A gallium-based liquid metal paste for thermal interface material and a method of preparing the same

Abstract

The application discloses a gallium-based liquid metal paste for a thermal interface material and a preparation method thereof. The preparation raw material of the gallium-based liquid metal paste for the thermal interface material comprises liquid metal and heat-conducting reinforced particles. The gallium-based liquid metal paste prepared by the application has good heat conductivity, good adhesion and good wettability, avoids the risk of leakage caused by the too high flowability of the liquid metal, is more convenient to fill, and can play an important role in the heat conduction of electronic chips in the fields of computers, satellites, rocket propellers and lasers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermal interface materials, and the classification number is C22C29 / 00, and in particular relates to a gallium-based liquid metal paste for a thermal interface material and a preparation method thereof. BACKGROUND

[0002] In recent years, chip miniaturization and integration have become the development trend of electronic devices. However, in electronic devices, due to surface unevenness, there are a large number of air filling the gap between the CPU and the heat sink. Air is a poor conductor of heat, and its thermal conductivity is only 0.0267 W m -1 K -1 at 20℃, which produces a large contact thermal resistance, thereby affecting the heat conduction of the entire device. The thermal interface material is mainly composed of a high-thermal-conductivity material with good elasticity, which is placed between the CPU and the heat sink and can fill the gap under a certain pressure to achieve efficient heat dissipation. In this case, a gallium-based liquid metal material with both liquid and metallic properties has attracted a lot of attention because the liquid can exclude air and the metal has a high thermal conductivity, thereby being able to build a good heat conduction path, thus having a broad application prospect as a thermal interface material.

[0003] Although the pure gallium-based liquid metal has many good properties, it still has some defects. On the one hand, the high flowability of the pure gallium-based liquid metal makes it have a risk of leakage when in use, affecting the stability and reliability of the electronic device; on the other hand, the pure gallium-based liquid metal has a super-high surface tension and poor wettability, which makes it difficult to adhere to the surface of the substrate.

[0004] Chinese patent CN108777254A discloses a metal thermal interface material and a preparation method thereof, and the metal thermal interface material prepared thereby can wet the solid interface and avoid flow overflow to pollute the electronic components and even cause short circuit, but its thermal conductivity needs to be improved. SUMMARY

[0005] To solve the above problems, a first aspect of the application provides a gallium-based liquid metal paste for a thermal interface material, and the preparation raw materials of the gallium-based liquid metal paste for a thermal interface material comprise: a liquid metal and a thermal conductivity enhancing particle.

[0006] Preferably, the raw material of the liquid metal is selected from at least one of gallium, indium, bismuth, tin, zinc, aluminum and copper.

[0007] Preferably, the raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 65-70%:20-23%:8-12%.

[0008] Further preferably, the raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%.

[0009] Preferably, the heat-conducting reinforcing particles include at least one of copper powder, silicon carbide powder, silver powder, aluminum oxide powder and antimony powder.

[0010] Further preferably, the heat-conducting reinforcing particles are antimony powder.

[0011] Preferably, the mass fraction of the heat-conducting reinforcing particles is 1-10%, and the average particle size is 10-30 μm.

[0012] Further preferably, the mass fraction of the heat-conducting reinforcing particles is 1-5%, and the average particle size is 15-25 μm.

[0013] Further preferably, the mass fraction of the heat-conducting reinforcing particles is 2%, and the average particle size is 20 μm.

[0014] The second aspect of the present application provides a preparation method of a gallium-based liquid metal paste for a thermal interface material, and the steps are as follows:

[0015] S1: Preparation of a gallium-based liquid metal;

[0016] According to the proportion, gallium metal is placed in a sealed flask and placed in a water bath at 50-60°C. After heating in a constant temperature state in air, liquid gallium is obtained. Then, according to the proportion, indium and tin metals are added, and after constant temperature stirring at a temperature of 50-60°C, a gallium-based liquid metal is obtained.

