KR20060052782A - Coated conductive particle, anisotropic conductive material, and conductive connection structure - Google Patents

Abstract

Disclosed is a coated conductive particle which can be preferably used for conductively connecting electronic devices or electronic components with high connection reliability. Also disclosed are an anisotropic conductive material using the coated conductive particle and a conductive connection structure which is conductively connected using the coated conductive particle or the anisotropic conductive material. The coated conductive particle is composed of a particle having a conductive metallic surface and insulating fine particles covering the surface of the particle having a conductive metallic surface. The particle having a conductive metallic surface has a plurality of projections on the surface.

Description

Coated electroconductive particle, anisotropic conductive material, and conductive connection structure {COATED CONDUCTIVE PARTICLE, ANISOTROPIC CONDUCTIVE MATERIAL, AND CONDUCTIVE CONNECTION STRUCTURE}

The present invention relates to coated conductive particles, anisotropic conductive materials, and conductive bonded structures excellent in connection reliability.

Particles having a metal surface are used as various resin fillers and modifiers, and are mixed with binder resins as conductive fine particles, and small electric parts such as semiconductor devices are used as electronic engineering products such as liquid crystal displays, personal computers, and mobile communication devices. It is also used as an so-called anisotropic conductive material for electrically connecting or electrically connecting boards.

In recent years, as electronic devices or electronic components have become smaller, wiring of substrates and the like has become finer, so that fine particles of conductive fine particles or improvement in particle diameter precision have been planned. In order to ensure high connection reliability, it is necessary to increase the compounding amount of the conductive fine particles in the anisotropic conductive material. In such a substrate having such fine wiring, lateral conduction by adjacent conductive fine particles occurs, such that a short circuit between adjacent electrodes occurs. There was a problem that it may occur. In order to solve this problem, the anisotropic conductive material using the coated electroconductive particle which coat | covered the surface of electroconductive fine particle with the insulator is proposed. In the coated conductive fine particles, electrical insulation is achieved by the insulator of the element, and the conductive part is exposed by partially removing the insulator by exposing the thermal compressive force or the like, so that conduction can be achieved.

As a method of coating the surface of such electroconductive fine particles with an insulator, for example, Patent Document 1 describes a method of microencapsulating with resin by performing interfacial polymerization, suspension polymerization, emulsion polymerization, and the like in the presence of conductive fine particles. 2 describes a method of microencapsulating by dipping method of dispersing conductive fine particles in a resin solution and then drying, and Patent Document 3 describes a method by spray drying and hybridization. This is known.

However, in such a method, it is difficult to make constant the thickness of an insulating coating layer, and it may apply | coat several electroconductive fine particles simultaneously. In the case of conducting conductive connection using coated conductive particles, even when the particle diameter of the conductive fine particles is highly controlled, if the thickness of the insulating coating layer is uneven, the pressure is not evenly transmitted when fixed between the electrodes by heat or pressure, resulting in poor conduction. Easier For example, the formation method of the insulation coating by hybridization mentioned above is a method of attaching the insulating particle which becomes a coating layer to the surface of electroconductive fine particles with a physical force, so that a coating layer cannot be formed in a single layer on the surface of electroconductive fine particles, and an insulating coating layer Control of the thickness of the resin powder was difficult, and uniform coating was difficult because the resin powder melted and deformed due to heat or impact caused by heating or frictional heat. In addition, since the contact area between the fine resin powder and the metal surface becomes large, when used in an apparatus which is difficult to apply heat or pressure, such as a liquid crystal element, it is difficult to remove the insulating coating layer, resulting in problems such as poor conduction.

Patent document 4 and patent document 5 describe coated electroconductive particle formed by weakly adhering insulating particle to the surface of electroconductive fine particle by electrostatic interaction or a hybridization method. However, in the case of the coated conductive particles obtained by this method, the bonding force between the insulating particles and the conductive fine particles is very weak because they are caused only by van der Waals or electrostatic forces, and the insulating particles are peeled off when dispersed in the binder resin or by contact of adjacent particles. There was a problem that sufficient insulation cannot be secured. On the other hand, when such insulating particles are bonded to the surface of the conductive fine particles with a strong bonding force, there is a concern that the insulating particles do not peel off and may not conduct even when thermally compressed.

In addition, conductive fine particles are often dispersed in an insulating binder resin to be used as an anisotropic conductive material. However, when conducting conductive connection using such an anisotropic conductive material, poor conduction occurs when attempting to speed up the conductive connection process to increase production efficiency. There was also the problem of being easy. This was considered to be because the binder resin between the electrode and the conductive fine particles could not be sufficiently excluded when the connection was to be made at high speed, and the binder resin remained between the electrode and the conductive fine particles.

Patent Document 1: Japanese Patent Application Laid-Open No. 4-362104

Patent Document 2: Japanese Patent Application Laid-Open No. 62-40183

Patent Document 3: Japanese Patent Application Laid-Open No. 7-105716

Patent Document 4: Japanese Patent Application Laid-Open No. 4-259766

Patent Document 5: Japanese Patent Application Laid-Open No. 3-112011

<Start of invention>

In view of the above phenomenon, an object of the present invention is to provide coated conductive particles, anisotropic conductive materials, and conductive connecting structures excellent in connection reliability.

The present invention is coated conductive particles comprising particles having a surface containing a conductive metal and insulating particles covering the surface of the particles having a surface containing the conductive metal, and having a surface containing the conductive metal. Particles are coated conductive particles having a plurality of projections on the surface.

This invention is explained in full detail below.

The coated electroconductive particle of this invention contains the particle | grains which have a surface containing electroconductive metal (henceforth a "metal surface particle"), and the insulating fine particle which coat | covers the said metal surface particle. Thus, when conducting connection of a substrate or the like using the coated conductive particles of the present invention by coating the surface of the metal surface particles with insulating particles, lateral conduction by adjacent conductive fine particles, etc., even on a substrate having fine wiring, etc. While this does not occur, the metal surface of the metal surface particles is exposed and can be reliably connected by thermal compression with application of heat and pressure in the longitudinal direction.

The said metal surface particle has a some processus | protrusion on the surface. By having a plurality of projections on the surface, when used as an anisotropic conductive material, the exclusion of the binder resin between the electrode and the coated conductive particles is increased, and it is possible to reliably conduct even at high speed. Moreover, even if an oxide film is formed in the aluminum electrode to connect by having such a process, it can penetrate and conduct, and connection reliability becomes high.

