JP5535507B2 - Conductive particles and manufacturing method thereof - Google Patents

Description

  The present invention relates to a method for producing conductive particles and conductive particles obtained by the method for producing conductive particles.

In general, the conductive particles are used as conductive spacers for conducting vertical conduction of a glass substrate of a liquid crystal display.
Further, it is mixed with a binder resin and the like, for example, ACF (Anisotropic Conductive Film) such as anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, anisotropic conductive sheet, etc. : Anisotropic conductive film) is widely used as a conductive material.

  These conductive particles are used to electrically connect wiring circuit boards to each other, for example, in an electronic device such as a liquid crystal display, a plasma display, a personal computer, and a mobile phone, or to electrically connect a small component such as a semiconductor element to the wiring circuit board. In order to make connections, it is used by being sandwiched between printed circuit boards and electrode terminals, and the amount of use will continue to increase as equipment becomes smaller, lighter, and flatter It is expected.

  Conventionally, as conductive particles suitable for conductive spacers and anisotropic conductive materials, non-conductive fine particles such as resin fine particles and glass beads having a uniform particle diameter have been used as the base particle, In addition, conductive fine particles formed by plating with a metal such as nickel have been reported (see Patent Documents 1 and 2).

However, the nickel-plated conductive particles are problematic in that the plating layer corrodes over time and the electrical resistance increases. In addition, since the nickel plating layer is hard, the plating layer is cracked and peeled off when the conductive particles are compressed and deformed, increasing the electric resistance, and sometimes becoming insulating.
In order to prevent oxidation, gold plating may be applied on top of nickel plating, but even in these cases, the gold plating cannot be protected from cracking or peeling off, as in the case of nickel plating alone. In addition, there are problems such as increased electrical resistance and insulation.

  Electricity, electronic equipment, flat panels, etc., ensure the operation of the equipment by ensuring the conduction of conductive particles, so the above-described decrease in conductivity is fatal to reduce the reliability of the operation of the equipment. So it was a problem.

  Therefore, a new conductive material with improved conduction reliability has not yet been provided to ensure the reliability of equipment, and the particles themselves remain conductive even after the plating film is peeled off. Under the present circumstances, there is a strong demand for the development of conductive particles that are less likely to have a decrease in conductivity even after being subjected to electrical resistance and do not increase in electrical resistance and that have excellent conduction reliability.

JP 09-306231 A JP 2003-064500 A

An object of the present invention is to solve the above-described problems and achieve the following objects.
That is, the present invention retains the good compression characteristics of the base polymer particles, has little decrease in conductivity even after being subjected to compression deformation, has an antioxidant effect and a migration prevention effect due to the plating film layer, Furthermore, since the particles themselves have electrical conductivity, the electrical resistance does not increase even after the plating film layer is peeled off or becomes insulative, and the conductive particles have excellent conduction reliability, and the electrical conductivity. It aims at providing the manufacturing method of the electroconductive particle for manufacturing particle | grains.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, since the polymer / iodine complex doped with iodine is higher in diffusibility and permeability of ions and molecules than the untreated base polymer particles, the base polymer particles are secondarily doped. Metal species are easily diffused, and the diffused metal species react with the doped iodine component to form a metal iodide composite. By reducing the metal iodide composite to metal fine particles, metal fine particles are formed. Since the doped particles are formed, and the metal fine particle doped particles have conductivity by the metal fine particles, the conductive particles in which the base polymer particles themselves are made conductive can be obtained. Furthermore, by conducting electroless plating, conductive particles with plating layer having antioxidation effect and migration prevention effect are obtained. The conductive particles, and the conductive particles with plating layer have good compressive properties of the base polymer particles, and the electroless plating film layer of the conductive particles with plating layer Since it has excellent compression characteristics, the plating film layer is not cracked or peeled off, and therefore it has been found that the electric resistance does not increase and has high conductivity. Completed.

This invention is based on the said knowledge by the present inventors, and the means for solving the said subject are as follows. That is,
<1> A primary doping step of preparing a polymer / iodine complex by doping iodine with respect to the base polymer particles, and reacting a metal species with the polymer / iodine complex to prepare a metal iodide composite. A method for producing conductive particles, comprising at least a secondary doping step and a reduction step of reducing the metal iodide composite to metal fine particles to prepare metal fine particle doped particles.
<2> The method for producing conductive particles according to <1>, including an electroless plating step of electrolessly plating metal fine particle dope particles.
<3> The method for producing conductive particles according to any one of <1> to <2>, wherein the primary doping step is performed by immersing the base polymer particles in a solution containing at least iodine. .
<4> The method for producing conductive particles according to any one of <1> to <3>, wherein the primary doping step is performed under ultrasonic irradiation treatment.
<5> The method for producing conductive particles according to any one of <1> to <4>, wherein the primary doping step is performed under a temperature condition of 0 ° C to 90 ° C.
<6> Any of the above <1> to <5>, wherein the base polymer particles are at least partially crosslinked, the particle diameter is 1 μm to 100 μm, and the coefficient of variation (CV value) of the particles is 10% or less It is a manufacturing method of the electroconductive particle as described above.
<7> The method for producing conductive particles according to any one of <1> to <6>, wherein the secondary doping step is performed by immersing the metal iodide composite in a solution containing a metal species. .
<8> The method for producing conductive particles according to any one of <1> to <7>, wherein the secondary doping step is performed under an ultrasonic irradiation treatment.
<9> The method for producing conductive particles according to any one of <1> to <8>, wherein the secondary doping step is performed under a temperature condition of 0 ° C to 90 ° C.
<10> The method for producing conductive particles according to any one of <1> to <9>, wherein the metal species is at least one of gold, silver, copper, platinum, nickel, palladium, iron, and tin. is there.
<11> The solution containing a metal species is a metal salt solution, and the metal salt is a metal nitrate, metal sulfate, metal acetate, metal carbonate, metal chloride salt, metal bromide salt, and metal iodide, and The method for producing conductive particles according to any one of <1> to <10>, which is any of those coordination compounds.
<12> Conductive particles obtained by the method for producing conductive particles according to <1> to <11>.
<13> The conductive particle according to <12>, wherein the surface resistance value is 10 ⁵ Ω or less.
<14> The conductive particles according to any one of <12> to <13>, which are used in at least one of a conductive spacer and an anisotropic conductive film.

