Conductive particles, method for producing conductive particles, and conductive composition

Abstract

To provide a conductive particle, a method for producing a conductive particle, and a conductive composition, which can prevent outflow of a matrix layer comprising a matrix conductive material during thermocompression and enable improvement in conduction reliability and insulation.SOLUTION: The present invention provides a conductive particle comprising a base particle, and a matrix conductive material and a domain conductive material disposed on the surface of the base particle.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive particle, a method for producing a conductive particle, and a conductive composition. [Background technology]

[0002] A technique has been proposed in the past in which small particles are physically collided with the surface of base particles by a mechanochemical method (hybridization treatment) to form a film of the small particles on the surface of the base particles (see, for example, Patent Document 1). For example, as shown in FIG. 1A, when base particles 101 having a metal layer 102 on their surface and solder particles 103 such as SnBi are mixed by a mechanochemical method, conductive particles 100 having a solder layer 103a on the surface of the base particles 101 are produced (see FIG. 1B). Next, as shown in FIG. 1C, when a connection structure is produced using a conductive composition containing the conductive particles 100 and the connection structure is subjected to thermocompression bonding, the molten solder layer 103a is pushed out and the electrical conductivity reliability is reduced (see FIG. 1D). Furthermore, as shown in FIG. 1E, adjacent conductive particles 100 coalesce during thermocompression bonding, resulting in a problem of reduced insulation.

[0003] Also proposed is a conductive particle that includes a base particle and a solder layer disposed on the surface of the base particle, the solder layer containing a reinforcing material that suppresses solder cracking (see, for example, Patent Document 2). In Patent Document 2, carbon black or carbon nanotubes are used as the reinforcing material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-209491 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-54851 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conductive particles described in Patent Document 2 above do not have a matrix conductive material and a domain conductive material on the surface of the base particle, and the objective is to provide conductive particles that are less likely to cause cracks in the solidified solder portion after melting when used for electrical connection of a connection structure, but the objective is not to prevent the outflow of the matrix layer made of the matrix conductive material during thermocompression bonding, thereby improving the conductivity reliability and insulation properties.

[0006] The present invention aims to solve the above-mentioned problems in the prior art and to achieve the following object: That is, the present invention aims to provide conductive particles, a method for producing conductive particles, and a conductive composition that can prevent the matrix layer made of a matrix conductive material from flowing out during thermocompression bonding and improve the conductivity reliability and insulating properties. [Means for solving the problem]

[0007] The means for solving the above problems are as follows: <1> The conductive particles are characterized by having a base particle, a matrix conductive material on the surface of the base particle, and a domain conductive material. <2> the domain conductive material has a melting point higher than the melting point of the matrix conductive material; <1> The conductive particles are as described in <3> the matrix layer made of the matrix conductive material on the surface of the base particle has an average thickness of 1 nm or more; <1> from <2> The conductive particles are any one of the above. <4> the matrix conductive material contains Sn and at least one selected from Bi, Ag, Cu, and In; <1> from <3> The conductive particles are any one of the above. <5> the domain conductive material contains at least one selected from Au, Ag, Cu, Ni, Sn, and Zn; <1> from <4> The conductive particles are any one of the above. <6> The base particles are at least one of resin particles and metal-coated resin particles. <1> from <5> The conductive particles are any one of the above. <7> The above-mentioned, which is produced by a mechanochemical method. <1> from <6> The conductive particles are any one of the above. <8> The method for producing conductive particles is characterized by including a mixing step of mixing base particles, a matrix conductive material, and a domain conductive material by a mechanochemical method. <9> The average particle size of the base particles is 3 μm or more and 300 μm or less. <8> 2. A method for producing conductive particles according to claim 1. <10> the ratio (D / C) of the average particle diameter D of the domain conductive material to the average particle diameter C of the base particles is 1 / 10,000 or more and 1 / 10 or less; <9> 2. A method for producing conductive particles according to claim 1. <11> the mixing mass ratio (A:B) of the matrix conductive material A to the domain conductive material B is 9:1 to 5:5; <8> from <10> 1. A method for producing conductive particles according to any one of the above. <12> The aforementioned <1> from <7> 1. A conductive composition comprising the conductive particles according to any one of the above items. [Effects of the Invention]