The above metal surface particles are not particularly limited as long as the outermost layer contains a conductive metal and have projections on the surface thereof. Examples include particles containing only metals; Particles in which a metal layer is formed on the surface of a core particle including an organic compound or an inorganic compound by vapor deposition, plating, and coating; The particle | grains which the metal fine particle introduce | transduced into the surface of an insulating core particle, etc. are mentioned. Among them, the conductive metal layer is formed on the surface of the core particles containing the resin. In the case where the coated conductive particles of the present invention are used for the anisotropic conductive material, the connection between the electrodes can be deformed at the time of crimping and the bonding area can be increased, so that the bonding area can be increased. Preferred at

Although it does not specifically limit as said core particle, For example, Polyolefins, such as polyethylene, a polypropylene, polystyrene, polypropylene, polyisobutylene, polybutadiene, acrylic resins, such as polymethylmethacrylate and polymethylacrylate, polyalkyl Phenolic resins such as lenterephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, melamine resins such as melamine formaldehyde resin, benzoguanamine resins such as benzoguanamine formaldehyde resin, urea formaldehyde resin And epoxy resins, (un) saturated polyester resins, polyethylene terephthalates, polysulfones, polyphenylene oxides, polyacetals, polyamides, polyamideimide, polyether ether ketones, polyether sulfones, and the like. . Especially, what uses the resin formed by superposing | polymerizing the 1 type (s) or 2 or more types of various polymerizable monomers which have an ethylenically unsaturated group is preferable because it is easy to obtain suitable hardness.

The polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer or a crosslinkable monomer.

As said non-crosslinkable monomer, For example, Styrene-type monomers, such as styrene, a-methylstyrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene; Carboxyl group-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 (meth) acrylate, isobornyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoromethyl (meth) acrylate, pentafluoropropyl Alkyl (meth) acrylates such as (meth) acrylate; Oxygen atom-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, glycerol (meth) acrylate, polyoxyethylene (meth) acrylate and glycidyl (meth) acrylate; Nitrile-containing monomers such as (meth) acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; Acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate, vinyl stearate, vinyl fluoride, vinyl chloride and vinyl propionate; And unsaturated hydrocarbons such as ethylene, propylene, butylene, methylpentene, isoprene and butadiene.

As said crosslinkable monomer, tetramethylol methane tetra (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane di (meth) acrylate, trimethylol propane tri (meth) acrylate, for example. , Dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate; Polyfunctional (meth) acrylates such as glycerol di (meth) acrylate, polyethylene glycol di (meth) acrylate and polypropylene glycol di (meth) acrylate; Triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, diallyl acrylamide, diallyl ether and the like; silane-containing monomers such as γ- (meth) acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane; Dicarboxylic acids such as phthalic acid; Diamines; Diallyl phthalate, benzoguanamine, triallyl isocyanate, etc. are mentioned.

The minimum with preferable average particle diameter of the said core particle is 0.5 micrometer, and a preferable upper limit is 100 micrometers. If the thickness is less than 0.5 µm, agglomeration is likely to occur when the metal layer is formed. The coated conductive particles produced by using the core particles that have agglomerated tend to cause a short circuit between adjacent electrodes, and when the thickness exceeds 100 µm, the metal layer of the coated conductive particles obtained. Since this peels off easily, there exists a tendency for reliability to fall. The minimum with more preferable is 1 micrometer, and a more preferable upper limit is 20 micrometers. In addition, the average particle diameter of the said core particle can be calculated | required by statistically processing the particle diameter measured using the optical microscope, the electron microscope, a particle size distribution meter, etc.

 It is preferable that the variation coefficient of the average particle diameter of the said core particle is 10% or less. When it exceeds 10%, it becomes difficult to arbitrarily control the electrode space | interval which mutually opposes using the covered electroconductive particle obtained. The coefficient of variation is a numerical value obtained by dividing the standard deviation obtained from the particle size distribution by the average particle diameter.

The minimum with preferable 10% K value of the said core particle is 1000 MPa, and a preferable upper limit is 15000 MPa. If it is less than 1000 MPa, the strength of the coated conductive particles obtained is insufficient, so that the particles are broken when compression-deformed, and the function as a conductive material tends not to be completed, and if it exceeds 15000 MPa, the electrode tends to be damaged. The minimum with more preferable is 2000 MPa, and a more preferable upper limit is 10000 MPa. The 10% K value is a smooth indenter cross section containing a 50 mm-diameter diamond column using a micro compression tester (e.g., PCT-200 manufactured by Shimadzu Corporation). The compression displacement (mm) in the case of compressing under the conditions of mN / sec and the maximum test load of 10 g can be calculated | required by the following formula.

K value ^{(N / ㎜ 2) = (} 3 / √2) · F · S -3/2 · R -1/2

F: Load value (N) at 10% compression set of particles

S: compression displacement (mm) at 10% compression deformation of the particles

R: radius of particles (mm)

In addition, in order to obtain a core particle whose 10% K value satisfies the above conditions, it is preferable that the core particles include a resin obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group as described above. It is more preferable to contain at least 20 weight% or more of a monomer.

It is preferable that a recovery rate of the said core particle is 20% or more. If it is less than 20%, even if it deform | transforms in the case of compressing the coating electroconductive particle obtained, since it does not return to original, there exists a tendency which causes connection defect. More preferably, it is 40% or more. In addition, the said recovery rate means the recovery rate after loading a particle | grain of 9.8 mN.

The metal is not particularly limited as long as it has conductivity, but for example, gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, And metal compounds such as metals such as cadmium and silicon or ITO and solder.

The metal layer may be a single layer structure or a laminated structure including a plurality of layers. When including a laminated structure, it is preferable that outermost layer contains gold. By including gold in the outermost layer, since the corrosion resistance is high and the contact resistance is small, the coated electroconductive particle obtained becomes further excellent.

Although it does not specifically limit as thickness of the said metal layer, A preferable minimum is 0.005 micrometer and a preferable upper limit is 1 micrometer. If it is less than 0.005 µm, a sufficient effect as a conductive layer tends not to be obtained. If it exceeds 1 µm, the specific gravity of the coated conductive particles obtained is too high, or the hardness of the core particles containing the resin is now sufficiently deformable. Tend not to be. The minimum with more preferable is 0.01 micrometer, and a more preferable upper limit is 0.3 micrometer.

In addition, when making an outermost layer of the said metal layer into a gold layer, the minimum with preferable thickness of a gold layer is 0.001 micrometer, and a preferable upper limit is 0.5 micrometer. If it is less than 0.001 micrometer, it will become difficult to coat | cover a metal layer uniformly, and there exists a tendency which cannot anticipate the improvement effect of corrosion resistance or a contact resistance value, and when it exceeds 0.5 micrometer, it is comparatively expensive compared with the effect. The minimum with more preferable is 0.01 micrometer, and a more preferable upper limit is 0.2 micrometer.

Although it does not specifically limit as a method of forming the said electroconductive metal layer, For example, well-known methods, such as a physical metal vapor deposition method and a chemical electroless plating method, are mentioned, In view of the simplicity of a process, an electroless plating method is preferable. Examples of the metal layer that can be formed by the electroless plating method include gold, silver, copper, platinum, palladium, nickel, rhodium, ruthenium, cobalt, tin, and alloys thereof, and the like. Since one coating can be formed at a high density, it is preferable that part or all of the metal layer is formed by electroless nickel plating.

