High-thermal-conductivity wave-absorbing gasket, preparation method and application thereof

Abstract

The present application relates to the technical field of heat-conducting wave-absorbing composite materials (IPC classification number is C08L), and particularly relates to a high-heat-conducting wave-absorbing gasket as well as a preparation method and application thereof, and preparation raw materials include silicon oil, heat-conducting fillers and wave-absorbing fillers; the heat-conducting fillers include first heat-conducting particles with a particle size of 20-150 mu m, second heat-conducting particles with a particle size of 1-50 mu m, and third heat-conducting particles with a particle size of 0.1-20 mu m; and the viscosity of the silicon oil is 50-10000 mPa. The prepared high-heat-conducting wave-absorbing gasket has the excellent effect that the heat conductivity coefficient is 7-7.5 W / m*K, which is achieved by the collocation of multiple wave-absorbing fillers and heat-conducting particles in a specific proportion and particle size.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive and microwave-absorbing composite materials (IPC classification number C08L), and particularly to a high thermal conductivity microwave-absorbing pad, its preparation method, and its application. Background Technology

[0002] With the development of 5G technology, the number of various types of electronic devices is gradually increasing, and the operating frequency of communication equipment is also constantly increasing. Electronic devices generate significantly more heat during operation, and the temperature rises at a faster rate. Furthermore, various high-frequency electromagnetic radiations in the environment can also affect the normal operation of equipment. These factors pose challenges to the reliability and stability of communication equipment. Solving the problems of heat dissipation and electromagnetic wave absorption simultaneously presents a significant technical hurdle for internal application materials. The thermally conductive pads inside electronic devices occupy considerable thickness, leaving insufficient space for adding electromagnetically absorbing fillers to address electromagnetic interference. Therefore, thermally conductive absorbing sheets have emerged, integrating heat conduction and electromagnetic wave absorption functions to solve the problem of insufficient space in electronic devices that prevents a balance between performance and thermal conductivity. For example, Chinese patent CN114133740A discloses a thermally conductive and electromagnetically absorbing composite material using an addition-curing process, but its thermal conductivity is only 4 W / mK, which is too low to meet the heat dissipation requirements of high-power electronic devices. Existing high thermal conductivity absorbing fillers often employ complex processes, such as treating carbon fibers or boron nitride, which are difficult to scale up production and are costly. Therefore, a high thermal conductivity absorbing pad with readily available raw materials, simple process and easy mass production has great market potential. Summary of the Invention

[0003] The first aspect of the present invention provides a high thermal conductivity microwave absorbing pad, the raw materials for which include: silicone oil, thermally conductive filler and microwave absorbing filler; the thermally conductive filler includes first thermally conductive particles with a particle size of 20-150 μm, second thermally conductive particles with a particle size of 1-50 μm, and third thermally conductive particles with a particle size of 0.1-20 μm; the silicone oil has a viscosity of 50-10000 mPa.

[0004] Furthermore, by weight, the raw materials include: 3-5 parts silicone oil, 70-100 parts thermally conductive filler, and 10-70 parts microwave absorbing filler.

[0005] In some embodiments, the silicone oil comprises vinyl silicone oil and hydrogen-containing silicone oil in a mass ratio of 1:(0.1-0.2).

[0006] In some embodiments, the vinyl silicone oil includes at least one of single-ended vinyl silicone oil, double-ended vinyl silicone oil, side-chain vinyl silicone oil, phenyl silicone oil, fluorosilicone oil, and vinyl MQ resin.

[0007] The vinyl silicone oil has a vinyl content of 0.7% and a viscosity of 20-100 mPa·s, and is preferably sourced from Shandong Dayi.

[0008] In some embodiments, the hydrogen-containing silicone oil includes at least one of end-containing hydrogen-containing silicone oil and side-containing hydrogen-containing silicone oil.

[0009] The hydrogen-containing silicone oil has a hydrogen content of 0.4%, and is preferably sourced from Xin'an, Zhejiang.

