KR20220016582A - Thick graphite foil and Method for making the same - Google Patents

Abstract

Disclosed is a method for manufacturing a thick graphite foil having a thick thickness and excellent thermal conductivity in a thickness direction. The thick graphite foil is manufactured by mixing carbon powder with a polymer resin to form a liquid slurry, casting the slurry and at least drying it to form a green foil, performing first and second heat treatment on the green foil to form a graphitized foil, and then rolling the graphitized foil in the thickness direction.

Description

Thick graphite foil and method for making the same

The present invention relates to a method for manufacturing a thick-film graphite foil, and more particularly, to a method for manufacturing a thick-film graphite foil having a thick thickness and excellent thermal conductivity in the thickness direction.

Graphite is important as an industrial material because it has excellent heat resistance, chemical resistance, high thermal conductivity and high electrical conductivity. have. In particular, graphite is manufactured in a sheet shape with a uniform thickness and when provided in electronic devices with a built-in heating element, has excellent thermal conductivity in the plane direction. It can be effectively cooled by transferring it to the outside.

Graphite on such a sheet may be used by being attached to an opposing heat source on only one side, or by having one side attached to the opposing heat source and the other side being in contact with an object facing the opposite direction in the other direction. Graphene forming one layer is well arranged in the plane direction, so that the thermal conductivity in the plane direction is much better than the thermal conductivity in the thickness direction.

Such a graphite sheet may be divided into a natural graphite sheet and an artificial graphite sheet.

One type of natural graphite sheet is manufactured by increasing the purity of the graphite powder mined from nature, then applying heat at high temperature and continuously pressing a large force with a roll press to make a natural graphite foil in a roll, and then cutting it. .

Since these natural graphite sheets are manufactured using natural graphite, the material cost is low and the thickness can be made thick, while the hexagonal shape of carbon is non-uniform and irregularly arranged, and furthermore, in order to have mechanical properties, impurities other than carbon There is a disadvantage in that the thermal conductivity is worse than that of a conventional artificial graphite sheet.

On the other hand, the artificial graphite sheet, for example, a polyimide (PI) film prepared for artificial graphite in a roll state is put in a thermal decomposition furnace and maintained at around 1200 ° C., the polyimide film is carbonized and carbonized film becomes this

A polyimide film usually used for manufacturing an artificial graphite sheet is made of a polyimide resin containing polyamic acid.

After that, when the carbonized film is put into another thermal decomposition furnace and the temperature is raised while supplying argon gas and maintained at around 2800° C., the carbonized polymer film becomes a graphitized film. In this case, the polyimide film usually contains a foaming agent and foamed during heat treatment for carbonization or graphitization, so that the graphitized film maintains a foamed state.

After that, when the foamed graphitized film is continuously pressed and rolled with a large force with a roll press, the foamed graphitized film is compressed to a low density in the thickness direction, and as a result, the thickness becomes thinner and becomes an artificial graphite foil with a smooth surface.

These artificial graphite foils have almost no impurities and are configured to be stacked in the thickness direction in a state in which graphene layers with very thin thickness are relatively uniformly arranged in the plane direction, so that the thermal conductivity in the plane direction is good as about 900 W/mK or more. However, the thermal conductivity in the thickness direction is bad at about 50 W/mK or less because the graphene is stacked up and down, and in particular, the thicker the thickness, the worse the thermal conductivity in the thickness direction. A polyimide (PI) film invented for such artificial graphite and an artificial graphite sheet manufactured using the same are disclosed in Korean Patent Registration Nos. 10-2063215 and the like.