Although it does not specifically limit as a method of forming a gold layer in the outermost layer of the said metal layer, For example, well-known methods, such as electroless plating, substitution plating, electroplating, sputtering, etc. are mentioned.

The surface protrusion of the metal surface particles is not particularly limited as long as the surface of the protrusion is a conductive metal, but may be the same as or different from the metal layer.

The minimum with preferable protrusion height is 0.05 micrometer. If the thickness is less than 0.05 µm, it is difficult to obtain the effect of imparting projections that are easily exposed from the insulating coating layer at the time of connection. The minimum with more preferable is 0.1 micrometer.

The upper limit with preferable protrusion height is 40% of the said metal surface particle diameter. If it exceeds 40%, the projection may be easily bent, may be deeply embedded in the electrode, and may be damaged, or it may be difficult to arbitrarily control the electrode gaps facing each other using the coated conductive particles obtained. More preferably, the upper limit is 20%.

Although it does not specifically limit as the number of the said protrusions, It is preferable that the average number of protrusions per coating electroconductive particle is eight or more. If it is less than 8, there exists a tendency which cannot exhibit stable high connection stability as an effect which provided protrusion.

Although it does not specifically limit as a method of manufacturing the metal surface particle | grains which have such a processus | protrusion, For example, 1) When forming a conductive metal layer on the surface of a core particle, the magnetic particle containing an inorganic material or an organic material is affixed. 2) a method of growing a conductive metal layer while the conductive metal layer is formed on the surface of the core particles, a material having a high affinity for the metal is non-uniformly attached to the surface of the core particle, 3) a method of forming a conductive metal layer while growing a projection containing a conductive metal locally at a portion; and 3) core particles having a surface having magnetic particles containing an organic material or an inorganic material as a projection (hereinafter referred to as 'protrusion particles'). And a conductive metal layer on the surface thereof.

As a specific method of said 1), when the aqueous slurry of the core particle containing resin is added to an electroless plating bath containing a nickel salt, a reducing agent, a complexing agent, etc., electroless nickel plating is performed, The formation of the nickel layer and the self-decomposition of the plating bath are performed at the same time, and this self-decomposition is used as the nucleus of the projection, and the growth of the nickel film and the growth of the projection can be given.

As a specific method of said 2), the palladium chloride is introduce | transduced into the core particle surface, for example, and then the reduction of palladium chloride is performed very smoothly under moderate stirring in the lean liquid of palladium, and the origin of electroless nickel plating is started, for example. Palladium to be formed nonuniformly on the surface of the core particle, and then added to an electroless plating bath containing a nickel salt, a reducing agent and a complexing agent, and the like to perform electroless nickel plating.

In this method, since the deposition rate of nickel is faster than that of the portion containing less palladium in the portion containing more palladium, plating proceeds in the protruding state as a result.

As a specific method of said 3), after producing the processus | protrusion particle which attached the magnetic particle to the core particle surface by various methods, such as hybridization, the metal layer is formed in the surface of the obtained processus particle by electroless nickel plating etc., for example. Method of making; Agglomerated magnetic particles are aggregated or bound to the surface of the polymerizable droplet in which the seed particles are swollen with the polymerizable monomer in a polymerizable droplet or a medium containing at least a polymerizable unsaturated monomer and a polymerizable unsaturated monomer. After producing the particle | grains (protrusion particle) which have a processus | protrusion on the surface by superposing | polymerizing a polymerizable droplet, the method of forming a metal layer by electroless nickel plating etc. on the surface of the obtained processus | protrusion particle | grains, etc. are mentioned.

As a method of forming a conductive metal layer on the surface of the core particles and the fine particles after chemically and / or physically bonding the magnetic particles that become projections on the surface of the core particles, for example, at least a polymerizable unsaturated monomer and a medium. To prepare a dispersion in which polymerizable droplets containing a polymerizable unsaturated monomer are dispersed in a medium, adding magnetic particles to the dispersion, and adhering the magnetic particles to the surface of the polymerizable droplets. The method which has the process of superposing | polymerizing the polymerizable droplet which obtained is a processus | protrusion particle | grain, and the process of metal-plating the obtained protrusion particle | grains are preferable.

As another method, for example, a step of mixing a seed particle and a medium containing a polymerizable unsaturated monomer to prepare a dispersion in which the seed particle is dispersed in the medium, and absorbing the polymerizable unsaturated monomer into the seed particle to polymerize the polymer. A process of preparing droplets, adding magnetic particles to the dispersion to attach the magnetic particles to the surface of the polymerizable droplets, polymerizing the polymerizable droplets to which the magnetic particles are attached, obtaining projection particles, and metal plating the obtained projection particles. Also by the method which has a process, the metal surface particle which has a processus | protrusion can be manufactured.

The insulating fine particles are not particularly limited as long as they are insulating. Examples of the insulating fine particles include insulating resins and insulating inorganic materials such as silica. Especially, it is preferable to contain insulating resin. Although it does not specifically limit as said insulating resin, For example, resin etc. which are used for the core particle mentioned above are mentioned. These resins may be used independently or may use 2 or more types together.

The minimum with preferable particle size of the said insulating fine particle is 5 nm, and a preferable upper limit is 1000 nm. If it is less than 5 nm, the distance between adjacent covering electroconductive particles becomes smaller than the hopping distance of electrons, and it becomes easy to produce a leak, and when it exceeds 1000 nm, the pressure or heat required at the time of thermocompression tends to become large too much. The minimum with more preferable is 10 nm and a more preferable upper limit is 500 nm.

In addition, since small insulating fine particles enter the gap covered by the large insulating fine particles and the coating density can be improved, two or more types of insulating fine particles having different particle diameters can be used together. At this time, it is preferable that the particle diameter of small insulating fine particles is 1/2 or less of the particle size of large insulating fine particles, and it is preferable that the number of small insulating fine particles is 1/4 or less of the number of large insulating fine particles.

Moreover, the ratio of the particle diameter of the said insulating fine particle and the height of a metal surface particle | grain protrusion is not specifically limited, either. 1 to 4 are partial cutaway front cross-sectional views showing examples in which the particle diameter of the insulating fine particles and the height of the metal surface particle projections vary in various ways. For example, as shown in FIG. 1, a plurality of protrusions 11 are formed on the surface of the metal surface particles 1 containing a metal, and the height of the protrusions 11, that is, the metal surface particles 1. The diameter of the insulating fine particles 2 may be larger than the dimension from the surface of the top face to the outermost end of the protrusion 11. 1 and the following FIGS. 2 to 4 point out that only the relationship between the diameter of the insulated fine particles and the projection height is merely shown.

In addition, as shown in FIG. 2, the diameter of the insulating fine particles 2 may be smaller than the height of the protrusions 11 formed on the surface of the metal surface particles 1. In addition, as shown in FIG. 3, a plurality of small insulating fine particles 2 are disposed in comparison with the height of the projections 11 formed to protrude outward from the metal surface particles 1, and the outer surface of the metal surface particles 1 is disposed. It may be coated with this insulating material.

