JP4852311B2 - Conductive particle, anisotropic conductive material, and conductive connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive particle, an anisotropic conductive material, and a conductive connection structure wherein by being arranged, adhered, and fixed between circuit faces or the like installed at opposing substrate surfaces in carrying out electric connection between the circuits of the substrate surfaces, there is no occurrence of cracks in the direction in parallel with the circuit faces in a conductive layer to secure the electric connection between the circuits, and wherein connection reliability is superior. <P>SOLUTION: This is the conductive particle composed of a base material particle and the conductive layer formed on the surface of the base material particle, and the base material particle is composed of a hard particle and a porous layer formed on the surface of the hard particle. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

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

In addition to being used as various resin fillers and modifiers, the particles having a metal surface are mixed with a binder resin as conductive particles, and in electronic products such as liquid crystal displays, personal computers, portable communication devices, etc. It is also used as a so-called anisotropic conductive material for electrically connecting small electrical products to substrates or electrically connecting substrates.

As such conductive particles, for example, hard conductive particles in which the surface of hard particles such as silica are coated with a metal thin film have been proposed. Such hard conductive particles are, for example, disposed between opposing circuit electrodes and bonded and fixed with an adhesive, whereby the electrodes are electrically connected.
However, when the electrical connection between the substrates is performed using such hard conductive particles, the contact between the hard conductive particles and the electrode surface is a point contact. Under the environment, the thermal expansion coefficient and elastic modulus of the hard conductive particles and the adhesive for bonding and fixing the hard conductive particles are different, so that sufficient contact points between the hard conductive particles and the electrode surface are ensured. There is a problem in that sufficient connection reliability cannot be obtained.

On the other hand, in order to obtain good connection reliability in recent years, flexible conductive particles in which the surface of the flexible particles is covered with a metal thin film have been proposed for the purpose of increasing the contact area between the conductive particles and the electrodes.
However, when the flexible conductive particles are used for electrical connection between the substrates, if the temperature and pressure at the time of connection are insufficient, a sufficient contact area with the electrode cannot be secured, and the bonding area is reduced. To increase the deformation of the flexible particles by increasing the temperature and pressure at the time of connection, the thin metal layer may be peeled off from the elastic particles or partially broken, etc. There is a problem that insulation between the adjacent electrodes is insufficient when a fine circuit is connected, and it is very difficult to set control conditions for temperature and pressure at the time of connection.

In order to avoid such a problem, a method of controlling deformation of flexible conductive particles by using flexible conductive particles and hard particles or hard conductive particles smaller than the flexible conductive particles has been proposed. . However, in such a method, compared to the addition amount of hard particles or the like, the connection area between the flexible conductive particles and the electrode cannot be sufficiently secured, and as a result, the flexible conductive particles and the like are bonded to the electrode surface. There was a problem that the adhesive force was reduced due to a decrease in the amount of the binder resin to be fixed, and the cost was increased.

Thus, conductive particles are disclosed in which the surfaces of hard particles are coated with a soft resin and then covered with a thin metal layer (see, for example, Patent Document 1 or Patent Document 2). In the conductive particles disclosed in these documents, the soft resin is deformed together with the thin metal layer by thermocompression bonding, increasing the connection area between the electrode and the thin metal layer, while the deformation rate of the entire conductive particle is increased by the hard particles. It is something to control.
However, although the conductive particles disclosed in these documents increase the contact area between the electrode and the particles, the metal deforms with the soft resin when heat and pressure are applied to sufficiently deform the soft resin. In some cases, the thin layer was cracked in the direction parallel to the circuit surface, and sufficient conduction could not be ensured.
Japanese Patent Laid-Open No. 7-140481 JP 2003-272445 A

An object of this invention is to provide the electroconductive particle excellent in connection reliability, the anisotropic conductive material, and the conductive connection structure in view of the said present condition.

The present invention is a conductive particle comprising a substrate particle and a conductive layer formed on the surface of the substrate particle, the substrate particle is a porous particle formed on the surface of the hard particle and the hard particle It is the electroconductive particle which consists of a layer.
The present invention is described in detail below.

The conductive particles of the present invention are composed of base particles and a conductive layer formed on the surface of the base particles.
In the conductive particles of the present invention, the substrate particles are composed of hard particles and a porous layer.
The above hard particles are sandwiched between two electrodes when electrically connecting circuit electrodes using the conductive particles of the present invention, and the interval between these two electrodes is regulated. It serves to maintain a proper inter-electrode distance. The soft layer is deformed by the pressure received from the electrodes when the conductive particles of the present invention are sandwiched between two electrodes in order to make electrical connection between the electrodes, and the soft layer and the electrodes It plays the role which enlarges the contact area with respect to the electrode surface of the conductive layer between the surfaces. Furthermore, the said conductive layer ensures the electrical connection between electrodes, when the electrical connection of electrodes etc. is performed using the electroconductive particle of this invention.

In the conductive particle of the present invention, the porous layer may have a structure provided on the entire surface of the hard particle, or may have a structure provided on a part of the hard particle.
FIG. 1 is a sectional view schematically showing an example of the conductive particles of the present invention having a structure in which a porous layer is provided on the entire surface of hard particles.
In the conductive particles 10 shown in FIG. 1, the hard particles 11 and the porous layer 12 are concentric with the same center in the cross section, but the conductive particles of the present invention are 2, the center of the hard particle 21 and the center of the porous layer 22 are different from each other, that is, the hard particle 21 is embedded in a position biased to one of the inside of the porous layer 22. It may be a structure.

When the conductive particle of the present invention has a structure in which a porous layer is provided on a part of the surface of the hard particle, for example, a part of a spherical hard particle 31 like the conductive particle 30 shown in FIG. Is embedded in a porous layer 32 that is larger than the hard particles 31, and at this time, the conductive layer formed on the surface of the base material particle is a hard particle like the conductive layer 33 shown in FIG. It is formed on the surface and the surface of the porous layer. In addition, FIG. 3 is sectional drawing which shows typically another example of the electroconductive particle of this invention.

