Copper sintered compact

Abstract

To provide a copper sintered compact with a low elastic modulus and its manufacturing method.SOLUTION: [1] A copper sintered compact has a tensile elastic modulus of 35 GPa or less. [2] A method for manufacturing a copper sintered compact comprises a step of burning a dispersion D containing copper nanoparticles A and the following polymer B at a burning temperature of 240°C or more and 300°C or less while applying a pressure of 0.1 MPa or more and 40 MPa or less. The polymer B: A polymer comprising constitutional units derived from a monomer (b-1) having carboxyl groups, and constitutional units derived from a monomer (b-2) having polyalkylene glycol segments. [3] A copper sintered compact is obtained by the manufacturing method described in [2]. [4] A conjugate comprises a first member, a second member, and a copper sintered compact described in [1] or [3] for bonding the first member and the second member. [5] A method for manufacturing a conjugate comprising a first member, a second member, and a copper sintered compact joining the first member and second member comprises: a step of applying a dispersion D containing copper nanoparticles A and the following polymer B between the first member and the second member; and a step of burning the dispersion D at a burning temperature of 240°C or more but not exceeding 300°C while applying a pressure of 0.1 MPa or more but not exceeding 40 MPa.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a copper sintered body and a method for producing the same. [Background technology]

[0002] Copper has excellent electrical and thermal conductivity, and is therefore widely used, for example, as a conductor wiring material, a heat transfer material, a heat exchange material, a heat dissipation material, etc. Because copper has excellent thermal conductivity, it is sometimes used as an alternative material to solder for joining objects to be joined.

[0003] In recent years, semiconductor devices known as power devices have become increasingly popular as power conversion and control devices for inverters and other devices. Unlike integrated circuits such as memories and microprocessors, power devices are designed to control high currents and generate a large amount of heat during operation. Therefore, the solder used to mount power devices requires not only high bonding strength but also heat resistance. However, lead-free solder, which is widely used these days, has the disadvantage of low heat resistance. Therefore, various techniques have been proposed to bond objects by using a metal particle dispersion, in which metal particles are dispersed, instead of solder. This dispersion is applied to the object by various coating methods and then baked. The metal species of the metal particle dispersion used for mounting is mainly silver or copper. On the other hand, when a silver sintered body formed from a silver particle dispersion is exposed to high temperatures of 200°C or higher, the voids in the bonding layer repeatedly coalesce and expand, causing the voids to become coarse and eventually break.In contrast, the copper bonding layer formed from a copper particle dispersion does not coalesce or expand, even when exposed to high temperatures of 200°C or higher, and due to its high thermal stability, it is expected to be a next-generation bonding material.

[0004] Non-Patent Document 1 describes that a power cycle test was conducted on a 74 GPa highly elastic copper sintered body formed between semiconductor chips using a copper particle sintered body, in which a current was applied to the semiconductor element and heating and cooling were repeated, and the results showed that the copper sintered body exhibited a cycle life that could withstand more power cycles than silver bonding materials. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] H. Nakako, M. Natori, D. Ishikawa, T. Tanaka and Y. Ejiri, “Copper Sintering Pastes for Die Bonding,” PCIM Europe digital days 2021; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Online, 2021, pp.1-6. Summary of the Invention [Problem to be solved by the invention]

[0006] Although copper sintered bodies formed with copper bonding materials have higher heat resistance than solder, there is still room for improvement in terms of the stress they exert on the bonded objects. Generally, semiconductor elements and substrates bonded with copper sintered bodies experience large stresses at their interfaces due to temperature cycles due to the difference in the linear expansion coefficients of each material. In this case, if the copper sintered body has a high elastic modulus, it is difficult for it to deform in response to strain, resulting in greater stress on the bonded components, the semiconductor chip and substrate. Silicon, which is used in semiconductor chips, is particularly susceptible to chip cracking due to the large difference in linear expansion coefficient between it and copper, making it difficult to use it for mounting power devices. The copper sintered body described in Non-Patent Document 1 experienced chip cracking after a power cycle test. It is believed that this was due to the fact that the copper sintered body was joined to a copper sintered body with a high elastic modulus of 74 GPa. Therefore, further improvement by lowering the elastic modulus of the copper sintered body is required.

[0007] The present invention relates to a copper sintered body having a low elastic modulus and a method for producing the same. [Means for solving the problem]

[0008] The present invention relates to the following [1] to [5]. [1] A sintered copper body with a tensile modulus of elasticity of 35 GPa or less. [2] A method for producing a copper sintered body, comprising the following step 1: Step 1: A step of baking a dispersion D of copper nanoparticles A and the following polymer B at a baking temperature of 240°C or higher and 300°C or lower while applying a pressure of 0.1 MPa or higher and 40 MPa or lower. Polymer B: A polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyalkylene glycol segment. [3] A copper sintered body obtained by the manufacturing method described in [2]. [4] A joined body comprising a first member, a second member, and the copper sintered body according to [1] or [3] that joins the first member and the second member. [5] A method for manufacturing a joined body including a first member, a second member, and a copper sintered body that joins the first member and the second member, the method comprising the following steps 0-1 and 1: Step 0-1: A step of applying a dispersion D containing copper nanoparticles A and the following polymer B between the first member and the second member. Step 1: A step of baking the dispersion D at a baking temperature of 240°C or more and 300°C or less while applying a pressure of 0.1 MPa or more and 40 MPa or less. [Effects of the Invention]

[0009] The present invention provides a copper sintered body having a low elastic modulus and a method for producing the same. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Sintered copper] The copper sintered body of the present invention has a tensile modulus of elasticity of 35 GPa or less. The copper sintered body of the present invention has a low tensile modulus of elasticity, and therefore, even when subjected to rigorous thermal testing in a state where a semiconductor chip and a substrate are bonded together, no chip cracking occurs, and there is little breakage of the sintered body or peeling between the semiconductor chip and the substrate. This copper sintered body has excellent physical properties.

[0011] In this specification, the "tensile modulus" is a value determined from the slope of the region of a stress-strain curve where the stress and strain are proportional to each other. The "tensile modulus" is also sometimes called the "Young's modulus." A "stress-strain curve" is a plot of the stress generated when a tensile test is performed using a thermomechanical analyzer (TMA) and the strain obtained by dividing the initial tensile length by the deformed length. The tensile modulus can be measured, for example, according to the method described in the Examples below.

[0012] A "copper sintered body" is a structure made of copper and having a pore structure (porous structure). It can usually be formed by firing a dispersion such as a paste containing copper particles.

[0013] The copper sintered body of the present invention has a tensile modulus of elasticity of 35 GPa or less, and from the viewpoint of reducing the tensile modulus of elasticity and thereby preventing chip cracking during temperature cycling, the tensile modulus is preferably 30 GPa or less, more preferably 25 GPa or less.

[0014] The tensile strength of the copper sintered body of the present invention is preferably 100 GPa or more, more preferably 120 GPa or more, even more preferably 140 GPa or more, even more preferably 160 GPa or more, and even more preferably 180 GPa or more, from the viewpoint of reducing the peeling rate after temperature cycling. The "tensile strength" is a value determined from the maximum stress value of a stress-strain curve obtained in a tensile test. The tensile strength can be measured, for example, according to the method described in the Examples below.

[0015] Furthermore, the porosity of the copper sintered body of the present invention is preferably 1% or more, more preferably 3% or more, and even more preferably 5% or more, from the viewpoint of preventing chip cracking during temperature cycling due to a decrease in elastic modulus, and is preferably 25% or less, more preferably 20% or less, even more preferably 15% or less, and even more preferably 10% or less, from the viewpoint of improving tensile strength and thereby reducing the peeling rate after temperature cycling. "Porosity" refers to the percentage of pores in the total volume of the copper sintered body (%). The porosity can be measured, for example, by the method described in the Examples below. Specifically, the porosity can be determined by calculating the ratio of the area of ​​pores to the area of ​​the entire cross section in a scanning electron microscope (SEM) image of the cross section of the copper sintered body.

[0016] [zygote] The copper sintered body of the present invention can be used to join a plurality of members, for example, metal members, to obtain a joined body by joining a plurality of members. The present invention also provides a bonded body. A specific embodiment of the bonded body of the present invention is a bonded body comprising a first member, a second member, and the copper sintered body of the present invention bonding the first member and the second member. More specifically, the bonded body is a semiconductor device, and is a semiconductor device comprising a first member, a second member, and the copper sintered body of the present invention bonding the first member and the second member.

[0017] Examples of the metal members to be joined include metal-based 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; metal parts such as electrodes of electrically insulating substrates; etc. The multiple metal members used in the present invention may be metal members of the same type or different types. Among these, the metal member preferably includes at least one selected from a gold substrate, a gold-plated substrate, a silver substrate, a silver-plated metal substrate, a copper substrate, a palladium substrate, a palladium-plated metal substrate, a platinum substrate, a platinum-plated metal substrate, an aluminum substrate, a nickel substrate, a nickel-plated metal substrate, a tin substrate, a tin-plated metal substrate, and a metal portion of an electrically insulating substrate.

[0018] The copper sintered body of the present invention can be used for bonding in various semiconductor devices, for example, bonding chip components such as capacitors and resistors to circuit boards; bonding semiconductor chips such as memories, diodes, transistors, ICs, and CPUs to lead frames or circuit boards; bonding high-heat-generating semiconductor chips to cooling plates, etc. That is, a bonded body in which multiple members are bonded using the copper sintered body of the present invention is preferably a semiconductor device. A preferred embodiment of the bonded body of the present invention is a bonded body comprising a semiconductor chip, a substrate, and the copper sintered body of the present invention bonding the semiconductor chip and the substrate together. Such a bonded body is preferably a semiconductor device, more preferably a power device.

[0019] The semiconductor chip preferably includes a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, a diamond semiconductor chip, and the like. The substrate is preferably a copper substrate.

