A thermal interface material and a preparation method thereof

Abstract

The present invention discloses a preparation method of a thermal interface material, which is prepared based on a column array. Specifically, the column array is placed in an assembly liquid containing two-dimensional heat-conducting elements, and the two-dimensional heat-conducting elements are assembled along the surface of the columns; the columns can release charged particles; the column array is removed, and a thermal interface material composed of vertically oriented two-dimensional heat-conducting elements is obtained. The present invention uses the column array as a template and the electrostatic force between the charged particles on the column surface and the two-dimensional heat-conducting elements as the driving force for ordered assembly, and can simply, quickly, and at low cost obtain a thermal interface material with an upright orientation structure.

Description

Technical Field

[0001] The present invention relates to new materials, and in particular to a high thermal conductivity thermal interface material and a preparation method thereof. Background Art

[0002] The high integration of high-power and high-frequency electronic devices has generated a huge demand for high-performance thermal management materials. Among them, thermal interface materials are an important part of electronic device thermal management materials. Thermal interface materials are thermal conductive materials filled between the interfaces of heat dissipation devices and heat generating devices to reduce contact thermal resistance, and are crucial for solving the heat dissipation problems of electronic devices. In particular, high-performance thermal interface materials with high out-of-plane thermal conductivity can effectively transfer heat and reduce the operating temperature of electronic devices.

[0003] At present, the research focus and difficulty of high-performance thermal interface materials lie in constructing effective vertical thermal conduction paths through innovative preparation methods. People have gradually realized that the excellent thermal conductivity of thermal interface materials mainly comes from their effective thermal conduction paths in addition to the filling amount of their thermal conductive fillers. Only by constructing effective thermal conduction paths in the vertical direction can the inherent thermal properties of thermal conductive fillers be more fully utilized.

[0004] In recent years, people have developed various ways to construct vertical thermal conduction paths, including magnetic field / electric field induced orientation, 3D printing, directional freezing, etc. By using a magnetic field or an electric field to induce two-dimensional nano-thermal conductive fillers to orient along the out-of-plane direction and maintaining for a certain time until the polymer matrix is completely cured, a thermal interface material with a vertical orientation structure can be prepared. However, this method has the problem that the fillers are difficult to be evenly distributed, and the improvement of the out-of-plane thermal conductivity is limited. The 3D printing method uses the shear force during the extrusion printing process to make two-dimensional nano-thermal conductive fillers orient along the out-of-plane direction, but this method has the problem that the filling amount is difficult to increase, which affects the further improvement of the out-of-plane thermal conductivity. The directional freezing method uses the extrusion effect of ice crystals to make two-dimensional nano-thermal conductive fillers orient along the out-of-plane direction, but the freeze-drying process requires a large amount of energy consumption, which is not conducive to large-scale preparation. Therefore, there is an urgent need to develop a new way to construct vertical thermal conduction paths to achieve controllable, large-scale, green, and low-cost preparation of high-performance thermal interface materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a thermal interface material in view of the deficiencies of the prior art.

[0006] The object of the present invention is achieved by the following technical solutions: A preparation method of a thermal interface material, which is prepared based on a column array. Specifically, the column array is placed in an assembly liquid containing two-dimensional heat-conducting elements, and the two-dimensional heat-conducting elements are assembled along the surface of the columns; the columns can release charged particles; the column array is removed, and a thermal interface material composed of vertically oriented two-dimensional heat-conducting elements is obtained; wherein, the assembly elements can form an electrostatic interaction with the charged particles. The present invention uses a column array as a template and the electrostatic force between the charged particles on the column surface and the two-dimensional heat-conducting elements as the driving force for ordered assembly, and can simply, quickly, and at low cost obtain a thermal interface material with an upright orientation structure.

[0007] It is proved by experiments that for array assembly, the volume fraction of the two-dimensional heat-conducting elements is below 20 vol%. If the content is too high, the steric hindrance between the nanosheets is relatively large, which affects the turning of the nanosheets in space and will reduce the degree of orientation.

