JP6333552B2 - Conductive particles, conductive materials, and connection structures - Google Patents

Description

  The present invention relates to conductive particles that can be used, for example, for electrical connection between electrodes, and more specifically, a conductive layer is disposed on the surface of a base particle, and the conductive layer is an outer surface. The present invention relates to a conductive particle having a plurality of protrusions. 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 the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin.

  The anisotropic conductive material is used for connection between an IC chip and a flexible printed circuit board, connection between an IC chip and a circuit board having an ITO electrode, and the like. For example, after disposing an anisotropic conductive material between the electrode of the IC chip and the electrode of the circuit board, these electrodes can be electrically connected by heating and pressing.

  As an example of the conductive particles, Patent Document 1 below discloses conductive particles including composite particles and a metal plating layer that covers the composite particles. The composite particles include a plastic core and non-conductive inorganic particles adsorbed on the plastic core by chemical bonding. In the electroconductive particle of patent document 1, the said metal plating layer has the surface which forms a projection part. The non-conductive inorganic particles are harder than the metal plating layer.

  Patent Document 2 below discloses conductive particles further including second non-conductive inorganic particles adsorbed on the surface of the metal plating layer in the conductive particles described in Patent Document 1.

JP 2011-29179 A JP 2011-29180 A

  When the electrodes are connected using the conductive particles described in Patent Documents 1 and 2, it is possible to reduce the connection resistance between the electrodes to some extent. However, even when the conductive particles described in Patent Documents 1 and 2 are used, the connection resistance between the electrodes may not be sufficiently low.

  In addition, in order to reduce the connection resistance between the electrodes, development of new conductive particles different from the conductive particles described in Patent Documents 1 and 2 is desired.

  An object of the present invention is to provide conductive particles capable of reducing the connection resistance between electrodes when used for connection between electrodes, and a conductive material and a connection structure using the conductive particles. is there.

  According to a broad aspect of the present invention, a base particle, a conductive layer disposed on the surface of the base particle and having a plurality of protrusions on the outer surface, and a plurality of embedded in the conductive layer The inorganic particles are disposed inside the protrusions on the outer surface of the conductive layer, and at least some of the inorganic particles of the plurality of inorganic particles are formed of the base particles. Conductive particles are provided that are not in contact with the surface.

  On the specific situation with the electroconductive particle which concerns on this invention, the several said inorganic particle is arrange | positioned inside the said 1 processus | protrusion of the outer surface of the said conductive layer.

  In another specific aspect of the conductive particle according to the present invention, 20% or more of the total number of the plurality of inorganic particles is not in contact with the surface of the substrate particle.

  In another specific aspect of the conductive particles according to the present invention, the distance between the inorganic particles that are not in contact with the surface of the substrate particles and the substrate particles is 5 nm or more.

  In another specific aspect of the conductive particle according to the present invention, a plurality of core substances embedded in the conductive layer are further provided.

  In another specific aspect of the conductive particle according to the present invention, the core substance is disposed inside the protrusion on the outer surface of the conductive layer, and the one protrusion on the outer surface of the conductive layer and the protrusion The inorganic particles are arranged between the core substance arranged inside the protrusions.

  In still another specific aspect of the conductive particle according to the present invention, the plurality of inorganic particles are in contact with the core substance.

  In another specific aspect of the conductive particles according to the present invention, the inorganic particles are adhered on the surface of the core substance, and a composite is formed by the core substance and the inorganic particles.

  In still another specific aspect of the conductive particle according to the present invention, the core substance is a metal particle.

  On the other specific situation of the electroconductive particle which concerns on this invention, the said some inorganic particle is unevenly distributed so that there may exist more on the outer surface side rather than the inner surface side of the said conductive layer.

  In another specific aspect of the conductive particle according to the present invention, an insulating material attached to the surface of the conductive layer is further provided.

  The conductive material according to the present invention includes the conductive particles described above and a binder resin.

  A connection structure according to the present invention 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 described above. The part is formed of the above-described conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin.

  The conductive particles according to the present invention include a base particle, a conductive layer disposed on the surface of the base particle and having a plurality of protrusions on the outer surface, and a plurality of embedded in the conductive layer. The inorganic particles are disposed inside the protrusions on the outer surface of the conductive layer, and at least some of the plurality of inorganic particles include the base material. Since it is not in contact with the surface of the particles, the connection resistance can be lowered by using conductive particles for the connection between the electrodes.

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. 4 is a front cross-sectional view schematically showing a connection structure using the conductive particles shown in FIG.

  Details of the present invention will be described below.

  The conductive particles according to the present invention include a base particle, a conductive layer disposed on the surface of the base particle and having a plurality of protrusions on the outer surface, and a plurality of embedded in the conductive layer. Inorganic particles.

  In the conductive particles according to the present invention, the conductive layer has a plurality of protrusions on the outer surface. An oxide film is often formed on the surface of the electrode connected by the conductive particles. Furthermore, an oxide film is often formed on the outer surface of the conductive layer. When the conductive layer has a plurality of protrusions on the outer surface, the conductive film is disposed between the electrodes and then subjected to pressure bonding, whereby the oxide film is effectively excluded by the protrusions. For this reason, an electrode and electroconductive particle can be made to contact effectively and the connection resistance between electrodes can be made low. Further, the protrusion can effectively exclude the binder resin and the insulating material between the conductive particles and the electrode. For this reason, the conduction | electrical_connection reliability between electrodes can be improved.

  Furthermore, in the electroconductive particle which concerns on this invention, the said inorganic particle is arrange | positioned inside the said protrusion of the outer surface of the said conductive layer. Furthermore, at least some of the inorganic particles among the plurality of inorganic particles are not in contact with the surface of the substrate particles. At least some of the inorganic particles are spaced apart from the substrate particles. The inorganic particles that are not in contact with the surface of the substrate particles are arranged at a position closer to the outer surface of the conductive layer as compared to the inorganic particles that are in contact with the surface of the substrate particles.

