JPWO2019066081A1 - Composite particles and methods for producing them, composite particle compositions, bonding materials and bonding methods, and bonded products. - Google Patents

Abstract

The method for producing the composite particles is as follows: step A) a step of mixing a metal salt and a reducing agent to obtain a metal complexing reaction solution, and step B) heating the metal complexing reaction solution to obtain the metal complexing reaction solution. The average particles include a step of reducing the metal ions in the metal ion to obtain a slurry of the composite particles, and at any timing from the step A to heating the metal complexing reaction solution in the step B. Metal particles or metal oxide particles having a diameter of 0.03 to 50 μm, and an organic metal compound selected from an alkali metal-based organic metal compound or an alkaline earth metal-based organic metal compound are added.

Description

The present invention relates to composite particles suitable for a bonding material and a method for producing the same, a composite particle composition, a bonding material and a bonding method, and a bonded body.

It is known that metal nanoparticles having an average particle diameter of less than 1 μm cause bonding between the particles at a temperature much lower than the melting point of the metal constituting the metal nanoparticles, and after the bonding, they behave in the same manner as bulk metal. There is. Taking advantage of this property, bonding materials using metal nanoparticles such as silver, gold, copper, and nickel are being actively studied for applications that require bonding at low temperatures during processing and withstand high temperature environments. It has been done. (Patent Document 1)

As a typical application, there is a bonding material for joining a semiconductor chip of a power device semiconductor substrate using SiC (silicon carbide) and a mounting substrate. As the characteristics required for the bonding material, high reliability of bonding strength that does not deteriorate in an environment exposed to high temperature and low temperature is required, and in addition, high functionality such as high thermal conductivity is required. ..

Traditionally, in this field, solder materials have been used as bonding materials. Instead of this solder material, bonding materials using various metal nanoparticles such as silver nanoparticles are currently being actively studied. For example, in Patent Document 2, a silver nanoparticle bonding material having a size of submicro to several micrometers is volatilized at 200 ° C. and heated at 300 ° C. or 350 ° C. to obtain a bonding strength of about 20 to 40 MPa. ing.

Further, a bonding material using low-cost copper nanoparticles instead of silver nanoparticles is also disclosed. For example, in Patent Document 3, a bonding material containing copper nanoparticles having a particle size of 1 to 35 nm and copper particles having a particle size of 35 to 1000 nm is pressure-sintered in hydrogen at 400 ° C. for 5 minutes to obtain a high bonding strength of 40 MPa or more. Materials have been proposed.

As described above, the development of metal nanoparticle-based bonding materials (also referred to as "nano-sinter-based bonding materials") is underway, but silver nanoparticles-based bonding materials (silver-sinter-based bonding materials) are expensive, and in addition, cold cycles, etc. When the reliability test is carried out, there are problems of coarsening of voids and brittleness of the joint layer. On the other hand, although the copper fine particle type (copper sinter type) is low in cost, there is a problem that deterioration due to oxidation occurs.

Therefore, the present inventor has studied a nickel (Ni) nanoparticle-based bonding material which is low in cost, is not easily deteriorated by oxidation, and can be expected to have high reliability. For example, in Non-Patent Document 1, a bonding material using 90 nm Ni nanoparticles maintains a bonding strength of 10 MPa or more even after 1000 cycls have passed in a thermal cycle test at −40 ° C. to + 250 ° C., and further cross-sectional observation is performed. Disclosed that it shows high reliability that no cracks are observed.

However, nickel has a thermal conductivity of 90.9 W / m · K, which is lower than that of silver (420 W / m · K) and copper (398 W / m · K), and guarantees driving in the high temperature region. It was expected that the heat dissipation would be further improved, which is an important characteristic.

By the way, metal nanoparticles have characteristics such as a small size, a large surface area, and a large oxidizing action, and thus there is a concern about safety. Therefore, if metal particles having a large particle size can be applied as the metal bonding material, further development of applications is expected, not limited to the metal bonding material.

Further, there is a demand for a bonding material in an application of bonding metal oxides to each other or metal oxides to a metal. A typical method for joining metal oxides is to use a metal brazing material. However, since metals generally have a higher coefficient of thermal expansion than metal oxides, they are used for repeated high-temperature driving and temperature rise and fall. In, the reliability of the bonding interface becomes an issue.

Therefore, it is possible to devise a joint formation by sintering a metal oxide powder. Since the metal oxide powder has a coefficient of thermal expansion almost equal to that of the metal oxide bonded member, the stress generated at the bonding interface is small, and excellent bonding formation can be expected in long-term reliability.

However, since metal oxides often have a lower thermal conductivity than metals, there is a need for a method for increasing the thermal conductivity while maintaining reliability.

Japanese Unexamined Patent Publication No. 2013-12693 Japanese Unexamined Patent Publication No. 2011-236494 Japanese Unexamined Patent Publication No. 2013-91835

Journal of Smart Process Society Vol. 4 No. 4 Pages 190-195

An object of the present invention is to provide composite particles and composite particle compositions having bondability, safety, and thermal conductivity.

The present inventors have solved the above problems with composite particles, which are core-shell type particles, which have both a layer having excellent thermal conductivity and a layer which can be expected to have high reliability, or a composition containing the same. I found that it could be solved.

The method for producing composite particles of the present invention is:
The following steps A and B;
A) A step of mixing a metal salt and a reducing agent to obtain a metal complexing reaction solution,
B) A step of heating the metal complexing reaction solution to reduce metal ions in the metal complexing reaction solution to obtain a slurry of composite particles.
Including
Metal particles or metal oxide particles having an average particle diameter of 0.03 to 50 μm, and an alkali metal at any timing between the step A and the heating of the metal complexing reaction solution in the step B. It is characterized by adding an organometallic compound selected from an organometallic compound or an alkaline earth metal-based organometallic compound.

In the method for producing composite particles of the present invention, the organometallic compound may have nucleophilicity. Further, the organometallic compound may be an organomagnesium halide or an organolithium compound. Further, the metal particles have an atomic number concentration of one or more metals selected from aluminum, titanium, iron, manganese, chromium, nickel, cobalt, zirconium, tin, tungsten, molybdenum, vanadium, copper, silver, gold and platinum. It may contain 50% or more. Further, the metal oxide particles may contain one or more metal oxides selected from alumina, silicon dioxide, zirconia, stabilized zirconia, ceria, doped ceria, lanthanum gallate, and barium cerate as main components. Further, the metal salt may be a silver salt, a nickel salt, a copper salt or a cobalt salt.

Further, the composite particles of the present invention include core layer metal (II) particles or core layer metal oxide (III) particles.
The core layer metal (II) particles or the core layer metal oxide (III) particles are coated, and a metal species different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles is mainly used. The coating layer metal (I) contained as a component
It is a complex particle containing
The content of the alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg or less in the composite particles.

Further, the composite particle composition of the present invention comprises core layer metal (II) particles or core layer metal oxide (III) particles and the core layer metal (II) particles or core layer metal oxide (III) particles. Composite particles that are coated and contain a coating layer metal (I) containing a metal species different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles as a main component. A complex particle composition containing
The content of alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg with respect to the content of the main component element of the coating layer metal (I) in the entire composition. It is characterized by being less than kg.

In the composite particles or composite particle composition of the present invention, the main component of the core layer metal (II) particles may be gold, platinum, silver, nickel, copper or cobalt.

In the composite particles or composite particle composition of the present invention, the main components of the core layer metal oxide (III) particles are alumina, silicon dioxide, zirconia, stabilized zirconia, ceria, doped toceria, lanthanum gallate, and barium serate. It may be.

Further, the composite particle composition of the present invention contains the composite particles and other particles a having an average primary particle diameter of 10 to 150 nm.
It is determined that the metal element having an atomic number concentration of 50% or more in the coating layer of the composite particles and the metal element having an atomic number concentration of 50% or more in the other particles are the same metal element Z1. It is a feature.

Further, the composite particle composition of the present invention contains the composite particles and other particles b having an average primary particle diameter of 0.03 to 50 μm.
The metal element having an atomic number concentration of 50% or more in the coating layer of the composite particles and the metal element having an atomic number concentration of 50% or more in the other particles b are the same metal element Z1. It is characterized by.

Further, the composite particle composition of the present invention contains the composite particles and other particles c having an average primary particle diameter of 0.03 to 50 μm.
It is characterized in that the main component of the core layer of the composite particle and the main component of the other particle c are the same, that is, a composite particle composition.

Further, in the composite particle composition of the present invention, when the core layer of the composite particles is the core layer metal (II) particles, the atomic number concentration of the core layer metal (II) particles is 50% or more. The weight ratio (Y1: Z1) of the metal element Y1 to the metal element Z1 is 95: 5 to 50:50.

Further, in the composite particle composition of the present invention, when the core layer of the composite particles is the core layer metal (II) particles, the metal element Y1 is copper and the metal element Z1 is nickel. Is preferable.

Further, in the composite particle composition of the present invention, when the core layer of the composite particles is the core layer metal oxide (III) particles, the main component W1 of the core layer metal oxide (III) and the metal element The weight ratio of Z1 (W1: Z1) is 90:10 to 10:90.

Further, in the composite particle composition of the present invention, when the core layer of the composite particles is the core layer metal oxide (III) particles, the main component W1 of the core layer metal oxide (III) is yttria-stabilized. It is zirconia, and the metal element Z1 is preferably nickel.

Further, the bonding material of the present invention contains the composite particles and an organic solvent having a boiling point in the range of 100 to 350 ° C., and the content of the organic solvent is in the range of 2 to 40% by weight. It is a feature.

