CN113214583B - Thermal interface material with vertical sandwich structure and preparation method thereof - Google Patents
Thermal interface material with vertical sandwich structure and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a thermal interface material with a vertical sandwich structure and a preparation method thereof. In the polymer composite film with the vertical sandwich structure prepared by the method, the heat-conducting fillers are distributed in the film matrix in an oriented manner, namely the upper surface and the lower surface are arranged in parallel, the middle part is vertically arranged, a heat-conducting passage can be formed in the in-plane direction and the out-of-plane direction, and the in-plane and out-of-plane heat conductivity is effectively improved. The invention comprises the following steps: a polymer gel mixed solution containing a heat-conducting filler is prepared and dropped onto a flat substrate. And (3) forming a film by using an ice rolling gel solution containing calcium ions, freezing, and drying the frozen gel film at normal pressure to obtain the composite film with the vertical sandwich structure. The thermal interface material prepared by the invention has bidirectional high thermal conductivity and excellent mechanical property, can effectively improve the heat dispersion performance, does not need to use complex and expensive processing equipment and severe processing conditions, and is beneficial to large-scale production.
Description
Technical Field
The invention relates to a thermal interface material with a vertical sandwich structure and a preparation method thereof, belonging to the technical field of heat-conducting composite materials.
Background
In recent years, along with the development of microelectronic devices toward miniaturization, light weight, high density and high integration, heat generated during operation is difficult to dissipate rapidly, the service life of the electronic device is greatly shortened, the use safety is reduced, and the performance is greatly influenced. Heat dissipation is critical to the lifetime, safety and performance of electronic devices, and therefore the search for developing new heat dissipation materials for thermal management of high power density electronic devices has become a hotspot in research in the fields of electronic information and new materials. Thermal Interface Material (TIM) is a material used for heat dissipation and packaging of integrated circuits, and is mainly used for filling up microscopic voids and holes with uneven surfaces generated when two materials are joined or contacted, and rapidly conducting and diffusing excess heat generated by electronic components to the surrounding environment or a cooling system. To maximize heat transfer efficiency, TIMs are required not only to have high thermal conductivity, but also to be easily compressible and to be able to flexibly fill gaps. Polymer-based composites are widely used as TIMs due to their good mechanical flexibility, but because polymers are mostly amorphous structures, intrinsic thermal conductivity is low. To meet the requirement of TIM thermal conductivity, it is often necessary to add fillers with higher thermal conductivity, such as carbon materials, metallic materials, and ceramic materials, to the polymer. In order to improve the thermal conductivity of the composite material, the fillers are reasonably oriented and arranged, and a heat conducting network is constructed in a matrix, so that an effective means is provided.
Disclosure of Invention
The invention aims to provide a thermal interface material with a vertical sandwich structure and a preparation method thereof. The composite material has reasonable orientation arrangement of the filler, can form an effective heat conducting network at a lower content, has excellent heat conducting performance in the in-plane and out-of-plane directions, and also has flexible performance, thereby laying a foundation for the application of the composite material in the heat dissipation of electronic elements. The method is easy to process, and does not need complex and expensive equipment and preparation process, thereby having good theoretical research and practical application values.
The thermal interface material with the vertical sandwich structure comprises a heat-conducting filler and a polymer material with flexibility, wherein the mass percentage of the heat-conducting filler to the polymer material is 2.5% -25%.
In the present invention, the thermal interface material has a film thickness of 100 to 400 μm.
In the invention, the cross section structure of the thermal interface material is that the upper surface and the lower surface are parallel structures, and a vertical orientation structure is embedded between the parallel structures.
In the invention, the orientation structure of the heat conducting filler of the thermal interface material is that the upper surface and the lower surface are oriented in parallel, and the middle part is oriented vertically.
In the invention, the polymer material with the flexible property is a water-soluble polymer and comprises at least one of polyvinyl alcohol, waterborne polyurethane or waterborne polyacrylate.
In the present invention, the thermally conductive filler includes at least one of graphene, hexagonal boron nitride, graphite flake, MXene, or carbon nanotube.
The invention provides a preparation method of a thermal interface material with a vertical sandwich structure, which comprises the following specific steps:
(1) weighing 10mL of deionized water, adding 0.15-0.3 g of sodium alginate and 0.1-1.2 g of water-soluble polymer, fully stirring and mixing under corresponding dissolving conditions, adding 0.01-0.2 g of heat-conducting filler, and stirring to obtain a mixed gel solution;
(2) dripping the mixed gel solution obtained in the step (1) on a flat base material, placing ice containing calcium ions on the gel, calendering to form a film, freezing, and removing the calcium ion ice to obtain a frozen gel film;
(3) sequentially soaking the frozen film obtained in the step (2) in ethanol and acetone; drying under normal pressure to obtain the thermal interface material with a vertical sandwich structure.
In the invention, the ice containing calcium ions in the step (2) is frozen by a calcium chloride solution.
