JP2005327510A - Conductive fine particle and anisotropic conductive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide conductive fine particles capable of properly connecting electrode terminals to be connected to each other even when the distance between them is irregular, and having excellent connection reliability; and to provide an anisotropic conductive material using the conductive fine particles. <P>SOLUTION: These conductive fine particles manufactured by forming conductive metal layers on surfaces of resin particles are a mixture of conductive fine particles 1 and conductive fine particles 2 different in both a 10%K value and fracture strain. Each conductive fine particle 1 has a 10%K value satisfying the following expression (1) and the fracture strain less than 50%. Each conductive fine particle 2 has a 10%K value satisfying the following expression (2) and the fracture strain not less than 50%. In the conductive fine particles, the weights of the two kinds of them are the same, or either of them is excessively included by not more than 20 wt.%. 10%K value of the conductive fine particles 1: K<SB>1</SB>(N/mm<SP>2</SP>)>15,680R<SB>1</SB>(μm)<SP>-7/10</SP>(1). 10%K value of the conductive fine particles 2: K<SB>2</SB>(N/mm<SP>2</SP>)>11,530R<SB>2</SB>(μm)<SP>-3/5</SP>(2). In expressions, R1: particle diameter of the conductive fine particles 1; and R2: particle diameter of the conductive fine particles 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive fine particle and an anisotropic conductive material. Specifically, the conductive fine particle that can be connected well even when the interval between electrode terminals to be connected is wide and narrow, and the conductive fine particle are used. The present invention relates to an anisotropic conductive material.

  The conductive fine particles are mixed and kneaded with a binder resin or an adhesive, for example, an anisotropic conductive paste, an anisotropic conductive ink, an anisotropic conductive adhesive, an anisotropic conductive film, Widely used as anisotropic conductive materials such as anisotropic conductive sheets.

  These anisotropic conductive materials are, for example, for electrically connecting substrates in electronic devices such as liquid crystal displays, personal computers, and mobile phones, and electrically connecting small components such as semiconductor elements to the substrate. In order to do so, it is used by being sandwiched between opposing substrates and electrode terminals.

  Conventionally, as the conductive fine particles used for the anisotropic conductive material, metal plated particles in which metal particles, plastic particles, or organic / inorganic composite particles are used as core particles and the surface thereof is subjected to gold plating by an electroless plating method are used. It is used. For example, Patent Document 1 describes metal plating particles having organic-inorganic composite particles as core particles.

  Compared to metal-plated plastic particles and metal-plated organic-inorganic inorganic composite particles, the above metal particles are harder and harder to bump into gold bumps, and because they have poor recoverability, they cannot absorb variations in the height of the substrate and bumps, and connection reliability In contrast, metal-plated plastic particles and metal-plated organic-inorganic inorganic composite particles are softer and more resilient than metal particles, so even if the board or bump height varies, there is relatively high reliability between electrode terminals. Can be connected by sex.

JP 2003-183337 A

  However, when connecting between bare chips by three-dimensional mounting in the process of manufacturing a multilayer substrate, even if an anisotropic conductive adhesive or anisotropic conductive resin sheet is placed on the connection surface and crimped, depending on the electrode structure May be difficult to connect with an anisotropic conductive adhesive or an anisotropic conductive resin sheet. This is because, for example, the shape of the electrode terminal surface of the semiconductor chip to be stacked or the shape of the electrode terminal surface on the substrate side connected to the semiconductor chip may not necessarily be a flat surface but may be an uneven electrode terminal. . Therefore, in some cases, the interval between the opposing electrode terminals may be narrower than the other connection locations, or may be separated from each other. If it is difficult and the settings are not appropriate, poor connection may occur.

Such connection between the electrode terminals is usually performed under a condition in which a high crimping force is applied between the electrode terminals. Further, a temperature of 150 ° C. or higher is generally applied at the time of pressure bonding. However, if the crimping force is too strong under such temperature conditions, the metal-plated plastic particles and metal-plated organic / inorganic composite particles may be plastically deformed or broken between the electrode terminals with a narrow gap to generate a restoring force. There is a risk of poor connection. Of course, if the pressure-bonding force is too weak, the binder resin concentrates and flows in between the electrode terminals with a wide gap, and the binder resin between the metal plating particles and the electrode terminals may not be excluded, resulting in poor connection. There is.
Accordingly, there is a problem that it is difficult to set the crimping conditions in order to connect the electrode terminal surfaces having different intervals between the opposing electrode terminals with an anisotropic conductive material such as an anisotropic conductive adhesive.

