JP2013254733A - Conductive particle, conductive material, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle which inhibits the condensation, and to provide a connection structure using the conductive particles.SOLUTION: A conductive particle 1 according to this invention includes: a base material particle 2; and a conductive layer 3 disposed on a surface of the base material particle 2. The conductive layer 3 includes at least one of nickel, boron, and phosphorus and copper. A connection structure 51 according to this invention includes: a first connection object member 52; a second connection object member 53; and a connection part 54 connecting the first connection object member 52 with the second connection object member 53. The connection part 54 is formed by the conductive particles 1 or a conductive material including the conductive particles 1.

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.

JP 2000-243132 A

  In the conventional conductive particles as described in Patent Document 1, 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 objective of this invention is providing the electroconductive material and connection structure using the electroconductive particle which can suppress aggregation, and this electroconductive particle.

  The limited object of the present invention is to suppress the aggregation and further reduce the connection resistance between the electrodes when used for the connection between the electrodes, and a conductive material using the conductive particles and It is to provide a connection structure.

  According to a wide aspect of the present invention, the substrate has a base particle and a conductive layer disposed on the surface of the base particle, and the conductive layer includes nickel and at least one of boron and phosphorus. Conductive particles comprising copper are provided.

  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.

  The total content of nickel and copper in 100% by weight of the conductive layer is preferably 61% by weight or more. The total content of nickel and copper in 100% by weight of the conductive layer is preferably 99.95% by weight or less.

  In 100% by weight of the conductive layer, the copper content is preferably 0.5% by weight or more. In 100% by weight of the conductive layer, the nickel content is preferably 10% by weight or more.

  The conductive layer preferably contains boron, and the boron content in 100% by weight of the conductive layer is preferably 0.05% by weight or more and 4% by weight or less.

  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.

  On the specific situation with the electroconductive particle which concerns on this invention, the said conductive layer does not contain phosphorus or contains, and content of phosphorus in 100 weight% of said conductive layers is less than 0.5 weight%.

  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, the first connection target member, the second connection target member, the connection portion connecting the first connection target member, and the second connection target member; There is provided a connection structure in which the connection part 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, so that the plurality of conductive particles aggregate. Can be suppressed.

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.

  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.

  For example, the surface of the conductive layer containing nickel and boron has high magnetism, and when the upper and lower electrodes are electrically connected, they are adjacent to each other in the lateral direction that should not be connected due to the influence of the conductive particles aggregated by the magnetism. There is a tendency that the electrodes are easily connected. 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.

  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 conductive layer 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. However, the connection resistance between the electrodes tends to be high. 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 conductive layer is 0.5% by weight or more, the connection resistance tends to increase.

  On the other hand, when the thickness of the conductive layer containing nickel and phosphorus is increased in order to reduce the connection resistance between the electrodes, 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. The conductive layer may contain 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 contains nickel, boron, and copper. The conductive layer 3 contains nickel, at least one of boron and phosphorus, 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. In the conductive particles 11, the second conductive layer 12 does not correspond to a conductive layer containing nickel, at least one of boron and phosphorus, and copper.

  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 second conductive layer 12 has a plurality of protrusions on the outer surface. 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 conductive surface. The conductive particles 21 are spherical. The conductive layer 22 has no protrusion on the outer surface. Thus, the electroconductive particle which concerns on this invention does not need to have a processus | protrusion on the electroconductive surface, 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.

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particle may be a core-shell particle including a core and a shell disposed on the surface of the core. 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 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; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether ether Tons, polyethersulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. 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 di (meth) acrylate, 1,4-butanediol di (meth) acrylate; triallyl (iso) cyanurate, tria Rutorimeriteto, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, .gamma. (meth) acryloxy propyl trimethoxy silane, trimethoxy silyl styrene, include silane-containing monomers such as vinyltrimethoxysilane.