In addition, as shown in FIG. 4, the insulating fine particles 2A having a diameter smaller than the height of the protrusion 11 formed on the surface of the metal surface particles 1 and the large insulating fine particles 2B may be used in combination. . That is, it is also possible to use insulating fine particles of various sizes.

In addition, although the metal surface particle | grains 1 are formed with the metal in FIGS. 1-4, it is the surface of the particle | grain main body 1A containing an insulating material like the metal surface particle | grains 1 shown in FIG. It is also possible to have a structure in which the metal layers 1B and 1C are laminated. Also in this case, the outer surface of the metal surface particles 1 is formed of metal, including the portion where the protrusions 11 are formed. In addition, it is pointed out that the insulating fine particles are not shown in FIG.

As shown in FIG. 6, the metal surface particles 21 are formed by forming a plating film 23 containing metal on the outer surface of the insulating particles 22 as shown on the right side of FIG. 6. It may be. In this case, a sudden plated film growth portion is formed in a part of the plated film 23, and the protruding portion 23a is formed. In this manner, when forming the plated film, the plated film may be partially grown to form a plurality of projection portions 23a. In addition, although the insulating particle 22 can be comprised from a suitable material, it is preferable that it is made from the material which can form the plating film 23 containing a metal. In addition, instead of the insulating particles 22, a metal film is formed on the surface of the particles containing an insulating material, and a plating film 23 may be formed on the metal film.

It is preferable that the CV value of a particle size of the said insulating fine particle is 20% or less. When it exceeds 20%, the thickness of the coating layer of the coated electroconductive particle obtained will become nonuniform, and it will become difficult to apply a pressure uniformly at the time of thermocompression bonding between electrodes, and it exists in the tendency which causes a poor conduction. In addition, the CV value of the said particle diameter can be computed by the following formula.

CV value (%) of particle diameter = standard deviation / mean particle diameter * 100 of particle size

As a measuring method of the said particle size distribution, before coating metal surface particle | grains, it can measure by a particle size distribution meter etc., and after coating, it can measure by image analysis etc. of a SEM photograph.

It is preferable that the said insulating fine particle has a positive charge. By having a positive charge, it can bond with metal surface particle | grains using the hetero agglomeration method mentioned later, and since the said insulating fine particles electrostatically repulse, aggregation of insulating fine particles can be suppressed and a coating layer of a single layer can be formed. That is, when the insulating fine particles are charged to the plus, the insulating fine particles are attached in a single layer on the metal surface particles. In addition, when such a positive charge is based on an ammonium group or a sulfonium group, it also acts as a functional group (A) having a binding property to a metal described later, and the insulating fine particles easily form a chemical bond with the metal on the surface of the metal surface particles. do. Therefore, it is preferable that the said insulating fine particle contains resin which has an ammonium group or a sulfonium group. Especially, it is more preferable to include resin which has a sulfonium group.

As the insulating fine particles having a positive charge, a polymerizable monomer having a positive charge is mixed in the production of the insulating fine particles, polymerized by a radical initiator having a positive charge, a dispersion stabilizer or an emulsifying agent having a positive charge is used. And the like are manufactured. These methods can also be used together 2 or more types. Among these, the method of using the polymerizable monomer which has positive charge, or the method of using a radical initiator is preferable.

Examples of the polymerizable monomer having a positive charge include N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropylacrylamide, N, N, N-trimethyl-N-2-methacryl, and the like. Monomers having sulfonium groups such as ammonium group-containing monomers such as monooxyethylammonium chloride and phenyl dimethyldimethylsulfonium methyl sulfate, and the like. Examples of the radical initiator having the positive charge include 2,2'-azobis {2-methyl-N- [2- (1-hydroxy-butyl)]-propionamide} and 2,2'-azo. Bis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis (2-amidinopropane), salts thereof, and the like.

In the coated electroconductive particle of this invention, it is preferable that the said metal surface particle and insulating fine particle are chemically bonded through the functional group (A) which has a bond with respect to a metal. As a result of chemical bonding, the bonding strength is stronger than the bonding due to van der Waals force or electrostatic force, and the insulating fine particles are peeled off when kneading with the binder resin or the like, or when the coated conductive particles are used as anisotropic conductive materials, Peeling can prevent leakage. On the other hand, as mentioned above, since the said metal surface particle | grains have a processus | protrusion, even if insulated microparticles | fine-particles are firmly adhere | attached, a processus | protrusion pushes insulated microparticles | fine-particles by thermocompression bonding and can reliably connect electrically. This chemical bond is formed only between the metal surface particles and the insulating fine particles, and since the insulating fine particles do not bond with each other, the coating layer made of the insulating fine particles becomes a single layer. From this point of view, when the particle size of the coated conductive particles of the present invention is used as the metal surface particles and the insulating fine particles, the particle size of the coated conductive particles of the present invention can be easily made uniform.

The functional group (A) is not particularly limited as long as it is a group capable of ionic bonds, covalent bonds, and coordinate bonds with metals. Examples of the functional group (A) include silane groups, silanol groups, carboxyl groups, amino groups, ammonium groups, nitro groups, hydroxyl groups, carbonyl groups, and thiol groups. And sulfonic acid group, sulfonium group, boric acid group, oxazoline group, pyrrolidone group, phosphoric acid group and nitrile group. Especially, although the functional group which can coordinate is preferable, the functional group which has S, N, and P atom is used preferably. For example, when a metal is gold, it is preferable that it is a functional group which has S atom which forms a coordination bond with respect to gold, especially a thiol group or a sulfide group.

Although it does not specifically limit as a method of chemically bonding metal surface particle | grains and insulating microparticles | fine-particles using such a functional group (A), For example, 1) Introducing fine particle | grains which have functional group (A) in the surface to the surface of metal surface particle | grains is carried out. Method, 2) a method of introducing a compound having a functional group (A) and a reactive functional group (B) onto a metal surface, and then reacting and reacting the reactive functional group (B) with insulating fine particles by one or a multi-step reaction. Can be mentioned.

In the method of said 1), although it does not specifically limit as a method of manufacturing the insulating fine particle which has a functional group (A) on the surface, For example, the method of incorporating the monomer which has a functional group (A) at the time of manufacture of an insulating fine particle; A method of introducing the functional group (A) by chemical bonding to the surface of the insulating fine particles; A method of chemically treating the surface of the insulating fine particles to a functional group (A); The method of modifying the surface of an insulating fine particle with a functional group (A) by plasma etc. is mentioned.

As the method of said 2), the compound which has a reactive group (B), such as a functional group (A), a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a silyl group, a silanol group, an isocyanate group, etc. in the same molecule | numerator, for example And a method of reacting the particles with the particles and subsequently reacting the organic compound particles having a functional group covalently bonded to the reactive functional group (B) on the surface. As a compound which has a functional group (A) and a reactive functional group (B) in this same molecule, 2-aminoethane thiol, p-aminothiophenol, etc. are mentioned, for example. When 2-aminoethanethiol is used, 2-aminoethanethiol is bonded to the surface of metal surface particles via an SH group, and the insulating fine particles having an epoxy group, a carboxyl group, or the like react with one amino group, for example, Metal surface particles and insulating fine particles can be combined.