  In particular, there are stud bumps that can be manufactured easily and at low cost in addition to plated bumps as bumps for IC chips. Generally, however, variations in the height of the stud bumps are ± 2 μm, whereas there are variations in the height of the stud bumps. Is as large as about ± 4 μm. For this reason, even when an IC chip with stud bumps is mounted on a wiring board, the above-mentioned connection failure occurs.

  In view of the above situation, the present invention provides conductive fine particles that can be connected satisfactorily even when the distance between electrode terminals to be connected is wide and narrow, and anisotropic using the conductive fine particles. An object is to provide a conductive material.

In order to achieve the above object, according to the first aspect of the present invention, the conductive fine particle 1 in which the conductive metal layer is formed on the surface of the resin particle is different in both the 10% K value and the fracture strain. The conductive fine particles 1 have a 10% K value satisfying the following formula (1) and the fracture strain is less than 50%. The conductive fine particles 2 can be expressed by the following formula ( 2) 10% K value satisfying 2) and fracture strain is 50% or more, and the two kinds of conductive fine particles are contained in the same weight, or one of the conductive fine particles is another conductive fine particle. In addition, the present invention provides conductive fine particles that are excessively contained within a range of 20% by weight or less.
10% K value of conductive fine particles 1: K ₁ (N / mm ² )>
15680R ₁ (μm) ^-7/10 (1)
(R ₁ : particle diameter of conductive fine particles 1)
10% K value of conductive fine particles 2: K ₂ (N / mm ² ) <
11530R ₂ (μm) ^-3/5 (2)
(R ₂ : particle size of conductive fine particles 2)

  The invention according to claim 2 provides the conductive fine particles according to claim 1, wherein at least one of the conductive fine particles is a conductive fine particle having a protrusion having a height of 0.04 μm or more on the surface.

  The invention according to claim 3 provides an anisotropic conductive material in which the conductive fine particles according to claim 1 or 2 are dispersed in a resin binder.

Details of the present invention will be described below.
In the conductive fine particles of the present invention, the conductive fine particles in which the conductive metal layer is formed on the surface of the resin particles are different from each other in the conductive fine particles 1 and the conductive fine particles 2 in which both the 10% K value and the fracture strain are different. It is a mixture. That is, the conductive fine particles of the present invention are composed of a mixture of two types of conductive fine particles having different compression characteristics.

  The method for obtaining the resin particles to be the core particles of the conductive fine particles of the present invention is not particularly limited, and examples thereof include methods by polymerization methods such as emulsion polymerization, suspension polymerization, seed polymerization, dispersion polymerization, and dispersion seed polymerization. . Among these, the seed polymerization method is preferable because resin particles having a uniform particle diameter can be obtained without classifying the resin particles after polymerization. As for the seed polymerization method, for example, JP-A No. 64-81810 is known.

  As a specific method of the seed polymerization method, for example, an aqueous emulsion composed of an ethylenically unsaturated monomer and an aqueous emulsion of an oil-soluble polymerization initiator are added to water in which seed particles are dispersed, and the seed particles are added to the seed particles. A method of polymerizing the ethylenically unsaturated monomer after absorbing the ethylenically unsaturated monomer and the oil-soluble polymerization initiator is mentioned.

  The weight average molecular weight of the seed particles is preferably 20000 or less. Moreover, it is preferable that the said ethylenically unsaturated monomer shall be 10-500 weight part with respect to 1 weight part of seed particles.

  The ethylenically unsaturated monomer used for forming the resin particles in the present invention is not particularly limited, and may be formed only from a crosslinkable monomer or a non-crosslinkable monomer, or a crosslinkable monomer. In addition, a non-crosslinkable monomer may be used in combination. Among these, a crosslinkable monomer is preferably included in order to obtain appropriate compression characteristics. In order to obtain relatively hard conductive fine particles 1, it is preferable to use a hard crosslinkable monomer, and in order to obtain relatively flexible conductive fine particles 2, a flexible crosslinkable monomer. Is preferably used.

