Thermal interface material for immersed liquid cooling and preparation method thereof

Abstract

The invention provides a thermal interface material for immersed liquid cooling. The thermal interface material is prepared from the following components in parts by weight: 3-8 parts of vinyl-terminated silicone oil with the viscosity of 500 mPa.s, 0.1-1 part of side chain type hydrogen-containing silicone oil with the hydrogen content of 3.8 mmol / g, 0.5-3 parts of double-terminated hydrogen-containing silicone oil, 1-5 parts of modified silicone oil, 0.01-0.2 part of a catalyst, 0.01-0.2 part of an inhibitor, 0.1-1 part of a coupling agent, 60-80 parts of zinc oxide with the particle size of 2-7 microns and 15-25 parts of zinc oxide with the particle size of 0.1-1 micron. According to the thermal interface material prepared by the invention, cooling liquid is greatly prevented from permeating from a radiator interface and a heating device interface; the liquid cooling device can perfectly meet the requirement of electronic components needing to be cooled by adopting immersed liquid cooling, has ultralow thermal resistance to meet the heat dissipation requirement, can resist dissolution and swelling of various cooling liquids, and keeps the reliability of products.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thermal interface materials, and particularly relates to a thermal interface material for immersion liquid cooling and a preparation method thereof. BACKGROUND

[0002] A data center is a strategic resource and new infrastructure supporting the development of modern economy and society, and is used for collecting, storing, processing and distributing a large amount of data. With the gradual development of high-density business applications such as artificial intelligence, virtual reality and smart city, the computing capacity and complexity required to be dealt with by the data center are rapidly increasing. Under the limitation that the chip process improvement speed is slowing down, in order to meet the requirements of faster and more difficult processing, the computing industry has to increase the chip capacity by "stacking", and the CPU power has increased from 150W to more than 300W per single CPU, and the power of a single GPU for a graphics processing unit is even more than 700W. For information communication equipment, operating temperature is an important factor that seriously affects the stability of its working performance, and data center heat dissipation must be effectively solved as the density increases. According to different cooling principles, the current cooling solutions can be divided into two categories: gas cooling (air cooling) and liquid cooling. Since the maximum power of a data center rack under the air cooling heat dissipation architecture is 20-30kW, and the direct liquid cooling can increase the power limit of each rack to more than 100kW, therefore in more and more high heat load, limited building area and high energy saving requirement scenarios, only liquid cooling solutions can be sought.

[0003] With the tightening of PUE requirements of China's data center policy and the emphasis on energy saving and low carbon, reducing energy consumption has become a topic that must be explored by data centers. At least 1 / 3 of the energy required for the operation of a data center is used for heat dissipation of IT equipment, so reducing the energy consumption of the refrigeration system is the key link of the entire data center energy saving and consumption reduction. Liquid cooling heat dissipation technology improves cooling efficiency through liquid circulation heat exchange, which can significantly reduce the total energy consumption and carbon dioxide emissions of the data center, and meets the low-carbon development requirements of China's data center.

[0004] Data center liquid cooling is divided into immersion, cold plate and other main ways. Immersion cooling method can greatly reduce PUE due to its high heat dissipation efficiency, and has been the focus of research by experts, scholars and industry users in recent years, and is a key branch of data center liquid cooling technology. According to statistics, the global immersion liquid cooling market is expected to grow to 700 million US dollars in the next five years, with a compound annual growth rate of more than 20%. Increasing chip density, harsh edge computing environment and the pressure of data center energy saving and emission reduction will continue to drive the growth of the immersion liquid cooling market.