When joining between electrodes using the coated electroconductive particle of this invention, it conducts by exposing and heating the metal surface of a metal surface particle by applying heat and pressure and thermocompression bonding. Exposing the metal surface here means that at least a part of the metal surface of the metal surface particles is in a state in which it can directly contact the electrode without being interrupted by the insulating fine particles. Further, the conditions of the thermocompression bonding, but be not limited by the kind of the electronic component which the density or the connection of the coated conductive particles in the anisotropic conductive material, typically a temperature of from 120 to 220 ℃, 9.8 × 10 ⁴ to 4.9 × 10 The pressure is ⁶ Pa.

As an aspect in which the metal surface of a metal surface particle is exposed, the following three aspects are considered.

In a first aspect, the insulating particles are melted by thermocompression bonding to expose the metal surface of the metal surface particles. In the second aspect, the insulating particles are deformed by thermal compression, thereby exposing the metal surface of the metal surface particles. In a third aspect, the metal surface particles and the insulating particles are dissociated by thermocompression bonding to expose the metal surface of the metal surface particles.

Especially, it is preferable that the metal surface of a metal surface particle is exposed and conductive connection is performed by a 2nd aspect. In the case of the first embodiment, the molten insulating particles bleed out, and thus, the coating layer that contaminates the binder resin or the substrate or insulates the adjacent coated conductive particles is melted and does not exhibit sufficient insulation. In the case of the third aspect, when the metal surface particles and the insulating particles are arranged in the direction in which the metal surface particles and the insulating particles are squeezed, the insulating particles are sandwiched between the metal surface particles and the substrate and cannot be dissociated, resulting in low connection reliability. There is a case. In addition, since the metal surface particles have protrusions on the surface, the metal surface of the metal surface particles according to the second and third aspects is easily exposed.

In any of these embodiments, whether the metal surface of the metal surface particles is exposed and conducting a connection is determined by thermocompression conditions or the like, but is usually controlled by the relative relationship between the hardness of the metal surface particles and the hardness of the insulating particles. can do. Here, the hardness of the particles means relative hardness under thermocompression conditions. For example, the softening temperature of the insulating particles is lower than that of the metal surface particles, and the insulating particles are softer when only the insulating particles soften under the thermocompression conditions. I can do it.

In addition, in order to expose the metal surface of metal surface particle | grains, it is preferable to make the area of the part coat | covered by the insulating particle which occupies the coverage of insulating particle, ie, the whole surface area of a metal surface particle, 5 to 50%. If it is less than 5%, insulation of adjacent coating electroconductive particles will become inadequate, and if it exceeds 50%, in the 1st aspect, it will melt | dissolve to the coating layer which insulates between adjacent coating electroconductive particles, and exhibits sufficient insulation. In the case of the second aspect, there is a tendency that the metal surface is not sufficiently exposed even when the insulating particles are deformed and pressed. In the third aspect, the other insulating particles are pushed because the insulating particles in the thermal compression direction dissociate. When it is necessary to cut out or is arranged in the direction in which the metal surface particles and the insulating particles are pressed during thermal compression, the insulating particles tend to be sandwiched or dissociated between the metal surface particles and the substrate.

The adjustment of the relative relationship between the hardness of the metal surface particles and the hardness of the insulating particles will be described again. For example, relatively hard metals, such as copper, nickel, iron, and gold, as said metal surface particle; Relatively hard metal oxides such as aluminum nitride; Inorganic particles such as silica; In the case where a relatively hard one such as a metal layer formed in a core particle containing a resin having a compounding amount of a crosslinkable monomer of 50% by weight or more is selected, metal surface particles according to any one of the embodiments described above are selected as the insulating particles. It is possible to adjust whether the metal surface of is exposed and conductive connection is made.

The method for producing the coated conductive particles of the present invention is not particularly limited as long as it is a method of bringing the insulating fine particles into contact with the surface of the metal surface particles having the projections and chemically bonding them, for example, at least an organic solvent and / or water. Among them, step 1 of agglomerating the insulating fine particles to particles having a surface containing a conductive metal by van der Waals force or electrostatic interaction and step 2 of chemically bonding the particles having a surface containing a conductive metal and the insulating fine particles to each other. Preference is given to a method having The agglomeration method of step 1 is a method called a hetero agglomeration method, and this method does not require more pressure than necessary because the chemical effect between the metal surface particles and the insulating fine particles is not only rapidly and reliably generated by the solvent effect. In addition, since the temperature of the entire system can be easily controlled, the insulating fine particles are hardly deformed due to heat. On the other hand, when the insulating fine particles are introduced by a dry method using a conventional high speed stirrer or a breeder, it is easy to apply a load such as pressure or frictional heat more than necessary, and when the insulating fine particles are harder than the metal surface particles, In some cases, the metal layer may peel off, or when the insulating fine particles are softer than the metal surface particles, or when the glass transition point temperature of the insulating fine particles is lower, the insulating fine particles are deformed due to collision with the metal surface particles or frictional heat. The area may be large, the thickness of the insulating film may be uneven, the insulating fine particles may be laminated or adhered, or the insulating fine particles may be melted and the coated conductive particles may be bonded to each other to form a single particle.

The organic solvent is not particularly limited as long as it does not dissolve the insulating fine particles. Since the coated electroconductive particle of this invention coat | covers the surface of metal surface particle | grains with insulating microparticles | fine-particles, even when used as an anisotropic conductive material, a leak does not arise between adjacent particles. In addition, since there are protrusions on the surface of the metal surface particles, the metal surface of the metal surface particles is easily exposed by thermocompression bonding at the time of connection, and reliable conduction is obtained. In addition, when the metal surface particles and the insulating fine particles are chemically bonded, the bonding force between the insulating fine particles and the metal surface is too weak when kneading the binder resin or the like or when contacting the adjacent particles, so that the insulating fine particles do not peel off. . In addition, since the insulating fine particles form a single coating layer, not only the particle size distribution of the insulating fine particles is small, but also the contact area between the insulating fine particles and the metal surface is constant, the particle size of the coated conductive particles can be made uniform.

The coated electroconductive particle of this invention can be used for uses, such as an anisotropic conductive material, a heat ray reflecting material, and an electromagnetic shielding material. Especially, it can use suitably as an anisotropic material by disperse | distributing in insulating binder resin.

The anisotropic conductive material in which the coating electroconductive particle of this invention is disperse | distributed in insulating binder resin is also one of the characteristics of this invention.

In the present invention, the anisotropic conductive material includes an anisotropic conductive film, an anisotropic conductive paste, an anisotropic conductive adhesive, an anisotropic conductive ink, and the like.

