JP2014026971A - Conductive particle, conductive material, and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle which can reduce connection resistance when connecting between electrodes, and a conductive material using the conductive particle.SOLUTION: A conductive particle 1 includes a substrate particle 2 and a conductive layer 3 which is arranged on the surface of the substrate particle 2 so as to be in contact with the substrate particle 2. The substrate particle 2 and the conductive layer 3 are chemically bonded to each other through a pyrrolidone group. The conductive particle 1 has a compressive elasticity modulus, when compressed by 30%, of not less than 1,500 N/mmand not more than 8,000 N/mm, and a compression recovery rate of not less than 20% and not more than 90%. A conductive material comprises the conductive particle 1 and a binder resin.

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, Patent Document 1 below discloses conductive fine particles having resin fine particles and a metal coating layer formed on the surface of the resin fine particles. The resin fine particles include core material fine particles and a resin coating layer formed on the surface of the core material fine particles. The resin coating layer has a functional group having a binding ability with metal ions. Examples of the functional group capable of binding to the metal ion include a sulfone group, a carboxyl group, an amino group, an ammonium group, and a phosphate group.

  Patent Document 2 below discloses conductive particles in which a metal film is formed on the surface of non-conductive particles by electroless plating. Here, the electroless plating is performed after a pretreatment for attaching metal nuclei to the surface of non-conductive particles, and a metal film is formed of silver in the presence of a hydrophilic polymer having a pyrrolidone group. It is described.

JP 2003-208813 A WO2010 / 035708A1

  In the conventional conductive particles as described in Patent Document 1, the adhesion between the resin fine particles and the metal coating layer may be low. For this reason, when the connection structure is obtained by electrically connecting the electrodes via the conductive particles, the metal coating layer may be peeled off from the resin fine particles due to pressurization at the time of connection, etc. Large cracks occur in the layer. For this reason, there is a problem that a connection failure between electrodes occurs or a connection resistance increases. Even the conductive particles described in Patent Document 2 have problems in that poor connection between electrodes occurs or the connection resistance increases.

  An object of the present invention is to provide conductive particles that can reduce connection resistance when electrodes are connected, and a conductive material and a connection structure using the conductive particles.

According to a wide aspect of the present invention, the substrate particle and a conductive layer disposed on the surface of the substrate particle so as to be in contact with the substrate particle, the substrate particle and the conductive layer are provided. , Pyrrolidone group is chemically bonded, the compression elastic modulus when compressed 30% is 1500 N / mm ² or more and 8000 N / mm ² or less, and the compression recovery rate is 20% or more and 90% or less Certain conductive particles are provided.

  In a specific aspect of the conductive particle according to the present invention, the conductive particle is obtained by disposing the conductive layer on the surface of the base particle having a pyrrolidone group on the surface.

  In a specific aspect of the conductive particle according to the present invention, the base particle is obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or the base particle is It can be obtained by performing a polymerization reaction using a polymerizable compound having a pyrrolidone group, or the substrate particles can be obtained by surface-treating the substrate particle body with a compound having a pyrrolidone group.

  It is preferable that the base particle is obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or using a polymerizable compound having a pyrrolidone group. It is also preferable that the base particle is obtained by surface-treating the base particle body with a compound having a pyrrolidone group.

  On the specific situation with the electroconductive particle which concerns on this invention, the said conductive layer which contact | connects the said base particle contains 50 weight% or more of nickel in 100 weight% of said conductive layers.

  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 particle according to the present invention, a conductive layer is disposed on the surface of the base particle so as to be in contact with the base particle, and the base particle and the conductive layer are chemically bonded via a pyrrolidone group. Therefore, the compression elastic modulus when the conductive particles are further compressed by 30% is 1500 N / mm ² or more and 8000 N / mm ² or less, and the compression recovery rate of the conductive particles is 20% or more and 90% or less. Therefore, when the electrodes are connected using the conductive particles according to the present invention, the connection resistance can be lowered.

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.

(Conductive particles)
The conductive particles according to the present invention include base particles and a conductive layer disposed on the surface of the base particles so as to be in contact with the base particles. The substrate particles and the conductive layer are bonded via a pyrrolidone group. In the conductive particles according to the present invention, the compression elastic modulus when compressed by 30% is 1500 N / mm ² or more and 8000 N / mm ² or less. In the conductive particles according to the present invention, the compression recovery rate is 20% or more and 90% or less.

