JP2019019045A - Aluminum nitride-based powder and method for producing the same - Google Patents

Abstract

To provide an aluminum nitride-based powder which hardly causes aggregation in the sintering step even without using boron nitride as a raw material.SOLUTION: There is provided an aluminum nitride-based powder containing oxygen and a rare earth element, wherein the aluminum nitride-based powder has an apparent density of 3.2 g/cmor more, the content of the oxygen is 0.01 to 1 mass% in 100 mass% of the aluminum nitride-based powder and the mass ratio (M/M) of the content (M) of the rare earth element to the content (M) of the oxygen is 0.1 to 1.5.SELECTED DRAWING: None

Description

  The present invention relates to an aluminum nitride powder and a method for producing the same.

  Conventionally, aluminum nitride-based powders obtained by granulating and sintering aluminum nitride raw material powder into high thermal conductive resin used for cooling electronic parts with large heat generation such as power semiconductors, LEDs, high-frequency devices, etc. Is blended.

  For example, Patent Document 1 discloses a method of obtaining a spherical powder having an average particle size of 10 μm or more by granulating an aluminum nitride raw material powder and sintering it in an inert gas atmosphere. In this method, there is a problem that the powders are fused and aggregated in the sintering process, and it is difficult to obtain a spherical powder having good filling properties even if the aggregate is pulverized. This document also discloses that powder aggregation can be prevented by reducing the amount of sintering aid added, but simply reducing the amount of sintering aid added has high density and high thermal conductivity. It is difficult to obtain an aluminum nitride-based powder.

  Patent Document 2 discloses a method of obtaining an aluminum nitride powder obtained by granulating and sintering an aluminum nitride raw material powder, and maintaining the strength of the defatted body by adjusting the defatting temperature and maintaining the shape of the powder. It is disclosed. However, even in this method, there is a problem of agglomeration, and agglomeration of the powder occurs in the sintering process, and it is necessary to pulverize later. Therefore, it is difficult to obtain a spherical powder having a uniform particle diameter.

  Patent Document 3 also discloses a method of obtaining an aluminum nitride-based powder having a small particle size by granulating and sintering an aluminum nitride raw material powder. However, it is difficult to obtain a spherical powder having a uniform particle size because this method also tends to cause agglomeration of the powder and requires subsequent pulverization.

  On the other hand, Patent Document 4 and Patent Document 5 disclose a method of adding boron nitride powder to a raw material powder and sintering it in order to overcome the above-described problem of aggregation of aluminum nitride-based powder. However, this method requires the boron nitride powder to be separated later and cannot be completely separated. As a result, when the aluminum nitride powder is blended with the high thermal conductive resin, there arises a problem that the viscosity of the resin becomes too higher than the proper viscosity.

  Patent Document 6 discloses a spherical aluminum nitride-based powder having excellent filling properties by mixing aluminum nitride raw material granules and a small amount of boron nitride powder without using a dispersion medium such as a ball and then sintering the mixture. A method of manufacturing is described. However, when manufacturing by this method, there exists a subject that a granule tends to disintegrate in the process of mixing aluminum nitride raw material granules. In addition, there is also a problem that the resin viscosity becomes too high when the aluminum nitride powder is blended with the high thermal conductive resin as described above.

  On the other hand, in Patent Document 7, a spherical aluminum nitride powder having an average particle size of 3 to 30 μm and an oxygen content of 1% or less is manufactured by adding an alkaline earth metal compound and carbon to an alumina raw material and performing reduction nitriding. A method is disclosed. In such a method, since alumina is used as a starting material, a long time is required for the reaction and a long time is required for the subsequent decarburization treatment. Moreover, it is difficult to produce a powder having a large particle diameter exceeding 30 μm.

  Also, in Cited Document 8, a spherical aluminum nitride-based powder having a particle diameter of 10 to 200 μm containing aluminum oxynitride as a core is manufactured by firing alumina granules in two stages in an atmosphere containing carbon monoxide and nitrogen. A method is disclosed. In such a method, there is a problem that solid solution oxygen tends to remain in the aluminum nitride crystal, and as a result, the thermal conductivity as the filler material is lowered. Further, the relative density of the obtained powder particles is as low as 95% or less, and it is difficult to make it 99% or more.

