Composition and method for producing composition

Abstract

To provide a composition that, when used for sinter bonding, can be sintered at a low temperature, can be firmly bonded, and can form a sintered body having excellent heat resistance. A composition according to the present disclosure includes composite particles, an organic material, and particles containing Ag and / or Cu other than the composite particles. The composite particles include base material particles and Ag and / or Cu supported on the base material particles. The linear expansion coefficient of the base material particles is 8 ppm / K or less. The particle sintering rate represented by formula (1) is 30% or more. Formula (1): Particle sintering rate = (total number of base material particles bonded to the object to be bonded that have a length of 100 nm or more in at least one direction in an image obtained by photographing a cross section of a sintered body after the sintering step at 20,000× using FE-SEM) / (total number of base material particles having a length of 100 nm or more in at least one direction in an image obtained by photographing a cross section of the sintered body after the sintering step at 20,000× using FE-SEM)

Description

Composition and method for producing the composition

[0001] This disclosure relates to compositions and methods for producing the compositions. This application claims priority to Japanese Patent Application No. 2024-34444, filed March 6, 2024, and Japanese Patent Application No. 2024-157033, filed September 10, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, when die-bonding (die-attaching) semiconductor elements that operate at high temperatures, such as SiC chips, sinter bonding has been considered, in which a metal paste containing nano-sized or micro-sized particles of silver or copper is used as a bonding material, and the bonding material is interposed between objects to be bonded and heated for a predetermined time to sinter the metal, such as silver, in the bonding material, thereby bonding the objects to be bonded together by a metal bonding layer (see, for example, Patent Document 1). This metal bonding technology is expected to be applied to various electronic elements, such as power semiconductor elements and LED elements.

[0003] However, metals such as silver are too hard as die-attach materials, and the difference in thermal expansion coefficient between a semiconductor element such as Si or SiC and a metal layer such as silver is very large, so that in thermal fatigue tests exceeding 200° C., cracks develop in the sintered portion, and insulating substrates such as the semiconductor element or DBC (Direct Bonded Copper) break, resulting in insufficient heat resistance. Furthermore, when metal is used as the bonding material, the only way to improve bonding strength and heat resistance is to control the density of the sintering, which poses the problem of not being able to essentially change the mechanical properties of the bonded body.

[0004] To solve the above problems, a material having specific metal nanoparticles supported on a carrier is known as a material that combines low-temperature processability and heat resistance (for example, Patent Document 2).

[0005] International Publication No. 2018 / 037992 Japanese Patent Application Laid-Open No. 2010-65265

[0006] However, there are limitations to the combinations of conventionally known metal nanoparticles with simple substances, and the functions that can be exhibited are also limited. Therefore, there has been a demand for materials with better low-temperature sintering properties and heat resistance.

[0007] Therefore, an object of the present disclosure is to provide a composition that, when used for sinter bonding, can be sintered at low temperatures, yet can form a strong bond and a sintered body with excellent heat resistance.

[0008] As a result of intensive research to solve the above problems, the inventors of the present disclosure have found that a composition containing base particles and Ag and / or Cu supported on the base particles, where the base particles contain composite particles satisfying specific physical properties, and which satisfies specific physical property values ​​when sintered, can be sintered at a low temperature, can be firmly bonded, and can form a sintered body with excellent heat resistance. The invention of the present disclosure was completed based on these findings.

[0009] That is, the present disclosure aims to provide a composition comprising composite particles, an organic substance, and particles other than the composite particles that contain Ag and / or Cu, wherein the composite particles comprise base particles and Ag and / or Cu supported on the base particles, the base particles have a linear expansion coefficient of 8 ppm / K or less, and a particle sintering rate represented by the following formula (1) of 30% or more: Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The above composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

[0010] The composition has a specific combination of composite particles, metal particles, and organic matter, and the particle sintering rate is 30% or more. This allows for sintering at low temperatures, while still achieving strong bonding and forming a sintered body with excellent heat resistance.

[0011] The composition is characterized in that the base particles are Si, W, SiO ２ , Cr, and Mo.

[0012] It is preferable that the volume ratio of Ag and / or Cu is 50 to 95% by volume of all particles contained in the composition.

[0013] In an image taken at 1000x magnification using an SEM at any five points on the cross section of the composite particle, the average number of particle agglomerates A described below is preferably 2 or less: Particle agglomerate A: Comprises a plurality of base particles and Ag and / or Cu, the area ratio of the supported Ag and / or Cu to the base particles is 70 area % or more, and the diameter of the longest part in the agglomerate is 5 μm or more.

[0014] The present disclosure also provides a method for producing a composition containing composite particles in which a metal is supported on a base particle and a solvent, the method comprising: a step of irradiating ultrasonic waves to composition (A) containing the base particle, a metal compound serving as a raw material for the metal, and a solvent, in order to produce the composite particle, thereby obtaining a composition having a particle sintering rate of 30% or more, as represented by the following formula (1): Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The above composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

[0015] In the step of irradiating with ultrasonic waves, the temperature of the composition (A) is preferably 20 to 100°C.

[0016] In the step of irradiating with ultrasonic waves, the ultrasonic irradiation conditions are preferably a frequency of 5 to 1000 kHz and an output of 10 to 1000 W.

[0017] The solvent in the composition preferably contains water or an alcohol.

[0018] It is preferable that the composition (A) further contains a reducing agent.

[0019] It is preferable that the composition (A) further contains a carboxylic acid.

[0020] The base particles are Si, W, SiO ２ , Cr, and Mo.

[0021] The metal compound is preferably a metal oxide and / or a metal carboxylate.

[0022] When the composition of the present disclosure is used for sinter bonding, it can be sintered at a low temperature, yet can firmly bond the materials, and can form a sintered body with excellent heat resistance.

[0023] 1 is an FE-SEM image of a cross section of a sintered body of a composition according to an embodiment of the present disclosure. 2 is an FE-SEM image of a cross section of a sintered body of Example 1. 3 is an FE-SEM image of a cross section of a sintered body of Example 2. 4 is an FE-SEM image of a cross section of a sintered body of Comparative Example 1.

[0024] [Composition] The composition of the present disclosure comprises composite particles, an organic substance, and particles other than the composite particles that contain Ag and / or Cu, the composite particles comprising base particles and Ag and / or Cu supported on the base particles, the base particles having a linear expansion coefficient of 8 ppm / K or less and a particle sintering rate represented by the following formula (1) of 30% or more, whereby when used for sinter bonding, strong bonding can be achieved while sintering at a low temperature, and a sintered body with excellent heat resistance can be formed. Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The above composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

[0025] The object to be bonded in the above formula (1) includes anything to which the composite particles can be bonded. Specifically, it includes composite particles contained in the above composition, particles other than the composite particles, and substrates, electronic components, and the like in addition to the above composition. Furthermore, the "composite particles bonded to the object to be bonded" refers to composite particles bonded to at least one of the above objects to be bonded.

[0026] 1 is an FE-SEM image of a sintered body of the above composition, which shows that the sintered composite particles 1 are bonded to objects 2, such as particles 21 other than the composite particles and a substrate 22.

[0027] The volume ratio of Ag and / or Cu to all particles contained in the composition is preferably 50 to 95 volume %, more preferably 60 to 95 volume %, and even more preferably 70 to 90 volume %. Note that particles that can be contained in the composition include the composite particles, particles containing Ag and / or Cu other than the composite particles, and particles other than the above particles.

[0028] The particle sintering rate of the composition is 30% or more, preferably 35% or more, and more preferably 37% or more. By having the particle sintering rate of 30% or more, it is possible to firmly bond the material to be bonded. The upper limit is not particularly limited, but may be 100%.

[0029] Furthermore, the composition preferably has a unit sintering rate, represented by the following formula (2), of 0.7 or more, more preferably 1.0 or more, even more preferably 2.0 or more, and particularly preferably 3 or more. A unit sintering rate of 0.7 or more allows for more efficient bonding during sintering. Unit sintering rate = (particle sintering rate) / (volume ratio of supported Ag and / or Cu to the volume of base particle) (2) Specifically, the (volume ratio of supported Ag and / or Cu to the volume of base particle) is represented by the following formula (3), where VA is the volume of the base particle and VB is the volume ratio of supported Ag and / or Cu in the composite particle. (volume ratio of supported Ag and / or Cu to the volume of base particle) = VB / (VA + VB) (3) Furthermore, the volume can also be substituted by the area of ​​each image taken by SEM.

[0030] The form of the composition is not particularly limited, but specific examples include paste, ink, and the like.

[0031] (Composite Particle) The composite particle includes the base particle and Ag and / or Cu supported on the base particle, and the base particle is made of Si, W, SiO ２ The composition contains particles of one or more raw materials selected from the group consisting of Ag, Cr, and Mo. It is preferable that the Ag and / or Cu are uniformly supported on the substrate particles as Ag particles and / or Cu particles, and as the amount of adhesion increases, they may be supported on the substrate particles in the form of a film. When supported in the form of a film, it may be a film of Ag or Cu alone, or a film containing both Ag and Cu. In the composition, only one type of composite particle may be used, or two or more types may be used.

[0032] In an image of the composite particle taken at 1000x magnification using an SEM, the number of particle agglomerates A described below is preferably two or less, more preferably one or less, and even more preferably no particle agglomerates A are present. Having the number of particle agglomerates A be two or less not only facilitates the exertion of heat resistance but also means that Ag or Cu is not unevenly distributed in the composite particle, and Ag and / or Cu are uniformly supported on the base particle, resulting in excellent sinterability. Particle agglomerate A: Contains a plurality of base particles and Ag and / or Cu, the area ratio of the supported Ag and / or Cu to the base particle is 70 area% or more, and the diameter of the longest part in the agglomerate is 5 μm or more.