[0010] In some embodiments, the first thermally conductive particle, the second thermally conductive particle, and the third thermally conductive particle each include at least one of aluminum oxide, zinc oxide, boron nitride, bismuth oxide, silicon carbide, aluminum nitride, silicon dioxide, aluminum powder, silver powder, graphene, and carbon nanotubes.

[0011] Furthermore, the mass ratio of the first thermally conductive particle, the second thermally conductive particle, and the third thermally conductive particle is (2-8):(1-5):(0.5-5).

[0012] Furthermore, the specific types of the first, second, and third thermally conductive particles can be completely the same, partially the same, or completely different.

[0013] Excessive filler content in gaskets can lead to decreased mechanical strength and brittleness. The applicant discovered in its research that limiting the particle size of three thermally conductive particles can significantly increase the amount of thermally conductive filler in the system, thereby endowing the material with excellent thermal conductivity. The prepared gaskets still maintain their integrity under stress test.

[0014] In some embodiments, the microwave absorbing filler includes at least one of Fe-Co alloy, Fe-Si alloy, Fe-Cr alloy, Fe-Si-Al-Cr alloy, silicon-copper alloy, Fe-Cu-Nb-Si-B alloy, Fe-Si-Cr-Ni alloy, manganese-zinc ferrite, nickel-zinc ferrite, iron-silicon-aluminum ferrite, carbonyl iron powder, carbonyl nickel powder, and ferrite.

[0015] Furthermore, the particle size of the microwave absorbing filler is 3-5 μm, and it is preferably sourced from BASF.

[0016] In some embodiments, the thermal conductivity of the gasket is 7-7.5 W / m*K.

[0017] In some embodiments, the raw materials for preparation also include: treatment agents, inhibitors, and catalysts.

[0018] Furthermore, by weight, the raw materials also include: 0-10 parts of treatment agent, 0.02-0.08 parts of inhibitor, and 0.05-0.2 parts of catalyst.

[0019] To increase the compatibility between the filler and the base polymer and reduce the viscosity of the system, the treatment agent further includes at least one of alkoxy silicone oil, silane coupling agent, phthalate coupling agent, aluminate coupling agent, bimetallic coupling agent, lignin coupling agent, and tin coupling agent.

[0020] Furthermore, the inhibitor includes at least one of ethynylcyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, and 3,6-dimethyl-1-heptyyn-3-ol.

[0021] Furthermore, the catalyst comprises at least one of methylvinylsiloxane-platinum complex, isopropanol solution of chloroplatinic acid, platinum-tetrahydrofuran complex, and platinum-vinyl complex.

[0022] The compression ratio is the ratio of the compressed amount of a thermally conductive silicone pad after installation to its actual thickness in the free state. The compression ratio of a gasket is one of the mechanical performance indicators for evaluating its compressibility. The deformation characteristics of a gasket during loading are important conditions for achieving initial sealing capability, and this is closely related to the compression ratio and resilience. The harder the gasket, the lower its compression ratio under the same pressure. This can easily cause gasket structural damage under normal installation preload. Conversely, the softer the gasket, the greater its compression ratio under the same pressure. This requires a larger initial installation preload, making it difficult to achieve a proper seal. Figure 1-2 As shown, the compressibility of the thermally conductive silicone sheet was evaluated by plotting a pressure-compression ratio curve under pressures ranging from 0 to 100 psi. Figure 3-5 It can be seen that the gaskets showed no obvious damage or cracking after the pressure test.

[0023] The second aspect of the present invention provides a method for preparing a high thermal conductivity microwave absorbing pad, the method comprising: adding silicone oil, thermally conductive filler, microwave absorbing filler and treatment agent to a stirrer, mixing and heating, then heating and cooling in a gradient manner, then adding inhibitor and catalyst in sequence, and then calendering and curing the mixture to obtain a high thermal conductivity microwave absorbing pad.

