Liquid metal composite modified metal mesh interface material and preparation method thereof

Abstract

The application discloses a liquid metal composite modified metal mesh interface material and a preparation method thereof. The surface of a metal mesh matrix is modified by a modifier, so that room temperature liquid metal is more easily wetted on the metal surface, a composite structure of room temperature liquid gold and the metal mesh is formed, and the liquid metal can still fill all the mesh holes under vertical placement. The thermal conductivity of the overall interface material can be further improved after the liquid metal is doped and modified. After the liquid gold completely wets the metal mesh, the product can further act on the attached interface surface, so that the liquid metal mesh is more easily wetted on other surfaces. The application can be widely applied to various high-power-density devices, improves the heat transmission speed, and reduces the working temperature of the devices.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of interface materials, and particularly relates to a liquid metal composite modified metal mesh interface material and a preparation method thereof. BACKGROUND

[0002] Generally, the heat dissipation of electronic components is achieved by conducting heat to the heat dissipation fins through surface contact with the heat sink. However, there are a large number of gaps at the interface of the contact surface, and the large thermal resistance of air hinders the further conduction of heat. Therefore, as an important material for filling heat sources and heat sinks, the interface material has been widely used in high-power-density electronic devices. The traditional interface material is generally a composite material with a polymer material such as silicone grease or resin as a matrix. Since the thermal conductivity of the matrix is generally less than 1 W / mk, even if the matrix is modified by a high-thermal-conductivity filler, the thermal conductivity of the interface material cannot be greatly improved.

[0003] With the in-depth study of liquid metal, its thermal conductivity 10-20 times higher than that of polymer materials and the characteristics of being liquid at room temperature have gradually been recognized by people. It has been widely used in various high-power-density heat-generating electronic devices, including CPUs and GPUs in the personal electronics field. However, its characteristics of easy flow, electrical conductivity, and difficulty in wetting various matrices limit its application market. Existing means can only reduce the leakage of liquid metal by protecting and controlling the coating weight of the coating surface, which is difficult to popularize. SUMMARY

[0004] The technical problem solved by the present application is to provide a liquid metal composite modified metal mesh interface material and a preparation method thereof. The flow of liquid metal is restricted by the mesh structure, the metal mesh is chemically modified by the modifier, and the wettability of the liquid metal to the metal mesh is also improved, which further restricts the flow of the liquid metal and makes it not easy to leak under high-frequency vibration.

[0005] To solve the above technical problems, one technical solution adopted by the present application is that the present application provides a liquid metal composite modified metal mesh interface material. The interface material is composed of modified room-temperature liquid metal and modified metal mesh.

[0006] Further, the modified room-temperature liquid metal is composed of room-temperature liquid metal and nanoparticles, and the volume ratio of the nanoparticles is 0.1-5%.

[0007] Further, the melting point of the room-temperature liquid metal is less than 30℃, and the room-temperature liquid metal is a metal element or a multi-metal.

[0008] Further, the metal element is elemental gallium.

[0009] The multi-metal is a multi-alloy formed by gallium and at least one of indium, zinc, bismuth, and tin.

[0010] The multi-element metal is, for example, a gallium-tin, gallium-indium, gallium-indium-zinc, gallium-indium-bismuth, gallium-indium-tin-zinc or gallium-indium-tin-bismuth alloy.

[0011] Further, the nanoparticles are one or more of silver powder, copper powder, silver-coated copper, silver-coated graphite, nickel-coated graphite, aluminum nitride, boron nitride, graphene, carbon nanotubes, diamond and silicon carbide.

[0012] Further, the nanoparticles have a size of 5-500 nm and a spherical shape.

[0013] Further, the modified metal mesh is made of nickel, copper, silver or stainless steel, has a thickness of 0.01-1 mm and a mesh number of 50-1000.

[0014] The thickness range of the modified metal mesh is to meet the heat dissipation requirement of a CPU, which is a high-power-density device, to ensure extremely low thermal resistance and accelerate heat conduction; the high mesh number is to limit the flow of liquid metal after wetting, and the greater the mesh number, the smaller the holes of the mesh; when the mesh number is less than 50, the holes are greater than 0.3 mm, and it is difficult for the liquid metal to completely fill all the holes; and when the mesh number is too large, the holes are too small, and the liquid metal is difficult to penetrate the metal mesh.

[0015] Further, the modified metal mesh is modified by a modifier; the modifier reduces the contact angle of the liquid metal to the metal mesh and improves the adhesion of the liquid metal to the metal mesh.

