Composite microparticles

Abstract

The present invention provides composite microparticles that can be sintered at low pressure and low temperature and that can suppress the occurrence of cracks and fractures due to sintering, a method for manufacturing composite microparticles, a dispersion of composite microparticles, and a copper bonding layer and wiring pattern which are sintered bodies of the composite microparticles. [Solution] A composite microparticle in which at least a portion of the surface of copper microparticles is coated with a dispersant, the average particle size D50 of the composite microparticles is 50 nm or more and 350 nm or less, in the particle size histogram based on the number of composite microparticles, the particle size D10 when the cumulative frequency is 10% and the particle size D90 when the cumulative frequency is 90% satisfy the relationship D90 / D10 ≤ 4.0, and the dispersant is a vinyl polymer having a carboxyl group and containing a structure represented by the following formula (1). In the following formula (1), R 1 R is a hydrogen atom or a methyl group. 2 This refers to an organic group containing a cyclic structure or an organic group containing a chain structure having a linear chain with 3 or more carbon atoms. [Formula 1] JPEG2026092685000014.jpg3563

Description

[Technical Field]

[0001] The present invention relates to composite microparticles, a method for producing composite microparticles, a dispersion of composite microparticles, and a copper bonding layer and wiring pattern, etc. [Background technology]

[0002] Copper has excellent electrical and thermal conductivity, and is therefore widely used as a conductive wiring material, heat transfer material, heat exchange material, and heat dissipation material. Because of its excellent thermal conductivity, copper is sometimes used as a substitute for solder when joining objects.

[0003] In recent years, semiconductor devices called power devices have become widely used as power conversion and control devices such as inverters. Unlike integrated circuits such as memory and microprocessors, power devices are designed to control high currents, resulting in high heat generation during operation, or so-called operating temperature. In particular, with the advent of wide-bandgap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN), it is possible to control even higher currents, but operating temperatures exceeding 200°C are also anticipated. Therefore, the solder used to mount power devices requires not only bonding strength but also heat resistance. However, lead-free solder, which is widely used these days, has the disadvantage of low heat resistance. As a result, various technologies have been proposed that use a metal particle dispersion, which contains dispersed metal particles, as a substitute for solder. This dispersion is then applied to the target object using various coating methods, sintered, and used to join the objects to be joined. The metal species used in the metal particle dispersion for mounting are mainly silver or copper. On the other hand, when joining parts using metal particle dispersions, pressure and heat are applied, but if done at high pressures of 20 MPa or higher and high temperatures of 350°C or higher, there is a risk of damaging the semiconductor chip of the power device. Therefore, dispersions using metal nanoparticles with high surface energy, so-called large specific surface area, are often used so that joining can be done at low pressures of 20 MPa or lower and low temperatures of 350°C or lower. Among these, silver bonding layers formed by silver nanoparticle dispersions, when exposed to high temperatures of 200°C or higher, repeatedly undergo bonding and expansion of pores in the bonding layer, leading to pore coarsening and ultimately fracture. In contrast, copper bonding layers formed by copper particle dispersions show little bonding and expansion of pores even when exposed to high temperatures of 200°C or higher, and have high thermal stability, making them promising as next-generation bonding materials.

[0004] Patent Document 1 discloses a copper nanoparticle dispersion containing copper nanoparticles A dispersed in polymer B having a specific monomer composition and a specific acid value, and a specific dispersion medium C, and states that a bonded body with improved bonding strength can be obtained using this copper nanoparticle dispersion even after storage for a certain period of time. Patent Document 2 discloses a sintered powder containing copper fine particles for die attachment, wherein the particles are at least partially coated with a predetermined type and amount of capping agent, and the sintered powder exhibits a D10 of 100 nm or more and a D90 of 2000 nm or less. It is stated that this sintered powder exhibits advantageous sintering properties while being less susceptible to oxidation than conventional copper-containing sintered powders. Patent Document 3 discloses spherical copper fine powder obtained by a disproportionation reaction, characterized in that the average particle size of the copper fine powder measured by a laser diffraction particle size distribution analyzer is 0.25 μm or less, and the powder has only a single peak in particle size distribution, and that it is particularly effective as a powder for use in internal electrodes of multilayer ceramics. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2023 / 013034 [Patent Document 2] Japanese Patent Publication No. 2022-169512 [Patent Document 3] Japanese Patent Publication No. 2012-126942 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] While copper bonding materials containing copper nanoparticles have higher heat resistance than solder, there is still room for improvement when used in power devices operating at temperatures exceeding 200°C. Specifically, even when using copper bonding materials containing copper nanoparticles with excellent low-temperature sinterability, cracks may occur in the copper bonding layer during or after sintering, or the layer may rupture due to thermal shrinkage caused by temperature changes after sintering. Such cracks or ruptures reduce heat dissipation in the copper bonding layer, hindering the stable operation of the power device. Furthermore, copper wiring formed using copper bonding materials containing copper nanoparticles may not function adequately as wiring. The present invention aims to provide composite microparticles that can be sintered at low temperatures and that can suppress the occurrence of cracks and fractures due to sintering, a method for producing composite microparticles, a dispersion of composite microparticles, a copper bonding layer and wiring pattern which are sintered bodies of the composite microparticles, a bonding body which includes a sintered body of composite microparticles as a copper bonding layer, and a method for producing the bonding body. [Means for solving the problem]

[0007] The inventors have found that composite microparticles having a specific average particle diameter D50, satisfying the relationship D90 / D10 ≤ 4.0 in a particle diameter histogram based on particle count, and comprising copper microparticles and a specific dispersant coating at least a portion of their surface, can solve the above problem. In other words, the present invention relates to the following [1] to [8]. [1] Composite fine particles in which at least a portion of the surface of copper fine particles is coated with a dispersant, The average particle diameter D50 of the composite fine particles is 50 nm or more and 350 nm or less, in the particle size histogram of the composite fine particles based on the number of particles, the particle diameter D10 when the cumulative frequency is 10% and the particle diameter D90 when the cumulative frequency is 90% satisfy the relationship of D90 / D10 ≦ 4.0, the composite fine particles, wherein the dispersant has a carboxy group and is a vinyl polymer containing a structure represented by the following formula (1). [Chemical formula] In the above formula (1), R 1 is a hydrogen atom or a methyl group, R 2 is an organic group containing a cyclic structure or an organic group containing a linear structure having a straight chain of 3 or more carbon atoms, and n is a number of 1 or more and 1000 or less. [2] A method for producing composite fine particles in which at least a part of the surface of copper fine particles is coated with a dispersant, including a step of dropping a reducing agent into a mixed solution containing a copper raw material compound, a dispersant, and a solvent having an SP value of 8 or more and 18 or less, the dispersant has a carboxy group and is a vinyl polymer containing a structure represented by the following formula (1), a method for producing composite fine particles, wherein the dropping rate of the reducing agent with respect to 1 mol of copper in the copper raw material compound is 0.01 mol / min or more. [Chemical formula] In the above formula (1), R 1 is a hydrogen atom or a methyl group, R 2 is an organic group containing a cyclic structure or an organic group containing a linear structure having a straight chain of 3 or more carbon atoms, and n is a number of 1 or more and 1000 or less. [3] A composite fine particle dispersion containing the composite fine particles described in [1] above. [4] A copper bonding layer which is a sintered body of the composite fine particles described in [1] above. [5] A wiring pattern which is a sintered body of the composite fine particles described in [1] above. [6] A joined body in which metal members are joined via a copper bonding layer, The bonded body, wherein the copper bonding layer is a sintered body of the composite fine particles described in [1]. [7] A method for manufacturing a bonded body in which metal members are bonded via a copper bonding layer, applying the composite fine particle dispersion described in [3] to one of the metal members, placing the other metal member on the composite fine particle dispersion applied to the one metal substrate, and pressurizing and firing these, the method for manufacturing a bonded body including these steps. [8] Use of the composite fine particle dispersion described in [3] as a bonding material for bonding metal members. [Advantages of the Invention]

[0008] According to the present invention, there can be provided composite fine particles capable of low-temperature sintering and suppressing the generation of cracks and fractures due to sintering, a method for manufacturing the composite fine particles, a composite fine particle dispersion, a copper bonding layer and a wiring pattern which are sintered bodies of the composite fine particles, a bonded body including a sintered body of the composite fine particles as a copper bonding layer, and a method for manufacturing the bonded body. [Embodiments for Carrying Out the Invention]

[0009] [Composite Fine Particles] The composite fine particles of the present invention are composite fine particles including copper fine particles and a dispersant covering at least a part of the surface of the copper fine particles, where the average particle diameter D50 of the composite fine particles is 50 nm or more and 350 nm or less, in the particle diameter histogram based on the number of the composite fine particles, the particle diameter D10 when the cumulative frequency is 10% and the particle diameter D90 when the cumulative frequency is 90% satisfy the relationship D90 / D10 ≦ 4.0, and the dispersant is a vinyl polymer having a carboxy group and including a structure represented by the following formula (1). [Chemical Formula] In the above formula (1), R 1 is a hydrogen atom or a methyl group, R 2 is an organic group including a cyclic structure or an organic group including a linear chain having 3 or more carbon atoms, and n is a number of 1 or more and 1000 or less.