[0005] Unlike air cooling, immersion liquid cooling structure will the entire electronic device bubble in the cooling liquid, through the cooling liquid circulation will heat away quickly, thermal interface material is located between the chip and the heat sink, also immersed in the cooling liquid. The market mainstream cooling liquid has three systems, they are high boiling point of single-phase fluorinated liquid, and the same source of lubricating oil olefin system synthetic oil, and silicone system of modified silicone oil. Because, chip power is high, heat needs to be quickly out, interface material thermal resistance is one of the key factors, plus the cooling liquid has the characteristics of similar solvent, on the ordinary polymer-based thermal interface material has the effect of dissolution or swelling. Such as ultra-low thermal resistance of thermal conductive silicone grease or thermal conductive phase change material, easy to dissolve in a certain type of cooling liquid, with the cooling liquid compatibility is poor; and thermal pad can resist dissolution to some extent, but long-term immersion will also appear swelling phenomenon, plus the thermal pad itself thermal resistance is very high, seriously affect the heat dissipation; The use of metal-based thermal interface material such as indium alloy, there will be a gap between the interface, the cooling liquid will enter the interface, the thermal resistance will be further improved. Therefore, the thermal interface material applied in the immersion liquid cooling box, its own thermal resistance should be as low as possible, at the same time, solve the compatibility with the cooling liquid is the most important. SUMMARY

[0006] The present application is directed to the above problems, a kind of low thermal resistance thermal interface material with good compatibility can resist cooling liquid immersion. By designing high crosslinking density and higher adhesion, prevent the invasion of cooling liquid in the thermal interface material and the interface between the thermal interface material and chip, maintain the stability and reliability of thermal interface material, protect the chip, prevent overheating.

[0007] The thermal interface material for immersion liquid cooling described in the application is made from the following components by weight parts: 3-8 parts of end vinyl silicone oil with viscosity 500 mPa·s, 0.1-1 parts of side chain type hydrogen-containing silicone oil with hydrogen content 3.8 mmol / g, 0.5-3 parts of double-end hydrogen-containing silicone oil, 1-5 parts of modified silicone oil, 0.01-0.2 parts of catalyst, 0.01-0.2 parts of inhibitor, 0.1-1 parts of coupling agent, 60-80 parts of 2-7 um zinc oxide, 15-25 parts of 0.1-1 um zinc oxide.

[0008] The end vinyl silicone oil is preferably HV series of Kawabata Chemical, VS series of Dow Corning.

[0009] The side chain type hydrogen-containing silicone oil is preferably SH series of Kawabata Chemical, XL series of Dow Corning.

[0010] The double-end hydrogen-containing silicone oil has a viscosity of 30-500 mPa·s, and is preferably D-100, D-500 of Kawabata Chemical, and CE series of Dow Corning.

[0011] The modified silicone oil has a viscosity of 10-100 mPa·s, is a double-end chain branched modified polysiloxane, and has one of a vinyl group, a long-chain alkyl group with 3-10 carbons, an acrylate group, a 3-glycidylpropyl group, an epoxy group, a methacryloyloxy group, and the like as a functional group at one end, and one of a methoxy group, an ethoxy group, a propoxy group, a hydroxyl group, a carboxyl group, and the like as a functional group at the other end.

[0012] The modified silicone oil is preferably a Kawabata Chemical JOC series.

[0013]

[0014] The modified silicone oil is preferably a Kawabata Chemical HVO series.

[0015]

[0016] The modified silicone oil is preferably Shin-Etsu's X-22-176.

[0017]

[0018] The modified silicone oil is preferably MCR-XT11 of Shanghai Mayreal Chemical.

[0019]

[0020] The catalyst is a platinum-gold catalyst, and preferably CAT-PL-56 of Shin-Etsu Chemical with a platinum content of 4800 ppm, or PT-5000 of Guangzhou Siyou with a platinum content of 5000 ppm.

[0021] The inhibitor is an acetylenic alcohol inhibitor, and preferably YZJ-12 of Guangzhou Siyou.

[0022] The coupling agent is KH-570.

[0023] The 2-7 um zinc oxide has a particle size D100 of less than 15 um, and is preferably LPZINC-2S of Japan Sakai Chemical, DW-4, DW-10, and the like of Japan Bai Shui Chemical.

