TW201808798A - Graphite sheet preparation method for changing high thermal conductivity orientation capable of increasing the heat dissipation in the thickness direction - Google Patents

Abstract

A graphite sheet preparation method for changing high thermal conductivity orientation, which comprises the steps of: (A) providing a plurality of pyrolytic graphite papers placed in a hot pressing jig in a first direction to perform a hot pressing process, thereby obtaining a pyrolysis graphite block; (B) placing the pyrolysis graphite block into an adhesive-penetrating jig, and then placing the adhesive-penetrating jig into an autoclave to perform a vacuum process; (C) injecting an adhesive-penetrating solvent into the autoclave to perform a pressurization process; (D) retrieving the pyrolysis graphite block for a heat treatment; (E) cutting the pyrolysis graphite block in a second direction to obtain a graphite sheet with high thermal conductivity. Accordingly, the use of a process that changes the orientation of the high thermal conductivity to produce a high thermal conductivity graphite sheet in a desired direction and thickness is applied to develop the field of heat dissipation materials.

Description

Manufacturing method of graphite sheet with high thermal conductivity alignment

The invention relates to a method for preparing a graphite sheet, in particular to a method for preparing a graphite sheet with high thermal conductivity alignment.

Graphite material has good thermal conductivity. Its thermal conductivity is better than that of copper. Therefore, the polymer can be converted into thermally cracked graphite paper with a thermal conductivity of up to 1700W / mK through proper synthesis and heat treatment in the industry. It can be used in the field of heat dissipation. Especially today, the thinning and thinning of electronic products requires good heat dissipation materials, but thermally cracked graphite paper with thermal conductivity up to 1700W / mK has inherent material limitations. Graphite materials do not have good ductility. It is not easy to make a heat dissipation element that meets the specifications.

Thermally cracked graphite paper is a two-dimensional planar structure. Its thermal conductivity in the XY plane (parallel to the plane of the thermally cracked graphite paper) is significantly better than that in the Z-axis direction (the direction perpendicular to the plane of the thermally cracked graphite paper). Characteristics, so even if thermally cracked graphite paper (or general graphite flake material) has been highly graphitized, due to its high thermal conductivity only exhibited on a certain plane, the Z-axis direction (vertical plane direction) cannot achieve plane-oriented thermal conduction coefficient.

The Republic of China Invention Patent (Bulletin No. I521054) entitled Thermally Conductive Element and Manufacturing Method. This invention provides a highly thermally conductive A method for manufacturing a thermally conductive element. The thermally conductive element includes a support and a plurality of thermally conductive fibers, and the thermal conductivity of the thermally conductive fibers is between 380 and 2000 W / m. K, and it is covered by a polymer-based support, and another part is exposed outside the support and directly contacts the outside. The thermal conductivity of these thermally conductive fibers is between 380 and 2000 W / m. K, and the thermal conductivity of the highly thermally conductive substrate along the arrangement direction of the thermally conductive fibers is not less than 300 W / m. K, the invention directly contacts the outside world by partially exposing these thermally conductive fibers, so it has excellent thermal and thermal conductivity; the name is the Republic of China invention patent for thermally conductive sheet, its manufacturing method, and the heat sink using thermally conductive sheet (Bulletin No. I470010), this invention is a thermally conductive sheet, which is a thermally conductive sheet containing a composition containing graphite particles (A) and an organic polymer compound (B) having a Tg of 50 ° C or lower, in which the graphite particles (A ) Is scaly, ellipsoidal or rod-shaped, and the six-member torus in the crystal is oriented in the direction of the scales, the major axis of the ellipsoid, or the major axis of the rod, and is characterized by the graphite particles (A) The plane direction of the scales, the major axis direction of the ellipsoid, or the major axis direction of the rod are oriented in the thickness direction of the thermally conductive sheet, and therefore, the thermal conductivity in the thickness direction (vertical sheet plane direction) can be improved.

The above-mentioned prior art content discloses that a method for making a high thermal conductivity sheet by changing a high thermal conductivity alignment technique is to arrange a material having a unidirectional high thermal conductivity property (such as thermally conductive fibers or flaky graphite) inside the substrate, and the arrangement manner The high thermal conductivity direction is oriented to the thickness direction of the thermally conductive sheet (vertical sheet plane direction), thereby improving the thermal conductivity of the thermally conductive sheet in the thickness direction (vertical sheet plane direction); Alignment characteristics The material is coated in a polymer substrate in an orientation manner to complete a thermally conductive sheet with high thermal conductivity in the thickness direction (vertical sheet plane direction), but most of the highly thermally conductive material added is a thermally conductive sheet with a small thermal cross-sectional area. Fibers, or discontinuous thermally conductive powders scattered inside the substrate, so the improvement of thermal conductivity is really limited.

