JP2011076940A - Conductive particulate, anisotropic conductive material, and connection structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive particulate in which a high connection reliability can be attained and a connection process of the electrodes can be simplified, and to provide an anisotropic conductive material and a connection structure that are composed by using the conductive particulates. <P>SOLUTION: The conductive particulate has a low melting-point metal layer formed on the surface of a base material particulate, and the low melting-point metal layer is formed by contacting a low melting-point metal particulate having a layer of flux on the surface to the base material particulate and by melting/softening by shear-compression. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention provides conductive fine particles that can realize high connection reliability and can simplify the electrode connection process, an anisotropic conductive material using the conductive fine particles, and connection Concerning the structure.

Conventionally, in an electronic circuit board, ICs and LSIs are connected by soldering electrodes to a printed circuit board. However, soldering cannot efficiently connect the printed circuit board to the IC or LSI. In addition, it is difficult to improve the mounting density of ICs and LSIs by soldering.
In order to solve this problem, a BGA (ball grid array) has been developed in which the solder is made into a spherical shape, so-called “solder balls” that connect the IC or LSI to the substrate. According to this technology, an electronic circuit that achieves both high productivity and high connection reliability can be manufactured by melting a solder ball mounted on a chip or a substrate at a high temperature and connecting the substrate and the chip.

However, in recent years, since the number of substrates has been increased and multilayer substrates are easily affected by the use environment, there has been a problem that distortion and expansion / contraction occur in the substrates and disconnection occurs in the connection portion between the substrates.

For such a problem, Patent Document 1 discloses that a metal layer containing a highly conductive metal is formed on the surface of resin fine particles, and further, a low melting point metal made of a metal such as tin on the surface of the metal layer. A conductive fine particle having a layer formed therein is disclosed. If such conductive fine particles are used, the stress applied to the conductive fine particles by the flexible resin fine particles can be relaxed, and the low melting point metal layer is formed on the outermost surface, so that the electrodes can be easily conductive. Can be connected.

On the other hand, when conductive fine particles are placed and connected to an electrode, a flux is usually applied to the electrode surface in order to improve the wettability of the solder by removing oil stains and oxide film on the electrode surface. To be done.
However, the flux applied to the electrode becomes unnecessary after the electrode is connected, and the extra flux may cause various harmful effects, so it was necessary to remove the flux by washing. . Therefore, there is a problem that a process for cleaning the flux is required separately and an organic solvent must be used for the cleaning process.
In addition, when the surface of the conductive fine particles is oxidized due to changes over time, hydrogen is generated due to the reaction between the oxide film and the flux when mounting using the conductive fine particles, When this is taken into the molten low melting point metal, it becomes a void, which causes a decrease in bonding strength.

On the other hand, Patent Document 2 describes conductive fine particles with flux in which microcapsules enclosing flux are fixed to a metal layer formed on the outer surface of the base fine particles. However, in order to produce such conductive fine particles, it is necessary to separately perform a process for producing a microcapsule enclosing a flux and a process for attaching a microcapsule, resulting in a complicated manufacturing process. Moreover, the bad effect by the outer shell of the microcapsule which encloses a flux also arises. Further, when sucking with a ball mounter in the mounting process, there is a problem that the conductive fine particles cannot be sucked.

Furthermore, methods using microcapsules with a flux applied to the surface are also being studied, but the amount of flux that can be applied is limited, and applying a sufficient amount of flux to improve the wettability of solder is not possible. could not.

JP 2001-220691 A Japanese Patent Laid-Open No. 2003-247083

The present invention provides conductive fine particles that can realize high connection reliability and can simplify the electrode connection process, an anisotropic conductive material using the conductive fine particles, and connection An object is to provide a structure.

The present invention relates to conductive fine particles in which a low melting point metal layer is formed on the surface of a substrate fine particle, and the low melting point metal layer includes a low melting point metal particle having a layer made of a flux on the surface. It is the electroconductive fine particles which are formed by making it contact and melt-softening by shear compression.
The present invention is described in detail below.

The conductive fine particles of the present invention are conductive fine particles in which a low melting point metal layer is formed, and the low melting point metal layer is formed by bringing low melting point metal fine particles having a layer made of a flux on the surface into contact with substrate fine particles. It is formed by melting by shear compression.