As described above, in order to manufacture an artificial thick film graphite foil having a relatively thick thickness, for example, an artificial thick film graphite foil having a thickness of 0.10 mm or more by the conventional manufacturing method, a polyimide film having a corresponding thick thickness must be prepared and then carbonized - foamed - graphitized - rolled. However, there is a disadvantage in that it is difficult to economically and reliably provide a thick polyimide film and an artificial thick film graphite foil applied thereto due to the specific gravity and viscosity of the liquid polyimide resin for the polyimide film. For example, there is a limit to increasing the solid content ratio of a liquid polyimide resin for the production of a graphite sheet with high thermal conductivity. Considering the shrinkage of the solvent during drying, it is difficult and expensive to manufacture a thick polyimide film. this costs a lot

Looking at Korean Patent Laid-Open No. 10-2020-0057314 as another conventional technique, it is described that graphitization includes a plurality of firing steps of heat-treating the sheet pre-body at different temperature rising rates.

However, it is difficult to provide a thick polyimide film economically even by such a technology, and even if a thick film is provided, it is composed of only a polyimide film and it takes a lot of time to carbonize and graphitize it. There is a limit to improving the thermal conductivity in the thickness direction with a constant arrangement.

As another conventional technique, when thick artificial graphite is needed, several sheets of thin artificial thick film graphite foil with good thermal conductivity can be alternately laminated with an adhesive interposed therebetween. In particular, the thermal conductivity in the thickness direction is not good, and since several sheets of thick graphite foil are adhered using a separate adhesive, there are conventional performance, quality and economical disadvantages.

In addition, when a force is applied in the thickness direction of the graphite laminate, there is a disadvantage in that interlayer separation occurs in the thickness portion where the pressure-sensitive adhesive is not formed.

As another conventional technique, according to Korean Patent Registration No. 1473708, there is a method for manufacturing a plate in which graphite powder is complexed on a metal matrix, comprising the steps of: (a) coating a metal on the plate-shaped graphite powder; (b) applying vibration to the metal-coated graphite powder so that the plate-shaped graphite powder is oriented in a horizontal direction; (c) molding the graphite powder oriented in the horizontal direction by pressing; (d) making a bulk material by sintering the pressurized graphite powder; and (e) cutting the bulk material to a predetermined thickness in a direction perpendicular to the direction oriented in the horizontal direction to make a plate so that the plate-shaped graphite powder is oriented parallel to the thickness direction of the plate to be formed; Disclosed is a method of manufacturing a heat sink having excellent heat conduction properties in the thickness direction including the thickness.

According to this technique, there is a disadvantage in that the in-plane thermal conductivity of the metal is inferior because the in-plane thermal conductivity is worse than that of the graphite sheet.

In addition, since the heat sink manufactured in this way needs to be manufactured in the shape of a block of a certain size or more to be economical, the block is cut thinly so that graphite powder does not occur in the case of a product with a relatively thin thickness, for example, 0.3 mm. There are disadvantages in that productivity is poor and the cut surface is not smooth.

Accordingly, it is an object of the present invention to provide a method of manufacturing a thick-film graphite foil that can easily, economically, and reliably provide a thick-film graphite foil having a relatively thick thickness and excellent thermal conductivity in the thickness direction.

Another object of the present invention is to provide a method for manufacturing a thick-film graphite foil that can easily control the thickness of the thick-film graphite and prevent separation in the thickness direction while providing electrical insulation.

According to one aspect of the present invention, the step of preparing a carbon powder; evenly mixing the carbon powder with a liquid polymer resin to form a liquid slurry; casting the slurry and at least drying to form a green foil having a uniform thickness; forming a carbonized foil by first heat-treating the green foil; forming a graphitized foil by subjecting the carbonized foil to a second heat treatment; and rolling the graphitized foil in the thickness direction to make the thickness constant and to smooth the surface.

Preferably, the carbon powder may be natural graphite powder, artificial carbon powder or artificial graphite powder.

Preferably, the natural graphite powder may have a carbon content of 95% or more.

Preferably, the artificial carbon powder may be formed by pulverizing and foaming the polyimide film corresponding to the artificial carbon powder after carbonization, or may be formed from petroleum-based pitch.

Preferably, the artificial graphite powder may be formed by pulverizing the polyimide film corresponding to the artificial graphite powder after carbonization and graphitization, and may be foamed, or may be formed from petroleum-based pitch.

