JP2020095785A - Conductive particle for anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive particle capable of joining electrodes by heat and a manufacturing method thereof.
SOLUTION: The resin particle and a tin alloy supported so as to cover the surface of the resin particle are provided, the tin alloy forms a layer, and the average value of the layer thickness is the average particle of the resin particle. The present invention relates to conductive particles for an anisotropic conductive film having a diameter of 0.003 to 0.3 times.
[Selection diagram] Figure 1

Description

The present invention relates to conductive particles for anisotropic conductive adhesives.

The method of mounting an IC (Integrated Circuit) for driving a liquid crystal on a glass panel for liquid crystal display can be roughly classified into two types: COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting. In COG mounting, the liquid crystal driving IC is directly bonded onto the glass panel using an anisotropic conductive adhesive containing conductive particles. On the other hand, in COF mounting, liquid crystal driving ICs are bonded to a flexible tape having metal wiring, and they are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. The term "anisotropic" as used herein means that conductivity is maintained in the pressing direction and insulation is maintained in the non-pressurizing direction. As the conductive particles used for the anisotropic conductive adhesive, conductive particles in which a metal conductive layer is formed on the surface of resin particles are mainly used.

2. Description of the Related Art In recent years, in the field of electronic devices such as liquid crystal displays, personal computers, tablet PCs, and smartphones, electrode circuits have become finer and have a smaller area, and it is necessary to make conductive particles smaller. However, with the miniaturization of the conductive particles, it is necessary to reduce the thickness of the metal conductive layer. Furthermore, it is difficult to impart conductivity to the resin particles in the existing process. It is difficult to achieve both low resistance characteristics. Therefore, a new technique for improving the conductivity of the conductive particles is required.

For example, Patent Document 1 discloses an anisotropic conductive adhesive characterized in that metal particles supporting resin particles in which a plurality of metal particles are supported on a resin particle surface are dispersed in an adhesive component. There is.

Patent Document 2 is a conductive particle including a base resin particle, a plurality of nano-sized conductive particles, and a conductive layer, and conductive by dot bonding between a plurality of nano-sized conductive particles attached to the surface of the base resin particle. Disclosed is a conductive particle comprising a network and a conductive layer formed on the nano-sized conductive particle by plating.

Further, as a method for producing such conductive particles, Patent Document 3 is a method for producing conductive particles in which a conductive material having conductivity is coated on a core material serving as a base material. A kneading step of charging the conductive material smaller than the core material and kneading the charged core material and the conductive material is included, and the kneading step attaches the conductive material to the core material. While applying a compressive force to the core material, a method for producing conductive particles, characterized by comprising a torsional shearing step of applying shearing force from a plurality of directions so that the conductive material is attached. Disclosure.

JP 2002-245853 A JP, 2010-033911, A JP, 2011-228281, A

For example, the metal fine particles in the anisotropic conductive adhesive described in Patent Documents 1 to 3 are composed of a metal capable of forming plating such as Au, Pt, Ni, Cu, Ag, and the like. It is said that when the particles are deformed by being pressed against each other, the metal fine particles are brought into close contact with each other and good conduction can be obtained. Further, it is said that the metal fine particles are advantageous in that unlike the conventional metal-coated resin particles, the problem that the metal coating is broken during pressure bonding and conduction cannot be secured does not occur.

However, since the fine metal particles capable of forming plating have a high melting point, it is difficult to bond the electrodes by heat.

The present invention has been achieved in view of the above problems of the prior art, and an object of the present invention is to provide a conductive particle capable of joining electrodes by heat and a method for manufacturing the same.

As a result of intensive studies, the present inventors have mixed a suspension (dispersion liquid) of resin particles and a suspension of tin alloy, and then agitated the resin to make use of an electrostatic force or an intermolecular force. After supporting a tin alloy on the surface of the particles, optionally produced by a method of heating, resin particles, and a tin alloy supported so as to cover the surface of the resin particles, the tin alloy layer That the average value of the thickness of the layer is 0.003 to 0.3 times the average particle diameter of the resin particles, the conductive particles for anisotropic conductive film can solve the above problems. Heading, completed the present invention.

