JP6641406B2 - Base particles, conductive particles, conductive material and connection structure - Google Patents

Description

  The present invention relates to a core-shell type base particle including a core and a shell disposed on a surface of the core. The present invention also relates to conductive particles, a conductive material, and a connection structure using the base particles.

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

  The anisotropic conductive material is used to electrically connect electrodes of various members to be connected such as a flexible printed circuit (FPC), a glass substrate, and a semiconductor chip to obtain a connection structure. In addition, conductive particles having base particles and a conductive layer disposed on the surface of the base particles may be used as the conductive particles.

  As an example of the base particles used for the conductive particles, in Patent Document 1 below, an organic material in which a shell is an inorganic compound (A), a core is an organic polymer (b), and the core is covered with the shell. Polymer particles (B) (substrate particles) are disclosed. Patent Document 1 also discloses conductive particles in which organic polymer particles (B) are coated with a conductive metal (C).

  Further, the liquid crystal display element is configured such that liquid crystal is arranged between two glass substrates. In the liquid crystal display device, a spacer is used as a gap control material in order to keep the gap (gap) between two glass substrates uniform and constant. Substrate particles are generally used as the spacer.

  As an example of the conductive particles or particles used for the spacer for a liquid crystal display element, Patent Document 2 below discloses that a polyfunctional silane compound having a polymerizable unsaturated group is hydrolyzed in the presence of a surfactant. Disclosed are organic-inorganic composite particles (base particles) obtained by polycondensation. In Patent Document 2, the polyfunctional silane compound is a first silicon compound containing at least one radically polymerizable group selected from the compound represented by the specific formula (X) and a derivative thereof.

  Patent Document 3 below discloses core-shell particles in which the surface of hard particles is coated with a soft polymer layer. Preferable examples of the hard particles include metal particles such as nickel, inorganic particles such as glass fiber, alumina and silica, and cured resin particles such as cured benzoguanamine. Patent Document 3 describes that by providing a soft high-molecular polymer layer, a contact area can be increased and reliability can be improved.

JP 2006-156068 A JP 2000-204119 A JP-A-7-140481

  In recent years, there is a tendency that the distance between electrodes connected by conductive particles is small and the electrode area is small, and there is a demand for conductive particles that can be connected with lower resistance.

  In the case where the conventional conductive particles as described in Patent Literatures 1 to 3 electrically connect electrodes having a small interval, the connection resistance may increase. As a cause of this, at the time of connection between the electrodes, the binder resin between the electrodes and the conductive particles cannot be sufficiently removed, and the resin is sandwiched between the electrodes and the conductive particles, and the conductive layer and the electrodes have It cannot be sufficiently penetrated through the oxide film on the surface.

  From the viewpoint of improving the exclusion of the binder resin and the penetration of the oxide film, conductive particles obtained by coating the surface of hard base particles with a conductive layer are advantageous. However, when hard base particles are simply used, the conductive particles are not sufficiently deformed after removing the resin and penetrating the oxide film. For this reason, there is a problem that the contact area between the electrode and the conductive particles does not become sufficiently large and the connection resistance does not become sufficiently low.

  In particular, in recent years, in order to reduce the power consumption of electronic devices such as smartphones and tablets, a metal electrode having a low resistance value without a metal oxide film but having a metal oxide film easily formed on the surface may be employed. is there. For this reason, conductive particles and anisotropic conductive materials that can penetrate the metal oxide film are demanded.

  Also, when thermocompression bonding is performed for electrical connection between electrodes using conventional conductive particles and an anisotropic conductive material containing a binder resin, the melt viscosity of the binder resin increases, and Since the conductive particles are eliminated together with the binder resin, the ratio of the conductive particles involved in the connection decreases. Therefore, it is necessary to mix a large amount of conductive particles in the anisotropic conductive material.

  On the other hand, when a conventional base particle as described in Patent Document 2 is used as a spacer for a liquid crystal display element and arranged between substrates to obtain a liquid crystal display element, the spacer is too hard, and the In some cases, a sufficient contact area between the spacer and the substrate cannot be ensured, or the distance between the substrates varies. In particular, when the base particles are included in the peripheral sealant of the liquid crystal display element, the spacing between the substrates is likely to vary due to the movement of the spacer during curing. As a result, the display quality of the obtained liquid crystal display element may be degraded.

  An object of the present invention is to provide a connection structure obtained by electrically connecting electrodes using conductive particles having a conductive layer formed on a surface, and to reduce the connection resistance, When thermocompression bonding is performed in a resin using conductive particles, many conductive particles can be involved in the connection without excessive removal of the conductive particles together with the binder resin during thermocompression bonding. It is an object of the present invention to provide base particles capable of improving the display quality of a liquid crystal display element when used as a spacer in a display element, and conductive particles, a conductive material, and a connection structure using the base particles. .

  According to a broad aspect of the present invention, a core having a core and a shell disposed on a surface of the core, and having a compression modulus of 10% compression of the base particles and a compression modulus of 30% of the base particles Wherein the ratio of the compression recovery of the core to the compression recovery of the base particles is 1 or more.

In a specific aspect of the base particles according to the present invention, the compression modulus when the base particles were compressed 10% 3000N / mm ² or more and 10000 N / mm ² or less.

  In a specific aspect of the base particles according to the present invention, the core is formed of an organic compound, and the shell is formed of a metal oxide.

  In a specific aspect of the base particles according to the present invention, the thickness of the shell is 50 nm or more and 500 nm or less.

In a specific aspect of the base particles according to the present invention, the compression modulus when the substrate particles to compression 30% 1000 N / mm ² or more and 4000 N / mm ² or less.

  In a specific aspect of the base particles according to the present invention, a compression recovery rate of the base particles is 25% or more.

  In a specific aspect of the base particle according to the present invention, the fracture strain of the shell is 10% or more and 30% or less, and the fracture strain of the core is 50% or more.

  In a specific aspect of the base particles according to the present invention, the base particles are obtained by adsorbing primary particles for constituting the shell in a solvent in which the core is dispersed, thereby forming the shell.

  In a specific aspect of the base particles according to the present invention, the core and the shell are not covalently bonded.

  The base particles according to the present invention preferably have a conductive layer formed on the surface and are used for obtaining conductive particles having the conductive layer, or are preferably used as spacers for liquid crystal display elements. It is preferable that the base particles according to the present invention have a conductive layer formed on the surface and are used to obtain conductive particles having the conductive layer.

  According to a broad aspect of the present invention, there is provided conductive particles having the above-described base particles and a conductive layer disposed on a surface of the base particles.

  In a specific aspect of the conductive particles according to the present invention, the conductive particles further include an insulating substance disposed on an outer surface of the conductive layer.

  In a specific aspect of the conductive particle according to the present invention, the conductive particle has a protrusion on an outer surface of the conductive layer.

  According to a wide aspect of the present invention, the conductive particles, comprising a binder resin, the conductive particles, the base particles described above, comprising a conductive layer disposed on the surface of the base particles, A conductive material is provided.

  According to a wide aspect of the present invention, a first connection target member having a first electrode on a surface, a second connection target member having a second electrode on a surface, the first connection target member, A connection portion connecting the second connection target member, the connection portion is formed of conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin, Wherein the conductive particles include the above-described base particles and a conductive layer disposed on the surface of the base particles, and the first electrode and the second electrode are electrically connected by the conductive particles. A connection structure is provided, wherein the connection structure is electrically connected.

  In the base particles according to the present invention, the shell is arranged on the surface of the core, and the compression elastic modulus when the base particles are compressed by 10% with respect to the compression elastic modulus when the base particles are compressed by 30%. The ratio is 1.5 or more, and the ratio of the compression recovery of the core to the compression recovery of the base particles is 1 or more. When the connection structure is obtained by electrically connecting the conductive particles, the connection resistance can be reduced, and the conductive particles are not excessively removed together with the binder resin during thermocompression bonding. It can be involved in the connection, and on the other hand, when used as a spacer in a liquid crystal display element, the display quality of the liquid crystal display element can be improved.

