JP2007194210A - Conductive fine particle and anisotropic conductive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive fine particle having high corrosion resistance and a low resistance value, which is suppressed in separation of a conductive layer during production and thermal compression bonding as well as migration during use; and to provide an anisotropic conductive material obtained by using such a conductive fine particle. <P>SOLUTION: This conductive fine particle is composed of a base fine particle having a conductive layer wherein a nickel layer, a silver layer and a layer of a noble metal nobler than silver are sequentially formed on a surface thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention is a conductive fine particle that suppresses peeling of a conductive layer during production and thermocompression bonding and migration during use, and has high corrosion resistance and low electrical resistance, and anisotropy formed using the conductive fine particle The present invention relates to a conductive material.

The conductive fine particles are generally mixed in a binder resin or the like, such as anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, anisotropic conductive sheet, etc. Widely used as an anisotropic conductive material. These anisotropic conductive materials are used to electrically connect wiring circuit boards to each other, for example, in electronic devices such as liquid crystal displays, personal computers, and mobile phones, and to electrically connect small components such as semiconductor elements to the wiring circuit board. For example, it is used by being sandwiched between a printed circuit board and electrode terminals.

Conventionally, as conductive fine particles suitable for anisotropic conductive materials, resin fine particles having a uniform particle diameter and non-conductive fine particles such as glass beads have been used as substrate fine particles, and a metal such as nickel is used on the surface of the substrate fine particles. Conductive fine particles on which the plating was formed have been reported. However, the nickel-plated conductive fine particles have a problem that the plating layer corrodes with time and the electric resistance increases.

In order to solve this problem, conductive fine particles in which a gold layer or a silver layer is further formed on the surface of the nickel-plated conductive fine particles have been reported. For example, Patent Document 1 discloses conductive fine particles in which a nickel layer is formed by electroless plating on the surface of substantially spherical resin fine particles, and then a gold layer is formed using gold cyanide. Yes. Further, for example, in Patent Document 2, a nickel layer formed by electroless plating and a copper layer covering the nickel layer are formed on the surface of the substrate fine particles, and further, by a substitution reaction between copper and silver by electroless silver plating. Conductive fine particles having a silver layer formed thereon are disclosed.

However, the conductive fine particles having a gold layer formed on the surface of the nickel layer are excellent in connection stability but have a problem of high electrical resistance.
On the other hand, the conductive fine particles in which the silver layer is formed on the surface of the nickel layer have a lower electrical resistance than the conductive fine particles in which the gold layer is formed on the surface of the nickel layer, and are preferably used for thermocompression bonding of a substrate or the like. However, there was a problem that migration occurred while using a current, causing disconnection.

Therefore, as conductive fine particles aiming at stable conduction and reduction in electric resistance, for example, Patent Document 3 discloses conductive fine particles in which a silver layer is formed on the surface of a base fine particle and a gold layer is further formed. Is disclosed. However, since the adhesion between the fine particles of the base material and the silver layer is poor, the layer may be peeled off at the time of manufacturing and thermocompression bonding of the substrate or the like.
JP-A-8-31655 Japanese Patent Laid-Open No. 11-61424 JP 2002-270038 A

In view of the above-described situation, the present invention suppresses peeling of a conductive layer during production and thermocompression bonding and migration during use, and uses conductive fine particles having high corrosion resistance and low electrical resistance, and the conductive fine particles. It is an object of the present invention to provide an anisotropic conductive material.

The present invention is a conductive fine particle comprising substrate fine particles having a conductive layer in which a nickel layer, a silver layer, and a noble metal layer nobler than silver are sequentially formed on the surface.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have sequentially formed a nickel layer, a silver layer, and a noble metal layer noble from silver (hereinafter, these three layers are also referred to as a conductive layer) on the surface of the base particle. It is possible to combine high adhesion, low resistance, and high corrosion resistance between the fine particles of the substrate and the conductive layer, which was impossible before, and suppresses peeling of the conductive layer during manufacturing and thermocompression bonding and migration during use. At the same time, the inventors have found that the conductive fine particles have low connection resistance and have completed the present invention.

The conductive fine particles of the present invention comprise substrate fine particles and a conductive layer formed on the surface of the substrate fine particles.

