TWI528014B - Graphite paper and its manufacturing method - Google Patents

Description

Graphite paper and manufacturing method thereof 【0001】

The present invention relates to a heat conductive material and a method of manufacturing the same, and more particularly to a graphite paper and a method of manufacturing the same.

【0002】

Under the development of technology and the demand trend of the consumer market, electronic products continue to develop in the direction of high performance, high speed and lightness and shortness. This makes the density of the electronic components relatively increase, but because the electronic components generate a large amount of thermal energy during operation, how to make the electronic products have good heat dissipation efficiency under a limited component volume to ensure the normal operation of the electronic products, thereby extending The service life of the product, "heat dissipation" has become the key issue for today's electronic products.

[0003]

At present, it is common to use metal heat sinks with high thermal conductivity such as copper and aluminum. The heat generated by the operation of electronic components is derived from the surface, but graphite has lower thermal resistance, lighter weight, and thermal conductivity than copper and aluminum. With its unique and unique performance advantages, graphite has been recognized as an excellent thermal conductive material for solving the heat dissipation problems of today's electronic products.

[0004]

Among the graphite sheet heat dissipating materials, natural graphite is a type that is relatively inexpensive to manufacture and is also widely used. At present, the natural graphite sheet heat-dissipating material is produced by a scaly graphite which is expanded by a volume of several hundred times by heating and becomes a so-called low-density worm-like graphite, which is then pressed into a plate-like graphite sheet. However, in such a manufacturing manner, the overall bending strength is low because the bending and torsion characteristics of the worm-like graphite cause large holes in the surface or even the inside of the natural graphite sheet heat dissipating material. Furthermore, in order to maintain the basic strength of the natural graphite sheet to withstand external impact, the thickness of the natural graphite sheet tends to be maintained in a relatively thick state, and thus it is gradually unable to conform to the trend of thinning and thinning of electronic components. The narrow heat sink material configuration space requirements.

[0005]

In view of the above, the present invention proposes a new graphite paper and a manufacturing method thereof in order to effectively overcome the above problems in view of the above-mentioned shortcomings of the prior art.

[0006]

The main object of the present invention is to provide a graphite paper and a method for producing the same, which have the advantages of a thinner thickness, a flat surface, a denser and higher hardness.

【0007】

Another object of the present invention is to provide a graphite paper and a method for manufacturing the same, which can be installed in a narrow remaining space of an electronic component to achieve good heat dissipation.

[0008]

In order to achieve the above-mentioned various purposes and effects, the present invention discloses a method for producing graphite paper, which comprises the steps of first expanding a scaly natural graphite to obtain a worm-like graphite. Subsequently, the worm-like graphite is subjected to a desulfurization reaction. Subsequently, the dewormed worm-like graphite is pulverized to form a fragmented worm-like graphite. Finally, the fragmented worm-like graphite is pressed into graphite paper.

【0009】

The invention further discloses a graphite paper obtained by the above-mentioned manufacturing method, wherein the graphite paper has a thickness of 10 to 170 μm and a heat transfer coefficient of 300 to 500 W/m-K.

[0010]

The invention also teaches a graphite paper which is formed by crushing worm-like graphite. The surface roughness of the graphite paper is preferably 0.6-0.8 micron, and the density of the graphite paper is preferably 1.8-2.1. g/cm ³ , second best 1.5~1.7 g/cm ³ , minimum not less than 1.2 g/cm ³ , the average diameter of the holes is 0.5 μm, and the cross section of the graphite paper exhibits a layered graphite sheet.

no

[0011]

Figure 1 is a flow chart showing a preferred embodiment of the present invention;

Figure 2(a): This is a SEM cross-sectional photograph of the existing natural graphite sheet heat-dissipating material;

Figure 2(b): This is an SEM surface photograph of the existing natural graphite sheet heat dissipating material;

Figure 2(c): is a SEM cross-sectional photograph of graphite paper of the present invention;

Figure 2(d): This is a SEM surface photograph of graphite paper of the present invention.

[0012]

In order to provide a better understanding and understanding of the features and the efficacies of the present invention, the preferred embodiment and the detailed description are as follows:

[0013]

The invention provides a graphite paper and a manufacturing method thereof, so as to solve the problem that the graphite sheet has low strength, thick thickness and high surface undulation, and cannot meet the current trend of electronic component demand. The detailed method steps are as follows:

[0014]

Please refer to FIG. 1 , which is a flow chart of a preferred embodiment of the present invention. As shown in the figure, the method for producing graphite paper of the present invention comprises the following steps:

[0015]

Step S10: The scaly natural graphite is subjected to a high temperature expansion reaction at 300 to 500 ° C to obtain a worm-like graphite, and the average length of the worm-like graphite is 3 to 8 mm.

[0016]

Step S12: The worm-like graphite is subjected to a desulfurization reaction, and the operation temperature of the desulfurization reaction is higher than the expansion reaction of the step S10, and the temperature ranges from 800 to 1000 °C.

[0017]

Step S14: The desulfurized worm-like graphite is pulverized in an ethanol solution to form a fragmented worm-like graphite, and the average length of the worm-like graphite is 0.3 to 1 mm.

[0018]

Step S16: removing the fragmented worm-like graphite through the moisture layer to remove high specific gravity impurities, and the impurities referred to herein may be metals such as vanadium, titanium, iron, aluminum, calcium, boron, or transition metals and oxides thereof. Graphene oxide and the like. The embodiment of the moisture-passing layer is to disperse the fragmented worm-like graphite on the water surface, and impurities with a higher specific gravity are deposited on the bottom.

