JP6463195B2 - Nickel particle composition, bonding material, and bonding method using the same - Google Patents

Description

The present invention relates to a nickel particle composition, a bonding material, and a bonding method using the same, which can be used for manufacturing electronic components.

  In recent years, high efficiency of power converters such as inverters has been promoted in efforts to save power. Among these, the practical application of SiC (silicon carbide) is being studied as a next-generation power device semiconductor material that can be expected to reduce loss. However, since the driving temperature of the current Si (silicon) power device is about 125 ° C, SiC is assumed to be 250 ° C or higher, so the bonding material for bonding the power semiconductor chip and the mounting substrate is reliable at high temperature driving. Sexuality is required.

  In addition, although a lead-free solder material is required by the RoHS directive enforced in the EU in 2006, a satisfactory material for a lead solder substitute material in a high temperature region has not yet been obtained.

  As a joining material that replaces solder, a metal having a small size has been studied extensively, centering on silver nanoparticles, utilizing the physical property of sintering at a temperature lower than that of bulk metal. On the other hand, fine metal particles are likely to aggregate due to their high surface activity, and it is necessary to coat the particles with an organic substance to ensure dispersion stability. When the particle coating has a large number of carbon atoms, the temperature for volatilizing the particle coating naturally rises, so that it is not suitable as a semiconductor packaging temperature.

In order to solve such a problem, Patent Document 1 proposes that an organic substance having 2 to 8 carbon atoms is used to coat metal particles having a thickness of 100 nm or less, and the organic substance is volatilized at a low temperature, and is coated with hexylamine or octylamine. It is exemplified that a bonding material using silver particles exhibits high bonding strength when heated at 250 ° C. Similarly, as an attempt of a low carbon number surface coating material, in Patent Document 2, an alcohol molecule residue having 1 to 9 or 11 carbon atoms, an alcohol molecule derivative (herein, an alcohol molecule derivative is a carboxylic acid, an aldehyde, or C _{n. -1} H _2n-1 COO) or a metal paste containing composite silver nanoparticles formed with an organic coating layer composed of one or more alcohol molecules has been proposed.

  A method for defining metal particles suitable as a bonding material has also been proposed. For example, Patent Document 3 discloses a method for determining the quality of sinterability of a particle by conducting thermal differential-thermogravimetric simultaneous measurement (TG-DTA) of pyrolysis of metal particle organic coating. Yes. Specifically, the sinterability is excellent when the pyrolysis temperature of the organic substance is lower than the intrinsic pyrolysis temperature of the organic substance due to the catalytic action of the metal, and the activation energy in the pyrolysis is less than 95 kJ / mol. It is said that. Furthermore, in Patent Document 4, the silver particles that give a silver sintered body having excellent electrical and thermal conductivity are defined as non-spherical silver particles having a carbon content of 1.0% by weight or less. Converts carbon in organic compounds adhering to silver particles to carbon dioxide by heating in an oxygen stream, measures the amount of carbon dioxide by infrared absorption spectroscopy, and converts the amount of carbon dioxide to carbon Is what you want.

  The above-mentioned Patent Documents 1, 2 and 4 are examples of good low-temperature sintering using silver fine particles as an example, and no examples are shown in which particles such as nickel, which are less expensive than silver, are sintered. Furthermore, in Patent Document 3, it is determined that sinterability is inferior to silver particles from the thermal decomposition temperature and activation energy of organic matter by measuring a thermal differential balance of flaky nickel particles under an air stream, In the joining test by firing in a reducing atmosphere containing 10% hydrogen, it is exemplified that the joining strength cannot be measured.

Japanese Patent No. 4872663 Japanese Patent No. 5306322 Japanese Patent No. 4633857 Japanese Patent No. 4353380

  An object of the present invention is to use a nickel layer that is cheaper than a precious metal, and achieve a good sintered state at a temperature within a range of 250 to 350 ° C., for example, so that a sufficient bonding strength can be obtained. Is to form.

  The present inventor has an average primary particle diameter in the range of 30 to 150 nm, the particle surface is coated with an organic compound, and the carbon content per specific surface area is in the range of 0.100 to 0.160. It was found that a good particle sintering state can be achieved even between 250 ° C. and 350 ° C. by using the nickel fine particles.

The nickel particle composition of the present invention comprises the following components A and B;
A) Nickel particles having an average particle diameter by laser diffraction / scattering in the range of 0.5 to 20 μm and containing 99% by weight or more of nickel element,
B) The average primary particle diameter by scanning electron microscope observation is in the range of 30 to 150 nm, the particle surface is coated with an organic compound, and the following formula:
Carbon content per specific surface area = [Carbon content by elemental analysis of nickel fine particles (wt%)]
/ [Specific surface area (m ² / g) obtained by calculation based on average primary particle size]
Nickel fine particles having a carbon content per specific surface area determined in the range of 0.100 to 0.160,
Containing
Furthermore, the total amount of carbon contained in Component A and Component B is in the range of 0.30 to 1.40% by weight.

  The nickel fine particles of the present invention are obtained by simultaneous differential heat / thermogravimetric measurement at a heating rate of 5 ° C./min in an atmosphere consisting of a mixed gas of hydrogen gas and nitrogen gas containing hydrogen gas at a volume ratio of 3%. The weight reduction rate may be less than 0.05% / min at a temperature up to 265 ° C.

  In the nickel composition of the present invention, the weight ratio of the component A and the component B (component A: component B) may be in the range of 30:70 to 70:30.

  The bonding material of the present invention is a bonding material containing any one of the above nickel particle compositions, and the content of the nickel composition may be in the range of 70 to 96% by weight.

  The bonding material of the present invention may contain an organic solvent having a boiling point in the range of 100 to 300 ° C., and the content of the organic solvent may be in the range of 4 to 30% by weight.

  The bonding material of the present invention may contain an organic binder component.

  In the bonding method of the present invention, any one of the above-described bonding materials is interposed between the members to be bonded and heated at a temperature in the range of 250 to 350 ° C. in a reducing gas atmosphere containing a reducing gas. A bonding layer may be formed between the members to be bonded.

  According to the nickel fine particles, nickel particle composition, bonding material, and bonding method of the present invention, a good sintered state can be achieved at a temperature of 250 to 350 ° C. without using a noble metal such as silver, and sufficient bonding strength. Can be formed.

It is drawing which shows the joining material preparation process, analysis, and evaluation process in an Example.

  Hereinafter, embodiments of the present invention will be described.

[Nickel particle composition]
The nickel particle composition of the present invention comprises the following components A and B;
A) Nickel particles having an average particle diameter by laser diffraction / scattering in the range of 0.5 to 20 μm and containing 99% by weight or more of nickel element,
B) The average primary particle diameter by scanning electron microscope observation is in the range of 30 to 150 nm, the particle surface is coated with an organic compound, and the following formula:
Carbon content per specific surface area = [Carbon content by elemental analysis of nickel fine particles (wt%)]
/ [Specific surface area (m ² / g) obtained by calculation based on average primary particle size]
Nickel fine particles having a carbon content per specific surface area determined in the range of 0.100 to 0.160,
Containing
Furthermore, it is the nickel composition whose sum total of the carbon content contained in the said component A and the component B exists in the range of 0.30-1.40 weight%.