[0033] The number of base particles contained in the particle agglomerate A is preferably 30% or less, more preferably 15% or less, even more preferably 5% or less, and particularly preferably 3% or less, relative to the total number of base particles, and most preferably there is no particle agglomerate A. By having the total number of base particles contained in the particle agglomerate A be 30% or less, the amount of Ag and / or Cu in the composite particles can be made appropriate, making it easier to exhibit heat resistance.

[0034] The number of particle agglomerates A, the number of base particles contained in the particle agglomerates A, and the number of base particles can be counted from an image of a cross section taken with an SEM after the composite particle of the present disclosure is embedded in an epoxy resin and cured. The number of base particles also includes the number of base particles contained in the particle agglomerates A. The evaluation of the number of particle agglomerates A and the number of base particles represents an average value measured at any five locations in the sample.

[0035] Furthermore, the composite particles preferably have two or less particle agglomerates B in an image taken at 1000x magnification using an SEM, more preferably one or less, and even more preferably no particle agglomerates B are present. Having two or less particle agglomerates B not only facilitates heat resistance, but also means that Ag or Cu is not unevenly distributed in the composite particles, and Ag and / or Cu are uniformly supported on the base particles, resulting in excellent sinterability. Particle agglomerate B: Contains multiple base particles and Ag and / or Cu, wherein the area ratio of the supported Ag and / or Cu is 70 area% or more relative to the base particles, the voids in the particle agglomerates are 30 area% or less, and the diameter of the longest point in the agglomerates is 5 μm or more.

[0036] The number of base particles contained in the particle agglomerate B is preferably 30% or less, more preferably 15% or less, even more preferably 5% or less, and particularly preferably 3% or less, relative to the number of base particles, and most preferably there is no particle agglomerate B. By having the number of base particles contained in the particle agglomerate B be 30% or less, the amount of Ag and / or Cu in the composite particles can be made appropriate, making it easier to exhibit heat resistance.

[0037] The number of particle agglomerates B, the number of base particles contained in the particle agglomerates B, and the number of base particles can also be measured in the same manner as in the particle agglomerates A.

[0038] When the Ag is supported as particles, the Ag content in 100% by mass of the Ag particles is preferably 95% by mass or more, more preferably 99% by mass or more, and may be 99.9% by mass or more, or even 100% by mass. That is, it may be Ag particles alone. Furthermore, other components besides Ag may include silver oxide as a raw material, silver carboxylate as a reaction intermediate, additives such as a protective agent, etc., but from the viewpoint of exhibiting sinterability, it is preferable that no other components than the Ag are included. Incidentally, when Ag is supported in the form of a single film, it is preferable that the same range as above is satisfied.

[0039] Similarly, when the Cu is supported as particles, the Cu content in 100% by mass of the Cu particles is preferably 95% by mass or more, more preferably 99% by mass or more, and may be 99.9% by mass or more, or even 100% by mass. That is, it may be simple Cu particles. Furthermore, other components besides Cu may include copper oxide as a raw material, copper carboxylate as a reaction intermediate, additives such as a protective agent, etc., but from the viewpoint of exhibiting sinterability, it is preferable that no other components besides the Cu are included. Incidentally, when Cu is supported in the form of a simple film, it is preferable that the same range as above is satisfied.

[0040] The average particle size (median size) of the Ag particles and Cu particles is preferably 10,000 nm or less, more preferably 1,000 nm or less, even more preferably 500 nm or less, particularly preferably 200 nm or less, particularly preferably 100 nm or less, and particularly preferably 50 nm or less. The lower limit is not particularly limited, but from the viewpoint of production, it is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. The average particle size (median size) is calculated based on the volume of the particles and can be measured by a laser diffraction / scattering method.

[0041] When the Ag and / or Cu is supported on the base particle in the form of a film, the thickness thereof is preferably 10 nm to 10 μm, more preferably 50 nm to 5 μm, and even more preferably 100 nm to 3 μm. A thickness of 10 nm or more facilitates bonding during sintering. Furthermore, a thickness of 10 μm or less facilitates low-temperature sintering.

[0042] In order to reduce the coefficient of linear thermal expansion of the composite particles and to enhance heat resistance, when Ag is supported on the composite particles, Si and / or SiO are used as the base particles. ２When Cu is supported, the base particles are preferably particles of a raw material selected from the group consisting of W, Cr, and Mo. However, when Si is used as the base particles and Ag is supported, from the viewpoint of reducing the particle agglomerates A, it is preferable that the base particles are not composite particles produced by physical treatment such as a ball mill. Only one type of base particle may be used, or two or more types may be used.

[0043] The base particles may contain components other than those exemplified above. However, in order to facilitate the loading of Ag and Cu, the base particles should contain Si, SiO, etc., in the total amount (100% by mass) of the base particles. ２、 The total content of W, Cr, and Mo is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, particularly preferably 99.9% by mass or more, and may be 100% by mass. ２、 When any of W, Cr, and Mo is not contained, it is preferable that the total content ratio of the contained elements satisfies the above range.

[0044] The average particle size (median diameter) of the base particles is preferably 0.05 to 50 μm, more preferably 0.1 to 30 μm, and even more preferably 0.5 to 10 μm. When the average particle size is 0.05 μm or more, the surface area of ​​the simple substance is appropriate, and metal particles are easily supported on the surface. Furthermore, when the average particle size is 50 μm or less, heat resistance is easily exhibited when sintered. The average particle size (median diameter) is calculated based on the volume of the particles and can be measured by a laser diffraction / scattering method.

[0045] The shape of the base particles is not particularly limited, but examples thereof include spherical, flake (flat) and polyhedral shapes.

[0046] In the composite particles of the present disclosure, the volume ratio of the base particle to the Ag and / or Cu [base particle:Ag and / or Cu] is preferably 99.9:0.1 to 50:50, more preferably 99:1 to 80:20, and even more preferably 99.5:0.5 to 90:10. The composite particles of the present disclosure can be firmly bonded even when the volume ratio of Ag and / or Cu to the base particle is within the above range, and therefore can be efficiently sintered.

[0047] The base particle has a linear expansion coefficient of 8 ppm / K or less, more preferably 7 ppm / K or less, and even more preferably 6 ppm / K or less. A linear expansion coefficient of 8 ppm / K or less makes it easier to exhibit heat resistance. The lower limit is not particularly limited, but may be 1 ppm / K or more. The thermal expansion coefficient can be measured, for example, using a thermomechanical analyzer (apparatus name "TMA-60", manufactured by Shimadzu Corporation).

[0048] (Method for producing composite particles) The composite particles can be produced using a production method including a step of irradiating ultrasonic waves to a composition (A) containing the base particles, a metal compound serving as a raw material for the metal, and a solvent. In the present disclosure, the composition for producing the composite particles may be referred to as "composition (A)."

[0049] The metal may be supported in the form of particles on the base particles, or the amount of metal attached may increase and the metal may be supported in the form of a film on the base particles.

[0050] The metal is preferably Ag and / or Cu, and the base particles are preferably Si, W, SiO ２ Preferably, the base particle is one or more materials selected from the group consisting of Ag, Cr, and Mo. When the metal is Ag, the base particle is Si and / or SiO ２ When the metal is Cu, the base particles are preferably particles made of a raw material selected from the group consisting of W, Cr, and Mo. The Ag, Cu, and base particles are preferably the same as those described in the section on composite particles.

[0051] The temperature of the composition during the ultrasonic irradiation is preferably 20 to 100°C, more preferably 25 to 90°C, and even more preferably 30 to 80°C. The temperature of the composition can be appropriately changed within the above range depending on the specific process. Furthermore, ultrasonic treatment instantaneously generates tiny bubbles called cavitation, which undergo repeated quasi-adiabatic expansion and compression, eventually collapsing. During this process, the cavitation itself reaches extremely high temperatures and pressures, and shock waves and jet streams are also generated during collapse. Therefore, in the method for producing composite particles of the present disclosure, the reduction reaction of the metal compound can occur even when the temperature of the composition is kept relatively low within the above range.

[0052] The irradiation conditions for the ultrasonic irradiation are preferably a frequency in the range of 5 to 1000 kHz, more preferably 20 to 200 kHz. Although the output and irradiation time are affected by the capacity and temperature, the output is preferably 10 to 1000 W, more preferably 20 to 300 W. Furthermore, the irradiation time is preferably in the range of 0.5 to 50 hours.

[0053] Furthermore, the composite particle manufacturing method may include a heat irradiation step in addition to the ultrasonic irradiation step. Examples of heat irradiation methods include those using a laser or microwaves. Specifically, the laser can be generated using an excimer laser device or a YAG laser device, and the microwaves can be generated using a microwave generator with a frequency of 2.45 GHz and an output of approximately 50 to 1500 W. While the heat irradiation step may be performed before the ultrasonic treatment step, it is preferable that the heat irradiation step be performed after the ultrasonic treatment step from the viewpoint of efficiently forming the composite particles.