Preferably, the liquid polymer resin is a liquid polyimide resin, and when the liquid polyimide resin is cast alone, dried, cured, carbonized heat treatment, graphite heat treatment, and rolled, it may be a material that becomes a specific artificial graphite sheet, The thickness of the specific artificial graphite sheet may be 0.01 mm to 0.08 mm, and the thermal conductivity in the plane direction may be 800 W/K or more.

Preferably, the polymer resin includes at least polyamic acid, and the liquid polymer resin may be the same material as the liquid slurry.

Preferably, the polymer resin may be used for preparing a polyamic acid derivative by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate, followed by imidization by ring closure dehydration at a high temperature.

Preferably, the mixing ratio of the polymer resin and the carbon powder may be such that the green foil has a desired thickness and thermal conductivity.

Preferably, a foaming agent may be included in the polymer resin or the slurry.

Preferably, the drying is performed by heat to volatilize the solvent, and after drying, the polymer resin may be cured by heat. The drying and curing may be performed by a continuous process or a separate process.

Preferably, the green foil may be manufactured as a roll after the casting or may be cut to a predetermined length after being manufactured as a roll.

Preferably, the green foil may be a single-layered green foil or a multi-layered green foil. The single-layered green foil is made of only a green foil corresponding to the corresponding green foil, and the multi-layered green foil is formed by stacking at least two or more single-layered green foils. and may be integrally formed by applying heat and pressure, and the multi-layered green foil may be formed after drying or curing.

Preferably, the heat and pressure may be high temperature isostatic pressing or provided by a press.

Preferably, the thickness of the single-layer green foil may be 0.03 mm to 0.2 mm, and the thickness of the multi-layer green foil may be 0.1 mm to 1.5 mm.

Preferably, the first heat treatment is performed in an oxidizing atmosphere, and the dried polymer resin constituting the green foil is carbonized to form the carbonized foil at a temperature within 1,300° C., and the second heat treatment is performed in an argon gas atmosphere. It is made in a gas atmosphere that includes, and the carbonized foil is graphitized and may be made at a temperature within 3,000° C. so that the graphitized foil becomes the graphitized foil.

Preferably, the polymer resin may be foamed in the first or second heat treatment, and impurities of the carbon powder may be further removed or the thermal conductivity of the carbon powder may be improved by the first and second heat treatment. .

Preferably, the rolling is performed by pressure by a press, and heat may be simultaneously provided when the pressure is applied, and the thickness of the carbonized foil may be reduced by 50% to 90% by the rolling.

Preferably, the thick film graphite foil may be provided on a roll or sheet, and the thickness of the thick film graphite foil may be 0.07 mm to 1.2 mm.

According to another aspect of the present invention, the step of preparing a carbon powder; evenly mixing the carbon powder with a liquid polymer resin to form a liquid slurry; casting the slurry and at least drying to form a green foil having a uniform thickness; forming a single laminated foil by laminating and pressing two or more sheets of the green foil; forming a carbonized foil by first heat-treating the laminated foil; forming a graphitized foil by subjecting the carbonized foil to a second heat treatment; and rolling the graphitized foil in the thickness direction to make the thickness constant and to smooth the surface.

Preferably, a thermal curing process of the polyimide resin may be added after the drying.

Preferably, an insulating coating layer may be formed on at least a portion of the surface of the thick graphite foil by a deposition method, and the insulating coating layer may be made of parylene.

According to the present invention, since it is prepared by uniformly mixing carbonized or graphitized solid carbon powder with a liquid polymer resin, it is easy to provide a relatively thick green foil, and consequently, a thick thick graphite foil is economically manufactured. It is easy to do and has good thermal conductivity after graphitization.

In addition, since the solid carbon powder is mixed with the liquid polyimide resin used to manufacture the graphite sheet, the amount of polymer resin is small compared to the thickness of the thick-film graphite foil, resulting in easy production and drying, carbonization and graphitization time can reduce

In addition, the polymer resin or slurry contains a foaming agent and is foamed when carbonized or graphitized, so that it is easy to press after graphitization and to provide a smooth press with a uniform thickness and a smooth surface.

