JP4743387B2 - Method for producing aluminum nitride powder - Google Patents

Description

  The present invention provides a method for producing an aluminum nitride powder that can obtain an aluminum nitride powder that has low impurities and has an excellent thermal conductivity and a sharp particle size distribution and that has a low thermal shrinkage during sintering at low cost. .

  Aluminum nitride is used as a substrate material for highly integrated electronic circuits because it has high thermal conductivity, excellent insulation, strength and corrosion resistance, and a thermal expansion coefficient close to that of a silicon chip. In addition, taking advantage of these excellent characteristics, the application to heat dissipation members such as laser oscillation parts, semiconductor manufacturing equipment members, precision machine members, jig members, etc. is progressing. Along with this, there is a need for further improvements to aluminum nitride as well as cost reduction associated with diversification of applications.

  In ceramics using aluminum nitride powder, the powder properties such as purity, particle size and particle size distribution of the aluminum nitride powder as a raw material greatly affect the dimensional accuracy during sintering and the physical properties of the sintered body. In addition to the excellent basic properties of aluminum nitride such as high thermal conductivity and high insulation properties, there is a need for fine powders with excellent sintering properties and excellent particle size distribution that enables high-density molding.

  The production method of aluminum nitride powder is broadly divided into 1) a direct nitriding method in which nitriding is performed by heating in an atmosphere containing metal aluminum powder and nitrogen, and 2) a mixture of alumina or alumina hydrate and carbon contains nitrogen. A reduction nitriding method in which heating is performed in an atmosphere is known. The reduction nitriding method is a manufacturing method with a smaller amount of cationic impurities than the direct nitriding method. On the other hand, since alumina and carbon are used as raw materials, reduction of oxygen and residual carbon is strongly demanded. In addition, since it is fired at a high temperature for a long time, it has a disadvantage that it has a wide particle size distribution and is difficult to form fine particles.

  So far, as a method for producing aluminum nitride powder by the reduction nitriding method, a method using a mixture of alumina and carbon as a starting material has been disclosed. (Patent Documents 1 to 3)

Japanese Patent Laid-Open No. 2-102109 JP-A-4-114909 JP-A-10-245207

  A manufacturing method that can obtain aluminum nitride powder with low impurities and excellent thermal conductivity, sharp particle size distribution and low thermal shrinkage during sintering at a relatively low cost is currently the most demanded. However, it has not been obtained yet.

  That is, in Patent Documents 1 to 3, a mixture of alumina and carbon powder is used as a starting material for the production method of aluminum nitride powder by the reductive nitriding method. In any of these methods, alumina particles and carbon black are used. Since the carbon component is simply mixed and the carbon component is not uniformly present on the surface of the alumina particles, the deoxygenation reaction due to carbon from the alumina particles shown in the following reaction formula 1 becomes uneven and insufficient. It is difficult to obtain high-purity aluminum nitride powder.

<Reaction Formula 1>
Al ₂ O ₃ + 3C + N ₂ → 2AlN + 3CO

  Accordingly, the present invention provides a production method that can obtain an aluminum nitride powder having a low amount of impurities, an excellent thermal conductivity, a sharp particle size distribution, and a low thermal shrinkage rate during sintering, at a relatively low cost. Is a technical issue.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention, in the method of producing aluminum nitride powder in the reduction nitriding method, the particle surface of the alumina particle powder is coated with a surface modifier and the surface. Using composite particle powder with carbon powder adhering to the surface of the modifier-coated alumina particles as a starting material, it has excellent thermal conductivity and sharp particle size distribution with few impurities, and thermal shrinkage rate during sintering It has been found that aluminum nitride having a low thickness can be obtained at low cost, and the present invention has been made.

