KR102172940B1 - Base material particle, conductive particle, conductive material, and connection structure - Google Patents

Abstract

The present invention provides a substrate particle capable of reducing the connection resistance and suppressing the occurrence of cracks in the electrode when the electrodes are electrically connected using conductive particles having a conductive layer formed on the surface thereof. The substrate particle 11 according to the present invention is used to obtain a conductive particle 1 having a conductive layer 2 formed thereon with a conductive layer 2 on the surface thereof. The substrate particles 11 are core shell particles including a core 12 and a shell 13 disposed on the surface of the core 12. The compression recovery rate of the substrate particles 11 is 50% or more. The compressive elastic modulus when the substrate particles 11 are compressed by 10% is 3000 N/mm ² or more and less than 6000 N/mm ² . The ratio of the load value when the substrate particles 1 is compressed by 30% to the load value when compressed by 10% is 3 or less.

Description

Substrate particle, conductive particle, conductive material, and connection structure {BASE MATERIAL PARTICLE, CONDUCTIVE PARTICLE, CONDUCTIVE MATERIAL, AND CONNECTION STRUCTURE}

The present invention relates to a substrate particle used in order to obtain an electroconductive particle having a conductive layer formed on a surface thereof and having the electroconductive layer. Further, the present invention relates to a conductive particle, a conductive material, and a connection structure using the substrate particle.

Anisotropic conductive materials such as anisotropic conductive paste and anisotropic conductive film are widely known. In the anisotropic conductive material, conductive particles are dispersed in a binder resin.

The anisotropic conductive material is used to electrically connect electrodes of various members to be connected, such as a flexible printed circuit board (FPC), a glass substrate, a glass epoxy substrate, and a semiconductor chip, to obtain a connection structure. Moreover, as said electroconductive particle, electroconductive particle which has a substrate particle and a conductive layer arrange|positioned on the surface of the said substrate particle may be used.

As an example of the substrate particle used for the electroconductive particle, in the following Patent Document 1, the shell is an inorganic compound (A), the core is an organic polymer (b), and the core is an organic polymer particle (B) covered with a shell. ) (Substrate particle) is disclosed. In addition, in Patent Document 1, the conductive particles in which the organic polymer particles (B) are covered with the conductive metal (C) are also disclosed.

In addition, Patent Document 2 below discloses an organic inorganic composite particle (substrate particle) obtained by hydrolyzing and polycondensing a polyfunctional silane compound having a polymerizable unsaturated group in the presence of a surfactant. In Patent Document 2, the polyfunctional silane compound is a first silicone compound containing at least one radical polymerizable group selected from compounds represented by the following formula (X) and derivatives thereof.

In the formula (X), R1 represents a hydrogen atom or a methyl group, R2 represents a divalent organic group having 1 to 20 carbon atoms which may have a substituent, R3 represents an alkyl group or a phenyl group having 1 to 5 carbon atoms, and R4 represents hydrogen At least one monovalent group selected from the group consisting of an atom, an alkyl group having 1 to 5 carbon atoms, and an acyl group having 2 to 5 carbon atoms is shown.

Further, in Patent Document 3 below, core shell particles in which the surfaces of hard particles are coated with a soft polymer layer are disclosed. Suitable examples of the hard particles include metal particles such as nickel, glass fibers, inorganic particles such as alumina and silica, and cured resin particles such as cured benzoguanamine. In Patent Document 3, it is described that by providing a soft polymeric polymer layer, the contact area can be increased and reliability can be improved.

Japanese Patent Publication No. 2006-156068 Japanese Patent Publication No. 2000-204119 Japanese Patent Publication No. Hei 7-140481

In recent years, the spacing between electrodes connected by electroconductive particles is narrow, and the electrode area tends to decrease, and thus electroconductive particles capable of connecting with a lower resistance are required. In addition, for the substrate material, in order to increase the flexibility, a relatively soft resin film substrate is used instead of a glass substrate, and conductive particles that do not damage the soft substrate and the electrode are required.

When electroconductive particles in which the surface of the flexible substrate particle is covered with a conductive layer are used, the contact area between the electrode and the electroconductive particle increases, and the electroconductive particle is less likely to cause damage to the electrode. However, if a simple flexible substrate particle is used, the binder resin between the electrode and the conductive particle cannot be sufficiently removed when connecting between the electrodes, so that the resin is stuck between the electrode and the conductive particle, or the conductive layer and the oxide film on the electrode surface are There is a problem that it cannot penetrate sufficiently, and as a result, the connection resistance becomes high. This problem also occurs when the core is covered by a shell as the substrate particle, and the core shell particle is a relatively flexible organic shell.

On the other hand, in the case of using conductive particles in which the surfaces of relatively hard substrate particles such as silica are coated with a conductive layer, the exclusion property of the binder resin and the penetrability of the oxide film on the conductive layer and the electrode surface are improved. However, since the conductive particles are not sufficiently deformed, there is a problem that the contact area between the electrode and the conductive particles is not sufficiently large, and the connection resistance is not sufficiently lowered. In addition, depending on the crimp conditions at the time of connection between the electrodes, the electroconductive particle may damage the electrode, causing cracks in the electrode.

In addition, electroconductive particles having insufficient resilience (recovery rate) after compression adversely affect connection reliability. There is a problem that connection failure is liable to occur when a connection structure in which electrodes are connected by using conductive particles having poor resilience after compression is stored under high temperature conditions and high humidity conditions.

It is an object of the present invention to provide substrate particles capable of lowering connection resistance and suppressing the occurrence of cracks in electrodes when electrically connected between electrodes using conductive particles having a conductive layer formed on the surface thereof. To provide. Further, an object of the present invention is to provide a conductive particle, a conductive material, and a connection structure using the substrate particle.

According to a broad aspect of the present invention, a core shell having a core and a shell disposed on the surface of the core, as a substrate particle formed on a surface of a conductive layer and used to obtain conductive particles having the conductive layer It is a particle, and the compressive recovery rate is 50% or more, and the compressive elastic modulus at the time of 10% compression is 3000 N/mm ² or more and less than 6000 N/mm ² , and the load value at 10% compression of the load value at 30% compression A base particle having a ratio of 3 or less is provided.

In one particular aspect of the substrate particles according to the present invention, the core is an organic core and the shell is an inorganic shell.

In one particular aspect of the substrate particles according to the present invention, the thickness of the shell is 100 nm or more and 5 μm or less.

It is preferable that the compressive elastic modulus when the said substrate particle is compressed by 30% is 3000 N/mm ² or less. It is preferable that the ratio of the load value when the substrate particles are compressed by 40% to the load value when the substrate particles are compressed by 10% is 6 or less. It is preferable that the fracture strain of the substrate particles is 10% or more and 30% or less.

According to a broad aspect of the present invention, electroconductive particles are provided that include the above-described substrate particles and a conductive layer disposed on the surface of the substrate particles.

In a specific aspect of the electroconductive particle according to the present invention, the electroconductive particle further includes an insulating material disposed on the outer surface of the conductive layer.

In one specific aspect of the electroconductive particle according to the present invention, the electroconductive particle has a protrusion on the outer surface of the electroconductive layer.

According to a broad aspect of the present invention, there is provided a conductive material comprising conductive particles and a binder resin, wherein the conductive particles include the above-described substrate particles and a conductive layer disposed on the surface of the substrate particles.

According to a broad aspect of the present invention, a first connection object member having a first electrode on its surface, a second connection object member having a second electrode on its surface, the first connection object member and the second connection object member are provided. A connecting portion to be connected is provided, the connecting portion is formed of conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin, and the conductive particles are the aforementioned substrate particles and the substrate particles. There is provided a connection structure comprising a conductive layer disposed on the surface of the cell, wherein the first electrode and the second electrode are electrically connected by the conductive particles.

The substrate particle according to the present invention is a core-shell particle having a core and a shell disposed on the surface of the core, and the substrate particle according to the present invention has a compression recovery rate of 50% or more, and when compressed by 10%. Since the compressive elastic modulus is 3000 N/mm ² or more and less than 6000 N/mm ² , and the ratio of the load value when compressed by 30% to the load value when compressed by 10% is 3 or less, conductive particles having a conductive layer formed on the surface are When the electrodes are electrically connected by using, the connection resistance can be lowered and the occurrence of cracks in the electrodes can be suppressed.

1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention.
2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention.
3 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention.
4 is a front cross-sectional view schematically showing a connection structure using electroconductive particles according to the first embodiment of the present invention.

Hereinafter, the details of the present invention will be described.