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, 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. Although it does not specifically limit as the particle | grains formed with the said silica, For example, after hydrolyzing the silicon compound which has two or more hydrolysable alkoxysil groups, and forming a crosslinked polymer particle, it calcinates as needed. 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 it becomes difficult to form the aggregated conductive particles. 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.

[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 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 content of nickel in 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, and particularly preferably 90% by weight. % Or more. The content of nickel in the conductive layer X 100% by weight 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 the 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 or a conductive layer, there exists a tendency for the connection resistance between electrodes to become low, so that there is much content of the said nickel.

  The total content of boron and phosphorus 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 or less, more preferably 4% by weight or less, further 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 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 reduced. It can be made even lower. 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 boron content in 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 or less. It is preferably 4% by weight or less, 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 at least the above lower limit, the conductive layer 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. Can do. 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 conductive layer is less than 0.5% by weight. The content of phosphorus in 100% by weight of the conductive layer 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 copper content in 100% by weight of the conductive layer X is preferably 0.5% by weight or more, more preferably 1% by weight or more, still more preferably more than 5% by weight, and particularly preferably 10% by weight or more. When the copper content is at least the above lower limit, the hardness of the outer surface of the conductive layer is further increased. For this reason, when the oxide film is formed on the surface of the electrode or the conductive layer, the oxide film on the surface of the electrode and the conductive particles can be effectively eliminated, the connection resistance can be lowered, and the obtained connection The impact resistance of the structure can be increased. Furthermore, when the copper content is not less than the above lower limit, the magnetism of the outer surface of the conductive layer becomes weak and the plurality of conductive particles are difficult to aggregate. For this reason, the short circuit between electrodes can be suppressed effectively. The copper content in 100% by weight of the conductive layer X may be 0.01% by weight or more, or 0.2% by weight or more. The upper limit of the content of the copper in the conductive layer X100% by weight can be appropriately changed depending on the contents of nickel, boron and phosphorus. The copper content in 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.

  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 the conductive layer X 100% by weight is preferably 51% by weight or more. More preferably, it is 61% by weight or more, further preferably 71% by weight or more, and particularly preferably 91% by weight or more. The total content of nickel and copper in the conductive layer X 100% by weight may be 98% by weight or more, 98.5% by weight or more, or 99% by weight or more. The total content of nickel and copper in 100% by weight of the 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, ICP-MS analyzers manufactured by Hitachi, Ltd., and the like.

  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 conductive layer preferably contains nickel.

  A method for forming a conductive layer (another conductive layer and conductive layer X) on the surface of the base 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 upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrode is sufficiently large, and the conductive layer is formed. Aggregated conductive particles are less likely to be formed during formation. 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 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.

  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 the method for forming the protrusions, a core material is attached to the surface of the base particle, and then a conductive layer is formed by electroless plating, and a conductive layer is formed on the surface of the base particle by electroless plating. Thereafter, a method of attaching a core substance and further forming a conductive layer by electroless plating may be used. As another method for forming the protrusion, an inner conductive layer is formed on the surface of the base particle, and then a core substance is disposed on the inner conductive layer, and then an outer conductive layer is formed. Examples thereof include a method and a method of adding a core substance in the course of forming a conductive layer 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. The conductive particles may have a second conductive layer on the surface of the base particle, and may have a conductive layer X on the second conductive layer.

  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 of the conductive particles and the electrode can be easily excluded.

  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 particles and the conductive material are each preferably used for electrical connection between electrodes. The conductive material is preferably an anisotropic conductive 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 and kneaded 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 a conductive film, a film that does not include conductive particles may be laminated on a conductive film that includes conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

  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. The connection structure is preferably formed of conductive particles or formed of a conductive material (such as an anisotropic 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.

  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 portion 54 is 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. Instead of the conductive particles 1, conductive particles 11, 21 and the like may be used.

  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 connection object member is preferably an electronic component.

  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 0.0023 mol / L of copper sulfate was prepared.