[0008] According to the present invention, it is possible to solve the above-mentioned problems in the prior art, achieve the above-mentioned object, and provide conductive particles, a method for manufacturing conductive particles, and a conductive composition that can prevent the matrix layer made of a matrix conductive material from flowing out during thermocompression bonding and improve the conductivity reliability and insulation properties. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1A is a diagram showing how solder particles and base particles are mixed by a mechanochemical method. [Figure 1B] FIG. 1B is a schematic diagram showing an example of a conventional conductive particle. [Figure 1C]FIG. 1C is a schematic diagram showing a connection portion of the connection structure using the conductive particles of FIG. 1B. [Figure 1D] FIG. 1D is a schematic diagram showing the state of conductive particles during thermocompression bonding. [Figure 1E] FIG. 1E is a diagram showing a state in which adjacent conductive particles are united during thermocompression bonding. [Figure 2A] FIG. 2A is a diagram showing how a matrix conductive material, a domain conductive material, and base particles are mixed by a mechanochemical method. [Figure 2B] FIG. 2B is a schematic diagram showing an example of the conductive particle of the present invention. [Figure 2C] FIG. 2C is a schematic diagram showing a connection portion of the connection structure using the conductive particles of FIG. 2B. [Figure 2D] FIG. 2D is a schematic diagram showing the state of the conductive particles during thermocompression bonding. [Figure 2E] FIG. 2E is a diagram showing a state in which adjacent conductive particles are not united during thermocompression bonding. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Conductive particles) The conductive particles of the present invention have a base particle, a matrix conductive material on the surface of the base particle, and a domain conductive material. The conductive particles have a matrix layer made of a matrix conductive material on the surface of the base particle, and domain particles made of a domain conductive material are present in a dispersed state in the matrix layer. As a result, even if the matrix layer melts during thermocompression bonding, the domain particles present in the matrix layer suppress the flow of the matrix layer, preventing the matrix layer from flowing out during thermocompression bonding, thereby improving conductivity reliability. In addition, adjacent conductive particles do not coalesce, improving insulation properties.

[0011] <Mother particle> The base particles are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include resin particles, metal-coated resin particles, organic-inorganic hybrid particles, metal particles, etc. Among these, resin particles or metal-coated resin particles are preferred because of their excellent stress relaxation properties.

[0012] Examples of the resin in the resin particles include styrene-divinylbenzene copolymer, benzoguanamine resin, cross-linked polystyrene resin, acrylic resin, and styrene-silica composite resin. The metal-coated resin particles are particles having a metal layer provided on the surface of the resin particles. The method for coating the resin particles with the metal layer is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include electroplating and sputtering. The metal layer is preferably made of at least one of nickel, silver, copper, gold, and palladium, or an alloy thereof. The average thickness of the metal layer is preferably 50 nm to 300 nm, more preferably 80 nm to 250 nm. When the metal layer is composed of multiple metal layers, it is preferable that the total average thickness of the multiple metal layers falls within the above average thickness range. Examples of the organic-inorganic hybrid particles include particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin. Examples of the metal particles include nickel particles, cobalt particles, silver particles, copper particles, gold particles, palladium particles, and solder particles.

[0013] The average particle size of the base particles is preferably 3 μm or more and 300 μm or less, and more preferably 10 μm or more and 50 μm or less. When the average particle size of the base particles is 3 μm or more and 300 μm or less, the conductive particles can be efficiently produced using a mechanochemical method. The average particle size can be expressed as a number frequency by measuring approximately 10,000 particles using a dry imaging particle size distribution analyzer (Morphologi G3, manufactured by Malvern).