  According to the present invention, the conventional problems can be solved, the object can be achieved, the good compression characteristics of the base polymer particles are maintained, and the conductivity is lowered even after being subjected to compression deformation. Fewer anti-oxidation and migration-preventing effects due to the plating film layer, and further, since the particles themselves are conductive, the electrical resistance increases and becomes insulating even after the plating film layer is peeled off. There can be provided conductive particles excellent in conduction reliability, and a method for producing conductive particles for producing the conductive particles.

FIG. 1 is a conceptual diagram of a method for measuring the compressive conductivity of conductive particles. FIG. 2 is a diagram showing displacement in compression of conductive particles before electroless plating and after a reduction process. FIG. 3 is a diagram showing resistance values obtained at the time of compressive displacement before electroless plating and after the reduction process.

(Method for producing conductive particles)
The method for producing conductive particles of the present invention includes a primary doping step in which a base material polymer particle is doped with iodine to prepare a polymer / iodine composite, and a metal species is reacted with the polymer / iodine composite. A secondary doping step of preparing a metal iodide composite, and a reduction step of reducing the metal iodide composite to metal fine particles to prepare metal fine particle doped particles, and further including other steps as necessary. .

<Primary dope process>
The primary dope step is a step of preparing a polymer / iodine complex by doping (adding) iodine to the base polymer particles.
The polymer / iodine complex is formed by dispersing and adsorbing iodine components such as polyiodine or molecular iodine in the polymer.

-Base polymer particles-
The polymer material of the base polymer particles is not particularly limited as long as it is a polymer compound that can include iodine, and can be appropriately selected depending on the purpose. For example, thermoplastic resin, thermosetting resin Etc.
Examples of the thermoplastic resin include vinyl chloride resin, vinyl acetate resin, polystyrene resin, polyester resin, polyethylene resin, polypropylene resin, acrylic resin, polyamide resin, and acetal resin.
Examples of the thermosetting resin include phenol resin, melamine resin, benzoguanamine resin, alkyd resin, polyurethane resin, epoxy resin, cross-linked acrylic resin, unsaturated polyester resin, vinyl polymer, silicon resin, and the like.
Among these, a crosslinked acrylic resin, a vinyl polymer, and a benzoguanamine resin are preferable.
The said polymeric material may be used individually by 1 type, and may be used in combination of 2 or more type.
The property of the polymer material is not particularly limited and may be appropriately selected according to the purpose. However, the hydrophilic material and the polar group may increase the iodine doping amount. It is preferable in that it can be performed. However, even if the property of the polymer material is neither a hydrophilic group nor a polar group, iodine affinity can be improved by partially hydrolyzing the surface of the base polymer particle with an alkaline solution. It is also possible to increase the amount of iodine dope. Moreover, the iodine dope amount can also be increased by using a solvent mixed with an organic solvent and adjusting the mixing ratio.
There is no restriction | limiting in particular as said alkaline solution, According to the objective, it can select suitably, For example, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, calcium hydroxide aqueous solution, ammonia water, sodium hydrogencarbonate aqueous solution Etc.
In the present specification, the polymer material includes those partially hydrolyzed with the alkaline solution.
The high molecular compound capable of including iodine means a high molecular compound capable of taking a structure in which the iodine component diffuses to the inside and is adsorbed or non-covalently associated in the molecule.

-Manufacturing method-
The method for producing the base polymer particles is not particularly limited and may be appropriately selected depending on the intended purpose. For example, suspension polymerization, seed polymerization, soap-free polymerization, dispersion polymerization, emulsion polymerization, electrostatic spraying method Ink jet method, micro channel method and the like. Commercial products can also be used.

The suspension polymerization is a method in which a monomer is dropped into an aqueous solution to which a protective colloid is added, stirred, droplets are formed by the surface tension of the monomer itself, and heated to obtain the base polymer particles. .
With the seed polymerization, seeds such as polystyrene and PMMA (polymethylmethacrylate) are deposited in water to form uniform microparticles, and the microparticles absorb and enlarge the monomer, then heat, This is a method for obtaining base polymer particles.
The soap-free polymerization is the formation of seed particles mainly using an anionic radical polymerization initiator such as persulfate under the condition that no surfactant is present, and the seed particles absorb and polymerize vinyl monomers. And obtaining the base polymer particles.
The dispersion polymerization is a method in which seed particles are formed in an organic solvent such as alcohol, and vinyl monomer is absorbed and polymerized in the seed particles to obtain the base polymer particles.
In the emulsion polymerization, after forming uniform monomer droplets from uniform holes, the particles are obtained by heating. After forming droplets by so-called membrane emulsification dispersion or SPG (shirasu porous glass) emulsification, heating is performed. It is a method of obtaining the base polymer particles by curing.
The electrostatic spraying method is a method in which a polymer solution is placed in a syringe and a high voltage and pressure are applied to form uniform droplets and the solvent is evaporated to obtain the base polymer particles.
The inkjet method is a method in which the polymer solution is uniformly formed into droplets with an inkjet and at the same time the solvent is evaporated to obtain the base polymer particles.
The microchannel method is a method of obtaining the base polymer particles by taking out a monomer from fine holes having a special shape, forming uniform droplets, and then curing by heating.
Among these, seed polymerization and a method of further classifying particles obtained by other polymerization methods are preferable in that a uniform particle diameter can be obtained.

  Among the methods for producing the base polymer particles, when a monomer is cured by applying heat, a polymerization initiator for polymerizing the monomer is necessary.

--- Monomer ---
The monomer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, styrene derivatives, vinyl esters, unsaturated nitriles, (meth) acrylic acid ester derivatives, conjugated dienes, polyfunctionality And monomers.
Examples of the styrene derivative include styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, chloromethylstyrene, and the like.
Examples of the vinyl esters include vinyl chloride, vinyl acetate, and vinyl propionate.
Examples of the unsaturated nitriles include acrylonitrile.
Examples of the (meth) acrylic acid ester derivatives include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and acrylic. Examples include stearyl acid, stearyl methacrylate, trifluoroethyl acrylate, and trifluoroethyl methacrylate.
Examples of the conjugated dienes include butadiene and isoprene.
Examples of the polyfunctional monomer include bifunctional butanediol diacrylate, butylene glycol diacrylate, dicyclopentanyl diacrylate, diethylene glycol diacrylate, divinylbenzene; bifunctional or more trimethylolpropane diacrylate. , Trimethylolpropane trimethacrylate, tetramethylolpropane tetraacrylate, tetramethylolpropane tetramethacrylate and the like.
Among these, when a compressive strength such as a spacer is required, a bifunctional or higher functional monomer is preferable in that it has compressive elasticity and can suitably maintain the gap.
On the other hand, in the case of maintaining electrical conduction by compressing and deforming like an anisotropic conductive material, copolymerization of a bifunctional monomer alone or a bifunctional monomer and a monofunctional monomer Is preferable in that it can be made flexible.

