JP6592235B2 - Conductive particles with insulating particles, method for producing conductive particles with insulating particles, conductive material, and connection structure - Google Patents

Description

  The present invention relates to conductive particles with insulating particles in which insulating particles are arranged on the surface of conductive particles, and a method for producing conductive particles with insulating particles. Moreover, this invention relates to the electrically-conductive material and connection structure using the said electroconductive particle with an insulating particle.

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

  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 particle, Patent Document 1 below includes an insulating particle including a particle having a conductive metal surface and an insulating particle covering the surface of the particle having the conductive metal surface. Conductive particles are disclosed. Patent Document 1 describes that when two or more kinds of insulating particles having different particle diameters are used in combination, small insulating particles enter a gap covered with large insulating particles, thereby improving the coating density. .

  Further, in Patent Documents 2 and 3 below, conductive particles with insulating particles comprising conductive particles having at least a conductive layer on the surface and a plurality of insulating particles arranged on the surface of the conductive particles are provided. It is disclosed.

  In patent document 2, the coverage which is the area of the part coat | covered with the said insulating particle which occupies for the whole surface area of the said electroconductive particle is 60% or more and 95% or less. In Patent Document 3, the outer surface of the conductive part is rust-proofed, and the coverage, which is the area of the portion covered with the insulating particles in the entire surface area of the conductive particles, is 60% or more. .

JP 2005-44773 A JP 2013-16414 A JP 2014-29857 A

  The present inventors have found that the conventional conductive particles with insulating particles have a problem that the insulation reliability cannot be sufficiently improved when a considerably high insulation reliability is required.

  An object of the present invention is to provide a conductive particle with insulating particles and a method for producing conductive particles with insulating particles, which can increase the insulation reliability while maintaining high conduction reliability after conductive connection. is there. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles with insulating particles.

  According to a wide aspect of the present invention, the method includes conductive particles having at least a conductive portion on a surface and a plurality of insulating particles disposed on the surface of the conductive particles, and occupies the entire surface area of the conductive particles. The coverage, which is the area covered with the insulating particles, is 60% or more, and at least some of the plurality of insulating particles are in surface contact with each other, or the plurality of insulating particles However, conductive particles with insulating particles, which are formed by swelling the particles on the surface of the conductive particles, are provided.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, at least some of the plurality of insulating particles are in surface contact with each other.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, the plurality of insulating particles are formed by swelling the particles on the surface of the conductive particles.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, at least 30% by number or more of the total number of the plurality of insulating particles are in surface contact with each other.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, the coverage is greater than 85%.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, the plurality of insulating particles are a plurality of first insulating particles and 50 nm or more and 500 nm or less than the first insulating particles. A plurality of second insulating particles having a large average particle diameter.

  On the specific situation with the electroconductive particle with an insulating particle which concerns on this invention, the said electroconductive particle has several protrusion on the outer surface of the said electroconductive part.

  On the specific situation with the electroconductive particle with an insulating particle which concerns on this invention, the average particle diameter of the said insulating particle is 1 time or less of the average height of the said processus | protrusion.

  On the specific situation with the electroconductive particle with an insulating particle which concerns on this invention, the average height of the said processus | protrusion is 100 nm or more.

  On the specific situation with the electroconductive particle with an insulating particle which concerns on this invention, the average particle diameter of the said insulating particle is 0.1 time or more and 1 time or less of the average height of the said processus | protrusion.

  In a specific aspect of the conductive particles with insulating particles according to the present invention, a ratio of an average particle size of the insulating particles to a particle size of the conductive particles is 1/1000 or more and 1/3 or less.

  On the specific situation with the electroconductive particle with an insulating particle which concerns on this invention, the said insulating particle has adhered to the surface of the said electroconductive particle through a chemical bond.

  According to a wide aspect of the present invention, there is provided a method for producing the conductive particles with insulating particles described above, wherein the plurality of insulating particles are formed by swelling the particles on the surface of the conductive particles. A method for producing conductive particles with insulating particles is provided.

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

  According to a wide aspect of the present invention, a first connection target member having a first electrode on the surface, a second connection target member having a second electrode on the surface, the first connection target member, A connecting portion connecting the second connection target member, wherein the connecting portion is formed of the above-described conductive particles with insulating particles, or the conductive particles with insulating particles and a binder resin. A connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles in the conductive particles with insulating particles. Is provided.

  The conductive particles with insulating particles according to the present invention include conductive particles having at least a conductive part on a surface thereof, and a plurality of insulating particles arranged on the surface of the conductive particles. The coverage which is the area covered with the insulating particles in the entire surface area is 60% or more, and at least some of the plurality of insulating particles are in surface contact with each other, or the plurality Since the insulating particles are formed by swelling the particles on the surface of the conductive particles, the insulation reliability can be improved after conducting the conductive connection.

  In the method for producing conductive particles with insulating particles according to the present invention, the plurality of insulating particles are formed by swelling the particles on the surface of the conductive particles, so that the coverage rate is effectively increased. In addition, by conducting conductive connection using the obtained conductive particles with insulating particles, the insulation reliability can be enhanced while maintaining high conduction reliability.

FIG. 1 is a cross-sectional view showing conductive particles with insulating particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing conductive particles with insulating particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view showing conductive particles with insulating particles according to the third embodiment of the present invention. FIG. 4 is a sectional view showing conductive particles with insulating particles according to the fourth embodiment of the present invention. FIG. 5 is a front cross-sectional view schematically showing a connection structure using the conductive particles with insulating particles shown in FIG. 1. FIGS. 6A and 6B are schematic views for explaining a method for evaluating the coverage.

  Details of the present invention will be described below.

(Conductive particles with insulating particles)
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing conductive particles with insulating particles according to the first embodiment of the present invention. Note that different partial configurations in the respective embodiments can be appropriately replaced and combined.

  A conductive particle 1 with insulating particles shown in FIG. 1 includes conductive particles 2 and a plurality of insulating particles 3.

  The electroconductive particle 2 has the electroconductive part 12 at least on the surface. It is preferable that the outer surface of the electroconductive part 12 is rust-proofed.

  The insulating particles 3 are disposed on the surface of the conductive particles 2. The plurality of insulating particles 3 are in contact with the surface of the conductive particles 2 and are attached to the surface of the conductive particles 2. The plurality of insulating particles 3 are in contact with the outer surface of the conductive part 12 in the conductive particle 2 and are attached to the outer surface of the conductive part 12. The coverage, which is the area of the portion covered with the insulating particles 3 occupying the entire surface area of the conductive particles 2, is 60% or more.

  The plurality of insulating particles 3 are formed by swelling the particles on the surface of the conductive particles 2. At least some of the plurality of insulating particles 3 are not in point contact with each other but in surface contact. At least some of the total number of the plurality of insulating particles 3 are in surface contact with each other.