In addition, it is easy to economically provide a thick thick graphite foil because a multilayer green foil pressed after laminating the dried single layer green foil is used.

In addition, heat is provided during lamination pressing or rolling, so that pressing is uniform and easy.

In addition, by the heat treatment process of carbonization and graphitization that is additionally provided to the carbon powder, impurities of the carbon powder are additionally removed or the structure or arrangement of carbon is partially stabilized to provide better thermal conductivity. In addition, peeling in the thickness direction may be partially reduced by this structure.

In addition, the carbon arrangement of the solid carbon powder and the carbon arrangement of the graphite foil made of the polymer resin cross or mix with each other to improve thermal conductivity in the thickness direction.

In addition, in the case of using natural graphite powder as the carbon powder, there is an advantage that the material cost is reduced.

In addition, when the artificial carbon powder is used as the carbon powder, the manufacturing cost can be reduced because the polyimide film or the pitch providing the artificial carbon powder is not graphitized.

In addition, when an artificial graphite powder carbonized with carbon powder, foamed, and graphitized is used, a large amount of polymer solution is filled between the foamed pores to increase the filling density.

In addition, by forming an insulating coating layer thinly and uniformly on the surface of the graphite foil by vapor deposition, heat transfer efficiency is reduced to a minimum, it is not separated in the thickness direction, and it is possible to maintain insulation from an opposing object.

1 shows a thick-film graphite foil according to the present invention.
2 shows a method of manufacturing a thick-film graphite foil according to an embodiment of the present invention.
3 shows a method of manufacturing a thick-film graphite foil according to another embodiment of the present invention.

It should be noted that the technical terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. In addition, the technical terms used in the present invention should be interpreted as meanings generally understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise specifically defined in the present invention, and excessively comprehensive It should not be construed in the meaning of a human being or in an excessively reduced meaning.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a thick-film graphite foil according to the present invention.

In the thick film graphite foil 100 or sheet of the present invention, carbon powder 110 is mixed with a liquid polymer resin to form a liquid slurry, and the green foil formed by casting the slurry and at least drying the first and the first 2 After heat treatment to form carbonized and graphitized foil, the graphitized foil is rolled in the thickness direction to manufacture.

The thick film graphite foil 100 is flexible and can be easily cut by a Thompson blade.

In addition, the thermal conductivity in the surface direction of the thick-film graphite foil 100 may be 600 W/k or more, and the thermal conductivity in the thickness direction may be 15 W/k or more.

2 shows a method of manufacturing a thick-film graphite foil 100 according to an embodiment of the present invention.

First, a carbon powder is prepared (step S21).

Here, the carbon powder refers to a powder containing carbon as a main component, and refers to natural graphite powder, artificial carbon powder, artificial graphite powder, etc. mentioned below, but the present invention is not particularly limited thereto.

The carbon powder may be natural graphite powder, and the natural graphite powder may be used after pulverizing natural graphite collected from coal mines to remove impurities by sulfuric acid and heat treatment, etc. In this case, the carbon content may be 95% or more, The higher the carbon content, the better the thermal conductivity. This natural graphite powder has already been graphitized, has a thermal conductivity above a certain level, and has the advantage of being able to cope with the carbonization process and graphitization process of manufacturing the thick-film graphite foil 100 .

The shape and size of the carbon powder are not limited, but in consideration of the thickness and thermal conductivity of the thick-film graphite foil 100, the spherical or plate-shaped dimension may be 0.04 mm or less.

When natural graphite powder is used as the carbon powder, there is an advantage that material cost and process cost are greatly reduced.

In addition, the conventional natural graphite powder has the advantage that the thermal conductivity is lower than that of the conventional artificial graphite powder, but the price is low.