[0020] The copper sintered body of the present invention can be produced by the method for producing a copper sintered body described in detail below. The copper sintered body of the present invention is preferably a copper sintered body obtained by the production method described in the section "Production method of a copper sintered body" below.

[0021] [Method of manufacturing sintered copper body] The method for producing a copper sintered body of the present invention includes the following step 1. Step 1: A step of baking a dispersion D containing copper nanoparticles A and the following polymer B at a baking temperature of 240°C or higher and 300°C or lower while applying a pressure of 0.1 MPa or higher and 40 MPa or lower. Polymer B: A polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyalkylene glycol segment.

[0022] According to the method for manufacturing a copper sintered body of the present invention, it is possible to obtain a bonded body that has a predetermined low tensile modulus, exhibits a small peeling rate even after temperature cycling, and is capable of suppressing cracking of the semiconductor chip. The reasons for this are not clear, but are thought to be partly as follows. Since the copper nanoparticles A contained in the dispersion D according to the manufacturing method of the present invention have high dispersibility, they are uniformly distributed in the dispersion, and it is believed that sintering proceeds uniformly. As a result, the obtained sintered body is dense, but pores are uniformly present within the structure, which is thought to result in a copper sintered body with a low elastic modulus. Furthermore, by heating at a predetermined temperature, pressure or firing time, the degree of density is adjusted and the number of pores is not reduced too much, which is thought to suppress an increase in the elastic modulus.

[0023] <<Copper nanoparticles A>> Dispersion D to be fired in the method for producing a copper sintered body according to the present invention contains copper nanoparticles A. The copper content in the copper nanoparticles A 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 electrical conductivity, low-temperature sinterability, and low-temperature bondability. Here, "substantially 100% by mass" means that the material may contain unintentionally contained components, such as unavoidable impurities.

[0024] The average particle size of the copper nanoparticles A is preferably 50 nm or more, more preferably 75 nm or more, even more preferably 100 nm or more, and even more preferably 125 nm or more from the viewpoint of suppressing oxidation of the copper nanoparticles, and is preferably 400 nm or less, more preferably 375 nm or less, even more preferably 350 nm or less, and even more preferably 320 nm or less from the viewpoint of improving sinterability to improve tensile strength and thereby reducing the peeling rate after temperature cycling. The average particle size of the copper nanoparticles A is measured by the method described in the examples. The average particle size of the copper nanoparticles A can be adjusted by the production conditions of the copper nanoparticles A, such as the reduced metal rate, the type and amount of the polymer B, and the reduction temperature.

[0025] The content of copper nanoparticles A in dispersion D used in the present invention is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and even more preferably 35% by mass or more, from the viewpoint of improving sinterability and thereby improving tensile strength, and is preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 91% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of improving the dispersion stability of the copper nanoparticle dispersion, which suppresses shrinkage of the bonding layer after sintering and thereby reduces the peeling rate after temperature cycling.

[0026] <<Copper Microparticles A'>> Dispersion D used in the present invention may further contain copper microparticles A' from the viewpoint of improving electrical conductivity, low-temperature sinterability, and low-temperature bondability. The copper content in the copper microparticles A' 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 electrical conductivity, low-temperature sinterability, and low-temperature bondability. Here, "substantially 100% by mass" means that the material may contain unintentionally contained components, such as unavoidable impurities.

[0027] The average particle size of the copper microparticles A' is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.5 μm or more, and even more preferably 2.0 μm or more, from the viewpoint of suppressing shrinkage of the bonding layer after sintering and thereby reducing the peeling rate after temperature cycling, and is preferably 6 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less, from the viewpoint of improving the tensile strength by improving the surface energy and sinterability, thereby reducing the peeling rate after temperature cycling. The average particle size of the copper microparticles A' is measured by the method described in the Examples.

[0028] The content of copper microparticles A' in dispersion D used in the present invention is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of suppressing shrinkage of the bonding layer after sintering and thereby reducing the peeling rate after temperature cycling, and is preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less, from the viewpoint of suppressing deterioration of sinterability due to a decrease in surface energy and maintaining tensile strength.

[0029] The mass ratio of the content of copper nanoparticles A to the total content of copper nanoparticles A and copper microparticles A' in dispersion D used in the present invention [copper nanoparticles A / (copper nanoparticles A+copper microparticles A')] is preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and even more preferably 0.6 or more, from the viewpoint of improving electrical conductivity, storage stability of the copper microparticle dispersion, low-temperature sinterability, and low-temperature bondability; and is preferably 1.0 or less, more preferably 0.9 or less, even more preferably 0.8 or less, and even more preferably 0.75 or less, from the viewpoint of improving electrical conductivity, low-temperature sinterability, and low-temperature bondability.

[0030] <<Polymer B>> Dispersion D used in the present invention contains polymer B from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving low-temperature sinterability and low-temperature bonding properties. Preferably, dispersion D comprises copper nanoparticles A coated with polymer B. Polymer B contains a constituent unit derived from a monomer (b-1) having a carboxy group and a constituent unit derived from a monomer (b-2) having a polyalkylene glycol segment, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving low-temperature sintering properties and low-temperature bonding properties.

[0031] <Monomer (b-1) having a carboxy group> Examples of the monomer (b-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 acids may be anhydrides. The monomer (b-1) may be used alone or in combination of two or more kinds. From the viewpoint of improving the dispersion stability of the copper nanoparticles A in the dispersion D and improving the low-temperature sintering property and the low-temperature bonding property, the monomer (b-1) is preferably at least one selected from (meth)acrylic acid and maleic acid, more preferably (meth)acrylic acid, and even more preferably methacrylic acid. In this specification, "(meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth)acrylic acid" below.

[0032] <Monomer (b-2) Having a Polyalkylene Glycol Segment> Examples of the monomer (b-2) include polyalkylene glycol (meth)acrylate, alkoxy polyalkylene glycol (meth)acrylate, phenoxy polyalkylene glycol (meth)acrylate, etc. The monomer (b-2) may be used alone or in combination of two or more. In this specification, "(meth)acrylate" refers to at least one selected from acrylate and methacrylate. The "(meth)acrylate" used below has the same meaning.

[0033] Monomer (b-2) is preferably at least one selected from polyalkylene glycol (meth)acrylates and alkoxy polyalkylene glycol (meth)acrylates, more preferably alkoxy polyalkylene glycol (meth)acrylates, from the viewpoint of improving the dispersibility of copper nanoparticles A in dispersion D and improving low-temperature sintering and bonding properties. From the same viewpoints as above, the number of carbon atoms in the alkoxy group of the alkoxy polyalkylene glycol (meth)acrylate is preferably 1 to 18, more preferably 1 to 14, and even more preferably 1 to 12. Examples of the alkoxy polyalkylene glycol (meth)acrylate include methoxy polyalkylene glycol (meth)acrylate, ethoxy polyalkylene glycol (meth)acrylate, propoxy polyalkylene glycol (meth)acrylate, butoxy polyalkylene glycol (meth)acrylate, octoxy polyalkylene glycol (meth)acrylate, and lauroxy polyalkylene glycol (meth)acrylate.

[0034] The polyalkylene glycol segment of monomer (b-2) preferably contains a unit derived from an alkylene oxide having from 2 to 4 carbon atoms, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving low-temperature sintering and bonding properties. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide, and are preferably at least one selected from ethylene oxide and propylene oxide, and more preferably ethylene oxide. The number of alkylene oxide-derived units in the polyalkylene glycol segment is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more, from the viewpoint of improving the dispersion stability of the copper nanoparticles A in the dispersion D and improving low-temperature sintering properties and low-temperature bonding properties, and is 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. The polyalkylene glycol segment may be a copolymer containing units derived from ethylene oxide and units derived from propylene oxide, from the viewpoint of improving the dispersion stability of the copper microparticle dispersion and improving low-temperature sintering properties and low-temperature bonding properties. The copolymer containing units derived from ethylene oxide and units derived from propylene oxide may be any of a block copolymer, a random copolymer, and an alternating copolymer.

[0035] Specific examples of commercially available monomer (b-2) include NK Ester AM-90G, AM-130G, AM-230G, AMP-20GY, M-20G, M-40G, M-90G, and M-230G manufactured by Shin-Nakamura Chemical Co., Ltd.; and Blenmar PE-90, PE-200, PE-350, PME-100, and PME-230G 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.

[0036] <Hydrophobic Monomer (b-3)> From the viewpoint of improving low-temperature sintering properties and low-temperature bonding properties, polymer B may further contain a structural unit derived from a hydrophobic monomer (b-3). In this specification, the term "hydrophobic monomer" refers to a monomer whose dissolution amount is less than 10 g when the monomer is dissolved to saturation in 100 g of ion-exchanged water at 25° C. From the viewpoint of improving low-temperature sinterability and low-temperature bondability, the dissolution amount of the monomer (b-3) is preferably 5 g or less, more preferably 1 g or less. The monomer (b-3) is preferably at least one selected from aromatic group-containing monomers and (meth)acrylates having a hydrocarbon group derived from an aliphatic alcohol.

[0037] From the viewpoint of improving low-temperature sintering properties and low-temperature bonding properties, the aromatic group-containing monomer is preferably a vinyl monomer having an aromatic group of 6 to 22 carbon atoms, which may have a substituent containing a hetero atom, and more preferably one or more selected from a styrene-based monomer and an aromatic group-containing (meth)acrylate. The molecular weight of the aromatic group-containing monomer is preferably less than 500. Examples of styrene-based monomers include styrene, α-methylstyrene, 2-methylstyrene, 4-vinyltoluene (4-methylstyrene), and divinylbenzene. From the viewpoint of improving low-temperature sintering properties and low-temperature bonding properties, styrene and α-methylstyrene are preferred. As the aromatic group-containing (meth)acrylate, from the viewpoint of improving low-temperature sintering properties and low-temperature bonding properties, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, etc. are preferred, and benzyl (meth)acrylate is more preferred.