  The conductive particle 2 includes a base particle 11 and a conductive portion 12 disposed on the surface of the base particle 11. The conductive part 12 is a conductive layer. The conductive part 12 covers the surface of the base particle 11. The conductive particle 2 is a coated particle in which the surface of the base particle 11 is coated with the conductive portion 12. The conductive particle 2 has a conductive portion 12 on the surface.

  The insulating particles 3 are made of an insulating material. The particle diameter of the insulating particles 3 is smaller than the particle diameter of the conductive particles 2.

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

  The conductive particles 21 with insulating particles shown in FIG. 2 include conductive particles 22 and a plurality of insulating particles 23.

  The electroconductive particle 22 has the electroconductive part 26 at least on the surface. The outer surface of the conductive portion 26 is rust-proofed. The insulating particles 23 are disposed on the surface of the conductive particles 22. The coverage, which is the area of the portion covered with the insulating particles 23 occupying the entire surface area of the conductive particles 22, is 60% or more.

  In the conductive particles 1 with insulating particles and the conductive particles 21 with insulating particles, the conductive particles 2 and 22 and the insulating particles 3 and 23 are different.

  The conductive particle 22 includes the base particle 11 and a conductive portion 26 disposed on the surface of the base particle 11. The conductive particle 22 has a plurality of core substances 27 on the surface of the base particle 11. The conductive portion 26 covers the base particle 11 and the core material 27. By covering the core material 27 with the conductive portion 26, the conductive particles 22 have a plurality of protrusions 28 on the surface. The surface of the conductive portion 26 is raised by the core material 27, and a plurality of protrusions 28 are formed.

  The plurality of insulating particles 23 are formed by swelling the particles on the surface of the conductive particles 22. At least some of the plurality of insulating particles 23 are not in point contact with each other but in surface contact.

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

  The conductive particles 31 with insulating particles shown in FIG. 3 include conductive particles 32 and a plurality of insulating particles 33.

  The electroconductive particle 32 has the electroconductive part 36 at least on the surface. The insulating particles 33 are disposed on the surface of the conductive particles 32. The coverage, which is the area of the portion covered with the insulating particles 33 in the entire surface area of the conductive particles 32, is 60% or more.

  In the conductive particles 1 with insulating particles and the conductive particles 31 with insulating particles, only the conductive particles 2 and 32 and the insulating particles 3 and 33 are different.

  The conductive particle 32 includes the base particle 11 and a conductive portion 36 disposed on the surface of the base particle 11. The conductive particles 22 have a core material 27, but the conductive particles 32 do not have a core material. The conductive portion 36 has a first portion and a second portion that is thicker than the first portion. The conductive particles 32 have a plurality of protrusions 37 on the surface. A portion excluding the plurality of protrusions 37 is the first portion in the conductive portion 36. The plurality of protrusions 37 are the second portion in which the conductive portion 36 is thick.

  The plurality of insulating particles 33 are formed by swelling the particles on the surface of the conductive particles 32. At least some of the plurality of insulating particles 33 are not in point contact with each other but in surface contact.

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

  The conductive particle 41 with insulating particles shown in FIG. 4 includes the conductive particles 2 and a plurality of insulating particles 43. The insulating particles 43 are disposed on the surface of the conductive particles 2.

  The plurality of insulating particles 43 are formed by swelling the particles on the surface of the conductive particles 2. At least some of the plurality of insulating particles 43 are not in point contact with each other but in surface contact.

  The plurality of insulating particles 43 includes a plurality of first insulating particles 43A and a plurality of second insulating particles 43B having an average particle diameter that is 50 nm or more and 500 nm or less larger than the first insulating particles 43A. Including. In the conductive particles 41 with insulating particles, first and second insulating particles 43A and 43B having different average particle diameters are used.

  In each of the conductive particles 1, 21, 31, 41 with insulating particles, the area of the portion covered with the insulating particles 3, 23, 33, 43 occupying the entire surface area of the conductive particles 2, 22, 32 is Some coverage is 60% or more. Furthermore, the plurality of insulating particles 3, 23, 33, 43 are formed by swelling the particles on the surfaces of the conductive particles 2, 22, 32, or the plurality of insulating particles 3 At least some of them are in surface contact with each other. When the upper and lower electrodes are electrically connected using the conductive particles with insulating particles, it is possible to suppress electrical connection between the electrodes adjacent in the lateral direction that should not be connected. That is, insulation reliability can be improved. Normally, at the time of conductive connection, a large force that affects the detachment of the insulating particles is applied. As a result, the insulating particles are detached and the exposed conductive particles 2, 22, and 32 are in contact with the electrodes. The plurality of insulating particles 3, 23, 33, 43 are formed by swelling the particles on the surfaces of the conductive particles 2, 22, 32, or the plurality of insulating particles 3, Since at least some of them are in surface contact with each other, a plurality of insulating particles 3, 23, 33, 43 between the conductive particles 2, 22, 32, and the electrode are gathered together by the force applied during the conductive connection. Easy to take. For this reason, conduction reliability can be maintained high.

  In the present invention, a plurality of insulating particles may be formed by swelling the particles on the surface of the conductive particles. In this case, the insulating particles are likely to be in surface contact with each other or close to each other, so that unintended insulating particles can be prevented from being detached, and insulation reliability can be improved.

  In the present invention, at least some of the plurality of insulating particles may be in surface contact with each other. In this case, since the insulating particles are in surface contact with each other, unintentional detachment of the insulating particles can be prevented, and insulation reliability can be improved. In this case, a plurality of insulating particles may be brought into surface contact with each other by collision or the like and then disposed on the surface of the conductive particles.

  From the viewpoint of further increasing the insulation reliability and the insulation reliability against impact, the coverage, which is the area of the portion covered with the insulating particles in the entire surface area of the conductive particles, is preferably 65% or more, More preferably 70% or more, still more preferably more than 70%, still more preferably 75% or more, still more preferably 80% or more, particularly preferably 85% or more, and most preferably more than 85%. From the viewpoint of further improving the conduction reliability, the coverage is preferably 99% or less, more preferably 98% or less, and still more preferably 95% or less.

  The coverage, which is the area of the portion covered with the insulating particles occupying the entire surface area of the conductive particles, is obtained as follows.

  By observation with a scanning electron microscope (SEM), for example, 20 conductive particles with insulating particles are observed, and the coverage of conductive particles in the conductive particles with insulating particles (%) (attachment rate (%)) (Also called). The said coverage is a total area (projected area) of the part coat | covered with the insulating particle which occupies for the surface area of electroconductive particle.

  Specifically, when the conductive particles with insulating particles are observed from one direction with a scanning electron microscope (SEM), the coverage ratio is the surface of the conductive particles of the conductive particles with insulating particles in the observation image. The total area of the insulating particles in the circle of the outer peripheral edge portion of the surface of the conductive particles occupying the entire area in the circle of the outer peripheral edge portion (the hatched portion in FIG. 6A) (the hatched line in FIG. 6B) Part).

