Heat conduction material, and preparation method therefor and use thereof

Abstract

The present disclosure belongs to the technical field of materials, and provides a heat conduction material, and a preparation method therefor and the use thereof. The heat conduction material comprises an indium sheet layer, and a first liquid metal layer and a second liquid metal layer which are arranged on the upper surface and the lower surface of the indium sheet layer, respectively; the two liquid metal layers both have a melting point not exceeding 30°C, or the two liquid metal layers both have a melting point not lower than 30°C; and a solid indium-rich alloy is formed in the respective connecting areas of the indium sheet layer and the two liquid metal layers. The heat conduction material has low thermal resistance, good thermal conductivity, and the thermal performance thereof is comparable to that of a pure liquid metal, and the heat conduction material is in a solid state during and after use with no observable liquid component, thereby avoiding the problems in the related technology of short circuit or burnout of a device caused by leakage or flow of a liquid metal, which tends to occur when the liquid metal is used alone.

Description

A thermal conductive material and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 202310968501.8 filed with the State Intellectual Property Office of China on August 2, 2023, entitled “A thermally conductive material, its preparation method and application,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the field of material technology, and in particular to a thermal conductive material and a preparation method and application thereof. Background Art

[0004] With the continuous advancement of science and technology, electronic components and electronic equipment are developing towards miniaturization and micro-miniaturization, but the negative impact of heat dissipation problems is also becoming increasingly serious. Heat dissipation design has become an important part of the modern electronic and electrical industry. At this time, thermally conductive insulating materials are needed to dissipate the generated heat. Using heat sinks to dissipate heat is a more commonly used heat dissipation method.

[0005] Liquid metal is a new type of thermal interface material developed in the past decade, with the characteristics of low thermal resistance and high thermal conductivity. The most critical problem of current liquid metals comes from their fluidity as liquid metals. If they flow or splash onto the power nodes on the surrounding circuits, they will cause short circuits and device burnout, resulting in great losses. In order to prevent this from happening, manufacturers using liquid metal thermal conductive materials often make a layer of protective material around the device to be dissipated (such as a chip), usually a circle of foam, which can effectively block the liquid metal from leaking out. However, this method adds additional costs and takes up a considerable volume, making the already crowded space around the main chip even more tense.

[0006] Although the above-mentioned containment protection method can prevent the risk of short circuit caused by liquid metal overflow, the liquid metal will still leak out of the chip inside the containment material. Although it will not leak outside the containment material, it will still have a great impact on the thermal conductivity. Because it is assumed that the surface of the CPU is originally coated with a uniform layer of liquid metal material, and then during use, some of the liquid metal leaks out and flows to the side. The containment material cannot be 100% close to the edge of the CPU chip, and there must be a gap between them for the liquid metal to flow. Then the liquid metal on the surface of the CPU may not be enough, and there may even be voids in some places, which will obviously greatly affect the overall thermal conductivity. This situation will be more obvious after the machine is placed vertically.

[0007] Summary of the Invention

[0008] The present disclosure provides a thermal conductive material and a preparation method and application thereof, which at least improve the above-mentioned technical problems.

[0009] The present disclosure can be implemented in the following ways.

[0010] In some embodiments, the present disclosure provides a thermally conductive material, which may include an indium sheet layer and a first liquid metal layer and a second liquid metal layer disposed on an upper surface and a lower surface of the indium sheet layer, respectively;

[0011] Wherein, the melting points of the first liquid metal layer and the second liquid metal layer may not exceed 30° C., or the melting points of the first liquid metal layer and the second liquid metal layer may not be lower than 30° C.;

[0012] A solid indium-rich alloy may be formed in the connection area between the indium sheet layer and the first liquid metal layer, and in the connection area between the indium sheet layer and the first liquid metal layer.

[0013] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer are both less than 30°C, the raw materials for preparing the first liquid metal layer and the second liquid metal layer can both be metals or metal alloys with a melting point not exceeding 30°C.

[0014] In an alternative embodiment, the metal may be Ga.

