Liquid metal heat conduction material, coating, preparation method and use thereof

Abstract

Disclosed are a liquid metal heat conduction material and a coating, a preparation method and use thereof, belonging to the technical field of materials. The liquid metal heat conduction material is prepared from the following raw materials in percentage by mass: 0.5-10% of Ga, 50-70% of In, 20-40% of Bi and 5-25% of Sn. The liquid metal heat conduction material can be prepared into a metal heat conduction material coating by means of spraying, and the coating has low preparation cost, excellent heat conduction performance, high heat conduction coefficient, small thermal resistance, good thermal stability and is beneficial in dissipating heat; in addition, the coating is beneficial to improving the bonding force between the heat dissipation module and the heating source, and is convenient to use and has a long service life.

Description

Liquid metal thermal conductive material, coating, preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application number 202310928038.4 filed with the Patent Office of China on July 26, 2023, entitled “A liquid metal thermal conductive material, its coating, 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 liquid metal thermal conductive material, a coating thereof, a preparation method, and an 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 caused by heat dissipation problems is also becoming increasingly serious. Heat dissipation design has become an important part of the modern electronic and electrical industry.

[0005] Currently, the conventional heat dissipation method is to dissipate heat through a metal heat conducting sheet, but this method cannot achieve good thermal conductivity at a low cost.

[0006] In view of this, the present disclosure is proposed.

[0007] Public content

[0008] The present disclosure provides a liquid metal thermal conductive material. The raw materials for preparing the liquid metal thermal conductive material include, by mass percentage, 0.5-10% of Ga, 50-70% of In, 20-40% of Bi and 5-25% of Sn.

[0009] Optionally, the raw materials include 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi, and 9.7-12.2% Sn.

[0010] Optionally, the raw materials for preparing the liquid metal thermal conductive material consist of 0.5-10% Ga, 50-70% In, 20-40% Bi and 5-25% Sn, calculated by mass percentage.

[0011] Optionally, the raw materials are composed of 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi and 9.7-12.2% Sn.

[0012] Optionally, the gallium source providing Ga, the indium source providing In, the bismuth source providing Bi, and the tin source providing Sn are all independently powder materials with an (average) particle size of 3-8 mm.

[0013] The present disclosure provides a method for preparing the aforementioned liquid metal thermal conductive material, comprising the following steps:

[0014] The prepared raw materials are liquefied.

[0015] Optionally, the liquefaction includes at least one of the following features:

[0016] Feature 1: Liquefaction is carried out under vacuum conditions;

[0017] Feature 2: Liquefaction temperature is 300-500℃;

[0018] Feature 3: Liquefaction time is 1.5-2.5h.

[0019] Optionally, under the vacuum conditions, the vacuum degree is ≤1×10 -3 Pa.

[0020] Optionally, the method further includes:

[0021] Stirring and mixing the liquid raw materials to ensure uniform mixing of the raw materials;

[0022] Optionally, the stirring is performed at 100-120° C. and 350-450 r / min for 25-35 min.

[0023] The present disclosure provides a metal thermal conductive material coating, comprising the aforementioned liquid metal thermal conductive material or the liquid metal thermal conductive material obtained by the aforementioned preparation method.

[0024] Optionally, the thickness of the metal thermal conductive material coating may be 5-20 μm.

[0025] The present disclosure provides a metal thermal conductive material coating, which is formed by spraying the aforementioned liquid metal thermal conductive material or the liquid metal thermal conductive material obtained by the aforementioned preparation method.

[0026] Optionally, the thickness of the metal thermal conductive material coating may be 5-20 μm.

[0027] The present disclosure provides a method for preparing the aforementioned metal thermal conductive material coating, comprising the following steps: spraying the aforementioned liquid metal thermal conductive material or the liquid metal thermal conductive material obtained by the aforementioned preparation method onto the surface of the material to be sprayed, and cooling to form the coating.

[0028] Optionally, the liquid metal thermally conductive material is in a liquid state before being ejected from the nozzle; and the liquid metal thermally conductive material is in a paste state after being ejected from the nozzle.