  From the viewpoint of further improving the conduction reliability and the insulation reliability, in the insulating particles in surface contact with each other, the surface area in surface contact with other insulating particles in the surface area of one insulating particle is preferably It is 0.5% or more, more preferably 1% or more, still more preferably 5% or more, preferably 40% or less, more preferably 30% or less. Insulating particles that are not in surface contact with other insulating particles are not considered in the surface area in surface contact.

  It is preferable that at least 30% by number or more of the total number of the plurality of insulating particles are in surface contact with each other. The ratio of the number of insulating particles in surface contact is more preferably 40% by number or more, further preferably 50% by number or more, and preferably 100% by number or less. The higher the ratio of the number of insulating particles in surface contact, the higher the coverage ratio and the higher the insulation reliability.

  The plurality of insulating particles include a plurality of first insulating particles and a plurality of second insulating particles having an average particle diameter larger by 50 nm or more and 500 nm or less than the first insulating particles. May be. By using two or more kinds of insulating particles having different particle diameters, the coverage can be effectively increased, and the insulation reliability can be effectively increased.

  From the viewpoint of further improving the conduction reliability, the insulation reliability, and the insulation reliability against impact, the ratio of the average particle diameter A of the insulating particles to the particle diameter B of the conductive particles (average particle diameter A / particle diameter B ) Is preferably 1/1000 or more, more preferably 1/100 or more, preferably 1/3 or less, more preferably 1/10 or less.

  The particle diameter of the conductive particles and the insulating particles means a diameter when the conductive particles and the insulating particles are spherical, and the conductive particles and the insulating particles are other than spherical. In the case of a shape, it means the maximum diameter. The average particle diameter is preferably obtained by observing 50 arbitrary particles with an electron microscope or an optical microscope and calculating an average value.

  From the viewpoint of further increasing the insulation reliability and the insulation reliability against impact, it is preferable that the insulating particles adhere to the surface of the conductive particles through a chemical bond.

  From the viewpoint of enhancing the conduction reliability between the electrodes, the conductive particles preferably have a plurality of protrusions on the outer surface of the conductive part. Generally, in conductive particles having protrusions on the outer surface of the conductive part, the insulation reliability tends to decrease as the protrusions increase. In the conductive particles with insulating particles according to the present invention, since the insulating particles are provided, insulation reliability can be sufficiently ensured even if the protrusions are large.

  From the viewpoint of further improving the conduction reliability, the conductive particles preferably have protrusions on the outer surface of the conductive part. From the viewpoint of further improving the conduction reliability, the average height of the protrusions is preferably 10 nm or more, more preferably 50 nm or more, preferably 200 nm or less, more preferably 150 nm or less.

  From the viewpoint of further improving the conduction reliability and the insulation reliability, the average particle diameter of the insulating particles is preferably 0.1 times or more, preferably 0.3 times or more of the average height of the protrusions. More preferably, it is 1 times or less, more preferably less than 1 time, still more preferably 0.9 times or less, and particularly preferably 0.8 times or less.

  The average particle diameter of the insulating particles indicates an average value of a plurality of insulating particles. The average height of the protrusions indicates an average value of the heights of the plurality of protrusions. The height of the protrusion is the imaginary line of the conductive layer (the broken line shown in FIG. 2) when it is assumed that there is no protrusion on the line connecting the center of the conductive particles and the tip of the protrusion (broken line L1 shown in FIG. 2). L2) Indicates the distance from the top (on the outer surface of the spherical conductive particles assuming no projection) to the tip of the projection. That is, in FIG. 2, the distance from the intersection of the broken line L1 and the broken line L2 to the tip of the protrusion is shown.

  Hereinafter, the details of the conductive particles and the insulating particles in the conductive particles with insulating particles will be described.

[Conductive particles]
The said electroconductive particle should just have an electroconductive part on the surface at least. The conductive part is preferably a conductive layer. The conductive particles may be base particles and conductive particles having a conductive layer disposed on the surface of the base particles, or may be metal particles whose entirety is a conductive portion. Among these, from the viewpoint of reducing the cost and increasing the flexibility of the conductive particles to increase the conduction reliability between the electrodes, the base particles and the conductive material disposed on the surface of the base particles are used. Conductive particles having a portion are preferred.

  Examples of the substrate particles include resin particles, inorganic particles excluding metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles excluding metal particles, and are preferably resin particles or organic-inorganic hybrid particles. The base particles may be core-shell particles. The core may be an organic core, and the shell may be an inorganic shell.

  The substrate particles are preferably resin particles formed of a resin. When connecting the electrodes using the conductive particles with insulating particles, the conductive particles with insulating particles are compressed by placing the conductive particles with insulating particles between the electrodes and then pressing them. When the substrate particles are resin particles, the conductive particles are likely to be deformed during the pressure bonding, and the contact area between the conductive particles and the electrode is increased. For this reason, the conduction | electrical_connection reliability between electrodes becomes high.

  Various organic materials are suitably used as the resin for forming the resin particles. Examples of the resin for forming the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Alkylene terephthalate, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polysulfone, polyphenylene Oxide, polyacetal, polyimide, polyamideimide, polyether ether Ketones, polyether sulfones, 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 the ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer. And a polymer.

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

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

  The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

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

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

    The metal for forming the conductive part is not particularly limited. Furthermore, in the case where the conductive particles are metal particles that are conductive parts as a whole, the metal for forming the metal particles is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, tungsten, and molybdenum. , Silicon 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 preferable. The melting point of the conductive part is preferably 300 ° C. or higher, more preferably 450 ° C. or higher. The conductive part may be a conductive part that is not solder.

  As the metal constituting the conductive part is more likely to be rusted, the coating effect by the coating is more remarkable. In the conductive part formed of nickel, copper or tin, rust is relatively easily generated on the outer surface of the conductive part. By covering the outer surface of such a conductive part with a film, it is possible to effectively suppress rust from being generated on the outer surface of the conductive part. Since the covering effect by the said film is acquired effectively, the said electroconductive part may contain nickel, copper, or tin.

  In many cases, hydroxyl groups are present on the surface of the conductive portion by oxidation. In general, a hydroxyl group exists on the surface of a conductive portion formed of nickel by oxidation. Insulating particles can be attached to the surface of the conductive part having such a hydroxyl group (the surface of the conductive particles) through a chemical bond.

