint of more effectively suppressing aggregation of a plurality of conductive particles, the absolute value of the difference between the copper content in the entire region R1 and the copper content in the entire region R2 is preferably Is 20% by weight or more, more preferably 40% by weight or more. The absolute value of the difference between the copper content in the entire region R1 and the copper content in the entire region R2 may be 20% by weight or less, or 50% by weight or less.

  The content of nickel in the entire region R1 on the outer surface side of the thickness 厚 み of the conductive layer X is such that the central region R2 of the thickness １ ／ of the conductive layer X and the thickness １ ／ of the conductive layer X are 1/3. It is preferable that the content is larger than the nickel content in the entire region R2, R3 having a thickness of 2/3 including the region R3 on the inner surface side. In this case, the occurrence of migration on the outer surface of the conductive layer X can be effectively suppressed, and the connection resistance between the electrodes can be effectively reduced.

  From the viewpoint of more effectively suppressing the occurrence of migration on the outer surface of the conductive layer X, the difference between the nickel content in the entire region R1 and the nickel content in the entire region R2, R3 The absolute value is preferably 10% by weight or more, more preferably 20% by weight or more. The absolute value of the difference between the nickel content in the entire region R1 and the nickel content in the entire region R2, R3 may be 40% by weight or less, or 70% by weight or less. Good.

  The nickel content in the entire region R1 on the outer surface side of the conductive layer X having a thickness of 1/3 is greater than the nickel content in the entire region R2 in the center of the conductive layer X having a thickness of 1/3. Is preferred. In this case, the occurrence of migration on the outer surface of the conductive layer X can be effectively suppressed, and the connection resistance between the electrodes can be effectively reduced.

  From the viewpoint of more effectively suppressing the occurrence of migration on the outer surface of the conductive layer X, the absolute value of the difference between the nickel content in the entire region R1 and the nickel content in the entire region R2 Is preferably 30% by weight or more, more preferably 50% by weight or more. The absolute value of the difference between the nickel content in the entire region R1 and the nickel content in the entire region R2 may be 60% by weight or less, or 98% by weight or less.

  The copper content in the entire central region R2 of the thickness ３ of the conductive layer X is larger than the copper content in the entire region R3 on the inner surface side of the thickness ３ of the conductive layer X. Is preferred. In this case, aggregation of a plurality of conductive particles can be further effectively suppressed, and a short circuit between the electrodes can be more effectively prevented. Furthermore, the flexibility of the conductive particles can be increased by the region R2 having a relatively large copper content.

  From the viewpoint of more effectively suppressing aggregation of a plurality of conductive particles, the absolute value of the difference between the copper content in the entire region R2 and the copper content in the entire region R3 is preferably Is 30% by weight or more, more preferably 50% by weight or more. The absolute value of the difference between the copper content in the entire region R1 and the copper content in the entire region R3 may be 60% by weight or less, or 98% by weight or less.

  The nickel content in the entire region R3 on the inner surface side of the conductive layer X having a thickness of 1/3 is greater than the nickel content in the entire region R2 in the center of the conductive layer X having a thickness of 1/3. Is preferred. In this case, the adhesion between the substrate particles and the conductive layer X is further improved. As a result, the connection resistance between the electrodes can be further reduced.

  From the viewpoint of further improving the adhesion between the base particles and the conductive layer X, the absolute value of the difference between the nickel content in the entire region R3 and the nickel content in the entire region R2 is preferably Is 30% by weight or more, more preferably 50% by weight or more. The absolute value of the difference between the nickel content in the entire region R3 and the nickel content in the entire region R2 may be 60% by weight or less, or 98% by weight or less.

  In the conductive layer X, at least one of nickel, boron, and phosphorus and copper may be alloyed. In the conductive layer X, chromium, tungsten, molybdenum, or seaborgium may be used in addition to nickel, boron, phosphorus, and copper.

  The conductive layer X preferably contains nickel as a main component. The total content of nickel in 100% by weight of the conductive layer X is preferably 10% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, still more preferably 70% by weight or more, particularly preferably. Is 90% by weight or more. The content of nickel in 100% by weight of the entire conductive layer X may be 97% by weight or more, 97.5% by weight or more, or 98% by weight or more. The upper limit of the nickel content can be appropriately changed depending on the contents of boron, phosphorus, and copper. The content of nickel in 100% by weight of the entire conductive layer X is preferably 99.85% by weight or less, more preferably 99.7% by weight or less, and still more preferably less than 99.45% by weight. When the nickel content is not less than the lower limit, the connection resistance between the electrodes is further reduced. Moreover, when there are few oxide films in the surface of an electrode and the conductive layer X, there exists a tendency for the connection resistance between electrodes to become low, so that content of the said nickel is large.

  In the entire region R1 on the outer surface side of the thickness 1/3 of the conductive layer X, the content of the nickel is preferably 49% by weight or more, more preferably 60% by weight or more, and preferably 99% by weight or less. Is 70% by weight or less. When the content of nickel in the entire region R1 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration on the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. A plurality of conductive particles are more difficult to aggregate.

  In the entire region R2 and R3 having a thickness of 2/3 including the central region R2 having a thickness of 1/3 of the conductive layer X and the region R3 on the inner surface side having a thickness of 1/3 of the conductive layer X, the inclusion of the nickel The amount is preferably 29% by weight or more, more preferably 50% by weight or more, preferably 89% by weight or less, more preferably 70% by weight or less. In the entire region R2, R3, the nickel content may be 25% by weight or more. When the nickel content in the entire region R2, R3 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration of the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. In addition, the plurality of conductive particles are more difficult to aggregate.