  By adopting the above-described configuration in the conductive particles according to the present invention, in particular, by arranging the inorganic particles inside the protrusions, and further by the presence of the inorganic particles not in contact with the surface of the base particle, Derived from the inorganic particles, the hardness of the protrusions in the conductive particles is effectively increased, and the connection resistance between the electrodes connected by the conductive particles can be reduced. For example, at the time of pressure bonding between the electrodes, the conductive layer tends to be strongly pressed against the electrodes due to the hard inorganic particles, so that the connection resistance is lowered. Further, when the conductive particles are compressed to connect the electrodes, it is possible to form an appropriate indentation on the electrodes. The indentation formed on the electrode is a concave portion of the electrode formed by pressing the electrode with conductive particles. Furthermore, when a conductive material (such as anisotropic conductive material) in which conductive particles are dispersed in a binder resin is used for pressure bonding between electrodes, the binder resin between the conductive layer and the electrode is effectively eliminated. it can. The connection resistance between the electrodes can also be lowered by effectively eliminating the binder resin.

  In the present invention, the inorganic particles that are not in contact with the surface of the substrate particles can be brought closer to the outer surface side of the conductive layer. When the inorganic particles approach the outer surface side of the conductive layer, the hardness of the protruding portion of the conductive particles is further effectively increased, and the connection resistance between the electrodes can be effectively reduced. The inorganic particles that are not in contact with the surface of the substrate particles are not chemically bonded to the substrate particles. Moreover, it is preferable that the said inorganic particle which is contacting the surface of the said base particle is not chemically bonded to the said base particle. Since the inorganic particles are not chemically bonded to the base particles, it is not necessary to introduce a functional group for chemically bonding the inorganic particles and the base particles to the surface of the inorganic particles or the surface of the base particles. For this reason, it is not necessary to prepare a new substance for introducing a functional group, and further, it is not necessary to perform a step of introducing a functional group, so that the production efficiency of conductive particles can be increased. It is preferable that the conductive particles include inorganic particles that are not adsorbed on the base particles by chemical bonds. It is preferable that the inorganic particles are not adsorbed on the base particles by chemical bonds.

  The conductive particles according to the present invention preferably further include a plurality of core substances embedded in the conductive layer. However, the conductive particles according to the present invention may not necessarily include the core substance. With the core material, protrusions can be easily formed on the outer surface of the conductive layer, and it is easy to bring inorganic particles closer to the outer surface side of the conductive layer. When the inorganic particles approach the outer surface side of the conductive layer, the hardness of the protruding portion of the conductive particles is effectively increased, and the connection resistance between the electrodes can be effectively reduced.

  A plurality of the inorganic particles are preferably arranged inside one of the protrusions on the outer surface of the conductive layer, and five or more inorganic particles are preferably arranged. Furthermore, the core material is disposed inside the protrusion on the outer surface of the conductive layer, and the gap between one protrusion on the outer surface of the conductive layer and the core material disposed on the inner side of the protrusion. It is preferable that the inorganic particles are arranged, more preferably a plurality of the inorganic particles are arranged, and it is preferable that five or more inorganic particles are arranged. In these cases, the hardness at the protruding portion of the conductive particles is effectively increased. For this reason, since the conductive layer is more strongly pressed by the electrodes by the inorganic particles arranged inside the protrusions when the electrodes are crimped, the connection resistance between the electrodes can be effectively reduced.

  It is preferable that the plurality of inorganic particles are unevenly distributed so that they are present more on the outer surface side than on the inner surface side of the conductive layer. In this case, when crimping between the electrodes, the conductive layer is effectively strongly pressed against the electrodes by the inorganic particles arranged inside the protrusions and in the vicinity of the outer surface of the conductive layer. It can be made even lower.

  It is preferable that the conductive layer is disposed between the surface of at least a part of the inorganic particles and the surface of the substrate particles. Further, it is preferable that the conductive layer or the core substance is disposed between at least a part of the surface of the inorganic particles and the surface of the base particle, and it is preferable that the core substance is disposed. . Furthermore, the conductive layer or the core substance is disposed between the surface of 20% or more (preferably 50% or more) of the inorganic particles out of the total number of inorganic particles and the surface of the substrate particles. It is preferable that the conductive layer is disposed. Of the total number of inorganic particles, 20% or more (preferably 50% or more) of the inorganic particles are preferably not in contact with the substrate particles, and are preferably separated from the substrate particles. In these cases, since the conductive layer is pressed more effectively and strongly by the electrode due to the inorganic particles at the time of pressure bonding between the electrodes, the connection resistance between the electrodes can be further reduced.

  The inorganic particles are preferably harder than the conductive layer. In this case, since the conductive layer is more effectively pressed by the electrode due to the inorganic particles at the time of pressure bonding between the electrodes, the connection resistance between the electrodes can be further reduced.

  The distance X between the inorganic particles that are not in contact with the surface of the substrate particles and the substrate particles is preferably 5 nm or more, more preferably more than 5 nm, still more preferably 10 nm or more, preferably 1 μm or less, more Preferably it is 0.3 micrometer or less. When only one inorganic particle that is not in contact with the surface of the substrate particle is present, the distance X indicates the shortest distance between one inorganic particle and the substrate particle. When there are a plurality of inorganic particles that are not in contact with the surface of the substrate particles, the distance X is determined by measuring the shortest distance between one inorganic particle and the substrate particles. It is obtained by calculating an average value. When there are 10 or more inorganic particles that are not in contact with the surface of the substrate particles, the distance X is determined by measuring the shortest distance between all the inorganic particles and the substrate particles. Although it is preferable to calculate by calculating the average value of the shortest distances, the 10 shortest distances between the 10 inorganic particles and the substrate particles are measured, and the average value of the 10 shortest distances is calculated. You may ask for it. The distance X may be 9/10 or less, 4/5 or less, 1/2 or less, or 1/3 or less of the thickness of the conductive layer.