FIG. 1 is a sectional view showing the conductive particles according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating the conductive particles according to the second embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a conductive particle according to the third embodiment of the present invention. FIG. 4 is a front sectional view schematically showing a connection structure using the conductive particles according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing a liquid crystal display device using the base particles according to one embodiment of the present invention as a spacer for a liquid crystal display device.

  Hereinafter, the present invention will be described in detail.

(Base particles)
The base particles according to the present invention include a core and a shell disposed on a surface of the core.

  In the present invention, the ratio (10%) of the compression modulus (10% K value) when the base particles are compressed by 10% to the compression modulus (30% K value) when the base particles are compressed by 30%. % K value / 30% K value) is 1.5 or more. In the present invention, the ratio of the core compression recovery ratio to the base particle compression recovery ratio (core compression recovery ratio / base particle compression recovery ratio) is 1 or more.

  In the base particles according to the present invention, the compression modulus is high during the initial deformation (10% compression deformation), and the compression modulus is low during the middle deformation (30% compression deformation). As a result, when the electrodes are electrically connected to each other using conductive particles having a conductive layer formed on the surface of the base particles, the binder resin is sufficiently removed due to the hardness initially developed, and the conductive layer Alternatively, it is possible to sufficiently penetrate the oxide film on the surface of the electrode, and it is possible to sufficiently increase the contact area between the electrode and the conductive particles due to medium-term flexibility. Therefore, the connection resistance between the electrodes can be reduced, and the connection reliability between the electrodes can be improved. For example, even if the connection structure in which the electrodes are electrically connected by the conductive particles is left for a long time under a high-temperature and high-humidity condition, the connection resistance does not easily increase and the connection failure does not easily occur.

  Further, by setting the ratio of the compression recovery rate of the core to the compression recovery rate of the base particles to be 1 or more, the contact area of the base particles can be further increased. In the step of connecting between the electrodes using the conductive particles having, since the contact area between the conductive particles and the electrodes is increased, excessive movement of the conductive particles due to melting of the binder resin can be prevented, and The ratio of the conductive particles that participate in the heat treatment can be increased.

  Further, when the substrate particles according to the present invention are used as a spacer for a liquid crystal display element and arranged between substrates to obtain a liquid crystal display element, a sufficient contact area between the liquid crystal display element spacer and the substrate can be secured, Variations in the distance between the substrates can be suppressed, and the display quality of the liquid crystal display element can be improved.

  Further, when the base particles according to the present invention are used as a spacer for a liquid crystal display element, since the contact area between the spacer and the substrate is large, it is possible to prevent the movement of the spacer and to suppress a decrease in display quality. Can be.

  Further, the base particles according to the present invention have a conductive layer formed on the surface thereof, and are preferably used for obtaining conductive particles having the conductive layer, or preferably used as a spacer for a liquid crystal display element. It can also be used in other applications where similar or similar properties are required.

  The ratio (10% K value / 30% K value) of the 10% K value of the base particles to the 30% K value of the base particles is 1.5 or more. The ratio (10% K value / 30% K value) is preferably 1.75 or more, and more preferably 2.0 or more. When the ratio (10% K value / 30% K value) is not less than the lower limit, the contact area between the electrode and the conductive particles becomes sufficiently large, the connection resistance between the electrodes is effectively reduced, and the electrode The connection reliability between them is further improved. The ratio (10% K value / 30% K value) is preferably 5.0 or less, and more preferably 3.0 or less.

Compression modulus when the base particle is compressed 10% (10% K value) is preferably 1500 N / mm ² or more, more preferably 3000N / mm ² or more, more preferably 5000N / mm ² or more, preferably 15000N / Mm ² or less, more preferably 12000 N / mm ² or less, still more preferably 10,000 N / mm ² or less.

The compression modulus (30% K value) when the base particles are compressed by 30% is preferably 300 N / mm ² or more, more preferably 500 N / mm ² or more, still more preferably 1000 N / mm ² or more, and preferably 5000 N / mm ² or more. / mm ² or less, more preferably 4000 N / mm ^2, more preferably not more than 3000N / mm ^2.

  The compression modulus (10% K value and 30% K value) of the base particles can be measured as follows.

  Using a micro compression tester, the base particles are compressed under the conditions of 25 ° C., a compression speed of 0.3 mN / sec, and a maximum test load of 20 mN on the end face of a smooth indenter of a cylinder (diameter: 100 μm, made of diamond). At this time, the load value (N) and the compression displacement (mm) are measured. From the obtained measured values, the above-mentioned compression modulus can be determined by the following equation. As the micro-compression tester, for example, "Fischer Scope H-100" manufactured by Fischer is used.

10% K value or 30% K value (N / mm ² ) = (3/2 ^1/2 ) ・^FS -3 ^{/ 2}・ R ^{１ ／}
F: Load value (N) when the base particles are compressed or deformed by 10% or 30%
S: Compressive displacement (mm) when base particles undergo 10% or 30% compressive deformation
R: radius of base particles (mm)

  The compressive modulus universally and quantitatively represents the hardness of the base particles. By using the compression modulus, the hardness of the base particles can be quantitatively and uniquely expressed.

  The ratio of the compression recovery of the core to the compression recovery of the base particles (compression recovery of the core / compression recovery of the base particles) is 1 or more. The ratio (compression recovery of the core / compression recovery of the base material particles) is preferably 1.1 or more. When the ratio (compression recovery ratio of the core / compression recovery ratio of the base particles) is equal to or more than the lower limit, the connection resistance in the connection structure is effectively reduced, and the display quality in the liquid crystal display element is effectively increased. be able to. The ratio (compression recovery of the core / compression recovery of the base material particles) is preferably 1.3 or less.

  The compression recovery rate of the base particles is preferably 20% or more, more preferably 23% or more, and further preferably 25% or more. The compression recovery rate of the base particles may be 30% or more. When the compression recovery ratio is equal to or larger than the lower limit, the conductive particles sufficiently follow and easily deform in response to the change in the interval between the electrodes. For this reason, poor connection between the electrodes is less likely to occur. The compression recovery of the substrate particles is preferably less than 100%.

  The compression recovery rate can be measured as follows.

  Spray core or substrate particles on the sample stage. Using a micro-compression tester, a load (reversal load value) is applied to one of the sprayed core or base material particles in the center direction of the core or base material particle until the core or base material particle undergoes 30% compression deformation. . Thereafter, unloading is performed up to the load value for the origin (0.40 mN). The load-compression displacement during this time is measured, and the compression recovery rate can be obtained from the following equation. The load speed is 0.33 mN / sec. As the micro-compression tester, for example, "Fischer Scope H-100" manufactured by Fischer is used.

Compression recovery rate (%) = [(L1−L2) / L1] × 100
L1: Compressive displacement from the load value for origin to the reverse load value when applying a load L2: Unload displacement from the reverse load value to the load value for origin when the load is released

  When measuring the compression recovery rate of the core, the compression recovery rate of the core used to obtain the base particles is measured.

  The fracture strain rate of the shell is preferably 5% or more, more preferably 10% or more, further preferably 15% or more, preferably 30% or less, and more preferably 20% or less. When the fracture strain is not less than the lower limit, the rejection of the binder resin, the penetration of the conductive layer and the oxide film of the electrode are further increased, and the connection resistance is further decreased. When the fracture strain rate is equal to or less than the upper limit, flexibility in a medium term is exhibited, the contact area between the conductive particles and the electrode is further increased, and the connection resistance is further reduced.

  The fracture strain of the core is preferably 40% or more, more preferably 50% or more, further preferably 60% or more, and preferably less than 100%. When the fracture strain is not less than the lower limit, the rejection of the binder resin, the penetration of the conductive layer and the oxide film of the electrode are further increased, and the connection resistance is further decreased. When the fracture strain rate is equal to or less than the upper limit, flexibility in a medium term is exhibited, the contact area between the conductive particles and the electrode is further increased, and the connection resistance is further reduced.

  The fracture strain rate of the shell and the fracture strain rate of the core are measured using substrate particles.