JP-A-3-295863 JP 2003-267708 A JP 2006-206393 A JP-A-4-124006 Japanese Patent Laid-Open No. 11-269302 JP 2017-036183 JP 2012-056774 A JP, 2006-037438, A

  In view of the circumstances as described above, an object of the present invention is to provide an aluminum nitride-based powder that hardly causes aggregation in the sintering process without using boron nitride as a raw material.

  As a result of intensive research to achieve the above object, the present inventors have obtained a nitrided aluminum powder containing a rare earth element and oxygen in a predetermined ratio and further having an apparent density of a predetermined value or more. It has been found that aggregation can be suppressed in the sintering process without using boron. The present inventors have further studied based on such knowledge and have completed the present invention.

That is, the present invention provides the following aluminum nitride powder.
Item 1.
An aluminum nitride-based powder containing oxygen and rare earth elements,
The apparent density of the aluminum nitride-based powder is 3.2 g / cm ³ or more,
The oxygen content is 0.01 to 1% by mass in 100% by mass of the aluminum nitride-based powder,
The mass ratio of the content of the rare earth element _{(M R)} and the content of the oxygen _{(M O) (M R /} M O) is characterized in that 0.1 to 1.5, aluminum nitride powder .
Item 2.
Item 2. The aluminum nitride-based powder according to Item 1, wherein the rare earth element is yttrium.
Item 3.
The nitriding according to Item 1 or 2, further comprising 0.01 to 0.05 parts by mass of an alkaline earth metal element with respect to 100 parts by mass of a component other than the alkaline earth metal element contained in the aluminum nitride powder. Aluminum-based powder.
Item 4.
The aluminum nitride powder particles in the aluminum nitride powder are
A first phase component that is aluminum nitride crystal grains;
A second phase component that is a composite metal oxide,
95% or more of the entire second phase component has a longest diameter of 1 μm or less.
Item 4. The aluminum nitride powder according to any one of Items 1 to 3.
Item 5.
The composite metal oxide is
Item 5. The aluminum nitride-based powder according to Item 4, which is a composite metal oxide containing at least aluminum and a rare earth.
Item 6.
(1) Step 1 of mixing 0.1 to 3% by mass of oxygen and mixing an aluminum nitride raw material powder having a mean particle size of 2 μm or less, a rare earth compound powder, an organic binder, and a solvent into a slurry;
(2) Granulation and drying of the slurry obtained in the step 1 to obtain a granulated product, and (3) Degreasing the granulated product obtained in the step 2 in a reducing atmosphere 1700 Step 3 of sintering at a temperature condition of ˜1900 ° C.,
A method for producing an aluminum nitride powder characterized by comprising:
Item 7.
Item 7. The production method according to Item 6, wherein in the step 1, the alkaline earth metal compound powder is further mixed to be slurried.

  The aluminum nitride powder of the present invention hardly aggregates in the sintering process without using boron nitride as a raw material.

2 is an external view photograph of the aluminum nitride-based powder of Example 1. FIG. 2 is a cross-sectional photograph of the aluminum nitride-based powder particles of Example 1. FIG. 2 is a cross-sectional photograph of aluminum nitride-based powder particles of Comparative Example 1. FIG.

Aluminum nitride-based powder The aluminum nitride-based powder of the present invention is an aluminum nitride-based powder containing oxygen and a rare earth element, and the apparent density of the aluminum nitride-based powder is 3.2 g / cm ³ or more. The amount is 0.01 to 1% by mass in 100% by mass of the aluminum nitride powder, and the mass ratio of the rare earth element content (M _R ) to the oxygen content (M _O ) (M _R / M _O ) is 0.1 to 1.5.

  The aluminum nitride powder in the present specification means an aggregate of aluminum nitride powder particles obtained by granulating and sintering an aluminum nitride raw material powder. Such aluminum nitride-based powder can be suitably used as a filler for resin products that require high thermal conductivity, for example.