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

  The method for forming the conductive portion on the surface of the particle is not particularly limited. Examples of the method for forming the conductive part include a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of particles with metal powder or a paste containing metal powder and a binder. Can be mentioned. Especially, since formation of an electroconductive part 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 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 20 μm or less, and even more preferably 5 μm 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 electrodes is sufficiently large when the electrodes are connected using the conductive particles with insulating particles. And it becomes difficult to form aggregated conductive particles when the conductive 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 part is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, particularly preferably 50 nm or more, preferably 1000 nm or less, more preferably 800 nm or less, still more preferably 500 nm or less, particularly preferably 400 nm. Hereinafter, it is most preferably 300 nm or less. The thickness of the conductive portion is the total thickness of the multilayer conductive portions (first and second conductive portions) when the conductive portion is a multilayer (such as the first and second conductive portions). When the thickness of the entire conductive portion is not less than the above lower limit, the conductivity of the conductive particles is further improved. When the thickness of the entire conductive part is less than or equal to the above upper limit, the difference in thermal expansion coefficient between the base particle and the conductive part is small, and the metal layer is difficult to peel from the base particle.

  When the conductive part is a multilayer, the thickness of the conductive part of the outermost layer is preferably 1 nm or more, more preferably 10 nm or more, preferably 500 nm or less, more preferably 100 nm or less. When the thickness of the conductive portion of the outermost layer is not less than the above lower limit and not more than the above upper limit, the coating with the conductive portion of the outermost layer can be made uniform, corrosion resistance is sufficiently high, and connection resistance between the electrodes is sufficiently high Lower. In addition, when the outermost layer is more expensive than the inner-layer conductive portion, the thinner the outermost layer, the lower the cost.

  The thickness of the said electroconductive part can be measured by observing the cross section of electroconductive particle or electroconductive particle with an insulating particle using a transmission electron microscope (TEM), for example.

  The conductive particles preferably have a plurality of protrusions on the outer surface of the conductive portion. An oxide film is often formed on the surface of the electrode connected by the conductive particles with insulating particles. When conductive particles with insulating particles having protrusions on the surface of the conductive part are used, the oxide film is effectively applied by the protrusions by placing conductive particles with insulating particles between the electrodes and pressing them. Can be eliminated. For this reason, an electrode and an electroconductive part contact more reliably and the connection resistance between electrodes becomes still lower. Furthermore, when the electrodes are connected, the insulating particles between the conductive particles and the electrodes can be effectively eliminated by the protrusions of the conductive particles. For this reason, the conduction | electrical_connection reliability between electrodes becomes still higher.

  As a method for forming the protrusions, after a core substance is attached to the surface of the base particle, a conductive part is formed by electroless plating, and a conductive part is formed by electroless plating on the surface of the base particle. Thereafter, a method of attaching a core substance and further forming a conductive portion by electroless plating can be used. As another method for forming the protrusion, a first conductive part is formed on the surface of the base particle, and then a core substance is disposed on the first conductive part, and then the second conductive part. And a method of adding a core substance in the middle of forming a conductive part on the surface of the base particle.

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

  Examples of the material of the core substance include a conductive substance and a non-conductive substance. 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. 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 substance may be the same as or different from the metal constituting the conductive part (conductive layer).

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

  The average diameter (average particle diameter) of the core substance is preferably 0.001 μm or more, more preferably 0.05 μm or more, preferably 0.9 μm or less, more preferably 0.2 μm or less. When the average diameter of the core substance is not less than the above lower limit and not more than the upper limit, the connection resistance between the electrodes is 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 substance is determined by measuring the number average particle diameter by measuring with a pore electrical resistance method Coulter counter Multisizer 4 (manufactured by Beckman Coulter).

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

  The outer surface of the conductive part is preferably rust-proofed. The rust prevention treatment suppresses corrosion of the outer surface of the conductive part. The said rust prevention process is not specifically limited. As the rust prevention treatment, a conventionally known rust prevention treatment can be performed.

  In order to make it difficult for rust to occur in the conductive layer, it is preferable that the outer surface of the conductive part is subjected to a rust prevention treatment with a compound having an alkyl group having 6 to 22 carbon atoms (hereinafter also referred to as compound A). Rust tends to occur on the surface of the conductive layer when the alkyl group has less than 6 carbon atoms. When carbon number of the said alkyl group exceeds 22, the electroconductivity of the electroconductive particle with an insulating particle will become low. From the viewpoint of further increasing the conductivity of the conductive particles with insulating particles, the alkyl group in the compound A preferably has 16 or less carbon atoms. The alkyl group may have a linear structure or a branched structure. The alkyl group preferably has a linear structure.

  The compound A is not particularly limited as long as it has an alkyl group having 6 to 22 carbon atoms. The compound A has a phosphate ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, a phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof, and an alkyl group having 6 to 22 carbon atoms. It is preferably at least one selected from the group consisting of alkoxysilanes, alkylthiols having an alkyl group having 6 to 22 carbon atoms, and dialkyl disulfides having an alkyl group having 6 to 22 carbon atoms. That is, the compound A having an alkyl group having 6 to 22 carbon atoms is at least one selected from the group consisting of phosphate esters or salts thereof, phosphite esters or salts thereof, alkoxysilanes, alkylthiols, and dialkyl disulfides. It is preferable that By using these preferable compounds A, it is possible to further prevent rust from being generated in the conductive layer. From the viewpoint of making rust more difficult to occur, the compound A is preferably at least one selected from the group consisting of the phosphate ester or a salt thereof, a phosphite ester or a salt thereof and an alkoxysilane, More preferably, the phosphoric acid ester or a salt thereof and a phosphorous acid ester or a salt thereof are at least one of them. As for the said compound A, only 1 type may be used and 2 or more types may be used together.

  The compound A preferably has a reactive functional group capable of reacting with the conductive part. The compound A preferably has a reactive functional group capable of reacting with insulating particles. It is preferable that the insulating particles are attached to the surface of the conductive particles through chemical bonds. Due to the presence of the reactive functional group and the chemical bond, rust is more unlikely to be generated in the conductive layer, and the insulating particles are more difficult to be detached from the surface of the conductive particles unintentionally.

  Examples of the phosphoric acid ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include, for example, phosphoric acid hexyl ester, phosphoric acid heptyl ester, phosphoric acid monooctyl ester, phosphoric acid monononyl ester, phosphoric acid monodecyl ester, Monoundecyl phosphate, monododecyl phosphate, monotridecyl phosphate, monotetradecyl phosphate, monopentadecyl phosphate, monohexyl phosphate monosodium salt, monoheptyl phosphate monosodium Salts, monooctyl phosphate monosodium salt, monononyl phosphate monosodium salt, monodecyl phosphate monosodium salt, monoundecyl phosphate monosodium salt, monododecyl phosphate monosodium salt, Phosphate mono tridecyl ester monosodium salt, phosphate acid mono tetradecyl ester monosodium salt and phosphoric acid mono pentadecyl ester monosodium salt. You may use the potassium salt of the said phosphate ester.