FIG. 1 is a cross-sectional view showing an example of conductive fine particles of the present invention. As shown in FIG. 1, the conductive fine particles of the present invention are composed of base material fine particles 1, a low melting point metal layer 2 and a flux 3, and the deformed low melting point metal fine particles 2 'are deposited, so that the flux At the same time as 3 covers the surface of the low melting point metal layer 2, the flux 3 is included in the low melting point metal layer 2.
FIG. 2 is a cross-sectional view showing a state where the conductive fine particles of the present invention are connected to an electrode. As shown in FIG. 2, when the low melting point metal layer 2 is melted by heat, the flux 3 ′ is eluted on the electrode 4. In this case, the amount of flux 3 ′ is the minimum necessary, and the configuration exists only on the vicinity of the electrode 4.

As shown in FIG. 1 described above, the conductive fine particles of the present invention have a structure in which the low melting point metal fine particles are deposited so that the flux covers the surface of the low melting point metal layer. Can be prevented from being oxidized. Thereby, it can suppress effectively that an oxide film is formed on the surface of electroconductive fine particles.
Further, when conducting the conductive connection by melting the low melting point metal layer, the contained flux is eluted to the outside. As a result, the flux application step that has been conventionally performed is not necessary, and furthermore, since only the minimum necessary flux is eluted, the excess flux cleaning step is also unnecessary. As a result, the electrode connection process can be greatly simplified. Further, the generation of extra flux does not cause deterioration of the working environment.

The substrate fine particles are not particularly limited, and examples thereof include resin fine particles, inorganic fine particles, organic-inorganic hybrid fine particles, and metal fine particles. As the substrate fine particles, resin fine particles are particularly preferable.

The resin fine particles are not particularly limited, and include, for example, polyolefin resin, acrylic resin, polyalkylene terephthalate resin, polysulfone resin, polycarbonate resin, polyamide resin, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, and the like. Resin fine particles.
The polyolefin resin is not particularly limited, and examples thereof include polyethylene resin, polypropylene resin, polystyrene resin, polyisobutylene resin, and polybutadiene resin. The acrylic resin is not particularly limited, and examples thereof include polymethyl methacrylate resin and polymethyl acrylate resin. These resins may be used alone or in combination of two or more.

The method for producing the resin fine particles is not particularly limited, and examples thereof include a polymerization method, a method using a polymer protective agent, and a method using a surfactant.
The polymerization method is not particularly limited, and examples thereof include emulsion polymerization, suspension polymerization, seed polymerization, dispersion polymerization, and dispersion seed polymerization.

The inorganic fine particles are not particularly limited, and examples thereof include fine particles composed of metal oxides such as silica and alumina. The organic-inorganic hybrid fine particles are not particularly limited, and examples thereof include hybrid fine particles containing an acrylic polymer in an organosiloxane skeleton.
The metal fine particles are not particularly limited, and examples thereof include fine particles made of metals such as aluminum, copper, nickel, iron, gold, and silver. Of these, copper fine particles are preferred. The copper fine particles may be copper fine particles formed substantially only of copper metal, or may be copper fine particles containing copper metal. When the substrate fine particles are copper fine particles, a conductive layer described later need not be formed.

When the substrate fine particles are resin fine particles, the preferred lower limit of the 10% K value of the fine resin particles is 1000 MPa, and the preferred upper limit is 15000 MPa. If the 10% K value is less than 1000 MPa, the resin fine particles may be destroyed when the resin fine particles are compressed and deformed. When the 10% K value exceeds 15000 MPa, the conductive fine particles may damage the electrode. The more preferable lower limit of the 10% K value is 2000 MPa, and the more preferable upper limit is 10,000 MPa.

The 10% K value is obtained by using a micro compression tester (for example, “PCT-200” manufactured by Shimadzu Corporation), and using a smooth indenter end face of a diamond cylinder having a diameter of 50 μm and a compression speed of 2.6 mN / The compression displacement (mm) when compressed under conditions of seconds and a maximum test load of 10 g can be measured and determined by the following equation.
K value ^{(N / mm 2) = (} 3 / √2) · F · S -3/2 · R -1/2
F: Load value at 10% compression deformation of resin fine particles (N)
S: Compression displacement (mm) in 10% compression deformation of resin fine particles
R: radius of resin fine particles (mm)