[0024] The 0.1-1 um zinc oxide is preferably FB-72 of Jingong New Material, HD-01, HD-02, and the like of Japan Bai Shui Chemical.

[0025] The process of the heat-conducting interface material mainly includes the following steps: (1) adding end-vinyl silicone oil, modified silicone oil, side-chain hydrogen-containing silicone oil, double-end hydrogen-containing silicone oil, coupling agent, 2-7 um zinc oxide, and 0.1-1 um zinc oxide into a mixing tank of a planetary gravity stirrer, stirring for 3-10 min at a speed of 400 r-1000 rpm, and adding vacuum; (2) Add the inhibitor and stir for 3-5 minutes at a rotation speed of 400r-1000rpm under vacuum; (3) Add the catalyst and stir for 3-5 minutes at a rotation speed of 400r-1000rpm under vacuum; (4) After uniform stirring, a paste material is obtained, that is, the heat-conducting interface material, which is filled into an EFD dispensing tube and stored in a frozen state, is returned to room temperature before dispensing, and is baked at 100 DEG C for 1h after assembly to completely solidify.

[0026] Since the electronic components requiring liquid cooling design are necessarily high-power components with strong heat dissipation requirements, the thermal interface material is applied between the electronic components and the heat sink to act as a heat flow bridge. The thermal resistance of the thermal interface material is a key factor affecting the maximum temperature of the heat-generating components, and the smaller the thermal resistance, the lower the maximum temperature, indicating that the heat dissipation capacity of the thermal interface material is stronger. Ordinary low-thermal-resistance heat-conducting interface materials are mainly mixed with small-particle-size powder and a resin matrix to form a paste, which can slowly dissolve in some cooling liquids after working in the cooling liquid for a period of time, losing the heat transfer effect. The cross-linked and solidified heat-conducting interface material can maintain good compatibility to a certain extent, but the thermal resistance is about 5-10 times higher, and the heat cannot be quickly dissipated.

[0027] The innovation of the present application lies in: 1. By more fine powder grading, the porosity of the system is greatly reduced, and the cooling liquid infiltration channel is reduced.

[0028] 2. By more closely packed powder and control of the maximum particle size, the thermal resistance of the product can be greatly reduced, and the heat dissipation capacity can be improved.

[0029] 3. By higher density cross-linking, the silicon oil molecular chains are linked by tighter chemical bonds to resist the dissolution and swelling of the cooling liquid.

[0030] 4. By using ultra-high speed equipment, the agglomeration between the powders is maximized, the system uniformity is enhanced, the possibility of cooling liquid dissolution and swelling is further reduced, and the thermal resistance is also reduced to a certain extent.

[0031] 5. Designing a higher density cross-linking and a certain bonding capacity can greatly prevent the cooling liquid from infiltrating from the heat sink interface and the heat-generating device interface; at the same time, it can also to a certain extent prevent the warping deformation of the heat-generating device due to thermal expansion and cold contraction, and is not easy to separate the interface.

[0032] In summary, the above five points can be basically solved by ordinary thermal interface materials, but the present application realizes the above five points at the same time in one product through special formulation and process design, which can perfectly meet the needs of electronic components using immersion liquid cooling for cooling, that is, the super-low thermal resistance meets the heat dissipation requirements, and the dissolution and swelling of various cooling liquids are resisted, and the reliability of the product is maintained. DETAILED DESCRIPTION

[0033] The present application is described below in connection with examples, which are intended to be illustrative only and not limiting of the scope of the application.