  Examples of the phosphite ester having an alkyl group having 6 to 22 carbon atoms or a salt thereof include, for example, hexyl phosphite ester, heptyl phosphite ester, monooctyl phosphite ester, monononyl phosphite ester, Phosphoric acid monodecyl ester, phosphorous acid monoundecyl ester, phosphorous acid monododecyl ester, phosphorous acid monotridecyl ester, phosphorous acid monotetradecyl ester, phosphorous acid monopentadecyl ester, phosphorous acid monohexyl Ester monosodium salt, phosphorous acid monoheptyl ester monosodium salt, phosphorous acid monooctyl ester monosodium salt, phosphorous acid monononyl ester monosodium salt, phosphorous acid monodecyl ester monosodium salt, phosphorous acid monoun Decyl ester monosodium salt, phosphorous acid Dodecyl ester monosodium salt, phosphorous acid mono-tridecyl ester monosodium salt, phosphorous acid mono-tetradecyl ester monosodium salt and phosphorous acid mono-pentadecyl ester monosodium salt. You may use the potassium salt of the said phosphite.

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

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

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

(Insulating particles)
The insulating particles are particles having insulating properties. The insulating particles are smaller than the conductive particles. When the electrodes are connected using conductive particles with insulating particles, the insulating particles can prevent a short circuit between adjacent electrodes. Specifically, when the conductive particles with a plurality of insulating particles are in contact with each other, the insulating particles are present between the conductive particles in the conductive particles with a plurality of insulating particles. In addition, a short circuit between electrodes adjacent in the lateral direction can be prevented. Note that the insulating particles between the conductive portion and the electrode can be easily excluded by pressurizing the conductive particles with insulating particles with two electrodes when connecting the electrodes. When the protrusion is provided on the surface of the conductive particle, the insulating particle between the conductive portion and the electrode can be more easily removed.

  In the present invention, the plurality of insulating particles are preferably formed by swelling the particles on the surface of the conductive particles.

  The particles to be swollen are, for example, insulating particles before the swelling treatment. Examples of the swelling method include a seed polymerization method.

  Specific manufacturing methods include the following manufacturing methods. Monomers that do not contain a crosslinking agent are polymerized using a technique such as soap-free polymerization to produce insulating particles before swelling treatment. Thereafter, the insulating particles before the swelling treatment are put into the dispersion liquid in which the conductive particles are dispersed, and the surfaces of the conductive particles are coated with the insulating particles before the swelling treatment by stirring. The insulating particles take in the emulsified monomer and swell by stirring while further dropping the emulsified monomer into the dispersion of the coated conductive particles. When the swelling is completed, the temperature of the dispersion is increased, and a polymerization reaction is performed to produce conductive particles covered with the insulating particles subjected to the swelling treatment.

  Examples of the material constituting the insulating particles include an insulating resin and an insulating inorganic substance. As said insulating resin, the said resin quoted as resin for forming the resin particle which can be used as a base particle is mentioned. As said insulating inorganic substance, the said inorganic substance quoted as an inorganic substance for forming the inorganic particle which can be used as a base particle is mentioned.

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

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

  From the viewpoint of further improving the detachability of the insulating particles at the time of pressure bonding, the insulating particles are preferably inorganic particles, and are preferably silica particles.

  Examples of the inorganic particles include shirasu particles, hydroxyapatite particles, magnesia particles, zirconium oxide particles, and silica particles. Examples of the silica particles include pulverized silica and spherical silica. Spherical silica is preferably used. The silica particles preferably have a functional group capable of chemical bonding such as a carboxyl group and a hydroxyl group on the surface, and more preferably have a hydroxyl group. Inorganic particles are relatively hard, especially silica particles are relatively hard. When the conductive particles with insulating particles including such hard insulating particles are used, when the conductive particles with insulating particles and the binder resin are kneaded, the surface of the conductive particles has a hard insulating property. There is a tendency for particles to be easily detached. On the other hand, when the conductive particles with insulating particles according to the present invention are used, even if hard insulating particles are used, the insulating particles have a high residual rate after kneading, resulting in insulation reliability. Can be secured.

  In order to make it difficult to cause rust in the conductive layer, the outer surface of the insulating particles is preferably subjected to a rust prevention treatment with the compound A having an alkyl group having 6 to 22 carbon atoms. A preferable compound A of the compound A is the same as the preferable compound A used for the antirust treatment of the outer surface of the conductive part.

  It is preferable that the insulating particles adhere to the surface of the conductive particles through chemical bonds. This chemical bond includes a covalent bond, a hydrogen bond, an ionic bond, a coordination bond, and the like. Of these, a covalent bond is preferable, and a chemical bond using a reactive functional group is preferable.

  Examples of the reactive functional group that forms the chemical bond include a vinyl group, (meth) acryloyl group, silane group, silanol group, carboxyl group, amino group, ammonium group, nitro group, hydroxyl group, carbonyl group, and thiol group. Sulfonic acid group, sulfonium group, boric acid group, oxazoline group, pyrrolidone group, phosphoric acid group and nitrile group. Among these, a vinyl group and a (meth) acryloyl group are preferable.

  From the viewpoint of further suppressing the detachment of the insulating particles and further increasing the insulation reliability in the connection structure, it is preferable to use insulating particles having reactive functional groups on the surface as the insulating particles. From the viewpoint of further suppressing the detachment of the insulating particles and further increasing the insulation reliability in the connection structure, the insulating particles surface-treated with a compound having a reactive functional group as the insulating particles. Is preferably used.

  Examples of the reactive functional group that can be introduced on the surface of the insulating particles include a (meth) acryloyl group, a glycidyl group, a hydroxyl group, a vinyl group, and an amino group. The reactive functional group on the surface of the insulating particles is at least one reactive functional group selected from the group consisting of a (meth) acryloyl group, a glycidyl group, a hydroxyl group, a vinyl group, and an amino group. preferable.

  Examples of the compound (surface treatment substance) for introducing the reactive functional group include a compound having a (meth) acryloyl group, a compound having an epoxy group, a compound having a vinyl group, and the like.

  Examples of the compound (surface treatment substance) for introducing a vinyl group include a silane compound having a vinyl group, a titanium compound having a vinyl group, and a phosphate compound having a vinyl group. The surface treatment substance is preferably a silane compound having a vinyl group. Examples of the silane compound having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and vinyltriisopropoxysilane.

  As a compound (surface treatment substance) for introducing a (meth) acryloyl group, a silane compound having a (meth) acryloyl group, a titanium compound having a (meth) acryloyl group, and a phosphoric acid having a (meth) acryloyl group Compounds and the like. The surface treatment substance is also preferably a silane compound having a (meth) acryloyl group. Examples of the silane compound having a (meth) acryloyl group include (meth) acryloxypropyltriethoxysilane, (meth) acryloxypropyltrimethoxysilane, (meth) acryloxypropyltridimethoxysilane, and the like.

  Examples of a method for attaching the insulating particles to the surfaces of the conductive particles and the conductive part 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 a spray drying method, a hybridization method, an electrostatic adhesion method, a spray method, a dipping method, and a vacuum deposition method. However, since the hybridization method tends to cause the detachment of the insulating particles, the method for arranging the insulating particles is preferably a method other than the hybridization method. The insulating particles are preferably not arranged on the surface of the conductive particles by the hybridization method. Since the insulating particles are more difficult to be detached, a method in which the insulating particles are arranged on the surface of the conductive particles through a chemical bond is preferable.