(Component A: Nickel particles)
From the viewpoint of suppressing volume shrinkage during the formation of the bonding layer by heating, the nickel particles of component A have an average particle diameter in the range of 0.5 to 20 μm by the laser diffraction / scattering method. When the average particle diameter is less than 0.5 μm, the volume shrinkage increases when the bonding layer is formed by heating, and the objects to be bonded are not sufficiently bonded to each other. On the other hand, when the average particle diameter exceeds 20 μm, it is difficult to adjust the coating property on the bonded body and to adjust the bonding layer thickness.

  In addition, the nickel particles of component A may be appropriately selected according to the purpose of use, and the content of nickel element may be appropriately selected. In order to exhibit the effects of the present invention with respect to 100 parts by weight of all metal elements, nickel element It is most preferable to contain 99% by weight or more. For example, the nickel element content of 99.0% by weight or more is based on the amount of nickel element generally contained in commercially available nickel particles. Other contained components may include impurity metals in addition to oxygen and carbon. In addition, since the sinterability of nickel particles is affected by the properties of the surface or surface layer of the nickel particles, from this point of view, the nickel particles have a core (shell) containing nickel element and a core made of a different metal. It may have a multilayer structure such as a core-shell structure composed of (central part), or a structure in which the concentration of nickel element in the surface layer part of nickel particles is higher than that in the central part and the concentration of different metals is high in the central part You may have. In the case of such a structure, the nickel element is preferably contained in an amount of 50% by weight or more, more preferably 75% by weight or more, and still more preferably 90% by weight or more with respect to all the metal elements in the surface layer portion. . Therefore, since the concentration of nickel element can be inclined to the surface layer portion of the nickel particles, the content of nickel element can be about 10 parts by weight with respect to 100 parts by weight of all metal elements.

  The nickel particles of component A can be used regardless of the production method. As the nickel particles of component A, for example, commercially available products such as [Product name: Nickel (powder)] manufactured by Kanto Chemical Co., Ltd. and [Product name: Nickel] manufactured by Sigma-Aldrich Japan GK can be preferably used.

(Component B: Nickel fine particles)
The nickel fine particles of component B have an average primary particle diameter in the range of 30 to 150 nm as observed with a scanning electron microscope. When the average primary particle size of the nickel fine particles is less than 30 nm, the nickel fine particles are likely to aggregate, and uniform mixing with the component A nickel particles becomes difficult. On the other hand, when the average primary particle diameter of the nickel fine particles exceeds 150 nm, the sintering ability between the nickel fine particles or between the nickel fine particles and the nickel particles is insufficient during low-temperature firing at 350 ° C. or less, resulting in a decrease in bonding strength. In addition, in this specification, the average particle diameter of the primary particles of the nickel fine particles, including the values used in the examples, is a photograph of a sample by a field emission scanning electron microscope (FE-SEM). Is a value calculated based on the number of particles, which is obtained by randomly extracting 200 images from each of the images, obtaining the respective areas, and converting them into true spheres.

  The nickel fine particles of component B may be appropriately selected according to the purpose of use, and the content of nickel element may be appropriately selected. The amount of nickel element is preferably 50 parts by weight or more with respect to 100 parts by weight of all metal elements. More preferably 75 parts by weight or more, still more preferably 90 to 99.0% by weight. For example, when using nickel fine particles produced by a wet reduction method or nickel fine particles that have been subjected to a dispersion treatment as Component B, if the average primary particle diameter is within the range of 30 to 150 nm, the surface coating carbon or In the presence of passive oxygen, the content of nickel element becomes the above value. In addition, since the sinterability of the nickel fine particles is affected by the properties of the surface of the nickel fine particles or the surface layer portion, from this point of view, the nickel fine particles are composed of a shell containing a nickel element and a core made of a different metal. It may have a multilayer structure such as a core-shell structure composed of (central part), or a structure in which the concentration of nickel element in the surface layer part of nickel fine particles is higher than that in the central part and the concentration of different metals is high in the central part You may have. In the case of such a structure, the nickel element is preferably contained in an amount of 50% by weight or more, more preferably 75% by weight or more, and still more preferably 90% by weight or more with respect to all the metal elements in the surface layer portion. . Therefore, since the concentration of nickel element can be inclined to the surface layer portion of the nickel fine particles, the content of nickel element can be about 10 parts by weight with respect to 100 parts by weight of all metal elements.

  The nickel fine particles of component B may contain a metal other than nickel, but the content is most preferably in the range of 1 to 10% by weight. Examples of metals other than nickel include, for example, base metals such as tin, titanium, cobalt, copper, chromium, manganese, iron, zirconium, tungsten, molybdenum, vanadium, gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, A metal element such as a noble metal such as rhenium can be given. These may be contained alone or in combination of two or more.

(Carbon amount per specific surface area of nickel fine particles)
In order to ensure the dispersibility in the solvent of the component B nickel fine particles, the particle surface must be coated with organic molecules. At the same time, the particle surface organics volatilize upon firing and must be removed from the particle surface. Insufficient volatilization of the organic matter is undesirable because the sintering of the nickel fine particles or between the nickel fine particles and the nickel particles is hindered. Usually, the smaller the particle size (the larger the specific surface area), the greater the weight content of the surface organic component in the nickel fine particles. Therefore, in the present invention, the carbon content per specific surface area defines a suitable carbon content that achieves both dispersibility and particle sinterability. That is:
Carbon content per specific surface area = [Carbon content by elemental analysis of nickel fine particles (wt%)]
/ [Specific surface area (m ² / g) obtained by calculation based on average primary particle size]
It is preferable that the carbon content per specific surface area given by is in the range of 0.100 to 0.160. When the carbon content per specific surface area is less than 0.100, nickel fine particle dispersibility in the solvent is not ensured, and fine particle aggregates are generated. In addition, bonding failure occurs and cannot be used. Further, when the carbon content per specific surface area is larger than 0.160, as described above, particle sintering is hindered, which is not suitable.

(Differential heat and thermogravimetric measurement of nickel fine particles)
By removing the coating organic matter and nickel oxide on the surface of the nickel fine particles by firing, the nickel metal surface is exposed, and sintering of the target nickel fine particles or sintering with the nickel particles proceeds. The thermal behavior at which the above components are removed can be examined by simultaneous thermo-differential-differential thermal analysis (TG-DTA). The minimum temperature required for sintering of nickel fine particles is determined from the measurement results. Can also grasp.

  The TG-DTA measurement atmosphere must be a mixed gas of a reducing gas and an inert gas of several volume% or more as in the actual bonding test. Here, it is preferable to use hydrogen gas as the reducing gas, for example, preferably containing hydrogen gas in a volume ratio of 1 to 4%, and hydrogen gas and nitrogen containing hydrogen gas in a volume ratio of 3%. A gas mixed gas is particularly preferably used. In the case of only an inert gas that does not contain any reducing gas, a reduction reaction does not occur on the nickel fine particles, so that an accurate thermal behavior cannot be examined. Furthermore, the temperature at which the carbon component is removed may be detected at a high temperature of 10 ° C. or higher with only the inert gas. Also, when an oxidizing gas such as oxygen is contained, the weight increase due to the progress of the oxidation reaction of the nickel fine particles occurs, which is not suitable for examining the thermal behavior.

  The rate of temperature rise during TG-DTA measurement is preferably 5 ° C./min or less, and more preferably 5 ° C./min. As the rate of temperature increase is faster, the weight loss when the carbon component and oxygen component are removed is observed at a higher temperature or in a wider temperature range, so the exact behavior is often unknown.

