KR101923341B1 - Silicone composite composition comprising natural graphite and alumina, and preparation method of thermal conductive grease comprising the same - Google Patents

Abstract

The present invention relates to a thermally conductive grease and a method including a high viscosity silicone resins, ultrasonic disruption of natural graphite and alumina, thermally conductive grease according to the present invention is a silicone resin and a thermally conductive filler, natural graphite and alumina (Al ₂ O ₃ ), the silicone resin has a viscosity of 900-1100 cSt, and the natural graphite has an effect of improving the heat radiation characteristic by ultrasonic disintegration for 25-35 minutes at a frequency of 400-500 Hz, and furthermore, a carbon fiber is added There is an effect that the heat radiation characteristic is further improved.

Description

TECHNICAL FIELD The present invention relates to a silicon composite composition including natural graphite and alumina, and a method for manufacturing a heat conductive grease using the same,

The present invention relates to a high-viscosity silicone resin, a thermally conductive grease comprising ultrasonic crushed natural graphite and alumina, and a process for producing the same.

Recently, due to the high performance, miniaturization and high performance of electronic devices including LED lighting, the amount of heat generated by the electronic components circuit is increased. As a result, the internal temperature of the device rises and malfunctions of the semiconductor devices, characteristics of the resistor components, Problems are occurring. Accordingly, various technologies have been developed as heat dissipation measures for solving such problems.

Among them, the LED converts the input energy into light and thermal energy, and the temperature of the light emitting part rises due to the converted heat. The high efficiency and long life characteristics, which are inherent advantages of LED, are required to develop core technology for high efficiency heat dissipation system because excellent characteristics can be obtained when the heat dissipation technology that effectively reduces the temperature of the light emitting part is supported.

The actual contact area is very small due to the rough interface when two solid surfaces touch each other, such as a PCB substrate or a heat sink. The pores between these interfaces are filled with air with low thermal conductivity and adversely affect the conduction of heat through the interface. To solve this problem, a thermal interface material (TIM) using a composite composition capable of improving thermal conductivity has been developed.

However, although a product using a thermally conductive composite composition is commercially available, it is difficult to expand the market with a low thermal conductivity (~ 1 W / mK). Some companies are in the process of developing the grease but it is not yet commercialized.

Although research and development is underway for development of heat dissipation materials, the technology gap with Japan has not been reduced. In fact, heat dissipation application products with high thermal conductivity are hard to find in the market. Some of the technologies include a heat dissipation material that has high thermal conductivity characteristics by adding silver (Ag) material, but it is expected to be difficult to commercialize as an expensive product, and it is technically suitable for application to a high output LED with a low thermal emissivity not.

Accordingly, the inventors of the present invention have been studying a thermally conductive grease having excellent heat dissipation characteristics, such as a high viscosity silicone resin; And ultrasonic disruption of natural graphite as a thermal conductive filler and an alumina (Al ₂ O _3); and include the viscosity of the silicone resin is 900-1100 cSt, the natural graphite is processed 25-35 minutes sonication in the century 400-500Hz The present invention has been accomplished on the basis of the finding that heat dissipation characteristics of the thermally conductive grease improved by the addition of carbon fibers to the thermally conductive filler are further improved.

Korean Patent Publication No. 10-2014-0182293

An object of the present invention is to provide a thermally conductive grease.

Another object of the present invention is to provide a method for producing the thermally conductive grease.

It is still another object of the present invention to provide a heat dissipation structure including the thermally conductive grease.

Another object of the present invention is to provide a heat sink comprising the thermally conductive grease.

In order to achieve the above object,

The present invention relates to a silicone resin; And natural graphite and alumina (Al ₂ O ₃ ) as thermally conductive fillers,

The viscosity of the silicone resin is 900-1100 cSt,

The natural graphite is ultrasonically pulverized at a frequency of 400 to 500 Hz for 25 to 35 minutes.

