Low contact thermal resistance heat conducting film and preparation method and application thereof

Abstract

The application provides a low-contact thermal resistance heat-conducting film and a preparation method and application thereof. The low-contact thermal resistance heat-conducting film of the application is coated with a liquid metal microcapsule layer on the surface of the film; the liquid metal microcapsule layer comprises the following components in mass fraction: liquid metal microcapsule: 400-2200 parts, carbon material: 1-10 parts. The heat-conducting film of the application is simple in preparation method, suitable for industrialized production, low in contact thermal resistance, which can be as low as 1.33mm 2 K / W, good in heat dissipation effect, simple to use and reusable, and capable of well meeting the needs of the majority of electronic products.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal interface, in particular to a low contact thermal resistance heat-conducting film and its preparation method and application. BACKGROUND

[0002] With the development of electronic technology, the miniaturization and high integration of electronic devices lead to a sharp increase in heat flux density. Heat dissipation has become a key problem affecting the performance and service life of equipment. To achieve efficient heat dissipation, heat-conducting films such as graphene films are widely used in electronic device thermal management, which can effectively transfer heat from high-temperature areas to low-temperature areas.

[0003] Heat-conducting films are usually made of materials such as graphite, graphene, graphene oxide, and boron nitride, with thermal conductivity of several tens to several hundred Wm -1 K -1 In addition to excellent thermal conductivity, heat-conducting films also have excellent flexibility, high-temperature resistance, mechanical properties, and chemical stability. By adding different types of fillers to the heat-conducting film, its performance can be adjusted to meet various application requirements. For example, adding high-thermal-conductivity fillers such as metal nanoparticles, boron nitride, aluminum nitride, and carbon nanotubes to the heat-conducting film can create more heat-conducting pathways, significantly enhancing the thermal conductivity of the film. Introducing high-enthalpy phase change materials such as paraffin, fatty acids, and alcohols into the heat-conducting film can store and release energy through the phase change process. This feature helps to reduce thermal shock and maintain temperature within a predetermined range, effectively protecting equipment. However, these low-thermal-conductivity organic phase change materials can reduce the overall thermal conductivity of the film.

[0004] Although the above heat-conducting films have improved thermal management capabilities to varying degrees through improved preparation processes, in actual applications, due to the incomplete flatness of the surface or uneven thickness, there are inevitably gaps between the heat-conducting film and the heat-generating components or heat sinks, and the air (thermal conductivity = 0.026 Wm -1 K -1 ) filling the gaps can also severely affect heat dissipation. Therefore, developing a heat-conducting film with low contact thermal resistance and good heat dissipation effect can better meet the thermal management needs of electronic products. SUMMARY

[0005] To address the deficiencies of the prior art, the present application provides a low contact thermal resistance heat-conducting film and its preparation method and application. The preparation method of the heat-conducting film of the present application is simple and suitable for industrial production. The heat-conducting film of the present application has low contact thermal resistance, which can be as low as 1.33 mm 2 K / W, and good heat dissipation effect, is simple to use and reusable, and can well meet the wide needs of electronic products.

[0006] The technical solutions of the present application are as follows:

[0007] A low contact thermal resistance heat conducting film, the heat conducting film is coated with a liquid metal microcapsule layer on the surface of the film; the liquid metal microcapsule layer comprises the following components in mass fraction: liquid metal microcapsule: 400-2200 parts, carbon material: 1-10 parts.

[0008] According to the application, preferably, the film is one of a graphite heat conducting film, a graphene heat conducting film, a graphene oxide heat conducting film, a nanocarbon heat conducting film or a boron nitride heat conducting film; the thickness of the film is 80-120 microns. The film can be directly purchased on the market.

[0009] According to the application, preferably, the thickness of the liquid metal microcapsule layer is 1-6 microns.

[0010] According to the application, preferably, the liquid metal microcapsule layer comprises the following components in mass fraction: liquid metal microcapsule: 434-848 parts, carbon material: 1-5 parts.

[0011] Preferably, the liquid metal microcapsule layer comprises the following components in mass fraction: liquid metal microcapsule: 600-700 parts, carbon material: 1-5 parts.

[0012] According to the application, preferably, the carbon material is one or a combination of two or more of graphene, graphene oxide, carbon nanotube, carbon fiber or carbon powder.