[0034] Example 1 (1) 4 parts of end-vinyl silicone oil HV-500, 3 parts of modified silicone oil X-22-176, 0.5 parts of side chain hydrogen-containing silicone oil SH-36, 1 part of double-end hydrogen-containing silicone oil CE-100, 0.3 parts of coupling agent, 2-7 um zinc oxide 70 parts, 0.1-1 um zinc oxide 21 parts are added to the mixing tank of the planetary gravity stirrer, stirred for 3-10 min, the speed is 800 rpm, vacuum is added; (2) 0.1 parts of inhibitor YZJ-12 is added and stirred for 3-5 min, the speed is 800 rpm, vacuum is added; (3) 0.1 parts of catalyst PT-5000 is added and stirred for 3-5 min, the speed is 800 rpm, vacuum is added; (4) After mixing evenly, a paste-like material is obtained, that is, the heat-conducting interface material is obtained.

[0035] Example 2 (1) 4 parts of end-vinyl silicone oil HV-500, 3 parts of modified silicone oil X-22-176, 1.5 parts of double-end hydrogen-containing silicone oil CE-100, 0.3 parts of coupling agent, 2-7 um zinc oxide 70 parts, 0.1-1 um zinc oxide 21 parts are added to the mixing tank of the planetary gravity stirrer, stirred for 3-10 min, the speed is 800 rpm, vacuum is added; (2) 0.1 parts of inhibitor YZJ-12 is added and stirred for 3-5 min, the speed is 800 rpm, vacuum is added; (3) 0.1 parts of catalyst PT-5000 is added and stirred for 3-5 min, the speed is 800 rpm, vacuum is added; (4) After mixing evenly, a paste-like material is obtained, that is, the heat-conducting interface material is obtained.

[0036] Example 3 (1) 4 parts of end-vinyl silicone oil HV-500, 3 parts of modified silicone oil X-22-176, 0.5 parts of side chain hydrogen-containing silicone oil CE-100, 1.3 parts of double-end hydrogen-containing silicone oil CE-100, 2-7 um zinc oxide 70 parts, 0.1-1 um zinc oxide 21 parts are added to the mixing tank of the planetary gravity stirrer, stirred for 3-10 min, the speed is 800 rpm, vacuum is added; (2) 0.1 parts of inhibitor YZJ-12 is added and stirred for 3-5 min, the speed is 400r~1000rpm, vacuum is added; (3) Add 0.1 part of catalyst PT-5000, stir for 3-5 min, rotate at 800 rpm, and add vacuum; (4) After stirring evenly, obtain paste material, that is, the heat-conducting interface material.

[0037] Example 4 (1) Add 4 parts of end-vinyl silicone oil HV-500, 3 parts of modified silicone oil X-22-176, 1.5 parts of hydrogen-containing silicone oil CE-100, 0.3 parts of coupling agent, 70 parts of 2-7 um zinc oxide, and 21 parts of 0.1-1 um zinc oxide to the mixing tank of the planetary gravity stirrer, stir for 3-10 min, rotate at 800 rpm, and add vacuum; (2) Add 0.1 part of inhibitor YZJ-12, stir for 3-5 min, rotate at 800 rpm, and add vacuum; (3) Add 0.1 part of catalyst PT-5000, stir for 3-5 min, rotate at 800 rpm, and add vacuum; (4) After stirring evenly, obtain paste material, that is, the heat-conducting interface material.

[0038] Comparative Example 1 Common low-thermal-resistance heat-conducting paste.

[0039] Comparative Example 2 Common solidifiable heat-conducting gel.

[0040] Test The heat-conducting interface materials obtained in Examples 1-4 and Comparative Examples 1-2 are tested, and the test results are shown in Table 1.

[0041] Table 1. Performance comparison of Examples 1-4 and Comparative Examples 1-2

[0042] From the above examples and comparative data, it can be seen that: although the thermal resistance of Comparative Example 1 is the lowest, the maximum temperature of the chip is also the lowest, but the temperature rises sharply after soaking in the cooling liquid for 30 days; the initial maximum temperature of Comparative Example 2 is the highest due to the excessively high thermal resistance, which is not helpful for heat dissipation of the chip; the crosslinking density of Example 2 is greatly reduced, and the temperature rises obviously after soaking in the cooling liquid for 30 days; the shear force of Example 3 is greatly reduced after removing the coupling agent that provides certain adhesion, and the temperature also rises obviously after soaking in the cooling liquid for 30 days; the crosslinking density of Example 4 is greatly increased, which leads to interface delamination due to the warping deformation of the chip, and the cooling liquid invades, and the temperature rises obviously after soaking in the cooling liquid for 30 days; and the A group can well meet the long-term, reliable, and effective work of electronic components in the immersion liquid cooling through the design of high crosslinking density, certain adhesion strength, and low thermal resistance.