  From the viewpoint of further effectively eliminating the oxide film on the surface of the electrode and the conductive particles, and further improving the conduction reliability between the electrodes, the inorganic particles and the base material out of 100% of the total number of the inorganic particles. The ratio of the number of inorganic particles having a shortest distance to the particles of 5 nm or more is preferably 50% or more, more preferably more than 80% and 100% or less. In all the inorganic particles, the shortest distance between the inorganic particles and the substrate particles may be 5 nm or more. The ratio of the number of inorganic particles having a shortest distance of 10 nm or more between the inorganic particles and the substrate particles in the total number of 100% of the inorganic particles is preferably 50% or more, more preferably more than 80%. 100% or less. In all of the inorganic particles, the shortest distance between the inorganic particles and the substrate particles may be 10 nm or more.

  The shortest distance between the inorganic particles and the base particles is obtained by photographing a plurality of cross-sections of the conductive particles to obtain an image, creating a stereoscopic image from the obtained image, and obtaining the obtained stereoscopic image. By using it, it is possible to measure accurately. The cross section can be photographed using a focused ion beam-scanning electron microscope (FIBSEM) or the like. For example, a thin film slice of conductive particles is prepared using a focused ion beam, and the cross section is observed with a scanning electron microscope. The operation is repeated several hundred times, and a three-dimensional image of the particle is obtained by image analysis.

  About the detail of the said measuring method, the distance between the surface of a base particle and a several inorganic particle can be measured by cut | disconnecting the obtained electroconductive particle and observing a cross section. The distance between the surface of the base material particle and the surface of the core material is obtained by photographing a plurality of cross-sections of the conductive particles to obtain an image, creating a stereoscopic image from the obtained image, and obtaining the stereoscopic image Can be measured. The above cross-section was photographed by a focused ion beam-scanning electron microscope (FIBSEM) apparatus name Helios NanoLab. 650 or the like. Using a focused ion beam, a thin film slice of conductive particles is prepared, and the cross section is observed with a scanning electron microscope. The operation is repeated 200 times, and a three-dimensional image of the particle is obtained by image analysis. The distance between the surface of the base particle and the surface of the inorganic particle is determined from the stereoscopic image, and the distance between the surface of the base particle and the surface of the inorganic particle is specified in a total number of 100% by weight of the inorganic particles. The ratio (%) of the number of inorganic particles satisfying the value can be obtained.

  Hereinafter, details of the conductive particles, the conductive material, and the connection structure will be described.

(Conductive particles)
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.

  First, the conductive particles 1 shown in FIG. 3 will be described. A conductive particle 1 shown in FIG. 3 includes a base particle 2, a conductive layer 3, a plurality of core substances 4, a plurality of inorganic particles 5, and an insulating substance 6. The conductive layer 3 is disposed on the surface of the base particle 2. The conductive layer 3 has a plurality of protrusions 3a on the outer surface. The plurality of core substances 4 are arranged on the surface of the base particle 2 and are embedded in the conductive layer 3. The core substance 4 is disposed inside the protrusion 3a. The plurality of inorganic particles 5 are disposed on the surface of the base particle 2 and are embedded in the conductive layer 3. The insulating material 6 is disposed on the surface of the conductive layer 3.

  The insulating material 6 is insulating particles. The insulating substance 6 is made of an insulating material. The conductive particles do not necessarily include an insulating substance. Moreover, the electroconductive particle may be provided with the insulating layer which coat | covers the outer surface of a conductive layer instead of an insulating particle as an insulating substance.

  In the conductive particle 1, a plurality of inorganic particles 5 are arranged inside one protrusion 3 a on the outer surface of the conductive layer 3. A plurality of inorganic particles 5 are disposed between one protrusion 3a on the outer surface of the conductive layer 3 and the core material 4 disposed inside the protrusion 3a. In addition, the conductive layer 3 or the core substance 4 is disposed between the surface of at least some of the inorganic particles 5 and the surface of the substrate particles 2. At least some of the inorganic particles 5 are not in contact with the base particle 2 and are spaced apart from the base particle 2. Furthermore, the plurality of inorganic particles 5 are in contact with the core substance 4. The plurality of inorganic particles 5 are attached to the core substance 4. The plurality of inorganic particles 5 are not chemically bonded to the substrate particles 2 and are not adsorbed by chemical bonding. The inorganic particles 5 that are not in contact with the substrate particles 2 are not chemically bonded to the substrate particles 2. The inorganic particles 5 are harder than the conductive layer 3. The Mohs hardness of the inorganic particles 5 is higher than the Mohs hardness of the conductive layer 3.

In the conductive particles 1, at least some of the inorganic particles 5 are in contact with the substrate particles 2. The conductive particles 1 include inorganic particles 5 that are in contact with the substrate particles 2. The inorganic particles 5 that are in contact with the substrate particles 2 are not chemically bonded to the substrate particles 2. The conductive particles 1 also include inorganic particles 5 that are not in contact with the substrate particles 2. Moreover, in the electroconductive particle 1, the base material particle 2 and the core substance 4 are not contacting. The base particle 2 and the core substance 4 may be in contact with each other.
A conductive particle 11 shown in FIG. 2 includes a base particle 2, a conductive layer 12, a plurality of core substances 13, a plurality of inorganic particles 14, and insulating particles 6. The conductive layer 12 is disposed on the surface of the base particle 2. The conductive layer 12 has a plurality of protrusions 12a on the outer surface. The plurality of core materials 13 are embedded in the conductive layer 12. The core substance 13 is disposed inside the protrusion 12a. The plurality of inorganic particles 14 are embedded in the conductive layer 12. The insulating particles 6 are disposed on the surface of the conductive layer 12.

  In the conductive particles 11, the core substance 13 and the inorganic particles 14 are not in contact. Thus, the core substance 13 and the inorganic particles 14 may not be in contact with each other.

  In the conductive particles 11, a plurality of inorganic particles 14 are arranged inside one protrusion 12 a on the outer surface of the conductive layer 12. The inorganic particles 14 are not in contact with the substrate particles 2. Further, in the conductive particles 11, the plurality of inorganic particles 14 are unevenly distributed so as to be present more on the outer surface side than on the inner surface side of the conductive layer 12. As a result, the inorganic particles 14 effectively increase the hardness of the protrusions 12a in the conductive particles 11. Therefore, the use of the conductive particles 11 further reduces the connection resistance between the electrodes.