According to the present invention, by providing a conductive particle having a structure in which the surface of a resin particle is covered with a tin alloy, it is possible to perform metal-to-metal bonding by heat, a highly conductive conductive particle and a difference using the same. It has an extremely excellent effect that a one-way conductive adhesive can be realized. Problems, configurations and effects other than those described above will be clarified by the following description of the embodiments.

It is a figure which shows typically an example of the basic structure of the electroconductive particle of this invention. It is a figure which shows typically an example of the basic structure of the electroconductive particle of another form of this invention. It is a figure which shows typically an example of the preparation method of the electroconductive particle of this invention. It is a figure which shows typically an example of the preparation method of the electroconductive particle of another form of this invention. It is a figure which shows typically an example of the manufacturing system of the electroconductive particle of this invention. It is a figure which shows typically an example of the manufacturing system of the electroconductive particle of another form of this invention. It is the SEM image which observed the electroconductive particle obtained in the Example of this invention. It is the SEM image which observed the electroconductive particle obtained in the Example of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the size and shape of each part are exaggerated for clarity, and the actual size and shape are not accurately drawn. Therefore, the technical scope of the present invention is not limited to the size and shape of each part shown in these drawings. It is needless to say that the embodiments to be described later are examples, and that other modes such as a combination of the respective examples, a combination with a known or well-known technique, and a substitution are possible.

<Conductive particles>
The conductive particles for the anisotropic conductive film of the present invention include resin particles and a tin alloy supported so as to cover the surfaces of the resin particles, the tin alloy forming a layer, and the thickness of the layer. The average value of the thickness is 0.003 to 0.3 times, preferably 0.01 to 0.1 times, more preferably 0.03 to 0.1 times the average particle diameter of the resin particles.

When the ratio of the thickness of the resin particles and the layer of tin alloy in the conductive particles is the above ratio, the conductive particles have anisotropic conductivity and high conductivity, which enables metal-to-metal bonding by heat. To become active particles. It is important to control the thickness of the tin alloy layer because if the tin alloy layer is too thin, the conductivity cannot be ensured, and if it is too thick, the uniformity of the layer cannot be maintained.

Here, examples of the resin particles include known resin particles in the technical field, but are not limited to, for example, acrylic resins such as polymethylmethacrylate and polymethylacrylate, polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene. Polymers such as alkanediol di(meth)acrylate and/or divinylbenzene, polystyrene which is a polymer of styrene, and the like. Polymers such as alkanediol di(meth)acrylate and/or divinylbenzene are preferable as the resin particles from the viewpoint of recovery rate and the like.

The shape of the resin particles is usually spherical. Here, the spherical shape includes not only a true sphere but also an ellipsoid, an arbitrary rotating body, and the like. For example, the aspect ratio is usually 0.5 or more, preferably 0.8 or more.

Since the resin particles are the above-mentioned resin particles, the tin alloy can be supported on the surface of the resin particles. Since the resin particles have a high sphericity and a uniform particle size distribution, the bonding area becomes constant, which facilitates thermal bonding.

The size of the resin particles is not limited as long as it falls within the range defined above with respect to the average value of the thickness of the layer formed by the tin alloy, but the average particle size is usually 0.1 μm to 10 μm, preferably 0 μm. It is 0.5 μm to 3 μm. The average particle size of the resin particles can be measured by SEM.

When the size of the resin particles is within the above range, low resistance characteristics of the conductive particles are secured.

Examples of the tin alloy include tin alloys known in the art, and are not limited, but for example, alloys having a low melting point, such as Sn-Pb-based, Pb-Sn-Sb-based, Sn-Sb-based, Examples thereof include Sn-Pb-Bi system, Bi-Sn system, Sn-Cu system, Sn-Pb-Cu system, Sn-Ag system, Sn-Pb-Ag system, Sn-In system and the like. As the tin alloy, Pb-free is preferable from the viewpoint of the environment, and Bi—Sn type and Sn—In type are preferable because low temperature bonding is possible. Further, from the viewpoint of bonding stability against external temperature, Bi-Sn system is preferable.