  The nickel content is preferably 1% by weight or more, more preferably 30% by weight or more, preferably 79% by weight or less, more preferably 60% by weight in the entire central region R2 of the thickness 1/3 of the conductive layer X. % By weight or less. When the content of nickel in the entire region R2 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration on the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. A plurality of conductive particles are more difficult to aggregate.

  In the entire region R3 on the inner surface side of the thickness 1/3 of the conductive layer X, the nickel content is preferably 49% by weight or more, more preferably 69% by weight or more, preferably 99% by weight or less, more preferably. Is 79% by weight or less. In the entire region R3, the nickel content may be 25% by weight or more. When the content of nickel in the entire region R3 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration on the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. The conductive particles are less likely to aggregate, and the adhesion between the substrate particles and the conductive layer X is further increased.

  The total content of boron and phosphorus in 100% by weight of the entire conductive layer X is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, still more preferably 0.1% by weight or more, It is preferably 5% by weight or less, more preferably 4% by weight or less, still more preferably 3% by weight or less, particularly preferably 2.5% by weight or less, and most preferably 2% by weight or less. When the total content of boron and phosphorus is not less than the above lower limit, the conductive layer X becomes harder, and the oxide film on the surface of the electrode and conductive particles can be more effectively removed, and the connection resistance between the electrodes Can be further reduced. When the total content of boron and phosphorus is not more than the above upper limit, the contents of nickel and copper are relatively increased, so that the connection resistance between the electrodes is lowered.

  The content of boron in 100% by weight of the conductive layer X is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, still more preferably 0.1% by weight or more, preferably 5% by weight. Below, more preferably 4% by weight or less, still more preferably 3% by weight or less, particularly preferably 2.5% by weight or less, and most preferably 2% by weight or less. When the boron content is not less than the above lower limit, the conductive layer X becomes harder, the oxide film on the surface of the electrode and conductive particles can be more effectively removed, and the connection resistance between the electrodes is further reduced. be able to. When the boron content is less than or equal to the above upper limit, the nickel and copper contents are relatively increased, so that the connection resistance between the electrodes is reduced.

  It is preferable that the conductive layer X does not contain phosphorus or contains phosphorus, and the content of phosphorus in 100% by weight of the entire conductive layer X is less than 0.5% by weight. The content of phosphorus in the total 100% by weight of the conductive layer X is more preferably 0.3% by weight or less, and still more preferably 0.1% by weight or less. It is particularly preferable that the conductive layer X does not contain phosphorus.

  The content of copper in the total 100% by weight of the conductive layer X is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, still more preferably 0.2% by weight or more, and still more preferably. 0.5% by weight or more, even more preferably 1% by weight or more, particularly preferably more than 5% by weight, most preferably 10% by weight or more. When the content of the copper in the entire conductive layer X is equal to or more than the lower limit, the hardness of the outer surface of the conductive layer X is further increased. For this reason, when the oxide film is formed on the surface of the electrode and the conductive layer X, the oxide film on the surface of the electrode and the conductive particles can be effectively eliminated, and the connection resistance can be lowered and obtained. The impact resistance of the connection structure can be increased. Furthermore, when the content of copper in the entire conductive layer X is equal to or more than the lower limit, the magnetism of the outer surface of the conductive layer X becomes weak and a plurality of conductive particles are difficult to aggregate. For this reason, the short circuit between electrodes can be suppressed effectively. The upper limit of the copper content in the total 100% by weight of the conductive layer X can be appropriately changed depending on the contents of nickel, boron and phosphorus. The copper content in the total 100% by weight of the conductive layer X is preferably 40% by weight or less, more preferably 30% by weight or less, still more preferably 25% by weight or less, and particularly preferably 20% by weight or less.

  In the entire region R1 on the outer surface side of the conductive layer X having a thickness of 1/3, the copper content is preferably 0.1% by weight or more, more preferably 10% by weight or more, preferably 50% by weight or less. More preferably, it is 40% by weight or less. When the copper content in the entire region R1 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration of the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. A plurality of conductive particles are more difficult to aggregate.

  In the entire region R2, R3 having a thickness of 2/3 including the central region R2 of the conductive layer X having a thickness of 1/3 and the region R3 on the inner surface side of the conductive layer X having a thickness of 1/3, the inclusion of the copper The amount is preferably 10% by weight or more, more preferably 20% by weight or more, preferably 75% by weight or less, more preferably 70% by weight or less, and further preferably 60% by weight or less. When the copper content in the entire region R2, R3 is not less than the above lower limit and not more than the above upper limit, the migration of the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. In addition, the plurality of conductive particles are more difficult to aggregate.

  The copper content is preferably 20% by weight or more, more preferably 30% by weight or more, preferably 98% by weight or less, more preferably 88% in the entire central region R2 of the thickness 1/3 of the conductive layer X. % By weight or less. When the copper content in the entire region R2 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration on the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. A plurality of conductive particles are more difficult to aggregate.

  In the entire region R3 on the inner surface side of the thickness 1/3 of the conductive layer X, the content of the copper is preferably 0.1 wt% or more, more preferably 10 wt% or more, preferably 50 wt% or less, More preferably, it is 40% by weight or less. When the copper content in the entire region R3 is not less than the above lower limit and not more than the above upper limit, the occurrence of migration on the outer surface of the conductive layer X is further suppressed, and the connection resistance between the electrodes is further reduced. The conductive particles are less likely to aggregate, and the adhesion between the substrate particles and the conductive layer X is further increased.

