JP2005104765A - Aluminum nitride powder and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum nitride powder which exhibits sufficient moisture resistance even under high temperature and high humidity conditions and does not remarkably reduce high thermal conductivity of a resin composition; and to provide a method for producing the same. <P>SOLUTION: The aluminum nitride powder has been subjected to surface treatment using an alkoxy-modified silicone. The method for producing the aluminum nitride powder comprises adding the alkoxy-modified silicone to an aluminum nitride powder having a hydroxy group, then mixing, and curing the resulting mixture until the hydroxy group and the alkoxy-modified silicone chemically bind and the alkoxy-modified silicone condenses with each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an aluminum nitride powder suitable for producing a high thermal conductive resin composition and a method for producing the same.

Aluminum nitride sintered body is an insulating ceramic with high thermal conductivity close to that of gold, and its thermal expansion coefficient is close to that of Si semiconductor elements. Therefore, it is used as an insulating and heat dissipation substrate (heat sink) for high power semiconductor elements. ing. In addition, since it has excellent plasma resistance against halogen-containing gas plasma, application to semiconductor manufacturing apparatus members such as electrostatic chucks is also being studied.

On the other hand, the application as a heat conductive filler for producing a high heat conductive resin composition is still in the middle of the process. Despite the fact that aluminum nitride powder has high thermal conductivity, its application as a heat conductive filler is limited because aluminum nitride powder is easily hydrolyzed by moisture in the air, and aluminum hydroxide and ammonia This is because. There is a problem that this hydrolysis product impairs the heat conductivity and electrical insulation, which are the original characteristics.

Various measures for suppressing the hydrolysis of the aluminum nitride powder have been proposed, but there are advantages and disadvantages. That is, a method of forming a dense alumina hydrate layer on the surface of aluminum nitride particles by treatment with high-temperature steam or pressurized hot water (Patent Document 1), a method of treating the surface of aluminum nitride powder with phosphoric acid or a phosphoric acid compound (Patent) In literature 2), there is a problem that the fluidity of the resin composition is remarkably lowered. In the method of forming an oxynitride film (Patent Document 3) and a silicon oxide film (Patent Document 4) by heating at several hundred degrees Celsius after surface treatment with alkoxysilane, the surface oxide layer becomes thick, and thus the thermal conductivity. Is a problem, and high temperature treatment is required. In the treatment method using a silane coupling agent (Patent Document 5 and Patent Document 6), the moisture resistance is insufficient, and the silane coupling agent is hydrolyzed in advance in an organic solvent to which water is added. Since this process uses aluminum nitride powder, the process is complicated, and another consideration is required to suppress hydrolysis of aluminum nitride due to excessive moisture in the solution.
JP-A-3-93612 Japanese Patent No. 3396510 JP 7-507760 Gazette Japanese Patent No. 3175073 Japanese Patent No. 2981002 JP 2002-53736 A

As described above, in the conventional method, sufficient moisture resistance cannot be imparted to the aluminum nitride powder, the high thermal conductivity and fluidity of the resin composition are impaired, the process is complicated, and the treatment is expensive. There were some problems and it was not always satisfactory. An object of the present invention is to provide an aluminum nitride powder that exhibits sufficient moisture resistance even under high-temperature and high-humidity conditions and does not significantly impair the high thermal conductivity of the resin composition. Another object of the present invention is to easily produce an aluminum nitride powder having such characteristics by a simple process.

That is, the present invention is an aluminum nitride powder that is surface-treated with an alkoxy-modified silicone. In this case, it is preferable that the alkoxy-modified silicone is an alkyl alkoxy resin or an alkyl alkoxy silicone, and the treatment amount thereof is 0.05 to 0.5% by mass in terms of the total carbon amount. Furthermore, the aluminum nitride powder is preferably a powder obtained by pulverizing an aluminum nitride sintered body. In addition, the present invention is characterized in that after the alkoxy-modified silicone is added to and mixed with the aluminum nitride powder having a hydroxyl group, the hydroxyl group and the alkoxy-modified silicone are chemically bonded and cured until the alkoxy-modified silicone is condensed. It is a manufacturing method of the said aluminum nitride powder. In this case, it is preferable that the curing includes heating curing by holding at 120 to 300 ° C. for 30 minutes or more.

