阅读说明：本技术 一种液态金属导热膏及其制备方法和应用 (Liquid metal heat-conducting paste and preparation method and application thereof ) 是由 关志祥 郑立聪 谢开旺 李正荣 盛磊 刘静 于 2019-10-12 设计创作，主要内容包括：本发明属于液态金属热界面材料技术领域,具体涉及一种液态金属导热膏及其制备方法和应用。所述液态金属导热膏,包括：液态金属、导热增强颗粒及粘度调节剂；其中,所述导热增强颗粒选自铜粉、碳化硅粉、银粉或氧化铝粉中的一种或多种；所述粘度调节剂选自气相二氧化硅和/或不饱和聚羧酸胺盐。本发明通过增加经过表面处理过的导热增强颗粒以及粘度调节剂来提高液态金属导热膏的导热性能,同时使得液态金属导热膏粘度增加,避免液态金属的泄露,从而保证在使用过程中导热膏更加稳定、安全。(The invention belongs to the technical field of liquid metal thermal interface materials, and particularly relates to liquid metal heat-conducting paste and a preparation method and application thereof. The liquid metal heat conducting paste comprises: liquid metal, heat conduction enhancing particles and a viscosity regulator; wherein the heat conduction enhanced particles are selected from one or more of copper powder, silicon carbide powder, silver powder or alumina powder; the viscosity modifier is selected from fumed silica and/or an unsaturated polycarboxylic amine salt. The invention improves the heat conduction performance of the liquid metal heat conduction paste by adding the heat conduction enhancement particles and the viscosity regulator which are subjected to surface treatment, increases the viscosity of the liquid metal heat conduction paste, and avoids leakage of liquid metal, thereby ensuring that the heat conduction paste is more stable and safer in the use process.)

1. A liquid metal thermal paste, comprising: liquid metal, heat conduction enhancing particles and a viscosity regulator; wherein the content of the first and second substances,

the heat conduction enhanced particles are selected from one or more of copper powder, silicon carbide powder, silver powder or alumina powder;

the viscosity modifier is selected from fumed silica and/or an unsaturated polycarboxylic amine salt.

2. The liquid metal thermal paste according to claim 1, wherein the mass fraction of the thermal conductivity enhancement particles is 1-50%, preferably 5-30%;

and/or the particle size of the heat conduction enhancing particles is 1-100 μm.

3. The liquid metal thermal paste according to claim 1 or 2, wherein the mass fraction of the viscosity modifier is 0.1% -4%.

4. A liquid metal thermal paste according to any one of claims 1 to 3, wherein said liquid metal is selected from one or more of gallium-based alloys, tin-based alloys or bismuth-based alloys.

5. A liquid metal thermal paste according to claim 4, wherein said gallium-based alloy is selected from alloys having a melting point below 50 ℃;

preferably, the gallium-based alloy is selected from low melting point alloys prepared from gallium and one or more metals of indium, tin, zinc, aluminum, copper, magnesium or bismuth;

further preferably, the gallium-based alloy is selected from one or more of a gallium-indium alloy, a gallium-indium-tin alloy, a gallium-indium-zinc alloy, or a gallium-indium-tin-zinc alloy.

6. The liquid metal thermal paste of claim 4, wherein the tin-based alloy is selected from one or more of a tin-bismuth alloy, a tin-bismuth-indium alloy, or a tin-bismuth-indium-zinc alloy.

7. A liquid metal thermal paste according to claim 4, wherein said bismuth-based alloy is selected from alloys having a melting point below 100 ℃; preferably, the bismuth-based alloy is selected from one or more of bismuth indium alloy, bismuth indium tin alloy, bismuth indium zinc or bismuth indium tin zinc alloy.

8. The method for preparing a liquid metal thermal paste according to any one of claims 1 to 7, comprising:

(1) surface pretreatment of the heat conduction enhancement particles;

(2) mixing the heat conduction enhanced particles treated in the step (1) with liquid metal, and homogenizing and stirring to obtain a mixture A;

(3) and adding a viscosity regulator into the mixture A, stirring to uniformly disperse the viscosity regulator in the mixture A, and fully oxidizing the liquid metal to obtain the liquid metal heat-conducting paste.