The conductive particles of the present invention have a structure in which a porous layer is provided on the entire surface of the hard particles as shown in FIGS. 1 and 2, or the surface of the hard particles as shown in FIG. When the porous layer larger than the hard particles is provided in part, the ratio (b / a) between the apparent diameter (a) of the hard particles and the apparent diameter (b) of the soft layer is a lower limit. Exceeds 1.0 and the upper limit is 1.5. When 1.0 or less, the hard particles are larger than the porous layer, and when the conductive particles of the present invention are used to electrically connect the substrates and the like, the pressure applied to the soft layer from the substrate The effect of the present invention that the contact area between the conductive layer and the substrate surface is increased due to the deformation is not obtained. If it exceeds 1.5, the volume of the porous layer with respect to the hard particles becomes large, the conductive particles themselves become too large, and when the number of conductive particles necessary for electrical connection between the electrodes is used, The adhesive force may decrease due to the contact between the conductive particles or the decrease in the amount of the binder resin that fixes the electrodes.

In this specification, the apparent diameter (a) of the hard particles means the diameter of the sphere when the hard particles are regarded as a sphere, as shown in FIGS. Further, the apparent diameter (b) of the porous layer is, as shown in FIGS. 1 and 2, the diameter of the sphere when the porous layer is regarded as a sphere, or shown in FIG. Thus, it means the diameter of the sphere when the surface of the porous layer is regarded as a part of the surface of the sphere.

Furthermore, when the conductive particles of the present invention have a structure in which a porous layer is provided on a part of the surface of the hard particles as shown in FIG. 3, the length (c) in the major axis direction is the above-mentioned hard It is necessary to be smaller than the sum of the apparent diameter (a) of the particles and the apparent diameter (b) of the porous layer. When the length (c) in the major axis direction is equal to or larger than the sum of the apparent diameter (a) of the hard particles and the apparent diameter (b) of the porous layer, the hard particles and the porous layer are in contact with each other. However, the effect of the present invention that the contact reliability between the conductive layer and the substrate is increased to increase the connection reliability between the substrates cannot be obtained.
In the present specification, the length (c) in the major axis direction is a straight line connecting two points on the surface of the base particle composed of the hard particles and the porous layer, as shown in FIG. Of these, it means the longest one.

When the conductive particle of the present invention has a structure in which a porous layer is provided on the entire surface of a hard particle such as the conductive particle 10 shown in FIG. 1, the conductive particle of the present invention is placed between opposing substrates. When placed and electrically connected to each other, the portion of the porous layer that comes into contact with the substrate by the pressure applied from the substrate is equal to the height of the hard particles together with the conductive layer provided on the surface of the porous layer. The substrate surface and the conductive layer are brought into surface contact, and the contact area is increased. At this time, the deformation that occurs in the portion of the porous layer in contact with the substrate is sufficiently absorbed by the pores present therein, so that almost no deformation occurs in other portions of the porous layer. As a result, the conductive layer provided on the surface of the porous layer is not cracked in the direction parallel to the substrate surface, and the connection reliability between the substrates is ensured.

Further, when the conductive particle of the present invention has a structure in which a porous layer larger than the hard particle is provided on a part of the surface of the hard particle, such as the conductive particle 30 shown in FIG. When the conductive particles are arranged between the opposing substrates and the electrical connection between the substrates is performed, as shown in FIG. 4, the portion of the porous layer 32 that comes into contact with the substrate 40 by the pressure applied from the substrate 40 is The conductive layer 33 provided on the surface of the porous layer 32 is deformed so as to be crushed to a height equal to the height of the hard particles 31, and the surface of the substrate 40 and the conductive layer 33 are brought into surface contact to increase the contact area. At this time, the deformation that occurs in the portion of the porous layer 32 that comes into contact with the substrate 40 is sufficiently absorbed by the pores present therein, so that almost no deformation occurs in other portions of the porous layer 32. Furthermore, since the hard particles 31 hardly deform, the conductive layer 33 provided on the surface of the hard particles 31 hardly deforms. As a result, the conductive layer 33 other than the portion in contact with the surface of the substrate 40, in particular, the conductive layer 33 provided on the surface of the hard particles 31, is hardly affected by the deformation of the porous layer 32 and the like. There is no crack in the parallel direction, and the connection reliability between the substrates 40 is more reliable.
FIG. 4 is a cross-sectional view schematically showing electrical connection between substrates using the conductive particles of the present invention shown in FIG.

In the electroconductive particle of this invention of such a structure, it does not specifically limit as a material which comprises the said hard particle, For example, an inorganic or organic material is mentioned.

It does not specifically limit as said inorganic material, For example, a metal, a metal oxide, a silica etc. are mentioned.

Examples of the organic material used as the base particles include olefins such as ethylene, propylene, butylene, isoprene, and methylpentene, and derivatives thereof; styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and divinylbenzene. Styrene derivatives such as chloromethylstyrene; vinyl halides such as vinyl fluoride and vinyl chloride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl stearate; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and propyl vinyl ether Unsaturated nitriles such as (meth) acrylonitrile; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate Glycidyl (meth) acrylate, hydroxyethyl (meth) acrylate, ethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, cyclohexyl (meth) acrylate, di ( (Meth) acrylic such as polyethylene glycol (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerol tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate Acid ester derivatives; unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and maleic anhydride; polymers using polymerizable monomers such as acrylamides and acrylamides such as N-isopropylacrylamide, polyamides, (unsaturated) Poly Examples include esters, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyamideimide, polyether ether ketone, polyether sulfone, epoxy resin, phenol resin, melamine resin, and benzoguanamine resin. The said polymerizable monomer may be used independently and may use 2 or more types together.

In the conductive particles of the present invention, the hard particles may be composed of only the inorganic material or the organic material, or may have a composite structure of the inorganic material and the organic material. Good.

When the hard particles are made of an organic material obtained by polymerizing the polymerizable monomer described above, the polymerization method is not particularly limited. For example, suspension polymerization method, emulsion polymerization method, seed polymerization method, dispersion polymerization method Conventionally known polymerization methods are mentioned, and any polymerization method may be used.