  When the compressive behavior of the particles is evaluated, it is observed that at a certain load value, the displacement amount largely changes due to the fracture of the shell. The load value at this changing point is the breaking load value, and the displacement is the breaking displacement. The ratio of the breaking displacement to the particle size before compression (breaking displacement / particle size before compression) × 100 is defined as the breaking strain rate (%). For example, when a particle having a particle diameter of 5 μm before compression shows a fracture behavior of the shell at a displacement of 1 μm, a fracture strain rate of 20% is calculated. For example, when a particle having a particle diameter of 5 μm before compression shows a core breaking behavior at a displacement of 1 μm, a fracture strain rate of 20% is calculated. The fracture behavior of the core is observed after the fracture behavior of the shell is observed. The fracture strain rate can be evaluated from the above-described measurement of the compression elastic modulus, and can be measured by reading the displacement amount at the discontinuous point of the compression displacement curve.

  The use of the base particles is not particularly limited. The base particles are suitably used for various applications. It is preferable that the base particles have a conductive layer formed on the surface and are used to obtain conductive particles having the conductive layer, or are used as spacers for a liquid crystal display element. It is preferable that the base particles according to the present invention have a conductive layer formed on the surface and are used to obtain conductive particles having the conductive layer. The base particles are preferably used as a spacer for a liquid crystal display element, and are preferably used as a peripheral sealant for a liquid crystal display element. In the peripheral sealant for a liquid crystal display element, the base particles preferably function as spacers. Since the base particles have good compressive deformation characteristics, the base particles are used as spacers for a liquid crystal display element and are arranged between substrates, or a conductive layer is formed on the surface and used as conductive particles to form an electrode. When electrical connection is made between them, the spacers for liquid crystal display elements or conductive particles are efficiently arranged between the substrates or between the electrodes. For this reason, variations in the intervals between the substrates or between the electrodes are less likely to occur, and poor connection between the electrodes is less likely to occur.

  Further, the base particles are suitably used as an inorganic filler, a toner additive, a shock absorber or a vibration absorber. For example, the above-described base particles can be used as a substitute for rubber or a spring.

  The particle size of the core is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 500 μm or less, more preferably 100 μm or less, further preferably 50 μm or less, particularly preferably 20 μm or less, and most preferably 10 μm or less. . When the particle size of the core is equal to or more than the lower limit and equal to or less than the upper limit, the 10% K value, the 30% K value, and the ratio (10% K value / 30% K value) can easily show suitable values. In addition, the base particles can be suitably used for conductive particles and liquid crystal display devices. For example, when the particle size of the core is equal to or greater than the lower limit and equal to or less than the upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and Aggregated conductive particles are less likely to be formed when forming the conductive layer. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer does not easily peel off from the surface of the base particles.

  The particle diameter of the core means the diameter when the core is a true sphere, and the diameter when the core is assumed to be a sphere equivalent to the volume when the core has a shape other than the true sphere. I do. The particle size of the core means an average particle size of the core measured by an arbitrary particle size measuring device. For example, a particle size distribution analyzer using principles such as laser light scattering, electric resistance change, and image analysis after imaging can be used.

  The thickness of the shell is preferably 50 nm or more, more preferably 100 nm or more, further preferably 200 nm or more, preferably 500 nm or less, more preferably 300 nm or less. When the thickness of the shell is equal to or more than the lower limit and equal to or less than the upper limit, the 10% K value and the 30% K value show more preferable values, and the base particles are used for conductive particles and liquid crystal display element spacers. It becomes possible to use it suitably. The thickness of the shell is an average thickness per substrate particle. The thickness of the shell can be controlled by controlling the sol-gel method.

  In the present invention, the thickness of the shell can be determined from the difference between the particle size of the base particles and the particle size of the core. One half of this difference is the shell thickness. The particle diameter of the base particles means a diameter when the base particles are truly spherical, and assumes a volume-equivalent true sphere when the base particles have a shape other than a true sphere. It means the diameter when it is done. For the measurement of the particle size, for example, a particle size distribution measuring device using principles such as laser light scattering, electric resistance change, and image analysis after imaging can be used.

  The aspect ratio of the base particles is preferably 2 or less, more preferably 1.5 or less, and further preferably 1.2 or less. The aspect ratio indicates a major axis / a minor axis.

  The base particles are core-shell particles including a core and a shell disposed on the surface of the core. The core is preferably formed of an organic compound from the viewpoint of effectively reducing the connection resistance in the connection structure and effectively improving the display quality of the liquid crystal display element. From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively increasing the display quality in the liquid crystal display element, the shell is preferably formed of an inorganic compound, and formed of a metal oxide. Is preferred. In the core-shell particles in which the core is formed of an organic compound and the shell is formed of a metal oxide, the ratio (10% K value / 30% K value) and the ratio (compression recovery rate of the core / When the compression recovery rate of the base particles satisfies the above-described value, the connection resistance between the electrodes can be effectively reduced, and the connection reliability between the electrodes can be effectively increased.

  The core is preferably a core formed of an organic compound, and more preferably an organic core. The shell is preferably a shell formed of an inorganic compound, and more preferably an inorganic shell. Preferably, the core is an organic core and the shell is an inorganic shell. It is preferable that the base particles include an organic core and an inorganic shell disposed on the surface of the organic core, and are core-shell type organic-inorganic hybrid particles. When the core is an organic core or the shell is an inorganic shell, the ratio (10% K value / 30% K value) and the ratio (compression recovery rate of the core / compression recovery rate of the base particles) ) Can easily satisfy the above-mentioned values.

  The core is preferably an organic core, and more preferably an organic particle. Since the organic core and the organic particles are relatively flexible as compared with the inorganic core and the inorganic particles, a shell is formed on the surface of the relatively flexible organic core, and as a result, the ratio (10% K value / 30) is obtained. % K value) and the above ratio (compression recovery ratio of the core / compression recovery ratio of the base particles).

  Various organic substances are suitably used as a material for forming the organic core. Examples of the material for forming the organic core include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyalkylenes Terephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, and polymerizing one or more kinds of various polymerizable monomers having an ethylenically unsaturated group The resulting polymer or the like is used. By polymerizing one or two or more kinds of polymerizable monomers having an ethylenically unsaturated group, it is easy to design and synthesize base particles having physical properties at the time of compression suitable for a conductive material. It is.

  When the organic core is obtained by polymerizing a monomer having an ethylenically unsaturated group, the monomer having an ethylenically unsaturated group includes a non-crosslinkable monomer and a crosslinkable monomer. And a dimer.

  Examples of the non-crosslinkable monomer include styrene-based monomers such as styrene and α-methylstyrene; carboxyl-containing monomers such as (meth) acrylic acid, maleic acid, and maleic anhydride; methyl ( (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 and 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 tetramethylolmethanetetra (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, trimethylolpropanetri (meth) acrylate, and dipentane. 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) Acrylate, (poly) tetramethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nona Polyfunctional (meth) acrylates such as diol di (meth) acrylate; triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether, γ- (meth) acryloxypropyl trimethoxysilane And silane-containing monomers such as trimethoxysilylstyrene and vinyltrimethoxysilane.

  Among the above monomers, from the viewpoint of further improving the recoverability of the core, a copolymer containing 60% by weight or more of di (meth) acrylate containing a polyethylene glycol unit or a polyethylene oxide unit in the structure is preferable. For example, the core is preferably formed of an ethylene glycol diacrylate-divinylbenzene copolymer or a 1,4-butanediol diacrylate-ethylene glycol diacrylate copolymer.

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

  From the viewpoint of suppressing the deformation of the core during the formation of the shell and the use of the base particles, the decomposition temperature of the core is preferably higher than 200 ° C, more preferably higher than 250 ° C, and still more preferably higher than 300 ° C. Exceed. The decomposition temperature of the core may exceed 400 ° C., may exceed 500 ° C., may exceed 600 ° C., or may exceed 800 ° C.

  The base particles are core-shell particles. The shell is disposed on a surface of the core. The shell preferably covers the surface of the core. The shell is preferably an inorganic shell.

  From the viewpoint of effectively lowering the connection resistance in the connection structure and effectively improving the display quality in the liquid crystal display element, the base particles are used in the solvent in which the core is dispersed to constitute the shell. It is preferable that the above-mentioned shell is formed by adsorbing the primary particles.