The present invention also relates to a process for the production of natural graphite and alumina (Al ₂ O ₃ ) powders as thermally conductive fillers at 450-550 rpm (45-75 seconds), 650-750 rpm (45-75 seconds) and 950-1050 rpm -45 sec) are sequentially performed and mixed (step 1);

Silicone resin was added to the mixed powder, and the mixture was subjected to high speed mixing at 450-550 rpm (45-75 seconds), 650-750 rpm (45-75 seconds) and 950-1050 rpm (15-45 seconds) (Step 2);

The present invention also provides a method for producing the thermally conductive grease.

Furthermore, the present invention provides a heat dissipating structure including the thermally conductive grease.

The present invention also provides a heat sink comprising the thermally conductive grease.

The thermally conductive grease according to the present invention comprises natural graphite and alumina (Al ₂ O ₃ ) as a silicone resin and thermally conductive filler, the viscosity of the silicone resin is 900-1100 cSt, the natural graphite has a strength of 400-500 Hz The heat dissipation property is improved by ultrasonic disintegration treatment for 25 to 35 minutes, and furthermore, when the carbon fiber is further included, the heat dissipation property is further improved.

1 is a graph showing the results of thermal conduction according to the ultrasonic breaking conditions of Tables 6 and 8.
2 is a schematic diagram of an experimental model for evaluating the heat radiation temperature.
3 is a schematic view showing the effect of the carbon fibers on the vertical thermal conductivity.

Unless defined otherwise, all technical terms used in the present invention have the following definitions and are consistent with the meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In addition, preferred methods or samples are described in this specification, but similar or equivalent ones are also included in the scope of the present invention. The contents of all publications referred to herein are incorporated herein by reference.

The term "about" is used herein to refer to a reference quantity, a level, a value, a number, a frequency, a percent, a dimension, a size, a quantity, a weight, or a length of 30, 25, 20, 25, 10, 9, 8, 7, Level, value, number, frequency, percent, dimension, size, quantity, weight or length of a variable, such as 4, 3, 2 or 1%.

Throughout this specification, the words "comprises" and "comprising ", unless the context requires otherwise, include the steps or components, or groups of steps or elements, Steps, or groups of elements are not excluded.

Hereinafter, the present invention will be described in detail.

Thermal conductivity  Grease

The present invention relates to a silicone resin; And natural graphite and alumina (Al ₂ O ₃ ) as thermally conductive fillers,

The viscosity of the silicone resin is 900-1100 cSt,

The natural graphite is ultrasonically pulverized at a frequency of 400 to 500 Hz for 25 to 35 minutes.

Preferably, the thermally conductive filler may further include carbon fiber (CF).

In the thermally conductive grease according to the present invention, the viscosity of the silicone resin may be 900-1100 cSt, preferably 950-1050 cSt, and particularly preferably 1000 cSt. If the viscosity of the silicone resin is less than 900 cSt, the heat dissipation characteristics may be deteriorated. If the viscosity exceeds 1100 cSt, the viscosity of the grease becomes too high, and the spreadability and dispersibility of the filler are lowered. (See Experimental Example 1).

In the thermally conductive grease according to the present invention, the natural graphite is ultrasonically pulverized for 30 to 30 minutes at a frequency of 25 to 35 minutes, preferably 425 to 475 Hz, at a frequency of 400 to 500 Hz, particularly preferably at a frequency of 450 Hz . If the ultrasonic wave breaking strength is out of the range of 400-500 Hz and the processing time is 25-35 minutes, the heat radiation characteristic may be deteriorated (see Experimental Example 2).

In the thermally conductive grease according to the present invention, the silicone resin may be selected from the group consisting of poly (dimethylsiloxane), poly (methylphenylsiloxane), poly (dimethylsiloxane-co-diphenylsiloxane) (Dimethylsiloxane-co-methylhydroxylsiloxane), polyphenyl-methylsiloxane, and the like. In the present invention, poly (dimethylsiloxane) (MW? 28,000) is used.