  In order to realize sintering between nickel fine particles between 250 ° C. and 350 ° C., or a good sintered state of nickel fine particles and nickel particles, 265 ° C. when TG-DTA was measured on the nickel fine particles under the above conditions. It is preferable that the weight reduction rate is less than 0.05% / min at temperatures up to. When the weight reduction rate is 0.05% / min or more, it indicates that the removal of surface organic matter is in progress even at a temperature higher than 265 ° C., and such nickel fine particles are not suitable for low-temperature sintering.

(Method of synthesizing nickel fine particles)
The nickel fine particles of component B can be used regardless of the production method, but those obtained by a known method in which nickel ions are heated and reduced by a wet reduction method from a mixture containing a nickel salt and an organic amine are preferable. (For example, see Patent Document 1). Here, an example of a method for producing nickel fine particles by a wet reduction method will be described.

The production of nickel fine particles by the wet reduction method includes the following step 1 and step 2;
Step 1) A complexing reaction solution generating step of obtaining a complexing reaction solution by heating a mixture containing nickel carboxylate and a primary amine to a temperature within a range of 100 ° C. to 165 ° C.,
as well as,
Step 2) Nickel to obtain a slurry of nickel fine particles coated with primary amine by heating the complexing reaction liquid to a temperature of 170 ° C. or higher by microwave irradiation to reduce nickel ions in the complexing reaction liquid A fine particle slurry generating step.

Step 1) Complexation reaction solution generation step:
(Nickel carboxylate)
The nickel carboxylate (nickel salt of carboxylic acid) is not limited to the type of carboxylic acid. For example, the carboxyl group may be a monocarboxylic acid having one carboxyl group, or a carboxylic acid having two or more carboxyl groups. It may be. Moreover, acyclic carboxylic acid may be sufficient and cyclic carboxylic acid may be sufficient. As such nickel carboxylate, nickel acyclic monocarboxylate can be suitably used, and among nickel acyclic monocarboxylate, nickel formate, nickel acetate, nickel propionate, nickel oxalate, benzoic acid It is more preferable to use nickel or the like. By using these nickel acyclic monocarboxylates, for example, the resulting nickel fine particles are less likely to have a variation in shape and are easily formed as a uniform shape. The nickel carboxylate may be an anhydride or a hydrate.

(Primary amine)
The primary amine can form a complex with nickel ions, and effectively exhibits a reducing ability for nickel complexes (or nickel ions). On the other hand, secondary amines have great steric hindrance and may hinder the good formation of nickel complexes. Since tertiary amines do not have the ability to reduce nickel ions, none can be used alone. When these are used, these may be used in combination as long as the shape of the nickel fine particles to be produced is not hindered. The primary amine is not particularly limited as long as it can form a complex with nickel ions, and can be a solid or liquid at room temperature. Here, room temperature means 20 ° C. ± 15 ° C. The primary amine that is liquid at room temperature also functions as an organic solvent for forming the nickel complex. In addition, even if it is a primary amine solid at normal temperature, there is no particular problem as long as it is liquid by heating at 100 ° C. or higher, or can be dissolved using an organic solvent.

  The primary amine may be an aromatic primary amine, but an aliphatic primary amine is preferred from the viewpoint of easy nickel complex formation in the reaction solution. The aliphatic primary amine can control the particle diameter of the nickel fine particles produced by adjusting the length of the carbon chain, for example, the nickel fine particles having an average primary particle diameter in the range of 30 nm to 150 nm. This is advantageous when manufacturing. From the viewpoint of controlling the particle diameter of the nickel fine particles, the aliphatic primary amine is preferably selected from those having about 6 to 20 carbon atoms. The larger the carbon number, the smaller the particle size of the nickel fine particles obtained. Examples of such amines include octylamine, trioctylamine, dioctylamine, hexadecylamine, dodecylamine, tetradecylamine, stearylamine, oleylamine, myristylamine, and laurylamine. For example, oleylamine exists in a liquid state under the temperature conditions in the nickel fine particle production process, and therefore the reaction can proceed efficiently in a homogeneous solution.

Since the primary amine functions as a surface modifier during the production of the nickel fine particles, secondary aggregation can be suppressed even after removal of the primary amine. The primary amine is preferably liquid at room temperature from the viewpoint of ease of processing operation in the washing step of separating the solid component of the nickel fine particles produced after the reduction reaction and the solvent or unreacted primary amine. . Further, the primary amine is preferably one having a boiling point higher than the reduction temperature from the viewpoint of ease of reaction control when the nickel complex is reduced to obtain nickel fine particles. That is, the aliphatic primary amine preferably has a boiling point of 180 ° C. or higher, more preferably 200 ° C. or higher, and preferably has 9 or more carbon atoms. Here, for example, the boiling point of C ₉ H ₂₁ N (nonylamine) of an aliphatic amine having 9 carbon atoms is 201 ° C. The amount of primary amine is preferably 2 mol or more, more preferably 2.2 mol or more, and more preferably 4 mol or more with respect to 1 mol of nickel. When the amount of primary amine is less than 2 mol, it is difficult to control the particle diameter of the obtained nickel fine particles, and the particle diameter tends to vary. The upper limit of the amount of primary amine is not particularly limited, but is preferably 20 mol or less from the viewpoint of productivity, for example.

(Organic solvent)
In step 1, an organic solvent different from the primary amine may be newly added in order to allow the reaction in the homogeneous solution to proceed more efficiently. When an organic solvent is used, the organic solvent may be mixed simultaneously with the nickel carboxylate and the primary amine. However, when the organic solvent is added after first mixing the nickel carboxylate and the primary amine to form a complex, It is more preferable because it efficiently coordinates to a nickel atom. The organic solvent that can be used is not particularly limited as long as it does not inhibit the complex formation between the primary amine and the nickel ion. For example, the organic solvent having 4 to 30 carbon atoms, 7 to 30 carbon atoms, and the like. A saturated or unsaturated hydrocarbon organic solvent, an alcohol organic solvent having 8 to 18 carbon atoms, or the like can be used. Moreover, from the viewpoint of enabling use even under heating conditions by microwave irradiation, it is preferable to select an organic solvent having a boiling point of 170 ° C. or higher, more preferably in the range of 200 to 300 ° C. It is better to choose one. Specific examples of such an organic solvent include tetraethylene glycol and n-octyl ether.

  Although the complex formation reaction can proceed even at room temperature, in order to perform a sufficient and more efficient complex formation reaction, the reaction is carried out by heating to a temperature in the range of 100 ° C. to 165 ° C. This heating is particularly advantageous when nickel carboxylate hydrate such as nickel formate dihydrate or nickel acetate tetrahydrate is used as nickel carboxylate. The heating temperature is preferably a temperature exceeding 100 ° C., more preferably a temperature of 105 ° C. or more, so that the ligand substitution reaction between the coordinating water coordinated with nickel carboxylate and the primary amine is efficient. The water molecule as the complex ligand can be dissociated, and the water can be discharged out of the system, so that the complex can be formed efficiently. For example, nickel formate dihydrate has a complex structure in which two coordination waters and two formate ions as bidentate ligands exist at room temperature. In order to efficiently form a complex by substituting a ligand for a primary amine, it is preferable to dissociate the water molecule as the complex ligand by heating at a temperature higher than 100 ° C. In addition, the heat treatment in the complex formation reaction between nickel carboxylate and primary amine is surely separated from the subsequent heat reduction process by microwave irradiation of the nickel complex (or nickel ion) to complete the complex formation reaction. In view of the above, the temperature is set to the upper limit temperature or lower, preferably 160 ° C. or lower, more preferably 150 ° C. or lower.