[0014] <Matrix conductive material> The matrix conductive material is present in the form of a layer on the surface of the base particles, forming a matrix layer. Examples of the matrix conductive material include Sn-Pb solder particles, Pb-Sn-Sb solder particles, Sn-Sb solder particles, Sn-Pb-Bi solder particles, Sn-Bi solder particles, Sn-Bi-Ag solder particles, Sn-Bi-Cu solder particles, Sn-Cu solder particles, Sn-Pb-Cu solder particles, Sn-In solder particles, Sn-Ag solder particles, Sn-Pb-Ag solder particles, Pb-Ag solder particles, and Sn-Ag-Cu solder particles, as defined in JIS Z3282-1999. These may be used alone or in combination of two or more. Among these, solder particles containing Sn and at least one selected from Bi, Ag, Cu, and In are preferred, and Sn-Bi based solder particles, Sn-Bi-Ag based solder particles, Sn-Ag-Cu based solder particles, and Sn-In based solder particles are more preferred.

[0015] The average thickness of the matrix layer made of the matrix conductive material on the surface of the base particle is preferably 1 nm or more, and more preferably 100 nm or more and 1000 nm or less. The average thickness of the matrix layer can be determined by, for example, measuring approximately 10,000 particles before and after mechanochemical treatment using a dry imaging particle size distribution analyzer (Morphologi G3, manufactured by Malvern), comparing the particle size distributions in terms of number frequency, and calculating the thickness increase from the particle diameters obtained before and after mechanochemical treatment. The average thickness of the matrix layer made of the matrix conductive material on the surface of the base particle is preferably larger than the average particle size of the domain particles made of the domain conductive material present in the matrix layer, thereby making it possible to reliably hold the domain particles in the matrix layer. The melting point of the matrix conductive material is preferably 110°C or higher and 240°C or lower, and more preferably 120°C or higher and 200°C or lower. The melting point of the matrix conductive material is preferably lower than the melting point of the domain conductive material, since the domain conductive material can exist in a particulate state in the matrix layer made of the matrix conductive material.

[0016] <Domain conductive material> The domain conductive material exists as domain particles in a matrix layer made of a matrix conductive material on the surface of the base particle. The domain conductive material preferably contains at least one selected from Au, Ag, Cu, Ni, Sn, and Zn. The mass ratio (A:B) of the matrix conductive material A to the domain conductive material B on the surface of the base particle is preferably 9:1 to 5:5.

[0017] The conductive particles of the present invention suppress the outflow of the matrix layer of the thermocompressed conductive particles, improving the electrical conductivity reliability. In addition, adjacent conductive particles do not coalesce, improving the insulating properties. The conductive particles of the present invention are preferably produced by a mechanochemical method in which base particles, a matrix conductive material, and a domain conductive material are mixed together.

[0018] (Method of manufacturing conductive particles) The method for producing conductive particles of the present invention includes a mixing step of mixing base particles, a matrix conductive material, and a domain conductive material by a mechanochemical method, and may further include other steps as necessary. According to the method for producing conductive particles of the present invention, even if the layer made of the matrix conductive material formed in a layered form on the surface of the base particle melts, the domain particles made of the domain conductive material in the matrix layer made of the matrix conductive material suppress the flow of the matrix layer, thereby obtaining conductive particles in which the matrix layer does not flow out during thermocompression bonding.

[0019] The mechanochemical method utilizes a chemical reaction caused by mechanical energy applied to a substance in a mechanical operation such as impact, compression, pulverization, mixing, or kneading, and examples of the mechanochemical method include a mixing method using a high-speed stirring powder spheroidizer, a hybridizer, or the like. Examples of the high-speed stirring type powder spheroidizing device include Model NSM-200 and Model NSM-350 (both manufactured by Seishin Enterprise Co., Ltd.). The hybridizer may be, for example, Hybridization System NHS (manufactured by Nara Machinery Co., Ltd.).