In the thermally conductive grease according to the present invention, the natural graphite has an average particle size of 40-50 탆, preferably 43-47 탆, particularly preferably 45 탆,

The alumina (Al ₂ O ₃ ) has an average particle size of _2-4 μm, particularly preferably 3 μm,

The carbon fibers CF may have an average length of 145 to 155 占 퐉, preferably 148 to 152 占 퐉, particularly preferably 150 占 퐉. The diameter of the carbon fibers CF may be 5-10 占 퐉, preferably 6-9 占 퐉, more preferably 7-8 占 퐉.

In the thermally conductive grease according to the present invention, the content of the thermally conductive filler in the total weight of the thermally conductive grease may be 75-85 wt%, preferably 80-85 wt%. If the content of the thermally conductive filler is less than 75% by weight, the heat radiation property may be deteriorated. If the content is more than 85% by weight, there is a problem that the physical properties as a grease deteriorates.

In one example of the thermally conductive grease according to the present invention, 10-20 wt% (preferably 13-17 wt%, particularly preferably 14.9 wt%) of a silicone resin; (Preferably 2.7-4.7 wt%, particularly preferably 3.7 wt%) and alumina (Al ₂ O ₃ ) 75-85 wt% (preferably 78.4-83.4 wt% By weight, particularly preferably 81.4% by weight).

In one example of the thermally conductive grease according to the present invention, 10-20 wt% (preferably 13-17 wt%, particularly preferably 14.9 wt%) of a silicone resin; And a thermally conductive filler, natural graphite, 1-3% by weight (preferably 1.5-2% by weight, particularly preferably 1.85% by weight), alumina (Al ₂ O ₃₎ 75-85% by weight (preferably 78.4 to 83.4 By weight, particularly preferably 81.4% by weight) and carbon fibers (CF), in an amount of 1 to 3% by weight (preferably 1.5-2% by weight, particularly preferably 1.85% by weight).

Thermal conductivity  Manufacturing method of grease

The present invention relates to the use of natural graphite and alumina (Al ₂ O ₃ ) powders as thermally conductive fillers at 450-550 rpm (45-75 seconds), 650-750 rpm (45-75 seconds) and 950-1050 rpm Second) conditions (step 1);

Silicone resin was added to the mixed powder, and the mixture was subjected to high speed mixing at 450-550 rpm (45-75 seconds), 650-750 rpm (45-75 seconds) and 950-1050 rpm (15-45 seconds) (Step 2);

The present invention also provides a method for producing the thermally conductive grease.

In the manufacturing method according to the present invention, carbon fiber (CF) may further be included as the thermally conductive filler in the step 1.

In the manufacturing method according to the present invention, the natural graphite in the step 1 is characterized in that it is subjected to an ultrasonic wave breaking treatment, and the ultrasonic wave breaking treatment method is as follows.

Specifically, the graphite powder is dispersed in an organic solvent such as toluene using mechanical stirring, and the dispersed solution is pulverized by irradiation with ultrasonic waves. Next, the ultrasound-treated solution is filtered through a vacuum filter and dried in a drying oven to obtain a natural graphite which has been ultrasonically pulverized.

Heat dissipation structure and heat sink

The present invention also provides a heat dissipating structure including the thermally conductive grease.

Further, the present invention provides a heat sink including the thermally conductive grease.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

Thermal conductivity  Method of manufacturing a grease sample

(Step 1) of performing powders such as graphite powder, inorganic filler and the like in succession at 500 rpm (1 min), 700 rpm (1 min) and 1000 rpm (30 sec) through high-speed mixing (PM-500D).

(Step 2) in which poly (dimethylsiloxane) is added as a silicone resin to the mixed powder, and then the mixture is subjected to high speed mixing at 500 rpm (1 min), 700 rpm (1 min) and 1000 rpm .