[0015] In an optional embodiment, the metal alloy may be formed of Ga, In, and Sn; more preferably, the metal alloy may be composed of Ga, In, and Sn in a mass ratio of 68.5:21:10.5.

[0016] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer are both not lower than 30° C., the raw materials for preparing the first liquid metal layer and the second liquid metal layer may contain In, Bi and Sn simultaneously.

[0017] In an optional embodiment, the raw materials for preparing the first liquid metal layer and the second liquid metal layer may be composed of In, Bi and Sn in a mass ratio of 51.3:32.3:16.4 or 51:32.5:16.5.

[0018] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer do not exceed 30° C., the thicknesses of the first liquid metal layer and the second liquid metal layer may be 10-50 μm, and the thickness of the indium sheet layer may be 0.05-0.5 mm.

[0019] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer are not lower than 30°C, the thickness of the first liquid metal layer and the second liquid metal layer can be 0.025-0.1 mm, the thickness of the indium sheet layer can be 0.05-0.5 mm, and the thickness of the entire thermal conductive material can be 0.05-0.5 mm.

[0020] In other embodiments, the present disclosure provides a method for preparing a thermally conductive material as described in any of the aforementioned embodiments, which may include the following steps: preparing a first liquid metal layer and a second liquid metal layer on the upper surface and the lower surface of the indium sheet, respectively.

[0021] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer do not exceed 30° C., the raw materials for preparing the first liquid metal layer and the raw materials for preparing the second liquid metal layer can be coated on the upper and lower surfaces of the indium sheet respectively.

[0022] In an alternative embodiment, the coating is performed at 60-90°C.

[0023] In an optional embodiment, the coating is performed by spraying or blade coating.

[0024] In an optional embodiment, the preparation method may further include: heating during the coating, so that the first liquid metal layer, the second liquid metal layer and the indium sheet undergo alloying transformation.

[0025] In an optional embodiment, when the melting points of the first liquid metal layer and the second liquid metal layer are both not lower than 30°C, the raw materials for preparing the first liquid metal layer and the raw materials for preparing the second liquid metal layer are respectively rolled into a first liquid metal sheet and a second liquid metal sheet, and the first liquid metal sheet, the indium sheet and the second liquid metal sheet are stacked in a preset position and then rolled into a thermal conductive material.

[0026] In an optional embodiment, the rolling temperature of the first liquid metal sheet, the indium sheet, and the second liquid metal sheet after stacking can be 65-70°C.

[0027] In an optional embodiment, after the first liquid metal sheet, the indium sheet, and the second liquid metal sheet are stacked, a PET film can be attached to the surface of the first liquid metal sheet facing away from the indium sheet and the surface of the second liquid metal sheet facing away from the indium sheet, and then calendering is performed. After calendering is completed, the PET film is removed.

[0028] In some further embodiments, the present disclosure provides an application of the thermally conductive material according to any of the aforementioned embodiments, which can be used, for example, for heat dissipation of electronic components.

[0029] In an optional embodiment, the electronic component may be a chip or a heat sink.

[0030] The beneficial effects of the present disclosure include at least:

[0031] The thermally conductive material provided by the present disclosure has low thermal resistance, good thermal conductivity, and thermal performance comparable to that of pure liquid metal. In addition, the thermally conductive material is in solid form both during and after use, with no observable liquid component, thus avoiding problems such as device short circuits and burning caused by leakage or flow that are prone to occur when using liquid metal alone in related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0033] FIG1 is a schematic diagram of the present disclosure of the fusion of liquid metal and indium sheet to form a new solid indium-rich alloy;

[0034] FIG2 is a schematic diagram of the liquid metal layer surface beginning to melt and infiltrate and wet the thermal conductive interface in the present disclosure;

[0035] FIG3 is a physical diagram of the thermal conductive material provided in Example 1 of the present disclosure;

[0036] FIG4 is a diagram showing the state of the laptop computer before use in the test example;

[0037] FIG5 is a diagram showing the state of the laptop computer after use in the test example;

[0038] FIG6 is a diagram showing the state of the thermal conductive material before entering the oven in the test example; and

[0039] FIG7 is a diagram showing the state of the thermal conductive material after being put into the oven in the test example. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0041] The thermal conductive material provided by the present disclosure, its preparation method and application are described in detail below.