In addition, when the thick-film graphite foil 100 is manufactured using natural graphite powder, carbon molecules are cultured in various directions, so that the thermal conductivity in the thickness direction may be better than that of a conventional artificial graphite foil manufactured using a polyimide film alone.

The carbon powder may be an artificial carbon powder, and the artificial carbon powder is applied by carbonizing a polyimide film used in manufacturing an artificial graphite foil by heat treatment and then pulverizing it, or carbonizing a pitch extracted from petroleum by heat treatment After grinding, it can be applied.

Such heat treatment may be performed in an oxidizing atmosphere within 1,300°C.

Since the artificial carbon powder is used without graphitizing the polyimide film or pitch that provides the artificial carbon powder, the manufacturing cost is reduced, and the material cost is greatly reduced when the pitch is used.

The artificial carbon powder has an advantage that it can cope with the carbonization process and the graphitization process of manufacturing the thick-film graphite foil 100 by being already carbonized.

The carbon powder may be artificial graphite powder, and the polyimide film used in manufacturing the artificial graphite foil is carbonized and graphitized by heat treatment, then pulverized and applied, or a pitch extracted from petroleum is carbonized by heat treatment and graphite It can be applied by pulverizing and then grinding.

Here, when the polyimide film is carbonized and graphitized and then pulverized and formed, the artificial graphite powder may preferably be foamed.

When the artificial graphite powder carbonized, foamed, and graphitized with carbon powder is used, a large amount of liquid polymer resin is filled between the foamed pores to increase the filling density or facilitate casting.

The artificial graphite powder has already been graphitized and has the advantage of being able to respond to the carbonization process and graphitization process of manufacturing the thick-film graphite foil 100 .

In this way, the solid carbon powder is uniformly mixed with the liquid polymer resin, so that the slurry has a high solid content as a whole, which can provide a high slurry density or viscosity, so that it is easy to provide a thick green foil, resulting in a thick thick film It is easy to manufacture the graphite foil.

In addition, since the slurry in which the solid carbon powder is mixed with the liquid polymer resin is used, distortion or deformation due to the thick polymer resin during drying or curing of the polymer resin is small. As a result, there is an advantage that drying, curing, carbonization and graphitization times can be minimized.

In addition, since the solid carbon powder already carbonized or graphitized is used, it is easy to manufacture, economical, and has good thermal conductivity in the thickness direction.

Next, the carbon powder is evenly mixed with the liquid polymer resin to form a liquid slurry (step S22).

Preferably, the liquid polymer resin may be a slurry.

The liquid polymer resin is a liquid polyimide resin, and when the liquid polyimide resin is cast alone, dried, cured, carbonized, heat treated, and rolled to form a specific artificial graphite sheet.

Here, the thickness of the specific artificial graphite sheet may be 0.01 mm to 0.08 mm, and the thermal conductivity in the plane direction may be 800 W/K or more.

The polymer resin includes at least polyamic acid, and may be the same material as the liquid slurry.

The polymer resin may be used for preparing a polyamic acid derivative by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate, followed by imidization by ring closure dehydration at a high temperature.

Here, the mixing ratio of the polymer resin and the carbon powder may be configured to have a desired thickness and thermal conductivity of the green foil.

In this embodiment, the polymer resin or slurry may contain a foaming agent that is foamed during carbonization or graphitization heat treatment. When the foaming agent is carbonized or graphitized, the polymer resin is foamed so that it is easy to press after graphitization and has a uniform thickness It is easy to provide pressing and smooth pressing of the surface.

The liquid slurry is cast and at least dried to remove the solvent contained in the slurry to form a green foil having a uniform thickness (step S23).

Here, drying is performed by heat to volatilize the solvent, and after drying, the polymer resin may be cured by heat. Drying and curing may be performed by a continuous process or a separate process.

After the green foil is manufactured as a roll during casting, it may be manufactured as a roll in a subsequent process or may be cut to a predetermined length after being manufactured as a roll.

