WO2024070350A1 - Silver particles - Google Patents

Silver particles Download PDF

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Publication number
WO2024070350A1
WO2024070350A1 PCT/JP2023/030336 JP2023030336W WO2024070350A1 WO 2024070350 A1 WO2024070350 A1 WO 2024070350A1 JP 2023030336 W JP2023030336 W JP 2023030336W WO 2024070350 A1 WO2024070350 A1 WO 2024070350A1
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Prior art keywords
silver particles
solvent
silver
span
mass
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PCT/JP2023/030336
Other languages
French (fr)
Japanese (ja)
Inventor
真利 奥田
崇充 森
諒 加藤
大介 友利
Original Assignee
株式会社大阪ソーダ
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Publication of WO2024070350A1 publication Critical patent/WO2024070350A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102—Metallic powder coated with organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/107—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing organic material comprising solvents, e.g. for slip casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof

Definitions

  • the present invention relates to silver particles, a conductive adhesive, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
  • Conductive adhesives including die bonding agents, are bonding materials used in electronic components such as semiconductors, LEDs, and power semiconductors.
  • bonding methods involve bonding with pressure and heat, or sintering with heat without pressure to bond to the base material.
  • pressureless bonding materials has progressed from the perspective of the simplicity and efficiency of the manufacturing process.
  • Patent Document 1 discloses a metal paste made by kneading a solid content of silver particles with a solvent, in which the solid content is made of silver particles containing 30% or more silver particles with a particle size of 100 to 200 nm based on the particle number, and further, the silver particles that make up the solid content are bonded to an amine compound with a total carbon number of 4 to 8 as a protective agent.
  • this metal paste it is possible to sinter the silver particles at a low temperature range, and it is possible to form a sintered body with low resistance and excellent thermal conductivity.
  • Conductive adhesives containing silver particles have silver particles dispersed in a solvent, and can be applied to the surfaces of components (such as substrates used in electronic components, semiconductor chips, etc.) and sintered to bond the components together.
  • the conductive adhesives are applied to the surface of components using a dispenser or the like, it is desirable for the conductive adhesive to have good fluidity.
  • the conductive adhesive Furthermore, from the perspective of bonding components together with high precision, it is desirable for the conductive adhesive to have excellent shape stability after it is applied to the components and before it is sintered.
  • the main object of the present invention is to provide a conductive adhesive in which silver particles are dispersed in a solvent, the silver particles having good fluidity and excellent shape stability after application to a component until sintering. Furthermore, the present invention also aims to provide a conductive adhesive containing the silver particles, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
  • the inventors have conducted intensive research to solve the above problems. Specifically, the inventors have focused on the particle size distribution of secondary particles of silver particles dispersed in a solvent, rather than on silver particles that have been previously studied. They have made the novel discovery that when the value of SPAN: (V90-V10)/V50, measured by a light transmission centrifugal sedimentation method under specified conditions, for silver particles dispersed in a solvent is set within a specific range, the aforementioned good fluidity and shape stability are both achieved. The present invention was completed based on this discovery and through further research.
  • Item 1 Silver particles dispersed in a solvent, A compound represented by the following general formula (1) is attached to the surface of the silver particles, [In the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.] Silver particles, wherein when a concentration of the silver particles in the solvent is 50% by mass, the SPAN value measured by a light transmission centrifugal sedimentation method under the following conditions is 0.1 or more and 5.0 or less. SPAN: (V90-V10)/V50...Equation (1) When the sedimentation velocity is shown as a cumulative distribution, The settling velocity of 10% of the integrated value is V10.
  • the sedimentation velocity at 90% of the integrated value is V90.
  • the sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
  • a measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass.
  • the solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less.
  • 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds.
  • Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm.
  • Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
  • Item 2. The silver particles according to Item 1, wherein the average particle size of the silver particles is 50 to 600 nm.
  • the sedimentation velocity at 90% of the integrated value is V90.
  • the sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
  • a measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass.
  • the solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less.
  • 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds.
  • Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm.
  • Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
  • Item 4. The silver particle dispersion liquid according to Item 3, wherein the average particle size of the silver particles is 50 to 600 nm.
  • Item 5. A conductive adhesive comprising the silver particles according to item 1 or 2.
  • Item 6. A conductive adhesive comprising the silver particles according to item 1 or 2 and a resin.
  • Item 7. A sintered body of the conductive adhesive according to item 5 or 6.
  • the present invention can provide a conductive adhesive in which silver particles are dispersed in a solvent, the silver particles having good fluidity and excellent shape stability after application to a component until sintering. Furthermore, the present invention can also provide a conductive adhesive containing the silver particles, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
  • the silver particles of the present invention are silver particles dispersed in a solvent.
  • the silver particles of the present invention are characterized in that a compound represented by the following general formula (1) is attached to the silver particles, and when the concentration of the silver particles in the solvent is 50% by mass, the SPAN value measured by a light transmission centrifugal sedimentation method under the following conditions is 0.1 to 5.0.
  • the silver particles of the present invention exhibit good fluidity and excellent shape stability after application to a member until sintering.
  • the silver particles, conductive adhesive, sintered body of the conductive adhesive, and electronic components having the sintered body between members of the present invention are described in detail below.
  • R 1 is an alkyl group having 1 to 5 carbon atoms
  • R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.
  • SPAN (V90-V10)/V50...Equation (1)
  • the sedimentation velocity is shown as a cumulative distribution, The settling velocity of 10% of the integrated value is V10.
  • the sedimentation velocity at 90% of the integrated value is V90.
  • the sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
  • a measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass.
  • the solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less.
  • 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds.
  • Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm.
  • Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
  • a numerical value connected with “ ⁇ ” means a numerical range that includes the numerical values before and after " ⁇ " as the lower and upper limits.
  • the silver particles of the present invention are particles containing silver.
  • a compound represented by the above general formula (1) (hereinafter, may be referred to as compound (1)) is attached to the surface of the silver particles. That is, the silver particles of the present invention have a structure in which compound (1) is attached to the surface of a particle composed of silver.
  • the silver particles of the present invention have a SPAN: (V90 - V10) / V50 value of 0.1 or more and 5.0 or less, measured by the light transmission centrifugal sedimentation method under the above conditions.
  • the SPAN: (V90 - V10) / V50 value measured by the light transmission centrifugal sedimentation method correlates with the particle size distribution of the secondary particles of the silver particles, and it can be said that the smaller the SPAN: (V90 - V10) / V50 value, the narrower the particle size distribution of the secondary particles of the silver particles.
  • the SPAN: (V90 - V10) / V50 value of the silver particles to which compound (1) is attached is within a specific range of 0.1 to 5.0, and therefore it can be evaluated that the particle size distribution of the secondary particles of the silver particles is within an appropriate range, further aggregation of the secondary particles is suppressed, and the secondary particles are appropriately dispersed in the solvent.
  • the value of SPAN: (V90-V10)/V50 of the silver particles of the present invention is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.4 or more. It is also preferably 5.0 or less, more preferably 4.9 or less, even more preferably 4.8 or less, and particularly preferably 4.7 or less. Preferred ranges include 0.1 to 5.0, 0.2 to 4.9, 0.3 to 4.8, and 0.4 to 4.7.
  • the method for setting the value of the SPAN: (V90-V10)/V50 of the silver particles within the specific range of 0.1 to 5.0 is not particularly limited, but for example, as described below, it can be adjusted by the refining solvent (washing solvent) used in the production of the silver particles and the washing method when using the refining solvent, the solvent used when replacing the amine compound on the surface of the silver particles with an acid (protecting group) (i.e., compound (1)), the selection of the dispersion solvent and the method of dispersing into the dispersion solvent, and the centrifugation conditions during the production of the silver particles when concentration is required.
  • the refining solvent washing solvent
  • the solvent used when replacing the amine compound on the surface of the silver particles with an acid (protecting group) i.e., compound (1)
  • the selection of the dispersion solvent and the method of dispersing into the dispersion solvent i.e., compound (1)
  • the refining solvent needs to be selected depending on the particle size and the protective group, and if an appropriate solvent is not used, the particle size distribution of the secondary particles may be broadened when a high-concentration dispersion is made, or extremely large secondary particles may be generated.
  • the centrifugation conditions also affect the secondary particles if an excessively strong load G is applied.
  • the average particle size (primary particle size) of the silver particles is, for example, 600 nm or less, preferably 580 nm or less, more preferably 560 nm or less, and even more preferably 550 nm or less, and is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 65 nm or more, with preferred ranges being 50 to 600 nm, 60 to 580 nm, and 65 to 550 nm.
  • the average particle size (primary particle size) of silver particles is the volume-based average particle size measured for 200 randomly selected particles using image analysis software (e.g., Macview (manufactured by Mountec Co., Ltd.)) for SEM images.
  • image analysis software e.g., Macview (manufactured by Mountec Co., Ltd.)
  • SED mode secondary electron detector
  • the vertical direction of the SEM image is set to a width that includes 200 or more silver particles (usually about 200 to 300 particles).
  • the volume-based average particle size is a value measured assuming that the particles observed in the SEM image are spherical with that diameter. Specific measurement methods are as described in the Examples.
  • the silver particles of the present invention have at least one exothermic peak observed in a thermogravimetric differential thermal analysis in the range of 120 to 300°C, more preferably at least one in the range of 120 to 160°C, and even more preferably at least one in the range of 160 to 300°C. Note that typically, one of these exothermic peaks is observed in these ranges.
  • the dry powder of silver particles of the present invention preferably exhibits a weight loss rate of 1.5% or less by weight when heated from 30°C to 500°C by thermogravimetric differential thermal analysis, and more preferably 0.05 to 1.3% by weight.
  • the method of thermogravimetric differential thermal analysis is as follows.
  • TG-DTA Thermogravimetric Differential Thermal Analysis
  • the silver content of the silver particles of the present invention is preferably 95% by mass or more, and more preferably 98% by mass or more.
  • the silver particles of the present invention have compound (1) attached to their surfaces. That is, the silver particles of the present invention are surface-treated with a treatment solution containing compound (1) (surface-treated silver particles). Compound (1) adheres to the surfaces of the silver particles and forms a protective layer.
  • the compound (1) there are no particular limitations on the compound (1) as long as it adheres to the surface of the silver particles and can set the SPAN: (V90-V10)/V50 value within the specific range.
  • the silver particles have a protective layer. Specifically, the silver particles have a protective layer on the surface of the particles composed of silver.
  • the protective layer also contains a compound represented by the general formula (1).
  • the conductive adhesive of the present invention contains a compound represented by the general formula (1) in the protective layer, so that the silver particles have good dispersibility in the solvent, and a sintered body with a small specific resistance value can be obtained.
  • R 1 is an alkyl group having 1 to 5 carbon atoms, and from the viewpoint of more suitably exerting the effects of the present invention, it is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 carbon atom (i.e., a methyl group).
  • R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and from the viewpoint of more suitably exerting the effects of the present invention, it is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 carbon atom (i.e., a methyl group), and particularly preferably an alkyl group having 1 carbon atom (i.e., a methyl group). That is, among the compounds represented by the general formula (1), 2-hydroxyisobutyric acid and lactic acid (L-, D-, and DL-forms) are particularly preferred, and 2-hydroxyisobutyric acid is most preferred.
  • the compound represented by the general formula (1) contained in the protective layer may be one type or two or more types.
  • the amount of compound (1) attached to the silver particles of the present invention is not particularly limited, but is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and the lower limit is preferably 0.05% by mass or more, assuming that the mass of the silver particles is 100% by mass.
  • the content of compound (1) attached to the silver particles can be measured by thermogravimetric differential thermal analysis.
  • the protective layer may also contain a compound different from the compound represented by general formula (1).
  • the different compound include amine compounds, fatty acids, and hydroxy fatty acids (however, hydroxy fatty acids different from the compound represented by general formula (1)).
  • the different compound contained in the protective layer may be one type, or two or more types.
  • the amine compound is not particularly limited, but is preferably an alkylamine having an alkyl group with 3 to 18 carbon atoms, and more preferably an alkylamine having an alkyl group with 4 to 12 carbon atoms.
  • alkylamines include ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, isoamylamine, tert-amylamine, 3-pentylamine, n-amylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n-aminoundecane, n-dodecylamine, and n-tridecylamine.
  • amines examples include dibutylamine, which is a secondary amine, and cycloalkylamines such as cyclopropylamine, cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, and 2-(2-aminoethylamino)ethanol.
  • dibutylamine which is a secondary amine
  • cycloalkylamines such as cyclopropylamine, cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, and 2-(2-aminoethylamino)ethanol.
  • the amount of the amine compound attached is also appropriately adjusted, as in the case of compound (1).
  • the specific amount of the amine compound attached is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, with the mass of the silver particles being 100% by mass, and the lower limit is preferably 0.01% by mass or more.
  • the content of fatty acids and hydroxy fatty acids attached to the silver particles can be measured by differential thermal analysis.
  • fatty acids, hydroxy fatty acids, etc. may be attached to the surface of the silver particles.
  • the fatty acids are not particularly limited, but are preferably fatty acids having an alkyl group with 3 to 18 carbon atoms, and more preferably fatty acids having an alkyl group with 4 to 18 carbon atoms.
  • Preferred examples of fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, ⁇ -linolenic acid, etc.
  • fatty acids include cyclic alkyl carboxylic acids such as cyclohexane carboxylic acid.
  • Hydroxy fatty acids that can be used include compounds having 3 to 24 carbon atoms and one or more hydroxyl groups (for example, one).
  • hydroxy fatty acids examples include 2-hydroxydecanoic acid, 2-hydroxydodecanoic acid, 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyeicosanoic acid, 2-hydroxydocosanoic acid, 2-hydroxytricosanoic acid, 2-hydroxytetracosanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, and 3-hydroxydodecanoic acid.
  • fatty acids examples include hydroxy fatty acids having 4 to 18 carbon atoms and one hydroxyl group at a position other than the ⁇ position (particularly the 12th position), and more preferably hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid.
  • the fatty acids and hydroxy fatty acids may each be used alone or in combination of two or more.
  • the amount of fatty acid or hydroxy fatty acid attached is appropriately adjusted, as in compound (1).
  • the specific amount of fatty acid or hydroxy fatty acid attached is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, with the mass of the silver particles being 100% by mass, and the lower limit is preferably 0.01% by mass or more.
  • the content of fatty acid or hydroxy fatty acid attached to the silver particles can be measured by differential thermal analysis.
  • compound (1) an amine compound, a fatty acid, and a hydroxy fatty acid may be used in combination, or other compounds different from these may be attached to the surface of the silver particles, as long as compound (1) is attached to the surface and the above-mentioned SPAN: (V90-V10)/V50 value is satisfied.
  • the silver particles of the present invention are dispersed in a solvent. That is, the silver particles are present in a state of being dispersed in the solvent.
  • a solvent There are no particular limitations on the solvent, so long as the solvent has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less.
  • the solvent include diethylene glycol monohexyl ether (Log Pow: 1.7), texanol (Log Pow: 3.2), isopropyl alcohol (Log Pow: 0.05), ⁇ -terpineol (Log Pow: 2.98), diethylene glycol (Log Pow: -1.98), ethylene glycol (Log Pow: -1.36), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), butyl carbitol (Log Pow: 0.56), butyl carbitol acetate (Log Pow: 2.9), butanediol (Log Pow: -0.34), etc.
  • the solvent may be one type or two or more types, but preferably one type.
  • the concentration of the silver particles of the present invention in the solvent is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and is preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 92% by mass or less, with preferred ranges including 80 to 95% by mass, 85 to 93% by mass, and 88 to 92% by mass.
  • the concentration is adjusted to 50% by mass and the measurement is performed.
  • a composition for producing silver particles (silver particle preparation composition) is prepared. Specifically, the silver compound that is the raw material for the silver particles, compound (1) to be attached to the surface of the silver particles, and solvents to be used in each step (solvents used in synthesizing the silver particles, solvents for purifying the silver particles, solvents used when replacing with compound (1), etc.) are prepared.
  • the silver particles are synthesized through a process of synthesizing silver particles from a silver compound, a process of replacing the amine compound on the surface of the silver particles with an acid (protecting group) (i.e., compound (1)) described below, and the separation of the silver particles may be included during or between each process.
  • an acid protecting group
  • preferred silver compounds include silver nitrate and silver oxalate, with silver oxalate being particularly preferred.
  • the solvent used when synthesizing silver particles from a silver compound is not particularly limited as long as silver particles are synthesized, but it is preferable that the solvent contains a polar organic solvent.
  • polar organic solvents include ketones such as acetone, acetylacetone, and methyl ethyl ketone; ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, and 1,4-dioxane; diols such as 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentan
  • Alcohols such as linear or branched alcohols, cyclohexanol, 3-methoxy-3-methyl-1-butanol, and 3-methoxy-1-butanol; fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, ethyl formate, and texanol; polyethylene glycol, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether.
  • fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, ethyl formate, and texan
  • glycol monohexyl ether ethylene glycol monooctyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, polypropylene glycol, propylene glycol monopropyl ether,
  • glycols or glycol ethers include pyrene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl
  • linear or branched alcohols having 3 to 5 carbon atoms, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, terpineol, and texanol are preferred.
  • the solvent may further contain a non-polar or hydrophobic solvent in addition to the polar organic solvent.
  • non-polar organic solvents include linear, branched, or cyclic saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, 2-ethylhexane, and cyclohexane; alcohols such as linear or branched alcohols having 6 or more carbon atoms; aromatic compounds such as benzene, toluene, and benzonitrile; halogenated hydrocarbons such as dichloromethane, chloroform, and dichloroethane; methyl-n-amyl ketone; methyl ethyl ketone oxime; and triacetin.
  • saturated hydrocarbons and linear or branched alcohols having 6 or more carbon atoms are preferred, and hexane, octane, decane, octanol, decanol, and dodecanol are more preferred.
  • the solvents can be used alone or in combination of two or more.
  • a silver compound, compound (1), and a solvent are mixed to obtain a composition for preparing silver particles.
  • the ratio of each component in the composition is adjusted as appropriate.
  • the content of silver oxalate in the composition is preferably about 20 to 70% by mass relative to the total amount of the composition.
  • the content of compound (1) is preferably about 5 to 55% by mass relative to the total amount of the composition.
  • the content of the fatty acid is preferably about 0.1 to 20% by mass relative to the total amount of the composition.
  • the content of the hydroxy fatty acid is preferably about 0.1 to 15% by mass relative to the total amount of the composition.
  • the means for mixing the components is not particularly limited, and they can be mixed using general-purpose equipment such as a mechanical stirrer, magnetic stirrer, vortex mixer, planetary mill, ball mill, three-roll mill, line mixer, planetary mixer, dissolver, etc.
  • general-purpose equipment such as a mechanical stirrer, magnetic stirrer, vortex mixer, planetary mill, ball mill, three-roll mill, line mixer, planetary mixer, dissolver, etc.
  • the composition for preparing silver particles is reacted in a reaction vessel, usually by heating, causing a thermal decomposition reaction of the silver compound to produce silver particles.
  • the composition may be introduced into a reaction vessel that has been heated in advance, or the composition may be introduced into the reaction vessel and then heated.
  • the reaction temperature may be any temperature at which the thermal decomposition reaction proceeds and silver particles are produced, for example, about 50 to 250°C.
  • the reaction time may be appropriately selected according to the desired average particle size and the composition of the composition corresponding to that size. The reaction time may be, for example, 1 minute to 100 hours.
  • the silver particles produced by the thermal decomposition reaction are obtained as a mixture containing unreacted raw materials, so it is preferable to purify the silver particles.
  • Purification methods include solid-liquid separation methods and precipitation methods that utilize the difference in specific gravity between the silver particles and unreacted raw materials such as organic solvents.
  • Solid-liquid separation methods include filter filtration, centrifugal separation, cyclone, and decanter methods.
  • the mixture containing the silver particles may be diluted with a low-boiling point solvent such as acetone or methanol to adjust its viscosity.
  • the average particle size (primary particle size) of the resulting silver particles can be adjusted by adjusting the composition of the silver particle manufacturing composition and the reaction conditions.
  • the refining solvent from the viewpoint of setting the value of SPAN: (V90-V10)/V50 within the specific range, it is preferable to use n-propanol, 1-butanol, or the like as the refining solvent.
  • the selection of the refining solvent affects the value of SPAN: (V90-V10)/V50 of the silver particles of the present invention.
  • Silver particles (with amine compounds attached to the surface) once synthesized by the above method are prepared and dispersed in a solvent.
  • the solvent include the same as those exemplified as the solvent used in the silver particle synthesis process, but it is preferable to use ethanol, n-propanol, isopropyl alcohol, 1-butanol, etc.
  • the selection of the solvent used when replacing and adjusting the compound (1) on the silver particle surface affects the value of the SPAN: (V90-V10)/V50 of the silver particles of the present invention.
  • another compound (1) is added in an amount of 0.1 to 5 times the mass of the silver particles, and the mixture is stirred at room temperature to 80° C.
  • the amine compounds attached to the silver particle surface can be replaced with compound (1).
  • the silver particles with the amine compounds on the surface replaced with compound (1) can be recovered by the above solid-liquid separation method, etc.
  • the solvent used in this solid-liquid separation it is preferable to use ethanol, n-propanol, isopropyl alcohol, 1-butanol, etc. The selection of the solvent also affects the SPAN: (V90-V10)/V50 value of the silver particles of the present invention.
  • the conductive adhesive of the present invention is characterized by containing the silver particles of the present invention. That is, the conductive adhesive of the present invention contains silver particles and a solvent. Details of the silver particles and the solvent of the present invention are as described above.
  • the conductive adhesive of the present invention may further contain a resin in addition to the silver particles and solvent of the present invention.
  • a resin in addition to the silver particles and solvent of the present invention.
  • resins used in known conductive adhesives containing silver particles can also be used in the present invention, including thermoplastic resins and thermosetting resins.
  • Thermoplastic resins include urethane resins, acrylic resins, methacrylic resins, polyvinyl alcohol resins, vinyl acetate resins, polycarbonate resins, polyorganosiloxane resins, polyamide resins, and mixtures thereof are also acceptable.
  • Thermosetting resins include epoxy resins, acrylic resins, silicone resins, urethane resins, vinyl ester resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, polyimide resins, and the like.
  • preferred solvents include diethylene glycol monohexyl ether (Log Pow: 1.7), texanol (Log Pow: 3.2), isopropyl alcohol (Log Pow: 0.05), ⁇ -terpineol (Log Pow: 2.98), diethylene glycol (Log Pow: -1.98), ethylene glycol (Log Pow: -1.36), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), butyl carbitol (Log Pow: 0.56), butyl carbitol acetate (Log Pow: 2.9), butanediol (Log Pow: -0.34), and the like.
  • Particularly preferred solvents are diethylene glycol monohexyl ether (Log Pow: 1.7), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), and Texanol (Log Pow: 3.2).
  • the conductive adhesive of the present invention further contains a solvent, the conductive adhesive may contain one type of solvent or two or more types of solvents.
  • the content of silver particles in the conductive adhesive of the present invention is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 88% by mass or more, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 92% by mass or less, with preferred ranges including 80-95% by mass, 85-93% by mass, and 88-92% by mass.
  • the content of the resin in the conductive adhesive of the present invention is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, and is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 3% by mass or less, with preferred ranges including 0.001-10% by mass, 0.005-7% by mass, and 0.01-3% by mass.
  • Sintered body of conductive adhesive The sintered body of the conductive adhesive of the present invention can be obtained by sintering the conductive adhesive of the present invention described in detail in "3. Conductive adhesive" above.
  • the sintered body of the conductive adhesive of the present invention most of the components (compound (1) etc.), solvent and resin attached to the surface of the silver particles are removed by the high heat during sintering, and the sintered body is essentially composed of silver.
  • the sintering temperature is not particularly limited, but may be, for example, 250°C or lower, preferably about 150°C to 250°C, and more preferably about 200°C to 250°C.
  • the sintering time is preferably about 0.4 hours to 2.0 hours, and more preferably about 0.5 hours to 1.2 hours.
  • Pressurization may or may not be applied during sintering of the conductive adhesive of the present invention. If pressurization is applied, the pressure is, for example, about 10 to 30 MPa.
  • Sintering may be performed in an atmosphere of air, inert gas (nitrogen gas, argon gas), or the like.
  • the sintering means is not particularly limited, and may be, for example, an oven, a hot air drying furnace, an infrared drying furnace, laser irradiation, flash lamp irradiation, microwave, etc.
  • the electronic components of the present invention have a portion in which components are bonded together by the sintered body of the present invention. That is, the electronic components of the present invention are formed by disposing the conductive adhesive of the present invention, which is described in detail in "3. Conductive Adhesive" above, between components of the electronic components (e.g., between components included in a circuit) and sintering the conductive adhesive to bond the components together.
  • Silver particles were produced using the following procedure. When a larger quantity was required for evaluation, the required sample amount was prepared by increasing the number of trials in the same manner.
  • Example 1 Synthesis of Silver Particles 1
  • Silver particles 1 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 1.
  • the glass centrifuge tube was then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C. for 30 minutes, and further stirred at 90° C. for 30 minutes. After cooling, the magnetic stirrer was removed, 15 g of ethanol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600 ⁇ G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube.
  • HHE-19G-U manufactured by Koike Precision Machinery Works
  • Example 2 Synthesis of silver particles 2
  • Silver particles 2 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 2. Thereafter, the glass centrifuge tube was placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C.
  • HHE-19G-U manufactured by Koike Precision Machinery Works
  • Example 3 Synthesis of silver particles 3
  • Silver particles 4 dispersed in a solvent were produced by the following procedure. 2-(2-aminoethylamino)ethanol (1.74 g) and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer, and the mixture was stirred for about 1 minute. Then, silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 4. The glass centrifuge tubes were then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and the mixture was stirred at 40°C for 30 minutes, and further stirred at 90°C for 30 minutes.
  • HHE-19G-U manufactured by Koike Precision Machinery Works
  • Comparative Example 1 Synthesis of Silver Particles 4
  • Silver particles 6 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 6. The glass centrifuge tube was then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C.
  • HHE-19G-U manufactured by Koike Precision Machinery Works
  • 2-hydroxyisobutyric acid was added in an amount 0.5 times the mass of the silver particles using the obtained dispersion of silver particles (isopropyl alcohol solution), and the mixture was stirred at room temperature for 2 hours.
  • the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer.
  • the mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600 ⁇ G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube.
  • the steps of adding 15 g of diethylene glycol monohexyl ether, stirring, centrifugation, and removing the supernatant were repeated twice to recover silver particles 4.
  • volume-based average particle size For each SEM image (width 1-20 ⁇ m) obtained in the above ⁇ Observation by electron microscope>, the volume-based average particle size (primary particle size) of 200 randomly selected particles was measured using image analysis software (MacView (Mountec)). A range of width 1-20 ⁇ m was observed in the vertical direction of the SEM image. Note that the vertical direction of the SEM image is set to a width that includes 200 or more silver particles (usually about 200-300 particles) in a range of width 1-20 ⁇ m. Note that the volume-based average particle size is a value measured assuming that the particles observed in the SEM image are spherical with that diameter. The results are shown in Table 1.
  • SPAN (V90-V10)/V50 Formula (1)
  • the sedimentation velocity of 10% of the integrated value is V10.
  • the sedimentation velocity at 90% of the integrated value is V90.
  • the sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
  • a measurement sample was prepared in which the concentration of silver particles in the solvent was 50% by mass.
  • the solvent used for the measurement sample was a solvent with an octanol/water distribution coefficient (Log Pow) of -2 to 4.
  • Each silver particle (1 to 4) was dispensed into a 50 ml vial, and silver particles 1 and 2 were diluted with 2-ethyl-1,3-hexanediol, and silver particles 3 and 4 were diluted with diethylene glycol monohexyl ether to a total of 100%, with 50% silver and 50% solvent by mass.
  • a vortex mixer was used for kneading, and the mixture was dispersed at 2000 rpm for 2 minutes.
  • the particles are not visibly dispersed (solids remain) at this time, they may be roughly kneaded using a spatula or the like, or dispersed using a planetary rotation mixer.
  • a planetary rotation mixer When using a planetary rotation mixer, the rotation and revolution should be balanced to prevent the particles from settling.
  • the solvent in which the silver particles are dispersed should be used as a diluent to prepare the measurement sample. If the dispersion contains multiple solvents, multiple solvents may be used and should be diluted in an equal volume ratio to the dispersion.
  • SPAN ((V90-V10)/V50) was measured using a dispersibility evaluation/particle size distribution device LS-610 manufactured by LUM Japan. Specifically, 0.2 ml of the measurement sample was filled into a glass cell (glass cell with an optical path length of 2 mm), rotated at a low speed at 25° C. with a centrifugal acceleration of 130 G, and data for 500 points was obtained at intervals of 5 seconds. Then, the cell was rotated at a high speed with a centrifugal acceleration of 1160 G, and data for 500 points was obtained at intervals of 5 seconds.
  • the LightFactor is not set to 6, the light intensity is insufficient due to the nature of the measurement object, which is a high-concentration metal particle dispersion. Therefore, in order to measure the secondary particle state of a high-concentration particle dispersion, it is necessary to set it to 6.
  • attention must be paid to the light source of the measurement device.
  • nodes analysis widths
  • a reasonable number of points cannot be obtained as the number of measurement profiles (number of measurement points), so it is necessary to analyze the nodes so that they do not overlap. The measurement results are shown in Table 1.
  • each silver particle (1 to 4) was taken into a 50 ml vial, and silver particle 5 was added so that the silver content was equal.
  • silver particles 1 and 2 2-ethyl-1,3-hexanediol was used, and for silver particles 3 and 4, diethylene glycol monohexyl ether was used to adjust the silver content to 90 mass % and the solvent to 10 mass % to a total of 100%, to obtain each paste.
  • the paste was kneaded for 30 seconds using a rotation/revolution type kneader (Mazerustar KK-400W manufactured by Kurabo Industries, Ltd.) under the condition of 1340/1340 rpm.
  • kneading may be performed manually using a spatula or the like. This was filtered through a mesh with an opening of 100 ⁇ m, and 10 g was filled into a barrel (PS05N manufactured by Iwashita Engineering Co., Ltd.) and sealed. Using the above kneader, the barrel filled with the silver paste was stirred and degassed under the same conditions for 60 seconds, and further left for 12 hours after stirring to obtain a fluidity test sample. The fluidity of the silver paste was evaluated using an air pulse dispenser (AD3300C manufactured by Iwashita Engineering). The discharge pressure was adjusted by a regulator and adjusted in the range of 20 kPa to 100 kPa.
  • discharge Weight Maintenance Rate The discharge weight maintenance rate was calculated as B/A*100% by mass from the weight A of the line pattern on the printed substrate at the beginning of printing (weight of silver paste for 100 points in g) and the weight B of the line pattern on the printed substrate at the end after 1 hour (weight of silver paste for 100 points in g).
  • discharge weight maintenance rate is based on 100% by mass, those below 50% were marked with ⁇ , those at 50% or more with ⁇ , and those at 85% or more with ⁇ .
  • the shape stability of each of the obtained silver particles 1 to 4 was evaluated by the following method. The results are shown in Table 1.
  • the shape stability of the silver paste was evaluated by preparing a sample in the same manner as in the fluidity test, and using an air pulse dispenser (AD3300C manufactured by Iwashita Engineering Co., Ltd.). The discharge pressure was adjusted by a regulator to a range of 20 kPa to 100 kPa. In addition, all tests were performed using temperature control, after adjusting the barrel temperature (paste temperature) to 25°C.
  • a precision nozzle with a nozzle diameter of 0.27 mm ⁇ was set in a barrel (PS05N manufactured by Iwashita Engineering Co., Ltd.) filled with 10 g of silver paste, and set in the dispenser.
  • the distance from the nozzle tip to the printed material (glass substrate) was set to 100 ⁇ m.
  • a line pattern of 5 mm was printed on the printed material at equal intervals. It was set so that printing of the next line pattern would start 1 second after printing of the line pattern was completed. In this way, the printing was moved to the next printed material every time a 100-point line pattern was printed, and printing was continued for 1 hour.

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Abstract

Provided are silver particles which exhibit favorable fluidity and excellent shape stability after being coated onto a member until sintering occurs as a conductive adhesive obtained by dispersing the silver particles in a solvent.　Silver particles which are dispersed in a solvent, wherein a compound represented by general formula (1) is adhered to the surface of the silver particles [in general formula (1), R1 is a C1-5 alkyl group, and R2 is a hydrogen atom or a C1-5 alkyl group].　The silver particles have a SPAN value of 0.1-5.0, inclusive, when measured according to a light transmission-type centrifugal sedimentation method under the following conditions and when the concentration of the silver particles in the solvent is 50 mass%. Formula (1) SPAN: (V90-V10)/V50. When the sedimentation rate is expressed as a cumulative distribution, the sedimentation rate which is 10% of the integrated value is V10. Meanwhile, the sedimentation rate which is 90% of the integrated value is V90. The sedimentation rate which is 50% of the integrated value is V50 (median sedimentation rate).

Description

銀粒子Silver particles
　本発明は、銀粒子、導電性接着剤、当該導電性接着剤の焼結体、及び当該焼結体を部材間に備えている電子部品に関する。 The present invention relates to silver particles, a conductive adhesive, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
　ダイボンド剤等を始めとする導電性接着剤は、半導体、ＬＥＤ、パワー半導体等の電子部品に使われる接合材料である。接合方式として、加圧と加熱による接合、もしくは無加圧で加熱等による焼結によって基材と接合させることが一般に知られている。近年、製造プロセスの簡便さや効率の観点から、無加圧方式の接合材料の開発が進んでいる。 Conductive adhesives, including die bonding agents, are bonding materials used in electronic components such as semiconductors, LEDs, and power semiconductors. Generally, bonding methods involve bonding with pressure and heat, or sintering with heat without pressure to bond to the base material. In recent years, development of pressureless bonding materials has progressed from the perspective of the simplicity and efficiency of the manufacturing process.