[0024] Furthermore, the preparation method includes: adding silicone oil, thermally conductive filler, microwave-absorbing filler, and treatment agent to a stirrer, mixing them, heating to 115-125℃ and vacuuming for 0.5-5 hours, cooling to 45-55℃ and adding inhibitor, stirring under vacuum for 0.5-2 hours, continuing to cool to below 30℃ and adding catalyst, stirring under vacuum for 0.5-2 hours, and then calendering and curing the mixture to obtain a high thermal conductivity microwave-absorbing pad.

[0025] A third aspect of the present invention provides an application of a high thermal conductivity absorbing pad in electronic devices.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. By preparing a high thermal conductivity absorbing pad, the problem that thermal conductivity and wave absorption cannot be achieved simultaneously in the existing technology is solved. When used in electronic devices, it can minimize the footprint and integrate thermal conductivity and wave absorption functions, which can meet the needs of the electronic device industry for high-power electronic devices in terms of efficient energy conduction and electromagnetic compatibility.

[0028] 2. The high thermal conductivity absorbing pad prepared by the present invention can reduce electrical signal interference to electronic components. By combining various absorbing fillers and thermally conductive particles in a specific ratio and particle size, an excellent thermal conductivity of 7-7.5 W / m*K is achieved.

[0029] 3. The microwave absorbing filler and thermally conductive particles of the present invention are added in amounts of more than 95%. By combining specific types and particle sizes, the problem of poor mechanical properties caused by high filler content is solved. After stress compression test, the gasket still maintains its intact shape without cracking or shattering.

[0030] 4. When the high thermal conductivity absorbing pad of the present invention is used in electronic devices, the pad material is soft, has good conformability, is easy to peel off completely, and leaves no residue.

[0031] 5. The production size of the high thermal conductivity absorbing pad of the present invention is not limited, the preparation process is simple and the raw materials are readily available, making it suitable for large-scale production. Attached Figure Description

[0032] Figure 1 The image shows the stress variation curve of the compressive stress test of the thermally conductive and microwave absorbing sheet prepared in Example 1.

[0033] Figure 2 The maximum compressive stress of the thermally conductive and microwave-absorbing sheet prepared in Example 1 is the stress value at 10%, 20%, 30%, 40%, and 50% of the compressive displacement.

[0034] Figure 3 This is the state of the thermally conductive and microwave-absorbing sheet prepared in Example 1 before compression.

[0035] Figure 4 This refers to the thermally conductive and microwave-absorbing state of the thermally conductive and microwave-absorbing sheet prepared in Example 1 during compression.

[0036] Figure 5 This refers to the thermally conductive and microwave-absorbing sheet prepared in Example 1 after compression to a state of thermal microwave absorption.

[0037] Figure 6 This is an image of the thermally conductive and microwave-absorbing sheet prepared in Example 1. Detailed Implementation

[0038] Example 1

[0039] A high thermal conductivity microwave absorbing pad, the raw materials for preparation by weight are: 3.35 parts silicone oil, 74 parts thermally conductive filler, 20 parts microwave absorbing filler, 0.5 parts treatment agent, 0.05 parts inhibitor, and 0.1 parts catalyst;

[0040] The silicone oil is a blend of vinyl-terminated silicone oil (viscosity 100 mPa·s) and hydrogen-containing silicone oil (viscosity 50 mPa·s) in a mass ratio of 3:0.35.

[0041] The thermally conductive filler is a compound of aluminum nitride (first thermally conductive particles with a particle size of 100 μm), aluminum oxide (second thermally conductive particles with a particle size of 10 μm), and zinc oxide (third thermally conductive particles with a particle size of 0.3 μm), in a mass ratio of 45:23:8.

[0042] The microwave absorbing filler is carbonyl iron powder with a particle size of 3 μm, purchased from BASF.

[0043] The treatment agent is alkoxy silicone oil.

[0044] The inhibitor is ethynylcyclohexanol.

[0045] The catalyst is a platinum-vinyl complex.