[0029] Optionally, the liquid metal thermal conductive material remains in a liquid state before being ejected from the nozzle; and the liquid metal thermal conductive material is in a viscous paste state after being ejected from the nozzle.

[0030] Optionally, before the liquid metal heat conductive material is ejected from the nozzle, a component for conveying the liquid metal heat conductive material is maintained at a temperature of not less than 120° C.;

[0031] Optionally, the component is a feeding pipe and / or a nozzle.

[0032] Optionally, the thermally conductive metal material in a paste state contains In oxide, Sn oxide, and Bi oxide at the same time.

[0033] Optionally, the total amount of In oxide, Sn oxide and Bi oxide accounts for 4-6 wt % of the metal thermal conductive material in a paste state.

[0034] Optionally, the In oxide includes In2O3, the Sn oxide includes SnO2, and the Bi oxide includes Bi2O3.

[0035] Optionally, the spraying speed is 150-250 mm / s; and / or the spraying distance is 25-35 cm.

[0036] The present disclosure provides an electronic component, which includes a heat dissipation module and a heat source, wherein the contact surface between the heat dissipation module and the heat source has the aforementioned metal thermal conductive material coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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 paying any creative work.

[0038] FIG1 is a photograph of the coating after spraying provided in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0039] 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 shall be followed. Where the manufacturer of the reagents or instruments used is not specified, all are commercially available conventional products.

[0040] The following is a detailed description of the liquid metal thermal conductive material, its coating, preparation method, and application provided by the present disclosure.

[0041] The present disclosure provides a liquid metal thermal conductive material, which has high thermal conductivity and low preparation cost.

[0042] The present disclosure provides a method for preparing a liquid metal thermal conductive material.

[0043] The present disclosure provides a metal thermal conductive material coating prepared from liquid metal thermal conductive material.

[0044] The present disclosure provides a method for preparing a metal thermal conductive material coating.

[0045] The present disclosure provides an electronic component containing a metal thermal conductive material coating.

[0046] One embodiment of the present disclosure provides a liquid metal thermal conductive material, wherein the raw materials for preparing the liquid metal thermal conductive material include, by mass percentage, 0.5-10% Ga, 50-70% In, 20-40% Bi, and 5-25% Sn.

[0047] In the liquid metal thermal conductive material provided by the present disclosure, Ga has strong wettability to metal or Si. By combining In, Bi, Sn and Ga together, it can have better wettability than the thermal conductive material containing only In, Bi and Sn, which is more conducive to exerting the good thermal conductivity and heat dissipation effect of the liquid metal thermal conductive material.

[0048] In some embodiments, the mass percentage of Ga in the raw material can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, or any value in a range consisting of any two of these values, without limitation. For example, the mass percentage of Ga in the above raw material can also be 1-9%, 2-8%, 3-7%, 4-6%, etc.

[0049] Without being bound by theory, it is believed that if the mass fraction of Ga in the raw material is less than 0.5%, the wettability and thermal conductivity of the liquid metal thermal conductive material will be unsatisfactory. If the mass fraction of Ga in the raw material exceeds 10% (e.g., reaching 45% or above), it will easily affect the flexibility of the material, making the coating surface brittle and prone to cracking. In addition, Ga has a small atomic radius and good wettability with metals. If Ga is used in excessive amounts, it will penetrate into metals such as Cu and Al, destroying their atomic bonds, forming intermetallic compounds, and corroding them.

[0050] In some embodiments, the mass percentage of In in the raw materials may be 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, or 70%, or any value within a range consisting of any two of these values, without limitation. For example, the mass percentage of In in the raw materials may be 52-68%, 55-65%, 58-62%, or 60-68%, or the like.

[0051] In some embodiments, the mass percentage of In in the raw material may be 55.8-65.3%.

[0052] It is believed, without being bound by theory, that if the mass fraction of In in the raw material is less than 50%, the ductility of the material will be reduced; if the mass fraction of In in the raw material is more than 70%, the melting point of the material will be increased.