--- Polymerization initiator ---
The polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include organic peroxides and azo compounds.
Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 8,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethyl Examples include hexanoate and di-t-butyl peroxide.
Examples of the azo compound include azobisisobutyronitrile, azobiscyclohexacarbonitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), and the like.

---- Polymerization temperature ---
There is no restriction | limiting in particular as temperature of the said polymerization, Although it can select suitably according to the kind of monomer to be used, a polymerization initiator, etc., 25 to 100 degreeC is preferable and 50 to 90 degreeC is more preferable.

--- Adjustment of particle size distribution ---
When the desired CV value, that is, the variation coefficient of the particle size distribution cannot be obtained as in the case of the suspension polymerization, or when the desired particle size cannot be obtained, the particle size distribution is adjusted by classification operation. is necessary.
The classification operation method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a dry classification method and a wet classification method.
Examples of the dry classification method include a method of performing classification using a dry cyclone or wind power.
Examples of the wet classification method include methods performed in water such as water classification, wet cyclone, electrostatic classification and the like.

  Whether or not the base polymer particles obtained by the production method are suitable as the base polymer particles used in the production of the conductive particles of the present invention depends on the particle diameter of the obtained base polymer particles and the coefficient of variation of the particle diameter. , Surface resistance value, strength, compression recovery rate, etc.

--- Particle size--
There is no restriction | limiting in particular as a particle diameter of the said base polymer particle, Although it can select suitably according to the objective, 0.5 micrometers-500 micrometers are preferable, and 1 micrometer-100 micrometers are more preferable. When the number average particle diameter is less than 0.5 μm, in the electroless plating step described later, the base polymer particles are likely to be aggregated, and the conductive particles obtained from the aggregated base polymer particles are It becomes a large particle with a large particle diameter, causing a short circuit between adjacent electrodes. Further, the variation in the accuracy of the electrode is relatively greater than the accuracy of the particle diameter, and the conduction reliability is significantly reduced. When the number average particle diameter exceeds 500 μm, its application is very limited.

When the conductive particles obtained by the method for producing conductive particles of the present invention are used as spacers, the particle diameter of the base polymer particles depends on the gap of the liquid crystal cell and is used as an anisotropic conductive material. When used, it depends on the distance between adjacent electrodes.
In general, the anisotropic conductive material has been miniaturized and the distance between adjacent electrodes has been reduced, and the particle diameter tends to be smaller than 3 μm. However, when used as a spacer other than liquid crystal, large particles of about 20 μm to 50 μm may be used.

--- Measurement method ---
The method for obtaining the particle size is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method of measuring with an optical microscope, a method of measuring with an electron microscope, and measuring with a light scattering particle size distribution meter. And a method using a Coulter counter. The number average particle size can be obtained by statistically processing the particle size measured by these methods.

--- CV value (coefficient of variation) ---
The CV value (coefficient of variation) of the particle diameter of the base polymer particles is such that the lower the value, the smaller the variation of the particle diameter, so that a uniform pressure is applied to all the particles. The conductive particles obtained by the production method have significantly improved conduction reliability.
There is no restriction | limiting in particular as said CV value, Although it can select suitably according to the objective, 10% or less is preferable, 5% or less is more preferable, and 3% or less is especially preferable. When the CV value exceeds 10%, it becomes difficult for the conductive fine particles to arbitrarily control the distance between the opposing electrodes.

The CV value (coefficient of variation) can be obtained by the following calculation formula.
CV value (%) = (σ / Dn) × 100%
In the above formula, “σ” represents the standard deviation (μm) of the particle diameter, and “Dn” represents the number average particle diameter (μm).

-Surface resistance value-
There is no restriction | limiting in particular as surface resistance value of the said base polymer particle, According to the objective, it can select suitably.
The method for measuring the surface resistance value is not particularly limited and can be appropriately selected depending on the purpose. For example, the microscopic tester (for example, MCT-W200J: manufactured by Shimadzu Corp.) In order to measure the surface resistance value of the base polymer particles, a smooth indenter made of a metal cone having a diameter of 50 μm, a metal sample table, and a resistance measuring device (RS-232C) are attached, and the compression speed is 2.2 mN / sec. , One base polymer particle is compressed under the condition of a maximum test load of 10 g, and the minimum value among the resistance values obtained until the particle is compressed and displaced is broken. It can be a surface resistance value.

--Strength--
The method for measuring the strength of the base polymer particles is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method for measuring compressive deformation strength and a method for measuring compressive fracture load value. Can be mentioned.

---- Compressive deformation strength ---
The compressive deformation of the base polymer particles refers to deformation of the material under a compressive load. When a load of 10 g is applied to one particle of the base polymer particles, the particle diameter is deformed by 10% (hereinafter, “ The load value at the time of “10% compression deformation” is referred to as S10 strength (10% compression strength).

The method for measuring the S10 intensity is not particularly limited and may be appropriately selected depending on the intended purpose. For example, using a micro compression tester (for example, MCT-W200J: manufactured by Shimadzu Corporation), particles Can be obtained by the following Hiramatsu equation by measuring the compression displacement (mm) when compressed with a smooth indenter end face made of a diamond cone having a diameter of 50 μm under the conditions of a compression speed of 2.6 mN / sec and a maximum test load of 10 g. it can.
S10 = 2.8 × 10 ³ P × 1 / πd ²
In the Hiramatsu equation, “S10” is a load value (N) in 10% compression deformation of the base polymer particles, “P” is a compression displacement (mm) in 10% compression deformation of the base polymer particles, “ “d” represents the radius (mm) of the base polymer particle.

---- Compressive fracture load value ----
The compressive fracture load value of the base polymer particles refers to a load value when the base polymer particles begin to break under a compressive load.
The compressive fracture load value is preferably 300 MPa to 3,000 MPa, and more preferably 40 MPa to 1,500 MPa.
When the compressive fracture load value is less than 300 MPa, the base polymer particles are destroyed when compressively deformed, and the function as a conductive material is not achieved. When the compressive breaking load value exceeds 3,000 MPa, when used as a spacer, the color filter is broken, or so-called low-temperature foaming in which a vacuum state is generated in the LCD at low temperatures is not preferable.