  From the viewpoint of further suppressing the aggregation of the conductive particles and further reducing the connection resistance between the electrodes, the total content of nickel and copper in 100% by weight of the entire conductive layer X is preferably 51. % By weight or more, more preferably 61% by weight or more, still more preferably 71% by weight or more, and particularly preferably 91% by weight or more. The total content of nickel and copper in 100% by weight of the entire conductive layer X may be 98% by weight or more, 98.5% by weight or more, and 99% by weight or more. Also good. The total content of nickel and copper in 100% by weight of the entire conductive layer X is preferably 99.95% by weight or less.

  The measuring method of each content of nickel, boron, phosphorus and copper in the conductive layer X is not particularly limited, and various known analytical methods can be used. Examples of this measuring method include absorption spectrometry or spectrum analysis. In the above-mentioned absorption analysis method, a flame absorptiometer, an electric heating furnace absorptiometer, or the like can be used. Examples of the spectrum analysis method include a plasma emission analysis method and a plasma ion source mass spectrometry method.

  When measuring the contents of nickel, boron, phosphorus and copper in the conductive layer X, it is preferable to use an ICP emission spectrometer. Examples of commercially available ICP emission analyzers include ICP emission analyzers manufactured by HORIBA. Moreover, when measuring each content of nickel, boron, phosphorus, and copper, you may use an ICP-MS analyzer.

  The metal for forming the other conductive layer (second conductive layer) is not particularly limited. Examples of the metal include gold, silver, copper, palladium, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and tungsten. And alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Especially, since the connection resistance between electrodes becomes still lower, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable. The metal constituting the other conductive layer preferably contains nickel.

  The method for forming a conductive layer (another conductive layer and conductive layer X) on the surface of the substrate particle is not particularly limited. As a method for forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a paste containing metal powder or metal powder and a binder is used for base particles or other conductive layers. For example, a method of coating the surface. Especially, since formation of a conductive layer is simple, the method by electroless plating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

  The particle diameter 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. When the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrodes is sufficiently large when the electrodes are connected using the conductive particles, and the conductive layer When forming the conductive particles, it becomes difficult to form aggregated conductive particles. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the base material particles.

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

  The thickness of the conductive layer X is preferably 0.005 μm or more, more preferably 0.01 μm or more, still more preferably 0.05 μm or more, preferably 1 μm or less, more preferably 0.3 μm or less. When the thickness of the conductive layer X is not less than the above lower limit and not more than the above upper limit, sufficient conductivity can be obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently bonded at the time of connection between the electrodes. Deform.

  When the conductive layer has a laminated structure of two or more layers, the thickness of the conductive layer X is preferably 0.001 μm or more, more preferably 0.01 μm or more, still more preferably 0.05 μm or more, preferably 0.5 μm or less. More preferably, it is 0.3 μm or less, and further preferably 0.1 μm or less. When the thickness of the conductive layer X is not less than the above lower limit and not more than the above upper limit, the coating with the conductive layer X can be made uniform, and the connection resistance between the electrodes becomes sufficiently low.

  The thickness of the conductive layer X is particularly preferably 0.05 μm or more and 0.3 μm or less. Furthermore, it is particularly preferable that the particle diameter of the base particles is 2 μm or more and 5 μm or less, and the thickness of the conductive layer X is 0.05 μm or more and 0.3 μm or less. In this case, the conductive particles can be suitably used for applications in which a large current flows. Furthermore, when the conductive particles are compressed to connect the electrodes, it is possible to further suppress the electrodes from being damaged.

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

  The number of protrusions on the outer surface of the conductive particles per one of the conductive particles is preferably 3 or more, more preferably 5 or more. The number of protrusions on the outer surface of the conductive layer per one conductive particle is preferably 3 or more, more preferably 5 or more. The upper limit of the number of protrusions is not particularly limited. The upper limit of the number of protrusions can be appropriately selected in consideration of the particle diameter of the conductive particles.

  As a method for controlling the contents of nickel, boron, phosphorus and copper in the conductive layer X, for example, a method of controlling the pH of the nickel plating solution when forming the conductive layer X by electroless nickel plating, electroless A method of adjusting the concentration of the boron-containing reducing agent when forming the conductive layer X by nickel plating, a method of adjusting the concentration of the phosphorus-containing reducing agent when forming the conductive layer X by electroless nickel plating, nickel plating Examples thereof include a method for adjusting the copper concentration in the liquid and a method for adjusting the nickel concentration in the nickel plating solution.

  As a method for controlling the contents of nickel, boron, phosphorus and copper in each of the regions R1, R2 and R3, the regions R1, R2 and R3 of the conductive layer X are formed by electroless nickel plating. A method of controlling the pH of the nickel plating solution, and a method of adjusting the concentration of the boron-containing reducing agent when forming the regions R1, R2, and R3 of the conductive layer X by electroless nickel plating. A method of adjusting the concentration of the phosphorus-containing reducing agent, a method of adjusting the copper concentration in the nickel plating solution, and nickel when forming the regions R1, R2, and R3 of the conductive layer X by electroless nickel plating Examples include a method of adjusting the nickel concentration in the plating solution.

  In the method of forming by electroless plating, generally, a catalyzing step and an electroless plating step are performed. Hereinafter, an example of a method for forming an alloy plating layer containing nickel, boron, and copper on the surface of resin particles by electroless plating will be described.