[0016] The modifier is composed of an acidic solution, a surfactant and deionized water, and according to the mass percentage, the acidic solution is 1-5%, the surfactant is 5-10%, and the rest is water solution.

[0017] The acidic solution removes impurities and oxides and reduces the surface energy of the metal mesh, and then the surfactant forms a liquid metal wetting material on the surface of the metal mesh to promote the wetting of the modified liquid metal.

[0018] Further, the acidic solution is at least one of nitric acid, hydrochloric acid and sulfuric acid.

[0019] The surfactant is at least one of copper chloride, potassium chloride, silver chloride, copper sulfide and silver sulfide.

[0020] The modification method is different from conventional modification methods and does not roughen the surface. The specific mechanism is as follows: after the metal mesh is soaked in the modifier and dried, a chloride (such as copper chloride, the type of which is determined by the type of the selected surfactant) can be formed on the surface of the metal mesh wire. After the addition of liquid metal (such as gallium-based metal), the chloride can absorb moisture in the air to form an acidic water film on the surface of the substrate, which promotes the reaction of the gallium-based alloy with copper to form gallide (such as CuGa2). The wettability of liquid metal to CuGa2 is very good, so the contact angle is very low, thereby improving the adhesion of the liquid metal to the metal mesh.

[0021] The application also provides a preparation method of the liquid metal composite modified metal mesh interface material.

[0022] S1: the metal mesh and the nanoparticles are respectively subjected to alcohol ultrasonic removal of oil stains or impurities on the surface, then 1-10 mol / L hydrochloric acid is used for soaking for 10-1000s, and deionized water is used for washing residual hydrochloric acid;

[0023] S2: the nanoparticles are mixed into the room temperature liquid metal by ball milling to obtain modified room temperature liquid metal;

[0024] The mixing conditions are as follows: protection under a helium atmosphere, a rotation speed of 1000-5000 r / min, and a duration of 30-90 min.

[0025] S3: the metal mesh is treated with a modifier for 10-1000s, and then deionized water is used for washing residual modifier;

[0026] S4: the modified metal mesh is soaked in the modified room temperature liquid metal for 5-15 min and then taken out.

[0027] The application has the following beneficial effects:

[0028] The application limits the flow of liquid metal through the mesh structure and chemically modifies the metal mesh using a modifier, which changes the microstructure and surface energy of the metal mesh surface and improves the wettability of the liquid metal to the metal mesh. The flow of liquid metal can be effectively limited so that it is not easy to leak under high-frequency vibration.

[0029] In addition, after the modification of the metal mesh, when the surface particles form intermetallic compounds with the liquid metal (such as Ga-based alloy), chlorides (such as silver chloride, the type of which is determined by the type of surfactant selected) are formed, and the chlorides form corrosion points on the attached surface, removing the surface oxides, making the liquid metal more easily react with the attached surface to form the corresponding intermetallic compound, thereby better wetting, but the content of chlorides is not much, so it will not cause too much corrosion; that is, when the metal mesh is modified, the product can also improve the wettability of other interfaces, making it easier to adhere to high-power density heat generating devices as a whole.

[0030] At the same time, the addition of nanoparticles can further improve the overall thermal conductivity of the interfacial material, making it have a high thermal conductivity of more than 100 W / mk.

[0031] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and can be implemented in accordance with the content of the specification, the following will be described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of a liquid metal composite modified metal mesh interfacial material structure in embodiment 1 of the present application;

[0033] Marked as follows: 1, modified room temperature liquid metal; 2, modified metal mesh; 3, nanoparticles. DETAILED DESCRIPTION

[0034] The specific embodiments of the present application will be described below through specific specific embodiments, and those skilled in the art can easily understand the advantages and effects of the present application from the content disclosed in the specification. The present application can also be implemented in other different ways, that is, different modifications and changes can be made without departing from the scope disclosed in the present application.

[0035] Embodiment: a liquid metal composite modified metal mesh interfacial material, as shown in Figure 1 The interfacial material is obtained by compounding modified room temperature liquid metal 1 and modified metal mesh 2.

[0036] The modified room temperature liquid metal is composed of room temperature liquid metal and nanoparticles 3, and the volume ratio of the nanoparticles is 0.1-5%.

[0037] The melting point of the room temperature liquid metal is less than 30℃; the room temperature liquid metal is a metal element or a multi-metal.

[0038] The metal element is elemental gallium;

[0039] The multi-metal is a multi-alloy formed by gallium and at least one of indium, zinc, bismuth and tin metal.

[0040] The multi-element metal is, for example, a gallium-tin, gallium-indium, gallium-indium-zinc, gallium-indium-bismuth, gallium-indium-tin-zinc or gallium-indium-tin-bismuth alloy.