[0038] From the viewpoint of improving low-temperature sinterability and low-temperature bondability, the (meth)acrylate having a hydrocarbon group derived from an aliphatic alcohol preferably has a hydrocarbon group derived from an aliphatic alcohol having from 1 to 22 carbon atoms, more preferably has a hydrocarbon group derived from an aliphatic alcohol having from 1 to 12 carbon atoms, even more preferably has a hydrocarbon group derived from an aliphatic alcohol having from 1 to 8 carbon atoms, and even more preferably has a hydrocarbon group derived from an aliphatic alcohol having from 1 to 4 carbon atoms. Examples of the (meth)acrylate include a (meth)acrylate having a linear alkyl group, a (meth)acrylate having a branched alkyl group, and a (meth)acrylate having an alicyclic alkyl group. 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 a branched alkyl group 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. Examples of (meth)acrylates having an alicyclic alkyl group include cyclohexyl (meth)acrylate. The monomer (b-3) may be used alone or in combination of two or more.

[0039] From the viewpoint of improving low-temperature sinterability and low-temperature bondability, the monomer (b-3) is preferably at least one selected from an aromatic group-containing monomer and a (meth)acrylate having a linear alkyl group, more preferably at least one selected from a styrene-based monomer and a (meth)acrylate having a linear alkyl group having from 1 to 4 carbon atoms, even more preferably at least one selected from styrene, α-methylstyrene, 2-methylstyrene, 4-vinyltoluene (4-methylstyrene), methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate, even more preferably at least one selected from styrene, α-methylstyrene, and methyl (meth)acrylate, and even more preferably at least one selected from styrene and methyl (meth)acrylate.

[0040] From the viewpoint of improving the dispersion stability of the copper nanoparticles A in the dispersion D and improving the low-temperature sintering property and low-temperature bonding property, the polymer B is preferably a vinyl polymer containing, as the monomer (b-1), a structural unit derived from at least one selected from (meth)acrylic acid and maleic acid, and, as the monomer (b-2), a structural unit derived from an alkoxypolyalkylene glycol (meth)acrylate. The vinyl polymer containing, as the monomer (b-1), a structural unit derived from at least one selected from (meth)acrylic acid and maleic acid, and, as the monomer (b-2), a structural unit derived from an alkoxypolyalkylene glycol (meth)acrylate, may be any of a block copolymer, a random copolymer, and an alternating copolymer.

[0041] The content of the vinyl polymer containing the structural unit derived from the monomer (b-1) and the structural unit derived from the monomer (b-2) in the polymer B is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably substantially 100% by mass, from the viewpoint of improving the dispersion stability of the copper nanoparticles A in the dispersion D and improving low-temperature sintering properties and low-temperature bonding properties. Here, "substantially 100% by mass" means that unintentionally contained components may be included. Examples of unintentionally contained components include polymers B other than the vinyl polymers contained in the polymer B.

[0042] During the production of polymer B, the total content of monomer (b-1) and monomer (b-2) in the raw material monomers, or the total content of the structural units derived from monomer (b-1) and monomer (b-2) in polymer B, is preferably 72% by mass or more, more preferably 88% by mass or more, even more preferably 91% by mass or more, even more preferably 97% by mass or more, and even more preferably substantially 100% by mass, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving low-temperature sintering and low-temperature bonding. Here, "substantially 100% by mass" means that unintentionally contained components may be included. Examples of unintentionally contained components include monomers other than monomer (b-1) and monomer (b-2) contained in the raw material monomer (b-1) and monomer (b-2).

[0043] In producing polymer B, the content of monomer (b-1) in the raw material monomers or the content of structural units derived from monomer (b-1) in polymer B is preferably 3% by mass or more, more preferably 5% by mass or more, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving low-temperature sinterability and low-temperature bondability, and is preferably 35% by mass or less, more preferably 25% by mass or more, even more preferably 18% by mass or less, and even more preferably 10% by mass or less.

[0044] During the production of polymer B, the content of monomer (b-2) in the raw material monomers or the content of structural units derived from monomer (b-2) in polymer B is preferably 55% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 84% by mass or more, even more preferably 90% by mass or more, from the viewpoint of improving the dispersion stability of the copper microparticle dispersion and improving low-temperature sintering properties and low-temperature bonding properties, and is preferably 97% by mass or less, more preferably 95% by mass or less.

[0045] The content of polyalkylene glycol segments in polymer B is preferably 55% by mass or more and 97% by mass or less, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 84% by mass or more, from the viewpoint of improving low-temperature sintering properties and low-temperature bonding properties, and is more preferably 94% by mass or less, and even more preferably 92% by mass or less, from the viewpoint of improving the dispersion stability of the copper microparticle dispersion and improving the storage stability of the copper microparticle dispersion.

[0046] The number average molecular weight Mn of polymer B is preferably 4,000 or more, more preferably 6,000 or more, and even more preferably 7,000 or more from the viewpoint of improving the dispersion stability of the copper microparticle dispersion and improving the storage stability of the copper microparticle dispersion, and is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 10,000 or less from the viewpoint of improving the dispersion stability and low-temperature bonding of the copper microparticle dispersion. The number average molecular weight Mn is measured by the method described in the Examples.

[0047] The acid value of polymer B is preferably 20 mgKOH / g or more and 250 mgKOH / g or less, and from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving the storage stability of dispersion D, it is more preferably 25 mgKOH / g or more, even more preferably 30 mgKOH / g or more, even more preferably 35 mgKOH / g or more, even more preferably 40 mgKOH / g or more, and from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving the storage stability of dispersion D, it is more preferably 230 mgKOH / g or less, even more preferably 220 mgKOH / g or less, even more preferably 215 mgKOH / g or less. The acid value of Polymer B can be measured by the method described in the Examples, or can be calculated from the mass ratio of the constituent monomers.

[0048] The content of polymer B in dispersion D used in the present invention is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving the storage stability of dispersion D, and is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, and even more preferably 7% by mass or less, from the viewpoint of improving low-temperature sinterability and low-temperature bondability.

[0049] The mass ratio of the content of polymer B to the total content of copper nanoparticles A and polymer B in dispersion D used in the present invention [polymer B / (copper nanoparticles A+polymer B)] (hereinafter also referred to as "polymer mass ratio") is preferably 0.0055 or more, more preferably 0.0058 or more, and even more preferably 0.0060 or more, from the viewpoint of improving the dispersion stability of copper nanoparticles A in dispersion D and improving the storage stability of dispersion D, and is preferably 0.025 or less, more preferably 0.022 or less, even more preferably 0.020 or less, and even more preferably 0.018 or less, from the viewpoint of improving low-temperature sinterability and low-temperature bondability. The polymer mass ratio is calculated from the content of copper nanoparticles A and the content of polymer B in dispersion D measured by the method described in the examples using a thermogravimetric / differential thermal analyzer (TG / DTA).

[0050] <<Dispersion medium C>> The dispersion D used in the present invention preferably further contains a dispersion medium C. The dispersion medium C is a medium for dispersing the copper nanoparticles A and, if necessary, the copper microparticles A′ in the dispersion D. Preferred examples of the dispersion medium C include one or more organic solvents selected from the group consisting of hydrocarbons, alcohols, ethers, and esters. The organic solvents may be used singly or in combination of two or more. The organic solvent is preferably at least one selected from the group consisting of alcohols, ethers, and esters, and more preferably at least one selected from the group consisting of aliphatic monohydric alcohols, (poly)alkylene glycols, and (poly)alkylene glycol derivatives.

[0051] 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. Among these, terpene alcohols are preferred as aliphatic monohydric alcohols. Preferred examples of terpene alcohols include monoterpene alcohols such as α-terpineol, linalool, geraniol, citronellol, and dihydroterpineol.

[0052] The (poly)alkylene glycol is at least one 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 or more and 1000 or less, more preferably 150 or more and 600 or less, and even more preferably 180 or more and 500 or less), dipropylene glycol, tripropylene glycol, polypropylene glycol (number average molecular weight preferably 150 or more and 1000 or less, more preferably 180 or more and 600 or less, and even more preferably 200 or more and 500 or less), and polytetramethylene glycol.

[0053] Examples of the (poly)alkylene glycol derivative include compounds in which the terminal hydroxy groups of the (poly)alkylene glycols 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. The (poly)alkylene glycol alkyl ether is at least one selected from the group consisting of alkylene glycol alkyl ethers and polyalkylene glycol alkyl ethers. Examples of the (poly)alkylene glycol alkyl ether include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol butyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether. The (poly)alkylene glycol monoalkyl ether acetate is at least one member selected from the group consisting of alkylene glycol monoalkyl ether acetates and polyalkylene glycol monoalkyl ether acetates. Examples of the (poly)alkylene glycol monoalkyl ether acetate 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.

[0054] Among these, from the viewpoint of improving the dispersion stability of the copper nanoparticles A in the dispersion D and improving the bonding strength, the dispersion medium C preferably contains one or more compounds selected from the group consisting of hydroxy group-containing compounds having at least one hydroxy group in the molecule (hereinafter also referred to as "hydroxy group-containing compounds") and ester group-containing compounds having at least one ester group in the molecule (hereinafter also referred to as "ester group-containing compounds"), and more preferably contains a hydroxy group-containing compound.

[0055] The hydroxy group-containing compound is preferably at least one selected from the group consisting of (poly)alkylene glycols and (poly)alkylene glycol alkyl ethers, and more preferably a (poly)alkylene glycol. The ester group-containing compound is preferably a (poly)alkylene glycol monoalkyl ether acetate.