The bonding material of the present invention may further contain an organic binder in the range of 0.05 to 5.0% by weight based on the total amount of particles.

Further, in the joining method of the present invention, the joining material is interposed between the members to be joined and heated to form a joining layer between the members to be joined, and the members to be joined are joined to each other. It is a feature. At this time, a bonding layer may be formed between the members to be bonded by heating at a temperature in the range of 100 ° C. to 500 ° C. in a reducing gas atmosphere.

Further, the joined body of the present invention is characterized in that the first member to be joined and the second member to be joined are joined by the joining material. At this time, in the bonded body, the first member to be bonded may be the first metal layer constituting the semiconductor element, and the second member to be bonded may be the second metal layer.

According to the composite particles, composite particle composition, bonding material and bonding method of the present invention, for example, copper particles were used as the core layer metal (II) particles, and nickel was used as the coating layer metal (I). In this case, it is possible to form an excellent bonding layer having excellent thermal conductivity, which is a feature of the copper particle system, and low cost, high reliability, and bondability, which are the features of the nickel particle system. .. Furthermore, since it is possible to increase the particle size as compared with conventional copper nanoparticles and nickel nanoparticles, it is excellent in safety.
Therefore, for example, it can be applied to a semiconductor module for a power device used in a power conversion device, a power control device, a power supply device, and the like. Specifically, a power semiconductor chip using a so-called "wide-gap semiconductor" such as SiC, GaN, Ga ₂ O ₃ , AlN, or diamond, which requires reliability when driven in a high temperature region of 250 ° C. or higher. It can be suitably used as a bonding material for bonding mounting substrates. It can also be used as a bonding material that requires other heat dissipation properties, such as bonding an LED and an electrode.

Further, for example, when yttria-stabilized zirconia is used as the core layer metal oxide (III) particles in the core layer and nickel is used as the coating layer metal (I), the low thermal expansion that is a feature of yttria-stabilized zirconia is characteristic. It is possible to form an excellent bonding layer that has both a coefficient and a high thermal conductivity as compared with a metal oxide, which is a feature of nickel.
Therefore, for example, it can be applied as a bonding material between a metal and a metal oxide used for a heat radiating substrate for mounting a semiconductor. Specifically, it is suitable for bonding between a copper plate of a heat dissipation substrate and silicon nitride.

6 is an SEM image of the composite particles produced in Example 1.

Hereinafter, embodiments of the present invention will be described.

<Complex particles>
The composite particles of the present invention include core layer metal (II) particles or core layer metal oxide (III) particles.
The core layer metal (II) particles or the core layer metal oxide (III) particles are coated, and a metal species different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles is mainly used. A composite particle containing a coating layer metal (I) contained as a component,
The content of the alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg or less in the composite particles.

<Composite particle composition>
The composite particle composition of the present invention covers the core layer metal (II) particles or the core layer metal oxide (III) particles and the core layer metal (II) particles or the core layer metal oxide (III) particles. , Contains a composite particle containing a coating layer metal (I) containing a metal species different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles as a main component. Complex particle composition
The content of alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg with respect to the content of the main component element of the coating layer metal (I) in the entire composition. It is characterized by being less than kg.

The composite particle composition refers to a composition containing composite particles. The composite particle composition may contain any component other than the composite particles, but preferably contains the composite particles in an amount of 20 wt% or more, more preferably 50 wt% or more based on the total weight of the solid content. .. Here, the solid content refers to a component composed of a metal and a metal oxide among the components contained in the composition. If the content of the composite particles is less than the above range, the effect of the composite particles is less likely to be obtained, and both thermal conductivity and reliability are impaired.
The content of the complex particles can be measured by, for example, ICP emission spectroscopic analysis (high frequency inductively coupled plasma emission spectroscopic analysis, ICP-OES / ICP-AES) and / or cross-sectional observation of the particles by SEM-EDX. it can.

<Contents of alkali metal or alkaline earth metal>
The composite particles or composite particle composition has an alkali metal or alkaline earth metal content of 0.1 mg / mg as measured by high frequency inductively coupled plasma mass spectrometry (ICP mass spectrometry). It is preferably kg or more and 2,000 mg / kg or less. In the case of the composite particle composition, the content of the element as the main component of the coating layer metal (I) in the entire composition is used as a reference. In addition, the measurement is performed on the solid content of the dried product of the composition. A more preferable lower limit is 0.3 mg / kg, and even more preferably 0.5 mg / kg. The upper limit is more preferably 1,800 mg / kg, still more preferably 1,000 mg / kg, particularly preferably 100 mg / kg, and most preferably 10 mg / kg. Within this range, complex particles having less sedimentation and aggregation and excellent dispersibility (hereinafter, also simply referred to as “dispersibility”) can be obtained in the case of a paste, slurry or dispersion. If it is less than 0.1 mg / kg, the desired particle size tends not to be obtained, while if it exceeds 2,000 mg / kg, the dispersibility tends to be impaired.

<Material, composition, shape, thickness, coverage of coating layer metal>
The material of the coating layer metal (I) is appropriately selected according to the intended use, but the main component thereof is preferably silver, nickel, copper or cobalt. Further, the coating layer metal (I) may contain elements other than metal elements such as oxygen, hydrogen, carbon, nitrogen and sulfur, or may be alloys thereof. Further, the coating layer metal (I) may be composed of a single metal or may be a mixture of two or more kinds of metals. More preferably, it is copper, silver or nickel or an alloy of nickel and copper, which is excellent in low cost, high reliability and bondability when used as a bonding material for a SiC power device, and more preferably nickel. Here, the "main component" of the coating layer metal (I) means that the atomic number concentration is 50% or more. It is preferably 60% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 95% or more. The atomic number concentration is, for example, energy with respect to a sample (hereinafter, also referred to as “cross-section sample”) obtained by cross-sectioning a resin embedding of a dried product of a powder or composition by cross-section polishing / CP (cross-section polisher) treatment. It can be measured with a scanning transmission electron microscope (STEM-EDX) with a dispersive X-ray analyzer or a transmission electron microscope (TEM-EDX) with an energy dispersive X-ray analyzer.
Further, the shape of the coating layer metal (I) is not particularly limited. Various shapes such as a film-like shape, a granular shape, a shape in which granules are combined, or a shape in which particles are combined on one core layer thereof can be used.

When used as a bonding material, the thickness of the coating layer of the composite particles is preferably 0.1 to 100 nm, and more preferably 1 to 50 nm, which facilitates bonding between the particles with a thick bypass. More preferably, it is 1 to 20 nm.
A known method is used for measuring the average thickness of the coating layer, and examples thereof include a method of measuring a cross-sectional sample with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like. For example, in the case of SEM, a photograph of a sample is taken, the distance between two points at 50 points is randomly measured, and the average value is calculated. The boundary between the coating and the core is defined as a line analysis using a transmission electron microscope (TEM-EDX) equipped with an energy dispersive X-ray analyzer, in which the main component of the coating shows an atomic number concentration of 30%. To do.

Further, the coating layer does not necessarily have to cover the entire surface of the core layer, and the coating layer may be chipped, but the coverage is preferably 30% or more. Here, the coverage refers to the ratio of the outer peripheral length of the coated portion of the composite particles to the outer peripheral length of the core layer, and can be calculated from cross-sectional observation of the particles or the dried composition with a transmission electron microscope. it can.

<particle size of core layer metal (II) particles or core layer metal oxide (III) particles>
The average particle size of the core layer metal (II) particles or the core layer metal oxide (III) particles exists between the bonded objects to be bonded when used as a bonding material, and has good heat conduction between the bonded objects. The range is 0.03 to 50 μm from the viewpoint of suppressing the volume shrinkage at the time of forming the bonding layer by heating. The average particle size of the metal particles or metal oxide particles that are the raw materials of the core layer metal (II) particles or the core layer metal oxide (III) particles is also the same.
Here, the average particle diameter is obtained by taking a picture of the composite particles, metal particles, or metal oxide particles by SEM, randomly extracting 200 particles from the photographs, and determining the respective areas by image analysis. It means the average particle size (D50) of the primary particles calculated based on the number of particles when converted into a true sphere.
The preferred lower limit of the average particle size is 0.3 μm, while the preferred upper limit is 30 μm, more preferably 20 μm. If the average particle size is less than 0.03 μm, the particles tend to aggregate and it becomes difficult to make a paste. On the other hand, if the average particle size exceeds 50 μm, problems such as deterioration of coatability to the bonded body and difficulty in adjusting the thickness of the bonded layer occur.

<Material, composition, shape, etc. of core layer metal (II) particles>
The material of the core layer metal (II) particles is appropriately selected according to the application, and the main components thereof are aluminum, titanium, iron, manganese, chromium, nickel, cobalt, zirconium, tin, tungsten, molybdenum, vanadium, and the like. Examples thereof include one or more metals selected from copper, silver, gold, and platinum, which may contain elements other than metal elements such as oxygen, hydrogen, carbon, nitrogen, and sulfur, or alloys thereof. Good. Further, it may be composed of a single metal particle, or may be a mixture of two or more kinds of metal particles. The metal type is selected according to the application and price. Preferably, it is aluminum, gold, platinum, silver, nickel, copper or cobalt having excellent thermal conductivity when used as a bonding material for a SiC power device. More preferably, it is aluminum or copper from the viewpoint of cost, and even more preferably, it is copper having good adhesion to nickel, which is preferably used for the coating layer. Here, the "main component" of the core layer metal (II) particles means that the atomic number concentration is 50% or more. It is preferably 70% or more, more preferably 80% or more, still more preferably 90% or more, and particularly preferably 95% or more.