The substrate fine particles are not particularly limited, and may be an inorganic material or an organic material as long as it has an appropriate elastic modulus, elastic deformability, and restoration property. Since it is easy to control the deformability and the recoverability, resin fine particles made of a resin are preferable.

The resin fine particles are not particularly limited. For example, polyolefins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate Divinylbenzene polymer resin; divinylbenzene-styrene copolymer, divinylbenzene-acrylic acid ester copolymer, divinylbenzene-methacrylic acid ester copolymer and other divinylbenzene copolymer resins; polyalkylene terephthalate, polysulfone, polycarbonate, Polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, etc. Thing, and the like. These resin fine particles may be used independently and 2 or more types may be used together.

Although it does not specifically limit as an average particle diameter of the said base material fine particle, A preferable minimum is 1 micrometer and a preferable upper limit is 20 micrometers. If it is less than 1 μm, for example, it is likely to aggregate when electroless plating is performed, and it may be difficult to form single particles. If it exceeds 20 μm, it exceeds the range used between the substrate electrodes as an anisotropic conductive material. May end up. A more preferable upper limit is 10 μm.

The conductive layer has a nickel layer in contact with the surface of the substrate fine particles.
In the present invention, the nickel layer is formed for the purpose of enhancing the adhesion between the substrate fine particles and the conductive layer, and suppressing the peeling of the conductive layer during production and thermocompression bonding of a substrate or the like.

Although it does not specifically limit as thickness of the said nickel layer, A preferable minimum is 5 nm and a preferable upper limit is 2000 nm. If the thickness is less than 5 nm, desired adhesion may not be obtained. If the thickness exceeds 2000 nm, the nickel layer may be easily peeled off due to the difference in thermal expansion coefficient between the substrate fine particles and the nickel layer. A more preferred lower limit is 10 nm, a more preferred upper limit is 500 nm, a still more preferred lower limit is 50 nm, and a still more preferred upper limit is 100 nm.
The thickness of the nickel layer is a thickness obtained by measuring 10 randomly selected particles and arithmetically averaging them.

The conductive layer has a silver layer in contact with the surface of the nickel layer.
In the present invention, the silver layer is formed for the purpose of reducing the resistance value of the conductive layer. In addition, compared to conventional conductive fine particles in which a gold layer is provided on the surface of a nickel layer, the conductivity can be maintained even if the thickness of the gold layer is reduced, so that the cost is also excellent.
The silver layer may be a silver alloy layer composed of silver and at least one metal selected from the group consisting of copper, palladium, tin, cobalt, iron, nickel, and bismuth.

Although it does not specifically limit as thickness of the said silver layer, A preferable minimum is 5 nm and a preferable upper limit is 1000 nm. When the thickness is less than 5 nm, desired conductivity may not be obtained. When the thickness exceeds 1000 nm, migration tends to occur during use, and the cost increases.
The thickness of the silver layer is a thickness obtained by measuring 10 randomly selected particles and arithmetically averaging them.

The conductive layer has a noble metal layer nobler than silver in contact with the surface of the silver layer. Specific examples of noble metals that are nobler than silver include gold, palladium, and platinum.
In the present invention, the noble metal layer nobler than silver is formed for the purpose of suppressing the occurrence of migration with use and improving the corrosion resistance after thermocompression bonding of a substrate or the like.
The noble metal layer nobler than silver may be an alloy layer made of noble metal nobler than silver and at least one metal selected from the group consisting of copper, cobalt, rhodium, nickel, tin and silver. Good. However, when a high oxidation resistance is required, the purity of the noble metal nobler than silver is preferably 99% or more.

The thickness of the noble metal layer nobler than the silver is not particularly limited, but the preferred lower limit is 5 nm and the preferred upper limit is 50 nm. If the thickness is less than 5 nm, it may be difficult to prevent oxidation or migration of the conductive layer. If the thickness exceeds 50 nm, no further oxidation resistance can be expected, and the cost increases.
In addition, the thickness of the noble metal layer nobler than the silver is a thickness obtained by measuring 10 randomly selected particles and arithmetically averaging them.