  The following method is mentioned as an example of the method of attaching insulating particles to the surface of the said electroconductive particle and the surface of the said electroconductive part.

  First, the conductive particles are put in 3 L of a solvent such as water, and the insulating particles are gradually added while stirring. After sufficiently stirring, the conductive particles with insulating particles are separated and dried by a vacuum dryer or the like to obtain conductive particles with insulating particles.

  The conductive part preferably has a reactive functional group capable of reacting with the insulating particles on the surface. The insulating particles preferably have a reactive functional group capable of reacting with the conductive part on the surface. By introducing a chemical bond with these reactive functional groups, it becomes difficult for the insulating particles to be unintentionally detached from the surface of the conductive particles. In addition, the insulation reliability and the insulation reliability against impact are further enhanced.

  As the reactive functional group, an appropriate group is selected in consideration of reactivity. Examples of the reactive functional group include a hydroxyl group, a vinyl group, and an amino group. Since the reactivity is excellent, the reactive functional group is preferably a hydroxyl group. The conductive particles preferably have a hydroxyl group on the surface. The conductive part preferably has a hydroxyl group on the surface. The insulating particles preferably have a hydroxyl group on the surface.

  When there are hydroxyl groups on the surface of the insulating particles and the surface of the conductive particles, the adhesion force between the insulating particles and the conductive particles is appropriately increased by the dehydration reaction.

  Examples of the compound having a hydroxyl group include a P—OH group-containing compound and a Si—OH group-containing compound. Examples of the compound having a hydroxyl group for introducing a hydroxyl group on the surface of the insulating particles include a P—OH group-containing compound and a Si—OH group-containing compound.

  Specific examples of the P-OH group-containing compound include acid phosphooxyethyl methacrylate, acid phosphooxypropyl methacrylate, acid phosphooxypolyoxyethylene glycol monomethacrylate, and acid phosphooxypolyoxypropylene glycol monomethacrylate. As for the said P-OH group containing compound, only 1 type may be used and 2 or more types may be used together.

  Specific examples of the Si-OH group-containing compound include vinyltrihydroxysilane and 3-methacryloxypropyltrihydroxysilane. As for the said Si-OH group containing compound, only 1 type may be used and 2 or more types may be used together.

  For example, insulating particles having a hydroxyl group on the surface can be obtained by a treatment using a silane coupling agent. Examples of the silane coupling agent include hydroxytrimethoxysilane.

  The surface of the conductive particles and the surface of the insulating particles may each be coated with a compound having a reactive functional group. The surface of the conductive particles and the surface of the insulating particles may not be directly chemically bonded, but may be indirectly chemically bonded by a compound having a reactive functional group. After introducing a carboxyl group into the surface of the conductive particle, the carboxyl group may be chemically bonded to a functional group on the surface of the insulating particle through a polymer electrolyte such as polyethyleneimine.

(Conductive material)
The conductive material according to the present invention includes the conductive particles with insulating particles according to the present invention and a binder resin. When the conductive particles with insulating particles according to the present invention are dispersed in the binder resin, the insulating particles are not easily detached from the surface of the conductive particles. The conductive particles with insulating particles according to the present invention are preferably dispersed in a binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection of electrodes. The conductive material is preferably a circuit connection material.

  The binder resin is not particularly limited. In general, an insulating resin is used as the binder resin. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers, and elastomers. As for the said binder resin, only 1 type may be used and 2 or more types may be used together.

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

  In addition to the conductive particles with insulating 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, and heat stability. Various additives such as an agent, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant may be contained.

  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.

  The conductive material according to the present invention is preferably a conductive paste. The conductive paste is excellent in handleability and circuit fillability. Although a relatively large force is imparted to the conductive particles with insulating particles when obtaining the conductive paste, the coverage of the insulating particles is high, so that the residual rate of the insulating particles in the conductive particles is increased. Can do.

  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 with insulating particles are efficiently arranged between the electrodes, and the conduction reliability of the connection target member connected by the conductive material is further increased. Get higher.

  In 100% by weight of the conductive material, the content of the conductive particles with insulating 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 15% by weight or less. When the content of the conductive particles with insulating 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)
By using the conductive particles with insulating particles described above, or by using a conductive material including the conductive particles with insulating particles and a binder resin, a connection structure can be obtained by connecting the connection target members. it can.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first connection target member and the second connection target member, the connection portion A connection structure formed of the above-described conductive particles with insulating particles or a conductive material (such as an anisotropic conductive material) containing the conductive particles with insulating particles and a binder resin. Preferably there is. The first connection target member preferably has a first electrode on the surface. The second connection object member preferably has a second electrode on the surface. It is preferable that the first electrode and the second electrode are electrically connected by the conductive particles in the conductive particles with insulating particles. When the conductive particles with insulating particles described above are used, the connection portion itself is formed of conductive particles with insulating particles. That is, the first and second connection target members are electrically connected by the conductive particles in the conductive particles with insulating particles.

  FIG. 5 is a cross-sectional view schematically showing a connection structure using the conductive particles 1 with insulating particles shown in FIG.

  The connection structure 81 shown in FIG. 5 is a connection that connects the first connection target member 82, the second connection target member 83, and the first connection target member 82 and the second connection target member 83. Part 84. The connecting portion 84 is formed of a conductive material including the conductive particles 1 with insulating particles and a binder resin. In FIG. 5, for convenience of illustration, the conductive particles 1 with insulating particles are schematically shown. Instead of the conductive particles 1 with insulating particles, conductive particles 21, 31, 41 with insulating particles may be used.

  The first connection target member 82 has a plurality of first electrodes 82a on the surface (upper surface). The second connection target member 83 has a plurality of second electrodes 83a on the surface (lower surface). The 1st electrode 82a and the 2nd electrode 83a are electrically connected by the electroconductive particle 2 in the electroconductive particle 1 with one or some insulating particle. Therefore, the first and second connection target members 82 and 83 are electrically connected by the conductive particles 1 with insulating particles.

The manufacturing method of the connection structure is not particularly limited. As an example of a method of manufacturing a connection structure, a method of placing the conductive material between a first connection target member and a second connection target member to obtain a laminate, and then heating and pressurizing the laminate Etc. 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.

  When the laminate is heated and pressed, the insulating particles 3 existing between the conductive particles 2 and the first and second electrodes 82a and 83a can be eliminated. For example, during the heating and pressurization, the insulating particles 3 existing between the conductive particles 2 and the first and second electrodes 82a and 83a are melted or deformed, The surface of the conductive particle 2 is partially exposed. It should be noted that since a large force is applied during the heating and pressurization, a part of the insulating particles 3 is detached from the surface of the conductive particles 2 and the surface of the conductive particles 2 is partially exposed. Sometimes. The portion where the surface of the conductive particle 2 is exposed contacts the first and second electrodes 82a and 83a, so that the first and second electrodes 82a and 83a are electrically connected through the conductive particle 2. it can.