The average particle diameter of the substrate fine particles is not particularly limited, but a preferable lower limit is 1 μm and a preferable upper limit is 2000 μm. When the average particle diameter of the above-mentioned substrate fine particles is less than 1 μm, the substrate fine particles are likely to aggregate. When conductive fine particles in which a low melting point metal layer is formed on the surface of the aggregated substrate fine particles are used, a gap between adjacent electrodes can be obtained. May cause a short circuit. When the average particle diameter of the base material fine particles exceeds 2000 μm, the range suitable for connection between electrodes such as a circuit board may be exceeded. The more preferable lower limit of the average particle diameter of the substrate fine particles is 3 μm, and the more preferable upper limit is 1000 μm.
The average particle size of the above-mentioned substrate fine particles is obtained by measuring the particle size of 50 randomly selected substrate fine particles using an optical microscope or an electron microscope and arithmetically averaging the measured particle sizes. Can do.

The coefficient of variation of the average particle diameter of the substrate fine particles is not particularly limited, but is preferably 10% or less. If the coefficient of variation exceeds 10%, the connection reliability of the conductive fine particles may be lowered. The coefficient of variation is a numerical value obtained by dividing the standard deviation obtained from the particle size distribution by the average particle size and expressed as a percentage (%).

The shape of the substrate fine particles is not particularly limited as long as the distance between the opposing electrodes can be maintained, but a true spherical shape is preferable. Further, the surface of the substrate fine particles may be smooth or may have a protrusion.

In the conductive fine particles of the present invention, the low-melting-point metal layer is formed by bringing low-melting-point metal fine particles having a layer made of a flux on the surface into contact with the substrate fine particles and melting and softening them by shear compression. Since the low melting point metal layer is melted and joined to the electrode by a reflow process, connection reliability can be improved.

The flux is not particularly limited. For example, an inactive rosin flux mainly composed of rosins such as rosin and rosin derivatives, an active rosin flux mainly composed of the rosins and an activator, carboxylic acid, dicarboxylic acid And the like.
The activator is not particularly limited, and examples thereof include organic acid or inorganic acid salts of amine compounds such as triethanolamine hydrochloride, triethylenetetramine hydrochloride, cyclohexylamine hydrochloride, and aniline hydrochloride.
The carboxylic acid is not particularly limited, and examples thereof include stearic acid, adipic acid, anthranilic acid, lauric acid, glycolic acid, azelaic acid, succinic acid, and sebacic acid.

In the low melting point metal fine particles having a layer made of a flux on the surface, the layer made of the flux may be a single molecule adsorption layer as long as the effect of preventing the formation of an oxide film on the surface of the low melting point metal and the removal of the oxide film upon melting can be obtained good.

The average particle diameter of the low melting point metal fine particles having a layer made of a flux on the surface is not particularly limited, but a preferable lower limit is 0.1 μm and a preferable upper limit is 100 μm. When the average particle diameter of the low melting point metal fine particles having a layer made of a flux on the surface is less than 0.1 μm, the low melting point metal fine particles are likely to aggregate, so that it is difficult to form a low melting point metal layer. There is. When the average particle size of the low melting point metal fine particles having a layer made of a flux on the surface exceeds 100 μm, it may not be melted during shear compression, and it may be difficult to form a low melting point metal layer. The average particle size of the low-melting-point metal fine particles having a layer made of a flux on the surface was measured by measuring the particle size of 50 low-melting-point metal fine particles randomly selected using an optical microscope or an electron microscope. It can be determined by arithmetically averaging the particle size.
Moreover, it is preferable that the average particle diameter of the low melting metal fine particle which has the layer which consists of a flux on the said surface is 1/10 or less of the average particle diameter of the said base particle. When the average particle size of the low melting point metal fine particles having a layer made of a flux on the surface exceeds 1/10 of the average particle size of the substrate fine particles, the low melting point metal having a layer made of a flux on the surface during shear compression In some cases, the fine particles cannot adhere to the substrate fine particles and become a film.