The thickness of the conductive layer covering the surface of the substrate fine particles is not particularly limited, but a preferred lower limit is 15 nm and a preferred upper limit is 3050 nm. When the thickness is less than 15 nm, desired conductivity may not be obtained. When the thickness exceeds 3050 nm, the adhesion between the base particle and the conductive layer may be deteriorated, and the cost is increased.

The method for producing conductive fine particles of the present invention is not particularly limited. For example, a step of forming a nickel layer by electroless nickel plating on the surface of the substrate fine particles, and a silver layer by electroless silver plating on the surface of the nickel layer And a step of forming a noble metal layer nobler than silver by a conventionally known method on the surface of the silver layer.
Details of each step will be described below.

The method for forming the nickel layer is not particularly limited. For example, the catalyst-provided substrate fine particles are immersed in a solution containing nickel ions in the presence of a reducing agent, and the catalyst is used as a starting point for the substrate fine particles. Examples include a method of depositing nickel on the surface.
Here, as the method for applying the catalyst, for example, the substrate fine particles etched with an alkali solution are subjected to acid neutralization and sensitizing in a tin dichloride (SnCl ₂ ) solution to obtain palladium dichloride (PdCl ₂ ) A method of performing an electroless plating pretreatment step for activating in solution.
Sensitizing is a process in which Sn ²⁺ ions are adsorbed on the surface of an insulating material, and activating is a reaction represented by Sn ²⁺ + Pd ²⁺ → Sn ⁴⁺ + Pd ⁰ on the surface of an insulating material. In this process, palladium is used as a catalyst core for electroless plating.

The method for forming the silver layer by electroless silver plating is not particularly limited as long as the silver layer is formed on the surface of the nickel layer, but the adhesion between the nickel layer and the silver layer is not particularly limited. Since it becomes excellent, for example, a base catalyst type reduction electroless silver plating method is preferably used. Further, in addition to the method based on the base catalyst type reduced electroless silver plating, for example, the method based on the autocatalytic type reduced electroless silver plating and the method based on the substitutional type electroless silver plating may be used in combination. .

The base catalyst type reduction electroless silver plating is a method of depositing a silver layer using nickel of the nickel layer as a catalyst.
In the method using the base catalyst type reduced electroless silver plating, a reducing agent that causes an oxidation reaction on the surface of the nickel layer and does not cause an oxidation reaction on the surface of the deposited metal silver is present on the surface of the nickel layer. A silver plating film can be formed by reducing the silver salt in the plating solution and precipitating silver.

The electroless silver plating solution used for the electroless silver plating is not particularly limited, and in the same way as a general electroless silver plating solution, a water-soluble silver salt as a silver ion source, and for stably dissolving silver ions. The thing containing a complexing agent is mentioned.

The water-soluble silver salt is not particularly limited as long as it is water-soluble, and examples thereof include non-cyanide silver salts such as silver nitrate and silver sulfate; cyan-based silver salts such as silver cyanide. Of these, a norcian silver salt is preferable from the viewpoint of environmental problems.
By using the above cyanogen silver salt, it is possible to perform nocyanide electroless silver plating, and since it is not used as a strong alkali like a cyan bath, there is no erosion to substrate fine particles, etc. It becomes. Among the above-mentioned nocyan silver salts, silver nitrate is preferable in consideration of solubility in water.

The method for forming the noble metal layer nobler than silver is not particularly limited, and examples thereof include conventionally known methods such as electroless plating, displacement plating, electroplating, reduction plating, and sputtering.

The conductive fine particles of the present invention have the above-described configuration, thereby suppressing plating peeling at the time of production and thermocompression bonding and migration at the time of use and having a low resistance value.

Further, an anisotropic conductive material can be produced by dispersing the conductive fine particles of the present invention in a binder resin. Such an anisotropic conductive material is also one aspect of the present invention.

Specific examples of the anisotropic conductive material of the present invention include, for example, anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive layer, anisotropic conductive film, anisotropic conductive sheet and the like. Is mentioned.