The insulating binder resin is not particularly limited as long as it is insulating. Examples of the insulating binder resin include thermoplastics such as acrylic acid ester, ethylene-vinyl acetate resin, styrene-butadiene block copolymer and its hydrogenated substance, styrene-isopropylene block copolymer and its hydrogenated substance. Suzy; Thermosetting resins such as epoxy resins, acrylic acid ester resins, melanin resins, urea resins, and phenol resins; The resin hardened | cured by ultraviolet-rays, electron beams, etc., such as acrylic acid ester of polyhydric alcohol, polyester acrylate, and unsaturated ester of polyhydric carboxylic acid, etc. are mentioned. Especially, the adhesive agent hardened | cured by heat and / or light is preferable.

In addition to the binder resin which is an essential component and the coating conductive material of this invention, the anisotropic conductive material of this invention is a filler, an extender, a softener, a plasticizer, a polymerization catalyst, and hardening as needed in the range which does not inhibit achievement of the subject of this invention. One kind or two or more kinds of various additives such as catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents and flame retardants may be added.

In the anisotropic electrically-conductive material of this invention, it is preferable that the functional group and the functional group in binder resin which are contained in the insulating particle of the coating conductive particle of this invention contained are chemically bonded. When the insulating particles and the binder resin are combined and combined, not only the stability of the coated conductive particles of the present invention dispersed in the binder resin is excellent, but also the heat-melted insulating particles are bleeded out to not contaminate the electrode or the liquid crystal, and thus long-term connection stability or It becomes an anisotropic conductive material with excellent reliability.

Although it does not specifically limit as a method of disperse | distributing the coating electroconductive particle of this invention in the said binder resin, Although a conventionally well-known dispersion method is used, For example, after adding a coating electroconductive particle in binder resin, a planetary mixer etc. Kneading and dispersing; A method in which the coated conductive particles are uniformly dispersed in water or an organic solvent by using a homogenizer or the like, then added to the binder resin and kneaded by a planetary mixer or the like; After diluting the binder resin with water or an organic solvent or the like, a dispersing method for imparting mechanical shear force such as a method of adding coated conductive particles and kneading and dispersing with a planetary mixer or the like may be used. These dispersion methods may be used alone, or two or more kinds may be used in combination.

In addition, when applying the said mechanical shear force, it is preferable to select and perform a method or conditions suitably so that the mechanical shear force of the grade which destroys the structure of the coating electroconductive particle of this invention disperse | distributed in binder resin is not applied.

Although it does not specifically limit as a method of manufacturing the said anisotropic conductive film, For example, the coating electroconductive particle of this invention is suspended by adding a solvent to binder resin, and this suspension is cast on a mold release film. To form a film, and to wind the evaporated solvent from the film onto a roll. In the electrically conductive connection by the said anisotropic conductive film, the film is wound together with a release film, the film is placed on the electrode to which it adhere | attaches, and the method of connecting by connecting a counter electrode by thermocompression on this is mentioned.

The anisotropic conductive paste can be produced by, for example, forming an anisotropic conductive adhesive into a paste, which is placed in a suitable dispenser, applied to a desired thickness on the electrode to be connected, and the counter electrode is superimposed thereon, and thermally crimped. And hardening resin can be connected.

The anisotropic conductive ink can be prepared, for example, by adding a solvent to the anisotropic conductive adhesive to have a viscosity suitable for printing, which is screen printed onto the electrode to be bonded, and then the solvent is evaporated thereon. The counter electrode can be connected by thermocompression bonding again.

As a coating film thickness of the said anisotropic electrically-conductive material, it calculates from the average particle diameter of the coated electroconductive particle of this invention used, and the specification of a connection electrode, and coated electroconductive particle is pinched between connection electrodes, and the bonding board | substrate is fully sufficient as an adhesive layer. It is desirable to be filled.

The electrically conductive connection structure by which the electronic component, such as an IC chip or a board | substrate, is electrically conductively connected by the coating electroconductive particle of this invention or the anisotropic conductive material of this invention is also one of the characteristics of this invention.

According to this invention, the coating electroconductive particle excellent in connection reliability, an anisotropic conductive material, and an electrically conductive connection structure can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a fragmentary sectional sectional drawing which shows an example of the aspect of coating | covering metal surface particle | grains with insulating fine particles.

2 is a partial cut cross-sectional view showing another example of the aspect of coating of metal surface particles with insulating fine particles.

3 is a partially cut cross-sectional view showing still another example of the coating of metal surface particles with insulating fine particles.

4 is a partial cut cross-sectional view showing another example of the embodiment of the coating of the metal surface particles by the insulating fine particles.

It is a figure which shows the modification of a metal surface particle.

6 is a view showing still another modification of the metal surface particles.

<Brief description of symbols for the main parts of the drawings>

1: metal surface particles

2: insulating fine particles

11: projection part of metal surface particles

21: metal surface particles

22: insulating particles

23: plating film

23a: protrusion

Best Mode for Carrying Out the Invention

Although an Example is given to the following and this invention is demonstrated to it in more detail, this invention is not limited only to these Examples.

<Example 1>

1. Production of Metal Surface Particles with Projections

(1) Preparation of magnetic particles

70 mmol of methyl methacrylate, 10 mmol of glycidyl methacrylate, dimethacryl in a 1000 mL container separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube, and temperature probe 20 mmol of ethylene glycol acid, 3 mmol of phenyl dimethyl sulfonium methyl sulfate, 2,2'-azobis [N- (2-carboxyethyl) -2-methyl-propionamidine] tetrahydrate 3 mmol And after weighing 470 mL of distilled water, it stirred at 200 rpm and superposed | polymerized at 70 degreeC in nitrogen atmosphere for 5 hours, and obtained the magnetic particle which has an epoxy group on the surface. Subsequently, 30 mmol of ethylene diamine were added and the epoxy group was converted into an amino group by making it react at 70 degreeC for 1 hour. After completion of the reaction, unreacted monomers, polymerization initiators and the like were removed by centrifugation, 400 mL of distilled water was added and dispersed by ultrasonic irradiation, and then 30 mmol of glycidyl methacrylate was added thereto, followed by 70 ° C. By reacting at for 1 hour, the amino group was converted into a polymerizable methacryl group. After completion of the reaction, the unreacted substance was removed and washed twice by centrifugation, and then dispersed in distilled water again to obtain a magnetic particle dispersion having a polymerizable functional group on the surface having an average particle diameter of 305 nm, a CV value of 8.8%, and a solid fraction of 10%. Got it.

In addition, the particle diameter and distribution of a magnetic particle were measured using the dynamic light scattering particle size distribution diameter (DLS8000, Otsuka Denshi Corporation make).

(2) Preparation of Seed Particles

500 mmol of styrene, 85 mmol of n-octyl mercaptan, 2 mmol of potassium persulfate, in a 1000 mL container separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube, and temperature probe After weighing 2.5 mmol of sodium chloride and 585 mL of distilled water, the mixture was stirred at 200 rpm, and polymerization was carried out at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, the unreacted monomers, polymerization initiators, and the like were removed and washed twice by centrifugation, and again dispersed with distilled water to obtain a seed particle dispersion having an average particle diameter of 900 nm, a CV value of 3.2%, and a solid fraction of 10%. .