  By adopting the above-described configuration of the conductive particles according to the present invention, the adhesion between the substrate particles and the conductive layer is considerably increased. For this reason, peeling with a base material particle and a conductive layer and the floating from the surface of the base material particle of a conductive layer become difficult to produce. As a result, when the connection structure is obtained by connecting the electrodes using the conductive particles according to the present invention, the connection failure between the electrodes hardly occurs, and the connection resistance between the electrodes is effectively reduced. be able to.

  It is preferable that the electroconductive particle which concerns on this invention is obtained by arrange | positioning the said electroconductive layer on the surface of the base particle which has a pyrrolidone group on the surface. In the conductive particles thus obtained, the base particles and the conductive layer can be easily chemically bonded via pyrrolidone groups.

  Since the pyrrolidone group can be easily introduced onto the surface of the base particle, the conductive particle according to the present invention uses a polymerizable compound and a compound having a pyrrolidone group to perform a polymerization reaction. Or the base material particle is obtained by performing a polymerization reaction using a polymerizable compound having a pyrrolidone group, or the base material particle is a base material particle main body. It is preferably obtained by surface treatment with a compound having a group.

  The base particles are preferably obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or using a polymerizable compound having a pyrrolidone group. In this case, pyrrolidone groups can be uniformly present on the entire surface of the substrate particles, and further pyrrolidone groups can be present inside the substrate particles. The substrate particles are preferably obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group. The substrate particles are preferably obtained by performing a polymerization reaction using a polymerizable compound having a pyrrolidone group.

  It is also preferable that the base particle is obtained by surface-treating the base particle body with a compound having a pyrrolidone group. In this case, pyrrolidone groups can be selectively present on the surface of the substrate particles. In addition, by adjusting the surface treatment amount with the compound having a pyrrolidone group, the amount of pyrrolidone groups present on the surface of the base particle can be adjusted, and the amount of pyrrolidone groups can be easily increased. The base particle body is a base particle before surface treatment.

In order to reduce the connection resistance and increase the connection reliability between the electrodes, the compression elastic modulus (30% K value) when the conductive particles are compressed by 30% is 1500 N / mm ² or more and 8000 N / mm ² or less. is there. From the viewpoint of further reducing the connection resistance and further improving the connection reliability between the electrodes, the compression elastic modulus (30% K value) when the conductive particles are compressed by 30% is preferably 3000 N / mm ² or more. , Preferably 7000 N / mm ² or less.

  The compression elastic modulus (30% 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 30% compressively deformed (N)
S: Compression displacement (mm) when conductive particles are 30% compressed and deformed
R: radius of conductive particles (mm)

  In order to reduce the connection resistance, the compression recovery rate of the conductive particles is 20% or more and 90% or less. From the viewpoint of further reducing the connection resistance, the compression recovery rate of the conductive particles is preferably 50% or more, and preferably 80% or less.

  The compression recovery rate can be measured as follows.

  Spread conductive particles on the sample stage. With respect to one dispersed conductive particle, a load (reversal load value) is applied to the central direction of the conductive particle at 25 ° C. until the conductive particle is compressed and deformed by 30% at 25 ° C. Thereafter, unloading is performed up to the origin load value (0.40 mN). The load-compression displacement during this period is measured, and the compression recovery rate can be obtained from the following equation. The load speed is 0.33 mN / sec. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

Compression recovery rate (%) = [(L1-L2) / L1] × 100
L1: Compression displacement from the load value for origin to the reverse load value when applying a load L2: Unloading displacement from the reverse load value to the load value for origin when releasing the load

  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 so as to be in contact with the base particle 2. The conductive layer 3 is in contact with the base particle 2. The base particle 2 and the conductive layer 3 are chemically bonded via a pyrrolidone group. 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 base particle 2 may be obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or by performing a polymerization reaction using a polymerizable compound having a pyrrolidone group. It may be obtained, and may further be obtained by surface-treating the base particle body with a compound having a pyrrolidone group.

  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.

  A conductive particle 11 shown in FIG. 2 includes a base particle 2, a first conductive layer 12, a second conductive layer 13, a plurality of core substances 4, and a plurality of insulating substances 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 first conductive layer 12 and second conductive layer 13 formed. Yes.

