Silver particles

Abstract

Provided are novel silver particles which, when used as an electroconductive adhesive, have excellent adhesion between a sintered body obtained by sintering the electroconductive adhesive in a nitrogen atmosphere and a copper member, and which exhibit high mechanical strength (shear strength) when a shear force is applied to the sintered body that is in close contact with the copper member. A silver particle in which a compound represented by general formula (1) is adhered to the surface of the silver particle. [In general formula (1), R1 is an alkyl group having 2-8 carbon atoms, R2 is an alkyl group having 1-4 carbon atoms, and R3 is a hydrogen atom or an alkyl group having 1-4 carbon atoms. ]

Description

TECHNICAL FIELD

[0001] The present application relates to silver particles, a conductive adhesive, a sintered body of the conductive adhesive, and an electronic component having the sintered body between members. BACKGROUND

[0002] A conductive adhesive such as a die bonding agent is a joining material used in electronic components such as semiconductors, LEDs, power semiconductors, and the like. As a joining method, a method of joining to a base material by sintering based on heating or the like without pressure, or a method of joining by pressure and heating is generally known. In recent years, from the viewpoint of the degree of ease of manufacturing process and efficiency, development of joining materials of the non-pressure type has been progressing.

[0003] In recent years, development of conductive adhesives containing silver particles has been progressing. Silver particles have characteristics including easy sintering by heat treatment at low temperature for a short time. For example, in Patent Literature 1, a metal paste in which a solid component containing 30% or more of silver particles having a particle size of 100 nm to 200 nm on a particle number basis is mixed with a solvent is disclosed. Further, the silver particles constituting the solid component have an amine compound having a total carbon atom number of 4 to 8 as a protective agent. According to the metal paste, it is possible to sinter silver particles in a low temperature region, and it is possible to form a sintered body having low resistance and a sintered body having excellent thermal conductivity. PRIOR ART DOCUMENTS PATENT LITERATURE

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2015-159096 SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] A conductive adhesive containing silver particles is a conductive adhesive in which silver particles are dispersed in a solvent, and by coating and sintering on the surface of a member (for example, a substrate used in an electronic component, a semiconductor chip, or the like), it is possible to bond the members to each other.

[0006] For example, in the manufacturing process of a member such as a substrate used in an electronic component, a semiconductor chip, or the like, in the case where a conductive adhesive containing silver particles is applied, in order to suppress deterioration of the member (for example, deterioration due to heating in the atmosphere), it is required to perform the manufacturing process under a nitrogen atmosphere. In addition, by performing the manufacturing under a nitrogen atmosphere, it is possible to perform the manufacturing process under a uniform environment.

[0007] In addition, for example, in the case where a conductive adhesive containing silver particles is applied to a copper member such as a copper substrate, it is necessary to perform sintering under a nitrogen atmosphere, not an atmospheric atmosphere.

[0008] However, in the case where the conventional conductive adhesive containing silver particles is applied to a copper member and sintered in a nitrogen atmosphere to obtain a laminate, there is a case where the adhesion of the sintered body to the copper member is insufficient (specifically, in the case where a shear force is applied to the sintered body which is in close contact with the copper member, the mechanical strength (shear strength) of the laminate is low, and the sintered body is easily peeled from the copper member).

[0009] Under such circumstances, the present application has an object to provide a novel silver particle which, in the case where the silver particle is used for a conductive adhesive, has excellent adhesion of a sintered body obtained by sintering the conductive adhesive on the surface of a copper member in a nitrogen atmosphere to the copper member, and exhibits high mechanical strength (shear strength) in the case where a shear force is applied to the sintered body of the laminate. Further, the present application has an object to provide a conductive adhesive containing the silver particle, a sintered body of the conductive adhesive, and an electronic component having the sintered body between members. Technical solution for solving the technical problem

[0010] The present inventors have made intensive studies in order to solve the above-described technical problem. As a result, the present inventors have obtained the following new insight: by using a novel silver particle in which a prescribed acidic compound is attached to the surface of a silver particle composed of silver, for a conductive adhesive, the sintered body obtained by sintering the conductive adhesive in a nitrogen atmosphere has excellent adhesion to a copper member. The present application has been completed based on this insight, through further repeated studies.

[0011] That is, the present application provides the invention in the manner disclosed below. Item 1. A silver particle in which a compound represented by the following general formula (1) is attached to the surface of the silver particle. [Chemical Formula 1] [In the general formula (1), R 1 is an alkyl group having 2 to 8 carbon atoms, R 2 is an alkyl group having 1 to 4 carbon atoms, and R 3 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.] Item 2. The silver particle according to Item 1, wherein the average particle diameter of the silver particle is 60 nm to 600 nm. Item 3. The silver particle according to Item 1 or 2, wherein the silver particle is dispersed in a solvent. Item 4. The silver particle according to Item 3, wherein, when the concentration of the silver particle in the solvent is set to 50% by mass, the value of SPAN determined by a light transmission centrifugal sedimentation method under the following conditions is 0.1 or more and 5.0 or less. SPAN: (X90 - X10) / X50... (1) When the particle diameter is expressed in terms of a cumulative distribution, The particle diameter at which the cumulative particle diameter distribution is 10% is X10. The particle diameter at which the cumulative particle diameter distribution is 90% is X90. The particle diameter at which the cumulative particle diameter distribution is 50% is X50 (median particle diameter). (Measurement conditions of SPAN) A measurement sample was prepared in which the above silver particles were at a concentration of 50 mass% in the above solvent. As the solvent of the measurement sample, a solvent having an octanol / water partition coefficient (Log Pow) of -2 or more and 4 or less was used. The measurement sample was filled into a glass cell (a glass cell having an optical path length of 2 mm) at 0.2 ml, and was subjected to low-speed rotation at a centrifugal acceleration of 130 G under conditions of 25°C. After data of 500 points were obtained at 5-second intervals, high-speed rotation was performed at a centrifugal acceleration of 1160 G, and data of 500 points were obtained at 5-second intervals. Three points were arbitrarily selected between the gas-liquid interface (the liquid surface of the measurement sample) and the solid-liquid interface (the interface between the settled silver particles and the solvent) of the measurement sample, and each of the three points was analyzed at a node width of 1 mm. The settling velocity was calculated from the moving distance of the particles and the time required for the movement, and the particle diameter was converted using the viscosity and the refractive index of the solvent used, to obtain the particle diameters X90, X10, and X50. SPAN was calculated by Formula (1). Item 5. An electrically conductive adhesive comprising the silver particles described in any one of items 1 to 4. Item 6. An electrically conductive adhesive comprising the silver particles described in any one of items 1 to 4 and a resin. Item 7. A sintered body of the electrically conductive adhesive described in item 5. Item 8. An electronic component in which members are joined using the sintered body described in item 7. Effects of the Invention

[0012] According to the present application, it is possible to provide novel silver particles in which, when the silver particles are used in an electrically conductive adhesive, the adhesion of a sintered body obtained by sintering the electrically conductive adhesive on the surface of a copper member under a nitrogen atmosphere to the laminate of the copper member is excellent, and high mechanical strength (shear strength) is exhibited when a shear force is applied to the sintered body of the laminate. Further, according to the present application, it is also possible to provide an electrically conductive adhesive containing the silver particles, a sintered body of the electrically conductive adhesive, and an electronic component in which the sintered body is present between members. DETAILED DESCRIPTION

[0013] In the silver particles of the present application, a compound represented by the following general formula (1) is attached to the surface of the silver particles composed of silver. The silver particles of the present application have the surface of the particles composed of silver to which the specific acidic compound is attached, whereby, in the case of use as a conductive adhesive, the adhesion of the sintered body obtained by sintering the conductive adhesive in a nitrogen atmosphere to a copper member is excellent, and in the case where a shear force is applied to the sintered body in close contact with the copper member, high mechanical strength (shear strength) can be exerted. Hereinafter, the silver particles of the present application, the conductive adhesive, the sintered body of the conductive adhesive, and the electronic component having the sintered body between members will be described in detail.