[0053] In some embodiments, the mass percentage of Bi in the raw material can be 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, or 40%, or any value within a range consisting of any two of these values, without limitation. For example, the mass percentage of Bi in the raw material can be 22-40%, 25-38%, 28-35%, or 30-38%, or the like.

[0054] In some embodiments, the mass percentage of Bi in the raw material may be 22-25%.

[0055] It is believed, without being bound by theory, that if the mass fraction of Bi in the raw material is less than 20%, the wettability of the material will be reduced; if the mass fraction of Bi in the raw material is more than 40%, the melting point of the material will be increased and the thermal conductivity will be decreased.

[0056] In some embodiments, the mass percentage of Sn in the raw material can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, or 25%, or any value within a range consisting of any two of these values, without limitation. For example, the mass percentage of Sn in the raw material can be 5-22%, 8-20%, or 10-15%, or the like.

[0057] In some embodiments, the mass percentage of Sn in the raw material may be 9.7-12.2%.

[0058] It is believed, without being bound by theory, that if the mass fraction of Sn in the raw material is less than 5%, the thermal conductivity of the material will be reduced; if the mass fraction of Sn in the raw material is more than 25%, the melting point of the material will be increased.

[0059] In some optional embodiments, the raw materials for preparing the liquid metal thermal conductive material may include 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi, and 9.7-12.2% Sn. Within this ratio range, a liquid metal thermal conductive material with better thermal conductivity can be obtained.

[0060] In some optional embodiments, the raw materials for preparing the liquid metal thermal conductive material consist of 0.5-10% Ga, 50-70% In, 20-40% Bi and 5-25% Sn, calculated by mass percentage.

[0061] In some optional embodiments, the preparation raw material consists of 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi and 9.7-12.2% Sn.

[0062] In the present disclosure, the gallium source providing Ga, the indium source providing In, the bismuth source providing Bi, and the tin source providing Sn are all independently powder materials. For example, the (average) particle size of these powder materials can be 3-8 mm, for example, it can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm, etc., or any value within the range of any two of these values, and is not limited here.

[0063] It is believed, without being bound by theory, that if the particle size of the powder material is less than 3 mm, the surface is too exposed and the possibility of external oxide film formation increases; if the particle size of the powder material is greater than 8 mm, it is not conducive to reducing the melting efficiency.

[0064] It should be noted that the present disclosure specifically uses powder materials under the above-mentioned particle size conditions, which can enable liquid metal thermal conductive materials to be prepared into metal thermal conductive material coatings with better performance (such as surface flatness, uniformity of materials in the coating, thermal conductivity of the coating, etc.) by spraying. Not only is the preparation cost low, but it is also beneficial to improve the bonding force between the heat dissipation module and the heat source, thereby extending the service life of the corresponding product.

[0065] One embodiment of the present disclosure further provides a method for preparing the above-mentioned liquid metal thermal conductive material, which may include the following steps: liquefying the raw materials.

[0066] In some optional embodiments, the liquefaction process can be carried out in a furnace, and vacuum conditions are maintained in the furnace. The corresponding vacuum degree during the liquefaction process can be ≤1×10 -3 Pa.

[0067] It is believed, without being bound by theory, that the raw materials of liquid metal thermal conductive materials need to be liquefied under vacuum conditions to prevent oxidation of the materials. -3 Pa, which can easily cause the material to oxidize prematurely.

[0068] In some optional embodiments, the liquefaction temperature may be 300-500°C, such as 300°C, 350°C, 400°C, 450°C or 500°C, or any other value within the range of 300-500°C.

[0069] It should be noted that the present disclosure controls the liquefaction temperature between 300°C and 500°C to melt the raw materials and form an alloy. If the liquefaction temperature is below 300°C but above 100°C, it is not conducive to sufficient melting of the material. If the liquefaction temperature is above 500°C, it is not conducive to improving smelting efficiency, and it is likely to affect the quality of the finished product and may also cause metal volatilization.