[0020] The matrix conductive material and the domain conductive material are both in particulate form before the mixing step, and the ratio (D1 / C or D2 / C) of the average particle size D1 of the matrix particles made of the matrix conductive material and the average particle size D2 of the domain particles made of the domain conductive material to the average particle size C of the base particles is preferably 1 / 100,000 or more to 1 / 10 or less, more preferably 1 / 10,000 or more to 1 / 10 or less, and even more preferably 1 / 1,000 or more to 1 / 10 or less. When the ratio (D1 / C or D2 / C) is 1 / 100,000 or more to 1 / 10 or less, a matrix layer in which the domain particles are dispersed on the surfaces of the base particles can be efficiently formed using the matrix particles and the domain particles. The average particle size of the matrix particles made of the matrix conductive material and the average particle size of the domain particles made of the domain conductive material can be determined, for example, by measuring approximately 10,000 particles using a dry imaging particle size distribution analyzer (Morphologi G3, manufactured by Malvern) and comparing the particle size distributions in terms of number frequency.

[0021] The mixing mass ratio (A:B) of the matrix conductive material A to the domain conductive material B is preferably 95:5 to 5:95, more preferably 9:1 to 5:5, thereby enabling efficient formation of a matrix layer in which domain particles are dispersed on the surface of a base particle using the matrix conductive material and the domain conductive material.

[0022] FIG. 2A is a schematic view illustrating the mixing step in the method for producing conductive particles of the present invention. 2A, in the mixing step, base particles 11 having metal layers 12 on their surfaces, a matrix conductive material 13, and a domain conductive material 14 are mixed by a mechanochemical method, and the matrix conductive material 13 and the domain conductive material 14 are caused to collide with the base particles 11. As a result, as shown in FIG. 2B, conductive particles 10 are produced in which domain particles 13 made of the domain conductive material are dispersed in a matrix layer 12a made of the matrix conductive material 12. Next, as shown in Fig. 2C, a connection structure is prepared using a conductive composition containing conductive particles 10, and the connection structure is then thermocompression-bonded. As shown in Fig. 2D, even if matrix layer 13a melts, domain particles 14 present in matrix layer 13a suppress the flow of matrix layer 13a, preventing matrix layer 13a from flowing out, thereby improving electrical conductivity reliability. Furthermore, as shown in Fig. 2E, the suppression of matrix layer 13a flow during thermocompression bonding of the connection structure prevents adjacent conductive particles 10 from coalescing, thereby improving insulation.

[0023] (Conductive composition) The conductive composition of the present invention contains the conductive particles of the present invention, and preferably contains a binder, a monofunctional polymerizable monomer, an elastomer, a curing agent, and a silane coupling agent, and further contains other components as necessary.

[0024] The conductive composition may be either a conductive film in film form or a conductive paste in paste form. A conductive film is preferred from the viewpoint of ease of handling, and a conductive paste is preferred from the viewpoint of cost. When the conductive composition is a conductive film, a film not containing conductive particles may be laminated on the conductive film containing conductive particles.

[0025] -Conductive particles- As the conductive particles, the conductive particles of the present invention described above are used. The content of the conductive particles in the conductive composition is not particularly limited, and can be adjusted appropriately depending on the wiring pitch and connection area of ​​the connection structure.

[0026] -binder- The binder is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include phenoxy resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, polyolefin resin, etc. These may be used alone or in combination of two or more. Among these, phenoxy resin is particularly preferred from the viewpoints of film-forming property, processability, and connection reliability. The phenoxy resin is a resin synthesized from bisphenol A and epichlorohydrin, and may be either a suitably synthesized product or a commercially available product, such as YP-50 (manufactured by Tohto Kasei Co., Ltd.), YP-70 (manufactured by Tohto Kasei Co., Ltd.), or EP1256 (manufactured by Japan Epoxy Resins Co., Ltd.). The content of the binder in the conductive composition is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 20% by mass to 70% by mass, and more preferably 35% by mass to 55% by mass, for example.

[0027] -Monofunctional polymerizable monomer- The monofunctional polymerizable monomer is not particularly limited as long as it has one polymerizable group in the molecule and can be appropriately selected depending on the purpose. Examples include monofunctional (meth)acrylic monomers, styrene monomers, butadiene monomers, and other olefin-based monomers having double bonds. These may be used alone or in combination of two or more. Among these, monofunctional (meth)acrylic monomers are particularly preferred from the viewpoints of adhesive strength and connection reliability. The monofunctional (meth)acrylic monomer is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include acrylic acid or esters thereof, such as acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, n-dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate; and methacrylic acid or esters thereof, such as methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, n-dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. These may be used alone or in combination of two or more.