  The first conductive layer 12 is disposed on the surface of the base particle 2 so as to be in contact with the base particle 2. The first conductive layer 12 is disposed between the base particle 2 and the second conductive layer 13. The first conductive layer 12 is a conductive layer in contact with the base particle 2. Therefore, the first conductive layer 12 is disposed on the surface of the base particle 2, and the second conductive layer 13 is disposed on the surface of the first conductive layer 12. The base particle 2 and the first conductive layer 12 are chemically bonded via a pyrrolidone group. The second 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 so as to be in contact with the base particle 2. The base particle 2 and the conductive layer 22 are chemically bonded via a pyrrolidone group.

  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.

  Moreover, the said compression elastic modulus (30% K value) and the said compression recovery factor of the electroconductive particle 1,11,21 are in the range mentioned above.

[Base material particles]
Examples of the substrate particles and the substrate particle main body include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The base particle (base particle main body) may be a core-shell particle. Especially, it is preferable that the said base particle (base particle main body) is a base particle (base particle main body) except a metal particle, and is an inorganic particle or organic-inorganic hybrid particle except a resin particle, a metal particle. It is more preferable.

  The base particle and the base particle body 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 and the substrate particle main body 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. By polymerizing one or more of various polymerizable monomers having an ethylenically unsaturated group, it is possible to design and synthesize resin particles having any compression property suitable for a conductive material.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and a crosslinkable monomer. And so on.

  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 this polymerization, a polymerizable compound having a pyrrolidone group may be used, or a polymerizable compound and a compound having a pyrrolidone group may be used. The base particles are preferably obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or using a polymerizable compound having a pyrrolidone group. The compound having a pyrrolidone group can be used as a dispersion stabilizer. In addition, since the pyrrolidone group does not exist on the surface of the base particle, the base particle is preferably not surface-treated with a composition containing no compound having a pyrrolidone group (surface treatment composition). .

  Moreover, it is also preferable that the said base particle is obtained by surface-treating the surface of the said base particle main body with the compound which has a pyrrolidone group.

  Examples of the polymerizable compound having a pyrrolidone group and the compound having a pyrrolidone group include N-vinylpyrrolidone, polyvinylpyrrolidone, poly (N-vinyl-2-pyrrolidone-g-citric acid), and poly (N-vinyl-2-pyrrolidone). -Co-itaconic acid, poly (N-vinyl-2-pyrrolidone-co-styrene), and the like.

  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 base particle body is a metal particle, examples of the metal for forming the metal particle 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 has an electroconductive layer arrange | positioned so that it may contact | connect a base particle on the surface of a base particle.

  The metal for forming the conductive layer is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and these. And the like. Examples of the metal include tin-doped indium oxide (ITO) and solder. Especially, since the connection resistance between electrodes can be made still lower, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is preferable.

  Like the conductive particles 1 and 21, the conductive layer may be formed of one layer. Like the conductive particles 11, the conductive layer may be formed of a plurality of layers. That is, the conductive layer may have a stacked structure of two or more layers. When the conductive layer is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and is a gold layer. Is more preferable. When the outermost layer is these preferred conductive layers, the connection resistance between the electrodes is further reduced. Moreover, when the outermost layer is a gold layer, the corrosion resistance is further enhanced.

  The conductive layer in contact with the substrate particles preferably contains nickel. The conductive layer preferably contains nickel as a main component. The conductive layer containing nickel is strongly chemically bonded to the base particle through the pyrrolidone group. When the conductive layer is formed on the surface of the base particle having the pyrrolidone group on the surface, the base particle and the conductive layer are strongly chemically bonded via the pyrrolidone group. For this reason, when the conductive layer connects the electrodes with conductive particles containing nickel, the connection resistance between the electrodes is further reduced.

  When the content of nickel in 100% by weight of the conductive layer in contact with the substrate particles is 50% by weight or more, the connection resistance between the electrodes is considerably reduced. The content of nickel in 100% by weight of the conductive layer is preferably 50% by weight or more, 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 100% by weight of the conductive layer may be 97% by weight or more, 97.5% by weight or more, or 98% by weight or more. The content of nickel in 100% by weight of the conductive layer 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 conductive layer in contact with the substrate particles preferably includes nickel and at least one of boron and phosphorus. In the conductive layer, nickel and at least one of boron and phosphorus may be alloyed. In the conductive layer, components other than nickel, boron, and phosphorus may be used.

  The total content of boron and phosphorus in 100% by weight of the conductive layer in contact with the substrate particles is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and still more preferably 0.1% by weight. % Or more, 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 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 content of nickel is relatively increased, so that the connection resistance between the electrodes is reduced.