[0070] The liquefaction time may be 1.5-2.5 h, such as 1.5 h, 2 h or 2.5 h, etc., or any other value within the range of 1.5-2.5 h.

[0071] Through the above liquefaction stage, all the raw materials for preparing the liquid metal thermal conductive material are in liquid form.

[0072] In some optional embodiments, the liquid raw materials can be stirred and mixed to ensure uniform mixing of the raw materials. For example, the stirring process can be carried out at 100-120° C. and 350-450 rpm for 25-35 minutes.

[0073] In some optional embodiments, the temperature of the stirring process can be 100°C, 105°C, 110°C, 115°C or 120°C, etc., or any other value within the range of 100-120°C.

[0074] In some optional embodiments, the stirring rate of the stirring process can be 350 r / min, 370 r / min, 390 r / min, 400 r / min, 420 r / min or 450 r / min, etc., or any other value within the range of 350-450 r / min.

[0075] In some optional embodiments, the stirring time of the stirring process can be 25 min, 27 min, 29 min, 30 min, 32 min or 35 min, etc., or any other value within the range of 25-35 min.

[0076] It is believed, without being bound by theory, that the present disclosure can obtain a liquid metal thermal conductive material with uniform composition and good fluidity through the above-mentioned liquefaction method.

[0077] One embodiment of the present disclosure provides a metal thermal conductive material coating, which is formed by spraying the above-mentioned liquid metal thermal conductive material and can be used as a thermal conductive layer.

[0078] For reference, the thickness of the metal thermal conductive material coating may be 5-20 μm, such as 5 μm, 10 μm, 15 μm or 20 μm.

[0079] Accordingly, the present disclosure provides a method for preparing a metal thermal conductive material coating as described in the aforementioned embodiment, which may include the following steps: spraying the liquid metal thermal conductive material onto the surface of the material to be sprayed, and cooling the material to form the coating.

[0080] It should be noted that In, Bi, and Sn are highly ductile metals, while Ga is a brittle metal. Therefore, the liquid metal thermal conductive material disclosed herein cannot be produced into sheet products using conventional rolling methods. The present disclosure utilizes a spraying method to deposit the liquid metal thermal conductive material onto the thermal interface (e.g., between the heat dissipation module and the heat source). This method not only reduces production costs and allows for easily controlled process conditions, but also produces a coating product with superior performance.

[0081] In the present disclosure, the liquid metal thermal conductive material always remains in a liquid state before being ejected from the nozzle; and the liquid metal thermal conductive material is in a viscous paste state after being ejected from the nozzle.

[0082] For reference, the spraying method is air spraying, which uses compressed air to atomize the paint. In order to control the liquid metal thermal conductive material to remain in a liquid state before being sprayed from the nozzle, the components that convey the liquid metal thermal conductive material (such as the feeding pipe and nozzle) can be kept at no less than 120°C.

[0083] If the metal thermal conductive material is always sprayed onto the surface to be sprayed in liquid form, the thermal conductivity stability of the final coating will be greatly reduced; if the metal thermal conductive material is directly prepared into a coating in a paste form, the paste-like metal thermal conductive material has high tension, which will make coating difficult and difficult to implement.

[0084] It's important to emphasize that the present disclosure achieves superior coating performance by controlling the specific state of the metal thermally conductive material before and during spraying. Specifically, in the disclosed solution, the liquid metal thermally conductive material is partially oxidized between the time it is ejected from the nozzle and the time it reaches the surface to be sprayed, resulting in a viscous paste. This paste exhibits significantly lower fluidity than a non-oxidized liquid, resulting in improved thermal conductivity stability.

[0085] The liquid metal thermal conductive material in the paste state contains In oxide (such as In2O3), Sn oxide (such as SnO2) and Bi oxide (such as Bi2O3) at the same time, and Ga is basically not oxidized.