[0010] The composite microparticles of the present invention can be sintered at low temperatures, and the occurrence of cracks and fractures due to sintering can be suppressed. The reason for this is not entirely clear, but it is thought to be as follows. The composite microparticles of the present invention have an average particle diameter D50 of 50 nm to 350 nm, and at least a portion of the surface of the copper microparticles is coated with a dispersant that is a vinyl polymer containing a predetermined structure. The particle diameters D10 and D90 in the particle diameter histogram based on the number of composite microparticles satisfy the relationship D90 / D10 ≤ 4.0. Therefore, the composite microparticles of the present invention are relatively small particles, and are dispersed in the dispersion medium by the dispersant that coats at least a portion of the surface of the copper microparticles, resulting in uniform dispersion of particles and suppression of aggregation. Furthermore, because the particle diameters of the individual composite microparticles are close, their surface energy values ​​are also similar, and it is thought that sintering proceeds uniformly. As a result, the resulting copper bonding layer has a uniform and strong structure, and it is thought that the occurrence of cracks and fractures due to sintering can be significantly suppressed. On the other hand, if the particle size histogram based on the number of composite microparticles does not satisfy the relationship D90 / D10 ≤ 4.0, the variation in particle size becomes large, which may cause an unevenness in the degree of sintering, resulting in an ununiform sintered body and making it prone to cracks and fractures in the areas where distortion occurs. Furthermore, composite microparticles that satisfy the above characteristics can be suitably manufactured by a wet chemical reduction method using a solvent with an SP value of 8 to 18, and by dropping a reducing agent into the solvent at a predetermined dropping rate.

[0011] In this specification, "low-temperature sintering" means sintering at a temperature of 300°C or lower. Furthermore, the copper nanoparticles are granular copper components derived from the copper raw material compound used in the manufacturing method of composite nanoparticles, which will be described in detail later, and are produced by the reduction of the copper raw material compound. The copper component preferably consists only of copper, but may contain some unavoidable impurities. The copper content in the copper component is preferably 95% by mass or more, more preferably 98% by mass or more, even more preferably 99% by mass or more, and even more preferably substantially 100% by mass. "Substantially 100% by mass" means that it may contain components that are unintentionally included (unavoidable impurities).

[0012] The average particle size D50 of the composite fine particles (primary particles) of the present invention is 50 nm to 350 nm, from the viewpoint of improving sinterability at low temperatures and suppressing the occurrence of cracks and fractures due to sintering. The average particle size D50 of these composite fine particles is preferably 60 nm or more, more preferably 65 nm or more, from the viewpoint of providing good oxidation resistance and suppressing shrinkage during sintering, and from the viewpoint of improving the density of the sintered body, suppressing the occurrence of cracks and fractures, and improving sinterability at low temperatures, it is preferably 300 nm or less, more preferably 250 nm or less, even more preferably 210 nm or less, and even more preferably 175 nm or less. The average particle size D50 of the composite microparticles is the particle size D50 at which the cumulative frequency is 50% in the particle size histogram based on the number of particles shown below. Specifically, it is measured by the method described in the examples. The average particle size D50 of the composite microparticles can be adjusted by the copper raw material compound used in the production of the composite microparticles, the type and amount of reducing agent, the type and amount of dispersant, the type and amount of solvent, and the production conditions of the composite microparticles, such as the temperature and time of the reduction reaction (the duration for which the temperature of the reduction reaction is maintained), as described later.

[0013] In the present invention, the composite microparticles satisfy the relationship D90 ≤ 4.0 in the ratio [D90 / D10] of the particle size D90 at a cumulative frequency of 90% to the particle size D10 at a cumulative frequency of 10% in a particle size histogram based on the number of particles. The ratio [D90 / D10] is an indicator of the spread of the particle size distribution, and a smaller value means that the particle size distribution is narrower and the particle sizes are more uniform. This ratio [D90 / D10] is preferably 4.0 or less, more preferably 3.5 or less, and more preferably 3.1 or less, from the viewpoint of uniformly advancing sintering to improve the density of the sintered body and suppressing the occurrence of cracks and fractures. Furthermore, from the viewpoint of high close-packing of composite fine particles, improving the density of the sintered body, suppressing the occurrence of cracks and fractures, and ease of manufacturing composite fine particles, it is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.1 or more, and even more preferably 2.3 or more. This ratio [D90 / D10] is calculated for composite microparticles by determining the particle size D10 when the cumulative frequency is 10% and the particle size D90 when the cumulative frequency is 90% from a particle size histogram based on the particle size of each particle measured from scanning electron microscope (SEM) images of the composite microparticles. The ratio [D90 / D10] is then determined from the calculated D10 and D90. Specifically, it is measured by the method described in the examples. This ratio [D90 / D10] can be adjusted by the copper raw material compound used in the production of the composite fine particles described later, the type and amount of reducing agent, the type and amount of dispersant, the type and amount of solvent, and the production conditions of the composite fine particles, such as the temperature and time of the reduction reaction (the duration for which the temperature of the reduction reaction is maintained).

[0014] Here, the particle size D10 of the composite fine particles (primary particles) is preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 40 nm or more, from the viewpoint of improving oxidation resistance and suppressing shrinkage during sintering, thereby suppressing the occurrence of cracks and fractures. Furthermore, from the viewpoint of improving the density of the sintered body and suppressing the occurrence of cracks and fractures, it is preferably 105 nm or less, more preferably 100 nm or less, even more preferably 95 nm or less, and even more preferably 90 nm or less.

[0015] <Dispersant> The composite microparticles of the present invention are preferably used as a composite microparticle dispersion for forming a conjugate by being dispersed in a dispersion medium as described later. Therefore, from the viewpoint of improving the dispersibility of the composite microparticles, suppressing the uneven distribution due to the aggregation of the composite microparticles when obtaining a sintered body, and allowing sintering to proceed uniformly, the composite microparticles include copper microparticles and a dispersant that coats at least a part of the surface of the copper microparticles.

[0016] As the dispersant, a vinyl polymer having a carboxy group is used from the viewpoint of improving the dispersion stability of the composite microparticles, improving the denseness of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. A vinyl polymer refers to a polymer obtained by the addition polymerization of monomers having a vinyl group, and examples thereof include acrylic resins, styrene resins, styrene-acrylic resins, acrylic silicone resins, and the like. As the vinyl polymer used in the present invention, a vinyl polymer having a carboxy group and containing a structure represented by the following formula (1) is used.

Chemical formula

[0017] In this vinyl polymer, R 1 is a hydrogen atom or a methyl group, and from the viewpoint of improving its stability, it is preferably a methyl group.

[0018] In this vinyl polymer, the organic group containing a cyclic structure represented by R 2 may be an organic group containing one or more structures selected from the group consisting of an aromatic ring structure and an alicyclic structure. In the alicyclic structure, all bonds may be formed by saturated bonds, or may be formed with some unsaturated bonds. Further, a heteroatom may be contained in the cyclic structure. Examples of aromatic ring structures in this cyclic structure include benzene, naphthalene, anthracene, and phenanthrene. Furthermore, from the viewpoint of better demonstrating the effects of the present invention, the number of ring-forming carbon atoms in the aromatic ring is preferably 5 to 10. Specifically, the aromatic ring structure is preferably benzene. Furthermore, examples of alicyclic structures in this cyclic structure include monocyclic structures such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, cyclododecane, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, and cyclododecene, as well as polycyclic structures such as norbornane, adamantane, norbornene, and adamantene. From the viewpoint of further demonstrating the effects of the present invention, the number of ring-forming carbon atoms in the alicyclic structure is preferably 5 to 10. Specifically, the alicyclic structure is preferably cyclohexane.

[0019] In this vinyl polymer, R 2 An organic group containing a chain structure represented by (excluding organic groups containing the cyclic structure) is any organic group containing a chain structure having a straight chain with 3 or more carbon atoms, and the chain structure may contain heteroatoms. This chain structure may be either a straight chain or a branched chain, and preferably contains an alkylene oxide structure.

[0020] This vinyl polymer R 2 The number of carbon atoms constituting the linear structure of the organic group containing the chain structure represented by is preferably 5 or more, more preferably 15 or more, even more preferably 25 or more, even more preferably 35 or more, and even more preferably 45 or more, from the viewpoint of improving the dispersion stability of the composite fine particles and suppressing the occurrence of cracks and fractures due to sintering, and is preferably 200 or less, more preferably 150 or less, even more preferably 100 or less, and even more preferably 60 or less, from the viewpoint of improving the sinterability of the composite fine particles and suppressing the occurrence of cracks and fractures due to sintering.

[0021] This vinyl polymer R 2The linear structure of an organic group containing a chain structure represented by includes, for example, an alkylene structure or an alkylene oxide structure. When, for example, an alkylene structure (meth)acrylate is used as a monomer as a raw material for the production of vinyl polymers, R 2 is -COO-R 3 -(Here, R 3 This is a linear or branched alkylene group having 2 or more carbon atoms. The number of carbon atoms constituting the chain structure is at least 3. Furthermore, when using an ethylene oxide structure (meth)acrylate as a monomer, R 2 is -COO-(CH2-CH2-O) n The structure is represented by -, and the number of carbon atoms constituting the chain structure is at least 3 when n=1, and at least 5 when n=2. Here, n represents the repeating unit and is a number of 1 or more, preferably 2 or more, more preferably 3 or more, even more preferably 15 or more, even more preferably 20 or more, and preferably 100 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, and even more preferably 35 or less.