The core layer metal (II) particles may have any shape and composition. For example, in the case of copper particles, the copper element may be contained in an atomic number concentration of 60% or more, preferably 70% or more, and more preferably 90% or more because of its excellent thermal conductivity. The atomic number concentration can be measured by a transmission electron microscope (TEM-EDX) equipped with an energy dispersive X-ray analyzer for the cross-sectional sample. Moreover, the shape and the contained components other than the copper element do not matter. As the components other than the copper element, for example, silver, gold, platinum, aluminum, silicon, silicon carbide, aluminum nitride, and diamond having a thermal conductivity of 100 W / m · K or more as a simple substance are preferably mentioned. Various shapes such as spherical shape, polyhedral shape, fibrous shape, spike shape, and flake shape can be used. More preferably, it is spherical or spike-shaped as a bonding material, which is excellent in filling property and bonding strength.

The method for producing the core layer metal (II) particles is not limited, and the metal particles as a raw material may be commercially available products. For example, in the case of copper particles, commercially available products such as Fukuda Metal Foil Powder Industry Co., Ltd. copper powder (product name: Cu-HWQ) and Furukawa Chemicals Co., Ltd. copper powder (product name: FMC-10, FMC-05C) are preferably used. it can.

The composite particle composition has different thermal conductivity depending on the shape and composition of the core layer and the coating layer, but when used as a bonding material, it exhibits excellent thermal conductivity when the bonding layer is formed. It is preferable that the shape and composition exhibit a thermal conductivity equal to or higher than the thermal conductivity of the current solder, more preferably twice or more, still more preferably 2.5 times or more the thermal conductivity of the solder. Is. This preferred shape is similar to the preferred shape of the core layer metal (II) particles. The shape of the composite particles reflects the shape of the core layer metal (II) particles.

<Material and composition of core layer metal oxide (III) particles>
The material of the core layer metal oxide (III) particles may be a metal oxide, but the preferred main components thereof are alumina, silicon dioxide, zirconia, stabilized zirconia, ceria, doped toceria, lanthanum gallate, and barium cerate. Can be mentioned. Stabilized zirconia includes yttria-stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, and magnesia-stabilized zirconia. Further, the doped ceria includes gadlinear doped ceria, Samaria doped ceria and the like. Here, regarding the core layer metal oxide (III) particles, the "main component" is determined as follows. First, the compound species of the core layer metal oxide (III) is determined from the electron diffraction image measured by a transmission electron microscope (TEM) of the cross section of the dried particle or composition or the X-ray diffraction measurement of the dried particle or composition. Specify (assumed to be oxide α). Next, by energy dispersive X-ray analysis (TEM-EDS) attached to the transmission electron microscope, the total amount of metal elements that are constituents of the core layer metal oxide (III) is calculated excluding non-metal elements. If the concentration of the number of atoms is 50% or more, it is determined that the main component of the particles is oxide α.

Further, the content of the metal element which is a component of the core layer metal oxide (III) is preferably 70% or more, more preferably 80% or more.

The method for producing the core layer metal oxide (III) particles is not limited, and the metal oxide particles as a raw material may be commercially available products. For example, in the case of alumina, a powder manufactured by High Purity Chemical Co., Ltd. (product name: ALE11PB) or the like can be preferably used. In the case of yttria-stabilized zirconia, powder manufactured by Tosoh Corporation (product name: TZ-8Y), powder manufactured by Daiichi Rare Element Chemical Industry Co., Ltd. (HSY-8) and the like can be preferably used.

<Other particles>
The composite particle composition of the present embodiment can further contain other particles as an optional component. Here, the material and shape of the other particles are not limited, but tin, titanium, cobalt, nickel, copper, chromium, manganese, iron, zirconium, tungsten, molybdenum, and vanadium, which have excellent thermal conductivity as a sintered material, are excellent. Examples include base metals such as gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, and metal elements such as noble metals such as renium. These may be contained alone or in two or more kinds. More preferably, it is cobalt, silver, copper or nickel, which has excellent thermal conductivity and sinterability, and even more preferably nickel.
Examples of other particles include other particles a to c described below.
When nickel particles are used as the other particles a, the other particles a may contain a metal other than nickel in a range of less than 50% by weight. In this case, the content of the metal other than nickel is preferably 10% by weight or less, and more preferably 2% by weight or less. It is more preferable that the metal component is nickel only.

Further, the average particle size of the other particles a is within the range of 10 to 150 nm in the average primary particle size as observed by a scanning electron microscope (SEM) from the viewpoint of packing property and bondability.
For example, when component B is heated at a temperature of 300 ° C. and sintered in order to form a bonding layer, the average primary particle size of component A is preferably in the range of 30 to 120 nm, preferably 50 to 100 nm. It is more preferable that it is within the range of.
Further, for example, when the other particles a are nickel particles and the bonding material is heated at a temperature of 350 ° C. for sintering, the average primary particle diameter of the other particles a is within the range of 30 to 120 nm. It is more preferable to have.
If the average primary particle diameter of the other particles a is less than 10 nm, the other particles a tend to aggregate with each other, making uniform mixing with the composite particles difficult. On the other hand, when the average primary particle diameter of the other particles a exceeds 150 nm, the sinterability between the other particles a or between the other particles a and the composite particles is insufficient, and the bonding strength is lowered. Invite.
In the present specification, the average primary particle diameter of the other particles a includes the values used in the examples, and a cross-sectional sample of the particles or the dried composition is sampled with a field emission scanning electron microscope (Field Emission-Scanning Electron Microscope). : FE-SEM), 200 particles were randomly selected from the particles, the area of each particle was obtained by image analysis, and the particle size when converted into a true sphere was used as a reference. Whether or not the observed particle is another particle a is determined by elemental analysis of the central part of the particle by energy dispersive X-ray spectroscopic analysis (SEM-EDX or TEM-EDX) attached to a scanning electron microscope or a transmission electron microscope. It is possible to make a judgment by analyzing.

Further, the other particle a may contain a non-metal element such as an oxygen element and a carbon element. When the carbon element is contained in the other particles a, the content thereof is preferably in the range of 0.3 to 2.5% by weight, more preferably in the range of 0.5 to 2.0% by weight. Is. The carbon element is derived from an organic compound existing on the surface of the component A, and contributes to the improvement of the dispersibility of the other particles a. Therefore, this range is preferable because it has excellent dispersibility and thermal conductivity. If the content of the carbon element of the other particles a is less than 0.3% by weight, the dispersibility tends to decrease, and if it exceeds 2.5% by weight, it is carbonized after firing to become residual carbon, and the bonding layer It tends to reduce thermal conductivity. Further, when the other particles a contain an oxygen element, the sinterability may be lowered, so that the content is, for example, 7.5% by weight or less, preferably 2.0% by weight or less, more preferably. It is 1.0% by weight or less. If it is within this range, it is preferable because it is easier to sinter.
When nickel particles are used as the other particles a, the other particles a may contain a metal other than nickel in a range of less than 50% by weight. In this case, the content of the metal other than nickel is preferably 10% by weight or less, and more preferably 2% by weight or less. It is more preferable that the metal component is nickel only.

The composite particle composition of the present embodiment can further contain other particles b as an optional component. Since the other particles b are not coated, they can be used to inexpensively produce a composite particle composition. Further, the other particles b are present between the bonded bodies to be joined, and have a cross section from the viewpoint of performing good heat conduction between the bonded bodies and suppressing volume shrinkage during formation of the bonded layer due to heating. The average primary particle size calculated from the sample by image analysis is in the range of 0.03 to 50 μm, and the preferable lower limit is 0.3 μm. When the average primary particle diameter is 0.03 μm or less, the particles tend to aggregate and it becomes difficult to make a paste. On the other hand, if the average particle size exceeds 50 μm, problems such as deterioration of paste applicability and difficulty in adjusting the thickness of the bonding layer occur. Regarding the composition of the other particles b, the metal element that occupies 50% or more of the atomic number concentration of the other particle b is the metal element that occupies 50% or more of the atomic number concentration in the coating layer of the composite particle. It is the same metal element Z1. As a result, the composite particles and the other particles b can be brought into close contact with each other at the time of firing, which contributes to the improvement of thermal conductivity and reliability. The preferable ratio contained in the composition is within a range that does not hinder the performance development of the composite particles, and is 50 wt% or less.

The composite particle composition of the present embodiment can further contain other particles c as an optional component. Since the other particles c are not coated, they can be used to inexpensively produce a composite particle composition. Further, the other particles c are present between the bonded bodies to be joined, and have a cross section from the viewpoint of performing good heat conduction between the bonded bodies and suppressing volume shrinkage during formation of the bonded layer due to heating. The average primary particle size calculated from the sample by image analysis is in the range of 0.03 to 50 μm, and the preferable lower limit is 0.3 μm. When the average primary particle diameter is 0.03 μm or less, the particles tend to aggregate and it becomes difficult to make a paste. On the other hand, if the average particle size exceeds 50 μm, problems such as deterioration of paste applicability and difficulty in adjusting the thickness of the bonding layer occur. The main components of the other particles c are the same as the main components of the core layer of the complex particles. As a result, it is possible to suppress the mismatch of the coefficient of thermal expansion in the bonding layer as compared with the case of using different types of particles, which leads to improvement in reliability. The preferable ratio contained in the composition is within a range that does not hinder the performance development of the composite particles, and is 50 wt% or less.