The suspension polymerization method and the emulsion polymerization method are suitable for the purpose of producing fine particles having a wide variety of particle sizes because the particle size distribution is relatively wide and polydispersed particles can be obtained. However, when using particles produced by the suspension polymerization method, it is preferable to classify and use those having a desired particle size or particle size distribution.
The seed polymerization method is suitable for the purpose of producing a large amount of fine particles having a specific particle size because monodisperse particles can be obtained without requiring classification operation.

The medium used in the polymerization method is not particularly limited, and may be appropriately selected according to the type of monomer used and the monomer composition. For example, water; alcohols such as methanol, ethanol and propanol; methyl Cellosolves such as cellosolve and ethyl cellosolve; ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and 2-butanone; acetates such as ethyl acetate and butyl acetate; carbonization such as acetonitrile, N, N-dimethylformamide and dimethyl sulfoxide Hydrogen etc. are mentioned. These media may be used independently and 2 or more types may be used together.

The preferable lower limit of the average particle diameter of the hard particles is 0.5 μm, and the preferable upper limit is not particularly limited, but is 3000 μm. When the thickness is less than 0.5 μm, aggregation is likely to occur when a soft layer or a conductive layer described later is formed, and the conductive particles of the present invention manufactured using the aggregated hard particles are short-circuited between adjacent electrodes. When the thickness exceeds 3000 μm, the conductive layer of the obtained conductive particles of the present invention tends to be peeled off and the reliability may be lowered. A more preferred lower limit is 0.8 μm, a more preferred upper limit is 100 μm, a still more preferred lower limit is 1 μm, and a still more preferred upper limit is 20 μm. The average particle size of the hard particles can be obtained by statistically processing the particle size measured using an optical microscope, an electron microscope, a coulter counter, or the like.

The coefficient of variation of the average particle diameter of the hard particles is preferably 10% or less. If it exceeds 10%, it becomes difficult to arbitrarily control the distance between the opposing electrodes using the obtained conductive particles. The coefficient of variation is a numerical value obtained by dividing the standard deviation obtained from the particle size distribution by the average particle size.

The hard particles preferably have a certain strength, and the preferable lower limit of the compressive elastic modulus (10% K value) when the diameter of the hard particles is displaced by 10% is 1000 MPa, and the preferable upper limit is 15000 MPa. It is. When it is less than 1000 MPa, the strength of the conductive particles obtained is insufficient, so that when the electrical connection between the substrates or the like is performed, the hard particles may be broken and may not function as a conductive material. If it exceeds 15000 MPa, the electrode may be damaged. A more preferable lower limit is 2000 MPa, and a more preferable upper limit is 10,000 MPa.
The above 10% K value is obtained by using a micro-compression tester (for example, “PCT-200” manufactured by Shimadzu Corporation), and using a smooth indenter end face made of a diamond cylinder having a diameter of 50 μm and a compression speed of 2.6 mN / The compression displacement (mm) when the hard particles are compressed under conditions of a second and a maximum test load of 10 g can be measured and obtained by the following formula.
K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value at 10% compression deformation of hard particles (N)
S: Compression displacement (mm) in 10% compression deformation of hard particles
R: radius of hard particles (mm)

It is preferable that the lower limit of the recovery rate of the hard particles is 20%. If it is less than 20%, the resulting conductive particles of the present invention will not return to their original shape even if they are deformed, resulting in poor connection and accurate control of the substrate spacing may not be achieved. A more preferred lower limit is 40%. In addition, the said recovery rate means the recovery rate after applying a load of 9.8 mN to hard particles.

In the conductive particles of the present invention, the porous layer has a large number of pores therein and is softer than the hard particles. Accordingly, the electrical connection between the substrates using the conductive particles of the present invention is performed while applying the pressure at which only the porous layer is deformed to the conductive particles of the present invention disposed between the opposing substrates.

Although it does not specifically limit as a specific surface area of the said porous layer, A preferable minimum is 1 m < ² > / g and a preferable upper limit is about 100 m < ² > / g. When the porous layer is less than 1 m ² / g, the porous layer becomes hard, and the conductive particles of the present invention are not deformed sufficiently when the conductive particles of the present invention are arranged between opposing substrates and electrically connected to each other. The contact area between the conductive layer and the substrate surface may not be increased, and if it exceeds 100 m ² / g, the hard particles may be easily peeled off or destroyed.

Further, the 10% K value of the porous layer is not particularly limited, but a preferable upper limit is ½ of the 10% K value of the hard particles. When the upper limit exceeds 1/2 of the 10% K value of the hard particles, the conductive layer and the substrate are electrically conductive because the soft layer is not deformed when the conductive particles of the present invention are used to electrically connect the substrates. The contact area with the layer cannot be increased sufficiently, resulting in poor connection reliability, or hard particles may be deformed and the substrate spacing cannot be controlled.

Although it does not specifically limit as a material which comprises such a porous layer, For example, the same kind as the material used for the said hard particle can be utilized. However, the material constituting the porous layer is preferably selected from a material that is relatively softer than the material used for the hard particles. Among them, a thermoplastic resin is preferably used because it is softened and deformed by heating, increasing the contact area with the substrate, and consequently increasing the contact area of the conductive layer with the substrate.

Although it does not specifically limit as a softening point of the said soft layer, A preferable minimum is 40 degreeC and a preferable upper limit is 150 degreeC. When the temperature is lower than 40 ° C., the base particles are aggregated when the conductive layer is formed, or the conductive particles are deformed when the conductive particles are transported. When the temperature is higher than 150 ° C., the conductive particles of the present invention. For example, the heating temperature at the time of fixing between two substrates increases, and the burden on the substrate is large, which may cause distortion and the like.
The softening point refers to a temperature at which the thermoplastic resin is plastically deformed by heating.

Examples of the method for forming the porous layer made of the crosslinked (meth) acrylate resin on the surface of the hard particles include, for example, the hard particles, the (meth) acrylate monomer, and a crosslinkable monomer. The mixture (oil phase) of a body and a nonpolymerizable organic solvent is superposed | polymerized in water (aqueous phase), and the method of removing a nonpolymerizable organic solvent from a reaction product after completion | finish of a polymerization reaction is mentioned. The polymerization method in water is not particularly limited, and may be any of suspension polymerization, emulsion polymerization, seed polymerization, etc., but suspension polymerization is particularly preferable in that the porous layer is easily obtained. Is preferred. In addition, the formation state to the hard particle of the obtained porous layer is controllable by selecting suitably the polarity, interfacial tension, etc. of the said hard particle and the monomer which comprises a porous layer.