[0086] In some embodiments, the total amount of In oxide, Sn oxide, and Bi oxide accounts for 4-6 wt % of the liquid metal thermal conductive paste, such as 4 wt %, 4.5 wt %, 5 wt %, 5.5 wt %, or 6 wt %, and can be 4-5 wt %. Taking the total amount of In oxide, Sn oxide, and Bi oxide as 5 wt % of the liquid metal thermal conductive paste as an example, In2O3 can be approximately 3%, SnO2 can be approximately 1%, and Bi2O3 can be approximately 1%.

[0087] It is precisely because the oxides of In, Sn and Bi contained in the above ranges that these oxides have good chemical stability and thermal stability, so that the coating obtained by spraying can have better thermal stability and thermal conductivity.

[0088] It should be noted that if the amount of In, Sn and Bi oxidized is too much, for example, more than 6 wt %, it is not conducive to improving the thermal conductivity.

[0089] In the present disclosure, the spraying speed may be 150-250 mm / s, such as 150 mm / s, 180 mm / s, 200 mm / s, 220 mm / s or 250 mm / s, or any other value within the range of 150-250 mm / s.

[0090] If the spraying speed is lower than 150mm / s, the coating will be too thick and prone to cracking. Furthermore, too low a spraying speed will increase the oxide content, thereby increasing the surface roughness of the coating and impairing thermal conductivity. If the spraying speed is higher than 250mm / s, the sprayed paste cannot be continuously and evenly deposited on the surface to be sprayed due to its high viscosity, resulting in faults and seriously affecting thermal conductivity.

[0091] In the present disclosure, the spraying distance may be 25-35 cm, such as 25 cm, 28 cm, 30 cm, 32 cm or 35 cm, etc., or any other value within the range of 25-35 cm.

[0092] By spraying at the above-mentioned spraying distance in combination with the above-mentioned spraying speed, it is possible to ensure sufficient flight time of the spray and control the oxidized substance within the range of 4-6 wt %.

[0093] If the spraying distance is greater than 35cm, the spray cannot be sprayed evenly and completely on the surface to be sprayed, and gaps will appear in the middle of the surface to be sprayed, resulting in a significant increase in thermal resistance. If the spraying distance is less than 25cm, the spraying area will be relatively concentrated, the spray layer will be too thick, and it will be brittle and crack easily.

[0094] As mentioned above, the spraying method provided by the present invention has low cost, and the prepared metal thermal conductive material coating has low surface roughness, high surface flatness, high uniformity of the material in the coating, and high thermal conductivity and thermal stability of the coating. In addition, the coating is also beneficial to improving the bonding force between the heat dissipation module and the heat source, thereby extending the service life of the corresponding product.

[0095] An embodiment of the present disclosure further provides an electronic component, which includes a heat dissipation module and a heat source, wherein the contact surface between the heat dissipation module and the heat source has the above-mentioned metal thermal conductive material coating.

[0096] The heat dissipation module may include, for example, heat dissipation fins, heat pipes or cold plates; the heat source may include, for example, a CPU, a GPU, an IGBT module or a large server chip.

[0097] The electronic component can dissipate heat quickly and has a long service life.

[0098] The present disclosure provides a liquid metal thermal conductive material. In, Bi, Sn, and Ga are prepared in specific ratios from the raw materials used to prepare the liquid metal thermal conductive material, resulting in good wettability and favorable thermal conductivity and heat dissipation effects. The liquid metal thermal conductive material is prepared into a metal thermal conductive material coating by spraying. This coating not only has low preparation costs and is easy to operate, but also has a smooth surface, high thermal conductivity, and low thermal resistance. Furthermore, the coating prepared in this manner exhibits good bonding strength with both the heat dissipation module and the heat source, thereby improving the bonding strength between the heat dissipation module and the heat source and extending the service life of the corresponding product.

[0099] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0100] Example 1

[0101] This embodiment provides an electronic component, which includes a heat dissipation module (CPU) and a heat source (heat dissipation fins), and a metal thermal conductive material coating is deposited between the contact surfaces of the heat dissipation module and the heat source.