　近年、銀粒子を含む導電性接着剤の開発が進んでいる。銀粒子は、低温で短時間の熱処理で容易に焼結する特徴がある。例えば、特許文献１には、銀粒子からなる固形分と溶媒とを混練してなる金属ペーストにおいて、前記固形分が、粒径１００～２００ｎｍの銀粒子を粒子数基準で３０％以上含む銀粒子で構成されており、更に、固形分を構成する銀粒子は、保護剤として炭素数の総和が４～８のアミン化合物が結合した金属ペーストが開示されている。当該金属ペーストによれば、低温域で銀粒子を焼結させることができ、その上で抵抗の低い焼結体や熱伝導性に優れた焼結体を形成可能とされている。 In recent years, the development of conductive adhesives containing silver particles has progressed. Silver particles have the characteristic of being easily sintered by short-term heat treatment at low temperatures. For example, Patent Document 1 discloses a metal paste made by kneading a solid content of silver particles with a solvent, in which the solid content is made of silver particles containing 30% or more silver particles with a particle size of 100 to 200 nm based on the particle number, and further, the silver particles that make up the solid content are bonded to an amine compound with a total carbon number of 4 to 8 as a protective agent. With this metal paste, it is possible to sinter the silver particles at a low temperature range, and it is possible to form a sintered body with low resistance and excellent thermal conductivity.
特開２０１５－１５９０９６号公報JP 2015-159096 A
　銀粒子を含む導電性接着剤は、銀粒子が溶媒中に分散されたものであり、部材（例えば、電子部品に使用される基板、半導体チップ等）の表面に塗布し、焼結させることで、部材同士を接着することができる。 Conductive adhesives containing silver particles have silver particles dispersed in a solvent, and can be applied to the surfaces of components (such as substrates used in electronic components, semiconductor chips, etc.) and sintered to bond the components together.
　このような導電性接着剤は、ディスペンサーなどを用いて部材表面に塗布することから、導電性接着剤が良好な流動性を備えることが望ましい。 Since such conductive adhesives are applied to the surface of components using a dispenser or the like, it is desirable for the conductive adhesive to have good fluidity.
　さらに、部材同士を精度高く接着する観点などから、導電性接着剤は、部材に塗布した後、焼結させる前までの形状安定性に優れていることが望ましい。 Furthermore, from the perspective of bonding components together with high precision, it is desirable for the conductive adhesive to have excellent shape stability after it is applied to the components and before it is sintered.
　本発明は、銀粒子が溶媒中に分散された導電性接着剤であって、良好な流動性と、部材に塗布した後、焼結に供されるまでの形状安定性とに優れた銀粒子を提供することを主な目的とする。さらに、本発明は、当該銀粒子を含む導電性接着剤、当該導電性接着剤の焼結体、及び当該焼結体を部材間に備えている電子部品を提供することも目的とする。 The main object of the present invention is to provide a conductive adhesive in which silver particles are dispersed in a solvent, the silver particles having good fluidity and excellent shape stability after application to a component until sintering. Furthermore, the present invention also aims to provide a conductive adhesive containing the silver particles, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
　本発明者は、上記の課題を解決すべく鋭意検討を行った。具体的には、本発明者は、銀粒子について、従来検討がなされているものではなく、溶媒に分散された銀粒子の二次粒子の粒度分布に着目した。そして、溶媒に分散された銀粒子について、所定条件の光透過式遠心沈降法によって測定される、ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を特定の範囲内に設定すると、前述した良好な流動性と形状安定性とが両立されるという新規な知見を得た。本発明は、このような知見に基づいて、さらに検討を重ねることにより完成したものである。 The inventors have conducted intensive research to solve the above problems. Specifically, the inventors have focused on the particle size distribution of secondary particles of silver particles dispersed in a solvent, rather than on silver particles that have been previously studied. They have made the novel discovery that when the value of SPAN: (V90-V10)/V50, measured by a light transmission centrifugal sedimentation method under specified conditions, for silver particles dispersed in a solvent is set within a specific range, the aforementioned good fluidity and shape stability are both achieved. The present invention was completed based on this discovery and through further research.
　即ち、本発明は、下記に掲げる態様の発明を提供する。
項１．　溶媒に分散されてなる銀粒子であって、
　前記銀粒子の表面に下記一般式（１）で表される化合物が付着しており、
Figure JPOXMLDOC01-appb-C000003
 ［一般式（１）中、Ｒ1は炭素数が１～５のアルキル基であり、Ｒ2は水素原子であるか、炭素数が１～５のアルキル基である。］
　前記銀粒子の前記溶媒中の濃度を５０質量％とした場合、下記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮの値が、０．１以上５．０以下である、銀粒子。
ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
沈降速度を累積分布で示した際、
積算値の１０％の沈降速度はＶ１０である。
積算値の９０％の沈降速度はＶ９０である。
積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。
（ＳＰＡＮの測定条件）
　前記銀粒子の前記溶媒中の濃度が５０質量％である測定用試料を用意する。前記測定用試料の前記溶媒としては、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下であるものを用いる。前記測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離とその移動に要した時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出する。
項２．　前記銀粒子の平均粒子径が５０～６００ｎｍである、項１に記載の銀粒子。
項３．　銀粒子が溶媒に分散されてなる銀粒子分散液であって、
　前記銀粒子の表面に下記一般式（１）で表される化合物が付着しており、
Figure JPOXMLDOC01-appb-C000004
 ［一般式（１）中、Ｒ1は炭素数が１～５のアルキル基であり、Ｒ2は水素原子であるか、炭素数が１～５のアルキル基である。］
　前記銀粒子の前記溶媒中の濃度を５０質量％とした場合、下記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮの値が、０．１以上５．０以下である、銀粒子分散液。
ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
沈降速度を累積分布で示した際、
積算値の１０％の沈降速度はＶ１０である。
積算値の９０％の沈降速度はＶ９０である。
積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。
（ＳＰＡＮの測定条件）
　前記銀粒子の前記溶媒中の濃度が５０質量％である測定用試料を用意する。前記測定用試料の前記溶媒としては、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下であるものを用いる。前記測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離とその移動に要した時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出する。
項４．　前記銀粒子の平均粒子径が５０～６００ｎｍである、項３に記載の銀粒子分散液。
項５．　項１又は２に記載の銀粒子を含む導電性接着剤。
項６．　項１又は２に記載の銀粒子と、樹脂と、を含む導電性接着剤。
項７．　項５又は６に記載の導電性接着剤の焼結体。
項８．　項７に記載の焼結体によって部材間が接合されてなる電子部品。 That is, the present invention provides the following aspects.
Item 1. Silver particles dispersed in a solvent,
A compound represented by the following general formula (1) is attached to the surface of the silver particles,
Figure JPOXMLDOC01-appb-C000003
 [In the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]
Silver particles, wherein when a concentration of the silver particles in the solvent is 50% by mass, the SPAN value measured by a light transmission centrifugal sedimentation method under the following conditions is 0.1 or more and 5.0 or less.
SPAN: (V90-V10)/V50...Equation (1)
When the sedimentation velocity is shown as a cumulative distribution,
The settling velocity of 10% of the integrated value is V10.
The sedimentation velocity at 90% of the integrated value is V90.
The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
(SPAN measurement conditions)
A measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass. The solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less. 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds. Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm. Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
Item 2. The silver particles according to Item 1, wherein the average particle size of the silver particles is 50 to 600 nm.
Item 3. A silver particle dispersion liquid in which silver particles are dispersed in a solvent,
A compound represented by the following general formula (1) is attached to the surface of the silver particles,
Figure JPOXMLDOC01-appb-C000004
 [In the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]
A silver particle dispersion liquid having a SPAN value of 0.1 or more and 5.0 or less, when the concentration of the silver particles in the solvent is 50% by mass, as measured by a light transmission centrifugal sedimentation method under the following conditions:
SPAN: (V90-V10)/V50...Equation (1)
When the sedimentation velocity is shown as a cumulative distribution,
The settling velocity of 10% of the integrated value is V10.
The sedimentation velocity at 90% of the integrated value is V90.
The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
(SPAN measurement conditions)
A measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass. The solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less. 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds. Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm. Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
Item 4. The silver particle dispersion liquid according to Item 3, wherein the average particle size of the silver particles is 50 to 600 nm.
Item 5. A conductive adhesive comprising the silver particles according to item 1 or 2.
Item 6. A conductive adhesive comprising the silver particles according to item 1 or 2 and a resin.
Item 7. A sintered body of the conductive adhesive according to item 5 or 6.
Item 8. An electronic component in which members are joined together by the sintered body according to item 7.
　本発明によれば、銀粒子が溶媒中に分散された導電性接着剤であって、良好な流動性と、部材に塗布した後、焼結に供されるまでの形状安定性とに優れた銀粒子を提供することができる。さらに、本発明によれば、当該銀粒子を含む導電性接着剤、当該導電性接着剤の焼結体、及び当該焼結体を部材間に備えている電子部品を提供することもできる。 The present invention can provide a conductive adhesive in which silver particles are dispersed in a solvent, the silver particles having good fluidity and excellent shape stability after application to a component until sintering. Furthermore, the present invention can also provide a conductive adhesive containing the silver particles, a sintered body of the conductive adhesive, and an electronic component having the sintered body between components.
　本発明の銀粒子は、溶媒に分散されてなる銀粒子である。本発明の銀粒子においては、下記一般式（１）で表される化合物が付着しており、銀粒子の溶媒中の濃度を５０質量％とした場合、下記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮの値が、０．１以上５．０以下であることを特徴とする。本発明の銀粒子は、当該特徴を備えることにより、良好な流動性と、部材に塗布した後、焼結に供されるまでの形状安定性とに優れるという特性が発揮される。以下、本発明の銀粒子、導電性接着剤、当該導電性接着剤の焼結体、及び当該焼結体を部材間に備えている電子部品について詳述する。 The silver particles of the present invention are silver particles dispersed in a solvent. The silver particles of the present invention are characterized in that a compound represented by the following general formula (1) is attached to the silver particles, and when the concentration of the silver particles in the solvent is 50% by mass, the SPAN value measured by a light transmission centrifugal sedimentation method under the following conditions is 0.1 to 5.0. By having this characteristic, the silver particles of the present invention exhibit good fluidity and excellent shape stability after application to a member until sintering. The silver particles, conductive adhesive, sintered body of the conductive adhesive, and electronic components having the sintered body between members of the present invention are described in detail below.
Figure JPOXMLDOC01-appb-C000005
 ［一般式（１）中、Ｒ1は炭素数が１～５のアルキル基であり、Ｒ2は水素原子であるか、炭素数が１～５のアルキル基である。］
Figure JPOXMLDOC01-appb-C000005
 [In the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]
ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
沈降速度を累積分布で示した際、
積算値の１０％の沈降速度はＶ１０である。
積算値の９０％の沈降速度はＶ９０である。
積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。
（ＳＰＡＮの測定条件）
　前記銀粒子の前記溶媒中の濃度が５０質量％である測定用試料を用意する。前記測定用試料の前記溶媒としては、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下であるものを用いる。前記測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離とその移動に要した時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出する。 SPAN: (V90-V10)/V50...Equation (1)
When the sedimentation velocity is shown as a cumulative distribution,
The settling velocity of 10% of the integrated value is V10.
The sedimentation velocity at 90% of the integrated value is V90.
The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
(SPAN measurement conditions)
A measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass. The solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less. 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds. Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm. Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
　なお、本明細書において、「～」で結ばれた数値は、「～」の前後の数値を下限値及び上限値として含む数値範囲を意味する。複数の下限値と複数の上限値が別個に記載されている場合、任意の下限値と上限値を選択し、「～」で結ぶことができるものとする。 In this specification, a numerical value connected with "~" means a numerical range that includes the numerical values before and after "~" as the lower and upper limits. When multiple lower limits and multiple upper limits are listed separately, any lower limit and upper limit can be selected and connected with "~".
１．銀粒子
　本発明の銀粒子は、銀を含む粒子である。銀粒子の表面に前記一般式（１）で表される化合物（以下、化合物（１）と表記することがある）が付着している。すなわち、本発明の銀粒子は、銀により構成された粒子の表面に化合物（１）が付着した構造を有している。 1. Silver Particles The silver particles of the present invention are particles containing silver. A compound represented by the above general formula (1) (hereinafter, may be referred to as compound (1)) is attached to the surface of the silver particles. That is, the silver particles of the present invention have a structure in which compound (1) is attached to the surface of a particle composed of silver.
　本発明の銀粒子は、前記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値が、０．１以上５．０以下である。光透過式遠心沈降法によって測定される、ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値は、銀粒子の二次粒子の粒度分布に相関しており、ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値が小さい程、銀粒子の二次粒子の粒度分布が狭いといえる。本発明においては、化合物（１）が付着した銀粒子のＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値が０．１～５．０という特定範囲内にあることで、銀粒子の二次粒子としての粒度分布が適切な範囲内にあり、二次粒子のさらなる凝集が抑制され溶媒中で適切分散されていると評価することができる。従来、銀粒子の一次粒子を制御することで、銀粒子を含む導電性接着剤の特性を調整する試みはなされてきたが、本発明においては、銀粒子の二次粒子の分散性に着目し、光透過式遠心沈降法によって測定されるＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を特定範囲に制御することで、溶媒に分散した銀粒子の良好な流動性と、部材に塗布した後、焼結に供されるまでの形状安定性とに優れるという特性を両立する。光透過式遠心沈降法の具体的な測定条件については、実施例の記載による。 The silver particles of the present invention have a SPAN: (V90 - V10) / V50 value of 0.1 or more and 5.0 or less, measured by the light transmission centrifugal sedimentation method under the above conditions. The SPAN: (V90 - V10) / V50 value measured by the light transmission centrifugal sedimentation method correlates with the particle size distribution of the secondary particles of the silver particles, and it can be said that the smaller the SPAN: (V90 - V10) / V50 value, the narrower the particle size distribution of the secondary particles of the silver particles. In the present invention, the SPAN: (V90 - V10) / V50 value of the silver particles to which compound (1) is attached is within a specific range of 0.1 to 5.0, and therefore it can be evaluated that the particle size distribution of the secondary particles of the silver particles is within an appropriate range, further aggregation of the secondary particles is suppressed, and the secondary particles are appropriately dispersed in the solvent. Previously, attempts have been made to adjust the properties of conductive adhesives containing silver particles by controlling the primary particles of the silver particles, but in this invention, attention is focused on the dispersibility of the secondary particles of silver particles, and the value of SPAN: (V90-V10)/V50 measured by the light transmission centrifugal sedimentation method is controlled within a specific range, thereby achieving both good fluidity of the silver particles dispersed in the solvent and excellent shape stability after application to a component until sintering. Specific measurement conditions for the light transmission centrifugal sedimentation method are described in the examples.
　本発明の効果を好適に発揮する観点から、本発明の銀粒子の前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値は、好ましくは０．１以上、より好ましくは０．２以上、さらに好ましくは０．３以上であり、特に好ましくは０．４以上である。また、好ましくは５．０以下、より好ましくは４．９以下、さらに好ましくは４．８以下であり、特に好ましくは４．７以下である。好ましい範囲としては、０．１～５．０、０．２～４．９、０．３～４．８、０．４～４．７などが挙げられる。 From the viewpoint of optimally exerting the effects of the present invention, the value of SPAN: (V90-V10)/V50 of the silver particles of the present invention is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and particularly preferably 0.4 or more. It is also preferably 5.0 or less, more preferably 4.9 or less, even more preferably 4.8 or less, and particularly preferably 4.7 or less. Preferred ranges include 0.1 to 5.0, 0.2 to 4.9, 0.3 to 4.8, and 0.4 to 4.7.