When the composition of the tin alloy is the above-mentioned composition, the conductive particles become conductive particles having anisotropic conductivity and high conductivity, which can be bonded to each other by heat.

The shape of the tin alloy forming the layer is, for example, a particle (sphere) shape (particulate tin alloy), a scale-like flake shape (flake tin alloy), or the like. The tin alloy may be a coating film that covers the entire surface of the resin particles (coating tin alloy). It is desirable that the shape of the tin alloy forming the layer is uniform.

When the shape of the tin alloy is the above-mentioned shape, the electroconductive particles become electroconductive particles having anisotropic electroconductivity and having high electroconductivity capable of performing metal-to-metal bonding by heat.

The size of the tin alloy forming the layer is not limited as long as the thickness of the layer is within the range defined above with respect to the average particle size of the resin particles.

For example, when the layer is composed of a particulate tin alloy, the size of the particulate tin alloy is not limited as long as the thickness of the layer is within the range defined above with respect to the average particle diameter of the resin particles, but the average The particle size is usually 0.001 μm to 1 μm, preferably 0.03 μm to 0.3 μm. The average particle size of the particulate tin alloy can be measured by SEM.

For example, when the layer is composed of a flaky tin alloy, the size of the tin alloy is not limited as long as the thickness of the layer falls within the range defined above with respect to the average particle diameter of the resin particles, but The average value of the sides is usually 0.001 μm to 1 μm, preferably 0.03 μm to 0.3 μm. The average value of the long sides of the tin alloy pieces can be measured by SEM.

The conductive layer formed of a tin alloy may be one layer or a plurality of layers, preferably 1 layer to 10 layers, more preferably 1 layer to 5 layers.

The thickness of the layer formed of the tin alloy is not limited as long as it is the thickness defined above with respect to the average particle diameter of the resin particles, but is an average value and is usually 0.001 μm to 1 μm, preferably 0.03 μm. Is about 0.3 μm. The average value of the thickness of the layer formed of the tin alloy can be measured by SEM.

When the thickness of the layer formed of the tin alloy is in the above range, the conductive particles become anisotropically conductive and highly conductive conductive particles that can be bonded to each other by heat.

The conductive particles for an anisotropic conductive adhesive of the present invention can be used for an anisotropic conductive adhesive, for example, an adhesive film, and a connection structure using the anisotropic conductive adhesive. The anisotropic conductive adhesive is used for adhering the circuit members to each other and electrically connecting the circuit electrodes of the respective circuit members. The anisotropic conductive adhesive contains an adhesive component and conductive particles, and the conductive particles are dispersed in the film-shaped adhesive. The concentration of the conductive particles in the anisotropic conductive adhesive is usually 5% by mass to 60% by mass, preferably 15% by mass to 50% by mass, based on the total weight of the anisotropic conductive adhesive.

FIG. 1 schematically shows a cross-sectional view of an example of the conductive particles 10 of the present invention and an anisotropic conductive adhesive 1 using the conductive particles 10. As shown in FIG. 1, the anisotropic conductive adhesive 1 has a structure in which conductive particles 10 are uniformly dispersed in a film-like adhesive 12, and the conductive particles 10 are the surface of the resin particles 101. Has a structure covered with a layer formed by a plurality of particulate tin alloys 102.

In the anisotropic conductive adhesive 1 of FIG. 1, by sandwiching the anisotropic conductive adhesive 1 containing the conductive particles 10 between the electrodes and applying heat, the particulate tin alloy 102 is melted and the electrodes are joined together. To do. The conductive particles 10 maintain conductivity in the inter-electrode direction (z direction), but since the conductive particles 10 do not contact each other, they maintain insulation in the plane direction (xy plane) of the adhesive 12.