  The heating time can be appropriately determined according to the heating temperature and the content of each raw material, but is preferably 10 minutes or more from the viewpoint of completing the complex formation reaction. There is no upper limit on the heating time, but heat treatment for a long time is useless from the viewpoint of saving energy consumption and process time. The heating method is not particularly limited, and may be heating by a heat medium such as an oil bath or heating by microwave irradiation.

  The complex formation reaction between nickel carboxylate and primary amine can be confirmed by a change in the color of the solution when a solution obtained by mixing nickel carboxylate and primary amine in an organic solvent is heated. . In addition, this complex formation reaction is carried out by measuring the absorption maximum wavelength of the absorption spectrum observed in the wavelength region of 300 nm to 750 nm using, for example, an ultraviolet / visible absorption spectrum measuring apparatus, and measuring the maximum absorption wavelength of the raw material (for example, nickel formate). In dihydrate, the maximum absorption wavelength is 710 nm, and in nickel acetate tetrahydrate, the maximum absorption wavelength is 710 nm.) The shift of the complexing reaction solution (the maximum absorption wavelength shifts to 600 nm) is observed. Can be confirmed.

  After the complex formation between nickel carboxylate and primary amine is performed, the resulting reaction solution is heated by microwave irradiation to reduce the nickel ions of the nickel complex as described below. At the same time, the carboxylate ions coordinated in the nuclei are decomposed, and finally nickel fine particles containing nickel having an oxidation number of 0 are generated. In general, nickel carboxylate is hardly soluble under conditions other than using water as a solvent, and a solution containing nickel carboxylate needs to be a homogeneous reaction solution as a pre-stage of the heat reduction reaction by microwave irradiation. On the other hand, the primary amine used in the present embodiment is liquid under the operating temperature conditions, and is considered to be liquefied by coordination with nickel ions to form a homogeneous reaction solution.

Step 2) Nickel fine particle slurry generation step:
In this step, the complexing reaction solution obtained by the complexation reaction between nickel carboxylate and primary amine is heated to a temperature of 170 ° C. or higher by microwave irradiation to reduce nickel ions in the complexing reaction solution. To obtain a nickel fine particle slurry coated with a primary amine. The temperature for heating by microwave irradiation is preferably 180 ° C. or higher, more preferably 200 ° C. or higher, from the viewpoint of suppressing variation in the shape of the obtained nickel fine particles. The upper limit of the heating temperature is not particularly limited, but is preferably set to 270 ° C. or less, for example, from the viewpoint of efficiently performing the treatment. In addition, the use wavelength of a microwave is not specifically limited, For example, it is 2.45 GHz. The heating temperature can be appropriately adjusted depending on, for example, the type of nickel carboxylate and the use of an additive that promotes the nucleation of nickel fine particles.

  In this step, since microwaves penetrate into the reaction solution, uniform heating is performed, and energy can be directly applied to the medium, so that rapid heating can be performed. As a result, the entire reaction solution can be made uniform at a desired temperature, and the processes of reduction, nucleation, and nucleation of the nickel complex (or nickel ions) can occur simultaneously in the entire solution. Narrow monodisperse particles can be easily produced in a short time.

  In order to generate nickel fine particles having a uniform particle size, the nickel complex is uniformly and sufficiently generated in the complexing reaction liquid generating step (step in which the nickel complex is generated) in step 1; In the nickel fine particle slurry generation step, it is necessary to simultaneously generate and grow nickel (zero-valent) nuclei generated by reduction of the nickel complex (or nickel ions). In other words, by adjusting the heating temperature in the complexing reaction liquid production step within the above specific range and ensuring that it is lower than the microwave heating temperature in the nickel fine particle slurry production step, the particle size and shape are adjusted. Particles are easily generated. For example, if the heating temperature is too high in the complexing reaction liquid generation step, the formation of nickel complex and the reduction reaction to nickel (zero valence) proceed simultaneously, and new nuclei are generated, so that in the nickel fine particle slurry generation step There is a possibility that it is difficult to generate particles having a uniform particle shape. In addition, if the heating temperature in the nickel fine particle slurry generation process is too low, the reduction reaction rate to nickel (zero valence) is slowed and the generation of nuclei is reduced, so that not only the particles are enlarged, but also in terms of the yield of nickel fine particles. Is also not preferred.

  The nickel fine particle slurry obtained by heating by microwave irradiation is, for example, left and separated, and after removing the supernatant liquid, washed with an appropriate solvent and dried to obtain nickel fine particles. In the nickel fine particle slurry production step, the organic solvent described above may be added as necessary. As described above, the primary amine used for the complex formation reaction is preferably used as it is as the organic solvent.

  As described above, nickel fine particles having an average primary particle diameter in the range of 30 to 150 nm can be prepared.

(Compounding ratio in nickel particle composition)
The total amount of carbon contained in component A and component B in the nickel particle composition must be in the range of 0.30 to 1.40% by weight. Since the amount of carbon in the nickel particle composition is mostly the surface organic matter in the nickel fine particles of component B, the compounding ratio of component A and component B can be expressed by the amount of carbon. When the amount of carbon is less than 0.30% by weight, the blending ratio of the component B nickel fine particles responsible for particle sintering is insufficient. Insufficient strength occurs. Further, when the carbon content is higher than 1.40% by weight, the number of sintered parts due to the nickel fine particles increases, and the volume shrinkage of the entire bonding layer becomes excessive, so that sufficient bonding strength cannot be obtained.

  In the nickel particle composition, the weight ratio of component A and component B (component A: component B) is more preferably in the range of 30:70 to 70:30, and good bonding strength is achieved within the above range. Is done.

(Nickel particulate coating organic component)
The organic compound covering the nickel fine particles preferably contains a functional group capable of interacting with the nickel fine particles. Examples of such a functional group include an alcohol group, an amino group, a sulfanyl group, a carboxyl group, and a carbonyl group.

  From the viewpoint of achieving both low-temperature volatility and dispersibility of nickel fine particles, the organic compound covering the nickel fine particles is preferably within the range of 6 to 17 carbon atoms, more preferably within the range of 6 to 12 carbon atoms. Fatty acids in are good. When the number of carbon atoms of the fatty acid is 5 or less, the distance between the nickel metal surfaces of the nickel fine particles becomes close and aggregation tends to occur. Moreover, when the number of carbon atoms of the fatty acid is 18 or more, the organic compound is not sufficiently volatilized even at a temperature exceeding 250 ° C., and there is a concern that sintering may be inhibited by carbonizing on the particle surface.

(Coating treatment with organic compounds)
The nickel fine particles can be coated with an organic compound, for example, by subjecting the nickel fine particles to a slurry state with an organic solvent for surface treatment. The slurry can be produced, for example, by mixing nickel fine particles and an organic solvent and stirring. The stirring method is not particularly limited, and examples thereof include a method using ultrasonic waves, a method using a mechanical stirrer, a paint shaker, and the like, but these stirring units can be applied even after the addition of the organic compound. Moreover, you may crush, such as a jet mill and a ball mill, as needed.