[0042] The present disclosure provides a thermally conductive material, which may include an indium sheet and a first liquid metal layer and a second liquid metal layer disposed on the upper and lower surfaces of the indium sheet, respectively. A solid indium-rich alloy may be formed in the connecting region between the indium sheet and the first liquid metal layer, and in the connecting region between the indium sheet and the first liquid metal layer.

[0043] In some embodiments, the melting points of the first liquid metal layer and the second liquid metal layer may not exceed 30°C (such as 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 15°C, 20°C, 25°C or 30°C, etc.). For reference, under this condition, the raw materials for preparing the first liquid metal layer and the second liquid metal layer may both be metals or metal alloys having a melting point not exceeding 30°C. Among them, the metal may be Ga, but not limited thereto. The metal alloy may be formed, for example, by Ga, In and Sn, in a mass ratio of 68.5:21:10.5. In addition, the metal alloy may also be composed of Ga, In and Sn in other mass ratios, as long as the melting point of the metal alloy composed thereof does not exceed 30°C.

[0044] Accordingly, under the condition that the melting points of the first liquid metal layer and the second liquid metal layer do not exceed 30° C., the thickness of the first liquid metal layer and the second liquid metal layer can be 10-50 μm, such as 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm. The thickness of the indium sheet layer can be 0.05-0.5 mm, such as 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm or 0.5 mm. In some embodiments, the thickness of the first liquid metal layer and the second liquid metal layer may not exceed 10% of the thickness of the indium sheet layer.

[0045] The raw materials for preparing the first and second liquid metal layers, both of which have melting points no greater than 30°C, are liquid at room temperature. In related art, liquid metals with this melting point are typically applied directly to the surface of a device to be dissipated (such as a chip or heat sink) to dissipate heat. However, due to their fluidity, they are in liquid form and can easily flow or splash onto energized nodes in surrounding circuits, causing short circuits and device burns. Even with containment protection, it is difficult to completely prevent the liquid metal applied to the surface of the heat dissipating device from flowing and leaking into other spaces.

[0046] The present invention sets the thermal conductive material into a structure with an indium sheet in the middle and liquid metal layers on both sides, so that the indium sheet can play a skeleton and support role. In addition, the indium sheet itself can be used as a thermal interface material. It has good softness, is non-toxic and non-hazardous, can undergo certain deformation at the thermal interface and exert certain gap-filling ability, and has a low thermal resistance (about 0.15cm at 50psi). 2 ·K / W).

[0047] On this basis, due to the thin thickness of the first liquid metal layer and the second liquid metal layer, during the preparation process, most of the raw materials for the preparation of the liquid metal can react and fuse with the indium sheet covered by the liquid metal to form a new alloy, some of which form a series of eutectic alloys (such as InBiSn alloy or GaInSn alloy), and some form non-equilibrium alloys (i.e., non-eutectic alloys). The above series of eutectic alloys and non-equilibrium alloys are all in solid state, and the closer to the surface of the thermal conductive material, the lower the In content. When the thermal conductive material is heated (e.g., 50-70°C) and used, the series of eutectic alloys and non-equilibrium alloys formed above will all undergo a short (about 10s) phase change and melt. Although this phase change process occurs within a short period of time, this short period of time is sufficient for the melted portion to move to the position where the gap in the thermal conductive material needs to be filled (i.e., filling the gap in the thermal interface, such as the micro-undulations and gaps between the chip and the heat dissipation module, resulting in extremely low thermal resistance) to perform the function of "thermal interface material". In other words, the majority of the liquid metal reacts and fuses with the surface indium sheet covered by the liquid metal to form a new alloy. The middle indium sheet acts as a support, maintaining its original ductility and toughness, while a small amount of liquid metal fills the gaps between the contact surfaces. The new solid alloy formed is a metastable non-eutectic alloy with a variable melting point, ranging from approximately 130-150°C. Thereafter, during normal operation of the device to be dissipated, the entire thermally conductive material remains in a solid state (no liquid state), effectively solving important key defects such as liquid metal flow and sag.