A method for providing the soft layer on a part of the surface of the hard particle is not particularly limited, but after forming a complex of the hard particle and a polymerizable droplet composed of a monomer constituting the soft layer. A method of polymerizing polymerizable droplets composed of the above monomers is preferably used.

As a method of forming polymerizable droplets composed of monomers constituting the soft layer and combining them with hard particles, (1) dispersing the monomers constituting the soft particles in an insoluble medium (2) Resin layer (hereinafter referred to as shell seed layer) swellable with monomers constituting the soft layer on the surface of hard particles And the shell seed layer is swollen with the monomer constituting the soft layer. As a method of compounding with the hard particles, the method of forming the shell seed layer is preferable because the uniformity of the size of the soft layer to be formed becomes high. For example, when the shell seed layer is swollen with the monomer constituting the soft layer, if the composition (polarity) and size of the hard particle and the monomer are different, the thermodynamically In order to form a stable structure, a soft layer can be formed by uneven distribution of the swelling layer.
As described above, the composite state can be controlled by appropriately selecting the polarity, interfacial tension, and the like between the hard particles and the monomer constituting the soft layer.

The medium is not particularly limited as long as it is incompatible with the monomer, and examples thereof include water, methanol, ethanol, dimethyl sulfoxide, dimethylformamide, and a mixed solution thereof. Of these, water is preferable because it is easy to handle.

In order to stably disperse the polymerizable droplets in the medium, for example, dispersion stabilizers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyoxyethylene, cellulose, polyalkylene glycol alkyl ether, polyalkylene glycol alkyl phenyl ether It is preferable to add an ionic or nonionic surfactant such as fatty acid diethanolamide, sodium alkyl sulfate, sodium alkylbenzenesulfonate, long chain fatty acid, long chain alkyltrimethylamine hydrochloride, dimethylalkylbetaine.
Further, additives such as auxiliary stabilizers, pH adjusters, anti-aging agents, antioxidants, preservatives and the like that are usually used in suspension polymerization methods and emulsion polymerization methods may be added to the medium.

The resin layer constituting the shell seed layer is not particularly limited as long as it absorbs the monomer constituting the soft layer and forms a polymerizable droplet, and uses an organic material constituting hard particles. It is possible. The material constituting the shell seed layer is preferably a non-crosslinked material because the monomer constituting the soft layer is easily absorbed to form a polymerizable droplet.

The method for producing the shell seed layer is not particularly limited. For example, (1) a method for precipitating the resin layer constituting the shell seed layer on the surface of the hard particles, and (2) a single material for the hard particles and the resin layer. A method in which a polymer is dispersed in a medium and the resin layer is formed on the surface of hard particles by dispersion polymerization, emulsion polymerization, suspension polymerization, soap-free precipitation polymerization, or the like. (3) Reactive functional groups are introduced on the surface of hard particles. And (4) introducing a polymerizable functional group onto the surface of the hard particles, and using the polymerizable functional group as a starting point, the resin of the above-mentioned resin has a chemical reaction with the reactive functional group. Examples include a method of graft polymerization of raw material monomers.

The method for swelling the shell seed layer with the monomer constituting the soft layer is not particularly limited. For example, (1) mixing the monomer constituting the soft layer and hard particles having the shell seed layer. After that, a method of adding a solvent incompatible with the monomer constituting the soft layer, (2) dispersing hard particles having a shell seed layer in the solvent incompatible with the monomer constituting the soft layer For example, a method of adding a monomer that constitutes the soft layer may be used. In addition, in order to prevent the shell seed layers swollen by the monomers constituting the soft layer from being united, surfactants and / or dispersion stabilizers used for emulsion polymerization, suspension polymerization, dispersion polymerization, etc. May be added.

The thickness of the shell seed layer varies depending on the size of the obtained soft layer and is not particularly limited, but is preferably from 0.01 μm to 20% of the particle size of the hard particles. When it is less than 0.01 μm, it may not be swollen with a necessary amount of the monomer or may swell unevenly when it is swollen with the monomer constituting the soft layer. If it exceeds 20% of the particle size of the hard particles, the physical properties of the obtained soft layer may be governed by the physical properties of the shell seed layer.

Examples of the non-polymerizable organic solvent include those having a solubility parameter of 6 to 11, more preferably 7 to 10. When a non-polymerizable organic solvent having a solubility parameter of less than 6 or more than 11 is used, the particle shape and the porous shape may not be formed well, and the specific surface area and the oil absorption amount may decrease.
Examples of the non-polymerizable organic solvent include aromatic hydrocarbons such as toluene and benzene, esters such as ethyl acetate and butyl acetate, and saturated aliphatic hydrocarbons such as n-hexane, n-octane and n-dodecane. Etc. These non-polymerizable organic solvents may be used alone or in combination of two or more.

As a use ratio of the non-polymerizable organic solvent, a preferable lower limit is 30% by weight and a preferable upper limit is 90% by weight in the oil phase. If it is less than 30% by weight, the specific surface area and oil absorption of the resulting porous layer may decrease, and if it exceeds 90% by weight, the porosity in the resulting porous layer becomes too large, and deformation, Destruction may occur.

In the conductive particles of the present invention, a conductive layer is formed on the surface of the substrate particles.
The conductive layer is not particularly limited as long as it has conductivity. For example, gold, silver, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, Examples thereof include metals such as bismuth, germanium, cadmium and silicon, and metal compounds such as ITO and solder.

The conductive layer may have a single layer structure or a laminated structure including a plurality of layers. In the case of a laminated structure, the outermost layer is preferably made of gold. When the outermost layer is made of gold, the corrosion resistance is high and the contact resistance is small, so that the obtained conductive particles are further improved.

The method for forming the conductive layer on the surface of the substrate particles is not particularly limited, and examples thereof include known methods such as physical metal vapor deposition and chemical electroless plating. Therefore, the 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. In the method, since a uniform coating can be formed at a high density, it is preferable that a part or all of the conductive layer is formed by electroless nickel plating.