[0046] A method for preparing a high thermal conductivity microwave absorbing pad includes: adding silicone oil, thermally conductive filler, microwave absorbing filler, and a treatment agent to a stirrer, mixing them, heating the mixture to 120°C and vacuuming it for 1 hour, cooling it to 50°C and adding an inhibitor, stirring under vacuum for 0.5 hours, continuing to cool it to below 30°C and adding a catalyst, stirring under vacuum for 0.5 hours, and then calendering and curing the mixture to obtain the high thermal conductivity microwave absorbing pad.

[0047] Example 2

[0048] A high thermal conductivity microwave absorbing pad, the specific implementation method is the same as that in Example 1, except that, by weight, the raw materials include: 4.45 parts silicone oil, 74.9 parts thermally conductive filler, 20 parts microwave absorbing filler, 0.5 parts treatment agent, 0.05 parts inhibitor, and 0.1 parts catalyst.

[0049] The silicone oil is a blend of vinyl-terminated silicone oil (viscosity 100 mPa·s) and hydrogen-containing silicone oil (viscosity 50 mPa·s) in a mass ratio of 4:0.45.

[0050] The thermally conductive filler is a compound of aluminum nitride (first thermally conductive particles with a particle size of 100 μm), aluminum oxide (second thermally conductive particles with a particle size of 10 μm), and zinc oxide (third thermally conductive particles with a particle size of 0.3 μm), in a mass ratio of 43.9:23:8.

[0051] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0052] Example 3

[0053] A high thermal conductivity microwave absorbing pad, the specific implementation is the same as in Example 1, except that,

[0054] The thermally conductive filler is a compound of aluminum nitride (70 μm first thermally conductive particles), aluminum oxide (10 μm second thermally conductive particles), and zinc oxide (0.3 μm third thermally conductive particles), in a mass ratio of 45:23:8.

[0055] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0056] Example 4

[0057] A high thermal conductivity microwave absorbing pad, the specific implementation method is the same as that in Example 1, except that the microwave absorbing filler is carbonyl iron powder with a particle size of 5 μm, purchased from BASF.

[0058] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0059] Comparative Example 1

[0060] A high thermal conductivity microwave absorbing pad, the specific implementation method is the same as that in Example 1, except that the raw materials for preparation include: 5.05 parts of silicone oil, 44.3 parts of thermally conductive filler, and 50 parts of microwave absorbing filler;

[0061] The silicone oil is a blend of vinyl-terminated silicone oil (viscosity 100 mPa·s) and hydrogen-containing silicone oil (viscosity 50 mPa·s) in a mass ratio of 4.6:0.45.

[0062] The thermally conductive filler is a compound of aluminum nitride (first thermally conductive particle with a particle size of 90 μm), aluminum oxide (second thermally conductive particle with a particle size of 10 μm), and zinc oxide (third thermally conductive particle with a particle size of 0.3 μm), with a mass ratio of 23.85:11.9:8.55.

[0063] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0064] Comparative Example 2

[0065] A high thermal conductivity microwave absorbing pad, the specific implementation is the same as Comparative Example 1, except that the raw materials for preparation include: 5.05 parts of silicone oil, 54.3 parts of thermally conductive filler, and 40 parts of microwave absorbing filler;

[0066] The thermally conductive filler is a compound of aluminum nitride (first thermally conductive particles with a particle size of 90 μm), aluminum oxide (second thermally conductive particles with a particle size of 10 μm), and zinc oxide (third thermally conductive particles with a particle size of 0.3 μm), with a mass ratio of 28.9:14.8:10.6.

[0067] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0068] Comparative Example 3

[0069] A high thermal conductivity microwave absorbing pad, the specific implementation is the same as Comparative Example 1, except that the raw materials for preparation include: 5.05 parts of silicone oil, 64.3 parts of thermally conductive filler, and 30 parts of microwave absorbing filler;

[0070] The thermally conductive filler is a compound of aluminum nitride (70 μm first thermally conductive particles), aluminum oxide (10 μm second thermally conductive particles), and zinc oxide (0.3 μm third thermally conductive particles), in a mass ratio of 5:5:16.