[0028] The content of the monofunctional polymerizable monomer in the conductive composition is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass.

[0029] - Hardener - The curing agent is not particularly limited as long as it can cure the binder, and can be appropriately selected depending on the purpose. For example, organic peroxides are suitable. Examples of the organic peroxide include lauroyl peroxide, butyl peroxide, benzyl peroxide, dilauroyl peroxide, dibutyl peroxide, benzyl peroxide, peroxydicarbonate, benzoyl peroxide, etc. These may be used alone or in combination of two or more. The content of the curing agent in the conductive composition is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1% by mass to 15% by mass, and more preferably 3% by mass to 10% by mass.

[0030] -Elastomer- The elastomer is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include polyurethane elastomers, acrylic rubbers, silicone rubbers, butadiene rubbers, etc. These may be used alone or in combination of two or more.

[0031] -Silane coupling agent- The silane coupling agent is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include epoxy-based silane coupling agents, acrylic-based silane coupling agents, thiol-based silane coupling agents, and amine-based silane coupling agents. The content of the silane coupling agent in the conductive composition is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.5% by mass to 10% by mass, and more preferably 1% by mass to 5% by mass.

[0032] -Other ingredients- The other components are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include organic solvents, fillers, softeners, accelerators, antioxidants, colorants (pigments, dyes), ion catcher agents, etc. The amount of the other components added is not particularly limited and can be appropriately selected depending on the purpose.

[0033] <Application> The conductive particles and conductive composition of the present invention can be used to electrically connect electrodes of various connection target components, such as connecting a flexible printed circuit board to a glass substrate (FOG (Film on Glass)), connecting a semiconductor chip to a flexible printed circuit board (COF (Chip on Film)), connecting a semiconductor chip to a glass substrate (COG (Chip on Glass)), and connecting a flexible printed circuit board to a glass epoxy substrate (FOB (Film on Board)). [Example]

[0034] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way. In the following examples and comparative examples, acrylic resin core Ni-plated particles and acrylic resin particles were used as base particles, Cu particles, Ni particles, and Au particles were used as matrix conductive materials, and SnBi particles and SnAgCu particles were used as domain conductive materials.

[0035] In the following examples, the average particle sizes of the base particles, the matrix conductive material, and the domain conductive material were measured as follows.

[0036] <Measurement of the average particle size of the base particles, matrix conductive material, and domain conductive material> The average particle size of the base particles, matrix conductive material, and domain conductive material was measured using a dry imaging particle size distribution analyzer (Morphologi G3, manufactured by Malvern) on approximately 10,000 particles, and the particle size distribution was expressed as number frequency.

[0037] <Measurement of the average thickness of the matrix layer> Approximately 10,000 particles were measured before and after mechanochemical treatment using a dry imaging particle size distribution analyzer (Morphologi G3, manufactured by Malvern), and the particle size distributions were compared based on the number frequency. The increase in thickness was calculated from the particle diameter before and after mechanochemical treatment, and the average thickness was determined.

[0038] Example 1 <Preparation of conductive particles> One part by mass of Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point: 1,083°C) was weighed out, 9 parts by mass of SnBi particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point: 139°C), and 30 parts by mass of acrylic resin-core Ni-plated particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm), and the mixture was placed in a cup and mixed with a wood bar for 1 minute. This mixture was then placed in a high-speed stirring powder spheroidizer (NSM-200, manufactured by Seishin Enterprise Co., Ltd.) and granulated at 3,000 rpm for 1 minute under a nitrogen atmosphere to produce the conductive particles of Example 1.

[0039] <Preparation of conductive film> Five parts by mass of the conductive particles prepared in Example 1 and 95 parts by mass of the insulating binder described below were placed in a planetary stirrer and stirred for one minute to prepare a conductive composition. Next, the conductive composition was applied to a 50 μm thick PET film and dried in an oven at 80°C for 5 minutes, forming a 25 μm thick adhesive layer made of the conductive composition on the PET film, and producing a conductive film 2.0 mm wide.