　本発明において、銀粒子の前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を０．１～５．０という特定範囲内に設定する方法については、特に制限されないが、例えば、後述のように、銀粒子の製造に使用する精製溶媒（洗浄溶媒）やそれを用いた際の洗浄方法、銀粒子表面のアミン化合物を酸（保護基）（すなわち、化合物（１））に置換する際に使用する溶媒、及び分散溶媒の選択やその分散溶媒への分散方法、濃縮が必要な場合は銀粒子の製造時の遠心分離条件などによって調整することができる。特に、精製溶媒は粒子径や保護基によって選択する必要があり、適切なものを使わない場合は、高濃度分散液とした際の二次粒子の粒度分布が広がったり、極端に大きな二次粒子が発生したりする場合がある。また、遠心分離条件も過度に強い負荷Ｇをかけると、同様に二次粒子へ影響を与える。加えて、弱すぎる遠心条件では二次粒子としての分布が広がる傾向もあり、粒子径や遠心分離時に用いた溶剤種によって適切な遠心分離条件を規定する必要がある。 In the present invention, the method for setting the value of the SPAN: (V90-V10)/V50 of the silver particles within the specific range of 0.1 to 5.0 is not particularly limited, but for example, as described below, it can be adjusted by the refining solvent (washing solvent) used in the production of the silver particles and the washing method when using the refining solvent, the solvent used when replacing the amine compound on the surface of the silver particles with an acid (protecting group) (i.e., compound (1)), the selection of the dispersion solvent and the method of dispersing into the dispersion solvent, and the centrifugation conditions during the production of the silver particles when concentration is required. In particular, the refining solvent needs to be selected depending on the particle size and the protective group, and if an appropriate solvent is not used, the particle size distribution of the secondary particles may be broadened when a high-concentration dispersion is made, or extremely large secondary particles may be generated. In addition, the centrifugation conditions also affect the secondary particles if an excessively strong load G is applied. In addition, there is a tendency for the distribution of secondary particles to be broadened under too weak centrifugation conditions, so it is necessary to specify appropriate centrifugation conditions depending on the particle size and the type of solvent used during centrifugation.
　また、本発明の効果を好適に発揮する観点から、銀粒子の平均粒子径（一次粒子径）は、例えば６００ｎｍ以下、好ましくは５８０ｎｍ以下、より好ましくは５６０ｎｍ以下、さらに好ましくは５５０ｎｍ以下であり、また、好ましくは５０ｎｍ以上、より好ましくは６０ｎｍ以上、さらに好ましくは６５ｎｍ以上であり、好ましい範囲としては、５０～６００ｎｍ、６０～５８０ｎｍ、６５～５５０ｎｍが挙げられる。 In addition, from the viewpoint of optimally exerting the effects of the present invention, the average particle size (primary particle size) of the silver particles is, for example, 600 nm or less, preferably 580 nm or less, more preferably 560 nm or less, and even more preferably 550 nm or less, and is preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 65 nm or more, with preferred ranges being 50 to 600 nm, 60 to 580 nm, and 65 to 550 nm.
　本発明において、銀粒子の平均粒子径（一次粒子径）は、ＳＥＭ画像について、画像解析ソフト（例えば、Ｍａｃｖｉｅｗ（マウンテック社製））を用いて、無作為に選択した２００個の粒子について測定した体積基準平均粒子径である。なお、観察にはＳＥＤモード（二次電子検出器）を用いて、加速電圧を２０ｋＶ、５０００～３００００倍の観察倍率にて、横幅１～２０μｍの範囲を観察する。なお、ＳＥＭ画像の縦方向については、横幅１～２０μｍの範囲に２００個以上（通常、２００～３００個程度）の銀粒子が含まれる幅とする。また、体積基準平均粒子径は、ＳＥＭ画像に観察される粒子が、その直径を有する球形であると仮定して測定される値である。具体的な測定方法は、実施例に記載のとおりである。 In the present invention, the average particle size (primary particle size) of silver particles is the volume-based average particle size measured for 200 randomly selected particles using image analysis software (e.g., Macview (manufactured by Mountec Co., Ltd.)) for SEM images. Note that the observation is performed using an SED mode (secondary electron detector) with an accelerating voltage of 20 kV and an observation magnification of 5,000 to 30,000 times, and a range of 1 to 20 μm in width is observed. Note that the vertical direction of the SEM image is set to a width that includes 200 or more silver particles (usually about 200 to 300 particles). The volume-based average particle size is a value measured assuming that the particles observed in the SEM image are spherical with that diameter. Specific measurement methods are as described in the Examples.
　また、本発明の効果を好適に発揮する観点から、本発明の銀粒子は、熱重量示差熱分析における発熱ピークが、１２０～３００℃の範囲に少なくとも１つ観察されることが好ましく、１２０～１６０℃の範囲に少なくとも１つ観察されることがより好ましく、１６０～３００℃の範囲に少なくとも１つ観察されることがさらに好ましい。なお、これらの発熱ピークは、通常、これらの範囲に１つ観察される。 Furthermore, from the viewpoint of optimally exerting the effects of the present invention, it is preferable that the silver particles of the present invention have at least one exothermic peak observed in a thermogravimetric differential thermal analysis in the range of 120 to 300°C, more preferably at least one in the range of 120 to 160°C, and even more preferably at least one in the range of 160 to 300°C. Note that typically, one of these exothermic peaks is observed in these ranges.
　また、本発明の銀粒子の乾燥粉末は、熱重量示差熱分析によって３０℃から５００℃まで加熱したときの重量減少率が１．５重量％以下であることが好ましく、０．０５～１．３重量％であることがより好ましい。熱重量示差熱分析の方法は以下の通りである。 In addition, the dry powder of silver particles of the present invention preferably exhibits a weight loss rate of 1.5% or less by weight when heated from 30°C to 500°C by thermogravimetric differential thermal analysis, and more preferably 0.05 to 1.3% by weight. The method of thermogravimetric differential thermal analysis is as follows.
＜熱重量示差熱分析（ＴＧ－ＤＴＡ）＞
　まず、風乾した銀粒子を用意する。例えば、溶媒中の銀粒子を取得して分析する場合には、溶媒に分散された銀粒子１ｇに対し、メタノール２ｇを加えてよく分散させたのち、銀粒子をろ取、風乾して銀粒子乾燥粉末を得て、分析対象とする。銀粒子の乾燥粉末のＴＧ－ＤＴＡを熱重量示差熱分析装置（例えば、ＨＩＴＡＣＨＩ　Ｇ３００　ＡＳＴ－２）で測定する。測定条件は、雰囲気：空気、測定温度：３０～５００℃、昇温速度：１０℃／ｍｉｎとする。得られたＴＧ－ＤＴＡチャートから、ＴＧ－ＤＴＡ分析における銀粒子の結合に起因する発熱ピークと、熱分析によって３０℃から５００℃まで加熱したときの重量減少率を得る。 <Thermogravimetric Differential Thermal Analysis (TG-DTA)>
First, air-dried silver particles are prepared. For example, when silver particles in a solvent are obtained and analyzed, 2 g of methanol is added to 1 g of silver particles dispersed in a solvent, and the silver particles are thoroughly dispersed. The silver particles are then filtered and air-dried to obtain a silver particle dry powder, which is then used as the analysis subject. The TG-DTA of the dried silver particle powder is measured using a thermogravimetric differential thermal analyzer (e.g., HITACHI G300 AST-2). The measurement conditions are atmosphere: air, measurement temperature: 30 to 500°C, and heating rate: 10°C/min. From the obtained TG-DTA chart, the exothermic peak caused by the bonding of silver particles in the TG-DTA analysis and the weight loss rate when heated from 30°C to 500°C by thermal analysis are obtained.
　本発明の銀粒子に含まれる銀の含有量は、好ましくは９５質量％以上、より好ましくは９８質量％以上である。 The silver content of the silver particles of the present invention is preferably 95% by mass or more, and more preferably 98% by mass or more.
　本発明の銀粒子の表面には、化合物（１）が付着している。すなわち、本発明の銀粒子は、化合物（１）を含む処理液により表面処理されたもの（表面処理銀粒子）である。化合物（１）は、銀粒子の表面に付着し、保護層を形成している。 The silver particles of the present invention have compound (1) attached to their surfaces. That is, the silver particles of the present invention are surface-treated with a treatment solution containing compound (1) (surface-treated silver particles). Compound (1) adheres to the surfaces of the silver particles and forms a protective layer.
　化合物（１）としては、銀粒子の表面に付着し、かつ、前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を前記特定の範囲に設定できるものであれば、特に制限されない。 There are no particular limitations on the compound (1) as long as it adheres to the surface of the silver particles and can set the SPAN: (V90-V10)/V50 value within the specific range.
　銀粒子は、保護層を備えている。具体的には、銀粒子は、銀により構成された粒子の表面に保護層を備えている。また、保護層は、前記一般式（１）で表される化合物を含む。本発明の導電性接着剤は、一般式（１）で表される化合物を保護層に含んでいることにより、銀粒子の溶媒への分散性が良好であり、比抵抗値の小さい焼結体が得られる。 The silver particles have a protective layer. Specifically, the silver particles have a protective layer on the surface of the particles composed of silver. The protective layer also contains a compound represented by the general formula (1). The conductive adhesive of the present invention contains a compound represented by the general formula (1) in the protective layer, so that the silver particles have good dispersibility in the solvent, and a sintered body with a small specific resistance value can be obtained.
　前記の通り、一般式（１）中、Ｒ1は、炭素数が１～５のアルキル基であり、本発明の効果をより一層好適に発揮する観点から、炭素数が１～３のアルキル基であることが好ましく、炭素数が１のアルキル基（すなわちメチル基）であることがより好ましい。また、Ｒ2は、水素原子であるか炭素数が１～５のアルキル基であり、本発明の効果をより一層好適に発揮する観点から、水素原子であるか炭素数が１～３のアルキル基であることが好ましく、水素原子であるか炭素数が１のアルキル基（すなわちメチル基）であることがより好ましく、炭素数が１のアルキル基（すなわちメチル基）であることが特に好ましい。すなわち、一般式（１）で表される化合物の中でも、特に２－ヒドロキシイソ酪酸及び乳酸（Ｌ体、Ｄ体、ＤＬ体）が好ましく、２－ヒドロキシイソ酪酸が最も好ましい。保護層に含まれる一般式（１）で表される化合物は、１種類であってもよいし、２種類以上であってもよい。 As described above, in the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and from the viewpoint of more suitably exerting the effects of the present invention, it is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 carbon atom (i.e., a methyl group). In addition, R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and from the viewpoint of more suitably exerting the effects of the present invention, it is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 carbon atom (i.e., a methyl group), and particularly preferably an alkyl group having 1 carbon atom (i.e., a methyl group). That is, among the compounds represented by the general formula (1), 2-hydroxyisobutyric acid and lactic acid (L-, D-, and DL-forms) are particularly preferred, and 2-hydroxyisobutyric acid is most preferred. The compound represented by the general formula (1) contained in the protective layer may be one type or two or more types.
　本発明の銀粒子の化合物（１）の付着量としては、特に制限されないが、銀粒子の質量を１００質量％として、好ましくは１．５質量％以下、より好ましくは１．３質量％以下であり、下限については、好ましくは０．０５質量％以上である。銀粒子に付着している化合物（１）の含有量は、熱重量示差熱分析により測定することができる。 The amount of compound (1) attached to the silver particles of the present invention is not particularly limited, but is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and the lower limit is preferably 0.05% by mass or more, assuming that the mass of the silver particles is 100% by mass. The content of compound (1) attached to the silver particles can be measured by thermogravimetric differential thermal analysis.
　また、保護層には、一般式（１）で表される化合物とは異なる化合物が含まれていてもよい。異なる化合物としては、例えば、アミン化合物、脂肪酸、ヒドロキシ脂肪酸（ただし、一般式（１）で表される化合物とは異なるヒドロキシ脂肪酸）が挙げられる。一般式（１）で表される化合物とは異なる化合物が保護層に含まれる場合、保護層に含まれる当該異なる化合物は、１種類であってもよいし、２種類以上であってもよい。 The protective layer may also contain a compound different from the compound represented by general formula (1). Examples of the different compound include amine compounds, fatty acids, and hydroxy fatty acids (however, hydroxy fatty acids different from the compound represented by general formula (1)). When a compound different from the compound represented by general formula (1) is contained in the protective layer, the different compound contained in the protective layer may be one type, or two or more types.
　アミン化合物としては、特に制限されないが、好ましくはアルキル基の炭素数が３以上１８以下のアルキルアミン、より好ましくはアルキル基の炭素数が４以上１２以下のアルキルアミンが挙げられる。 The amine compound is not particularly limited, but is preferably an alkylamine having an alkyl group with 3 to 18 carbon atoms, and more preferably an alkylamine having an alkyl group with 4 to 12 carbon atoms.
　アルキルアミンの好ましい具体例としては、エチルアミン、ｎ－プロピルアミン、イソプロピルアミン、１，２－ジメチルプロピルアミン、ｎ－ブチルアミン、イソブチルアミン、ｓｅｃ－ブチルアミン、ｔｅｒｔ－ブチルアミン、イソアミルアミン、ｔｅｒｔ－アミルアミン、３－ペンチルアミン、ｎ－アミルアミン、ｎ－ヘキシルアミン、ｎ－ヘプチルアミン、ｎ－オクチルアミン、２－オクチルアミン、２－エチルヘキシルアミン、ｎ－ノニルアミン、ｎ－アミノデカン、ｎ－アミノウンデカン、ｎ－ドデシルアミン、ｎ－トリデシルアミン、２－トリデシルアミン、ｎ－テトラデシルアミン、ｎ－ペンタデシルアミン、ｎ－ヘキサデシルアミン、ｎ－ヘプタデシルアミン、ｎ－オクタデシルアミン、ｎ－オレイルアミン、Ｎ－エチル－１，３－ジアミノプロパン、Ｎ，Ｎ－ジイソプロピルエチルアミン、Ｎ，Ｎ－ジメチルアミノプロパン、Ｎ，Ｎ－ジブチルアミノプロパン、Ｎ，Ｎ－ジメチル－１，３－ジアミノプロパン、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパン、Ｎ，Ｎ－ジイソブチル－１，３－ジアミノプロパン、Ｎ－ラウリルジアミノプロパン等を例示することができる。さらに、２級アミンであるジブチルアミンや環状アルキルアミンであるシクロプロピルアミン、シクロブチルアミン、シクロプロピルアミン、シクロヘキシルアミン、シクロヘプチルアミン、シクロオクチルアミン、２－（２－アミノエチルアミノ）エタノール等も例示することができる。これらの中でも、本発明の効果をより一層好適に奏する観点から、ｎ－プロピルアミン、イソプロピルアミン、シクロプロピルアミン、ｎ－ブチルアミン、イソブチルアミン、ｓｅｃ－ブチルアミン、ｔｅｒｔ－ブチルアミン、シクロブチルアミン、ｎ－アミルアミン、ｎ－ヘキシルアミン、シクロヘキシルアミン、ｎ－オクチルアミン、２－エチルヘキシルアミン、ｎ－ドデシルアミン、ｎ－オレイルアミン、Ｎ，Ｎ－ジメチル－１，３－ジアミノプロパン、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパンが好ましく、ｎ－ブチルアミン、ｎ－ヘキシルアミン、シクロヘキシルアミン、ｎ－オクチルアミン、ｎ－ドデシルアミン、Ｎ，Ｎ－ジメチル－１，３－ジアミノプロパン、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパンがより好ましく、ｎ－ヘキシルアミンが特に好ましい。化合物（１）は、１種類単独で使用してもよいし、２種類以上を組み合わせて使用してもよい。 Preferred specific examples of alkylamines include ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, isoamylamine, tert-amylamine, 3-pentylamine, n-amylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, n-aminodecane, n-aminoundecane, n-dodecylamine, and n-tridecylamine. Examples of the amines include dibutylamine, which is a secondary amine, and cycloalkylamines such as cyclopropylamine, cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, and 2-(2-aminoethylamino)ethanol. Among these, from the viewpoint of more suitably exerting the effects of the present invention, n-propylamine, isopropylamine, cyclopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, cyclobutylamine, n-amylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-oleylamine, N,N-dimethyl-1,3-diaminopropane, and N,N-diethyl-1,3-diaminopropane are preferred, n-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, N,N-dimethyl-1,3-diaminopropane, and N,N-diethyl-1,3-diaminopropane are more preferred, and n-hexylamine is particularly preferred. Compound (1) may be used alone or in combination of two or more types.
　本発明の銀粒子において、アミン化合物の付着量についても、化合物（１）と同様、適宜調整する。具体的なアミン化合物の付着量は、特に制限されないが、銀粒子の質量を１００質量％として、好ましくは１．５質量％以下、より好ましくは１．３質量％以下であり、下限については、好ましくは０．０１質量％以上である。銀粒子に付着している脂肪酸、ヒドロキシ脂肪酸の含有量は示差熱分析により測定することができる。 In the silver particles of the present invention, the amount of the amine compound attached is also appropriately adjusted, as in the case of compound (1). There are no particular limitations on the specific amount of the amine compound attached, but it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, with the mass of the silver particles being 100% by mass, and the lower limit is preferably 0.01% by mass or more. The content of fatty acids and hydroxy fatty acids attached to the silver particles can be measured by differential thermal analysis.