At this time, high-speed mixing and hand mixing were alternately performed for more uniform mixing.

< Experimental Example  1> Evaluation of heat radiation characteristics according to viscosity of silicone resin

In order to evaluate the vertical heat radiation characteristics according to the viscosity of the silicone resin, various graphite powders were mixed with a silicone resin having a viscosity of 500 cSt and a viscosity of 1000 cSt, and a thermally conductive grease sample was prepared and evaluated according to the compositions shown in Tables 1 and 2 below.

Specifically, the thermal diffusivity of the sample was measured using a thermal diffusivity analyzer (LFA467, Netzsch, Germany) based on the laser flash method. In addition, specific heat was measured using a specific heat analyzer (DSC-214, Netzsch, Germany). The density (ρ) was measured according to the ISO 2811 standard, and the standard deviation was calculated by repeatedly testing at least 10 times per sample for comparison of reproducibility. The obtained thermal diffusivity, density and specific heat value can be obtained by the following formula (1). The results are shown in Tables 3 and 4.

Sample Silicone resin
(500 cSt) Graphite powder One 10g 0g 2 10g Natural graphite 45㎛ 6.7 g 3 10g Natural graphite 15㎛ 6.7 g 4 10g Natural graphite 6 ㎛ 6.7 g 5 10g Conductive graphite 5㎛ 6.7 g 6 10g Artificial graphite 3 μm 6.7 g

Sample Silicone resin
(1000 cSt) Graphite powder 7 10g 0g 8 10g Natural graphite 45㎛ 6.7 g 9 10g Natural graphite 15㎛ 6.7 g 10 10g Natural graphite 6 ㎛ 6.7 g 11 10g Conductive graphite 5㎛ 6.7 g 12 10g Artificial graphite 3 μm 6.7 g

Sample Thermal diffusivity (m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) One 0.100 1.702 0.970 0.165 2 0.660 1.647 1.230 1.337 3 0.560 1.457 1.366 1.115 4 0.400 1.596 1.377 0.879 5 0.420 1.396 1.327 0.778 6 0.408 1.519 1.119 0.694

Sample Thermal diffusivity (m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 7 0.169 1.816 0.970 0.298 8 0.678 1.727 1.262 1.478 9 0.635 1.526 1.363 1.321 10 0.469 1.664 1.414 1.104 11 0.504 1.396 1.356 0.954 12 0.409 1.587 1.155 0.750

As shown in Tables 3 and 4, it was found that the thermal conductivity of the sample having a high viscosity of the silicone resin was increased, and that the larger the particle size of the graphite powder, the higher the thermal conductivity.

< Experimental Example  2> Evaluation of heat dissipation characteristics by ultrasonic disintegration treatment of graphite

In order to evaluate the vertical heat dissipation characteristics of graphite according to the ultrasonic disintegration treatment conditions, a thermally conductive grease sample was prepared according to the composition shown in the following Table 5 and the thermal conductivity was evaluated. Here, the graphite used is TG80-GT (expanded graphite, average grain size of 180 mu m).

The graphite powder was crushed by dispersing the graphite powder in a toluene solvent by mechanical stirring and irradiating the dispersed solution with ultrasonic waves. Next, the ultrasonic treated solution was filtered through a vacuum filter and dried in a drying oven at 120 캜.

Sample Silicone resin
(1000 cSt) Graphite powder
(TG80-GT) Shred time Ultrasonic shredding
Power 13 10g 4.3 g 5h 450Hz 14 10g 4.3 g 1h 450Hz 15 10g 4.3 g 30min 450Hz

Sample Thermal diffusivity (m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 13 0.301 1.724 1.352 0.702 14 0.320 1.724 1.425 0.786 15 0.506 1.724 1.498 1.307

Sample Silicone resin
(1000 cSt) Graphite powder
(TG80-GT) Shred time Ultrasonic shredding
Power 16 10g 4.3 g 30min 150Hz 17 10g 4.3 g 30min 300Hz 18 10g 4.3 g 30min 450Hz 19 10g 4.3 g 30min 600Hz

Sample Thermal diffusivity (m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 16 0.413 1.724 1.197 0.855 17 0.435 1.724 1.278 0.958 18 0.506 1.724 1.498 1.307 19 0.451 1.724 1.513 1.176

1 is a graph showing the results of thermal conduction according to the ultrasonic breaking conditions of Tables 6 and 8.