[0019]

Step S18: removing the fragmented worm-like graphite from the high specific gravity impurities by a 10~30 mesh sieve and further draining, which is centrifuged and dehydrated by a centrifugal dehydrator at a speed of 60 to 150 revolutions per minute, about 1 to 5 minute.

[0020]

Step S20: drying in an oven and drying at a temperature of 100 to 200 °C. The dried flaky worm-like graphite was subjected to particle size screening to further remove the worm-like graphite having an excessively small particle size which was not removed in the rewet state.

[0021]

Step S22: Finally, the desired virgin size of the worm-like graphite is selected to be pressed into graphite paper, and the thickness of the graphite paper is made according to the required heat conduction requirement. The graphite paper of the present invention has a thickness ranging from 10 to 170 microns and a thermal conductivity of 300 to 500 W/mK. The pressing process has a pressure range of 50 to 200 Kg/cm ² .

[0022]

The method adopted by the invention is to make the large-scale worm-like graphite fragmented by the pulverization process, that is, the original large-scale worm-like graphite is cut into small scales, thereby reducing each single large-scale worm. The degree of bending and torsion of the graphite can make the worm-like graphite after the pressing process be tightly joined, and can have a higher density, so that the graphite paper can have a required thickness at a thin thickness. Strength of. Furthermore, since the worm-like graphite collected by the present invention exhibits a small-scale fragment shape, the state of the graphite interlayer and the interlayer is also more remarkable, and can be regarded as a sheet-like structure like mica. The density of the graphite paper prepared by the invention is preferably 1.8 to 2.1 g/cm ³ , the second best is 1.5 to 1.7 g/cm ³ , and the minimum is not less than 1.2 g/cm ³ .

[0023]

Further, since the degree of bending and torsion of the worm-like graphite is reduced, the surface of the graphite paper produced by the present invention is relatively flat and dense. The surface roughness (surface undulation) of the conventional graphite paper is 0.8 to 1.2 μm, the surface roughness of the graphite paper of the present invention is 0.6 to 0.8 μm, and the average diameter of the surface of the graphite paper of the present invention is 0.5 μm, and the cross section is presented. Layered graphite sheet.

[0024]

Please refer to Figures 2(a) to 2(d) together, which are SEM cross-section photographs of existing natural graphite sheet heat dissipating materials, SEM surface photographs of existing natural graphite sheet heat dissipating materials, and the present invention. Graphite paper SEM cross-sectional photograph; and graphite paper SEM surface photograph of the present invention.

[0025]

From these SEM cross-sectional photographs, it can be found that part of the graphite layer of the natural graphite sheet heat-dissipating material exists in the direction of the nearly vertical graphite sheet, because the use of large-scale worm-like graphite is pressed into a sheet shape due to multiple bending and twisting. They are entangled and therefore cannot exhibit a layered structure. In contrast, the graphite paper of the present invention uses a small-scale worm-like graphite and thus can clearly exhibit a layered structure.

[0026]

From the SEM surface photographs, it can be found that the natural graphite sheet heat dissipating material is larger than the graphite paper crystal grains of the present invention, and the surface and even the inside have larger pores, and the surface of the graphite paper of the present invention is flat and dense.

[0027]

In summary, the graphite paper of the present invention and the method for manufacturing the same can produce a graphite paper having a thin thickness, a small surface roughness and a dense and high hardness, and can be installed in a remaining space of a narrow electronic component when applied. Achieve good heat dissipation.

[0028]

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.

Claims (10)

[Item 1] A method of manufacturing graphite paper, comprising the following steps:
Step S1: performing swell expansion reaction on the scaly natural graphite to obtain worm-like graphite;
Step S2: performing the desulfurization reaction on the worm-like graphite;
Step S3: pulverizing the dewormed vermicular graphite to form a fragmented vermicular graphite; and step S4: pressing the fragmented vermicular graphite into graphite paper. [Item 2] The method for producing a graphite paper according to claim 1, wherein the step S3 and the step S4 further comprise a washing and drying and particle size screening step. [Item 3] The method for producing a graphite paper according to claim 2, wherein the washing and drying and particle size screening step comprises:
Passing the fragmented worm-like graphite through the moisture layer to remove high specific gravity impurities;
Dissolving the worm-like graphite of the high-specific gravity impurities by sieving and dewatering;
The worm-like graphite obtained by draining and dewatering is subjected to low-temperature drying; and the dried flaky worm-like graphite is subjected to particle size screening. [Item 4] The method for producing graphite paper according to claim 1, wherein the step S3 is carried out in a monoethanol solution. [Item 5] The method for producing graphite paper according to claim 1, wherein the temperature of the step S2 is higher than the temperature of the step S1. [Item 6] A graphite paper obtained by the method for producing graphite paper according to claim 1, wherein the graphite paper has a thickness of 10 to 170 μm and a heat transfer coefficient of 300 to 500 W/m-K. [Item 7] A graphite paper obtained by pressing a fragmented worm-like graphite having an average length of 0.3 to 1 mm. The surface roughness of the graphite paper is 0.8 μm or less, and the cross section of the graphite paper exhibits a layered graphite sheet. [Item 8] The graphite paper according to claim 7, wherein the graphite paper has a density in the range of 1.2 g/cm ³ or more, and the pores have an average diameter of 0.5 μm. [Item 9] The graphite paper of claim 8, wherein the graphite paper has a density ranging from 1.2 g/cm ³ to 2.1 g/cm ³ . [Item 10] The graphite paper according to claim 7, wherein the graphite paper has a thickness of 10 to 170 μm and a heat transfer coefficient of 300 to 500 W/mK.