　また、銀粒子の表面には、脂肪酸、ヒドロキシ脂肪酸等が付着していてもよい。脂肪酸としては、特に制限されないが、好ましくはアルキル基の炭素数が３以上１８以下の脂肪酸、より好ましくはアルキル基の炭素数が４以上１８以下の脂肪酸が挙げられる。脂肪酸の好ましい具体例としては、酢酸、プロピオン酸、酪酸、吉草酸、カプロン酸、カプリル酸、２－エチルヘキサン酸、カプリン酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸、オレイン酸、リノール酸、α－リノレン酸等が挙げられる。また、脂肪酸の具体例としては、シクロヘキサンカルボン酸のような環状アルキルカルボン酸等も挙げられる。また、ヒドロキシ脂肪酸としては、炭素数３～２４で、かつ水酸基を１個以上（例えば、１個）有する化合物を使用できる。また、ヒドロキシ脂肪酸として、例えば、２－ヒドロキシデカン酸、２－ヒドロキシドデカン酸、２－ヒドロキシテトラデカン酸、２－ヒドロキシヘキサデカン酸、２－ヒドロキシオクタデカン酸、２－ヒドロキシエイコサン酸、２－ヒドロキシドコサン酸、２－ヒドロキシトリコサン酸、２－ヒドロキシテトラコサン酸、３－ヒドロキシヘキサン酸、３－ヒドロキシオクタン酸、３－ヒドロキシノナン酸、３－ヒドロキシデカン酸、３－ヒドロキシウンデカン酸、３－ヒドロキシドデカン酸、３－ヒドロキシトリデカン酸、３－ヒドロキシテトラデカン酸、３－ヒドロキシヘキサデカン酸、３－ヒドロキシヘプタデカン酸、３－ヒドロキシオクタデカン酸、ω－ヒドロキシ－２－デセン酸、ω－ヒドロキシペンタデカン酸、ω－ヒドロキシヘプタデカン酸、ω－ヒドロキシエイコサン酸、ω－ヒドロキシドコサン酸、６－ヒドロキシオクタデカン酸、リシノール酸、１２－ヒドロキシステアリン酸、［Ｒ－（Ｅ）］－１２－ヒドロキシ－９－オクタデセン酸等が挙げられる。中でも、炭素数４～１８で、かつω位以外（特に、１２位）に１個の水酸基を有するヒドロキシ脂肪酸が好ましく、リシノール酸、１２－ヒドロキシステアリン酸がより好ましい。脂肪酸及びヒドロキシ脂肪酸は、それぞれ、１種類単独で使用してもよいし、２種類以上を組み合わせて使用してもよい。 Furthermore, fatty acids, hydroxy fatty acids, etc. may be attached to the surface of the silver particles. The fatty acids are not particularly limited, but are preferably fatty acids having an alkyl group with 3 to 18 carbon atoms, and more preferably fatty acids having an alkyl group with 4 to 18 carbon atoms. Preferred examples of fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, etc. Specific examples of fatty acids include cyclic alkyl carboxylic acids such as cyclohexane carboxylic acid. Hydroxy fatty acids that can be used include compounds having 3 to 24 carbon atoms and one or more hydroxyl groups (for example, one). Examples of hydroxy fatty acids include 2-hydroxydecanoic acid, 2-hydroxydodecanoic acid, 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyeicosanoic acid, 2-hydroxydocosanoic acid, 2-hydroxytricosanoic acid, 2-hydroxytetracosanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, and 3-hydroxydodecanoic acid. Examples of such fatty acids include hydroxy fatty acids having 4 to 18 carbon atoms and one hydroxyl group at a position other than the ω position (particularly the 12th position), and more preferably hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid. The fatty acids and hydroxy fatty acids may each be used alone or in combination of two or more.
　本発明の銀粒子において、脂肪酸やヒドロキシ脂肪酸の付着量についても、化合物（１）と同様、適宜調整する。具体的な脂肪酸やヒドロキシ脂肪酸の付着量は、特に制限されないが、銀粒子の質量を１００質量％として、好ましくは１．５質量％以下、より好ましくは１．３質量％以下であり、下限については、好ましくは０．０１質量％以上である。銀粒子に付着している脂肪酸、ヒドロキシ脂肪酸の含有量は示差熱分析により測定することができる。 In the silver particles of the present invention, the amount of fatty acid or hydroxy fatty acid attached is appropriately adjusted, as in compound (1). There are no particular limitations on the specific amount of fatty acid or hydroxy fatty acid attached, but it is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, with the mass of the silver particles being 100% by mass, and the lower limit is preferably 0.01% by mass or more. The content of fatty acid or hydroxy fatty acid attached to the silver particles can be measured by differential thermal analysis.
　なお、本発明の銀粒子は、表面に化合物（１）が付着し、かつ、前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を満たすことを限度として、化合物（１）、アミン化合物、脂肪酸、ヒドロキシ脂肪酸は、併用してもよいし、また、これらとは異なる他の化合物が銀粒子の表面に付着していてもよい。 In addition, in the silver particles of the present invention, compound (1), an amine compound, a fatty acid, and a hydroxy fatty acid may be used in combination, or other compounds different from these may be attached to the surface of the silver particles, as long as compound (1) is attached to the surface and the above-mentioned SPAN: (V90-V10)/V50 value is satisfied.
　本発明の銀粒子は、溶媒に分散されてなる。すなわち、銀粒子は、溶媒に分散された状態で存在している。溶媒は、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下のものであれば、特に制限されない。 The silver particles of the present invention are dispersed in a solvent. That is, the silver particles are present in a state of being dispersed in the solvent. There are no particular limitations on the solvent, so long as the solvent has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less.
　本発明の効果を好適に発揮する観点から、溶媒としては、好ましくは、ジエチレングリコールモノヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：１．７）、テキサノール（Ｌｏｇ　Ｐｏｗ：３．２）、イソプロピルアルコール（Ｌｏｇ　Ｐｏｗ：０．０５）、α－テルピネオール（Ｌｏｇ　Ｐｏｗ：２．９８）、ジエチレングリコール（Ｌｏｇ　Ｐｏｗ：－１．９８）、エチレングリコール（Ｌｏｇ　Ｐｏｗ：－１．３６）、２－エチル－１，３－ヘキサンジオール（Ｌｏｇ　Ｐｏｗ：１．６０）、ジエチレングリコールモノ－２－エチルヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：２．２３）、ブチルカルビトール（Ｌｏｇ　Ｐｏｗ：０．５６）、ブチルカルビトールアセテート（Ｌｏｇ　Ｐｏｗ：２．９）、ブタンジオール（Ｌｏｇ　Ｐｏｗ：－０．３４）などが挙げられる。溶媒は、１種類のみであってもよいし、２種類以上であってもよいが、好ましくは１種類である。 From the viewpoint of optimally exerting the effects of the present invention, preferred examples of the solvent include diethylene glycol monohexyl ether (Log Pow: 1.7), texanol (Log Pow: 3.2), isopropyl alcohol (Log Pow: 0.05), α-terpineol (Log Pow: 2.98), diethylene glycol (Log Pow: -1.98), ethylene glycol (Log Pow: -1.36), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), butyl carbitol (Log Pow: 0.56), butyl carbitol acetate (Log Pow: 2.9), butanediol (Log Pow: -0.34), etc. The solvent may be one type or two or more types, but preferably one type.
　本発明の効果をより好適に発揮する観点から、本発明の銀粒子の溶媒中の濃度としては、好ましくは８０質量％以上、より好ましくは８５質量％以上、さらに好ましくは８８質量％以上であり、また、好ましくは９５質量％以下、より好ましくは９３質量％以下、さらに好ましくは９２質量％以下であり、好ましい範囲としては、８０～９５質量％、８５～９３質量％、８８～９２質量％などが挙げられる。なお、本発明の銀粒子について、前記のＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を測定する際には、濃度を５０質量％に調整して測定を行う。 From the viewpoint of more suitably exerting the effects of the present invention, the concentration of the silver particles of the present invention in the solvent is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 88% by mass or more, and is preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 92% by mass or less, with preferred ranges including 80 to 95% by mass, 85 to 93% by mass, and 88 to 92% by mass. When measuring the value of SPAN: (V90-V10)/V50 for the silver particles of the present invention, the concentration is adjusted to 50% by mass and the measurement is performed.
２．銀粒子の製造方法
　本発明の銀粒子の製造方法の一例を以下に示す。 2. Method for Producing Silver Particles An example of a method for producing silver particles of the present invention is described below.
　まず、銀粒子を製造するための組成物（銀粒子調製用組成物）を用意する。具体的には、銀粒子の原料となる銀化合物、銀粒子の表面に付着させる化合物（１）、各工程で使用する溶媒（銀粒子の合成時に使用する溶媒、銀粒子の精製溶媒、化合物（１）に置換する際の溶媒など）を準備する。 First, a composition for producing silver particles (silver particle preparation composition) is prepared. Specifically, the silver compound that is the raw material for the silver particles, compound (1) to be attached to the surface of the silver particles, and solvents to be used in each step (solvents used in synthesizing the silver particles, solvents for purifying the silver particles, solvents used when replacing with compound (1), etc.) are prepared.
　銀粒子は、銀化合物からの銀粒子の合成工程、後述の銀粒子表面のアミン化合物を酸（保護基）（すなわち、化合物（１））へ置換する工程などを経て合成され、各工程中又は各工程間に銀粒子の分離が含まれ得る。 The silver particles are synthesized through a process of synthesizing silver particles from a silver compound, a process of replacing the amine compound on the surface of the silver particles with an acid (protecting group) (i.e., compound (1)) described below, and the separation of the silver particles may be included during or between each process.
　本発明の効果をより一層好適に奏する観点から、好ましい銀化合物としては、硝酸銀、シュウ酸銀等が挙げられ、特にシュウ酸銀が好ましい。 From the viewpoint of more effectively achieving the effects of the present invention, preferred silver compounds include silver nitrate and silver oxalate, with silver oxalate being particularly preferred.
　銀化合物から銀粒子を合成する際に使用される溶媒としては、銀粒子が合成されれば、特に制限されないが、極性有機溶媒を含むことが好ましい。極性有機溶媒としては、アセトン、アセチルアセトン、メチルエチルケトン等のケトン類；ジエチルエーテル、ジプロピルエーテル、ジブチルエーテル、テトラヒドロフラン、１，４－ジオキサン等のエーテル類；１，２－プロパンジオール、１，２－ブタンジオール、１，３－ブタンジオール、１，４－ブタンジオール、２，３－ブタンジオール、１，２－ヘキサンジオール、１，６－ヘキサンジオール、１，２－ペンタンジオール、１，５－ペンタンジオール、２－メチル－２，４－ペンタンジオール、３－メチル－１，５－ペンタンジオール、１，２－オクタンジオール、１，８－オクタンジオール、２－エチル－１，３－ヘキサンジオール等のジオール類；グリセロール；炭素数１～５の直鎖又は分岐鎖のアルコール、シクロヘキサノール、３－メトキシ－３－メチル－１－ブタノール、３－メトキシ－１－ブタノール等のアルコール類；酢酸エチル、酢酸ブチル、酪酸エチル、蟻酸エチル、テキサノール等の脂肪酸エステル類；ポリエチレングリコール、トリエチレングリコールモノメチルエーテル、テトラエチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールジメチルエーテル、トリエチレングリコールジメチルエーテル、テトラエチレングリコールジメチルエーテル、３－メトキシブチルアセテート、エチレングリコールモノブチルエーテル、エチレングリコールモノブチルエーテルアセテート、エチレングリコールモノヘキシルエーテル、エチレングリコールモノオクチルエーテル、エチレングリコールモノ－２－エチルヘキシルエーテル、エチレングリコールモノベンジルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノメチルエーテルアセテート、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテルアセテート、ジエチレングリコールモノブチルエーテル、ジエチレングリコールモノブチルエーテルアセテート、ジエチレングリコールモノヘキシルエーテル、ジエチレングリコールモノ－２－エチルヘキシルエーテル、ポリプロピレングリコール、プロピレングリコールモノプロピルエーテル、プロピレングリコールモノブチルエーテル、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノエチルエーテル、ジプロピレングリコールモノプロピルエーテル、ジプロピレングリコールモノブチルエーテル、トリプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノエチルエーテル、トリプロピレングリコールモノプロピルエーテル、トリプロピレングリコールモノブチルエーテル等のグリコール又はグリコールエーテル類；Ｎ，Ｎ－ジメチルホルムアミド；ジメチルスルホキシド；テルピネオール等のテルペン類；アセトニトリル；γ－ブチロラクトン；２－ピロリドン；Ｎ－メチルピロリドン；Ｎ－（２－アミノエチル）ピペラジン等が挙げられる。これらの中でも、本発明の効果をより一層好適に奏する観点から、炭素数３～５の直鎖又は分岐鎖のアルコール、３－メトキシ－３－メチル－１－ブタノール、３－メトキシ－１－ブタノール、ジエチレングリコールモノブチルエーテル、ジエチレングリコールモノブチルエーテルアセテート、ジエチレングリコールモノヘキシルエーテル、ジエチレングリコールモノ－２－エチルヘキシルエーテル、テルピネオール、テキサノールが好ましい。 The solvent used when synthesizing silver particles from a silver compound is not particularly limited as long as silver particles are synthesized, but it is preferable that the solvent contains a polar organic solvent. Examples of polar organic solvents include ketones such as acetone, acetylacetone, and methyl ethyl ketone; ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, and 1,4-dioxane; diols such as 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-hexanediol, 1,6-hexanediol, 1,2-pentanediol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,2-octanediol, 1,8-octanediol, and 2-ethyl-1,3-hexanediol; glycerol; and glycerol having 1 to 5 carbon atoms. Alcohols such as linear or branched alcohols, cyclohexanol, 3-methoxy-3-methyl-1-butanol, and 3-methoxy-1-butanol; fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, ethyl formate, and texanol; polyethylene glycol, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether. teracetate, ethylene glycol monohexyl ether, ethylene glycol monooctyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, polypropylene glycol, propylene glycol monopropyl ether, Examples of the glycols or glycol ethers include pyrene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, and tripropylene glycol monobutyl ether; N,N-dimethylformamide; dimethyl sulfoxide; terpenes such as terpineol; acetonitrile; γ-butyrolactone; 2-pyrrolidone; N-methylpyrrolidone; and N-(2-aminoethyl)piperazine. Among these, from the viewpoint of more suitably exerting the effects of the present invention, linear or branched alcohols having 3 to 5 carbon atoms, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, terpineol, and texanol are preferred.
　溶媒は、極性有機溶媒に加えて、さらに非極性又は疎水性溶媒を含んでいてもよい。非極性有機溶媒としては、ヘキサン、ヘプタン、オクタン、ノナン、デカン、２－エチルヘキサン、シクロヘキサン等の直鎖、分枝、又は環状の飽和炭化水素；炭素数６以上の直鎖又は分岐鎖のアルコール等のアルコール類；ベンゼン、トルエン、ベンゾニトリル等の芳香族化合物；ジクロロメタン、クロロホルム、ジクロロエタン等のハロゲン化炭化水素類；メチル－ｎ－アミルケトン；メチルエチルケトンオキシム；トリアセチン等が挙げられる。これらの中でも、飽和炭化水素及び炭素数６以上の直鎖又は分岐鎖のアルコール類が好ましく、ヘキサン、オクタン、デカン、オクタノール、デカノール、ドデカノールがより好ましい。溶媒は、１種を単独で、又は２種以上を混合して使用できる。 The solvent may further contain a non-polar or hydrophobic solvent in addition to the polar organic solvent. Examples of non-polar organic solvents include linear, branched, or cyclic saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, 2-ethylhexane, and cyclohexane; alcohols such as linear or branched alcohols having 6 or more carbon atoms; aromatic compounds such as benzene, toluene, and benzonitrile; halogenated hydrocarbons such as dichloromethane, chloroform, and dichloroethane; methyl-n-amyl ketone; methyl ethyl ketone oxime; and triacetin. Among these, saturated hydrocarbons and linear or branched alcohols having 6 or more carbon atoms are preferred, and hexane, octane, decane, octanol, decanol, and dodecanol are more preferred. The solvents can be used alone or in combination of two or more.
　銀化合物からの銀粒子の合成工程においては、銀化合物、化合物（１）、及び溶媒を混合して銀粒子調製用組成物を得る。当該組成物における各成分の割合は、適宜調整する。例えば、組成物中のシュウ酸銀の含有量は、組成物の全量に対して、２０～７０質量％程度とすることが好ましい。また、化合物（１）の含有量としては、組成物の全量に対して、５質量％～５５質量％程度とすることが好ましい。また、銀粒子の表面に脂肪酸を付着させる場合であれば、脂肪酸の含有量としては、組成物の全量に対して、０．１質量％～２０質量％程度とすることが好ましい。銀粒子の表面にヒドロキシ脂肪酸を付着させる場合であれば、ヒドロキシ脂肪酸の含有量としては、組成物の全量に対して、０．１質量％～１５質量％程度とすることが好ましい。 In the process of synthesizing silver particles from a silver compound, a silver compound, compound (1), and a solvent are mixed to obtain a composition for preparing silver particles. The ratio of each component in the composition is adjusted as appropriate. For example, the content of silver oxalate in the composition is preferably about 20 to 70% by mass relative to the total amount of the composition. The content of compound (1) is preferably about 5 to 55% by mass relative to the total amount of the composition. In addition, when a fatty acid is attached to the surface of the silver particles, the content of the fatty acid is preferably about 0.1 to 20% by mass relative to the total amount of the composition. In addition, when a hydroxy fatty acid is attached to the surface of the silver particles, the content of the hydroxy fatty acid is preferably about 0.1 to 15% by mass relative to the total amount of the composition.