  Examples of the hard crosslinkable monomer include divinylbenzene monomers such as divinylbenzene and derivatives thereof. Examples of the flexible crosslinkable monomer include polyfunctional groups such as conjugated dienes such as butadiene and isoprene, polytetramethylene glycol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. Examples include (meth) acrylates. Here, (meth) acrylate means methacrylate or acrylate. The said crosslinkable monomer may be used independently and may use 2 or more types together.

  Examples of the non-crosslinkable monomer include styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, and chloromethylstyrene; unsaturated nitriles such as vinyl chloride and acrylonitrile, isobutyl ( And monofunctional (meth) acrylates such as (meth) acrylate and isooctyl (meth) acrylate. The said non-crosslinkable monomer may be used independently and may use 2 or more types together.

  The oil-soluble polymerization initiator is not particularly limited. For example, benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butyl peroxide Organic peroxides such as oxy-2-ethylhexanoate and di-t-butyl peroxide; azos such as azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis (2,4-dimethylvaleronitrile) System compounds and the like.

  The amount of the oil-soluble polymerization initiator used is preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer.

  In the polymerization, a surfactant and a dispersion stabilizer may be used as necessary.

    The conductive fine particles of the present invention are particles in which a conductive metal layer is coated on the surface with resin particles as core particles.

  The metal used for the said conductive metal layer is not specifically limited, For example, nickel, gold | metal | money, silver, copper, cobalt or the alloy etc. which have these as a main component are mentioned.

  The conductive metal layer can be formed by, for example, metal plating of core particles by electroless plating or the like. The metal plating may be a single metal layer or a multilayer composed of a plurality of metals.

  The thickness of the conductive metal layer in the conductive fine particles of the present invention is preferably 0.02 to 5 μm. When the thickness of the conductive metal layer is less than 0.02 μm, the metal layer is thin and it is difficult to obtain conductivity. On the other hand, if the thickness of the conductive metal layer exceeds 5 μm, the conductive fine particles become too hard, and the conductive fine particles are difficult to deform following the distance between the electrode terminals.

  In addition, it is preferable that the particle size of the electroconductive fine particles of this invention is 1-10 micrometers. Moreover, since the dispersion of the contact area between the conductive fine particles and the electrode is small and stable connection is obtained, the CV value (value obtained by dividing the standard deviation of the particle size distribution by the average particle size as a percentage) is 10% or less. It is preferable that

In the present invention, the compression characteristics such as 10% K value and fracture strain can be obtained using a micro compression tester.
The 10% K value is, for example, a cylinder made of diamond having a diameter of 50 μm using a micro compression tester (PCT-200, manufactured by Shimadzu Corporation) as described in JP-T-6-503180. The conductive fine particles are compressed at a compression speed of 2.65 mN / sec and a maximum test load of 98 mN on the smooth end surface, and a value obtained from the following formula (3).
K (N / mm ² ) = (3 / √2) × F × S ^−3/2 × R ^−1/2 (3)
F: Load value at 10% compression deformation of conductive fine particles (N)
S: Compression displacement (mm) in 10% compression deformation of conductive fine particles
R: Radius of conductive fine particles (mm)

The fracture strain is measured by the same method as the 10% K value measurement method, and is the ratio of the compression displacement to the particle diameter when the particles are broken during the compression process, and is obtained from the following equation (4). Value.
Fracture strain (%) = (B / D) × 100 (4)
B: Compression displacement (mm) when conductive fine particles are destroyed
D: Diameter of conductive fine particles (mm)

  Hereinafter, a method for obtaining a 10% K value and fracture strain in the present invention will be described with reference to the drawings. The graph shown in FIG. 1 is a chart obtained by measuring the compression characteristics of two types of conductive fine particles, with the horizontal axis representing displacement and the vertical axis representing load. In this measurement example, the particle diameters of the conductive fine particles are both 4.2 μm. The 10% K value can be obtained by the above formula (3) using a load value when 10% of the particle diameter is compressed and deformed (0.42 μm in this measurement example). The fracture strain can be obtained by the above equation (4) using the displacement at the inflection point 1 when particle fracture occurs due to compression.