  In the conductive particles 11, the plurality of inorganic particles 14 are present more in a region having a thickness ½ on the outer surface of the conductive layer 12 than in a region having a thickness ½ on the inner surface side of the conductive layer 12. In the conductive particles 21 described later, a plurality of inorganic particles 23 are present in a region having a thickness 1/2 of the outer surface of the conductive layer 22 more than a region having a thickness 1/2 of the inner surface of the conductive layer 22. To do. For example, out of a total number of 100% of the plurality of inorganic particles 14 and 23, the inorganic particles 14 and 23 are present in an area of a thickness ½ on the outer surface side of the conductive layers 12 and 22 in excess of 50%, preferably 60% or more, more preferably 70% or more. The plurality of inorganic particles 14 and 23 are present in a region having a thickness of 1/2 on the inner surface side of the conductive layers 12 and 22, or in a region having a thickness of 1/2 on the outer surface side of the conductive layers 12 and 22. Whether or not it exists is determined based on the center point of the inorganic particles 14 and 23.

  In the conductive particles 11, many inorganic particles 14 are not in contact with the core substance 13 and are not attached. Thus, the inorganic particles do not necessarily have to be in contact with the core substance.

  A conductive particle 21 shown in FIG. 1 includes a base particle 2, a conductive layer 22, a plurality of inorganic particles 23, and insulating particles 6. The conductive layer 22 is disposed on the surface of the base particle 2. The conductive layer 22 has a plurality of protrusions 22a on the outer surface. The plurality of inorganic particles 23 are embedded in the conductive layer 22. The insulating particles 6 are disposed on the surface of the conductive layer 22. The conductive particles 21 do not include a core substance. As described above, the conductive particles do not necessarily include the core substance.

  In the conductive particles 21, a plurality of inorganic particles 23 are arranged inside one protrusion 22 a on the outer surface of the conductive layer 22. The inorganic particles 23 are not in contact with the substrate particles 2. Further, in the conductive particles 21, like the conductive particles 11, the plurality of inorganic particles 23 are unevenly distributed so that they are present more on the outer surface side than on the inner surface side of the conductive layer 22. As a result, the inorganic particles 23 effectively increase the hardness of the protruding portions of the conductive particles 21. Therefore, the use of the conductive particles 21 further reduces the connection resistance between the electrodes.

  Of the conductive particles 1, 11 and 21, the conductive particles 21 are preferable. The production of the conductive particles 21 is relatively easy.

[Base material particles]
Examples of the substrate particles include resin particles, inorganic particles excluding metals, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal, or organic-inorganic hybrid particles.

  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, polypropylene, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate. Polyalkylene 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, poly Ether ketone, polyether sulfone, and polymers such as obtained by a variety of polymerizable monomer having an ethylenically unsaturated group is polymerized with one or more thereof. Resin for forming the resin particles can be designed and synthesized, and the hardness of the base particles can be easily controlled within a suitable range, which is suitable for conductive materials and having physical properties at the time of compression. Is preferably a polymer obtained by polymerizing one or more polymerizable monomers having a plurality of ethylenically unsaturated groups.

  When the resin particles are obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and a crosslinkable monomer. And 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 the case where the substrate particles are inorganic particles or organic-inorganic hybrid particles excluding metal particles, 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 0.5 μm or more, still 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, it is 500 μm or less, still more preferably 300 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm or less. When the particle diameter of the substrate particles is equal to or greater than the above lower limit, the contact area between the conductive particles and the electrodes is increased, so that the conduction reliability between the electrodes is further increased, and the electrodes are connected via the conductive particles. The connection resistance between them becomes even lower. Further, when forming the conductive layer on the surface of the base particle by electroless plating, it becomes difficult to aggregate and the aggregated conductive particles are hardly formed. When the particle diameter is not more than the above upper limit, the conductive particles are easily compressed, the connection resistance between the electrodes is further reduced, and the distance between the electrodes is further reduced. The particle diameter of the base particle indicates a diameter when the base particle is a true sphere, and indicates a maximum diameter when the base particle is not a true sphere.

  The particle diameter of the substrate particles is particularly preferably 0.1 μm or more and 5 μm or less. When the particle diameter of the substrate particles is in the range of 0.1 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. From the viewpoint of obtaining even smaller conductive particles even when the distance between the electrodes is further reduced or the conductive layer is thickened, the particle diameter of the base particles is preferably 0.5 μm or more. More preferably, it is 2 μm or more, preferably 3 μm or less.

[Conductive layer]
The metal for forming the conductive layer is not particularly limited. Furthermore, when the conductive particles are metal particles that are conductive layers as a whole, the metal for forming the metal particles 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. , Molybdenum, and alloys thereof. 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 more preferable. The metal constituting the conductive layer preferably contains nickel. The conductive layer preferably contains at least one selected from the group consisting of nickel, tungsten, molybdenum, palladium, phosphorus and boron, and more preferably contains nickel and phosphorus or boron. The material forming the conductive layer may be an alloy containing phosphorus, boron, or the like. In the conductive layer, nickel and tungsten or molybdenum may be alloyed.

  When the conductive layer contains phosphorus or boron, the total content of phosphorus and boron is preferably 4% by weight or less in 100% by weight of the conductive layer. When the total content of phosphorus and boron is not more than the above upper limit, the content of metals such as nickel is relatively increased, so that the connection resistance between the electrodes is further reduced. In 100% by weight of the conductive layer, the total content of phosphorus and boron is preferably 0.1% by weight or more, more preferably 0.5% by weight or more.

  The conductive layer may be formed of one layer or may be formed of a plurality of layers. That is, the conductive layer may be a single layer or 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 the gold layer or the palladium layer Is more preferable, and a gold layer is particularly 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 method for forming the conductive layer on the surface of the substrate particles 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 method of coating the surface of base particles with metal powder or a paste containing metal powder and a binder Etc. 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 average particle diameter of the conductive particles is preferably 0.11 μm or more, more preferably 0.5 μm or more, further preferably 0.51 μm or more, particularly preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, More preferably, it is 5.6 micrometers or less, Most preferably, it is 3.6 micrometers or less. When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrode becomes sufficiently large when the electrodes are connected using the conductive particles, and the conductive Aggregated conductive particles are less likely to be formed when the layer is formed. 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 “average particle size” of the conductive particles indicates a number average particle size. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The thickness of the conductive layer is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 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. .