The resin binder is not particularly limited, and an insulating resin is used. For example, vinyl resins such as vinyl acetate resins, vinyl chloride resins, acrylic resins, styrene resins; polyolefin resins, ethylene-acetic acid Thermoplastic resins such as vinyl copolymers and polyamide resins; Epoxy resins, urethane resins, polyimide resins, unsaturated polyester resins, and curable resins composed of these curing agents; styrene-butadiene-styrene block copolymer Polymers, thermoplastic block copolymers such as styrene-isoprene-styrene block copolymers and hydrogenated products thereof; elastomers such as styrene-butadiene copolymer rubber, chloroprene rubber, acrylonitrile-styrene block copolymer rubber (rubbers) ) And the like. These resins may be used alone or in combination of two or more.
Further, the curable resin may be any curable type of room temperature curable type, heat curable type, photo curable type, and moisture curable type.

In addition to the conductive fine particles of the present invention and the resin binder described above, the anisotropic conductive material of the present invention includes, for example, a bulking agent and a softening agent (if necessary) within a range not impairing the achievement of the problems of the present invention. Additives such as plasticizers), adhesive improvers, antioxidants (anti-aging agents), heat stabilizers, light stabilizers, UV absorbers, colorants, flame retardants, organic solvents, etc. Good.

The method for producing the anisotropic conductive material of the present invention is not particularly limited. For example, the conductive fine particles of the present invention are added to an insulating resin binder, and are mixed and dispersed uniformly. A method of using a conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, etc., adding the conductive fine particles of the present invention in an insulating resin binder and uniformly dissolving (dispersing), or , Heat-dissolve, apply to the release treatment surface of the release material such as release paper or release film so that it has a predetermined film thickness, and dry and cool as necessary, for example, anisotropic For example, an appropriate manufacturing method may be employed in accordance with the type of anisotropic conductive material to be manufactured.
Moreover, it is good also as an anisotropic conductive material by using separately, without mixing an insulating resin binder and the electroconductive fine particles of this invention.

According to the present invention, it is possible to suppress peeling of the conductive layer during manufacturing and thermocompression bonding and migration during use, and to provide conductive fine particles with high corrosion resistance and low resistance, and different types of conductive fine particles. An isotropic conductive material can be provided.

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
(Electroless nickel plating)
Divinylbenzene resin particles having a particle size of 4 μm were treated with a 10% solution of an ion adsorbent for 5 minutes, then treated with a 0.01% palladium sulfate aqueous solution for 5 minutes, and further subjected to a reduction treatment by adding dimethylamine borane. By filtering and washing, substrate fine particles carrying palladium were obtained.
Next, a solution containing 1% sodium succinate and 500 mL of ion-exchanged water was prepared, mixed with 10 g of substrate fine particles to prepare a slurry, and sulfuric acid was further added to adjust the pH of the slurry to 5. On the other hand, a nickel solution containing nickel sulfate 10%, sodium hypophosphite 10%, sodium hydroxide 4% and sodium succinate 20% was prepared as a nickel plating solution. The slurry was brought to 80 ° C., and the prepared nickel solution was continuously added dropwise thereto and stirred for 20 minutes to cause a plating reaction. During the plating reaction, it was confirmed that there was no significant aggregation and generation of hydrogen disappeared, and the plating reaction was terminated.
Next, a late nickel solution containing 20% nickel sulfate, 5% dimethylamine borane, and 5% sodium hydroxide was prepared, and a late nickel solution was prepared. Thereafter, the late nickel solution prepared in the solution after completion of the early nickel solution reaction was continuously dropped and stirred for 1 hour to cause a plating reaction.

(Electroless silver plating)
Next, 15 g of benzimidazole was added as a reducing agent to a solution obtained by dissolving 4.25 g of silver nitrate as a silver salt in 1180 mL of pure water at room temperature, and after confirming that the initially formed precipitate was completely dissolved, As an agent, 6 g of ammonia and 6 g of citric acid monohydrate were dissolved, and then 10 g of glyoxylic acid was added as a crystal modifier and completely dissolved to prepare an electroless silver plating solution.
Next, 10 g of the particles on which the obtained nickel plating film was formed were put into an electroless silver plating solution, and this solution was heated with stirring to keep the temperature at 50 ° C. Thereafter, the particles were separated by filtration with a Buchner funnel to obtain particles on which a silver plating film was formed.

