CN110804269A - A liquid metal-based thermally conductive and conductive film and its preparation method and application - Google Patents

Abstract

The invention provides a liquid metal-based thermally conductive film, a preparation method and application thereof. The method comprises: mixing a thermally conductive filler and dopamine, and generating polydopamine on the surface of the thermally conductive filler to obtain a modified thermally conductive filler; The modified thermally conductive filler, liquid metal and polyvinyl alcohol aqueous solution are mixed to obtain a mixed solution; the mixed solution is poured into a mold, and after water volatilization, a thermally conductive and conductive film with the upper layer of the thermally conductive filler and the lower layer of liquid metal is obtained. The film prepared by the preparation method provided by the invention has both high thermal conductivity and electrical conductivity. In the liquid metal enrichment layer, the polyvinyl alcohol wrapped on the surface of the liquid metal can be scraped to expose the liquid metal to form a conductive circuit , can be connected to electronic devices, the heat generated by the electronic devices during the operation can be quickly dissipated through the layer enriched by the thermal conductive filler, and the heat dissipation effect is good.

Description

A liquid metal-based thermally conductive and conductive film and its preparation method and application

technical field

The invention relates to the technical field of polymer materials, in particular to a liquid metal-based thermally conductive and conductive film, a preparation method and application thereof.

Background technique

With the development of electronic components towards high power, high energy density, and miniaturization, the heat generated per unit area of electronic components is getting higher and higher, while the effective heat dissipation area is getting smaller and smaller. The problem of heat dissipation has become an important factor restricting the development of high-power electronic equipment, large-scale integrated circuits, and flexible electronic devices. Therefore, the development of a heat-dissipating material with high thermal conductivity is an important problem that needs to be solved urgently in the field of electronic components and materials.

At present, the commonly used heat dissipation technology is to realize heat dissipation by adding thermal conductive pads or gels to electronic devices. This method usually has the disadvantages of low heat dissipation efficiency and insufficient heat dissipation area.

Therefore, the existing technology still needs to be improved and developed.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a liquid metal-based thermally conductive and conductive film, a preparation method and application thereof, and to solve the problem of low heat dissipation efficiency of the existing thermally conductive and conductive film.

The technical scheme adopted by the present invention for solving the above-mentioned technical problems is as follows:

A preparation method of a liquid metal-based thermal conductive film, wherein the method comprises:

S100, mixing the thermally conductive filler and dopamine to generate polydopamine on the surface of the thermally conductive filler to obtain a modified thermally conductive filler;

S200, mixing the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution to obtain a mixed solution;

S300, pouring the mixed solution into a mold, and after the water volatilizes, a thermally conductive/conductive film whose upper layer is a thermally conductive filler and a lower layer is liquid metal is obtained.

The preparation method of the liquid metal-based thermally conductive and conductive film, wherein, in the step of mixing the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution, the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol are mixed. The mass ratio is 5:1-10:1-10.

In the preparation method of the liquid metal-based thermal conductive film, the thermal conductive filler is one or more of hexagonal boron nitride, graphene and graphene oxide.

In the preparation method of the liquid metal-based high thermal conductivity conductive film, the liquid metal is one or more of pure gallium, mercury, bismuth and alloys thereof.

In the preparation method of the liquid metal-based thermal and conductive film, the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 5-15%.

The preparation method of the liquid metal-based thermally conductive and conductive film, wherein, in the step, a thermally conductive filler and dopamine are mixed, and polydopamine is generated on the surface of the thermally conductive filler to obtain a modified thermally conductive filler, comprising:

The thermally conductive filler and dopamine are mixed in deionized water, reacted under predetermined conditions, centrifuged after the reaction is completed, and the precipitate is washed with ionized water and absolute ethanol, respectively, and the modified thermally conductive filler is obtained after the precipitate is vacuum-dried.

