KR102529239B1 - Spherical fine particulate material for heat dissipation, and preparing method thereof - Google Patents

Abstract

The present invention comprises preparing a fine particle powder by aggregating a slurry containing ultrafine powder having an average diameter (D ₅₀ ) of 5 to 800 nm by ultrasonic spray pyrolysis; It relates to a method for producing a fine-grained spherical heat-dissipating material, including, and a fine-grained spherical heat-dissipating material produced therefrom.

Description

Particulate spherical heat dissipation material and its manufacturing method {SPHERICAL FINE PARTICULATE MATERIAL FOR HEAT DISSIPATION, AND PREPARING METHOD THEREOF}

The present invention relates to a manufacturing method capable of reducing manufacturing cost due to a relatively short process time and easy control of process conditions, and a particulate spherical heating material manufactured therefrom.

Methods for producing alumina and silica in a spherical shape include a spray drying method, a spray pyrolysis method, a sol-gel process, a method using plasma, and the like. In addition, as a method using plasma, there are a method of manufacturing porous alumina ceramics using a discharge plasma sintering method, a method of manufacturing an alumina molded body by a hydration reaction of alumina powder and a spark plasma heat treatment method, etc. These methods have a short manufacturing time and It has the advantage of being able to produce in large quantities.

Specifically, Korean Patent Registration No. 1731665 (Patent Document 1) discloses a synthetic amorphous obtained by calcining the granulated silica powder, spheroidizing the calcined silica powder in a spheroidizer by thermal plasma, and washing and drying the spheroidized silica powder. Silica powder is disclosed. However, the silica produced by the method of Patent Document 1 has a shape with a low sphericity and has a problem of low spheroidization rate (see FIG. 1 of Patent Document 1).

In addition, Japanese Patent Registration No. 4214074 (Patent Document 2) discloses a method for producing high-purity spherical alumina powder having a high average sphericity and a low total amount of impurities by washing an alumina powder raw material with water. However, since the method of Patent Document 2 needs to go through a separate process, it causes contamination of the product or increases production cost, and there is a problem that Si, Fe, etc., which are impurities that are not purified even in the cleaning process, remain.

On the other hand, in recent years, electronic components have increased their calorific value according to the high performance of devices, and thus, a high-efficiency cooling module and a material having a heat dissipation function corresponding thereto are required. That is, there is an increasing demand for materials capable of solving cooling problems with excellent thermal stability in electronic devices that are becoming highly integrated and highly dense. As an alternative to this, alumina, aluminum nitride, etc. have been proposed, and they are widely applied as heat dissipation materials in various fields, especially electronic devices, due to their excellent thermal conductivity. Specifically, when alumina, aluminum nitride, etc. are mixed and used as a filler in heat dissipation resin or other heat dissipation materials, high density must be maintained by increasing the filling rate as well as the purity of alumina, aluminum nitride, etc. to obtain a heat dissipation material with excellent heat dissipation characteristics. be able to get Therefore, alumina, aluminum nitride, etc. applied to the heat dissipation material are required to be of high purity, have a particle size suitable for use as a filler, and have a high sphericity.

Accordingly, a manufacturing method capable of reducing manufacturing cost due to a relatively short process time and easy control of process conditions, and fine particles produced therefrom, of high purity, suitable for use as a filler, suitable for use as a filler, and having a high spheroid rate, suitable for heat dissipation materials There is a need for research and development on spherical heating materials.

Korean Patent Registration No. 1731665 (published date: 2012.11.14.) Japanese Patent Registration No. 4214074 (Publication date: 2005.10.13.)

The present invention provides a manufacturing method capable of reducing manufacturing cost due to a relatively short process time and easy control of process conditions, and a manufacturing method prepared therefrom, which is of high purity, suitable for use as a filler in particle size, and suitable for use as a heat dissipation material due to its high sphericity ratio. A particulate spherical heating material is provided.

In order to achieve the above object, the present invention comprises the steps of aggregating a slurry containing ultrafine powder having an average diameter (D ₅₀ ) of 5 to 800 nm by ultrasonic spray pyrolysis to produce fine particle powder; and

It provides a method for producing a fine-grained spherical heat dissipation material comprising a; thermal plasma treatment of the fine particle powder. In addition, the present invention provides a particulate spherical heat dissipation material produced by the method, having an average diameter (D ₅₀ ) of 1 to 10 μm and an average sphericity of 95% or more.