[0014] [Chemical Formula 2] [In the general formula (1), R 1 is an alkyl group having 2 to 8 carbon atoms, R 2 is an alkyl group having 1 to 4 carbon atoms, and R 3 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.]

[0015] Note that, in the present specification, the numerical values connected with "to" mean the numerical range including the numerical values before and after "to" as the lower limit value and the upper limit value. In the case where a plurality of lower limit values and a plurality of upper limit values are separately described, any lower limit value and any upper limit value can be selected and connected with "to".

[0016] 1. Silver particles The silver particles of the present application are particles containing silver. The compound represented by the above general formula (1) (hereinafter, sometimes referred to as compound (1)) is attached to the surface of the silver particles. That is, the silver particles of the present application have a structure in which the compound (1) is attached to the surface of the particles composed of silver.

[0017] Note that, in the present application, the expression "silver particles" is used for the particles composed of silver (particles composed of substantially only silver) to which the compound (1) is not attached, and the expression "silver particles" is also used for the particles in which the compound (1) is attached to the surface of the particles composed of silver for the sake of convenience. In the case where the expression "the silver particles of the present application" is used, it means the particles in which the compound (1) is attached to the surface of the particles composed of silver.

[0018] In the silver particles of the present application, the compound (1) attached to the surface of the silver particles can be present as a protective layer (or a surface layer, etc.). Specifically, the silver particles have a protective layer on the surface of the particles composed of silver. In addition, the protective layer contains the compound represented by the above general formula (1). The conductive adhesive of the present application is excellent in the adhesion of the sintered body to the copper member by containing the silver particles having such a protective layer, and by sintering the conductive adhesive in a nitrogen atmosphere, and can exhibit high mechanical strength (shear strength) in the case where a shearing force is applied to the sintered body in close contact with the copper member in the laminate.

[0019] In the general formula (1), R 1 is an alkyl group having 2 to 8 carbon atoms, and from the viewpoint of more preferably exerting the effects of the present application, an alkyl group having 3 to 7 carbon atoms is preferable, and an alkyl group having 3 to 6 carbon atoms is more preferable.

[0020] In the general formula (1), R 2 is an alkyl group having 1 to 4 carbon atoms, and from the viewpoint of more preferably exerting the effects of the present application, an alkyl group having 1 to 3 carbon atoms is preferable, and an alkyl group having 1 to 2 carbon atoms is more preferable.

[0021] In the general formula (1), R 3 is a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and from the viewpoint of more preferably exerting the effects of the present application, a hydrogen atom is preferable, or an alkyl group having 1 to 2 carbon atoms is more preferable, and a hydrogen atom is further more preferable.

[0022] From the viewpoint of more preferably exerting the effects of the present application, among the compounds represented by the general formula (1), specifically, 2-methylbutyric acid, 2-ethylbutyric acid, 2,2-dimethylbutyric acid, 2-methylvaleric acid, 2,2-dimethylvaleric acid, 2-ethylvaleric acid, 2-propylvaleric acid, 2-methylhexanoic acid, 2,2-dimethylhexanoic acid, 2-ethylhexanoic acid, 2,2-diethylhexanoic acid, 2-propylhexanoic acid, 2-butylhexanoic acid, 2-methylheptanoic acid, 2-ethylheptanoic acid, 2-propylheptanoic acid, 2-methyloctanoic acid, 2-ethyloctanoic acid, 2-propyloctanoic acid, 2-methylnonanoic acid, 2-ethylnonanoic acid, 2-methyldecanoic acid, 2-ethyldecanoic acid, and the like are preferable, and 2-ethylhexanoic acid is particularly preferable. The compound represented by the general formula (1) contained in the protective layer can be one kind, or two or more kinds.

[0023] The attached amount of the compound (1) of the silver particles of the present application is not particularly limited, and is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, based on 100% by mass of the silver particles, and is preferably 0.05% by mass or more. The content of the compound (1) attached to the silver particles can be measured by thermogravimetric differential thermal analysis.

[0024] In addition, a compound other than the compound represented by General Formula (1) can be contained in the protective layer. As the other compound, for example, an amine compound, a fatty acid, a hydroxy fatty acid can be given. In the case where the other compound is contained in the protective layer, the other compound contained in the protective layer can be one or two or more.

[0025] The amine compound is not particularly limited, and an alkylamine in which the number of carbon atoms of an alkyl group is 3 or more and 18 or less is preferable, and an alkylamine in which the number of carbon atoms of an alkyl group is 4 or more and 12 or less is more preferable.

[0026] As a preferable specific example of the alkylamine, ethylamine, n-propylamine, isopropylamine, 1,2-dimethylpropylamine, n-butylamine, isobutylamine, sec-butylamine, t-butylamine, isoamylamine, t-amylamine, 3-pentylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-octylamine, 2-ethylhexylamine, n-nonylamine, amino-n-decane, amino-n-undecane, n-dodecylamine, n-tridecylamine, 2-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-oleylamine, N-ethyl-1,3-diaminopropane, N,N-diisopropylethylamine, N,N-dimethylaminopropane, N,N-dibutylaminopropane, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, N,N-diisobutyl-1,3-diaminopropane, N-lauryldiaminopropane, and the like can be given. Further, dibutylamine as a secondary amine, cyclopropylamine, cyclobutylamine, cyclopropylamine, cyclohexylamine, cycloheptylamine, cyclooctylamine, 2-(2-aminoethylamino)ethanol, and the like can be given. Among them, from the viewpoint of more favorably achieving the effects of the present application, n-propylamine, isopropylamine, cyclopropylamine, n-butylamine, isobutylamine, sec-butylamine, t-butylamine, cyclobutylamine, n-pentylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, n-dodecylamine, n-oleylamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane are preferable, n-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-dodecylamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane are more preferable, and n-hexylamine is particularly preferable. The compound (1) can be used alone or in combination with two or more.

[0027] In the silver particles of the present application, the amount of the amine compound to be attached is also appropriately adjusted as with the compound (1). The amount of the amine compound to be attached is not particularly limited, and, with the mass of the silver particles being 100 mass%, 1.5 mass% or less, more preferably 1.3 mass% or less, and the lower limit being 0.00 mass%, 0.01 mass% or more, and the like are preferable. The content of the amine compound attached to the silver particles can be measured by differential thermal analysis.

[0028] Furthermore, fatty acids, hydroxy fatty acids, etc., may be attached to the surface of the silver particles. There are no particular limitations on the fatty acid, but fatty acids with 3 or more and 18 or fewer carbon atoms in the alkyl group are preferred, and fatty acids with 4 or more and 18 or fewer carbon atoms in the alkyl group are more preferred. Specific examples of preferred fatty acids include: acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, etc. α -Linolenic acid, etc. Additionally, specific examples of fatty acids include cyclic alkyl carboxylic acids such as cyclohexanecarboxylic acid. Furthermore, as hydroxy fatty acids, compounds with 3 to 24 carbon atoms and having one or more (e.g., one) hydroxyl groups can be used. 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-hydroxydienoic acid, 2-hydroxytridecanoic acid, 2-hydroxytetracosanoic acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, 3-hydroxyundecanoic acid, 3-hydroxydodecanoic acid, 3-hydroxytridecanoic acid, 3-hydroxytetradecanoic acid, 3-hydroxyhexadecanoic acid, 3-hydroxyheptadecanoic acid, 3-hydroxyheptadecanoic acid, 3-hydroxyoctadecanoic acid, 3-hydroxyoctadecanoic acid, ω -Hydroxy-2-decenoic acid, ω -Hydroxypentadecanoic acid, ω -Hydroxyheptadecanoic acid, ω -Hydroxyeicosanoic acid, ω 1-Hydroxy-dodecanoic acid, 6-hydroxy-octadecanoic acid, ricinoleic acid, 12-hydroxy-stearic acid, [R-(E)]-12-hydroxy-9-octadecenoic acid, etc. Among these, the preferred composition is a carbon number of 4 to 18, and excluding... ω Hydroxy fatty acids having one hydroxyl group outside the 12 position (especially at the 12 position), preferably ricinoleic acid and 12-hydroxystearic acid. Fatty acids and hydroxy fatty acids can each be used alone or in combination of two or more.