  The inorganic shell may be formed by forming a metal alkoxide into a shell-like material on the surface of the core by a sol-gel method, and then firing the shell-like material. In the sol-gel method, it is easy to arrange a shell on the surface of the core. In the case of performing the above-mentioned firing, in the above-mentioned base particles, after the firing, the above-mentioned core remains without being removed by volatilization or the like. The base particles have the core after firing. If the core is removed by volatilization or the like after firing, the 10% K value becomes considerably low.

  As a specific method of the sol-gel method, an interfacial sol reaction is performed by coexisting an inorganic monomer such as tetraethoxysilane in a dispersion containing a core, a solvent such as water or alcohol, a surfactant, and a catalyst such as an aqueous ammonia solution. And a method of performing a sol-gel reaction with an inorganic monomer such as tetraethoxysilane coexisting with a solvent such as water or alcohol and an aqueous ammonia solution, and then hetero-aggregating the sol-gel reactant on the core. In the sol-gel method, the metal alkoxide is preferably hydrolyzed and polycondensed.

  In the sol-gel method, it is preferable to use a surfactant. It is preferable that the metal alkoxide is formed into a shell by a sol-gel method in the presence of a surfactant. The surfactant is not particularly limited. The surfactant is appropriately selected and used so as to form a good shell-like material. Examples of the surfactant include a cationic surfactant, an anionic surfactant, and a nonionic surfactant. Among them, a cationic surfactant is preferable since a good inorganic shell can be formed.

  Examples of the cationic surfactant include quaternary ammonium salts and quaternary phosphonium salts. Specific examples of the cationic surfactant include hexadecyltrimethylammonium bromide.

  On the surface of the core, the shell may be fired to form the inorganic shell. The degree of crosslinking in the inorganic shell can be adjusted by the firing conditions. Further, by performing the firing, the 10% K value and the 30% K value of the base particles show more preferable values as compared with the case where the firing is not performed. In particular, by increasing the degree of crosslinking, the 10% K value becomes sufficiently high.

  Examples of the metal alkoxide include silane alkoxide, titanium alkoxide, zirconium alkoxide, and aluminum alkoxide. From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a silane alkoxide, a titanium alkoxide, a zirconium alkoxide or an aluminum alkoxide, more preferably a silane alkoxide, a titanium alkoxide or a zirconium alkoxide, and more preferably a silane alkoxide. Is more preferable. From the viewpoint of forming a good inorganic shell, the metal atom in the metal alkoxide is preferably a silicon atom, a titanium atom, a zirconium atom or an aluminum atom, more preferably a silicon atom, a titanium atom or a zirconium atom. And more preferably a silicon atom. Note that silicon atoms are included in metals. As the metal alkoxide, only one kind may be used, or two or more kinds may be used in combination.

  From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a metal alkoxide represented by the following formula (1).

M (R1) _n (OR2) _4-n (1)

  In the above formula (1), M is a silicon atom, a titanium atom or a zirconium atom, and R1 is a phenyl group, an alkyl group having 1 to 30 carbon atoms, an organic group having 1 to 30 carbon atoms having a polymerizable double bond, or It represents an organic group having 1 to 30 carbon atoms having an epoxy group, R2 represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. When n is 2, a plurality of R1s may be the same or different. A plurality of R2s may be the same or different.

  From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a silane alkoxide represented by the following formula (1A).

Si (R1) _n (OR2) _4-n (1A)

  In the formula (1A), R1 represents a phenyl group, an alkyl group having 1 to 30 carbon atoms, an organic group having 1 to 30 carbon atoms having a polymerizable double bond, or an organic group having 1 to 30 carbon atoms having an epoxy group. R2 represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. When n is 2, a plurality of R1s may be the same or different. A plurality of R2s may be the same or different.

  When R1 is an alkyl group having 1 to 30 carbon atoms, specific examples of R1 include a methyl group, an ethyl group, a propyl group, an isopropyl group, an isobutyl group, an n-hexyl group, a cyclohexyl group, an n-octyl group, And an n-decyl group. The alkyl group has preferably 10 or less carbon atoms, and more preferably 6 or less carbon atoms. Note that the alkyl group includes a cycloalkyl group.

  Examples of the polymerizable double bond include a carbon-carbon double bond. When R1 is an organic group having a polymerizable double bond and having 1 to 30 carbon atoms, specific examples of R1 include a vinyl group, an allyl group, an isopropenyl group, and a 3- (meth) acryloxyalkyl group. And the like. Examples of the (meth) acryloxyalkyl group include a (meth) acryloxymethyl group, a (meth) acryloxyethyl group, and a (meth) acryloxypropyl group. The carbon number of the organic group having 1 to 30 carbon atoms having the polymerizable double bond is preferably 2 or more, preferably 30 or less, more preferably 10 or less. The above “(meth) acryloxy” means methacryloxy or acryloxy.

  When R1 is an organic group having 1 to 30 carbon atoms having an epoxy group, specific examples of R1 include a 1,2-epoxyethyl group, a 1,2-epoxypropyl group, a 2,3-epoxypropyl group, Examples include a 3,4-epoxybutyl group, a 3-glycidoxypropyl group, and a 2- (3,4-epoxycyclohexyl) ethyl group. The carbon number of the organic group having 1 to 30 carbon atoms having the epoxy group is preferably 8 or less, more preferably 6 or less. The organic group having 1 to 30 carbon atoms having an epoxy group is a group containing an oxygen atom derived from an epoxy group in addition to a carbon atom and a hydrogen atom.

  Specific examples of the above R2 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group.

  Specific examples of the silane alkoxide include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, isobutyltrimethoxysilane, and cyclohexyltrimethoxy. Examples include silane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, and diisopropyldimethoxysilane. Other silane alkoxides may be used.

  Specific examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, and titanium tetrabutoxide. Titanium alkoxides other than these may be used.

  Specific examples of the zirconium alkoxide include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, and zirconium tetrabutoxide. Other zirconium alkoxides may be used.

  The metal alkoxide has a structure in which four -OM groups (M is a metal atom) are directly bonded to a metal atom, and four oxygen atoms in the four -OM groups are directly bonded. It is preferable to include a metal alkoxide. The metal alkoxide preferably contains a metal alkoxide represented by the following formula (1a).

M (OR2) ₄ ... (1a)

  In the above formula (1a), M is a silicon atom, a titanium atom or a zirconium atom, and R2 represents an alkyl group having 1 to 6 carbon atoms. A plurality of R2s may be the same or different.

  The metal alkoxide may include a silane alkoxide having a structure in which four -O-Si groups are directly bonded to a silicon atom and four oxygen atoms in the four -O-Si groups are directly bonded. preferable. The metal alkoxide preferably contains a silane alkoxide represented by the following formula (1Aa).

Si (OR2) ₄ ... (1Aa)

  In the formula (1Aa), R2 represents an alkyl group having 1 to 6 carbon atoms. A plurality of R2s may be the same or different.

  From the viewpoint of controlling the 10% load value and the 30% load value to more preferable ranges, four -OM groups are present on the metal atom in 100 mol% of the metal alkoxide used to form the inorganic shell. A metal alkoxide which is directly bonded and has a structure in which four oxygen atoms in the four -OM groups are directly bonded, a metal alkoxide represented by the above formula (1a), and four- Each of a silane alkoxide having a structure in which an O-Si group is directly bonded and four oxygen atoms in the four -O-Si groups are directly bonded, or a silane alkoxide represented by the above formula (1Aa) The content is preferably at least 20 mol%, more preferably at least 40 mol%, further preferably at least 50 mol%, particularly preferably at least 60 mol% and at most 100 mol%. A. The total amount of the metal alkoxide used to form the inorganic shell is such that four -OM groups are directly bonded to the metal atom and four oxygen atoms in the four -OM groups are directly bonded. A metal alkoxide having the following structure, a metal alkoxide represented by the above formula (1a), four —O—Si groups directly bonded to the silicon atom, and four oxygens in the four —O—Si groups A silane alkoxide having a structure in which atoms are directly bonded, or a silane alkoxide represented by the above formula (1Aa) may be used.