As shown in Table 6, Table 8 and FIG. 1, in Table 6, it was found that the ultrasonic breaking time was the best in 30 minutes. In Table 8, the breaking time was fixed to 30 minutes and the ultrasonic breaking power was 450 Hz The highest thermal conductivity was obtained. According to the results of this experiment, it was found that it is most preferable to treat graphite with ultrasound at 450 Hz for 30 minutes.

The conditions of ultrasonic disintegration treatment of graphite were treated for 30 minutes at a frequency of 450 Hz to prepare a thermoconductive grease having the composition shown in Table 9, and its thermal conductivity was confirmed (Table 10).

Sample Silicone resin
(1000 cSt) Crushed graphite powder 20 10g Natural graphite 45㎛ 6.7 g 21 10g Natural graphite 15㎛ 6.7 g 22 10g Natural graphite 6 ㎛ 6.7 g 23 10g Conductive graphite 5㎛ 6.7 g 24 10g Artificial graphite 3 μm 6.7 g

Sample Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 20 1.309 1.510 1.002 1.981 21 0.914 1.430 1.224 1.600 22 0.593 1.596 1.377 1.175 23 0.637 1.396 1.327 1.142 24 0.531 1.519 1.119 0.882

As shown in Table 10, similar to the results of Experimental Example 1, the larger the particle size of graphite, the higher the thermal diffusivity and the thermal conductivity. In addition, when the results of Table 10 are compared with those of Table 4, it can be seen that the thermal conductivity is improved by 0.1-0.5 (W / m * K) when graphite treated with ultrasonic waves is used as compared with graphite without any treatment .

< Experimental Example  3> Inorganic filler  Evaluation of heat dissipation characteristics by type

The thermally conductive grease samples prepared in Experimental Example 1 (graphite) and Experimental Example 2 (crushed graphite) were judged to have some defects in application to TIM (Thermal Interface Material) in terms of adhesiveness, adhesion, releasability and the like. This is because the adhesion and adhesiveness are deteriorated by graphite, so that the content of graphite is reduced and the thermal conductivity is improved. To this end, a thermally conductive grease sample was prepared by adding AlN or Al ₂ O ₃ as a thermally conductive filler to the composition shown in Table 11 below, and its heat radiation characteristics are shown in Table 12.

Sample Silicone resin
(1000 cSt) black smoke AlN
(5 탆) Al ₂ 0 ₃
(3 탆) Total filler content 25 10g Natural graphite 45㎛ 21.5g - 70wt% 2.5 g 26 10g Natural graphite 15㎛ 21.5g - 70wt% 2.5 g 27 10g Natural graphite 12 ㎛ 21.5g - 70wt% 2.5 g 28 10g Natural graphite 45㎛ - 37.5g 80wt% 2.5 g 29 10g Natural graphite 15㎛ - 37.5g 80wt% 2.5 g 30 10g Natural graphite 12 ㎛ - 37.5g 80wt% 2.5 g

division Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 25 0.878 1.200 1.914 2.016 26 0.631 1.164 1.937 1.423 27 0.472 1.140 1.971 1.061 28 0.854 1.015 2.494 2.162 29 0.762 0.999 2.524 1.921 30 0.733 0.984 2.470 1.781

As shown in Table 12, the graphite content was reduced as compared with the samples of Experimental Examples 1 and 2, and physical properties such as adhesiveness, adhesion and releasability were improved. By the addition of AlN or Al ₂ O ₃ in place of the loss of thermal conductivity of graphite it is rather shown to rise. On the other hand, also in the result of Experimental Example 3, it was found that the larger the grain size of graphite, the more favorable the thermal conductivity.