Provided is an aluminum nitride powder that exhibits sufficient moisture resistance even under high-temperature and high-humidity conditions and does not significantly impair the high thermal conductivity of the resin composition. In addition, an aluminum nitride powder having such characteristics can be easily manufactured by a simple process.

There are no particular restrictions on the aluminum nitride powder used in the present invention. For example, a direct nitriding method in which metal aluminum and nitrogen are reacted, a reduction nitriding method in which a mixture of alumina and carbon is heated in nitrogen, and organic aluminum It is manufactured by a gas phase method in which a compound and ammonia are reacted. Especially, it is preferable that it is a powder of the aluminum nitride sintered compact manufactured by sintering aluminum nitride powder at the temperature of 1600-2000 degreeC in non-oxidizing atmospheres, such as nitrogen and argon, and grind | pulverizing it. Such powder has higher thermal conductivity because metal impurities and oxygen are released from the aluminum nitride particles to the particle interface and lattice defects inside the aluminum nitride particles are reduced. An example of the particle size constitution of the aluminum nitride powder is an average particle size of 10 to 50 μm and a specific surface area of 0.1 to 1.0 m ² / g.

（式中、Ｍｅはメチル基、Ｒはメチル基またはエチル基、Ｒ１，Ｒ２，Ｒ３はアルキル基（炭素数１以上）、ｎは０以上の整数、ｘ，ｙ，ｚは１以上の整数である。） The surface treating agent used in the present invention is an alkoxy-modified silicone. Of these, alkyl alkoxy resins or alkyl alkoxy silicones are suitable. Specific examples of these are shown in general formulas (1) and (2).

(In the formula, Me is a methyl group, R is a methyl group or an ethyl group, R1, R2, and R3 are alkyl groups (1 or more carbon atoms), n is an integer of 0 or more, and x, y, and z are integers of 1 or more. is there.)

The alkoxy-modified silicone is dealcoholized with moisture, chemically bonded to the hydroxyl group of the aluminum nitride powder, and the alkoxy-modified silicone is condensed to give sufficient moisture resistance even under high temperature and high humidity conditions. With conventional silane coupling agents, it was necessary to replenish water to cause chemical bonding, so the aluminum nitride powder was hydrolyzed and the thermal conductivity deteriorated, but with alkoxy-modified silicone, water was replenished. In addition, since the chemical bonding is sufficiently performed only with the adsorbed water of the aluminum nitride powder, the thermal conductivity of the treated powder is not significantly deteriorated, and the thermal conductivity equivalent to that before the treatment is maintained. The amount of hydroxyl groups in the aluminum nitride powder only needs to be sufficient to hydrolyze the alkoxy groups of the alkoxy-modified silicone, and since there is no precise quantitative method, in the present invention, it was measured by the Karl Fischer method. The moisture value is preferably 0.02 to 1.0% by mass. The qualitative analysis of the alkoxy group can be performed by a hydrogen-oxygen stretching vibration peak appearing in the vicinity of 3500 cm ⁻¹ by infrared spectroscopy and a water desorption peak appearing near 250 ° C. by thermal analysis. .