The manufacturing method of the particulate spherical heat dissipation material according to the present invention has a relatively short process time and easy control of process conditions, so that manufacturing costs can be reduced and a material with a high spherical rate can be manufactured.

In addition, the particulate spherical heat dissipation material according to the present invention has high purity, is suitable for use as a filler in particle size, and has a high spherical ratio, making it very suitable as a heat dissipation material.

1 is a SEM picture of an experimental example of a spherical fine-grain heat dissipation material according to the present invention.

Hereinafter, the present invention will be described in detail.

Manufacturing method of particulate spherical heat dissipation material

The manufacturing method of the particulate spherical heat dissipation material according to the present invention comprises the steps of preparing a particulate powder by ultrasonic spray pyrolysis; and thermal plasma treatment.

As described above, in the manufacturing method, nano-sized ultra-fine powder is prepared into micro-sized fine particle powder by ultrasonic spray pyrolysis and then treated with thermal plasma, thereby effectively spheroidizing various particles and materials into micro-sized powders at the same time. there is

Preparing a fine particle powder by ultrasonic spray pyrolysis

In this step, fine particle powder is prepared by aggregating the slurry including ultrafine powder having an average diameter (D ₅₀ ) of nanometer size by ultrasonic spray pyrolysis.

The ultrafine powder may have an average diameter (D ₅₀ ) of nanometer size, specifically, 5 to 800 nm, or 15 to 800 nm. In the manufacturing method of the present invention, by using ultra-fine powder having an average diameter (D ₅₀ ) of nanometer size as a raw material, the slurry containing the slurry is spray-transferred or directly sprayed into a high-temperature pyrolysis furnace, thereby continuously producing fine powder. As a result, productivity is excellent.

In addition, the ultra-fine powder may include at least one selected from the group consisting of alumina, aluminum nitride, and silica.

The slurry may include the ultrafine powder and a solvent. In this case, the solvent may be used without particular limitation as long as it is generally applicable to the manufacture of the heat dissipation material, and may be, for example, water, and preferably does not include an organic solvent.

In addition, the slurry may include 0.1 to 10% by weight or 1 to 5% by weight of ultrafine powder based on the total weight of the slurry. When the content of the ultrafine powder in the slurry is less than the above range, the number of solutes in the slurry is small, resulting in a small amount of fine particle powder. Shortage problems can arise.

The ultrasonic spray pyrolysis may be performed at 600 to 900 °C or 700 to 900 °C. When the temperature is less than the above range during the ultrasonic spray pyrolysis method, the sphericity of the prepared powder is low or it is difficult to increase the particle size to the micro size. Unexpected problems may arise.

In addition, the fine particle powder agglomerated by the ultrasonic spray pyrolysis method may have an average diameter (D ₅₀ ) of 1 to 10 μm. If the average diameter of the fine particle powder is less than the above range, a problem may occur that nanoization rather than spheroidization may occur during the next process, thermal plasma treatment, and if it exceeds the above range, a problem that the sphericization rate by heat treatment may be lowered may occur. .

Thermal plasma treatment steps

In this step, thermal plasma treatment is performed to spheroidize the fine particle powder agglomerated by the ultrasonic spray pyrolysis method. At this time, this step increases the spheroidization rate by melting the surface of the fine particle powder without thermal decomposition through thermal plasma treatment.

In the thermal plasma treatment, a plasma gas having a temperature of 6,000 K or more or 6,000 to 8,000 K may be supplied at a flow rate of 100 to 250 L/min or 150 to 210 L/min. When the temperature during the thermal plasma treatment is less than the above range, a problem in that the spheroidization rate of the fine particle powder is lowered, and when it exceeds the above range, only nano-sized particles may be generated due to thermal decomposition of the fine particle powder. In addition, when the flow rate of the plasma gas is less than the above range, it is difficult to reach the temperature for spheronization, and when it exceeds the above range, it is impossible to inject fine particle powder as a raw material due to excessive gas input, or fire or explosion etc. may occur.

In addition, the plasma gas may be used without particular limitation as long as it is a gas that can be used in a conventional thermal plasma process, and may be, for example, at least one selected from the group consisting of argon gas and nitrogen gas (N ₂ ).