  While stirring the obtained suspension at 60 ° C., the nickel plating solution was gradually added dropwise to the suspension to perform electroless nickel plating. Thereafter, by filtering the suspension, the particles are taken out, washed with water, and dried to obtain conductive particles in which a nickel-boron-copper conductive layer (thickness 0.1 μm) is disposed on the surface of the resin particles. It was.

(Example 2)
Conductive particles in which a nickel-boron-copper conductive layer (thickness: 0.1 μm) is disposed on the surface of the resin particles are the same as in Example 1 except that the copper sulfate concentration is changed to 0.11 mol / L. Obtained.

(Example 3)
(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 4
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 3 except that the copper sulfate (pentahydrate) concentration is changed to 0.11 mol / L. Conductive particles were obtained.

(Example 5)
(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 4 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 6)
Conductive particles in which a nickel-boron-copper conductive layer (thickness: 0.1 μm) is arranged on the surface of the resin particles are the same as in Example 1 except that the copper sulfate concentration is changed to 0.0011 mol / L. Obtained.

(Example 7)
A nickel-boron-copper-tungsten conductive layer (on the surface of the resin particles (except that the copper sulfate concentration was changed to 0.05 mol / L and sodium tungstate 0.5 mol / L was added) was formed in the same manner as in Example 1. Conductive particles having a thickness of 0.1 μm were obtained.

(Example 8)
Conductive particles in which a nickel-boron-copper conductive layer (thickness: 0.1 μm) is disposed on the surface of the resin particles are the same as in Example 1 except that the copper sulfate concentration is changed to 0.22 mol / L. Obtained.

Example 9
Conductivity in which a nickel-boron-phosphorus-copper conductive layer (thickness 0.1 μm) was disposed on the surface of the resin particles in the same manner as in Example 1 except that sodium hypophosphite 0.92 mol / L was added. Sex particles were obtained.

(Example 10)
A nickel-phosphorus-copper conductive layer (thickness 0. 0) was formed on the surface of the resin particles in the same manner as in Example 1 except that dimethylamine borane 0.92 mol / L was changed to sodium hypophosphite 0.92 mol / L. 1 [mu] m) was obtained.

(Example 11)
The surface of divinylbenzene copolymer resin particles (“Micropearl SP-203” manufactured by Sekisui Chemical Co., Ltd.) having a particle diameter of 3.0 μm was coated with an inorganic shell (thickness 250 nm) using a condensation reaction by sol-gel reaction. Core-shell type organic-inorganic hybrid particles (base material particles) were prepared.

  Conductivity in which a nickel-boron-copper conductive layer (thickness: 0.1 μm) is disposed on the surface of the organic-inorganic hybrid particle in the same manner as in Example 1 except that the resin particle is changed to the organic-inorganic hybrid particle. Particles were obtained.

(Comparative Example 1)
Conductive particles in which a conductive layer (thickness 0.1 μm) containing nickel and boron is disposed on the surface of the resin particles are obtained in the same manner as in Example 1 except that copper sulfate in the nickel plating solution is not used. It was.

(Comparative Example 2)
Conductive particles in which a conductive layer (thickness 0.1 μm) containing nickel and phosphorus is disposed on the surface of the resin particles are obtained in the same manner as in Example 10 except that copper sulfate in the nickel plating solution is not used. It was.

(Comparative Example 3)
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 copper plating solution (pH 12.5) containing 0.23 mol / L of copper sulfate, 2.3 mol / L of ethylenediaminetetraacetate, and 0.5 mol / L of formalin was prepared.

  While stirring the obtained suspension at 60 ° C., the copper plating solution was gradually added dropwise to the suspension to perform electroless copper plating. Thereafter, by filtering the suspension, the particles were taken out, washed with water, and dried to obtain conductive particles in which a copper conductive layer (thickness: 0.1 μm) was disposed on the surface of the resin particles.