The amount of alkoxy-modified silicone used is 0.05 to 0.5% by mass (outer percentage, the same shall apply hereinafter) with respect to the aluminum nitride powder, and particularly preferably 0.1 to 0.4. It is the amount that becomes mass%. If it is less than 0.05% by mass, sufficient moisture resistance cannot be obtained even under high-temperature and high-humidity conditions, and if it exceeds 0.5% by mass, the fluidity of the resin composition decreases. Here, the carbon content of the surface treatment agent is determined from the total carbon content of the surface-treated aluminum nitride by using a low-temperature ashing treatment with plasma, a heat oxidation treatment in an oxidizing atmosphere such as oxygen, or nitric acid or halogens. It can be determined by subtracting the total carbon content of aluminum nitride from which the surface treating agent has been decomposed and removed by wet oxidation treatment or the like. The total carbon amount is measured by a calibration curve method using, for example, a carbon-sulfur simultaneous analyzer (CS-444LS) manufactured by LECO and using a standard sample of the Japan Iron and Steel Federation. As the auxiliary combustor at that time, a product name “HIGHPOPITY IRON CHIP” manufactured by LECO, a product name “LECOCEL II” manufactured by LECO, and the like are used.

In the present invention, the surface treatment of the aluminum nitride powder is performed by adding the alkoxy-modified silicone to the aluminum nitride powder by spraying, etc., and then mixing with a mixer such as a Henschel mixer, a super mixer, or a V blender, followed by heating and curing. . The alkoxy-modified silicone may be used as it is without being diluted, or may be used after being diluted with a solvent such as toluene, benzene, hexane, isopropyl alcohol, or methyl isobutyl ketone.

Curing is performed until the hydroxyl group of the aluminum nitride powder and the alkoxy-modified silicone are chemically bonded and the alkoxy-modified silicones are condensed with each other, and is allowed to stand at room temperature for 10 hours or more, preferably for 20 hours or more. More preferably, after curing at room temperature, in the air or in a non-oxidizing atmosphere such as nitrogen, carbon dioxide, carbon monoxide, helium, etc., at 120 to 300 ° C., particularly 125 to 150 ° C., for 30 minutes or more, particularly 1 hour. The above is to hold. Thereby, a stable moisture-resistant film can be formed in a short time. When the temperature is lower than 120 ° C., such an effect is small. When the temperature exceeds 300 ° C., excess adsorbed water is desorbed and the alkoxy-modified silicone is decomposed. When the curing time is less than 30 minutes, a large amount of unreacted alkoxy-modified silicone is present, and the moisture resistance stability becomes poor.

The chemical bond between the hydroxyl group and the alkoxy-modified silicone, or the condensation between the alkoxy-modified silicones does not have to be completed, and the fixing rate by carbon analysis before and after the ethanol cleaning, “fixing rate = carbon after ethanol cleaning / ethanol cleaning” The “pre-carbon” may be 0.4 or more, preferably 0.8 or more.

In the present invention, as the moisture resistance index, an increase amount of oxygen generated by hydrolysis with AlN + 3H ₂ O → Al (OH) ₃ + NH ₃ was used. Hydrolysis conditions are left for 72 hours in an atmosphere at a temperature of 80 ° C. and a relative humidity of 95%.

Example 1
Carbon powder of methyl alkoxy resin (trade name “XC96-B0446” manufactured by GE Toshiba Silicone Co., Ltd .: general formula 1) is used for commercially available aluminum nitride sintered body (thermal conductivity: 130 W / mK) (average particle diameter: 24 μm). Then, 0.14% by mass was added and mixed, followed by curing at room temperature for 24 hours.

Example 2
The treatment was performed in the same manner as in Example 1 except that methyl alkoxy resin (trade name “XR31-B1410” manufactured by GE Toshiba Silicone Co., Ltd .: general formula 1) was changed to 0.16% by mass as the methyl alkoxy resin. went.

Example 3
Example except that alkylalkoxysilicone (trade name “FZ-3511” manufactured by Nihon Unicar Co., Ltd .: general formula 2) was used instead of methylalkoxy resin, and the amount added was 0.07% by mass in terms of carbon content. The treatment was carried out in the same manner as in 1.

Example 4
The treatment was performed in the same manner as in Example 3 except that the amount of the alkylalkoxysilicone was 0.10% by mass in terms of carbon and was cured for 24 hours, and further heated at 150 ° C. for 1 hour in the air. went.