The apparent density of the aluminum nitride-based powder is 3.2 g / cm ³ or more. When the apparent density of the aluminum nitride-based powder is less than 3.2 g / cm ³ , it is not possible to obtain sufficient sinterability when sintering during production. Moreover, sufficient heat conductivity cannot be provided to the resin obtained using the manufactured aluminum nitride-based powder as a filler. On the other hand, the upper limit of the apparent density of the aluminum nitride-based powder is not particularly limited, but is preferably 3.32 g / cm ³ from the viewpoint of the theoretical density of the composite of aluminum nitride and rare earth oxide.

  In this specification, the apparent density is a volume obtained by excluding a gap volume between powders from the volume of the container when the powder is filled in a fixed volume container (however, the volume of voids existing inside the powder is , Not removed) means the density obtained by dividing the mass of the powder in the container. The apparent density can be measured by a known method, for example, the Archimedes method.

Oxygen and rare earth elements The aluminum nitride powder of the present invention contains oxygen and rare earth elements. The content of oxygen in the aluminum nitride-based powder is 0.01 to 1% by mass in 100% by mass of the aluminum nitride-based powder, more preferably 0.5 to 1% by mass, and 0.7 to More preferably, it is 1% by mass. When the oxygen content is less than 0.01% by mass, there is a problem that the apparent density of the aluminum nitride-based powder is lowered. On the other hand, when the oxygen content exceeds 1% by mass, there is a problem in that the amount of liquid phase generated in the sintering process during the production of the aluminum nitride powder increases, and the aluminum nitride powder particles tend to aggregate. . At the same time, the amount of oxygen in the aluminum nitride crystal grains increases, so that excellent thermal conductivity cannot be obtained.

  The content of oxygen in the aluminum nitride powder can be measured by quantitative analysis using, for example, an oxygen-nitrogen analyzer EMGA920 manufactured by Horiba, Ltd. using an inert gas melting / non-dispersive infrared absorption method. it can.

  Examples of the rare earth element include known rare earth elements. As the rare earth element, one or more selected from the group consisting of yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), samarium (Sm), dysprosium (Dy), and europium (Eu). It can mention, but is not limited to these. Among them, yttrium has excellent properties as a sintering aid, and aluminum nitride powder particles having high density and high thermal conductivity can be obtained.

  The content of rare earth elements in the aluminum nitride powder is preferably 0.1 to 1.8% by mass and preferably 0.3 to 1.5% by mass from the viewpoint of thermal conductivity and prevention of aggregation. Is more preferable. The content of rare earth elements in the aluminum nitride powder is determined by ICP emission spectroscopic analysis using a ICP emission spectroscopic analyzer (for example, ThermoFisher Scientific iCAP6100) by heating the sample in a sulfuric acid / nitric acid solution by microwave heating. By doing so, it can be measured.

The mass ratio (M _R / M _O ) of the rare earth element content (M _R ) and the oxygen content (M _O ) in the aluminum nitride powder is 0.1 to 1.5, 0.2 to More preferably, it is 1.3. If the mass ratio (M _R / M 2 _{O 3} ) is less than 0.1, the density of the aluminum nitride powder particles will be low. On the other hand, if it exceeds 1.5, there arises a problem that the aluminum nitride powder particles are bonded and aggregated by the liquid phase generated in the sintering process, and the density of the powder particles is lowered when the sintering temperature is low. . Thus, aggregation of aluminum nitride-based powder can be suppressed by setting the mass ratio (M _R / M _O ) within the above numerical range. As a result, it is not necessary to add boron nitride to prevent aggregation of the aluminum nitride-based powder, and the manufacturing process of the aluminum nitride-based powder can be simplified.

Alkaline earth metal element The aluminum nitride-based powder of the present invention may further contain an alkaline earth metal element. By containing an alkaline earth metal element, a dense aluminum nitride-based powder (without voids inside) can be obtained at a lower sintering temperature. Examples of the alkaline earth metal include one or more selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Of course, it is not limited to these. Among these, calcium is preferable because it can impart high thermal conductivity to the aluminum nitride powder.

  As content of alkaline-earth metal element, 0.01-0.05 mass part of alkaline-earth metal elements are included with respect to 100 mass parts of components other than the alkaline-earth metal element contained in the aluminum nitride-based powder. Is preferable, and it is more preferable to contain 0.01-0.05 mass part. By containing 0.01 parts by mass or more of the alkaline earth metal element, the sintering temperature in the sintering step of producing the aluminum nitride powder can be lowered. Moreover, the heat conductivity of the aluminum nitride type powder obtained can be improved by setting it as 0.08 mass part or less.