(Substrate particle)

The substrate particle according to the present invention has a conductive layer formed on its surface, and is used to obtain conductive particles having the conductive layer. That is, the substrate particle according to the present invention is a substrate particle for electroconductive particles. The substrate particle according to the present invention includes a core and a shell disposed on the surface of the core. The substrate particles according to the present invention are core shell particles.

The compression recovery rate of the substrate particles according to the present invention is 50% or more. The compressive elastic modulus (10% K value) when the substrate particles according to the present invention are compressed by 10% is 3000 N/mm ² or more and less than 6000 N/mm ² . The ratio (30% load value/10% load value) of the load value (30% load value) when the substrate particles according to the present invention are compressed by 30% to the load value (10% load value) when compressed by 10% Is 3 or less.

The compression recovery rate of the substrate particles according to the present invention is high, and the substrate particles have an appropriate hardness at the initial stage of compression. In addition, in the substrate particle according to the present invention, the hardness changes in a compressed stage to some extent, and thus more flexible properties are expressed. For this reason, deformation in the middle period (30% compression deformation time) occurs as a load value that does not differ much from the load value at the initial deformation time point (10% compression deformation time point). As a result, when the electrodes are electrically connected using conductive particles having a conductive layer formed on the surface of the substrate particles, the binder resin is sufficiently excluded by the initially developed hardness, and the conductive layer or the oxide film on the electrode surface It is possible to penetrate sufficiently, and it is possible to sufficiently increase the contact area between the electrode and the conductive particles due to the flexibility of the medium term. For this reason, connection resistance between electrodes can be made low, and connection reliability between electrodes can be improved. For example, even if a connection structure electrically connected between electrodes by electroconductive particles is left for a long time under a high temperature condition and a high humidity condition, the connection resistance is difficult to increase and connection failure is less likely to occur. Further, due to the flexibility of the medium term, damage to the electrode and the substrate caused by the electroconductive particle can also be suppressed. Therefore, by using the substrate particles according to the present invention, it is possible to suppress connection failure due to the occurrence of cracks in the electrode.

The compression recovery rate of the substrate particles is 50% or more. The compression recovery rate is preferably 52% or more. When the compression recovery rate is equal to or greater than the lower limit, electroconductive particles are sufficiently followed and easily deformed in response to variations in the spacing between electrodes. For this reason, it becomes difficult to generate a connection failure between electrodes.

The compression recovery rate can be measured as follows.

Spray substrate particles on the sample stand. For one sprayed substrate particle, a load (reverse load value) is applied using a micro-compression tester until the substrate particles are compressively deformed by 30% in the center direction of the substrate particles. After that, the load is removed up to the original load value (0.40 mN). By measuring the load-compression displacement in the meantime, the compression recovery rate can be obtained from the following equation. In addition, the load speed is set to 0.33 mN/sec. As the micro-compression tester, for example, "Fischer Scope H-100" manufactured by Fischer is used.

Compression recovery rate (%)=[(L1-L2)/L1]×100

L1: Compression displacement from the origin load value when applying a load to the reverse load value

L2: Load removal displacement from the reverse load value when the load is released to the origin load value

The 10% K value is 3000 N/mm ² or more and less than 6000 N/mm ² . The 10% K value is preferably 3200 N/mm ² or more, more preferably 3500 N/mm ² or more, preferably 5800 N/mm ² or less, and more preferably 5500 N/mm ² or less. If the 10% K value is equal to or greater than the lower limit, the binder resin is effectively removed and effectively penetrates the conductive layer or the oxide film on the electrode surface, so that the connection resistance between the electrodes is effectively lowered. When the 10% K value is less than or equal to the upper limit, it becomes more difficult to generate cracks in the electrode. If the 10% K value is 3500 N/mm ² or more, the connection resistance is effectively lowered.

The ratio of the 30% load value to the 10% load value (30% load value/10% load value) is 3.0 or less. The ratio (30% load value/10% load value) is more preferably 2.9 or less. If the ratio (30% load value/10% load value) is less than or equal to the upper limit, the contact area between the electrode and the conductive particles becomes sufficiently large, the connection resistance between the electrodes is effectively lowered, and the connection reliability between the electrodes is further increased. The ratio (30% load value/10% load value) is preferably 1.5 or more.

Compression modulus (30% K value) when the 30% compressive deformation of the base particles is preferably 3000N / mm ^2, more preferably at most 2500N / mm ² or less. When the 30% K value is less than or equal to the above upper limit, the contact area between the conductive particles and the electrode is further increased, and cracks are more difficult to occur in the electrode. The 30% K value is preferably 500 N/mm ² or more. If the 10% K value is 3000 N/mm ² or less, it becomes more difficult to generate cracks in the electrode. If the 10% K value is 2500 N/mm ² or less, it becomes difficult to generate cracks in the electrode considerably.

The ratio (40% load value/10% load value) to the load value (10% load value) when compressing 10% of the load value (40% load value) when the substrate particles are compressed by 40% is preferably It is preferably 6 or less, more preferably 5 or less. When the ratio (40% load value/10% load value) is equal to or less than the upper limit, the design width for enhancing connection reliability is further widened. When the ratio (40% load value/10% load value) is less than or equal to the upper limit, the connection resistance is effectively lowered. The ratio (40% load value/10% load value) is preferably 2 or more.

The load value and the compressive elastic modulus (10% K value and 30% K value) of the substrate particles can be measured as follows.

Using a micro-compression tester, the base particles are compressed under the conditions of 25°C, a compression speed of 0.3 mN/sec, and a maximum test load of 20 mN, at the end face of the smooth indenter of a cylinder (diameter 100 μm, made of diamond). The load value (N) and compression displacement (mm) at this time are measured. From the obtained measured values, the compressive modulus can be determined by the following equation. As the micro-compression tester, for example, "Fischer Scope H-100" manufactured by Fischer is used.

10% K value or 30% K value (N/mm ² )=(3/2 ^1/2 )·F·S ^-3/2 ·R ^-1/2

F: Load value (N) when the base particles are compressed by 10% or 30%

S: Compression displacement (mm) when the substrate particles are compressed by 10% or 30%

R: radius of the substrate particle (mm)

The compressive modulus is a universal and quantitative representation of the hardness of the substrate particles. By using the compression modulus, the hardness of the substrate particles can be quantitatively and uniquely expressed.

The fracture strain of the substrate particles is 10% or more and 30% or less. When evaluating the compression behavior of the particles, it is observed that the amount of displacement changes significantly at a certain constant load value. The load value at this change point is the breaking load value, and the displacement amount is the breaking displacement. The ratio of the fracture displacement and the particle diameter before compression (destruction displacement/particle diameter before compression) x 100 is defined as the fracture strain (%). For example, when the fracture behavior is observed when the particle diameter before compression is 5 µm when the displacement amount is 1 µm, the fracture strain is calculated as 20%. In the case of core-shell particles, the fracture behavior of the shell is generally observed at the beginning of the displacement. If the fracture strain is more than the above lower limit, the exclusion property of the binder resin and the oxide film penetrability of the conductive layer and the electrode are further increased, and the connection resistance is further lowered. When the fracture strain is less than or equal to the upper limit, the flexibility in the medium term is expressed, the contact area between the electroconductive particle and the electrode is further increased, and the connection resistance is further lowered.

The fracture deformation can be evaluated from the measurement of the compressive elastic modulus described above, and can be measured by reading the displacement amount of the discontinuous point of the compression displacement curve.

The particle diameter of the core is preferably 0.5 µm or more, more preferably 1 µm or more, preferably 500 µm or less, more preferably 100 µm or less, still more preferably 50 µm or less, particularly preferably 20 µm Hereinafter, most preferably, it is 10 micrometers or less. If the particle diameter of the core is greater than or equal to the lower limit and less than or equal to the upper limit, 10% K value, 30% K value, the ratio (30% load value/10% load value) and the ratio (40% load value/10% load value) It is easy for) to represent a suitable value, and the substrate particle can be suitably used for the use of the electroconductive particle. For example, if the particle diameter of the core is greater than or equal to the lower limit and less than or equal to the upper limit, the contact area between the conductive particles and the electrode becomes sufficiently large when the electrodes are connected by using the conductive particles, and aggregated when forming the conductive layer. It becomes difficult to form electroconductive particle. Further, the gap between the electrodes connected via the conductive particles does not become too large, and the conductive layer becomes difficult to peel off from the surface of the substrate particles.

The particle diameter of the core means a diameter when the core is in a spherical shape, and when the core has a shape other than a spherical shape, it means a diameter assuming that it is a spherical sphere equivalent to its volume. In addition, the particle diameter of a core means the average particle diameter which measured a core by an arbitrary particle diameter measuring apparatus. For example, a particle size distribution measuring device using principles such as laser light scattering, change in electrical resistance value, and image analysis after imaging can be used.