(Electroless gold plating)
Next, a solution containing 10 g of sodium chloroaurate and 1000 mL of ion-exchanged water was prepared, and 15 g of particles obtained by sequentially forming the nickel plating film and the silver plating film were mixed to prepare an aqueous suspension. A plating solution was prepared by adding 15 g of ammonium thiosulfate, 80 g of ammonium sulfite, and 40 g of ammonium hydrogen phosphate to the obtained aqueous suspension. 4 g of hydroxylamine is added to the obtained plating solution, and then the pH is adjusted to 9 using ammonia, the bath temperature is set to 60 ° C., and the reaction is performed for about 15 to 20 minutes. Got.

(Example 2)
In the same manner as in Example 1, particles in which a nickel plating film and a silver plating film were sequentially formed were produced.

(Electroless palladium plating)
Next, a nickel plating obtained by preparing a solution containing 9 g of tetrachloropalladium, 10.1 g of ethylenediamine, 5.3 g of aminopyridine, 17.8 g of sodium hypophosphite, 20 g of polyethylene glycol, and 1000 mL of ion-exchanged water was obtained. A plating solution was prepared by mixing 15 g of particles on which a coating and a silver plating coating were sequentially formed. Ammonia was added to the obtained plating solution, the pH was adjusted to 7.5, the bath temperature was 65 ° C., and the reaction was carried out for about 15 to 20 minutes to obtain conductive fine particles having a palladium plating film formed on the outermost layer. .

(Comparative Example 1)
(Conductive fine particles having a conductive layer made of Ni / Au)
An aqueous suspension was prepared by preparing a solution containing 10 g of sodium chloroaurate and 1000 mL of ion-exchanged water, and mixing 12 g of particles having the same nickel plating film as in Example 1. To the obtained aqueous suspension, 30 g of ammonium thiosulfate, 80 g of ammonium sulfite, and 40 g of ammonium hydrogen phosphate were added to prepare a plating solution. After adding 10 g of hydroxylamine to the resulting plating solution, the pH is adjusted to 10 using ammonia, the bath temperature is set to 60 ° C., and the reaction is performed for 15 to 20 minutes, whereby a gold plating film is formed on the outermost layer. Fine particles were obtained.

(Comparative Example 2)
(Conductive fine particles having a conductive layer made of Ni / Ag)
In the same manner as in Example 1, electroless nickel plating was performed to obtain particles on which a nickel plating film was formed.
Next, 15 g of benzimidazole was added as a reducing agent to a solution obtained by dissolving 4.25 g of silver nitrate as a silver salt in 1180 mL of pure water at room temperature, and after confirming that the initially formed precipitate was completely dissolved, As an agent, 6 g of ammonia and 6 g of citric acid monohydrate were dissolved, and then 10 g of glyoxylic acid was added as a crystal modifier and completely dissolved to prepare an electroless silver plating solution. Next, the obtained particles on which the nickel plating film was formed were put into an electroless silver plating solution, and this solution was heated with stirring to keep the temperature at 50 ° C. Thereafter, the particles were separated by filtration with a Buchner funnel, and about 1000 mL of pure water was sprinkled and washed on the separated particles. Then, alcohol substitution was performed, and it dried at 80 degreeC with the vacuum dryer for 2 hours, and obtained the electroconductive fine particles in which the silver plating film was formed in the outermost layer.

