LU502863B1

LU502863B1 - Method for preparing high-thermal-conductivity graphite film

Info

Publication number: LU502863B1
Application number: LU502863A
Authority: LU
Inventors: Wei Tang; Wenjing Wang
Original assignee: Zhonghui Ruineng Fengyang New Material Tech Co Ltd
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2023-03-30

Abstract

Described is a method for preparing a high-thermal-conductivity graphite film. The method comprises the following steps: taking a graphite-phase carbon nitride and polyimide composite as a graphite film precursor, and taking graphite-phase carbon nitride as an orientation and crystallization inducer in the high-temperature carbonization and graphitization process to promote graphitization of polyimide, so as to prepare the high-thermal-conductivity graphite film. With the adoption of the method, the temperature in the graphitization technique is reduced, and thus the energy consumption is decreased; and moreover, the crystallinity of the graphite film can be improved, and the graphite film is good in flexibility and high in thermal conductivity, thus the high heat dissipation requirement of the existing microelectronic industry is met, the amorphous defects of the graphite film are reduced, and the thermal conductivity and mechanical properties of the graphite film are improved.

Description

METHOD FOR PREPARING HIGH-THERMAL-CONDUCTIVITY GRAPHITE FILM

LU502863

Technical Field

The present invention mainly relates to the technical field of thermal-conductivity films, and particularly relates a method for preparing a high-thermal-conductivity graphite film by using graphite-phase carbon nitride (g-CsN4) to induce orientation and crystallization of polyimide.

Background Art

With the rapid development of modern microelectronic industry and high-frequency high- speed communication technique, electronic equipment and integrated circuits develop to miniaturization and high density, and the miniature high-density interconnect (HDI) integrated circuit has become one of the future development trends. In the HDI, the density of wires and electronic components is greatly increased, and the locally generated heat is quickly accumulated and increased, thereby causing negative effects on the service lives of the electronic components and influencing the stability and reliability of the components. Besides, in the high-frequency high-speed communication system, the heat productivity of the components is much higher than that of the low-frequency communication, which further requires heat dissipation components with high thermal conductivity in the electronic equipment and integrated circuit to quickly transfer the heat to heat dissipation equipment or outside in time, thereby ensuring the service life and stability of the electronic equipment.

At present, a metal sheet or a graphite film is usually used for conducting heat in the electronic component, however, the metal dissipation sheet is larger in mass and poorer in flexibility and cannot meet the development requirement of light weight and thinness of the electronic equipment. The graphite film is used as a heat-transfer medium, has the advantage of light weight and is widely applied to portable electronic equipment such as a mobile phone and a computer. A method for preparing the graphite film mainly comprises two modes: 1, artificial graphite is laminated into a film, this mode is simple to operate, but the prepared graphite film cannot reach ideal thermal conductivity and mechanical properties, and particularly, the flexibility and the strength cannot meet the requirement; and 2, the graphite film is directly prepared by graphitization of a polymer film, the graphite film prepared by this mode generally has good flexibility and thermal conductivity, but the energy consumption is very high in the high-temperature graphitization process, a large number of amorphous defects due to incomplete graphitizing are easy to occur, which seriously influences the thermal conductivity and electric-conducting properties of the graphite film. Therefore, how to reduce the graphitization temperature, simultaneously improve the graphitized crystalline structure and reduce the amorphous defects is an important topic to be solved for the high-thermal- conductivity graphite film.

Summary of the Invention LU502863 1. Object

The present invention provides a method for preparing a high-thermal-conductivity graphite film by using graphite-phase carbon nitride to induce orientation and crystallization of polyimide. 2. Technical Solution

In order to achieve the above object, a technical solution provided by the present invention is that a method for preparing a high-thermal-conductivity graphite film comprises the steps of taking a graphite-phase carbon nitride and polyimide composite as a graphite film precursor, and taking graphite-phase carbon nitride as an orientation and crystallization inducer in the high-temperature carbonization and graphitization process to promote graphitization of polyimide, so as to prepare the high-thermal-conductivity graphite film.

Further, the specific preparation method comprises the following steps:

Step 1, sequentially adding an organic solvent, graphite-phase carbon nitride and a modifying assistant into a reaction kettle, and reacting at a high speed under a high temperature of 30°C for 2-12 h;

Step 2, sequentially adding dianhydride and a diamine compound into the reaction system, and reacting at 5-30°C for 2 h under nitrogen gas protection to obtain a graphite-phase carbon nitride hybrid polyamic acid solution:

Step 3, making the graphite-phase carbon nitride hybrid polyamic acid solution obtained in the step 2 uniform, carrying out casting, drying and imidization film preparation treatment on the uniform graphite-phase carbon nitride hybrid polyamic acid solution to obtain a graphite-phase carbon nitride hybrid polyimide film; and

Step 4, carrying out carbonization and graphitization calcining on the obtained polyimide film to graphitize the polyimide carbonized film, and carrying out calendaring treatment on the graphitized polyimide carbonized film to obtain the artificial graphite film.