Therefore, the industry currently needs to develop a method for manufacturing graphite sheets (high thermal conductive flakes) that can change the orientation of high thermal conductivity to produce graphite sheets with high thermal conductivity alignment characteristics in the thickness direction (vertical plane direction of the sheet). It can simultaneously combine the advantages of material heat dissipation with the requirements of practical applications, and prepare highly thermally-oriented graphite sheets that meet the application orientation.

In view of the shortcomings of the above-mentioned conventional technologies, the main object of the present invention is to provide a method for manufacturing a graphite sheet that changes the orientation of high thermal conductivity, integrating a plurality of pyrolytic graphite paper, a hot-pressing jig, a glue-seeking jig, a pressure kettle, and a hot-pressing, Processes such as heat treatment can effectively change the alignment of materials with high thermal conductivity, and obtain the high thermal conductivity graphite sheet with the required high thermal conductivity alignment and thickness.

In order to achieve the above object, according to a solution provided by the present invention, a method for manufacturing a graphite sheet with high thermal conductivity alignment is provided. The steps include: (A) providing a plurality of thermally cracked graphite papers into a hot pressing fixture in a first direction; A hot pressing process is performed to obtain a thermally cracked graphite block; (B) the thermally cracked graphite block is placed in a glue infiltration fixture, and then the glue infiltration fixture is placed in a pressure kettle to perform a vacuum process; C) Inject a gelatinizing solvent into the autoclave, and pressurize Manufacturing process; (D) taking out the thermally cracked graphite block for a heat treatment; (E) cutting the thermally cracked graphite block in a second direction to obtain a graphite sheet with high thermal conductivity, wherein the first direction is parallel to the thermal The direction of the plane of the cracked graphite paper, the second direction is a direction perpendicular to the plane of the thermally cracked graphite paper.

In the above step (A), when a plurality of thermally cracked graphite papers are placed in a hot-pressing fixture for a hot-pressing process, since the pressure range during the hot-pressing process can be 50 to 100 kg / cm ² , so to avoid thermally cracking the graphite paper Sliding or moving, the surface of the pyrolytic graphite paper can be coated with phenol resin. The phenol resin coating area can be the four sides and the middle point of the pyrolytic graphite paper, but it is not limited to this.

Three sets of pipelines and valves can be designed above the autoclave of the present invention, which can control processes such as vacuum extraction, injection of oozing solvent, and air pressure. When the oozing solvent is injected into the autoclave, the liquid level of the oozing solvent in the autoclave should exceed The height of the glue-fixing fixture completely submerged the glue-fixing fixture and a plurality of thermally cracked graphite papers to increase the glue-seeking effect. The glue-seeking solvent may include phosphoric acid, pure water, and furan alcohol, and the ratio may be 1:10: 100 (but not limited to this).

Step (C) of the present invention may further include a step. After the pressure process is performed, the thermally cracked graphite block may be taken out from the pressure-reduced autoclave, and then an infiltration process may be performed. The pyrolytic graphite block in the glue-fixing fixture is put into a container filled with glue-fixing solvent (the colloid liquid level in the container must exceed the fixture), and then heat-treated.

The heat treatment in step (D) of the present invention may include a 4-stage heating process, and the heating process procedure may be as follows (but not limited to this): heating up to 60 ° C holding temperature 12 hours → heating up for 4 hours to 95 ° C and holding temperature for 8 hours → heating up for 4 hours to 100 ° C and holding temperature for 8 hours → heating up for 10 hours to 250 ° C and holding temperature for 2 hours → furnace cooling for 4 hours to cool to 30 ° C.

The above summary and the following detailed description and drawings are to further explain the methods, means and effects adopted by this creation to achieve the intended purpose. The other purposes and advantages of this creation will be explained in the subsequent description and drawings.

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21‧‧‧base

22‧‧‧Die

41‧‧‧metal container

42, 43, 44‧‧‧‧three sets of pipelines and valves

51‧‧‧heat source

52‧‧‧ cooling water

53‧‧‧Graphite sheet with high thermal conductivity

54‧‧‧metal

The first diagram is a flowchart of a method for manufacturing a graphite sheet with a high thermal conductivity alignment according to the present invention; the second diagram is a schematic diagram of a hot-pressing fixture according to the present invention; the third diagram is a schematic diagram of a glue penetrating fixture according to the present invention; the fourth diagram is It is a schematic diagram of a pressure kettle of the present invention; the fifth diagram is a schematic diagram of a graphite sheet with high thermal conductivity (high thermal conductivity in the Z-axis direction) of the present invention applied to a water cooling device.

The following is a specific example to illustrate the implementation of this creation. Those who are familiar with this technique can easily understand the advantages and effects of this creation from the content disclosed in this manual.