FIG. 2 schematically shows a cross-sectional view of an example of conductive particles 10 of another embodiment of the present invention and an anisotropic conductive adhesive 1 using the conductive particles 10. As shown in FIG. 2, the anisotropic conductive adhesive 1 has a structure in which conductive particles 10 are uniformly dispersed in a film-like adhesive 12, and the conductive particles 10 are the surfaces of the resin particles 101. Has a structure covered with a layer formed of a tin alloy or a film-shaped tin alloy 103.

Similar to FIG. 1, even in the anisotropic conductive adhesive 1 of FIG. 2, a layer formed of a tin alloy by sandwiching the anisotropic conductive adhesive 1 containing the conductive particles 10 between electrodes and applying heat. Alternatively, the film-shaped tin alloy 103 is melted and the electrodes are joined together. The conductive particles 10 maintain conductivity in the inter-electrode direction (z direction), but since the conductive particles 10 do not contact each other, they maintain insulation in the plane direction (xy plane) of the adhesive 12.

<Method for producing conductive particles>
The method for producing conductive particles according to the present invention is a method in which a suspension of resin particles and a tin alloy, for example, a suspension of a particulate tin alloy or a flaky tin alloy are mixed and then stirred, and electrostatic force or intermolecular Supporting the tin alloy on the surface of the resin particles by using force.

Here, the suspension of resin particles is a suspension of resin particles known in the art, and as the resin particles, the resin particles described in the above <conductive particles> can be used. Examples of the suspension of resin particles include a suspension in which crosslinked polystyrene particles activated by dimethylamine borane or the like are dispersed in distilled water.

By using the above-mentioned suspension of resin particles as the suspension of resin particles, the tin alloy can be supported on the surface of the resin particles.

The suspension of the tin alloy can be obtained by dispersing the particulate tin alloy having the composition described in the above <conductive particles> in a solvent and optionally pulverizing it. As the pulverizing method, a pulverizing method known in the art can be used, and examples thereof include a bead mill. The shape of the tin alloy in the suspension of the tin alloy can be adjusted by the grinding conditions of the particulate tin alloy, for example, in the case of a bead mill, the bead diameter, the grinding time, the grinding temperature, the solvent, and the like. For example, when a soft metal such as a particulate tin alloy is crushed by a bead mill, the particulate tin alloy is not immediately crushed but has an elongated shape. After that, the particles are further extended by prolonging the time of the pulverization treatment, and gradually broken to be finely divided.

As an example of a method of supporting the tin alloy on the surface of the resin particles by using electrostatic force or intermolecular force, an alternate lamination method using electrostatic force or the like can be mentioned.

By mixing the suspension of resin particles and the suspension of tin alloy and then stirring, the tin alloy can be supported on the surface of the static resin particles by electrostatic force or intermolecular force.

Furthermore, the method for producing conductive particles according to another embodiment of the present invention, a suspension of resin particles, and a tin alloy, for example, a suspension of a particulate tin alloy or flaky tin alloy is mixed and then stirred, After supporting the tin alloy on the surface of the resin particles using electrostatic force or intermolecular force, the tin alloy supported on the surface of the resin particles is melted by heating, and the tin alloy melts the surface of the resin particles. After covering, the molten tin alloy is solidified by cooling to form a film-form tin alloy on the surface of the resin particles.

Here, the heat treatment is usually performed at 100° C. to 200° C., preferably 120° C. to 170° C. for usually 0.5 minutes to 5 minutes, preferably 0.5 minutes to 3 minutes.

By performing the heat treatment under the above conditions, the tin alloy carried on the surface of the resin particles can form a film on the surface of the resin particles.

FIG. 3 shows an example of the process of the method for producing the conductive particles 10 of the present invention.

First, the suspension containing the resin particles 101 and the suspension containing the particulate tin alloy 102 are stirred and mixed, and the particulate tin alloy 102 is supported on the surface of the resin particles 101.