  Specific examples of the connection target member include electronic components such as semiconductor chips, capacitors, and diodes, and electronic components such as printed boards, flexible printed boards, glass epoxy boards, and glass boards. The conductive material is in a paste form, and is preferably applied on the connection target member in a paste state. The conductive particles with insulating particles and the conductive material are preferably used for connection of a connection target member that is an electronic component. The connection target member is preferably an electronic component. The conductive particles with insulating 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 silver electrode, a molybdenum electrode, and a tungsten electrode. When the connection object member is a flexible printed board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, the electrode formed only with aluminum may be sufficient and the electrode by which the aluminum layer was laminated | stacked on the surface of the metal oxide layer may be sufficient. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

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

Example 1
(1) Production of conductive particles Divinylbenzene polymer particles (average particle diameter of 3 μm) were prepared. The polymer particles were etched and washed with water. Next, polymer particles were added to 100 mL of a palladium-catalyzed solution containing 8% by weight of a palladium catalyst and stirred. Then, it filtered and wash | cleaned. Polymer particles were added to a 0.5 wt% dimethylamine borane solution at pH 6 to obtain polymer particles to which palladium was attached.

  The polymer 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 nickel particle slurry (average particle diameter of nickel particles as the core material of 200 nm) was added to the dispersion over 3 minutes to obtain polymer particles to which the core material was adhered.

  A nickel layer was formed on the surface of the polymer particles by electroless plating using the polymer particles to which the core substance was attached. Conductive particles having a plurality of protrusions on the outer surface of the nickel layer were produced. The nickel layer had a thickness of 0.1 μm. The average height of the plurality of protrusions was 250 nm. Furthermore, the obtained electroconductive particle was rust-proofed and the electroconductive particle A by which the anti-rust process was carried out was obtained.

(Process for producing insulating particles)
A 1000 mL separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a cooling tube, and a temperature probe was charged with 40 parts by weight of glycidyl methacrylate, 380 parts by weight of methyl methacrylate, and acid phosphooxypolyoxyethylene glycol methacrylate 9 A monomer composition containing 8 parts by weight and 11 parts by weight of 2,2′-azobis {2- [N- (2-carboxyethyl) amidino] propane} was added. Distilled water was added to the monomer composition so that the solid content was 10% by weight, and the mixture was stirred at 300 rpm and polymerized at 80 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, freeze drying was performed to obtain insulating particles B before swelling treatment having P—OH groups derived from acid phosphooxypolyoxyethylene glycol methacrylate on the surface.

(Producing process of emulsion monomer for swelling treatment)
In a 300 ml beaker, 4 parts by weight of glycidyl methacrylate, 34 parts by weight of methyl methacrylate, 4 parts by weight of ethylene glycol dimethacrylate, 1.0 part by weight of an initiator (“V-50” manufactured by Wako Pure Chemical Industries, Ltd.) As an emulsifier, 2 parts by weight of polyoxyethylene lauryl ether (“Emulgen 106” manufactured by Kao Corporation) and 100 parts by weight of distilled water were blended and sufficiently emulsified using an ultrasonic irradiator to obtain an emulsion.

(Process for producing conductive particles with insulating particles)
The insulating particles B before swelling treatment obtained above were dispersed in distilled water under ultrasonic irradiation to obtain a 10 wt% aqueous dispersion of insulating particles. 10 g of the obtained conductive particles A were dispersed in 500 mL of distilled water, 5 g of an aqueous dispersion of insulating particles was added, and the mixture was stirred at room temperature for 3 hours. To the obtained dispersion, 3 g of the emulsion obtained above was gradually added dropwise over 5 hours, followed by further stirring for 10 hours to perform a swelling treatment. Then, it heated up to 80 degreeC, fully stirring with a three-one motor, and hold | maintained at 80 degreeC for 5 hours, and the said monomer was polymerized. After filtration with a mesh filter, the product was further washed with methanol and dried to obtain conductive particles with insulating particles.

  When observed with a scanning electron microscope (SEM), in the conductive particles with insulating particles, a coating layer of insulating particles is formed on the surface of the conductive particles having protrusions, and the area covered with the insulating particles The covering ratio was 85%, and 83% of the total number of insulating particles was in surface contact.

(Examples 2-8 and Comparative Examples 1-5)
The average particle diameter of the insulating particles was set as shown in Table 1 below, and the average particle diameter of the nickel particles as the core material was changed to set the average height of the protrusions as shown in Table 1 below. In addition, conductive particles with insulating particles were obtained in the same manner as in Example 1 except that the coverage was changed as shown in Table 1 below by changing the addition amount of the insulating particles.

Example 9
As insulating particles before the swelling treatment, silica particles (average particle size 50 nm) prepared by a sol-gel method were prepared. Vinyl groups were introduced on the surface of the silica particles using a silane coupling agent. To a 1000 mL separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, condenser and temperature probe, 500 ml of distilled water, 0.1 g of silica particles introduced with the above vinyl group, 38 mmol of methyl methacrylate, Monomer composition comprising ethylene glycol methacrylate 1.3 mmol, acid phosphooxypolyoxyethylene glycol methacrylate 0.05 mmol, and 2,2′-azobis {2- [N- (2-carboxyethyl) amidino] propane} 0.1 mmol The product was put in, sufficiently emulsified with an ultrasonic irradiation machine, stirred at 300 rpm, and polymerized at 80 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, the resultant was freeze-dried to obtain silica particle-containing polymer-coated insulating particles C having P—OH groups derived from acid phosphooxypolyoxyethylene glycol methacrylate on the surface.

  Using the obtained insulating particles C, changing the average particle diameter of the metallic nickel particles, setting the average height of the protrusions as shown in Table 1 below, and changing the addition amount of the insulating particles Except having set the said coverage as shown in following Table 1, it carried out similarly to Example 1, and obtained the electroconductive particle with an insulating particle.

(Example 10)
As insulating particles before the swelling treatment, silica particles (average particle size of 100 nm) prepared by a sol-gel method having different particle sizes were prepared. A silica particle-containing polymer-coated insulating particle having P-OH groups derived from acid phosphooxypolyoxyethylene glycol methacrylate on the surface was obtained in the same manner as in Example 9 except that this insulating particle before swelling treatment was used. Obtained.

  Using the obtained insulating particles, changing the average particle diameter of the metallic nickel particles, setting the average height of the protrusions as shown in Table 1 below, and changing the addition amount of the insulating particles Conductive particles with insulating particles were obtained in the same manner as in Example 1 except that the coverage was set as shown in Table 1 below.