(3) production of protuberant particles

After weighing 10 g of the obtained seed particle dispersion and 90 mL of distilled water in a 500 mL container separable flask equipped with a four-neck separable cover, a stirring blade, a three-way cock, a cooling tube, and a temperature probe, the magnetic particle dispersion obtained while stirring 1 g was added dropwise and the seed particles and the magnetic particles were combined. Next, 0.05 g of sodium lauryl sulfate and 20 g of a polyvinyl alcohol 3% aqueous solution were added to obtain a seed / child particle complexed liquid.

Separately, 120 g of divinylbenzene, 3 g of benzoyl peroxide, 0.7 g of sodium lauryl sulfate, and 800 mL of distilled water were mixed and emulsified to obtain a polymerizable monomer emulsion.

The obtained polymerizable monomer emulsion was added to the seed / child particle complexed solution, stirred at 100 rpm, and the polymerizable monomer was absorbed into the seed / child particle complex for 24 hours at room temperature under nitrogen stream to obtain a polymerizable droplet. Subsequently, after making the stirring speed 200 rpm, it heated at 70 degreeC and superposed | polymerized the polymerizable droplet and obtained projection particle | grains.

As a result of observing using a scanning electron microscope, the obtained protruding particles had an average particle diameter of 4.01 µm and a CV value of 3%, and an average number of protuberances per 24 (13.5% as a projection area).

(4) Preparation of Metal Surface Particles Having Projections

The obtained projection particles were subjected to degreasing, sensitizing and activating to generate a palladium nucleus on the surface of the resin to form a catalyst nucleus for electroless plating. Next, it immersed in the electroless nickel plating bath, and the nickel plating layer was formed. In addition, electroless substitution gold plating was performed on the surface of the nickel layer to obtain metal surface particles having projections.

When the obtained projection electroconductive particle was observed using the scanning electron microscope, metal plating is given to the surface of the particle | grains containing a processus | protrusion, The number of protrusions was an average of 24, and the number of protrusions did not decrease by plating operation.

2. Preparation of Insulating Fine Particles

50 mmol of glycidyl methacrylate, 50 mmol of methyl methacrylate, dimethacryl in a 1000 mL container separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube, and temperature probe 3 mmol of ethylene glycol acid, 1 mmol of phenyl dimethyl sulfonium methyl sulfate, and 2 mmol of 2,2'-azobis {2- [N- (2-carboxyethyl) amidino] propane} The monomer composition was weighed into distilled water so that the solid fraction was 5% by weight, stirred at 200 rpm, and polymerization was performed at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion | finish of reaction, it lyophilized and the insulating particle of CV value 7% of the average particle diameter of 180 nm which has a sulfonium group and an epoxy group, and a particle diameter was obtained.

3. Production of coated conductive particles

The metal surface particle | grains which have obtained insulated fine grain protrusion were disperse | distributed to distilled water under ultrasonic irradiation, and the 10 weight% water dispersion liquid of the insulating fine particles was obtained.

10 g of the metal surface particles having the obtained protrusions were dispersed in 500 mL of distilled water, 4 g of a water dispersion liquid of insulating fine particles was added, and stirred at room temperature for 6 hours. After filtration with a 3 μm mesh filter, the resultant was further washed with methanol and dried to obtain coated conductive particles.

When observed with the scanning electron microscope (SEM), only one coating layer by insulating fine particles was formed in the surface of the metal surface particle which has protrusion instead of the obtained coating electroconductive particle. The coverage was 30% when the coating area (namely, the projected area of the particle diameter of an insulating fine particle) with respect to 2.5 micrometers area was computed from the center of coating electroconductive particle by image analysis. In addition, by cross-sectional observation by a transmission electron microscope (TEM), since the bonding interface between insulating fine particles and metal surface particles is 12% of the circumference of the insulating fine particles, the interface bonding area with the metal surface particles is determined by the surface area of the insulating fine particles. 12%.

The obtained coated electroconductive particle was disperse | distributed to t-butyl alcohol, it weighed so that the weight of coated electroconductive fine particle after drying might be 0.00004g (about 240,000 pieces) on a 10 * 10mm silicon wafer, and after drying, a 10 * 10mm silicon wafer Covered and heated at 200 ° C. for 30 seconds under 100 N of pressurization. Thereafter, the silicon wafer was removed and the state of the insulating fine particles on the surface of the coated conductive particles was observed by SEM. The molten insulating fine particles were pushed out to expose the projections of the metal surface particles.

<Example 2>

1. Preparation of Insulation Particles

50 mmol of glycidyl methacrylate, 50 mmol of methyl methacrylate, dimethacryl in a 1000 mL container separable flask equipped with a four-neck separable cover, stirring blade, three-way cock, cooling tube, and temperature probe 3 mmol of ethylene glycol acid, 1 mmol of phenyl dimethyl sulphonium methyl sulfate, and 2 mmol of 2,2'-azobis {2- [N- (2-carboxyethyl) amidino] propane} The monomer composition was weighed into distilled water so that the solid fraction was 5% by weight, stirred at 200 rpm, and polymerization was carried out at 70 ° C. for 24 hours under a nitrogen atmosphere. After completion of the reaction, the particles were freeze-dried to obtain insulating particles having a mean particle size of 180 nm and a CV value of 7% having a sulfonium group and an epoxy group on the surface.

2. Preparation of Metal Surface Particles

(1) Preparation of Metal Surface Particles Having Projections

Electroless plating including alkali degreasing, acid neutralization, sensitizing in SnCl ₂ solution, activating in PdCl ₂ solution, to core particles comprising tetramethylolmethanetetraacrylate / divinylbenzene with an average particle diameter of 5 μm The pretreatment process was performed. In addition, the sensitizing is a process of adsorbing Sn ²⁺ ions on the surface of the insulating material, activating the reaction of the Sn ² + + Pd ^{2 +} → Sn ⁴ + + Pd ⁰ on the surface of the insulating material to electroless Pd It is a process of making the catalyst nucleus for plating.

The core particles subjected to the electroless plating pretreatment step were immersed in an electroless plating bath heated in a dry bath according to a predetermined method to perform electroless plating. As the electroless plating bath, nickel plating was performed using an electroless nickel bath. Here, in the step of forming Pd on the surface of the core particles, a small amount of PdCl ₂ is added to the system during activating, the Pd is unevenly attached to the surface, and nickel plating is performed under ultrasonic irradiation at 45 Hz to give a nickel plated layer having protrusions. Formed.

Then, gold plating was performed on the surface by the substitution plating method again to obtain metal surface particles having projections.