Next, the unsupported particulate tin alloy 102 is removed and the conductive particles 10 are purified by performing a separation step such as filtration or sedimentation. Examples of the separation method include filter filtration for separation by particle size, sedimentation separation for separation by particle size and mass difference, and separation methods utilizing the difference in flow velocity distribution with respect to particle size.

FIG. 4 shows an example of a process of a method for producing the conductive particles 10 according to another embodiment of the present invention.

First, the suspension containing the resin particles 101 and the suspension containing the particulate tin alloy 102 are mixed by stirring, and the particulate tin alloy 102 is supported on the surface of the resin particles 101.

Next, the unsupported particulate tin alloy 102 is removed and the conductive particles 10 are purified by performing a separation step such as filtration or sedimentation. Examples of the separation method include filter filtration for separation by particle size, sedimentation separation for separation by particle size and mass difference, and separation methods utilizing the difference in flow velocity distribution with respect to particle size.

Further, the separated suspension containing the conductive particles 10 is heated to melt the particulate tin alloy 102 carried on the surface of the resin particles 101. By using the particulate tin alloy 102 having a melting point lower than the melting point of the resin particles 101, the molten particulate tin alloy 102 covers the surface of the resin particles 101 by surface tension and forms the film-shaped tin alloy 103. Then, the suspension containing the conductive particles 10 is cooled, and the temperature of the liquid is lowered below the melting point of the particulate tin alloy 102, so that the coated tin alloy 103 is solidified.

<Production system for conductive particles>
The production system of the conductive particles of the present invention is a container for resin particle suspension for holding a suspension of resin particles, and a resin particle suspension for feeding the suspension of resin particles , A stirrer for resin particle suspension to stir the suspension of resin particles and prevent the precipitation of resin particles, and a tin alloy suspension for holding the suspension of tin alloy Container, a tin alloy suspension feed pump for feeding the tin alloy suspension, and a tin alloy suspension for stirring the tin alloy suspension and preventing the precipitation of the tin alloy. A stirrer for suspension, a mixing mechanism for mixing a suspension of resin particles and a suspension of tin alloy to support the tin alloy on the surface of the resin particles, and resin particles supporting the tin alloy on the surface A conductive mechanism comprising, or consisting of, a separation mechanism for separating unsupported tin alloy and a container for the tin alloy for holding a separated suspension of unsupported tin alloy. This is a system for producing permeable particles. The respective devices are connected by an appropriate connection mechanism.

By using the above system as a system for producing conductive particles of the present invention, the conductive particles of the present invention can be efficiently produced.

Further, another embodiment of the conductive particle production system of the present invention, a container for resin particle suspension for holding a suspension of resin particles, a resin for sending the suspension of resin particles. A liquid feed pump for the particle suspension, a stirrer for the resin particle suspension for stirring the resin particle suspension to prevent precipitation of the resin particles, and for holding the tin alloy suspension A container for tin alloy suspension, a liquid feed pump for tin alloy suspension for feeding the tin alloy suspension, and agitating the tin alloy suspension to prevent precipitation of the tin alloy A stirrer for tin alloy suspension for mixing, a mixing mechanism for mixing the suspension of resin particles and the suspension of tin alloy and supporting the tin alloy on the surface of the resin particles, and the tin alloy on the surface Separation mechanism for separating the supported resin particles and the unsupported tin alloy, a container for the tin alloy for holding the separated unsupported tin alloy suspension, and the surface of the tin alloy A heating mechanism for melting the tin alloy by heating the resin particles supported on the resin particles to form a film-shaped tin alloy on the surface of the resin particles, and containing conductive particles for collecting the suspension that has passed through the heating mechanism. A system for producing electrically conductive particles comprising or consisting of a container for suspension. The respective devices are connected by an appropriate connection mechanism.

By adding a heating mechanism to the conductive particle manufacturing system of the present invention, the conductive particles including the coated tin alloy of the present invention can be efficiently manufactured.

FIG. 5 schematically shows an example of a configuration diagram of the manufacturing system 11 for the conductive particles 10 of the present invention.