[0102] The above-mentioned metal thermal conductive material coating is prepared by the following method:

[0103] S1: Indium particles, bismuth particles, tin particles, and gallium particles are used as raw materials. The purity of indium particles, bismuth particles, tin particles, and gallium particles is not less than 99.99%, and the (average) particle size of indium particles, bismuth particles, tin particles, and gallium particles is 5mm. The mass percentage ratio of indium, bismuth, tin, and gallium in the raw materials is 55.8:22:12.2:10 respectively. The raw materials are placed in a vacuum medium frequency melting furnace and evacuated to <1×10 -3 Pa, heated to 400 ° C and maintained for 2 h to obtain liquid metal thermal conductive material.

[0104] S2: Place the liquid metal thermal conductive material obtained in S1 into a vacuum heating stirrer and stir at 400 r / min at 100° C. for 30 min to mix all the raw materials evenly.

[0105] S3: Pour the evenly mixed liquid metal thermal conductive material obtained in S2 into a heated mechanical pump, which is connected to the heated spray head through a heating tube. The temperature of all components involved in the spraying is maintained at 120°C. Turn on the mechanical pump, pump the liquid metal into the spray tube for spraying, place the heat dissipation module to be sprayed under the nozzle, control the spraying distance at 30cm, spray the liquid metal on the desired area by setting the movement direction of the nozzle, and control the spraying speed to 200mm / s by adjusting the servo motor. After the spraying is completed, cool and form it, and the resulting coating thickness is 10μm; a physical photo of the coating is shown in Figure 1.

[0106] Example 2

[0107] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 60.3:25:9.7:5 respectively.

[0108] Example 3

[0109] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 65.3:22:12.2:0.5 respectively.

[0110] Example 4

[0111] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 50:40:5:5 respectively.

[0112] Example 5

[0113] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 70:20:8:2 respectively.

[0114] Example 6

[0115] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 60:20:15:5 respectively.

[0116] Example 7

[0117] The difference between this embodiment and embodiment 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 55:20:15:10 respectively.

[0118] Example 8

[0119] The difference between this embodiment and embodiment 1 is that the particle sizes of the indium particles, bismuth particles, tin particles, and gallium particles are all 3 mm.

[0120] Example 9

[0121] The difference between this embodiment and embodiment 1 is that the particle sizes of the indium particles, bismuth particles, tin particles, and gallium particles are all 8 mm.

[0122] Example 10

[0123] The difference between this embodiment and embodiment 1 is that the spraying speed is 150 mm / s.

[0124] Example 11

[0125] The difference between this embodiment and embodiment 1 is that the spraying speed is 250 mm / s.

[0126] Example 12

[0127] The difference between this embodiment and embodiment 1 is that the spraying distance is 25 cm.

[0128] Example 13

[0129] The difference between this embodiment and embodiment 1 is that the spraying distance is 35 cm.

[0130] Comparative Example 1

[0131] The difference between this comparative example and Example 1 is that the spraying distance is 40 cm.

[0132] Comparative Example 2

[0133] The difference between this comparative example and Example 1 is that the spraying distance is 20 cm.

[0134] Comparative Example 3

[0135] The difference between this comparative example and Example 1 is that the spraying speed is 300 mm / s.

[0136] Comparative Example 4

[0137] The difference between this comparative example and Example 1 is that the spraying speed is 100 mm / s.

[0138] Comparative Example 5

[0139] The difference between this comparative example and Example 1 is that the uniformly mixed liquid metal thermal conductive material obtained in S2 is placed in a crucible, the temperature is maintained at 120° C., and then the liquid metal thermal conductive material is soaked with a brush and coated on the surface of the heat dissipation module.

[0140] That is, the present disclosure does not use a spraying method to prepare the coating, and does not involve metal thermal conductive materials in a paste state.

[0141] Comparative Example 6

[0142] The difference between this comparative example and Example 1 is that the uniformly mixed liquid metal thermal conductive material obtained in S2 is first oxidized into a paste state and then coated.