Further, the organic solvent is composed of one or more of N-methylpyrrolidone (NMP), N,

N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO).

Further, the graphite-phase carbon nitride is in a flaky shape, and the plane size is 10-1,000 nm.

Further, the modifying assistant that is an organosiloxane compound is composed of one or more of KH550, KH560, KH570 and KH590.

Further, the dianhydride is composed of one or more of pyromellitic dianhydride, 3, 3’, 4, 4’- biphenyltetracarboxylic dianhydride, 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride, 2, 3, 6, 7-naphthalenetetracarboxylic dianhydride and 3, 4, 9, 10-perylenetetracarboxylic dianhydride.

Further, the diamine compound is composed of one or more of p-phenylenediamine, 1, 3- diaminobenzene, 4, 4-diaminodiphenyl, 1, 2-diaminobenzene, 4, 4-diaminodiphenylpropane, 4, 4’-oxybisbenzenamine and 4, 4-dimethoxybenzophenone.

Further, the molar ratio of dianhydride to the diamine compound is 1: (0.995-1.005); the LU502863 mass of graphite-phase carbon nitride is 0.1-0.5wt% of the total mass of dianhydride and the diamine compound; the mass of the modifying assistant is 10-30wt% of that of the graphite- phase carbon nitride (g-C3N4); and the total solid content of the graphite-phase carbon nitride hybrid polyamic acid solution is 15-20wt%.

Further, a high-thermal-conductivity graphite film is prepared by the abovementioned preparation method. 3. Beneficial effects

Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: in the present invention, the graphite-phase carbon nitride and polyimide composite is used as the graphite film precursor; the graphite-phase carbon nitride (g-CsN4) is used as the orientation and crystallization inducer in the high-temperature carbonization and graphitization process to promote graphitization of polyimide. In the present invention, the flaky nano graphite- phase carbon nitride (g-CsN4) introduced into the graphite film has an intrinsic crystalline graphitized carbon structure, and can be used as a graphitized carbon template in the stretching and graphitization process to induce the polyimide molecule orientation and graphitized carbon crystallization process, thereby reducing the generation of amorphous defects in the graphitization process and further improving the thermal conductivity and mechanical properties of the graphite film; and on one hand, the prevent invention can reduce the temperature in the graphitization technique, and thus the energy consumption is reduced; and on the other hand, the crystallinity of the graphite film can be improved, the amorphous defects are reduced, and the thermal conductivity and mechanical properties of the graphite film are improved. The high-thermal- conductivity graphite film prepared by the method provided by the present invention is good in flexibility and high in thermal conductivity, and thus the high heat dissipation requirement of the existing microelectronic industry is met.

Detailed Description of the Invention

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the related drawings, in which several embodiments of the present invention are shown, however, the present invention may be implemented in many different forms and is not limited to the embodiments described herein, conversely, these embodiments are provided so that this prevent invention will be thorough and complete.

It is to be noted that when an element is referred to as being “fixed to” another element, it can be directly on the other element or an intervening element may also be present; when an element is considered to be “connected” to another element, it may be directly connected to the other element or the intervening element may be present; and the terms “vertical”, horizontal”, ||. oes “left”, “right” and similar expressions are used herein for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical art of the present invention; the terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention; as used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Embodiment 1 88 L of DMF, 7.5 g of graphite-phase carbon nitride (g-CsN4) and 0.15 g of KH550 were sequentially added into a reaction kettle and mechanically stirred to react at 5°C for 2 h. 20 mol of 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride and 20 mol of p- phenylenediamine were sequentially added into the reaction system and reacted at 5°C under nitrogen gas protection for 2 h to obtain a graphite-phase carbon nitride (g-CsN4) hybrid polyamic acid solution.

Defoaming was performed on the graphite-phase carbon nitride (g-CsN4) hybrid polyamic acid solution; the solution was taken out and then uniformly coated on a toughened glass plate by an automatic coating machine until the film thickness was 50 um; then the toughened glass plate coated with the polyamic acid solution was put into a high-temperature oven, and the heating and temperature maintaining speeds were controlled for performing imidization, wherein the imidization technique comprised the following steps: maintaining the temperature at 60°C for 45 min, heating to 110°C and maintaining the temperature for 10 min, heating to 200°C and maintaining the temperature for 5 min, heating to 270°C and maintaining the temperature for 5 min, and heating to 350°C and maintaining the temperature for 3 min.