[0017] S2: Preparation of a gallium-based liquid metal paste;

[0018] 8-10 mL of the gallium-based liquid metal and the heat-conducting reinforcing particles are mixed and stirred in air for 50-70 min at a stirring speed of 400-600 rpm / min. Then, a three-roll mixer is used to grind the semi-finished product to a particle size of 5-10 mm in air. After that, the semi-finished product is pre-stirred for 0.5-2 min at a rotation speed of 700-900 rpm / min in a vacuum condition using a vacuum stirrer. Then, the rotation speed is adjusted to 1500-2500 rpm / min, and the stirring is performed twice, with the stirring time being 13-16 min and 9-12 min, respectively. After the stirring is completed, a gallium-based liquid metal paste is obtained.

[0019] Further preferably, the melting point of the gallium-based liquid metal in step (1) is 8-12°C.

[0020] Further preferably, the melting point of the gallium-based liquid metal in step (1) is 10°C.

[0021] Preferably, the heating time of the metallic gallium in step (1) is 20-30 min. The applicant has found that, in step (1), the infiltration and adhesion of the heat-conductive material can be improved by heating in air for 20-30 min under constant temperature, presumably because the metallic gallium with a mass percentage of 65-70% is micro-oxidized to form gallium oxide with a content of less than 1%, thereby improving the infiltration and adhesion of the liquid metal. Then, in order to avoid further increase of the content of gallium oxide, the gallium-based liquid metal is synthesized by heating and stirring for 2-4 h under oxygen-free condition. However, the applicant has found that the heat-conducting performance of the metal paste is reduced to some extent. On this basis, the application adds 1%-5% of antimony powder with an average particle size of 10-30 μm, which not only further improves the infiltration and adhesion of the metal paste, but also enhances the thermal conductivity of the metal paste, presumably because the antimony powder particles form a continuous heat-conducting path, and at the same time, the interaction between different metal atoms is enhanced, and the surface tension of the liquid metal is reduced, thereby improving the thermal conductivity of the metal paste while ensuring the infiltration and adhesion of the metal paste.

[0022] Further preferably, the heating time of the metallic gallium in step (1) is 25 min.

[0023] Preferably, in step (1), after the addition of indium and tin metals, heating and stirring are performed under oxygen-free condition for 2-4 h.

[0024] Further preferably, in step (1), after the addition of indium and tin metals, heating and stirring are performed under oxygen-free condition for 3 h.

[0025] Preferably, the vacuum degree in step (2) is 0.1-0.3 KPa.

[0026] Further preferably, the vacuum degree in step (2) is 0.2 KPa.

[0027] Preferably, the pre-stirring time in step (2) is 0.5-2 min.

[0028] Further preferably, the pre-stirring time in step (2) is 1 min.

[0029] Beneficial Effects: By heating gallium-based liquid metal in air for 20-30 minutes, the present invention significantly improves the wettability and adhesion between the gallium-based liquid metal and various interfaces, meeting the requirements of thermal interface materials. The present invention also adds 1%-5% by mass of antimony powder with an average particle size of 10-30 μm, which reduces the surface tension of the liquid metal and forms a continuous thermal conductivity path, further improving the wettability and adhesion of the metal paste. It also enhances the thermal conductivity of the metal paste, avoiding the risk of leakage due to excessive liquid metal fluidity, making filling more convenient, and significantly reducing interfacial thermal resistance. This is expected to play a significant role in the thermal conduction of electronic chips in fields such as computers, satellites, rocket thrusters, and lasers. Example

[0030] Example 1

[0031] A gallium-based liquid metal paste for a thermal interface material. The raw materials for preparing the gallium-based liquid metal paste for a thermal interface material include liquid metal and thermal conductivity enhancing particles.

[0032] The raw materials of the liquid metal are gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%. The melting point of the liquid metal is 10°C.

[0033] The thermal conductivity enhancing particles are antimony powders with an average particle size of 20 μm, purchased from Aladdin, and having a CAS number of 7440-36-0.

[0034] The mass fraction of the thermal conductivity enhancing particles is 2%.