< Experimental Example  4> crushed graphite and Inorganic filler  include Thermal conductivity  Evaluation of heat dissipation characteristics of grease

In case of using crushed graphite in Experimental Example 2, it was confirmed that the thermal conductivity was increased. Thus, samples in which normal graphite and crushed graphite were respectively added to the thermoconductive grease with the compositions shown in Tables 13 and 14 were prepared, and their heat radiation characteristics were evaluated and shown in Table 15.

Sample Silicone resin
(1000 cSt) black smoke AlN
(5 탆) Al ₂ 0 ₃
(3 탆) Filler content 31 10g Natural graphite 45㎛ 21.5g - 70wt% 2.5 g 32 10g Natural graphite 45㎛ - 54.5g 85wt% 2.5 g

Sample Silicone resin
(1000 cSt) Crushed graphite AlN
(5 탆) Al ₂ 0 ₃
(3 탆) Filler content 33 10g Natural graphite 45㎛ 21.5g - 70wt% 2.5 g 34 10g Natural graphite 45㎛ - 54.5g 85wt% 2.5 g

Sample Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 31 0.878 1.200 1.914 2.016 32 0.854 1.015 2.494 2.162 33 0.973 1.200 1.885 2.201 34 1.441 1.015 2.278 3.332

As shown in Table 15, it was found that the thermal conductivity was improved in the case of using crushed graphite (Samples 33 and 34) as compared with the case of using ordinary graphite (Samples 31 and 32).

In addition, the heat radiation temperatures of the samples 32 and 34 prepared above were evaluated by an experimental model as shown in Fig. Specifically, the test was performed by setting the surface temperature of the hot plate to T ₁ , the surface temperature of the aluminum plate layer to T ₂ , and the heat radiation temperature to T ₃ , and the surface temperature to 100 ° C. The experimental results are shown in Table 16 below.

2 is a schematic diagram of an experimental model for evaluating the heat radiation temperature.

Sample 32 Sample 34 Al plate (1) Gr (45 m) + Al ₂ O ₃
[ 85wt% ](2) (S) - Gr (45 m) + Al ₂ O ₃
[ 85wt% ] (3) Average Average Average T ₁ (° C) 101.7 ± 0.2 101.5 ± 0.2 101.7 ± 0.1 T ₂ (° C) 97.8 ± 0.3 94.5 ± 0.1 90.5 ± 0.2 T ₃ (° C) 46.6 ± 0.1 47.7 ± 0.2 49.7 ± 0.2

As shown in Table 16, when the sample 32 or 34 was applied between the aluminum plate layers, it was found that the heat radiation temperature was increased. Particularly, the sample 34 using the crushed graphite was superior in heat radiation characteristics to the sample 32 using the ordinary graphite .

< Experimental Example  5> Evaluation of heat radiation characteristics by addition of carbon fiber (CF)

Since the structure of the graphite powder is plate-like, it is expected that it will not be effective for heat transfer in the vertical direction. To compensate for this, the heat radiation characteristic when carbon fiber (CF) is further added is evaluated. Specifically, a thermally conductive grease sample was prepared with the composition shown in Table 17 below, and the heat radiation characteristics thereof are shown in Table 18.

Sample Silicone resin
( 1000cSt ) Crushed graphite CF
(150 탆) Al ₂ O ₃
(3 탆) Total filler content 35 10g Natural graphite 45㎛
4.3 g - 19.7 g 70wt% 36 10g Natural graphite 45㎛
2.15 g 2.15 g 19.7 g 70wt% 37 10g Natural graphite 15㎛
4.3 g - 35.7 g 80wt% 38 10g Natural graphite 15㎛
2.15 g 2.15 g 35.7 g 80wt%

Sample Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 35 1.023 1.216 1.920 2.388 36 1.138 1.177 1.853 2.482 37 0.769 1.061 2.404 1.961 38 1.312 1.052 2.132 2.943

3 is a schematic view showing the effect of the carbon fibers on the vertical thermal conductivity.