In the composite particle composition, when the core layer of the composite particles is metal (II) particles, the metal element occupying 50% or more of the atomic number concentration in the coating layer of the composite particles and other particles a to. The metal element that occupies 50% or more of the atomic number concentration in b is the same metal element Z1, and the metal element Y1 that occupies 50% or more of the atomic number concentration in the core layer of the composite particles and the metal. The weight ratio (Y1: Z1) with the element Z1 is preferably 95: 5 to 50:50. For example, when the composite particles are nickel-coated copper particles, it is particularly preferable to use nickel nanoparticles as the other particles a because they are excellent in bonding strength and reliability. In this case, the metal element Y1 is copper and the metal element Z1 is nickel.

In a preferred embodiment of the composite particle composition, 0 to 80% by weight of nickel nanoparticles having an average particle diameter of 10 to 150 nm can be added to the nickel-coated copper particles. The average particle size of the nickel nanoparticles is preferably 10 to 150 nm from the viewpoint of bondability, and more preferably 30 to 100 nm, which is a particle size advantageous for bondability. If the average particle size of the nickel nanoparticles is smaller than 10 nm, the surface is easily oxidized and the bondability is lowered, and if it exceeds 150 nm, the bonding temperature of the nickel nanoparticles is high, so that it tends to be difficult to obtain the integration of the bonding layers. It is in. The amount of nickel nanoparticles added is not particularly limited, but is preferably 0 to 80% by weight, more preferably 0 to 50% by weight, and even more preferably 0 to 30% by weight. When nickel nanoparticles are not added, the bonding strength tends to be low. Further, when the amount of nickel nanoparticles added exceeds 80% by weight, the amount of shrinkage increases and the voids increase, so that the thermal conductivity tends to decrease. The weight ratio is, for example, the energy dispersive X-ray attached to the ICP emission spectroscopic analysis method (high frequency inductively coupled plasma emission spectroscopic analysis method, ICP-OES / ICP-AES) and / or the scanning electron microscope of the dried composition. It can be measured by observing the cross section of the particles by analysis. In this method, for example, when nickel-coated particles are used, it is not possible to distinguish between nickel nanoparticles and a nickel-coated film, but the thermal conductivity of the bonded structure is the total amount of nickel elements in the composition and the core layer. Since it depends on the ratio of the amount of major elements, there is no problem in developing the action and effect.

When the core layer of the composite particle is a metal oxide (III) particle, the metal element occupying 50% or more of the atomic number concentration in the coating layer and the atomic number concentration of the other particles a to b are 50. The metal element occupying% or more is the same metal element Z1, and the weight ratio (W1: Z1) of the main component W1 of the core layer metal oxide (III) particles in the composite particles to the metal element Z1. ) Is preferably 90:10 to 10:90. If the weight of the main component W1 of the metal oxide particles exceeds 90% by weight, the effect of increasing the thermal conductivity by the metal element Z1 cannot be expected, and if it is less than 10% by weight, the coefficient of thermal expansion increases and the reliability decreases. To do. The weight ratio can be measured, for example, by ICP emission spectroscopic analysis (high frequency inductively coupled plasma emission spectroscopic analysis, ICP-OES / ICP-AES) of dried composition, transmission electron microscopy of particle cross-section samples, and transmission electrons. It can be carried out by energy dispersive X-ray analysis and electron diffraction measurement attached to the microscope.

Further, in the preparation of the composite particle composition, other particles may be added after the composite particles are prepared, but the metal particles or the metal oxide, which is the method for producing the composite particles of the present invention described above. Another method is to coat the particles with a metal and at the same time generate nanoparticles of the metal as other particles a at the same time. With this method, not only the production efficiency is good, but also the dispersibility between the nanoparticles and the metal particles or the metal oxide particles is improved, and the nanoparticles are adhered to the particle surface, which can be expected to improve the bondability.

The above is an example of the case where the composite particle composition is used as a bonding material. In addition to the bonding material, the composite particle composition may include, for example, electrodes of a laminated ceramic capacitor (MLCC), a transparent conductive film, and the like. It can be applied to electrodes or current collectors such as solid oxide fuel cells and dye-sensitized solar cells, wiring materials such as touch panels and sensors, catalysts, catalyst carriers, magnetic materials, and filters. Then, it can be suitably used for mobile phones, mobile terminals, personal computers, electric / electronic products such as drones and smart watches, and automobile parts such as audio, communication, and computer control.

<Manufacturing method of composite particles>
The preferred method for producing composite particles of the present invention is
The following steps A and B;
A) A step of mixing a metal salt and a reducing agent to obtain a metal complexing reaction solution,
B) A step of heating the metal complexing reaction solution to reduce metal ions in the metal complexing reaction solution to obtain a slurry of composite particles.
Including
Metal particles or metal oxide particles having an average particle diameter of 0.03 to 50 μm, and an alkali metal at any timing between the step A and the heating of the metal complexing reaction solution in the step B. An organometallic compound selected from an organometallic compound or an alkaline earth metal-based organometallic compound is added.

[Step A]
Step A is a step of mixing a metal salt and a reducing agent to obtain a metal complexing reaction solution.

Examples of the metal salt include known base metal salts and noble metal salts. Here, examples of the base metal include nickel, titanium, cobalt, copper, chromium, manganese, iron, zirconium, tin, tungsten, molybdenum, and vanadium. Examples of the precious metal include gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, and rhenium. Among the base metals or precious metals, nickel, titanium, cobalt, copper and silver are preferable.
The metal salt may contain the above metal elements alone or in combination of two or more. Examples of the metal salt include an organic acid metal salt such as a carboxylic acid metal salt and an inorganic metal salt such as a chloride metal salt, a metal sulfate metal salt, a nitrate metal salt and a carbonate metal salt. Among these, a metal chloride salt whose average particle size and particle size distribution of the composite particles can be easily controlled, and a carboxylic acid metal salt having 1 to 12 carbon atoms in the portion excluding the COOH group are preferable. Among these, nickel chloride, nickel acetate, copper acetate and cobalt acetate are more preferable.

The reducing agent is not particularly limited as long as it can form a complex with a metal, but for example, a primary amine can form a complex with a metal and effectively reduces the reducing ability to the metal complex. It is preferably used because it can be exerted. On the other hand, secondary amines have a large steric hindrance and may hinder the good formation of metal complexes. Since tertiary amines do not have the ability to reduce metals, neither can be used alone, but primary amines can be used. In use, it is permissible to use them in combination as long as they do not interfere with the shape of the complex particles to be produced.

The reducing agent may be solid or liquid at room temperature. Here, the normal temperature means 20 ° C. ± 15 ° C. The primary amine, which is liquid at room temperature, also functions as an organic solvent when forming a metal complex. Even if it is a primary amine that is solid at room temperature, there is no particular problem as long as it is a liquid by heating at 100 ° C. or higher or is dissolved by using an organic solvent.

The primary amine may be an aromatic primary amine, but an aliphatic primary amine is preferable from the viewpoint of easiness of forming a metal complex in the reaction solution. Aliphatic primary amines can control the dispersibility of complex particles produced, for example, by adjusting the length of their carbon chains, which is advantageous in applications requiring dispersibility. From the viewpoint of controlling the aggregation of the complex particles, it is preferable to use the aliphatic primary amine selected from those having about 6 to 20 carbon atoms. Examples of such amines include octylamine, trioctylamine, dioctylamine, hexadecylamine, dodecylamine, tetradecylamine, stearylamine, oleylamine, myristylamine, and laurylamine. Oleylamine and dodecylamine are particularly preferable because they exist in a liquid state under the temperature conditions in the process of forming the complex particles, and therefore the reaction can proceed efficiently in a uniform solution. Most preferably, it is oleylamine.

Since the primary amine functions as a surface modifier during metal formation, secondary aggregation can be suppressed even after the primary amine is removed. Further, the primary amine is liquid at room temperature from the viewpoint of ease of treatment operation in the cleaning step of separating the solid component of the produced metal from the solvent or the unreacted primary amine after the reduction reaction in step B. preferable. Further, the primary amine preferably has a boiling point higher than the reduction temperature from the viewpoint of ease of reaction control when the metal complex is reduced to form a metal. The amount of the primary amine is preferably used at a magnification of 1 times mol or more of the valence of the metal with respect to 1 mol of the metal, more preferably 1.1 times mol or more of the valence of the metal, and of the metal. It is more preferable to use twice mol or more of the valence. If the amount of the primary amine is less than 1 times mol of the valence of the metal, it becomes difficult to control the thickness of the obtained coating layer, and the coating amount tends to vary. The upper limit of the amount of the primary amine is not particularly limited, but for example, from the viewpoint of productivity, it is preferably 10 times mol or less of the valence of the metal.

Since the conditions for forming the metal complexing reaction solution in the step A, that is, the mixing conditions for the metal salt and the reducing agent differ depending on the metal salt and the reducing agent used, appropriate conditions may be selected according to the raw materials used. Here, a case where nickel carboxylate is used as the metal salt and primary amine is used as the reducing agent will be described as an example. In this case, the complex formation reaction can proceed even at room temperature, but in order to carry out a sufficient and more efficient complex formation reaction, it is heated to a temperature in the range of, for example, 100 ° C. to 165 ° C. It is preferable to carry out the reaction. The heating temperature is preferably a temperature exceeding 100 ° C., more preferably a temperature of 105 ° C. or higher, so that the ligand substitution reaction between the coordinated water coordinated with nickel carboxylate and the primary amine is efficient. This is done, the water molecule as a complex ligand can be dissociated, and the water can be taken out of the system, so that a complex with an amine can be efficiently formed. Further, when nickel formate dihydrate is used as nickel carboxylate, it has a complex structure in which two coordinated waters and two formalic acids, which are bidentate ligands, are present at room temperature. In order to efficiently form a complex by the ligand substitution of one coordinated water and the primary amine, it is preferable to heat at a temperature higher than 100 ° C. to dissociate the water molecule as a complex ligand. The heating time can be appropriately determined according to the heating temperature and the content of each raw material. There is no particular upper limit to the heating time, but unnecessarily long heat treatment is wasteful from the viewpoint of saving energy consumption and process time.