The production system 11 of the present invention includes a resin particle suspension container 111 for holding a resin particle suspension 1110 and a resin particle suspension 1110 for feeding the resin particle suspension 1110. Liquid feed pump 112, stirrer 113 for resin particle suspension for stirring resin particle suspension 1110 to prevent precipitation of resin particles 101 (FIG. 3), and tin alloy suspension 1140. A container 114 for a tin alloy suspension for holding a tin alloy suspension, a liquid feed pump 115 for a tin alloy suspension for feeding a tin alloy suspension 1140, and a tin alloy suspension 1140. The stirrer 116 for tin alloy suspension for stirring to prevent precipitation of the particulate tin alloy 102 (FIG. 3), the suspension 1110 of resin particles and the suspension 1140 of tin alloy are mixed to form resin particles. The mixing mechanism 117 for supporting the particulate tin alloy 102 (FIG. 3) on the surface of 101 (FIG. 3), and the resin particles 101 (FIG. 3) supporting the particulate tin alloy 102 (FIG. 3) on the surface Separation mechanism 118 for separating unsupported particulate tin alloy 102 (FIG. 3), and particulate for retaining a separated suspension 1190 of unsupported particulate tin alloy 102 (FIG. 3). Container for tin alloy 102 (FIG. 3) and conductive particle-containing suspension for collecting the suspension containing conductive particles 10 that has passed through the separation mechanism 118 (conductive particle-containing suspension 1200) Container 120 of, or composed of. It should be noted that the respective devices are connected by an appropriate connection mechanism such as a connection mechanism 2011 of the container 111 for resin particle suspension and the liquid feed pump 112 for resin particle suspension.

FIG. 6 schematically shows an example of a configuration diagram of the manufacturing system 11 for the conductive particles 10 according to another embodiment of the present invention.

The production system 11 of the present invention includes a resin particle suspension container 111 for holding a resin particle suspension 1110 and a resin particle suspension 1110 for feeding the resin particle suspension 1110. Liquid supply pump 112, a stirrer 113 for resin particle suspension for stirring the resin particle suspension 1110 to prevent precipitation of the resin particles 101 (FIG. 4), and a tin alloy suspension 1140. A container 114 for a tin alloy suspension for holding a tin alloy suspension, a liquid feed pump 115 for a tin alloy suspension for feeding a tin alloy suspension 1140, and a tin alloy suspension 1140. A stirrer 116 for tin alloy suspension to prevent precipitation of the particulate tin alloy 102 (FIG. 4) by stirring, and a suspension 1110 of resin particles and a suspension 1140 of tin alloy are mixed to form resin particles. Mixing mechanism 117 for supporting the particulate tin alloy 102 (FIG. 4) on the surface of 101 (FIG. 4), and resin particles 101 (FIG. 4) supporting the particulate tin alloy 102 (FIG. 4) on the surface Separation mechanism 118 for separating unsupported particulate tin alloy 102 (FIG. 4) and particulate for retaining a separated suspension 1190 of unsupported particulate tin alloy 102 (FIG. 4). The particulate tin alloy 102 (FIG. 4) is melted by heating the container for the tin alloy 102 (FIG. 4) and the resin particles 101 (FIG. 4) carrying the particulate tin alloy 102 (FIG. 4) on the surface. , A suspension containing the heating mechanism 119 for forming the coating tin alloy 103 (FIG. 4) on the surface of the resin particles 101 (FIG. 4) and the conductive particles 10 that have passed through the heating mechanism 119 (suspended with the conductive particles. A container 120 for the suspension containing conductive particles for collecting the suspension liquid 1200). It should be noted that the respective devices are connected by an appropriate connection mechanism such as a connection mechanism 2011 of the container 111 for resin particle suspension and the liquid feed pump 112 for resin particle suspension.

As a method of stirring the two stirrers (113, 116), there is a method of stirring the suspension by rotating a spatula or a magnetic stirrer.

Examples of the mixing method of the mixing mechanism 117 include a batch method in which two liquids are stirred and mixed in a stirring tank, and a flow method in which the two liquids are caused to flow in a minute flow channel and mixed by a diffusion effect.