[0071] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0072] Comparative Example 4

[0073] A high thermal conductivity microwave absorbing pad, the specific implementation method is the same as that in Example 1, except that the raw materials for preparation include: 5.05 parts of silicone oil, 34.3 parts of thermally conductive filler, and 60 parts of microwave absorbing filler;

[0074] The silicone oil is a blend of vinyl-terminated silicone oil (viscosity 100 mPa·s) and hydrogen-containing silicone oil (viscosity 50 mPa·s) in a mass ratio of 4.6:0.45.

[0075] The thermally conductive filler is a compound of first thermally conductive alumina particles with a particle size of 120 μm, second thermally conductive alumina particles with a particle size of 10 μm, and third thermally conductive alumina particles with a particle size of 0.3 μm, in a mass ratio of 7.5:3.5:3.3.

[0076] The microwave absorbing filler is carbonyl iron powder with a particle size of 3 μm, purchased from BASF.

[0077] A method for preparing a high thermal conductivity microwave absorbing pad, the specific implementation method is the same as in Example 1.

[0078] Performance testing

[0079] The gaskets prepared in the examples and comparative examples were subjected to the following tests, and the results are shown in Table 1.

[0080] (1) Thermal conductivity test: Refer to ASTM D5470.

[0081] (2) Reflectivity test: Refer to GB / T32596.

[0082] (3) Hardness test: Refer to ASTM D2240.

[0083] (4) Density test: Refer to ASTM D792.

[0084] (5) Compressive stress test was performed on Example 1: Refer to GB / T7759, the test results are shown below. Figure 1-5 .from Figure 3-5 It can be seen that the compressed gasket showed no obvious deformation or damage.

[0085] Table 1

[0086]

[0087]

Claims

1. A high thermal conductivity microwave absorbing pad, characterized in that, The raw materials for preparing the gasket include: silicone oil, thermally conductive filler and microwave absorbing filler; the thermally conductive filler includes aluminum nitride as the first thermally conductive particle with a particle size of 100 μm, aluminum oxide as the second thermally conductive particle with a particle size of 10 μm, and zinc oxide as the third thermally conductive particle with a particle size of 0.3 μm, in a mass ratio of 45:23:

8. The silicone oil includes vinyl silicone oil and side-hydrogen-containing silicone oil in a mass ratio of 1:(0.1-0.2). The viscosity of the vinyl silicone oil is 100 mPa·s, and the viscosity of the hydrogen-containing silicone oil is 50 mPa·s. The raw materials for preparation, by weight, include: 3-5 parts silicone oil, 70-100 parts thermally conductive filler, 10-70 parts microwave absorbing filler, 0-10 parts treatment agent, 0.02-0.08 parts inhibitor and 0.05-0.2 parts catalyst; The thermal conductivity of the gasket is 7-7.5 W / m*K.

2. The high thermal conductivity absorbing pad according to claim 1, characterized in that, The microwave absorbing filler includes at least one of the following: Fe-Co alloy, Fe-Si alloy, Fe-Cr alloy, Fe-Si-Al-Cr alloy, silicon-copper alloy, Fe-Cu-Nb-Si-B alloy, Fe-Si-Cr-Ni alloy, manganese-zinc ferrite, nickel-zinc ferrite, iron-silicon-aluminum ferrite, carbonyl iron powder, carbonyl nickel powder, and ferrite.

3. A method for preparing a high thermal conductivity microwave absorbing pad according to any one of claims 1-2, characterized in that, The preparation method includes: adding silicone oil, thermally conductive filler, microwave absorbing filler and treatment agent to a stirrer, mixing and heating, then gradually cooling and adding inhibitor and catalyst in sequence, and then calendering and curing the mixture to obtain a high thermal conductivity microwave absorbing pad.

4. The application of a high thermal conductivity absorbing pad according to any one of claims 1-2 in electronic devices.

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