The substrate particle has a core and a shell disposed on the surface of the core, and is a core shell particle. The compression recovery rate, 10% K value, 30% K value, the ratio (30% load value/10% load value) and the ratio (40% load value/10% load value) of the core shell particles satisfy the above-described values. By doing so, connection resistance between electrodes can be made low, and connection reliability between electrodes can be improved.

It is preferable that the core is an organic core. It is preferable that the shell is an inorganic shell. It is preferable that the core is an organic core and the shell is an inorganic shell. The substrate particle includes an organic core and an inorganic shell disposed on the surface of the organic core, and is preferably a core-shell particle, and is preferably a core-shell type organic-inorganic hybrid particle. When the core is an organic core or the shell is an inorganic shell, compression recovery rate, 10% K value, 30% K value, the ratio (30% load value/10% load value) and the ratio (40% load value/10 It is easy for the% load value) to satisfy the above-described value.

It is preferable that the said core is an organic core, and it is preferable that it is an organic particle. Since the organic core and the organic particles are relatively flexible compared to the inorganic core and the inorganic particles, as a result of forming a shell on the surface of the relatively flexible organic core, the compression recovery rate, the ratio (30% load value/10% load value) And it is easy to satisfy the above ratio (40% load value/10% load value).

As a material for forming the organic core, various organic substances are suitably used. As a material for forming the organic core, for example, polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polypropylene, polyisobutylene, and polybutadiene; Acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Polyalkylene terephthalate, polysulfone, polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, and various polymerizable monomers having an ethylenically unsaturated group. Polymers obtained by polymerizing one or two or more types are used. By polymerizing one or two or more of various polymerizable monomers having an ethylenically unsaturated group, it is easy to design and synthesize base particles having physical properties upon compression suitable for a conductive material.

When the organic core is obtained by polymerizing a monomer having an ethylenically unsaturated group, examples of the monomer having an ethylenically unsaturated group include a non-crosslinkable monomer and a crosslinkable monomer.

Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; Carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; Methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth) Alkyl (meth)acrylates such as acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; Oxygen atom-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate; Nitrile-containing monomers such as (meth)acrylonitrile; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; Acid vinyl esters such as vinyl acetate, vinyl butyrate, vinyl laurate, and vinyl stearate; Unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; And halogen-containing monomers such as trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene.

As the crosslinkable monomer, for example, tetramethylolmethane tetra (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane di (meth) acrylate, trimethylol propane tri (meth) acrylic Rate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, glycerol tri (meth) acrylate, glycerol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylic Polyfunctional (meth)acrylates such as acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; Triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallylphthalate, diallylacrylamide, diallyl ether, γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene And silane-containing monomers such as vinyl trimethoxysilane.

The organic core can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerization by swelling a monomer together with a radical polymerization initiator using non-crosslinked seed particles.

In particular, for the core optimal for the present invention, the compressive elastic modulus (10% K value) when the core is compressed by 10% is preferably 1500 N/mm ² or more and 4000 N/mm ² or less, more preferably 2000 N/mm ² or more and 3500N/mm ² or less. The compression recovery rate of the core is preferably 50% or more, more preferably 55% or more. If the core satisfies the 10% K value or satisfies the compressive elastic modulus, the 10% K value of the base particles coated with the core with an inorganic shell, the ratio (10% load value/30% load value), And the compression recovery rate can be easily controlled within a suitable range.

The method of designing the physical properties of the core within the above-described range is not limited, for example, when obtained by polymerizing a monomer having an ethylenically unsaturated group, ethylene between the (meth)acryloyl groups as a compound for forming the core A method of using 50% by weight or more of a crosslinkable monomer having a flexible structure such as a glycol structure or a methylene structure is mentioned. Examples of such crosslinkable monomers include (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, (poly) tetramethylene di (meth) acrylate and 1,4-butanediol. Di(meth)acrylate, etc. are mentioned. In a core obtained by using 70% by weight or more of a crosslinkable monomer having a rigid structure such as divinylbenzene, a 10% K value tends to be high. In addition, a silane coupling agent such as vinyl trimethoxysilane or (meth)acryloxytrimethoxysilane is polycondensed by a sol-gel method to form granulated particles, and then a monomer having an ethylenically unsaturated group is absorbed and then polymerized. It is possible to design the physical properties of the core with optimum values even in the obtained particles. The material constituting the core may include not only an organic compound but also a compound having a silicon atom. The ratio of the content of carbon atoms in the core to the content of silicon atoms (content of carbon atoms/content of silicon atoms) is preferably 1.2 or more. A core having the ratio (content of carbon atoms/content of silicon atoms) of 1.2 or more corresponds to an organic core.

From the viewpoint of suppressing the deformation of the core during the formation of the shell and the use of the substrate particles, the decomposition temperature of the core preferably exceeds 200°C, more preferably exceeds 250°C, and even more preferably Exceeds 300°C. The decomposition temperature of the core may exceed 400°C, may exceed 500°C, may exceed 600°C, or may exceed 800°C.

The substrate particles are core shell particles. The shell is disposed on the surface of the core. It is preferable that the shell covers the surface of the core. It is preferable that the shell is an inorganic shell.

It is preferable that the said inorganic shell contains 50 weight% or more of silicon atoms, and in this case, the said inorganic shell is an inorganic shell containing a silicon atom as a main component. The inorganic shell may contain a carbon atom, but even if it contains a carbon atom, if a silicon atom is the main component, it is referred to as an inorganic shell.

It is preferable that the said inorganic shell is formed by making a metal alkoxide into a shell-like material on the surface of the said core by a sol-gel method, and then firing the shell-like material. In the sol-gel method, it is easy to arrange a shell-like object on the surface of the core. In the case of performing the firing, in the substrate particles, after firing, the core remains without being removed by volatilization or the like. The substrate particle is provided with the core after firing. Further, for example, if the core is removed by volatilization or the like after firing, the 10% K value is considerably lowered.

As a specific method of the sol-gel method, a method of performing a surfactant sol reaction by coexisting an inorganic monomer such as tetraethoxysilane in a dispersion containing a core, a solvent such as water or alcohol, a surfactant, and a catalyst such as an aqueous ammonia solution, And a method of performing a sol-gel reaction with a solvent such as water or alcohol and an inorganic monomer such as tetraethoxysilane coexisted with an aqueous ammonia solution, and then hetero-aggregating the sol-gel reactant to the core. In the sol-gel method, the metal alkoxide is preferably hydrolyzed and polycondensed.

In the sol-gel method, it is preferable to use a surfactant. In the presence of a surfactant, it is preferable to make the metal alkoxide into a shell-like material by a sol-gel method. The surfactant is not particularly limited. The surfactant is appropriately selected and used so as to form a good shell shape. Examples of the surfactant include cationic surfactants, anionic surfactants, and nonionic surfactants. Among them, a cationic surfactant is preferred from the viewpoint of being able to form a good inorganic shell.

Examples of the cationic surfactant include quaternary ammonium salts and quaternary phosphonium salts. As a specific example of the cationic surfactant, hexadecyl ammonium bromide, etc. are mentioned.

On the surface of the core, in order to form the inorganic shell, the shell-shaped material is preferably fired. Depending on the firing conditions, the degree of crosslinking in the inorganic shell can be adjusted. In addition, by performing firing, the 10% K value and 30% K value of the substrate particles exhibit more suitable values than when not firing. In particular, by increasing the degree of crosslinking, the 10% K value becomes sufficiently high.

It is preferable that the said inorganic shell is formed by making a metal alkoxide into a shell-like object by a sol-gel method on the surface of the said core, and firing the said shell-like object at 100 degreeC or more (baking temperature). The firing temperature is more preferably 150°C or higher, and still more preferably 200°C or higher. If the firing temperature is higher than the lower limit, the degree of crosslinking in the inorganic shell becomes more suitable, and the 10% K value, 30% K value, the ratio (30% load value/10% load value) and the ratio (40% load value) /10% load value) shows a more suitable value, and the substrate particle can be used more appropriately for the use of the electroconductive particle.

The inorganic shell is preferably formed on the surface of the core by making a metal alkoxide into a shell-like material by a sol-gel method, and then firing the shell-like material at a decomposition temperature of the organic core or less (firing temperature). The firing temperature is preferably 10°C or more lower than the decomposition temperature of the core, and more preferably 50°C or more lower than the decomposition temperature of the core. Further, the firing temperature is preferably 500°C or less, more preferably 300°C or less, and still more preferably 200°C or less. When the firing temperature is less than or equal to the upper limit, thermal deterioration and deformation of the core can be suppressed, and the 10% K value, 30% K value, the ratio (30% load value/10% load value) and the ratio (40 A substrate particle having a good value (% load value/10% load value) is obtained.