  As the organic solvent used in the coating treatment of the organic compound, a solvent in which the aggregation of the nickel fine particles is suppressed and the covering organic compound is compatible with the organic solvent is used. Examples of such solvents include organic solvents that are immiscible with water. Specific examples thereof include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene, hexane, heptane, decane, octane, heptane, cyclohexane, and methyl. Aliphatic hydrocarbon solvents such as cyclohexane and ethylcyclohexane, ester solvents such as ethyl acetate and butyl acetate, long chain alcohol solvents such as α-terpineol and butyl carbitol, esters of long chain alcohols and carboxylic acids, etc. Can be mentioned. Also, organic solvents other than the above organic solvents can be used as long as the nickel fine particles do not aggregate.

  The amount of the organic compound added is preferably excessive with respect to the amount that can be coated on the nickel fine particles, and is preferably added, for example, about 2 to 100% by weight with respect to the amount of nickel in the nickel fine particle slurry. Moreover, it is preferable to wash the excess organic compound which was not coat | covered on the surface of nickel fine particle with an organic solvent. The organic solvent is preferably compatible with the coating organic component, and the above organic solvents can be used. For example, hydrocarbon solvents such as octane and nonpolar aromatic solvents such as toluene and xylene are particularly preferable. .

(Joining material)
The bonding material of the present embodiment contains the nickel particle composition. The bonding material of the present embodiment can further contain an organic solvent having a boiling point in the range of 100 to 300 ° C. The joining material is preferably concentrated after adding a high-boiling organic solvent to form a paste. The boiling point of the solvent contained in the bonding material is preferably in the range of 150 to 260 ° C. from the viewpoint of practical use. If the boiling point of the organic solvent used is less than 100 ° C, long-term stability tends to be lacking. If the boiling point exceeds 300 ° C, residual carbon is generated in the joining layer without volatilization during heating, and the particles are sintered. And tends to inhibit the formation of intermetallic compounds.

  As the solvent having a boiling point in the range of 100 to 300 ° C., for example, alcohol solvents, aromatic solvents, hydrocarbon solvents, ester solvents, ketone solvents, ether solvents and the like can be used. Examples of alcohol solvents include 1-heptanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, 1-nonanol, 3,5,5-trimethyl-1-hexanol, 1-decanol, 1-decanol, C7 or more aliphatic alcohols such as undecanol, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, tetramethylene glycol, Polyhydric alcohols such as methyl triglycol, terpineols such as α-terpineol, β-terpineol, and γ-terpineol, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, methylmethoxybutanol, die Glycol, dipropylene glycol, 2-phenoxyethanol, it can be mentioned alcohols having an ether group such as 1-phenoxy-2-propanol. Examples of the hydrocarbon solvent include octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, and pentadecane. Among these, 1-undecanol and tetradecane are preferable, and it is more preferable that 1-undecanol and / or tetradecane are contained in the range of 15 wt% to 50 wt% with respect to the total organic solvent. When 1-undecanol and / or tetradecane are used, it is more preferable to use terpineol in the range of 30% by weight to 85% by weight with respect to the total organic solvent.

  The content of the nickel particle composition in the bonding material is, for example, in the range of 70 to 96% by weight, and preferably in the range of 85 to 95% by weight. If the content of the nickel particle composition is less than 70% by weight, the thickness of the bonding layer may be reduced. For example, it may be necessary to repeat coating several times, resulting in unevenness and sufficient bonding strength. It may not be possible. On the other hand, if the content of the nickel particle composition exceeds 96% by weight, the fluidity as a paste is lost, and the usability may be lowered, such as difficulty in coating.

  The content of the organic solvent in the bonding material of the present embodiment is, for example, in the range of 4 to 30% by weight, and preferably in the range of 5 to 15% by weight. When the content of the organic solvent in the bonding material is less than 4% by weight, the fluidity may be lowered and the usability as the bonding material may be reduced. On the other hand, when the content of the organic solvent exceeds 30% by weight, for example, it becomes necessary to repeat coating several times, which may cause unevenness, and sufficient bonding strength may not be obtained.

  The bonding material of this embodiment preferably contains an organic binder. The organic binder has the effect of connecting the nickel particles of component A and the nickel fine particles of component B and placing them in close proximity to make the bonding layer agglomerated. Since the nickel particle composition of the present embodiment includes micrometer-sized particles and nanometer-sized fine particles, due to the difference in particle size, aggregation is less likely to occur compared to uniform particles, and there are few contacts between the particles. When an organic binder is added thereto, the connection between the particles is formed over a wide range. And a massive joint layer having high joint strength can be obtained by firing while maintaining a wide range of connection between the nickel particles of component A and the nickel fine particles of component B by the organic binder.

  As the organic binder, any binder that can be dissolved in an organic solvent can be used without particular limitation. 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 a polyethylene resin. And thermoplastic resins such as acrylic resin, methacrylic resin, nylon resin, acetal resin, and polyvinyl acetal resin. 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 unit in the molecule is more preferable.

  For example, the organic binder preferably has a molecular weight of 30000 or more, more preferably 100000 or more in order to suppress sedimentation of the nickel particles of component A and the nickel fine particles of component B and maintain a sufficiently dispersed state.

  As the organic binder, for example, commercially available products such as Sekisui Chemical Co., Ltd. polyvinyl acetal resin (ESREC BH-A; trade name) can be preferably used.

  In addition to the above components, the bonding material of the present embodiment can contain, for example, a thickener, a thixotropic agent, a leveling agent, a surfactant, and the like as optional components.

(Joining method)
In the joining method of the present embodiment, the joining material is interposed between the members to be joined and heated at a temperature in the range of 250 to 350 ° C. in a reducing gas atmosphere containing a reducing gas. A bonding layer is formed between the members to be bonded. In order to advance the sintering between the nickel fine particles and between the nickel fine particles and the nickel particles, it is considered necessary to expose the nickel fine particles and the metal surfaces of the nickel particles. The heating temperature for volatilizing or decomposing organic substances present on the surface of the nickel fine particles is preferably 250 ° C. or higher. Furthermore, by heating in a reducing gas atmosphere, the passive layers on the surfaces of both the nickel fine particles and the nickel particles are formed. Can be removed. On the other hand, if the heating temperature exceeds 350 ° C., the periphery of the semiconductor device as the bonded member may be damaged. As the reducing gas, hydrogen gas is preferably used. For example, hydrogen gas is preferably contained at a volume ratio of 1 to 4%, and a mixture of hydrogen gas and nitrogen gas containing hydrogen gas at a volume ratio of 3% is preferable. Gas is particularly preferably used.

  In the bonding method of the present embodiment, for example, a step of applying a paste-like bonding material to one or both bonded surfaces of a pair of bonded members (application step), the bonded surfaces are bonded together, for example, a temperature of 250 By heating within the range of -350 degreeC, the process (baking process) of sintering a joining material can be included.

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

  Further, the firing step can be performed by pressing the members to be joined at, for example, 10 MPa or less, preferably 1 MPa or less, or more preferably without applying pressure. By carrying out in a non-pressurized state, the operation | work in a baking process can be simplified and also the damage by the pressurization of a to-be-joined member can be reduced.

  The bonding method of the present embodiment can be used, for example, in the bonding of Si or SiC semiconductor materials or in the manufacturing process of electronic components. Here, examples of the electronic component mainly include a semiconductor device and an energy conversion module component. 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, between the power device or the power module and the heat dissipation member. It can be applied to joining.

  When bonding electronic components, in order to increase the bonding strength, for example, a contact metal layer made of a material such as Au, Cu, Pd, Ni, Ag, Cr, Ti or an alloy thereof is previously formed on one or both of the surfaces to be bonded. Is preferably provided. When the material of the surface to be joined is SiC or Si or an oxide film on the surface thereof, a contact metal 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.