[0041] The nanoparticles are one or more of silver powder, copper powder, silver-coated copper, silver-coated graphite, nickel-coated graphite, aluminum nitride, boron nitride, graphene, carbon nanotubes, diamond and silicon carbide.

[0042] The size of the nanoparticles is 5-500 nm, and the particle shape is spherical.

[0043] The modified metal mesh is made of nickel, copper, silver or stainless steel, has a thickness of 0.01-1 mm and a mesh number of 50-1000.

[0044] The modified metal mesh is modified by a modifier; the modifier reduces the contact angle of the liquid metal on the metal mesh and improves the adhesion of the liquid metal to the metal mesh

[0045] The modifier is composed of an acidic solution, a surfactant and deionized water, and according to the mass percentage, the acidic solution is 1-5%, the surfactant is 5-10%, and the rest is water solution.

[0046] For example, the formula of the modifier is: the modifier is composed of an acidic solution, a surfactant and deionized water, and according to the mass percentage, the acidic solution is 1%, the surfactant is 10%, and the rest is water solution.

[0047] Another formula of the modifier is: the modifier is composed of an acidic solution, a surfactant and deionized water, and according to the mass percentage, the acidic solution is 5%, the surfactant is 5%, and the rest is water solution.

[0048] Still another formula of the modifier is: the modifier is composed of an acidic solution, a surfactant and deionized water, and according to the mass percentage, the acidic solution is 2%, the surfactant is 8%, and the rest is water solution.

[0049] The acidic solution is at least one of nitric acid, hydrochloric acid and sulfuric acid.

[0050] The surfactant is at least one of copper chloride, potassium chloride, silver chloride, copper sulfide and silver sulfide.

[0051] Example 1:

[0052] S1: A 0.15 mm thick copper metal mesh and 50 nm Cu nanoparticles are treated by alcohol ultrasonic to remove possible oil stains or impurities on the surface, then soaked in 1 mol / L hydrochloric acid for 60 s, and then rinsed with deionized water to remove residual hydrochloric acid.

[0053] S2: 1% nanoparticles by volume were mixed into 68Ga by ball milling 21.5 In 10.5 In Sn liquid metal, the rotation speed was 2000 r / min, lasting for 30 min, under the protection of helium atmosphere

[0054] S3: The metal mesh was treated with a modifier of 1% acidic solution, 8% surfactant and the rest of water solution by mass percentage for 200 s, and then washed with deionized water to remove the residual modifier.

[0055] S4: The modified metal mesh was taken out after being immersed in the modified room temperature liquid metal for 10 min.

[0056] Example 2:

[0057] S1: The 0.15 mm thick copper metal mesh was treated with 50 nm silver particles by alcohol ultrasonic to remove possible oil stains or impurities on the surface, and then soaked in 1 mol / L hydrochloric acid for 60 s, and then washed with deionized water to remove the residual hydrochloric acid.

[0058] S2: 1% nanoparticles by volume were mixed into 68Ga by ball milling 21.5 In 10.5 In Sn liquid metal, the rotation speed was 2000 r / min, lasting for 30 min, under the protection of helium atmosphere

[0059] S3: The metal mesh was treated with a modifier of 1% acidic solution, 8% surfactant and the rest of water solution by mass percentage for 200 s, and then washed with deionized water to remove the residual modifier.

[0060] S4: The modified metal mesh was taken out after being immersed in the modified room temperature liquid metal for 10 min.

[0061] Example 3:

[0062] The difference between this example and Example 1 is that the thickness of the metal mesh in this example is 0.5 mm.

[0063] In the above examples, each parameter is only taken as an example for experiment, and other technical solutions within the range also belong to the protection scope of the present application, and the examples are not listed one by one.

[0064] Comparative Example 1:

[0065] S1: The 0.15 mm thick copper metal mesh was treated with 50 nm silver particles by alcohol ultrasonic to remove possible oil stains or impurities on the surface, and then soaked in 1 mol / L hydrochloric acid for 60 s, and then washed with deionized water to remove the residual hydrochloric acid.

[0066] S2: 1% nanoparticles by volume were mixed into 68Ga by ball milling21.5 In 10.5 Sn liquid metal, the rotation speed is 2000r / min, lasting for 30min, under the protection of helium atmosphere.

[0067] S3: the metal mesh is soaked in the modified room temperature liquid metal for 10min and then taken out.