[0040] -Insulating binder- The insulating binder was a mixed solution of ethyl acetate and toluene containing 47 parts by mass of phenoxy resin (trade name: YP-50, manufactured by Shin-Nichika Epoxy Manufacturing Co., Ltd.), 3 parts by mass of monofunctional monomer (trade name: M-5300, manufactured by Toagosei Co., Ltd.), 25 parts by mass of urethane resin (trade name: UR-1400, manufactured by Toyobo Co., Ltd.), 15 parts by mass of rubber component (trade name: SG80H, manufactured by Nagase ChemteX Corporation), 2 parts by mass of silane coupling agent (trade name: A-187, manufactured by Momentive Performance Materials Japan), and 3 parts by mass of organic peroxide (trade name: Nyper BW, manufactured by NOF Corporation) so that the solid content was 50% by mass.

[0041] <Fabrication of connection structure> A connection structure was produced by thermocompression bonding an evaluation substrate (glass epoxy substrate (FR4), 200 μm pitch, line:space=1:1, terminal thickness 10 μm, Cu (undercoat) / Ni / Au plating) and an FPC (polyimide film, 200 μm pitch, line:space=1:1, terminal thickness 12 μm, Cu (undercoat) / Ni / Au plating) via the conductive film. The thermocompression bonding was performed by pressing a tool down through a 200 μm thick silicone rubber on the FPC under the conditions of temperature: 150° C., pressure: 2 MPa, and time: 20 seconds.

[0042] <Evaluation of conduction characteristics> For initial conductivity, the initial conduction resistance of the connection structure was measured using a digital multimeter (manufactured by Yokogawa Electric Corporation) by the four-terminal method when a current of 1 mA was applied, and the initial conductivity was evaluated according to the following criteria. As for the electrical conductivity, the electrical conductivity reliability was measured by measuring the electrical resistance of the connection structure after an environmental test under conditions of a temperature of 85° C., a humidity of 85%, and 500 hours, in the same manner as for the initial electrical conductivity, and evaluated according to the following criteria. [Evaluation criteria] ◎: Conduction resistance is less than 100mΩ ○: When the conduction resistance is between 100mΩ and 1,000mΩ △: When the conduction resistance exceeds 1,000mΩ ×: Conduction resistance is open

[0043] <Evaluation of matrix layer outflow and self-bonding between adjacent conductive particles> The cross-sections of the conductive particles in the terminal portions of the connection structure were observed by cutting the crimped samples and observing the cross-sections using a scanning electron microscope, and the outflow of the matrix layer and the self-fusion of adjacent conductive particles were evaluated. Cases where there was no outflow of the matrix layer of the conductive particles in the terminal portions of the connection structure and no self-fusion of adjacent conductive particles were evaluated as "absent," and cases where there was outflow of the matrix layer of the conductive particles in the terminal portions of the connection structure and no self-fusion of adjacent conductive particles were evaluated as "present."

[0044] <Insulation> After environmental testing at a temperature of 85°C, humidity of 85%, and 500 hours, a voltage was applied between the two patterns using a probe to measure the insulation resistance from the current that flowed at that time, and the insulation resistance was evaluated according to the following criteria. [Evaluation criteria] ◎: Electrical resistance is 10 5 Ω or more △: Electrical resistance is 10 5 If less than Ω ×: If a short circuit occurs

[0045] In Example 1, the conduction resistance was measured, and the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of a connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0046] Example 2 <Preparation of conductive particles> The conductive particles of Example 2 were prepared in the same manner as in Example 1, except that the Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,083°C) in Example 1 were replaced with Ni particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,455°C).

[0047] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 2, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0048] Example 3 <Preparation of conductive particles> The conductive particles of Example 3 were prepared in the same manner as Example 1, except that in Example 1, the Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,083°C) were replaced with Au particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point 1,064°C).