  From the viewpoint of controlling the 10% K value and the 30% K value in a more preferable range, four -OM groups in 100% of the total number of metal atoms derived from the metal alkoxide contained in the inorganic shell are used. Are directly bonded and the proportion of the number of metal atoms to which four oxygen atoms in the four -OM groups are directly bonded, four -O-Si groups are directly bonded and the four The proportion of the number of silicon atoms to which four oxygen atoms are directly bonded in the —O—Si group is preferably 20% or more, more preferably 40% or more, further preferably 50% or more, and particularly preferably 60% or more. That is all.

  From the viewpoint of appropriately increasing the 10% K value and controlling the ratio (10% K value / 30% K value) to an appropriate range, the total number of metal atoms contained in the inorganic shell is considered. In 100%, the ratio of the number of metal atoms to which four -OM groups are directly bonded and four oxygen atoms in the four -OM groups are directly bonded is preferably 20% or more. , More preferably at least 40%, further preferably at least 50%, particularly preferably at least 60%. From the viewpoint of appropriately increasing the 10% K value and controlling the ratio (10% K value / 30% K value) to an appropriate range, the metal alkoxide is a silane alkoxide and is contained in the inorganic shell. Out of 100% of the total number of silicon atoms, four -O-Si groups are directly bonded, and four oxygen atoms in the four -O-Si groups are directly bonded. The proportion is preferably at least 20%, more preferably at least 40%, further preferably at least 50%, particularly preferably at least 60%.

  In addition, the silicon atom in which four -O-Si groups are directly bonded and four oxygen atoms in the four -O-Si groups are directly bonded is represented by, for example, the following formula (11). Is a silicon atom in the structure. Specifically, it is a silicon atom indicated by an arrow A in the structure represented by the following formula (11X).

  In addition, the oxygen atom in the above formula (11) generally forms a siloxane bond with an adjacent silicon atom.

  Preferably, there is no covalent bond between the core and the shell. If the core and the shell are not covalently bonded, the shell is not likely to be excessively cracked, and the contact area of the electrode and the conductive particles with the member to be connected can be increased. The connection resistance can be further reduced, and the display quality of the liquid crystal display element can be further improved.

  Preferably, the core and the shell are not covalently bonded, but may be covalently bonded. As a method of forming a covalent bond between the core and the shell, after introducing a functional group capable of reacting with a functional group of a material constituting the shell on the surface of the core, the shell is formed on the surface of the core. A method of forming a shell with a material may be used. Specifically, a method of treating the surface of the core with a coupling agent and then converting the metal alkoxide into a shell-like material on the surface of the core by a sol-gel method may be used.

(Conductive particles)
The conductive particles include the base particles described above and a conductive layer disposed on the surface of the base particles.

  FIG. 1 is a cross-sectional view showing the conductive particles according to the first embodiment of the present invention.

  The conductive particles 1 shown in FIG. 1 have base particles 11 and a conductive layer 2 disposed on the surface of the base particles 11. The conductive layer 2 covers the surface of the base particles 11. The conductive particles 1 are coated particles in which the surface of the base particles 11 is coated with the conductive layer 2.

  The base particles 11 include a core 12 and a shell 13 disposed on a surface of the core 12. The shell 13 covers the surface of the core 12. The conductive layer 2 is disposed on the surface of the shell 13. The conductive layer 2 covers the surface of the shell 13.

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

  The conductive particles 21 shown in FIG. 2 have the base particles 11 and the conductive layer 22 disposed on the surface of the base particles 11. The conductive layer 22 has a first conductive layer 22A as an inner layer and a second conductive layer 22B as an outer layer. The first conductive layer 22 </ b> A is disposed on the surface of the base particles 11. On the surface of the shell 13, a first conductive layer 22A is arranged. The second conductive layer 22B is disposed on the surface of the first conductive layer 22A.

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

  The conductive particles 31 shown in FIG. 3 include the base particles 11, the conductive layer 32, a plurality of core substances 33, and a plurality of insulating substances.

  The conductive layer 32 is disposed on the surface of the base particle 11. The conductive layer 32 is disposed on the surface of the shell 13.

  The conductive particles 31 have a plurality of protrusions 31a on the surface. The conductive layer 32 has a plurality of protrusions 32a on the outer surface. As described above, the conductive particles may have protrusions on the surface of the conductive particles, or may have protrusions on the outer surface of the conductive layer. A plurality of core substances 33 are arranged on the surface of the base particle 11. A plurality of core substances 33 are arranged on the surface of the shell 13. The plurality of core substances 33 are embedded in the conductive layer 32. The core substance 33 is arranged inside the projections 31a and 32a. The conductive layer 32 covers the plurality of core substances 33. The outer surface of the conductive layer 32 is raised by a plurality of core substances 33, and projections 31a and 32a are formed.

  The conductive particles 31 have an insulating material disposed on the outer surface of the conductive layer 32. At least a part of the outer surface of the conductive layer 32 is covered with the insulating material 34. The insulating substance 34 is formed of a material having an insulating property, and is an insulating particle. As described above, the conductive particles may have an insulating substance disposed on the outer surface of the conductive layer.

  The metal for forming the conductive layer is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, tungsten, and molybdenum. , Silicon and alloys thereof. Examples of the metal include tin-doped indium oxide (ITO) and solder. Among them, an alloy containing tin, nickel, palladium, copper, or gold is preferable, and nickel or palladium is preferable because the connection resistance between the electrodes can be further reduced.

  Like the conductive particles 1 and 31, the conductive layer may be formed by one layer. Like the conductive particles 21, the conductive layer may be formed by a plurality of layers. That is, the conductive layer may have a laminated 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 preferably a gold layer. Is more preferred. When the outermost layer is a preferred conductive layer, the connection resistance between the electrodes is further reduced. When the outermost layer is a gold layer, the corrosion resistance is further improved.

  The method for forming the conductive layer on the surface of the base particles is not particularly limited. As a method of forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a method of coating the surface of the base particles with a metal powder or a paste containing a metal powder and a binder And the like. Above all, a method using electroless plating is preferable because formation of the conductive layer is simple. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering.

  The particle size of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 520 μm or less, more preferably 500 μm or less, even more preferably 100 μm or less, further preferably 50 μm or less, and particularly preferably 20 μm or less. It is as follows. When the particle size of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, and the conductive layer When forming the conductive particles, it is difficult to form aggregated conductive particles. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer does not easily peel off from the surface of the base particles. When the particle size of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles can be suitably used for a conductive material.

  The particle diameter of the conductive particles means a diameter when the conductive particles are truly spherical, and when the conductive particles have a shape other than a true spherical shape, assuming that the volume is a true sphere equivalent to the volume. Means the diameter of

  The thickness of the conductive layer (the total thickness of the conductive layer when the conductive layer is a multilayer) is preferably 0.005 μm or more, more preferably 0.01 μm or more, preferably 10 μm or less, more preferably 1 μm or less, and furthermore Preferably it is 0.3 μm or less. When the thickness of the conductive layer is equal to or greater than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles are not excessively hard, and the conductive particles are sufficiently deformed at the time of connection between the electrodes. .

  When the conductive layer is formed of a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably 0 μm or less. .1 μm or less. When the thickness of the outermost conductive layer is equal to or greater than the lower limit and equal to or less than the upper limit, the coating with the outermost conductive layer becomes uniform, the corrosion resistance becomes sufficiently high, and the connection resistance between the electrodes is further increased. Lower. When the outermost layer is a gold layer, the cost is lower as the thickness of the gold layer is smaller.

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

  The conductive particles may have protrusions on the outer surface of the conductive layer. It is preferable that the number of the projections is plural. An oxide film is often formed on the surface of the conductive layer and the surface of the electrode connected by the conductive particles. In the case where conductive particles having protrusions are used, the oxide film is effectively removed by the protrusions by arranging the conductive particles between the electrodes and pressing the electrodes together. For this reason, the electrode and the conductive layer of the conductive particles can be more reliably brought into contact, and the connection resistance between the electrodes can be reduced. Further, when the conductive particles are provided with an insulating material on the surface, or when the conductive particles are dispersed in a binder resin and used as a conductive material, the protrusions of the conductive particles cause the conductive particles and the electrodes to be in contact with each other. An insulating material or a binder resin therebetween can be effectively eliminated. For this reason, the reliability of conduction between the electrodes can be improved.