[0035] This embodiment also includes a method for preparing a gallium-based liquid metal paste for a thermal interface material, comprising the following steps:

[0036] S1: Preparation of gallium-based liquid metal;

[0037] Metal gallium is placed in a sealed flask according to the ratio and placed in a water bath at 55°C. Liquid gallium is obtained after heating in air at a constant temperature for 25 minutes. After that, indium and tin metals are added according to the ratio. Gallium-based liquid metal is obtained after constant temperature stirring for 3 hours at a temperature of 55°C and in an oxygen-free condition.

[0038] S2: Preparation of gallium-based liquid metal paste;

[0039] 9mL of gallium-based liquid metal and heat-conducting reinforcing particles are mixed and stirred in air for 60min at a stirring speed of 500rpm / min, and then ground in a three-roll mixer in air to a particle size of 8mm to obtain a semi-finished product, and then the semi-finished product is pre-stirred in a vacuum condition using a vacuum stirrer at a vacuum degree of 0.2KPa at a rotating speed of 800rpm / min for 1min, and then the rotating speed is adjusted to 2000rpm / min, and stirred twice at a stirring time of 15min and 10min respectively, and then a gallium-based liquid metal paste is obtained after the stirring is completed.

[0040] Example 2

[0041] A gallium-based liquid metal paste for a thermal interface material, raw materials for preparing the gallium-based liquid metal paste for a thermal interface material comprising: liquid metal and heat-conducting reinforcing particles.

[0042] The raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%, and the melting point of the liquid metal is 10℃.

[0043] The heat-conducting reinforcing particles are antimony powder with an average particle size of 20μm, which is purchased from Aldrich and has a CAS number of 7440-36-0.

[0044] The mass fraction of the heat-conducting reinforcing particles is 5%.

[0045] The embodiment also includes a preparation method of a gallium-based liquid metal paste for a thermal interface material, and the steps are as follows:

[0046] S1: preparation of a gallium-based liquid metal;

[0047] According to the proportion, gallium metal is placed in a sealed flask and placed in a water bath at 55℃, and after heating in air for 30min under constant temperature, liquid gallium is obtained, and then indium and tin metals are added according to the proportion, and after constant temperature stirring under oxygen-free conditions at a temperature of 55℃ for 3h, a gallium-based liquid metal is obtained.

[0048] S2: preparation of a gallium-based liquid metal paste;

[0049] 9mL of gallium-based liquid metal and heat-conducting reinforcing particles are mixed and stirred in air for 60min at a stirring speed of 500rpm / min, and then ground in a three-roll mixer in air to a particle size of 8mm to obtain a semi-finished product, and then the semi-finished product is pre-stirred in a vacuum condition using a vacuum stirrer at a vacuum degree of 0.2KPa at a rotating speed of 800rpm / min for 1min, and then the rotating speed is adjusted to 2000rpm / min, and stirred twice at a stirring time of 15min and 10min, respectively, to obtain a gallium-based liquid metal paste.

[0050] Example 3

[0051] A gallium-based liquid metal paste for a thermal interface material, raw materials for preparing the gallium-based liquid metal paste for a thermal interface material comprising: liquid metal and heat-conducting reinforcing particles.

[0052] The raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%, and the melting point of the liquid metal is 10℃.

[0053] The heat-conducting reinforcing particles are antimony powder with an average particle size of 20μm, which is purchased from Aldrich and has a CAS number of 7440-36-0.

[0054] The mass fraction of the heat-conducting reinforcing particles is 1%.

[0055] The embodiment also includes a preparation method of a gallium-based liquid metal paste for a thermal interface material, and the steps are as follows:

[0056] S1: preparation of a gallium-based liquid metal;

[0057] According to the proportion, gallium metal is placed in a sealed flask and placed in a water bath at 55℃, and after heating in air for 20min under constant temperature, liquid gallium is obtained, and then indium and tin metals are added according to the proportion, and after constant temperature stirring for 3h under the condition of 55℃ and oxygen-free, a gallium-based liquid metal is obtained.