[0013] According to the application, preferably, the liquid metal microcapsule is one or a combination of two or more of cesium-based microcapsule, gallium-based microcapsule, indium-based microcapsule or tin-based microcapsule.

[0014] According to the application, preferably, the particle size of the liquid metal microcapsule is 2-5 microns.

[0015] According to the application, preferably, the core material of the liquid metal microcapsule is one or a combination of two or more of cesium, gallium, indium or tin; and the shell material is one or a combination of two or more of silicon dioxide, calcium carbonate or silicon carbide.

[0016] According to the application, preferably, the liquid metal microcapsule is prepared from the following raw materials in mass fraction: liquid metal: 400-600 parts, nucleating agent: 1-5 parts, surfactant: 20-50 parts, shell precursor: 30-60 parts, catalyst: 1500-2000 parts.

[0017] Preferably, the liquid metal microcapsule is prepared from the following raw materials in mass fraction: liquid metal: 450-550 parts, nucleating agent: 2-4.2 parts, surfactant: 25-40 parts, shell precursor: 45-50 parts, catalyst: 1800-1850 parts.

[0018] Further preferably, the liquid metal microcapsule is prepared from the following raw materials by mass fraction: liquid metal: 500 parts, nucleating agent: 2.5 parts, surfactant: 30 parts, shell material precursor: 46 parts, and catalyst: 1820 parts.

[0019] Preferably, the liquid metal is one or a combination of two or more of cesium, gallium, indium, or tin; the nucleating agent is one or a combination of two or more of iron, copper, tellurium dioxide, calcium oxide, or magnesium oxide; the surfactant is one or a combination of two or more of cetyltrimethylammonium bromide, dodecyldimethylamine oxide, dopamine hydrochloride, or sodium dodecyl sulfate; the shell material precursor is one or a combination of two or more of tetraethyl orthosilicate, calcium hydroxide, methyl silicate, or triethoxysilane; and the catalyst is one or a combination of two or more of silver hydroxide, sodium hydroxide, sodium bicarbonate, or ammonia water with a mass concentration of 20-30%.

[0020] Preferably, the method for preparing the liquid metal microcapsule comprises the following steps:

[0021] (1) mixing the liquid metal and the nucleating agent at a room temperature of 800-2000 r / min for 10-20 min in a planetary centrifugal mixer, then adding dropwise into a surfactant aqueous solution with a mass concentration of 5-15%, and obtaining a mixed solution by ultrasonic treatment at 100-800 W for 1-2 h;

[0022] (2) mixing the shell material precursor and the catalyst at a room temperature of 500-2000 r / min for 15-25 min to obtain a shell layer reactant;

[0023] (3) mixing the mixed solution obtained in step (1) and the shell layer reactant obtained in step (2), stirring at a room temperature of 800-2000 r / min for 1-2 h, and then filtering, washing, and drying to obtain the liquid metal microcapsule.

[0024] Further preferably, in step (1), the ultrasonic power is 400-500 W, and more preferably, the ultrasonic power is 400 W.

[0025] The method for preparing the low-contact thermal resistance heat-conducting film comprises the following steps:

[0026] (1) dispersing the liquid metal microcapsule and the carbon material in water to obtain a dispersion liquid;

[0027] (2) coating the dispersion liquid on the surface of the film, and drying to obtain the low-contact thermal resistance heat-conducting film.

[0028] Preferably, in step (1), the mass ratio of the carbon material to water is 1:1000-2000.

[0029] According to the application, preferably, in step (1), the sufficient dispersion is stirring at room temperature for 10-20 min, and the stirring rate is 600-2000 r / min.

[0030] According to the application, preferably, in step (2), the drying temperature is 50-60 DEG C.

[0031] The low-contact thermal resistance heat-conducting film can be applied to the interface between electronic components and heat sinks to achieve heat dissipation, reduce the contact thermal resistance and achieve excellent heat dissipation effect.

[0032] The technical features and advantages of the application are as follows:

[0033] 1. The heat-conducting film of the application adds liquid metal microcapsules, which greatly reduces the contact thermal resistance by using flexible deformation capacity, and has high thermal conductivity while closely adhering to the surface. The application adds carbon materials to enhance the bonding force between the liquid metal microcapsules and the commercial film, so that they can be firmly attached together, thereby being reusable and further improving the thermal conductivity.