Example 5
The treatment was performed in the same manner as in Example 3 except that the addition amount of the alkylalkoxysilicone was 0.12% by mass in terms of carbon and the room temperature curing time for 24 hours was 8 hours.

Example 6
The treatment was performed in the same manner as in Example 3 except that a commercially available aluminum nitride powder (H grade 4 μm manufactured by Tokuyama Corporation) was used instead of the powder of the aluminum nitride sintered body.

Comparative Example 1
A hydrolysis test was conducted in the same manner as in Example 1 without performing the treatment with methyl alkoxy resin.

Comparative Examples 2-4
Instead of methyl alkoxy resin, γ-glycidoxypropyltrimethoxysilane (trade name “A-187” manufactured by Nihon Unicar Co., Ltd.), or silicone oil (trade name “KF96-100CS” manufactured by Shin-Etsu Chemical Co., Ltd.), or methyl The treatment was performed in the same manner as in Example 1 except that an alkoxy resin (trade name “XR31-B1410” manufactured by GE Toshiba Silicones) was used.

The thermal conductivity of the resin composition produced using the aluminum nitride powder and the moisture resistance of the aluminum nitride powder were measured as follows. The results are shown in Table 1.
(1) Thermal conductivity: 100 parts by mass of aluminum nitride powder (average particle size 24 μm), 250 parts by mass of alumina powder (average particle size 1.3 μm) (trade name “Sumicorundum” manufactured by Sumitomo Chemical Co., Ltd.), silicone 40 parts by mass of gel (trade name “XE14-B8530 (A)” manufactured by GE Toshiba Silicone), 40 parts by mass of silicone gel (trade name “XE14-B8530 (B)” manufactured by GE Toshiba Silicone), and silicone oil ( 20 parts by weight of Shin-Etsu Chemical Co., Ltd. trade name “KF96-100CS”) are mixed, molded into a sheet with a thickness of 1.0 mm, and kept in a dryer at 120 ° C. for 6 hours for vulcanization. The resin composition was sandwiched between a TO-3 type copper heater case and a copper plate, and after compressing 10% of the thickness of the resin composition, the copper heater was held for 4 minutes with electric power of 5 W. The temperature difference between the heater case and the copper plate is measured, and thermal conductivity (W / m · K) = {power (W) × thickness (m)} / {temperature difference (K) × measurement area (m ² ) The thermal conductivity was calculated.
(2) Moisture resistance: The amount of increase in oxygen before and after being left for 72 hours in an atmosphere at a temperature of 80 ° C. and a relative humidity of 95% was measured.

As shown in Table 1, the aluminum nitride powder of the present invention exhibits sufficient moisture resistance even under high-temperature and high-humidity conditions (contrast of oxygen increase amounts of Examples 1 to 6 and Comparative Example 1). Aluminum nitride powder is provided that does not significantly impair high thermal conductivity (contrast of thermal conductivity of Examples 1-6 and Comparative Example 1).

The aluminum nitride powder of the present invention can be used as a filler for producing a heat radiating member of an electronic device and a suitable high thermal conductive resin composition, and as a raw material for producing an aluminum nitride sintered body.

Claims (5)

An aluminum nitride powder obtained by surface treatment with an alkoxy-modified silicone. The aluminum nitride powder according to claim 1, wherein the alkoxy-modified silicone is an alkyl alkoxy resin or an alkyl alkoxy silicone, and a treatment amount thereof is 0.05 to 0.5% by mass in terms of carbon. The aluminum nitride powder according to claim 1 or 2, wherein the aluminum nitride powder is a powder obtained by pulverizing an aluminum nitride sintered body. The alkoxy group-modified silicone is added to and mixed with the aluminum nitride powder having a hydroxyl group, and thereafter the hydroxyl group and the alkoxy-modified silicone are chemically bonded and cured until the alkoxy-modified silicone is condensed. 3. The method for producing an aluminum nitride powder as described in 3. The method for producing an aluminum nitride powder according to claim 4, wherein the curing includes heating curing by holding at 120 to 300 ° C for 30 minutes or more.