The thermal interface material prepared by the invention has the beneficial effects that:
(1) according to the invention, as the heat-conducting fillers in the composite film are reasonably oriented and arranged into a vertical sandwich structure, a heat-conducting passage can be formed in the in-plane direction and the out-of-plane direction, and the heat-conducting property is very excellent;
(2) in the invention, the composite material is compounded with a flexible polymer material, so that the composite material has good flexibility;
(3) according to the invention, the preparation process of the composite film is simple, the environment is not polluted, the raw material and production cost are low, and the large-scale preparation is facilitated;
(4) in the invention, the composite film shows excellent heat dissipation effect when the CPU runs in full load.
Drawings
FIG. 1 is a photograph of the appearance of the thermal interface material having the vertical sandwich structure of example 1 and a SEM photograph. Wherein (a) is a macroscopic picture of the thermal interface material with the vertical sandwich structure, the scale bar is 2cm, and (b) is a scanning electron microscope picture of the thermal interface material with the vertical sandwich structure;
FIG. 2 is a photograph of Micro-CT of the thermal interface material with a vertical sandwich structure of example 1. Wherein (a) is a photograph of a thin film having a vertical sandwich structure, and (b) is a photograph of a cross-section of a thermal interface material having a vertical sandwich structure;
FIG. 3 shows the in-plane and out-of-plane thermal conductivities of the thermal interface material with a vertical sandwich structure of example 1;
FIG. 4 is a thermal expansion curve of the thermal interface material with a vertical sandwich structure of example 1;
FIG. 5 is a graph showing the resistivity of the thermal interface material with a vertical sandwich structure of example 1;
FIG. 6 is an infrared image of the thermal interface material with a vertical sandwich structure of example 1. Wherein: (a) and (c) is an infrared image of the sample before heating, (b) and (d) are infrared images of the sample after heating on a 90 ℃ hot stage for 90 s;
FIG. 7 is a graph showing the temperature change of the CPU core when the thermal interface material with the vertical sandwich structure of example 1 is used for heat dissipation;
FIG. 8 is a SEM of a thermal interface material with a vertical sandwich structure of example 2;
FIG. 9 is a graph of the in-plane and out-of-plane thermal conductivities of the thermal interface materials with the vertical sandwich structure of example 2.
Detailed Description
The present invention will be further described with reference to the following specific examples and drawings, but the present invention is not limited to the following examples. The method is a conventional method unless otherwise specified. The starting materials are commercially available from the open literature unless otherwise specified.
Example 1:
firstly, dispersing 5g of commercial hexagonal Boron Nitride (BN) powder in 500ml of mixed solution of isopropanol and water (volume ratio is 1: 1) for over 12 hours by ultrasonic treatment, centrifuging at 3000rpm for 10min to obtain supernatant, continuing to centrifuge at 15000rpm for 10min, collecting precipitate, and freeze-drying for later use. Dispersing 0.2g of sodium alginate and 0.18g of polyvinyl alcohol in 10mL of deionized water, stirring and dissolving for 30min at 90 ℃, cooling to room temperature, stirring for more than 24h, adding 0.07g of freeze-dried powder, and stirring for more than half an hour for full mixing;
secondly, the mixed gel solution obtained is dripped on a flat substrate, and ice (3 wt% CaCl) containing calcium ions is added2) The gel solution was rolled for 10min to form a film and frozen. Removing the ice blocks, sequentially soaking the frozen gel film in ethanol and acetone for 1h, and drying at 60 ℃ under normal pressure to obtain the polymer/BN composite film with the vertical sandwich structure;
as shown in figure 1, the prepared polymer/BN composite film has a white appearance, is not obviously damaged after being folded, has a vertical sandwich structure in the cross section, and is embedded in a layered structure which is parallel from top to bottom;
FIG. 2 shows a photograph of the distribution of BN filler in the polymer/BN composite film, which shows that vertically arranged BN is embedded in BN arranged in parallel on the upper and lower surfaces to form a vertical sandwich structure;
FIG. 3 shows the thermal conductivity of pure polymer films and polymer/BN composite films, and the vertical sandwich structure forms thermal conduction paths in two directions, namely in-plane and out-of-plane, so that the thermal conductivity is improved;
as shown in fig. 4, compared with the pure polymer film, the polymer/BN composite film has small thermal expansion and good shape stability;
FIG. 5 shows the resistivity of the polymer/BN composite film, which can be seen to have excellent electrical insulation properties;
fig. 6 (a) and fig. 6 (b) compare the thermal images of the pure polymer, fig. 6 (c) and fig. 6 (d) of the polymer/BN composite film, and it can be seen that the surface temperature of the polymer/BN composite film is significantly higher than that of the pure polymer;
fig. 7 shows the core temperature curve of the CPU when the polymer/BN composite film with the vertical sandwich structure is used for heat dissipation, and it can be seen that the core temperature of the CPU in full load operation can be reduced by 27 ℃ after the polymer/BN composite film with the vertical sandwich structure is used.