Examples of the metal alkoxide include silane alkoxide, titanium alkoxide, zirconium alkoxide and aluminum alkoxide. From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a silane alkoxide, titanium alkoxide, zirconium alkoxide or aluminum alkoxide, more preferably a silane alkoxide, titanium alkoxide or zirconium alkoxide, It is more preferable that it is a silane alkoxide. From the viewpoint of forming a good inorganic shell, the metal atom in the metal alkoxide is preferably a silicon atom, a titanium atom, a zirconium atom or an aluminum atom, more preferably a silicon atom, a titanium atom, or a zirconium atom, and a silicon atom It is more preferable to be. Only one type of the metal alkoxide may be used, or two or more types may be used in combination.

From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a metal alkoxide represented by the following formula (1).

M(R1) _n (OR2) _4-n ... (One)

In the formula (1), M is a silicon atom, a titanium atom, or a zirconium atom, and R1 is a phenyl group, an alkyl group having 1 to 30 carbon atoms, an organic group having 1 to 30 carbon atoms having a polymerizable double bond, or an epoxy group having 1 to carbon atoms. Represents an organic group of 30, R2 represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 0 to 2. When n is 2, a plurality of R1s may be the same or different. A plurality of R2 may be the same or different.

From the viewpoint of forming a good inorganic shell, the metal alkoxide is preferably a silane alkoxide represented by the following formula (1A).

Si(R1) _n (OR2) _4-n ... (1A)

In the formula (1A), R1 represents a phenyl group, an alkyl group having 1 to 30 carbon atoms, an organic group having 1 to 30 carbon atoms having a polymerizable double bond, or an organic group having 1 to 30 carbon atoms having an epoxy group, and R2 is 1 to 6 carbon atoms. Represents an alkyl group of, and n represents an integer of 0 to 2. When n is 2, a plurality of R1s may be the same or different. A plurality of R2 may be the same or different. In order to effectively increase the content of the silicon atom contained in the shell, n in the formula (1A) preferably represents 0 or 1, and more preferably represents 0. When the content of the silicon atom contained in the shell is high, the effect of the present invention is more excellent.

When R1 is an alkyl group having 1 to 30 carbon atoms, specific examples of R1 include methyl group, ethyl group, propyl group, isopropyl group, isobutyl group, n-hexyl group, cyclohexyl group, n-octyl group, and n-decyl group. And the like. The number of carbon atoms in this alkyl group is preferably 10 or less, more preferably 6 or less. In addition, a cycloalkyl group is contained in an alkyl group.

Examples of the polymerizable double bond include a carbon-carbon double bond. When R1 is an organic group having 1 to 30 carbon atoms having a polymerizable double bond, specific examples of R1 include a vinyl group, an allyl group, an isopropenyl group and a 3-(meth)acryloxyalkyl group. Examples of the (meth)acryloxyalkyl group include a (meth)acryloxymethyl group, a (meth)acryloxyethyl group, and a (meth)acryloxypropyl group. The number of carbon atoms of the organic group having 1 to 30 carbon atoms having a polymerizable double bond is preferably 2 or more, preferably 30 or less, and more preferably 10 or less. The "(meth)acryloxy" means methacryloxy or acryloxy.

When R1 is an organic group having 1 to 30 carbon atoms having an epoxy group, specific examples of R1 include 1,2-epoxyethyl group, 1,2-epoxypropyl group, 2,3-epoxypropyl group, 3,4-epoxybutyl group, 3-glycidoxypropyl group and 2-(3,4-epoxycyclohexyl)ethyl group, etc. are mentioned. The number of carbon atoms of the organic group having 1 to 30 carbon atoms having the epoxy group is preferably 8 or less, more preferably 6 or less. Further, the organic group having 1 to 30 carbon atoms having the epoxy group is a group containing an oxygen atom derived from an epoxy group in addition to a carbon atom and a hydrogen atom.

Specific examples of R2 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group. In order to effectively increase the content of the silicon atom contained in the shell, it is preferable that R2 represents a methyl group or an ethyl group.

Specific examples of the silane alkoxide include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isopropyltrimethoxysilane, iso Butyltrimethoxysilane, cyclohexyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane and diiso And propyl dimethoxysilane. Silane alkoxides other than these can also be used.

In order to effectively increase the content of silicon atoms contained in the shell, it is preferable to use tetramethoxysilane or tetraethoxysilane as the material of the shell. In 100% by weight of the material of the shell, the total content of tetramethoxysilane and tetraethoxysilane is preferably 50% by weight or more (the total amount may be). In 100% by weight of the shell, the total content of the skeleton derived from tetramethoxysilane and the skeleton derived from tetraethoxysilane is preferably 50% by weight or more (the total amount may be).

Specific examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, and the like. Titanium alkoxides other than these can also be used.

Specific examples of the zirconium alkoxide include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetrabutoxide, and the like. Zirconium alkoxides other than these may be used.

The metal alkoxide preferably includes a metal alkoxide having a structure in which four oxygen atoms are directly bonded to a metal atom. It is preferable that the said metal alkoxide contains a metal alkoxide represented by following formula (1a).

M(OR2) ₄ … (1a)

In the formula (1a), M is a silicon atom, a titanium atom, or a zirconium atom, and R 2 represents an alkyl group having 1 to 6 carbon atoms. A plurality of R2 may be the same or different.

The metal alkoxide preferably includes a silane alkoxide having a structure in which four oxygen atoms are directly bonded to a silicon atom. In this silane alkoxide, in general, four oxygen atoms are bonded to a silicon atom by a single bond. It is preferable that the said metal alkoxide contains a silane alkoxide represented by following formula (1Aa).

Si(OR2) ₄ … (1Aa)

In the formula (1Aa), R2 represents an alkyl group having 1 to 6 carbon atoms. A plurality of R2 may be the same or different.

From the viewpoint of effectively increasing the 10% K value and effectively lowering the 30% K value, the structure in which 4 oxygen atoms are directly bonded to the metal atom out of 100 mol% of the metal alkoxide used to form the inorganic shell Each of a metal alkoxide having, a metal alkoxide represented by the formula (1a), a silane alkoxide having a structure in which four oxygen atoms are directly bonded to the silicon atom, or a silane alkoxide represented by the formula (1Aa) The content is preferably 20 mol% or more, more preferably 40 mol% or more, still more preferably 50 mol% or more, still more preferably 55 mol% or more, particularly preferably 60 mol% or more, 100 mol % Or less. The total amount of the metal alkoxide used to form the inorganic shell is a metal alkoxide having a structure in which four oxygen atoms are directly bonded to the metal atom, a metal alkoxide represented by the formula (1a), and the silicon atom It may be a silane alkoxide having a structure in which four oxygen atoms are directly bonded to each other, or a silane alkoxide represented by the above formula (1Aa).

From the viewpoint of effectively increasing the 10% K value and effectively reducing the 30% K value, in 100% of the total number of metal atoms derived from the metal alkoxide contained in the inorganic shell, 4 oxygen atoms are directly bonded to the metal The ratio of the number of atoms, the ratio of the number of silicon atoms to which the four -O-Si groups are directly bonded and the four oxygen atoms in the four -O-Si groups are directly bonded is preferably 20% or more. , More preferably 40% or more, still more preferably 50% or more, still more preferably 55 mol% or more, particularly preferably 60% or more.

In addition, from the viewpoint of properly increasing the 10% K value and controlling the ratio (30% load value/10% load value) and the ratio (40% load value/10% load value) to an appropriate range, the inorganic In 100% of the total number of metal atoms contained in the shell, the ratio of the number of metal atoms to which four oxygen atoms are directly bonded is preferably 20% or more, more preferably 40% or more, even more preferably 50 % Or more, more preferably 55 mol% or more, particularly preferably 60% or more. From the viewpoint of appropriately increasing the 10% K value and controlling the ratio (30% K value/10% K value) to an appropriate range, the metal alkoxide is a silane alkoxide, and a silicon atom contained in the inorganic shell Of the total number of 100%, the ratio of the number of silicon atoms to which four -O-Si groups are directly bonded and four oxygen atoms in the four -O-Si groups are directly bonded is preferably 20% or more. , More preferably 40% or more, further preferably 50% or more, still more preferably 55% or more, particularly preferably 60% or more.