The preparation method of the liquid metal-based thermal conductive film, wherein the thermal conductive filler and dopamine are mixed in deionized water, a buffer is added to adjust the pH to 8-9, and the reaction is carried out at a temperature of 25° C. for 20-30 hours.

The preparation method of the liquid metal-based thermally conductive and electrically conductive film, wherein the step is to mix the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution, including:

The modified thermally conductive filler, liquid metal and polyvinyl alcohol aqueous solution are mixed, and placed in a cell crusher for 50-70 minutes to obtain a mixed solution.

A thermally conductive and electrically conductive film, wherein the above-mentioned preparation method is used.

An application of a thermally conductive and conductive film, wherein the liquid metal-enriched side of the above-mentioned conductive and thermally conductive film is scraped to obtain a conductive circuit, which is applied to the preparation of electronic devices.

Beneficial effects: In the present invention, by adding liquid metal as a conductive material, the thermally conductive filler is modified by dopamine to improve the hydrophilicity of the thermally conductive filler, so that it can be dispersed in the mixed solution. The liquid metal settles during the film-forming process, and the lower layer is enriched with liquid metal droplets, and the upper layer is enriched with thermally conductive fillers. The prepared film has both high thermal conductivity and electrical conductivity. By scraping the polyvinyl alcohol wrapped on the surface of the liquid metal, the liquid metal can be exposed to form a conductive circuit, which can be connected to electronic devices. The heat generated by the electronic devices during operation can pass through the layer of thermal conductive fillers The heat is quickly dissipated, and the heat dissipation effect is good.

Description of drawings

FIG. 1 is a flow chart of a method for preparing a liquid metal-based thermally conductive and conductive film provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer and clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Please refer to FIG. 1. FIG. 1 is a flowchart of a preferred embodiment of a method for preparing a liquid metal-based thermally conductive film provided by the present invention. As shown in the figure, it includes the following steps:

S100, mixing the thermally conductive filler and dopamine to generate polydopamine on the surface of the thermally conductive filler to obtain a modified thermally conductive filler;

S200, mixing the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution to obtain a mixed solution;

S300 , pouring the mixed solution into a mold, and after the water volatilizes, a thermally conductive and conductive film whose upper layer is a thermally conductive filler and the lower layer is a liquid metal is obtained.

In this example, the thermally conductive filler is mixed with dopamine first, and the dopamine undergoes a polymerization reaction in the system to form polydopamine, which is deposited on the surface of the thermally conductive filler to form a polydopamine-modified thermally conductive filler. The hydrophilic hydroxyl group improves the hydrophilicity of the thermally conductive filler. The modified thermal conductive filler, liquid metal and polyvinyl alcohol aqueous solution are mixed, poured into the mold and left to stand. During the standing process, the water volatilizes, and the liquid metal droplets settle down and accumulate in the lower part of the film, and have good hydrophilic properties. The thermally conductive filler can be well dispersed in the system and enriched in the upper part of the film, so after the water is completely volatilized, a double-layer film structure and a film material with high thermal conductivity and electrical conductivity are formed.

The film exposes the liquid metal by scraping the polyvinyl alcohol wrapped on the liquid metal enrichment layer to form a conductive circuit. The conductive circuit can be used for the packaging of electronic devices, and a large amount of heat generated during the operation of the device can be enriched by the thermal conductive filler The heat-conducting surface of the aggregate layer is dispersed in time to achieve efficient heat dissipation. In addition, the film has thermal conductivity and electrical conductivity at the same time, and no additional heat dissipation device is required, which satisfies the development trend of miniaturization of existing electronic devices.

In some embodiments, the mass ratio of the modified thermally conductive filler, liquid metal and polyvinyl alcohol is 5:1-10:1-10. The thermally conductive and conductive films prepared within this range have better electrical and thermal conductivity.