[0056] The content of dispersion medium C in dispersion D used in the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of improving the sinterability and tensile strength of dispersion D by improving the dispersibility of copper nanoparticles A and / or copper microparticles A', and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving the sinterability and tensile strength of dispersion D. The mass ratio of the content of dispersion medium C to the content of copper nanoparticles A in dispersion D [dispersion medium C / copper nanoparticles A] is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, from the viewpoint of improving the sinterability and tensile strength of dispersion D, and is preferably 1.0 or less, more preferably 0.5 or less, and even more preferably 0.2 or less, from the viewpoint of suppressing shrinkage of dispersion D during sintering.

[0057] <<Dispersion D>> In the dispersion D used in the present invention, from the viewpoint of improving the dispersibility of the copper nanoparticles A in the dispersion D and the low-temperature sintering and bonding properties of the dispersion D, the content of the copper nanoparticles A is preferably 30% by mass or more and 95% by mass or less, the content of the polymer B is preferably 0.1% by mass or more and 10% by mass or less, the content of the dispersion medium C is preferably 4% by mass or more and 60% by mass or less, and the content of the copper microparticles A' is preferably 0% by mass or more and 65% by mass or less.

[0058] Dispersion D may contain various additives as components other than the above components, provided that the effects of the present invention are not impaired. Examples of such additives include metal particles other than copper nanoparticles A and copper microparticles A', sintering accelerators such as glass frit, antioxidants, viscosity adjusters, pH adjusters, buffers, antifoaming agents, leveling agents, and volatilization inhibitors. Examples of metal particles other than copper nanoparticles A and copper microparticles include zinc, nickel, silver, gold, palladium, platinum, and other metal particles. The content of the additive in Dispersion D is preferably 1% by mass or less.

[0059] <<Method of manufacturing dispersion D>> Dispersion D used in the present invention can be obtained by a method in which polymer B and dispersion medium C, and optionally copper microparticles A' and various additives, are added to copper nanoparticles A prepared in advance by a known method and mixed; or by a method in which a copper source compound, a reducing agent, and polymer B as a dispersant, and optionally a solvent for dispersing the copper source compound and reducing agent are mixed, the copper source compound is reduced to obtain a dispersion of copper nanoparticles A, and then dispersion medium C and optionally copper microparticles and various additives are added and mixed. Among these, from the viewpoint of improving the low-temperature sinterability, low-temperature bondability, and dispersion stability of copper nanoparticles A in dispersion D, a method in which a dried powder of copper nanoparticles A containing polymer B is obtained in advance (hereinafter also referred to as "copper nanoparticle dried powder"), and then dispersion medium C and optionally copper microparticles A' and various additives are added and mixed is preferred. The copper nanoparticle dry powder can be obtained by mixing a copper source compound, a reducing agent, and a polymer B, reducing the copper source compound with the reducing agent to obtain a dispersion of copper nanoparticles A dispersed in the polymer B, and then drying the dispersion of copper nanoparticles A by freeze-drying or the like. In the copper nanoparticle dry powder, preferably, part or all of the surface of the copper nanoparticles A is coated with the polymer B.

[0060] The copper raw material compound is not particularly limited as long as it is a compound containing copper. Examples of copper source compounds include copper sulfate, copper nitrate, cupric oxide, cuprous oxide, copper formate, copper acetate, copper oxalate, etc. The copper source compounds can be used alone or in combination of two or more.

[0061] The reducing agent is not particularly limited as long as it is a compound that can reduce the copper raw material compound. Examples of reducing agents include hydrazine compounds such as hydrazine, hydrazine hydrochloride, hydrazine sulfate, and hydrazine hydrate; boron compounds such as sodium borohydride; and inorganic acid salts such as sodium sulfite, sodium hydrogen sulfite, sodium thiosulfate, sodium nitrite, sodium hyponitrite, phosphorous acid, sodium phosphite, hypophosphorous acid, and sodium hypophosphite. The reducing agent may be used alone or in combination of two or more.

[0062] Examples of the solvent for dispersing the copper source compound and the reducing agent include water, methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol.

[0063] The temperature of the reduction reaction is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, and even more preferably 60 ° C. or higher, from the viewpoint of reducing and uniforming the particle size of the copper nanoparticles A, and is preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and even more preferably 80 ° C. or lower. The reduction reaction may be carried out in an air atmosphere or an inert gas atmosphere such as nitrogen gas.

[0064] In producing the copper nanoparticle dispersion, the dispersion of copper nanoparticles A may be purified before freeze-drying in order to remove impurities such as unreacted reducing agent and excess polymer B that does not contribute to the dispersion of copper nanoparticles A. The method for purifying the dispersion containing copper nanoparticles A is not particularly limited, and examples thereof include membrane treatments such as decantation, dialysis, and ultrafiltration; and centrifugation. Among these, decantation and centrifugation are preferred from the viewpoint of improving yield. Regenerated cellulose is preferred as the material for the dialysis membrane used in dialysis. From the viewpoint of efficiently removing impurities, the molecular weight cutoff of the dialysis membrane is preferably 1,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less.

[0065] Dispersion D can be obtained by further adding the various additives described above as necessary and performing a filtration treatment using a filter or the like.

[0066] <<Firing process>> The method for producing a copper sintered body of the present invention includes a step of firing the above dispersion D at a firing temperature of 240° C. or higher and 300° C. or lower while applying a pressure of 0.1 MPa or higher and 40 MPa or lower.

[0067] The firing temperature, which is the heating temperature in the firing step, is 240°C or higher, preferably 250°C or higher, from the viewpoint of improving sinterability to improve tensile strength and thereby reducing the peeling rate after temperature cycling, and is 300°C or lower, preferably 290°C or lower, more preferably 275°C or lower, from the viewpoint of avoiding damage to components such as semiconductor chips when they are bonded. The firing temperature can be, for example, 200°C or higher and 300°C or lower. It is also preferable to set the firing temperature to 150°C or higher. The firing step is carried out under a pressure of 0.1 MPa to 40 MPa. The pressure to be applied is 0.1 MPa or more, preferably 2 MPa or more, more preferably 4 MPa or more, from the viewpoint of improving sinterability to improve tensile strength and thereby reducing the peeling rate after temperature cycling, and is 40 MPa or less, preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 15 MPa, from the viewpoint of preventing chip cracking during temperature cycling due to a decrease in elastic modulus. The firing time can be adjusted appropriately depending on the heating temperature and the applied pressure. From the viewpoint of improving the sinterability to improve the tensile strength and thereby reducing the peeling rate after temperature cycling, it is preferably 150 seconds or more, more preferably 200 seconds or more, even more preferably 250 seconds or more, and even more preferably 300 seconds or more, and from the viewpoint of preventing chip cracking during temperature cycling due to a decrease in elastic modulus, it is preferably 3600 seconds or less, more preferably 1800 seconds or less, even more preferably 1200 seconds or less, and even more preferably 600 seconds or less.

[0068] The atmosphere in the firing step may be any of an air atmosphere, an inert gas atmosphere such as nitrogen gas, and a reducing gas atmosphere such as hydrogen gas, and from the viewpoints of inhibiting copper oxidation and safety, a nitrogen gas atmosphere is preferred.

[0069] The firing carried out under pressure can be carried out by, for example, the HP (hot press) method, the HIP (hot isostatic pressing) method, the atmospheric pressure method, etc. Preferably, firing is carried out by the HP method. Specifically, for example, it can be performed using a pressure firing machine (pressure sintering machine). Alternatively, a simple method can be used in which a weight capable of applying the pressure is placed on the material and the material is fired using an oven or the like.

[0070] <<Application process>> The method for producing a sintered copper body of the present invention preferably further includes the following step 0 before the step 1. Step 0: Applying the Dispersion D to a Member The member to which dispersion D is applied is preferably a metal member, and examples thereof include metal-based 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. Among these, preferred examples of the metal member include a gold substrate, a gold-plated substrate, a silver substrate, a silver-plated metal substrate, a copper substrate, a palladium substrate, a palladium-plated metal substrate, a platinum substrate, a platinum-plated metal substrate, an aluminum substrate, a nickel substrate, a nickel-plated metal substrate, a tin substrate, a tin-plated metal substrate, and the metal portion of an electrically insulating substrate. Methods for applying Dispersion D to a member include various application methods such as slot die coating, dip coating, spray coating, spin coating, doctor blading, knife edge coating, and bar coating; and various pattern printing methods such as stencil printing, screen printing, flexographic printing, gravure printing, offset printing, dispenser printing, and inkjet printing. The amount of dispersion D to be applied to a member such as a metal member can be adjusted appropriately depending on the size and type of the member such as a metal member to be joined.

[0071] The step 0 is preferably the following step 0-1. Step 0-1: A step of applying the dispersion D between a first member and a second member so that the dispersion D is interposed between the first member and the second member. The first member and the second member may be the same type of member or different types of members. In this case, the resulting copper sintered body joins the first member and the second member.

[0072] Thus, a copper sintered body is produced. The produced copper sintered body preferably has the physical properties described in the above [Copper sintered body] section.

[0073] [Method of manufacturing the bonded body] The method for producing a bonded body of the present invention includes the steps of: A method for manufacturing a bonded body including a first member, a second member, and a copper sintered body that bonds the first member and the second member, includes the following steps 0-1 and 1. Step 0-1: A step of applying a dispersion D containing copper nanoparticles A and the following polymer B between the first member and the second member. Step 1: A step of baking the dispersion D at a baking temperature of 240°C or more and 300°C or less while applying a pressure of 0.1 MPa or more and 40 MPa or less.

[0074] The conjugate to be produced and its preferred embodiments are described in the above [Conjugate] section.

[0075] Dispersion D is the one described in the above section [Method for producing sintered copper body].

[0076] The means for applying the copper dispersion D between the first member and the second member is not particularly limited, and examples thereof include various application methods such as slot die coating, dip coating, spray coating, spin coating, doctor blading, knife edge coating, and bar coating, and various pattern printing methods such as stencil printing, screen printing, flexographic printing, gravure printing, offset printing, dispenser printing, and inkjet printing. The amount of dispersion D applied to the first member and / or the second member can be adjusted appropriately depending on the size and type of the first member and the second member to be joined.