  In the catalyzing step, a catalyst serving as a starting point for forming a plating layer by electroless plating is formed on the surface of the resin particles.

  As a method of forming the catalyst on the surface of the resin particles, for example, after adding the resin particles to a solution containing palladium chloride and tin chloride, the surface of the resin particles is activated with an acid solution or an alkali solution, A method of depositing palladium on the surface of the resin particles, and after adding the resin particles to a solution containing palladium sulfate and aminopyridine, the surface of the resin particles is activated by a solution containing a reducing agent. Examples thereof include a method of depositing palladium on the surface. As the reducing agent, a boron-containing reducing agent is preferably used. In addition, a conductive layer containing phosphorus can be formed by using a phosphorus-containing reducing agent as the reducing agent.

  In the electroless plating step, a nickel plating bath containing a nickel-containing compound, the boron-containing reducing agent, and a copper-containing compound is preferably used. By immersing the resin particles in the nickel plating bath, nickel can be deposited on the surface of the resin particles on which the catalyst is formed, and a conductive layer containing nickel, boron, and copper can be formed.

  Examples of the nickel-containing compound include nickel sulfate and nickel chloride. The nickel-containing compound is preferably a nickel salt.

  Examples of the boron-containing reducing agent include dimethylamine borane, sodium borohydride, and potassium borohydride. Examples of the phosphorus-containing reducing agent include sodium hypophosphite.

  Examples of the copper-containing compound include copper sulfate, copper chloride, and copper pyrophosphate. The copper-containing compound is preferably a copper salt.

[Core material]
The conductive particles according to the present invention preferably have protrusions on the conductive surface. The conductive layer X preferably has protrusions on the outer surface. It is preferable that there are a plurality of the protrusions. An oxide film is often formed on the surface of the electrode connected by the conductive particles. Furthermore, an oxide film is often formed on the surface of the conductive layer of the conductive particles. By using the conductive particles having protrusions, the oxide film is effectively eliminated by the protrusions by placing the conductive particles between the electrodes and then pressing them. For this reason, an electrode and electroconductive particle can be contacted still more reliably and the connection resistance between electrodes can be made low. Furthermore, 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 protrusion between the conductive particles and the electrode is caused by the protrusion of the conductive particles. Resin can be effectively eliminated. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

  Since the core substance is embedded 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 surfaces of the conductive particles and the conductive layer, the core substance is not necessarily used.

  As a method for forming the protrusions, a method of forming a conductive layer by electroless plating after attaching a core substance to the surface of the base particle, and a method of forming a conductive layer by electroless plating on the surface of the base particle And a method of forming a conductive layer by electroless plating, and a method of adding a core material in the middle of forming the conductive layer by electroless plating on the surface of the substrate particles.

  As a method of disposing the core substance on the surface of the base particle, for example, the core substance is added to the dispersion of the base particle, and the core substance is applied to the surface of the base particle, for example, van der Waals force. And a method in which a core substance is added to a container containing base particles, and a core substance is attached to the surface of the base particles by mechanical action such as rotation of the container. . Especially, since the quantity of the core substance to adhere is easy to control, the method of making a core substance accumulate and adhere on the surface of the base particle in a dispersion liquid is preferable.

  Examples of the material constituting the core material include conductive materials and non-conductive materials. Examples of the conductive material include conductive non-metals such as metals, metal oxides, and graphite, and conductive polymers. Examples of the conductive polymer include polyacetylene. Examples of the nonconductive material include silica, alumina, and zirconia. Among them, metal is preferable because conductivity can be increased and connection resistance can be effectively reduced. The core substance is preferably metal particles.

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

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

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

  The “average diameter (average particle diameter)” of the core substance indicates a number average diameter (number average particle diameter). The average diameter of the core material is obtained by observing 50 arbitrary core materials with an electron microscope or an optical microscope and calculating an average value.

[Insulating material]
The conductive particles according to the present invention preferably include an insulating substance disposed on the surface of the conductive layer. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be further prevented. Specifically, when a plurality of conductive particles are in contact with each other, an insulating material is present between the plurality of electrodes, so that it is possible to prevent a short circuit between electrodes adjacent in the lateral direction instead of between the upper and lower electrodes. In addition, the insulating substance between the conductive layer of an electroconductive particle and an electrode can be easily excluded by pressurizing electroconductive particle with two electrodes in the case of the connection between electrodes. In the case where the conductive particles have a plurality of protrusions on the outer surface of the conductive layer, the insulating substance between the conductive layer and the electrode of the conductive particles can be more easily removed.

  The insulating substance is preferably an insulating particle because the insulating substance can be more easily removed when the electrodes are pressed.

  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 thermoplastic resins, heat Examples thereof include curable resins and water-soluble resins.

  Examples of the polyolefins include polyethylene, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. Examples of the (meth) acrylate polymer include polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate. Examples of the block 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. As said thermosetting resin, an epoxy resin, a phenol resin, a melamine resin, etc. are mentioned. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrrolidone, polyethylene oxide, and methyl cellulose. Of these, water-soluble resins are preferable, and polyvinyl alcohol is more preferable.

  Examples of a method for disposing an 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, and an emulsion polymerization method. Examples of the physical or mechanical method include spray drying, hybridization, electrostatic adhesion, spraying, dipping, and vacuum deposition. In particular, since the insulating substance is difficult to be detached, a method of disposing the insulating substance on the surface of the conductive layer through a chemical bond is preferable.