The features of the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of average particle diameter of component A]
The average particle diameter of the nickel particles used as component A was measured by a laser diffraction / scattering method. The apparatus used was LMS-30 manufactured by Seishin Co., Ltd., and measurement was performed in a flow cell using water as a dispersion medium.

[Measurement of Average Particle Size of Component B]
The average particle diameter of component B (nickel fine particles) was measured by taking a picture of a sample with a field emission scanning electron microscope (FE-SEM), and randomly 200 samples were taken. The respective areas were extracted and the average particle diameter of primary particles was calculated based on the number of particles when converted to a true sphere.

[Calculation of specific surface area of component B nickel fine particles]
The specific surface area was calculated by the following formula.
Specific surface area of nickel fine particles (m ² / g) = 3 / d · r
[Where d means the specific gravity of nickel of 8.91 (g / cm ³ ), and r means the radius (nm) of the nickel fine particles determined by FE-SEM. ]

[Thermal analysis of nickel fine particles of component B]
It confirmed using the differential-thermal / thermogravimetric simultaneous measuring apparatus (Thermogravimetry-Differential Thermal Analysis: TG-DTA, Hitachi High-Tech Science Co., Ltd. make, brand name; TG / DTA7220). Measurement conditions were as follows: temperature rising condition: 5 ° C./min, gas flow: nitrogen / hydrogen = 97/3 volume ratio, mixed gas 200 ml / min.

[Measurement of carbon content in nickel fine particles and nickel composition]
Using 200 mg of nickel fine particles or nickel composition, the carbon content was measured with a combustion-infrared absorber (trade name; CS-444, manufactured by LECO).

[Baking method]
The sinterability test sample is fired using a small inert gas oven (trade name: KLO-30NH, manufactured by Koyo Thermo Systems Co., Ltd.) while flowing a mixed gas of 3% hydrogen and 97% nitrogen at a flow rate of 5 L / min. The temperature was raised from room temperature to 300 ° C. at a temperature rising rate of 5 ° C./min, and held for 1 hour. Next, the temperature was lowered to 50 ° C. over 400 minutes, and then left to room temperature.

[Evaluation of shear strength (shear strength)]
Using a stainless steel mask (mask width; 2.0 mm × length; 2.0 mm × thickness; 0.1 mm), the sample was gold-plated copper substrate (width; 10 mm × length; 10 mm × thickness; 0 mm) is applied to form a coating film, and then a silicon die (width: 2.0 mm × length; 2.0 mm × thickness: 0.40 mm) is mounted on the coating film and firing is performed. went. The shear strength of the obtained joined sample (joint layer thickness; about 50 μm) was measured with a joint strength tester (manufactured by Daisy Japan, trade name: Bond Tester 4000). A bond tester tool was pressed from the side of the die at a height of 50 μm from the substrate and a tool speed of 100 μm / second, and the load when the joint was sheared was determined as shear strength (shear strength). The gold-plated copper substrate is obtained by plating Ni / Au with a thickness of 4 μm / 40 to 50 nm on the surface of a Cu substrate (thickness: 1.0 mm), and the silicon die is a Si substrate (thickness). ; 0.40 mm) on the bonding surface, Au was sputtered.

(Synthesis Example 1)
To 642 parts by weight of oleylamine, 100 parts by weight of nickel acetate tetrahydrate was added and heated at 150 ° C. for 20 minutes under a nitrogen flow to dissolve nickel acetate to obtain a complexing reaction solution. Next, 492 parts by weight of oleylamine was added to the complexing reaction solution, and the mixture was heated at 250 ° C. for 5 minutes using a microwave to obtain a nickel fine particle slurry 1.

The nickel fine particle slurry 1 obtained in Synthesis Example 1 was allowed to stand and separated, the supernatant was removed, washed with toluene and methanol, and then dried for 6 hours in a vacuum dryer maintained at 60 ° C. The average primary particle diameter of the obtained nickel fine particles was 90 nm, and the specific surface area calculated according to [Calculation of specific surface area of nickel fine particles of component B] was 7.48 m ² / g.

(Synthesis Example 2)
18.5 parts by weight of nickel formate dihydrate was added to 182 parts by weight of oleylamine and heated at 120 ° C. for 10 minutes under a nitrogen flow to dissolve nickel formate to obtain a complexing reaction solution. Next, 121 parts by weight of oleylamine was added to the complexing reaction solution, and the mixture was heated at 180 ° C. for 10 minutes using a microwave to obtain a nickel fine particle slurry 2.

The nickel fine particle slurry 2 obtained in Synthesis Example 2 was allowed to stand and separated, the supernatant was removed, washed with toluene and methanol, and then dried for 6 hours in a vacuum dryer maintained at 60 ° C. The average primary particle diameter of the obtained nickel fine particles was 40 nm, and the specific surface area calculated according to [Calculation of specific surface area of nickel fine particles of component B] was 16.8 m ² / g.

(Synthesis Example 3)
To 642 parts by weight of oleylamine, 264 parts by weight of nickel acetate tetrahydrate was added and heated at 140 ° C. for 20 minutes under a nitrogen flow to dissolve nickel acetate to obtain a complexing reaction solution. Next, 492 parts by weight of oleylamine was added to the complexing reaction solution, and the mixture was heated at 250 ° C. for 12 minutes using a microwave to obtain a nickel fine particle slurry 3.

The nickel fine particle slurry 3 obtained in Synthesis Example 3 was allowed to stand and separated, the supernatant was removed, washed with toluene and methanol, and then dried for 6 hours in a vacuum dryer maintained at 60 ° C. The average primary particle diameter of the nickel fine particles obtained was 170 nm, and the specific surface area calculated according to [Calculation of specific surface area of nickel fine particles of component B] was 3.96 m ² / g.

Example 1
<Preparation of nickel fine particles 1, nickel composition 1, paste 1 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 1 obtained in Synthesis Example 1 is taken, 20 parts by weight of octanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 100 parts by weight of toluene are added thereto, and subjected to ultrasonic treatment for 15 minutes. Then, it was washed with toluene to prepare a nickel dispersion 1 (solid content concentration 68.1% by weight). Furthermore, a part of this was dried for 1 hour by a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 1. About the obtained nickel fine particle 1, carbon content was measured according to [Measurement of carbon content contained in nickel fine particle and nickel composition]. The amount of carbon was 1.12% by weight, and the amount of carbon per specific surface area was 0.150.

  193 parts by weight of the nickel dispersion 1 was fractionated, and 131 parts by weight of nickel particles 1 (manufactured by Kanto Chemical Co., Ltd., trade name: nickel (powder), average particle diameter by laser diffraction / scattering method; 9 0.8 μm, content of nickel element: 99 wt% or more based on the whole nickel particles), 6.91 parts by weight of α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd., boiling point: 220 ° C.), 6.91 parts by weight 1-undecanol (manufactured by Wako Pure Chemical Industries, Ltd., boiling point; 243 ° C.), 1.38 parts by weight of binder resin 1 (manufactured by Sekisui Chemical Co., Ltd., trade name: ESREC BH-A) are mixed in an evaporator. Then, the mixture was concentrated at 60 ° C. and 100 hPa to prepare 278 parts by weight of paste 1 (solid content concentration 94.5% by weight).