In addition, the silicon atom to which 4 -O-Si groups are directly bonded and 4 oxygen atoms in the 4 -O-Si groups are directly bonded is, for example, in the structure represented by the following formula (11). It is a silicon atom. Specifically, it is a silicon atom represented by attaching an arrow A in the structure represented by the following formula (11X).

In addition, the oxygen atom in the formula (11) generally forms a siloxane bond with an adjacent silicon atom.

Method of measuring the ratio of the number of silicon atoms to which 4 -O-Si groups are directly bonded and 4 oxygen atoms in the 4 -O-Si groups are directly bonded (the ratio of the number of Q4 (%)) As, for example, using an NMR spectrum analyzer, the peak of Q4 (a silicon atom to which four -O-Si groups are directly bonded and four oxygen atoms in the four -O-Si groups are directly bonded) Area and peak areas of Q1 to Q3 (silicon atoms to which 1 to 3 -O-Si groups are directly bonded and 1 to 3 oxygen atoms in 1 to 3 -O-Si groups are directly bonded) How to compare. By this method, out of 100% of the total number of silicon atoms contained in the inorganic shell, four -O-Si groups are directly bonded, and four oxygen atoms in the four -O-Si groups are directly bonded. The ratio of the number of silicon atoms (the ratio of the number of Q4) can be calculated.

The thickness of the shell is preferably 100 nm or more, more preferably 200 nm or more, preferably 5 μm or less, and more preferably 3 μm or less. When the thickness of the shell is greater than or equal to the lower limit and less than or equal to the upper limit, the 10% K value and the 30% K value represent more suitable values, and the substrate particles can be suitably used for the use of the conductive particles. The thickness of the shell is an average thickness per substrate particle. By controlling the sol-gel method, the thickness of the shell can be controlled.

In the present invention, the thickness of the shell can be obtained from the difference between the average value of the particle diameter of the substrate particle and the core particle diameter. The particle diameter of the substrate particle means the diameter when the substrate particle is in a spherical shape, and when the substrate particle has a shape other than a spherical shape, it means the diameter assuming that the particle size is a spherical sphere equivalent to the volume. For the measurement of the particle diameter, for example, a particle size distribution measuring device using principles such as laser light scattering, change in electric resistance value, and image analysis after imaging can be used.

The aspect ratio of the substrate particles is preferably 2 or less, more preferably 1.5 or less, and still more preferably 1.2 or less. The aspect ratio represents the long diameter/short diameter.

(Conductive particles)

The said electroconductive particle is provided with the above-mentioned base material particle, and the conductive layer arrange|positioned on the surface of the said base material particle.

In Fig. 1, conductive particles according to a first embodiment of the present invention are shown in cross-sectional views.

The electroconductive particle 1 shown in FIG. 1 has the base material particle 11 and the electroconductive layer 2 arrange|positioned on the surface of the base material particle 11. The conductive layer 2 covers the surface of the substrate particle 11. The electroconductive particle 1 is a coated particle in which the surface of the substrate particle 11 is coated with the electroconductive layer 2.

The substrate particle 11 includes a core 12 and a shell 13 disposed on the surface of the core 12. The shell 13 covers the surface of the core 12. The conductive layer 2 is disposed on the surface of the shell 13. The conductive layer 2 covers the surface of the shell 13.

In Fig. 2, electroconductive particles according to a second embodiment of the present invention are shown in cross-sectional views.

The electroconductive particle 21 shown in FIG. 2 has the base material particle 11 and the conductive layer 22 arrange|positioned on the surface of the base material particle 11. The conductive layer 22 has a first conductive layer 22A as an inner layer and a second conductive layer 22B as an outer layer. The first conductive layer 22A is disposed on the surface of the substrate particle 11. The first conductive layer 22A is disposed on the surface of the shell 13. The second conductive layer 22B is disposed on the surface of the first conductive layer 22A.

3 shows a cross-sectional view of conductive particles according to a third embodiment of the present invention.

The electroconductive particle 31 shown in FIG. 3 has a base particle 11, a conductive layer 32, a plurality of core substances 33, and a plurality of insulating substances 34.

The conductive layer 32 is disposed on the surface of the substrate particle 11. A conductive layer 32 is disposed on the surface of the shell 13.

The electroconductive particle 31 has a plurality of protrusions 31a on the electroconductive surface. The conductive layer 32 has a plurality of protrusions 32a on the outer surface. As described above, the conductive particles may have protrusions on the conductive surface or may have protrusions on the outer surface of the conductive layer. A plurality of core materials 33 are disposed on the surface of the substrate particle 11. A plurality of core materials 33 are disposed on the surface of the shell 13. A plurality of core materials 33 are embedded in the conductive layer 32. The core material 33 is disposed inside the protrusions 31a and 32a. The conductive layer 32 covers a plurality of core materials 33. The outer surface of the conductive layer 32 is raised by the plurality of core materials 33, and projections 31a and 32a are formed.

The conductive particles 31 have an insulating material 34 disposed on the outer surface of the conductive layer 32. At least a part of the outer surface of the conductive layer 32 is covered with an insulating material 34. The insulating material 34 is formed of an insulating material and is an insulating particle. As described above, the conductive particles may have an insulating material disposed on the outer surface of the conductive layer.

The metal for forming the conductive layer is not particularly limited. Examples of the metal include gold, silver, palladium, copper, platinum, zinc, iron, tin, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, thallium, germanium, cadmium, silicon, and these And alloys of. Moreover, as said metal, tin-doped indium oxide (ITO), solder, etc. are mentioned. Among them, since the connection resistance between electrodes can be further lowered, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is preferable.

Like the conductive particles 1 and 31, the conductive layer may be formed by one layer. Like the conductive particles 21, the conductive layer may be formed of a plurality of layers. That is, the conductive layer may have a stacked structure of two or more layers. When the conductive layer is formed of a plurality of layers, the outermost layer is preferably a gold layer, a nickel layer, a palladium layer, a copper layer, or an alloy layer containing tin and silver, and more preferably a gold layer. When the outermost layer is such a preferable conductive layer, the connection resistance between electrodes is further lowered. In addition, when the outermost layer is a gold layer, the corrosion resistance is further increased.

The method of forming the conductive layer on the surface of the substrate particle is not particularly limited. As a method of forming the conductive layer, for example, a method by electroless plating, a method by electroplating, a method by physical vapor deposition, and a metal powder or a paste containing a metal powder and a binder are coated on the surface of the substrate particles. Method, etc. are mentioned. Among them, since formation of the conductive layer is easy, a method by electroless plating is preferred. Examples of the physical vapor deposition method include vacuum vapor deposition, ion plating, and ion sputtering.

The particle diameter of the conductive particles is preferably 0.5 µm or more, more preferably 1 µm or more, preferably 520 µm or less, more preferably 500 µm or less, even more preferably 100 µm or less, even more preferably It is 50 µm or less, particularly preferably 20 µm or less. If the particle diameter of the conductive particles is greater than or equal to the lower limit and less than or equal to the upper limit, the contact area between the conductive particles and the electrode is sufficiently large when the electrodes are connected using conductive particles, and aggregated conductive particles are formed when forming the conductive layer. It becomes difficult to become. In addition, the gap between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the substrate particles. Moreover, if the particle diameter of the electroconductive particle is more than the said lower limit and less than the said upper limit, electroconductive particle can be used suitably for the use of a conductive material.

The particle diameter of the said electroconductive particle means the diameter when electroconductive particle is a spherical shape, and when electroconductive particle is a shape other than a spherical shape, it means the diameter assuming that it is a spherical equivalent of the volume.

The thickness of the conductive layer is preferably 0.005 µm or more, more preferably 0.01 µm or more, preferably 10 µm or less, more preferably 1 µm or less, and still more preferably 0.3 µm or less. The thickness of the conductive layer is the thickness of the entire conductive layer when the conductive layer is a multilayer. When the thickness of the conductive layer is greater than or equal to the lower limit and less than or equal to the upper limit, sufficient conductivity is obtained, the conductive particles are not too hard, and the conductive particles are sufficiently deformed at the time of connection between electrodes.

When the conductive layer is formed by a plurality of layers, the thickness of the outermost conductive layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, preferably 0.5 μm or less, more preferably 0.1 It is not more than µm. When the thickness of the outermost conductive layer is greater than or equal to the lower limit and less than or equal to the upper limit, the covering by the outermost conductive layer becomes uniform, the corrosion resistance is sufficiently high, and the connection resistance between the electrodes is further lowered. In addition, when the outermost layer is a gold layer, the thinner the gold layer, the lower the cost.