[0029] In the silver particles of the present invention, the amount of fatty acids and hydroxy fatty acids attached is adjusted appropriately, similar to that of compound (1). There are no particular limitations on the specific amount of fatty acids and hydroxy fatty acids attached; preferably, it is 1.5% by mass or less, more preferably 1.3% by mass or less, with the mass of the silver particles as 100% by mass, and the lower limit is 0.01% by mass or more. The content of fatty acids and hydroxy fatty acids attached to the silver particles can be determined by differential thermal analysis.

[0030] It should be noted that in the silver particles of the present invention, the effect of the present invention is limited to compound (1) being attached to the surface. Compound (1), amine compounds, fatty acids, and hydroxy fatty acids can be used together. In addition, other compounds different from them can also be attached to the surface of the silver particles.

[0031] The silver particles of the present invention can be prepared in a state of dispersion in a solvent. In this case, the silver particles of the present invention exist in a state of dispersion in a solvent. As a solvent, there are no particular limitations as long as it can disperse the silver particles of the present invention, but solvents with an octanol / water partition coefficient (Log Pow) of -2 or more and 4 or less are preferred.

[0032] From the viewpoint of properly maximizing the effects of the present invention, preferred solvents include diethylene glycol monohexyl ether (octanol / water partition coefficient: 1.7), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol) (octanol / water partition coefficient: 3.2), and isopropanol (octanol / water partition coefficient: 0.05). α - Terpineol (octanol / water partition coefficient: 2.98), diethylene glycol (octanol / water partition coefficient: -1.98), ethylene glycol (octanol / water partition coefficient: -1.36), 2-ethyl-1,3-hexanediol (octanol / water partition coefficient: 1.60), diethylene glycol mono-2-ethylhexyl ether (octanol / water partition coefficient: 2.23), butyl carbitol (octanol / water partition coefficient: 0.56), butyl carbitol acetate (octanol / water partition coefficient: 2.9), butanediol (octanol / water partition coefficient: -0.34), etc. The solvent can be one or more, preferably one.

[0033] From the viewpoint of more appropriately maximizing 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, further preferably 88% by mass or more, and preferably 95% by mass or less, more preferably 93% by mass or less, further preferably 92% by mass or less. Examples of preferred ranges include 80% to 95% by mass, 85% to 93% by mass, and 88% to 92% by mass. It should be noted that, regarding the silver particles of the present invention, when measuring the value of SPAN: (X90-X10) / X50 (described later), the concentration is adjusted to 50% by mass for measurement.

[0034] The value of SPAN: (X90-X10) / X50 of the silver particles of the present application, measured by the light transmittance centrifugal sedimentation method described above, is preferably 0.1 or greater and 5.0 or less. The value of SPAN: (X90-X10) / X50 measured by the light transmittance centrifugal sedimentation method is related to the particle size distribution of the secondary particles of the silver particles, and it can be said that the smaller the value of SPAN: (X90-X10) / X50, the narrower the particle size distribution of the secondary particles of the silver particles. In the present application, the value of SPAN: (X90-X10) / X50 of the silver particles to which the compound (1) is attached is within a specific range of 0.1 to 5.0, and thus it can be evaluated that the particle size distribution of the secondary particles of the silver particles is within an appropriate range, further agglomeration of the secondary particles is inhibited, and the secondary particles are appropriately dispersed in a solvent. In the past, attempts have been made to adjust the properties of the conductive adhesive containing the silver particles by controlling the primary particles of the silver particles, but in the present application, the dispersibility of the secondary particles of the silver particles is focused on, and the value of SPAN: (X90-X10) / X50 measured by the light transmittance centrifugal sedimentation method is controlled within a specific range, and thus both the good flowability of the silver particles dispersed in a solvent and the properties excellent in sinterability are taken into account. As a result, the effects of the present application can be more appropriately exerted. As for the specific measurement conditions of the light transmittance centrifugal sedimentation method, those described in the examples are used.

[0035] From the viewpoint of appropriately exerting the effects of the present application, the value of SPAN: (X90-X10) / X50 of the silver particles of the present application described above is preferably 0.1 or greater, more preferably 0.2 or greater, further preferably 0.3 or greater, and particularly preferably 0.4 or greater. In addition, it is preferably 5.0 or less, more preferably 4.9 or less, further preferably 4.8 or less, and particularly preferably 4.7 or less. As the preferable range, 0.1 to 5.0, 0.2 to 4.9, 0.3 to 4.8, 0.4 to 4.7, and the like can be given.

[0036] In the present application, the method for setting the value of SPAN: (X90-X10) / X50 of the silver particles in the specific range of 0.1 to 5.0 is not particularly limited, and for example, as described later, it can be adjusted by the refining solvent (cleaning solvent) used in the production of the silver particles, the cleaning method when using the 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)), and the selection of the dispersion solvent, the dispersion method into the dispersion solvent, the centrifugal separation conditions when producing the silver particles in the case of requiring concentration, and the like. In particular, the refining solvent needs to be selected according to the particle diameter and the protecting group, and in the case of not using an appropriate refining solvent, there are cases where the particle size distribution of the secondary particles when producing a high-concentration dispersion liquid becomes wide, or extremely large secondary particles are produced. In addition, the centrifugal separation conditions also have an impact on the secondary particles when an excessively strong load G is applied. Furthermore, under excessively weak centrifugal conditions, there is also a tendency for the distribution of secondary particles to become wide, and appropriate centrifugal separation conditions need to be specified according to the particle diameter and the type of solvent used during centrifugal separation.

[0037] In addition, from the viewpoint of appropriately exerting the effects of the present application, the average particle diameter (primary particle diameter) of the silver particles is, for example, 600 nm or less, preferably 580 nm or less, more preferably 560 nm or less, further preferably 550 nm or less, and in addition, is preferably 50 nm or more, more preferably 60 nm or more, further preferably 65 nm or more, and as a preferable range, 50 nm to 600 nm, 50 nm to 580 nm, 50 nm to 560 nm, 50 nm to 550 nm, 60 nm to 600 nm, 60 nm to 580 nm, 60 nm to 560 nm, 60 nm to 550 nm, 65 nm to 600 nm, 65 nm to 580 nm, 65 nm to 560 nm, and 65 nm to 550 nm can be given.

[0038] For example, the sinterability of the conductive adhesive containing silver particles having an average particle diameter of about 100 nm (about 50 nm to 150 nm) is excellent, and thus it can be suitably used for the bonding portion of a power device in a thin film form, a solar cell use, and the like. In addition, for example, the conductive adhesive containing silver particles having an average particle diameter of about 200 nm (about 150 nm to 300 nm) is low in shrinkage while maintaining sinterability, and thus it can be suitably used for the bonding portion of a power device, a power amplifier, and the like. In addition, for example, the conductive adhesive containing silver particles having an average particle diameter of about 500 nm (about 300 nm to 600 nm) is low in shrinkage, and thus it can be suitably used for the bonding portion of a power device in a thick film form, and the like. Depending on the use of the conductive adhesive, the required properties differ, but in the conductive adhesive of the present application, by adjusting the average particle diameter of the silver particles of the present application, a conductive adhesive suitable for each use can also be produced.