  The average diameter (average particle diameter) of the insulating material 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 diameter) of the insulating material is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 1 μm or less, more preferably 0.5 μm or less. When the average diameter of the insulating substance is not less than the above lower limit, the conductive layers in the plurality of conductive particles are difficult to contact 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 material between the electrodes and the conductive particles when the electrodes are connected, There is no need for heating.

  The “average diameter (average particle diameter)” of the insulating material indicates a number average diameter (number average particle diameter). The average diameter of the insulating material is determined using a particle size distribution measuring device or the like.

(Conductive material)
The conductive material according to the present invention includes the conductive particles described above and a binder resin. The conductive particles according to the present invention are preferably dispersed in a binder resin and used as a conductive material. The conductive material according to the present invention is preferably an anisotropic conductive material. The conductive material according to the present invention is preferably a circuit connection material.

  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. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

  Examples of the vinyl resin include vinyl acetate resin, acrylic resin, and styrene resin. Examples of the thermoplastic resin include polyolefin resins, ethylene-vinyl acetate copolymers, and polyamide resins. Examples of the curable resin include an epoxy resin, a urethane resin, a polyimide resin, and an unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene. -Hydrogenated product of a styrene block copolymer. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

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

  The method for dispersing the conductive particles in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. Examples of a method for dispersing the conductive particles in the binder resin include a method in which the conductive particles are added to the binder resin and then kneaded and dispersed with a planetary mixer or the like. The conductive particles are dispersed in water. Alternatively, after uniformly dispersing in an organic solvent using a homogenizer or the like, it is added to the binder resin, kneaded and dispersed with a planetary mixer or the like, and the binder resin is diluted with water or an organic solvent. Then, the method of adding the said electroconductive particle, kneading with a planetary mixer etc. and disperse | distributing is mentioned.

  The conductive material according to the present invention can be used as a conductive paste and a conductive film. When the conductive material according to the present invention is used as a film-like adhesive such as a conductive film, a film-like adhesive containing no conductive particles is added to the film-like adhesive containing the conductive particles. It may be laminated. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

  In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably 99.% or more. It is 99 weight% or less, More preferably, it is 99.9 weight% or less. When the content of the binder resin is not less than the above lower limit and not more than the above upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further increased.

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

(Connection structure)
A connection structure can be obtained by connecting the connection target members using the conductive particles of the present invention or using 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 is a conductive member of the present invention. It is preferable that the connection structure be formed of conductive particles or formed of a conductive material containing the conductive particles and a binder resin. In the case where conductive particles are used, the connection portion itself is conductive particles. That is, the first and second connection target members are connected by the conductive particles. The conductive material used for obtaining the connection structure is preferably an anisotropic conductive material.

  In FIG. 4, the connection structure using the electroconductive particle which concerns on the 1st Embodiment of this invention is typically shown with front sectional drawing.

  4 includes a first connection target member 52, a second connection target member 53, and a connection portion 54 that connects the first and second connection target members 52 and 53. Prepare. The connection part 54 is formed of a conductive material including the conductive particles 1. The connection portion 54 is preferably formed by curing a conductive material including the conductive particles 1. In FIG. 4, the conductive particles 1 are schematically shown for convenience of illustration.

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

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, the conductive material is disposed between the first connection target member and the second connection target member to obtain a laminate, and then the laminate is heated and pressurized. Methods and the like. The pressure of the said pressurization is about 9.8 * 10 < ⁴ > -4.9 * 10 < ⁶ > Pa. The temperature of the said heating is about 120-220 degreeC.

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

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

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

Example 1
Divinylbenzene copolymer resin particles having a particle size of 3.0 μm (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd.) were prepared.

  After dispersing 10 parts by weight of the resin particles in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the resin particles were taken out by filtering the solution. Next, the resin particles were added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the resin particles. The resin particles whose surface was activated were sufficiently washed with water, and then added to 500 parts by weight of distilled water and dispersed to obtain a suspension.

  Further, a nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane, 0.5 mol / L of sodium citrate and 0.23 mol / L of copper sulfate was prepared. While stirring the obtained suspension at 60 ° C., the above nickel plating solution was gradually added dropwise to the suspension, and an electroless nickel plating first stage step was performed.

  Subsequently, a nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane, 0.5 mol / L of sodium citrate and 2.3 mol / L of copper sulfate was prepared. This nickel plating solution was gradually added dropwise to the suspension in which the previous step was performed, and an electroless nickel plating middle step was performed.

  Subsequently, a nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.92 mol / L of dimethylamine borane, 0.5 mol / L of sodium citrate and 0.23 mol / L of copper sulfate was prepared. This nickel plating solution was gradually added dropwise to the suspension in which the intermediate process was performed, and the latter process of the electroless nickel plating was performed.

  By filtering the suspension, the particles were taken out, washed with water, and dried to obtain conductive particles in which a nickel-boron-copper conductive layer (thickness 0.1 μm) was disposed on the surface of the resin particles.

(Example 2)
In the nickel plating solution used in the latter stage of electroless nickel plating, a nickel-boron-copper conductive layer (thickness: 0.1 μm) is formed on the surface of the resin particles in the same manner as in Example 1 except that copper sulfate is not used. Arranged conductive particles were obtained.