[0043] The above merely describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A thermal interface material for submersion liquid cooling, characterized by, The following components are prepared by weight parts: 3-8 parts of end vinyl silicone oil with viscosity of 500 mPa·s, 0.1-1 parts of side chain type hydrogen-containing silicone oil with hydrogen content of 3.8 mmol / g, 0.5-3 parts of double-end hydrogen-containing silicone oil, 1-5 parts of modified silicone oil, 0.01-0.2 parts of catalyst, 0.01-0.2 parts of inhibitor, 0.1-1 parts of coupling agent, 60-80 parts of 2-7 um zinc oxide, and 15-25 parts of 0.1-1 um zinc oxide.

2. The thermal interface material of claim 1, wherein, The end vinyl silicone oil is preferably HV series of Kawabata Chemical, VS series of Dow Corning.

3. The thermal interface material of claim 1, wherein, The side chain type hydrogen-containing silicone oil is preferably SH series of Kawabata Chemical, XL series of Dow Corning.

4. The thermal interface material of claim 1, wherein, The double-end hydrogen-containing silicone oil has a viscosity of 30-500 mPa·s, and is preferably D-100, D-500 of Kawabata Chemical, and CE series of Dow Corning.

5. The thermal interface material of claim 1, wherein, The modified silicone oil has a viscosity of 10-100 mPa·s, and is preferably one of JOC and HVO series of Kawabata Chemical, X-22-176 of Shin-Etsu, and MCR-XT11 of Shanghai Mayreal Chemical.

6. The thermal interface material of claim 1, wherein, The catalyst is a platinum-gold catalyst, and is preferably CAT-PL-56 of Shin-Etsu Chemical with platinum content of 4800 ppm, and PT-5000 of Guangzhou Siyou with platinum content of 5000 ppm.

7. The thermal interface material of claim 1, wherein, The inhibitor is an alkyne alcohol inhibitor, and is preferably YZJ-12 of Guangzhou Siyou and methyl butyne alcohol; and the coupling agent is KH-570.

8. The thermal interface material of claim 1, wherein, The 2-7 um zinc oxide has a particle size D100 of less than 15 um, and is preferably LPZINC-2S of Sakai Chemical, DW-4 and DW-10 of Japan Hakuyo Chemical; and the 0.1-1 um zinc oxide is preferably FB-72 of Jingge New Material, and HD-01 and HD-02 of Japan Hakuyo Chemical.

9. The thermal interface material of claim 1, wherein, The preparation process mainly includes the following steps: (1) The end vinyl silicone oil, modified silicone oil, side chain hydrogen-containing silicone oil, double-end hydrogen-containing silicone oil, coupling agent, 2-7 um zinc oxide, and 0.1-1 um zinc oxide are added to the mixing tank of a planetary gravity stirrer, stirred for 3-10 min at a speed of 400 r-1000 rpm, and vacuum is applied; (2) The inhibitor is added and stirred for 3-5 min at a speed of 400 r-1000 rpm, and vacuum is applied; (3) The catalyst is added and stirred for 3-5 min at a speed of 400 r-1000 rpm, and vacuum is applied; (4) After uniform mixing, a paste-like material is obtained, that is, the thermal interface material is obtained, the paste-like material is filled into an EFD dispensing tube and stored in a refrigerator, and the dispensing tube is returned to room temperature before dispensing, and is baked at 100℃ for 1 h after assembly to completely solidify.

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