[0039] The average particle diameter (primary particle diameter) of the silver particles of the present application is the volume-based average particle diameter determined by using an image analysis software (for example, Macview (manufactured by Mountech)) for 200 particles randomly selected from the SEM image. Note that, in the observation, the SED mode (secondary electron detector) is used, and the observation magnification is 5000 to 30000 times at an acceleration voltage of 20 kV, and the width of 1 μ m to 20 μ m. Note that, with respect to the longitudinal direction of the SEM image, the width of 1 μ m to 20 μ m or more (typically, about 200 to 300) silver particles is included. Further, the volume-based average particle diameter is a value determined by assuming that the particles observed in the SEM image have a spherical shape with the diameter thereof. The specific determination method is described in the examples.

[0040] Further, from the viewpoint of appropriately exerting the effects of the present application, the silver particles of the present application preferably exhibit at least one or more heat generation peaks in the range of 120°C to 300°C in the thermal gravimetric differential thermal analysis, more preferably at least one or more heat generation peaks in the range of 120°C to 160°C, and further preferably at least one or more heat generation peaks in the range of 160°C to 300°C. Note that, these heat generation peaks are typically observed as one or more peaks in these ranges.

[0041] Further, the weight reduction ratio of the dried powder of the silver particles of the present application when heated from 30°C to 500°C by the thermal gravimetric differential thermal analysis is preferably 1.5% by weight or less, and more preferably 0.05% to 1.3% by weight. The method of the thermal gravimetric differential thermal analysis is described below.

[0042] <Thermal Gravimetric Differential Thermal Analysis (TG-DTA)> The TG-DTA of the silver particles dispersed in a solvent is measured by a thermal gravimetric differential thermal analysis device (for example, HITACHI G300 AST-2). The measurement conditions are: atmosphere: air (in the case of measuring the silver content in the dispersion liquid) or nitrogen (in the case of measuring the heat generation peak and the weight reduction amount), measurement temperature: 30°C to 500°C, and temperature increase rate: 10°C / min. From the obtained TG-DTA chart, the heat generation peak in the TG-DTA analysis due to the aggregation of the silver particles and the weight reduction ratio when heated from 30°C to 500°C by the thermal analysis are obtained.

[0043] The content of silver included in the silver particles of the present application is preferably 95% by mass or more, and more preferably 98% by mass or more.

[0044] The silver particle of the present application has compound (1) attached to the surface thereof. That is, the silver particle of the present application is a silver particle (surface-treated silver particle) that has been surface-treated using a treatment liquid containing compound (1). Compound (1) is attached to the surface of the silver particle to form a protective layer.

[0045] 2. Method for producing silver particles An example of a method for producing the silver particle of the present application is shown below.

[0046] First, a composition for producing the silver particle of the present application (a particle composed of silver) is prepared. Specifically, a silver compound that is a raw material of the silver particle, compound (1) that is attached to the surface of the silver particle, and a solvent used in each process (a solvent used at the time of synthesis of the silver particle, a refining solvent of the silver particle, a solvent at the time of replacement into compound (1), and the like) are prepared.

[0047] The silver particle of the present application is synthesized through a process of synthesizing a silver particle (a particle composed of silver) from a silver compound, a process of replacing an amine compound of the surface of the silver particle described later into an acid (protective group) (i.e., compound (1)), and the like, and separation of the silver particle can be included in each process or between the processes.

[0048] From the viewpoint of more further appropriately achieving the effects of the present application, as the preferred silver compound, silver nitrate, silver oxalate, and the like can be given, and silver oxalate is particularly preferred.

[0049] As a solvent used when silver particles are synthesized from a silver compound, there is no particular limitation as long as silver particles composed of silver are synthesized, and a polar organic solvent is preferred. As the polar organic solvent, mention can be made of ketones such as acetone, acetylacetone, methyl ethyl ketone, and the like; ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane, and the like; glycols 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, 2-ethyl-1,3-hexanediol, and the like; glycerol; linear or branched alcohols having 1 to 5 carbon atoms, cyclohexanol, 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-butanol, and the like; fatty acid esters such as ethyl acetate, butyl acetate, ethyl butyrate, ethyl formate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and the like; 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, ethylene glycol monobutyl ether acetate, 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, propylene 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, tripropylene glycol monobutyl ether, and the like glycols or glycol ethers; N,N-dimethylformamide; dimethyl sulfoxide; terpenes such as terpinen-4-ol, and the like; acetonitrile; γ - butyrolactone; 2-pyrrolidone; N-methylpyrrolidone; N-(2-aminoethyl)piperazine, and the like. Among these, from the viewpoint of more further favorably achieving the effects of the present application, 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, terpinen-4-ol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate are preferred.

[0050] As the non-polar or hydrophobic solvent, straight-chain, branched, or cyclic saturated hydrocarbons such as hexane, heptane, octane, nonane, decane, 2-ethylhexane, cyclohexane, and the like; alcohols such as straight-chain or branched alcohols having 6 or more carbon atoms; aromatic compounds such as benzene, toluene, benzonitrile, and the like; halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, and the like; methyl n-amyl ketone; methyl ethyl ketone oxime; triacetin, and the like can be further included. Among these, saturated hydrocarbons and alcohols having 6 or more carbon atoms are preferred, and hexane, octane, decane, octanol, decanol, dodecanol are more preferred. The solvent can be used singly or in combination of two or more.

[0051] In the process of synthesizing silver particles from a silver compound, a silver particle preparation composition is obtained by mixing the silver compound, the compound (1), and a solvent. The proportions of the respective components in the composition are appropriately adjusted. For example, the content of silver oxalate in the composition is preferably about 20 to 70 mass% relative to the total amount of the composition. Further, as the content of the compound (1), it is preferably set to about 5 to 55 mass% relative to the total amount of the composition. Further, if a fatty acid is attached to the surface of the silver particles, as the content of the fatty acid, it is preferably set to about 0.1 to 20 mass% relative to the total amount of the composition. If a hydroxy fatty acid is attached to the surface of the silver particles, as the content of the hydroxy fatty acid, it is preferably set to about 0.1 to 15 mass% relative to the total amount of the composition.

[0052] The silver particles to which the amine compound is temporarily attached can be synthesized, and the amine compound is replaced with the compound (1) by the method described later.

[0053] Further, the means for mixing the respective components is not particularly limited, and for example, a general device such as a mechanical stirrer, a magnetic stirrer, a vortex mixer, a planetary mill, a ball mill, a three-roll mill, a line mixer, a planetary mixer, a dissolver, and the like can be used for the mixing. In order to avoid the temperature rise of the composition and the start of the thermal decomposition reaction of the silver particles due to the influence of the heat of solution, the heat of friction, and the like at the time of mixing, it is preferred that the mixing be performed while the temperature of the composition is suppressed to, for example, 60°C or lower, particularly 40°C or lower.

[0054] Next, the silver particle preparation composition is supplied to a reaction in a reaction vessel, typically a reaction using heating, whereby the thermal decomposition reaction of the silver compound occurs, and silver particles are generated. In the reaction, the composition can be introduced into a reaction vessel that has been previously heated, or the composition can be introduced into the reaction vessel and then heated.

[0055] The reaction temperature can be any temperature at which thermal decomposition reaction proceeds and silver particles are generated, and for example, 50°C to 250°C or so can be mentioned. Further, the reaction time can be appropriately selected in accordance with the desired average particle size and the composition of the composition corresponding thereto. As the reaction time, for example, 1 minute to 100 hours can be mentioned.