[0143] Comparative Example 7

[0144] The difference between this comparative example and Example 1 is that the raw materials do not contain Ga, and the mass percentage ratios of indium, bismuth and tin are 65.8:22:12.2 respectively.

[0145] Comparative Example 8

[0146] The difference between this comparative example and Example 1 is that in the preparation raw materials, the content of Ga is 26.8 wt %, and the mass ratio of the remaining indium, bismuth, and tin is 60:8:5.2.

[0147] Comparative Example 9

[0148] The difference between this comparative example and Example 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 45:45:5:5 respectively.

[0149] Comparative Example 10

[0150] The difference between this comparative example and Example 1 is that in the preparation raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 75:15:2:8 respectively.

[0151] Comparative Example 11

[0152] The difference between this comparative example and Example 1 is that in the preparation of raw materials, the mass percentage ratios of indium, bismuth, tin and gallium are 45:10:30:15 respectively.

[0153] Comparative Example 12

[0154] The difference between this comparative example and Example 1 is that the particle sizes of the indium particles, bismuth particles, tin particles, and gallium particles in the preparation raw materials are all 1 mm.

[0155] Comparative Example 13

[0156] The difference between this comparative example and Example 1 is that the particle sizes of the indium particles, bismuth particles, tin particles, and gallium particles in the preparation raw materials are all 10 mm.

[0157] Test example

[0158] The oxide ratio, thermal conductivity, thermal resistance and surface smoothness of the coatings prepared in Examples 1-13 and Comparative Examples 1-13 were tested and observed, and the results are shown in Table 1.

[0159] The thermal conductivity is measured in accordance with ASTM D 5470, and the thermal resistance is measured in accordance with ASTM D 5470.

[0160] Table 1 Results

[0161] As can be seen from Table 1, compared to the comparative examples, each example can produce a coating with a higher thermal conductivity, lower thermal resistance, and a smoother surface, with Example 1 achieving the best results. Regarding Comparative Example 2, although its performance is similar to that of the examples, the coating obtained in this comparative example is not very user-friendly and is prone to brittle cracking.

[0162] By comparison, we can know that the ratio of raw materials and preparation conditions will have a direct impact on the performance of the coating. Only with appropriate raw material combination and appropriate preparation conditions can a coating with better performance be obtained.

[0163] In summary, the liquid metal thermal conductive material provided by the present invention can be prepared into a metal thermal conductive material coating by spraying, and its preparation cost is low. The resulting coating has excellent thermal conductivity, high thermal conductivity coefficient, low thermal resistance, good thermal stability, and is conducive to heat dissipation. In addition, the coating is also beneficial to improving the bonding force between the heat dissipation module and the heat source, and is easy to use and has a long service life.

[0164] The above are merely optional embodiments of the present disclosure and are not intended to limit the present disclosure. Those skilled in the art will readily appreciate that the present disclosure may be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure. Industrial Applicability

[0165] The present disclosure provides a liquid metal thermal conductive material. In, Bi, Sn and Ga in the raw materials for preparing the liquid metal thermal conductive material are prepared according to a specific ratio, which can make it have good wettability and be conducive to achieving good thermal conductivity and heat dissipation effects. The above-mentioned liquid metal thermal conductive material is prepared into a metal thermal conductive material coating by spraying. Not only is the preparation cost low and easy to operate, but the resulting coating surface is smooth and flat, the thermal conductivity coefficient is high, and the thermal resistance is small. In addition, the coating prepared in this way has good bonding strength with the heat dissipation module and the heat source, thereby improving the bonding strength between the heat dissipation module and the heat source, extending the service life of the corresponding product, and therefore has excellent practicality.

Claims

1. A liquid metal thermal conductive material, characterized in that: Calculated by mass percentage, the raw materials for preparing the liquid metal thermal conductive material include 0.5-10% Ga, 50-70% In, 20-40% Bi and 5-25% Sn.

2. The liquid metal thermal conductive material according to claim 1, characterized in that: The raw materials include 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi and 9.7-12.2% Sn.