[0068] Comparative Example 2:

[0069] S1: the 0.15mm thick copper metal mesh is treated by alcohol ultrasonic to remove possible oil stains or impurities on the surface, then soaked in 1mol / L hydrochloric acid for 60s, and then rinsed with deionized water to remove residual hydrochloric acid;

[0070] S2: the metal mesh is treated with a modifier solution containing 1% acid, 8% surfactant and the rest water for 200s, and then rinsed with deionized water to remove residual modifier.

[0071] S3: the modified metal mesh is soaked in room temperature liquid metal for 10min and then taken out.

[0072] Thermal conductivity measurement method: according to standard ASTM D5470-06 to test the thermal conductivity.

[0073] Experimental data table of examples and comparative examples

[0074] Item Face weight (g / cm 2 ) Overall thickness (mm) Coating thermal conductivity (W / mK) Example 1 0.35 0.20 154.87 Example 2 0.38 0.20 159.28 Example 3 0.41 0.51 148.94 Comparative Example 1 0.13 0.18 88.19 Comparative Example 2 0.29 0.19 116.37

[0075] Note: 1, the surface gram weight refers to the weight per unit area of the modified metal mesh after being soaked in the modified room temperature liquid metal.

[0076] 2, the mesh number of the metal mesh in the examples and comparative examples is the same.

[0077] The thickness and mesh number of the metal mesh in examples 1, 2 and comparative examples are the same. It can be seen from the above experimental data that the types of nanoparticles in examples 1 and 2 are different, and the thermal conductivities in examples 1 and 2 are both high, reaching more than 150 W / mK; in example 3, the thickness of the metal mesh is increased, and the surface gram weight is the heaviest, resulting in a larger thermal resistance in the test process, so the thermal conductivity is slightly decreased.

[0078] In comparative example 1, the metal mesh is not modified, so it is difficult to adsorb liquid metal and cannot fully wet the metal mesh and the interface, so the surface gram weight is the lowest and the thermal conductivity is relatively low. In comparative example 2, the liquid metal is not modified, so the overall thermal conduction channel is reduced, so the thermal conductivity is relatively low.

[0079] The above merely illustrates the embodiments of the present application, and is not intended to limit the patent scope of the present application, and any equivalent structure made according to the present application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A liquid metal composite modified metal grid interface material, characterized in that: The interface material is obtained by modifying a room-temperature liquid metal and a modified metal mesh; The modified room-temperature liquid metal is composed of a room-temperature liquid metal and nanoparticles, and the volume ratio of the nanoparticles is 0.1-5%; The size of the nanoparticles is 5-500 nm, and the particle shape is spherical. The nanoparticles are one or more of silver powder, copper powder, silver-coated copper, silver-coated graphite, nickel-coated graphite, aluminum nitride, boron nitride, graphene, carbon nanotubes, diamond, and silicon carbide. The modified metal mesh is modified by a modifier. The modifier is composed of an acidic solution, a surfactant, and deionized water, and according to the mass percentage, the acidic solution is 1-5%, the surfactant is 5-10%, and the rest is aqueous solution. The acidic solution is at least one of nitric acid, hydrochloric acid, and sulfuric acid. The surfactant is at least one of copper chloride, potassium chloride, silver chloride, copper sulfide, and silver sulfide. The preparation method of the liquid metal composite modified metal mesh interface material comprises the following steps: S1: The metal mesh and the nanoparticles are respectively treated by alcohol ultrasonic to remove the oil stains or impurities on the surface, then soaked in 1-10 mol / L hydrochloric acid for 10-1000 s, and then rinsed with deionized water to remove residual hydrochloric acid; S2: The nanoparticles are mixed into the room-temperature liquid metal by ball milling to obtain the modified room-temperature liquid metal; The mixing conditions are: protected in a helium atmosphere, rotation speed is 1000-5000 r / min, and the duration is 30-90 min; S3: The metal mesh is treated with the modifier for 10-1000 s, and then washed with deionized water to remove residual modifier; S4: The modified metal mesh is soaked in the modified room-temperature liquid metal for 5-15 min and then taken out.

2. The liquid metal composite modified metal grid interface material of claim 1, wherein: The melting point of the room-temperature liquid metal is less than 30℃, and the room-temperature liquid metal is a metal element or a multi-metal.

3. The liquid metal composite modified metal grid interface material of claim 2, wherein: The metal element is elemental gallium. The multi-metal is a multi-alloy formed by gallium and at least one of indium, zinc, bismuth, and tin.

4. The liquid metal composite modified metal grid interface material of claim 1, wherein: The material of the modified metal mesh is nickel, copper, silver, or stainless steel, the thickness is 0.01-1 mm, and the mesh number is 50-1000.

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