[0056] Since the silver particles generated by the thermal decomposition reaction are obtained as a mixture containing unreacted raw materials, it is preferable to refine the silver particles. As the refining method, a solid-liquid separation method, a precipitation method using the difference in specific gravity between the silver particles and unreacted raw materials such as organic solvents, or the like can be mentioned. As the solid-liquid separation method, a filter filtration, a centrifugal separation, a cyclone separation, or a decantation method, or the like can be mentioned. In order to make the handling at the time of refining easy, the mixture containing the silver particles can also be diluted with a low-boiling-point solvent such as acetone, methanol, or the like, and the viscosity thereof can be adjusted.

[0057] By adjusting the composition of the silver particle production composition and the reaction conditions, the average particle size (primary particle size) of the obtained silver particles can be adjusted. In addition, in the present application, from the viewpoint of setting the value of SPAN: (X90-X10) / X50 described above to the specific range described above, as the refining solvent, n-propanol, 1-butanol, or the like is preferably used. The selection of the refining solvent has an influence on the value of SPAN: (X90-X10) / X50 of the silver particles of the present application.

[0058] Method for replacing and adjusting an amine compound or the like on the surface of silver particles By the above-described method, the temporarily synthesized silver particles (to which an amine compound is attached to the surface) are prepared and dispersed in a solvent. As the solvent, the same solvent as that exemplified as the solvent used in the synthesis process of the silver particles can be exemplified, and ethanol, n-propanol, isopropanol, 1-butanol, or the like is preferably used. Note that the selection of the solvent used when the replacement and adjustment of the compound (1) on the surface of the silver particles is performed has an influence on the value of SPAN: (X90-X10) / X50 of the silver particles of the present application. Next, the other compound (1) is added in an amount of 0.1 to 5 times the mass of the silver particles, and a process of applying stirring at room temperature to 80°C for 1 minute to 24 hours is performed, whereby the amine compound attached to the surface of the silver particles can be replaced with the compound (1). The silver particles in which the amine compound on the surface is replaced with the compound (1) can be recovered by the above-described solid-liquid separation method or the like. As the solvent used at the time of this solid-liquid separation, ethanol, n-propanol, isopropanol, 1-butanol, or the like is preferably used. As for the selection of this solvent, the value of SPAN: (X90-X10) / X50 of the silver particles of the present application is influenced.

[0059] 3. Electrically conductive adhesive The conductive adhesive of the present application is characterized by containing the silver particles of the present application. That is, the conductive adhesive of the present application contains the silver particles of the present application and a solvent. Details of the silver particles of the present application and the solvent are as described above.

[0060] The conductive adhesive of the present application can contain a resin in addition to the silver particles of the present application and the solvent. The resin is not particularly limited, and the resin used in the known conductive adhesive containing silver particles can also be used in the present application, and examples include thermoplastic resins, thermosetting resins, and the like. As the thermoplastic resin, examples include polyurethane resins, acrylic resins, methacrylic resins, polyvinyl alcohol resins, vinyl acetate resins, polycarbonate resins, polyorganosiloxane-based resins, polyamide resins, and the like, and mixtures thereof can also be used. As the thermosetting resin, examples include epoxy resins, acrylic resins, silicone resins, polyurethane resins, vinyl ester resins, phenol resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, polyimide resins, and the like. In the present application, as specific examples of the preferred solvent, examples include diethylene glycol monohexyl ether (octanol / water partition coefficient: 1.7), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (octanol / water partition coefficient: 3.2), isopropyl alcohol (octanol / water partition coefficient: 0.05), 2-ethyl-1,3-hexanediol (octanol / water partition coefficient: 1.60), diethylene glycol mono-2-ethylhexyl ether (octanol / water partition coefficient: 2.23), butyl carbitol (octanol / water partition coefficient: 0.56), butyl carbitol acetate (octanol / water partition coefficient: 2.9), butanediol (octanol / water partition coefficient: -0.34), and the like. Particularly preferred solvents are diethylene glycol monohexyl ether (octanol / water partition coefficient: 1.7), 2-ethyl-1,3-hexanediol (octanol / water partition coefficient: 1.60), diethylene glycol mono-2-ethylhexyl ether (octanol / water partition coefficient: 2.23), and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (octanol / water partition coefficient: 3.2). In the case where the conductive adhesive of the present application further contains a solvent, the solvent contained in the conductive adhesive can be one or two or more. α - Pinol (octanol / water partition coefficient: 2.98), diethylene glycol (octanol / water partition coefficient: -1.98), ethylene glycol (octanol / water partition coefficient: -1.36), 2-ethyl-1,3-hexanediol (octanol / water partition coefficient: 1.60), diethylene glycol mono-2-ethylhexyl ether (octanol / water partition coefficient: 2.23), butyl carbitol (octanol / water partition coefficient: 0.56), butyl carbitol acetate (octanol / water partition coefficient: 2.9), butanediol (octanol / water partition coefficient: -0.34), and the like. Particularly preferred solvents are diethylene glycol monohexyl ether (octanol / water partition coefficient: 1.7), 2-ethyl-1,3-hexanediol (octanol / water partition coefficient: 1.60), diethylene glycol mono-2-ethylhexyl ether (octanol / water partition coefficient: 2.23), and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (octanol / water partition coefficient: 3.2). In the case where the conductive adhesive of the present application further contains a solvent, the solvent contained in the conductive adhesive can be one or two or more.

[0061] The content of silver particles in the conductive adhesive of the present application is preferably 80% by mass or more, more preferably 85% by mass or more, further preferably 88% by mass or more, and, in addition, preferably 95% by mass or less, more preferably 93% by mass or less, further preferably 92% by mass or less, and, as a preferable range, 80% by mass to 95% by mass, 85% by mass to 93% by mass, 88% by mass to 92% by mass, and the like can be given. In addition, in the case where the conductive adhesive of the present application contains a resin, the content of the resin in the conductive adhesive of the present application is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, further preferably 0.01% by mass or more, and, in addition, preferably 10% by mass or less, more preferably 7% by mass or less, further preferably 3% by mass or less, and, as a preferable range, 0.001% by mass to 10% by mass, 0.005% by mass to 7% by mass, 0.01% by mass to 3% by mass, and the like can be given.

[0062] 4. Sintered body of electrically conductive adhesive The sintered body of the conductive adhesive of the present application is obtained by sintering the conductive adhesive of the present application described in "2. Conductive adhesive" above. In the sintered body of the conductive adhesive of the present application, the components (compound (1) and the like) adhered to the surface of the silver particles and the solvent are mostly removed by the high heat at the time of sintering, and the sintered body is substantially composed of silver.

[0063] The sintering temperature is not particularly limited, and, for example, 300°C or lower, preferably around 150°C to 250°C, and more preferably around 200°C to 250°C can be given. The sintering time is preferably around 0.4 hours to 2.0 hours, and more preferably around 0.5 hours to 1.2 hours. The conductive adhesive of the present application can be sintered with or without pressure. In the case where pressure is applied, the pressure is, for example, around 10 MPa to 30 MPa. The sintering can be performed in an atmosphere of air, an inert gas (nitrogen, argon), and the like. In the present application, a nitrogen atmosphere is particularly preferable. The sintering means is not particularly limited, and, for example, an oven, a hot air type drying furnace, an infrared drying furnace, laser irradiation, flash lamp irradiation, microwaves, and the like can be given.

[0064] 5. Electronic component The electronic component of the present application has a portion between members bonded with the sintered body of the present application. That is, the electronic component of the present application is obtained by disposing the conductive adhesive of the present application described in detail in the above "2. Conductive adhesive" between members of an electronic component (for example, between members included in a circuit), sintering the conductive adhesive, and bonding the members. In the present application, as the members to be bonded, copper, silver, gold, nickel, aluminum, and the like can be selected, and more preferably, copper, silver, gold, and particularly copper members are used as the members to be bonded (for example, between copper members, between a copper member and a gold member, and between a copper member and a silver member). Examples

[0065] The present application is more specifically described in the following examples, but the present application is not limited to these examples.