[0022] This vinyl polymer R 2 The sum of the atomic weights of the atoms constituting the organic group represented by is preferably 50 or more, more preferably 100 or more, even more preferably 500 or more, and even more preferably 800 or more, from the viewpoint of improving the dispersibility of the composite fine particles and suppressing the occurrence of cracks and fractures due to sintering, and is preferably 5000 or less, more preferably 3500 or less, and even more preferably 2000 or less, from the viewpoint of improving the sinterability of the composite fine particles and suppressing the occurrence of cracks and fractures due to sintering.

[0023] This vinyl polymer is preferably a polymer of a monomer having a carboxyl group and a monomer represented by the following formula (2). [ka] In equation (2) above, R1 and R 2 This is the same organic group as the one in formula (1).

[0024] Among these, the dispersant is preferably a vinyl polymer containing constituent units derived from a monomer (p-1) having a carboxyl group and a monomer (p-2) having a (poly)alkylene glycol segment, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. The vinyl polymer may be a random copolymer, a block copolymer, or an alternating copolymer. Here, "having a (poly)alkylene glycol segment" means that the monomer (p-2) has an alkylene glycol segment or a polyalkylene glycol segment.

[0025] [Carboxylated monomer (p-1)] Preferred monomers (p-1) include unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, and 2-methacryloyloxymethylsuccinic acid; and unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid, and citraconic acid. The unsaturated dicarboxylic acid may also be an anhydride. The monomer (p-1) may be used alone or in combination of two or more types. The monomer (p-1) is preferably one or more selected from the group consisting of (meth)acrylic acid and maleic acid, more preferably (meth)acrylic acid, and even more preferably methacrylic acid, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, suppressing the occurrence of cracks and fractures, as well as from the viewpoint of availability and economy. In this specification, "(meth)acrylic acid" means one or more selected from the group consisting of acrylic acid and methacrylic acid.

[0026] [(Poly)alkylene glycol segment-containing monomer (p-2)] Examples of monomers (p-2) include alkylene glycol (meth)acrylate, polyalkylene glycol (meth)acrylate, alkoxy polyalkylene glycol (meth)acrylate, and phenoxy polyalkylene glycol (meth)acrylate. Monomers (p-2) may be used individually or in combination of two or more. In this specification, "(meth)acrylate" means one or more selected from the group consisting of acrylates and methacrylates.

[0027] From the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body, and suppressing the occurrence of cracks and fractures, the monomer (p-2) is preferably one or more selected from the group consisting of alkylene glycol (meth)acrylate, polyalkylene glycol (meth)acrylate, and alkoxy polyalkylene glycol (meth)acrylate, more preferably one or more selected from the group consisting of alkylene glycol (meth)acrylate and alkoxy polyalkylene glycol (meth)acrylate, and even more preferably alkoxy polyalkylene glycol (meth)acrylate. From the viewpoint of the same as above, the number of carbon atoms in the alkoxy polyalkylene glycol (meth)acrylate is preferably 18 or less, more preferably 12 or less, even more preferably 4 or less, and even more preferably 1. Examples of the alkylene glycol (meth)acrylate include hydroxypropyl (meth)acrylate. Examples of preferred alkoxy polyalkylene glycol (meth)acrylates include methoxypolyalkylene glycol (meth)acrylate, ethoxypolyalkylene glycol (meth)acrylate, propoxypolyalkylene glycol (meth)acrylate, butoxypolyalkylene glycol (meth)acrylate, octoxypolyalkylene glycol (meth)acrylate, and lauroxypolyalkylene glycol (meth)acrylate. Among these, methoxypolyalkylene glycol (meth)acrylate is more preferred, and methoxypolyalkylene glycol methacrylate is even more preferred.

[0028] The (poly)alkylene glycol segment of monomer (p-2) preferably contains units derived from alkylene oxide having 2 to 4 carbon atoms, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, suppressing the occurrence of cracks and fractures, as well as from the viewpoint of availability and economy. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, and preferably one or more selected from the group consisting of ethylene oxide and propylene oxide, and more preferably ethylene oxide. The number of alkylene oxide-derived units in the (poly)alkylene glycol segment is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, even more preferably 15 or more, even more preferably 20 or more, and preferably 100 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, and even more preferably 35 or less, from the viewpoint of improving the dispersion stability of the composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. The (poly)alkylene glycol segment may be a copolymer containing ethylene oxide-derived units and propylene oxide-derived units, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, suppressing the occurrence of cracks and fractures, as well as from the viewpoint of availability and economic efficiency. The copolymer containing units derived from ethylene oxide and units derived from propylene oxide may be a random copolymer, a block copolymer, or an alternating copolymer.

[0029] From the viewpoint of improving the dispersion stability of the composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures, the monomer (p-2) is preferably one or more selected from hydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate, more preferably one or more selected from hydroxypropyl (meth)acrylate and methoxypolyethylene glycol (meth)acrylate, even more preferably one or more selected from hydroxypropyl methacrylate and methoxypolyethylene glycol methacrylate, and even more preferably methoxypolyethylene glycol methacrylate. From the viewpoint of improving the dispersion stability of the composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures, the monomer (p-2) is preferably 2 or more, more preferably 3 or more, even more preferably 15 or more, even more preferably 20 or more, and preferably 100 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, and even more preferably 35 or less.

[0030] Specific examples of commercially available monomers (p-2) include NK ester AM-90G, AM-130G, AM-230G, AMP-20GY, M-20G, M-40G, M-90G, M-230G, etc., manufactured by Shin Nakamura Chemical Industry Co., Ltd.; and Bremmer PE-90, PE-200, PE-350, PME-100, P, etc., manufactured by NOF Corporation. Examples include ME-200, PME-400, PME-1000, PME-4000, PP-500, PP-500D, PP-800, PP-1000, PP-2000D, AP-150, AP-400, AP-550, 50PEP-300, 50POEP-800B, 43PAPE-600B, and PLE-1300.

[0031] [Hydrophobic monomer (p-3)] The vinyl polymer may further contain constituent units derived from hydrophobic monomers (p-3) to improve the density of the sintered body formed by sintering and to suppress the occurrence of cracks and fractures. In this specification, "hydrophobic monomer" means a monomer in which the amount dissolved when dissolved in 100 g of deionized water at 25°C until saturated is less than 10 g. The amount of monomer (p-3) dissolved is preferably 5 g or less, more preferably 1 g or less, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures. The monomer (p-3) is preferably one or more selected from the group consisting of aromatic group-containing monomers and (meth)acrylates having hydrocarbon groups derived from aliphatic alcohols.

[0032] Examples of aromatic group-containing monomers include styrene monomers and aromatic group-containing (meth)acrylates. The molecular weight of the aromatic group-containing monomer is preferably less than 500. Examples of styrene monomers include styrene, α-methylstyrene, 2-methylstyrene, 4-vinyltoluene (4-methylstyrene), and divinylbenzene. Examples of aromatic group-containing (meth)acrylates include phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0033] Examples of (meth)acrylates having hydrocarbon groups derived from aliphatic alcohols include (meth)acrylates having linear alkyl groups, (meth)acrylates having branched alkyl groups, and (meth)acrylates having alicyclic alkyl groups. Examples of (meth)acrylates having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. Examples of (meth)acrylates having branched alkyl groups include isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, isopentyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, isododecyl (meth)acrylate, isostearyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. As a (meth)acrylate having an alicyclic alkyl group, cyclohexyl (meth)acrylate is a preferred example.

[0034] The vinyl polymer preferably contains, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures, a constituent unit derived from one or more selected from (meth)acrylic acid and maleic acid as monomer (p-1), and a constituent unit derived from hydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate as monomer (p-2), more preferably a constituent unit derived from (meth)acrylic acid as monomer (p-1), and a constituent unit derived from hydroxypropyl (meth)acrylate and methoxypolyethylene glycol (meth)acrylate as monomer (p-2).

[0035] The content of monomer (p-1) in the raw material monomer during the production of vinyl polymers, or the content of monomer (p-1)-derived constituent units in the total constituent units of the vinyl polymer, is preferably 3% by mass or more, more preferably 5% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. Furthermore, the content of monomer (p-2) in the raw material monomer during the production of vinyl polymers, or the content of monomer (p-2)-derived constituent units in the total constituent units of the vinyl polymer, is preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and preferably 97% by mass or less, more preferably 95% by mass or less, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures.

[0036] In the present invention, the total content of monomer (p-1) and monomer (p-2) in the raw material monomer during the production of vinyl polymers, or the total content of constituent units derived from monomer (p-1) and monomer (p-2) in all constituent units of the vinyl polymer, is preferably 90% by mass or more, more preferably 97% by mass or more, and even more preferably substantially 100% by mass, from the viewpoint of improving the dispersion stability of composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. Here, "substantially 100% by mass" means that it may include components that are included unintentionally. Examples of components that are included unintentionally include monomers other than monomer (p-1) and monomer (p-2) contained in the raw material monomer (p-1) and monomer (p-2), so-called impurities.