The heating method in the step A is not particularly limited, and may be heating by a heat medium such as an oil bath, or heating by microwave irradiation or ultrasonic irradiation.

In step A, an organic solvent other than the primary amine may be newly added in order to allow the reaction in the uniform solution to proceed more efficiently. When an organic solvent is used, the organic solvent may be mixed at the same time as the metal salt and the reducing agent, but if the metal salt and the reducing agent are first mixed to form a complex and then the organic solvent is added, the reducing agent efficiently produces metal atoms. It is more preferable because it coordinates with. The organic solvent that can be used is not particularly limited as long as it does not inhibit the complex formation between the metal salt and the reducing agent, for example, an ether-based organic solvent having 4 to 30 carbon atoms and saturation having 7 to 30 carbon atoms. Alternatively, an unsaturated hydrocarbon-based organic solvent or the like can be used. Further, from the viewpoint of enabling use even under heating conditions, it is preferable to select an organic solvent having a boiling point of 170 ° C. or higher. Specific examples of such an organic solvent include tetraethylene glycol and n-octyl ether.

[Step B]
Step B is a step of heating the metal complexing reaction solution to reduce metal ions in the metal complexing reaction solution to obtain a slurry of complex particles.
At any timing between step A and heating the metal complexing reaction solution in step B, metal particles or metal oxide particles having an average particle diameter of 0.03 to 50 μm, and an alkali metal An organometallic compound selected from an organometallic compound or an alkaline earth metal-based organometallic compound (hereinafter, simply referred to as "organometallic compound") is added.
In step B, the organometallic compound and the metal particles or metal oxide particles are added to the metal complexing reaction solution obtained by the complex formation reaction, and then the metal is reduced by heating. The metal derived from the metal complexing reaction solution (corresponding to the coating layer metal (I); hereinafter referred to as “coating metal”) is deposited on the surface of the metal particles or the metal oxide particles.
The amount of the metal particles or the metal oxide particles added in the steps A to B is not particularly limited and varies depending on the particle size, the amount of the coated metal to be precipitated, and the like, so that the addition amount can be selected according to the purpose. ..
The amount of the organometallic compound added in steps A to B varies depending on the amount of metal particles or metal oxide particles, the particle size, the amount of coated metal to be precipitated, and the like. The amount of the organometallic compound added is not limited, and it is possible to deposit the coating metal on the surface of the metal particles or the metal oxide particles without adding the organometallic compound. However, by adding the organometallic compound, the composite is formed. Since body particles and metal nanoparticles derived from the metal complexing reaction solution and having the same components as the coating metal can be generated at the same time, they can be selected according to the purpose.
Examples of the shape of the coating metal deposited on the surface of the metal particles or the metal oxide particles include a particulate shape, a shape in which a plurality of particles are bonded, and a layered shape.

The amount of the organic metal compound to be added may be adjusted according to the purpose. For example, the smaller the average particle size of the metal particles or the metal oxide particles, that is, the larger the surface area of the metal particles or the metal oxide particles. By increasing the amount added, the metal is deposited on the surface of the metal particles or the metal oxide particles at a lower temperature and in a shorter time. When the addition amount of the organic metal compound is further increased, metal nanoparticles derived from the metal complexing reaction solution (for example, nickel nanoparticles derived from a nickel salt) are simultaneously produced, and when the addition amount is further increased, the complex formed. The average particle size of the particles becomes smaller. The amount of addition can be determined according to the desired average particle size of the composite particles.

The organometallic compound has the same properties (nucleophile) as the nucleophile, and is not particularly limited as long as it acts on the metal complex. As a preferable organometallic compound, an organic group such as an alkyl group or an alkoxy group is arranged in the alkali metal from the viewpoints of controllability of the average particle size and particle size distribution of the complex particles, safety, convenience, and productivity. Examples of the placed alkali metal-based organometallic compound and the alkali earth metal include an alkali earth metal-based organometallic compound in which the organic group is coordinated. Hereinafter, the alkali metal-based organometallic compound and the alkaline earth metal-based organometallic compound are collectively referred to as "the present organometallic compound". The present organometallic compound may be an organometallic halide containing a halide such as chlorine, bromine, or iodine. In this case, they are also referred to as an alkali metal-based organometallic halide and an alkaline earth metal-based organometallic halide, respectively. The alkali metal-based organometallic halide is a form of an alkali metal-based organometallic compound, and the alkali earth metal-based organometallic halide is a form of an alkaline earth metal-based organometallic compound.

Examples of the alkali metal constituting the alkali metal-based organometallic compound include lithium, sodium, potassium, rubidium, and cesium, and organic lithium containing highly reactive lithium is preferably used.
Examples of the alkaline earth metal constituting the alkaline earth metal-based organic metal compound include beryllium, magnesium, calcium, strontium, and barium, and an organic magnesium halide containing magnesium having good reactivity can be used. It is preferably used. Since alkylaluminum in which an alkyl group is coordinated with aluminum has strong ignitability, alkali metal-based and alkaline earth metal-based organometallic compounds are more preferably used from the viewpoint of safety and convenience. ..

The present organic metal compound is preferably used as a diluted solution diluted with an organic solvent such as tetrahydrofuran, hexane, toluene, cyclohexane, butyl ether, dibutyl ether and the like. There is no limitation on the concentration of the diluted solution, but when a small amount affects the particle size, a low concentration is preferable because it is easier to control.

As the alkali metal-based organometallic compound, inexpensive and general-purpose n-butyllithium and phenyllithium are preferably used, and these toluene solutions and n-hexane solutions are particularly suitable from the viewpoint of safety and convenience. ..
Further, as the alkaline earth metal-based organometallic compound, ethylmagnesium chloride, ethylmagnesium bromide, butylmagnesium chloride, 2-butylmagnesium chloride-lithium chloride complex, and butylmagnesium bromide are preferably used, and these tetrahydrofuran solutions are particularly preferable. Used for.

The metal particles or metal oxide particles having an average particle diameter of 0.03 to 50 μm (corresponding to core layer metal (II) particles or core layer metal oxide (III) particles) and the present organic metal compound are obtained from step A. , The metal complexing reaction solution may be added at any timing until it is heated in step B. For example, the metal particles or metal oxide particles and the present organometallic compound may be added after mixing a metal salt and a reducing agent in step A to remove excess water, or a metal complexing reaction solution is prepared. It may be added after the above. Further, since the organometallic compound is easily deactivated by water and loses its effect, it is preferable to add the organometallic compound immediately before heating the metal complexing reaction solution in step B. Since the effect is deactivated by the influence of moisture absorption and it becomes difficult to control the particle size distribution, it is preferable to add the present organometallic compound immediately before heating the metal complexing reaction solution in step B.

The thickness of the coating layer deposited on the surface of the metal particles or metal oxide particles depends on the concentration of the metal complexing reaction solution, the amount of metal particles or metal oxide particles added, the average particle size, shape, and the amount of organic metal compound added. The desired thickness can be obtained by varying and adjusting these control factors.

Examples of the heating means in the step B include a heat medium such as an oil bath, a heating method using electricity, microwaves, and ultrasonic waves. From the viewpoint of production cost, a heating method using a heat medium such as an oil bath or electricity is preferably used.

In step B, in order to improve the dispersibility of the composite particles and to impart a function such as a rust preventive for preventing oxidation, a known dispersant or an additive for imparting the function is added. You may.

<Joint material>
The bonding material of the present invention has a content of the composite particles of 30 to 90% by weight. Within this range, a bonding material having high thermal conductivity and less likely to be deteriorated by oxidation, which is a feature of the composite particles, can be obtained. In particular, nickel-coated copper particles in which the core layer metal (II) particles are copper particles and the coating layer metal (I) is nickel are preferable because the effect is remarkable.

The bonding material can further contain, as an optional component, an organic solvent having a boiling point in the range of 100 to 350 ° C. The boiling point of the solvent contained in the bonding material is preferably in the range of 150 to 260 ° C. from the practical point of view. If the boiling point of the organic solvent used is less than 100 ° C, it tends to lack long-term stability, and if it exceeds 350 ° C, residual carbon is generated in the bonding layer without volatilizing during heating, and the particles are sintered together. And tends to inhibit the formation of intermetallic compounds. The bonding material is preferably in the form of a paste after adding an organic solvent having a high boiling point and concentrating the bonding material.

As the organic solvent having a boiling point in the range of 100 to 350 ° C., for example, alcohol-based, aromatic-based, hydrocarbon-based, ester-based, ketone-based, and ether-based solvents can be used. Examples of alcohol-based solvents include 1-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-nonanol, 3,5,5-trimethyl-1-hexanol, 1-decanol, 1-. Aliper alcohols with 7 or more carbon atoms such as undecanol and isobornylcyclohexanol, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butane Polyhydric alcohols such as diol, 1,6-hexanediol, 1,8-octanediol, tetramethylene glycol, methyltriglycol, terpineols such as α-terpineol, β-terpineol, γ-terpineol, and ethylene glycol mono. Propyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, methylmethoxybutanol, diethylene glycol, dipropylene glycol, 2-phenoxyethanol, 1-phenoxy-2-propanol Alcohols having an ether group such as, etc. can be mentioned. Further, examples of the hydrocarbon solvent include octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane and the like.