In the present invention, the conductive fine particles 1 have a 10% K value satisfying the following formula (1) and the fracture strain is less than 50%, and the conductive fine particles 2 are 10% satisfying the following formula (2). It is necessary to have a K value and a fracture strain of 50% or more.
10% K value of conductive fine particles 1: K ₁ (N / mm ² )>
15680R ₁ (μm) ^-7/10 (1)
(R ₁ : particle diameter of conductive fine particles 1)
10% K value of conductive fine particles 2: K ₂ (N / mm ² ) <
11530R ₂ (μm) ^-3/5 (2)
(R ₂ : particle size of conductive fine particles 2)

  When the 10% K value of the conductive fine particles 1 is in the range of the above formula (1) and the fracture strain is less than 50%, the conductive fine particles 1 are relatively hard and have a small fracture strain. Further, when the 10% K value of the conductive fine particles 2 is in the range of the above formula (2) and the fracture strain is 50% or more, the conductive fine particles 2 are relatively soft and have a large fracture strain. . Therefore, by mixing and using the conductive fine particles 1 and the conductive fine particles 2, a mixture of two kinds of conductive fine particles having different compression characteristics between hard and soft ones is used. Thereby, even when there are wide and narrow variations in the distance between the electrode terminals to be connected, a good connection can be achieved.

  In the present invention, the two kinds of conductive fine particles, the conductive fine particles 1 and the conductive fine particles 2, are contained in the same weight, or any one of the conductive fine particles is 20% by weight than the other conductive fine particles. It is necessary to contain excessively within the range.

  When the mixing ratio of the conductive fine particles 1 and the conductive fine particles 2 is out of the above range, it may be difficult to follow the variation in the distance between the electrode terminals.

  The conductive fine particles of the present invention can be obtained by adjusting the ratio of the crosslinkable monomer and the non-crosslinkable monomer that form the resin particles as the core particles, respectively, Distortion is obtained.

  That is, the conductive fine particles to be the conductive fine particles 1 can be obtained by using resin particles that are core particles and using a hard crosslinkable monomer. Therefore, it is preferable that the conductive fine particles 1 contain 70% by weight or more of a hard crosslinkable monomer among at least ethylenically unsaturated monomers forming the resin particles.

  The conductive fine particles to be the conductive fine particles 2 can be obtained by using resin particles, which are core particles, using a flexible crosslinkable monomer. Therefore, it is preferable that the conductive fine particles 2 contain 70% by weight or more of a flexible crosslinkable monomer among ethylenically unsaturated monomers forming at least resin particles.

  In the conductive fine particles of the present invention, it is preferable that at least one of the conductive fine particles 1 and the conductive fine particles 2 has a protrusion having a height of 0.04 μm or more on the surface. If the height is less than 0.04 μm, it may be difficult to penetrate the binder resin. If the crimping force at the time of crimping is low, the conductive fine particles and the electrode terminals are easily separated from each other, and the binder resin tends to flow into the contact surface between the conductive fine particles and the electrode terminals. Since the resin can be penetrated and contacted with the electrode terminal, it can be connected well even between terminals having a wide electrode interval.

  The method for forming protrusions on the surface of the conductive fine particles of the present invention is not particularly limited. For example, when metal plating is performed on the surface of the core particles, a method of forming abnormal protrusions to form plating metal, metal fine particles or resin fine particles For example, there is a method of metal plating after adhering to the core particles.

In the present invention, the thickness of the conductive metal layer of the conductive fine particles and the height of the protrusions on the surface of the conductive fine particles can be determined by observing the cross section of the conductive fine particles with a transmission electron microscope (TEM). As the magnification, a magnification that is easy to observe may be selected. For example, 50,000 times is used.
The height of the protrusion on the surface of the conductive fine particles can be obtained by measuring the height appearing as a protrusion from the reference surface forming the outermost surface.

  The anisotropic conductive material of the present invention is obtained by dispersing the above-described conductive fine particles of the present invention in a resin binder.

  The anisotropic conductive material is not particularly limited as long as the conductive fine particles of the present invention are dispersed in a resin binder. For example, anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive An adhesive, an anisotropic conductive film, an anisotropic conductive sheet, etc. are mentioned.

  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 mixed and dispersed uniformly. For example, a method of using an anisotropic conductive paste, anisotropic conductive ink, anisotropic conductive adhesive, etc., or adding the conductive fine particles of the present invention to an insulating resin binder and mixing them uniformly. After preparing the conductive composition, the conductive composition is uniformly dissolved (dispersed) in an organic solvent as necessary, or heated and melted to release a release material such as release paper or release film. Applying to the mold processing surface so as to have a predetermined film thickness, and performing drying or cooling as necessary, for example, an anisotropic conductive film, an anisotropic conductive sheet, etc. Depending on the type of anisotropic conductive material to be produced, Manufacturing methods may Taking. Further, the insulating resin binder and the conductive fine particles of the present invention may be used separately without being mixed to form an anisotropic conductive material.