[0037] The weight-average molecular weight Mw of the vinyl polymer is preferably 3,000 or more, more preferably 6,000 or more, and preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 17,000 or less, and even more preferably 10,000 or less, from the viewpoint of improving the dispersion stability of the composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. The weight-average molecular weight Mw is measured by the method described in the examples.

[0038] The acid value of the vinyl polymer is preferably 10 mg KOH / g or more, more preferably 20 mg KOH / g or more, even more preferably 30 mg KOH / g or more, and even more preferably 40 mg KOH / g or more, and preferably 250 mg KOH / g or less, more preferably 230 mg KOH / g or less, and even more preferably 210 mg KOH / g or less, from the viewpoint of improving the dispersion stability of the composite fine particles, improving the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. The acid value of vinyl polymers can be measured by the method described in the examples, but it can also be calculated from the mass ratio of the constituent monomers.

[0039] In the composite fine particles of the present invention, the ratio of the mass of the dispersant to the total mass of the copper fine particles and the dispersant [dispersant / (copper fine particles + dispersant)] (hereinafter also referred to as the "dispersant mass ratio") is preferably 0.001 or higher, more preferably 0.003 or higher, even more preferably 0.005 or higher, even more preferably 0.009 or higher, and preferably 0.020 or lower, more preferably 0.018 or lower, even more preferably 0.016 or lower, and even more preferably 0.014 or lower. The mass ratio of the dispersant is calculated from the content of composite microparticles and the content of the dispersant in the composite microparticle dispersion using a differential thermogravimetric / thermogravimetric analysis (TG / DTA) system. Specifically, it is measured by the method described in the examples.

[0040] [Method for manufacturing composite microparticles] The present invention relates to a method for producing composite microparticles, which includes a composite microparticle production step in which a copper raw material compound is reduced by a wet chemical reduction method to produce the composite microparticles. For example, this method involves mixing a copper raw material compound, a reducing agent, and a solvent, and then reducing the copper raw material compound with the reducing agent. Here, it is preferable to mix the copper raw material compound, a dispersant, a solvent, and a reducing agent to obtain a dispersion of composite microparticles containing copper microparticles and a dispersant that disperses the copper microparticles in the solvent, and then dry the dispersion of composite microparticles by freeze-drying or the like. In the dried composite microparticle powder obtained in this way, part or all of the surface of the copper microparticles is coated with the dispersant.

[0041] Furthermore, in one embodiment, the method for producing composite fine particles of the present invention is a method for producing composite fine particles that includes copper fine particles and a dispersant that coats at least a portion of the surface thereof. The process includes adding a reducing agent dropwise to a mixture containing a copper raw material compound, a dispersant, and a solvent with an SP value of 8 to 18. The dispersant is a vinyl polymer having a carboxyl group and a structure represented by the following formula (1): The dropping rate of the reducing agent relative to 1 mole of copper in the copper raw material compound is 0.01 mol / min or higher.

[0042] [ka] In the above equation (1), R 1 R is a hydrogen atom or a methyl group. 2 n is an organic group containing a cyclic structure or an organic group containing a chain structure having 3 or more carbon atoms, and n is a number between 1 and 1000. The preferred vinyl polymers are as described above. In one embodiment, the method for producing composite fine particles of the present invention preferably includes maintaining a mixture containing a copper raw material compound, a dispersant, and a solvent with an SP value of 8 to 18 for at least one minute, preferably at a predetermined temperature below the boiling point of the solvent, for the reduction of the copper raw material compound.

[0043] The temperature of the reduction reaction in the composite fine particle manufacturing process, in other words, the temperature for reducing the copper raw material compound in the mixture of the copper raw material compound, reducing agent, dispersant, and solvent, more specifically, the temperature of the reaction solution containing the mixture of the copper raw material compound, dispersant, and solvent and the reducing agent dropped into the mixture (the predetermined temperature), is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 30°C or higher, even more preferably 50°C or higher, and even more preferably 60°C or higher, from the viewpoint of increasing the specific surface area of ​​the composite fine particles and making the particle size distribution uniform. Furthermore, from the viewpoint of suppressing the generation of bubbles and making the particle size distribution uniform, it is preferably carried out in a range of less than the boiling point of the solvent, more preferably 2.5°C or less below the boiling point of the solvent, and even more preferably 5°C or less below the boiling point of the solvent. In other words, the predetermined temperature is preferably less than the boiling point of the solvent, more preferably 2.5°C or more below the boiling point of the solvent, and even more preferably 5°C or more below the boiling point of the solvent. The upper limit of the reduction reaction temperature varies depending on the solvent used, but from the viewpoint of suppressing foam generation and ensuring a uniform particle size distribution, it is preferably 75°C or lower, more preferably 73°C or lower. The reduction of the copper raw material compound may be carried out in an air atmosphere or in an inert gas atmosphere such as nitrogen gas. From the viewpoint of suppressing foam generation and ensuring a uniform particle size distribution, the maintenance time for the reduction reaction temperature is preferably 1 minute or more, more preferably 30 minutes or more, and even more preferably 1 hour or more. From the viewpoint of productivity, it is preferably 30 hours or less, more preferably 20 hours or less, and even more preferably 10 hours or less.

[0044] There are no particular restrictions on the copper raw material compound, as long as it contains copper. Examples of copper raw material compounds include copper sulfate, copper nitrate, cupric oxide, cuprous oxide, copper formate, copper acetate, and copper oxalate. Among these, the copper raw material compound is preferably one or more selected from copper oxides such as cupric oxide and cuprous oxide, and more preferably cupric acid value, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures. The copper raw material compound can be used individually or as a mixture of two or more types.

[0045] There are no particular restrictions on the reducing agent, as long as it is a compound that can reduce copper raw material compounds. Examples of reducing agents include hydrazine compounds, boron compounds, and inorganic salts. Examples of hydrazine compounds include hydrazine, hydrazine hydrochloride, hydrazine sulfate, and hydrazine monohydrate. Examples of boron compounds include sodium borohydride. Examples of inorganic acid salts include sodium sulfite, sodium bisulfite, sodium thiosulfate, sodium nitrite, sodium hyponitrite, phosphorous acid, sodium phosphite, hypophosphorous acid, and sodium hypophosphite. Among these, as a reducing agent, from the viewpoint of productivity and uniform particle size distribution, it is preferably one or more selected from the group consisting of hydrazine and hydrated hydrazine (hydrazine monohydrate), and even more preferably hydrated hydrazine (hydrazine monohydrate). The reducing agent may be used individually or in combination of two or more types.

[0046] In the aforementioned composite microparticle manufacturing process, a solvent that leaves minimal foam during manufacturing is preferred for dispersing the copper raw material compound and the reducing agent, because if foam remains, the particles will aggregate starting from that point. This is because, from the viewpoint of achieving a uniform particle size distribution, a solvent that leaves minimal foam during manufacturing is preferable.

[0047] The solubility parameter (SP value) of the solvent is preferably 18 or less, more preferably 16 or less, even more preferably 14 or less, and even more preferably 13 or less, from the viewpoint of reducing foam persistence and ensuring a uniform particle size distribution, and preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more, from the viewpoint of uniformly dispersing the reducing agent and ensuring a uniform particle size distribution. Here, the SP value is a value calculated by the Fedors method (see "Polym.Eng.Sci.14(2)152,(1974)"). Note that the upper and lower limits of the numerical range in this invention are included in the equivalent range of this invention, even if they fall slightly outside the numerical range specified by this invention, as long as they have the same effects and advantages as those within the numerical range specified by this invention.

[0048] Examples of solvents include methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol. Among these, ethanol is preferred as the solvent from the viewpoint of reducing foam persistence, ensuring a uniform particle size distribution, and from the viewpoint of availability and cost-effectiveness. The solvent may be used alone or in combination of two or more.

[0049] When adding the reducing agent dropwise to the copper raw material compound and solvent, the amount (dropping rate) of the reducing agent added is preferably 0.01 mol / min or more per 1 mol of copper in the copper raw material compound, from the viewpoint of making the primary particle size of the composite fine particles uniform and improving the density of the sintered body formed by sintering, thereby suppressing the occurrence of cracks and fractures. More preferably, this amount (dropping rate) is 0.02 mol / min or more, even more preferably 0.05 mol / min or more, and even more preferably 0.10 mol / min or more. Furthermore, from the viewpoint of stably producing composite fine particles, it is preferably 2.00 mol / min or less, more preferably 1.50 mol / min or less, even more preferably 1.00 mol / min or less, even more preferably 0.80 mol / min or less, even more preferably 0.50 mol / min or less, and even more preferably 0.40 mol / min or less.

[0050] In the production of composite microparticles, from the viewpoint of removing impurities such as unreacted reducing agents and excess dispersants that do not contribute to the dispersion of copper microparticles, the dispersion of composite microparticles may be purified after obtaining it, before freeze-drying. There are no particular limitations on the method for purifying the composite microparticles, and methods such as decantation, dialysis, membrane treatment such as ultrafiltration, and centrifugation of the dispersion of the composite microparticles are possible. Among these, centrifugation is preferred from the viewpoint of efficiently removing impurities.