[0058] S2: preparation of a gallium-based liquid metal paste;

[0059] 9mL of gallium-based liquid metal and heat-conducting reinforcing particles are mixed and stirred in air for 60 min at a stirring speed of 500 rpm / min, and then ground in a three-roller mixer in air to a particle size of 8 mm to obtain a semi-finished product. Then, the semi-finished product is pre-stirred in a vacuum for 1 min at a rotation speed of 800 rpm / min, and then stirred twice at a rotation speed of 2000 rpm / min, with the stirring time being 15 min and 10 min, respectively. After the stirring is completed, a gallium-based liquid metal paste is obtained.

[0060] Comparative Example 1

[0061] A gallium-based liquid metal paste for a thermal interface material, raw materials for preparing the gallium-based liquid metal paste for the thermal interface material comprising: liquid metal and heat-conducting reinforcing particles.

[0062] The raw material of the liquid metal is gallium, indium and tin, with the mass percentage being 68.5%:21.5%:10%, and the melting point of the liquid metal being 10℃.

[0063] The heat-conducting reinforcing particles are antimony powder, with an average particle size of 50μm, which is purchased from Hunan Fujia Technology Co., Ltd.

[0064] The mass fraction of the heat-conducting reinforcing particles is 6%.

[0065] The embodiment also includes a preparation method of a gallium-based liquid metal paste for a thermal interface material, with the steps being as follows:

[0066] S1: Preparation of a gallium-based liquid metal;

[0067] According to the proportion, gallium metal is placed in a sealed flask and placed in a water bath at 55℃. After being heated in air for 25 min under constant temperature, liquid gallium is obtained. Then, according to the proportion, indium and tin metals are added, and after being stirred for 3 h under constant temperature at a temperature of 55℃ and in an oxygen-free condition, a gallium-based liquid metal is obtained.

[0068] S2: Preparation of a gallium-based liquid metal paste;

[0069] 9mL of gallium-based liquid metal and heat-conducting reinforcing particles are mixed and stirred in air for 60 min at a stirring speed of 500 rpm / min, and then ground in a three-roller mixer in air to a particle size of 8 mm to obtain a semi-finished product. Then, the semi-finished product is pre-stirred in a vacuum for 1 min at a rotation speed of 800 rpm / min, and then stirred twice at a rotation speed of 2000 rpm / min, with the stirring time being 15 min and 10 min, respectively. After the stirring is completed, a gallium-based liquid metal paste is obtained.

[0070] Comparative Example 2

[0071] A gallium-based liquid metal paste for thermal interface material, raw materials for preparing the gallium-based liquid metal paste for thermal interface material include: liquid metal and heat-conducting reinforcing particles.

[0072] The raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%. The melting point of the liquid metal is 10℃.

[0073] The heat-conducting reinforcing particles are antimony powder, the average particle size of which is 20μm, and it is purchased from Aldrich, and the CAS number is 7440-36-0.

[0074] The mass fraction of the heat-conducting reinforcing particles is 2%.

[0075] The embodiment also includes a preparation method of a gallium-based liquid metal paste for thermal interface material, and the steps are as follows:

[0076] S1: Preparation of gallium-based liquid metal;

[0077] According to the proportion, the metal gallium is placed in a sealed flask and placed in a water bath at 55℃. After heating in air for 25min under constant temperature, liquid gallium is obtained. Then, according to the proportion, indium and tin metals are added, and after constant temperature stirring in air for 1h at a temperature of 55℃, the gallium-based liquid metal is obtained.

[0078] S2: Preparation of gallium-based liquid metal paste;

[0079] 9mL of gallium-based liquid metal and heat-conducting reinforcing particles are mixed and stirred in air for 60min at a stirring speed of 500rpm / min. Then, the semi-finished product is obtained by grinding in air to a particle size of 8mm using a three-roll mixer. Then, the semi-finished product is pre-stirred for 1min at a speed of 800rpm / min under vacuum conditions using a vacuum stirrer, and then the speed is adjusted to 2000rpm / min. Stirring is carried out twice, and the stirring time of each time is 15min and 10min, respectively. After stirring is completed, the gallium-based liquid metal paste is obtained.