[0077] The step of firing Dispersion D at a firing temperature of 240° C. to 300° C. while applying a pressure of 0.1 MPa to 40 MPa and a preferred embodiment thereof are described in the above section [Method for producing a copper sintered body].

[0078] The bonded body to be produced is preferably a semiconductor, in which case the first member and the second member are preferably a semiconductor chip and a substrate. The semiconductor chip is preferably a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, or a diamond semiconductor chip. The substrate is preferably a copper substrate.

[0079] Thus, a bonded body is produced. The copper sintered body constituting the produced bonded body preferably has the physical properties described in the above [Copper sintered body] section.

[0080] The present invention further provides the following: <1> ~ <80> Disclose. <1> A copper sintered body having a tensile modulus of elasticity of 35 GPa or less, preferably 30 GPa or less, and more preferably 25 GPa or less. <2> The tensile strength is preferably 100 MPa or more, more preferably 120 GPa or more, even more preferably 140 GPa or more, even more preferably 160 GPa or more, and even more preferably 180 GPa or more. <1> The copper sintered body according to claim 1. <3> The porosity is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and is preferably 25% or less, more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less. <1> or <2> The copper sintered body according to claim 1. <4> A method for producing a copper sintered body, comprising the following step 1: Step 1: A step of baking a dispersion D containing copper nanoparticles A and the following polymer B at a baking temperature of 240°C or higher and 300°C or lower while applying a pressure of 0.1 MPa or higher and 40 MPa or lower. Polymer B: A polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyalkylene glycol segment. <5> The copper content in the copper nanoparticles A 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. <4> A method for producing a copper sintered body according to claim 1. <6> The method further includes the following step 0 before step 1: <4> A method for producing a copper sintered body according to claim 1. Step 0: Applying the Dispersion D to a Member <7> The step 0 is a step of applying the dispersion D between a first member and a second member so that the dispersion D is interposed between the first member and the second member. <4> or <5> A method for producing a copper sintered body according to claim 1. <8> The average particle size of the copper nanoparticles A is preferably 50 nm or more, more preferably 75 nm or more, even more preferably 100 nm or more, even more preferably 125 nm or more, and preferably 400 nm or less, more preferably 375 nm or less, even more preferably 350 nm or less, even more preferably 320 nm or less. <4> ~ <6> 1. A method for producing a copper sintered body according to any one of the above. <9> The content of copper nanoparticles A in dispersion D is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 91% by mass or less, even more preferably 90% by mass or less. <4> ~ <8> 1. A method for producing a copper sintered body according to any one of the above. <10> Dispersion D further contains copper microparticles A', and the copper content in the copper microparticles A' 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. <4> ~ <9> 1. A method for producing a copper sintered body according to any one of the above. <11> The average particle size of the copper microparticles A' is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and is preferably 6 μm or less, more preferably 5 μm or less, even more preferably 4 μm or less. <10> A method for producing a copper sintered body according to claim 1. <12> The content of copper microparticles A' in dispersion D is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, even more preferably 50% by mass or less. <10> or <11> A method for producing a copper sintered body according to claim 1. <13> The mass ratio of the content of copper nanoparticles A to the total content of copper nanoparticles A and copper microparticles A' in dispersion D [copper nanoparticles A / (copper nanoparticles A+copper microparticles A')] is preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, even more preferably 0.6 or more, and is preferably 1.0 or less, more preferably 0.9 or less, even more preferably 0.8 or less, even more preferably 0.75 or less. <10> ~ <12> A method for manufacturing sintered copper bodies. <14> The monomer (b-1) is at least one selected from the group consisting of 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. <4> ~ <13> 1. A method for producing a copper sintered body according to any one of the above. <15> The monomer (b-2) is at least one selected from the group consisting of polyalkylene glycol (meth)acrylate, alkoxy polyalkylene glycol (meth)acrylate, and phenoxy polyalkylene glycol (meth)acrylate. <4> ~ <14> 1. A method for producing a copper sintered body according to any one of the above. <16> The monomer (b-2) is preferably at least one selected from the group consisting of polyalkylene glycol (meth)acrylates and alkoxy polyalkylene glycol (meth)acrylates, more preferably an alkoxy polyalkylene glycol (meth)acrylate, and the number of carbon atoms in the alkoxy group of the alkoxy polyalkylene glycol (meth)acrylate is preferably 1 or more and 18 or less, more preferably 1 or more and 14 or less, and even more preferably 1 or more and 12 or less. <15> A method for manufacturing sintered copper. <17> The polyalkylene glycol segment of the monomer (b-2) preferably contains a unit derived from an alkylene oxide having from 2 to 4 carbon atoms. <4> ~ <16> 1. A method for producing a copper sintered body according to any one of the above. <18> the number of alkylene oxide-derived units in the polyalkylene glycol segment of the monomer (b-2) is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and is preferably 100 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, even more preferably 35 or less; <4> ~ <17> 1. A method for producing a copper sintered body according to any one of the above. <19> Polymer B further contains a structural unit derived from a hydrophobic monomer (b-3). <4> ~ <16> 1. A method for producing a copper sintered body according to any one of the above. <20> The monomer (b-3) is preferably at least one selected from an aromatic group-containing monomer and a (meth)acrylate having a hydrocarbon group derived from an aliphatic alcohol. <19> A method for producing a copper sintered body according to claim 1. <21> Polymer B is more preferably a vinyl polymer containing, as monomer (b-1), a structural unit derived from at least one selected from the group consisting of (meth)acrylic acid and maleic acid, and, as monomer (b-2), a structural unit derived from an alkoxypolyalkylene glycol (meth)acrylate. <4> ~ <20> 1. A method for producing a copper sintered body according to any one of the above. <22> the content of the vinyl polymer containing a structural unit derived from the monomer (b-1) and a structural unit derived from the monomer (b-2) in the polymer B is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably substantially 100% by mass; <21> A method for producing a copper sintered body according to claim 1. <23> During the production of polymer B, the total content of monomer (b-1) and monomer (b-2) in the raw material monomers or the total content of structural units derived from monomer (b-1) and structural units derived from monomer (b-2) in polymer B is preferably 72% by mass or more, more preferably 88% by mass or more, even more preferably 91% by mass or more, even more preferably 97% by mass or more, and even more preferably substantially 100% by mass. <4> ~ <22> 1. A method for producing a copper sintered body according to any one of the above. <24> During the production of polymer B, the content of monomer (b-1) in the raw material monomers or the content of structural units derived from monomer (b-1) in polymer B is preferably 3% by mass or more, more preferably 5% by mass or more, and preferably 35% by mass or less, more preferably 25% by mass or more, even more preferably 18% by mass or less, and even more preferably 10% by mass or less. <4> ~ <23> 1. A method for producing a copper sintered body according to any one of the above. <25> During the production of polymer B, the content of monomer (b-2) in the raw material monomers or the content of structural units derived from monomer (b-2) in polymer B is preferably 55% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 84% by mass or more, even more preferably 90% by mass or more, and is preferably 97% by mass or less, more preferably 95% by mass or less. <4> ~ <24> 1. A method for producing a copper sintered body according to any one of the above. <26> The content of polyalkylene glycol segments in polymer B is preferably 55% by mass or more and 97% by mass or less, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 84% by mass or more, and more preferably 94% by mass or less, even more preferably 92% by mass or less. <4> ~ <25> 1. A method for producing a copper sintered body according to any one of the above. <27> The number average molecular weight Mn of polymer B is preferably 4,000 or more, more preferably 6,000 or more, even more preferably 7,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 10,000 or less. <4> ~ <26> 1. A method for producing a copper sintered body according to any one of the above. <28> The acid value of Polymer B is preferably 20 mgKOH / g or more and 250 mgKOH / g or less, more preferably 25 mgKOH / g or more, even more preferably 30 mgKOH / g or more, even more preferably 35 mgKOH / g or more, even more preferably 40 mgKOH / g or more, and more preferably 230 mgKOH / g or less, even more preferably 220 mgKOH / g or less, even more preferably 215 mgKOH / g or less. <4> ~ <27> 1. A method for producing a copper sintered body according to any one of the above. <29> The content of polymer B in dispersion D is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, and is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, even more preferably 7% by mass or less. <4> ~ <28> 1. A method for producing a copper sintered body according to any one of the above. <30> The mass ratio of the content of polymer B to the total content of copper nanoparticles A and polymer B in dispersion D [polymer B / (copper nanoparticles A+polymer B)] is preferably 0.0055 or more, more preferably 0.0058 or more, even more preferably 0.0060 or more, and is preferably 0.025 or less, more preferably 0.022 or less, even more preferably 0.020 or less, even more preferably 0.018 or less, <4> ~ <29> 1. A method for producing a copper sintered body according to any one of the above. <31> Dispersion D further contains a dispersion medium C; <4> ~ <30> 1. A method for producing a copper sintered body according to any one of the above. <32> The dispersion medium C is one or more organic solvents selected from the group consisting of hydrocarbons, alcohols, ethers, and esters; <31> A method for producing a copper sintered body according to claim 1. <33> The content of the dispersion medium C in the dispersion D is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less. <31> or <32> A method for producing a copper sintered body according to claim 1. <34> The mass ratio of the content of dispersion medium C to the content of copper nanoparticles A in dispersion D [dispersion medium C / copper nanoparticles A] is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, and preferably 1.0 or less, more preferably 0.5 or less, even more preferably 0.2 or less. <31> ~ <33> 1. A method for producing a copper sintered body according to any one of the above. <35> In the dispersion D, the content of copper nanoparticles A is preferably 30% by mass or more and 95% by mass or less, the content of polymer B is preferably 0.1% by mass or more and 10% by mass or less, the content of dispersion medium C is preferably 4% by mass or more and 60% by mass or less, and the content of copper microparticles A' is preferably 0% by mass or more and 65% by mass or less, <4> A method for producing a copper sintered body according to claim 1. <36> The heating temperature in the firing step is preferably 150°C or higher, more preferably 200°C or higher, even more preferably 240°C or higher, and still more preferably 250°C or higher. <4> ~ <35> 1. A method for producing a copper sintered body according to any one of the above. <37> The pressure applied in the firing step is preferably 2 MPa or more, more preferably 4 MPa or more, and preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 15 MPa or less. <4> ~ <36> 1. A method for producing a copper sintered body according to any one of the above. <38> The baking time is preferably 150 seconds or more, more preferably 200 seconds or more, even more preferably 250 seconds or more, even more preferably 300 seconds or more, and 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. <4> ~ <37> 1. A method for producing a copper sintered body according to any one of the above. <39> <4> ~ <38> A copper sintered body obtained