[0051] [Composite fine particle dispersion] The composite microparticle dispersion of the present invention is a composite microparticle dispersion containing the composite microparticles and dispersion medium of the present invention. The composite microparticles are as described above, and their description is omitted. <Dispersion medium> The dispersion medium used here can be any solvent capable of dispersing the composite fine particles, and preferably one or more organic solvents selected from the group consisting of hydrocarbons, alcohols, ethers, and esters. The organic solvent may be used alone or in combination of two or more. Furthermore, the organic solvent is more preferably one or more selected from the group consisting of alcohols, ethers, and esters, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures, and even more preferably one or more selected from the group consisting of aliphatic monohydric alcohols, (poly)alkylene glycols, (poly)alkylene glycol derivatives, glycerin, and glycerin derivatives.

[0052] Examples of aliphatic monohydric alcohols include allyl alcohol, n-heptanol, n-octanol, 2-ethylhexyl alcohol, n-nonanol, n-decanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, hexadecenol, stearyl alcohol, oleyl alcohol, and terpene alcohols.

[0053] (Poly)alkylene glycol is one or more selected from the group consisting of alkylene glycols and polyalkylene glycols. Examples of alkylene glycols include ethylene glycol, propylene glycol, butylene glycol, and neopentyl glycol. Examples of polyalkylene glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (number average molecular weight preferably 100 to 1000, more preferably 150 to 600, and even more preferably 180 to 500), dipropylene glycol, tripropylene glycol, polypropylene glycol (number average molecular weight preferably 150 to 1000, more preferably 180 to 600, and even more preferably 200 to 500), and polytetramethylene glycol.

[0054] Examples of (poly)alkylene glycol derivatives include compounds in which the terminal hydroxyl groups of the (poly)alkylene glycol are etherified or esterified. Specifically, one or more compounds selected from the group consisting of (poly)alkylene glycol alkyl ethers and (poly)alkylene glycol monoalkyl ether acetates are included. (Poly)alkylene glycol alkyl ether is one or more selected from the group consisting of alkylene glycol alkyl ethers and polyalkylene glycol alkyl ethers. Examples of (poly)alkylene glycol alkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether. (Poly)alkylene glycol monoalkyl ether acetate is one or more selected from the group consisting of alkylene glycol monoalkyl ether acetate and polyalkylene glycol monoalkyl ether acetate. Examples of (poly)alkylene glycol monoalkyl ether acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate.

[0055] There are no particular restrictions on glycerin derivatives as long as they are solvents containing a structure derived from glycerin. Examples include glycerin ether derivatives, glycerin ester derivatives, polyglycerin, and glycerin alkylene oxide adducts (e.g., ethylene oxide adducts and propylene oxide adducts). Examples of polyglycerin include diglycerin and triglycerin. Examples of commercially available polyglycerin include polyglycerin #310, polyglycerin #500, and polyglycerin #750 manufactured by Sakamoto Pharmaceutical Co., Ltd. Examples of glycerin ether derivatives include 3-(2-ethylhexyloxy)-1,2-propanediol (boiling point: 325°C, molecular weight 204). Examples of glycerin ester derivatives include glyceryl tributyrate (boiling point: 305°C, molecular weight 302).

[0056] Among these, the dispersion medium is preferably one or more selected from the group consisting of (poly)alkylene glycol and (poly)alkylene glycol alkyl ether, more preferably (poly)alkylene glycol, even more preferably one or more selected from dipropylene glycol and polyethylene glycol, even more preferably one or more selected from dipropylene glycol and polyethylene glycol with a number average molecular weight of 200, and even more preferably a combination of dipropylene glycol and polyethylene glycol with a number average molecular weight of 200.

[0057] <Copper microparticles> The composite fine particle dispersion of the present invention may further contain copper microparticles, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures. The copper content in the copper microparticles is preferably 95% by mass or more, more preferably 98% by mass or more, even more preferably 99% by mass or more, and even more preferably substantially 100% by mass, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures. Here, "effectively 100% by mass" means that it may include components that are present unintentionally. Examples of unintentionally present components include unavoidable impurities.

[0058] The average particle size of the copper microparticles is preferably greater than 0.35 μm, more preferably 0.5 μm or more, even more preferably 0.6 μm or more, even more preferably 0.7 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less, and even more preferably 6 μm or less, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures. The average particle size of copper microparticles is measured by the same method as the average particle size (particle size D50) of the composite fine particles described in the examples.

[0059] <Content of each component in the dispersion> The composite microparticle dispersion of the present invention can be used to manufacture a bonded body by sintering. When the composite microparticle dispersion of the present invention is used to manufacture a bonded body, the content of composite microparticles is preferably 35% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 93% by mass or less, from the viewpoint of improving the dispersibility of the composite microparticles in the dispersion, the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. The content of the dispersant in the dispersion is preferably 0.2% by mass or more, more preferably 0.4% by mass or more, even more preferably 0.5% by mass or more, and preferably 1.3% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.9% by mass or less, and even more preferably 0.8% by mass or less, from the viewpoint of improving the dispersibility of the composite fine particles in the dispersion, the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. From the viewpoint of improving the dispersibility of composite fine particles in the dispersion, the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures, the content of the dispersant in the dispersion, expressed as the mass ratio of the dispersant to the composite fine particles (dispersant / composite fine particles), is preferably 0.001 or more, more preferably 0.003 or more, even more preferably 0.005 or more, even more preferably 0.009 or more, and preferably 0.020 or less, more preferably 0.018 or less, even more preferably 0.016 or less, and even more preferably 0.014 or less. The content of the dispersion medium in the dispersion is preferably 4% by mass or more, more preferably 6% by mass or more, even more preferably 7% by mass or more, and preferably 60% by mass or less, more preferably 25% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of improving the dispersibility of composite fine particles in the dispersion, the density of the sintered body formed by sintering, and suppressing the occurrence of cracks and fractures. Furthermore, if the dispersion contains copper microparticles, from a similar viewpoint, the content of composite fine particles in the dispersion is preferably 30% to 95% by mass, the content of the dispersant is preferably 0.1% to 10% by mass, the content of the dispersion medium is preferably 4% to 60% by mass, and the content of copper microparticles is preferably 0% to 65% by mass. Furthermore, if the dispersion contains copper microparticles, from a similar viewpoint, the content of composite fine particles in the dispersion is preferably 30% by mass or more and 95% by mass or less, the content of the dispersant is preferably 0.001 to 0.020 when expressed as the above mass ratio (dispersant / composite fine particles), the content of the dispersion medium is preferably 4% by mass or more and 60% by mass or less, and the content of copper microparticles is preferably 0% by mass or more and 65% by mass or less.

[0060] The dispersion may contain various additives as components other than those mentioned above, to the extent that they do not impair the effects of the present invention. Examples of such additives include metal particles other than composite fine particles and copper microparticles, sintering accelerators such as glass frit, antioxidants, viscosity modifiers, pH adjusters, buffers, defoamers, leveling agents, and volatilization inhibitors. Examples of metal particles other than composite fine particles and copper microparticles include metal particles such as zinc, nickel, silver, gold, palladium, and platinum. The content of the additive in the dispersion is preferably 1% by mass or less.

[0061] <Method for manufacturing a composite microparticle dispersion> The composite microparticle dispersion according to the present invention can be obtained by adding and mixing a dispersion medium and, if necessary, various additives to the composite microparticles. As for the mixing method, known methods can be used, and from the viewpoint of better dispersing the composite fine particles in the dispersion medium, it is preferable to pre-mix the composite fine particles and the dispersion medium using an agate mortar or the like, and then further mix the resulting mixture using a stirring device such as a rotation-and-revolution stirring device.

[0062] The composite microparticle dispersion of the present invention obtained in this way can be sintered at low temperatures, has good density in the sintered body formed by sintering, and can suppress the occurrence of cracks and fractures in the sintered body, so it can be used to form conductive members of various electronic and electrical devices. Examples of such conductive members include conductive members that were conventionally formed using conductive bonding agents such as solder. Furthermore, the composite microparticle dispersion of the present invention is preferably used to form conductive members that constitute antennas such as RFID (radio frequency identifier) ​​tags; capacitors such as MLCCs (multilayer ceramic capacitors); electronic paper; image display devices such as liquid crystal displays and organic EL displays; organic EL elements; organic transistors; wiring boards such as printed circuit boards and flexible circuit boards; organic solar cells; and sensors such as flexible sensors. Among these, the composite microparticle dispersion of the present invention is preferably used for joining multiple metal members together or for manufacturing wiring patterns.

[0063] [Wiring Pattern] The wiring pattern of the present invention is a sintered body obtained by heat-treating the composite fine particle dispersion of the present invention described above. In other words, the wiring pattern of the present invention is a sintered body of the composite fine particles of the present invention. Because the composite fine particle dispersion of the present invention has the above-described characteristics, it has excellent low-temperature sinterability, and therefore the wiring pattern of the present invention can be formed at a low temperature of 250°C or below. As a result, the wiring pattern of the present invention can reduce damage to semiconductor chips and the like. Because the wiring pattern of the present invention has the above-mentioned characteristics, it is preferably used in wiring boards such as printed circuit boards and flexible circuit boards, which have low high-temperature resistance of the substrate.