That is, the present invention provides an alumina nitride powder and an aluminate coupling agent, polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, acrylic acid-maleic acid copolymer and One or more surface modifiers selected from olefin-maleic acid copolymers are mixed to coat the particle surface of the alumina particle powder with the surface modifier, and then the alumina particle powder coated with the surface modifier and carbon a powder obtained by mixing, the particle surface of the alumina particles, aluminate-based coupling agent, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, acrylic acid - selected from maleic acid copolymer - maleic acid copolymer and an olefin One or more A method for producing an aluminum nitride powder characterized by using a composite particle powder coated with a surface modifier and having a carbon powder adhered to the surface modifier-coated alumina particles (Invention 1). .

  Further, the present invention provides the method for producing an aluminum nitride powder according to the present invention 1, wherein the weight ratio of alumina and carbon powder in the composite particle powder is 1.0: 0.36 to 1.0: 1.0. (Invention 2).

  The method for producing an aluminum nitride powder according to the present invention can obtain an aluminum nitride powder with low impurities and excellent thermal conductivity, sharp particle size distribution and low thermal shrinkage during sintering at a relatively low cost. Therefore, it is suitable as a method for producing aluminum nitride powder for ceramic raw materials of various industrial materials such as a substrate material for highly integrated electronic circuits, a heat radiating member such as an oscillating portion, a member for a semiconductor manufacturing apparatus, a precision machine member, and a jig member.

  The configuration of the present invention will be described in more detail as follows.

  First, a method for producing aluminum nitride powder according to the present invention will be described.

  The aluminum nitride powder having excellent thermal conductivity and sharp particle size distribution with low impurities in the present invention and low thermal shrinkage during sintering is obtained by the production method of aluminum nitride powder in the reduction nitriding method. It can be obtained by using, as a starting material, a composite particle powder in which the particle surface is coated with a surface modifier and carbon powder is adhered to the surface modifier-coated alumina particle surface.

  As the alumina particle powder in the present invention, known materials such as α-alumina and γ-alumina can be used, and α-alumina is preferable. The purity of alumina is preferably as high as possible. Specifically, it is preferably 95% by weight, more preferably 97% by weight or more, and even more preferably 99% by weight or more.

  The particle shape of the alumina particle powder may be any shape such as a spherical shape, a granular shape, an indefinite shape, a needle shape, and a plate shape. Considering the uniform treatment of the carbon powder on the surface of the alumina particles, the particle shape is preferably spherical or granular.

  The average particle diameter of the alumina particle powder is preferably in the range of 0.001 to 3.0 μm, more preferably 0.005 to 1.0 μm, and still more preferably 0.01 to 0.7 μm.

When the average particle diameter exceeds 3.0 μm, the proportion of Al ₂ O ₃ inside the particles not in contact with the carbon powder increases, so the purity of the resulting aluminum nitride powder decreases. When the average particle size is less than 0.001 μm, aggregation is likely to occur due to an increase in intermolecular force due to particle miniaturization. Therefore, uniform carbon powder adhesion treatment to the alumina particle surface via the surface modifier is performed. It becomes difficult.

BET specific surface area of the alumina particles is preferably 0.01~200m ² / g, more preferably 0.05~160m ² / g, and even more preferably 0.1~120m ² / g.

  As the surface modifier in the present invention, any material can be used as long as it can adhere carbon powder to the particle surface of alumina particles, and an aluminate coupling agent and a polymer compound are preferably used. .

  Examples of the aluminate coupling agent include acetoalkoxy aluminum diisopropylate, aluminum diisopropoxy monoethyl acetoacetate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate and the like.

  Examples of the polymer compound include polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, acrylic acid-maleic acid copolymer, and olefin-maleic acid copolymer.

  The coating amount of the surface modifier is preferably 0.01 to 15.0% by weight in terms of C with respect to the alumina particle powder. In the case of less than 0.01% by weight, it is difficult to attach 36 parts by weight or more of carbon powder to 100 parts by weight of alumina particle powder. Since 0.01 to 15.0% by weight of the coating allows 36 to 100 parts by weight of the carbon powder to adhere to 100 parts by weight of the alumina particle powder, there is no meaning to cover more than necessary. More preferably, it is 0.02-12.5 weight%, More preferably, it is 0.03% -10.0 weight%.