In some embodiments, the thermally conductive filler is one or more of hexagonal boron nitride, graphene and graphene oxide. In this embodiment, the thermally conductive filler is a two-dimensional thermally conductive material. During the film-forming process, the volatilization of water will induce the orientation of the two-dimensional filler, thereby achieving the effect of increasing thermal conductivity.

In some embodiments, the liquid metal is one or more of pure gallium, mercury, bismuth, and alloys thereof. In this embodiment, the liquid metal is one or more of low melting point metals or alloys thereof.

In some embodiments, the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 5-15%. In this embodiment, the polyvinyl alcohol is a base support material in the present invention. After the water in the mixed solution is volatilized to form a film, the polyvinyl alcohol will be wrapped on the surface of the liquid metal enrichment layer. Both sides forming the film are insulating, with polyvinyl alcohol on one side and a thermally conductive filler enrichment layer on the other side. By scraping the polyvinyl alcohol on the surface, the liquid metal enrichment layer can be exposed, and the exposed liquid metal route has conductive properties, and different conductive routes can be drawn according to different circuit designs. In some embodiments, the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 10%.

In some embodiments, the step S100 includes:

The thermally conductive filler and dopamine are mixed in deionized water, reacted under predetermined conditions, centrifuged after the reaction is completed, and the precipitate is washed with ionized water and absolute ethanol, respectively, and the modified thermally conductive filler is obtained after the precipitate is vacuum-dried.

In some embodiments, the thermally conductive filler and dopamine are mixed in deionized water, a buffer is added to adjust the pH to 8-9, and the reaction is carried out at a temperature of 25° C. for 20-30 hours. Dopamine polymerizes in a weak alkaline environment to form polydopamine, which is deposited on the surface of the thermally conductive filler, and a lot of hydrophilic hydroxyl groups are enriched on the surface of the filler to modify the thermally conductive filler and improve the hydrophilicity of the thermally conductive filler , so that the thermal conductive filler can be better dispersed in the mixed solution, so that the thermal conductive filler on the formed film is evenly distributed, and the heat dissipation effect of the film is better. In some embodiments, the pH is 8.5. In some embodiments, the buffer is tris.

In some embodiments, the step S200 includes:

The modified thermally conductive filler, liquid metal and polyvinyl alcohol aqueous solution are mixed, and placed in a cell crusher for 50-70 minutes to obtain a mixed solution. In this embodiment, the cell crusher is sonicated for 50-70 minutes, so that the base material and the functional filler can be fully mixed, and the polyvinyl alcohol is wrapped on the outside of the liquid metal. In some embodiments, the cell disintegrator is sonicated for 60 min.

The present invention also provides a thermally conductive and electrically conductive film, which is prepared by the above-mentioned preparation method.

The liquid metal-enriched side of the above thermally conductive and conductive film can be scratched, and different conductive lines can be drawn, which can be applied to electronic devices. The heat dissipation efficiency of electronic devices is improved. Moreover, the thermally conductive and conductive film provided by the present invention has both electrical and thermal conductivity properties, does not require additional heat dissipation materials, greatly reduces the thickness of electronic devices, and is especially suitable for the preparation of flexible electronic devices.

In the preparation method provided by the invention, no organic solvent is used, which conforms to the principle of green environmental protection and greatly reduces the pollution to the environment during the preparation process.

The present invention will be described in detail below through specific embodiments.

Example 1

1 g of BN and 0.5 g of dopamine were weighed into a beaker containing 150 ml of deionized water, the pH of the solution was adjusted to 8.5 with tris, and the reaction was carried out under magnetic stirring for 24 h at 25 °C. After the reaction, the centrifugation method was used to wash three times with deionized water, then three times with absolute ethanol, and finally dry the centrifuged product in a vacuum oven at 60 °C for 24 h to obtain polydopamine-modified boron nitride (BN@ PDA).