In this embodiment, the green foil may be a single-layered green foil or a multi-layered green foil, the single-layered green foil is made of only the green foil corresponding to the corresponding green foil, and the multi-layered green foil is formed by laminating two or more single-layered green foils and then heat and It can be formed by applying pressure, and heat and pressure can also be applied to a single-layer green foil.

Here, as the single-layer green foil laminated on the multi-layer green foil, a dried single-layer green foil or a hardened single-layer green foil may be used, and compression and adhesion of the single-layer green foil are easily performed after drying, but the present invention is not limited thereto.

Heat and pressure after lamination may be high temperature isostatic pressing or may be provided by a press.

The thickness of the thick-film graphite foil can be economically and freely adjusted by the structure of the multi-layered green foil by lamination of the single-layered green foil.

Preferably, the thickness of the single-layer green foil may be 0.03 mm to 0.2 mm, and the thickness of the multi-layer green foil may be 0.1 mm to 1.5 mm.

Thereafter, the green foil is subjected to a first heat treatment to form a carbonized foil (step S24).

The first heat treatment is performed in an oxidizing atmosphere at a temperature within 1,300° C. so that the dried polymer resin constituting the green foil is carbonized and becomes a part of the carbonized foil.

Next, the carbonized foil is subjected to a second heat treatment to form a graphitized foil (step S25).

The second heat treatment is performed in a gas atmosphere such as an argon gas atmosphere at a temperature within 3,000° C. so that the dried and carbonized polymer resin constituting the green foil is graphitized to become a graphitized foil.

Preferably, the dried polymer resin is foamed by the first or second heat treatment. By this foaming, it is easy to press during rolling, and it is easy to provide a press of a uniform thickness and a smooth surface.

As described above, by the heat treatment process of carbonization and graphitization that is additionally provided to the carbon powder, impurities of the carbon powder are additionally removed or the structure or arrangement of carbon is further partially stabilized, so that the thick-film graphite foil provides better thermal conductivity. and peeling in the thickness direction may be partially reduced.

Finally, the graphitized foil is rolled in the thickness direction to make the thickness constant and to smooth the surface (step S26).

The rolling is effected by a press, and preferably heat can be provided simultaneously when pressure is applied.

By rolling, the carbonized greenfoil thickness can be reduced by 50% to 90% of its original thickness.

As described above, the thick-film graphite foil may be provided with a predetermined length after being manufactured into a sheet or roll, for example, the thick-film graphite foil may have a thickness of 0.07 mm to 1.2 mm.

After that, by forming an insulating coating layer thinly and uniformly on the surface of the thick-film graphite foil manufactured by applying the multi-layered green foil through a deposition process, the heat transfer efficiency of the thick-film graphite foil is reduced to a minimum, and the thick-film graphite foil is not easily separated in the thickness direction. and can maintain insulation with opposing objects.

Preferably, the insulating coating layer is formed by vapor deposition by an evaporator, and the deposition material is a flexible and tough heat-resistant polymer resin, and the deposition thickness is as thin as 0.001 mm to 0.01 mm.

Preferably, the heat-resistant polymer resin may be parylene.

The surface of the thick-film graphite foil is not exposed to the outside by such an insulating coating layer, so that the graphite powder of the thick-film graphite foil is not smeared or dropped by an external force.

3 shows a method of manufacturing a thick-film graphite foil according to another embodiment of the present invention.

First, a carbon powder is prepared (step S31), and the carbon powder is evenly mixed with a polymer resin containing at least polyamic acid to form a liquid slurry (step S32), and the slurry is cast and at least dried to have a uniform thickness A green foil is formed (step S33).

In addition, a thermal curing process of the polymer resin after drying may be added.

Thereafter, two or more single-layer green foils are laminated and pressed to form a multi-layered green foil (step S34).

Here, the lamination may be made of a green foil sheet or roll.

The multilayer green foil is first heat-treated to form a carbonized foil (step S35), and the carbonized foil is subjected to a second heat treatment to form a graphitized foil (step S36).

Next, the graphitized foil is rolled in the thickness direction to make the thickness constant and to smooth the surface (step S37).