  As the carbon powder in the present invention, carbon black particle powder such as furnace black, channel black and acetylene black and graphite powder can be used, and carbon black is preferable.

The amount of carbon powder deposited in the present invention is 36 to 100 parts by weight with respect to 100 parts by weight of the alumina particle powder. If the amount is less than 36 parts by weight, the amount of carbon component relative to the alumina particles is too small, so that the deoxygenation reaction from Al ₂ O ₃ by carbon becomes insufficient, and unreacted Al ₂ O ₃ remains, thereby reducing the purity. It will be. On the other hand, when the amount exceeds 100 parts by weight, the amount of carbon components remaining as impurities without contributing to the reaction increases, which is disadvantageous for high purity, which is not preferable. Considering high purification of the obtained aluminum nitride powder, the amount of carbon powder attached to 100 parts by weight of the alumina particle powder is preferably 38 to 90 parts by weight, more preferably 40 to 80 parts by weight.

  The composite particle powder in the present invention comprises mixing alumina particle powder and a surface modifier, coating the particle surface of the alumina particle powder with the surface modifier, and then coating the alumina particle powder coated with the surface modifier. It can be obtained by mixing with carbon powder.

  Coating the surface of the alumina particle powder with the surface modifier is performed by mechanically mixing and stirring the alumina particle powder and the surface modifier or a solution of the surface modifier, or by adding the surface modifier to the alumina particle powder. What is necessary is just to mix and stir mechanically, spraying a solution or a surface modifier.

  As a device for mixing and stirring the alumina particle powder and the surface modifier, and mixing and stirring the carbon powder and the alumina particle powder whose surface is coated with the surface modifier, shear force is applied to the powder layer. A device that can be added is preferable, and in particular, a device capable of simultaneously performing shearing, spatula and compression, for example, a wheel-type kneader, a ball-type kneader, a blade-type kneader, and a roll-type kneader can be used. A wheel-type kneader can be used more effectively.

  Examples of the wheel-type kneader include an edge runner (synonymous with “mix muller”, “simpson mill”, “sand mill”), multi-mal, stotz mill, wet pan mill, conner mill, ring muller, etc., preferably edge Runners, multi-mals, stocks mills, wet pan mills and ring mullers, more preferably edge runners. Examples of the ball kneader include a vibration mill. Examples of the blade-type kneader include a Henschel mixer, a planetary mixer, and a nauter mixer. Examples of the roll-type kneader include an extruder.

  The conditions at the time of mixing and stirring the alumina particle powder and the surface modifier are such that the line load is 19.6 to 1960 N / cm, preferably so that the surface modifier is coated as uniformly as possible on the particle surface of the alumina particle powder. May be adjusted appropriately in the range of 98 to 1470 N / cm, more preferably 147 to 980 N / cm, and the treatment time is 5 minutes to 24 hours, preferably 10 minutes to 20 hours. In addition, what is necessary is just to adjust process conditions suitably in the range of stirring speed 2-2000rpm, Preferably 5-1000rpm, More preferably, it is 10-800rpm.

  After the surface modifier is coated on the surface of the alumina particle powder, the carbon powder is added, mixed and stirred to adhere the carbon powder to the surface modifier coated alumina particle surface. If necessary, drying or heat treatment may be further performed.

  The carbon powder is added little by little over a period of 5 minutes to 24 hours, preferably 5 minutes to 20 hours, or 5 to 25 weights with respect to 100 parts by weight of the alumina particle powder. Part of the carbon powder is preferably added in portions until the desired addition amount is reached.

  The conditions at the time of mixing and stirring are such that the linear load is 19.6 to 1960 N / cm, preferably 98 to 1470 N / cm, more preferably 147 to 980 N / cm, and the treatment time is 5 minutes so that the carbon powder adheres uniformly. The treatment conditions may be appropriately adjusted in a range of ˜24 hours, preferably 10 minutes to 20 hours. In addition, what is necessary is just to adjust process conditions suitably in the range of stirring speed 2-2000rpm, Preferably 5-1000rpm, More preferably, it is 10-800rpm.