by the manufacturing method described in any one of the above. <40> A first member, a second member, and a joining of the first member and the second member <1> ~ <3> and <39> A joined body comprising the copper sintered body according to any one of the above. <41> The first member is preferably a semiconductor chip selected from a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, and a diamond semiconductor chip. <40> The conjugate according to claim 1. <42> The second member is preferably a copper substrate. <40> or <41> The conjugate according to claim 1. <43> Preferably, it is a semiconductor device, more preferably a power device. <40> ~ <42> 10. The conjugate according to any one of the preceding claims. <44> A method for manufacturing a bonded body comprising a first member, a second member, and a copper sintered body that bonds the first member and the second member, the method comprising the following steps 0-1 and 1. Step 0-1: A step of applying a dispersion D containing copper nanoparticles A and the following polymer B between the first member and the second member. Step 1: A step of baking the dispersion D at a baking temperature of 240°C or more and 300°C or less while applying a pressure of 0.1 MPa or more and 40 MPa or less. <45> The first member is preferably a semiconductor chip selected from a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, and a diamond semiconductor chip. <44> A method for producing the bonded body according to claim 1. <46> The second member is preferably a copper substrate. <44> or <45> A method for producing the bonded body according to claim 1. <47> Preferably, it is a semiconductor device, more preferably a power device. <44> ~ <46> 10. A method for producing the bonded body according to any one of the above items. <48> the junction is a semiconductor device, the first member is a semiconductor chip selected from a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, and a diamond semiconductor chip; The second member is a copper substrate. <44> ~ <47> 10. A method for producing the bonded body according to any one of the above items. <49> The copper content in the copper nanoparticles A 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. <44> ~ <48> 10. A method for producing the bonded body according to any one of the above items. <50> The average particle size of the copper nanoparticles A is preferably 50 nm or more, more preferably 75 nm or more, even more preferably 100 nm or more, even more preferably 125 nm or more, and preferably 400 nm or less, more preferably 375 nm or less, even more preferably 350 nm or less, even more preferably 320 nm or less. <44> ~ <49> 10. A method for producing the bonded body according to any one of the above items. <51> The content of copper nanoparticles A in dispersion D is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 91% by mass or less, even more preferably 90% by mass or less. <44> ~ <50> 10. A method for producing the bonded body according to any one of the above items. <52> Dispersion D further contains copper microparticles A', and the copper content in the copper microparticles A' 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. <44> ~ <51> 10. A method for producing the bonded body according to any one of the above items. <53> The average particle size of the copper microparticles A' is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and is preferably 6 μm or less, more preferably 5 μm or less, even more preferably 4 μm or less. <52> A method for producing the bonded body according to claim 1. <54> The content of copper microparticles A' in dispersion D is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, and preferably 70% by mass or less, more preferably 65% ​​by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, even more preferably 50% by mass or less. <52> ~ <53> 10. A method for producing the bonded body according to any one of the above items. <55> The mass ratio of the content of copper nanoparticles A to the total content of copper nanoparticles A and copper microparticles A' in dispersion D [copper nanoparticles A / (copper nanoparticles A+copper microparticles A')] is preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, even more preferably 0.6 or more, and is preferably 1.0 or less, more preferably 0.9 or less, even more preferably 0.8 or less, even more preferably 0.75 or less. <51> ~ <54> 10. A method for producing the bonded body according to any one of the above items. <56> The monomer (b-1) is at least one selected from the group consisting of 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. <44> ~ <51> 10. A method for producing the bonded body according to any one of the above items. <57> The monomer (b-2) is at least one selected from the group consisting of polyalkylene glycol (meth)acrylate, alkoxy polyalkylene glycol (meth)acrylate, and phenoxy polyalkylene glycol (meth)acrylate. <44> ~ <56> 10. A method for producing the bonded body according to any one of the above items. <58> The monomer (b-2) is preferably at least one selected from the group consisting of polyalkylene glycol (meth)acrylates and alkoxy polyalkylene glycol (meth)acrylates, more preferably an alkoxy polyalkylene glycol (meth)acrylate, and the number of carbon atoms in the alkoxy group of the alkoxy polyalkylene glycol (meth)acrylate is preferably 1 or more and 18 or less, more preferably 1 or more and 14 or less, and even more preferably 1 or more and 12 or less. <57> A method for producing the bonded body according to claim 1. <59> The polyalkylene glycol segment of the monomer (b-2) preferably contains a unit derived from an alkylene oxide having from 2 to 4 carbon atoms. <44> ~ <58> 10. A method for producing the bonded body according to any one of the above items. <60> the number of alkylene oxide-derived units in the polyalkylene glycol segment of the monomer (b-2) is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, and is preferably 100 or less, more preferably 70 or less, even more preferably 50 or less, even more preferably 40 or less, even more preferably 35 or less; <44> ~ <59> 10. A method for producing the bonded body according to any one of the above items. <61> Polymer B further contains a structural unit derived from a hydrophobic monomer (b-3). <44> ~ <60> 10. A method for producing the bonded body according to any one of the above items. <62> The monomer (b-3) is preferably at least one selected from an aromatic group-containing monomer and a (meth)acrylate having a hydrocarbon group derived from an aliphatic alcohol. <61> A method for producing the bonded body according to claim 1. <63> Polymer B is more preferably a vinyl polymer containing, as monomer (b-1), a structural unit derived from at least one selected from the group consisting of (meth)acrylic acid and maleic acid, and, as monomer (b-2), a structural unit derived from an alkoxypolyalkylene glycol (meth)acrylate. <44> ~ <62> 10. A method for producing the bonded body according to any one of the above items. <64> the content of the vinyl polymer containing a structural unit derived from the monomer (b-1) and a structural unit derived from the monomer (b-2) in the polymer B is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably substantially 100% by mass; <63> A method for producing the bonded body according to claim 1. <65> During the production of polymer B, the total content of monomer (b-1) and monomer (b-2) in the raw material monomers or the total content of structural units derived from monomer (b-1) and structural units derived from monomer (b-2) in polymer B is preferably 72% by mass or more, more preferably 88% by mass or more, even more preferably 91% by mass or more, even more preferably 97% by mass or more, and even more preferably substantially 100% by mass. <44> ~ <64> 10. A method for producing the bonded body according to any one of the above items. <66> During the production of polymer B, the content of monomer (b-1) in the raw material monomers or the content of structural units derived from monomer (b-1) in polymer B is preferably 3% by mass or more, more preferably 5% by mass or more, and preferably 35% by mass or less, more preferably 25% by mass or more, even more preferably 18% by mass or less, and even more preferably 10% by mass or less. <44> ~ <65> 10. A method for producing the bonded body according to any one of the above items. <67> During the production of polymer B, the content of monomer (b-2) in the raw material monomers or the content of structural units derived from monomer (b-2) in polymer B is preferably 55% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 84% by mass or more, even more preferably 90% by mass or more, and is preferably 97% by mass or less, more preferably 95% by mass or less. <44> ~ <66> 10. A method for producing the bonded body according to any one of the above items. <68> The content of polyalkylene glycol segments in polymer B is preferably 55% by mass or more and 97% by mass or less, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 84% by mass or more, and more preferably 94% by mass or less, even more preferably 92% by mass or less. <44> ~ <67> 10. A method for producing the bonded body according to any one of the above items. <69> The number average molecular weight Mn of polymer B is preferably 4,000 or more, more preferably 6,000 or more, even more preferably 7,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 10,000 or less. <44> ~ <68> 10. A method for producing the bonded body according to any one of the above items. <70> The acid value of Polymer B is preferably 20 mgKOH / g or more and 250 mgKOH / g or less, more preferably 25 mgKOH / g or more, even more preferably 30 mgKOH / g or more, even more preferably 35 mgKOH / g or more, even more preferably 40 mgKOH / g or more, and more preferably 230 mgKOH / g or less, even more preferably 220 mgKOH / g or less, even more preferably 215 mgKOH / g or less. <44> ~ <69> 10. A method for producing the bonded body according to any one of the above items. <71> The content of polymer B in dispersion D is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, and is preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, even more preferably 7% by mass or less. <44> ~ <70> 10. A method for producing the bonded body according to any one of the above items. <72> The mass ratio of the content of polymer B to the total content of copper nanoparticles A and polymer B in dispersion D [polymer B / (copper nanoparticles A+polymer B)] is preferably 0.0055 or more, more preferably 0.0058 or more, even more preferably 0.0060 or more, and is preferably 0.025 or less, more preferably 0.022 or less, even more preferably 0.020 or less, even more preferably 0.018 or less. <44> ~ <71> 10. A method for producing the bonded body according to any one of the above items. <73> Dispersion D further contains a dispersion medium C; <44> ~ <72> 10. A method for producing the bonded body according to any one of the above items. <74> The dispersion medium C is one or more organic solvents selected from the group consisting of hydrocarbons, alcohols, ethers, and esters; <73> A method for producing the bonded body according to claim 1. <75> The content of the dispersion medium C in the dispersion D is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less. <73> or <74> A method for producing the bonded body according to claim 1. <76> The mass ratio of the content of dispersion medium C to the content of copper nanoparticles A in dispersion D [dispersion medium C / copper nanoparticles A] is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, and preferably 1.0 or less, more preferably 0.5 or less, even more preferably 0.2 or less. <73> ~ <75> 1. A method for producing a joined body according to any one of the methods for producing a copper sintered body described above. <77> In the dispersion D, the content of copper nanoparticles A is preferably 30% by mass or more and 95% by mass or less, the content of polymer B is preferably 0.1% by mass or more and 10% by mass or less, the content of dispersion medium C is preferably 4% by mass or more and 60% by mass or less, and the content of copper microparticles A' is preferably 0% by mass or more and 65% by mass or less, <44> or <76> A method for manufacturing a bonded body. <78> The heating temperature in the firing step is preferably 150°C or higher, more preferably 200°C or higher, even more preferably 240°C or higher, and still more preferably 250°C or higher. <44> ~ <77> 10. A method for producing the bonded body according to any one of the above items. <79> The pressure applied in the firing step is preferably 2 MPa or more, more preferably 4 MPa or more, and preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 15 MPa or less. <44> ~ <78> 10. A method for producing the bonded body according to any one of the above items. <80> The baking time is preferably 150 seconds or more, more preferably 200 seconds or more, even more preferably 250 seconds or more, even more preferably 300 seconds or more, and 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. <44> ~ <79> 10. A method for producing the bonded body according to any one of the above items. [Example]