The invention is to change the alignment technique to make a thin sheet with excellent thermal conductivity in the thickness direction (vertical sheet plane direction, but not limited to this). The thermally-splitting graphite paper layers are adhered directly to the thickness direction after cutting along the preferred direction of thermal conductivity. Therefore, the cross-sectional area of the single graphite paper material responsible for thermal conductivity in the present invention is larger than the thermal conductive fibers used in other patents. The effect is also much better than the thermally conductive powder dispersed in the polymer substrate. In the embodiment of the present invention, the thermally cracked graphite paper layers are laminated and adhered, and the thermally conductive sheet is cut from the vertical direction of the laminated surface. The XY plane (parallel to the pyrolytic graphite paper plane) is perpendicular to the graphite paper stacking surface before cutting. Because the XY plane of the pyrolytic graphite paper (parallel to the pyrolytic graphite paper plane) has high thermal conductivity and is cut The Z-thickness direction of the rear thermally conductive sheet (the direction perpendicular to the plane of the thermally cracked graphite paper) is aligned with the thermally conductive XY plane of the thermally cracked graphite paper (parallel to the plane of the thermally cracked graphite paper). (Thickness direction) It is possible to maintain the same thermal conductivity as the thermally cracked graphite paper XY plane.

Please refer to the first figure, which is a flowchart of a method for manufacturing a graphite sheet with high thermal conductivity alignment according to the present invention. As shown in the figure, the present invention provides a method for manufacturing a graphite sheet with a high thermal conductivity alignment. The steps include: (A) providing a plurality of thermally cracked graphite papers in a first direction into a hot pressing fixture for a hot pressing process, To obtain a thermally cracked graphite block S101; (B) placing the thermally cracked graphite block into a cementation fixture, and then placing the cementation fixture into a pressure kettle to perform a vacuum process S102; (C) placing a The penetrating solvent is injected into the autoclave, and a pressure process S103 is performed; (D) the thermally cracked graphite block is taken out and subjected to a heat treatment S104; (E) the thermally cracked graphite block is cut in a second direction to obtain high thermal conductivity characteristics Graphite sheet S105.

Examples

Please refer to the second diagram, which is a schematic diagram of a hot-pressing fixture of the present invention, and please refer to the third diagram, which is a schematic diagram of a glue permeating fixture of the present invention, and refer to the fourth diagram, which is a schematic diagram of a pressure kettle of the present invention. The implementation steps of this embodiment are as follows : (1) Take thermally cracked graphite paper (or other graphite sheet with high thermal conductivity in the XY plane) and apply phenol resin. The glued area is the four sides and the middle point of the graphite paper. (2) The glued heat Pieces of cracked graphite paper (in the first direction: parallel to the plane of the pyrolyzed graphite paper) were placed in a stainless steel hot-pressed fixture, a total of about 2000 layers of thermally-cracked graphite paper, in which the hot-pressed fixture was made of stainless steel or other Made of metal material, the structure includes a base 21 and a stamper 22. The base 21 has a cube-shaped groove. The length and width of the groove should be the same as the length and width of the stamper 22 and the thermally cracked graphite paper to be pressed. The press presses the hot pressing fixture of the previous step, the pressure value is about 50 ~ 100kg / cm ² , and the temperature is raised to 150 ° C for 2 hours. (4) Take out the hot-pressed pyrolytic graphite block from the hot pressing fixture and put it in In stainless steel cementing fixtures, Tighten and fix the pyrolytic graphite block with screws. The glue infiltration fixture is made of stainless steel or other metal materials with considerable strength. The structure includes two flat metal plates above and below, and the two metal plates can be fastened or paralleled in parallel. The loosened screw column (5) puts the glue-fixing fixture in a pressure kettle, and then evacuates for 1 hour, and then closes the vacuum valve. The pressure kettle is made of stainless steel or other metal materials with considerable strength, and the main body is provided with The upper cover is a hollow metal container 41. The upper cover contains three sets of pipelines and valves (42, 43, 44), which can be connected to a vacuum pump to evacuate, pour a gelatinizing solvent, and connect an air compressor to pressurize the air (6). The gelatinizing solvent is injected into the autoclave, and then the injection line valve is closed. The colloid liquid level in the autoclave must exceed the height of the gelling fixture. The method of formulating the gelatinizing solvent is based on the weight ratio of each solvent as "phosphoric acid: pure water: furan alcohol." = 1: 10: 100 "for sufficient stirring and mixing (7) to the pressurized compressor air line pressure of the autoclave is pressurized to a pressure of 7kg / cm ^2, and the injection valve opening pressure, for 4 hours (8) After pressing, remove the glue-fixing jig from the autoclave, put it into a container filled with glue-fixing solvent, put the container in an oven, and heat it to 65 ° C for 24 hours. The level of glue-filling solvent in the container must exceed the pressure. Glue fixture height (9) After the glue solution of the glue-penetrating solvent in the container thickens, loosen the glue-piercing fixture to remove the thermally cracked graphite block, and scrape off the remaining glue solution. (10) The thermally-cracked graphite block is again placed in the glue. Place it on the jig and put it in the oven for heat treatment. The heat treatment procedure is: "Heating to 60 ℃ and holding temperature for 12 hours → Heating for 4 hours to 95 ℃ and holding temperature for 8 hours → Heating for 4 hours to 100 ℃ and holding temperature for 8 hours → heating for 10 hours To 250 ° C and holding temperature for 2 hours → furnace cooling for 4 hours to cool to 30 ° C "(11) cut the thermally cracked graphite block in a direction (second direction) perpendicular to the stacking surface (parallel to the plane of the thermally cracked graphite paper) By forming thin sheets with appropriate thickness, graphite sheets with high thermal conductivity in the Z-axis direction can be obtained.