[0008] The columns that can release charged particles can be: metal columns that in-situ release charged particles through reactions, columns that adsorb charged particles; since the assembly elements are assembled under the action of the charged particles released by the columns, those skilled in the art can foresee that the concentration of the charged particles adsorbed on the columns will affect the thickness of the orientation assembly. The higher the concentration of the charged particles, the greater the thickness of the assembly; it is proved by experiments that ordered assembly can be achieved at a concentration of 0.1 mol / L. Those skilled in the art can adjust the concentration of the charged particles adsorbed on the columns according to the thickness requirements of the product.

[0009] Those skilled in the art should know that the higher the in-plane thermal conductivity of the two-dimensional heat-conducting elements, the better the interfacial thermal conductivity of the assembled thermal interface material. In this application, a thermal interface material with better interfacial thermal conductivity can be obtained by using nanosheets with an in-plane thermal conductivity of more than 10 W / (m*K). For example, it can be at least one of boron nitride nanosheets, graphene oxide nanosheets, and alumina nanosheets.

[0010] Further, the column array is composed of columns arranged orderly or disorderly, and the distance between adjacent two columns is 0.5 - 3.0 mm. It is proved by experiments that if the distance is too large, a dense structure cannot be formed, and if the distance is too small, the volume ratio of the columns will be too high, resulting in too low a volume ratio of the assembled material.

[0011] Further, the columns are circular columns, square columns, triangular prism columns or other columns with a vertical orientation on the side.

[0012] Further, the material of the columns is selected from at least one of copper, stainless steel, titanium, aluminum, and iron.

[0013] Further, the charged particles are selected from Na + , Ca 2+, Zn 2+ , Ba 2+ , Cu 2+ , Fe 3+ , Al 3+ , Zr 4+ at least one of them.

[0014] In some preferred embodiments of the present invention, the out-of-plane thermal conductivity is further improved by filling or compressing. Specifically: the porous material obtained after removing the pillar array and drying is immersed in a prepolymer resin or a solution of polymer monomers. After vacuum treatment, it is heated and cured. Or the porous material obtained after removing the pillar array and drying is placed in a stainless steel mold and compressed from the periphery to the middle to a higher nanoflake filling amount.

[0015] In some preferred embodiments of the present invention, the assembly solution further includes a gel component, which can form a gel under the induction of the charged particles. This enables the diffusion of the charged particles to be synchronized with the gel formation. The interface of the gel is electrically charged because it contains a large number of charged particles. The interface continuously attracts nanoflakes with opposite charges to migrate towards the interface. When the nanoflakes are parallel to the gel interface, they have the largest contact area and reach the most stable state. Therefore, the nanoflakes are oriented parallel to the gel interface. When the nanoflakes contact and orient with the gel interface, as the charged particles further diffuse, the nanoflakes are fixed. The charged particles continue to diffuse forward in the direction perpendicular to the substrate to orient and fix the subsequent nanoflakes. It can be seen that when there is a gel component in the assembly solution, the thickness (diameter) of the ordered assembly can be greatly increased. Therefore, the spacing between the pillars can be increased, the porosity of the product can be reduced, thereby improving the thermal conductivity; moreover, the gel has a fixing effect on the two-dimensional heat conduction elements, which can prevent the assembled material from deforming and breaking when separating from the pillar structure.

[0016] In the present invention, the content of the gel component is based on the following premises: ① The concentration cannot be too low, otherwise, it cannot form a gel under the induction of the charged particles; ② The concentration cannot be too high, otherwise the viscosity of the assembly solution is too high, bringing orientation resistance; generally, the viscosity of the assembly solution should be below 500 mPa·s.

[0017] Furthermore, the gel component is selected from at least one of polyurethane, sodium alginate, pectin, cellulose, chitosan, and sodium polygalacturonate.

[0018] Since the gel formation rate is directly related to the release rate of charged particles on the substrate, it has been proven through experiments that when the gel formation rate is below 0.2 mm / min, the gel can ensure effective orientation induction for the assembly units. For example, for divalent calcium ions, in the adsorption case, the concentration of charged particles adsorbed on the substrate is set below 5 mol / L to ensure that the gel formation rate is below 0.2 mm / min; while for trivalent iron ions, in the adsorption case, the concentration of charged particles adsorbed on the substrate is set below 1 mol / L to ensure that the gel formation rate is below 0.2 mm / min. Those skilled in the art can adjust the concentration of adsorbed charged particles or the electrochemical reaction rate (such as the current magnitude, for metals that release charged particles in situ during the reaction) by detecting the gel formation rate to achieve the best promotion effect of the gel.