[0081] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. In the following Production Examples, Examples and Comparative Examples, "parts" and "%" are "parts by mass" and "% by mass" unless otherwise specified. Various physical properties were measured or calculated by the following methods.

[0082] [Average particle size of copper nanoparticles A and copper microparticles A'] Scanning electron microscope (SEM) images of copper nanoparticles A and copper microparticles were taken using a scanning electron microscope (Hitachi High-Tech Corporation, field emission scanning electron microscope: S-4800). The magnification was determined depending on the particle size, and images were taken at magnifications ranging from 5,000x to 150,000x. The SEM images were analyzed using image analysis software ImageJ (obtained from the National Institutes of Health, USA), and the particle sizes of 100 or more particles per sample were determined. The arithmetic mean value of these particles was used as the average particle size of copper nanoparticles A and copper microparticles A'.

[0083] [Calculation of the mass ratio of the dispersion coated on copper in copper nanoparticles A [polymer B / (copper nanoparticles A)]] Using a differential thermal / thermogravimetric simultaneous analyzer (TG / DTA) (Hitachi High-Tech Science Corporation, product name: STA7200RV), 10 mg of the sample (dried powder of copper microparticles A coated with dispersion D) was weighed into an aluminum pan and heated from 35 ° C to 550 ° C at a heating rate of 10 ° C / min under a 50 mL / min nitrogen flow, and the mass loss was measured. The mass loss from 35 ° C to 550 ° C was taken as the mass of polymer B, and the remaining mass at 550 ° C was taken as the mass of copper nanoparticles A. The mass ratio of polymer B coated on copper in copper nanoparticles A to dispersion D [polymer B / (copper microparticles A)] was calculated using the following formula. Mass ratio of polymer B coated on copper nano A = (mass loss from 35°C to 550°C) / (mass loss from 35°C to 550°C + remaining mass at 550°C)

[0084] [Measurement of number average molecular weight Mn of polymer B] The measurement was performed by gel permeation chromatography. The measurement sample was prepared by mixing 0.1 g of polymer with 10 mL of eluent in a glass vial, stirring with a magnetic stirrer at 25°C for 10 hours, and filtering with a syringe filter (DISMIC-13HP PTFE 0.2 μm, manufactured by Advantec Toyo Co., Ltd.). The measurement conditions are shown below. GPC equipment: Tosoh Corporation "HLC-8320GPC" Column: Tosoh Corporation "TSKgel SuperAWM-H, TSKgel SuperAW3000, TSKgel guardcolumn Super AW-H" Eluent: N,N-dimethylformamide dissolved with phosphoric acid and lithium bromide at concentrations of 60mmol / L and 50mmol / 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)"

[0085] [Measurement of Acid Value of Polymer B] The acid value of Polymer B was measured in accordance with JIS K0070:1992 (potentiometric titration method), except that the measurement solvent was changed from the ethanol and ether mixed solvent specified in JIS K0070 to an acetone and toluene mixed solvent (acetone:toluene = 4:6 (volume ratio)).

[0086] [Production of Polymer B-1] Manufacturing Example 1 A 1000 mL four-necked round-bottom flask equipped with a thermometer, two 100 mL nitrogen-bypass dropping funnels, and a reflux condenser was charged with 20.0 g of ethanol (Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent). The flask was heated to 80°C in an oil bath, and nitrogen bubbling was performed for 10 minutes. Next, 7.0 g of methacrylic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), 93.0 g of methoxypolyethylene glycol (EO 4 mol) methacrylate (NOF Corporation, "PME-200"), 1.0 g of 3-mercaptopropionic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent), and 28.7 g of ethanol were dissolved in a polybeaker and placed in the dropping funnel (1). Separately, 51.3 g of ethanol and 1.3 g of 2,2'-azobis(2,4-dimethylvaleronitrile) ("V-65" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., polymerization initiator) were dissolved in a plastic beaker and placed in the dropping funnel (2). Next, the mixtures in the dropping funnels (1) and (2) were simultaneously added dropwise to the flask over 90 minutes. Thereafter, the internal temperature of the flask was raised to 90°C, and stirring was continued for another hour to complete the reaction. The resin solution 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) under drying conditions (freezing at -25°C for 1 hour, vacuum at -10°C for 9 hours, vacuum at 25°C for 5 hours, vacuum level 5 Pa) to obtain bone-dried polymer B-1 (methacrylic acid / methoxypolyethylene glycol (EO 4 mol) methacrylate polymer, acid value: 46 mg KOH / g, Mn: 12100).

[0087] [Table 1]

[0088] MAA: Methacrylic acid (Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) PEG(4)MA: Methoxypolyethylene glycol (EO 4 mol) methacrylate (NOF Corporation "PME-200")

[0089] (Synthesis of copper nanoparticle A dry powder) Synthesis Example 1 (Production of Copper Nanoparticles A-1) 50.0 g of copper oxide (N-120, manufactured by Nisshin Chemco Co., Ltd.) as a copper raw material compound, 1.20 g of polymer B-1, and 500 g of ethanol (95) (Fujifilm Wako Pure Chemical Industries, Ltd., first-class reagent) were added to a 2 L beaker and stirred for 15 minutes. During stirring, the temperature of the reaction solution was controlled at 70 °C using an oil bath. Next, 63.0 g of hydrazine monohydrate (special grade reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) placed in a 50 mL dropping funnel was added dropwise to the mixed solution over 20 minutes at 25° C. Thereafter, the reaction solution was stirred for 1 hour while controlling the temperature at 70° C. in an oil bath, and then air-cooled to obtain a reddish-brown dispersion containing copper nanoparticles. The entire amount of the obtained dispersion was placed in a Hitachi Koki Co., Ltd. centrifuge sedimentation tube 500PA bottle using a refrigerated centrifuge "himacCR22G" and rotor (R12A, radius 15.1 cm), and centrifuged at 3000 rpm with a centrifugal acceleration of 675 G for 30 minutes. 300 g of ethanol (95) (Fujifilm Wako Pure Chemical Corporation, first-class reagent) was added to the precipitate separated by centrifugation, and the mixture was stirred for 15 minutes to redisperse. The entire amount of the redispersion was centrifuged again under the same conditions, and the precipitate was separated. This procedure was repeated three times. The purified copper nanoparticle precipitate 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 36.5 g of copper nanoparticles A-1. The drying conditions were freezing at -25 ° C for 1 hour, drying at -10 ° C for 9 hours under reduced pressure at 5 Pa, and further drying at 25 ° C for 5 hours under reduced pressure at 5 Pa to obtain a dried powder of copper nanoparticles A-1. The obtained copper nanoparticles A-1 had an average particle size of 185 nm and a polymer B-1 content of 1.0 mass%. The results are shown in Table 2.

[0090] [Table 2]

[0091] Example 1 (Preparation of copper particle dispersion) 4.0 parts by mass of diethylene glycol, 3.0 parts by mass of tetraethylene glycol, 50 parts by mass of dried powder of copper nanoparticles A-1, and 43 parts by mass of MA-C025K (Mitsui Mining & Smelting Co., Ltd., average particle size 2.4 μm) were added to an agate mortar and mixed until the dried powder was no longer visible to the naked eye. The resulting mixture was transferred to a plastic bottle. The sealed plastic bottle was stirred for 2000 min using a planetary vacuum mixer (Thinky Corporation, Planetary Vacuum Mixer ARV-310). -1 The mixture was stirred at 2000 rpm for 5 minutes, and then passed three times through a three-roll mill (Imex Co., Ltd., BV 100) with a gap adjusted to 0.2 mm to obtain copper particle dispersion 1.

[0092] (Manufacturing of sintered copper) The obtained copper particle dispersion 1 was used to produce a copper sintered body according to the following method. First, a stainless steel metal mask (50 μm thick) with a 17 mm x 17 mm square opening was placed on a 30 mm x 30 mm silicon wafer (total thickness: 0.4 mm), and the copper particle dispersion was applied to the silicon wafer by stencil printing using a metal squeegee. The wafer was then dried at 110°C for 10 minutes on a Shamal hot plate (AS ONE Corporation, Model: HHP-441) in air. A 15 mm x 15 mm silicon wafer (400 μm thick) was then placed on the coated copper particle dispersion. The copper particle dispersion sandwiched between silicon wafers was then placed in a pressure firing machine (Meisho Kiko Co., Ltd., Model: HTM-1000), and nitrogen was flowed into the furnace at 500 mL / min to replace the air inside the furnace. The upper and lower heating heads were then used to pressurize the laminate at 10 MPa while raising the temperature of the heating heads to 260°C over 3 minutes. After the temperature increase, the heating heads were held at 260°C for 300 seconds to obtain a sintered copper compact. After sintering, the heating heads were water-cooled at -60°C / min, and the copper sintered compact sandwiched between the silicon wafers at 100°C or below was removed into air, and the copper sintered compact alone was removed from the silicon wafers.