Here, heat may be provided in at least one of the lamination or rolling processes among steps S34 and S37.

As in this embodiment, it is easy to provide a thick graphite foil having a thicker thickness by laminating the dried single-layer green foil and then pressing the integrated multi-layer green foil. In addition, it is possible to do a lot while uniformly pressing by providing heat during lamination pressing or rolling.

Preferably, as in the above embodiment, an insulating coating layer may be further formed on at least a portion of the surface of the thick graphite foil by a deposition method.

In this way, by forming the insulating coating layer thinly and uniformly on the surface of the graphite foil by vapor deposition, the heat transfer effect is reduced to a minimum, and it is possible to maintain insulation from the opposing object without being separated in the thickness direction.

Although the above description has been focused on the embodiments of the present invention, it goes without saying that various changes may be made at the level of those skilled in the art. Accordingly, the scope of the present invention cannot be construed as being limited to the above-described embodiments, and should be construed by the claims described below.

100: thick graphite foil
110: carbon powder

Claims (40)

preparing carbon powder;
evenly mixing the carbon powder with a liquid polymer resin to form a liquid slurry;
casting the slurry and at least drying to form a green foil having a uniform thickness;
forming a carbonized foil by first heat-treating the green foil;
forming a graphitized foil by subjecting the carbonized foil to a second heat treatment; and
and rolling the graphitized foil in the thickness direction to make the thickness constant and to smooth the surface. In claim 1,
The carbon powder is a method of manufacturing a thick-film graphite foil, characterized in that natural graphite powder, artificial carbon powder or artificial graphite powder. In claim 2,
The method for producing a thick-film graphite foil, characterized in that the natural graphite powder has a carbon content of 95% or more. In claim 2,
The artificial carbon powder is formed by pulverizing the polyimide film corresponding to the artificial carbon powder after carbonization,
The artificial graphite powder is a method of manufacturing a thick-film graphite foil, characterized in that the polyimide film corresponding to the artificial graphite powder is carbonized and graphitized and then pulverized. In claim 2,
The method of manufacturing a thick-film graphite foil, characterized in that the artificial carbon powder and the artificial graphite powder are foamed. In claim 2,
The method for manufacturing a thick-film graphite foil, characterized in that the artificial carbon powder and the artificial graphite powder are formed from petroleum-based pitch. In claim 1,
The liquid polymer resin is a liquid polyimide resin, which is a material that becomes a specific artificial graphite sheet when the liquid polyimide resin is cast alone, dried, cured, carbonized heat treatment, graphite heat treatment, and rolled. A method for manufacturing a foil. In claim 7,
The thickness of the specific artificial graphite sheet is 0.01 mm to 0.08 mm, and the thermal conductivity in the plane direction is 800 W/K or more. In claim 1,
The method for producing a thick-film graphite foil, characterized in that the polymer resin comprises at least polyamic acid. In claim 1,
The liquid polymer resin is a method of manufacturing a thick-film graphite foil, characterized in that the same material as the liquid slurry. In claim 1,
The polymer resin is used for preparing a polyamic acid derivative by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate, followed by imidization by ring closure dehydration at a high temperature. In claim 1,
A method for manufacturing a thick-film graphite foil, characterized in that the mixing ratio of the polymer resin and the carbon powder is such that the green foil has a desired thickness and thermal conductivity. In claim 1,
A method for producing a thick-film graphite foil, characterized in that the polymer resin or the slurry contains a foaming agent. In claim 1,
The method of manufacturing a thick-film graphite foil, characterized in that the drying is made by heat to volatilize the solvent. In claim 1,
A method of manufacturing a thick-film graphite foil, characterized in that the polymer resin is cured by heat after drying. In claim 15,
The method of manufacturing a thick-film graphite foil, characterized in that the drying and the curing are made by a continuous process or a separate process. In claim 1,