  In the case of performing drying or heat treatment, the heating temperature is usually preferably 40 to 80 ° C, more preferably 50 to 70 ° C, and the heating time is preferably 10 minutes to 6 hours, more preferably 30 minutes to 3 hours. .

  The particle shape and particle size of the composite particles in the present invention greatly depend on the particle shape and particle size of the alumina particles and have a particle form similar to the alumina particles.

  The particle shape of the composite particle powder in the present invention may be any shape such as a spherical shape, a granular shape, an indefinite shape, a needle shape, and a plate shape.

The average particle size of the composite particle powder in the present invention is 0.001 to 3.0 μm, preferably 0.005 to 1.0 μm, and more preferably 0.01 to 0.7 μm. When the average particle diameter exceeds 3.0 μm, the proportion of Al ₂ O ₃ inside the particles not in contact with the carbon powder increases, so the purity of the resulting aluminum nitride powder decreases.

BET specific surface area of the alumina particles is preferably 0.01~200m ² / g, more preferably 0.05~160m ² / g, and even more preferably 0.1~120m ² / g. When the BET specific surface area value is less than 0.01 m ² / g, the alumina particles are coarse, and the proportion of Al ₂ O ₃ inside the particles not in contact with the carbon powder increases. Purity decreases.

  The aluminum nitride powder in the present invention is a composite particle powder in which the particle surface of the above-mentioned alumina particle powder is coated with a surface modifier and carbon powder is adhered to the surface modifier-coated alumina particle surface. And reducing and nitriding by heating and baking at a predetermined temperature in a nitrogen atmosphere. If necessary, the carbon removal treatment may be performed by heating at 600 to 800 ° C. in an oxidizing atmosphere.

  Moreover, you may use what mixed the sintering aid previously with the above-mentioned composite particle powder as a starting material as needed. As the sintering aid, rare earth element compounds such as yttria and yttrium aluminate, alkaline earth metal compounds such as calcium oxide, calcium fluoride and calcium aluminate can be used.

  The composite particle powder as the starting material may have a granulated body formed in advance if necessary. By forming a granulated body, the handleability of the obtained aluminum nitride can be improved. Examples of the granulation method include compression granulation, extrusion granulation, rolling granulation, spray granulation and the like.

  As a binder used when forming a granulated body, a binder that does not remain as an impurity in the obtained aluminum nitride is preferable. Specifically, starch, polyvinyl alcohol, phenol resin, or the like can be used.

As a gas for forming a nitrogen atmosphere, N ₂ gas, NH ₃ gas, or a mixed system of these and an inert gas such as Ar gas can be used. N ₂ gas is preferred.

  The heating and firing temperature in a nitrogen atmosphere is preferably in the range of 1350 to 1750 ° C, more preferably 1400 to 1700 ° C, and even more preferably 1450 to 1650 ° C. When the heating and baking temperature is 1350 ° C. or lower, the formation reaction of the aluminum nitride powder hardly occurs, which is industrially disadvantageous. On the other hand, when the temperature is 1750 ° C. or higher, the resulting aluminum nitride powder tends to be sintered and the particle size distribution tends to be widened.

  End point determination of the reductive nitriding reaction by heating and baking in a nitrogen atmosphere is performed by monitoring the amount of CO generated in the reaction furnace, and the amount of CO generated is preferably 50 ppm or less, more preferably 30 ppm or less, and even more preferably 10 ppm or less. The end point was taken as the end point.

  In the present invention, the aluminum nitride powder is cooled after the above reductive nitriding treatment, if necessary, for decarbonization treatment, and further in an oxidizing atmosphere at a temperature range of 600 to 800 ° C. for 1 hour or more, preferably 3 Heat treatment for more than an hour.

  The particle size of the aluminum nitride powder obtained by the production method of the present invention is 0.05 to 5.00 μm, preferably 0.01 to 3.00 μm, more preferably 0.02 to 1.50 μm.