As shown in Table 18, it was confirmed that the vertical thermal conductivity was improved in the samples 36 and 38 in which the carbon fiber was further added as the graphite content was decreased.

< Experimental Example  6> Inorganic filler  Evaluation of heat dissipation characteristics by mixing ratio

In order to determine the mixing ratio of the inorganic filler (AlN or Al ₂ O ₃ ) exhibiting the optimum heat dissipation characteristics, a thermally conductive grease sample was prepared with the composition shown in the following Table 19 without adding graphite powder, Respectively.

Sample Silicone resin
(1000 cSt) Filler Al ₂ O ₃ / AlN ratio Al ₂ O ₃ AlN 39 10g 3 탆 12g 5 탆 28g 3: 7 40 10g 5 탆 12g 5 탆 28g 3: 7 41 10g 3 탆 20g 5 탆 20g 5: 5 42 10g 5 탆 20g 5 탆 20g 5: 5 43 10g 3 탆 28g 5 탆 12g 7: 3 44 10g 5 탆 28g 5 탆 12g 7: 3

Sample Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 39 0.721 1.057 2.221 1.693 40 0.566 1.045 2.346 1.387 41 0.680 1.052 2.134 1.527 42 0.517 1.032 2.286 1.219 43 0.756 1.047 2.163 1.712 44 0.495 1.019 2.322 1.172

As shown in Table 20, Al ₂ O ₃ Average particle size and the result to the mixture ratio of the AlN comparing the thermal conductivity of a sample produced otherwise, Al ₂ O ₃ and an average particle size of the AlN in the different samples from each other of And the optimum composition ratio of Al ₂ O ₃ / AlN was found to be 7: 3.

< Experimental Example  7 > In the example  Manufactured Thermal conductivity Grease  Evaluation of heat dissipation characteristics

The compositions of the thermally conductive grease prepared in Examples 1-1 to 1-6 and Examples 2-1 to 2-4 according to the present invention (Table 21 and Table 22 below) were the same as those of Experimental Example 1-6 The results of evaluating the heat radiation characteristics in order to directly compare the heat radiation characteristics with the samples 1-44 produced in Experimental Example 1-6 are shown in Tables 23 and 24 below. Here, the viscosity of the silicone resin used in Examples 1-1 to 1-6 and Examples 2-1 to 2-4 was 1000 cSt (see Experimental Example 1), crushed graphite was crushed at 450 Hz for 30 minutes (See Experimental Example 2).

Example Silicone resin
(1000 cSt) Shredded
Natural graphite
(45 탆) Al ₂ O ₃
(3 탆) CF
(150 탆) Total filler
content 1-1 10g 4.3 g 19.7 g - 70wt% 1-2 10g 2.15 g 19.7 g 2.15 g 70wt% 1-3 10g 4.3 g 14.3 g - 65wt% 1-4 10g 2.15 g 14.3 g 2.15 g 65wt% 1-5 10g 4.3 g 10.7 g - 60wt% 1-6 10g 2.15 g 10.7 g 2.15 g 60wt%

Example Silicone resin
(1000 cSt) Shredded
Natural graphite
(45 탆) Al ₂ O ₃
(3 탆) CF
(150 탆) Total filler
content 2-1 10g 2.5 g 54.5g - 85wt% 2-2 10g 1.25 g 54.5g 1.25 g 85wt% 2-3 10g 2.5 g 37.5g - 80wt% 2-4 10g 1.25 g 37.5g 1.25 g 80wt%