Examples of the separation method of the separation mechanism 118 include a filter filtration, a sedimentation separation, and a mechanism utilizing the difference in flow velocity distribution.

Examples of the heating method of the heating mechanism 119 include a method of heating and cooling the container holding the target liquid, and a method of heating and cooling the flow path through which the target liquid flows.

[Preparation of conductive particles]
(Step a) Preparation of Suspension of Resin Particles Crosslinked polystyrene particles having an average particle diameter of 3.0 μm were added to a 0.5% by mass dimethylamine borane solution adjusted to pH 6.0 to activate the surface of the resin. The particles were obtained. Then, the resin particles having the activated surface were immersed in 20 mL of distilled water and ultrasonically dispersed to obtain a suspension of resin particles.

(Step b) Preparation of suspension of tin alloy (1) Suspension of particulate tin alloy not subjected to pulverization A particulate tin alloy (average particle size 5 μm, Bi—Sn system) was added in isopropanol. A suspension was obtained by adding the particulate tin alloy so that the concentration thereof was about 10% by mass based on the total weight of the suspension. The suspension was subjected to ultrasonic agitation for 15 minutes, and then allowed to stand for 80 minutes to sediment and separate large metal particles, and the supernatant was recovered to remove the large tin alloy, and the pulverization treatment was not performed. A suspension of particulate tin alloy was obtained.

(2) Suspension of flake tin alloy that has been subjected to pulverization A particulate tin alloy (average particle size 5 μm, Bi—Sn system) was added to isopropanol so that the concentration of the particulate tin alloy was the total weight of the suspension. On the other hand, a suspension was obtained by adding about 10% by mass. The obtained suspension was pulverized with a beads mill (manufactured by Nippon Coke Co., Ltd., trade name "MSC-50") using about 0.2% zirconia particles with a diameter of about 10% by mass based on the total weight of the suspension. went.

When a bead mill pulverized a soft metal such as a particulate tin alloy, the metal particles were not pulverized immediately but had an elongated shape. Further, the particles were further extended by prolonging the time of the pulverization treatment, and the particles were gradually torn, whereby the particles could be miniaturized. In this example, the crushing process was performed for 360 minutes.

The suspension of the tin alloy after the pulverization process contained not only the refined tin alloy but also the stretched tin alloy. In order to remove these stretched large tin alloys, the suspension of the tin alloy after the pulverization treatment was subjected to ultrasonic agitation for 15 minutes, and then allowed to stand for 80 minutes to sediment large metal particles. Then, the supernatant liquid was collected to obtain a suspension of the flaky tin alloy which had been subjected to the pulverization treatment while removing the large tin alloy.

(Step c) Modification of Tin Alloy on Surface of Resin Particles To 100 μL of the suspension of tin alloy recovered in Step b, 10 μL of a suspension of 6% resin particles was added to obtain a mixed suspension. The mixed suspension was repeatedly mixed by inversion (0.5 minutes) and ultrasonic agitation (5 minutes) (total 24 times). Inversion mixing and ultrasonic agitation have the effect of preventing sedimentation of particles and aggregation of particles, and modifying the surface of one resin particle with a tin alloy.

[Evaluation of conductive particles]
The prepared conductive particles scanning electron microscope (S canning E lectron M icroscope, hereinafter SEM) was used to observe. The acquired SEM images are shown in FIGS. 7 and 8(a) to (d).

FIG. 7 shows that, in (step c), the pulverized tin alloy prepared in (1) of (step b) is not added to the surface of the resin particles of the suspension of resin particles prepared in (step a). 8(a) to 8(d) are SEM images of the conductive particles carrying (a), and (a) to (d) show ((c) on the resin particle surface of the suspension of resin particles prepared in (a)). It is a SEM image of the electroconductive particle which carry|supported the flaky tin alloy which performed the grinding process in (2) of process b).