[0064] [Copper bonding layer] The copper bonding layer of the present invention is a sintered body obtained by heat-treating the composite fine particle dispersion of the present invention described above. In other words, the copper bonding layer of the present invention is a sintered body of the composite fine particles of the present invention. The composite fine particle dispersion used here possesses the characteristics described above, allowing for uniform sintering and the formation of a dense copper bonding layer. As a result, crack formation in the copper bonding layer due to sintering is suppressed, and a copper bonding layer with high thermal stability can be formed. Because the copper bonding layer of the present invention has the above-described characteristics, it is preferably used for bonding members to be bonded together in devices that operate at high temperatures.

[0065] [Jointed body and method for manufacturing the same] The composite fine particle dispersion of the present invention is interposed between multiple metal members, and these are then fired at low pressure and low temperature to produce a bonded body in which the multiple metal members are joined via a copper bonding layer. That is, the bonded body obtained here has a metal member-copper bonding layer-metal member structure in which the multiple metal members are joined together by the copper bonding layer formed when the composite fine particle dispersion of the present invention is fired. The metal members are examples of members to be joined. Furthermore, the joint of the present invention is a joint comprising a plurality of metal members and a copper bonding layer disposed between adjacent metal members to bond the adjacent metal members together, wherein the copper bonding layer is a sintered body of the composite fine particles of the present invention. In one embodiment, the present invention relates to a method for manufacturing a joined body, and in one embodiment, the method for manufacturing the joined body includes the following steps 1 to 2 in this order. Step 1: A step of applying the composite fine particle dispersion of the present invention to one main surface of one of the metal members. Step 2: A step in which one metal member is placed on a composite fine particle dispersion applied to one metal member to form a laminate, and the laminate is fired while being pressed in the thickness direction.

[0066] Examples of metal components joined by the copper bonding layer include metal substrates or metal substrates such as gold substrates, gold-plated substrates, silver substrates, silver-plated metal substrates, copper substrates, palladium substrates, palladium-plated metal substrates, platinum substrates, platinum-plated metal substrates, aluminum substrates, nickel substrates, nickel-plated metal substrates, tin substrates, and tin-plated metal substrates; and metal parts such as electrodes of electrically insulating substrates. The multiple metal components used in this invention may be of the same type or of different types. Among these, the metal component preferably includes at least one selected from gold substrates, gold-plated substrates, silver substrates, silver-plated metal substrates, copper substrates, palladium substrates, palladium-plated metal substrates, platinum substrates, platinum-plated metal substrates, aluminum substrates, nickel substrates, nickel-plated metal substrates, tin substrates, tin-plated metal substrates, and the metal portion of an electrically insulating substrate. The joining of metal members in this invention includes joining chip components such as capacitors and resistors to a circuit board; joining semiconductor chips such as memory, diodes, transistors, ICs, and CPUs to a lead frame or circuit board; and joining high-heat-generating semiconductor chips to a cooling plate.

[0067] In forming the wiring pattern and the copper bonding layer, methods for applying the composite fine particle dispersion to the metal member include various coating methods such as slot die coating, dip coating, spray coating, spin coating, doctor bladeding, knife edge coating, and bar coating; and various patterning printing methods such as stencil printing, screen printing, flexographic printing, gravure printing, offset printing, dispenser printing, and inkjet printing. The amount of the composite fine particle dispersion applied to the metal member can be appropriately adjusted according to the size and type of the metal member to be joined.

[0068] In forming the wiring pattern, the heating temperature (firing temperature) for forming the copper sintered body is preferably 150°C or higher, more preferably 160°C or higher, and even more preferably 180°C or higher, from the viewpoint of improving the density of the sintered body and suppressing the occurrence of cracks and fractures, and preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 230°C or lower, from the viewpoint of reducing damage to the semiconductor chip.

[0069] In forming the wiring pattern, the heating time (firing time) for forming the copper sintered body can be appropriately adjusted by the heating temperature and pressurizing pressure. However, from the viewpoint of improving the density of the sintered body and suppressing the occurrence of cracks and fractures, it is preferably 600 seconds or more, more preferably 900 seconds or more, and even more preferably 1200 seconds or more. Furthermore, from the viewpoint of reducing damage to the substrate and semiconductor chip, it is preferably 5400 seconds or less, more preferably 4500 seconds or less, and even more preferably 3600 seconds or less.

[0070] In forming the copper bonding layer, the heating temperature (firing temperature) for forming the bonded body is preferably 200°C or higher, more preferably 230°C or higher, even more preferably 250°C or higher, and even more preferably 280°C or higher, from the viewpoint of strengthening the bond between the composite fine particles and the member to be bonded, such as a metal member. From the viewpoint of reducing damage to the semiconductor chip, it is preferably 350°C or lower, more preferably 330°C or lower, and even more preferably 310°C or lower.

[0071] In forming the copper bonding layer, the pressurizing pressure for forming the bonded body is preferably 5 MPa or higher, more preferably 7 MPa or higher, and even more preferably 10 MPa or higher, from the viewpoint of improving the density of the sintered body and suppressing the occurrence of cracks and fractures, and preferably 30 MPa or lower, more preferably 25 MPa or lower, and even more preferably 22 MPa or lower, from the viewpoint of reducing damage to the semiconductor chip.

[0072] In forming the copper bonding layer, the heating time for forming the bonded body can be appropriately adjusted according to the heating temperature (firing temperature) and the pressure during pressurization. However, from the viewpoint of improving the density of the sintered body formed by sintering and suppressing the occurrence of cracks and fractures, the heating time is preferably 150 seconds or more, more preferably 200 seconds or more, and even more preferably 250 seconds or more. Furthermore, from the viewpoint of reducing damage to the semiconductor chip, the heating time is preferably 3600 seconds or less, more preferably 1800 seconds or less, even more preferably 1200 seconds or less, even more preferably 600 seconds or less, and even more preferably 400 seconds or less.

[0073] The atmosphere in which the low-temperature firing is carried out may be an air atmosphere, an inert gas atmosphere such as nitrogen gas, or a reducing gas atmosphere such as hydrogen gas, but a nitrogen gas atmosphere is more preferable from the viewpoint of suppressing copper oxidation and ensuring safety. [Examples]

[0074] The present invention will be described in more detail below with reference to examples and comparative examples. However, the scope of the present invention is not limited to these examples. Furthermore, in the following manufacturing examples, embodiments, and comparative examples, "parts" and "%" refer to "parts by mass" and "% by mass" respectively, unless otherwise specified. Various physical properties were measured or calculated using the following methods.

[0075] [Measurement of the weight-average molecular weight (Mw) of the dispersant] The weight-average molecular weight (Mw) of the dispersant was determined by gel permeation chromatography. The sample prepared for measurement consisted of 0.1 g of dispersant mixed with 10 mL of eluent in a glass vial, stirred with a magnetic stirrer at 25°C for 10 hours, and filtered through a syringe filter (DISMIC-13HP PTFE 0.2 μm, Advantec Toyo Co., Ltd.). The measurement conditions are shown below. GPC device: Tosoh Corporation "HLC-8320GPC" Columns: Tosoh Corporation products "TSKgel SuperAWM-H, TSKgel SuperAW3000, TSKgel guardcolumn Super AW-H" Eluent: A solution prepared by dissolving phosphoric acid and lithium bromide in N,N-dimethylformamide at concentrations of 60 mmol / L and 50 mmol / L, respectively. Flow rate: 0.5mL / min Standard material: Monodisperse polystyrene kit manufactured by Tosoh Corporation: "PStQuick B (F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-40, F-4, A-5000, A-500)"

[0076] [Measurement of the acid value of dispersants] The acid value of the dispersant was measured in accordance with JIS K0070-1992 (potentiometric titration method). However, the measurement solvent was changed from the ethanol and ether mixture specified in JIS K 0070 to an acetone and toluene mixture (acetone:toluene = 4:6 (volume ratio)).

[0077] [Calculation of the ratio of the mass of the dispersant to the total mass of copper nanoparticles and dispersant [dispersant / (copper nanoparticles + dispersant)]] Using a differential thermogravimetric / thermogravimetric analyzer (TG / DTA) (manufactured by Hitachi High-Tech Science Corporation, product name: STA7200RV), 10 mg of the sample (dried powder of composite microparticles) was weighed into an aluminum pancell and heated from 35°C to 550°C at a heating rate of 10°C / min under a nitrogen flow of 50 mL / min, and the mass loss was measured. The mass loss from 35°C to 550°C was taken as the mass of the dispersant, and the remaining mass at 550°C was taken as the mass of copper microparticles (granular copper component) not coated with the dispersant. The mass ratio [dispersant / (copper microparticles + dispersant)] was calculated using the following formula. Mass ratio [dispersant / (copper nanoparticles + dispersant)] = (mass loss from 35°C to 550°C) / (mass loss from 35°C to 550°C + remaining mass at 550°C)

[0078] [Calculation of D10, D50, D90 and ratio [D90 / D10] of composite microparticles] Scanning electron microscope (SEM) images of composite microparticles were taken using a scanning electron microscope (Hitachi High-Tech Corporation, field emission scanning electron microscope, product name: S-4800). The magnification was determined according to the particle size, and images were taken in the range of 5,000x to 150,000x. The SEM images were analyzed using the image analysis software ImageJ (National Institutes of Health, USA), and the particle size was determined for 1,000 particles per sample. From the particle size histogram based on the determined particle sizes, the particle size D10 at a cumulative frequency of 10%, the particle size D50 (average particle size D50) at a cumulative frequency of 50%, and the particle size D90 at a cumulative frequency of 90% were calculated. Furthermore, the ratio [D90 / D10] was calculated from the calculated D90 and D10.