Aluminum nitride powder particles The aluminum nitride powder particles in the aluminum nitride powder preferably include a first phase component that is aluminum nitride crystal grains and a second phase component that is a composite metal oxide.

  Here, the second phase component is 95% or more of the entire second phase component contained in the aluminum nitride-based powder, and the grain boundary triple point of the crystal grains constituting the first phase component (hereinafter simply referred to as the triple point). .). That is, it is preferable that the second phase component does not continuously exist and is scattered at the triple point of the first phase component. When the second phase component is continuously present in the form of a plane at the crystal grain boundary, the liquid phase tends to ooze out on the surface during the sintering process, and as a result, the aluminum nitride-based powder tends to aggregate. In other words, agglomeration of the aluminum nitride-based powder can be suppressed by adopting a configuration in which 95% or more of the second phase component is present at the triple point of the first phase component.

  95% or more of the entire second phase component described above has a longest diameter of 1 μm or less. When the longest diameter exceeds 1 μm, the second phase component may not be within the above-mentioned triple point and may spread in a planar shape. The fact that 95% or more of the entire second phase component has a longest diameter of 1 μm or less means that the second phase distributed in the matrix of the first phase component (dark portion) by SEM observation of the cross section by ion milling or the like of the aluminum nitride powder. It can be calculated by measuring the size of the component (bright portion) and determining the ratio of the number of second phase components having a maximum diameter of 1 μm or less to the total quantity.

  The composite metal oxide in the second phase component is preferably a composite metal oxide containing at least aluminum and a rare earth. Alternatively, a composite metal oxide containing aluminum, rare earth, and alkaline earth metal may be used. By having such a configuration, the melting point of the second phase component is lowered, and a high-density aluminum nitride-based powder can be obtained even if the sintering process is performed at a low temperature.

In particular, yttrium is used as the rare earth element, and the mass ratio (M _R / M _O ) of the rare earth element content (M _R ) and the oxygen content (M _O ) is 0.1 to 1.5. By producing such an aluminum nitride-based powder, the main component of the second phase component is yttrium aluminum garnet (Y ₃ Al ₅ O ₁₂ ). Since the main component of the second phase component is yttrium aluminum garnet (Y ₃ Al ₅ O ₁₂ ), the melting point of the second phase component becomes low, and even if the sintering process is performed at a low temperature, a high-density aluminum nitride system A powder can be obtained.

The shape of the aluminum nitride powder particles is not particularly limited, but is preferably particles having a sphericity of 0.9 or more. The average particle size is preferably 5 to 200 μm. When the average particle size exceeds 200 μm, there arises a problem that powder particles protrude when mixed with a resin and formed into a sheet or the like. Here, the sphericity of the aluminum nitride-based powder particles is obtained by calculating the area S and the perimeter L of the projected image of each particle from an image analysis device (for example, Morphology G3 manufactured by Malvern), by calculating the roundness of the powder. By calculating 4πS / L ² and calculating the average value per number thereof, the average particle size is determined by a general laser diffraction / scattering type particle size distribution measuring device (for example, MT3300 manufactured by Nikkiso Co., Ltd.). It can be calculated by measuring the volume average particle size of an aluminum nitride-based powder ultrasonically dispersed in water to which (for example, Triton X-100 manufactured by Dow Chemical Company) is added.

  The abundance ratio of aluminum nitride powder particles having a particle size of 2 μm or less in 100% by mass of aluminum nitride powder is preferably 0.01 to 10% by mass. If the content exceeds 10% by mass, the packing density when the aluminum nitride powder is combined with the resin becomes low. Moreover, since the viscosity at the time of mixing an aluminum nitride type powder and resin becomes high, a filling amount cannot be increased and it becomes difficult to obtain high thermal conductivity. As described above, the shape is preferably a spherical particle having a sphericity of 0.9 or more in principle, but may be adjusted to a flat shape or a block shape depending on the application.