After the obtained graphite-phase carbonized nitrogen (g-CsN4) hybrid polyimide film was stripped, carbonization-graphitization calcining was further performed as follows: cutting the obtained polyimide film to 300 x 300 mm, and vertically putting the film surface into the graphite to obtain a cylindrical closed holding container. Then the container was heated to 1,100°C in argon gas at a rate of 3°C/min and was maintained for 1 h to obtain a polyimide carbonized film; and then the polyimide carbonized film was heated to 2,850°C at a rate of 3°C/min and was continuously calcined for 1 h to realize graphitization.

Finally, the obtained graphite sheet was clamped between two calendaring rollers for calendaring to obtain an artificial graphite film of 25 um, wherein the thermal conductivity coefficient was 1,680 W/m. k.

Embodiment 2 LU502863 60 L of DMF, 100 g of graphite-phase carbon nitride (g-CsN4) and 3 g of KH550 were sequentially added into a reaction kettle and mechanically stirred to react at 20°C for 6 h. 20 mol of 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride and 20 mol of p- 5 phenylenediamine were sequentially added into the reaction system and reacted at 25°C under nitrogen gas protection for 6 h to obtain a graphite-phase carbon nitride (g-CsN4) hybrid polyamic acid solution.

Defoaming was performed on the graphite-phase carbon nitride (g-CsN4) hybrid polyamic acid solution; the solution was taken out and then uniformly coated on a toughened glass plate by an automatic coating machine until the film thickness was 50 um; the toughened glass plate coated with the polyamic acid solution was put into a high-temperature oven, and the heating and temperature maintaining speeds were controlled for performing imidization, wherein the imidization technique comprised the following steps: maintaining the temperature at 60°C for 45 min, heating to 110°C and maintaining the temperature for 10 min, heating to 200°C and maintaining the temperature for 5 min, heating to 270°C and maintaining the temperature for 5 min, and heating to 350°C and maintaining the temperature for 3 min.

After the obtained graphite-phase carbonized nitrogen (g-CsN4) hybrid polyimide film was stripped, carbonization-graphitization calcining was further performed as follows: cutting the obtained polyimide film to 300 x 300 mm, and vertically putting the film surface into graphite to obtain a cylindrical closed holding container. Then the container was heated to 1,100°C in argon gas at a rate of 3°C/min and was maintained for 1 h to obtain a polyimide carbonized film; and then the polyimide carbonized film was heated to 2,850°C at a rate of 3°C/min and was calcined for 1 h to realize graphitization.

Finally, the obtained graphite sheet was clamped between two calendaring rollers for calendaring to obtain an artificial graphite film of 25 um, wherein the thermal conductivity coefficient was 1,550 W/m k.

Embodiment 3

L of DMF, 376 g of graphite-phase carbon nitride (g-CsN4) and 18.8 g of KH550 were 30 sequentially added into a reaction kettle and mechanically stirred to react at 30°C for 12 h. 20 mol of 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride and 20 mol of p- phenylenediamine were sequentially added into the reaction system and reacted at 30°C under nitrogen gas protection for 16 h to obtain a graphite-phase carbon nitride (g-CsNa4) hybrid polyamic acid solution.

Defoaming was performed on the graphite-phase carbon nitride (g-CsN4) hybrid polyamic acid solution; the solution was taken out and then uniformly coated on a toughened glass plate by an automatic coating machine until the film thickness was 50 um; the toughened glass plate coated with the polyamic acid solution was put into a high-temperature oven, and the heating and temperature maintaining speeds were controlled for performing imidization, wherein the LU502863 imidization technique comprised the following steps: maintaining the temperature at 60°C for 45 min, heating to 110°C and maintaining the temperature for 10 min, heating to 200°C and maintaining the temperature for 5 min, heating to 270°C and maintaining the temperature for 5 min, and heating to 350°C and maintaining the temperature for 3 min.

Finally, the obtained graphite sheet was clamped between two calendaring rollers for calendaring to obtain an artificial graphite film of 25 um, wherein the thermal conductivity coefficient was 1,503 W/m.k.

Contrast 60 L of DMF, 20 mol of 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride and 20 mol of p- phenylenediamine were sequentially added into a reaction kettle and reacted at 25°C under nitrogen gas protection for 6 h to obtain a polyamic acid solution.

Defoaming was performed on the polyamic acid solution; the solution was taken out and then uniformly coated on a toughened glass plate by an automatic coating machine until the film thickness was 50 um; the toughened glass plate coated with the polyamic acid solution was put into a high-temperature oven, and the heating and temperature maintaining speeds were controlled for performing imidization, wherein the imidization technique comprised the following steps: maintaining the temperature at 60°C for 45 min, heating to 110°C and maintaining the temperature for 10 min, heating to 200°C and maintaining the temperature for 5 min, heating to 270°C and maintaining the temperature for 5 min, and heating to 350°C and maintaining the temperature for 3 min.