(Evaluation)
(1) Coverage ratio, which is the total area of the portions covered with insulating particles in the entire surface area of the conductive particles. By observation with SEM, 20 conductive particles with insulating particles were observed. The coverage, which is the total projected area of the portion covered with insulating particles occupying the entire surface area of the conductive particles, was determined. The average value of the 20 coverages was taken as the coverage.

(2) The ratio of the number of insulating particles in surface contact with each other out of the total number of insulating particles, and the insulating particles in surface contact with each other, in the surface area of one insulating particle Ratio of surface area in surface contact with other insulating particles Twenty conductive particles with insulating particles were observed by SEM observation. The number of insulating particles per conductive particle when the conductive particles were observed from above and the number of insulating particles in surface contact with each other were counted and the ratio was evaluated. In addition, 20 insulating particles when one conductive particle is observed from the top surface are randomly observed, 0% for non-contact particles, 15% for one-surface contact particles, and two-surface contact particles. 30%, 3 surface contact particles were counted as 45%, 4 surface contact particles were counted as 60%, and 5 surface contact particles were counted as 75%, and the above values were evaluated by averaging the values.

(3) Aggregation state The resulting conductive particles with insulating particles are added to and dispersed in “Strectbond XN-5A” manufactured by Mitsui Chemicals so that the content is 10% by weight, and an anisotropic conductive paste. Got.

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

[Judgment criteria for aggregation state]
○: Aggregated conductive particles are not settled Δ: Small agglomerated conductive particles are slightly settled ×: Many aggregated conductive particles are settled

(4) Conductivity (between upper and lower electrodes)
The obtained conductive particles with insulating particles were added to “Strectbond XN-5A” manufactured by Mitsui Chemicals Co., Ltd. so as to have a content of 10% by weight, and dispersed to obtain an anisotropic conductive paste.

  A transparent glass substrate having an IZO electrode pattern with L / S of 20 μm / 20 μm formed on the upper surface was prepared. Further, a semiconductor chip having a gold electrode pattern with L / S of 20 μm / 20 μm formed on the lower surface was prepared.

  On the transparent glass substrate, the obtained anisotropic conductive paste was applied to a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was stacked on the anisotropic conductive paste layer so that the electrodes face each other. Then, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 185 ° C., a pressure heating head is placed on the upper surface of the semiconductor chip and a pressure of 3 MPa is applied to form the anisotropic conductive paste layer. It hardened | cured at 185 degreeC and the connection structure was obtained.

  The connection resistances between the upper and lower electrodes of the 20 connection structures obtained were each measured by the 4-terminal method. Note that the connection resistance can be obtained by measuring the voltage when a constant current is passed from the relationship of voltage = current × resistance. The conductivity was determined according to the following criteria.

[Conductivity criteria]
○○: The ratio of the number of connection structures having a resistance value of 5Ω or less is 90% or more ○: The ratio of the number of connection structures having a resistance value of 5Ω or less is 80% or more and less than 90% Δ: The resistance value is 5Ω or less The ratio of the number of connection structures of 60% or more and less than 80% ×: The ratio of the number of connection structures having a resistance value of 5Ω or less is less than 60%

(5) Insulation (between adjacent electrodes in the horizontal direction)
In the 20 connection structures obtained by the above (4) conductivity evaluation, the presence or absence of leakage between adjacent electrodes was evaluated by measuring resistance with a tester. Insulation was judged according to the following criteria.

[Insulation criteria]
○○: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 90% or more. ○: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is 80% or more and less than 90%. The ratio of the number of connection structures having a value of 10 ⁸ Ω or more is 70% or more and less than 80% ×: The ratio of the number of connection structures having a resistance value of 10 ⁸ Ω or more is less than 70%

DESCRIPTION OF SYMBOLS 1 ... Conductive particle with insulating particle 2 ... Conductive particle 3 ... Insulating particle 11 ... Base material particle 12 ... Conductive part 21 ... Conductive particle with insulating particle 22 ... Conductive particle 23 ... Insulating particle 26 ... Conductive Part 27 ... Core substance 28 ... Protrusions 31 ... Conductive particles with insulating particles 32 ... Conductive particles 33 ... Insulating particles 36 ... Conducting part 37 ... Protrusions 41 ... Conductive particles with insulating particles 43 ... Insulating particles 43A ... 1st insulating particle 43B ... 2nd insulating particle 81 ... Connection structure 82 ... 1st connection object member 82a ... 1st electrode 83 ... 2nd connection object member 83a ... 2nd electrode 84 ... Connection Part

Claims (13)

Conductive particles having at least a conductive portion on the surface;
A plurality of insulating particles disposed on the surface of the conductive particles,
The coverage, which is the area covered by the insulating particles in the entire surface area of the conductive particles, is 60% or more,
It said plurality of at least a portion of the insulating particles to each other, you are in surface contact, the insulating particles with the conductive particles. The conductive particles with insulating particles according to claim 1, wherein at least 30% by number or more of the total number of the plurality of insulating particles are in surface contact with each other. The conductive particles with insulating particles according to claim 1 or 2 , wherein the coverage ratio exceeds 85%. The plurality of insulating particles include a plurality of first insulating particles and a plurality of second insulating particles having an average particle diameter that is 50 nm or more and 500 nm or less larger than the first insulating particles. The electroconductive particle with an insulating particle of any one of Claims 1-3 . Wherein the conductive particles have a plurality of projections on the outer surface of the conductive portion, the insulating particles with conductive particles according to any one of claims 1-4. The conductive particles with insulating particles according to claim 5 , wherein an average particle diameter of the insulating particles is not more than 1 times an average height of the protrusions. The conductive particles with insulating particles according to claim 5 or 6 , wherein the average height of the protrusions is 100 nm or more. The conductive particles with insulating particles according to any one of claims 5 to 7 , wherein an average particle diameter of the insulating particles is 0.1 to 1 times the average height of the protrusions. The conductivity with insulating particles according to any one of claims 1 to 8 , wherein a ratio of an average particle size of the insulating particles to a particle size of the conductive particles is 1/1000 or more and 1/3 or less. particle. Wherein the surface of the conductive particles, through chemical bonds, the insulating particles are adhered, insulating particles with the conductive particles according to any one of claims 1-9. It is a manufacturing method of the electroconductive particle with an insulating particle of any one of Claims 1-10 , Comprising:
The method for producing conductive particles with insulating particles, wherein the plurality of insulating particles are formed by swelling the particles on the surface of the conductive particles. And insulating particles with conductive particle according to any one of claims 1-10, and a binder resin, conductive material. A first connection object member having a first electrode on its surface;
A second connection target member having a second electrode on its surface;
The first connection target member, and a connection portion connecting the second connection target member,
The connection portion is formed of the conductive particles with insulating particles according to any one of claims 1 to 10 , or formed of a conductive material including the conductive particles with insulating particles and a binder resin. Has been
The connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles in the conductive particles with insulating particles.

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