  The content of boron in 100% by weight of the conductive layer in contact with the substrate particles 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 It is 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 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. If the boron content is less than or equal to the above upper limit, the nickel content is relatively increased, so that the connection resistance between the electrodes is reduced.

  It is preferable that the conductive layer in contact with the substrate particles 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 does not contain phosphorus.

  The measuring method of each content of nickel, boron, phosphorus and the like in the conductive layer 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, etc. in the conductive layer, it is preferable to use an ICP emission spectrometer. Examples of commercially available ICP emission analyzers include ICP emission analyzers manufactured by HORIBA.

  The method for forming the conductive layer on the surface of the substrate particles or the like 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 total thickness of the conductive layer in the conductive particles and the thickness of the conductive layer when the conductive layer is a single layer are preferably 0.005 μm or more, more preferably 0.01 μm or more, still more preferably 0.05 μm or more, preferably It is 1 μm or less, more preferably 0.3 μm or less. When the thickness of the conductive layer is not less than the above lower limit and not more than the above upper limit, sufficient conductivity is obtained, and the conductive particles do not become too hard, and the conductive particles are sufficiently deformed when connecting the electrodes. To do.

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

  The thickness of the entire conductive layer in the conductive particles and the thickness of the conductive layer when the conductive layer is a single layer are particularly preferably 0.05 μm or more and 0.3 μm or less. Furthermore, when the particle diameter of the substrate particles is 2 μm or more and 5 μm or less, and the thickness of the entire conductive layer in the conductive particles and the conductive layer is a single layer, the thickness of the conductive layer is 0.05 μm or more, 0. It is particularly preferable that the thickness is 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 can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM).

  As a method for controlling the content of nickel, boron and phosphorus in the conductive layer, for example, when forming a conductive layer by electroless nickel plating, a method for controlling the pH of a nickel plating solution, and by conducting electroless nickel plating A method of adjusting the concentration of the boron-containing reducing agent when forming the layer, a method of adjusting the concentration of the phosphorus-containing reducing agent when forming the conductive layer by electroless nickel plating, and the nickel concentration in the nickel plating solution The method etc. of adjusting are mentioned.

  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 and boron 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 and the boron-containing reducing agent 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 and boron 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.

[Core material]
The conductive particles according to the present invention preferably have protrusions on the conductive surface. The conductive layer preferably has a protrusion 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, a first conductive layer is formed on the surface of the base particle, and then a core substance is disposed on the first conductive layer, and then the second conductive layer. And a method of adding a core substance in the middle of forming the conductive layer on the surface of the base particle.

  The number of the protrusions per 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.

[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. Since 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.

(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 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 target member is preferably an electronic component. The conductive particles are preferably used for electrical connection of electrodes in 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.

(Preparation of substrate particles A to L)
(1) Preparation of base particle A A mixture of 100 parts by weight of divinylbenzene and 2 parts by weight of benzoyl peroxide was added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone, and the particle size was adjusted by stirring. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base particle A which has the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle A had a particle size of 3.0 μm.

(2) Preparation of base particle B A mixture of 100 parts by weight of divinylbenzene, 5 parts by weight of N-vinylpyrrolidone, and 2 parts by weight of benzoyl peroxide was added to 800 parts by weight of a 3% by weight aqueous solution of polyvinyl alcohol and stirred. The particle size was adjusted. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base-material particle | grains B which have the pyrrolidone group derived from N-vinyl pyrrolidone on the surface. The obtained base particle B had a particle size of 3.0 μm.

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

  In the separable flask, 100 parts by weight of the divinylbenzene copolymer resin particles, 200 parts by weight of dimethyl sulfoxide, and 50 parts by weight of N-vinylpyrrolidone were added and stirred. Next, nitrogen gas was introduced into the separable flask and stirred at 30 ° C. for 3 hours. Thereafter, 50 parts by weight of a 0.1 mol / L ceric ammonium nitrate solution prepared with a 1N nitric acid aqueous solution was added to the separable flask and reacted for 10 hours to obtain particles. After completion of the reaction, the obtained particles were washed with tetrahydrofuran. Thereafter, drying was performed to obtain base particles C having pyrrolidone groups derived from N-vinylpyrrolidone on the surface. The obtained base particle C had a particle size of 3.0 μm.