  As a method of forming protrusions on the surface of the conductive particles, a method of forming a conductive layer by electroless plating after attaching a core substance to the surface of the substrate particles, and an electroless plating method on the surface of the substrate particles A conductive material is formed thereon, a core substance is adhered thereto, and a conductive layer is formed by electroless plating. In addition, the core material may not be used to form the projection.

  The conductive particles may include an insulating substance disposed on an outer surface of the conductive layer. In this case, when the conductive particles are used for connection between the electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, an insulating substance is present between the plurality of electrodes, so that a short circuit between not only upper and lower electrodes but also horizontally adjacent electrodes can be prevented. When the conductive particles are pressurized by the two electrodes at the time of connection between the electrodes, the insulating substance between the conductive layer of the conductive particles and the electrode can be easily removed. When the conductive particles have protrusions on the surface of the conductive layer, the insulating substance between the conductive layer of the conductive particles and the electrode can be more easily removed. The insulating substance is preferably an insulating resin layer or insulating particles, and more preferably insulating particles. The insulating particles are preferably insulating resin particles.

(Conductive material)
The conductive material includes the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in a binder resin and used as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is suitably used for electrical connection of electrodes. The conductive material is preferably a circuit connecting material.

  The binder resin is not particularly limited. As the binder resin, a known insulating resin is used. Examples of the binder resin include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, and an elastomer. As the binder resin, only one kind may be used, or two or more kinds may be used in combination.

  Examples of the vinyl resin include a vinyl acetate resin, an acrylic resin, and a styrene resin. Examples of the thermoplastic resin include a polyolefin resin, an ethylene-vinyl acetate copolymer, and a polyamide resin. 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 styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and styrene-isoprene. -Hydrogenated products of styrene block copolymers. Examples of the elastomer include a styrene-butadiene copolymer rubber and an acrylonitrile-styrene block copolymer rubber.

  The conductive material may be, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, and a light stabilizer, in addition to the conductive particles and the binder resin. And various additives such as an agent, an ultraviolet absorber, a lubricant, an antistatic agent and a flame retardant.

  A method for dispersing the conductive particles in the binder resin may be a conventionally known dispersion method, and is not particularly limited. Examples of a method of dispersing the conductive particles in the binder resin include, for example, a method of adding the conductive particles to the binder resin, kneading and dispersing the mixture with a planetary mixer, or dispersing the conductive particles in water. Or after uniformly dispersed in an organic solvent using a homogenizer or the like, added to the binder resin, a method of kneading and dispersing with a planetary mixer or the like, and diluting the binder resin with water or an organic solvent or the like Thereafter, a method of adding the above-mentioned conductive particles, kneading and dispersing the mixture with a planetary mixer, or the like can be used.

  The conductive material 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 containing no conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

  In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, further preferably 50% by weight or more, particularly preferably 70% by weight or more, and preferably 99.% or more. It is at most 99% by weight, more preferably at most 99.9% by weight. When the content of the binder resin is equal to or more than the lower limit and equal to or less than the upper limit, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target member connected by the conductive material is further increased.

  In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 40% by weight or less, more preferably 20% by weight or less, It is more preferably at most 10% by weight. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, conduction reliability between the electrodes is further increased.

(Connection structure and liquid crystal display element)
A connection structure can be obtained by connecting the connection target members using the above-described conductive particles or using a conductive material including the above-described conductive particles and a binder resin.

  The connection structure includes a first connection target member, a second connection target member, and a connection portion connecting the first connection target member and the second connection target member. Is preferably a connection structure formed of the above-described conductive particles or a conductive structure including the above-described conductive particles and a binder resin. When the conductive particles are used alone, the connecting portions themselves are the conductive particles. That is, the first and second connection target members are connected by the conductive particles. The conductive material used for obtaining the connection structure is preferably an anisotropic conductive material.

  It is preferable that the first connection target member has a first electrode on a surface. The second connection target 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.

  FIG. 4 is a front sectional view schematically showing a connection structure using the conductive particles 1 shown in FIG.

  The connection structure 51 shown in FIG. 4 includes a first connection target member 52, a second connection target member 53, and a connection connecting the first connection target member 52 and the second connection target member 53. A portion 54. The connection portion 54 is formed of a conductive material including the conductive particles 1 and a binder resin. In FIG. 4, the conductive particles 1 are schematically illustrated for convenience of illustration. Instead of the conductive particles 1, other conductive particles such as the conductive particles 21 and 31 may be used.

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

The method for manufacturing the connection structure is not particularly limited. As an example of a method of manufacturing a connection structure, a method of disposing the conductive material between a first connection target member and a second connection target member, obtaining a laminate, and then heating and pressing the laminate. And the like. The pressure for the pressurization is about 9.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. The heating temperature is about 120 to 220 ° C. The pressure for connecting the electrodes of the flexible printed circuit board, the electrodes arranged on the resin film, and the electrodes of the touch panel is about 9.8 × 10 ^{4 to} 1.0 × 10 ⁶ Pa.

  Specific examples of the connection target member include electronic components such as a semiconductor chip, a capacitor and a diode, and electronic components such as a circuit board such as a printed board, a flexible printed board, a glass epoxy board, and a glass board. The conductive material is preferably a conductive material for connecting electronic components. The conductive paste is a paste-like conductive material, and is preferably applied to the connection target member in a paste-like state.

  The conductive particles and the conductive material are also suitably used for a touch panel. Therefore, it is also preferable that the connection target member is a flexible substrate or a connection target member having electrodes disposed on the surface of a resin film. The connection target member is preferably a flexible substrate, and is preferably a connection target member having electrodes disposed on a surface of a resin film. When the flexible substrate is a flexible printed substrate or the like, the flexible substrate generally has electrodes on its surface.

  Examples of the electrodes 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 member to be connected is a flexible substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. When the electrode is an aluminum electrode, the electrode may be an electrode formed only of aluminum, or may be an electrode in which an aluminum layer is laminated on a surface of a metal oxide layer. Examples of the material of 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.

  Further, the base particles are suitably used as a spacer for a liquid crystal display element. That is, the base particles comprise a pair of substrates constituting a liquid crystal cell, a liquid crystal sealed between the pair of substrates, and a liquid crystal display element spacer disposed between the pair of substrates. It is suitably used for obtaining. The liquid crystal display element spacer may be included in a peripheral sealant.

  FIG. 5 is a cross-sectional view of a liquid crystal display device using the base particles according to one embodiment of the present invention as a spacer for a liquid crystal display device.

The liquid crystal display element 81 shown in FIG. 5 has a pair of transparent glass substrates 82. The transparent glass substrate 82 has an insulating film (not shown) on the opposite surface. As a material of the insulating film, for example, SiO ₂ or the like can be used. A transparent electrode 83 is formed on the transparent glass substrate 82 on the insulating film. Examples of the material of the transparent electrode 83 include ITO. The transparent electrode 83 can be formed by patterning, for example, by photolithography. An alignment film 84 is formed on the transparent electrode 83 on the surface of the transparent glass substrate 82. Polyimide or the like is cited as a material of the alignment film 84.

  Liquid crystal 85 is sealed between the pair of transparent glass substrates 82. A plurality of base particles 11 are arranged between the pair of transparent glass substrates 82. The base particles 11 are used as a spacer for a liquid crystal display element. The interval between the pair of transparent glass substrates 82 is regulated by the plurality of base particles 11. A sealant 86 is arranged between the edges of the pair of transparent glass substrates 82. The sealant 86 prevents the liquid crystal 85 from flowing out. The sealant 86 contains base particles 11A that differ only in the particle size from the base particles 11.

In the above liquid crystal display element, the arrangement density of the liquid crystal display element spacer per 1 mm ² is preferably 10 pieces / mm ² or more, and more preferably 1000 pieces / mm ² or less. When the arrangement density is 10 cells / mm ² or more, the cell gap becomes even more uniform. When the arrangement density is 1000 / mm ² or less, the contrast of the liquid crystal display element is further improved.