The BET specific surface area value of the aluminum nitride powder obtained by the production method of the present invention is preferably 0.01 to 150 m ² / g, more preferably 5 to 125 m ² / g.

  In the particle size distribution of the aluminum nitride powder obtained by the production method of the present invention, the geometric standard deviation value of the particle diameter is 2.5 or less, preferably 2.3 or less, more preferably 2.0 or less. When the geometric standard deviation value of the particle diameter exceeds 2.5, a large number of voids are generated inside the green compact when producing the green compact due to the existing coarse particles, and the compaction density is reduced. Is unfavorable because of an increase in size.

  The metal impurity content of the aluminum nitride powder obtained by the production method of the present invention is 5000 ppm or less, preferably 1000 ppm or less, more preferably 500 ppm or less. However, this is not the case when a rare earth element compound, an alkaline earth metal compound or the like is intentionally added as a sintering aid.

  The oxygen content of the aluminum nitride powder obtained by the production method of the present invention is 1.2% or less, preferably 1.0% or less, more preferably 0.8% or less.

  The residual carbon of the aluminum nitride powder obtained by the production method of the present invention is 1.0% or less, preferably 0.5% or less, more preferably 0.1% or less.

  The shrinkage of the aluminum nitride sintered body using the aluminum nitride powder obtained by the production method of the present invention is 18% or less, preferably 16% or less, more preferably 14% or less.

  The aluminum nitride sintered body using the aluminum nitride powder obtained by the production method of the present invention usually has a thermal conductivity of 100 to 250 W / mK, and by selecting reducing nitriding conditions, oxygen content, additives, etc. 250 W / mK or more can be obtained.

<Action>
The most important point in the present invention is that, in the method of producing aluminum nitride powder in the reduction nitriding method, the particle surface of the alumina particle powder is coated with a surface modifier and the surface modifier-coated alumina particle surface is coated with carbon powder. As a starting material, the composite particle powder with a small amount of impurities can be used to reduce the cost of aluminum nitride powder with low impurities and excellent thermal conductivity and sharp particle size distribution and low thermal shrinkage during sintering. The fact that you can get.

The present inventor considers the following as the reason why the content of impurities, particularly the oxygen content, of the aluminum nitride powder obtained by the production method according to the present invention is low. Production of aluminum nitride powder by the reductive nitriding method is a reaction represented by the following formula 2. It is known that Al ₂ O ₃ is first reduced by carbon and then a nitriding reaction occurs. According to the production method of the present invention, a composite particle powder in which a carbon powder as a carbon supply source is uniformly attached to the particle surface of an alumina particle powder via a surface modifier is used as a starting material. Compared to a simple mixture of alumina particle powder and carbon components such as carbon black, the reduction reaction by carbon from the alumina particles occurs uniformly, so that aluminum nitride with a low oxygen content could be obtained. Estimated.

<Formula 2>
Al ₂ O ₃ + 3C + N ₂ → 2AlN + 3CO

  Hereinafter, the present invention will be described in detail with reference to examples.

  The average particle diameters of the alumina particle powder, carbon powder, composite particle powder, and aluminum nitride powder were all measured by measuring the particle diameters of 350 particles shown in the electron micrograph, and showing the average value.

  The particle size distribution of the particle size of the aluminum nitride powder was indicated by a geometric standard deviation value obtained by the following method.

  That is, the value measured for the particle size of the particle shown in the above enlarged photograph is calculated from the measured value and the particle size is plotted on the horizontal axis on the lognormal probability paper according to the statistical method from the actual particle size and number of particles obtained. The diameter is plotted on the vertical axis, and the cumulative number of particles belonging to each of the predetermined particle diameter sections (under the integrated sieve) is plotted as a percentage. Then, from this graph, the particle diameter values corresponding to the number of particles of 50% and 84.13% are read, and the geometric standard deviation value = particle diameter under integrated fluid 84.13% / under integrated fluid 50%. The value was calculated according to the particle diameter (geometric mean diameter). The closer the geometric standard deviation value is to 1, the better the particle size distribution of the particles.