[0054] Examples of the solvent include water and organic solvents. Examples of the organic solvent include reducing organic solvents and non-reducing organic solvents. Specific examples of the reducing organic solvent include alcohols such as ethanol, methanol, 2-propanol, and 2-ethylhexyl alcohol, aldehydes such as acetaldehyde, and polyols such as glycol. Examples of the non-reducing organic solvent include toluene, hexane, cyclohexane, xylene, and benzene. Of these, water and alcohols are preferred, and water, ethanol, methanol, and 2-propanol are more preferred. Note that only one type of the solvent may be used, or two or more types may be used.

[0055] The viscosity of the solvent is preferably 10 mPa·s or less in order to fully exert the effect of the ultrasonic treatment, and although there is no particular lower limit, it may be 0.1 mPa·s or more.

[0056] The metal compound is a component that serves as a raw material for Ag and Cu in the composite particles. The metal compound is not particularly limited as long as it contains Ag or Cu, but specific examples include metal oxides such as silver oxide and copper oxide, and metal carboxylates such as silver acetate and copper acetate. Only one type of the metal compound may be used, or two or more types may be used.

[0057] The metal compounds may include compounds that are directly added as raw materials as well as compounds that are produced as reaction intermediates.

[0058] The content of the metal compound is preferably 0.05 to 10 mass %, and more preferably 0.1 to 5 mass %, relative to 100 mass % of the total amount of the composition. When the amount of the metal compound added is within the above range, it becomes easier to form metal particles on the surface of the base particle.

[0059] The composition may contain other components in addition to the base particles, the metal compound, and the solvent, such as additives such as a protective agent and a reducing agent.

[0060] The protective agent may be a component that coats the Ag and Cu surfaces. A compound having a functional group with an unshared electron pair and capable of coordinately adsorbing to Ag and Cu can be used as the protective agent. Compounds having a functional group containing a nitrogen atom are particularly preferred because they can coordinately adsorb to the metal surface. Examples of the functional group containing a nitrogen atom include an amine group and an imide group. Only one type of protective agent may be used, or two or more types may be used.

[0061] Specific examples of the protective agent include primary amine compounds such as ethylamine and dodecylamine, secondary amine compounds such as dimethylamine and diethylamine, tertiary amine compounds such as triethylamine, and polymers having a functional group containing a nitrogen atom, such as ethylpolyvinylpyrrolidone.

[0062] The content of the protective agent is preferably 1 to 10 mass %, and more preferably 2 to 5 mass %, relative to the total amount (100 mass %) of the composition. By keeping the amount of the protective agent added within the above range, the amount added relative to Ag and Cu can be sufficient.

[0063] The reducing agent is a component added to reduce the metal compound by ultrasonic treatment and facilitate the formation of Ag and Cu on the base particle. Only one type of reducing agent may be used, or two or more types may be used.

[0064] Specific examples of the reducing agent include lithium aluminum hydroxide, sodium thiosulfate, hydrogen peroxide, hydrogen sulfide, borane, diborane, hydrazine, potassium iodide, and carboxylic acids such as citric acid, oxalic acid, and ascorbic acid. Of these, it is preferable to use carboxylic acids and hydrazine.

[0065] The content of the reducing agent is preferably 1 to 10 mass %, and more preferably 2 to 7 mass %, relative to 100 mass % of the total amount of the composition. When the amount of the protective agent added is within the above range, Ag and Cu can be easily produced from the metal compound.

[0066] After synthesizing the composite particles using the above method, they can be separated and purified by known or conventional methods to produce composite particles. The composite particles produced in this manner can be produced safely and at low cost because they use only relatively low-toxicity raw materials and can be produced at low temperatures. Furthermore, ultrasonic treatment can create a localized high-energy environment, which causes decomposition and reduction reactions in the metal compounds while simultaneously precipitating Ag and / or Cu on the surface of the base particle, thereby producing composite particles in which Ag and / or Cu are present at a high density on the surface of the base particle.

[0067] Furthermore, when an attempt is made to physically support Ag and / or Cu on the surface of the base particle using a ball mill or the like, an excessive amount of Ag and / or Cu is supported, and the above-mentioned particle agglomerates are likely to be formed, resulting in poor heat resistance. On the other hand, in the above-mentioned method for producing composite particles, Ag and / or Cu are precipitated on the surface of the base particle, so that an appropriate amount of Ag and / or Cu can be supported, making it easier to exhibit heat resistance.

[0068] (Particles containing Ag and / or Cu other than the composite particles) The composition also contains particles (other particles) containing Ag and / or Cu other than the composite particles. Among these, Ag particles or Cu particles are preferred as the other particles because they can be firmly bonded to the Ag or Cu supported on the base particles in the composite particles. In particular, Ag particles are preferred when the composite particles support Ag, and Cu particles are preferred when the composite particles support Cu.

[0069] The volume average particle size (median diameter) of the other particles is preferably 0.1 to 100 μm, more preferably 0.3 to 50 μm, and even more preferably 0.5 to 10 μm. A volume average particle size of 0.1 μm or more makes handling easier. A volume average particle size of 100 μm or less makes it easier to demonstrate bonding reliability.

[0070] The shape of the other particles is not particularly limited, but examples thereof include spherical, flake (flat), polyhedral, etc. Particles of the same shape may be used alone, or particles of different shapes may be used in combination. Among these, spherical particles are preferred for proper dispersion in the alloy paste.

[0071] The content of the other particles is preferably 5 to 2000 parts by mass, more preferably 10 to 1000 parts by mass, even more preferably 20 to 500 parts by mass, and particularly preferably 40 to 400 parts by mass, relative to 100 parts by mass of the composite particles. When the content of the other particles is 5 parts by mass or more, the other particles can be sufficiently bonded to the composite particles during sinter bonding, and when the content is 2000 parts by mass or less, the linear expansion coefficient can be easily reduced.

[0072] (Organic substance) The composition contains an organic substance. Examples of the organic substance include reducing organic substances, basic compounds, coordinating organic compounds other than the compounds corresponding to the basic compounds, resins, organic solvents, etc. Only one type of the organic substance may be used, or two or more types may be used.

[0073] <Reducing Organic Substance> Examples of the reducing organic substance include alcohols (lower alcohols such as ethanol, higher alcohols such as palmitol) other than those exemplified as organic solvents described below, aldehydes (formaldehyde, acetaldehyde, cyclic trimers and tetramers of these aldehydes), amino acids, organic acids (carboxylic acids, etc.), aromatic compounds (polyphenols, phenolic acid compounds, etc.). Among these, organic acids (carboxylic acids, etc.) and aromatic compounds are preferred because they exhibit acidity, and carboxylic acids are more preferred because they are easy to handle at room temperature and not highly toxic. These may be used alone or in combination of two or more.

[0074] Examples of the carboxylic acid include formic acid, acetic acid, lactic acid, propionic acid, acrylic acid, malic acid, n-hexanoic acid, succinic acid, n-octanoic acid, tartaric acid, oxalic acid, and malonic acid. Among these, formic acid, oxalic acid, and malonic acid are preferred because they are excellent in reducing properties and can easily produce a sintered body having excellent electrical conductivity.

[0075] The reducing organic substance preferably contains formic acid or malonic acid from the viewpoint of excellent reducibility and void suppression, and further preferably contains, together with formic acid, a compound having a boiling point higher than that of formic acid (particularly, a compound having a boiling point higher than that of the coordinating organic compound) from the viewpoint of exhibiting reducing properties over a wide temperature range.

[0076] When formic acid is contained as the reducing organic substance, the content of formic acid is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, relative to the total amount (100% by mass) of the reducing organic substances. When another reducing organic substance other than formic acid (e.g., a compound having a boiling point higher than that of formic acid) is contained together with formic acid, the content of the other reducing organic substance is preferably 0.1 molar parts or less, more preferably 0.05 molar parts or less, relative to 1 molar part of formic acid.

[0077] The content of the reducing organic substance is preferably 5% by mass or less (for example, 0.1 to 5% by mass) relative to the total amount (100% by mass) of the composition, more preferably 0.1 to 4.0% by mass, even more preferably 0.2 to 3.7% by mass, and particularly preferably 0.3 to 3.5% by mass.

[0078] <Basic Compound> The basic compound is not particularly limited as long as it functions as a base and realizes the effects of the present disclosure, and specific examples include nitrogen-containing compounds such as ammonia, amine compounds, and phosphorus-containing compounds such as phosphines and phosphate esters. Among these, nitrogen-containing compounds represented by the following formula (1) are preferred because they make it easier to obtain a sintered body with excellent electrical conductivity. In formula (1), R ａ ~R ｃare the same or different and represent a hydrogen atom or a hydrocarbon group which may have a substituent. The substituent may be the same or different and is at least one group selected from an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, and a hydroxyl group. ａ ~R ｃ are not hydrogen atoms at the same time. A double line including a dashed line represents a single bond or a double bond. In the case of a double bond, R ｃ does not exist. ａ ~R ｃ Any two of may be bonded to each other to form a ring together with the adjacent nitrogen atom.

[0079] R ａ ~R ｃ Examples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Among these, an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are preferred, and an aliphatic hydrocarbon group is more preferred.

[0080] Examples of the aliphatic hydrocarbon group include a linear or branched alkyl group, a linear or branched alkenyl group, a linear or branched alkynyl group, and a linear or branched alkylidene group, and among these, a linear or branched alkyl group is preferred.

[0081] The linear or branched alkyl group is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, or a branched alkyl group having preferably 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Examples of the linear or branched alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a decyl group, a dodecyl group, a tetradecyl group, an octadecyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and a 2-ethylhexyl group.