[0034] 2. The liquid metal selected in the liquid metal microcapsules has a large latent heat value, which can absorb a large amount of heat during the phase change process; the shell material is an inorganic material with high thermal conductivity, which is more conducive to heat transfer. In the preferred liquid metal microcapsules of the application, the core material adds a nucleating agent, which reduces the supercooling degree and significantly improves the latent heat of the microcapsule phase change; but when no nucleating agent, a small amount or an excessive amount of nucleating agent is added, the supercooling effect is not reduced, resulting in a latent heat value of the obtained microcapsule being substantially 0. In the preparation method of the preferred liquid metal microcapsules of the application, the ultrasonic power of the micronization has a great influence on the performance of the microcapsules. When the power is too low, the liquid metal cannot be effectively dispersed into small droplets, and when the power is too high, the obtained liquid metal microcapsules have a small particle size and weak heat storage capacity, resulting in a decrease in the latent heat value of the microcapsules. The inorganic shell of the microcapsules can protect the internal liquid metal, solve the problems of easy oxidation and easy leakage, greatly reduce the loss of the liquid metal, and reduce the cost. The liquid metal microcapsules have excellent latent heat performance, and when the microcapsules are coated on the commercial film, they can fill the surface wrinkles, increase the heat exchange area, reduce the contact thermal resistance, and thus achieve the effect of heat exchange enhancement.

[0035] 3. In the raw material composition of the application, the carbon material plays the role of adhesive. If no carbon material is added or the amount of the carbon material is insufficient, the microcapsules are easily detached from the film. At the same time, the carbon material also plays the role of constructing a heat-conducting path and filling the gaps between the microcapsules.

[0036] 4. The preparation method of the application is simple and suitable for industrial production. The heat-conducting film has a low contact thermal resistance, which can be as low as 1.33 mm 2K / W, and has good heat dissipation effect, is simple to use and reusable, and can well meet the needs of the majority of electronic products. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the effect diagram of the low contact thermal resistance heat-conducting film pad prepared by the embodiment 2 of the present application under the heat-generating chip.

[0038] Figure 2 is the total thermal resistance comparison diagram of the low contact thermal resistance heat-conducting film prepared by the embodiments 3-8 of the present application. DETAILED DESCRIPTION

[0039] The present application will be further described below in conjunction with specific embodiments, but is not limited thereto.

[0040] Meanwhile, the experimental methods described in the following embodiments are all conventional methods unless otherwise specified; and the reagents and materials described are all available from commercial channels unless otherwise specified.

[0041] Preparation Example 1

[0042] A liquid metal microcapsule is prepared from the following raw materials in mass parts: liquid gallium: 500 parts, nucleating agent tellurium dioxide: 2.5 parts, surfactant dopamine hydrochloride: 30 parts, shell material precursor tetraethyl orthosilicate: 46 parts, and catalyst ammonia water with a mass concentration of 25%: 1820 parts.

[0043] The preparation method of the above-mentioned liquid metal microcapsule comprises the following steps:

[0044] S1. Pour 500 parts of liquid metal gallium and 2.5 parts of tellurium dioxide into a planetary centrifugal mixer, and stir at 2000 r / min at room temperature for 10 min;

[0045] S2. Take 30 parts of dopamine hydrochloride and dissolve it in 300 parts of water to prepare a surfactant aqueous solution;

[0046] S3. Add the mixture (liquid) obtained in the above step S1 dropwise to the solution obtained in the above step S2, and perform ultrasonic micronization at a power of 400 W for 1 h;

[0047] S4. Mix 46 parts of tetraethyl orthosilicate with 1820 parts of ammonia water, and stir at 600 r / min at room temperature for 20 min;

[0048] S5. Mix the solution obtained in the above step S3 with the solution obtained in step S4, and stir at 1200 r / min at room temperature for 2 h;

[0049] S6. Filter, wash and dry the mixture obtained in the reaction of the above step S5 to finally obtain the liquid metal microcapsule.

[0050] The liquid metal microcapsule prepared in the preparation example has a melting point of 30.9°C and a latent heat value of 46.7 J / g.