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

  In addition to the insulating resin binder and the conductive fine particles of the present invention, the anisotropic conductive material of the present invention includes, for example, a bulking agent, a softening agent, etc. 1 type of various additives such as additives (plasticizers), tackifiers, antioxidants (anti-aging agents), heat stabilizers, light stabilizers, UV absorbers, colorants, flame retardants, organic solvents, etc. Or 2 or more types may be used together.

(Function)
Since the conductive fine particles of the present invention are composed of a mixture of two kinds of conductive fine particles having different compressive properties, they can be connected well at a portion where the electrode interval is wide or a portion where the electrode interval is narrow. The conductive fine particles 1 easily remove the binder resin from the binder resin that flows intensively between the wide electrode terminals due to its hard characteristics, and connect the electrode terminals well.

  On the other hand, in the narrow part of the electrode, the conductive fine particles 2 are easily compressed due to the flexible characteristics and are not broken to the extent that the restoring force disappears due to the characteristics with a large breaking strain, so that the electrode terminals are well connected. Further, since the conductive fine particles 1 have a small fracture strain in a narrow part, they are easily broken during the compression process, and no restoring force that adversely affects the connection between terminals is generated.

  For this reason, the anisotropic conductive material using the conductive fine particles of the present invention has a wide applicable pressure range, and when connecting between electrode terminals, variation in bump height, flatness of the substrate, etc. It is possible to select an appropriate pressure condition according to the above.

  Since the conductive fine particles of the present invention have the above-described configuration, even when the distance between the electrode terminals to be connected is wide or narrow, it is possible to connect well and obtain an excellent connection reliability. Further, the anisotropic conductive material using the conductive fine particles can be connected well even when the distance between the electrode terminals to be connected is wide and excellent in connection reliability.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

(Example 1)
(Preparation of conductive fine particles 1)
After mixing 5 g of 0.8 μm styrene particles as seed particles, 500 g of ion-exchanged water and 100 g of a 5 wt% polyvinyl alcohol aqueous solution and applying ultrasonic waves to disperse, the mixture was placed in a separable flask and stirred uniformly.
Next, a separable flask was obtained by dividing an emulsion prepared from 160 g of divinylbenzene from 1035 g of ion-exchanged water to which 12 g of benzoyl peroxide as an oil-soluble polymerization initiator, 9 g of lauryl sulfate triethanolamine and 118 g of ethanol were added. In addition, the seed particles were allowed to absorb the monomer by stirring for 12 hours.
Thereafter, 500 g of a 5% by weight aqueous polyvinyl alcohol solution was added, nitrogen gas was introduced, and the mixture was reacted at 90 ° C. for 9 hours to obtain resin particles having an average particle diameter of 4 μm.
Electroless nickel plating was performed on the surface of the obtained resin particles to form a nickel plating layer of about 0.08 μm. Further, substitution gold plating was performed, and a gold plating layer of about 0.03 μm was formed on the nickel plating layer to obtain conductive fine particles 1.
The obtained conductive fine particles 1 had a 10% K value of 8938 (N / mm ² ) and a fracture strain of 43%. The right side of the above formula (1) was 5742 (μm) ^−7/10 , and the conductive fine particles 1 had a 10% K value satisfying the above formula (1). A chart in which the compression characteristics of the conductive fine particles 1 are measured is shown in FIG.

(Preparation of conductive fine particles 2)
In the production of the conductive fine particles 1, the conductive fine particles 2 were obtained in the same manner except that 132 g of polytetramethylene glycol diacrylate and 28 g of divinylbenzene were used instead of using 160 g of divinylbenzene.
The obtained conductive fine particles 2 had a 10% K value of 4488 (N / mm ² ) and a fracture strain of 57%. The right side of the above formula (2) was 4874 (μm) ^−3/5 , and the conductive fine particles 2 had a 10% K value satisfying the above formula (2). A chart showing the compression characteristics of the conductive fine particles 2 is shown in FIG.

  The obtained conductive fine particles 1 and the obtained conductive fine particles 2 were mixed with the same weight to obtain conductive fine particles.