The nickel plating thickness of the obtained metal surface particle was 90 nm, and the thickness of gold plating was 30 nm. In addition, when observed with the scanning electron microscope (SEM), the height of the processus | protrusion was 10% of the metal surface particle diameter.

(2) Preparation of Metal Surface Particles Having Reactive Functional Groups

Next, 20 mmol of 2-aminoethanethiol was dissolved in 1000 mL of methanol to prepare a reaction solution in a 2000 mL container separable flask equipped with a four-neck separable cover, a stirring blade, and a three-way cock. 20 g of particles were dispersed in a reaction solution under a nitrogen atmosphere, stirred at room temperature for 3 hours, filtered to remove unreacted 2-aminoethanethiol, washed with methanol and dried, and had an amino group as a reactive functional group on the surface. Metal surface particles were obtained.

3. Production of coated conductive particles

The insulating particles were dispersed in acetone under ultrasonic irradiation to obtain a 10 wt% acetone dispersion of the insulating particles.

10 g of metal surface particles were dispersed in 500 mL of acetone, 4 g of acetone dispersion of insulating particles were added, and the mixture was stirred at room temperature for 6 hours. After filtration with a 3 μm mesh filter, the resultant was further washed with methanol and dried to obtain coated conductive particles.

When observed with the scanning electron microscope (SEM), the coating electroconductive particle had only one layer of coating layers by insulating particle formed in the surface of metal surface particle | grains. The coverage was 40% when the coating area (namely, the projected area of the particle diameter of an insulating particle) with respect to 2.5 micrometers area was computed from the center of the coating electroconductive particle by image analysis.

The coated conductive particles were dispersed in t-butyl alcohol, weighed so that the weight of the coated conductive particles after drying was 0.00004 g (about 240,000 pieces) on a 10 × 10 mm silicon wafer, and after drying, a 10 × 10 mm silicon wafer After heating at 200 ° C. for 30 seconds under pressure of 100 N, the silicon wafer was removed and the state of the insulating particles on the surface of the coated particle was observed by SEM. The surface was exposed and the insulating particle adhering to the silicon wafer side was also deformed.

These results are shown in Table 1.

4. Fabrication of Anisotropic Conductive Materials

(1) Anisotropic conductive film production

100 parts by weight of an epoxy resin ("Epicoat 828" manufactured by Yuca Shell Epoxy Co., Ltd.), 100 parts by weight of trisdimethylaminoethylphenol, and toluene were sufficiently dispersed and mixed with a planetary stirrer as a binder resin, and placed on a release film. It apply | coated in fixed thickness so that the thickness after drying might be set to 10 micrometers, and toluene was evaporated and the adhesive film which does not contain coating electroconductive particle was obtained.

Further, the coated conductive particles were added to 100 parts by weight of an epoxy resin ("Epicoat 828" manufactured by Yuca Shell Epoxy Co., Ltd.) and 100 parts by weight of trisdimethylaminoethylphenol and toluene as a binder resin, and sufficiently dispersed and mixed using an planetary stirrer. After obtaining a binder resin dispersion, it applied on a release film to a fixed thickness so that the thickness after drying might be set to 7 micrometers, and toluene was evaporated and the adhesive film containing coating electroconductive particle was obtained. In addition, the addition amount of coating electroconductive particle was set so that content in the anisotropic conductive film might be 200,000 piece / cm <2>.

A 17-micrometer-thick anisotropic conductive film which has a two-layered structure was obtained by laminating the adhesive film which does not contain a coating electroconductive particle in the adhesive film containing obtained coating electroconductive particle at normal temperature.

In addition, when some of the binder resin dispersions containing the coated conductive particles were washed in toluene, and the coated conductive particles were extracted, then observed by SEM, it was not recognized that the insulating particles were peeled from the coated conductive particles.

(2) Evaluation of connection status (insulation, resistance value)

Using the obtained anisotropic conductive film, it sandwiched between flexible printed circuit boards with a 200 * 200 micrometer bonded wiring pattern, and measured insulation and resistance value in the state which was thermally crimped.

(3) Evaluation of adhesiveness

The cross-section was observed by SEM after 300 hours under a cycle of 55 ° C. × 6 hours-120 ° C. × 6 hours, and the interface between the metal surface particles-insulating particles and the insulating particle-binder resin was used for evaluation of the connection state. The presence or absence of peeling was observed.

The results are shown in Table 1.

Comparative Example 1

In the same manner as in Example 2, metal surface particles having protrusions were produced, but no introduction of reactive functional groups and coating with insulating particles were performed. In addition, it carried out similarly to Example 2 in the manufacture of an anisotropic electrically-conductive material except having used metal surface particle | grains which have protrusion which is not coat | covered with insulating particle instead of coating electroconductive particle.

These results are shown in Table 1.

Comparative Example 2

Preparation of the insulating particle was performed similarly to Example 2.

In the production of metal surface particles, in the step of forming Pd on the surface of the core particles, Pd is adhered by ultrasonic irradiation and stirring, Pd is uniformly attached to the surface, nickel plating is performed under ultrasonic irradiation of 28 kPa, and the smooth surface is obtained. Metal surface particles were obtained in the same manner as in Example 2 except that the nickel plating layer was formed. The nickel plating thickness of the obtained metal surface particle was 90 nm, and the thickness of gold plating was 30 nm.

Moreover, when observed with the scanning electron microscope (SEM), it was a metal surface particle | grains without a processus | protrusion.

Production of metal surface particles having reactive functional groups, production of coated conductive particles, and production of anisotropic conductive materials were performed in the same manner as in Example 2 except that metal surface particles having no projections were used instead of metal surface particles having projections, respectively. It was.

These results are shown in Table 1.

According to this invention, the coated electroconductive particle, anisotropic electrically-conductive material, and an electrically conductive connection structure excellent in connection reliability can be provided.

Claims (6)

It is coated electroconductive particle containing the particle | grains which have the surface containing the conductive metal, and the insulating particle which coat | covers the surface of the particle | grains which have the surface containing the said conductive metal, The particle | grains which have the surface containing the said conductive metal are the surfaces Covered electroconductive particle characterized by having a some processus | protrusion. The single layer coating layer is formed by chemically bonding insulating particles to particles having a surface containing a conductive metal via a functional group (A) having a bonding property to the conductive metal. Coated conductive particles. The coated electroconductive particle of Claim 1 or 2 in which the particle | grains which have the surface containing electroconductive metal contain the core particle containing resin and the electroconductive metal layer formed in the surface of the said core particle. The coated electroconductive particle of any one of Claims 1-3 whose minimum of protrusion height is 0.05 micrometer, and the upper limit of protrusion height is 40% of the particle diameter which has the surface containing an electroconductive metal. The coated electroconductive particle of any one of Claims 1-4 is disperse | distributed in insulating binder resin, The anisotropic conductive material characterized by the above-mentioned. An electronic component is electrically connected by the covering electroconductive particle of any one of Claims 1-4, or the anisotropic conductive material of Claim 5, The electrically conductive connection structure characterized by the above-mentioned.

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