The content of the organic solvent in the bonding material is preferably 2 to 40% by weight, more preferably 4 to 30% by weight, still more preferably 5 to 15% by weight. If the content of the organic solvent in the bonding material is less than 2% by weight, the fluidity tends to decrease and the usability as the bonding material tends to decrease. On the other hand, if the content of the organic solvent exceeds 40% by weight, for example, it is necessary to repeat coating a plurality of times, which causes unevenness, and there is a tendency that sufficient bonding strength cannot be obtained.

In addition, the bonding material may contain an organic binder as an optional component. The organic binder contributes to the formation of a massive bonding layer having high bonding strength by connecting the composite particles or the composite particles to other particles to form a wide-ranging network structure.

The organic binder can be used without particular limitation as long as it is soluble in an organic solvent. For example, a thermosetting resin such as a phenol resin, an epoxy resin, an unsaturated polyester resin, a urea resin, or a melamine resin, or polyethylene. Examples thereof include thermoplastic resins such as resins, acrylic resins, methacrylic resins, nylon resins, acetal resins, and polyvinyl acetal resins. Among these, a polyvinyl acetal resin is preferable, and a polyvinyl acetal resin having an acetal group unit, an acetyl group unit, and a hydroxyl group unit in the molecule is more preferable.

Further, the organic binder preferably has a molecular weight of 30,000 or more, and more preferably 100,000 or more, in order to suppress sedimentation of composite particles and other particles and maintain a sufficiently dispersed state.

Further, as the organic binder, for example, a commercially available product such as a polyvinyl acetal resin (Eslek BH-A; trade name) manufactured by Sekisui Chemical Co., Ltd. can be preferably used.

The blending amount of the organic binder in the bonding material is preferably in the range of 0.05 to 5.0% by weight, more preferably 0.1 to 2 with respect to the total amount of particles in the bonding material. It is in the range of 5.5% by weight, more preferably in the range of 0.3 to 1.5% by weight, and particularly preferably in the range of 0.5 to 1.2% by weight. Here, if it exceeds the above range, the sintering between the composite particles or between the composite particles and other particles tends to be insufficient, and if it is below the above range, the effect of blending tends not to be obtained. It is in.

In addition to the above components, the bonding material may contain, for example, a thickener, a thixotropy, a leveling agent, a surfactant, or the like as optional components.

<Joining method>
By interposing the bonding material between the members to be bonded and heating the members, a bonding layer can be formed between the members to be bonded and the members to be bonded can be bonded to each other. The firing conditions may be a reducing gas atmosphere, and the temperature may be, for example, in the range of 100 ° C. to 500 ° C., preferably in the range of 200 to 400 ° C., more preferably in the range of 230 to 350 ° C. May be good. Here, the “reducing gas atmosphere” includes an atmosphere containing hydrogen gas and an atmosphere containing formic acid. Preferably, it is in an atmosphere containing hydrogen gas, which has good reduction efficiency.
In this joining method (hereinafter referred to as "main joining method"), in order to proceed with sintering between components B or between component B and component A, the metal surfaces of component B and component A are exposed. Is considered necessary. The heating temperature for volatilizing or decomposing the organic substances present on these surfaces and removing the passivation layer is preferably 200 ° C. or higher, more preferably 250 ° C. or higher. On the other hand, if the heating temperature exceeds 500 ° C., when a semiconductor device is used as the member to be joined, the periphery of the semiconductor device may be damaged.

In this bonding method, for example, a step of applying a paste-like bonding material to one or both bonded surfaces of a pair of members to be bonded (coating step), bonding the bonded surfaces to each other, preferably at a temperature of 200 to 400 ° C. The step of sintering the bonding material (baking step) can be included by heating in the range of, more preferably in the range of 250 to 400 ° C., still more preferably in the range of 250 to 350 ° C.

In the coating step, for example, methods such as spray coating, inkjet coating, and printing can be adopted. The bonding material can be applied to any shape such as a pattern shape, an island shape, a mesh shape, a lattice shape, and a stripe shape, depending on the purpose. In the coating step, it is preferable to apply the bonding material so that the thickness of the coating film is within the range of 50 to 200 μm. By applying with such a thickness, defects in the joint portion can be reduced, so that it is possible to prevent an increase in electrical resistance and a decrease in joint strength.

Further, in the firing step, the members to be joined are subjected to pressurization or no pressurization. When the pressure is applied, the pressure is preferably 10 MPa or less, more preferably 1 MPa or less. By pressurizing under a low pressure of 10 MPa or less or under no pressurization, the firing process can be simplified, and damage to the member to be joined due to the pressurization can be reduced.

This joining method can be used, for example, in joining Si-based and SiC-based semiconductor materials and in the manufacturing process of electronic components. Here, examples of electronic components include mainly semiconductor devices and energy conversion module components. When the electronic component is a semiconductor device, for example, between the back surface of the semiconductor element and the substrate, between the semiconductor electrode and the substrate electrode, between the semiconductor electrode and the semiconductor electrode, and between the power device or the power module and the heat radiation member. It can be applied to joining such as.

When joining electronic components, in order to increase the joining strength, a contact layer made of a material such as Au, Cu, Pd, Ni, Ag, Cr, Ti, or an alloy thereof is previously applied to one or both of the surfaces to be joined. It is preferable to provide it. When the material of the surface to be bonded is SiC or Si or an oxide film on the surface thereof, a contact layer made of a material such as Ti, TiW, TiN, Cr, Ni, Pd, V, or an alloy thereof is used. It is preferable to provide it.

As described above, in the composite particles of the present invention, most of the parts exposed to the air are composed of the coating layer metal (I). When the coating layer metal (I) is a metal species that forms an oxidation passivation film on the metal surface in the air, it is possible to suppress the progress of oxidation above a certain level, so that even when the material is exposed to high temperatures, the material Prevents changes over time and has high reliability. Further, the composite particles dispersed in the bonding layer serve as a heat path, so that the thermal conductivity of the entire bonding layer is improved. In this way, it is possible to achieve both high reliability and high thermal conductivity.
Therefore, the bonding material of the present invention can be used particularly preferably for each application used in a high temperature region, for example. For example, it can be suitably used as a bonding material for bonding a power semiconductor chip using SiC and a mounting substrate, which requires reliability during driving in a high temperature region of 250 ° C. or higher. In addition, it can also be used for joining a semiconductor chip using Si to a mounting substrate, joining an LED to an electrode, and the like.

[Joint]
The bonded body of the present embodiment is formed by bonding a first metal layer and a second metal layer constituting a semiconductor element with the bonding material. The junction of the present embodiment is preferably a semiconductor module, and more preferably a semiconductor module for a power device used in, for example, a power conversion device, a power control device, a power supply device, or the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In the following examples, the measurement and evaluation are as follows unless otherwise specified.

[Measurement of average particle size]
To measure the average particle size, a photograph of a cross-sectional sample of a dried particle or composition of a particle or composition was taken by SEM, 200 particles were randomly selected from the photograph, and the area of each was obtained by image analysis and converted into a true sphere. The average particle size of the primary particles was calculated based on the number of particles. The CV value (coefficient of variation) was calculated by (standard deviation) ÷ (average particle size). The smaller the CV value, the more uniform the particle size.

[Measurement of coating layer thickness]
Photographs of cross-sectional samples of particles or compositions of dried bodies were measured by SEM, and the distances between two points at 50 points were randomly measured from the photographs, and the average value was calculated.

[Measurement of thermal conductivity]
In the case of evaluation of the core layer metal particles, a copper plate (10 mm × 10 mm × thickness 1 mm) / particle sintered layer (10 mm × 10 mm × thickness 0.2 mm) / copper plate laminated test piece is used as the core layer metal oxide particles. In the case of evaluation, a lamination test of a metal oxide plate (10 mm × 10 mm × thickness 1 mm) / particle sintered layer (10 mm × 10 mm × thickness 0.2 mm) / metal oxide plate (10 mm × 10 mm × thickness 1 mm) The pieces were prepared by pressure firing. In the case of core layer metal particles, calcination was carried out at 300 ° C. for 30 minutes while pressurizing under a nitrogen gas flow in which hydrogen was mixed in a volume of 3%. In the case of the core layer metal oxide particles, the temperature was 1350 ° C. for 2 hours while pressurizing in an air atmosphere. The thermal conductivity was measured using a NETZSCH Xe flash analyzer LFA 447 Nanoflash.

[Synthesis Example 1]
20.6 g of nickel acetate tetrahydrate was added to 50 g of oleylamine, and the mixture was heated to 140 ° C. and held for 180 minutes under a nitrogen stream to obtain a complexing reaction solution 1 (the above is the complexing reaction step).

[Example 1]
59.8 g of copper particles (average particle size; 0.54 μm, FMC-05C; manufactured by Furukawa Chemicals Co., Ltd.) in 65 g of the complexing reaction solution 1 under a nitrogen stream, and 20% phenyllithium (PhLi) as an organometallic compound. ) ・ Add 118 mg of dibutyl ether solution, heat to 252 ° C with a mantle heater, and further heat at 252 ° C for 5 minutes to make the core layer metal (II) particles copper and the coating layer metal (I). A copper-nickel composite particle A slurry, which is nickel, was obtained.
The obtained copper-nickel composite particle A slurry was washed with toluene and then allowed to stand to precipitate the copper-nickel composite particle A.
The average particle size of the copper-nickel composite particles A was 0.55 μm, and the thickness of the coating layer was 5 nm.
The amount of Li measured by ICP mass spectrometry was 1.4 mg / kg in the copper-nickel composite particles A.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. 5 g of copper-nickel composite particles A was added to 0.5 g of the solution, and the mixture was stirred and concentrated to obtain a paste 1 of copper-nickel composite particles A. The weight ratio (Cu: Ni) of copper atoms and nickel atoms in the paste 1 calculated from the raw material charging ratio was 92.5: 7.5.