[0080] Comparative Example 3

[0081] A gallium-based liquid metal paste for thermal interface material, raw materials for preparing the gallium-based liquid metal paste for thermal interface material include: liquid metal and heat-conducting reinforcing particles.

[0082] The raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 68.5%:21.5%:10%, and the melting point of the liquid metal is 10℃.

[0083] The heat-conducting reinforcing particles are antimony powder with an average particle size of 20μm, which is purchased from Aldrich and has a CAS number of 7440-36-0.

[0084] The mass fraction of the heat-conducting reinforcing particles is 2%.

[0085] The embodiment also includes a preparation method of a gallium-based liquid metal paste for a thermal interface material, and the steps are as follows:

[0086] S1: Preparation of a gallium-based liquid metal;

[0087] According to the ratio, place the metal gallium in a sealed flask and place it in a water bath at 55℃. After heating in air for 10min under constant temperature, liquid gallium is obtained. Then, according to the ratio, add indium and tin metals, and after constant temperature stirring for 5h under the condition of 55℃ and oxygen-free, a gallium-based liquid metal is obtained.

[0088] S2: Preparation of a gallium-based liquid metal paste;

[0089] Mix and stir 9mL of gallium-based liquid metal and heat-conducting reinforcing particles in air for 60min at a stirring speed of 500rpm / min. Then, use a three-roll mixer to grind the semi-finished product to a particle size of 8mm in air. After that, use a vacuum stirrer under vacuum conditions, with a vacuum degree of 0.2KPa and a rotation speed of 800rpm / min, pre-stir for 1min, then adjust the rotation speed to 2000rpm / min, stir twice, with stirring time of 15min and 10min respectively. After stirring, a gallium-based liquid metal paste is obtained.

[0090] Performance Evaluation

[0091] (1) Measurement of thermal conductivity: The thermal conductivity of Examples 1-3 and Comparative Examples 1-3 was measured, and the test standard was ASTM D 5470. The test data is shown in Table 1.

[0092] Table 1

[0093]

Claims

1. A gallium-based liquid metal paste for thermal interface materials, characterized in that, The preparation raw material of the gallium-based liquid metal paste for thermal interface material comprises liquid metal and heat-conducting reinforcing particles; The raw material of the liquid metal is gallium, indium and tin, and the mass percentage of the three is 65-70%:20-23%:8-12%; the heat-conducting reinforcing particles are antimony powder; The mass fraction of the heat-conducting reinforcing particles is 2%, and the average particle size is 20μm.

2. A method of producing a gallium-based liquid metal paste for thermal interface materials according to claim 1, characterized in that, The steps are as follows: S1: preparation of gallium-based liquid metal; According to the proportion, the metal gallium is placed in a sealed flask and is placed in a water bath pot at 50-60℃, and after heating in a constant temperature state in air, liquid gallium is obtained, then according to the proportion, indium and tin metals are added, and after constant temperature stirring at a temperature of 50-60℃, the gallium-based liquid metal is obtained; S2: preparation of gallium-based liquid metal paste; After the antimony powder is added to the gallium-based liquid metal, stirring and grinding are performed, then under vacuum conditions, pre-stirring is performed once, and after stirring twice, the gallium-based liquid metal paste is obtained. In the step (1), the heating time of the metal gallium is 20-30min.

3. The method of claim 2, wherein the gallium-based liquid metal paste for thermal interface materials is prepared by the steps of: In the step (1), after the indium and tin metals are added, heating and stirring are performed under oxygen-free conditions for 2-4h.

4. The method of claim 2, wherein the gallium-based liquid metal paste for thermal interface material is prepared by the steps of: In the step (2), the vacuum degree is 0.1-0.3KPa.

5. The method of claim 2, wherein the gallium-based liquid metal paste for thermal interface material is prepared by the steps of: In the step (2), the pre-stirring time is 0.5-2min.

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