In FIG. 7, it could be confirmed that the particulate tin alloy was carried on the surface of the resin particles. In addition, in FIGS. 8A to 8D, it was confirmed that the flake tin alloy was carried on the surface of the resin particles. From this result, it was confirmed that resin particles having a tin alloy supported on their surfaces could be prepared by the method of the present specification.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are included. For example, a part of the configuration of the embodiment can be added/deleted/replaced with another configuration.

1: anisotropically conductive adhesive, 10: conductive particles, 11: manufacturing system, 12: adhesive, 101: resin particles, 102: particulate tin alloy, 103: coating tin alloy, 111: resin particle suspension Container for liquid, 112: liquid feed pump for resin particle suspension, 113: stirrer for resin particle suspension, 114: container for tin alloy suspension, 115: for tin alloy suspension Liquid feed pump, 116: stirrer for tin alloy suspension, 117: mixing mechanism, 118: separation mechanism, 119: heating mechanism, 120: container for suspension containing conductive particles, 1110: suspension of resin particles Suspension, 1140: Suspension of tin alloy, 1190: Suspension of separated unsupported tin alloy, 1200: Suspension containing conductive particles, 2011: Container and resin for suspension of resin particles Connection mechanism of liquid feed pump for particle suspension

Claims (9)

The resin particles and a tin alloy supported so as to cover the surfaces of the resin particles are provided, and the tin alloy forms a layer, and the average value of the layer thickness is 0. Conductive particles for anisotropic conductive film, which are 003 times to 0.3 times. The conductive particles according to claim 1, wherein the tin alloy is a particulate tin alloy, a flake tin alloy, or a film tin alloy. Tin alloy is Sn-Pb system, Pb-Sn-Sb system, Sn-Sb system, Sn-Pb-Bi system, Bi-Sn system, Sn-Cu system, Sn-Pb-Cu system, Sn-Ag system, The conductive particle according to claim 1, which is at least one selected from the group consisting of Sn-Pb-Ag-based and Sn-In-based. The conductive material according to claim 1, wherein the resin particles are polymethyl methacrylate, polymethyl acrylate, polyethylene, polypropylene, polyisobutylene, polybutadiene, a polymer of alkanediol di(meth)acrylate and/or divinylbenzene, or polystyrene. particle. An anisotropic conductive adhesive in which the conductive particles according to any one of claims 1 to 4 are dispersed in a film-like adhesive. The method of mixing a suspension of resin particles and a suspension of tin alloy, followed by stirring, and supporting the tin alloy on the surface of the resin particles by using electrostatic force or intermolecular force. A method for producing the conductive particles described. Further, the tin alloy supported on the surface of the resin particles is melted by heating, the surface of the resin particles is covered with the melted tin alloy, and then the melted tin alloy is solidified, and the film-shaped tin alloy is formed on the surface of the resin particles. 7. The method of claim 6 including forming. Container for resin particle suspension for holding suspension of resin particles, liquid feed pump for resin particle suspension for feeding suspension of resin particles, and suspension of resin particles Stirrer for resin particle suspension to stir the liquid to prevent precipitation of resin particles, container for tin alloy suspension to hold the suspension of tin alloy, and suspension of tin alloy A liquid feed pump for the tin alloy suspension for feeding the tin alloy, a stirrer for the tin alloy suspension for stirring the tin alloy suspension to prevent the precipitation of the tin alloy, and a resin particle In order to separate the mixing mechanism for mixing the suspension and the suspension of the tin alloy and supporting the tin alloy on the surface of the resin particles, and the resin particles supporting the tin alloy on the surface and the tin alloy not supporting the tin alloy on the surface. 2. A system for producing electrically conductive particles according to claim 1, comprising a separation mechanism of 1. and a container for tin alloy for holding a separated suspension of unsupported tin alloy. Furthermore, by heating the resin particles carrying the tin alloy on the surface, the tin alloy is melted, and the heating mechanism for forming the film-shaped tin alloy on the resin particle surface and the suspension that has passed through the heating mechanism are collected. A container for a suspension containing conductive particles for use in a system according to claim 8.

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