The low-melting-point metal layer constituting the conductive fine particles of the present invention is formed by bringing low-melting-point metal fine particles having a layer made of flux on the surface into contact with the substrate fine particles and melting and softening them by shear compression (dry coating method). The

Examples of the dry coating method include a method using a theta composer (manufactured by Tokuju Kogakusho Co., Ltd.). The theta composer includes a vessel having an elliptical cavity, and a rotor that is separately rotated on the same axis as the vessel in the cavity. A shear compressive force can be applied in the gap in the vicinity where the minor axis of the cavity and the major axis of the rotor coincide. By this shear compression, the low melting point metal fine particles having a layer made of a flux on the surface are melted and softened, and by repeatedly attaching the low melting point metal fine particles to the base material fine particles, Conductive fine particles on which a low melting point metal layer containing a flux is formed can be produced.

The low melting point metal fine particles having a layer made of flux on the surface are prepared by, for example, dissolving flux in a solvent such as ethanol to prepare a flux solution, immersing the substrate fine particles in the flux solution, filtering, and drying. Can be manufactured.

The low melting point metal layer is made of tin or an alloy of tin and another metal. The said alloy is not specifically limited, For example, a tin-copper alloy, a tin-silver alloy, a tin-bismuth alloy, a tin-zinc alloy, a tin-indium alloy etc. are mentioned. Among these, a tin-silver alloy is preferable because the melting point of the low melting point metal layer to be formed can be lowered.

Furthermore, in order to improve the bonding strength between the low-melting-point metal layer and the electrode, the low-melting-point metal layer includes nickel, antimony, aluminum, iron, gold, titanium, phosphorus, germanium, tellurium, gallium, cobalt, manganese, A metal such as chromium, molybdenum, palladium, or indium may be contained. Especially, since it is excellent in the effect of improving the bonding strength between the low melting point metal layer and the electrode, it is preferable that the low melting point metal fine particles contain nickel, antimony, and aluminum.
The content of the metal in the total of metals contained in the low melting point metal layer is not particularly limited, but a preferred lower limit is 0.0001% by weight and a preferred upper limit is 2% by weight. When the content of the metal is less than 0.0001% by weight, the bonding strength between the low melting point metal layer and the electrode may not be sufficiently obtained. If the metal content exceeds 2% by weight, the melting point of the conductive fine particles may change.

Although the thickness of the said low melting metal layer is not specifically limited, A preferable minimum is 0.1 micrometer and a preferable upper limit is 200 micrometers. When the thickness of the low-melting-point metal layer is less than 0.1 μm, it may not be able to be sufficiently bonded to the electrode even when reflowed and melted. When the thickness of the low-melting-point metal layer exceeds 200 μm, Aggregation tends to occur when the melting point metal layer is formed, and the aggregated conductive fine particles may cause a short circuit between adjacent electrodes. The minimum with more preferable thickness of the said low melting metal layer is 0.2 micrometer, and a more preferable upper limit is 50 micrometers.
The thickness of the low melting point metal layer is a thickness obtained by observing and measuring a cross section of 10 randomly selected conductive fine particles with a scanning electron microscope (SEM) and arithmetically averaging the measured values. .

The low melting point metal layer may be formed directly on the surface of the substrate fine particles. In the low melting point metal layer, a conductive layer (underlying metal layer) may be further formed between the low melting point metal layer and the base particle.
The metal forming the conductive layer is not particularly limited, and examples thereof include gold, silver, copper, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, antimony, bismuth, germanium, cadmium and the like. . Especially, since it is excellent in electroconductivity, it is preferable that the metal which forms the said conductive layer is gold, copper, or nickel.

The method for forming the conductive layer on the surface of the substrate fine particles is not particularly limited, and examples thereof include an electroless plating method, an electrolytic plating method, a vacuum deposition method, an ion plating method, and an ion sputtering method.

Although the thickness of the said conductive layer is not specifically limited, A preferable minimum is 0.1 micrometer and a preferable upper limit is 100 micrometers. If the thickness of the conductive layer is less than 0.1 μm, sufficient conductivity may not be obtained. When the thickness of the conductive layer exceeds 100 μm, the flexibility of the conductive fine particles may be lowered. A more preferable lower limit of the thickness of the conductive layer is 0.2 μm, and a more preferable upper limit is 50 μm.
The thickness of the conductive layer is a thickness obtained by observing and measuring a section of 10 randomly selected conductive fine particles with a scanning electron microscope (SEM) and arithmetically averaging them.