Example Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 1-1 1.023 1.216 1.920 2.388 1-2 1.138 1.177 1.853 2.482 1-3 0.845 1.286 1.727 1.876 1-4 0.911 1.234 1.700 1.911 1-5 0.750 1.350 1.697 1.718 1-6 0.890 1.290 1.610 1.848

Example Thermal diffusivity m ² / s) Specific heat (J / g / K) Density (g / cm³) Thermal conductivity
(Vertical direction)
(W / m * K) 2-1 1.441 1.015 2.278 3.332 2-2 1.684 1.002 2.151 3.662 2-3 1.387 1.073 2.019 3.005 2-4 1.557 1.056 1.916 3.150

As shown in Tables 23 and 24, it was found that the heat radiation properties of the thermally conductive grease prepared in Examples 1-1 to 1-6 and Examples 2-1 to 2-4 were improved. In particular, the heat radiation properties of the thermally conductive greases prepared in Examples 2-1 to 2-4 were remarkably improved.

Claims (11)

950-1050 cSt silicone resin;
Characterized in that the natural graphite powder is dispersed in an organic solvent by mechanical stirring, the ultrasonic wave is irradiated at 425 to 475 Hz for 28 to 32 minutes to disintegrate the dispersed solution, and the ultrasonic treated solution is filtered by a vacuum filter and dried. Surface treated graphite as thermally conductive filler; And
Alumina as the thermally conductive filler (Al ₂ O _3);
And a thermally conductive grease.
The method according to claim 1,
The thermally conductive grease further comprises carbon fiber (CF) as the thermally conductive filler.
The method according to claim 1,
The silicone resin may be selected from the group consisting of poly (dimethylsiloxane), poly (methylphenylsiloxane), poly (dimethylsiloxane-co-diphenylsiloxane), poly (dimethylsiloxane-co-methylphenylsiloxane) And polyphenyl-methylsiloxane. &Lt; Desc / Clms Page number 24 &gt;
3. The method of claim 2,
The surface-treated graphite has an average particle size of 40-50 탆,
The alumina (Al ₂ O ₃ ) has an average particle size of _2-4 μm,
Wherein the carbon fibers (CF) have an average length of 145 to 155 占 퐉 and an average diameter of 5 to 10 占 퐉.
3. The method according to claim 1 or 2,
Wherein the content of the thermally conductive filler in the total weight of the thermally conductive grease is 75-85 wt%.
The method according to claim 1,
10-20% by weight of silicone resin; And 2 to 6% by weight of surface-treated graphite as a thermally conductive filler, and 75 to 85% by weight of alumina (Al ₂ O ₃ ).
3. The method of claim 2,
10-20% by weight of silicone resin; And thermally conductive grease comprising 1-3% by weight of surface treated graphite, 75-85% by weight of alumina (Al ₂ O ₃ ) and 1-3% by weight of carbon fibers (CF) as thermally conductive fillers.
The natural graphite powder was dispersed in an organic solvent using mechanical stirring. The dispersed solution was ultrasonically irradiated at 425 to 475 Hz for 28 to 32 minutes to be crushed, and then the ultrasonic treated solution was filtered through a vacuum filter and dried. (Step 1);
The surface-treated graphite and alumina (Al ₂ O ₃ ) powders prepared in step 1 as the thermally conductive filler were subjected to high speed mixing at 45-575 seconds at 450-550 rpm, 45-75 seconds at 650-750 rpm, and 15- 45 seconds (step 2); And
Adding the silicone resin to the mixed powder and then performing the mixing at 450-550 rpm for 45-75 seconds, 650-750 rpm for 45-75 seconds, and 950-1050 rpm for 15-45 seconds by high speed mixing Step 3);
The method of manufacturing a thermally conductive grease according to claim 1,
9. The method of claim 8,
Wherein the thermally conductive filler of step 1 further comprises a carbon fiber (CF).
A heat dissipation structure comprising the thermally conductive grease of claim 1.
A heat sink comprising the thermally conductive grease of claim 1.

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