The method for forming the gold layer on the outermost layer of the conductive layer is not particularly limited, and examples thereof include known methods such as electroless plating, displacement plating, electroplating, and sputtering.

Although it does not specifically limit as thickness of the said conductive 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 the conductive layer may not be obtained. If it exceeds 1 μm, the specific gravity of the obtained conductive particles becomes too high, or the hardness of the porous soft layer is no longer sufficient. The hardness may not be sufficiently deformable. A more preferable lower limit is 0.01 μm, and a more preferable upper limit is 0.3 μm.

Moreover, when making the outermost layer of the said conductive layer into a gold layer, the minimum with the preferable thickness of a gold layer is 0.001 micrometer, and a preferable upper limit is 0.5 micrometer. If the thickness is less than 0.001 μm, it may be difficult to uniformly coat the conductive layer, and the effect of improving corrosion resistance and contact resistance may not be expected. If the thickness exceeds 0.5 μm, the effect is expensive. is there. A more preferable lower limit is 0.01 μm, and a more preferable upper limit is 0.1 μm.

The conductive particles of the present invention may further have an insulating layer on at least a part of the surface of the conductive layer. When the conductive particles of the present invention are coated with an insulating layer, when conducting conductive connection of a substrate or the like using the conductive particles of the present invention, even if the substrate or the like having fine wiring is adjacent The conductive particles do not cause lateral conduction between the conductive particles, and the conductive layer of the conductive particles is exposed and exposed to heat by applying heat and pressure in the vertical direction to perform thermal compression. .

The material constituting the insulating coating layer is not particularly limited as long as it is an insulating material, and examples thereof include a material made of an insulating organic material and a material made of an insulating inorganic material such as silica. Especially, what consists of an insulating organic material is preferable. It does not limit as said insulating organic material, For example, the organic material etc. which are used for the above-mentioned hard particle are mentioned. These organic materials may be used alone or in combination of two or more.

Furthermore, it is preferable that the insulating organic material has a particulate shape.
The particle size of the particulate organic material varies depending on the particle size of the hard particles and the use of the conductive particles of the present invention, but is preferably 1/10 or less of the particle size of the hard particles. If it exceeds 1/10, the particle diameter of the insulating particles becomes too large, and the effect of using the conductive particles of the present invention cannot be expected. Moreover, when it is 1/10 or less, when manufacturing the electroconductive particle of this invention by a hetero-aggregation method, an insulating particle can be efficiently adsorbed on an electroconductive layer. Moreover, when using the electroconductive particle of this invention as an anisotropic conductive material, the minimum with the preferable particle diameter of the said insulating particle is 5 nm, and a preferable upper limit is 1000 nm. If it is less than 5 nm, the distance between adjacent conductive particles becomes smaller than the electron hopping distance, and leakage easily occurs. If it exceeds 1000 nm, the pressure and heat required for thermocompression bonding may become too large. is there. A more preferred lower limit is 10 nm, and a more preferred upper limit is 500 nm.

As the method for forming the insulating layer on the surface of the conductive particles, a conventionally known method can be used. For example, chemical methods such as a coacervation method, an interfacial polymerization method, an in situ polymerization method, and a submerged curing coating method are used. Physical-mechanical methods such as mechanical methods, spray drying methods, air suspension coating methods, vacuum deposition coating methods, dry blending methods (hybridization methods), electrostatic coalescence methods, melt dispersion cooling methods and inorganic encapsulation methods, Physicochemical methods such as interfacial precipitation and heteroaggregation can be used. Among these, the physicochemical method is preferable, and the heteroaggregation method is particularly preferable.

The area where the conductive particles are covered with the insulating organic material has a preferable lower limit of 5% and a preferable upper limit of 80%. If it is less than 5%, the conductive layers of the conductive particles may be in contact with each other between adjacent particles, and insulation may not be ensured. If it exceeds 80%, the electrode and the conductive particles may be subjected to thermocompression bonding. It is difficult to eliminate the insulating layer between the conductive particles and the conductive particles, and sufficient continuity cannot be secured, or heating and pressure more than necessary are required, and the circuit and the substrate may be damaged.
In the case where the insulating organic material is in the form of particles, the covered area is the covered area with the projected area of the particles.

The thickness of the coating layer varies depending on the particle size of the conductive particles, the coating area, the shape of the insulating organic material, the physical properties, and the binder resin when used as an anisotropic conductive material, but the preferred lower limit is 5 nm and the preferred upper limit. Is 1000 nm. If it is less than 5 nm, the distance between adjacent particles becomes smaller than the hopping distance of electrons, and leakage tends to occur. If it is larger than 1000 nm, the pressure and heat required for thermocompression bonding become too large. A more preferred lower limit is 10 nm, and a more preferred upper limit is 500 nm.

Such an anisotropic conductive material in which the conductive particles of the present invention are dispersed in a binder resin is also one aspect of the present invention.
Note that in this specification, 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 method for producing the anisotropic conductive film is not particularly limited. For example, the conductive particles of the present invention are suspended in a binder resin added with a solvent, and the suspension is placed on a release film. For example, a method may be used in which a film is formed by casting, and a film obtained by evaporating the solvent from the film is wound on a roll.

In the conductive connection by the anisotropic conductive film, there is a method in which the film is unwound together with the release film, the film is placed on the electrode to be bonded, and the counter electrode is stacked on the electrode and thermocompression bonded. Can be mentioned.

The anisotropic conductive paste can be prepared, for example, by making an anisotropic conductive adhesive into a paste, which is put in a suitable dispenser and applied to a desired thickness on the electrode to be connected. Connection can be made by stacking the counter electrode on top and thermocompression-bonding the resin.

The anisotropic conductive ink can be prepared, for example, by adding a solvent to the anisotropic conductive adhesive to have a clay suitable for printing, and screen-printing this on the electrode to be bonded, and then The connection can be established by evaporating the solvent and stacking the counter electrode thereon and thermocompression bonding.