[0048] In other embodiments, the melting point of the first liquid metal layer and the second liquid metal layer is not less than 30°C, such as 40°C, 50°C, 55°C, 60°C, 65°C or 70°C, and preferably 50-70°C. For reference, under this condition, the raw materials for preparing the first liquid metal layer and the second liquid metal layer may simultaneously contain In, Bi and Sn, for example, by way of example but not limitation, and may be composed of In, Bi and Sn in a mass ratio of 51.3:32.3:16.4 or 51:32.5:16.5. In addition, the metal alloy may also be composed of In, Bi and Sn in other mass ratios, as long as the melting point of the metal alloy composed thereof is not less than 30°C.

[0049] Accordingly, when the melting points of the first liquid metal layer and the second liquid metal layer are both not lower than 30°C, the thickness of the first liquid metal layer and the second liquid metal layer can be 0.025-0.1mm, such as 0.025mm, 0.05mm, 0.08mm or 0.1mm. The thickness of the indium sheet layer can be 0.05-0.5mm, such as 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm or 0.5mm. In some embodiments, the thickness of the entire thermal conductive material is 0.05-0.5mm, that is, the stacked first liquid metal layer, indium sheet layer and second liquid metal layer can be pressed together to a preset thickness of the thermal conductive material by calendering.

[0050] The first liquid metal layer and the second liquid metal layer, both of which have melting points of not less than 30°C, are solid at room temperature. Related technologies usually place them on the surface of the device to be dissipated. However, when the temperature of the device to be dissipated exceeds 60°C, the liquid metal in the above metal layer will melt into liquid, which is fluid and easy to flow or splash onto the power nodes on the surrounding circuits, causing short circuits and device burning. Even if containment protection is adopted, it is difficult to completely prevent the liquid metal applied on the surface of the device with heat dissipation from flowing and leaking into other spaces.

[0051] The present invention sets the thermal conductive material into a structure with an indium sheet in the middle and liquid metal layers on both sides, so that the indium sheet can play a skeleton and support role. In addition, the indium sheet itself can be used as a thermal interface material. It has good softness, is non-toxic and non-hazardous, can undergo certain deformation at the thermal interface and exert certain gap-filling ability, and has a low thermal resistance (about 0.15cm at 50psi). 2 ·K / W).

[0052] At the rolling temperature (65-70°C) during the preparation process, the liquid metal layer is in a state of solid-liquid mixing, maintaining its sheet shape but the surface has begun to melt. The surface in contact with the indium sheet will penetrate into the indium metal and fuse with the indium metal surface to form a new solid indium-rich alloy (as shown in Figure 1). After cooling to room temperature, the entire thermal conductive material becomes a solid form. When it is placed in the device to be dissipated, if the heat source heats up more than 60°C, the surface of the liquid metal layer of the above-mentioned thermal conductive material begins to melt and penetrate and wet the thermal conductive interface (as shown in Figure 2). At the same time, it is quickly absorbed by the indium sheet layer, thereby completing the solidification and filling effect. The new solid alloy layer formed on the middle indium sheet layer and the two sides plays a skeleton support role and will not melt, which can ensure the integrity and stability of the thermal conductive material. After that, in the normal operation of the device to be dissipated, the entire thermal conductive material is in a solid state (no liquid state), which effectively solves important key defects such as liquid metal flow and vertical flow.

[0053] As mentioned above, the thermal resistance of the thermal conductive material provided by the present disclosure is very low, about 0.04cm at 20psi. 2 K / W, it is superior to silicone grease or phase-change silicone grease on the market. In actual computer CPU operation tests, its thermal performance is comparable to that of pure liquid metal. However, this thermally conductive material has no observable liquid component during and after use, thus avoiding the risk of liquid metal containment and leakage.

[0054] Accordingly, an embodiment of the present disclosure further provides a method for preparing the above-mentioned thermal conductive material, which may include the following steps: preparing a first liquid metal layer and a second liquid metal layer on the upper surface and the lower surface of the indium sheet, respectively.