  When the conductive layer is formed of a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably the thickness of the gold layer when the outermost layer is a gold layer. It is 0.01 μm or more, preferably 0.5 μm or less, more preferably 0.1 μm or less. When the thickness of the outermost conductive layer is not less than the above lower limit and not more than the above upper limit, the coating with the outermost conductive layer can be made uniform, corrosion resistance can be sufficiently enhanced, and the connection resistance between the electrodes can be increased. It can be made sufficiently low.

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

  The 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 average particle diameter of conductive particles and the like.

  The average height of the plurality of protrusions is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average height of the protrusions is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be effectively lowered.

[Core material]
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.

  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 a method for disposing the core substance on the surface of the base particle, for example, a conductive substance that becomes the core substance is added to the dispersion liquid of the base particle, and the core substance is formed on the surface of the base particle or metal particle. For example, by a method of accumulating and adhering by van der Waals force, and by adding a core substance to a container containing base particles or metal particles, and by mechanical action by rotating the container or the like, the base particles or metal Examples include a method of attaching a core substance to the surface of the particle. Especially, since the quantity of the core substance to adhere | attach is easy to control, the method to accumulate and adhere a core substance on the surface of the base particle or metal particle in a dispersion liquid is preferable.

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

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

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

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

[Inorganic particles]
It is preferable that the inorganic particles embedded in the conductive layer are harder than the conductive layer. In this case, the hardness of the protrusions in the conductive particles derived from the inorganic particles is further increased, and the connection resistance between the electrodes connected by the conductive particles can be lowered.

  Examples of the inorganic particles include silica (silicon dioxide, Mohs hardness 6-7), zirconia (Mohs hardness 8-9), alumina (Mohs hardness 9), tungsten carbide (Mohs hardness 9), diamond (Mohs hardness 10), and the like. Can be mentioned. The inorganic particles are preferably silica, zirconia, alumina, tungsten carbide or diamond, and are also preferably silica, zirconia, alumina or diamond. The Mohs hardness of the inorganic particles is preferably 5 or more, more preferably 6 or more. The Mohs hardness of the inorganic particles is preferably larger than the Mohs hardness of the conductive layer. The absolute value of the difference between the Mohs hardness of the inorganic particles and the Mohs hardness of the conductive layer is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.5 or more, and particularly preferably 1 or more. is there. Further, when the conductive layer is formed of a plurality of layers, the effect of reducing the connection resistance is more effectively exhibited when the inorganic particles are harder than all the metals constituting the plurality of layers.

  The plurality of inorganic particles may be in contact with the core substance. The inorganic particles may be attached to the surface of the core substance. You may arrange | position the said core substance and the said inorganic particle on the surface of the said base particle using the said core substance in which the said inorganic particle has adhered to the surface.

  The average particle size of the inorganic particles is preferably 0.0001 μm or more, more preferably 0.005 μm or more, preferably 0.5 μm or less, more preferably 0.1 μm or less. When the average particle size of the inorganic particles is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be effectively reduced.

  The “average particle diameter” of the inorganic particles indicates a number average particle diameter. The average particle diameter of the inorganic particles is obtained by observing 50 arbitrary inorganic particles with an electron microscope or an optical microscope and calculating an average value.

  In the conductive particles 1 shown in FIG. 3, a plurality of inorganic particles 5 are in contact with the core substance 4. The inorganic particles 5 are selectively disposed inside the protrusions 3 a on the outer surface of the conductive layer 3. The plurality of inorganic particles are preferably unevenly distributed so as to be present more inside the protrusions on the outer surface of the conductive layer than inside the outer surface portion where the protrusions of the conductive layer are not present. As a method of selectively disposing the inorganic particles inside the protrusions in this way, a method of attaching the inorganic particles to the core substance can be mentioned. Specifically, after the inorganic particles are attached to the surface of the core substance, Examples thereof include a method in which the core material to which the inorganic particles are attached is disposed on the surface of the base particle, and then the base material and the core material to which the inorganic particles are attached are covered with a conductive layer. Other methods may be used.

  Like the conductive particles 11 and 22 shown in FIGS. 2 and 1, the plurality of inorganic particles 14 and 23 are unevenly distributed so that they are present more on the outer surface side than the inner surface side of the conductive layers 12 and 22. Preferably it is. As a method of unevenly distributing inorganic particles in this way, a conductive layer is formed by a plurality of layers, and a method in which a larger amount of inorganic particles is contained in an outer conductive layer than an inner conductive layer, and a conductive layer is formed by electroless plating. In this case, a method of adding a large amount of inorganic particles to the electroless plating bath at a later stage than the initial stage of electroless plating may be used. Other methods may be used.

  From the viewpoint of effectively increasing the hardness of the protruding portions of the conductive particles and further reducing the connection resistance between the electrodes, the inorganic particles are attached on the surface of the core material, and the core material It is preferable that a composite is formed by the inorganic particles. Conductive particles including the composite can be obtained by preparing a composite having inorganic particles attached on the surface of the core material and embedding the composite in the conductive layer when the conductive layer is formed. . By using the composite, it is easy to embed the core substance and the inorganic particles in the conductive layer so that at least some of the inorganic particles do not come into contact with the surface of the base particles. .

  The inorganic particles may be attached to the core substance by chemical bonding, or may be attached mechanically or physically.

  The average diameter (average particle diameter) of the composite is preferably 0.0012 μm or more, more preferably 0.0502 μm or more, preferably 1.9 μm or less, more preferably 1.2 μm or less. When the average diameter of the composite is not less than the above lower limit and not more than the above upper limit, the connection resistance between the electrodes can be effectively reduced.