[0082] The linear or branched alkenyl group is preferably a linear alkenyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkenyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Examples thereof include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 1-hexenyl group, a 3-hexenyl group, a 5-hexenyl group, a 1-heptenyl group, a 1-octenyl group, a 1-nonenyl group, a 1-decenyl group, an isopropenyl group, a 2-methyl-1-propenyl group, a methallyl group, a 3-methyl-2-butenyl group, and a 4-methyl-3-pentenyl group.

[0083] The linear or branched alkynyl group is preferably a linear alkynyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkynyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Examples of the linear or branched alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a 1-pentynyl group, a 2-pentynyl group, a 3-pentynyl group, a 4-pentynyl group, a 1-hexynyl group, a 2-hexynyl group, a 3-hexynyl group, a 4-hexynyl group, a 5-hexynyl group, a 1-heptynyl group, a 1-octynyl group, a 1-nonynyl group, a 1-decynyl group, a trimethylsilylethynyl group, and a triethylsilylethynyl group.

[0084] The linear or branched alkylidene group is preferably a linear alkylidene group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkylidene group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Examples of the linear or branched alkylidene group include a methylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a sec-butylidene group, a pentylidene group, an isopentylidene group, an octylidene group, and an isooctylidene group.

[0085] Examples of the alicyclic hydrocarbon group include a cycloalkyl group and a cycloalkenyl group.

[0086] The cycloalkyl group is preferably a cycloalkyl group having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group.

[0087] The cycloalkenyl group is preferably a cycloalkenyl group having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms, and examples thereof include a cyclopentenyl group and a cyclohexenyl group.

[0088] The aromatic hydrocarbon group is preferably an aryl group having 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 6 to 10 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.

[0089] In formula (1), the double line including the dashed line represents a single bond or a double bond. When the double line including the dashed line is a double bond, R ｃ does not exist, and R in formula (1) ａ and R ｂ The nitrogen atom to which is bonded represents an imino group or an N-substituted imino group.

[0090] R ａ ~R ｃ The total number of amino groups, N-substituted amino groups and N,N-substituted amino groups that may be contained in the alkyl group is preferably 0 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0091] R ａ ~R ｃ The total number of imino groups and N-substituted imino groups that may be contained in the alkyl group is preferably 0 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0092] R ａ ~R ｃ The total number of hydroxyl groups that may be possessed by is preferably 0 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0093] The substituents of the N-substituted amino group, N,N-substituted amino group, and N-substituted imino group are the same as those of the above R ａ ~R ｃ The hydrocarbon groups are the same as those described above.

[0094] R ａ ~R ｃ Any two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom. Examples of the ring formed include a pyrrolidine ring, a pyrroline ring, a piperidine ring, a pyrrole ring, an imidazolidine ring, an imidazole ring, a piperazine ring, an imidazolidine ring, a pyridine ring, a diazine ring, and a triazine ring.

[0095] R ａ ~R ｃ The hydrocarbon group in the above formula (1) may have a substituent other than an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, or a hydroxyl group. Examples of such a substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an oxo group, a substituted oxy group (an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an aralkyloxy group having 7 to 16 carbon atoms, an acyloxy group having 1 to 4 carbon atoms, etc.), a carboxyl group, a substituted oxycarbonyl group (an alkoxycarbonyl group having 1 to 4 carbon atoms, an aryloxycarbonyl group having 6 to 10 carbon atoms, an aralkyloxycarbonyl group having 7 to 16 carbon atoms, etc.), a cyano group, a nitro group, a sulfo group, a mercapto group, and a heterocyclic group.

[0096] Specific examples of the basic compound represented by formula (1) include, for example, R ａ ~R ｃ an alkylamine in which at least one of R in formula (1) is a linear or branched alkyl group; ａ , R ｂ are independently a hydrogen atom or a linear or branched alkyl group, and R ｃ is a linear or branched alkyl group having one hydroxyl group; ａ is a hydrogen atom or a linear or branched alkyl group, and R ｂ and R ｃare the same or different and are linear or branched alkyl groups each having one hydroxyl group; ａ ~R ｃ are the same or different and are a linear or branched alkyl group having one hydroxyl group; ａ , R ｂ are the same or different and are a hydrogen atom or a linear or branched alkyl group, and R ｃ an aminoalkanediol in which R in formula (1) is a linear or branched alkyl group having two hydroxyl groups; ａ ~R ｃ a diamine having a total of one amino group; ａ ~R ｃ a triamine having a total of two amino groups; R in formula (1) ａ ~R ｃ a diaminoalkanol having a total of one amino group and a total of one hydroxyl group; R in formula (1) ａ ~R ｃ an imidazole compound in which a ring is formed by incorporating nitrogen atoms of the imino groups, the total number of which is 1; ａ , R ｂ is bonded to an imino group, and a ring is formed containing the imino group (such as a pyridine-based compound, a diazine-based compound, or a triazine-based compound).

[0097] Examples of the alkylamine include methylamine, ethylamine, propylamine, butylamine, pentylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, piperidine, trimethylamine, triethylamine, dimethyldecylamine, dimethyldodecylamine, 4-dimethylaminopyridine, 2-aminopyrazine, 2-aminopyrimidine, 3-aminopyridazine, 2-aminotriazine, diazabicyclononene, and diazabicycloundecene.

[0098] Examples of the monoalkanolamine include 2-aminoethanol, 3-aminopropanol, 1-amino-2-propanol, 1-amino-2-methyl-2-propanol, 2-amino-2-methyl-1-propanol, 4-amino-1-butanol, 6-amino-1-hexanol, 10-amino-1-decanol, 12-amino-1-dodecanol, N-methyl-2-aminoethanol, N-ethyl-2-aminoethanol, N-propyl-2-aminoethanol, 2-dimethylaminoethanol, 6-diethylaminohexanol, 1-(2-hydroxyethyl)pyrrolidine, 2-(hydroxymethyl)pyrrolidine, 2-(2-hydroxyethyl)-1-methylpyrrolidine, 1-piperidineethanol, and 1-ethanol-4-propanolpiperidine.

[0099] Examples of the dialkanolamine include diethanolamine, di-n-propanolamine, diisopropanolamine, di-n-butanolamine, diisobutanolamine, and N-methyldiethanolamine.

[0100] Examples of the trialkanolamine include triethanolamine, tri-n-propanolamine, triisopropanolamine, tri-n-butanolamine, and triisobutanolamine.

[0101] Examples of the aminoalkanediol include 1-amino-2,3-propanediol, 4-amino-1,2-butanediol, 4-amino-1,3-butanediol, 2-amino-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 1-methylamino-2,3-propanediol, 1-ethylamino-2,3-propanediol, 1-propylamino-2,3-propanediol, 1-butylamino-2,3-propanediol, 3-dimethylamino-1,2-propanediol, and 2-diethylamino-1,3-propanediol.

[0102] Examples of the diamine include 1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,5-diamino-2-methylpentane, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyl-1,3-propanediamine, N,N'-diethyl-1,3-propanediamine, N,N'-dimethyl-1,4-butanediamine, and N,N'-diethyl-1,4-butanediamine. Examples thereof include hexanediamine, N,N'-dimethyl-1,6-hexanediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, piperazine, N-methylpiperazine, N-ethylpiperazine, N,N'-dimethylpiperazine, and homopiperazine.

[0103] Examples of the triamine include diethylenetriamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N',N",N"-pentakis(2-hydroxypropyl)diethylenetriamine, 3,3'-diaminodipropylamine, N-(3-aminopropyl)-N-methyl-1,3-propanediamine, N'-[3-(dimethylamino)propyl]-N,N-dimethyl-1,3-propanediamine, 2,6,10-trimethyl-2,6,10-triazaundecane, N-(2-aminoethyl)piperazine, 1,4,7-triazacyclononane, N,N,N',N",N"-pentakis(2-hydroxypropyl)diethylenetriamine, 1-(2-aminoethyl)-4-methylpiperazine, and 1-(2-dimethylaminoethyl)-4-methylpiperazine.

[0104] Examples of the diaminoalkanol include 1,3-diaminopropan-2-ol, 2-(2-aminoethylamino)ethanol, 2-(2-aminopropylamino)ethanol, 2-(2-aminoethylmethylamino)ethanol, 1-(2-hydroxyethyl)piperazine, 4-methylpiperazine-1-ethanol, and 1,4-bis(2-hydroxyethyl)piperazine.

[0105] Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N-propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, and 2-hydroxybenzimidazole.

[0106] Examples of the nitrogen-containing aromatic compound include pyridine, α-picoline, β-picoline, γ-picoline, 2,6-lutidine, 2,3-lutidine, pyrazine, 2-hydroxypyrazine, pyrimidine, 2-hydroxypyrimidine, 4-hydroxypyrimidine, pyridazine, 3-hydroxypyridazine, 4-hydroxypyridazine, triazine, and 2-hydroxytriazine.

[0107] The basic compound contained in the composition is preferably a chelating basic compound having an ethylenediamine structure or an ethanolamine structure in its molecular structure, since it is easy to stabilize metal ions by chelating coordination. The amino group in the structure may be any of primary, secondary, and tertiary amino groups, but is preferably a tertiary amino group from the viewpoint of suppressing side reactions between the basic compound and reducing organic substances.

[0108] The basic compound preferably contains an alkylamine having at least one linear alkyl group having 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms) in addition to the chelating basic compound.