[0079] [Preparation of dispersant] Preparation Example 1 (Preparation of vinyl polymer P1) A 1000 mL four-necked round-bottom flask equipped with a thermometer, two 100 mL dropping funnels with nitrogen bypasses, and a reflux apparatus was filled with 20.0 g of ethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent). The flask was then heated to 80°C in an oil bath, and nitrogen bubbling was performed for 10 minutes. Separately, 32.5 g of methacrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) as monomer (p-1), 67.5 g of methoxypolyethylene glycol (EO 4 mol) methacrylate (manufactured by NOF Corporation, "PME-200") as monomer (p-2), 3.0 g of mercaptopropanediol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) as a chain transfer agent, and 28.7 g of ethanol were dissolved in a polybeaker and placed into a dropping funnel (A). In addition, 51.3g of ethanol and 1.3g of 2,2'-azobis(isobutyrate)dimethyl (V-601, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., polymerization initiator) were dissolved in a poly beaker and placed in a dropping funnel (B). Next, the respective mixtures in dropping funnel (A) and dropping funnel (B) were simultaneously added dropwise to the contents of the four-necked round-bottom flask over a period of 90 minutes while stirring. Subsequently, the internal temperature of the four-necked round-bottom flask was raised to 90°C, and stirring was continued for another hour to complete the reaction. After the reaction was complete, the resulting polymer solution was freeze-dried using a freeze-dryer (FDU-2110, manufactured by Tokyo Rikakikai Co., Ltd., model: FDU-2110) equipped with a dry chamber (DRC-1000, manufactured by Tokyo Rikakikai Co., Ltd.) under drying conditions (freezing at -25°C for 1 hour, reduced pressure at -10°C for 9 hours, reduced pressure at 25°C for 5 hours; vacuum degree 5 Pa) to obtain vinyl polymer P1. The monomer composition and physical properties are shown in Table 1.

[0080] Preparation Examples 2-7 (Preparation of vinyl polymers P2-P7) Vinyl polymers P2 to P7 were obtained by performing the same procedure as in Production Example 1, except that the types and amounts of monomer (p-1), monomer (p-2), and chain transfer agent were changed to those shown in Table 1. Weight-average molecular weight, acid value, R 2 Table 1 shows the sum of the atomic weights of the constituent atoms.

[0081] [Table 1]

[0082] • MAA: Methacrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) • PEG(4)MA: Methoxypolyethylene glycol (EO4 mol) methacrylate (manufactured by NOF Corporation, "PME-200") • PEG(9)MA: Methoxypolyethylene glycol (EO9 mol) methacrylate (manufactured by NOF Corporation, "PME-400") • PEG(23)MA: Methoxypolyethylene glycol (EO23 mol) methacrylate (manufactured by NOF Corporation, "PME-1000") • HPMA: Hydroxypropyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0083] [Manufacturing of composite microparticles] Example 1 (Production of composite microparticles 1) In a 2L beaker, 50.0g of cupric oxide (N-120, manufactured by Nisshin Chemco Co., Ltd.), 2.0g of vinyl polymer P1, and 500g of ethanol (95), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., first-grade reagent, were added and the mixture was stirred for 90 minutes to obtain a mixed solution. During stirring, the temperature of the mixed solution was controlled to 70°C using an oil bath. Next, 63.0 g of hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), placed in a 100 mL dropping funnel, was added dropwise to the mixture over 13 minutes at 25°C. Subsequently, the reaction solution containing the mixture and the added hydrazine monohydrate (reducing agent) was stirred for 1 hour while controlling the temperature to 70°C in an oil bath, and then air-cooled to obtain a reddish-brown dispersion containing composite fine particles. The entire volume of the obtained dispersion was placed in a Hitachi Koki Co., Ltd. refrigerated centrifuge "himacCR22G" and rotor (R12A, radius 15.1 cm) into a Hitachi Koki Co., Ltd. 500PA centrifuge tube bottle and subjected to a centrifugal acceleration of 675 G at 3000 rpm for 15 minutes. The precipitate was separated by centrifugation, and 300 g of ethanol (95) (Fujifilm Wako Pure Chemical Industries, Ltd., first-grade reagent) was added. The mixture was stirred for 15 minutes to redisperse the precipitate. The entire volume of the redispersed solution was again centrifuged under the same conditions, and the precipitate was separated. This procedure was repeated twice. The precipitate of the purified composite microparticles was freeze-dried using a freeze-dryer (FDU-2110, manufactured by Tokyo Rikakikai Co., Ltd., model: DRC-1000) equipped with a dry chamber, yielding 36.5 g of composite microparticle 1. The drying conditions were: freezing at -25°C for 1 hour, then vacuum drying at -10°C for 9 hours at 5 Pa, and finally vacuum drying at 25°C for 5 hours at 5 Pa to obtain the dried powder of composite microparticle 1.

[0084] Examples 2-6, 9 (Production of composite microparticles 2-6, 9) Composite fine particles 2-6 and 9 were obtained by the same procedure as in Example 1, except that vinyl polymer P1 was changed to vinyl polymers P2-P7 shown in Tables 2 and 3.

[0085] Example 7 (Manufacturing of composite microparticles 7) Composite microparticles 7 were obtained in the same manner as in Example 1, except that vinyl polymer P1 was replaced with vinyl polymer P5, and 63.0 g of hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) was added dropwise to the mixture over 60 minutes.

[0086] Example 8 (Production of composite microparticles 8) Composite microparticles 8 were obtained in the same manner as in Example 1, except that vinyl polymer P1 was replaced with vinyl polymer P5, and 63.0 g of hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) was added dropwise to the mixture over 6 minutes.

[0087] Comparative Example 1 (Manufacturing of composite microparticles C1) In a 2L beaker, 88.4g of copper sulfate pentahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), 0.7g of vinyl polymer P7, and 1000g of deionized water were added. The mixture was stirred at 40°C using a magnetic stirrer until it became visually clear to obtain the mixed solution. Next, 17.8 g of hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), placed in a 50 mL dropping funnel, was added dropwise to the mixture over 60 minutes at 25°C. Subsequently, the reaction solution containing the mixture and the added hydrazine monohydrate (reducing agent) was stirred for 5 hours while controlling the temperature to 40°C in an oil bath, and then air-cooled to obtain a reddish-brown dispersion containing composite fine particles. The entire volume of the obtained dispersion was placed into a dialysis tube (REPLIGEN, product name: Spectra / Pore 6, dialysis membrane: regenerated cellulose, molecular weight cutoff (MWCO) = 50K), and the top and bottom of the tube were sealed with a closeer. This tube was immersed in 5L of deionized water in a 5L glass beaker, and dialysis was performed by stirring for 1 hour while maintaining the water temperature at 20-25°C. This dialysis procedure was repeated, with the entire volume of deionized water being replaced after each 1-hour stirring. A sample was taken before replacing the deionized water, and the dialysis was terminated when the conductivity of the dispersion of composite microparticles fell to 7 mS / m or less, to obtain the dispersion of composite microparticles. Conductivity was measured by diluting the sampled solution with deionized water to adjust the copper concentration to 1%. The precipitate of the purified composite microparticles was freeze-dried using a freeze-dryer (Tokyo Rikakikai Co., Ltd., model: FDU-2110) equipped with a dry chamber (Tokyo Rikakikai Co., Ltd., model: DRC-1000) to obtain 20.8 g of composite microparticles C1. The drying conditions were to freeze at -25°C for 1 hour, then dry under reduced pressure at -10°C for 9 hours at 5 Pa, and then dry under reduced pressure at 25°C for 5 hours at 5 Pa to obtain the dried powder of composite microparticles C1.

[0088] Comparative Example 2 (Manufacturing of composite microparticles C2) A dried powder of composite fine particles C2 was obtained in the same manner as in Example 1, except that vinyl polymer P1 was replaced with vinyl polymer P5, and 63.0 g of hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) was added dropwise to the mixture over 600 minutes.

[0089] Comparative Example 3 (Manufacturing of composite microparticles C3) A dried powder of composite fine particles C3 was obtained in the same manner as in Example 1, except that the vinyl polymer P1 was replaced with polyacrylic acid.

[0090] Comparative Example 4 (Manufacturing of composite microparticles C4) A dried powder of composite fine particles C4 was obtained in the same manner as in Example 1, except that vinyl polymer P1 was replaced with vinyl polymer P5 and ethanol was replaced with deionized water.

[0091] The manufacturing conditions for Examples 1-9 and Comparative Examples 1-4 are shown in Tables 2 and 3. Here, the dropping rate of the reducing agent is the amount of reducing agent dropped per 1 mole of copper in the copper raw material compound. The cumulative frequency particle sizes D10, D50, D90, and ratio [D90 / D10] and mass ratio [dispersant / (copper particles + dispersant)] of the obtained composite fine particles 1-9 and C1-C4 are also summarized in Tables 2 and 3.