  The “average diameter (average particle diameter)” of the composite indicates a number average diameter (number average particle diameter). The average diameter of the composite is obtained by observing 50 arbitrary core substances 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 material 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 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. Note that when the conductive particles are pressurized with the two electrodes at the time of connection between the electrodes, the insulating substance between the conductive layer of the conductive particles and the electrodes can be easily excluded. Since the conductive particles have a plurality of protrusions on the outer surface of the conductive layer, the insulating material between the conductive layer of the conductive particles and the electrode can be easily excluded.

  It is preferable that the insulating material is an insulating particle because the insulating material can be more easily removed at the time of pressure bonding between the electrodes.

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

  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 material 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 of the insulating material (the average particle diameter of the insulating particles) 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 of the insulating material (the average particle diameter of the insulating particles) 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 (average particle diameter) of the insulating material is not less than the above lower limit, the conductive layers in the plurality of conductive particles are difficult to contact each other when the conductive particles are dispersed in the binder resin. When the average diameter (average particle diameter) of the insulating material is not more than the above upper limit, it is necessary to make the pressure too high in order to eliminate the insulating material between the electrode and the conductive particle when connecting the electrodes. Eliminates the need for heating to high temperatures.

  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 obtained 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 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.

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

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

  The conductive material according to the present invention can be used as a conductive paste and a conductive film. When the conductive material according to the present invention is 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 that electrically connects the first and second connection target members. The connection structure is preferably formed of the conductive particles of the invention or 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 one 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 electrodes 52b on the upper surface 52a (front surface). The second connection target member 53 has a plurality of electrodes 53b on the lower surface 53a (front surface). The electrode 52 b and the 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 that are circuit boards such as printed boards, flexible printed 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. The electrode is preferably an ITO electrode, an IZO electrode, an AZO electrode, a GZO electrode, or a ZnO electrode. These electrode surfaces are relatively hard. In the conductive particles according to the present invention, since the hardness of the protruding portion is relatively hard, the conductive layer and the relatively hard electrode can be effectively contacted, and the connection resistance between the electrodes can be effectively reduced. Can do.

  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
(1) Palladium adhesion process The divinylbenzene copolymer resin particle ("Micropearl SP-203" by Sekisui Chemical Co., Ltd.) whose particle diameter is 3.0 micrometers was 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 resin particles to which palladium was attached.

(2) Electroless nickel plating step 1000 mL of ion-exchanged water was added to the resin particles to which palladium was adhered, and the suspension was sufficiently dispersed using an ultrasonic processor. A nickel plating solution (pH 6.5) containing 0.23 mol / L of nickel sulfate, 0.5 mol / L of sodium hypophosphite, and 0.5 mol / L of sodium citrate was prepared. While stirring the suspension at 30 ° C., the nickel plating solution (pH 6.5) was gradually added dropwise to perform electroless nickel plating to form a first nickel plating layer having a thickness of 5 nm. After confirming that hydrogen foaming stopped, 1 g of alumina slurry (average particle diameter of 50 nm) was added and dispersed for 10 minutes, and then nickel plated particles 1 to which inorganic particles were adhered were obtained.

  1000 mL of ion-exchanged water was added to the nickel-plated particles 1 to which inorganic particles were adhered, and the suspension was sufficiently dispersed by using an ultrasonic processor. A nickel plating solution (pH 8.5) containing 0.23 mol / L of nickel sulfate, 0.5 mol / L of sodium hypophosphite, and 0.5 mol / L of sodium citrate was prepared. While the suspension is stirred at 30 ° C., the nickel plating solution (pH 8.5) is gradually dropped to perform electroless nickel plating of the nickel plating particles 1 to which inorganic particles are adhered, and a second film having a thickness of 95 nm. A nickel plating layer was formed. After confirming that hydrogen foaming stopped, the particles were collected by filtration, washed with water, substituted with alcohol, and then vacuum dried to obtain conductive particles having protrusions on the surface of the nickel plating layer.

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 100% (20% or more) of the total number of the plurality of inorganic particles is not in contact with the surface of the resin particles that are the base particles, and is spaced apart. It was.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the alumina slurry (average particle size 50 nm) was changed to zirconia slurry (average particle size 60 nm).

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 100% (20% or more) of the total number of the plurality of inorganic particles is not in contact with the surface of the resin particles that are the base particles, and is spaced apart. It was.

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that the alumina slurry (average particle size 50 nm) was changed to silica slurry (average particle size 20 nm).

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 100% (20% or more) of the total number of the plurality of inorganic particles is not in contact with the surface of the resin particles that are the base particles, and is spaced apart. It was.

Example 4
(1) Core substance adhesion process The resin particle to which the palladium obtained in Example 1 was adhered was prepared. The resin particles to which the palladium was attached 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 250 nm) was added to the dispersion over 3 minutes to obtain resin particles to which a core substance was adhered.

(2) Electroless nickel plating step 1000 mL of ion-exchanged water was added to the resin particles to which the core material was adhered, and the suspension was sufficiently dispersed using an ultrasonic processor. A nickel plating solution (pH 8.0) containing 0.25 mol / L of nickel sulfate, 0.25 mol / L of sodium hypophosphite, and 0.5 mol / L of sodium citrate was prepared. While the suspension is stirred at 30 ° C., the nickel plating solution (pH 8.0) is gradually added dropwise to perform electroless nickel plating of the resin particles to which the core material is adhered, A nickel plating layer was formed. After confirming that hydrogen foaming stopped, 1 g of alumina slurry (average particle diameter of 50 nm) was added and dispersed for 10 minutes, and then nickel plated particles 1 to which inorganic particles were adhered were obtained.

  1000 mL of ion-exchanged water was added to the nickel-plated particles 1 to which inorganic particles were adhered, and the suspension was sufficiently dispersed by using an ultrasonic processor. A nickel plating solution (pH 8.0) containing 0.25 mol / L of nickel sulfate, 0.25 mol / L of sodium hypophosphite, and 0.5 mol / L of sodium citrate was prepared. While the suspension is stirred at 30 ° C., the nickel plating solution (pH 8.0) is gradually added dropwise to perform electroless nickel plating of the nickel plating particles 1 to which the inorganic particles are adhered. A nickel plating layer was formed. After confirming that hydrogen foaming stopped, the particles were collected by filtration, washed with water, substituted with alcohol, and then vacuum-dried to obtain conductive particles having protrusions on the outer surface of the nickel plating layer.