[0051] Example 1

[0052] A low contact thermal resistance heat-conducting film, which is a commercial graphene heat-conducting film (100 microns in thickness) coated with a liquid metal microcapsule layer of 2 microns in thickness; the liquid metal microcapsule layer comprises the following components in mass fraction: gallium-based liquid metal microcapsules (2-5 microns in particle size) prepared in Preparation Example 1: 600 parts, carbon material graphene oxide (50-100 microns in particle size): 1 part.

[0053] The preparation method of the low contact thermal resistance heat-conducting film comprises the following steps:

[0054] S1. Take 600 parts of gallium-based liquid metal microcapsules and 1 part of graphene oxide and disperse them in 1500 parts of water, and stir at room temperature at 600 r / min for 15 min;

[0055] S2. Take the commercial graphene heat-conducting film and lay it on a smooth plane;

[0056] S3. Coating the mixture obtained in step S1 on one surface of the commercial graphene heat-conducting film in step S2, and placing it in a drying oven at 60°C for 10 min;

[0057] S4. Lay the heat-conducting film obtained in step S3 on a smooth plane, and coating the mixture obtained in step S1 on the other surface of the commercial graphene heat-conducting film, and placing it in a drying oven at 60°C for 10 min, to obtain a low contact thermal resistance heat-conducting film.

[0058] The low contact thermal resistance heat-conducting film prepared in the example has a contact thermal resistance of 1.38 mm 2 K / W, and the test method of the contact thermal resistance is a steady-state method. The effective thermal conductivity is 1.19 W / (mk). The total thermal resistance is 0.05 K / W.

[0059] Example 2

[0060] A low contact thermal resistance heat-conducting film, as described in Example 1, except that the gallium-based liquid metal microcapsules (2-5 microns in particle size) prepared in Preparation Example 1 are 700 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0061] The preparation method of the low contact thermal resistance heat-conducting film is the same as in Example 1.

[0062] The low contact thermal resistance heat-conducting film prepared in the example has a contact thermal resistance of 1.33 mm 2K / W, the testing method of the contact thermal resistance is the steady state method. The effective thermal conductivity is 1.21 W / (mk). The total thermal resistance is 0.04 K / W.

[0063] Example 3

[0064] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 434 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0065] The preparation method of the above low contact thermal resistance heat conducting film is the same as in Example 1.

[0066] The total thermal resistance of the low contact thermal resistance heat conducting film prepared in this example is 0.05 K / W, and the testing method of the total thermal resistance is the steady state method.

[0067] Example 4

[0068] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 610 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0069] The preparation method of the above low contact thermal resistance heat conducting film is the same as in Example 1.

[0070] The total thermal resistance of the low contact thermal resistance heat conducting film prepared in this example is 0.04 K / W, and the testing method of the total thermal resistance is the steady state method.

[0071] Example 5

[0072] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 848 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0073] The preparation method of the above low contact thermal resistance heat conducting film is the same as in Example 1.

[0074] The total thermal resistance of the low contact thermal resistance heat conducting film prepared in this example is 0.04 K / W, and the testing method of the total thermal resistance is the steady state method.

[0075] Example 6

[0076] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 1489 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0077] The preparation method of the above low contact thermal resistance heat conducting film is the same as in Example 1.

[0078] The low contact thermal resistance heat conducting film prepared in the embodiment has a total thermal resistance of 0.09 K / W, and the testing method of the total thermal resistance is the steady state method.

[0079] Example 7

[0080] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 1882 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0081] The preparation method of the low contact thermal resistance heat conducting film is the same as in Example 1.

[0082] The low contact thermal resistance heat conducting film prepared in the embodiment has a total thermal resistance of 0.10 K / W, and the testing method of the total thermal resistance is the steady state method.

[0083] Example 8

[0084] A low contact thermal resistance heat conducting film is prepared as described in Example 1, except that the gallium-based liquid metal microcapsules (particle size 2-5 microns) prepared in Preparation Example 1 are 2193 parts; the other structures and raw materials and their compositions are the same as in Example 1.

[0085] The preparation method of the low contact thermal resistance heat conducting film is the same as in Example 1.