[0019] The beneficial effects of the present invention are as follows: The present invention uses a column array as a template, which is simple to operate, low in cost, and stable in effect. The prepared vertically oriented thermal interface material has fillability and compressibility, and its out-of-plane thermal conductivity can reach 3.5 W / (m·K) through further filling treatment. In particular, a highly oriented thermal interface material is prepared by combining the gel induction method, and its out-of-plane thermal conductivity reaches 6.0 W / (m·K) through further filling treatment. In the case of gel induction, through compression treatment, the out-of-plane thermal conductivity can be further increased to 37.7 W / (m·K). Description of the Drawings

[0020] Figure 1 Optical image of the substrate surface with vertically oriented circular columns.

[0021] Figure 2 Optical image of the oriented porous material prepared by the ion diffusion method without gel induction.

[0022] Figure 3 SEM image of the oriented porous material prepared by the ion diffusion method without gel induction.

[0023] Figure 4 SEM image of the highly oriented porous material prepared by the gel-induced ion diffusion method.

[0024] Figure 5 Optical image of the highly oriented porous material after hot pressing treatment.

[0025] Figure 6 SEM image of the highly oriented porous material after hot pressing treatment.

[0026] Figure 7 SEM image of the disordered oriented porous material prepared by the blending method. Detailed Embodiments

[0027] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following specifically describes in detail the specific implementation manner, structure, features and effects of the present invention in conjunction with the accompanying drawings and preferred embodiments.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "plane", "xy plane", "front and back", "left and right", "vertical direction", "normal direction", "up and down", "upward", "downward", etc. is the orientation or positional relationship, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present invention.

[0029] Since the concentration of the assembly units, the viscosity of the assembly solution, and the concentration of the charged particles in the solution adsorbed on the substrate can all be adjusted through simple tests according to requirements, in the following embodiments, unless otherwise specified, the concentration of the assembly units is measured to be within 0-20 vol%, the viscosity of the assembly solution is tested to be below 500 mPa·s, the concentration of the charged particles adsorbed on the substrate is above 1 mol / L, and the gelation speed is ensured to be below 0.2 mm / min.

[0030] Example 1:

[0031] (1) Add 27.2 g of boron nitride nanosheets and 10 g of a graphene oxide solution with a concentration of 10 mg / g to 78 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the boron nitride nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0032] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.3 mm and a pitch of 2.0 mm, and fix a copper circular column with a diameter of 0.3 mm and a height of 20 mm in the pores, as Figure 1 is the surface of the substrate with vertically oriented circular columns.

[0033] (3) Immerse the vertically oriented column structure in a 5% polyvinyl alcohol solution for 10 s and then slowly take it out, so as to form a hydrophilic coating on the surface of the column.

[0034] (4) Immerse the vertically oriented column structure with the hydrophilic coating in a 1 mol / L calcium chloride solution to obtain a vertically oriented column structure with positive charges adsorbed on the surface.

[0035] (5) Place the vertically oriented column structure with positive charges adsorbed on the surface in the boron nitride nanosheet / graphene oxide dispersion liquid, take it out after assembling for 3 min.

[0036] (6) Separate the assembled material from the column structure and place it in an oven at 60 °C for 12 h of drying to obtain a boron nitride / graphene oxide porous material with an upright orientation structure. The filling amount of boron nitride in the porous material is about 20 vol%, and its optical photograph is as shown in Figure 2 shown, and its SEM photograph is as shown in Figure 3 shown. The pores in the figure are left after removing the columns.

[0037] It can be seen from the figure that the boron nitride nanosheets are oriented along the surface of the copper columns. Through reasonable design of the column spacing, the nanosheets between two columns are vertically and evenly distributed.

[0038] (7) Immerse the dried boron nitride / graphene oxide porous material in epoxy resin, perform vacuum treatment, and then cure it by heating at 80 °C for 2 h and at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0039] Use the transient plane heat source method to test the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 3.5 W / (m·K).