[0066] Details of each component used in the examples and comparative examples are described below. • Silver oxalate ((COOAg)2) was synthesized by the method described in Japanese Patent No. 5574761. • N,N-diethyl-1,3-diamino propane (manufactured by FUJIFILM Wako Pure Chemical Corporation) • 2-ethylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) • 2-hydroxyisobutyric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) • n-hexylamine (carbon number 6, manufactured by FUJIFILM Wako Pure Chemical Corporation) • 2-(2-aminoethylamino)ethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) • ricinoleic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) • ethylene glycol (manufactured by FUJIFILM Wako Pure Chemical Corporation) • 1-butanol (manufactured by FUJIFILM Wako Pure Chemical Corporation) • isopropyl alcohol (manufactured by FUJIFILM Wako Pure Chemical Corporation) • 2-ethyl-1,3-hexanediol (manufactured by FUJIFILM Wako Pure Chemical Corporation) • diethylene glycol mono-2-ethylhexyl ether (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0067] Silver particles were manufactured in the following order. When the amount was required for evaluation, the sample amount required for increasing the number of tests in the same manner was prepared.

[0068] <Synthesis Example 1: Synthesis of Silver Particles 1> Silver particles 1 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.05 g), N,N-diethyl-l,3-diamino propane (4.1 g), and 1-butanol (7.5 g) were put, and after stirring for about 1 minute, silver oxalate (5 g) was put, and stirred for about 10 minutes, thereby obtaining a silver particles 1 production composition. Then, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The process of adding isopropyl alcohol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion liquid (isopropyl alcohol solution), 2-ethylhexanoic acid 15 g of the mass of the silver particles was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the process of adding 2-ethyl-l,3-hexanediol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and silver particles 1 were recovered.

[0069] <SYNTHESIS EXAMPLE 2: SYNTHESIS OF SILVER PARTICLES 2> Silver particles 2 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.13 g), N,N-diethyl-l,3-diamino propane (4.1 g), 1-butanol (3.8 g), ethylene glycol (3.8 g) were put, and after stirring for about 1 minute, silver oxalate (5 g) was put, and stirred for about 10 minutes, thereby obtaining a silver particles 2 production composition. Then, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion (isopropyl alcohol solution), 2-ethylhexanoic acid 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the 2-ethyl-l,3-hexanediol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles 2 were recovered.

[0070] <SYNTHESIS EXAMPLE 3: SYNTHESIS OF SILVER PARTICLES 3> Silver particles 3 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, 2-(2-aminoethylamino)ethanol (1.74 g) and 1-butanol (7.5 g) were charged, and after stirring for about 1 minute, silver oxalate (5 g) was charged, and stirring was performed for about 10 minutes, thereby obtaining a silver particles 3 production composition. Then, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) equipped with an aluminum block, and stirring was performed at 40°C for 30 minutes, and further at 90°C for 30 minutes. After cooling, the magnetic stirrer was removed, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The process of adding isopropyl alcohol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion liquid (isopropyl alcohol solution), 2-ethylhexanoic acid 15 g was added, and stirring was performed at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the process of adding 2-ethyl-1,3-hexanediol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and the silver particles 3 were recovered.

[0071] <SYNTHESIS EXAMPLE 4: SYNTHESIS OF SILVER PARTICLES 4> Silver particles 4 dispersed in a solvent were produced by the following procedure. To a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.05 g), N,N-diethyl-l,3-diamino propane (4.1 g), and 1-butanol (7.5 g) were added, and after stirring for about 1 minute, silver oxalate (5 g) was added, and stirred for about 10 minutes, thereby obtaining a silver particle 4 preparation composition. Then, the glass centrifuge tube was set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion (isopropyl alcohol solution), 2-hydroxyisobutyric acid 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the 2-ethyl-l,3-hexanediol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles 4 were recovered.

[0072] <SYNTHESIS EXAMPLE 5: SYNTHESIS OF SILVER PARTICLES 5> Silver particles 5 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.13 g), N,N-diethyl-l,3-diamino propane (4.1 g), 1-butanol (3.8 g), ethylene glycol (3.8 g) were put, and after stirring for about 1 minute, silver oxalate (5 g) was put, and stirred for about 10 minutes, thereby obtaining a silver particle 5 preparation composition. Then, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion (isopropyl alcohol solution), 2-hydroxyisobutyric acid 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the 2-ethyl-l,3-hexanediol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles 5 were recovered.

[0073] <SYNTHESIS EXAMPLE 6: SYNTHESIS OF SILVER PARTICLES 6> The silver particles 6 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, 2-(2-aminoethylamino)ethanol (1.74 g) and 1-butanol (7.5 g) were put, and after stirring for about 1 minute, silver oxalate (5 g) was put, and stirred for about 10 minutes, thereby obtaining a silver particle 6 production composition. Then, the glass centrifuge tubes were vertically set on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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 taken out, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The process of adding isopropyl alcohol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion liquid (isopropyl alcohol solution), 2-hydroxyisobutyric acid 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was taken out, isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the process of adding 2-ethyl-1,3-hexanediol 15 g, stirring, centrifugation, and removing the supernatant was repeated twice, and the silver particles 6 were recovered.

[0074] <SYNTHESIS EXAMPLE 7: SYNTHESIS OF SILVER PARTICLES 7> Silver particles 7 dispersed in a solvent were produced by the following procedure. To a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.05 g), N,N-diethyl-l,3-diamino propane (4.1 g), and 1-butanol (7.5 g) were added, and after stirring for about 1 minute, silver oxalate (5 g) was added, and stirred for about 10 minutes, thereby obtaining a silver particle 7 preparation composition. Then, the glass centrifuge tube was set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Machinery Mfg. Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion (isopropyl alcohol solution), 15 g of n-hexylamine was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the diethylene glycol mono-2-ethylhexyl ether 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles 7 were recovered.

[0075] <SYNTHESIS EXAMPLE 8: SYNTHESIS OF SILVER PARTICLES 8> Silver particles 8 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, castor oil acid (0.13 g), N,N-diethyl-l,3-diamino propane (4.1 g), 1-butanol (3.8 g), ethylene glycol (3.8 g) were put, and after stirring for about 1 minute, silver oxalate (5 g) was put, and stirred for about 10 minutes, thereby obtaining a silver particle 8 production composition. Then, the glass centrifuge tubes were set upright on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Instruments Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles were recovered. Next, using the obtained silver particle dispersion (isopropyl alcohol solution), n-hexylamine 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 3000 rpm (centrifugal acceleration of about 1600 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the n-hexylamine 15 g addition, stirring, centrifugation, and supernatant removal procedures were repeated twice, and the silver particles 8 were recovered.