The conductive fine particles of the present invention are obtained by, for example, bringing the low-melting-point metal fine particles having a layer made of a flux on the surface into contact with the base-particle fine particles, and melting and softening the low-melting-point metal fine particles by shear compression. And a method having a step of forming a low melting point metal layer.
The low melting point metal layer obtained by such a manufacturing method has a structure in which the flux covers the surface of the low melting point metal layer by depositing the low melting point metal particles, and the low melting point metal layer is oxidized by long-term storage. Can be prevented. Thereby, it can suppress effectively that an oxide film is formed on the surface of electroconductive fine particles.
At the same time, since the flux is included in the low melting point metal layer, when conducting the conductive connection by melting the low melting point metal layer, the contained flux is eluted to the outside, and the flux conventionally used A coating process becomes unnecessary. Moreover, since only the minimum necessary flux is eluted, the cleaning process of the surplus flux becomes unnecessary, and the electrode connecting process can be greatly simplified. Furthermore, it is possible to prevent the working environment from deteriorating due to the extra flux.

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.

Examples of the anisotropic conductive material of the present invention include anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, anisotropic conductive film, and anisotropic conductive sheet.

The binder resin is not particularly limited, but an insulating resin is used, and examples thereof include a vinyl resin, a thermoplastic resin, a curable resin, a thermoplastic block copolymer, and an elastomer.
Although the said vinyl resin is not specifically limited, For example, a vinyl acetate resin, an acrylic resin, a styrene resin etc. are mentioned.
Although the said thermoplastic resin is not specifically limited, For example, polyolefin resin, ethylene-vinyl acetate copolymer, a polyamide resin etc. are mentioned.
Although the said curable resin is not specifically limited, For example, an epoxy resin, a urethane resin, a polyimide resin, an unsaturated polyester resin etc. are mentioned. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent.
The thermoplastic block copolymer is not particularly limited. For example, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, styrene -Hydrogenated product of isoprene-styrene block copolymer.
The elastomer is not particularly limited, and examples thereof include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.
These resins may be used alone or in combination of two or more.

In addition to the conductive fine particles of the present invention and the above-mentioned binder resin, the anisotropic conductive material of the present invention is, for example, an extender, a plasticizer, and improved adhesiveness within a range that does not hinder the achievement of the present invention. Agents, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, flame retardants, organic solvents, and the like.

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 the binder resin, and the mixture is uniformly mixed and dispersed. Examples thereof include a method for producing an anisotropic conductive ink, an anisotropic conductive adhesive, and the like. Further, the conductive fine particles of the present invention are added to the binder resin and uniformly dispersed or dissolved by heating, and a predetermined film thickness is applied to a release treatment surface of a release material such as release paper or release film. For example, a method for producing an anisotropic conductive film, an anisotropic conductive sheet or the like by coating may be used.
Moreover, it is good also as an anisotropic conductive material by using separately the said binder resin and the electroconductive fine particles of this invention, without mixing.

A connection structure using the conductive fine particles of the present invention or the anisotropic conductive material of the present invention is also one aspect of the present invention.

The connection structure of the present invention is a conductive connection structure in which a pair of circuit boards are connected by filling the pair of circuit boards with the conductive fine particles of the present invention or the anisotropic conductive material of the present invention. is there.

According to the present invention, conductive fine particles that can realize high connection reliability and can simplify the electrode connection step, an anisotropic conductive material using the conductive fine particles, and A connection structure can be provided.

It is sectional drawing which shows an example of the electroconductive fine particles of this invention. It is sectional drawing which shows the state at the time of connecting the electroconductive fine particles of this invention to an electrode.

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
Substrate fine particles were obtained by forming a copper layer having a thickness of 10 μm by electroplating on the surface of resin fine particles (average particle diameter 260 μm) made of a copolymer of tetramethylolmethane tetraacrylate and divinylbenzene.
On the other hand, low melting point metal fine particles (particle size distribution: 5 to 15 μm) having a composition of tin 96.5 silver 3.5 alloy are immersed in a 0.5 wt% ethanol solution of octadecanedioic acid for 2 hours, filtered and dried. Thus, flux-laminated low melting point metal fine particles were obtained.
50 g of the obtained substrate fine particles and 75 g of the flux-laminated low melting point metal fine particles were put into a Theta composer (manufactured by Tokuju Kogakusha Co., Ltd.) and mixed. As a result, the flux-laminated low melting point metal fine particles are adhered to the base fine particles to form a film, and a 25 μm thick tin 96.5 silver 3.5 alloy layer is formed on the surface of the base fine particles to obtain conductive fine particles. It was.
When mixing using a theta composer, the rotating container (vessel) was rotated reversely at 3000 rpm and the rotating blade (rotor) was rotated at 30 rpm so that the shear compression force acts on the flux-laminated low melting point metal fine particles. The mixing time was 120 minutes.