The thickness of the conductive layer can be measured by observing the cross section of the conductive particles using, for example, a transmission electron microscope (TEM).

The said electroconductive particle may have protrusions on an electroconductive surface. The said electroconductive particle may have a protrusion on the outer surface of the said electroconductive layer. It is preferable that the protrusion is plural. An oxide film is often formed on the surface of the conductive layer and the surface of the electrode connected by the conductive particles. When conductive particles having protrusions are used, the oxide film is effectively removed by the protrusions by placing and pressing electroconductive particles between electrodes. For this reason, the electrode and the conductive layer of the electroconductive particle can be made to contact more reliably, and the connection resistance between electrodes can be made low. In addition, when the conductive particles have an insulating material on the surface, or when the conductive particles are dispersed in a binder resin and used as a conductive material, an insulating material or a binder between the conductive particles and the electrode by the protrusion of the conductive particles Resin can be effectively excluded. For this reason, the reliability of conduction between electrodes can be improved.

As a method of forming protrusions on the surface of the conductive particles, a method of forming a conductive layer by electroless plating after attaching a core material to the surface of the base particles, and a conductive layer by electroless plating on the surface of the base particles After forming, a method of attaching a core material and further forming a conductive layer by electroless plating may be mentioned. Also, in order to form the protrusion, the core material may not be used.

The conductive particles may include an insulating material disposed on the outer surface of the conductive layer. In this case, if electroconductive particles are used for connection between electrodes, a short circuit between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles are in contact, since an insulating material is present between the plurality of electrodes, it is possible to prevent a short circuit between electrodes adjacent to each other in the horizontal direction, not between the upper and lower electrodes. In addition, by pressing the conductive particles with two electrodes at the time of connection between the electrodes, the insulating material between the conductive layer of the conductive particles and the electrode can be easily removed. In the case where the conductive particles have protrusions on the surface of the conductive layer, the insulating material between the conductive layer of the conductive particles and the electrode can be removed more easily. The insulating material is preferably an insulating resin layer or insulating particles, and more preferably insulating particles. It is preferable that the said insulating particle is an insulating resin particle.

(Conductive material)

The said conductive material contains the above-mentioned electroconductive particle and binder resin. It is preferable that the said electroconductive particle is dispersed in a binder resin and used as a conductive material. It is preferable that the said conductive material is an anisotropic conductive material. The conductive material is suitably used for electrical connection of electrodes. It is preferable that the said conductive material is a circuit connection material.

The binder resin is not particularly limited. As the binder resin, a known insulating resin is used. Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers and elastomers. As for the binder resin, only one type may be used, or two or more types may be used in combination.

As said vinyl resin, a vinyl acetate resin, an acrylic resin, a styrene resin, etc. are mentioned, for example. Examples of the thermoplastic resin include polyolefin resin, ethylene-vinyl acetate copolymer, and polyamide resin. As said curable resin, an epoxy resin, a urethane resin, a polyimide resin, an unsaturated polyester resin, etc. are mentioned, for example. In addition, 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. Examples of the thermoplastic block copolymer include a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, a hydrogenated product of a styrene-butadiene-styrene block copolymer, and a styrene-isoprene-styrene block copolymer. Hydrogenated substances, etc. are mentioned. Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

In addition to the conductive particles and the binder resin, the conductive material is, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and Various additives such as flame retardants may also be included.

The method of dispersing the conductive particles in the binder resin may be a conventionally known dispersion method, and is not particularly limited. As a method of dispersing the conductive particles in the binder resin, for example, after adding the conductive particles to the binder resin, kneading with a planetary mixer or the like to disperse the conductive particles, and homogenizing the conductive particles in water or an organic solvent. After uniformly dispersing using a genizer or the like, a method of adding to the binder resin and kneading with a planetary mixer to disperse, and after diluting the binder resin with water or an organic solvent, etc., the conductive particles are A method of adding, kneading and dispersing in a planetary mixer or the like can be mentioned.

The said conductive material can be used as a conductive paste, a conductive film, etc. When the conductive material according to the present invention is a conductive film, a film not containing conductive particles may be laminated on a conductive film containing conductive particles. It is preferable that the said conductive paste is an anisotropic conductive paste. It is preferable that the said conductive film is an anisotropic conductive film.

In 100% by weight of the conductive material, the content of the binder resin is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, particularly preferably 70% by weight or more, preferably It is preferably 99.99% by weight or less, and more preferably 99.9% by weight or less. When the content of the binder resin is greater than or equal to the lower limit and less than or equal to the upper limit, conductive particles are efficiently disposed between electrodes, and the connection reliability of the member to be connected connected by a conductive material is further improved.

In 100% by weight of the conductive material, the content of the conductive particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, preferably 40% by weight or less, more preferably 20% by weight or less, further preferably It is 10% by weight or less. When the content of the conductive particles is more than the lower limit and less than the upper limit, the reliability of conduction between electrodes is further increased.

(Connection structure)

A connection structure can be obtained by connecting the member to be connected using the above-described electroconductive particle or by using the electroconductive material containing the above-described electroconductive particle and a binder resin.

The connection structure includes a first connection object member, a second connection object member, and a connection portion connecting the first connection object member and the second connection object member, and the connection portion is formed of the aforementioned conductive particles. Alternatively, it is preferable that it is a connection structure formed of a conductive material containing the aforementioned conductive particles and a binder resin. When the electroconductive particle is used alone, the connection part itself is electroconductive particle. That is, the 1st and 2nd connection object members are connected by electroconductive particle. It is preferable that the said conductive material used to obtain the said connection structure is an anisotropic conductive material.

It is preferable that the first connection object member has a first electrode on its surface. It is preferable that the second connection object member has a second electrode on its surface. It is preferable that the first electrode and the second electrode are electrically connected by the conductive particles.

FIG. 4 is a front cross-sectional view schematically showing a connection structure using the conductive particles 1 shown in FIG. 1.

The connection structure 51 shown in FIG. 4 includes a first connection object member 52, a second connection object member 53, a first connection object member 52 and a second connection object member 53. It includes a connecting portion 54 to be connected. The connection portion 54 is formed of a conductive material containing the conductive particles 1 and a binder resin. In FIG. 4, for convenience of illustration, the electroconductive particle 1 is schematically shown. Instead of the electroconductive particle 1, other electroconductive particle, such as electroconductive particle 21 and 31, can also be used.

The first connection object member 52 has a plurality of first electrodes 52a on its surface (upper surface). The second connection object member 53 has a plurality of second electrodes 53a on the surface (lower surface). The first electrode 52a and the second electrode 53a are electrically connected by one or more conductive particles 1. Accordingly, the first and second connection object members 52 and 53 are electrically connected by the conductive particles 1.

The manufacturing method of the connection structure is not particularly limited. As an example of the manufacturing method of the connection structure, a method of heating and pressing the laminate after obtaining a laminate by disposing the conductive material between the first connection object member and the second connection object member. The pressure of the pressurization is about 9.8×10 ⁴ to 4.9×10 ⁶ Pa. The heating temperature is about 120 to 220°C. The pressure for connecting the electrode of the flexible printed circuit board, the electrode disposed on the resin film, and the electrode of the touch panel is about 9.8×10 ⁴ to 1.0×10 ⁶ Pa.

Specific examples of the member to be connected include electronic components such as semiconductor chips, capacitors and diodes, and electronic components such as circuit boards such as printed circuit boards, flexible printed circuit boards, glass epoxy substrates and glass substrates. It is preferable that the said conductive material is a conductive material for connecting electronic components. The conductive paste is a paste-like conductive material, and is preferably applied onto a member to be connected in a paste-like state.

The said electroconductive particle and the said electroconductive material are used suitably also for a touch panel. Therefore, it is preferable that the said connection object member is a flexible printed circuit board, or it is also a connection object member in which an electrode is arrange|positioned on the surface of a resin film. It is preferable that the said connection object member is a flexible printed circuit board, and it is preferable that it is a connection object member in which an electrode is arrange|positioned on the surface of a resin film. In general, the flexible printed circuit board has an electrode on its surface.

In particular, in the present invention, in order to suppress the damage of the electroconductive particle to a member to be connected such as a substrate, the initial hardness of the substrate particle is designed in an appropriate range. For this reason, in the present invention, when the surface of the electrode is a metal that is easily oxidized such as titanium or molybdenum, a glass substrate having a relatively thin thickness (about 0.2 mm thick) and a semiconductor chip are connected, or a flexible printed circuit board and a semiconductor chip In the case of connecting or, a great effect is exhibited.