  There is no restriction | limiting in particular as a measuring method of the said compression fracture load value, According to the objective, it can select suitably, For example, using a micro compression tester (For example, MCT-W200J: Shimadzu Corporation Corp.), One base polymer particle is compressed under the conditions of a smooth indenter end face made of a diamond cone having a diameter of 50 μm and a compression rate of 2.2 mN / sec and a maximum test load of 10 g. For example, a method of measuring a load value at the time when the rupture breaks.

-Compression recovery rate-
The compression recovery rate of the base polymer particles refers to the relationship between the load value and compression deformation when the load is reduced after the base polymer particles are compressed.
There is no restriction | limiting in particular as a compression recovery rate of the said base polymer particle, Although it can select suitably according to the objective, 20% or more is preferable and 40% or more is more preferable. When the compression recovery rate is less than 20%, when the conductive particles obtained by the method for producing conductive particles are compressed, they do not return to their original shape even if they are deformed. Inability to follow expansion and contraction, etc., may cause poor connection.

--- Measurement method ---
There is no restriction | limiting in particular as a measuring method of the said compression recovery rate, According to the objective, it can select suitably, For example, it measures with a micro compression tester (For example, MCT-W200J: Shimadzu Corporation Corp. make). Can do.
Specifically, after compressing the base polymer particles to an inversion load value of 9.8 mN, the end point when removing the load is set to an origin load value of 0.98 mN, and the compression rate in load and load removal is 0.284 mN / When measured as seconds, the amount of restoration (L1-L2), which is the difference between the displacement (L1) to the reversal point and the displacement (L2) from the reversal point to the point where the origin load value is taken, and the reversal A value expressed by multiplying the ratio (L1−L2) / (L1) to the compression amount (L1), which is the displacement up to the point, by 100 can be used as the recovery rate (%).
That is, it can be obtained by the following calculation formula.
Compression recovery rate (%) = restoration rate / compression rate × 100 = 100 × (L1-L2) / L1
In the above formula, “L1” represents the displacement (μm) until reversal, and “L2” represents the displacement (μm) up to the origin load value.

-Iodine-
The iodine contains at least elemental iodine, and further contains other components as necessary.
There is no restriction | limiting in particular as a state of the said iodine, Although it can select suitably according to the objective, The state of a solution is preferable.
When the iodine is in a solution state (hereinafter, sometimes referred to as “iodine solution”), the concentration of simple iodine in the iodine solution is not particularly limited, and may vary depending on the type of the base resin, the processing time, and the like. Although it can select suitably according to it, 0.01N-10N are preferable and 0.1N-1N are more preferable. If the elemental iodine is less than 0.01N, the penetration depth of iodine may be insufficient, or iodine may be easily detached through volatilization after doping, and the elemental iodine may be reduced to 10N. Exceeding this is not suitable because it may cause degradation of the polymer chain or an addition reaction as a chemical group.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, an iodine compound, an organic compound, etc. are mentioned.

--- Iodine compound ---
When the iodine compound is added to the iodine solution, the solubility of the simple iodine in the iodine solution can be adjusted, and the amount and state of the iodine component doped into the base polymer particles can be controlled. preferable.
There is no restriction | limiting in particular as said iodine compound, According to the objective, it can select suitably, For example, a metal iodide, an inorganic iodide, etc. are mentioned.
Examples of the metal iodide include potassium iodide, sodium iodide, lithium iodide, rubidium iodide, cesium iodide, nickel iodide and the like.
Examples of the inorganic iodine compound include ammonium iodide.
The said iodine compound may be used individually by 1 type, and may be used in combination of 2 or more type.
The concentration of the iodine compound in the iodine solution is not particularly limited and can be appropriately selected depending on the amount of the simple iodine, etc., but a molar ratio of 30 times or less of iodine is preferable, A concentration of 10 times or less of iodine is more preferable. When the iodine compound has a molar ratio of 2 times or less, it is difficult to adjust the solubility of the simple iodine, and when the molar ratio exceeds 30 times the iodine concentration, iodine in the aqueous solution Although dissolution becomes easy, the performance of diffusing iodine into the resin is reduced.

--- Organic compounds ---
When the iodine is a solution, it is preferable in that the wettability of the base polymer particles with respect to the iodine solution can be mainly controlled by adding the organic compound to the iodine solution.
There is no restriction | limiting in particular as said organic compound, According to the objective, it can select suitably, For example, water, such as monohydric alcohol, polyhydric alcohol, acetone, dimethyl sulfoxide, N, N- dimethylformamide, is arbitrarily set. Examples include organic solvents to be mixed.
Examples of the monohydric alcohol include methanol, ethanol, isopropanol and the like.
Examples of the polyhydric alcohol include ethylene glycol and glycerin.
The said organic compound may be used individually by 1 type, and may be used in combination of 2 or more type.
There is no restriction | limiting in particular as a state of the said organic compound, Although it can select suitably according to the objective, The state of aqueous solution is preferable.
There is no restriction | limiting in particular as addition amount with respect to the water of the said organic compound, Although it can select suitably according to the objective, 5 mass%-90 mass% are preferable, and 20 mass%-80 mass% are more preferable. When the organic compound is less than 5% by mass, the diffusion performance of iodine with respect to the base polymer particles cannot be improved, and when it exceeds 90% by mass, the solubility of the iodine compound decreases.

-Iodine doping method-
In the primary doping step, a method for doping iodine is not particularly limited as long as the base polymer particles can form a polymer / iodine complex, and can be appropriately selected according to the purpose. For example, a method of immersing the base polymer particles in an iodine solution, a method of spraying an iodine solution, a method of exposing to iodine vapor for a long time, a method of melting and molding by mixing with iodine alone, etc. Among these, a method of immersing the base polymer particles in an iodine solution is preferable.

The doping temperature is not particularly limited and can be appropriately selected depending on the purpose. The doping can be performed at room temperature, but heating is preferable because the doping time can be shortened.
There is no restriction | limiting in particular as the temperature of the said heating, Although it can select suitably according to the objective, 0 to 90 degreeC is preferable and 5 to 30 degreeC is more preferable.
There is no restriction | limiting in particular as time to dope, According to the objective, it can select suitably.
In addition, the conditions for doping iodine are not particularly limited and may be appropriately selected depending on the purpose. However, it is possible to uniformly dope iodine into the polymer fine particles under the ultrasonic irradiation treatment conditions. It is preferable at the point which can do.