[0049] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 3, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0050] Example 4 <Preparation of conductive particles> The conductive particles of Example 4 were prepared in the same manner as in Example 1, except that in Example 1, the SnBi particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point: 139°C) were replaced with SnAgCu particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point: 220°C).

[0051] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 4, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0052] Example 5 <Preparation of conductive particles> The conductive particles of Example 5 were prepared in the same manner as in Example 4, except that the Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,083°C) in Example 4 were replaced with Ni particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,455°C).

[0053] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 5, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0054] Example 6 <Preparation of conductive particles> The conductive particles of Example 6 were prepared in the same manner as Example 1, except that in Example 1, the Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,083°C) were replaced with Ni particles (manufactured by a Chinese venture company, average particle size: 1,000 nm, melting point 1,455°C).

[0055] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 6, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0056] Example 7 <Preparation of conductive particles> The conductive particles of Example 7 were prepared in the same manner as in Example 1, except that in Example 1, the Cu particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point 1,083°C) were replaced with Ni particles (manufactured by a Chinese venture company, average particle size: 30 nm, melting point 1,455°C).

[0057] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 7, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 100 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours in an environment of 85°C and 85% RH was measured, it was 160 mΩ. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that some outflow of the matrix layer had occurred. Furthermore, adjacent conductive particles were slightly self-fused to each other.

[0058] Example 8 <Preparation of conductive particles> The conductive particles of Example 8 were prepared in the same manner as in Example 2, except that the ingredients used in Example 2 were 5 parts by mass of Ni particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point: 1,455°C), 5 parts by mass of SnBi particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point: 139°C), and 30 parts by mass of acrylic resin core Ni-plated particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm).

[0059] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 8, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0060] Example 9 <Preparation of conductive particles> The conductive particles of Example 9 were prepared in the same manner as in Example 2, except that the ingredients used in Example 2 were 1 part by mass of Ni particles (manufactured by Taiyo Nippon Sanso Corporation, average particle size: 100 nm, melting point: 1,455°C), 9 parts by mass of SnBi particles (manufactured by a Chinese venture company, average particle size: 100 nm, melting point: 139°C), and 30 parts by mass of acrylic resin core Ni-plated particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm).

[0061] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Example 9, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 150 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours in an environment of 85°C and 85% RH was measured, it was 180 mΩ. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0062] Example 10 <Preparation of conductive particles> The conductive particles of Example 10 were prepared in the same manner as in Example 1, except that the acrylic resin core Ni-plated particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm) in Example 1 were replaced with acrylic resin particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm).

[0063] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles of Example 10 prepared, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. As a result, the initial conduction resistance was 40 mΩ, which was good. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was 50 mΩ, and good conduction reliability was obtained. In addition, cross-sectional observation of the conductive particle portion of the connection structure confirmed that the matrix layer did not flow out and that metal bonding was formed. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0064] (Comparative Example 1) <Conductive particles> Acrylic resin core Ni-plated particles (manufactured by Sekisui Chemical Co., Ltd., average particle size: 20 μm) were used as conductive particles.

[0065] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Comparative Example 1, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. The initial conduction resistance was 150 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours in an environment of 85°C and 85% RH was measured, it was 1,500 mΩ, indicating a decrease in conduction reliability. Furthermore, adjacent conductive particles did not self-weld, and good insulation between adjacent conductive particles was confirmed.

[0066] (Comparative Example 2) <Preparation of conductive particles> Conductive particles of Comparative Example 2 were produced in the same manner as in Example 1, except that Cu particles were not used and only SnBi particles were used.

[0067] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Comparative Example 2, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1. The initial conduction resistance was 180 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours under an environment of 85°C and 85% RH was measured, it was found to be 1,500 mΩ, confirming an increase in the conduction resistance value and confirming that the conduction reliability was NG. When a cross-section of the particle portion of the connection structure was observed, it was confirmed that the solder had flowed out slightly, but that there was a metal bond between the solder and the substrate. In addition, adjacent conductive particles were partially self-fused together.