(4) Preparation of base particle D A mixed solution of 100 parts by weight of divinylbenzene and 2 parts by weight of benzoyl peroxide was added to 800 parts by weight of a 3% by weight aqueous solution of polyvinyl alcohol, and the particle size was adjusted by stirring. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and the base particle D was obtained. The obtained base particle D had a particle size of 3.0 μm.

(5) Preparation of substrate particles E A mixture of 30 parts by weight of divinylbenzene, 70 parts by weight of methyl methacrylate, and 2 parts by weight of benzoyl peroxide is added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone and stirred to obtain a particle size. Adjustments were made. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base particle E which has the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle E had a particle size of 3.0 μm.

(6) Preparation of base particle F A mixture of 30 parts by weight of divinylbenzene, 70 parts by weight of isobornyl methacrylate and 2 parts by weight of benzoyl peroxide was added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone and stirred. The particle size was adjusted. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base particle F which has the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle F had a particle size of 3.0 μm.

(7) Preparation of base particle G A mixture of 80 parts by weight of divinylbenzene, 20 parts by weight of acrylonitrile and 2 parts by weight of benzoyl peroxide is added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone, and the particle size is adjusted by stirring. Went. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base-material particle | grains G which have the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle G had a particle size of 3.0 μm.

(8) Preparation of base particle H To 800 parts by weight of a 3% by weight aqueous solution of polyvinyl pyrrolidone, a mixed liquid of 60 parts by weight of divinylbenzene, 40 parts by weight of acrylonitrile, and 2 parts by weight of perbutyl Z (manufactured by Yushi Co., Ltd.) was added. The particle size was adjusted by stirring. Then, it heated up to 140 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base-material particle | grains H which have the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle H had a particle size of 3.0 μm.

(9) Preparation of base particle I A mixture of 40 parts by weight of divinylbenzene, 60 parts by weight of methyl methacrylate, and 2 parts by weight of benzoyl peroxide was added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone and stirred to obtain a particle size. Adjustments were made. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base material particle | grains I which have the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle I had a particle size of 3.0 μm.

(10) Preparation of substrate particles J To 800 parts by weight of a 3% by weight aqueous solution of polyvinyl pyrrolidone, a mixed liquid of 70 parts by weight of divinylbenzene, 30 parts by weight of acrylonitrile, and 2 parts by weight of perbutyl Z (manufactured by Yushi Co., Ltd.) was added. The particle size was adjusted by stirring. Then, it heated up to 120 degreeC, stirring, and reacted for 15 hours and obtained particle | grains. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base material particle | grains J which have the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle J had a particle size of 3.0 μm.

(11) Preparation of substrate particles K A mixture of 40 parts by weight of divinylbenzene, 60 parts by weight of isobornyl methacrylate and 2 parts by weight of benzoyl peroxide is added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone and stirred. The particle size was adjusted. Then, it heated up to 80 degreeC, stirring, and reacted for 15 hours, and particle | grains were obtained. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base particle K which has the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle K had a particle size of 3.0 μm.

(12) Preparation of base particle L A mixture of 70 parts by weight of divinylbenzene, 30 parts by weight of acrylonitrile and 2 parts by weight of benzoyl peroxide is added to 800 parts by weight of a 3% by weight aqueous solution of polyvinylpyrrolidone, and the particle size is adjusted by stirring. Went. Then, it heated up to 100 degreeC, stirring, and reacted for 15 hours, and obtained particle | grains. The obtained particles were washed with hot ion exchange water and methanol, and then classified. Then, it dried and obtained the base particle L which has the pyrrolidone group derived from polyvinylpyrrolidone on the surface. The obtained base particle L had a particle size of 3.0 μm.

Example 1
After dispersing 10 parts by weight of the obtained base particle A in 100 parts by weight of an alkaline solution containing 5% by weight of a palladium catalyst solution using an ultrasonic disperser, the base material particle A is obtained by filtering the solution. I took it out. Subsequently, the base particle A was added to 100 parts by weight of a 1% by weight dimethylamine borane solution to activate the surface of the base particle A. The substrate particles A whose surfaces were 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, and 0.5 mol / L of sodium citrate 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, whereby a conductive layer (thickness 0.1 μm) is disposed on the surface of the base particle A so as to be in contact with the base particle A. Conductive particles were obtained. The content of nickel in 100% by weight of the conductive layer was 98.9% by weight, and the content of boron was 1.1% by weight.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the base particle A was changed to the base particle B.