　一旦、アミン化合物が付着した銀粒子を合成し、後述する方法によって、アミン化合物を化合物（１）に置換することが可能である。 It is possible to first synthesize silver particles with an amine compound attached, and then replace the amine compound with compound (1) by the method described below.
　また、各成分の混合手段は特に制限されず、例えば、メカニカルスターラー、マグネティックスターラー、ボルテックスミキサー、遊星ミル、ボールミル、三本ロール、ラインミキサー、プラネタリーミキサー、ディゾルバー等の汎用の装置で混合できる。混合時の溶解熱、摩擦熱等の影響で組成物の温度が上昇し、銀粒子の熱分解反応が開始することを回避するために、組成物の温度を、例えば６０℃以下、特に４０℃以下に抑えながら混合することが好ましい。 In addition, the means for mixing the components is not particularly limited, and they can be mixed using general-purpose equipment such as a mechanical stirrer, magnetic stirrer, vortex mixer, planetary mill, ball mill, three-roll mill, line mixer, planetary mixer, dissolver, etc. In order to avoid the temperature of the composition increasing due to the heat of dissolution and frictional heat during mixing, which could cause the thermal decomposition reaction of the silver particles to begin, it is preferable to mix the components while keeping the temperature of the composition at, for example, 60°C or less, particularly 40°C or less.
　次に、銀粒子調製用組成物を、反応容器内で反応、通常は加熱による反応に供することにより、銀化合物の熱分解反応が起こり、銀粒子が生成する。反応に当たっては、予め加熱しておいた反応容器内に組成物を導入してもよく、組成物を反応容器内に導入した後に加熱してもよい。 Then, the composition for preparing silver particles is reacted in a reaction vessel, usually by heating, causing a thermal decomposition reaction of the silver compound to produce silver particles. For the reaction, the composition may be introduced into a reaction vessel that has been heated in advance, or the composition may be introduced into the reaction vessel and then heated.
　反応温度は、熱分解反応が進行し、銀粒子が生成する温度であればよく、例えば５０～２５０℃程度が挙げられる。また、反応時間は、所望する平均粒子径の大きさや、それに応じた組成物の組成に合せて、適宜選択すればよい。反応時間としては、例えば１分間～１００時間が挙げられる。 The reaction temperature may be any temperature at which the thermal decomposition reaction proceeds and silver particles are produced, for example, about 50 to 250°C. The reaction time may be appropriately selected according to the desired average particle size and the composition of the composition corresponding to that size. The reaction time may be, for example, 1 minute to 100 hours.
　熱分解反応により生成した銀粒子は、未反応原料を含む混合物として得られるため、銀粒子を精製することが好ましい。精製方法としては、固液分離方法、銀粒子と有機溶媒等の未反応原料との比重差を利用した沈殿方法等が挙げられる。固液分離方法としては、フィルター濾過、遠心分離、サイクロン式、又はデカンタ等の方法が挙げられる。精製時の取り扱いを容易にするために、アセトン、メタノール等の低沸点溶媒で銀粒子を含有する混合物を希釈して、その粘度を調整してもよい。 The silver particles produced by the thermal decomposition reaction are obtained as a mixture containing unreacted raw materials, so it is preferable to purify the silver particles. Purification methods include solid-liquid separation methods and precipitation methods that utilize the difference in specific gravity between the silver particles and unreacted raw materials such as organic solvents. Solid-liquid separation methods include filter filtration, centrifugal separation, cyclone, and decanter methods. To facilitate handling during purification, the mixture containing the silver particles may be diluted with a low-boiling point solvent such as acetone or methanol to adjust its viscosity.
　銀粒子製造用組成物の組成や反応条件を調整することにより、得られる銀粒子の平均粒子径（一次粒子径）を調整することができる。また、本発明においては、前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値を前記特定の範囲に設定する観点から、精製溶媒として、ｎ－プロパノール、１－ブタノールなどを用いることが好ましい。精製溶媒の選択は、本発明の銀粒子の前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値に影響を与える。 The average particle size (primary particle size) of the resulting silver particles can be adjusted by adjusting the composition of the silver particle manufacturing composition and the reaction conditions. In addition, in the present invention, from the viewpoint of setting the value of SPAN: (V90-V10)/V50 within the specific range, it is preferable to use n-propanol, 1-butanol, or the like as the refining solvent. The selection of the refining solvent affects the value of SPAN: (V90-V10)/V50 of the silver particles of the present invention.
銀粒子表面のアミン化合物等を置換・調整する方法
　前記の方法で、一旦合成された銀粒子（表面にアミン化合物が付着）を用意し、これを溶媒中に分散させる。溶媒としては、銀粒子の合成工程で使用される溶媒として例示したものと同じものが例示されるが、エタノール、ｎ－プロパノール、イソプロピルアルコール、１－ブタノールなどを用いることが好ましい。銀粒子表面の化合物（１）を置換・調整する際に使用する溶媒の選択は、本発明の銀粒子の前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値に影響を与える。次に、他の化合物（１）を銀粒子の質量に対して、０．１～５倍量の範囲で添加し、室温～８０℃で、１分～２４時間撹拌を行う工程に付することで、銀粒子の表面に付着しているアミン化合物を化合物（１）に置換することができる。表面のアミン化合物を化合物（１）に置換した銀粒子は、前記の固液分離法等によって回収することができる。この固液分離の際に使用する溶媒としては、エタノール、ｎ－プロパノール、イソプロピルアルコール、１－ブタノールなどを用いることが好ましい。当該溶媒の選択についても、本発明の銀粒子の前記ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０の値に影響を与える。 Method for replacing and adjusting amine compounds, etc. on the silver particle surface Silver particles (with amine compounds attached to the surface) once synthesized by the above method are prepared and dispersed in a solvent. Examples of the solvent include the same as those exemplified as the solvent used in the silver particle synthesis process, but it is preferable to use ethanol, n-propanol, isopropyl alcohol, 1-butanol, etc. The selection of the solvent used when replacing and adjusting the compound (1) on the silver particle surface affects the value of the SPAN: (V90-V10)/V50 of the silver particles of the present invention. Next, another compound (1) is added in an amount of 0.1 to 5 times the mass of the silver particles, and the mixture is stirred at room temperature to 80° C. for 1 minute to 24 hours, whereby the amine compounds attached to the silver particle surface can be replaced with compound (1). The silver particles with the amine compounds on the surface replaced with compound (1) can be recovered by the above solid-liquid separation method, etc. As the solvent used in this solid-liquid separation, it is preferable to use ethanol, n-propanol, isopropyl alcohol, 1-butanol, etc. The selection of the solvent also affects the SPAN: (V90-V10)/V50 value of the silver particles of the present invention.
３．導電性接着剤
　本発明の導電性接着剤は、本発明の銀粒子を含むことを特徴としている。すなわち、本発明の導電性接着剤は、銀粒子と溶媒を含んでいる。本発明の銀粒子及び溶媒の詳細については、前述の通りである。 3. Conductive adhesive The conductive adhesive of the present invention is characterized by containing the silver particles of the present invention. That is, the conductive adhesive of the present invention contains silver particles and a solvent. Details of the silver particles and the solvent of the present invention are as described above.
　本発明の導電性接着剤は、本発明の銀粒子、溶媒に加えて、さらに樹脂を含んでいてもよい。樹脂としては、特に制限されず、銀粒子を含む公知の導電性接着剤に使用される樹脂が本発明でも使用することができ、熱可塑性樹脂、熱硬化性樹脂などが挙げられる。熱可塑性樹脂としては、ウレタン樹脂、アクリル樹脂、メタクリル樹脂、ポリビニルアルコール樹脂、酢酸ビニル樹脂、ポリカーボネート樹脂、ポリオルガノシロキサン系樹脂、ポリアミド樹脂などが挙げられ、それらの混合物であっても良い。熱硬化性樹脂としては、エポキシ樹脂、アクリル樹脂、シリコーン樹脂、ウレタン樹脂、ビニルエステル樹脂、フェノール樹脂、ユリア樹脂、メラミン樹脂、不飽和ポリエステル樹脂、ジアリルフタレート樹脂、ポリイミド樹脂などが挙げられる。本発明において、好ましい溶媒の具体例としては、ジエチレングリコールモノヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：１．７）、テキサノール（Ｌｏｇ　Ｐｏｗ：３．２）、イソプロピルアルコール（Ｌｏｇ　Ｐｏｗ：０．０５）、α－テルピネオール（Ｌｏｇ　Ｐｏｗ：２．９８）、ジエチレングリコール（Ｌｏｇ　Ｐｏｗ：－１．９８）、エチレングリコール（Ｌｏｇ　Ｐｏｗ：－１．３６）、２－エチル－１，３－ヘキサンジオール（Ｌｏｇ　Ｐｏｗ：１．６０）、ジエチレングリコールモノ－２－エチルヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：２．２３）、ブチルカルビトール（Ｌｏｇ　Ｐｏｗ：０．５６）、ブチルカルビトールアセテート（Ｌｏｇ　Ｐｏｗ：２．９）、ブタンジオール（Ｌｏｇ　Ｐｏｗ：－０．３４）などが挙げられる。特に好ましい溶媒は、ジエチレングリコールモノヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：１．７）、２－エチル－１，３－ヘキサンジオール（Ｌｏｇ　Ｐｏｗ：１．６０）、ジエチレングリコールモノ－２－エチルヘキシルエーテル（Ｌｏｇ　Ｐｏｗ：２．２３）、テキサノール（Ｌｏｇ　Ｐｏｗ：３．２）である。本発明の導電性接着剤が溶媒をさらに含む場合、導電性接着剤に含まれる溶媒は、１種類であってもよいし、２種類以上であってもよい。 The conductive adhesive of the present invention may further contain a resin in addition to the silver particles and solvent of the present invention. There are no particular limitations on the resin, and resins used in known conductive adhesives containing silver particles can also be used in the present invention, including thermoplastic resins and thermosetting resins. Thermoplastic resins include urethane resins, acrylic resins, methacrylic resins, polyvinyl alcohol resins, vinyl acetate resins, polycarbonate resins, polyorganosiloxane resins, polyamide resins, and mixtures thereof are also acceptable. Thermosetting resins include epoxy resins, acrylic resins, silicone resins, urethane resins, vinyl ester resins, phenolic resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, polyimide resins, and the like. In the present invention, specific examples of preferred solvents include diethylene glycol monohexyl ether (Log Pow: 1.7), texanol (Log Pow: 3.2), isopropyl alcohol (Log Pow: 0.05), α-terpineol (Log Pow: 2.98), diethylene glycol (Log Pow: -1.98), ethylene glycol (Log Pow: -1.36), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), butyl carbitol (Log Pow: 0.56), butyl carbitol acetate (Log Pow: 2.9), butanediol (Log Pow: -0.34), and the like. Particularly preferred solvents are diethylene glycol monohexyl ether (Log Pow: 1.7), 2-ethyl-1,3-hexanediol (Log Pow: 1.60), diethylene glycol mono-2-ethylhexyl ether (Log Pow: 2.23), and Texanol (Log Pow: 3.2). When the conductive adhesive of the present invention further contains a solvent, the conductive adhesive may contain one type of solvent or two or more types of solvents.
　本発明の導電性接着剤における銀粒子の含有量は、好ましくは８０質量％以上、より好ましくは８５質量％以上、さらに好ましくは８８質量％以上であり、また、好ましくは９５質量％以下、より好ましくは９３質量％以下、さらに好ましくは９２質量％以下であり、好ましい範囲としては、８０～９５質量％、８５～９３質量％、８８～９２質量％などが挙げられる。また、本発明の導電性接着剤が樹脂を含む場合、本発明の導電性接着剤における樹脂の含有量は、好ましくは０．００１質量％以上、より好ましくは０．００５質量％以上、さらに好ましくは０．０１質量％以上であり、また、好ましくは１０質量％以下、より好ましくは７質量％以下、さらに好ましくは３質量％以下であり、好ましい範囲としては、０．００１～１０質量％、０．００５～７質量％、０．０１～３質量％などが挙げられる。 The content of silver particles in the conductive adhesive of the present invention is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 88% by mass or more, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 92% by mass or less, with preferred ranges including 80-95% by mass, 85-93% by mass, and 88-92% by mass. In addition, when the conductive adhesive of the present invention contains a resin, the content of the resin in the conductive adhesive of the present invention is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, and is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 3% by mass or less, with preferred ranges including 0.001-10% by mass, 0.005-7% by mass, and 0.01-3% by mass.
４．導電性接着剤の焼結体
　本発明の導電性接着剤の焼結体は、前述の「３．導電性接着剤」で詳述した本発明の導電性接着剤を焼結することにより得られる。本発明の導電性接着剤の焼結体においては、銀粒子の表面に付着している成分（化合物（１）等）、溶媒、樹脂は、焼結の際の高熱により、ほとんどが離脱しており、焼結体は、実質的に銀により構成されている。 4. Sintered body of conductive adhesive The sintered body of the conductive adhesive of the present invention can be obtained by sintering the conductive adhesive of the present invention described in detail in "3. Conductive adhesive" above. In the sintered body of the conductive adhesive of the present invention, most of the components (compound (1) etc.), solvent and resin attached to the surface of the silver particles are removed by the high heat during sintering, and the sintered body is essentially composed of silver.
　焼結温度としては、特に制限されないが、例えば２５０℃以下、好ましくは１５０℃～２５０℃程度、より好ましくは２００℃～２５０℃程度が挙げられる。焼結時間としては、好ましくは０．４時間～２．０時間程度、より好ましくは０．５時間～１．２時間程度が挙げられる。本発明の導電性接着剤の焼結の際に加圧してもよいし、加圧しなくてもよい。加圧する場合の圧力は例えば１０～３０ＭＰａ程度である。焼結は、大気、不活性ガス（窒素ガス、アルゴンガス）等の雰囲気下で行うことができる。焼結手段としては、特に制限されず、オーブン、熱風式乾燥炉、赤外線乾燥炉、レーザー照射、フラッシュランプ照射、マイクロウェーブ等が挙げられる。 The sintering temperature is not particularly limited, but may be, for example, 250°C or lower, preferably about 150°C to 250°C, and more preferably about 200°C to 250°C. The sintering time is preferably about 0.4 hours to 2.0 hours, and more preferably about 0.5 hours to 1.2 hours. Pressurization may or may not be applied during sintering of the conductive adhesive of the present invention. If pressurization is applied, the pressure is, for example, about 10 to 30 MPa. Sintering may be performed in an atmosphere of air, inert gas (nitrogen gas, argon gas), or the like. The sintering means is not particularly limited, and may be, for example, an oven, a hot air drying furnace, an infrared drying furnace, laser irradiation, flash lamp irradiation, microwave, etc.
５．電子部品
　本発明の電子部品は、本発明の焼結体により部材間が接着された部分を備えている。すなわち、本発明の電子部品は、前述の「３．導電性接着剤」で詳述した本発明の導電性接着剤を、電子部品の部材間（例えば、回路に含まれる部材間）に配置し、導電性接着剤を焼結させて、部材間を接着したものである。 5. Electronic Components The electronic components of the present invention have a portion in which components are bonded together by the sintered body of the present invention. That is, the electronic components of the present invention are formed by disposing the conductive adhesive of the present invention, which is described in detail in "3. Conductive Adhesive" above, between components of the electronic components (e.g., between components included in a circuit) and sintering the conductive adhesive to bond the components together.
　以下の実施例において本発明をより具体的に説明するが、本発明はこれらに限定されない。 The present invention will be described in more detail in the following examples, but is not limited to these.
　実施例及び比較例において使用した各成分の詳細は、以下の通りである。
・シュウ酸銀（（ＣＯＯＡｇ）2）は、特許第５５７４７６１号公報に記載の方法で合成した。
・Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパン（富士フイルム和光純薬株式会社製）
・２－ヒドロキシイソ酪酸（東京化成工業株式会社製）
・２－（２ーアミノエチルアミノ）エタノール（東京化成工業株式会社製）
・リシノール酸（東京化成工業株式会社製）
・イソプロピルアルコール（富士フイルム和光純薬株式会社製）
・エタノール（富士フイルム和光純薬株式会社製）
・１－ブタノール（富士フイルム和光純薬株式会社製）
・ジエチレングリコールモノヘキシルエーテル（富士フイルム和光純薬株式会社製）
・２－エチル－１，３－ヘキサンジオール（富士フイルム和光純薬株式会社製） Details of each component used in the examples and comparative examples are as follows.
Silver oxalate ((COOAg) 2 ) was synthesized by the method described in Japanese Patent No. 5,574,761.
N,N-diethyl-1,3-diaminopropane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
・2-Hydroxyisobutyric acid (Tokyo Chemical Industry Co., Ltd.)
2-(2-aminoethylamino)ethanol (Tokyo Chemical Industry Co., Ltd.)