( Reference Example 3)
In the nickel plating solution used in the first electroless nickel plating step, the copper sulfate concentration was changed from 0.23 mol / L to 0.46 mol / L, and in the nickel plating solution used in the middle step, the copper sulfate concentration was changed to 2. Nickel-boron was formed on the surface of the resin particles in the same manner as in Example 1 except that the copper plating was not used in the nickel plating solution used in the latter step, and changed from 3 mol / L to 1.2 mol / L. -The electroconductive particle in which the copper conductive layer (thickness 0.1 micrometer) was arrange | positioned was obtained.

Example 4
In the nickel plating solution used in the previous electroless nickel plating step, nickel was deposited on the surface of the resin particles in the same manner as in Example 1 except that the copper sulfate concentration was changed from 0.23 mol / L to 0.023 mol / L. -Conductive particles in which a boron-copper conductive layer (thickness 0.1 μm) was disposed were obtained.

(Example 5)
(1) Palladium adhesion process The divinylbenzene resin particle ("Micropearl SP-203" by Sekisui Chemical Co., Ltd.) whose particle diameter is 3.0 micrometers was prepared. The resin particles were etched and washed with water. Next, resin particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst and stirred. Then, it filtered and wash | cleaned. Resin particles were added to 0.5 wt% dimethylamine borane solution at pH 6 to obtain resin particles to which palladium was attached.

(2) Core substance adhesion step The resin particles to which palladium was adhered were stirred and dispersed in 300 mL of ion exchange water for 3 minutes to obtain a dispersion. Next, 1 g of metallic nickel particle slurry (average particle diameter 100 nm) was added to the dispersion over 3 minutes to obtain resin particles to which the core substance was adhered.

(3) Electroless nickel plating step In the same manner as in Example 1, conductive particles were obtained in which a nickel-boron-copper conductive layer (thickness 0.1 μm) was disposed on the surface of the resin particles.

(Example 6)
(1) Production of insulating particles A 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a condenser tube and a temperature probe was charged with 100 mmol methyl methacrylate and N, N, N-trimethyl. Ion-exchanged water containing a monomer composition containing 1 mmol of -N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride so that the solid content is 5% by weight. Then, the mixture was stirred at 200 rpm and polymerized at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, it was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle size of 220 nm, and a CV value of 10%.

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

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

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

(Example 7)
In each nickel plating solution used in the electroless nickel plating first-stage, middle-stage and later-stage processes, 0.23 mol / L of sodium hypophosphite was added and the pH was changed from 8.5 to 8.0. In the same manner as in Example 1, conductive particles in which a nickel-boron-phosphorus-copper conductive layer (thickness: 0.1 μm) was disposed on the surface of the resin particles were obtained.

(Example 8)
Resin particle surfaces in the same manner as in Example 1 except that 0.46 mol / L of sodium hypophosphite was added to each of the nickel plating solutions used in the electroless nickel plating first-stage, middle-stage and later-stage processes. Conductive particles having a nickel-boron-phosphorus-copper conductive layer (thickness 0.1 μm) disposed thereon were obtained.

(Comparative Example 1)
Conductives containing nickel and boron on the surface of the resin particles are the same as in Example 1 except that copper sulfate is not used in each of the nickel plating solutions used in the electroless nickel plating first-stage, middle-stage and later-stage processes. Conductive particles having a layer (thickness: 0.1 μm) were obtained.

(Comparative Example 2)
In the nickel plating solution used in the first stage of electroless nickel plating, the copper sulfate concentration was changed from 0.23 mol / L to 0.12 mol / L. In the nickel plating solution used in the middle stage of electroless nickel plating, The concentration was changed from 2.3 mol / L to 0.06 mol / L, and the concentration of copper sulfate was changed from 0.23 mol / L to 0.12 mol / L in the nickel plating solution used in the latter stage of electroless nickel plating. Except that, conductive particles in which a nickel-boron-copper conductive layer (thickness 0.1 μm) was arranged on the surface of the resin particles were obtained in the same manner as in Example 1.

(Comparative Example 3)
In the nickel plating solution used in the first step of electroless nickel plating, the concentration of copper sulfate was changed from 0.23 mol / L to 0.46 mol / L, and in the nickel plating solution used in the latter step, the concentration of copper sulfate was reduced to 0. Conductive particles in which a nickel-boron-copper conductive layer (thickness 0.1 μm) is disposed on the surface of the resin particles in the same manner as in Example 1 except that the amount is changed from 2.3 mol / L to 2.3 mol / L. Got.

(Evaluation)
(1) Content of nickel, boron, phosphorus and copper in 100% by weight of the entire conductive layer X Add 5 g of conductive particles to a mixed solution of 5 mL of 60% nitric acid and 10 mL of 37% hydrochloric acid to complete the conductive layer. To obtain a solution. Using the obtained solution, the contents of nickel, boron, phosphorus and copper were analyzed with an ICP emission analyzer (“ULTIMA2” manufactured by Horiba, Ltd.). The conductive layers in the conductive particles of Examples 1 and 2, Reference Example 3, and Examples 4 to 6 did not contain phosphorus.

(2) The entire region R1 on the outer surface side of the conductive layer thickness 1/3, the entire region R2 in the center of the conductive layer thickness 1/3, and the entire region R3 on the inner surface side of the conductive layer thickness 1/3. Each content of nickel, boron, phosphorus and copper The entire region R1 on the outer surface side of the conductive layer thickness 1/3, the entire region R2 in the center of the conductive layer thickness 1/3, the thickness of the conductive layer 1/3 Each content of nickel, boron, phosphorus, and copper in the entire region R3 on the surface side was performed by FE-TEM / EDX analysis (“JEM-ARM200F” manufactured by JEOL).