  TG-DTA was performed using the nickel fine particles 1 according to the above-mentioned [Thermal analysis of nickel fine particles of component B]. In the region of 230.2 ° C. or higher, the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 1 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 1. The nickel composition 1 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.58% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using paste 1, a joining test sample was prepared and the shear strength was evaluated. As a result, a good strength of 39.2 MPa was obtained. The results are shown in Table 1.

  An outline of the bonding material creation process, analysis, and evaluation process in Example 1 is shown in FIG.

(Example 2)
<Preparation of nickel composition 2 and paste 2, thermal analysis, carbon content analysis and bonding evaluation>
127 parts by weight of Nickel Dispersion 1 were fractionated, and 65.0 parts by weight of Nickel Particles 1 and 65.0 parts by weight of Nickel Particles 2 (manufactured by Sigma-Aldrich Japan G.K., trade name: Nickel, laser diffraction) / Average particle diameter by scattering method: 1.9 μm, content of nickel element: 99.8% by weight or more based on the whole nickel particles) 5.71 parts by weight of α-terpineol, 5.71 parts by weight of 1- Undecanol and 1.15 parts by weight of binder resin 1 were mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 229 parts by weight of paste 2 (solid content concentration 94.5% by weight).

  40 parts by weight of the nickel fine particles 1 and 30 parts by weight of the nickel particles 1 and the nickel particles 2 were fractionated to obtain a nickel composition 2. The nickel composition 2 was measured according to [Measurement of the amount of carbon contained in nickel fine particles and nickel composition]. The amount of carbon was 0.46% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using paste 2, a test sample was prepared and the shear strength was evaluated. As a result, a good strength of 32.7 MPa was obtained. The results are shown in Table 1.

(Example 3)
<Preparation of nickel fine particles 2, nickel composition 3, paste 3 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 2 obtained in Synthesis Example 2 was taken, and 20 parts by weight of octanoic acid and 100 parts by weight of toluene were added thereto, followed by sonication for 15 minutes, and then washed with toluene. Dispersion 2 (solid content concentration 70.0% by weight) was prepared. Further, a part of this was dried for 1 hour with a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 2. With respect to the obtained nickel fine particles 2, the carbon content was measured according to [Measurement of the amount of carbon contained in nickel fine particles and nickel composition]. The amount of carbon was 1.88% by weight, and the amount of carbon per specific surface area was 0.112.

  216 parts by weight of Nickel Dispersion 2 was fractionated into 151 parts by weight of nickel particles 1, 8.00 parts by weight of α-terpineol, 8.00 parts by weight of 1-undecanol, 1.61 parts by weight of Binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 320 parts by weight of paste 3 (solid content concentration 94.5% by weight).

  TG-DTA was carried out using the nickel fine particles 2 in accordance with the above [thermal analysis of nickel fine particles of component B]. In the region above 262.9 ° C., the weight loss was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 2 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 3. The nickel composition 3 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.92% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using the paste 3, a joining test sample was prepared and the shear strength was evaluated. As a result, a good strength of 30.2 MPa was obtained. The results are shown in Table 1.

(Example 4)
<Preparation of nickel fine particles 3, nickel composition 4, paste 4 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 1 obtained in Synthesis Example 1 is taken, and 20 parts by weight of 2-ethylhexanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 100 parts by weight of toluene are added thereto, and the mixture is added for more than 15 minutes. After sonication, it was washed with toluene to prepare a nickel dispersion 3 (solid content concentration 58.5% by weight). Further, a part of this was dried for 1 hour by a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 3. With respect to the obtained nickel fine particles 3, the carbon amount was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and the nickel composition]. The amount of carbon was 0.95% by weight, and the amount of carbon per specific surface area was 0.127.

  141 parts by weight of Nickel Dispersion 3 was fractionated, and 82.4 parts by weight of nickel particles 1, 4.38 parts by weight of α-terpineol, 4.38 parts by weight of 1-undecanol, 0.88 parts by weight. Part of the binder resin 1 was mixed and concentrated with an evaporator at 60 ° C. and 100 hPa to prepare 174 parts by weight of paste 4 (solid content concentration 94.5% by weight).

  TG-DTA was performed using the nickel fine particles 3 according to the above-mentioned [Thermal analysis of nickel fine particles of component B]. In the region of 222.5 ° C. or higher, the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  Nickel fine particles 3 and nickel particles 1 were separated by 50 parts by weight, and nickel composition 4 was obtained. The nickel composition 4 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.50% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using paste 4, a test sample was prepared and the shear strength was evaluated. As a result, a favorable strength of 22.1 MPa was obtained. The results are shown in Table 1.

(Example 5)
<Preparation of nickel fine particles 4, nickel composition 5, paste 5 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 1 obtained in Synthesis Example 1 is taken, 20 parts by weight of octylamine (manufactured by Wako Pure Chemical Industries, Ltd.) and 100 parts by weight of toluene are added thereto, and subjected to ultrasonic treatment for 15 minutes. Then, it was washed with toluene to prepare a nickel dispersion 4 (solid content concentration 73.5% by weight). Further, a part of this was dried for 1 hour by a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 4. About the obtained nickel fine particle 4, carbon content was measured according to [Measurement of carbon content contained in nickel fine particle and nickel composition]. The amount of carbon was 0.93% by weight, and the amount of carbon per specific surface area was 0.124.

  70.5 parts by weight of the nickel dispersion 4 was fractionated, and 51.8 parts by weight of nickel particles, 1.73 parts by weight of α-terpineol, 2.73 parts by weight of 1-undecanol, 55 parts by weight of binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 109 parts by weight of paste 5 (solid content concentration 94.5% by weight).

  TG-DTA was carried out using the nickel fine particles 4 in accordance with [Thermal analysis of nickel fine particles of component B]. In the region above 239.5 ° C., the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 4 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 5. The nickel composition 5 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.47% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using the paste 5, a joining test sample was prepared and the shear strength was evaluated. As a result, a good strength of 20.6 MPa was obtained. The results are shown in Table 1.

(Comparative Example 1)
<Preparation of Nickel Fine Particle 5, Nickel Composition 6, Paste 6 and Thermal Analysis, Carbon Content Analysis, Bonding Evaluation>
100 parts by weight of the nickel fine particle slurry 1 obtained in Synthesis Example 1 was taken, and 20 parts by weight of a liquid polymer having a carboxyl group (trade name; Act Flow, product number; 3060, molecular weight; 3000, manufactured by Soken Chemical Co., Ltd.) ), 100 parts by weight of toluene was added, subjected to ultrasonic treatment for 15 minutes, and then washed with toluene to prepare a nickel dispersion 5 (solid content concentration 68.2% by weight). Further, a part of this was dried for 1 hour with a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 5. About the obtained nickel fine particle 5, the carbon content was measured according to [Measurement of carbon content in nickel fine particle and nickel composition]. The carbon content was 1.79% by weight, and the carbon content per specific surface area was 0.239.

  105 parts by weight of the nickel dispersion 5 was fractionated, and 71.8 parts by weight of nickel particles 1, 3.80 parts by weight of α-terpineol, 3.80 parts by weight of 1-undecanol, 0.76 parts by weight. Part of binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 152 parts by weight of paste 6 (solid content concentration 94.5% by weight).