Method for producing aluminum nitride-based powder The method for producing aluminum nitride-based powder of the present invention comprises:
(1) Step 1 of mixing 0.1 to 3% by mass of oxygen and mixing an aluminum nitride raw material powder having a mean particle size of 2 μm or less, a rare earth compound powder, an organic binder, and a solvent into a slurry;
(2) Granulation and drying of the slurry obtained in the step 1 to obtain a granulated product, and (3) Degreasing the granulated product obtained in the step 2 in a reducing atmosphere 1700 It has the process 3 which sinters on -1900 degreeC temperature conditions, It is characterized by the above-mentioned.

Process 1
The aluminum nitride raw material powder used in step 1 contains 0.01 to 3% by mass of oxygen in 100% by mass of the aluminum nitride raw material powder. When the oxygen content exceeds 3% by mass, it becomes difficult to obtain an aluminum nitride-based powder having high thermal conductivity.

  In the aluminum nitride raw material powder, as long as the above-described content of oxygen is included, there is no particular limitation on the mode of inclusion. For example, an embodiment in which 2% by mass or more of oxygen exists as a surface oxide film (hydrated film) on the surface of aluminum nitride can be given.

  The aluminum nitride raw material powder used in step 1 has an average particle size of 2 μm or less. When the one having an average particle size exceeding 2 μm is used, it is difficult to obtain a dense aluminum nitride-based powder. The lower limit of the average particle diameter of the aluminum nitride raw material powder is not particularly limited, but is preferably 0.1 μm or more, for example.

  The aluminum nitride raw material powder is preferably added at a content of 20 to 60% by mass in 100% by mass of the slurry obtained in Step 1 from the viewpoint of easy dispersion and easy granulation.

A wide variety of known rare earth compound powders can be used. It is not particularly limited, but specifically, and the like _{Y 2 O 3, La 2 O} 3, Nd 2 O 3, CeO 2, Dy 2 O 3, Sm 2 O 3, Sc 2 O 3. These may be used alone or in combination of two or more. As the particle size, it is preferable to use those having an average particle size of 0.1 to 2 μm.

  Further, from the viewpoint of facilitating sintering and improving the thermal conductivity of the obtained aluminum nitride-based powder, the amount of rare earth compound powder added is 0.1 per 100 parts by mass of the aluminum nitride raw material powder. It is preferably 10 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and still more preferably 0.3 to 3 parts by mass.

  As the organic binder, known organic binders used for the production of aluminum nitride-based powders can be widely used. Specific examples include acrylic resins, waxes, polyvinyl butyral resins, polyester resins, and the like, but of course not limited thereto. These may be used individually by 1 type and may use 2 or more types together.

  The addition amount of the organic binder may be appropriately adjusted according to the type and addition amount of the aluminum nitride raw material powder and rare earth compound powder to be used. For example, 0.5 to 10 parts by mass is added to 100 parts by mass of the aluminum nitride raw material powder. Is preferred.

  Also as a solvent, it is possible to widely use known solvents used for the production of aluminum nitride-based powders. Specifically, an ester solvent, a ketone solvent, an aromatic solvent, an ether solvent, and the like can be given, but the invention is not limited to these. These may be used individually by 1 type and may use 2 or more types together.

  The addition amount of the solvent may be appropriately adjusted depending on the type and addition amount of the aluminum nitride raw material powder and rare earth compound powder to be used. For example, 50 to 300 parts by mass is added to 100 parts by mass of the aluminum nitride raw material powder. preferable.

Furthermore, it is good also as a slurry of the process 1 by adding alkaline-earth metal compound powder. Specific examples of the alkaline earth metal compound powder, BeO, mention may be made of MgO, _CaO, SrO, BaO, and CaC _2, CaCO 3, CaCN _2, and the like. These may be used individually by 1 type and may use 2 or more types together. As the particle size, it is preferable to use those having an average particle size of 0.1 to 2 μm.

  Further, from the viewpoint of facilitating sintering and improving the thermal conductivity of the resulting aluminum nitride-based powder, the addition amount of the alkaline earth metal compound powder is 0 with respect to 100 parts by mass of the aluminum nitride raw material powder. It is preferable to set it as 0.01-0.1 mass part, and it is more preferable to set it as 0.01-0.08 mass part.