The combination of the first and second members to be connected is preferably a combination of a glass substrate or a flexible printed circuit board and a semiconductor chip, preferably a combination of a glass substrate and a semiconductor chip, and a combination of a flexible printed circuit board and a semiconductor chip. It is also desirable. In this case, the first connection object member may be a glass substrate or a flexible printed circuit board, and the second connection object member may be a glass substrate or a flexible printed circuit board. It is preferable that the thickness of the glass substrate is 0.05 mm or more and less than 0.5 mm.

Examples of the electrodes provided on the member to be connected include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes and tungsten electrodes and titanium electrodes. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, or a tungsten electrode. In addition, when the electrode is an aluminum electrode, it may be an electrode formed of only aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Sn, Al, Ga, etc. are mentioned as said trivalent metal element.

At least one of the first and second electrodes is preferably a titanium electrode or a molybdenum electrode, and both of the first and second electrodes are preferably a titanium electrode or a molybdenum electrode. At least one of the materials constituting the surfaces of the first and second electrodes preferably contains titanium or molybdenum, and both of the materials constituting the surfaces of the first and second electrodes contain titanium or molybdenum. It is more preferable to do it.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

(Example 1)

(1) Preparation of substrate particles

Production of the core)

950 parts by weight of 1,4-butanediol diacrylate and 50 parts by weight of ethylene glycol dimethacrylate were mixed to obtain a mixed solution. To the obtained mixture was added 20 parts by weight of benzoyl peroxide, and stirred until uniformly dissolved to obtain a monomer mixture. 4000 parts by weight of a 2% by weight aqueous solution obtained by dissolving polyvinyl alcohol having a molecular weight of about 1700 in pure water was placed in a reaction furnace. The obtained monomer mixture was put therein and stirred for 4 hours to adjust the particle size so that the droplets of the monomer became a predetermined particle size. Then, it reacted for 9 hours in a nitrogen atmosphere at 85 degreeC, and the polymerization reaction of the monomer droplets was performed, and particle|grains were obtained. After washing the obtained particles several times with hot water, a classification operation was performed to collect several kinds of polymer particles (organic cores) having different particle diameters.

In Example 1, polymer particles (organic cores) having a particle diameter of 2.49 μm were prepared among the polymer particles collected by classification operation.

Production of core shell particles)

30 parts by weight of the obtained polymer particles (organic core), 12 parts by weight of hexadecyl ammonium bromide as a surfactant, and 24 parts by weight of a 25% by weight aqueous ammonia solution were placed in 540 parts by weight of isopropyl alcohol and 60 parts by weight of pure water and mixed, A dispersion of polymer particles was obtained. 140 parts by weight of tetraethoxysilane was added to this dispersion, and condensation reaction by sol-gel reaction was performed. The condensation product of tetraethoxysilane was deposited on the surface of the polymer particle to form a shell to obtain particles. The obtained particles were washed several times with ethanol and dried to obtain core shell particles (substrate particles). The particle diameter of the obtained core shell particles was 3.01 µm. From the particle diameter of the core and the particle diameter of the core shell particle, the thickness of the shell was calculated to be 0.26 µm.

(2) Preparation of conductive particles

The obtained substrate particles were washed and dried. Then, a nickel layer was formed on the surface of the obtained base material particle by electroless plating method, and electroconductive particle was produced. In addition, the thickness of the nickel layer was 0.1 µm.

(Example 2)

Among the polymer particles recovered by the classification operation in Example 1, polymer particles (organic cores) having a particle diameter of 2.25 µm were prepared. Core shell particles and electroconductive particles were obtained in the same manner as in Example 1 except that the obtained polymer particles were used, and the addition amount of tetraethoxysilane was changed to 310 parts by weight when producing the core shell particles.

(Example 3)

The substrate particles obtained in Example 1 were heat-treated at 200°C for 30 minutes in a state filled with nitrogen in an electric furnace. Then, electroconductive particle was produced by the same process as Example 1.

(Example 4)

(1) Palladium adhesion process

The substrate particles obtained in Example 1 were prepared. The obtained substrate particles were etched and washed with water. Subsequently, the base particles were added and stirred in 100 mL of a palladium catalyst solution containing 8% by weight of a palladium catalyst. After that, it was filtered and washed. Substrate particles were added to a 0.5% by weight dimethylamine borane solution at pH 6 to obtain palladium-adhered substrate particles.

(2) Core material adhesion process

The substrate particles to which palladium has adhered were stirred in 300 mL of ion-exchanged water for 3 minutes and dispersed to obtain a dispersion. Subsequently, 1 g of a metallic nickel particle slurry (average particle diameter of 100 nm) was added to the dispersion over 3 minutes to obtain base particles with a core substance attached thereto.

(3) Electroless nickel plating process

In the same manner as in Example 1, a nickel layer was formed on the surface of the substrate particles to produce electroconductive particles. In addition, the thickness of the nickel layer was 0.1 µm.

(Example 5)

(1) Preparation of insulating particles

In a 1000 mL separable flask equipped with a 4-neck separable cover, stirring blade, three-way cock, a cooling tube and a temperature probe, 100 mmol of methyl methacrylate and N,N,N-trimethyl-N-2-methacryloyloxy A monomer composition containing 1 mmol of ethyl ammonium chloride and 1 mmol of 2,2'-azobis (2-amidinopropane) dihydrochloride was weighed in ion-exchanged water so that the solid content was 5% by weight, and stirred at 200 rpm. , Polymerization was performed at 70°C for 24 hours in a nitrogen atmosphere. After completion of the reaction, it was freeze-dried to obtain insulating particles having an ammonium group on the surface and having an average particle diameter of 220 nm and a CV value of 10%.

The insulating particles were dispersed in ion-exchanged water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion of the insulating particles.

10 g of the conductive particles obtained in Example 1 were dispersed in 500 mL of ion-exchanged water, 4 g of an aqueous dispersion of insulating particles was added, followed by stirring at room temperature for 6 hours. After filtration with a 3 µm mesh filter, it was further washed with methanol and dried to obtain conductive particles with insulating particles attached thereto.

As a result of observation with a scanning electron microscope (SEM), only one layer of a coating layer made of insulating particles was formed on the surface of the conductive particles. As a result of calculating the covering area of the insulating particles (that is, the projected area of the particle diameter of the insulating particles) with respect to the area of 2.5 µm from the center of the conductive particles by image analysis, the coverage rate was 30%.

(Example 6)

Among the polymer particles recovered by the classification operation in Example 1, polymer particles (organic cores) having a particle diameter of 2.25 µm were prepared. In the same manner as in Example 1, except that the obtained polymer particles were used, and 540 parts by weight of methanol was changed to 540 parts by weight of acetonitrile when preparing the core shell particles, and the addition amount of tetraethoxysilane was changed to 310 parts by weight, Core shell particles and electroconductive particles were obtained.

(Example 7)

Among the polymer particles classified and collected in Example 1, polymer particles (organic cores) having a particle diameter of 2.75 µm were prepared. The core was carried out in the same manner as in Example 1, except that the obtained polymer particles were used, and 540 parts by weight of methanol was changed to 540 parts by weight of acetonitrile when preparing the core shell particles, and the addition amount of tetraethoxysilane was changed to 50 parts by weight. Shell particles and electroconductive particles were obtained.

(Comparative Example 1)

Among the polymer particles recovered by the classification operation in Example 1, polymer particles having a particle diameter of 3.02 µm were prepared. Using the obtained polymer particle as a base particle, it carried out similarly to Example 1, and obtained the electroconductive particle.

(Comparative Example 2)

When preparing the core, 950 parts by weight of 1,4-butanediol diacrylate and 50 parts by weight of ethylene glycol dimethacrylate are changed to 600 parts by weight of divinylbenzene (96% by weight purity) and 400 parts by weight of isoboronyl acrylate. Except having done it, it carried out similarly to Example 1, and obtained the particle. After washing the obtained particles several times with hot water, a classification operation was performed to collect several kinds of polymer particles having different particle diameters.

In Comparative Example 2, polymer particles having a particle diameter of 3.00 μm were prepared among the polymer particles collected by the classification operation. Using the obtained polymer particle as a base particle, it carried out similarly to Example 1, and obtained the electroconductive particle.

(Comparative Example 3)

When preparing the core, 950 parts by weight of 1,4-butanediol diacrylate and 50 parts by weight of ethylene glycol dimethacrylate were changed to 1000 parts by weight of divinylbenzene (purity 96% by weight), and the amount of benzoyl peroxide added was 40 Except having changed into parts by weight, it carried out similarly to Example 1, and obtained the particle. After washing the obtained particles several times with hot water, a classification operation was performed to collect several kinds of polymer particles having different particle diameters.