  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) Preparation of base particles Preparation of core)
300 parts by weight of divinylbenzene (purity: 57%) and 700 parts by weight of ethylene glycol dimethacrylate were mixed to obtain a mixed solution. To the obtained mixture, 20 parts by weight of benzoyl peroxide was added, and the mixture was stirred until it was uniformly dissolved to obtain a monomer mixture. 4000 parts by weight of a 2% by weight aqueous solution obtained by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction vessel. The obtained monomer mixed solution was put therein, and stirred for 4 hours to adjust the particle size so that the monomer droplets had a predetermined particle size. Thereafter, a reaction was carried out for 9 hours in a nitrogen atmosphere at 85 ° C., and a polymerization reaction of monomer droplets was carried out to obtain particles. The obtained particles were washed several times with hot water, methanol and acetone, respectively, and then subjected to a classification operation to collect several types of polymer particles (organic cores) having different particle sizes.

  In Example 1, polymer particles (organic core) having a particle size of 2.51 μm were prepared among the polymer particles collected by the classification operation.

Preparation of core-shell particles)
60 parts by weight of the obtained polymer particles (organic core), 12 parts by weight of a surfactant, hexadecyltrimethylammonium bromide, and 54.7 parts by weight of a 40% by weight aqueous methylamine solution were mixed with 1800 parts by weight of acetonitrile and It was put in 40 parts by weight of pure water and mixed to obtain a dispersion of polymer particles. To this dispersion, 300 parts by weight of tetraethoxysilane was added to carry out a condensation reaction by a sol-gel reaction. A condensate of tetraethoxysilane was precipitated on the surface of the polymer particles to form a shell and obtain particles. The obtained particles were washed twice with hot water, twice with methanol, and once with acetone, and dried to obtain core-shell particles (base particles). The particle size of the obtained core-shell particles was 3.01 μm. From the core particle size and the core-shell particle size, the shell thickness was calculated to be 0.25 μm.

(2) Preparation of conductive particles The obtained base particles were washed and dried. Thereafter, a nickel layer was formed on the surfaces of the obtained base particles by electroless plating to prepare conductive particles. The thickness of the nickel layer was 0.1 μm.

(Example 2)
In the production of the core, 300 parts by weight of divinylbenzene (purity 57%) and 700 parts by weight of ethylene glycol dimethacrylate were changed to 950 parts by weight of 1,4-butanediol diacrylate and 50 parts by weight of ethylene glycol dimethacrylate. Except for this, core-shell particles and conductive particles having a core particle size of 2.50 μm and a shell thickness of 0.26 μm were obtained in the same manner as in Example 1.

(Example 3)
By changing the particle size of the core from 2.51 μm to 2.78 μm, and by changing the amount of tetraethoxysilane added from 300 parts by weight to 140 parts by weight, the particle size of the core-shell particles was changed from 3.01 μm to 3.0 parts by weight. Conductive particles were obtained in the same manner as in Example 1 except that the thickness was changed to 02 µm (the thickness of the shell was 0.12 µm).

(Example 4)
Core-shell particles and conductive particles were obtained in the same manner as in Example 1, except that the core-shell particles obtained in Example 1 were fired at 250 ° C. for 2 hours in a nitrogen atmosphere. The firing changed the core particle size from 2.51 μm to 2.49 μm and the shell thickness from 0.25 μm to 0.24 μm.

(Example 5)
(1) Palladium attachment step The base particles obtained in Example 1 were prepared. The obtained base particles were etched and washed with water. Next, the resin particles were added to 100 mL of a palladium catalyzed liquid containing 8% by weight of a palladium catalyst, followed by stirring. Then, it was filtered and washed. The base particles were added to a 0.5% by weight dimethylamine borane solution having a pH of 6 to obtain base particles to which palladium was attached.

(2) Core substance attachment step The base particles to which palladium was attached were stirred and dispersed in 300 mL of ion-exchanged water for 3 minutes to obtain a dispersion. Next, 1 g of a metal nickel particle slurry (average particle size: 100 nm) was added to the dispersion over 3 minutes to obtain base particles to which a core substance was attached.

(3) Electroless Nickel Plating Step In the same manner as in Example 1, a nickel layer was formed on the surface of the base particles to prepare conductive particles. The thickness of the nickel layer was 0.1 μm.

(Example 6)
(1) Preparation of Insulating Particles In 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, 100 mmol of methyl methacrylate and N, N, N-trimethyl A monomer composition containing 1 mmol of -N-2-methacryloyloxyethylammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride was subjected to ion-exchanged water so that the solid content was 5% by weight. After stirring at 200 rpm, polymerization was carried out at 70 ° C. for 24 hours in a nitrogen atmosphere. After completion of the reaction, the resultant was freeze-dried to obtain insulating particles having an ammonium group on the surface, an average particle diameter of 220 nm and a CV value of 10%.

  The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of the insulating particles.

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

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

(Example 7)
By changing the core particle size from 2.51 μm to 1.51 μm and changing the amount of tetraethoxysilane from 300 parts by weight to 415 parts by weight, the particle size of the core-shell particles was changed from 3.01 μm to 2. Conductive particles were obtained in the same manner as in Example 1 except that the thickness was changed to 01 µm (the thickness of the shell was 0.25 µm).

(Comparative Example 1)
In the preparation of the core, 300 parts by weight of divinylbenzene (purity 57%) and 700 parts by weight of ethylene glycol dimethacrylate were changed to 600 parts by weight of divinylbenzene (purity 96%) and 400 parts by weight of isobornyl acrylate. Except for this, core-shell particles and conductive particles were obtained in the same manner as in Example 1.

(Comparative Example 2)
In the production of the core, in the same manner as in Example 1 except that 300 parts by weight of divinylbenzene (purity: 57%) and 700 parts by weight of ethylene glycol dimethacrylate were changed to 1000 parts by weight of divinylbenzene (purity: 96%). , Core-shell particles and conductive particles were obtained.

(Comparative Example 3)
Except that 300 parts by weight of divinylbenzene (57% purity) and 700 parts by weight of ethylene glycol dimethacrylate were changed to 75 parts by weight of ethylene glycol dimethacrylate, 850 parts by weight of isobornyl acrylate, and 75 parts by weight of cyclohexyl methacrylate. In the same manner as in Example 1, core-shell particles and conductive particles were obtained.

(Evaluation)
(1) Particle Size of Base Particles, Particle Diameter of Core, and Shell Thickness About 100,000 particle diameters of the obtained base particles were measured using a particle size distribution analyzer (“Multisizer 4” manufactured by Beckman Coulter, Inc.). The average particle size and the standard deviation were measured. The particle size of the core used in preparing the base particles was also measured by the same method. The shell thickness was determined from the difference between the average value of the particle size of the base particles and the average value of the particle size of the core. One half of the difference is the thickness of the shell.

(2) Compression modulus of base particles (10% K value and 30% K value)
The above-mentioned compression elastic modulus (10% K value and 30% K value) of the obtained base material particles was measured at 23 ° C. by a method described above using a micro-compression tester (“Fischer Scope H-100” manufactured by Fischer). ). 10% K value / 30% K value was determined.

(3) The compression recovery rate of the core and the base particles The compression recovery rate X of the core and the compression recovery rate Y of the base particles were measured by the above-mentioned method using a micro-compression tester (Fischer Scope H manufactured by Fischer). -100 "). The compression recovery ratio (X / Y) was determined.

(4) Breaking strain rate of core and shell Using a micro-compression tester (Fisher Scope H-100 manufactured by Fischer) at 23 ° C, the breaking strain rate of the core and shell was measured by the method described above. did.

(5) Connection resistance Preparation of connection structure:
10 parts by weight of a bisphenol A type epoxy resin ("Epicoat 1009" manufactured by Mitsubishi Chemical Corporation), 40 parts by weight of acrylic rubber (weight average molecular weight: about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent (Asahi Kasei E-Material) 50 parts by weight of "HX3941HP" manufactured by Toray Industries, Inc. and 2 parts by weight of a silane coupling agent ("SH6040" manufactured by Dow Corning Toray Silicone Co., Ltd.) were added, and conductive particles were added to a content of 3% by weight. And dispersed to obtain a resin composition.