3. The liquid metal thermal conductive material according to claim 1 or 2, characterized in that: The raw materials for preparing the liquid metal thermal conductive material are composed of 0.5-10% Ga, 50-70% In, 20-40% Bi and 5-25% Sn in terms of mass percentage; Optionally, the raw material consists of 0.5-10% Ga, 55.8-65.3% In, 22-25% Bi and 9.7-12.2% Sn.

4. The liquid metal thermal conductive material according to any one of claims 1 to 3, characterized in that: The gallium source for Ga, the indium source for In, the bismuth source for Bi, and the tin source for Sn are all independently powder materials with a particle size of 3-8 mm; Optionally, the particle size is an average particle size of the powder material.

5. The method for preparing the liquid metal thermal conductive material according to any one of claims 1 to 4, characterized in that: The following steps are involved: liquefying the prepared raw materials; Optionally, the liquefaction includes at least one of the following features: Feature 1: Liquefaction is carried out under vacuum conditions; Feature 2: Liquefaction temperature is 300-500℃; Feature 3: Liquefaction time is 1.5-2.5h.

6. The preparation method according to claim 5, wherein: Under the above vacuum conditions, the vacuum degree is ≤1×10 -3 Pa.

7. The preparation method according to claim 5 or 6, wherein: Also includes: Stirring and mixing the liquid raw materials to ensure that the raw materials are evenly mixed; Optionally, the stirring is performed at 100-120° C. and 350-450 r / min for 25-35 min.

8. A metal thermal conductive material coating, characterized in that: A liquid metal thermally conductive material comprising any one of claims 1 to 4; or A liquid metal thermal conductive material comprising a liquid metal thermal conductive material obtained by the preparation method according to any one of claims 5 to 7; Optionally, the thickness of the metal thermal conductive material coating is 5-20 μm.

9. A metal thermal conductive material coating, characterized in that: Formed by spraying the liquid metal thermal conductive material according to any one of claims 1 to 4; or The liquid metal thermal conductive material obtained by the preparation method according to any one of claims 5 to 7 is sprayed to form; Optionally, the thickness of the metal thermal conductive material coating is 5-20 μm.

10. The method for preparing a metal thermal conductive material coating according to claim 8 or 9, characterized in that: The method comprises the following steps: spraying the liquid metal thermal conductive material according to any one of claims 1 to 4 onto the surface of the material to be sprayed, and cooling the material to form the material; or The liquid metal thermal conductive material obtained by the preparation method according to any one of claims 5 to 7 is sprayed on the surface of the material to be sprayed, and cooled to form.

11. The preparation method according to claim 10, characterized in that: The liquid metal heat-conducting material is in a liquid state before being ejected from the nozzle; and the liquid metal heat-conducting material is in a paste state after being ejected from the nozzle; Optionally, the liquid metal thermally conductive material remains in a liquid state before being ejected from the nozzle; and the liquid metal thermally conductive material is in a viscous paste state after being ejected from the nozzle.

12. The preparation method according to claim 11, characterized in that: Before the liquid metal heat-conducting material is ejected from the nozzle, the component used to convey the liquid metal heat-conducting material is kept at no less than 120° C.; Optionally, the component is a feed pipe and / or a nozzle.

13. The preparation method according to claim 11, characterized in that: The metal thermal conductive material in the paste state contains In oxide, Sn oxide and Bi oxide at the same time; Optionally, the total amount of In oxide, Sn oxide and Bi oxide accounts for 4-6wt% of the metal thermal conductive material in paste state; Optionally, the oxide of In includes In2O3, the oxide of Sn includes SnO2, and the oxide of Bi includes Bi2O3.

14. The preparation method according to any one of claims 10 to 13, characterized in that: The spraying speed is 150-250 mm / s; and / or the spraying distance is 25-35 cm.

15. An electronic component, characterized in that: The electronic component comprises a heat dissipation module and a heat source, and the contact surface between the heat dissipation module and the heat source has the metal thermal conductive material coating according to claim 8 or 9.

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