In the thermal plasma treatment, any gas that can be used in the thermal plasma process as a carrier gas may be used without particular limitation, and may be, for example, at least one selected from the group consisting of nitrogen gas and argon gas.

During the thermal plasma treatment, the pressure may be 200 to 600 torr or 300 to 500 torr. When the pressure during the thermal plasma treatment is less than the above range, the contact frequency of the fine particle powder with the plasma generated by the plasma torch decreases, resulting in a low spheroidization rate, and when it exceeds the above range, the problem of nanoparticle powder occurs can

The thermal plasma-treated fine particle powder is cooled and then treated with ultrasonic waves to detach the thermally decomposed fine particles to prepare a fine spherical heat dissipation material; may further include.

Sonication after cooling

The cooling may be performed at room temperature. That is, the thermal plasma-treated fine particle powder may be cooled to room temperature and then subjected to ultrasonic treatment. At this time, the room temperature may be 15 to 30 ℃ or 20 to 25 ℃.

The cooled particulate powder can be treated with ultrasonic waves to desorb the pyrolyzed fine particles from the surface of the particulate powder. At this time, it is possible to manufacture a spherical heat dissipation material having a uniform particle size and a smooth surface through the desorption of the fine particles.

In the ultrasonic treatment, a commonly used ultrasonic wavelength may be used.

As described above, the manufacturing method of the particulate spherical heat dissipation material according to the present invention has a relatively short process time and easy control of process conditions, so that manufacturing costs can be reduced and a material with a high spherical rate can be manufactured.

Particulate spherical heat dissipation material

The particulate spherical heat dissipation material according to the present invention is manufactured by the manufacturing method as described above, and has an average diameter (D ₅₀ ) of 1 to 10 μm and an average sphericity of 95% or more.

At this time, the average sphericity is the average value of the ratio (DS/DL) of the minor diameter (DS) to the major diameter (DL) obtained for each particle by selecting 100 random particles from a photograph of a scanning electron microscope (SEM). indicates

The particulate spherical heat dissipation material may have an average diameter (D ₅₀ ) of 1 to 10 μm or 1.0 to 5.0 μm, and an average sphericity of 95% or more or 95% to 100%.

The particulate spherical heat dissipation material of the present invention as described above has a high purity, is suitable for use as a filler in particle size, and has a high spherical ratio, so it is very suitable as a heat dissipation material.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for helping the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[Example]

Experimental example 1.

Slurry-1 was prepared by adding ultrapure water to 5% by weight of aluminum nitride (AlN) having an average diameter (D ₅₀ ) of 800 nm. Thereafter, the slurry-1 was agglomerated by ultrasonic spray pyrolysis using ultrasonic waves having a wavelength of 1.7 MHz to prepare droplets, and then the solvent was evaporated from the droplets in a reactor at 900 ° C. to decompose the precursor, and finally the average diameter (D ₅₀ ) of 8 μm was prepared.

Thereafter, thermal plasma treatment was performed on the fine particle powder at a flow rate of 10 L/min using nitrogen gas as a carrier gas and at a flow rate of 180 L/min using nitrogen gas as a plasma gas at a pressure of 300 torr. Thereafter, the thermal plasma-treated microparticle powder was cooled to room temperature (22±2° C.), and ultrasonic waves were treated for 10 minutes to desorb the pyrolyzed microparticles from the surface of the microparticle powder, thereby preparing a microsphere spherical heat dissipation material.

The prepared fine grain spherical heat dissipation material had a purity of 99%, an average diameter (D ₅₀ ) of 2.2 μm, and an average sphericity of 96.3%.

Experimental Examples 2 to 16.

As shown in Table 1, a particulate spherical heat dissipation material was prepared in the same manner as in Experimental Example 1, except that the type of raw material used and the processing conditions were adjusted.