(Comparative Example 3)
(Conductive fine particles having a conductive layer made of Ag / Au)
Divinylbenzene resin particles having a particle size of 4 μm were treated with a 10% solution of an ion adsorbent for 5 minutes, then treated with a 0.01% palladium sulfate aqueous solution for 5 minutes, and further subjected to a reduction treatment by adding dimethylamine borane. By filtering and washing, substrate fine particles carrying palladium were obtained. Next, a solution containing 1% sodium succinate and 500 mL of ion-exchanged water was prepared, 10 g of base material fine particles were mixed to prepare a slurry, and sulfuric acid was further added to adjust the pH of the slurry to 6.5.
Next, 30 g of benzimidazole was added as a reducing agent to a solution obtained by dissolving 8.5 g of silver nitrate as a silver salt in 2360 mL of pure water at room temperature, and after confirming that the initially formed precipitate was completely dissolved, As an agent, 12 g of ammonia and 12 g of citric acid monohydrate were dissolved, and then 20 g of glyoxylic acid was added as a crystal adjusting agent and completely dissolved to prepare an electroless silver plating solution. This solution was continuously dropped into the slurry containing the substrate fine particles and stirred for 1 hour to cause a plating reaction.
Next, a solution containing 10 g of sodium chloroaurate and 1000 mL of ion-exchanged water was prepared, and 15 g of the particles on which the obtained silver plating film was formed were mixed to prepare an aqueous suspension. A plating solution was prepared by adding 15 g of ammonium thiosulfate, 80 g of ammonium sulfite, and 40 g of ammonium hydrogen phosphate to the obtained aqueous suspension. After putting 4 g of hydroxylamine into the obtained plating solution, adjusting the pH to 9 using ammonia, setting the bath temperature to 60 ° C., and reacting for about 15 to 20 minutes, the gold plating film was formed on the outermost layer. Fine particles were obtained.

<Evaluation>
The following evaluation was performed about the electroconductive fine particles obtained in Examples 1-2 and Comparative Examples 1-3. The results are shown in Table 1.

(1) Adhesive evaluation of conductive fine particles About each of the conductive fine particles obtained in Examples 1-2 and Comparative Examples 1-3, in a 100 mL beaker, 1 g of conductive fine particles, 40 g of zirconia balls having a diameter of 1 mm, and Then, 20 mL of ethanol was added, and the mixture was stirred for 2 minutes at 400 rpm with four stainless steel stirring blades, filtered and dried, and the conductive fine particles were crushed.
About the electroconductive fine particles which crushed, 5 sheets are image | photographed with the scanning electron microscope (SEM) photograph (1000 times), the number of the cracking particles in 1000 observation is counted, and base material microparticles | fine-particles and plating film The adhesion was evaluated. In addition, the number of cracked particles was counted as those having cracks or peeling of 1/2 or more of the diameter of the conductive fine particles.

(2) Resistance evaluation L / S 100 μm / 100 μm copper pattern crossing of two substrates is connected with a mixed paste of conductive fine particles and resin, and after heat curing, resistance is measured by a four-terminal method and evaluated. did.

(3) Corrosion resistance evaluation The crossing part of two board | substrates with the copper pattern of L / S100micrometer / 100micrometer which gave Ni / Au electroless plating on the surface was connected with the mixed paste of electroconductive fine particles and resin, and it heat-hardened, The sample was left in an environment of 85 ° C. and 85% RH for 1000 hours. The resistance before and after being left was measured by the four probe method to evaluate the corrosion resistance.

(4) Migration Evaluation A mixed paste of conductive fine particles and resin is applied to the surface of a comb-shaped copper pattern with a minimum L / S of 20 μm / 20 μm with Ni / Au electroless plating on the surface as shown in FIG. In order to make sure that the fine particles contact the electrode, an alkali-free glass plate was pressure-bonded from above the paste, cured by heating, and allowed to stand in an environment of 85 ° C. and 85% RH for 1000 hours while applying a bias of 5 V between the electrodes. The migration resistance was evaluated by measuring the insulation resistance between the electrodes before and after being left and observing changes in the appearance of the electrode surface (whether or not dent light was generated on the negative electrode surface).

According to the present invention, it is possible to suppress peeling of the conductive layer during manufacturing and thermocompression bonding and migration during use, and to provide conductive fine particles with high corrosion resistance and low resistance, and different types of conductive fine particles. An isotropic conductive material can be provided.

It is a schematic diagram which shows an example of the comb-shaped copper pattern of minimum L / S20micrometer / 20micrometer which gave Ni / Au electroless plating on the surface.

Claims (3)

Conductive fine particles comprising substrate fine particles having a conductive layer in which a nickel layer, a silver layer, and a noble metal layer nobler than silver are sequentially formed on the surface. The conductive fine particles according to claim 1, wherein the noble metal nobler than silver is gold, palladium, or platinum. An anisotropic conductive material, wherein the conductive fine particles according to claim 1 or 2 are dispersed in a resin binder.

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