The coating thickness of the anisotropic conductive material is calculated from the average particle diameter of the conductive particles used according to the present invention and the specifications of the connection electrodes. Between the connection electrodes, the conductive particles are sandwiched between the connection electrodes. Is preferably sufficiently filled with the adhesive layer.

The binder resin is not particularly limited as long as it has insulating properties. For example, acrylic ester, ethylene-vinyl acetate resin, styrene-butadiene block copolymer and hydrogenated product thereof, styrene-isoprene block copolymer Thermoplastic resins such as coalesced and hydrogenated products thereof; epoxy resins, acrylic ester resins, melamine resins, urea resins, phenolic resins and other thermosetting resins; polyhydric alcohol acrylic esters, polyester acrylates, polycarboxylic acids Resins that can be cured by ultraviolet rays, electron beams, etc., such as unsaturated esters. Especially, the adhesive agent hardened | cured with a heat | fever and / or light is suitable.

In the anisotropic conductive material of the present invention, when insulating particles are provided on the surface of the conductive layer of the conductive particles of the present invention described above, the insulating particles and the functional group in the binder resin may be chemically bonded. preferable. By chemically bonding the insulating particles and the binder resin, the conductive particles of the present invention dispersed in the binder resin have excellent stability, and the thermally melted insulating particles bleed out to contaminate the electrodes and liquid crystal. And an anisotropic conductive material having excellent long-term connection stability and reliability.

As a combination of such insulating particles and a binder resin, for example, the insulating particles preferably have a functional group such as a carboxyl group, an epoxy group, an isocyanate group, an amino group, a hydroxyl group, a sulfonic acid, a silane group, and a silanol group. Of these, it is more preferable to have an epoxy group. On the other hand, the binder resin has a (co) polymer having a functional group reactive with these functional groups at room temperature, under heating or under light irradiation, and has a reactive functional group as described above. It is preferable to use a monomer or the like that can form a (co) polymer or a polycondensate by a polycondensation reaction. These binder resins may be used alone or in combination of two or more.

The (co) polymer is not particularly limited. For example, polyolefins such as polyethylene and polybutadiene; polyethers such as polyethylene glycol and polypropylene glycol; polystyrene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, poly Acrylamide, polyvinyl alcohol, polyvinyl ester, phenol resin, melamine resin, allyl resin, furan resin, polyester, epoxy resin, silicone resin, polyimide resin, polyurethane, fluororesin, acrylonitrile-styrene copolymer resin, styrene-butadiene copolymer resin, Vinyl resin, polyamide resin, polycarbonate, polyacetal, polyether sulfone, polyphenylene oxide, sugar, starch, cellulose, polypeptide and the like can be mentioned. These (co) polymers may be used alone or in combination of two or more.

Moreover, it is not specifically limited as a monomer which can form the said (co) polymer and a polycondensate, For example, a polymerization reaction is performed with a heat | fever, light, an electron beam, a radical polymerization initiator, a polymerization catalyst etc. Examples thereof include vinyl monomers and monomers that undergo a polycondensation reaction. These monomers may be used alone or in combination of two or more.

In the anisotropic conductive material of the present invention, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an oxidizer can be used as long as it does not hinder achievement of the problems of the present invention. One kind or two or more kinds of various additives such as an inhibitor, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant may be added.

The method for dispersing the conductive particles of the present invention in the binder resin is not particularly limited, and a conventionally known dispersion method can be used. For example, after adding the conductive particles of the present invention to the binder resin, A method of kneading and dispersing with a planetary mixer, etc .; after uniformly dispersing the conductive particles of the present invention in water or an organic solvent using a homogenizer or the like, add it to a binder resin and knead with a planetary mixer or the like Dispersing by applying mechanical shearing force, such as a method of diluting the binder resin with water or an organic solvent, adding the conductive particles of the present invention, and kneading and dispersing with a planetary mixer or the like Methods and the like. These dispersion methods may be used alone or in combination of two or more.

The method for applying the mechanical shearing force is not particularly limited. For example, planetary stirrers, universal stirrers, planetary mixers, rolls, propeller stirrers, dispersers and the like, various mixing stirrers using these, and the like. Is mentioned. In addition, when applying the mechanical shearing force, a method and conditions that do not apply a mechanical shearing force that destroys the structure of the conductive particles of the present invention dispersed in the binder resin are appropriately selected. Is preferred.

The form of the anisotropic conductive material of the present invention is not particularly limited. For example, an insulating liquid or solid adhesive is used as the binder resin, and the conductive particles of the present invention are contained in the adhesive. An amorphous anisotropic conductive adhesive that is dispersed may be used, or a fixed anisotropic conductive film may be used.

A conductive connection structure in which electronic components such as an IC chip and a substrate are conductively connected with the conductive particles of the present invention or the anisotropic conductive material of the present invention is also one aspect of the present invention.

The conductive particles of the present invention are composed of base particles and a conductive layer formed on the surface of the base particles, and the base particles are composed of hard particles and a porous layer provided on the surface of the hard particles. It will be.
When the conductive particles of the present invention are arranged between the opposing substrates and the substrates are electrically connected, the portion of the porous layer that comes into contact with the substrate by the pressure applied from the substrate is the surface of the porous layer. It deforms together with the conductive layer provided on the substrate, the surface of the substrate and the conductive layer become in surface contact, and the contact area increases. At this time, the deformation generated in the portion of the porous layer in contact with the substrate is sufficiently absorbed by the pores present therein, so the conductive layer in the portion other than the portion in contact with the substrate has the porous layer. Cracks do not occur in the direction parallel to the substrate surface due to the deformation, and electrical connection between the substrates can be reliably ensured.
That is, according to the present invention, it is possible to provide conductive particles, anisotropic conductive materials, and conductive connection structures having excellent connection reliability.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(1) Preparation of conductive particles [1] Into a separable flask, 15 parts by weight of divinylbenzene, 5 parts of isooctyl acrylate, and 1.3 parts of benzoyl peroxide as a polymerization initiator were charged, and uniformly Stir and mix.
Next, 20 parts by weight of a 3% by weight aqueous solution of polyvinyl alcohol (GOHSENOL GL-03, manufactured by Nippon Synthetic Chemical) and 0.5 parts by weight of sodium dodecyl sulfate were added and stirred and mixed uniformly, and then 140 parts by weight of ion-exchanged water. Was introduced.
Next, a polymerization reaction was carried out at 80 ° C. for 15 hours while stirring the aqueous solution under a nitrogen gas stream to obtain fine particles. The obtained fine particles were sufficiently washed with hot water and acetone, and then classified to prepare hard particles. The average particle diameter of the obtained hard particles was 5 μm, the CV value was 3.0%, and the 10% K value was 3000 Mpa.