[0068] (Comparative Example 3) <Preparation of conductive particles> Conductive particles of Comparative Example 3 were produced in the same manner as in Example 1, except that SnBi particles were not used and only Cu particles were used.

[0069] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Comparative Example 3, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1, resulting in an initial conduction resistance of 1000 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours in an environment of 85°C and 85% RH was measured, it was found to be 2000 mΩ, confirming an increase in the conduction resistance value and confirming that the conduction reliability was NG.

[0070] Comparative Example 4 <Preparation of conductive particles> Conductive particles of Comparative Example 4 were produced in the same manner as in Example 1, except that SnBi particles were not used and only Ni particles were used.

[0071] <Preparation of conductive film, preparation of connection structure, and evaluation> Using the conductive particles prepared in Comparative Example 4, a conductive film and a connection structure were prepared in the same manner as in Example 1, and the conduction resistance was measured in the same manner as in Example 1, resulting in an initial conduction resistance of 1000 mΩ. Furthermore, when the conduction resistance of the connection structure stored in an oven for 500 hours in an environment of 85°C and 85% RH was measured, it was found to be 2000 mΩ, confirming an increase in the conduction resistance value and confirming that the conduction reliability was NG.

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] [Table 5]

[0077] The results in Tables 1 to 5 show that the conductive particles of Examples 1 to 10 are able to prevent the matrix layer from flowing out and adjacent conductive particles from coalescing together, compared to the conductive particles of Comparative Examples 1 to 4, thereby improving the conductivity reliability and insulation properties. [Industrial Applicability]

[0078] The conductive particles and conductive composition of the present invention have excellent conductive reliability and insulating properties, and are therefore suitable for use, for example, in connections between terminals of flexible printed circuit boards (FPCs) or IC chips and ITO (Indium Tin Oxide) electrodes formed on the glass substrates of LCD panels, connections between COFs and PWBs, connections between TCPs and PWBs, connections between COFs and glass substrates, connections between COFs, connections between IC substrates and glass substrates, and connections between IC substrates and PWBs. [Explanation of symbols]

[0079] 100 conductive particles 101 Resin particles 102 Metal layer 103 Solder particles 103a Solder layer 104 Metal particles 10 Conductive particles 11 Resin particles 12 metal layer 13 Matrix Conductive Materials 13a Matrix layer made of matrix conductive material 14 Domain conductive material (domain particles)

Claims

1. The conductive material has base particles, a matrix conductive material on the surface of the base particles, and a domain conductive material, the domain conductive material has a melting point higher than the melting point of the matrix conductive material; The domain conductive material comprises at least one selected from the group consisting of Au, Ag, Cu, Ni, and Sn.

2. The conductive particle according to claim 1 , wherein the matrix layer made of the matrix conductive material on the surface of the base particle has an average thickness of 1 nm or more.

3. The conductive particles according to claim 1 , wherein the matrix conductive material contains Sn and at least one element selected from the group consisting of Bi, Ag, Cu, and In.

4. The conductive particles according to claim 1 , wherein the base particles are at least one of resin particles and metal-coated resin particles.

5. The conductive particles according to claim 1 , which are produced by a mechanochemical method.

6. a mixing step of mixing base particles, a matrix conductive material, and a domain conductive material by a mechanochemical method, the domain conductive material has a melting point higher than the melting point of the matrix conductive material; A method for producing conductive particles, wherein the domain conductive material contains at least one selected from the group consisting of Au, Ag, Cu, Ni, and Sn.

7. The method for producing conductive particles according to claim 6 , wherein the average particle size of the base particles is 3 μm or more and 300 μm or less.

8. 8. The method for producing conductive particles according to claim 7, wherein a ratio (D / C) of an average particle size D of the domain conductive material to an average particle size C of the base particles is 1 / 10,000 or more and 1 / 10 or less.

9. 9. The method for producing conductive particles according to claim 6, wherein a mixing mass ratio (A:B) of the matrix conductive material A to the domain conductive material B is 9:1 to 5:

5.

10. A conductive composition comprising the conductive particles according to claim 1 .

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