  In addition, when the slurry is obtained in Step 1, a dispersant, a thixotropic agent, a plasticizer, an antifoaming agent, and the like may be further added as necessary.

  The method for forming the slurry is not particularly limited, and examples thereof include a method in which various materials described above are mixed and dispersed using a ball mill, a bead mill, a stirrer, or the like.

Process 2
In step 2, the slurry obtained in step 1 is granulated and dried. The method for granulating and drying is not particularly limited, and widely known methods can be employed. Specific examples include methods such as spray drying and rolling granulation.

Process 3
In step 3, the granulated product obtained in step 2 is degreased and sintered under a temperature condition of 1700 to 1900 degrees in a reducing atmosphere.

  As a specific method of degreasing, for example, a method of heating to 400 to 600 ° C. in air or in an inert atmosphere is preferable. By this method, the resin component of the organic binder added in Step 1 can be effectively removed, and the residual carbon amount derived from the organic binder in the obtained degreased body is set to 0.00% in 100% by mass of the degreased body. It can be reduced to 1 to 0.5% by mass. In addition, when the residual carbon amount derived from the organic binder in the degreased body is 0.1% by mass or more, the degreased body of the obtained granulated product is not easily broken, and the residual carbon amount is 0.5% by mass or less. As a result, the density of the obtained aluminum nitride-based powder becomes sufficient.

  Furthermore, the obtained degreased body is sintered under a temperature condition of 1700 to 1900 ° C. in a reducing atmosphere.

  Examples of a method for reducing atmosphere include a method for reducing nitrogen atmosphere.

As a more specific mode for achieving such a reducing nitrogen atmosphere, a sintering furnace using a carbon-based material is used, and a material other than carbon (BN, WC, Mo, SiC, Si ₃ N ₄ or the like) is used. By surrounding the granulated powder, a method of adjusting the amount of carbon vapor permeating into the sintered body can be mentioned.

  As another specific mode for obtaining a reducing nitrogen atmosphere, a method of creating a weakly reducing atmosphere by adding carbon, carbide or organic matter to the granulated powder and vaporizing the carbon during sintering is also mentioned. be able to. Here, the amount of carbon to be added is desirably 70 parts by mass or less with respect to 100 parts by mass of the oxygen content of the raw material aluminum nitride-based powder at the stage of the degreased body.

  Another specific embodiment for achieving a reducing nitrogen atmosphere is a method in which sintering is performed in a mixed atmosphere of nitrogen and hydrocarbon. By making the atmosphere reducible, preferably weakly reducible, the amount of oxygen contained in the sintered aluminum nitride-based powder can be reduced to 1% by mass or less, preventing agglomeration due to excessive liquid phase formation and firing. It becomes possible to increase the thermal conductivity of the powder. Here, the hydrocarbon concentration in nitrogen is preferably 5% by volume or less.

  Moreover, when the sintering temperature is less than 1700 ° C., the density of the obtained aluminum nitride powder particles may be insufficient. On the other hand, when the sintering temperature exceeds 1900 ° C., the aluminum nitride powder particles tend to aggregate. In view of such circumstances, the sintering temperature is more preferably 1750 to 1850 ° C.

  The embodiments of the present invention have been described above, but the present invention is not limited to these examples, and can of course be implemented in various forms without departing from the gist of the present invention.

  Hereinafter, based on an Example, Embodiment of this invention is described more concretely, This invention is not limited to these.

(Examples 1-7 and Comparative Examples 1-5)
A slurry was prepared by mixing for 24 hours in a ball mill with the composition shown in Table 1 below. Thereafter, the obtained slurry was granulated and dried by a spray drying method (apparatus: CDL20 manufactured by Okawara Chemical Co., Ltd.) to obtain a granulated powder having a volume average particle size of 70 μm. This granulated powder was degreased in air at 400 ° C. for 1 hour, then filled in a carbon container having a BN plate on the inner surface, and sintered in nitrogen for 3 hours. The apparent density of the obtained aluminum nitride-based powder was measured by the Archimedes method. The amount of oxygen contained in the aluminum nitride-based powder was measured with an inert gas melting / non-dispersion infrared absorption oxygen-nitrogen analyzer (Horiba, Ltd., ENGA-920). The amount of yttrium contained in the aluminum nitride was measured by dissolving the sample by microwave heating in a sulfuric acid / nitric acid solution using an ICP (high frequency inductively coupled plasma) emission spectroscopic analyzer (Thermo Fisher Scientific, iCAP 6100).