[0055] When the melting points of the first liquid metal layer and the second liquid metal layer are both lower than 30° C., the raw materials for preparing the first liquid metal layer and the raw materials for preparing the second liquid metal layer can be coated on the upper surface and the lower surface of the indium sheet respectively.

[0056] The coating is performed at a temperature of 60-90°C (e.g., 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C). For reference, the coating can be performed by spraying or blade coating, for example but not by way of limitation. Heating is performed during the coating process to cause the liquid metal and indium to alloy.

[0057] When the melting points of the first liquid metal layer and the second liquid metal layer are both not lower than 30°C, the raw materials for preparing the first liquid metal layer and the raw materials for preparing the second liquid metal layer can be respectively rolled into a first liquid metal sheet and a second liquid metal sheet, and the first liquid metal sheet, the indium sheet and the second liquid metal sheet can be stacked in a preset position and then rolled into a thermal conductive material.

[0058] For reference, the rolling temperature of the first liquid metal sheet, the indium sheet and the second liquid metal sheet after stacking can be 65-70°C, such as 65°C, 66°C, 67°C, 68°C, 69°C or 70°C.

[0059] In some embodiments, after stacking the first, indium, and second liquid metal sheets, a PET film can be attached to the surface of the first liquid metal sheet facing away from the indium sheet and the surface of the second liquid metal sheet facing away from the indium sheet. The sheet is then rolled. After rolling, the PET film is removed. During the rolling process, the liquid metal and the PET film do not fuse in the contact area; only the area in contact with the indium sheet fuses to form a new solid indium-rich alloy. After cooling to room temperature, the PET film is peeled off to form a thermally conductive material with a predetermined structure.

[0060] In addition, the present disclosure also provides an application of the thermally conductive material, for example, for dissipating heat from electronic components, where the electronic components may be, for example but not limited to, chips or heat sinks.

[0061] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0062] Example 1

[0063] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0064] The liquid metal raw material can be sprayed onto the upper surface and the lower surface of the indium sheet at 70° C. to form a first liquid metal layer with a thickness of 10 μm and a second liquid metal layer with a thickness of 10 μm.

[0065] The thickness of the indium sheet can be 0.15 mm. The raw materials for preparing the first and second liquid metal layers can each be composed of Ga, In, and Sn in a mass ratio of 68.5:21:10.5. The melting point of the liquid metal raw materials in the first and second liquid metal layers can be approximately 10°C.

[0066] A physical picture of the thermal conductive material is shown in FIG3 .

[0067] Example 2

[0068] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0069] The liquid metal raw material can be scraped onto the upper surface and the lower surface of the indium sheet at 60° C. to form a first liquid metal layer with a thickness of 10 μm and a second liquid metal layer with a thickness of 10 μm.

[0070] The thickness of the indium sheet can be 0.15 mm. The raw materials for preparing the first liquid metal layer and the second liquid metal layer can both be metal Ga with a melting point of about 29.5°C.

[0071] The eutectic alloy formed by the mutual diffusion and fusion of Ga and In can be In75Ga25.

[0072] Example 3

[0073] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0074] Pure indium particles, bismuth particles, and tin particles with a purity of >99.99% can be used as raw materials. The mass ratio of indium, bismuth, and tin can be 51:32.5:16.5 respectively. The raw materials in equal proportions are placed in a vacuum medium frequency melting furnace, vacuumed and heated to 400°C for 2 hours.

[0075] After smelting, place it in a vacuum heating stirrer, maintain the temperature at 80°C, and stir at 400 rpm for 30 minutes to mix the liquid metal (melting point is about 60°C) evenly, then pour it into a mold and cool it for later use.

[0076] The pure indium ingot with purity greater than 99.99% is pressed to 0.2 mm by a calender.

[0077] The liquid metal was rolled into a sheet with a thickness of 50 μm.

[0078] The indium sheet and two liquid metal sheets are stacked together with the indium sheet in the middle and the liquid metal sheets on both sides. Then, PET films are attached to the surfaces of the two liquid metal sheets facing away from the indium sheet to obtain the intermediate product to be rolled.