[0109] In the composition, the molar ratio of the basic groups of the basic compound to the acidic groups of the reducing organic material (basic groups / acidic groups) is 0.4 or more, preferably 0.5 or more, more preferably 0.6 or more, even more preferably 1.0 or more, and particularly preferably 1.6 or more. If the molar ratio is less than 0.4, the reaction of the acidic groups of the reducing organic material with the metal may proceed, causing the composition (particularly the paste) to become an aggregated solid and unable to maintain its paste state. The molar ratio is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.7 or less. If the molar ratio is 2.0 or less, the surface of the composite particle of the present disclosure is easily reduced, and the sintered body is likely to have excellent electrical conductivity. The number of moles of acidic groups contained in the reducing organic material is calculated by multiplying the number of moles of the reducing organic material by the number of acidic groups contained in the reducing organic material, and the number of moles of basic groups contained in the basic compound is calculated by multiplying the number of moles of the basic compound by the number of basic groups contained in the basic compound.

[0110] The content of the basic compound in the composition is preferably 0.1 to 10 mass %, more preferably 0.3 to 9 mass %, and even more preferably 0.5 to 8 mass %, relative to the total amount (100 mass %) of the composition.

[0111] <Coordinating Organic Compound> The coordinating organic compound is a compound that coordinates to the metal surface of the composite particle of the present disclosure, and is a compound excluding compounds that fall under the category of the basic compound. The coordinating organic compound preferably has a boiling point higher than that of at least one of the reducing organic substances. In this case, the coordinating organic compound remains more than the reducing organic substance during firing, and is more likely to suppress contact between the reducing organic substance and the active metal surface, thereby suppressing decomposition of the reducing organic substance.

[0112] Examples of the coordinating organic compound include at least one compound selected from the group consisting of compounds having a carboxyl group, compounds having a ketone group (e.g., diketones such as acetylacetone, β-ketoesters, etc.), compounds having a hydroxyl group, compounds having a sulfo group, and compounds having a thiol group.

[0113] The compound having a carboxyl group is preferably a monovalent or divalent carboxylic acid, and more preferably a monovalent carboxylic acid.

[0114] The carboxylic acid may be the same as the carboxylic acid described above for the reducing organic substance. Furthermore, because of their easy availability, low toxicity, and low odor, they may be carboxylic acids having 2 to 15 carbon atoms (preferably 5 to 12, and more preferably 8 to 10). Specific examples include acetic acid (boiling point 118°C), lactic acid (boiling point 122°C), propionic acid (boiling point 141°C), acrylic acid (boiling point 141°C), malic acid (boiling point 167°C), pentanoic acid (boiling point 186°C), n-hexanoic acid (boiling point 205°C), heptanoic acid (boiling point 223°C), 2-ethylhexanoic acid (boiling point 228°C), succinic acid (boiling point 235°C), n-octanoic acid (boiling point 237°C), nonanoic acid (boiling point 254°C), decanoic acid (boiling point 269°C), dodecanoic acid (boiling point 299°C), tartaric acid (boiling point 275°C), and oxalic acid (boiling point 365°C). Since carboxylic acids function as both reducing organic substances and coordinating organic compounds, when using carboxylic acids as coordinating organic compounds, one carboxylic acid having the lowest boiling point may be used in combination with another carboxylic acid having a higher boiling point than the one carboxylic acid. In this case, the carboxylic acid with the relatively high boiling point acts primarily as a protecting agent, and the carboxylic acid with the relatively low boiling point acts as a reducing agent.

[0115] The boiling point of the carboxylic acid at normal pressure is preferably above 110°C, more preferably 150°C or higher, and even more preferably 200°C or higher, because the carboxylic acid is less likely to volatilize than formic acid (boiling point 101°C).

[0116] In the composition, the ratio of the number of moles of the coordinating functional groups contained in the coordinating organic compound to the number of moles of the acidic groups contained in the reducing organic substance (coordinating functional groups / acidic groups) is preferably 0.05 to 1.20, more preferably 0.40 to 1.10, and even more preferably 0.50 to 0.70. When the molar ratio is 0.05 or more, precipitation of small-diameter metal particles is easily obtained, and when it is 1.20 or less, the coordinating organic compound is less likely to remain after firing.

[0117] In the composition, the molar ratio of the number of moles of the coordinating functional group contained in the coordinating organic compound to the basic group of the basic compound (coordinating functional group / basic compound) is preferably 0.10 to 1.00, more preferably 0.15 to 0.75, and even more preferably 0.20 to 0.60. When the molar ratio is 0.10 or more, precipitation of small-diameter metal particles is easily obtained, and when it is 1.00 or less, the coordinating organic compound is less likely to remain after firing.

[0118] The content of the coordinating organic compound in the composition is preferably 0.1 to 10 mass %, more preferably 0.2 to 9 mass %, and even more preferably 0.3 to 8 mass %, relative to the total amount (100 mass %) of the composition.

[0119] <Resin> Examples of the resin include thermoplastic resins (polyester-based resins, polyamide-based resins, polyurethane-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic resins, styrene-based resins, halogen-containing vinyl-based resins, polyvinyl acetal-based resins, cellulose-based resins (ethyl cellulose resins, alkyl cellulose resins, etc.), thermoplastic silicone resins, etc.), thermosetting resins (epoxy resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, etc.), etc. Among these, thermoplastic resins are preferred because they can relieve internal stress during heating.

[0120] The content of the resin in the composition is preferably 1.0% by mass or less, more preferably 0.05 to 1.0% by mass, and even more preferably 0.1 to 0.9% by mass, relative to the total amount (100% by mass) of the composition.

[0121] <Organic Solvent> The composition may contain an organic solvent to adjust fluidity (viscosity) and operability. The organic solvent preferably contains at least organic solvent (a), organic solvent (b), and organic solvent (c). The organic solvents (a), (b), and (c) are different compounds and satisfy the following formulas (1) to (6). Only one type of organic solvent (a), organic solvent (b), and organic solvent (c) may be used, or two or more types may be used. 150°C≦Ta≦250°C (1) 150°C≦Tb≦250°C (2) 250°C≦Tc≦350°C (3) δa≧10.0 (4) δc≦9.0 (5) δc≦δb≦δa (6)

[0122] In the formula, Ta to Tc represent the boiling points of the organic solvents (a) to (c), respectively, and δa to δc represent the Hansen solubility parameters of the organic solvents (a) to (c), respectively. In this specification, the Hansen solubility parameter is sometimes referred to as the "SP value" and abbreviated as "δ."

[0123] The organic solvents (a) to (c) may be any solvents that dissolve uniformly and become liquid when mixed in the blending ratio used in the composition, and each of them may be liquid or solid at room temperature.

[0124] The organic solvent (a) at least satisfies formula (1). That is, the boiling point Ta of the organic solvent (a) satisfies 150° C.≦Ta≦250° C., preferably 150° C.<Ta<250° C., more preferably 155° C.≦Ta≦220° C., and even more preferably 160° C.≦Ta≦200° C. By using an organic solvent (a) having a boiling point within the above range, the organic solvent is easily volatilized during sintering, and a sintered body can be easily formed.

[0125] The organic solvent (a) at least satisfies formula (4) [δa≧10.0]. The SP value δa of the organic solvent (a) is 10.0 or more, preferably 10.3 or more, and more preferably 10.4 or more, within the range satisfying formula (6). When the δa is 10.0 or more, the composite particles of the present disclosure have excellent dispersibility and are less likely to separate from the metal particles and the organic solvent. The δa of the organic solvent (a) may be, for example, 16.0 or less, or 15.0 or less.

[0126] Examples of the organic solvent (a) include alcohol solvents, urea-based solvents, and aprotic polar solvents. Examples of the alcohol solvent include compounds having one or more hydroxy groups, and among these, tertiary alcohols and ether alcohols are preferred. The alcohol solvent may have two or more hydroxy groups. Examples of the ether alcohol include compounds having an ether bond and a hydroxy group, such as (poly)alkylene glycol monoalkyl ethers and alkoxy-substituted alcohols.

[0127] Specific examples of the organic solvent (a) include pinacol (δ 10.7, boiling point 172°C), tetramethylurea (δ 10.6, boiling point 177°C), 3-methoxybutanol (δ 10.6, boiling point 161°C), 1-methylcyclohexanol (δ 10.4, boiling point 155°C), and methyl carbitol (diethylene glycol monomethyl ether) (δ 10.7, boiling point 193°C).

[0128] The organic solvent (b) at least satisfies formula (2). That is, the boiling point Tb of the organic solvent (b) satisfies 150°C ≦ Tb ≦ 250°C, preferably 150°C < Tb < 250°C, more preferably 180°C ≦ Tb ≦ 248°C, and even more preferably 200°C ≦ Tb ≦ 245°C. By using an organic solvent (b) having a boiling point within the above range, the organic solvent is easily volatilized during sintering, making it easy to form a sintered body. Furthermore, by using an organic solvent (b) having a boiling point of 250°C or less, it is possible to suppress the generation of voids during sintering.

[0129] The organic solvent (b) at least satisfies formula (6). The SP value δb of the organic solvent (b) is preferably 8.0 to 12.0, more preferably 8.5 to 11.0, and even more preferably 9.0 to 10.5, within the range that satisfies formula (6). When δb is within the above range, the compatibility of the organic solvent (a) and the organic solvent (c) is improved, they are less likely to separate, and the continuous ejection stability and storage stability tend to be more excellent.