[0040] Example 2:

[0041] (1) Add 27.2 g of boron nitride nanosheets, 10 g of a graphene oxide solution with a concentration of 10 mg / g, and 3.9 g of an aqueous polyurethane solution with a mass fraction of 35% to 74.1 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the boron nitride nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0042] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.3 mm and a spacing of 2.0 mm, and fix copper circular columns with a diameter of 0.3 mm and a height of 20 mm in the pores.

[0043] (3) Immerse the vertically oriented column structure in a 5% polyvinyl alcohol solution for 10 s and then slowly take it out to form a hydrophilic coating on the column surface.

[0044] (4) Immerse the vertically oriented column structure with a hydrophilic coating in a 1 mol / L zinc chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0045] (5) Place the vertically oriented column structure with positively charged surfaces adsorbed in the boron nitride nanosheet / graphene oxide nanosheet / polyurethane dispersion liquid, take it out after 3 min of assembly.

[0046] (6) Separate the assembled material from the column structure and place it in an oven at 60 °C for drying for 12 h to obtain a boron nitride-reduced graphene oxide-polyurethane porous material with an upright orientation structure. The filling amount of boron nitride in the porous material is about 20 vol%, and its SEM photograph is as shown in Figure 4 . The pores in the figure are left after removing the columns.

[0047] As can be seen from the figure, the boron nitride nanosheets are highly oriented along the surface of the copper columns.

[0048] (7) Immerse the dried boron nitride-reduced graphene oxide-polyurethane porous material in epoxy resin. After vacuum treatment, heat and cure it at 80 °C for 2 h and then at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0049] Use the transient plane heat source method to test the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 6.0 W / (m·K).

[0050] (8) Place the dried boron nitride-reduced graphene oxide-polyurethane porous material in a stainless steel mold and compress it from the periphery to the center at 80 °C to form a dense composite material. The filling amount of boron nitride in the composite material is about 65 vol%, and its optical photograph is as shown in Figure 5 . Its SEM photograph is as shown in Figure 6 .

[0051] As can be seen from the figure, the orientation degree of the boron nitride nanosheets is further improved after compression.

[0052] Use the transient plane heat source method to test the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 37.7 W / (m·K).

[0053] Example 3:

[0054] (1) Add 27.2 g of boron nitride nanosheets, 10 g of a reduced graphene oxide solution with a concentration of 10 mg / g, and 3.9 g of an aqueous polyurethane solution with a mass fraction of 35% to 74.1 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the boron nitride nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0055] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.2 mm and a pitch of 1.5 mm, and fix copper circular columns with a diameter of 0.2 mm and a height of 20 mm in the pores.

[0056] (3) Immerse the vertically oriented column structure in a 5% polyvinyl alcohol solution for 10 s and then slowly take it out to form a hydrophilic coating on the surface of the columns.

[0057] (4) Immerse the vertically oriented column structure with a hydrophilic coating into a 1 mol / L calcium chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0058] (5) Place the vertically oriented column structure with positively charged surfaces adsorbed into a boron nitride nanosheet / graphene oxide nanosheet / polyurethane dispersion liquid, take it out after assembling for 3 min.

[0059] (6) Separate the assembled material from the column structure, and place it in an oven at 60 °C and dry for 12 h to obtain a boron nitride graphene oxide polyurethane porous material with an upright orientation structure, and the filling amount of boron nitride in the porous material is about 19 vol%.

[0060] (7) Immerse the dried boron nitride graphene oxide polyurethane porous material into epoxy resin, after vacuum treatment, heat and cure at 80 °C for 2 h and heat and cure at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0061] The transient plane heat source method is used to test the thermal conductivity of the composite material, and the out-of-plane thermal conductivity at room temperature is 5.5 W / (m·K).

[0062] It can be seen from Examples 1 - 3 that the design of the column array can achieve the rapid assembly of two-dimensional heat conduction elements. When the assembly liquid only contains two-dimensional heat conduction elements, the assembled material has a good upright orientation structure. Especially after adding a gel component to the assembly liquid, the orientation degree of the assembled material is further improved. In addition, materials with excellent thermal conductivity can be assembled using different array parameters.

[0063] Example 4:

[0064] (1) Add 27.2 g of boron nitride nanosheets and 3.9 g of an aqueous polyurethane solution with a mass fraction of 35% to 84.1 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the boron nitride nanosheets is 12 vol%, and the viscosity of the assembly liquid is below 500 mPa·s.