[0086] The low contact thermal resistance heat conducting film prepared in the embodiment has a total thermal resistance of 0.13 K / W, and the testing method of the total thermal resistance is the steady state method.

[0087] Test Example 1

[0088] The sample prepared in Example 2 is packaged between a heat-generating LED chip and a heat sink, and after the temperature is stabilized, the temperature distribution is observed using an infrared thermal imager.

[0089] As shown in Figure 1 , compared with the un-packaged heat conducting film, the final temperature is reduced by 8.2℃.

[0090] Test Example 2

[0091] The total thermal resistance of the films prepared in Examples 3-8 is tested, as shown in Figure 2 .

[0092] With the increase of the microcapsule load, the total thermal resistance first decreases and then increases, and the reason is that a small amount of microcapsules can be deformed under heat, filling the interface gap and reducing the interface thermal resistance, playing a role in heat conduction enhancement, but with the increase of the microcapsule content, the interface thermal resistance no longer changes, and the thermal resistance effect introduced by itself is enhanced. Therefore, loading a small amount of microcapsules can reduce the total thermal resistance of the commercial heat conducting film and improve its thermal management capability.

Claims

1. A low contact thermal resistance thermally conductive film, characterized by, The heat-conducting film is coated with a liquid metal microcapsule layer on the surface of the film; the liquid metal microcapsule layer comprises the following components in mass fraction: liquid metal microcapsule: 434-848 parts; carbon material: 1 part; The film is a graphene heat-conducting film; the carbon material is graphene oxide; the liquid metal microcapsule is a gallium-based microcapsule; the core material of the liquid metal microcapsule is gallium; and the shell material is silicon dioxide; The liquid metal microcapsule is prepared from the following raw materials in mass fraction: liquid metal: 500 parts; nucleating agent: 2.5 parts; surfactant: 30 parts; shell material precursor: 46 parts; and catalyst: 1820 parts; The liquid metal is gallium; the nucleating agent is tellurium dioxide; the surfactant is dopamine hydrochloride; the shell material precursor is tetraethyl orthosilicate; and the catalyst is ammonia water with a mass concentration of 25%; The preparation method of the liquid metal microcapsule comprises the following steps: S1. Pour 500 parts of liquid metal gallium and 2.5 parts of tellurium dioxide into a planetary centrifugal mixer, and stir at 2000 r / min at room temperature for 10 min; S2. Dissolve 30 parts of dopamine hydrochloride in 300 parts of water to prepare a surfactant aqueous solution; S3. Add the mixture obtained in step S1 dropwise to the solution obtained in step S2, and perform ultrasonic micronization at a power of 400 W for 1 h; S4. Mix 46 parts of tetraethyl orthosilicate with 1820 parts of ammonia water, and stir at 600 r / min at room temperature for 20 min; S5. Mix the solution obtained in step S3 with the solution obtained in step S4, and stir at 1200 r / min at room temperature for 2 h; S6. Filter, wash, and dry the mixture obtained in step S5 to obtain the liquid metal microcapsule; The preparation method of the low-contact-thermal-resistance heat-conducting film comprises the following steps: (i) Disperse the liquid metal microcapsule and the carbon material in water to obtain a dispersion liquid; (ii) Coat the dispersion liquid on the surface of the film, and dry to obtain the low-contact-thermal-resistance heat-conducting film.

2. The low contact thermal resistance heat-conductive film according to claim 1, wherein One or more of the following conditions are included: i. The thickness of the film is 20-200 microns; ii. The thickness of the liquid metal microcapsule layer is 1-6 microns.

3. The low contact thermal resistance heat-conductive film according to claim 1, wherein The particle size of the liquid metal microcapsule is 2-5 microns.

4. The low contact thermal resistance heat-conductive film according to claim 1, wherein One or more of the following conditions are included: i. In step (i), the mass ratio of the carbon material to water is 1:1000-2000; ii. In step (i), the sufficient dispersion is stirring at 600-2000 r / min at room temperature for 10-20 min; iii. In step (ii), the drying temperature is 50-60°C.

5. Use of a low contact thermal resistance thermally conductive film according to any one of claims 1 to 4, wherein The low-contact-thermal-resistance heat-conducting film is applied to the interface between electronic components and heat sinks to achieve heat dissipation.

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