[0079] The calender was heated to 65° C. to calender the intermediate product to be calendered so that the overall thickness of the material could be 0.15 mm. The calender was then cooled and the PET film was removed.

[0080] Example 4

[0081] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0082] Pure indium particles, bismuth particles, and tin particles with a purity of >99.99% can be used as raw materials. The mass ratio of indium, bismuth, and tin can be 51.3:32.3:16.4 respectively. The raw materials in equal proportions are placed in a vacuum medium frequency melting furnace, vacuumed and heated to 400°C for 2 hours.

[0083] After smelting, place it in a vacuum heating stirrer, maintain the temperature at 80°C, and stir at 400 rpm for 30 minutes to mix the liquid metal (melting point is about 60°C) evenly, then pour it into a mold and cool it for later use.

[0084] The pure indium ingot with purity greater than 99.99% is pressed to 0.5 mm by a calender.

[0085] The liquid metal is rolled into a sheet with a thickness of 25 μm.

[0086] The indium sheet and two liquid metal sheets are stacked together with the indium sheet in the middle and the liquid metal sheets on both sides. Then, PET films are attached to the surfaces of the two liquid metal sheets facing away from the indium sheet to obtain the intermediate product to be rolled.

[0087] The calender was heated to 70° C. to calender the intermediate product to be calendered so that the overall thickness of the material could be 0.5 mm. The calender was then cooled and the PET film was removed.

[0088] Example 5

[0089] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0090] The liquid metal raw material can be sprayed on the upper surface and the lower surface of the indium sheet at 60° C. to form a first liquid metal layer with a thickness of 30 μm and a second liquid metal layer with a thickness of 30 μm.

[0091] The thickness of the indium sheet can be 0.05 mm. The raw materials for preparing the first and second liquid metal layers are composed of Ga, In, and Sn in a mass ratio of 55:32:13. The melting point of the liquid metal raw materials in the first and second liquid metal layers can be approximately 25°C.

[0092] Example 6

[0093] This embodiment provides a thermally conductive material, which can be prepared by the following method:

[0094] The liquid metal raw material is sprayed on the upper surface and the lower surface of the indium sheet at 90° C. to form a first liquid metal layer with a thickness of 50 μm and a second liquid metal layer with a thickness of 50 μm.

[0095] The thickness of the indium sheet can be 0.5 mm. The raw materials used to prepare the first and second liquid metal layers are composed of Ga, In, and Sn in a mass ratio of 60:19.5:20.5. The melting point of the liquid metal raw materials in the first and second liquid metal layers can be approximately 18°C.

[0096] Test example

[0097] As shown below, the thermally conductive material (liquid metal thermal conductive sheet) prepared in Example 1 was placed on a high-performance laptop CPU chip. The results after 24 hours of baking were compared with those before and after baking. The results are shown in Figures 4 (before baking) and 5 (after baking). As can be seen from Figures 4 and 5, the thermally conductive material remains solid after use, with no observable liquid content. This avoids the problems of device short circuits and burns caused by leakage or flow of liquid metal, which can occur in related technologies using only liquid metal.

[0098] Furthermore, the thermally conductive material (liquid metal thermal conductive sheet) prepared in Example 1 was subjected to a vertical sag test in a 125°C oven. The results before and after baking are shown in Figures 6 and 7, respectively. Comparison of Figures 6 and 7 shows that after baking at 125°C for 1000 hours, the product exhibited no sag, deformation, or overflow.

[0099] In summary, the thermally conductive material provided by the present disclosure is in a solid form during use, thereby avoiding the problems of device short circuit and burning caused by leakage or flow of liquid metal that are prone to occur in the related art when using liquid metal alone.

[0100] The above are merely preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Those skilled in the art will readily appreciate that various modifications and variations of the present disclosure are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure. Industrial Applicability

[0101] The present disclosure provides a thermally conductive material, a preparation method, and an application thereof. The thermally conductive material has low thermal resistance, good thermal conductivity, and thermal performance comparable to that of pure liquid metal. In addition, the thermally conductive material is in solid form both during and after use, with no observable liquid component, thus avoiding problems such as device short circuits and burning caused by leakage or flow that are prone to occur when using liquid metal alone in related technologies.