9. The production method according to claim 8, wherein in the step (1), the surface pretreatment includes: removing surface oxides of the heat conduction enhancement particles by using a surface treating agent, washing the particles to be neutral by using deionized water, and drying the particles; wherein the surface treating agent is selected from one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or carbonic acid;

and/or in the step (2) and the step (3), the homogenizing and stirring conditions are as follows: the stirring speed is 100-;

and/or in the step (2) and the step (3), the stirring temperature is 10-50 ℃ higher than the melting point of the liquid metal, and preferably 10-30 ℃.

10. Use of the liquid metal thermal paste according to any one of claims 1 to 7 in a heat sink for an electronic device.

Technical Field

The invention belongs to the technical field of liquid metal thermal interface materials, and particularly relates to liquid metal heat-conducting paste and a preparation method and application thereof.

Background

With the development of microelectronic technology, the heat flux density of electronic devices is increasing continuously, and it is counted that 55% of electronic equipment failures are caused by overhigh temperature, so that higher heat dissipation requirements on the electronic devices are necessary, and therefore, effectively solving the heat dissipation problem becomes a key technology that electronic equipment must solve.

The CPU is used as a core component of the computer, and the ultra-fast operation brings a large amount of heat, so that a heat dissipation device needs to be additionally arranged on the CPU to ensure that the CPU is at a proper temperature. At present, a sandwich structure consisting of a radiating fin, heat conducting paste and a CPU is adopted to realize heat dissipation; the heat conducting paste is currently made of silicone grease, the heat conductivity of the heat conducting paste is only 8W/m.K, and when the heat productivity of a chip is small, the performance requirement can be met; however, when the heat generated by the chip is large, the heat dissipation requirement of the chip cannot be satisfied.

As a new material, liquid metal has a higher thermal conductivity, and the trend of using liquid metal to make thermal conductive paste is present. Compared with the traditional heat-conducting silicone grease, the heat-conducting paste made of liquid metal has the advantages of non-volatility, high heat conductivity and the like.

However, the liquid metal heat-conducting paste has the problem of liquid metal leakage in the long-term use process, so that the heat conductivity is reduced, and the service life of an electronic product is influenced; on the other hand, leakage of liquid metal may short-circuit and damage the electronic product.

Therefore, finding a method for solving the problems of liquid metal leakage and heat conductivity reduction and ensuring long-term reliable work of the liquid metal heat conducting paste is an important research direction in the field of liquid metal thermal interface materials.

Disclosure of Invention

In order to overcome the technical problems, the invention provides a novel liquid metal heat conducting paste with high heat conducting performance. Compared with other liquid metal heat-conducting pastes, the liquid metal heat-conducting paste provided by the invention has the characteristics of high heat-conducting property, stability in operation, no leakage and no delamination after long-term placement.

The liquid metal heat conducting paste comprises: liquid metal, heat conduction enhancing particles and a viscosity regulator; wherein the content of the first and second substances,

the heat conduction enhanced particles are selected from one or more of copper powder, silicon carbide powder, silver powder or alumina powder;

the viscosity modifier is selected from fumed silica and/or an unsaturated polycarboxylic amine salt.

The invention discovers that the specific heat conduction enhanced particles added into the liquid metal are beneficial to improving the heat conductivity of the heat conducting paste; meanwhile, the proper viscosity regulator is selected to ensure that the heat conduction enhancement particles are more uniformly dispersed in the system, so that the heat conduction enhancement particles can play a role to the maximum extent, and the separation of liquid metal from the heat conduction paste and the leakage of the liquid metal in the use process of the heat conduction paste can be favorably prevented.

In order to further improve the comprehensive performance of the liquid metal heat-conducting paste, the invention also optimizes the composition of the liquid metal heat-conducting paste.

In the liquid metal heat-conducting paste, the mass fraction of the heat-conducting reinforcing particles is 1-50%, preferably 5-30%. Within the range, the dispersibility of the heat conduction reinforcing particles in the heat conduction paste can be better ensured, the agglomeration phenomenon is avoided, and the heat conduction paste is more favorable for improving the heat conductivity and the viscosity.

The particle size of the heat conduction enhancing particles is 1-100 mu m. By controlling the particle size, the agglomeration phenomenon of the heat conduction enhanced particles can be avoided, and the heat conductivity can be maximally improved.