  The specific surface area value was indicated by a value measured by the BET method.

  The coating amount of the surface modifier coated on the particle surface of the alumina particle powder and the adhesion amount of the carbon powder adhering to the alumina particle powder are “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 Model” (Inc. It was obtained by measuring the carbon content using HORIBA, Ltd.

  The desorption rate (%) of the carbon powder adhering to the composite particle powder was indicated by the value obtained by the following method. The closer the desorption rate of the carbon powder is to 0%, the smaller the desorption amount of the carbon powder from the particle surface.

  3 g of the composite particle powder and 40 ml of ethanol were placed in a 50 ml settling tube, subjected to ultrasonic dispersion for 20 minutes, and then allowed to stand for 120 minutes, whereby the composite particle powder and detached carbon powder were separated due to the difference in specific gravity. Next, 40 ml of ethanol was again added to the composite particle powder, and after ultrasonic dispersion for 20 minutes, the composite particle powder was allowed to stand for 120 minutes to separate the composite particle powder from the detached carbon powder. This composite particle powder was dried at 100 ° C. for 1 hour, and the carbon content was measured using the above-mentioned “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 type” (manufactured by Horiba, Ltd.). The value was defined as the carbon powder desorption rate (%).

<Equation 1>
Desorption rate of carbon powder (%) = {(Wa-We) / Wa} × 100
Wa: Carbon powder adhesion amount of composite particle powder We: Carbon powder adhesion amount of composite particle powder after desorption test

  The metal impurity content (% by weight) of the aluminum nitride powder is determined by using an “inductively coupled plasma emission spectrometer” (manufactured by Seiko Denshi Kogyo Co., Ltd.) from a solution obtained by alkali melting the aluminum nitride powder and neutralizing it with an acid. Quantification was performed.

  The oxygen content (% by weight) of the aluminum nitride powder was measured using “O / N analyzer TC-136” (manufactured by LECO Corporation).

  Residual carbon (TC) (% by weight) of the aluminum nitride powder was determined by measuring the amount of carbon using “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200 Model” (manufactured by Horiba, Ltd.).

  The thermal conductivity of the molded body using the aluminum nitride powder was determined by a laser flash method, and the thickness was corrected by a calibration curve.

  The shrinkage rate during sintering of the aluminum nitride powder was determined according to the following formula 2 after measuring the dimensions before and after sintering.

<Equation 2>
Shrinkage rate (%) = {1- (Da / Db)} × 100
Da: Dimension of sintered body Db: Dimension of molded body before sintering

<Composite Particle 1: Production of Composite Particle Powder>
Alumina particle powder (alumina particle 1) (particle shape: granular, average particle diameter: 0.013 μm, geometric standard deviation value: 1.83, BET specific surface area value: 102.5 m ² / g) 400 g of isopropylate was added to the alumina particle powder while operating the edge runner, and the mixture was stirred for 30 minutes with a linear load of 588 N / cm. The stirring speed at this time was 22 rpm.

Next, 4.0 kg of carbon powder (type: carbon black, particle shape: granular, particle diameter 0.022 μm, BET specific surface area value 133.5 m ^{2 /} g) is added over 10 minutes while the edge runner is running. Further, after mixing and stirring for 120 minutes at a linear load of 588 N / cm, carbon black was adhered to the acetoalkoxyaluminum diisopropylate coating, and then dried at 105 ° C. for 60 minutes using a dryer to obtain composite particle powder. Obtained. The stirring speed at this time was 22 rpm.

The obtained composite particle powder was a granular particle having an average particle diameter of 0.014 μm. The geometric standard deviation value is 1.85, the BET specific surface area value is 48.9 m ² / g, the desorption rate of the carbon powder is 7.3%, and the weight ratio of Al ₂ O ₃ and C is 1.0: 0.399. From the observation result of the electron micrograph, since almost no carbon black was observed, it was confirmed that almost the entire amount of carbon black adhered to the particle surface of the alumina particle powder through the acetoalkoxyaluminum diisopropylate coating. .