20 g of polyvinyl alcohol was made into a 10% aqueous solution, then 5 g of polyvinyl alcohol aqueous solution was taken into a 30-ml glass bottle, 0.1 g of BN@PDA and 0.1 g of gallium indium tin liquid metal were added, and ultrasonically dispersed for 60 min using a cell crusher to obtain The mixed liquid is then poured into a mold, and the water is evaporated in an air atmosphere at room temperature to obtain a Janus composite film.

Conductive lines can be drawn on the liquid metal enriched layer of the prepared Janus thin film by scratching.

Example 2

1 g of BN and 0.5 g of dopamine were weighed into a beaker containing 150 ml of deionized water, the pH of the solution was adjusted to 8.5 with tris, and the reaction was carried out under magnetic stirring for 24 h at 25 °C. After the reaction, the centrifugation method was used to wash three times with deionized water, then three times with absolute ethanol, and finally dry the centrifuged product in a vacuum oven at 60 °C for 24 h to obtain polydopamine-modified boron nitride (BN@ PDA).

20 g of polyvinyl alcohol was made into a 10% aqueous solution, and then 5 g of polyvinyl alcohol aqueous solution was taken into a 30-ml glass bottle, 0.3 g of BN@PDA and 0.5 g of gallium indium tin liquid metal were added, and ultrasonically dispersed for 60 min using a cell crusher to obtain The mixed liquid is then poured into a mold, and the water is evaporated in an air atmosphere at room temperature to obtain a Janus composite film.

Conductive lines can be drawn on the liquid metal enriched layer of the prepared Janus thin film by scratching.

Example 3

1 g of BN and 0.5 g of dopamine were weighed into a beaker containing 150 ml of deionized water, the pH of the solution was adjusted to 8.5 with tris, and the reaction was carried out under magnetic stirring for 24 h at 25 °C. After the reaction, the centrifugation method was used to wash three times with deionized water, then three times with absolute ethanol, and finally dry the centrifuged product in a vacuum oven at 60 °C for 24 h to obtain polydopamine-modified boron nitride (BN@ PDA).

20 g of polyvinyl alcohol was made into a 10% aqueous solution, and then 5 g of polyvinyl alcohol aqueous solution was taken into a 30-ml glass bottle, 0.7 g of BN@PDA and 1 g of gallium indium tin liquid metal were added, and ultrasonically dispersed using a cell crusher for 60 min to obtain a mixed solution. The liquid is then poured into a mold, and the water is evaporated in an air atmosphere at room temperature to obtain a Janus composite film.

Conductive lines can be drawn on the liquid metal enriched layer of the prepared Janus thin film by scratching.

Example 4

1 g of graphene and 0.5 g of dopamine were weighed into a beaker containing 150 ml of deionized water, the pH of the solution was adjusted to 8.5 with tris, and the reaction was performed under magnetic stirring for 24 h at 25 °C. After the reaction, the centrifugation method was used to wash three times with deionized water, then three times with anhydrous ethanol, and finally dry the centrifuged product in a vacuum oven at 60 °C for 24 h to obtain polydopamine-modified graphene (GNPs@PDA). ).

20 g of polyvinyl alcohol was made into a 10% aqueous solution, and then 5 g of polyvinyl alcohol aqueous solution was taken into a 30-ml glass bottle, 0.3 g of GNPs@PDA and 1 g of gallium indium tin liquid metal were added, and ultrasonically dispersed for 60 min using a cell crusher to obtain a mixed solution. The liquid is then poured into a mold, and the water is evaporated in an air atmosphere at room temperature to obtain a Janus composite film.

Conductive lines can be drawn on the liquid metal enriched layer of the prepared Janus thin film by scratching.