The mass fraction of the viscosity regulator is 0.1-4%. By adjusting the proper proportion among the heat conduction enhanced particles, the viscosity regulator and the liquid metal, the heat conduction enhanced particles in the obtained heat conduction paste are dispersed more uniformly, and meanwhile, the viscosity of the heat conduction paste is further improved, so that the obtained heat conduction paste has ultrahigh heat conductivity and proper viscosity, is more favorable for smearing, and has the advantages of more stable and reliable working state and no leakage of the liquid metal.

The liquid metal is selected from one or more of gallium-based alloy, tin-based alloy or bismuth-based alloy.

Wherein the gallium-based alloy is selected from alloys having a melting point below 50 ℃; preferably gallium with one or more of indium, tin, zinc, aluminum, copper, magnesium or bismuth; more preferably one or more of gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-zinc alloy, and gallium-indium-tin-zinc alloy.

Wherein the tin-based alloy is selected from one or more of a tin-bismuth alloy, a tin-bismuth-indium alloy or a tin-bismuth-indium-zinc alloy.

Wherein the bismuth-based alloy is selected from alloys with the melting point lower than 100 ℃, preferably one or more of bismuth indium alloy, bismuth indium tin alloy, bismuth indium zinc or bismuth indium tin zinc alloy.

The invention also provides a preparation method of the liquid metal heat-conducting paste, which comprises the following steps:

(1) surface pretreatment of the heat conduction enhancement particles;

(2) mixing the heat conduction enhanced particles treated in the step (1) with liquid metal, and homogenizing and stirring to obtain a mixture A;

(3) and adding a viscosity regulator into the mixture A, stirring to uniformly disperse the viscosity regulator in the mixture A, and fully oxidizing the liquid metal to obtain the liquid metal heat-conducting paste.

According to the invention, the heat conduction enhanced particles and the viscosity regulator are sequentially added into the liquid metal, the heat conduction enhanced particles are fully dispersed and oxidized in the liquid metal through homogeneous stirring, and the viscosity of the heat conduction paste is further regulated by using the viscosity regulator, so that the liquid metal heat conduction paste with the advantages is obtained, and the defects of easy leakage and low heat conductivity of the liquid metal in the use process of the conventional heat conduction paste are avoided.

In the step (1), the surface pretreatment comprises: firstly, removing surface oxides of the heat conduction enhanced particles by using a surface treating agent, then washing the particles to be neutral by using deionized water, and drying the particles. Wherein the surface treating agent is selected from one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or carbonic acid. Through pretreatment, the heat conduction enhanced particles can be better dispersed in the liquid metal, and the heat conductivity of the heat conduction paste can be better improved.

In the step (2) and the step (3), the homogenizing and stirring conditions are as follows: the stirring speed is 100-; the stirring time is 2.5 hours; the stirring temperature is 10-50 ℃ higher than the melting point of the liquid metal, and preferably 10-30 ℃.

The invention also provides application of the liquid metal heat-conducting paste in a heat dissipation device of an electronic device.

The application specifically comprises:

(1) when the liquid metal heat-conducting paste is Ga-based nano liquid metal heat-conducting paste, the liquid metal heat-conducting paste is paste at room temperature and is used for a heating and heat-dissipating scene of a copper substrate, a titanium substrate, a ceramic substrate or a stainless steel substrate;

(2) when the liquid metal heat-conducting paste is the Bi-based nano liquid metal heat-conducting paste, the liquid metal heat-conducting paste is used for a heating and heat-dissipating scene of a copper substrate, an aluminum substrate, a ceramic substrate or a stainless steel substrate; preheating is required before use.

The invention also provides a heat radiating device of the electronic device, which is a sandwich structure consisting of a heat radiating fin, the liquid metal heat conducting paste and the CPU.

The invention has the following beneficial effects:

according to the invention, by adding the heat conduction enhancement particles subjected to surface treatment and the viscosity regulator, the heat conduction performance of the heat conduction paste is improved, and the liquid metal is prevented from leaking (within a proper viscosity range) in the use process, so that the heat conduction paste is more stable and safer in the use process.

The heat dissipation device made of the heat conduction paste can solve the heat dissipation problem of the conventional large heat generation chip, ensure the temperature of the chip to be within a normal range and prolong the service life of the chip. Meanwhile, the heat conducting paste has higher heat conductivity, so that the liquid metal consumption can be reduced and the cost of the heat conducting paste can be reduced compared with the conventional pure liquid metal heat conducting paste under the condition of the same heat productivity of the chip.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In the following examples, the thermal conductivity was measured using the test standard ASTM D5470.