-Ricinoleic acid (Tokyo Chemical Industry Co., Ltd.)
- Isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
- Ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
1-Butanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
- Diethylene glycol monohexyl ether (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
2-Ethyl-1,3-hexanediol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
　以下の手順で銀粒子を製造した。評価で数量が必要な際は、同様の方法で試行回数を増やすことで必要サンプル量を用意した。
＜実施例１：銀粒子１の合成＞
　以下の手順により、溶媒中に分散された銀粒子１を製造した。磁気撹拌子を入れた５０ｍＬガラス製遠沈管に、リシノール酸（０．０５ｇ）、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパン（４．１ｇ）、及び１－ブタノール（７．５ｇ）を投入し、１分間程度攪拌したのち、シュウ酸銀（５ｇ）を投入し、約１０分間攪拌することで、銀粒子１調製用組成物を得た。その後、アルミブロックを備えたホットスターラー（小池精密機器製作所製ＨＨＥ－１９Ｇ－Ｕ）上に、これらのガラス製遠沈管を立てて設置し、４０℃で３０分間攪拌し、さらに、９０℃で３０分間攪拌した。放冷後、磁気撹拌子を取り出し、各組成物にエタノール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。エタノール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子を回収した。次に、得られた銀粒子の分散液（エタノール溶液）を用いて、２－ヒドロキシイソ酪酸を銀粒子の質量の０.５倍量を添加し、室温で２時間撹拌した。撹拌後、磁気撹拌子を取り出し、各組成物にエタノール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。次に、２－エチル－１，３－ヘキサンジオール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子１を回収した。 Silver particles were produced using the following procedure. When a larger quantity was required for evaluation, the required sample amount was prepared by increasing the number of trials in the same manner.
Example 1: Synthesis of Silver Particles 1
Silver particles 1 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 1. The glass centrifuge tube was then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C. for 30 minutes, and further stirred at 90° C. for 30 minutes. After cooling, the magnetic stirrer was removed, 15 g of ethanol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of ethanol, stirring, centrifugation, and removing the supernatant were repeated twice to recover the silver particles. Next, 2-hydroxyisobutyric acid was added in an amount 0.5 times the mass of the silver particles to the obtained dispersion of silver particles (ethanol solution), and the mixture was stirred at room temperature for 2 hours. After stirring, the magnetic stirrer was removed, 15 g of ethanol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the steps of adding 15 g of 2-ethyl-1,3-hexanediol, stirring, centrifugation, and removing the supernatant were repeated twice to recover silver particles 1.
＜実施例２：銀粒子２の合成＞
　以下の手順により、溶媒中に分散された銀粒子２を製造した。磁気撹拌子を入れた５０ｍＬガラス製遠沈管に、リシノール酸（０．０５ｇ）、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパン（４．１ｇ）、及び１－ブタノール（７．５ｇ）を投入し、１分間程度攪拌したのち、シュウ酸銀（５ｇ）を投入し、約１０分間攪拌することで、銀粒子２調製用組成物を得た。その後、アルミブロックを備えたホットスターラー（小池精密機器製作所製ＨＨＥ－１９Ｇ－Ｕ）上に、これらのガラス製遠沈管を立てて設置し、４０℃で３０分間攪拌し、さらに、９０℃で３０分間攪拌した。放冷後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。イソプロピルアルコール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子を回収した。次に、得られた銀粒子の分散液（イソプロピルアルコール溶液）を用いて、２－ヒドロキシイソ酪酸を銀粒子の質量の０.５倍量を添加し、室温で２時間撹拌した。撹拌後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。次に、２－エチル－１，３－ヘキサンジオール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子２を回収した。 Example 2: Synthesis of silver particles 2
Silver particles 2 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 2. Thereafter, the glass centrifuge tube was placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C. for 30 minutes, and further stirred at 90° C. for 30 minutes. After cooling, the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of isopropyl alcohol, stirring, centrifugation, and removing the supernatant were repeated twice to recover the silver particles. Next, 2-hydroxyisobutyric acid was added in an amount 0.5 times the mass of the silver particles using the obtained dispersion of silver particles (isopropyl alcohol solution), and the mixture was stirred at room temperature for 2 hours. After stirring, the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the steps of adding 15 g of 2-ethyl-1,3-hexanediol, stirring, centrifugation, and removing the supernatant were repeated twice to recover silver particles 2.
＜実施例３：銀粒子３の合成＞
　以下の手順により、溶媒中に分散された銀粒子４を製造した。磁気撹拌子を入れた５０ｍＬガラス製遠沈管に、２－（２－アミノエチルアミノ）エタノール（１．７４ｇ）、及び１－ブタノール（７．５ｇ）を投入し、１分間程度攪拌したのち、シュウ酸銀（５ｇ）を投入し、約１０分間攪拌することで、銀粒子４調製用組成物を得た。その後、アルミブロックを備えたホットスターラー（小池精密機器製作所製ＨＨＥ－１９Ｇ－Ｕ）上に、これらのガラス製遠沈管を立てて設置し、４０℃で３０分間攪拌し、さらに、９０℃で３０分間攪拌した。放冷後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて２５００ｒｐｍ（遠心加速度約１１１０×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。イソプロピルアルコール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子を回収した。次に、得られた銀粒子の分散液（イソプロピルアルコール溶液）を用いて、２－ヒドロキシイソ酪酸を銀粒子の質量の０.５倍量を添加し、室温で２時間撹拌した。撹拌後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて２５００ｒｐｍ（遠心加速度約１１１０×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。次に、ジエチレングリコールモノヘキシルエーテル１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子３を回収した。 Example 3: Synthesis of silver particles 3
Silver particles 4 dispersed in a solvent were produced by the following procedure. 2-(2-aminoethylamino)ethanol (1.74 g) and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer, and the mixture was stirred for about 1 minute. Then, silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 4. The glass centrifuge tubes were then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and the mixture was stirred at 40°C for 30 minutes, and further stirred at 90°C for 30 minutes. After cooling, the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 2500 rpm (centrifugal acceleration of about 1110×G) in a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of isopropyl alcohol, stirring, centrifugal separation, and removing the supernatant were repeated twice to recover silver particles. Next, 0.5 times the mass of the silver particles of 2-hydroxyisobutyric acid was added to the obtained dispersion of silver particles (isopropyl alcohol solution), and the mixture was stirred at room temperature for 2 hours. After stirring, the magnetic stirrer was removed, and 15 g of isopropyl alcohol was added to each composition and stirred with a vortex mixer. Then, a centrifuge operation was performed for 1 minute at 2500 rpm (centrifugal acceleration of about 1110×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the steps of adding 15 g of diethylene glycol monohexyl ether, stirring, centrifugal separation, and removing the supernatant were repeated twice to recover silver particles 3.
＜比較例１：銀粒子４の合成＞
　以下の手順により、溶媒中に分散された銀粒子６を製造した。磁気撹拌子を入れた５０ｍＬガラス製遠沈管に、リシノール酸（０．０５ｇ）、Ｎ，Ｎ－ジエチル－１，３－ジアミノプロパン（４．１ｇ）、及び１－ブタノール（７．５ｇ）を投入し、１分間程度攪拌したのち、シュウ酸銀（５ｇ）を投入し、約１０分間攪拌することで、銀粒子６調製用組成物を得た。その後、アルミブロックを備えたホットスターラー（小池精密機器製作所製ＨＨＥ－１９Ｇ－Ｕ）上に、これらのガラス製遠沈管を立てて設置し、４０℃で３０分間攪拌し、さらに、９０℃で３０分間攪拌した。放冷後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。イソプロピルアルコール１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子を回収した。次に、得られた銀粒子の分散液（イソプロピルアルコール溶液）を用いて、２－ヒドロキシイソ酪酸を銀粒子の質量の０.５倍量を添加し、室温で２時間撹拌した。撹拌後、磁気撹拌子を取り出し、各組成物にイソプロピルアルコール１５ｇを添加してボルテックスミキサーで攪拌した後、遠心分離機（日立工機製ＣＦ７Ｄ２）にて３０００ｒｐｍ（遠心加速度約１６００×Ｇ）で１分間の遠沈操作を実施し、遠沈管を傾けることにより上澄みを除去した。次に、ジエチレングリコールモノヘキシルエーテル１５ｇの添加、撹拌、遠心分離、及び上澄み除去の工程を２回繰り返し、銀粒子４を回収した。 Comparative Example 1: Synthesis of Silver Particles 4
Silver particles 6 dispersed in a solvent were produced by the following procedure. Ricinoleic acid (0.05 g), N,N-diethyl-1,3-diaminopropane (4.1 g), and 1-butanol (7.5 g) were added to a 50 mL glass centrifuge tube containing a magnetic stirrer and stirred for about 1 minute, and then silver oxalate (5 g) was added and stirred for about 10 minutes to obtain a composition for preparing silver particles 6. The glass centrifuge tube was then placed upright on a hot stirrer (HHE-19G-U manufactured by Koike Precision Machinery Works) equipped with an aluminum block, and stirred at 40° C. for 30 minutes, and further stirred at 90° C. for 30 minutes. After cooling, the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The steps of adding 15 g of isopropyl alcohol, stirring, centrifugation, and removing the supernatant were repeated twice to recover the silver particles. Next, 2-hydroxyisobutyric acid was added in an amount 0.5 times the mass of the silver particles using the obtained dispersion of silver particles (isopropyl alcohol solution), and the mixture was stirred at room temperature for 2 hours. After stirring, the magnetic stirrer was removed, 15 g of isopropyl alcohol was added to each composition, and the mixture was stirred with a vortex mixer. The mixture was then centrifuged for 1 minute at 3000 rpm (centrifugal acceleration of about 1600×G) in a centrifuge (Hitachi Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the steps of adding 15 g of diethylene glycol monohexyl ether, stirring, centrifugation, and removing the supernatant were repeated twice to recover silver particles 4.
　得られた各銀粒子１～４について、それぞれ、走査型電子顕微鏡による観察（ＳＥＭ画像の取得）、平均粒子径（体積基準平均粒子径）の測定、粒度分布の測定、ＴＧ－ＤＴＡの測定を以下の条件にて行った。 For each of the obtained silver particles 1 to 4, observation was performed using a scanning electron microscope (obtaining SEM images), the average particle size (volume-based average particle size) was measured, the particle size distribution was measured, and TG-DTA was measured under the following conditions.
＜電子顕微鏡による観察＞
　得られた各銀粒子１～４について、走査型電子顕微鏡（ＳＥＭ（日本電子製ＪＳＭ－ＩＴ５００ＨＲ））を用いて、ＳＥＭ画像を取得した。 <Observation by electron microscope>
For each of the obtained silver particles 1 to 4, an SEM image was taken using a scanning electron microscope (SEM (JSM-IT500HR manufactured by JEOL Ltd.)).
＜平均粒子径（体積基準平均粒子径）の測定＞
　前記＜電子顕微鏡による観察＞で取得した各ＳＥＭ画像（横幅１～２０μｍ）について、画像解析ソフト（マックビュー（マウンテック社製））を用いて、無作為に選択した２００個の粒子の体積基準平均粒子径（一次粒子径）を測定した。ＳＥＭ画像の縦方向については、横幅１～２０μｍの範囲を観察する。なお、ＳＥＭ画像の縦方向については、横幅１～２０μｍの範囲に２００個以上（通常、２００～３００個程度）の銀粒子が含まれる幅とする。なお、体積基準平均粒子径は、ＳＥＭ画像に観察される粒子が、その直径を有する球形であると仮定して測定される値である。結果を表１に示す。 <Measurement of average particle size (volume-based average particle size)>
For each SEM image (width 1-20 μm) obtained in the above <Observation by electron microscope>, the volume-based average particle size (primary particle size) of 200 randomly selected particles was measured using image analysis software (MacView (Mountec)). A range of width 1-20 μm was observed in the vertical direction of the SEM image. Note that the vertical direction of the SEM image is set to a width that includes 200 or more silver particles (usually about 200-300 particles) in a range of width 1-20 μm. Note that the volume-based average particle size is a value measured assuming that the particles observed in the SEM image are spherical with that diameter. The results are shown in Table 1.
＜光透過式遠心沈降法＞
　得られた各銀粒子１～４について、光透過式遠心沈降法により、以下のＳＰＡＮの値を求めた。
ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
沈降速度を累積分布で示した際、
積算値の１０％の沈降速度はＶ１０である。
積算値の９０％の沈降速度はＶ９０である。
積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。 <Light transmission centrifugal sedimentation method>
For each of the obtained Silver Particles 1 to 4, the following SPAN value was determined by the light transmission centrifugal sedimentation method.
SPAN: (V90-V10)/V50 Formula (1)
When the sedimentation velocity is shown as a cumulative distribution,
The sedimentation velocity of 10% of the integrated value is V10.
The sedimentation velocity at 90% of the integrated value is V90.
The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
（ＳＰＡＮの測定条件）
　銀粒子の溶媒中の濃度が５０質量％である測定用試料を用意した。測定用試料の溶媒は、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下である溶剤を用いた。５０ｍｌバイアル瓶に各銀粒子（１～４）を分取し、銀粒子１、２については２－エチル－１，３－ヘキサンジオールを、銀粒子３、４についてはジエチレングリコールモノヘキシルエーテル用いて、銀分が５０質量％、溶剤が５０質量％の計１００％となるように希釈した。混錬にはボルテックスミキサーを用い、２０００ｒｐｍで２分間分散させた。この時、目に見えて分散していない（固形分が残る）ようであれば、スパチュラ等を用いた粗混錬や自転公転式ミキサー等を用いて分散させても良い。自転公転式ミキサーを用いる際は、自転と公転のバランスをとり、粒子が沈降しないように攪拌すること。また、銀粒子が分散されてなる銀粒子分散液を測定対象とし、測定用試料を作成する際は、その銀粒子を分散させている溶剤を希釈液として用い、測定用試料を作成すること。その分散液に複数の溶剤が用いられている場合は、複数の溶剤を用いてもよく、その分散液と等量の比率で希釈すること。ＳＰＡＮ（（Ｖ９０－Ｖ１０）／Ｖ５０）の測定はＬＵＭＪａｐａｎ製 分散性評価・粒子径分布装置ＬＳ－６１０型により測定した。具体的には、測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離と時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出した。測定時のＬｉｇｈｔＦａｃｔｏｒは６に設定した。なお、測定の際にガラスセルを用いないと銀粒子が固着し、遮光することで正確な光度（吸光度）を測定出来ない。また、ＬｉｇｈｔＦａｃｔｏｒを６に設定しないと、高濃度の金属粒子分散液という測定物の性質上、光の強度が不足する。そのため、高濃度の粒子分散液の二次粒子状態を計測するためには６に設定する必要がある。同様の原理によって二次粒子の形態を測定する際は、測定装置の光源について留意する必要がある。そして、ノード（解析幅）同士を重ねると測定プロファイル数（測定点数）として妥当な点数が得られないため、ノードは重ならないように解析する必要がある。測定結果を表１に示す。 (SPAN measurement conditions)
A measurement sample was prepared in which the concentration of silver particles in the solvent was 50% by mass. The solvent used for the measurement sample was a solvent with an octanol/water distribution coefficient (Log Pow) of -2 to 4. Each silver particle (1 to 4) was dispensed into a 50 ml vial, and silver particles 1 and 2 were diluted with 2-ethyl-1,3-hexanediol, and silver particles 3 and 4 were diluted with diethylene glycol monohexyl ether to a total of 100%, with 50% silver and 50% solvent by mass. A vortex mixer was used for kneading, and the mixture was dispersed at 2000 rpm for 2 minutes. If the particles are not visibly dispersed (solids remain) at this time, they may be roughly kneaded using a spatula or the like, or dispersed using a planetary rotation mixer. When using a planetary rotation mixer, the rotation and revolution should be balanced to prevent the particles from settling. In addition, when preparing a measurement sample using a silver particle dispersion in which silver particles are dispersed as the measurement target, the solvent in which the silver particles are dispersed should be used as a diluent to prepare the measurement sample. If the dispersion contains multiple solvents, multiple solvents may be used and should be diluted in an equal volume ratio to the dispersion. SPAN ((V90-V10)/V50) was measured using a dispersibility evaluation/particle size distribution device LS-610 manufactured by LUM Japan. Specifically, 0.2 ml of the measurement sample was filled into a glass cell (glass cell with an optical path length of 2 mm), rotated at a low speed at 25° C. with a centrifugal acceleration of 130 G, and data for 500 points was obtained at intervals of 5 seconds. Then, the cell was rotated at a high speed with a centrifugal acceleration of 1160 G, and data for 500 points was obtained at intervals of 5 seconds. Three points were arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points was analyzed with a node width of 1 mm. The settling velocities V90, V10, and V50 were obtained from the moving distance and time of the particles, and the SPAN was calculated by formula (1). The LightFactor during measurement was set to 6. Note that if a glass cell is not used during measurement, the silver particles will adhere and will be blocked, making it impossible to measure accurate luminosity (absorbance). Furthermore, if the LightFactor is not set to 6, the light intensity is insufficient due to the nature of the measurement object, which is a high-concentration metal particle dispersion. Therefore, in order to measure the secondary particle state of a high-concentration particle dispersion, it is necessary to set it to 6. When measuring the morphology of secondary particles using a similar principle, attention must be paid to the light source of the measurement device. Furthermore, if nodes (analysis widths) overlap, a reasonable number of points cannot be obtained as the number of measurement profiles (number of measurement points), so it is necessary to analyze the nodes so that they do not overlap. The measurement results are shown in Table 1.