<Example 1: Production of aluminum nitride powder>
100 parts by weight of the composite particle powder was placed in a graphite container as a starting material, and calcination was carried out at 1600 ° C. for 4 hours while flowing N ₂ gas to perform reduction nitriding treatment. The CO concentration at the end of the reaction was 10 ppm. The obtained powder was heat-treated at 700 ° C. in air for 3 hours to burn off unreacted carbon, and then pulverized by a dry ball mill to obtain an aluminum nitride powder.

The obtained aluminum nitride powder was granular particles having an average particle size of 0.15 μm. The geometric standard deviation value of the particle diameter is 1.91, the BET specific surface area value is 18.6 m ² / g, the content of metal impurities is 263 ppm, the oxygen content is 0.73%, and residual carbon (TC) Was 0.09%.

Next, 5% by weight of yttrium oxide as a sintering aid was added to and mixed with the obtained aluminum nitride powder, a polyvinyl butyral binder was added, and press molding was performed at 1500 kg / cm ² , and then the compact was placed in a nitrogen atmosphere. And then sintered at 1850 ° C. for 3 hours at normal pressure. The shrinkage rate during sintering was 13.5%, and the thermal conductivity of the sintered body was 214 W / mK.

  According to the composite particles 1 to Example 1, composite particle powder and aluminum nitride powder as starting materials were prepared. Various characteristics of each production condition and the obtained composite particle powder and aluminum nitride powder are shown.

Alumina particles 1-3:
An alumina particle powder having the characteristics shown in Table 1 was prepared as the alumina particle powder.

Carbon powders A to C:
A carbon powder having the characteristics shown in Table 2 was prepared as the carbon powder.

<Composite particle>
Composite particles 2-3, comparative composite particles 1:
Type of alumina particle powder, type of additive in coating process with surface modifier, addition amount, line load and time of edge runner treatment, type of carbon powder in addition process of carbon powder, addition amount, line of edge runner treatment A composite particle powder was obtained in the same manner as the composite particle 1 except that the load and time were variously changed.

  The production conditions at this time are shown in Table 3, and various characteristics of the obtained composite particle powder are shown in Table 4.

<Production method of aluminum nitride>
Examples 2-3 and Comparative Example 1:
Aluminum nitride powder was obtained in the same manner as in the production of aluminum nitride in Example 1 except that the starting material type, reaction temperature and reaction time in the reduction nitriding treatment, and heating temperature and heating time in the decarbonization treatment were variously changed. It was.

  The production conditions at this time are shown in Table 5, and the various characteristics of the obtained aluminum nitride powder are shown in Table 6.

The method for producing an aluminum nitride powder according to the present invention can obtain an aluminum nitride powder with low impurities and excellent thermal conductivity, sharp particle size distribution and low thermal shrinkage during sintering at a relatively low cost. Therefore, it is suitable as a method for producing aluminum nitride powder for ceramic raw materials of various industrial materials such as a substrate material for highly integrated electronic circuits, a heat radiating member such as an oscillating portion, a member for a semiconductor manufacturing apparatus, a precision machine member, and a jig member.

Claims (2)

In the production method of aluminum nitride powder in the reductive nitriding method, as starting materials , from alumina particle powder and aluminate coupling agent, polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, acrylic acid-maleic acid copolymer and olefin-maleic acid copolymer One or more selected surface modifiers are mixed to coat the particle surface of the alumina particle powder with the surface modifier, and then the alumina particle powder coated with the surface modifier and the carbon powder are mixed. The obtained alumina particle powder has a particle surface having at least one surface modification selected from an aluminate coupling agent , polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose, acrylic acid-maleic acid copolymer, and olefin-maleic acid copolymer. By agent Method for producing an aluminum nitride powder, which comprises using the composite particles of carbon powder is adhered to the surface modifying agent coated alumina particle surface with covered Te. The method for producing an aluminum nitride powder according to claim 1, wherein the weight ratio of alumina and carbon powder in the composite particle powder is 1.0: 0.36 to 1.0: 1.0.