[0102] Furthermore, it is understood that the thermally conductive material, preparation method, and application provided herein are reproducible and can be used in a variety of industrial applications. For example, the thermally conductive material, preparation method, and application provided herein can be used in fields related to materials technology.

Claims

1. A thermally conductive material, wherein: The thermally conductive material comprises an indium sheet layer and a first liquid metal layer and a second liquid metal layer respectively arranged on the upper surface and the lower surface of the indium sheet layer; Wherein, the melting points of the first liquid metal layer and the second liquid metal layer are both not more than 30°C, or, the melting points of the first liquid metal layer and the second liquid metal layer are both not less than 30°C; A solid indium-rich alloy is formed in the connection area between the indium sheet layer and the first liquid metal layer and in the connection area between the indium sheet layer and the first liquid metal layer.

2. The thermally conductive material according to claim 1, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are both lower than 30° C., the raw materials for preparing the first liquid metal layer and the second liquid metal layer are both metals or metal alloys having a melting point not higher than 30° C.; Preferably, the metal is Ga; Preferably, the metal alloy is formed of Ga, In and Sn; more preferably, the metal alloy is composed of Ga, In and Sn in a mass ratio of 68.5:21:10.

5.

3. The thermally conductive material according to claim 1, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are both not less than 30° C., the raw materials for preparing the first liquid metal layer and the second liquid metal layer both contain In, Bi and Sn; Preferably, the raw materials for preparing the first liquid metal layer and the second liquid metal layer are composed of In, Bi and Sn in a mass ratio of 51.3:32.3:16.4 or 51:32.5:16.

5.

4. The thermally conductive material according to claim 1 or 2, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are both lower than 30° C., the thicknesses of the first liquid metal layer and the second liquid metal layer are both 10-50 μm, and the thickness of the indium sheet layer is 0.05-0.5 mm.

5. The thermally conductive material according to claim 1 or 3, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are not less than 30°C, the thicknesses of the first liquid metal layer and the second liquid metal layer are both 0.025-0.1 mm, the thickness of the indium sheet layer is 0.05-0.5 mm, and the thickness of the entire thermal conductive material is 0.05-0.5 mm.

6. A method for preparing a thermally conductive material according to any one of claims 1 to 5, wherein: The preparation method comprises the following steps: preparing a first liquid metal layer and a second liquid metal layer on the upper surface and the lower surface of the indium sheet layer respectively.

7. The preparation method according to claim 6, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are both lower than 30° C., coating the raw materials for preparing the first liquid metal layer and the raw materials for preparing the second liquid metal layer on the upper surface and the lower surface of the indium sheet respectively; Preferably, the coating is carried out at 60-90°C.

8. The preparation method according to claim 7, wherein: The coating is carried out by spraying or scraping.

9. The preparation method according to claim 7 or 8, wherein: The preparation method further includes: heating while coating, so that the first liquid metal layer, the second liquid metal layer and the indium sheet undergo alloy transformation.

10. The preparation method according to claim 6, wherein: When the melting points of the first liquid metal layer and the second liquid metal layer are both not less than 30° C., respectively rolling the raw material for preparing the first liquid metal layer and the raw material for preparing the second liquid metal layer into a first liquid metal sheet and a second liquid metal sheet, and stacking the first liquid metal sheet, the indium sheet, and the second liquid metal sheet at a preset position and rolling them into a thermal conductive material; Preferably, the rolling temperature of the first liquid metal sheet, the indium sheet and the second liquid metal sheet after being stacked is 65-70°C.

11. The preparation method according to claim 10, wherein: After the first liquid metal sheet, the indium sheet and the second liquid metal sheet are stacked, a PET film is attached to the surface of the first liquid metal sheet facing away from the indium sheet and the surface of the second liquid metal sheet facing away from the indium sheet, and then calendering is performed. After calendering is completed, the PET film is removed.

12. Use of the thermally conductive material according to any one of claims 1 to 5, wherein: The thermally conductive material is used for heat dissipation of electronic components.

13. The use according to claim 12, wherein: The electronic component is a chip or a heat sink.

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