  Conductive particles were dispersed in an epoxy resin, the particles were cut with a focused ion beam (“SMI-2050” manufactured by Seiko Instruments Inc.), and the cross section was observed with a scanning electron microscope. Each content of nickel, boron, phosphorus and copper was measured by energy dispersive X-ray analysis.

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

(4) Plating state The plating state of 50 conductive particles obtained was observed with a scanning electron microscope ("JSM-6060" manufactured by JEOL). The presence or absence of plating unevenness such as plating cracking or plating peeling was observed. The plating state was determined according to the following criteria.

[Criteria for plating state]
○: 4 or less conductive particles in which uneven plating was confirmed ×: 5 or more conductive particles in which uneven plating was confirmed

(5) Aggregation state 1
10 parts by weight of bisphenol A type epoxy resin (“Epicoat 1009” manufactured by Mitsubishi Chemical Corporation), 40 parts by weight of acrylic rubber (weight average molecular weight of about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent (Asahi Kasei Chemicals) "HX3941HP" manufactured by HX3941) and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed, and the conductive particles are added so that the content is 3% by weight. An anisotropic conductive material was obtained by dispersing.

  The obtained anisotropic conductive material was stored at 25 ° C. for 72 hours. After storage, it was evaluated whether or not the conductive particles aggregated in the anisotropic conductive material were settled. Aggregation state 1 was determined according to the following criteria.

[Criteria for Aggregation State 1]
○○: Aggregated conductive particles are not settled ○: Small aggregated conductive particles are slightly settled ×: Many aggregated conductive particles are settled

(6) Aggregation state 2
10 parts by weight of bisphenol A type epoxy resin (“Epicoat 1009” manufactured by Mitsubishi Chemical Corporation), 40 parts by weight of acrylic rubber (weight average molecular weight of about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent (Asahi Kasei Chemicals) "HX3941HP" manufactured by HX3941) and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed, and the conductive particles are added so that the content is 3% by weight. An anisotropic conductive material was obtained by dispersing.

  Using the obtained anisotropic conductive material, an anisotropic conductive film (thickness 35 μm) was produced. The obtained anisotropic conductive film was stored at 25 ° C. for 72 hours. The aggregation state of the conductive particles in 10 fields of view was evaluated with an optical microscope at a magnification of 100 times. Aggregation state 2 was determined according to the following criteria.

[Criteria for Aggregation State 2]
○: No more than 3 aggregates ○: 1-10 aggregates of 3 or more Δ: 11-20 aggregates of 3 or more ×: 21 aggregates of 3 or more Existence

(7) Connection resistance Fabrication of connection structure:
10 parts by weight of bisphenol A type epoxy resin (“Epicoat 1009” manufactured by Mitsubishi Chemical Corporation), 40 parts by weight of acrylic rubber (weight average molecular weight of about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent (Asahi Kasei Chemicals) "HX3941HP" manufactured by HX3941) and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Toray Dow Corning Silicone Co., Ltd.) are mixed, and the conductive particles are added so that the content is 3% by weight. A resin composition was obtained by dispersing.

  The obtained resin composition was applied to a 50 μm-thick PET (polyethylene terephthalate) film whose one surface was released from the mold, and dried with hot air at 70 ° C. for 5 minutes to produce an anisotropic conductive film. The thickness of the obtained anisotropic conductive film was 12 μm.

  The obtained anisotropic conductive film was cut into a size of 5 mm × 5 mm. The cut anisotropic conductive film is formed of a glass substrate (width 3 cm, length 3 cm) having an aluminum electrode (height 0.2 μm, L / S = 20 μm / 20 μm) having a lead wire for resistance measurement on one side. Affixed almost at the center on the aluminum electrode side. Next, a two-layer flexible printed board (width 2 cm, length 1 cm) having the same aluminum electrode was bonded after being aligned so that the electrodes overlap each other. The laminated body of this glass substrate and the two-layer flexible printed board was thermocompression bonded under pressure bonding conditions of 10 N, 180 ° C., and 20 seconds to obtain a connection structure. A two-layer flexible printed board in which an aluminum electrode is directly formed on a polyimide film was used.

Connection resistance measurement:
The connection resistance between the opposing electrodes in the obtained connection structure was measured by a four-terminal method. The connection resistance was evaluated according to the following evaluation criteria.

[Evaluation criteria for connection resistance]
○○○: Connection resistance is 2.0Ω or less ○○: Connection resistance is over 2.0Ω, 3.0Ω or less ○: Connection resistance is over 3.0Ω, 5.0Ω or less Δ: Connection resistance is 5.0Ω Exceeding 10Ω ×: Connection resistance exceeds 10Ω

(8) Impact resistance Impact resistance was evaluated by dropping the connection structure obtained in the above (7) evaluation of connection resistance from a position of 70 cm in height onto a concrete floor and confirming conduction. Impact resistance was determined according to the following criteria.

○: Increase rate of resistance value from initial resistance value is 50% or less ×: Increase rate of resistance value from initial resistance value exceeds 50%

(9) Migration resistance The connection structure produced in the above (7) evaluation of connection resistance was left under conditions of 85 ° C. and relative humidity of 85%. A tester was used to determine whether or not there were leaks in 20 adjacent electrodes 500 hours and 1000 hours after the start of standing. Migration resistance was determined according to the following criteria. In addition, if the evaluation result after 500 hours is “◯”, it can be said that the migration resistance is high, but the evaluation result after 1000 hours is also “◯” in order to considerably improve the resistance to microphones. It is preferable.