[0076] <SYNTHESIS EXAMPLE 9: SYNTHESIS OF SILVER PARTICLES 9> The silver particles 9 dispersed in a solvent were produced by the following procedure. Into a 50 mL glass centrifuge tube equipped with a magnetic stirrer, 2-(2-aminoethylamino)ethanol (1.74 g) and 1-butanol (7.5 g) were charged, and after stirring for about 1 minute, silver oxalate (5 g) was charged, and stirred for about 10 minutes, to thereby obtain a silver particle 9 production composition. Then, the glass centrifuge tube was vertically set on a hot stirrer (HHE-19G-U manufactured by Shikoku Precision Machinery Mfg. Co., Ltd.) 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, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. The process of isopropyl alcohol 15 g addition, stirring, centrifugation, and supernatant removal was repeated twice, and the silver particles were recovered. Next, using the obtained dispersion liquid (isopropyl alcohol solution) of the silver particles, n-hexylamine 15 g was added, and stirred at room temperature for 4 hours. After stirring, the magnetic stirrer was removed, and isopropyl alcohol 15 g was added to each composition, and after stirring with a vortex mixer, centrifugation was performed at 2500 rpm (centrifugal acceleration of about 1110 x G) for 1 minute with a centrifuge (Hitachi-Koki CF7D2), and the supernatant was removed by tilting the centrifuge tube. Next, the process of diethylene glycol mono-2-ethylhexyl ether 15 g addition, stirring, centrifugation, and supernatant removal was repeated twice, and the silver particles 9 were recovered.

[0077] For each of the obtained silver particles 1 to 9, observation with a scanning electron microscope (SEM image acquisition), average particle diameter (volume-based average particle diameter) measurement, particle size distribution measurement, and TG-DTA measurement were performed under the following conditions, respectively.

[0078] <Observation with an Electron Microscope> For each of the silver particles obtained in the examples and comparative examples, a scanning electron microscope (SEM (JSM-IT500HR manufactured by JEOL Ltd.)) was used to acquire SEM images.

[0079] <Measurement of Average Particle Diameter (Volume-Based Average Particle Diameter)> For each of the SEM images (lateral width 1 μ m to 20 μ m) acquired in the above <Observation with an Electron Microscope>, the volume-based average particle diameter (primary particle diameter) of 200 particles randomly selected was measured using image analysis software (MacView (manufactured by MOUNTECH Co., Ltd.)). For the longitudinal direction of the SEM image, the lateral width 1 μ m to 20 μrange of m. Note that, for the longitudinal direction of the SEM image, the width of 1 pixel is set to 1 nm μ m ~ 20 μ width of 200 or more (typically, about 200 to 300) silver particles in the range of m. Note that the volume-based average particle diameter is a value determined by assuming that the particles observed in the SEM image are spherical with this diameter. The results are shown in Table 1.

[0080] <Light Transmission Centrifugal Sedimentation Method> For each of the obtained silver particles 1 to 9, the value of SPAN was found by the light transmission centrifugal sedimentation method. SPAN: (X90 - X10) / X50... (1) When the particle diameter is expressed in a cumulative distribution, The particle diameter at which the cumulative particle diameter distribution is 10% is X10. The particle diameter at which the cumulative particle diameter distribution is 90% is X90. The particle diameter at which the cumulative particle diameter distribution is 50% is X50 (median particle diameter).

[0081] (Measurement Conditions for SPAN) A sample for measurement was prepared by diluting the silver particles to a concentration of 50 mass% in the above solvent. The solvent for the sample for measurement was a solvent having an octanol / water partition coefficient (Log Pow) of -2 or more and less than 4. In a 50-ml vial, each of the silver particles (1 to 9) was diluted with 2-ethyl-l,3-hexanediol for silver particles 1 to 6 and with diethylene glycol mono-2-ethylhexyl ether for silver particles 7 to 9 so that the silver component was 50 mass% and the solvent was 50 mass%, for a total of 100%. A vortex mixer was used for mixing during the dilution, and the particles were dispersed for 2 minutes at 2000 rpm. At this time, if the particles did not appear to be dispersed (solid component remained) to the naked eye, the particles were dispersed using rough mixing with a spatula or the like, a rotation-revolution mixer, or the like. When using a rotation-revolution mixer, the particles were stirred in a manner that achieved a balance between rotation and revolution and the particles did not settle. In addition, when preparing the sample for measurement using the silver particle dispersion liquid obtained by dispersing the silver particles as the sample for measurement, the solvent in which the silver particles were dispersed was used as the diluent to prepare the sample for measurement. When using a plurality of solvents in the dispersion liquid, the plurality of solvents were used to dilute the dispersion liquid at an equal amount. SPAN ((X90-X10) / X50) was measured using a dispersion evaluation / particle size distribution device LS-610 manufactured by LUM Japan. Specifically, 0.2 ml of the sample for measurement was filled into a glass cell (a glass cell having a light path length of 2 mm), and the sample was subjected to low-speed rotation at a centrifugal acceleration of 130 G under conditions of 25°C, and data for 500 points were obtained at intervals of 5 seconds, and then the sample was subjected to high-speed rotation at a centrifugal acceleration of 1160 G, and data for 500 points were obtained at intervals of 5 seconds. From the gas-liquid interface (the liquid surface of the sample for measurement) to the solid-liquid interface (the interface between the settled silver particles and the solvent) of the above sample for measurement, three points were arbitrarily selected, and each of the three points was analyzed at a node width of 1 mm. The settling velocity was calculated from the moving distance of the particles and the time required for the movement, and the particle size was converted using the viscosity and the refractive index of the solvent used, and the particle sizes X90, X10, and X50 were obtained. SPAN was calculated using Equation (1). The light factor at the time of measurement was set to 6. Note that if a glass cell is not used at the time of measurement, the silver particles can be fixed and light can be blocked, and thus the light intensity (absorbance) cannot be measured accurately. In addition, if the light factor is not set to 6, the light intensity is not sufficient in terms of the properties of the measurement object, such as a high-concentration metal particle dispersion liquid. Therefore, in order to measure the secondary particle state of a high-concentration particle dispersion liquid, the light factor needs to be set to 6. When measuring the shape of the secondary particles by the same principle, attention needs to be paid to the light source of the measurement device. Furthermore, if the nodes (analysis widths) overlap each other, the number of points obtained as the measurement profile number (the number of measurement points) is not appropriate, and thus the analysis needs to be performed in a manner that the nodes do not overlap each other. The measurement results are shown in Table 1.

[0082] Manufacture of Conductive Adhesive Using each of the silver particles obtained in the Examples and Comparative Examples, a conductive adhesive was manufactured in the following order, respectively.

[0083] The silver particles 1 to 9 obtained in the Synthesis Examples were mixed with a solvent (2-ethyl-l,3-hexanediol for the silver particles 1 to 6, and diethylene glycol mono-2-ethylhexyl ether for the silver particles 7 to 9), thereby preparing a conductive adhesive. Specifically, for each of the silver particles 1 to 9, diethylene glycol mono-2-ethylhexyl ether was added so that the content of silver in the conductive adhesive would be 90 mass%, and a silver particle dispersion liquid having a concentration of 90 mass% was prepared. In the mixing, a MAZERUSTAR manufactured by Kurabo Co., Ltd. was used, and the mixing was performed using a 2-time stirring priority mode. Thus, each of the conductive adhesives for the manufacture of sintered bodies was obtained.

[0084] Manufacture of Sintered Body (in Air) The dispersion of the silver particles (conductive adhesive) obtained in the Examples and Comparative Examples was sintered in an air atmosphere, respectively, to manufacture a sintered body. First, an Ag member (a silver plating layer having a thickness of 3 μ m on the surface of a Cu member) was prepared. The conductive adhesive (silver particle dispersion liquid of 90 mass% of silver particles, 10 mass% of 2-ethyl-l,3-hexanediol in the case of the silver particles 1 to 6, and 10 mass% of diethylene glycol mono-2-ethylhexyl ether in the case of the silver particles 7 to 9) was uniformly applied to the substrate (the surface on which the silver plating layer was formed) so that the coating film thickness would be 50 μ m. Further, on the coating film, a silicon wafer (size 2 mm x 2 mm) to which a gold plating layer (thickness 1 μ m) was applied to the back surface (the surface in contact with the conductive adhesive) was laminated, to obtain a laminate. Next, using a dryer (circulation type), the obtained laminate was heated under the sintering conditions of a prescribed sintering temperature (temperature increase at a rate of 3°C / min to 200°C or 225°C, and 60 minutes at (200°C or 225°C)), and each of the conductive adhesives between the substrate and the silicon wafer was sintered, to obtain 9 laminates in which the substrate and the silicon wafer were joined via a sintered body.