In Comparative Example 3, polymer particles having a particle diameter of 3.01 µm were prepared among the polymer particles collected by the classification operation. Using the obtained polymer particle as a base particle, it carried out similarly to Example 1, and obtained the electroconductive particle.

(Comparative Example 4)

When preparing the core, 1,4-butanediol diacrylate 950 parts by weight and ethylene glycol dimethacrylate 50 parts by weight changed to divinylbenzene (purity 96% by weight) 800 parts by weight and acrylonitrile 200 parts by weight, and Particles were obtained in the same manner as in Example 1 except that the addition amount of benzoyl peroxide was changed to 40 parts by weight. After washing the obtained particles several times with hot water, a classification operation was performed to collect several kinds of polymer particles having different particle diameters.

In Comparative Example 4, polymer particles having a particle diameter of 3.00 μm were prepared among the polymer particles collected by the classification operation. Using the obtained polymer particle as a base particle, it carried out similarly to Example 1, and obtained the electroconductive particle.

(Comparative Example 5)

Among the polymer particles recovered by the classification operation in Example 1, polymer particles having a particle diameter of 3.01 µm were prepared. When producing core shell particles using the obtained polymer particles, core shell particles and conductive particles were obtained in the same manner as in Example 1 except that the addition amount of tetraethoxysilane was changed to 10 parts by weight.

(evaluation)

(1) The particle diameter of the substrate particle, the particle diameter of the core and the thickness of the shell

For the obtained substrate particles, about 10000 particle diameters were measured using a particle size distribution measuring device ("Multisizer 3" manufactured by Beckman Coulter), and the average particle diameter and standard deviation were measured. Also about the core used when producing the substrate particle, the particle diameter was measured by the same method. The thickness of the shell was determined from the difference between the particle diameter of the substrate particles and the particle diameter of the core.

(2) Compressive modulus of the base particles (10% K value and 30% K value), and 10% load value, 30% load value, and 40% load value

The compression modulus (10% K value and 30% K value), and 10% load value, 30% load value, and 40% load value of the obtained substrate particles were micro-compressed by the above-described method at 23°C. It measured using a tester ("Fisher Scope H-100" manufactured by Fisher Corporation).

(3) compression recovery rate of the substrate particles

The compression recovery rate of the obtained substrate particles was measured using a micro compression tester ("Fischer Scope H-100" manufactured by Fischer) by the method described above.

(4) Fracture deformation of substrate particles

Using a micro-compression tester ("Fisher Scope H-100" manufactured by Fischer), fracture strain was measured by the method described above at 23°C.

(5) Connection resistance

Fabrication of the connection structure:

10 parts by weight of bisphenol A epoxy resin ("Epicoat 1009" manufactured by Mitsubishi Chemical), 40 parts by weight of acrylic rubber (weight average molecular weight of about 800,000), 200 parts by weight of methyl ethyl ketone, and a microcapsule type curing agent ( 50 parts by weight of Asahi Kasei E Materials Co., Ltd. "HX3941HP") and 2 parts by weight of a silane coupling agent (Toray Dow Corning Silicone Co., Ltd. "SH6040") were mixed, and conductive particles were added and dispersed so that the content was 3 wt%, A resin composition was obtained.

The obtained resin composition was applied to a 50 µm-thick PET (polyethylene terephthalate) film on which one side was subjected to a release treatment, and dried for 5 minutes with hot air at 70° C. to prepare an anisotropic conductive film. The thickness of the obtained anisotropic conductive film was 12 micrometers.

The obtained anisotropic conductive film was cut into a size of 5 mm x 5 mm. The cut anisotropic conductive film is almost on the side of the ITO electrode of a PET substrate (width 3 cm, length 3 cm) on which an ITO electrode (height 0.1 µm, L/S = 20 µm/20 µm) having a wiring for measuring resistance on one side is installed. Attached to the center. Subsequently, the two-layer flexible printed circuit board (width 2 cm, length 1 cm) provided with the same gold electrode was aligned so that the electrodes overlap each other, and then bonded. The laminated body of this PET substrate and a two-layer flexible printed circuit board was thermocompressed under the conditions of 10N, 180 degreeC, and 20 second compression bonding, and the connection structure was obtained. Further, a two-layer flexible printed circuit board in which a copper electrode was formed on a polyimide film and the copper electrode surface was plated with Au was used.

Measurement of connection resistance:

The connection resistance between the opposing electrodes of the obtained connection structure was measured by the four-terminal method. Connection resistance was determined based on the following criteria.

[Evaluation criteria for connection resistance]

○○: Connection resistance is 3.0Ω or less

○: Connection resistance exceeds 3.0 Ω and 4.0 Ω or less

△: Connection resistance exceeds 4.0 Ω and 5.0 Ω or less

×: Connection resistance exceeds 5.0 Ω

(6) presence or absence of cracks in the electrode

In the connection structure obtained in the above (5) evaluation of connection resistance, it was observed whether or not cracks occurred in 100 electrodes.

[Presence of crack in electrode]

○○: Out of 100 electrodes, no cracks occurred

○: Out of 100 electrodes, the number of cracks is 2 or less

△: Out of 100 electrodes, the number of cracks is 3 to 5

×: Out of 100 electrodes, the number of cracks is 6 to 10

××: Out of 100 electrodes, the number of cracks is 11 or more

(7) Connection reliability under high temperature and high humidity conditions

100 connection structures obtained in the above (5) evaluation of connection resistance were left at 85°C and 85% RH for 100 hours. After the test, for 100 connecting structures, it was evaluated whether or not a conduction failure between the upper and lower electrodes occurred.

○○: Out of 100 connection structures, the number of occurrence of conduction failure is 1 or less

○: Out of 100 connection structures, the number of occurrence of conduction failure is 2 to 5

△: Among 100 connection structures, the number of occurrences of conduction failure is 6 to 10

×: Out of 100 connection structures, the number of occurrences of conduction failure is 11 or more

The results are shown in Table 1 below. In addition, the aspect ratios of the substrate particles obtained in Examples 1 to 3, 6, and 7 were all 1.2 or less. In addition, the evaluation results of the connection resistance in Examples 2 to 4 and 6 were all "○○", but the value of the connection resistance in Example 4 was lower than the value of the connection resistance in Examples 2 to 3 and 6. It is thought that the protrusion had an effect.

1: conductive particle 2: conductive layer
11: substrate particle 12: core
13: shell 21: electroconductive particle
22: conductive layer 22A: first conductive layer
22B: second conductive layer 31: conductive particles
31a: protrusion 32: conductive layer
32a: protrusion 33: core material
34: insulating material 51: connection structure
52: first connection object member 52a: first electrode
53: second connection object member 53a: second electrode
54: connection

Claims (11)

As a substrate particle formed on a surface of a conductive layer and used to obtain conductive particles having the conductive layer,
It is a core shell particle having a core and a shell disposed on the surface of the core,
The core is an organic core,
The shell is an inorganic shell,
The compression recovery rate when 30% compression deformation is 50% or more,
The compressive modulus when compressed by 10% is 3000 N/mm ² or more and less than 6000 N/mm ²
The base particle of which the ratio of the load value when compressed by 30% to the load value when compressed by 10% is 3 or less. The substrate particle according to claim 1, wherein the shell has a thickness of 100 nm or more and 5 μm or less. The substrate particle according to claim 1, wherein the compressive elastic modulus when compressed by 30% is 3000 N/mm ² or less. The substrate particle according to claim 1, wherein the ratio of the load value when compressed by 40% to the load value when compressed by 10% is 6 or less. The substrate particle according to claim 1, wherein the fracture strain is 10% or more and 30% or less. The substrate particle according to any one of claims 1 to 5, and
A conductive particle comprising a conductive layer disposed on the surface of the substrate particle. The conductive particles according to claim 6, further comprising an insulating material disposed on the outer surface of the conductive layer. The electroconductive particle of Claim 6 which has a protrusion on the outer surface of the said electroconductive layer. Containing conductive particles and a binder resin,
The conductive material, wherein the conductive particles include the substrate particles according to any one of claims 1 to 5, and a conductive layer disposed on the surface of the substrate particles. A first connection object member having a first electrode on its surface,
A second connection object member having a second electrode on its surface,
And a connection portion connecting the first connection object member and the second connection object member,
The connection portion is formed of conductive particles, or is formed of a conductive material containing the conductive particles and a binder resin,
The said electroconductive particle is provided with the base material particle of any one of Claims 1-5, and the conductive layer arrange|positioned on the surface of the said base material particle,
The connection structure in which the first electrode and the second electrode are electrically connected by the conductive particles. delete

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