<Secondary dope process>
It is a step of preparing a metal iodide composite by reacting a metal species with the polymer / iodine composite.
In the metal iodide composite, the metal species diffuses in the polymer / iodine complex, and the iodine ions separated from polyiodine that is a constituent element of the polymer / iodine complex react with the metal species. Thus, a metal iodide is formed.
In addition, even when the same metal salt is doped into the same polymer / iodine composite, the metal iodide composite is subjected to the conditions in the primary doping step and the secondary doping step (for example, the doping amount of iodine). Depending on the amount of the metal species to be reacted, the processing time, and the temperature history, the particle diameter and the shape of the base polymer particles, and the like, the appearance and characteristics may be different.

-Metal species-
There is no restriction | limiting in particular as said metal seed | species, According to the objective, it can select suitably, For example, gold | metal | money, silver, copper, platinum, nickel, palladium, iron, tin etc. are mentioned.
The metal seed | species used for the said secondary dope process may be used individually by 1 type, and may be used in combination of 2 or more type.
The metal species may be in a metal ion state.

When the metal species is reacted with the polymer / iodine complex, the metal species is preferably in a solution state, and the solution containing the metal species is preferably a metal salt solution.
The metal salt is not particularly limited as long as it is a water-soluble metal salt, and can be appropriately selected according to the purpose. However, those that do not cause precipitation are preferable, for example, metal nitrate, metal sulfate, metal acetate Metal carbonates, metal chloride salts, metal bromide salts, metal iodides, and coordination compounds thereof.
There is no restriction | limiting in particular as a density | concentration of the solution of the said metal salt, Although it can select suitably according to the objective, 0.01 mol / L-10 mol / L are preferable, and 0.1 mol / L-1 mol / L are more preferable.
The solution may contain an organic solvent optionally mixed with water.
The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include methanol, ethanol, isopropanol, ethylene glycol, glycerin, acetone, dimethyl sulfoxide, N, N-dimethylformamide and the like. .

-Metal species doping method-
In the secondary doping step, the method of reacting the metal species is not particularly limited as long as the polymer / iodine complex is a method capable of forming a metal iodide composite, and is appropriately selected according to the purpose. For example, there are a method of immersing the polymer / iodine complex in a solution containing a metal species, a method of spraying a solution containing a metal species, and the like. Among these, the polymer / iodine complex can be used. A method of immersing in a solution containing a metal species is preferable.

The doping temperature is not particularly limited and can be appropriately selected depending on the purpose. The doping can be performed at room temperature, but heating is preferable because the doping time can be shortened.
There is no restriction | limiting in particular as the temperature of the said heating, Although it can select suitably according to the objective, 0 to 90 degreeC is preferable and 30 to 60 degreeC is more preferable.
There is no restriction | limiting in particular as time to dope, According to the objective, it can select suitably.
The method of reacting the metal species is not particularly limited and may be appropriately selected according to the purpose. However, the metal iodide can be formed more uniformly by performing the treatment under ultrasonic irradiation conditions. It is preferable in that it can be performed.

In the secondary doping step, the polymer / iodine complex is immersed in a solution containing a metal species, or the polymer / iodine complex is sprayed with a solution containing the metal species, and then the metal iodide composite is formed. It can be stopped by washing with a solution containing no iodine or metal species.
Depending on the concentration, temperature, and treatment time of the iodine doping in the primary doping step, the reaction of the metal species in the secondary doping step, and the reagent solution at the time of washing, the polymer / iodine complex may be contained inside the polymer / iodine complex. Since the precipitated metal salt can be re-eluted and optimal precipitation according to the penetration depth can be achieved, the concentration of the metal species on the surface of the metal iodide composite can be adjusted.
The unreacted iodine component remaining inside the polymer particles may affect the metal phase after the reduction step or electroless plating step described later, but the unreacted iodine component was made of an organic solvent such as acetone. It can be removed from the inside of the polymer particles by washing or high temperature heat treatment. In the heat treatment, it is more effective to perform under reduced pressure because iodine can be efficiently volatilized at a lower temperature.

<Reduction process>
The reduction step is a step of preparing the metal fine particle dope particles by reducing the metal iodide composite to metal fine particles.
The reduction of the metal on the surface of the base polymer particle is performed in the metal iodide composite by reducing the metal ion to the metal by electron donation by the reducing agent, and accompanying this, the iodine ion diffuses into the aqueous solution. It proceeds by being released from the polymer phase.
There is no restriction | limiting in particular as a method to perform the said reduction | restoration, According to the objective, it can select suitably.
Metal iodide usually has very low ionic conductivity at room temperature, and ionic conduction is not induced under high temperature conditions (for example, about 150 ° C. or more in the case of silver iodide). When a compound composite is formed, ion conduction and diffusion occur relatively easily even at room temperature without raising the temperature to the transition point. For this reason, for example, the metal iodide composite is reduced to the metal particles because the metal ions easily move by being left at a temperature close to room temperature (for example, 5 ° C. to 30 ° C.). .
The time for performing the reduction is not particularly limited as long as the metal can be reduced, and can be appropriately selected according to the purpose.

The reduction can promote reduction to fine metal particles by a method such as reducing agent, complex ion formation, and heating.
There is no restriction | limiting in particular as said reducing agent, According to the objective, it can select suitably, For example, acidic hydrogen peroxide solution, sodium borohydride, sodium thiosulfate etc. are mentioned.
There is no restriction | limiting in particular as the temperature of the said heating, Although it can select suitably according to the objective, 80 to 200 degreeC is preferable and 20 to 80 degreeC is more preferable.
The method for forming the complex ion is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method of immersing in an aqueous solution to which a complexing agent such as an ammoniacal compound or an amine is added. It is done.
The metal iodide composite is preferably reacted with an excessive amount of metal species. Such an iodide composite is prepared, for example, by shortening the cleaning time after secondary doping. be able to.

  The metal fine particle doped particles are conductive particles having conductivity due to metal fine particles formed on the surface of the base polymer particles.

<Other processes>
The other steps are not particularly limited and may be appropriately selected according to the purpose. However, electroless plating step, molding step, crystallinity control, molecular weight control, isomerization by blending, viscosity control by cross-linking reaction. , Heat treatment, environmental atmosphere during heat treatment, swelling treatment with a solvent, and the like. Among these, it is preferable to further include an electroless plating step of electroless plating the metal fine particle dope particles obtained in the reduction step.

-Electroless plating process-
The electroless plating step is a step of electroless plating the metal fine particle dope particles.
The electroless plating is a conductive plating formed on the surface of the metal fine particle doped particles.
Due to the electroless plating process, it has conductivity with very low electrical resistance, and also has an antioxidant effect, and metal ions move due to conduction for a long time, causing contamination to the part that needs insulation, resulting in insulation failure. Conductive particles having a so-called migration preventing effect (hereinafter, sometimes referred to as “conductive particles with plating layer”) can be obtained.