(Comparative Example 1)
Conductive fine particles were prepared in the same manner as in Example 1 except that the low melting point metal fine particles (particle size distribution 5 to 15 μm) were not immersed in a 0.5 wt% ethanol solution of octadecanedioic acid for 2 hours. did.

(Comparative Example 2)
The conductive fine particles obtained in Comparative Example 1 were immersed in a 0.5 wt% ethanol solution of octadecanedioic acid for 2 hours, filtered and dried to produce conductive fine particles.

(Comparative Example 3)
Microcapsules (average particle size 5 μm) containing the flux are prepared by copolymerizing ethyl acrylate, acrylonitrile and methacrylonitrile in an aqueous dispersion in which a commercial flux (Gammalux 360, Senju Metal Industry) is dispersed. did. Next, 50 g of the substrate fine particles, 0.6 g of the flux-encapsulated microcapsules, and 75 g of the low melting point metal fine particles are put into a theta composer and mixed to adhere and form a film on the substrate fine particles. Conductive fine particles were produced in the same manner as in Example 1 except that a 25 μm thick tin 96.5 silver 3.5 alloy layer was formed containing 5 vol% of the capsules with respect to the entire conductive fine particles.

(Comparative Example 4)
Example except that 50 g of the conductive fine particles obtained in Comparative Example 1 and 1 g of the flux-encapsulating capsules coated with the hot melt adhesive were mixed while heating to fix the flux-encapsulating capsules on the surface of the conductive fine particles. In the same manner as in Example 1, conductive fine particles were produced.

<Evaluation>
The following evaluation was performed about the electroconductive fine particles obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Shear test The obtained conductive fine particles were left in an air atmosphere at a temperature of 25 ° C. and a humidity of 50% for 100 hours to promote the formation of an oxide film. Next, 112 pieces were mounted on a silicon chip having a copper electrode, and placed in a reflow furnace set at 270 ° C. to be melted. Thereafter, a lateral stress of 250 gf was applied to each conductive fine particle mounted on the silicon chip using a shear tester ("Series 4000" manufactured by Daisy), and the copper electrode surface was broken. The total number of things was counted.
When the conductive fine particles obtained in Comparative Example 1 were used, the bumps could not be formed because the electrodes were not wet. The conductive fine particles obtained in Comparative Example 3 could not be mounted because they could not be sucked by the ball mounter.

According to the present invention, conductive fine particles that can realize high connection reliability and can simplify the electrode connection step, an anisotropic conductive material using the conductive fine particles, and A connection structure can be provided.

Claims (8)

Conductive fine particles in which a low melting point metal layer is formed on the surface of the base fine particles,
The low-melting-point metal layer is a conductive fine particle formed by bringing low-melting-point metal fine particles having a layer made of a flux on the surface thereof into contact with substrate fine particles and melt-softening them by shear compression. 2. The conductive fine particles according to claim 1, wherein the low melting point metal layer is made of tin or an alloy of tin and another metal. The conductive fine particles according to claim 1, wherein the substrate fine particles are resin fine particles. The conductive fine particles according to claim 1, wherein the substrate fine particles are copper fine particles. The conductive fine particles according to claim 1, 2, 3, or 4, further comprising a conductive layer between the substrate fine particles and the low melting point metal layer. An anisotropic conductive material, wherein the conductive fine particles according to claim 1, 2, 3, 4 or 5 are dispersed in a binder resin. A connection structure comprising the conductive fine particles according to claim 1, 2, 3, 4 or 5, or the anisotropic conductive material according to claim 6. A method for producing the conductive fine particles according to claim 1, 2, 3, 4 or 5,
A step of forming a low-melting-point metal layer on the base particle by bringing the low-melting-point metal fine particle having a layer made of a flux on the surface into contact with the base particle and melting the low-melting-point metal fine particle by shear compression The manufacturing method of the electroconductive fine particles characterized by the above-mentioned.

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