[0092] [Manufacturing of composite microparticle dispersions] 5.0 parts by mass of polyethylene glycol 200, 5.0 parts by mass of dipropylene glycol, and 90 parts by mass of the dried powder of each composite fine particle obtained in the above examples and comparative examples were added to an agate mortar and kneaded until the dried powder was no longer visible, and the resulting mixture was transferred to a plastic bottle. The sealed plastic bottle was stirred for 2000 min using a rotation-and-revolution type stirring device (Sinky Co., Ltd., Planetary Vacuum Mixer ARV-310). -1 The mixture was stirred at 2000 revolutions per minute for 5 minutes. Then, it was passed through a three-roll mill (manufactured by AIMEX Co., Ltd., BV 100) with a roll gap adjusted to 0.2 mm three times to obtain composite microparticle dispersions 1-9 and C1-C4 containing the composite microparticles obtained in the above examples and comparative examples.

[0093] [Manufacturing and evaluation of sintered bodies] Using the obtained composite fine particle dispersions 1-9 and C1-C4, sintered bodies 1-9 and C1-C4 were manufactured according to the following method. A stainless steel metal mask (thickness: 50 μm) with a 7.6 mm x 7.6 mm square opening was placed on a glass slide, and a composite microparticle dispersion was applied to the glass slide using stencil printing with a metal squeegee. Then, the glass slide coated with the composite microparticle dispersion was placed on a hot plate heated to 200°C, covered with a two-port separable cover, and nitrogen was circulated through one port to start firing. After firing for 1 hour, the coating (sintered body) was observed with a digital microscope (Keyence, VHX-8000) to check for the presence or absence of cracks. The cracks were observed throughout the entire coating (sintered body), and the number of cracks in the sintered body was measured.

[0094] [Manufacturing and evaluation of joints] Using the obtained composite fine particle dispersions 1-9 and C1-C4, bonded bodies 1-9 and C1-C4 having a copper bonding layer were manufactured according to the following method. A stainless steel metal mask (thickness: 50 μm) with a 7.6 mm x 7.6 mm square opening was placed on a solid copper plate, and a composite microparticle dispersion was applied to the solid copper plate by stencil printing using a metal squeegee. The solid copper plate coated with the composite microparticle dispersion was then heated at 120°C for 10 minutes, and then 5 mm x 5 mm Si chips were placed on the coated composite microparticle dispersion. These were then fired at 300°C for 5 minutes under pressure of 20 MPa. The bonded body, including the copper bonding layer which is a sintered body of composite microparticles contained in the composite microparticle dispersion, was observed using SAT (ultrasonic testing) to check for the presence or absence of cracks. The cracks were observed throughout the copper joint layer, and the number of cracks in the joint was measured.

[0095] Tables 2 and 3 show details of the composite fine particles obtained in Examples 1-9 and Comparative Examples 1-4, the number of cracks in the sintered body, and the number of cracks in the bonded body.

[0096] [Table 2]

[0097] [Table 3]

[0098] • Cupric oxide (manufactured by Nisshin Chemco Co., Ltd., N-120) • Copper(II) sulfate pentahydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) • Hydrazine monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) Ethanol (95%) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., first-grade reagent): (boiling point 78°C, SP value 12.7, viscosity 1.1 mPa·s) • Ion-exchanged water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., purified water): (boiling point 100℃, SP value 23.4, viscosity 1.0 mPa·s)

[0099] Tables 2 and 3 show that the composite microparticles of Examples 1 to 9 suppress the occurrence of cracks in the sintered bodies and joined bodies obtained by sintering, compared to the composite microparticles of Comparative Examples 1 to 4. In other words, the composite microparticles of the present invention can be used to obtain sintered bodies and joined bodies with good heat resistance. This is thought to be because the composite microparticles have a specific average particle diameter D50, satisfy the relationship D90 / D10 ≤ 4.0, and the copper microparticles are coated with a specific dispersant, which suppresses aggregation of the composite microparticles and ensures good dispersion. Furthermore, because the particle diameter and surface energy of each composite microparticle are similar, sintering proceeds uniformly. [Industrial applicability]

[0100] According to the present invention, it is possible to provide composite microparticles and composite microparticle dispersions that enable low-pressure, low-temperature sintering, form a dense sintered body, and suppress the occurrence of cracks and fractures in the resulting sintered body. Furthermore, it is possible to provide a wiring pattern that is a sintered body of the composite microparticles, and a bonded body having a copper bonding layer.

Claims

1. Composite microparticles in which at least a portion of the surface of copper microparticles is coated with a dispersant, The average particle size D50 of the composite fine particles is 50 nm or more and 350 nm or less. In the particle size histogram based on the number of composite fine particles, the particle size D10 when the cumulative frequency is 10% and the particle size D90 when the cumulative frequency is 90% satisfy the relationship D90 / D10 ≤ 4.

0. The aforementioned dispersant is a vinyl polymer having a carboxyl group and a structure represented by the following formula (1), wherein the composite fine particles. 【Chemistry 1】 In the above formula (1), R 1 R is a hydrogen atom or a methyl group. 2 is an organic group containing a cyclic structure or an organic group containing a chain structure having three or more carbon atoms in a straight chain, and n is a number between 1 and 1000.

2. The R of the vinyl polymer 2 The composite fine particles according to claim 1, wherein the sum of the atomic weights of the constituent atoms is 5000 or less.

3. The composite fine particles according to claim 1, wherein the vinyl polymer is a polymer of a monomer having a carboxyl group and a monomer represented by the following formula (2). 【Chemistry 2】 In the above formula (2), R 1 and R 2 This is the same organic group as the one in formula (1) above.

4. The R of the vinyl polymer 2 The composite fine particles according to claim 1, wherein the organic group includes an alkylene oxide structure or a cyclic structure.

5. The composite fine particles according to claim 1, wherein the acid value of the vinyl polymer is 10 mg KOH / g or more and 250 mg KOH / g or less.

6. The composite fine particles according to claim 1, wherein the vinyl polymer comprises a constituent unit derived from a monomer (p-1) having a carboxyl group and a constituent unit derived from a monomer (p-2) having a (poly)alkylene glycol segment.

7. The composite fine particles according to claim 6, wherein the content of constituent units derived from the monomer (p-2) having the (poly)alkylene glycol segment in the vinyl polymer is 55% by mass or more and 97% by mass or less.

8. The composite fine particles according to claim 1, wherein the weight-average molecular weight of the vinyl polymer is 3,000 or more and 50,000 or less.

9. The composite fine particles according to claim 1, wherein the particle size D10 of the composite fine particles is 105 nm or less.

10. A method for producing composite fine particles in which at least a portion of the surface of copper fine particles is coated with a dispersant, The process includes adding a reducing agent dropwise to a mixture containing a copper raw material compound, a dispersant, and a solvent with an SP value of 8 to 18. The dispersant is a vinyl polymer having a carboxyl group and containing a structure represented by the following formula (1): A method for producing composite fine particles, wherein the dropping rate of the reducing agent relative to 1 mol of copper in the copper raw material compound is 0.01 mol / min or more. 【Transformation 3】 In the above formula (1), R 1 R is a hydrogen atom or a methyl group. 2 is an organic group containing a cyclic structure or an organic group containing a chain structure having three or more carbon atoms in a straight chain, and n is a number between 1 and 1000.

11. The sum of the atomic weights of the atoms constituting the R of the vinyl polymer 2 is 5000 or less, The method for producing composite fine particles according to claim 10.

12. The method for producing composite fine particles according to claim 10, wherein the vinyl polymer is a polymer of a monomer having a carboxyl group and a monomer represented by the following formula (2). 【Chemistry 4】 In the above formula (2), R 1 and R 2 This is the same organic group as the one in formula (1) above.

13. The R of the vinyl polymer 2 A method for producing composite fine particles according to claim 10, wherein the composite fine particles have an organic group containing an alkylene oxide structure or a cyclic structure.

14. The method for producing composite fine particles according to claim 10, wherein the solvent is one or more selected from methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol.

15. The method for producing composite fine particles according to claim 10, wherein the dropping rate of the reducing agent is 2.00 mol / min or less.

16. The method for producing composite fine particles according to claim 10, wherein the copper raw material compound is cupric oxide and the reducing agent is a hydrazine-based compound.

17. The method for producing composite fine particles according to claim 10, wherein the reaction temperature of the reaction solution containing the mixture and the reducing agent added dropwise to the mixture is 5°C or higher and 75°C or lower.

18. A composite particle dispersion comprising composite particles according to any one of claims 1 to 9.

19. A copper bonding layer which is a sintered body of composite fine particles according to any one of claims 1 to 9.

20. A wiring pattern which is a sintered body of composite fine particles according to any one of claims 1 to 9.

21. It is a joint in which metal members are joined together via a copper bonding layer. A bonded body wherein the copper bonding layer is a sintered body of composite fine particles according to any one of claims 1 to 9.

22. This is a method for manufacturing a joined body in which metal members are joined together via a copper bonding layer. The composite fine particle dispersion described in claim 18 is applied to one of the metal members. A method for manufacturing a bonded body, comprising placing a composite fine particle dispersion applied to one of the metal substrates, placing the other metal member on top of it, and then pressurizing and firing them.

23. The composite fine particle dispersion according to claim 18 is used as a bonding material for joining metal members together.

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