[0065] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.3 mm and a spacing of 2.0 mm, and assemble copper circular columns with a diameter of 0.3 mm and a height of 20 mm in the pores.

[0066] (3) Immerse the vertically oriented column structure into a 5% polyvinyl alcohol solution for 10 s and then slowly take it out to form a hydrophilic coating on the surface of the column.

[0067] (4) Immerse the vertically oriented column structure with a hydrophilic coating into a 5 mol / L calcium chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0068] (5) Place the vertically oriented column structure with positively charged surfaces adsorbed in the boron nitride nanosheet / polyurethane dispersion, take it out after assembling for 2 min.

[0069] (6) Separate the assembled material from the column structure, and place it in an oven at 60 °C and dry for 12 h to obtain a boron nitride polyurethane porous material with an upright orientation structure. The filling amount of boron nitride in the porous material is about 20 vol%.

[0070] (7) Immerse the dried boron nitride polyurethane porous material in epoxy resin, after vacuum treatment, cure it by heating at 80 °C for 2 h and at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0071] The transient plane heat source method was used to test the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 5.7 W / (m·K).

[0072] Example 5:

[0073] (1) Add 27.2 g of boron nitride nanosheets and 5.4 g of a 5% sodium alginate solution by mass to 82.6 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of boron nitride nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0074] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.3 mm and a pitch of 2.0 mm, and fix a copper circular column with a diameter of 0.3 mm and a height of 20 mm in the pores.

[0075] (3) Immerse the vertically oriented column structure in a 5% polyvinyl alcohol solution by mass for 10 s and then slowly take it out to form a hydrophilic coating on the surface of the column.

[0076] (4) Immerse the vertically oriented column structure with a hydrophilic coating in a 5 mol / L calcium chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0077] (5) Place the vertically oriented column structure with positively charged surfaces adsorbed in the boron nitride nanosheet / sodium alginate dispersion, take it out after assembling for 5 min.

[0078] (6) Separate the assembled material from the column structure, and place it in an oven at 60 °C and dry for 2 h to obtain a boron nitride sodium alginate porous material with an upright orientation structure. The filling amount of boron nitride in the composite material is about 19 vol%.

[0079] (7) Immerse the dried boron nitride sodium alginate porous material in epoxy resin, after vacuum treatment, cure it by heating at 80 °C for 2 h and at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0080] The transient plane heat source method is used to measure the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 5.2 W / (m·K).

[0081] Example 6:

[0082] (1) Add 43.2 g of alumina nanosheets and 6.2 g of a 35% aqueous polyurethane solution to 81.8 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the alumina nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0083] (2) Use 3D printing technology to prepare a porous array substrate with a pore diameter of 0.3 mm and a pitch of 2.0 mm, and fix a copper circular column with a diameter of 0.3 mm and a height of 20 mm in the pores.

[0084] (3) Immerse the vertically oriented column structure in a 5% polyvinyl alcohol solution for 5 s and then slowly take it out, so as to form a hydrophilic coating on the surface of the column.

[0085] (4) Immerse the vertically oriented column structure with the hydrophilic coating in a 3 mol / L calcium chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0086] (5) Place the vertically oriented column structure with positively charged surfaces adsorbed in the alumina nanosheet / polyurethane dispersion, take it out after assembling for 1 min.

[0087] (6) Separate the assembled material from the column structure and place it in an oven at 60 °C for drying for 2 h to obtain an alumina polyurethane porous material with an upright orientation structure. The filling amount of alumina in the porous material is about 25 vol%.

[0088] (7) Immerse the dried alumina polyurethane porous material in epoxy resin, after vacuum treatment, heat and cure at 80 °C for 2 h and at 120 °C for 2 h to obtain a composite material with an upright orientation structure.

[0089] The transient plane heat source method is used to measure the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature is 2.0 W / (m·K).

[0090] Comparative Example 1:

[0091] (1) Add 27.2 g of boron nitride nanosheets and 10 g of a graphene oxide solution with a concentration of 10 mg / g to 78 mL of water, stir evenly, and ultrasonically disperse for 1 h. The volume fraction of the boron nitride nanosheets is 12 vol%, and the viscosity of the assembly solution is below 500 mPa·s.