＜流動性評価＞
　得られた各銀粒子１～４について、以下の方法により流動性を評価した。結果を表１に示す。なお、銀粒子５（平均粒子径１．８８μｍ）として、ＤＯＷＡエレクトロニクス株式会社製の製品名ＡＧ３－１Ｆを用いた。 <Liquidity assessment>
The fluidity of each of the obtained silver particles 1 to 4 was evaluated by the following method. The results are shown in Table 1. Note that as silver particles 5 (average particle size 1.88 μm), AG3-1F, a product manufactured by Dowa Electronics Co., Ltd., was used.
（銀ペーストの調製方法）
　５０ｍｌバイアルに各銀粒子（１～４）を分取し、銀分として等量となるように銀粒子５を加えた。それを銀粒子１、２については２－エチル－１，３－ヘキサンジオールを、銀粒子３、４についてはジエチレングリコールモノヘキシルエーテル用いて銀分９０質量％と溶剤１０質量％で計１００％となるように調整し、各ペーストを得た。そのペーストを自転／公転式混錬機（クラボウ社製マゼルスターＫＫ－４００Ｗ）を用い、１３４０／１３４０ｒｐｍの条件で３０秒混錬した。なお、銀粒子及び銀粒子分散液の状態によっては、スパチュラ等を用いた手作業によって粗混錬を実施しても良い。これを目開き１００μｍのメッシュでろ過し、バレル（岩下エンジニアリング製ＰＳ０５Ｎ）に１０ｇ充填して密栓した。上記混錬機を用いて、銀ペーストが充填されたバレルを同条件で６０秒間攪拌脱泡し、さらに攪拌後１２時間放置することで、流動性試験用試料を得た。銀ペーストの流動性の評価はエアパルス式ディスペンサー（岩下エンジニアリング製ＡＤ３３００Ｃ）を用いて実施した。吐出圧はレギュレーターで調整し、２０ｋＰａ～１００ｋＰａの範囲で調整した。また、試験はいずれも温調を用い、バレル温度（ペースト温度）が２５℃となるように調整した上で実施した。１０ｇの銀ペーストが充填されたバレル（岩下エンジニアリング製ＰＳ０５Ｎ）に０．２７ｍｍφのノズル径の精密ノズルをセットし、ディスペンサーにセットした。印刷条件として、ノズル先端から被印刷体（ガラス基板）までの距離を１００μｍとした。被印刷体上に５ｍｍのラインパターンを等間隔で印刷した。ラインパターンの印刷が終わってから、１秒経過すると、次のラインパターンの印刷が始まるように設定した。このようにして、１００点ラインパターンをうつ毎に次の被印刷体へと移行し、１時間印刷した。 (Method of preparing silver paste)
Each silver particle (1 to 4) was taken into a 50 ml vial, and silver particle 5 was added so that the silver content was equal. For silver particles 1 and 2, 2-ethyl-1,3-hexanediol was used, and for silver particles 3 and 4, diethylene glycol monohexyl ether was used to adjust the silver content to 90 mass % and the solvent to 10 mass % to a total of 100%, to obtain each paste. The paste was kneaded for 30 seconds using a rotation/revolution type kneader (Mazerustar KK-400W manufactured by Kurabo Industries, Ltd.) under the condition of 1340/1340 rpm. Depending on the state of the silver particles and the silver particle dispersion, rough kneading may be performed manually using a spatula or the like. This was filtered through a mesh with an opening of 100 μm, and 10 g was filled into a barrel (PS05N manufactured by Iwashita Engineering Co., Ltd.) and sealed. Using the above kneader, the barrel filled with the silver paste was stirred and degassed under the same conditions for 60 seconds, and further left for 12 hours after stirring to obtain a fluidity test sample. The fluidity of the silver paste was evaluated using an air pulse dispenser (AD3300C manufactured by Iwashita Engineering). The discharge pressure was adjusted by a regulator and adjusted in the range of 20 kPa to 100 kPa. In addition, all tests were performed using temperature control, with the barrel temperature (paste temperature) adjusted to 25 ° C. A precision nozzle with a nozzle diameter of 0.27 mmφ was set in a barrel (PS05N manufactured by Iwashita Engineering) filled with 10 g of silver paste, and set in the dispenser. The printing conditions were a distance from the nozzle tip to the printed material (glass substrate) of 100 μm. A line pattern of 5 mm was printed at equal intervals on the printed material. It was set so that printing of the next line pattern would begin 1 second after printing of the line pattern was completed. In this way, the printer moved to the next printed material every time a 100-point line pattern was printed, and printing was continued for 1 hour.
（吐出重量維持率）
　印刷初期の被印刷体上のラインパターンの重量Ａ（１００点分の銀ペースト重量ｇ）と１時間経過後の最後の被印刷体上のラインパターンの重量Ｂ（１００点分の銀ペースト重量ｇ）から吐出重量維持率＝Ｂ／Ａ ＊ １００質量％を算出した。吐出重量維持率が１００質量％を基準とした際、５０％を下回っているものは×、５０％以上のものを〇、８５％以上のものを◎とした。 (Discharge Weight Maintenance Rate)
The discharge weight maintenance rate was calculated as B/A*100% by mass from the weight A of the line pattern on the printed substrate at the beginning of printing (weight of silver paste for 100 points in g) and the weight B of the line pattern on the printed substrate at the end after 1 hour (weight of silver paste for 100 points in g).When the discharge weight maintenance rate is based on 100% by mass, those below 50% were marked with ×, those at 50% or more with ◯, and those at 85% or more with ◎.
（連続印刷性評価）
　１時間吐出した全てのラインパターンのうち、未塗布の箇所が５％以上存在するものを×とした。未塗布の箇所が発生しない、あるいは５％未満のものを〇とした。 (Continuous Printing Evaluation)
Among all the line patterns discharged for one hour, those in which 5% or more of the lines were uncoated were marked with an X. Those in which no uncoated areas occurred or those in which the uncoated areas were less than 5% were marked with an O.
＜形状安定性評価＞
　得られた各銀粒子１～４について、以下の方法により形状安定性を評価した。結果を表１に示す。銀ペーストの形状安定性の評価は流動性試験と同様に試料を用意し、エアパルス式ディスペンサー（岩下エンジニアリング製ＡＤ３３００Ｃ）を用いて実施した。吐出圧はレギュレーターで調整し、２０ｋＰａ～１００ｋＰａの範囲で調整した。また、試験はいずれも温調を用い、バレル温度（ペースト温度）が２５℃となるように調整した上で実施した。１０ｇの銀ペーストが充填されたバレル（岩下エンジニアリング製ＰＳ０５Ｎ）に０．２７ｍｍφのノズル径の精密ノズルをセットし、ディスペンサーにセットした。印刷条件として、ノズル先端から被印刷体（ガラス基板）までの距離を１００μｍとした。被印刷体上に５ｍｍのラインパターンを等間隔で印刷した。ラインパターンの印刷が終わってから、１秒経過すると、次のラインパターンの印刷が始まるように設定した。このようにして、１００点ラインパターンをうつ毎に次の被印刷体へと移行し、１時間印刷した。１時間吐出した全てのラインパターンにおいて、目視観察にて、ライン状に塗布出来ず、糸引きしているもの、太さや細さが著しく異なる印刷物が多量に発生した場合を×とした。ライン状に塗布出来たものしかない、あるいは形状が異なるラインパターンがある場合でも著しく目立たないものを〇とした。 <Evaluation of shape stability>
The shape stability of each of the obtained silver particles 1 to 4 was evaluated by the following method. The results are shown in Table 1. The shape stability of the silver paste was evaluated by preparing a sample in the same manner as in the fluidity test, and using an air pulse dispenser (AD3300C manufactured by Iwashita Engineering Co., Ltd.). The discharge pressure was adjusted by a regulator to a range of 20 kPa to 100 kPa. In addition, all tests were performed using temperature control, after adjusting the barrel temperature (paste temperature) to 25°C. A precision nozzle with a nozzle diameter of 0.27 mmφ was set in a barrel (PS05N manufactured by Iwashita Engineering Co., Ltd.) filled with 10 g of silver paste, and set in the dispenser. As a printing condition, the distance from the nozzle tip to the printed material (glass substrate) was set to 100 μm. A line pattern of 5 mm was printed on the printed material at equal intervals. It was set so that printing of the next line pattern would start 1 second after printing of the line pattern was completed. In this way, the printing was moved to the next printed material every time a 100-point line pattern was printed, and printing was continued for 1 hour. In all line patterns discharged for one hour, cases in which the ink could not be applied in a line shape and there were stringy prints or a large number of prints with significantly different thicknesses and thinnesses were observed by visual observation were rated as ×. Cases in which the ink could only be applied in a line shape or there were line patterns with different shapes but these were not significantly noticeable were rated as ◯.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006

Claims (8)

  1. 　溶媒に分散されてなる銀粒子であって、
    　前記銀粒子の表面に下記一般式（１）で表される化合物が付着しており、
    Figure JPOXMLDOC01-appb-C000001
     ［一般式（１）中、Ｒ1は炭素数が１～５のアルキル基であり、Ｒ2は水素原子であるか、炭素数が１～５のアルキル基である。］
    　前記銀粒子の前記溶媒中の濃度を５０質量％とした場合、下記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮの値が、０．１以上５．０以下である、銀粒子。
    ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
    沈降速度を累積分布で示した際、
    積算値の１０％の沈降速度はＶ１０である。
    積算値の９０％の沈降速度はＶ９０である。
    積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。
    （ＳＰＡＮの測定条件）
    　前記銀粒子の前記溶媒中の濃度が５０質量％である測定用試料を用意する。前記測定用試料の前記溶媒としては、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下であるものを用いる。前記測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離とその移動に要した時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出する。     Silver particles dispersed in a solvent,
    A compound represented by the following general formula (1) is attached to the surface of the silver particles,
    Figure JPOXMLDOC01-appb-C000001
     [In general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]
    Silver particles, wherein when a concentration of the silver particles in the solvent is 50% by mass, the SPAN value measured by a light transmission centrifugal sedimentation method under the following conditions is 0.1 or more and 5.0 or less.
    SPAN: (V90-V10)/V50...Equation (1)
    When the sedimentation velocity is shown as a cumulative distribution,
    The settling velocity of 10% of the integrated value is V10.
    The sedimentation velocity at 90% of the integrated value is V90.
    The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
    (SPAN measurement conditions)
    A measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass. The solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less. 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds. Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm. Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
  2. 　前記銀粒子の平均粒子径が５０～６００ｎｍである、請求項１に記載の銀粒子。 The silver particles according to claim 1, wherein the average particle size of the silver particles is 50 to 600 nm.
  3. 　銀粒子が溶媒に分散されてなる銀粒子分散液であって、
    　前記銀粒子の表面に下記一般式（１）で表される化合物が付着しており、
    Figure JPOXMLDOC01-appb-C000002
     ［一般式（１）中、Ｒ1は炭素数が１～５のアルキル基であり、Ｒ2は水素原子であるか、炭素数が１～５のアルキル基である。］
    　前記銀粒子の前記溶媒中の濃度を５０質量％とした場合、下記条件の光透過式遠心沈降法によって測定される、ＳＰＡＮの値が、０．１以上５．０以下である、銀粒子分散液。
    ＳＰＡＮ：（Ｖ９０－Ｖ１０）／Ｖ５０・・・式（１）
    沈降速度を累積分布で示した際、
    積算値の１０％の沈降速度はＶ１０である。
    積算値の９０％の沈降速度はＶ９０である。
    積算値の５０％の沈降速度はＶ５０（メジアン沈降速度）である。
    （ＳＰＡＮの測定条件）
    　前記銀粒子の前記溶媒中の濃度が５０質量％である測定用試料を用意する。前記測定用試料の前記溶媒としては、オクタノール／水分配係数（Ｌｏｇ　Ｐｏｗ）が－２以上４以下であるものを用いる。前記測定用試料０．２ｍｌをガラスセル（光路長２ｍｍのガラスセル）に充填し、２５℃条件下、遠心加速度１３０Ｇで低速回転させ、インターバル５秒で５００点分データを取得したのち、遠心加速度１１６０Ｇで高速回転させ、インターバル５秒で５００点分データを取得し、前記測定用試料の気液界面（測定用試料の液面）から固液界面（沈降した銀粒子と溶媒の界面）の間を任意に３点選択し、それぞれ３点をノード１ｍｍ幅で解析し、粒子の移動距離とその移動に要した時間から沈降速度Ｖ９０、Ｖ１０、Ｖ５０を求め、式（１）によりＳＰＡＮを算出する。     A silver particle dispersion liquid in which silver particles are dispersed in a solvent,
    A compound represented by the following general formula (1) is attached to the surface of the silver particles,
    Figure JPOXMLDOC01-appb-C000002
     [In the general formula (1), R 1 is an alkyl group having 1 to 5 carbon atoms, and R 2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.]
    A silver particle dispersion liquid having a SPAN value of 0.1 or more and 5.0 or less, when the concentration of the silver particles in the solvent is 50% by mass, as measured by a light transmission centrifugal sedimentation method under the following conditions:
    SPAN: (V90-V10)/V50...Equation (1)
    When the sedimentation velocity is shown as a cumulative distribution,
    The settling velocity of 10% of the integrated value is V10.
    The sedimentation velocity at 90% of the integrated value is V90.
    The sedimentation velocity at 50% of the integrated value is V50 (median sedimentation velocity).
    (SPAN measurement conditions)
    A measurement sample is prepared in which the concentration of the silver particles in the solvent is 50% by mass. The solvent for the measurement sample has an octanol/water partition coefficient (Log Pow) of -2 or more and 4 or less. 0.2 ml of the measurement sample is filled into a glass cell (a glass cell with an optical path length of 2 mm), rotated at a low speed of 130 G centrifugal acceleration under a condition of 25° C., and data for 500 points is obtained at intervals of 5 seconds, and then rotated at a high speed of 1160 G centrifugal acceleration to obtain data for 500 points at intervals of 5 seconds. Three points are arbitrarily selected between the gas-liquid interface (liquid surface of the measurement sample) and the solid-liquid interface (interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points is analyzed with a node width of 1 mm. Sedimentation velocities V90, V10, and V50 are calculated from the moving distance of the particles and the time required for the movement, and SPAN is calculated by formula (1).
  4. 　前記銀粒子の平均粒子径が５０～６００ｎｍである、請求項３に記載の銀粒子分散液。 The silver particle dispersion according to claim 3, wherein the average particle size of the silver particles is 50 to 600 nm.
  5. 　請求項１又は２に記載の銀粒子を含む導電性接着剤。 A conductive adhesive containing the silver particles according to claim 1 or 2.
  6. 　請求項１又は２に記載の銀粒子と、樹脂と、を含む導電性接着剤。 A conductive adhesive comprising the silver particles according to claim 1 or 2 and a resin.
  7. 　請求項５に記載の導電性接着剤の焼結体。 A sintered body of the conductive adhesive described in claim 5.
  8. 　請求項７に記載の焼結体によって部材間が接合されてなる電子部品。 An electronic component in which members are joined together using the sintered body described in claim 7.
PCT/JP2023/030336 2022-09-30 2023-08-23 Silver particles WO2024070350A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004047856A (en) * 2002-07-15 2004-02-12 Sumitomo Metal Electronics Devices Inc Conductive paste and printing method as well as manufacturing method of ceramic multilayer circuit board
JP2009074171A (en) * 2007-08-30 2009-04-09 Mitsuboshi Belting Ltd Metal colloidal particle and fluid dispersion thereof
JP2016164312A (en) * 2014-06-11 2016-09-08 バンドー化学株式会社 Silver fine particle dispersoid, silver fine particle, and production method thereof
JP2019087396A (en) * 2017-11-07 2019-06-06 三菱マテリアル株式会社 Silver paste, joined body, and method for manufacturing joined body

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004047856A (en) * 2002-07-15 2004-02-12 Sumitomo Metal Electronics Devices Inc Conductive paste and printing method as well as manufacturing method of ceramic multilayer circuit board
JP2009074171A (en) * 2007-08-30 2009-04-09 Mitsuboshi Belting Ltd Metal colloidal particle and fluid dispersion thereof
JP2016164312A (en) * 2014-06-11 2016-09-08 バンドー化学株式会社 Silver fine particle dispersoid, silver fine particle, and production method thereof
JP2019087396A (en) * 2017-11-07 2019-06-06 三菱マテリアル株式会社 Silver paste, joined body, and method for manufacturing joined body

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