(Example 3)
Except having changed the base material particle A into the base material particle C, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 1)
Except having changed the base material particle A into the base material particle D, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the base particle A was changed to the base particle E.

(Comparative Example 3)
Except having changed the base material particle A into the base material particle F, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 4)
Except having changed the base material particle A into the base material particle G, it carried out similarly to Example 1, and obtained electroconductive particle.

(Comparative Example 5)
Except having changed the base material particle A into the base material particle H, it carried out similarly to Example 1, and obtained electroconductive particle.

Example 4
(1) Palladium adhesion process The obtained base particle A was 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. Substrate particles A were added to 0.5 wt% dimethylamine borane solution at pH 6 to obtain substrate particles A to which palladium was attached.

(2) Core substance adhesion process The base particle A to which palladium was adhered was stirred and dispersed in 300 mL of ion-exchanged water for 3 minutes to obtain a dispersion. Next, 1 g of metallic nickel particle slurry (average particle size 100 nm) was added to the dispersion over 3 minutes to obtain substrate particles A to which a core substance was adhered.

(3) Electroless nickel plating step In the same manner as in Example 1, conductive particles in which a conductive layer (thickness: 0.1 μm) was disposed on the surface of the base particle A to which palladium was attached were obtained. The obtained conductive particles had protrusions on the outer surface of the conductive layer.

(Comparative Example 6)
Except having changed the base material particle A into the base material particle D, it carried out similarly to Example 4, and obtained electroconductive particle. The obtained conductive particles had protrusions on the outer surface of the conductive layer.

(Example 5)
Except having changed the base material particle A into the base material particle I, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 6)
Except having changed the base material particle A into the base material particle J, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 7)
Except having changed the base material particle A into the base material particle K, it carried out similarly to Example 1, and obtained electroconductive particle.

(Example 8)
Except having changed the base material particle A to the base material particle L, it carried out similarly to Example 1, and obtained electroconductive particle.

(Evaluation)
(1) Compression modulus (30% K value)
The compression modulus (30% 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).

(2) Compression recovery rate The compression recovery rate of the obtained electroconductive particle was measured by the method mentioned above using the micro compression tester ("Fischer scope H-100" by Fischer).

(3) 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 of the aluminum electrode. 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 of the obtained connection structure was measured by the 4-terminal method. Further, the connection resistance was determined according to the following 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

(4) Adhesion between substrate 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 ... 1st conductive layer 13 ... 2nd electroconductivity Layer 13a ... Projection 21 ... Conductive particles 22 ... Conductive layer 51 ... Connection structure 52 ... First connection target member 52a ... Surface 52b ... First electrode 53 ... Second connection target member 53a ... Surface 53b ... Second Electrode 54 ... connection part

Claims (8)

Having base material particles and a conductive layer disposed on the surface of the base material particles so as to be in contact with the base material particles,
The base particle and the conductive layer are chemically bonded via a pyrrolidone group,
The compression elastic modulus when compressed by 30% is 1500 N / mm ² or more and 8000 N / mm ² or less,
Conductive particles having a compression recovery rate of 20% or more and 90% or less.   The electroconductive particle of Claim 1 obtained by arrange | positioning the said electroconductive layer on the surface of the base particle which has a pyrrolidone group on the surface. Whether the substrate particles are obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group,
The substrate particles are obtained by performing a polymerization reaction using a polymerizable compound having a pyrrolidone group, or
The conductive particles according to claim 1 or 2, wherein the base particles are obtained by surface-treating the base particle main body with a compound having a pyrrolidone group.   The conductive material according to claim 1 or 2, wherein the substrate particles are obtained by performing a polymerization reaction using a polymerizable compound and a compound having a pyrrolidone group, or using a polymerizable compound having a pyrrolidone group. Sex particles.   The conductive particles according to claim 1 or 2, wherein the base particles are obtained by surface-treating the base particle main body with a compound having a pyrrolidone group.   The electroconductive particle of any one of Claims 1-5 in which the said electroconductive layer which contact | connects the said base material particle contains 50 weight% or more of nickel in 100 weight% of said electroconductive layers.   The electrically-conductive material containing the electroconductive particle of any one of Claims 1-6, 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;
A connection structure in which the connection portion is formed of the conductive particles according to any one of claims 1 to 6, or is formed of a conductive material including the conductive particles and a binder resin.

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