The graphite sheet with high thermal conductivity in the Z-axis direction (vertical to the plane of the thermally cracked graphite paper) completed in this embodiment is cut into 1 cm × 1 cm × 0.2 cm thick sheets, and a longitudinal thermal conductivity test is performed. The brand model of the thermal conductivity tester is NETZSCH CFA-447, the temperature test range is from 25 ℃ ~ 200 ℃, and the thermal conductivity test is performed 10 times with an increase of 25 ℃, and the average value is obtained. The test results are shown in Table 1.

Please refer to the fifth figure, which is a schematic diagram of a graphite sheet with high thermal conductivity (high thermal conductivity in the Z-axis direction) applied to a water-cooling device according to the present invention. As shown in FIG. 5, in order to let the heat of the heat source 51 take away the cooling water 52 (the direction of the arrow is the direction of the water flow), a graphite sheet 53 with high thermal conductivity alignment (high thermal conductivity in the Z-axis direction) of the present invention can be used as The separation layer of the heat source and the cooling water replaces other metal materials 54 used for heat dissipation. The graphite sheet with high thermal conductivity of the present invention has better high thermal conductivity characteristics in the Z-axis direction, thereby improving heat exchange speed.

The above-mentioned embodiments are only for illustrative purposes to explain the features and effects of this creation, and are not intended to limit the scope of the substantial technical content of this creation. Anyone familiar with the art can modify and change the above embodiments without departing from the spirit and scope of the creation. Therefore, the scope of protection of the rights of this creation shall be as listed in the scope of patent application mentioned later.

S101-S105‧‧‧step

Claims (9)

A method for manufacturing a graphite sheet with high thermal conductivity alignment, the steps include: (A) providing a plurality of thermally cracked graphite papers in a first direction and placing them in a hot-pressing fixture for a thermal pressing process to obtain a thermally cracked graphite block; B) The pyrolytic graphite block is placed in a glue-fixing fixture, and then the glue-fixing fixture is placed in a pressure kettle, and a vacuum process is performed; (C) A glue-fixing solvent is injected into the pressure kettle, and a Pressing process; (D) taking out the thermally cracked graphite block for a heat treatment; (E) cutting the thermally cracked graphite block in a second direction to obtain a graphite sheet with high thermal conductivity. The method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of the patent application, wherein the first direction is a direction parallel to the plane of the thermally cracked graphite paper, and the second direction is perpendicular to the thermally cracked graphite paper. Direction of the plane. The method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of the patent application, wherein the thermally cracked graphite paper is coated with phenol resin, and the phenolic resin coating area is the four sides of the thermally cracked graphite paper and A little in the middle. The method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of patent application, wherein the pressure range of the hot pressing process is 50 ~ 100kg / cm ² . According to the method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of patent application, there are three sets of pipelines and valves above the autoclave, which respectively control the processes of evacuating, injecting the solvent, and pressurizing the air. According to the method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of the patent application, the penetrating solvent contains phosphoric acid, pure water, and furan alcohol, and the ratio is 1: 10: 100. According to the method for manufacturing a graphite sheet with a high thermal conductivity alignment as described in item 1 of the scope of the patent application, wherein the liquid level of the glue-penetrating solvent in the autoclave exceeds the glue-penetrating jig. According to the method for manufacturing a graphite sheet with high thermal conductivity as described in item 7 of the scope of the patent application, step (C) further includes a step, wherein after the pressurizing process is performed, the thermally cracked graphite block is taken out for an infiltration. Process. The method for manufacturing a graphite sheet with high thermal conductivity as described in item 1 of the scope of the patent application, wherein the heat treatment includes a 4-stage heating process.