[0130] Examples of the organic solvent (b) include alcohol solvents, ester solvents, ketone solvents, and amine-based solvents. Examples of the alcohol solvent include solvent compounds having one or more hydroxy groups, and among these, tertiary alcohols, ether alcohols, and ester alcohols are preferred. The ether alcohol is a compound having an ether bond and a hydroxy group, such as a (poly)alkylene glycol monoalkyl ether or an alkoxy group-substituted alcohol. The ester alcohol is a compound having an ester bond and a hydroxy group, such as a (poly)alkylene glycol monoalkyl ether monoester. Examples of the ester solvent include diacetates of diols such as (poly)alkylene glycols. Examples of the ketone solvent include cyclic ketones. Examples of the amine-based solvent include alkylamines.

[0131] The organic solvent (b) is selected on the premise that it satisfies the formula (6) in relation to the organic solvents (a) and (c). Specific examples of the organic solvent (b) include d-camphor (δ 10.4, boiling point 204°C), 1-heptanol (δ 10.0, boiling point 177°C), butyl carbitol (diethylene glycol monobutyl ether) (δ 10.2, boiling point 231°C), ethyl carbitol (diethylene glycol monoethyl ether) (δ 10.5, boiling point 196°C), tripropylene glycol monomethyl ether (δ 9.4, boiling point 243°C), α-terpineol (δ 9 .3, boiling point 220°C), dihydroterpineol (δ 9.0, boiling point 210°C), 1,3-butanediol diacetate (δ 9.2, boiling point 232°C), propylene glycol diacetate (δ 9.3, boiling point 190°C), butyl carbitol acetate (δ 9.0, boiling point 247°C), dipropylene glycol butyl ether (δ 9.2, boiling point 230°C), isophorone (δ 9.5, boiling point 213°C), 1-decanol (δ 9.6, boiling point 230°C), propylene glycol monobutyl ether (δ 9.0, boiling point 170°C), 1-nonanol (δ 9.8, boiling point 214°C), etc. may be used.

[0132] The boiling point Tb of the organic solvent (b) is preferably higher than the boiling point Ta of the organic solvent (a), i.e., Tb > Ta. The temperature difference between Tb and Ta [Tb - Ta] is preferably 2°C or more, more preferably 5°C or more, and even more preferably 10°C or more. When the temperature difference is 2°C or more, the generation of voids during sintering can be further suppressed.

[0133] The organic solvent (c) at least satisfies formula (3). That is, the boiling point Tc of the organic solvent (c) satisfies 250° C.≦Tc≦350° C., preferably 250° C.<Tc<350° C., more preferably 250° C.<Tc≦320° C., and even more preferably 250° C.<Tc≦300° C. By using an organic solvent (c) having a boiling point within the above range, rapid volatilization of the organic solvents (a) and (b) during sintering can be suppressed, and the generation of voids can be suppressed.

[0134] The organic solvent (c) at least satisfies formula (5) [δc≦9.0]. The SP value δc of the organic solvent (c) is 9.0 or less, preferably 8.7 or less, and more preferably 8.5 or less. By making the δc 9.0 or less, it is possible to suppress the generation of voids during sintering. The δc of the organic solvent (c) is, for example, 6.0 or more, and may be 7.0 or more.

[0135] Examples of the organic solvent (c) include ether solvents, alkane solvents, and ester solvents. Examples of the ether solvent include (poly)alkylene glycol dialkyl ethers. Examples of the alkane solvent include alkanes having 14 or more carbon atoms (e.g., 14 to 20 carbon atoms). Examples of the ester solvent include esters of (poly)alkylene glycol alkyl ethers and fatty acids.

[0136] Specific examples of the organic solvent (c) include dibutyl carbitol (diethylene glycol dibutyl ether) (δ 8.3, boiling point 255°C), tetradecane (δ 7.9, boiling point 254°C), and hexadecane (δ 8.0, boiling point 287°C).

[0137] The boiling point Tc of the organic solvent (c) is preferably higher than the boiling point Tb of the organic solvent (b), i.e., Tc > Tb. The temperature difference between Tc and Tb [Tc - Tb] is preferably 2°C or more, more preferably 6°C or more, and even more preferably 10°C or more. When the temperature difference is 2°C or more, the generation of voids during sintering can be further suppressed.

[0138] The boiling point Tc of the organic solvent (c) is preferably higher than the boiling point Ta of the organic solvent (a), i.e., Tc > Ta. The temperature difference between Tc and Ta [Tc - Ta] is preferably 30°C or more, more preferably 50°C or more, and even more preferably 60°C or more. When the temperature difference is 30°C or more, the generation of voids during sintering can be further suppressed.

[0139] The SP value δa of organic solvent (a), the SP value δb of organic solvent (b), and the SP value δc of organic solvent (c) satisfy the relationship of the above formula (6) [δc≦δb≦δa]. In particular, it is preferable that δb is higher than δc, i.e., δc<δb is satisfied. It is also preferable that δa is higher than δb, i.e., δb<δa is satisfied.

[0140] The difference between δb and δc [δb - δc] is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more. When the difference is 0.1 or more, the dispersibility of the metal particles is superior and the continuous ejection stability is superior. The difference is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.3 or less. When the difference is 2.0 or less, the composite particles of the present disclosure and the organic solvent are less likely to separate, and the continuous ejection stability and storage stability are superior.

[0141] The difference between δa and δb [δa-δb] is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more. When the difference is 0.1 or more, the dispersibility of the metal particles is superior and the continuous ejection stability is superior. The difference is preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.8 or less. When the difference is 2.5 or less, the metal particles and the organic solvent are less likely to separate, and the continuous ejection stability and storage stability are superior.

[0142] The difference between δa and δc, [δa - δc], is 1.0 or more, preferably 1.5 or more, and more preferably 2.0 or more, based on formulas (4) and (5). When the difference is 1.0 or more, the generation of voids during sintering can be further suppressed. The difference is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. When the difference is 5.0 or less, the composite particles of the present disclosure and the organic solvent are less likely to separate, resulting in better continuous discharge stability and storage stability.

[0143] The ratio of organic solvent (a) to the total amount (100 mass%) of organic solvent (a), organic solvent (b), and organic solvent (c) [organic solvent (a) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, and even more preferably 15 to 50 mass%. When the ratio is within the above range, the organic solvent is easily volatilized during sintering, a sintered body can be easily formed, and dispersibility with the composite particles of the present disclosure is superior.

[0144] The ratio of organic solvent (b) to the total amount of organic solvent (a), organic solvent (b), and organic solvent (c) (100% by mass) [organic solvent (b) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, and even more preferably 15 to 50% by mass. When the ratio is within the above range, the compatibility of the organic solvents is excellent, and the continuous ejection stability and storage stability are further improved.

[0145] The proportion of organic solvent (c) relative to the total mass of organic solvents (a), (b), and (c) (100 mass%) [organic solvent (c) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, and even more preferably 15 to 50 mass%. When this proportion is within the above range, the generation of voids during sintering can be further suppressed.

[0146] The content of organic solvent (c) relative to 100 parts by mass of organic solvent (a) is preferably 20 to 400 parts by mass, more preferably 30 to 300 parts by mass, and even more preferably 50 to 200 parts by mass. When the content is within the above range, the blending amounts of organic solvent (a) and organic solvent (c) are well balanced, resulting in better void suppression during sintering and better dispersibility with the composite particles of the present disclosure.

[0147] The content of organic solvent (b) relative to 100 parts by mass of the total amount of organic solvent (a) and organic solvent (c) is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, and even more preferably 40 to 100 parts by mass. When the content is within the above range, the compatibility between organic solvent (a) and organic solvent (c) is further improved, and the continuous ejection stability and low-temperature storage stability are further improved.

[0148] The organic solvent may contain other solvents (organic solvents) in addition to organic solvents (a), (b), and (c). The total content of organic solvents (a), (b), and (c) in the organic solvent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to 100% by mass of the total amount of the organic solvents. When the content is 50% by mass or more, the dispersibility with the composite particles of the present disclosure and the compatibility with each organic solvent are excellent, and the continuous discharge stability, storage stability, and void formation suppression during sintering are excellent.

[0149] When organic solvent (a), organic solvent (b), and organic solvent (c) are mixed in the blending ratio used in the composition, it is preferable that organic solvent (a), organic solvent (b), and organic solvent (c) dissolve uniformly at room temperature and do not undergo phase separation. Furthermore, it is preferable that organic solvent (a), organic solvent (b), and organic solvent (c) dissolve uniformly at room temperature and do not undergo phase separation in the composition. In particular, it is preferable that phase separation does not occur at 22 to 28°C (preferably 10 to 30°C, more preferably 0 to 35°C).

[0150] In the composition, the content of the organic solvent is preferably 0.5 to 30 parts by mass, more preferably 2 to 20 parts by mass, per 100 parts by mass of the total of the composite particles of the present disclosure and the organic substance other than the organic solvent.

[0151] [Method for Producing Composition] One embodiment of the present disclosure can include a method for producing a composition comprising composite particles in which a metal is supported on a base particle and a solvent, the method comprising: irradiating, with ultrasonic waves, composition (A) comprising the base particle, a metal compound serving as a raw material for the metal, and a solvent, to produce the composite particle, thereby obtaining a composition having a particle sintering rate of 30% or more, as represented by the following formula (1): Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The above composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

[0152] The method for producing the composition is not particularly limited, but the composition can be produced, for example, by premixing the composite particles and components other than the solvent, then adding the solvent by a known or conventional method, and mixing. The composite particles can also be produced by the above-mentioned production method.