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 100% (20% or more) of the total number of the plurality of inorganic particles is not in contact with the surface of the resin particles that are the base particles, and is spaced apart. It was.

(Comparative Example 1)
(1) Palladium adhesion process The divinylbenzene copolymer resin particle ("Micropearl SP-203" by Sekisui Chemical Co., Ltd.) whose particle diameter is 3.0 micrometers was 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 resin particles to which palladium was attached.

(2) Step of attaching inorganic particles The resin particles to which palladium was attached were stirred and dispersed in 300 mL of ion exchange water for 3 minutes to obtain a dispersion. Next, 1 g of alumina slurry (average particle size 50 nm) was added to the dispersion over 3 minutes to obtain resin particles to which inorganic particles were adhered. In the resin particles to which the obtained inorganic particles were adhered, all of the inorganic particles were in contact with the resin particles.

(3) Electroless nickel plating step A nickel plating solution (pH 8.0) containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, and 0.5 mol / L sodium citrate was prepared. While stirring the particle slurry liquid with the inorganic particles attached thereto at 60 ° C., the nickel plating solution (pH 8.0) was gradually added dropwise to perform electroless nickel plating to form a nickel plating layer having a thickness of 100 nm. After confirming that hydrogen foaming stopped, the particles were collected by filtration, washed with water, substituted with alcohol, and then vacuum dried to obtain conductive particles having protrusions on the surface of the nickel plating layer.

(Example 5)
(1) Palladium adhesion process The divinylbenzene copolymer resin particle ("Micropearl SP-203" by Sekisui Chemical Co., Ltd.) whose particle diameter is 3.0 micrometers was 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 dispersion liquid containing resin particles having palladium attached thereto.

(2) Core substance adhesion step 1 g of metallic nickel particle slurry (average particle size 250 nm) is added to the aqueous dispersion over 3 minutes, and 1 g of alumina slurry (average particle size 50 nm) is further added and dispersed for 10 minutes. Metal nickel particles 1 to which alumina was attached were obtained. Next, the metallic nickel particles 1 were added to a dispersion containing resin particles to which palladium was attached, and a slurry containing particles to which a core substance was attached was obtained.

(3) Electroless nickel plating step A nickel plating solution (pH 8.0) containing 0.25 mol / L nickel sulfate, 0.25 mol / L sodium hypophosphite, and 0.5 mol / L sodium citrate was prepared. The nickel plating solution (pH 8.0) was gradually dropped into the slurry while stirring the slurry containing the particles to which the core material was adhered at 60 ° C., and electroless nickel plating was performed. After confirming that hydrogen foaming stopped, the particles were collected by filtration, washed with water, substituted with alcohol, and then vacuum dried to obtain conductive particles having protrusions on the outer surface of the nickel plating layer having a thickness of 100 nm.

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 20% or more of the total number of the plurality of inorganic particles was not in contact with the surface of the resin particles as the base particles, and was separated from the distance.

(Example 6)
Conductive particles were obtained in the same manner as in Example 5 except that the alumina slurry (average particle size 50 nm) was changed to zirconia slurry (average particle size 60 nm).

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 20% or more of the total number of the plurality of inorganic particles was not in contact with the surface of the resin particles as the base particles, and was separated from the distance.

(Example 7)
Conductive particles were obtained in the same manner as in Example 5 except that the alumina slurry (average particle size 50 nm) was changed to silica slurry (average particle size 20 nm).

  In the obtained conductive particles, the inorganic particles were harder than the conductive layer, and the Mohs hardness of the inorganic particles was larger than the Mohs hardness of the conductive layer. Further, in the obtained conductive particles, 20% or more of the total number of the plurality of inorganic particles was not in contact with the surface of the resin particles as the base particles, and was separated from the distance.

(Example 8)
(1) Preparation 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- A monomer composition containing 1 mmol of N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2′-azobis (2-amidinopropane) dihydrochloride is added to ion-exchanged water so that the solid content is 5% by weight. After weighing out, the mixture was stirred at 200 rpm and polymerized at 70 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, the mixture was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle size of 220 nm, and a CV value of 10%.

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

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

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

(Examples 9 to 14)
Conductive particles having insulating particles attached thereto were obtained in the same manner as in Example 8, except that the conductive particles obtained in Example 1 were changed to the conductive particles obtained in the following Examples.
Example 9: Change to the conductive particles obtained in Example 2 Example 10: Change to the conductive particles obtained in Example 3 Example 11: Change to the conductive particles obtained in Example 4 Example 12: Change to the conductive particles obtained in Example 5 Example 13: Change to the conductive particles obtained in Example 6 Example 14: Change to the conductive particles obtained in Example 7

(Evaluation)
(1) Preparation 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, Mixing 50 parts by weight of a capsule-type curing agent (“HX3941HP” manufactured by Asahi Kasei Chemicals) and 2 parts by weight of a silane coupling agent (“SH6040” manufactured by Toray Dow Corning Silicone), the content of conductive particles is 3% % Was added and dispersed to obtain a resin composition.

  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. A glass substrate (width 3 cm, length 3 cm) provided with an aluminum electrode (height 0.2 μm, L / S = 20 μm / 20 μm) having a lead wire for resistance measurement on one side of the cut anisotropic conductive film. ) On the aluminum electrode side. Subsequently, the two-layer flexible printed circuit board (width 2cm, length 1cm) provided with the same aluminum electrode was bonded after aligning so that electrodes might overlap. 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. In addition, the 2 layer flexible printed circuit board by which the aluminum electrode was directly formed in the polyimide film was used.

(2) Connection resistance The connection resistance between the opposing electrodes of the connection structure obtained in (1) Preparation of the connection structure was measured by a four-terminal method. Further, the connection resistance was determined according to the following criteria.

[Criteria for connection resistance]
○: Connection resistance is 3.0Ω or less △: Connection resistance is more than 3.0Ω, 5.0Ω or less ×: Connection resistance is more than 5.0Ω

  The results are shown below.