The paste 1 of the copper-nickel composite particles A was fired at 180 ° C. for 1 hour, and fired in the same manner as the above-mentioned method for preparing a sample for measuring thermal conductivity to obtain a fired body 1. It was. An SEM (magnification 100,000 times) image of the fired body 1 is shown in FIG. In the fired body 1, the interface between the copper-nickel composite particles disappeared, and it was confirmed that the copper-nickel composite particles were bonded to each other.

[Synthesis Example 2]
82.3 g of nickel acetate tetrahydrate was added to 200 g of oleylamine, and the mixture was heated to 140 ° C. and held for 180 minutes under a nitrogen stream to obtain a complexing reaction solution 2 (the above is the complexing reaction step).

[Example 2]
45.3 g of copper particles (average particle size; 2.5 μm, FMC-10C; manufactured by Furukawa Chemicals Co., Ltd.) in 282 g of complexing reaction solution 2 under a nitrogen stream, and 20% phenyllithium (PhLi) as an organometallic compound. ) ・ Add 352 mg of dibutyl ether solution, heat to 252 ° C with a mantle heater, and further heat at 252 ° C for 5 minutes to make the core layer metal (II) particles copper and the coating layer metal (I). A copper-nickel composite particle B slurry, which is nickel, was obtained. At the same time, nickel particles B were formed in the slurry.
The obtained copper-nickel composite particle B slurry was washed with toluene and then allowed to stand to allow the copper-nickel composite particle B to settle.
The thickness of the coating layer of the copper-nickel composite particles B was 10 nm, and the average particle diameter of the nickel particles B was 61 nm.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. 4.5 g of a mixture of copper-nickel composite particles B and nickel particles B was added to 0.5 g of the solution, and the mixture was stirred and concentrated to obtain a paste 2 of copper-nickel composite particles B. The weight ratio (Cu: Ni) of copper atoms and nickel atoms in the paste 2 calculated from the raw material charging ratio was 70.0: 30.0.
The amount of Li measured by ICP mass analysis was 11.3 mg / kg in the mixture of the copper-nickel composite particles B and the nickel particles B.

For the paste 2 of the copper-nickel composite particles B, a fired body 2 was obtained in the same manner as in Example 1. In the fired body 2, the interface between the copper-nickel composite particles B disappeared, and it was confirmed that the copper-nickel composite particles B were bonded to each other. In addition, bonding between copper-nickel composite particles B-nickel particles B was also confirmed.

[Synthesis Example 3]
20.6 g of nickel acetate tetrahydrate was added to 50.9 g of oleylamine, and the mixture was heated to 140 ° C. and held for 180 minutes under a nitrogen stream to obtain a complexing reaction solution 3 (the above is the complexing reaction step). ..

[Example 3]
19.3 g of copper particles (average particle size; 2.5 μm, Cu-HWQ; manufactured by Fukuda Metal Foil Industry Co., Ltd.) in 65 g of complex reaction solution 3 under a nitrogen stream, and 20% phenyllithium as an organometallic compound. By adding 126 mg of the (PhLi) dibutyl ether solution, heating to 252 ° C with a mantle heater, and further heating at 252 ° C for 5 minutes, the core layer metal (II) particles are copper and the coating layer metal (I). ) Is nickel, a copper-nickel composite particle C slurry was obtained. At the same time, nickel particles C were formed in the slurry.
The obtained copper-nickel composite particle C slurry was washed with toluene and then allowed to stand to precipitate the copper-nickel composite particle C.
The thickness of the coating layer of the copper-nickel composite particles C was 12 nm, and the average particle diameter of the nickel particles C was 56 nm.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. 4.5 g of a mixture of copper-nickel composite particles C and nickel particles C was added to 0.5 g of the solution, and the mixture was stirred and concentrated to obtain a paste 3 of copper-nickel composite particles C. The weight ratio (Cu: Ni) of copper atoms and nickel atoms in the paste 3 calculated from the raw material charging ratio was 70.0: 30.0.
The amount of Li measured by ICP mass analysis was 2.0 mg / kg in the mixture of copper-nickel composite particles C and nickel particles C.

For the paste 3 of the copper-nickel composite particles C, a fired body 3 was obtained in the same manner as in Example 1. In the fired body 3, the interface between the copper-nickel composite particles C disappeared, and it was confirmed that the copper-nickel composite particles C were bonded to each other. In addition, bonding between copper-nickel composite particles C and nickel particles C was also confirmed.

[Synthesis Example 4]
82.3 g of nickel acetate tetrahydrate was added to 200 g of oleylamine, and the mixture was heated to 140 ° C. and held for 180 minutes under a nitrogen stream to obtain a complexing reaction solution 4 (the above is the complexing reaction step).

[Example 4]
In 282 g of the complexing reaction solution 4, 45.3 g of copper particles (average particle size; 15 μm, MA-CJU; manufactured by Mitsui Metal Mining Co., Ltd.) under a nitrogen stream, and 20% phenyllithium (PhLi) as an organometallic compound. -Add 226 mg of dibutyl ether solution, heat to 252 ° C with a mantle heater, and further heat at 252 ° C for 5 minutes to make the core layer metal (II) particles copper and the coating layer metal (I) nickel. A copper-nickel composite particle D slurry was obtained. At the same time, nickel particles D were formed in the slurry.
The obtained copper-nickel composite particle D slurry was washed with toluene and then allowed to stand to precipitate the copper-nickel composite particle D.
The thickness of the coating layer of the copper-nickel composite particles D was 15 nm, and the average particle diameter of the nickel particles D produced at the same time was 69 nm.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. To 0.5 g of the solution, 4.5 g of a mixture of copper-nickel composite particles D particles and nickel particles D was added, and the mixture was stirred and concentrated to obtain a paste 4 of copper-nickel composite particles D. The weight ratio (Cu: Ni) of copper atoms and nickel atoms in the paste 4 calculated from the raw material charging ratio was 70.0: 30.0.
The amount of Li measured by ICP mass analysis was 2.3 mg / kg in the mixture of the copper-nickel composite particle D particles and the nickel particles D.

For the paste 4 of the copper-nickel composite particles D, a fired body 4 was obtained in the same manner as in Example 1. In the fired body 4, the interface between the copper-nickel composite particles D disappeared, and it was confirmed that the copper-nickel composite particles D were bonded to each other. In addition, bonding between copper-nickel composite particles D-nickel particles D was also confirmed.

[Comparative Example 1]
226 mg of a 20% phenyllithium (PhLi) dibutyl ether solution as an organometallic compound is added to the complexing reaction solution 4 of Synthesis Example 4, heated to 252 ° C. with a mantle heater, and further heated at 252 ° C. for 5 minutes. The nickel particles E (average particle diameter 68 nm) were obtained. A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Co., Ltd.) as a binder resin were prepared. To 0.5 g of the solution, 4.5 g of a mixture of nickel particles E and copper particles (average particle size; 0.54 μm, FMC-05C; manufactured by Furukawa Chemicals Co., Ltd.) was added, and the mixture was stirred and concentrated to obtain a paste 5. .. The weight ratio (Cu: Ni) of copper atoms and nickel atoms in the paste 5 calculated from the raw material charging ratio was 70.0: 30.0.

For the paste 5 of the copper-nickel composite particles E, a fired body 5 was obtained in the same manner as in Example 1.

Further, a similar fired body was produced using solder (tin-silver-copper).

When the thermal conductivity of the fired bodies 1 to 5 is more than twice as high as that of the fired body using solder (tin-silver-copper), it is evaluated as ○ (good), and when it is not, it is evaluated as × (bad). did. The results are shown in Table 1.

[Synthesis Example 5]
82.3 g of nickel acetate tetrahydrate was added to 200 g of oleylamine, and the mixture was heated to 140 ° C. and held for 180 minutes under a nitrogen stream to obtain a complexing reaction solution 5 (the above is the complexing reaction step).

[Example 5]
In 282 g of the complexing reaction solution 5, 12.9 g of yttria-stabilized zirconia particles (average particle size; 40 nm, TZ-8Y; manufactured by Toso Co., Ltd.) as metal oxide particles under a nitrogen stream, and 20 as an organic metal compound. Add 226 mg of% phenyllithium (PhLi) dibutyl ether solution, heat to 250 ° C with a mantle heater, and further heat at 250 ° C for 10 minutes to yttria-stabilized zirconia in the core layer metal oxide (III) particles. A yttria-stabilized zirconia-nickel composite particle F slurry was obtained in which the coating layer metal (I) was nickel. At the same time, nickel particles F were generated in the slurry.
The obtained yttria-stabilized zirconia-nickel composite particle F slurry was washed with toluene and then allowed to stand to precipitate the yttria-stabilized zirconia-nickel composite particle F.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. To 0.5 g of the solution, 4.5 g of a mixture of yttria-stabilized zirconia-nickel composite particles F particles and nickel particles F was added, stirred and concentrated to add paste 6 of yttria-stabilized zirconia-nickel composite particles F. Obtained. The weight ratio of yttria-stabilized zirconia (YSZ) and nickel atoms (YSZ: Ni) in the paste 6 calculated from the raw material charging ratio is 40.0: 60.0.

The thickness of the coating layer of the yttria-stabilized zirconia-nickel composite particles F was 20 nm, and the average particle diameter of the nickel particles F was 50 nm.