[0085] Manufacture of Sintered Body (in Nitrogen) The dispersion of the silver particles (conductive adhesive) obtained in the Examples and Comparative Examples was sintered in a nitrogen atmosphere, respectively, to manufacture a sintered body. First, an Ag member, an Au member (a gold plating layer having a thickness of 50 nm on the surface of a Cu member), and a Cu member (C1020) were prepared. Next, on the surface of each of the members, the conductive adhesive was applied so that the coating film thickness would be 50 μThe conductive adhesive (silver particle 90 mass%, and silver particle 1 to 6 in the case of 2-ethyl-l,3-hexanediol 10 mass%, silver particle 7 to 9 in the case of diethylene glycol mono-2-ethylhexyl ether 10 mass%) was uniformly applied in the manner of a bar coater. Further, on the coated film, a silicon wafer (size 2 mm x 2 mm) on which a gold plating layer was applied to the back surface (the surface in contact with the conductive adhesive) was laminated, to obtain a laminate. Subsequently, using a nitrogen furnace, the obtained laminate was heated under sintering conditions of a prescribed sintering temperature (temperature increase at a rate of 3°C / min to 200°C or 225°C, and 60 minutes at (200°C or 225°C)), and each of the conductive adhesives between the substrate and the silicon wafer was sintered, to obtain a laminate in which nine substrates and silicon wafers were joined via sintered bodies.

[0086] <Mechanical strength (shear strength) of sintered body> For the laminate obtained in the production of the above sintered body, a dieshear test was performed on each of the laminates using a bond tester (Shimadzu Corporation SS30-WD) at room temperature, under conditions of 0.120 mm / s, to apply a load to the sintered body, and the maximum load at the time of breakage was measured. The maximum load thus obtained was divided by the joining area, to thereby obtain a shear strength value. Note that the measurement result is the average value of the nine gold-plated silicon wafers for which the shear strength was measured. The measurement result of the shear strength is shown in Tables 1 to 3.

[0087] [Table 1]

[0088] *1: 2EHA (2-ethylhexanoic acid) *2: HBA (2-hydroxyisobutyric acid) *3: HA (hexylamine) *4: EHD (2-ethyl-l,3-hexanediol) *5: EHDG (diethylene glycol mono-2-ethylhexyl ether)

[0089] As is clear from the results shown in Table 1, the silver particles of Example 1, in which 2-ethylhexanoic acid was used for the protective layer as the conductive adhesive using silver particles having an average particle diameter of about 100 nm, had a very high mechanical strength of the sintered body obtained under a nitrogen atmosphere (particularly the sintered body formed on the surface of the copper member), as compared with the conventional silver particles (Comparative Examples 1 and 2) in which 2-hydroxyisobutyric acid or n-hexylamine was used for the protective layer. The conductive adhesive using silver particles having an average particle diameter of about 100 nm is particularly suitable for use in the joining of power devices in thin film form, solar cell applications, and the like, which require sintering under a nitrogen atmosphere.

[0090] [Table 2]

[0091] *1: 2EHA (2-ethylhexanoic acid) *2: HBA (2-hydroxyisobutyric acid) *3: HA (hexylamine) *4: EHD (2-ethyl-1,3-hexanediol) *5: EHDG (diethylene glycol mono-2-ethylhexyl ether)

[0092] As is apparent from the results shown in Table 2, the silver particles of Example 2, which are a conductive adhesive using silver particles having an average particle diameter of about 200 nm and in which 2-ethylhexanoic acid is used for the protective layer, have a very high mechanical strength of the sintered body obtained under a nitrogen atmosphere (particularly, the sintered body formed on the surface of a copper member) as compared with the conventional silver particles (Comparative Examples 3 and 4) in which 2-hydroxyisobutyric acid or hexylamine is used for the protective layer. The conductive adhesive using silver particles having an average particle diameter of about 200 nm is particularly suitable for use in applications such as the joining portion of a power device, a power amplifier, and the like, which require sintering under a nitrogen atmosphere.

[0093] [Table 3]

[0094] *1: 2EHA (2-ethylhexanoic acid) *2: HBA (2-hydroxyisobutyric acid) *3: HA (hexylamine) *4: EHD (2-ethyl-1,3-hexanediol) *5: EHDG (diethylene glycol mono-2-ethylhexyl ether).

[0095] As is apparent from the results shown in Table 3, the silver particles of Example 3, which are a conductive adhesive using silver particles having an average particle diameter of about 500 nm and in which 2-ethylhexanoic acid is used for the protective layer, have a very high mechanical strength of the sintered body obtained under a nitrogen atmosphere (particularly, the sintered body formed on the surface of a copper member) as compared with the conventional silver particles (Comparative Examples 5 and 6) in which 2-hydroxyisobutyric acid or hexylamine is used for the protective layer. The conductive adhesive using silver particles having an average particle diameter of about 500 nm is particularly suitable for use in applications such as the joining portion of a power device in a thick film form, which requires sintering under a nitrogen atmosphere.

Claims

1. Silver particles, characterized in that A compound represented by the following general formula (1) is attached to the surface of silver particles, In General Formula (1), R 1 is an alkyl group having 2 to 8 carbon atoms, R 2 is an alkyl group having 1 to 4 carbon atoms, and R 3 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

2. The silver particles according to claim 1, wherein, The average particle diameter of the silver particles is 60 nm to 600 nm.

3. The silver particles according to claim 1, wherein, The silver particles are dispersed in a solvent.

4. The silver particles according to claim 3, wherein, When the concentration of the silver particles in the solvent is set to 50% by mass, the value of SPAN determined by a light transmission type centrifugal sedimentation method under the following conditions is 0.1 or more and 5.0 or less, SPAN: (X90 - X10) / X50... Formula (1) When the particle diameter is expressed in a cumulative distribution, The particle diameter at which the cumulative particle diameter distribution is 10% is X10, The particle diameter at which the cumulative particle diameter distribution is 90% is X90, The particle diameter at which the cumulative particle diameter distribution is 50% is the median particle diameter X50, Measurement conditions of SPAN: A measurement sample in which the concentration of the silver particles in the solvent is 50% by mass is prepared; as the solvent of the measurement sample, a solvent having an octanol / water partition coefficient Log Pow of -2 or more and 4 or less is used; 0.2 ml of the measurement sample is filled into a glass cell having an optical path length of 2 mm, and low-speed rotation is performed at a centrifugal acceleration of 130 G at 25°C, data of 500 points are obtained at intervals of 5 seconds, and then high-speed rotation is performed at a centrifugal acceleration of 1160 G, data of 500 points are obtained at intervals of 5 seconds, three points are arbitrarily selected between the gas-liquid interface and the solid-liquid interface of the measurement sample, the three points are analyzed at a node of 1 mm width, respectively, the sedimentation velocity is calculated from the moving distance of the particles and the time required for the movement, the particle diameter is converted using the viscosity and the refractive index of the solvent used, the particle diameters X90, X10, and X50 are obtained, and SPAN is calculated by Formula (1), The gas-liquid interface is the liquid surface of the measurement sample, and the solid-liquid interface is the interface between the settled silver particles and the solvent.

5. An electrically conductive adhesive, characterized by The silver particles according to claim 1 or 2.

6. An electrically conductive adhesive, characterized by The silver particles according to claim 1 or 2 and a resin.

7. A sintered body of the conductive adhesive according to claim 5.

8. An electronic component in which members are joined by using the sintered body according to claim 7.

Images