  Details regarding the materials used in each example and comparative example are shown in Table 2. In addition, although it does not display in Table 2 about the aluminum nitride raw material powder of Example 7 and Comparative Example 4, when manufacturing JD made by Toyo Aluminum Co., Ltd., the particle size was adjusted by adjusting the degree of grinding. What was changed was used as aluminum nitride raw material powder.

  When the aluminum nitride powder of Example 1 was observed with a scanning electron microscope, it was confirmed that the aluminum nitride powder was composed of substantially spherical aluminum nitride powder particles as shown in FIG.

  Similarly, when the cross section of the aluminum nitride-based powder particles of Example 1 was observed by grinding by ion milling, as shown in FIG. 2, the second phase was between the crystal grains of aluminum nitride as the first phase component. It was confirmed that the composite metal oxide as a component was scattered, and the size was 100% having a longest diameter of 1 μm or less. On the other hand, when the cross section of the aluminum nitride-based powder particles of Comparative Example 1 was observed, it was confirmed that the number of second phase components having a longest diameter of 1 μm or less was 60% as shown in FIG.

Aggregation evaluation test The presence or absence of aggregation of the aluminum nitride-based powders of each Example and each Comparative Example was evaluated by measuring the particle size. Specifically, the powder was pulverized into primary particles, and the particle size of the powder after pulverization was measured by a laser diffraction method. When the volume average particle size was 80 μm or less, it was determined that no aggregation was observed.

Thermal conductivity evaluation test Each aluminum nitride powder of each example and each comparative example was blended with 65% by volume of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KE-1013), mixed and stirred and defoamed. A sheet having a thickness of 3 mm was prepared, and the thermal conductivity thereof was measured with a thermal conductivity measuring device (TCi manufactured by C-THERMTECHNOLOGIES).

  As shown in Table 3, it was confirmed that the aluminum nitride-based powders of each example had excellent thermal conductivity and no aggregation of particles was observed.

Claims (7)

An aluminum nitride-based powder containing oxygen and rare earth elements,
The apparent density of the aluminum nitride-based powder is 3.2 g / cm ³ or more,
The oxygen content is 0.01 to 1% by mass in 100% by mass of the aluminum nitride-based powder,
The mass ratio of the content of the rare earth element _{(M R)} and the content of the oxygen _{(M O) (M R /} M O) is characterized in that 0.1 to 1.5, aluminum nitride powder .   The aluminum nitride-based powder according to claim 1, wherein the rare earth element is yttrium.   Furthermore, 0.01-0.05 mass parts is contained with respect to 100 mass parts of components other than the alkaline-earth metal element contained in the said aluminum nitride type powder, alkaline-earth metal element. Aluminum nitride powder. The aluminum nitride powder particles in the aluminum nitride powder are
A first phase component that is aluminum nitride crystal grains;
A second phase component that is a composite metal oxide,
95% or more of the entire second phase component has a longest diameter of 1 μm or less.
The aluminum nitride-based powder according to any one of claims 1 to 3. The composite metal oxide is
The aluminum nitride-based powder according to claim 4, which is a composite metal oxide containing at least aluminum and a rare earth. (1) Step 1 of mixing 0.1 to 3% by mass of oxygen and mixing an aluminum nitride raw material powder having a mean particle size of 2 μm or less, a rare earth compound powder, an organic binder, and a solvent into a slurry;
(2) Granulation and drying of the slurry obtained in the step 1 to obtain a granulated product, and (3) Degreasing the granulated product obtained in the step 2 in a reducing atmosphere 1700 Step 3 of sintering at a temperature condition of ˜1900 ° C.,
A method for producing an aluminum nitride powder characterized by comprising:   The manufacturing method according to claim 6, wherein the alkaline earth metal compound powder is further mixed and slurried in the step 1.