Further, the weight ratio of the main component W1 of the core layer metal oxide (III) particles of the composite particles and the metal element Z1 accounting for 50% or more of the atomic number concentration in the coating layer of the composite particles is the transmission type of the cross-sectional sample. It was calculated from the results of electron microscope observation, energy dispersive X-ray analysis, electron diffraction, and ICP emission spectrum analysis.

The paste 6 of the yttria-stabilized zirconia-nickel composite particles F was fired in the same manner as in Example 1 to obtain a fired body 6. The thermal conductivity of the fired body 6 was measured.

[Examples 6 to 12, Comparative Examples 2 to 4]
A fired body was prepared in the same manner as in Example 5 except that the types of metal oxide particles and the coating layer metal, the weight ratio, and the types of the members to be joined i and ii were changed as shown in Table 2, and the thermal conductivity was changed. Evaluation was carried out. A comparative example is the case where the metal oxide particles are not coated.

When the thermal conductivity exceeded the physical property value of the metal oxide, it was evaluated as ◯ (good), and when it did not exceed it, it was evaluated as × (poor). The evaluation results of Examples 5 to 12 and Comparative Examples 2 to 4 are summarized in Table 2.
In addition, 1.5 W / mK for SiO ₂ , 32 W / mK for alumina, and 3 W / mK for YSZ were used as physical property values.
The metal oxide particles used are as follows.
YSZ particles: same as Example 5 SiO ₂ particles: average particle size; 1.8 μm, manufactured by Aldrich Alumina particles: average particle size; 8.5 μm, manufactured by High Purity Chemicals Co., Ltd.

[Example 13]
In 282 g of the complexing reaction solution 5, 19.4 g of yttria-stabilized zirconia particles (average particle size; 40 nm, TZ-8Y; manufactured by Toso Co., Ltd.) as metal oxide particles under a nitrogen stream, and 20 as an organic metal compound. Add 226 mg of% phenyllithium (PhLi) dibutyl ether solution, heat to 250 ° C with a mantle heater, and further heat at 250 ° C for 10 minutes to yttria-stabilized zirconia in the core layer metal oxide (III) particles. A yttria-stabilized zirconia-nickel composite particle G slurry was obtained in which the coating layer metal (I) was nickel. At the same time, nickel particles G were generated in the slurry.
The yttria-stabilized zirconia-nickel composite particle G slurry was washed with toluene and then allowed to stand to precipitate the yttria-stabilized zirconia-nickel composite particle G.
A mixed solution of 50 parts by weight of hexylcarbitol and 50 parts by weight of butyltriglycol and a mixed solution of 5 parts by weight of polyvinyl acetal resin (Eslek BHA; manufactured by Sekisui Chemical Industry Co., Ltd.) as a binder resin were prepared. 5.0 g of a mixture of Itria-stabilized zirconia-nickel composite particle G particles and nickel particles G, 0.8 g of Ni powder (3-5 μm, manufactured by High Purity Chemicals) and Itria-stabilized zirconia powder with respect to 0.8 g of the solution. 0.8 g (0.5-0.7 μm, manufactured by Toyo Technica) was added, stirred and concentrated to obtain a paste 7 of Itria-stabilized zirconia-nickel composite particles G. The weight ratio of yttria-stabilized zirconia (YSZ) and nickel atoms (YSZ: Ni) in the paste calculated from the raw material charging ratio was 50.0: 50.0.

The thickness of the coating layer of the yttria-stabilized zirconia-nickel composite particles G was 21 nm, and the average particle diameter of the nickel particles G was 52 nm.

The W1 and Z1 ratios were calculated from the results of transmission electron microscope observation of cross-sectional samples, energy dispersive X-ray analysis, electron diffraction, and ICP emission spectroscopic analysis.

The paste 7 of the yttria-stabilized zirconia-nickel composite particles G was fired in the same manner as in Example 1 to obtain a fired body 7, and the thermal conductivity of the fired body 7 was measured. An yttria-stabilized zirconia plate was used as the member to be joined. As a comparative example, a case where the metal oxide particles were not coated was used. Based on the physical property value of YSZ of 3 W / m · K, the thermal conductivity was evaluated as good (◯) when it exceeded, and poor (x) when it did not exceed it. The results are shown in Table 3.

Although the embodiments of the present invention have been described in detail for the purpose of illustration, the present invention is not limited to the above embodiments.

This application claims priority based on Japanese Patent Application No. 2017-1994, filed September 29, 2017, and Japanese Patent Application No. 2017-254778 filed on December 28, 2017. The entire contents of the application are incorporated herein by reference.

Claims (23)

The following steps A and B;
A) A step of mixing a metal salt and a reducing agent to obtain a metal complexing reaction solution,
B) A step of heating the metal complexing reaction solution to reduce metal ions in the metal complexing reaction solution to obtain a slurry of composite particles.
Including
Metal particles or metal oxide particles having an average particle diameter of 0.03 to 50 μm, and an alkali metal at any timing between the step A and the heating of the metal complexing reaction solution in the step B. A method for producing a composite particle, which comprises adding an organometallic compound selected from an organometallic compound or an alkaline earth metal-based organometallic compound. The method for producing composite particles according to claim 1, wherein the organometallic compound has nucleophilicity. The method for producing composite particles according to claim 2, wherein the organometallic compound is an organomagnesium halide or an organolithium. The metal particles consist of one or more metals selected from aluminum, titanium, iron, manganese, chromium, nickel, cobalt, zirconium, tin, tungsten, molybdenum, vanadium, copper, silver, gold, and platinum, with an atomic number concentration of 50. The method for producing a composite particle according to any one of claims 1 to 3, which contains% or more. Any of claims 1 to 3, wherein the metal oxide particles contain one or more metal oxides selected from alumina, silicon dioxide, zirconia, stabilized zirconia, ceria, doped ceria, lanthanum gallate, and barium cerate as main components. The method for producing a composite particle according to item 1. The method for producing composite particles according to any one of claims 1 to 5, wherein the metal salt is a silver salt, a nickel salt, a copper salt or a cobalt salt. With core layer metal (II) particles or core layer metal oxide (III) particles,
A metal species that coats the core layer metal (II) particles or the core layer metal oxide (III) particles and is different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles. With a coating layer metal (I) containing as a main component,
It is a complex particle containing
Complex particles in which the content of alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg or less in the composite particles. With core layer metal (II) particles or core layer metal oxide (III) particles,
A metal species that coats the core layer metal (II) particles or the core layer metal oxide (III) particles and is different from the main component of the core layer metal (II) particles or the core layer metal oxide (III) particles. With a coating layer metal (I) containing as a main component,
A composite particle composition containing complex particles containing
The content of alkali metal or alkaline earth metal by ICP mass spectrometry is 0.1 mg / kg or more and 2,000 mg / kg with respect to the content of the main component element of the coating layer metal (I) in the entire composition. A composite particle composition of kg or less. It contains other particles a having an average primary particle diameter of 10 to 150 nm.
The metal element having an atomic number concentration of 50% or more in the coating layer of the composite particles and the metal element having an atomic number concentration of 50% or more in the other particles a are the same metal element Z1. The complex particle composition according to claim 8. Contains other particles b having an average primary particle size of 0.03 to 50 μm.
The metal element having an atomic number concentration of 50% or more in the coating layer of the composite particles and the metal element having an atomic number concentration of 50% or more in the other particles b are the same metal element Z1. The composite particle composition according to claim 8 or 9. Includes other particles c with an average primary particle size of 0.03-50 μm,
The composite particle composition according to any one of claims 8 to 10, wherein the main component of the core layer of the composite particle and the main component of the other particle c are the same. The weight ratio (Y1: Z1) of the metal element Y1 accounting for 50% or more of the atomic number concentration in the core layer metal (II) particles of the composite particles to the metal element Z1 is 95: 5 to 50:50. The composite particle composition according to claim 9 or 10, wherein the composite particle composition is characterized by the above. The composite particle composition according to claim 12, wherein the main component of the core layer metal (II) particles is gold, platinum, silver, nickel, copper or cobalt. The composite particle composition according to claim 13, wherein the metal element Y1 is copper and the metal element Z1 is nickel. The claim is characterized in that the weight ratio (W1: Z1) of the main component W1 of the core layer metal oxide (III) particles of the composite particles and the metal element Z1 is 90:10 to 10:90. 9 or 10 of the complex particle composition. The composite particle composition according to claim 15, wherein the core layer metal oxide (III) particles contain alumina, silicon dioxide, zirconia, stabilized zirconia, ceria, doped toceria, lanthanum gallate, and barium serate as main components. .. The composite particle composition according to claim 16, wherein the main component W1 of the core layer metal oxide (III) particles is yttria-stabilized zirconia, and the metal element Z1 is nickel. A bonding material containing the composite particles according to claim 7 and an organic solvent having a boiling point in the range of 100 to 350 ° C., and the content of the organic solvent is in the range of 2 to 40% by weight. The bonding material according to claim 18, further containing an organic binder in the range of 0.05 to 5.0% by weight based on the total amount of particles. A joining method in which a joining layer according to claim 18 or 19 is interposed between the members to be joined and heated to form a joining layer between the members to be joined, and the members to be joined are joined to each other. The joining method according to claim 20, wherein the heating temperature is in the range of 100 ° C. to 500 ° C., and the treatment atmosphere is a reducing gas atmosphere. A joined body formed by joining a first member to be joined and a second member to be joined by the joining material according to claim 18 or 19. The bonded body according to claim 22, wherein the first member to be bonded is a first metal layer constituting a semiconductor element, and the second member to be bonded is a second metal layer.