-Plating agent-
The plating agent used in the electroless plating step is not particularly limited as long as it is a conductive material, and can be appropriately selected according to the purpose. However, depending on the material, the plating film layer becomes too hard and cracks. May be easier. Examples of the material in which the plating film layer becomes too hard include nickel and chromium. When nickel and chromium are used as the plating agent, the coating layer is hard, so even if the thickness of the plating coating layer is reduced, the effect as a plating coating layer appears more than necessary, and the coating strength increases, There is a tendency for cracking and peeling.
As the material used for the plating agent, for example, gold, silver, copper, platinum, nickel, palladium, tin, aluminum, iron, and the like are preferable, and among these, a metal film that maintains the shape of fine particles is formed. Copper, palladium is more preferable.
The plating agent used in the electroless plating step may be used alone or in combination of two or more.
There is no restriction | limiting in particular as a state of the said plating agent, Although it can select suitably according to the objective, The state of a solution is preferable. There is no restriction | limiting in particular as said solution, Although it can select suitably according to the objective, The mixed solution of water and ethanol is preferable. The mixing ratio of water and ethanol is not particularly limited and may be appropriately selected depending on the intended purpose. Water: ethanol is preferably 1: 4 to 4: 1 (V / V).
There is no restriction | limiting in particular as a density | concentration of the said plating agent in the said aqueous solution, According to the objective, it can select suitably.

-Electroless plating method-
The method for plating the metal fine particle dope particles with the plating agent is not particularly limited and can be appropriately selected according to the purpose. For example, the metal fine particle dope particles are mixed into the mixed solution containing the plating agent. The method of immersing, the method of spraying the mixed solution containing the said plating agent, etc. are mentioned, Among these, the method of immersing the said metal fine particle dope particle in the mixed solution containing the said plating agent is preferable.

There is no restriction | limiting in particular as temperature which performs the said plating, Although it can select suitably according to the objective, 5 to 80 degreeC is preferable and 20 to 60 degreeC is more preferable.
There is no restriction | limiting in particular as time to perform the said plating, Although it can select suitably according to the objective, 0.1 hours-120 hours are preferable, and it considers the uniformity and productivity of plating, and 1 hour- More preferred is 24 hours.

-Structure of electroless plating film layer-
There is no restriction | limiting in particular as a structure of the said electroless-plating film layer, According to the objective, it can select suitably, The single layer structure (for example, single metal structure which consists of one type of layer selected from the said material) ) Or a laminated structure made of a plurality of materials (for example, a plurality of metal layers).
There is no restriction | limiting in particular as thickness of the said film layer, Although it can select suitably according to the objective, 1 nm or more is preferable, 2 nm-100 nm are more preferable, and 3 nm-20 nm are especially preferable. If the thickness of the coating layer is less than 1 nm, there is a possibility that a portion lacking the plating coating layer may be generated, so that there is a risk of lowering the conduction reliability. When the thickness of the coating layer exceeds 100 nm, the state becomes the same as that of the conventional plating layer of conductive particles, the strength of the plating coating layer itself becomes too strong, and it is easily cracked or peeled off.

(Conductive particles)
The conductive particles of the present invention obtained by the method for producing conductive particles of the present invention are particles in which the surface of the base polymer particles is made conductive by metal fine particles.
There is no restriction | limiting in particular as a surface resistance value of the said electroconductive particle, Although it can select suitably according to the objective, 10 < ⁵ > (ohm) or less is preferable and 10 < ³ > (ohm) or less is more preferable.
There is no restriction | limiting in particular as a method of measuring the said surface resistance value, According to the objective, it can select suitably, For example, the method etc. which confirm by a conductive compression test are mentioned.

<Conductive particles with plating layer>
The conductive particles in which the surface of the base polymer particles is made conductive by metal fine particles are conductive particles with a plating layer, on which an electroless plating film layer is further formed by the electroless plating step. It is preferable.
There is no restriction | limiting in particular as a surface resistance value of the said electroconductive particle with a plating layer, Although it can select suitably according to the objective, 10 ² ohms or less are preferable and 10 ohms or less are more preferable.
There is no restriction | limiting in particular as a method of measuring the said surface resistance value, According to the objective, it can select suitably, For example, the method etc. which confirm by a conductive compression test are mentioned.

<Conductive compression test>
An outline of the conductive compression test will be described with reference to FIG. A smooth indenter 1 made of a metal cone having a diameter of 50 μm and a metal sample so that the surface resistance value of the conductive particles can be measured on a micro compression tester (for example, MCT-W200J: manufactured by Shimadzu Corporation) A base 3 and a resistance measuring device 4 (RS-232C) are attached, and one conductive particle 2 is compressed under the conditions of a compression speed of 2.2 mN / sec and a maximum test load of 10 g, and the particles are compressed and displaced. The minimum value among the resistance values obtained before the breakdown can be used as the conductivity evaluation.

<Application>
The conductive particles and the conductive particles with a plating layer are a combination of the base polymer particles, the metal species used for the preparation of the metal iodide composite, the metal used for the electroless plating, the base It can be used as various functional materials according to the particle diameter of the material polymer particles. For example, it can be used for conductive spacers, conductive materials for ACF, conductive materials for electronic paper, solder balls, and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not restrict | limited to these Examples at all.

(Example 1: Conductive particles for conductive spacer)
<Primary dope process>
-Base polymer particles-
Haya beads L-11 (manufactured by Hayakawa Rubber Co., Ltd.) (particle shape: spherical) was used as the base polymer particles of the conductive spacer.

--- Particle size--
The particle diameter of the acrylic resin spheres was measured for 30,000 particles with a Coulter Multisizer III (manufactured by Beckman Coulter, Inc.) and then statistically processed with a computer using the attached software to obtain a number average particle meter. However, it was 5.11 μm.
The calculated CV value (coefficient of variation) of the particles was calculated from the following formula, with the calculated number average particle size (μm) being “Dn” and the standard deviation (μm) of the particle size being “σ”.
CV value (%) = (σ / Dn) × 100%
The CV value (coefficient of variation) of the acrylic resin sphere particles was 4.0%.