[0153] (Sintered body) A sintered body can be produced by sintering the composition. The temperature of the heat treatment during sintering is preferably 150 to 400°C, more preferably 180 to 350°C, and even more preferably 200 to 300°C. By setting the heat treatment temperature to 400°C or less, the influence of the heat treatment on the substrate and non-bonded objects can be suppressed. The sintering time is preferably, for example, 10 seconds to 2 hours, more preferably 3 minutes to 1 hour. Furthermore, the sintered body may be sintered without pressure, or may be sintered with pressure. When pressure is applied, the pressure during pressing is, for example, 0.3 to 40 MPa.

[0154] The sintered body produced as described above can be used, for example, as a bonded body for bonding a substrate and an object to be bonded.

[0155] (Jointed body) The joined body can be produced by applying the composite particles of the present disclosure or the composition to a substrate by a printing method (specifically, a dispenser printing method, a mask printing method, a screen printing method, an inkjet printing method, etc.), placing an object to be joined on the coating layer, and then sintering the applied layer. The sintering conditions can be the same as those for producing the sintered body.

[0156] The thickness of the bonded body is preferably 5 to 500 μm, more preferably 20 to 300 μm, and even more preferably 40 to 150 μm.

[0157] Examples of the substrate include metal substrates such as copper substrates, ceramic substrates, metal-laminated ceramic substrates, SiC substrates, gallium nitride substrates, glass epoxy substrates, BT resin substrates, glass substrates, and resin substrates.

[0158] Examples of the bonded object include electronic components, heat dissipation substrates, etc. Examples of electronic components include electronic elements (chips, dies) such as semiconductor elements and LED elements, and a specific example of the semiconductor element is a power semiconductor element. Examples of the material of the bonded object include Si (silicon), SiC (silicon carbide), GaN, diamond, etc.

[0159] The bonded body thus produced can be sintered at low temperatures and has excellent heat resistance because the substrate and the non-bonded object are bonded via the composite particles of the present disclosure, which have excellent heat resistance. Furthermore, since the bonded body can be produced by heat treatment at a relatively low temperature, it can be used to bond even common materials.

[0160] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, each configuration and their combination in each embodiment is merely an example, and additions, omissions, and other modifications of configurations are possible as appropriate within the scope of the gist of this disclosure. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims.

[0161] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples.

[0162] Production example 1 Ag ２ 2.2 parts by mass of O powder, 1 part by mass of silicon particles (Si purity > 99.999%, particle size D50 = 0.56 μm) as base particles, and 100 ml of ethanol as a solvent were used. The above raw materials were mixed in a 300 ml Erlenmeyer flask, and ultrasonic irradiation was performed for 24 hours at a temperature of 40 ° C, a frequency of 50 kHz, and an output of 100 W using an ultrasonic generator (trade name "Sonoreactor", manufactured by Honda Electronics Co., Ltd.), to produce Ag-supported silicon particles of Production Example 1. The Ag-supported silicon particles of Production Example 1 carried 10% by volume of Ag relative to 90% by volume of silicon particles. The average particle diameter D50 of the supported Ag was 50 nm.

[0163] Production Example 2: SiO as base particles ２ Ag-supported SiO2 of Production Example 2 was prepared in the same manner as in Production Example 1, except that 1 part by mass of particles (manufactured by Sakai Chemical Industry Co., Ltd., particle size D50 = 0.4 μm) was used. ２ The Ag-supported SiO particles of Production Example 2 were prepared. ２ The particles are SiO ２ 10% by volume of Ag was supported on 90% by volume of the particles, and the average particle diameter D50 of the supported Ag was 100 nm.

[0164] Production Example 3 75 parts by mass of silver flakes (trade name "AgC-239", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) and 25 parts by mass of silicon particles (Si purity >98.9%, particle size D50 = 32.8 μm) were mixed and pulverized using the high-speed three-dimensional motion (strong frictional force motion) of a three-dimensional ball mill (trade name "3D Ball Mill", manufactured by Nagao Systems Co., Ltd.) to obtain Ag and silicon mixed particles of Production Example 3. The Ag and silicon mixed particles of Production Example 3 carried 40% by volume of Ag relative to 60% by volume of silicon particles.

[0165] Example 1 Particles obtained by mixing 70 parts by volume of silver flakes (trade name "AgC-239", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) and 30 parts by volume of the Ag-supported silicon particles of Production Example 1 are referred to as supported mixed particles A. The volume ratio of silicon to Ag in supported mixed particles A is 30:70. Using a solvent with the trade name "Cellul IA" (manufactured by Daicel Corporation), the mixture was added so that the weight ratio of the supported mixed particles A:Cellul IA was 8.2:1.0, and the mixture was manually mixed to prepare a paste-like composition of Example 1.

[0166] Example 2 70 parts by volume of silver flakes (trade name "AgC-239", manufactured by Fukuda Metal Foil and Powder Co., Ltd.) and Ag-supported SiO ２ The particles mixed with 30 parts by volume of the SiO 3 particles are called supported mixed particles B. ２ The volume ratio of the particles to Ag was 30:70. Using a solvent under the trade name "Cellutol IA" (manufactured by Daicel Corporation), the particles were added so that the weight ratio of the supported mixed particles B to Cellutol IA was 10.0:1.0, and the mixture was mixed manually to prepare a paste-like composition of Example 2.

[0167] Comparative Example 1 A mixture of 70 parts by volume of silver flakes (trade name "AgC-239", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) and 30 parts by volume of silicon particles (Si purity >99.999%, particle size D50 = 0.56 μm) is referred to as mixed particles A. Using a solvent "Cellul IA" (manufactured by Daicel Corporation) as the solvent, the mixture was added so that the weight ratio of mixed particles A:Cellul IA was 8.2:1.0, and the mixture was manually mixed to prepare a paste-like composition of Comparative Example 1.

[0168] Comparative Example 2 Particles obtained by mixing 70 parts by volume of silver flakes (trade name "AgC-239", manufactured by Fukuda Metal Foil & Powder Co., Ltd.) and 30 parts by volume of the Ag and silicon mixed particles of Production Example 3 are referred to as mixed particles B. The volume ratio of silicon to Ag in mixed particles B is 30:70. Using a solvent "Cellul IA" (manufactured by Daicel Corporation), the mixed particles were added so that the weight ratio of mixed particles B:Cellul IA was 8.2:1.0, and the mixture was manually mixed to prepare a paste-like composition of Comparative Example 2.

[0169] In the present disclosure, the ratio of solvent to powder when preparing the composition varies depending on the particle size and shape of the powder, and therefore the amount of solvent varies for different types of particles. However, the difference in the amount of solvent does not affect the evaluation of sinterability.

[0170] [Evaluation] The compositions of the Examples and Comparative Examples prepared above were evaluated as follows, and the results are shown in Table 1. Note that the values ​​in Table 1 are given in parts by volume unless otherwise specified.

[0171] (1) Particle Sintering Rate Using the compositions prepared in Examples and Comparative Examples, the compositions were printed on a Cu substrate plated with 2 μm thick Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), and then heated and sintered on a hot plate. Specifically, the Cu substrate was placed on a hot plate set at 100° C., held for 1 minute, then removed from the hot plate, returned to room temperature, and then placed on a hot plate held at 250° C., held for 30 minutes, then removed from the hot plate, and returned to room temperature to prepare sintered bodies of the compositions of Examples and Comparative Examples.

[0172] The cross sections of the sintered pastes of the above Examples and Comparative Examples were observed at a magnification of 20,000 times using an FE-SEM, and visually identifiable particles (silicon particles, Ag-supported silicon particles, Ag-supported SiO ２The number of sintered particles and the number of particles bonded to the bonded object, such as silver flakes or Ag-plated Cu substrates, were measured, and the ratio of sintered particles among particles of 100 nm or more was calculated as the particle sintering rate using the following formula (1), and the results are shown in Table 1. Particle sintering rate = (total number of particles having a length of 100 nm or more in at least one direction in an image taken at 20,000 magnification using an FE-SEM after sintering and bonded to the bonded object) / (total number of particles having a length of 100 nm or more in at least one direction in an image taken at 20,000 magnification using an FE-SEM after sintering) (1)

[0173] (2) Unit Sintering Rate The unit sintering rate was calculated by the method shown in the following formula (2), and the results are shown in Table 1. Unit sintering rate = (particle sintering rate) / (volume ratio of supported Ag and / or Cu to substrate particles) (2)

[0174]

[0175] 2 is an FE-SEM image of a cross section of the sintered body of Example 1. It can be seen that the sintered composite particles 1 are bonded to silver flakes 23, which are particles other than the composite particles. In particular, it can be seen that the Ag particles carried on the surface of the composite particles 1 have the effect of significantly reducing the contact angle with the silver flakes 23, improving the interface formation ability and expanding the silver flakes, so that the composite particles 1 and the silver flakes 23 are bonded over a wide area.

[0176] 3 is an FE-SEM image of a cross section of the sintered body of Example 2. It can be seen that the sintered composite particle 1 is bonded over a wide area to silver flakes 24, which are particles other than the composite particle. Furthermore, although not shown, it can be seen that the sintered composite particle 1 is bonded to an Ag-plated Cu substrate, and it can be seen that the composite particle 1 is not simply a particle coated with Ag, but is a particle that has self-sintering properties similar to Ag nanoparticles and Ag flake particles.