(Example 2)
Two types of resin particles obtained in the same manner as in Example 1 were used. When electroless nickel plating was performed on the surfaces of the two types of resin particles obtained, nickel particles having a particle size of about 0.05 μm were added to form a nickel plating layer of about 0.08 μm on the surface of the resin particles. . Further, substitution gold plating was performed to form a gold plating layer having a thickness of about 0.03 μm to obtain conductive fine particles 1 and conductive fine particles 2 having protrusions. Protrusions having a height of 0.05 μm derived from nickel particles were formed on the surfaces of the obtained conductive fine particles 1 and conductive fine particles 2.
The obtained conductive fine particles 1 and the obtained conductive fine particles 2 were mixed with the same weight to obtain conductive fine particles.

(Comparative Example 1)
Only the conductive fine particles 1 obtained in Example 1 were used to form conductive fine particles.

(Comparative Example 2)
Only the conductive fine particles 2 obtained in Example 1 were used to form conductive fine particles.

(Example 3)
Conductivity obtained in Example 1 was mixed with 50% by weight of phenoxy resin (dissolved in a mixed solvent of toluene / ethyl acetate = 50/50), 40% by weight of epoxy resin, and 10% by weight of latent curing agent. Fine particles were dispersed so as to be 10% by weight, applied to a PET film using a coating apparatus, and ACF (anisotropic conductive film) was produced by hot air drying.
Using the obtained ACF, an IC chip having a stud bump with a height of 20 μm was mounted on the wiring board by thermocompression bonding at 180 ° C. for 30 seconds.
The mounted IC chip was subjected to a PCT test (maintained in a high-temperature and high-humidity tank at 121 ° C., 0.2026 MPa, 100% humidity for 1000 hours), and the time until continuity was lost was measured. The evaluation results are shown in Table 1.

Example 4
An ACF was prepared in the same manner as in Example 3 except that the conductive fine particles obtained in Example 2 were used, and a PCT test was similarly performed to measure the time until continuity was lost. The evaluation results are shown in Table 1.

(Comparative Example 3)
An ACF was prepared in the same manner as in Example 3 except that the conductive fine particles obtained in Comparative Example 1 were used, and a PCT test was similarly performed to measure the time until continuity was lost. The evaluation results are shown in Table 1.

(Comparative Example 4)
An ACF was produced in the same manner as in Example 3 except that the conductive fine particles obtained in Comparative Example 2 were used, and a PCT test was similarly conducted to measure the time until continuity was lost. The evaluation results are shown in Table 1.

From Table 1, ACF (anisotropic conductive film) of Example 3 and Example 4 using the conductive fine particles obtained in Example 1 and Example 2 continued to be conductive for a long time.
On the other hand, in Comparative Example 3 in which the conductive fine particles 1 were used alone and in Comparative Example 4 in which the conductive fine particles 2 were used alone, conduction was lost in a short time.
From this, it can be seen that the conductive fine particles 1 and 2 contribute to conduction separately due to their compression characteristics.

  According to the present invention, conductive fine particles that can be connected well even when the distance between electrode terminals to be connected is wide and excellent in connection reliability, and an anisotropic conductive material using the conductive fine particles Can provide.

It is explanatory drawing of how to obtain | require 10% K value and fracture | rupture distortion in this invention.

Explanation of symbols

  1 Inflection point

Claims (3)

The conductive fine particles in which the conductive metal layer is formed on the surface of the resin particles are a mixture of the conductive fine particles 1 and the conductive fine particles 2 having different 10% K value and fracture strain.
The conductive fine particles 1 have a 10% K value satisfying the following formula (1), and the fracture strain is less than 50%.
The conductive fine particles 2 have a 10% K value satisfying the following formula (2), and the fracture strain is 50% or more.
The two kinds of conductive fine particles are contained in the same weight, or any one of the conductive fine particles is contained excessively within a range of 20% by weight or less than the other conductive fine particles. Fine particles.
10% K value of conductive fine particles 1: K ₁ (N / mm ² )>
15680R ₁ (μm) ^-7/10 (1)
(R ₁ : particle diameter of conductive fine particles 1)
10% K value of conductive fine particles 2: K ₂ (N / mm ² ) <
11530R ₂ (μm) ^-3/5 (2)
(R ₂ : particle size of conductive fine particles 2)   2. The conductive fine particle according to claim 1, wherein at least one of the conductive fine particles is a conductive fine particle having a protrusion having a height of 0.04 [mu] m or more on the surface. 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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