[Connection resistance judgment result]
Example 1: ○
Example 2: ○
Example 3: ○
Example 4: ○
Comparative Example 1: ×
Example 5: ○
Example 6: ○
Example 7: ○
Example 8: ○
Example 9: ○
Example 10: ○
Example 11: ○
Example 12: ○
Example 13: ○
Example 14: ○

  In the conductive particles obtained in all Examples, five or more inorganic particles were arranged inside one protrusion on the outer surface of the conductive layer. Furthermore, in Examples 5-7 and 12-14, one core substance is arrange | positioned inside one processus | protrusion of the outer surface of a conductive layer, and one processus | protrusion on the outer surface of an electroconductive layer and the processus | protrusion inside There are five or more inorganic particles arranged between the arranged core materials. Moreover, in Examples 5-7 and 12-14, the conductive layer was arrange | positioned and the core substance was arrange | positioned between the surface of many inorganic particles and the surface of base material particle | grains. Furthermore, in Examples 5 to 7 and 12 to 14, since the composite in which the inorganic particles were adhered to the core material was used, many inorganic particles were in contact with the core material. In Examples 1 to 4 and 8 to 11, the plurality of inorganic particles are unevenly distributed so that they are present more inside the protrusions on the outer surface of the conductive layer than inside the outer surface portion where there are no protrusions on the conductive layer. It was.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Base material particle 3 ... Conductive layer 3a ... Protrusion 4 ... Core substance 5 ... Inorganic particle 6 ... Insulating substance 11 ... Conductive particle 12 ... Conductive layer 12a ... Protrusion 13 ... Core substance 14 ... Inorganic particle 21 ... Conductive particles 22 ... Conductive layer 22a ... Protrusions 23 ... Inorganic particles 51 ... Connection structure 52 ... First connection target member 52a ... Upper surface 52b ... Electrode 53 ... Second connection target member 53a ... Lower surface 53b ... Electrode 54 ... Connection

Claims (15)

Substrate particles,
A conductive layer disposed on the surface of the substrate particles and having a plurality of protrusions on the outer surface;
A plurality of inorganic particles embedded in the conductive layer,
It has no core material,
The core material is a material that forms one protrusion corresponding to one core material on the outer surface of the conductive layer by the core material being embedded in the conductive layer,
A plurality of the inorganic particles are disposed apart from each other inside each of the plurality of protrusions on the outer surface of the conductive layer,
At least some of the inorganic particles of the plurality of inorganic particles are not in contact with the surface of the base particle,
Conductive particles in which the Mohs hardness of the inorganic particles is greater than the Mohs hardness of the conductive layer. Substrate particles,
A conductive layer disposed on the surface of the substrate particles and having a plurality of protrusions on the outer surface;
A plurality of core materials embedded in the conductive layer;
A plurality of inorganic particles embedded in the conductive layer and not in contact with the core substance;
The core material is a material that forms one protrusion corresponding to one core material on the outer surface of the conductive layer by the core material being embedded in the conductive layer,
One core substance and a plurality of inorganic particles separated from each other are disposed inside each of the plurality of protrusions on the outer surface of the conductive layer,
At least some of the inorganic particles of the plurality of inorganic particles are not in contact with the surface of the base particle,
Conductive particles in which the Mohs hardness of the inorganic particles is greater than the Mohs hardness of the conductive layer. Substrate particles,
A conductive layer disposed on the surface of the substrate particles and having a plurality of protrusions on the outer surface;
A plurality of core materials embedded in the conductive layer;
A plurality of inorganic particles embedded in the conductive layer and in contact with the core substance;
The core material is a material that forms one protrusion corresponding to one core material on the outer surface of the conductive layer by the core material being embedded in the conductive layer,
One core substance and a plurality of inorganic particles separated from each other are disposed inside each of the plurality of protrusions on the outer surface of the conductive layer,
At least some of the inorganic particles of the plurality of inorganic particles are not in contact with the surface of the base particle,
Conductive particles in which the Mohs hardness of the inorganic particles is greater than the Mohs hardness of the conductive layer.   The conductive particles according to claim 3, wherein the inorganic particles are attached on the surface of the core substance, and the core substance and the inorganic particles form a composite. The inorganic particles are inorganic particles having an average particle diameter of 0.0001 μm or more and 0.5 μm or less,
5. The conductive particle according to claim 2, wherein the core substance is a core substance having an average particle diameter of 0.05 μm or more and 0.9 μm or less. The inorganic particles are inorganic particles having an average particle diameter of 0.0001 μm or more and 0.5 μm or less,
The core material is a core material having an average particle size of 0.05 μm or more and 0.9 μm or less (excluding a core material having an average particle size smaller than the average particle size of the inorganic particles). The electroconductive particle of any one of 2-4.   The said inorganic particle is arrange | positioned between one said processus | protrusion of the outer surface of the said conductive layer, and the said core substance arrange | positioned inside this processus, The any one of Claims 2-6 Conductive particles.   The electroconductive particle of any one of Claims 2-7 whose said core substance is a metal particle.   The electroconductive particle of any one of Claims 1-8 by which the 5 or more said inorganic particle is arrange | positioned mutually apart inside the said protrusion of one outer surface of the said electroconductive layer.   10. The conductive particle according to claim 1, wherein 20% or more of the total number of the plurality of inorganic particles is not in contact with the surface of the base particle.   The conductive particles according to any one of claims 1 to 10, wherein a distance between the inorganic particles that are not in contact with the surface of the substrate particles and the substrate particles is 5 nm or more.   The conductive particles according to claim 1, wherein a plurality of the inorganic particles are unevenly distributed so as to be present more on the outer surface side than on the inner surface side of the conductive layer.   The electroconductive particle of any one of Claims 1-12 further provided with the insulating substance adhering to the surface of the said electroconductive layer.   The electroconductive material containing the electroconductive particle of any one of Claims 1-13, and binder resin. A first connection target member, a second connection target member, and a connection portion connecting the first and second connection target members;
The connection structure in which the said connection part is formed with the electroconductive particle of any one of Claims 1-13, or is formed with the electrically-conductive material containing the said electroconductive particle and binder resin.

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