  TG-DTA was performed using the nickel fine particles 5 in accordance with the above [thermal analysis of nickel fine particles of component B]. In the region of 354.6 ° C. or higher, the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 5 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 6. This nickel composition 6 was measured according to [Measurement of the amount of carbon contained in nickel fine particles and nickel composition]. The amount of carbon was 0.89% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using paste 6, a joining test sample was prepared and the shear strength was evaluated. As a result, a sufficient joining strength of 5.2 MPa was not obtained. The results are shown in Table 1.

(Comparative Example 2)
<Preparation of nickel fine particles 6, nickel composition 7, paste 7 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 3 obtained in Synthesis Example 3 was taken, and 20 parts by weight of octanoic acid and 100 parts by weight of toluene were added thereto, followed by ultrasonic treatment for 15 minutes, and then washed with toluene. Dispersion 6 (solid content concentration 72.6% by weight) was prepared. Further, a part of this was dried for 1 hour by a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 6. About the obtained nickel fine particle 6, carbon content was measured according to [Measurement of carbon content in nickel fine particle and nickel composition]. The carbon content was 0.45% by weight, and the carbon content per specific surface area was 0.114.

  131 parts by weight of the nickel dispersion 6 was fractionated, and 95.1 parts by weight of nickel particles 1, 5.10 parts by weight of α-terpineol, 5.10 parts by weight of 1-undecanol, 1.02 parts by weight. Part of the binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 201 parts by weight of paste 7 (solid content concentration 94.5% by weight).

  TG-DTA was performed using the nickel fine particles 6 in accordance with the above-mentioned [Thermal analysis of nickel fine particles of component B]. In the region of 207.4 ° C. or higher, the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 6 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 7. The nickel composition 7 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.24% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shearing strength] using paste 7, a joining test sample was prepared and the shearing strength was evaluated. As a result, a joining strength of 0.5 MPa was hardly obtained. The results are shown in Table 1.

(Comparative Example 3)
<Preparation and thermal analysis of nickel composition 8 and paste 8 and bonding evaluation>
45.9 parts by weight of Nickel Dispersion 1 were fractionated into 125 parts by weight of nickel particles 1, 4.13 parts by weight of α-terpineol, 4.13 parts by weight of 1-undecanol, 0.83 parts by weight. Part of the binder resin 1 was mixed and concentrated with an evaporator at 60 ° C. and 100 hPa to prepare 165 parts by weight of paste 8 (solid content concentration 94.5% by weight).

  20 parts by weight of the nickel fine particles 1 and 80 parts by weight of the nickel particles 1 were taken to obtain a nickel composition 8. The nickel composition 8 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 0.23% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using paste 8, a joining test sample was prepared and the shear strength was evaluated. As a result, a sufficient joining strength of 3.6 MPa was not obtained. The results are shown in Table 1.

(Comparative Example 4)
<Preparation and thermal analysis of nickel composition 9 and paste 9 and bonding evaluation>
176 parts by weight of Nickel Dispersion 2 was fractionated, and 41 parts by weight of nickel particles 1, 4.34 parts by weight of α-terpineol, 4.34 parts by weight of 1-undecanol, 0.87 parts by weight of Binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 174 parts by weight of paste 9 (solid content concentration 94.5% by weight).

  75 parts by weight of the nickel fine particles 2 and 25 parts by weight of the nickel particles 1 were taken to obtain a nickel composition 9. The nickel composition 9 was measured according to [Measurement of the amount of carbon contained in the nickel fine particles and nickel composition]. The amount of carbon was 1.43% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shear strength] using the paste 9, a joining test sample was prepared and the shear strength was evaluated. As a result, a sufficient joining strength of 1.9 MPa was not obtained. The results are shown in Table 1.

(Comparative Example 5)
<Preparation of nickel fine particles 7, nickel composition 10, paste 10 and thermal analysis, carbon content analysis, bonding evaluation>
100 parts by weight of the nickel fine particle slurry 1 obtained in Synthesis Example 1 was taken, and 20 parts by weight of adipic acid monoethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) and 100 parts by weight of toluene were added thereto, and the mixture was ultrasonicated for 15 minutes. After the treatment, it was washed with toluene to prepare a nickel dispersion 7 (solid content concentration 77.1% by weight). Further, a part of this was dried for 1 hour with a vacuum dryer maintained at 60 ° C. to obtain nickel fine particles 7. About the obtained nickel fine particle 7, the amount of carbon was measured according to [Measurement of amount of carbon contained in nickel fine particle and nickel composition]. The amount of carbon was 1.02% by weight, and the amount of carbon per specific surface area was 0.136.

  124 parts by weight of Nickel Dispersion 7 was fractionated, and 95.3 parts by weight of nickel particles 1, 5.06 parts by weight of α-terpineol, 5.06 parts by weight of 1-undecanol, 1.01 parts by weight. Part of binder resin 1 was mixed and concentrated by an evaporator at 60 ° C. and 100 hPa to prepare 201 parts by weight of paste 10 (solid content concentration 94.5% by weight).

  TG-DTA was carried out using the nickel fine particles 7 in accordance with the above [thermal analysis of nickel fine particles of component B]. In the region of 278.6 ° C. or higher, the weight loss rate was less than 0.05% / min. The results are shown in Table 1.

  The nickel fine particles 7 and the nickel particles 1 were separated by 50 parts by weight to obtain a nickel composition 10. This nickel composition 10 was measured according to [Measurement of the amount of carbon contained in nickel fine particles and nickel composition]. The amount of carbon was 0.50% by weight. The results are shown in Table 1.

  According to the above [Baking method] and [Evaluation of shearing strength] using paste 10, a joining test sample was prepared and the shearing strength was evaluated. As a result, 0.0 MPa and no joining strength were obtained. The results are shown in Table 1.

Claims (6)

The following components A and B;
A) Nickel particles having an average particle diameter by laser diffraction / scattering in the range of 0.5 to 20 μm and containing 99% by weight or more of nickel element,
B) The average primary particle diameter by scanning electron microscope observation is in the range of 30 to 150 nm, the particle surface is coated with an organic compound, and the following formula:
Carbon content per specific surface area = [Carbon content by elemental analysis of nickel fine particles (wt%)]
/ [Specific surface area (m ² / g) obtained by calculation based on average primary particle size]
In the range within the near carbon content per specific surface area determined it is from 0.100 to 0.160 is, in an atmosphere comprising a mixed gas of hydrogen gas and nitrogen gas containing 3% of the volume percentage of hydrogen gas, Nickel fine particles having a weight reduction rate of less than 0.05% / min at a temperature up to 265 ° C. by simultaneous differential heat / thermogravimetric measurement of a heating rate of 5 ° C./min ,
Containing
Furthermore, the nickel particle composition whose sum total of the carbon content contained in the said component A and the component B exists in the range of 0.30-1.40 weight%. The nickel particle composition according to claim 1 , wherein a weight ratio of said component A and component B (component A: component B) is in the range of 30:70 to 70:30. It is a joining material containing the nickel particle composition of Claim 1 or 2 , Comprising: Content of the said nickel particle composition exists in the range of 70 to 96 weight%. The bonding material according to claim 3 , comprising an organic solvent having a boiling point in the range of 100 to 300 ° C., wherein the content of the organic solvent is in the range of 4 to 30% by weight. Furthermore, the bonding | jointing material of Claim 3 or 4 containing an organic binder. Heating at a temperature in the range of 250 to 350 ° C in a reducing gas atmosphere containing the reducing gas with the bonding material according to any one of claims 3 to 5 interposed between the members to be bonded. A joining method in which a joining layer is formed between members to be joined.

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