50 parts by weight of the obtained hard particles were put into a mixed monomer composed of 200 parts by weight of N, N-dimethylformamide, 120 parts by weight of isobutyl methacrylate and 80 parts by weight of methyl methacrylate, dispersed by a sonicator, -Mixed with stirring.
Next, the reaction system was replaced with nitrogen gas, and stirring was continued at 30 ° C. for 2 hours.
Next, 10 parts by weight of 0.1 mol / L ceric ammonium nitrate aqueous solution prepared with 1N nitric acid aqueous solution was added to the reaction system, and after 5 hours of polymerization reaction, the reaction solution was taken out and a 3 μm membrane filter was attached. The particles and the reaction solution were separated by filtration. The obtained particles were sufficiently washed with THF and methanol to obtain shell seed particles [1]. The average particle diameter of the obtained shell seed particles [1] was 5.06 μm (CV value is 3.0%), and a shell seed layer having a thickness of 0.03 μm was formed on the surface of the substrate particles.

In a separable flask, 200 parts by weight of ion-exchanged water, 40 parts by weight of a 5% aqueous solution of polyvinyl alcohol (GOHSENOL GL-03, manufactured by Nippon Synthetic Chemical Co., Ltd.) and 50 parts by weight of core-shell particles (1) are weighed and stirred at 200 rpm. A shell seed particle dispersion [1] was obtained.
Separately, 160 parts by weight of ion-exchanged water, 1.8 parts by weight of polyethylene glycol diacrylate (light acrylate 4EG-A, manufactured by Kyoeisha), 1.8 parts by weight of divinylbenzene, 0.8 part by weight of xylene, benzoyl peroxide 0 0.1 part by weight and 1.2 parts by weight of sodium dodecyl sulfonate were uniformly emulsified with a homogenizer to obtain a polymerizable monomer emulsion.

The obtained polymerizable monomer emulsion is added to the obtained core-shell particle dispersion [1], stirred at 100 rpm, and absorbed into the shell seed layer at room temperature under a nitrogen stream for 24 hours. To obtain polymerizable droplets.
Next, after the stirring speed was set to 200 rpm, 50 parts by weight of a 5% polyvinyl alcohol (GOHSENOL GH-20, manufactured by Nippon Synthetic Chemical) was added and heated to 80 ° C. to polymerize the polymerizable droplets. By heating at 95 ° C., composite particles [1] having a porous layer were obtained.
When the cross section of the obtained composite particle [1] was observed with a transmission electron microscope (TEM), it was a structure in which a porous layer was provided on the surface of the hard particle as shown in FIG. The particle diameter of the composite particles [1] was 7 μm (CV value is 3.0%). The 10% K value of the composite particles [1] was 1000 MPa.

The obtained composite particles [1] were degreased, sensitized, and activated to generate Pd nuclei on the surfaces of the hard particles and the soft layer, and used as catalyst nuclei for electroless plating.
Next, it was immersed in a building bath and a heated electroless Ni plating bath according to a predetermined method to form a Ni plating layer.
Next, electroless replacement gold plating was performed on the surface of the nickel layer to form a conductive layer to obtain conductive particles [1]. The thickness of the Ni plating provided on the surface of the obtained conductive particles [1] was 90 nm, and the thickness of the gold plating was 30 nm.

(2) Preparation of anisotropic conductive material 100 parts of an epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd .: “Epicoat 828”) and 100 parts of trisdimethylaminoethylphenol and toluene as a binder resin are sufficiently obtained using a planetary stirrer. The mixture was dispersed and mixed, applied on the release film at a constant thickness so that the thickness after drying was 10 μm, and toluene was evaporated to obtain an adhesive film containing no conductive particles.

In addition, conductive particles [1] are added to 100 parts of an epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd .: “Epicoat 828”) and 100 parts of trisdimethylaminoethylphenol as a binder resin, and a planetary stirrer is used. To obtain a binder resin dispersion, which is then applied onto the release film with a constant thickness so that the thickness after drying is 10 μm, and the toluene is evaporated to contain conductive particles [1]. An adhesive film was obtained. In addition, the addition amount of electroconductive particle [1] was set so that content in an anisotropic conductive film might be 200,000 piece / cm < ² >.
By laminating an adhesive film containing no conductive particles on the resulting adhesive film containing the conductive particles [1] at room temperature, an anisotropic conductive film [1] having a two-layer structure and having a thickness of 17 μm. Got.

(Example 2)
Production of conductive particles [2] The same particles as in Example 1 were used as hard particles.
In a separable flask, 80 parts by weight of ion-exchanged water, 320 parts by weight of ethanol, 0.5 parts by weight of polyvinylpyrrolidone (K-30), 5 parts by weight of styrene, and 10 parts by weight of hard particles are weighed and mixed uniformly. Thus, a hard particle dispersion was obtained.

Next, a solution in which 10 parts by weight of ion-exchanged water, 40 parts by weight of ethanol, and 0.8 parts by weight of 2,2′-azobisisobutyronitrile are uniformly mixed is added to the hard particle dispersion, and the mixture is stirred at 60 ° C. for 20 hours. After polymerization, washing was performed to obtain shell seed particles [2] having a shell seed layer on the surface of the hard particles.
When the obtained shell seed particles were measured for particle size using a particle size distribution meter (manufactured by Coulter), the average particle size was 5.01 μm, and a shell seed layer having a thickness of 50 nm was formed.