(Evaluation)
(1) Content of nickel, boron, phosphorus and copper in 100% by weight of conductive layer X 5% of conductive particles are added to a mixture of 5 mL of 60% nitric acid and 10 mL of 37% hydrochloric acid to completely dissolve the conductive layer, A solution was obtained. Using the obtained solution, the contents of nickel, boron, phosphorus and copper were analyzed with an ICP emission analyzer (ULTIMA2 manufactured by HORIBA). In addition, the electroconductive layer in the electroconductive particle of Examples 1-8, 11 and Comparative Examples 1 and 3 did not contain phosphorus.

(2) 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).

(3) Plating state The plating state of 50 conductive particles obtained was observed with a scanning electron microscope. The presence or absence of plating unevenness such as plating cracking or plating peeling was observed. The case where the number of conductive particles in which plating unevenness was confirmed was 4 or less was judged as “good”, and the case where the number of conductive particles in which plating unevenness was confirmed was 5 or more was judged as “bad”.

(4) the aggregate state obtained conductive particles so that the particle concentration 100 × ^{10 3} ~500 × ¹⁰ 3 cells / mL, was adjusted with sheath fluid (Sysmex Corporation). About the slurry liquid after adjustment, it measured by the count number 5000-10000 in the state which attached the stirrer chip | tip with the electrical resistance type particle size distribution measuring apparatus (SD-2000 by Sysmex). From the obtained particle size distribution, the large particle ratio was determined using the center of the valley of the main peak and the connected peak as the large particle threshold. The aggregation state was determined according to the following criteria.
[Judgment criteria for aggregation state]
◯: Large particle ratio is 10% or less ○: Large particle ratio exceeds 10%, 20% or less △: Large particle ratio exceeds 20%, 30% or less ×: Large particle ratio exceeds 30%

(5) 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 the glass substrate and the two-layer flexible printed circuit 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

(6) Impact resistance The impact structure was evaluated by dropping the connection structure obtained in the above (5) connection resistance evaluation from a position of 70 cm in height and confirming conduction. The case where the rate of increase in resistance value from the initial resistance value was 50% or less was determined as “good”, and the case where the rate of increase in resistance value from the initial resistance value exceeded 50% was determined as “bad”.

  The results are shown in Tables 1 and 2 below. In the evaluation of the aggregation state, the large particle ratio in Example 8 was smaller than the large particle ratio in Examples 2, 4, 5, and 7.

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

Claims (11)

Having base particles and a conductive layer disposed on the surface of the base particles;
The conductive particle in which the conductive layer contains nickel, at least one of boron and phosphorus, and copper.   The conductive particle according to claim 1, wherein the conductive layer includes nickel, boron, and copper, and the conductive layer does not include or includes phosphorus.   The electroconductive particle of Claim 1 or 2 whose total content of nickel and copper in the said conductive layer 100 weight% is 61 weight% or more.   4. The conductive particle according to claim 1, wherein the total content of nickel and copper in 100% by weight of the conductive layer is 99.95% by weight or less.   The electroconductive particle of any one of Claims 1-4 whose copper content is 0.5 weight% or more in the said conductive layer 100 weight%.   The electroconductive particle of any one of Claims 1-5 whose content of nickel is 10 weight% or more in 100 weight% of said conductive layers. The conductive layer includes boron;
The electroconductive particle of any one of Claims 1-6 whose content of boron in the said conductive layer 100weight% is 0.05 weight% or more and 4 weight% or less.   The electroconductive particle of any one of Claims 1-7 in which the said electroconductive layer has a processus | protrusion on an outer surface.   The conductive layer according to any one of claims 1 to 8, wherein the conductive layer does not contain phosphorus or contains phosphorus, and the content of phosphorus in 100% by weight of the conductive layer is less than 0.5% by weight. Sex particles.   The electroconductive material containing the electroconductive particle of any one of Claims 1-9, and binder resin. A first connection target member;
A second connection target member;
A connecting portion connecting the first connection target member and the second connection target member;
The connection structure in which the connection part is formed of the conductive particles according to any one of claims 1 to 9, or is formed of a conductive material including the conductive particles and a binder resin.

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