Example 2:
dispersing 0.2g of sodium alginate and 0.6g of polyvinyl alcohol in 10mL of deionized water, stirring and dissolving for 1h at 90 ℃, cooling to room temperature, stirring for more than 24h, adding 0.04g of graphene, and stirring for more than half an hour for full mixing;
secondly, the mixed gel solution obtained is dripped on a flat substrate, and ice (3 wt% CaCl) containing calcium ions is added2) The gel solution was rolled for 10min to form a film and frozen. Removing the ice blocks, sequentially soaking the frozen gel film in ethanol and acetone for 1h, and drying at 60 ℃ under normal pressure to obtain the polymer/graphene composite film with the vertical sandwich structure;
fig. 8 shows a scanning electron micrograph of the polymer/graphene composite film, the cross-section showing a vertical sandwich structure;
fig. 9 shows the thermal conductivity coefficient of the polymer/graphene composite film, and the in-plane and out-of-plane thermal conductivity is excellent.
Claims (6)
1. The thermal interface material with the vertical sandwich structure is characterized by comprising a heat-conducting filler and a polymer material with flexible performance, wherein the mass percentage of the heat-conducting filler to the polymer material is 2.5% -25%; the cross section structure of the thermal interface material is that the upper surface and the lower surface are parallel structures, and a vertical orientation structure is embedded between the parallel structures; the orientation structure of the heat conducting filler of the thermal interface material is that the upper surface and the lower surface are oriented in parallel, and the middle part is oriented vertically;
the preparation method of the thermal interface material comprises the following specific steps:
(1) weighing 10mL of deionized water, adding 0.15-0.3 g of sodium alginate and 0.1-1.2 g of polymer material, fully stirring and mixing under corresponding dissolving conditions, then adding 0.01-0.2 g of heat-conducting filler, and stirring to obtain a mixed gel solution;
(2) dripping the mixed gel solution obtained in the step (1) on a flat base material, placing ice containing calcium ions on the gel, calendering to form a film, freezing, and removing the calcium ion ice to obtain a frozen gel film;
(3) sequentially soaking the frozen film obtained in the step (2) in ethanol and acetone; drying under normal pressure to obtain the thermal interface material with a vertical sandwich structure.
2. A thermal interface material as defined in claim 1, wherein the thermal interface material has a film thickness of 100 to 400 μm.
3. A thermal interface material as claimed in claim 1, wherein the polymer material with flexible property is water soluble, specifically any one of polyvinyl alcohol, aqueous polyurethane or aqueous polyacrylate.
4. The thermal interface material of claim 1, wherein the thermally conductive filler is any one of graphene, hexagonal boron nitride, graphite flakes, MXene, or carbon nanotubes.
5. The method for preparing a thermal interface material with a vertical sandwich structure according to claim 1, comprising the following steps:
(1) weighing 10mL of deionized water, adding 0.15-0.3 g of sodium alginate and 0.1-1.2 g of polymer material, fully stirring and mixing under corresponding dissolving conditions, then adding 0.01-0.2 g of heat-conducting filler, and stirring to obtain a mixed gel solution;
(2) dripping the mixed gel solution obtained in the step (1) on a flat base material, placing ice containing calcium ions on the gel, calendering to form a film, freezing, and removing the calcium ion ice to obtain a frozen gel film;
(3) sequentially soaking the frozen film obtained in the step (2) in ethanol and acetone; drying under normal pressure to obtain the thermal interface material with a vertical sandwich structure.
6. The method according to claim 5, wherein the calcium ion-containing ice of step (2) is prepared by freezing a calcium chloride solution.
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| CN114316573B (en) * | 2022-01-07 | 2023-02-03 | 南京航空航天大学 | Preparation method of slurry-based oriented ordered three-dimensional communication network electric conduction and heat conduction structure |
| CN115260575B (en) * | 2022-08-11 | 2023-11-24 | 复旦大学 | Heat conduction framework with vertical orientation and preparation method and application thereof |
| CN117603506B (en) * | 2024-01-22 | 2024-04-23 | 汕头大学 | Boron nitride heat conduction material with three-dimensional network structure and preparation and application thereof |
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| CN110550956A (en) * | 2019-09-25 | 2019-12-10 | 深圳烯创先进材料研究院有限公司 | preparation method of graphene-polyimide-based composite sponge precursor heat-conducting film |
| CN111391440A (en) * | 2020-03-17 | 2020-07-10 | 四川大学 | Insulating and heat-conducting polymer composite material with frequency-selective electromagnetic shielding function and preparation method thereof |
| CN112409791A (en) * | 2020-11-23 | 2021-02-26 | 中国科学院深圳先进技术研究院 | Heat-conducting composite material and preparation method thereof |
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| CN110550956A (en) * | 2019-09-25 | 2019-12-10 | 深圳烯创先进材料研究院有限公司 | preparation method of graphene-polyimide-based composite sponge precursor heat-conducting film |
| CN111391440A (en) * | 2020-03-17 | 2020-07-10 | 四川大学 | Insulating and heat-conducting polymer composite material with frequency-selective electromagnetic shielding function and preparation method thereof |
| CN112409791A (en) * | 2020-11-23 | 2021-02-26 | 中国科学院深圳先进技术研究院 | Heat-conducting composite material and preparation method thereof |
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