-Surface resistance value-
A smooth indenter made of a metal cone having a diameter of 50 μm, a metal sample stage, and a resistance so that the surface resistance value of the acrylic resin can be measured on a micro compression tester (MCT-W200J: manufactured by Shimadzu Corporation) Obtained by attaching a measuring instrument (RS-232C), compressing one acrylic resin under the conditions of a compression speed of 2.2 mN / sec and a test load of 10 g, until the acrylic resin is compressed and displaced and destroyed. When the minimum value was measured, the surface resistance value of the acrylic resin was 6.8 × 10 ¹⁵ Ω.

−−Compressive fracture load value−−
Using a micro-compression tester (MCT-W200J: manufactured by Shimadzu Corporation), particles are smooth indenter end faces made of a diamond cone having a diameter of 50 μm, under conditions of a compression rate of 2.2 mN / sec and a maximum test load of 10 g. When one acrylic resin sphere was compressed and the load value when the acrylic resin sphere was broken was measured, the compression failure load value of the acrylic resin sphere was 1,000 MPa.

-10% compressive strength-
The 10% compressive strength of the acrylic resin spheres was measured using a micro compression tester (MCT-W200J: manufactured by Shimadzu Corporation), and the acrylic resin spheres had a smooth indenter end face made of a diamond cone having a diameter of 50 μm. The compression displacement (mm) when compressed under conditions of 2 mN / sec and a maximum test load of 10 g was measured and determined by the following Hiramatsu equation.
S10 = 2.8 × 10 ³ P × 1 / πd ²
The 10% compressive strength of the acrylic resin sphere was 650 MPa.

-Compression recovery rate-
The compression recovery rate of the acrylic resin sphere was determined by compressing the acrylic resin sphere to a reverse load value of 9.8 mN using a micro compression tester (MCT-W200J: manufactured by Shimadzu Corporation), then removing the load and determining its end point. The origin load value was 0.98 mN, and the compression rate at load and load removal was measured at 2.2 mN / sec.
The displacement from the reversal point to the point where the origin load value is obtained is defined as “L2”, and the displacement from the reversal point to “L1” is obtained by the following calculation formula.
Compression recovery rate (%) = restoration rate / compression rate × 100 = 100 × (L1-L2) / L1
The compression recovery rate of the acrylic resin sphere was 75%.

-Dope of iodine-
3 g of the acrylic resin spheres are dissolved in 1.5 mol / L iodine and 5 mol / L ammonium iodide in 20 mL of 50% by mass ethanol aqueous solution (hereinafter sometimes referred to as “iodine-ammonium iodide solution”). It was thrown into. At this time, the aggregates of the large resin fine particles were previously crushed.
It was immersed in the iodine-ammonium iodide solution kept at 10 ° C. for 10 to 20 minutes to obtain an acrylic resin ball iodine complex.

<Secondary dope process>
The acrylic resin spherical iodine complex obtained in the primary dope process was washed with a 50% by mass aqueous ethanol solution while being filtered. The iodine complex produced inside or near the surface of the acrylic resin sphere was immersed in a 2.5 mol / L silver nitrate-50 mass% ethanol aqueous solution for 4 days to react with the metal species to obtain a silver iodide composite.

<Reduction process>
After the silver iodide composite obtained in the secondary doping step is washed with 50% by mass ethanol, it is further reduced to metallic silver by heating at 180 ° C. for 72 hours to 150 hours in the atmosphere. Conductive particles for conductive spacers having silver fine particles on the particle surface were obtained.

<Conductive compression test>
-Method-
The surface resistance value of the conductive particles for the conductive spacer was measured by a conductive compression test shown in FIG. That is, a smooth indenter 1 made of a metal cone having a diameter of 50 μm and a metal for measuring the surface resistance value of the conductive particles for the conductive spacer on a micro compression tester (MCT-W200J: manufactured by Shimadzu Corporation) A sample stage 3 and a resistance measuring device 4 (RS-232C) are attached, and one conductive particle 2 for a conductive spacer is compressed under the conditions of a compression speed of 2.2 mN / second and a maximum test load of 10 g. The minimum value among the resistance values obtained until the conductive particles for the conductive spacer were compressed and displaced and used for destruction was used.

-Result-
The surface resistance value of the conductive particles for conductive spacers obtained in Example 1 was 3.5 × 10 ⁷ Ω.
From this result, the conductive particles for the conductive spacer obtained in Example 1 retain the good compression characteristics of the acrylic resin that is the base polymer particle, and the silver fine particles formed on the particle surface It was found to have excellent conductivity.
Therefore, it is considered that the conductive particles of the present invention can be suitably used as a conductive spacer having high reliability.

(Example 2: Conductive particles for ACF)
<Primary dope process>
-Base polymer particles-
Acrylic resin spherical powder produced by the following method was used as the base polymer particles of the conductive particles for ACF.
That is, in dispersion polymerization, 9 g of PVP (polyvinylpyrrolidone) K-30 (manufactured by Nippon Shokubai Co., Ltd.) was dissolved in 180 g of ethanol, and then azobisisobutyronitrile (Japanese) was dissolved in 5 g of styrene monomer (manufactured by Tosoh Corporation). A solution obtained by dissolving 0.05 g (manufactured by Kosei Pharmaceutical Co., Ltd.) was added and reacted by stirring at 50 rpm and 80 ° C. for 16 hours while blowing nitrogen, and a uniform particle dispersion (polystyrene dispersion) of 300 nm polystyrene was obtained. Obtained.
Next, 5 g of 1-chlorododecane was added to 50 g of water in which 1% by mass of SDS (sodium dodecyl sulfate) was dissolved, and dispersion treatment 1 was obtained by carrying out a dispersion treatment for 1 hour with an ultrasonic homogenizer.
The dispersion 1 was added to the polystyrene dispersion and stirred at room temperature at 50 rpm for 16 hours to absorb 1-chlorododecane into polystyrene particles to obtain a 1-chlorododecane-absorbing polystyrene particle dispersion.
Dissolve 1 g of BPO (benzoyl peroxide) in 100 g of polyethylene glycol diacrylate (manufactured by Hitachi Chemical Co., Ltd.), add to 2,000 g of water in which 1% by mass of SDS is dissolved, and disperse with a high-speed homogenizer for 30 minutes. Thus, a dispersion 2 was obtained.
The 1-chlorododecane-absorbing polystyrene particle dispersion was added to the dispersion 2, and the mixture was stirred at 50 rpm and room temperature for 16 hours to obtain a dispersion 3 in which the monomer was absorbed into the polystyrene particles.
The dispersion 3 was reacted by stirring at 50 rpm and 80 ° C. for 24 hours to prepare an acrylic resin sphere dispersion having a uniform particle size.
The acrylic resin sphere dispersion was filtered, washed with pure water, further filtered, and dried to obtain an acrylic resin sphere powder.