[0092] (2) 5 mol / L calcium chloride solution was directly dropped into the assembled solution of boron nitride and graphene oxide, and after 5 minutes of assembly, it was taken out.

[0093] (3) The assembled material was placed in an oven at 60 °C and dried for 12 h to obtain a porous material of boron nitride and graphene oxide with a disordered orientation structure. The filling amount of boron nitride in the porous material was about 16 vol%, and its SEM photograph is as Figure 7 shown.

[0094] (4) The dried porous material of boron nitride and graphene oxide was immersed in epoxy resin. After vacuum treatment, it was heated and cured at 80 °C for 2 h and then at 120 °C for 2 h to obtain a composite material with a disordered orientation structure.

[0095] The transient plane heat source method was used to measure the thermal conductivity of the composite material. The out-of-plane thermal conductivity at room temperature was 1.3 W / (m·K).

[0096] Comparative Example 2:

[0097] (1) 27.2 g of boron nitride nanosheets were added to 88.0 mL of water, stirred evenly, and ultrasonically dispersed for 1 h. The volume fraction of boron nitride nanosheets was 12 vol%.

[0098] (2) A porous array substrate with a pore diameter of 0.3 mm and a spacing of 2.0 mm was prepared by 3D printing technology, and copper circular columns with a diameter of 0.3 mm and a height of 20 mm were fixed in the pores.

[0099] (3) The vertically oriented column structure was immersed in a 5% polyvinyl alcohol solution for 10 s and then slowly taken out, so as to form a hydrophilic coating on the surface of the column.

[0100] (4) The vertically oriented column structure with a hydrophilic coating was immersed in a 5 mol / L calcium chloride solution to obtain a vertically oriented column structure with positively charged surfaces adsorbed.

[0101] (5) The vertically oriented column structure with positively charged surfaces adsorbed was placed in the boron nitride nanosheet dispersion. Since there was almost no electrostatic interaction between the boron nitride nanosheets and the charged particles, it was taken out after 2 minutes of assembly. Only a boron nitride nanosheet layer with a thickness of about 100 μm was assembled on the surface of the column. The thickness did not increase after extending the assembly time, resulting in the space between the columns not being filled, so that a thermal interface material could not be assembled.

[0102] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a thermal interface material, characterized in that, It is prepared based on a column array. The column array is placed in an assembly liquid containing two-dimensional heat conduction elements, and the two-dimensional heat conduction elements are assembled along the surface of the columns; the columns can release charged particles; After removing the column array, a thermal interface material composed of vertically oriented two-dimensional heat conduction elements is obtained; wherein, the two-dimensional heat conduction elements can form an electrostatic interaction with the charged particles; The charged particles are selected from at least one of Na + , Ca 2+ , Zn 2+ , Ba 2+ , Cu 2+ , Fe 3+ , Al 3+ , Zr 4+ ; The assembly liquid further includes a gel component, and the gel component can form a gel under the induction of the charged particles; the gel component is selected from at least one of polyurethane, sodium alginate, pectin, and sodium polygalacturonate.

2. The preparation method according to claim 1, characterized in that, The two-dimensional heat conduction element is a nanosheet with an in-plane thermal conductivity of more than 10 W / (m*K).

3. The preparation method according to claim 1, characterized in that, The two-dimensional heat conduction element is at least one of boron nitride nanosheets, graphene oxide nanosheets, and alumina nanosheets.

4. The preparation method according to claim 1, characterized in that, The column array is composed of columns arranged orderly or disorderly, and the distance between adjacent two columns is 0.5 - 3.0 mm.

5. The preparation method according to claim 1, characterized in that, The columns are circular columns, square columns, triangular prism columns, or other columns with a vertical orientation on the side surface.

6. The preparation method according to claim 1, characterized in that, The material of the columns is selected from at least one of copper, stainless steel, titanium, aluminum, and iron.

7. The preparation method according to claim 1, characterized in that, It further includes resin filling the thermal interface material obtained after removing the column array to obtain a composite material composed of two-dimensional heat conduction elements and resin.

8. The preparation method according to claim 1, characterized in that, It further includes compressing the thermal interface material obtained after removing the column array to obtain a thermal interface material composed of high-density two-dimensional heat conduction elements.

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