After the obtained polyimide film was stripped, carbonization-graphitization calcining was further performed as follows: cutting the obtained polyimide film to 300 x 300 mm, and vertically putting the film surface into graphite to obtain a cylindrical closed holding container. Then the container was heated to 1,100°C in argon gas at a rate of 3°C/min and was maintained for 1 h to obtain a polyimide carbonized film; and then the polyimide carbonized film was heated to 2,850°C at a rate of 3°C/min and was calcined for 1 h to realize graphitization.

Finally, the obtained graphite sheet was clamped between two calendaring rollers for calendaring to obtain an artificial graphite film of 25 um, wherein the thermal conductivity coefficient was 874 W/m k.

According to the embodiment and the contrast, on one hand, the prevent invention could, 502863 reduce the temperature in the graphitization technique, and thus the energy consumption was reduced; and on the other hand, the crystallinity of the graphite film could be improved, the amorphous defects were reduced, the thermal conductivity and mechanical properties of the graphite film were improved.

The high-thermal-conductivity graphite film prepared by the method provided by the present invention was high in graphite crystallization degree, good in flexibility, high in heat conductivity and electric-conducting properties, and high in tensile strength, and thus the high heat dissipation requirement of the existing microelectronic industry is met.

Claims

1. A method for preparing a high-thermal-conductivity graphite film, comprising the following steps: taking a graphite-phase carbon nitride and polyimide composite as a graphite film precursor, and taking graphite-phase carbon nitride as an orientation and crystallization inducer in a high-temperature carbonization and graphitization process to promote graphitization of polyimide, so as to prepare the high-thermal-conductivity graphite film.

2. The method for preparing the high-thermal-conductivity graphite film according to claim 1, wherein the method comprises the following steps: 1) sequentially adding an organic solvent, graphite-phase carbon nitride and a modifying assistant into a reaction kettle, and reacting at a high speed under a high temperature of 30°C for 2 - 12 h; 2) sequentially adding dianhydride and a diamine compound into the reaction system, and reacting at 5 - 30°C for 2 h under nitrogen gas protection to obtain a graphite-phase carbon nitride hybrid polyamic acid solution: 3) making the graphite-phase carbon nitride hybrid polyamic acid solution obtained in the step 2 uniform, carrying out casting, drying and imidization film preparation treatment on the uniform graphite-phase carbon nitride hybrid polyamic acid solution to obtain a graphite-phase carbon nitride hybrid polyimide film; and 4) carrying out carbonization and graphitization calcining on the obtained polyimide film to graphitize the polyimide carbonized film, and carrying out calendaring treatment on the graphitized polyimide carbonized film to obtain the artificial graphite film.

3. The method for preparing the high-thermal-conductivity graphite film according to claim 2, wherein the organic solvent is composed of one or more of N-methylpyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO).

4. The method for preparing the high-thermal-conductivity graphite film according to claim 2, wherein the graphite-phase carbon nitride is in a flaky shape, and the plane size is 10 - 1,000 nm.

5. The method for preparing the high-thermal-conductivity graphite film according to claim 2, wherein the modifying assistant that is an organosiloxane compound is composed of one or more of KH550, KH560, KH570 and KH590.

6. The method for preparing the high-thermal-conductivity graphite film according to claim 2, LU502863 wherein the dianhydride is composed of one or more of pyromellitic dianhydride, 3, 3’, 4, 4’- biphenyltetracarboxylic dianhydride, 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride, 2, 3, 6, 7-naphthalenetetracarboxylic dianhydride and 3, 4, 9, 10-perylenetetracarboxylic dianhydride.

7. The method for preparing the high-thermal-conductivity graphite film according to claim 2, wherein the diamine compound is composed of one or more of p-phenylenediamine, 1, 3- diaminobenzene, 4, 4-diaminodiphenyl, 1, 2-diaminobenzene, 4, 4’-diaminodiphenyl- propane, 4, 4-oxybisbenzenamine and 4, 4’-dimethoxybenzophenone.

8. The method for preparing the high-thermal-conductivity graphite film according to claim 2, wherein — the molar ratio of dianhydride to the diamine compound is 1 : (0.995 - 1.005); — the mass of graphite-phase carbon nitride is 0.1 - 0.5 wt% of the total mass of dianhydride and the diamine compound; the mass of the modifying assistant is 10 - 30 wt% of that of the graphite-phase carbon nitride (g-CsN4); and — the total solid content of the graphite-phase carbon nitride hybrid polyamic acid solution is 15 — 20 wt%.

9. A high-thermal-conductivity graphite, being prepared by the preparation method according to claim 1.