In a separable flask, 200 parts by weight of ion-exchanged water, 40 parts by weight of 5% aqueous solution of polyvinyl alcohol (GL-03, manufactured by Nihon Gosei Co., Ltd.) and 2 parts by weight of shell seed particles are weighed and stirred at 200 rpm to disperse the shell seed particles. A liquid [2] was obtained.
Separately, 160 parts by weight of ion-exchanged water, 1.8 parts by weight of polyethylene glycol diacrylate (light acrylate 4EG-A, manufactured by Kyoeisha), 1.8 parts by weight of divinylbenzene, 0.8 part by weight of xylene, benzoyl peroxide 0 0.1 part by weight and 1.2 parts by weight of sodium dodecyl sulfonate were uniformly emulsified with a homogenizer to obtain a polymerizable monomer emulsion.

The obtained polymerizable monomer emulsion was added to the obtained shell seed particle dispersion [2], stirred at 100 rpm, and the polymerizable monomer was added to the shell seed layer under a nitrogen stream at room temperature for 24 hours. Absorbed to obtain polymerizable droplets.
Then, after setting the stirring speed to 200 rpm, the polymerizable droplets were polymerized by heating to 80 ° C. Furthermore, the composite particle [2] which has a porous layer on the surface of a hard particle was obtained by heating at 100 degreeC.
When the cross section of the obtained composite particle [2] was observed with a transmission electron microscope (TEM), it was a structure in which a soft layer was provided on a part of the surface of the hard particle as shown in FIG. The apparent diameter of the soft layer portion was 7.2 μm, and the length in the major axis direction was 10 μm. Further, the 10% K value of the soft layer portion was 1000 MPa.

The obtained composite particles [2] were degreased, sensitized, and activated to generate Pd nuclei on the surfaces of the hard particles and the soft layer, and used as catalyst nuclei for electroless plating. Next, it was immersed in a building bath and a heated electroless Ni plating bath according to a predetermined method to form a Ni plating layer. Next, electroless replacement gold plating was performed on the surface of the nickel layer to form a conductive layer to obtain conductive particles [2]. The thickness of the Ni plating provided on the surface of the obtained conductive particles was 90 nm, and the thickness of the gold plating was 30 nm.
Thereafter, an anisotropic conductive film [2] was prepared in the same manner as in Example 1.

(Comparative Example 1)
As the hard particles, the same particles as in Example 1 were used.
In a separable flask, 1 part by weight of polyethylene glycol diacrylate (light acrylate 4EG-A, manufactured by Kyoeisha), 2 parts by weight of divinylbenzene (Nippon Steel Chemical) and polyvinylpyrrolidone (K30, manufactured by Wako Pure Chemical Industries), benzoyl peroxide 0 .1 part by weight was added to 200 parts of methanol, stirred and mixed uniformly, and reacted at 50 degrees for 5 hours to obtain flexible particles having a particle size of 550 nm.

Next, 10 parts by weight of the hard particles and 2 parts by weight of the soft particles are put into a hybridization system (manufactured by Nara Machinery Co., Ltd.) and stirred at high speed to stir the composite particles having a soft layer on the surface of the hard particles [3] Got. The particle size of the composite particles having a soft layer was 7 μm.
The obtained composite particles [3] were degreased, sensitized, and activated to generate Pd nuclei on the surfaces of the hard particles and the soft layer, and used as catalyst nuclei for electroless plating.
Next, it was immersed in a building bath and a heated electroless Ni plating bath according to a predetermined method to form a Ni plating layer.
Next, electroless replacement gold plating was performed on the surface of the nickel layer to form a conductive layer to obtain conductive particles [3]. The thickness of the Ni plating provided on the surface of the obtained conductive particles was 90 nm, and the thickness of the gold plating was 30 nm.
Thereafter, an anisotropic conductive film [3] was prepared in the same manner as in Example 1.

(Vertical continuity test)
About the anisotropic conductive films [1] to [3] obtained in Examples 1 and 2 and Comparative Example 1, a glass substrate (width) having an ITO electrode (width 100 μm, height 0.2 μm, length 2 cm) 1 cm, length 2.5 cm), an anisotropic conductive film is cut into 5 × 5 mm and pasted almost at the center, and then the glass substrate having the same ITO electrode is placed at 90 degrees each other. The alignment was performed so as to overlap. The bonded portion of the glass substrate was thermocompression bonded at 120 ° C. under a pressure of 200 N for 30 seconds, and then the resistance value was measured by a four-terminal method to obtain a ratio of 5Ω or less. This test was conducted at n = 20. The gap between the joined electrodes was 5 μm.

As a result, the ratio of the resistance values of the anisotropic conductive films [1] and [2] obtained in Example 1 and Example 2 to 5Ω or less was 100%, whereas Comparative Example 1 The ratio of the resistance value of the anisotropic conductive film [3] obtained in (5) to 5Ω or less was 50%, and it was confirmed that the conductive layer was cracked in the direction parallel to the substrate.

ADVANTAGE OF THE INVENTION According to this invention, the electroconductive particle excellent in connection reliability, an anisotropic conductive material, and a conductive connection structure can be provided.

It is sectional drawing which shows an example of the electroconductive particle of this invention typically. It is sectional drawing which shows an example of the electroconductive particle of this invention typically. It is sectional drawing which shows an example of the electroconductive particle of this invention typically. It is sectional drawing which shows typically a mode that the electrical connection of board | substrates is performed using the electroconductive particle of this invention shown in FIG.

Explanation of symbols

10, 20, 30 Conductive particles 11, 21, 31 Hard particles 12, 22, 32 Porous soft layers 13, 23, 33 Conductive layer 40 Substrate

Claims (5)

Conductive particles comprising substrate particles and a conductive layer formed on the surface of the substrate particles, the substrate particles comprising hard particles and a porous layer formed on the surface of the hard particles. The porous layer is made of a thermoplastic resin, and the conductive layer is characterized in that the 10% K value of the porous layer is ½ or less of the 10% K value of the hard particles. The conductive particle according to claim 1, wherein the porous layer is provided on the entire surface of the hard particle. The conductive particle according to claim 1 , wherein the porous layer has a specific surface area of 1 to 100 m ² / g. An anisotropic conductive material, wherein the conductive particles according to claim 1, 2 or 3 are dispersed in an insulating binder resin. A conductive connection structure comprising the conductive particles according to claim 1, 2, or 3 , or the anisotropic conductive material according to claim 4 .

Images