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

  The obtained anisotropic conductive film was cut into a size of 5 mm × 5 mm. The cut anisotropic conductive film was placed on a glass substrate (width 3 cm, length 3 cm) provided with an aluminum electrode (height: 0.2 μm, L / S = 20 μm / 20 μm) having a lead wire for resistance measurement on one side. ) Was attached to almost the center of the aluminum electrode. Next, a two-layer flexible printed board (width 2 cm, length 1 cm) provided with the same aluminum electrode was aligned and then bonded so that the electrodes overlap. The laminate of the glass substrate and the two-layer flexible printed circuit board was thermocompression bonded under the conditions of 10 N, 180 ° C., and 20 seconds to obtain a connection structure.

Measurement of connection resistance:
The connection resistance between the opposing electrodes of the obtained connection structure was measured by a four-terminal method.

[Evaluation criteria for connection resistance]
○: Connection resistance is 3.0Ω or less ○: Connection resistance is more than 3.0Ω and 4.0Ω or less △: Connection resistance is more than 4.0Ω and 5.0Ω or less ×: Connection resistance is more than 5.0Ω

(6) Retentivity of particles in the connection structure Using the anisotropic conductive film and the connection structure obtained in the above (5) Evaluation of connection resistance, the number of conductive particles on the anisotropic conductive film per unit area By measuring (a) and the number of conductive particles (b) on the connection structure after thermocompression bonding with a 200-fold optical microscope, the particle retention property (b / a) of the connection structure was determined based on the following criteria. Judged.

[Evaluation criteria for particle retention property of connection structure]
○: Particle retention of 0.5 or more ：: Particle retention of 0.4 or more, less than 0.5 Δ: Particle retention of 0.3 or more, less than 0.4 ×: Particle retention of 0.3 Less than

  The results are shown in Table 1 below.

(7) Example of use as spacer for liquid crystal display element Fabrication of STN type liquid crystal display element:
In a dispersion medium containing 70 parts by weight of isopropyl alcohol and 30 parts by weight of water, the liquid crystal display element spacers (base particles) of Examples 1 to 7 before heating were solid-concentrated in 100% by weight of the obtained spacer dispersion liquid. Was added so as to be 2% by weight, followed by stirring to obtain a liquid crystal display element spacer dispersion liquid.

After depositing a SiO ₂ film on one surface of a pair of transparent glass plates (50 mm in length, 50 mm in width, and 0.4 mm in thickness) by a CVD method, an ITO film was formed on the entire surface of the SiO ₂ film by sputtering. A polyimide alignment film composition (product number: SE3510, manufactured by Nissan Chemical Industries, Ltd.) was applied to the obtained glass substrate with an ITO film by spin coating, and baked at 280 ° C. for 90 minutes to form a polyimide alignment film. After the rubbing treatment was performed on the alignment film, liquid crystal display element spacers were wet-sprayed on the alignment film side of one of the substrates so that the number of spacers was 100 per 1 mm ² . After a sealant was formed around the other substrate, this substrate and the substrate on which the spacers were scattered were disposed so as to face each other so that the rubbing direction was 90 °, and the two were bonded. Thereafter, the sealing agent was cured by treating at 160 ° C. for 90 minutes to obtain an empty cell (a screen containing no liquid crystal). An STN-type liquid crystal (manufactured by DIC) containing a chiral agent is injected into the obtained empty cell, and then the injection port is closed with a sealant, followed by heat treatment at 120 ° C. for 30 minutes to obtain an STN-type liquid crystal display element. Obtained.

  In the obtained liquid crystal display device, the spacing between the substrates was well regulated by the liquid crystal display device spacers before heating in Examples 1 to 7. In addition, the liquid crystal display element showed good display quality. In addition, as a result of applying a shock to the liquid crystal display device using the spacer for a liquid crystal display device of Examples 1 to 7, the display quality of the liquid crystal display device was favorably maintained even after the application of the shock. In addition, even when the base particles of Examples 1 to 7 were used as a liquid crystal display element spacer as a peripheral sealant of the liquid crystal display element, the display quality of the obtained liquid crystal display element was good.

DESCRIPTION OF SYMBOLS 1 ... Conductive particle 2 ... Conductive layer 11 ... Base particle 11A ... Base particle 12 ... Core 13 ... Shell 21 ... Conductive particle 22 ... Conductive layer 22A ... 1st conductive layer 22B ... 2nd conductive layer 31 ... Conductive particles 31a Projection 32 Conductive layer 32a Projection 33 Core material 34 Insulating material 51 Connection structure 52 First connection target member 52a First electrode 53 Second connection target member 53a ··· Second electrode 54 ··· Connection part 81 · · · Liquid crystal display element 82 · · · Transparent glass substrate 83 · · · Transparent electrode 84 · Alignment film 85 · Liquid crystal 86 · Sealant

Claims (15)

A core, and a shell disposed on a surface of the core,
The core is formed of an organic compound,
The shell is formed of a metal oxide,
The ratio of the compression modulus when the base particles are compressed by 10% to the compression modulus when the base particles are compressed by 30% is 1.5 or more;
The base particles, wherein a ratio of the compression recovery of the core to the compression recovery of the base particles is 1 or more. A core, and a shell disposed on a surface of the core,
The ratio of the compression modulus when the base particles are compressed by 10% to the compression modulus when the base particles are compressed by 30% is 1.5 or more;
The ratio of the compression recovery of the core to the compression recovery of the base particles is 1 or more,
A fracture strain rate of the core is 50% or more;
The base particles, wherein the fracture strain rate of the shell is 10% or more and 30% or less. A core, and a shell disposed on a surface of the core,
The ratio of the compression modulus when the base particles are compressed by 10% to the compression modulus when the base particles are compressed by 30% is 1.5 or more;
The ratio of the compression recovery of the core to the compression recovery of the base particles is 1 or more,
Base particles, wherein the shell is formed by forming a metal alkoxide into a shell-like material on a surface of the core by a sol-gel method and then firing the shell-like material. Compression modulus when the base particles were compressed 10% 3000N / mm ² or more and 10000 N / mm ² or less, the substrate particles according to any one of claims 1-3. The base particles according to any one of claims 1 to 4 , wherein the shell has a thickness of 50 nm or more and 500 nm or less. Compressive modulus upon compression of the base particle 30% 1000 N / mm ² or more and 4000 N / mm ² or less, the substrate particles according to any one of claims 1-5. The base particles according to any one of claims 1 to 6 , wherein a compression recovery rate of the base particles is 25% or more. The base particles according to any one of claims 1 to 7 , wherein the base particles are not covalently bonded between the core and the shell. The base material according to any one of claims 1 to 8 , wherein a conductive layer is formed on a surface, and is used to obtain conductive particles having the conductive layer, or is used as a spacer for a liquid crystal display element. particle. The base particles according to claim 9 , wherein a conductive layer is formed on a surface and used to obtain conductive particles having the conductive layer. The substrate particles according to any one of claims 1 to 10 ,
A conductive layer disposed on a surface of the base particle. The conductive particles according to claim 11 , further comprising an insulating material disposed on an outer surface of the conductive layer. Having protrusions on an outer surface of the conductive layer, the conductive particle according to claim 11 or 12. Including conductive particles and a binder resin,
A conductive material, wherein the conductive particles include the base particles according to any one of claims 1 to 10 and a conductive layer disposed on a surface of the base particles. A first connection target member having a first electrode on its surface;
A second member to be connected having a second electrode on its surface;
A connection portion connecting the first connection target member and the second connection target member,
The connection portion is formed of conductive particles, or is formed of a conductive material including the conductive particles and a binder resin,
The conductive particles, comprising a base particle according to any one of claims 1 to 10 , and a conductive layer disposed on a surface of the base particle,
A connection structure, wherein the first electrode and the second electrode are electrically connected by the conductive particles.

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