[Judgment criteria for migration resistance]
○: No leak occurred ×: Leak occurred

(10) Adhesiveness between base particles and conductive layer 1.0 g of the obtained conductive particles, 45 g of zirconia balls having a diameter of 1 mm, and 17 g of toluene were placed in a 200 mL beaker. The mixture was stirred at 400 rpm for 6 minutes using a three-one motor stirrer. After stirring, the conductive particles and zirconia balls were separated. 1000 conductive particles were observed with a scanning electron microscope, and the adhesion between the substrate particles and the conductive layer was determined according to the following criteria.

[Judgment criteria for adhesion between substrate particles and conductive layer]
○: Less than 10 conductive particles in which 1000 conductive particles are peeled. Δ: 10 or more conductive particles in which 1000 conductive particles are peeled. 50 Less than x: 50 or more conductive particles with peeling of the conductive layer in 1000 conductive particles

  The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 1a ... Protrusion 2 ... Base material particle 3 ... Conductive layer 3a ... Protrusion 4 ... Core substance 5 ... Insulating substance 11 ... Conductive particle 11a ... Protrusion 12 ... 2nd conductive layer 13 ... Conductive layer 13a ... Projection 21 ... Conductive particle 22 ... Conductive layer 51 ... Connection structure 52 ... First connection object member 52a ... Surface 52b ... First electrode 53 ... Second connection object member 53a ... Surface 53b ... Second electrode 54 ... Connection portion R1: Region on the outer surface side of the conductive layer thickness 1/3 R2: Region in the center of the conductive layer thickness 1/3 R3: Region on the inner surface side of the conductive layer thickness 1/3

Claims (15)

A conductive layer that is disposed on the surface of the base particle, nickel, at least one of boron and phosphorus, and copper;
The conductive layer has a single layer structure,
The copper content in the entire region on the outer surface side of the conductive layer thickness 1/3 is the central region of the conductive layer thickness 1/3 and the inner surface region of the conductive layer thickness 1/3. DOO rather less than the content of copper in the entire area of thickness 2/3 including,
Conductive particle | grains with more copper content in the whole center area | region of the thickness 1/3 of the said conductive layer than copper content in the whole area | region of the inner surface side of the thickness 1/3 of the said conductive layer .   The content of nickel in the entire region on the outer surface side of the conductive layer thickness 1/3 is the central region of the conductive layer thickness 1/3 and the region on the inner surface side of the conductive layer thickness 1/3. The conductive particle according to claim 1, wherein the content of nickel is larger than the content of nickel in the entire region of a thickness of 2/3 including:   The copper content in the entire region on the outer surface side of the conductive layer thickness ３ is less than the copper content in the entire central region of the conductive layer thickness ３. 2. Conductive particles according to 2.   The nickel content in the entire region on the outer surface side of the conductive layer thickness ３ is larger than the nickel content in the entire central region of the conductive layer thickness １ ／. 4. The conductive particle according to any one of 3 above. The nickel content in the entire region on the inner surface side of the thickness 1/3 of the conductive layer is larger than the nickel content in the entire central region of the thickness 1/3 of the conductive layer. 5. The conductive particle according to any one of 4 above. The nickel content is 49% by weight or more and 99% by weight or less and the copper content is 0.1% by weight or more and 50% by weight or less in the entire region on the outer surface side of the thickness 1/3 of the conductive layer. The electroconductive particle of any one of Claims 1-5 which is. The nickel content in the entire region of 2/3 thickness including the central region of the conductive layer thickness 1/3 and the inner surface side region of the conductive layer thickness 1/3 is 29% by weight or more, 89 The electroconductive particle of any one of Claims 1-6 which is weight% or less and whose copper content is 10 weight% or more and 75 weight% or less. The nickel content is 1 wt% or more and 79 wt% or less and the copper content is 20 wt% or more and 98 wt% or less in the entire central region of the thickness 1/3 of the conductive layer, Item 8. The conductive particle according to any one of Items 1 to 7 . In the entire region on the inner surface side of the thickness 1/3 of the conductive layer, the nickel content is 49 wt% or more and 99 wt% or less, and the copper content is 0.1 wt% or more and 50 wt% or less. The electroconductive particle of any one of Claims 1-8 which is these. Wherein the conductive layer comprises nickel and boron and copper, and the conductive layer comprises or phosphorus-free, electrically conductive particles according to any one of claims 1-9. Wherein wherein the conductive layer of boron, and the content of boron total of 100 wt% of the conductive layer is 0.05 wt% or more and 4 wt% or less, according to any one of claims 1-10 Conductive particles. The conductive layer has a protrusion on the outer surface, the conductive particles according to any one of claims 1 to 11. 13. The conductive layer according to any one of claims 1 to 12 , wherein the conductive layer does not contain phosphorus or contains phosphorus, and the content of phosphorus in 100% by weight of the entire conductive layer is less than 0.5% by weight. Conductive particles. And conductive particles according to any one of claims 1 to 13 and a binder resin, conductive material. A first connection target member;
A second connection target member;
A connection portion connecting the first connection target member and the second connection target member;
A connection structure in which the connection portion is formed of the conductive particles according to any one of claims 1 to 13 , or is formed of a conductive material including the conductive particles and a binder resin.

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