Raw material Ultrasonic Spray Pyrolysis Thermal plasma treatment Average diameter (D ₅₀ ) type Temperature (℃) pressure (torr) Plasma gas flow (L/min) Experimental Example 1 800 nm AlN 900 300 180 Experimental Example 2 15 nm SiO ₂ 900 300 180 Experimental Example 3 800 nm AlN 600 300 180 Experimental Example 4 800 nm AlN 750 300 180 Experimental Example 5 800 nm AlN 900 200 180 Experimental Example 6 800 nm AlN 900 600 180 Experimental Example 7 800 nm AlN 900 200 100 Experimental Example 8 800 nm AlN 900 600 250 Experimental Example 9 800 nm AlN 550 300 180 Experimental Example 10 800 nm AlN 1000 300 180 Experimental Example 11 800 nm AlN 900 100 180 Experimental Example 12 800 nm AlN 900 700 180 Experimental Example 13 800 nm AlN 900 300 80 Experimental Example 14 800 nm AlN 900 300 300 Experimental Example 15 800 nm AlN 900 - - Experimental Example 16 2 μm AlN 900 300 180

Test Example 1. Evaluation of characteristics

In the experimental example, the physical properties of the material were evaluated in the following manner, and the results are shown in Table 2. In addition, SEM pictures of the materials of Examples and Comparative Examples are shown in FIG. 1 .

At this time, the average sphericity is the average value of the ratio (DS/DL) of the short diameter (DS) and the long diameter (DL) obtained for each particle by selecting 100 random particles from the image of the scanning electron microscope (SEM) ( %) was used.

water Average diameter (D ₅₀ ) Average sphericity (%) Experimental Example 1 99.93% 2.2㎛ 96.3 Experimental Example 2 99.99% 4.7㎛ 96.5 Experimental Example 3 99.93% 1.3㎛ 97.6 Experimental Example 4 99.93% 1.8㎛ 96.9 Experimental Example 5 99.93% 2.8㎛ 95.2 Experimental Example 6 99.93% 1.1㎛ 97.1 Experimental Example 7 99.93% 3.2㎛ 95.8 Experimental Example 8 99.93% 1.1㎛ 95.1 Experimental Example 9 99.93% 0.2㎛ 62.3 Experimental Example 10 99.93% 8.2㎛ 12.9 Experimental Example 11 99.93% 8.2㎛ 12.9 Experimental Example 12 99.93% 2.7㎛ 34.1 Experimental Example 13 99.93% 5.4㎛ 24.8 Experimental Example 14 99.93% 0.1㎛ 64.1 Experimental Example 15 99.93% 2.4㎛ 6.6 Experimental Example 16 99.93% 6.9㎛ 70.4

As shown in Table 2, the particulate spherical heat dissipation materials of Experimental Examples 1 to 8 have a high purity of 99.9% or more, an average diameter (D ₅₀ ) of 1 to 5 μm, and an average sphericity of 95% or more and a spherical rate. This makes it very suitable as a heat dissipation material.

On the other hand, Experimental Example 9 having a low temperature during ultrasonic spray pyrolysis and Experimental Example 14 having a large flow rate during thermal plasma treatment had a small average diameter of less than 1 μm and an average sphericity of less than 65%, resulting in a low sphericity.

In addition, Experimental Example 10 with high temperature during ultrasonic spray pyrolysis, Experimental Example 11 with insufficient pressure during thermal plasma treatment, Experimental Example 12 with high pressure, Experimental Example 13 with insufficient flow rate of plasma gas, and Experimental Example 13 without thermal plasma treatment In Experimental Example 15, the average sphericity was less than 35% and the sphericity was low.

Experimental Example 16 using aluminum nitride having a large average diameter (D ₅₀ ) of 2 μm as a raw material had an average sphericity of less than 95% and a low sphericity.

Claims (4)

preparing fine particle powder by aggregating a slurry containing ultrafine powder having an average diameter (D ₅₀ ) of 5 to 800 nm by ultrasonic spray pyrolysis; and
Including; thermal plasma treatment of the fine particle powder,
The pressure during the thermal plasma treatment is 200 to 600 torr,
To supply a plasma gas at a flow rate of 100 to 250 L / min, a method for producing a fine-grained spherical heat dissipation material. The method of claim 1,
The ultrasonic spray heat treatment is carried out at 600 to 900 ° C,
The ultra-fine powder is a method for producing a fine-grained spherical heat dissipation material comprising at least one selected from the group consisting of alumina, aluminum nitride and silica. delete It is prepared by the method of claim 1 or claim 2,
A particulate spherical heat dissipation material having an average diameter (D ₅₀ ) of 1 to 10 μm and an average sphericity of 95% or more.

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