Performance Testing

The thermal conductivity and the electrical circuit resistance of the thermally conductive and electrically conductive films prepared in the above-mentioned embodiments 1, 2, 3, and 4 were tested, and the obtained test results were as follows:

Example Thermal conductivity (W/mK) Conductive Line Resistance (Ω) Example 1 2.32 920 Example 2 4.25 530 Example 3 8.39 92 Example 4 11.6 85

To sum up, the present invention provides a liquid metal-based thermally conductive film and a preparation method and application thereof. By using polyvinyl alcohol as a base support material, liquid metal and thermally conductive fillers are used as functional fillers for electrical and thermal conductivity, respectively, and thermally conductive fillers. After modification with polydopamine, the hydrophilicity is improved, which is beneficial to the uniform dispersion of the thermally conductive filler in the mixed solution. During the process of water volatilization and film formation, the liquid metal settles to the lower layer to form a liquid metal droplet enrichment layer, while the upper layer is a thermally conductive filler enrichment layer, thus forming a film with both high thermal conductivity and electrical conductivity, and the liquid metal enrichment layer The surface is wrapped with polyvinyl alcohol, so the film is insulated on both sides at the beginning. By scraping the polyvinyl alcohol on the surface, the liquid metal enrichment layer is exposed, which can form conductive lines and connect to electronic devices. The electronic devices are in the operation process. The heat generated in the heat-conducting filler can quickly dissipate the heat through the enriched layer of the thermally conductive filler, and the heat dissipation effect is good.

It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. a preparation method of a liquid metal-based thermally conductive film, characterized in that the method comprises: Mixing the thermally conductive filler and dopamine to generate polydopamine on the surface of the thermally conductive filler to obtain a modified thermally conductive filler; mixing the modified thermally conductive filler, liquid metal and polyvinyl alcohol aqueous solution to obtain a mixed solution; The mixed solution is poured into the mold, and after the water is volatilized, a thermally conductive and conductive film whose upper layer is a thermally conductive filler and a lower layer is liquid metal is obtained. 2. The method for preparing a liquid metal-based thermally conductive film according to claim 1, wherein in the step of mixing the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution, the modified thermally conductive filler , the mass ratio of liquid metal and polyvinyl alcohol is 5:1-10:1-10. 3. The preparation method of the liquid metal-based thermally conductive film according to claim 1, wherein the thermally conductive filler is one or more of hexagonal boron nitride, graphene and graphene oxide. 4 . The method for preparing a liquid metal-based high thermal conductivity and conductive film according to claim 1 , wherein the liquid metal is one or more of pure gallium, mercury, bismuth and alloys thereof. 5 . 5 . The method for preparing a liquid metal-based thermal and conductive film according to claim 1 , wherein the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 5-15%. 6 . 6. The preparation method of the liquid metal-based thermally conductive film according to claim 1, characterized in that, in the step, a thermally conductive filler and dopamine are mixed, and polydopamine is generated on the surface of the thermally conductive filler to obtain a modified thermally conductive filler, include: The thermally conductive filler and dopamine are mixed in deionized water, reacted under predetermined conditions, centrifuged after the reaction is completed, and the precipitate is washed with ionized water and absolute ethanol, respectively, and the modified thermally conductive filler is obtained after the precipitate is vacuum-dried. 7. The method for preparing a liquid metal-based thermally conductive and conductive film according to claim 6, wherein the thermally conductive filler and dopamine are mixed in deionized water, a buffer is added to adjust the pH to 8-9, and the temperature is 25°C. The next reaction is 20-30h. 8. The method for preparing a liquid metal-based thermally conductive film according to claim 1, wherein the step is to mix the modified thermally conductive filler, the liquid metal and the polyvinyl alcohol aqueous solution, comprising: The modified thermally conductive filler, liquid metal and polyvinyl alcohol aqueous solution are mixed, and placed in a cell crusher for 50-70 minutes to obtain a mixed solution. 9. A thermally conductive and electrically conductive film, characterized in that, it is formed by the preparation method according to claims 1-8. 10. An application of a thermally conductive film, wherein the liquid metal-enriched side of the conductive and thermally conductive film according to claim 9 is scraped to obtain a conductive circuit, which is applied to the preparation of electronic devices.

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