[0177] As can be seen from Figures 2 and 3, the compositions of the examples have a particle sintering rate of 30% or more in the sintered body, and it has been confirmed that they can be sufficiently bonded to the object to be bonded, and that they can be firmly bonded. The compositions contain Ag and / or Cu carried on the base particles, and the base particles do not contain Si, W, SiO ２ It was assumed that the material is particles of one or more raw materials selected from the group consisting of Cr, Cr, and Mo, and can be sintered at low temperatures while exhibiting heat resistance.

[0178] On the other hand, Figure 4 shows an FE-SEM photograph of a cross section of the sintered body of Comparative Example 1. Although there are some areas where the silicon particles 3 and the silver flakes 25 are bonded, bonding between the silicon particles 3 and the silver flakes 25 cannot be confirmed over a wide area, and the ability of the silver flakes 25 to form an interface on the surface of the silicon particles 3 is insufficient. The particle sintering rate was less than 30%, and sufficient bonding was not possible. Similarly, the particle sintering rate of the composition of Comparative Example 2 was less than 30%, and sufficient bonding was not possible.

[0179] Variations of the present disclosure are described below. [Appendix 1] A composition comprising composite particles, an organic substance, and particles other than the composite particles that contain Ag and / or Cu, wherein the composite particles comprise base particles and Ag and / or Cu supported on the base particles, the base particles have a linear expansion coefficient of 8 ppm / K or less, and a particle sintering rate represented by the following formula (1) is 30% or more. Particle sintering rate = (total number of base material particles having a length of 100 nm or more in at least one direction in an image of a cross section of a sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to a bonded object) / (total number of base material particles having a length of 100 nm or more in at least one direction in an image of a cross section of a sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and then placed on a hot plate maintained at 250° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature. [Appendix 2] The composition according to Appendix 1, having a unit sintering rate represented by the following formula (2) of 0.7 or more. Unit sintering rate = (particle sintering rate) / (volume ratio of supported Ag and / or Cu to the volume of base particle) (2) Specifically, (volume ratio of supported Ag and / or Cu to the volume of base particle) is expressed by the following formula (3), where VA is the volume of the base particle and VB is the volume ratio of supported Ag and / or Cu in the composite particle. (volume ratio of supported Ag and / or Cu to the volume of base particle) = VB / (VA + VB) (3) [Appendix 3] When the base particle is made of Si, W, SiO ２, Cr, and Mo. [Appendix 4] The composition according to any one of Appendices 1 to 3, wherein the volume ratio of Ag and / or Cu to all particles contained in the composition is 50 to 95 volume %. [Appendix 5] The composition according to any one of Appendices 1 to 4, wherein the average number of particle agglomerates A described below in an image taken at 1000x magnification using an SEM at any five points in a cross section of the composite particle is 2 or less. Particle agglomerate A: Comprising a plurality of base particles and Ag and / or Cu, wherein the area ratio of the supported Ag and / or Cu is 70 area % or more relative to the base particles, and the diameter of the longest point in the agglomerate is 5 μm or more. [Appendix 6] The composition according to Appendices 5, wherein the number of the base particles contained in the particle agglomerates A is 30% or less relative to the total number of base particles. [Appendix 7] The composition according to any one of Appendices 1 to 6, wherein the composite particle has two or less particle agglomerates B in an image taken at 1000x magnification using an SEM. Particle agglomerate B: comprises a plurality of base particles and Ag and / or Cu, wherein the area ratio of the supported Ag and / or Cu is 70 area % or more relative to the base particles, the voids in the particle agglomerates are 30 area % or less, and the diameter of the longest part in the agglomerates is 5 μm or more. [Appendix 8] The composition according to Appendices 7, wherein the number of base particles contained in the particle agglomerates B is 30% or less relative to the total number of base particles. [Appendix 9] The composition according to any one of Appendices 1 to 8, wherein the Ag and / or Cu are supported on the base particles in the form of uniform Ag particles and / or Cu particles. [Appendix 10] The composition according to any one of Appendices 1 to 8, wherein the Ag and / or Cu are supported on the base particles in the form of a film. [Appendix 11] The composition according to Appendix 9, wherein the Ag content in 100% by mass of the Ag particles is 95% by mass or more. [Appendix 12] The composition according to Appendix 9, wherein the Cu content in 100% by mass of the Cu particles is 95% by mass or more. [Appendix 13] The composition according to any one of Appendices 9 and 11 to 12, wherein the Ag particles and the Cu particles have an average particle size (median size) of 1 nm or more and 10,000 nm or less.[Appendix 14] The composition according to any one of Appendices 9, 11 to 12, wherein the average particle size (median size) of the Ag particles and the Cu particles is 5 nm or more and 1000 nm or less. [Appendix 15] The composition according to any one of Appendices 9, 11 to 12, wherein the average particle size (median size) of the Ag particles and the Cu particles is 10 nm or more and 500 nm or less. [Appendix 16] The composition according to Appendices 10, wherein the Ag and / or the Cu are supported on the base particles in the form of a film, the film having a thickness of 10 nm to 10 μm. [Appendix 17] The composition according to any one of Appendices 1 to 16, wherein the average particle size of the base particles is 0.05 to 50 μm. [Appendix 18] A method for producing a composition containing composite particles in which a metal is supported on a base particle and a solvent, the method comprising: irradiating, with ultrasonic waves, composition (A) containing the base particle, a metal compound serving as a raw material for the metal, and a solvent, in order to produce the composite particle, thereby obtaining a composition having a particle sintering rate represented by the following formula (1) of 30% or more: Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature. [Appendix 19] The method for producing a composition according to Appendix 18, wherein in the step of irradiating with ultrasonic waves, the temperature of the composition (A) is 20 to 100° C. [Appendix 20] The method for producing a composition according to Appendix 18 or 19, wherein in the step of irradiating with ultrasonic waves, the ultrasonic irradiation conditions are a frequency of 5 to 1000 kHz and an output of 10 to 1000 W.[Appendix 21] A method for producing the composition according to any one of Appendices 18 to 20, wherein the solvent comprises water or an alcohol. [Appendix 22] A method for producing the composition according to any one of Appendices 18 to 21, wherein the composition (A) further comprises a reducing agent. [Appendix 23] A method for producing the composition according to any one of Appendices 18 to 22, wherein the composition (A) further comprises a carboxylic acid. [Appendix 24] The base particle is Si, W, or SiO. ２ 25. The method for producing a composition according to any one of Appendices 18 to 24, wherein the metal compound is a particle of a raw material selected from the group consisting of a metal oxide and / or a metal carboxylate.

[0180] 1: Composite particles 2: Object to be bonded 21: Particles other than composite particles 22: Substrate 23, 24, 25: Silver flakes 3: Silicon particles

Claims

1. A composition comprising composite particles, an organic substance, and particles other than the composite particles that contain Ag and / or Cu, wherein the composite particles contain base particles and Ag and / or Cu supported on the base particles, the base particles have a linear expansion coefficient of 8 ppm / K or less, and the particle sintering rate, represented by the following formula (1), is 30% or more. Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

2. The base particles are Si, W, SiO ２ 10. The composition of claim 1, wherein the particles are of a material selected from the group consisting of Fe, Cr, and Mo.

3. The composition according to claim 1 or 2, wherein the volume ratio of Ag and / or Cu to all particles contained in the composition is 50 to 95 volume %.

4. The composition according to claim 1 or 2, wherein the average number of particle agglomerates A described below in an image taken at 1000x magnification using an SEM at any five points on the cross section of the composite particle is 2 or less: Particle agglomerate A: Comprises a plurality of base particles and Ag and / or Cu, the area ratio of the supported Ag and / or Cu to the base particles is 70 area % or more, and the diameter of the longest part in the agglomerate is 5 μm or more.

5. A method for producing a composition comprising composite particles in which a metal is supported on a base particle and a solvent, the method comprising: irradiating ultrasonic waves to composition (A) comprising the base particle, a metal compound serving as a raw material for the metal, and a solvent in order to produce the composite particle; and obtaining a composition having a particle sintering rate of 30% or more, as represented by the following formula (1): Particle sintering rate = (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM and bonded to the object to be bonded) / (the total number of base material particles having a length of 100 nm or more in at least one direction in an image of the cross section of the sintered body after the sintering process described below taken at 20,000 times using an FE-SEM) (1) Sintering process: The composition is printed on a Cu substrate plated with 2 μm of Ag using a metal mask (opening 5 mm, mask thickness 0.15 mm), the Cu substrate is placed on a hot plate maintained at 100 ° C. and held for 1 minute, then removed from the hot plate and returned to room temperature, and the Cu substrate is placed on a hot plate maintained at 250 ° C. and held for 30 minutes, then removed from the hot plate and returned to room temperature.

6. The method for producing a composition according to claim 5, wherein the temperature of the composition (A) is 20 to 100°C in the step of irradiating with ultrasonic waves.

7. The method for producing a composition according to claim 5 or 6, wherein in the step of irradiating with ultrasonic waves, the ultrasonic irradiation conditions are a frequency of 5 to 1000 kHz and an output of 10 to 1000 W.

8. The method for producing the composition according to claim 5 or 6, wherein the solvent comprises water or an alcohol.

9. The method for producing a composition according to claim 5 or 6, wherein the composition (A) further contains a reducing agent.

10. The method for producing a composition according to claim 5 or 6, wherein the composition (A) further contains a carboxylic acid.

11. The base particles are Si, W, SiO ２ 7. The method for producing a composition according to claim 5 or 6, wherein the particles are particles of a raw material selected from the group consisting of Al, Cr, and Mo.

12. A method for producing a composition according to claim 5 or 6, wherein the metal compound is a metal oxide and / or a metal carboxylate.

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