--- Particle size--
When the number average particle size of the acrylic resin spheres was determined in the same manner as in Example 1, it was 3.0 μm. Further, the CV value (coefficient of variation) of the particles was 4.0%.

-Surface resistance value-
When the surface resistance value of the acrylic resin sphere was measured by the same method as in Example 1, it was 5.4 × 10 ¹⁵ Ω.

−−Compressive fracture load value−−
When the compression failure load value of the acrylic resin sphere was measured by the same method as in Example 1, it was not broken by compression of 1 g.

-10% compressive strength-
The 10% compressive strength of the acrylic resin sphere was 50 MPa when measured by the same method as in Example 1 with a test load of 10 g added.

-Compression recovery rate-
When the compression recovery rate of the acrylic resin spheres was measured by the same method as in Example 1, the compression recovery rate of the acrylic resin spheres was 40%.

-Dope of iodine-
2 g of the acrylic resin spheres were put into a 50 ml water / ethanol (water: ethanol = 1: 1 (V / V)) mixed solution in which 0.5 mol / L iodine and 2 mol / L potassium iodide were dissolved. At this time, the aggregates of the large resin fine particles were previously crushed.
While the solution kept at 50 ° C. was irradiated with ultrasonic waves for 1 hour, iodine was introduced into the fine particles to obtain an acrylic resin sphere iodine complex.

<Secondary dope process>
The acrylic resin spherical iodine complex obtained in the primary dope process was washed with a 0.2% by mass aqueous sodium thiosulfate solution. The iodine solution adhering to the surface of the acrylic resin ball-iodine complex was put into 100 mL of 0.15 mass% ammonium chloride aqueous solution containing 0.1 mass% palladium chloride, and at 80 ° C. for 1 hour, iodine and Palladium ions were reacted to obtain a palladium iodide composite.

<Reduction process>
The palladium iodide composite obtained in the second step was reduced to metallic palladium with a 0.025% by mass aqueous sodium borohydride solution to obtain palladium fine particle doped particles.

<Electroless plating process>
The palladium fine particle dope particles obtained in the reduction step were charged into a mixed solution of water / ethanol (water: ethanol = 1: 1 (V / V)) in which 0.05 mol / L of silver nitrate was dissolved. A silver plating film layer was formed under the reaction conditions of ° C and 24 hours to 120 hours.
By observing these particles under a high-magnification optical microscope using transmitted light, the black particles were selected as fine particles that had been plated to obtain conductive particles for ACF.

<Compressive conductivity test>
-Method-
About the said conductive particle for ACF, the surface resistance value was measured by the compression conductive test shown in FIG.
The compression conductivity test was carried out by using a micro compression tester (MCT-W200J: manufactured by Shimadzu Corporation), a smooth indenter 1 made of a metal cone having a diameter of 50 μm, a metal sample table 3, and a resistance measuring instrument 4 (RS- 232C), and compressing one ACF conductive particle 2 under the conditions of a compression speed of 2.2 mN / sec and a maximum test load of 10 g, until the ACF conductive particles are compressed and displaced The minimum value among the resistance values obtained in the above was used as the evaluation of conductivity.
FIG. 1 is a conceptual diagram of a method for measuring the compressive conductivity of conductive particles, FIG. 2 is a displacement in compression of conductive particles before electroless plating and after the reduction process, and FIG. 3 is before electroless plating and after the reduction process. The resistance value obtained at the time of compressive displacement was shown.

-Result-
The conductive particles before electroless plating and after the reduction process obtained in Example 2 are 70% conductive particles for ACF, the surface resistance value is 2.0 × 10 ² Ω or less, and 30% conductive particles. The surface resistance value of the film exhibited a resistance value of 1.0 × 10 ² Ω or less and was confirmed to have excellent conductivity.
In addition, the conductive particles after electroless plating do not break the plating film layer even at a deformation rate of 50%, and retain the good compression characteristics of the base polymer particles, and the plating film layer also has good compression characteristics. Thus, it has been found that even when compressed, it retains good electrical conductivity.
Therefore, it is thought that the electroconductive particle with a plating layer of this invention can be used suitably as an anisotropic conductive material which has high reliability.

The method for producing conductive particles of the present invention retains the good compression characteristics of the base polymer particles, has little decrease in conductivity even after undergoing compression deformation, and further has an antioxidant effect due to the plating film layer, and Since it has an effect of preventing migration and the plating film layer also has excellent compression characteristics, there is little risk of cracking and peeling of the plating film layer. Even if the plating film layer is peeled off, the base polymer particle itself Since it has excellent conductivity, it can be suitably used for the production of conductive particles excellent in conduction reliability without increasing electrical resistance or becoming insulating even after the plating film layer is peeled off.
In addition, the conductive particles of the present invention can be suitably used as a conductive spacer and an anisotropic conductive material, and improve the reliability of the operation of the device by ensuring conduction of electricity, electronic devices, flat panels, etc. Is possible.

DESCRIPTION OF SYMBOLS 1 Indenter 2 Conductive particle 3 Metal sample stand 4 Resistance measuring device

Claims (7)

A primary dope step of preparing a polymer / iodine complex by doping iodine with respect to the base polymer particles;
A secondary doping step of preparing a metal iodide composite by reacting a metal species with the polymer / iodine composite;
A reduction step of reducing the metal iodide composite to metal fine particles to prepare metal fine particle doped particles;
At least look at including the,
The base polymer particle is a cross-linked acrylic resin having at least partly cross-linked, a particle diameter of 1 μm to 100 μm, and a particle variation coefficient (CV value) of 10% or less . Particle production method.   The method for producing conductive particles according to claim 1, further comprising an electroless plating step of electrolessly plating the metal fine particle dope particles. The method for producing conductive particles according to claim 1, wherein the primary dope step is performed by immersing the base polymer particles in an iodine solution containing iodine and an organic solvent.   The method for producing conductive particles according to any one of claims 1 to 3, wherein the metal species is at least one of gold, silver, copper, platinum, nickel, palladium, iron, and tin.   Conductive particles obtained by the method for producing conductive particles according to any one of claims 1 to 4. The conductive particles according to claim ⁵ , wherein the surface resistance value is 10 ⁵ Ω or less. The electroconductive particle in any one of Claim 5 to 6 used for at least any one of an electroconductive spacer and an anisotropic conductive film.