[0093] (Manufacturing of Joints) Using the obtained copper particle dispersion 1, a bonded body was produced according to the following method. First, a stainless steel metal mask (thickness: 50 μm) with three rows of 6 mm x 6 mm square openings was placed on a 30 mm x 30 mm copper plate (total thickness: 1 mm), and the copper particle dispersion was applied to the copper plate by stencil printing using a metal squeegee. The copper plate was then dried at 110 °C for 10 minutes on a Shamal hot plate (manufactured by AS ONE Corporation, model: HHP-441) in air. A 5 mm x 5 mm silicon chip (thickness: 400 μm) was then prepared by sputtering titanium, nickel, and gold in this order, and the silicon chip was placed on the applied copper particle dispersion so that the gold was in contact with the copper particle dispersion. This resulted in a laminate consisting of a copper plate, copper particle dispersion, and silicon chip stacked in this order. The resulting laminate was fired in the following manner to obtain a bonded body. First, the laminate was placed in a pressure firing machine (Meisho Kiko Co., Ltd., model HTM-1000), and nitrogen was flowed into the furnace at 500 mL / min to replace the air in the furnace with nitrogen. The upper and lower heating heads were then used to pressurize the laminate at 10 MPa while raising the temperature of the heating heads to 260°C over 3 minutes. After the temperature increase, the heating heads were held at 260°C for 300 seconds for sintering, obtaining a bonded body. After sintering, the heating heads were water-cooled at a cooling rate of -60°C / min, and the bonded body was removed into air at 100°C or below.

[0094] Example 2, Comparative Example 1 The same procedures as in Example 1 were carried out except that the pressure firing conditions shown in Table 3 were changed, and copper sintered bodies and joined bodies of Example 2 and Comparative Example 1 were obtained, respectively.

[0095] [Table 3]

[0096] The copper sintered bodies and joined bodies obtained in Examples 1 and 2 and Comparative Example 1 were evaluated as follows.

[0097] <Evaluation> [Measurement of tensile modulus and tensile strength of sintered copper] The tensile modulus and tensile strength of the copper sintered body were measured according to the following procedure. The thickness of the copper sintered compact was measured using a digital micrometer. The central portion of the copper sintered compact was cut at a width of 1 mm to obtain a 15 mm x 1 mm copper sintered compact. The copper sintered compact was placed on a tensile jig with a gauge length of 5 mm in a thermomechanical analyzer (Hitachi High-Tech Science Corporation, Model: TMA7100), and the thickness of the copper sintered compact was entered into the program. A heating and cooling furnace was set up to enclose the copper sintered compact, and a tensile test was performed at 25°C and a tensile rate of 1 N / min up to the tensile test limit of the thermomechanical analyzer, 6.82 N. The obtained results were converted into stress-strain curves using the software provided with the thermomechanical analyzer. The tensile modulus of the copper sintered compact was calculated using an approximate equation based on the slope of the strain range of 0.25% to 0.50%. The tensile strength (MPa) was defined as the maximum stress value of the stress-strain curve.

[0098] [Porosity of sintered copper] The copper sintered body was subjected to cross-sectional milling using a cooled cross-section polisher (JEOL Ltd., model IB-19520CCP). The cross-section of the copper sintered body obtained by cross-sectional milling was observed with a scanning electron microscope (Hitachi High-Tech Corporation, model S-4800) and SEM images were taken. Images were taken at a magnification of 5000x. Using the image analysis software ImageJ (obtained from the National Institutes of Health, USA), the SEM images were converted into binary images that express shades in two shades of black and white by binarization, and the porosity was calculated using the following formula. Porosity (%) = pore area (number of black pixels) / total area of ​​sintered copper body {area of ​​sintered copper body (number of white pixels) + pore area (number of black pixels)} × 100

[0099] [Debonding rate and chip cracking after temperature cycling] A bonded structure was fabricated using copper particle dispersion 1 in the same manner as described above. The bonded structure was placed in a compact thermal shock chamber (Espec Corporation, Model: TSE-12-A) and subjected to 4,000 temperature cycles in air at temperatures of -55°C and 200°C for 15 minutes each. Afterwards, the three silicon chips were visually inspected for cracks, and any cracks detected were considered to be cracks. The bonded interface was then observed from the copper substrate side of the bonded structure using an ultrasonic flaw detector (Hitachi Power Solutions Co., Ltd., Model: FS100III) equipped with a 50 MHz frequency probe. The instrument was fine-tuned to maximize the reflection peak at the bonded interface, and measurements were taken at a material sound velocity of 4,700 mm / s (Cu) and a gain of 28 dB. The reflection intensity threshold was set to 60%, and anything above that was considered delamination. The delamination area, obtained by binarization using the threshold, was calculated using software to determine the delamination rate.

[0100] The results of the copper sintered bodies and joined bodies obtained in Examples 1 and 2 and Comparative Example 1 are shown in Table 4.

[0101] [Table 4]

[0102] From Table 4, it can be seen that the copper sintered bodies of Examples 1 and 2 had a lower elastic modulus than the copper sintered body of Comparative Example 1, and therefore no chip cracking occurred after the temperature cycles, and the peeling rate of the bond after the temperature cycles was also low.

Claims

1. A copper sintered body having a tensile modulus of elasticity of 35 GPa or less.

2. 2. The copper sintered body according to claim 1, wherein the porosity is 1% or more and 25% or less.

3. The copper sintered body according to claim 1, having a tensile strength of 100 MPa or more.

4. A method for producing a copper sintered body, comprising the following step 1: Step 1: A step of baking a dispersion D containing copper nanoparticles A and the following polymer B at a baking temperature of 240 ° C. or more and 300 ° C. or less while applying a pressure of 0.1 MPa or more and 40 MPa or less Polymer B: A polymer containing a structural unit derived from a monomer (b-1) having a carboxy group and a structural unit derived from a monomer (b-2) having a polyalkylene glycol segment.

5. The method for producing a copper sintered body according to claim 4, further comprising the following step 0 before step 1: Step 0: Applying the Dispersion D to a Member

6. 6. The method for producing a copper sintered body according to claim 5, wherein the step 0 is a step of applying the dispersion D between a first member and a second member so that the dispersion D is interposed between the first member and the second member.

7. The method for producing a copper sintered body according to claim 4, wherein the dispersion D further contains copper microparticles A'.

8. The method for producing a copper sintered body according to claim 4, wherein the content of the copper nanoparticles A in the dispersion D is 20% by mass or more and 95% by mass or less.

9. The mass ratio of the content of polymer B to the total content of copper nanoparticles A and polymer B in the dispersion D [polymer B / (copper nanoparticles A + polymer B)] is 0.0055 or more and 0.025 or less. The method for producing a copper sintered body according to claim 4.

10. 5. The method for producing a copper sintered body according to claim 4, wherein the dispersion D further contains a dispersion medium C, and the content of the dispersion medium C in the dispersion D is 1% by mass or more and 20% by mass or less.

11. The mass ratio of the content of the dispersion medium C to the content of the copper nanoparticles A in the dispersion D [dispersion medium C / copper nanoparticles A] is 0.01 or more and 0.05 or less. The method for producing a copper sintered body according to claim 10.

12. The method for producing a copper sintered body according to claim 4, wherein the firing time is 150 seconds or more and 3600 seconds or less.

13. A copper sintered body obtained by the manufacturing method according to any one of claims 4 to 12.

14. A joined body comprising: a first member; a second member; and the copper sintered body according to claim 1 or 13, which joins the first member and the second member.

15. A method for manufacturing a joined body including a first member, a second member, and a copper sintered body that joins the first member and the second member, the method comprising the following steps 0-1 and 1. Step 0-1: A step of applying a dispersion D containing copper nanoparticles A and the following polymer B between the first member and the second member Step 1: A method for producing a bonded body, comprising a step of firing the dispersion D at a firing temperature of 240° C. or higher and 300° C. or lower while applying a pressure of 0.1 MPa or higher and 40 MPa or lower.

16. The method for producing a bonded body according to claim 15, wherein the dispersion D further contains copper microparticles A'.

17. The method for producing a joined body according to claim 15, wherein the content of the copper nanoparticles A in the dispersion D is 20% by mass or more and 95% by mass or less.

18. 16. The method for producing a joined body according to claim 15, wherein the mass ratio of the content of the polymer B to the total content of the copper nanoparticles A and the polymer B in the dispersion D [polymer B / (copper nanoparticles A + polymer B)] is 0.0055 or more and 0.025 or less.

19. 16. The method for producing a joined body according to claim 15, wherein the dispersion D further contains a dispersion medium C, and the content of the dispersion medium C in the dispersion D is 1% by mass or more and 20% by mass or less.

20. the junction is a semiconductor device, the first member is a semiconductor chip selected from a silicon semiconductor chip, a silicon carbide semiconductor chip, a gallium nitride semiconductor chip, a gallium oxide semiconductor chip, and a diamond semiconductor chip; The method for producing a bonded body according to claim 15, wherein the second member is a copper substrate.

21. 17. The method for producing a joined body according to claim 16, wherein the mass ratio of the content of copper nanoparticles A to the total content of copper nanoparticles A and copper microparticles A' in dispersion D [copper nanoparticles A / (copper nanoparticles A+copper microparticles A')] is 0.3 or more and 1.0 or less.

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