The green foil is manufactured into a roll after the casting, or a method of manufacturing a thick-film graphite foil, characterized in that it is cut to a predetermined length after being manufactured as a roll. In claim 1,
The method of manufacturing a thick-film graphite foil, characterized in that the green foil is a single-layer green foil or a multi-layer green foil. 19. In claim 18,
The single-layered green foil is made of only a green foil corresponding to the corresponding green foil, and the multi-layered green foil is formed integrally by stacking at least two or more single-layered green foils and applying heat and pressure. Way. 20. In claim 19,
The method for manufacturing a thick-film graphite foil, characterized in that the multi-layer green foil is formed after drying or curing of the single-layer green foil. 20. In claim 19,
The method of manufacturing a thick-film graphite foil, characterized in that the heat and pressure are provided by high-temperature isostatic pressing or a press. In claim 1,
The first heat treatment is a method of manufacturing a thick-film graphite foil, characterized in that the dried polymer resin constituting the green foil is carbonized at a temperature within 1,300 ℃ so that the carbonized foil. 23. In claim 22,
The first heat treatment is a method of manufacturing a thick-film graphite foil, characterized in that made in an oxidizing atmosphere. In claim 1,
The second heat treatment is a method of manufacturing a thick-film graphite foil, characterized in that the carbonized foil is graphitized so as to become the graphitized foil at a temperature within 3,000°C. 25. In claim 24,
The second heat treatment is a method of manufacturing a thick-film graphite foil, characterized in that made in a gas atmosphere including an argon gas atmosphere. In claim 1,
A method of manufacturing a thick-film graphite foil, characterized in that foaming of the polymer resin is performed in the first or second heat treatment. In claim 1,
The method for manufacturing a thick-film graphite foil, characterized in that by the first and second heat treatment, impurities of the carbon powder are further removed or thermal conductivity of the carbon powder is improved. In claim 1,
The rolling is a method of manufacturing a thick-film graphite foil, characterized in that made by pressure by a press. 29. The method of claim 28,
A method of manufacturing a thick-film graphite foil, characterized in that heat is simultaneously provided when the pressure is applied. In claim 1,
A method of manufacturing a thick-film graphite foil, characterized in that the thickness of the carbonized foil is reduced by 50% to 90% by the rolling. preparing carbon powder;
evenly mixing the carbon powder with a liquid polymer resin to form a liquid slurry;
casting the slurry and at least drying to form a green foil having a uniform thickness;
forming a single laminated foil by laminating and pressing two or more sheets of the green foil;
forming a carbonized foil by first heat-treating the laminated foil;
forming a graphitized foil by subjecting the carbonized foil to a second heat treatment; and
and rolling the graphitized foil in the thickness direction to make the thickness constant and to smooth the surface. 32. In claim 31,
After the drying, a method of manufacturing a thick-film graphite foil, characterized in that the heat curing process of the polyimide resin is added. 32. In claim 31,
The lamination is a method of manufacturing a thick-film graphite foil, characterized in that the green foil is made of a sheet or a roll. 32. In claim 31,
A method of manufacturing a thick-film graphite foil, characterized in that heat is provided in at least one process during the pressing or the rolling. 32. In claim 1 or 31,
The method of manufacturing a thick-film graphite foil, characterized in that it further comprises the step of forming an insulating coating layer on at least a portion of the surface of the thick-film graphite foil by a deposition method. 36. The method of claim 35,
The method of manufacturing a thick-film graphite foil, characterized in that the insulating coating layer is parylene (parylene). A thick film graphite foil, characterized in that produced by the manufacturing method of claim 1 or 31. 38. The method of claim 37,
The thick-film graphite foil has flexibility and is easily cut by a Thompson blade. 38. The method of claim 37,
The thick-film graphite foil, characterized in that the thermal conductivity in the surface direction of the thick-film graphite foil is 600W/k or more, and the thermal conductivity in the thickness direction is 15W/k or more. 38. The method of claim 37,
Thick-film graphite foil, characterized in that the insulating coating layer is formed on at least a portion of the surface of the thick-film graphite foil by a deposition method.

Images