A thermally conductive silicone gel, its preparation method and application

Abstract

This invention provides a thermally conductive silicone gel, its preparation method, and its application, belonging to the technical field of thermally conductive interface materials. The thermally conductive silicone gel consists of component A and component B; component A includes: vinyl silicone oil, modified diamond micropowder, modified boron nitride micropowder, aluminum nitride micropowder, modified carbon nanotubes, epoxy chain extender, and platinum-based catalyst; component B includes: vinyl silicone oil, modified diamond micropowder, modified boron nitride micropowder, aluminum nitride micropowder, modified carbon nanotubes, hydrogen-containing silicone oil, and inhibitor. This invention, through the rational gradation of four fillers with different morphologies and particle sizes, achieves high thermal conductivity while maintaining low system viscosity and good flowability, meeting the requirements of automated dispensing processes for microelectronic device packaging.

Description

Technical Field

[0001] This invention relates to the field of thermally conductive interface materials technology, and in particular to a thermally conductive organosilicon gel, its preparation method and application. Background Technology

[0002] With the miniaturization, high integration, and high power density of electronic devices, the heat flux per unit area has increased dramatically, making heat dissipation a key bottleneck restricting the development of the electronics industry. Thermally conductive interface materials, filling the microscopic gaps between heat-generating components and heat sinks, eliminate air and reduce interfacial thermal resistance, making them crucial materials for achieving efficient heat dissipation. Organosilicon gels, due to their excellent flexibility, compressibility, insulation, and superior surface affinity, are widely used in thermal management systems in consumer electronics, communication equipment, new energy vehicles, and power modules.

[0003] However, existing thermally conductive silicone gels still face the following key technical problems in practical applications: (1) Limited intrinsic thermal conductivity of thermally conductive fillers. Traditional thermally conductive silicone gels mostly use metal oxides such as alumina and zinc oxide as thermally conductive fillers, which have low intrinsic thermal conductivity (usually not exceeding 30 W / (m·K)). In order to achieve a high thermal conductivity of composite materials, extremely high filler loading (often ≥90wt%) is required. However, high loading leads to a sharp increase in system viscosity, which seriously damages the processing fluidity and construction performance of the material. (2) Limited interfacial interconnection between thermally conductive fillers and silicone oil matrix. Commonly used inorganic thermally conductive fillers have poor interfacial compatibility with silicone matrix. Although diamond has extremely high intrinsic thermal conductivity (single crystal diamond can reach 2200W / (m·K)), it has few surface functional groups, is not easy to modify, and has poor compatibility with silicone resin. Boron nitride (BN) has a highly chemically inert surface and its interfacial compatibility with the organosilicon matrix is ​​significantly insufficient. BN particles are prone to agglomeration in polymers, making it difficult to form a continuous thermally conductive network. Carbon nanotubes (CNTs) also have a serious tendency to agglomerate and poor compatibility with silicone rubber. Poor interfacial compatibility leads to a significant phonon scattering effect at the inorganic / organic interface, which seriously weakens the overall thermal conductivity. Although aluminum nitride has a high intrinsic thermal conductivity (theoretical value can reach 320 W / (m·K)), it is extremely easy to hydrolyze and its compatibility with the silicone rubber matrix is ​​not ideal. (3) Poor aging stability. Under long-term high-temperature working conditions, the small molecule reagents in the formulation of the thermally conductive gel are prone to volatilization, which leads to hardening, cracking or even failure of the thermally conductive gel. At the same time, when exposed to environmental factors such as oxygen and water vapor, the thermally conductive gel may age, yellow, etc., leading to a decrease in thermal conductivity or failure. In addition, thermally conductive fillers are prone to phase separation from the base polymer during long-term use, which further leads to increased hardness and decreased heat dissipation performance, seriously affecting the service life of electronic components.

[0004] Although researchers have attempted to improve thermal conductivity by combining different types of fillers, existing technologies generally suffer from insufficient surface modification of fillers, lack of effective bridging methods between different fillers, and insufficient stability of the matrix crosslinking network. As a result, the thermal conductivity of the final material is only slightly improved, and the overall performance degrades significantly under long-term high-temperature aging conditions.

[0005] In view of this, there is an urgent need to develop a thermally conductive silicone gel material that combines high thermal conductivity, good processing fluidity, and excellent aging resistance. Summary of the Invention

[0006] The purpose of this invention is to provide a thermally conductive silicone gel, its preparation method, and its application, thereby solving the problems of limited intrinsic thermal conductivity of fillers, insufficient interconnection between fillers and matrix, and poor aging stability in the prior art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a thermally conductive silicone gel, which is composed of component A and component B; Component A comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 3-15 parts epoxy chain extender, and 0.1-1 parts platinum group catalyst. Component B comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 10-40 parts hydrogen-containing silicone oil, and 0.05-0.5 parts inhibitor.

[0008] Preferably, the modified diamond micro powder is prepared by: The modified diamond powder is obtained by mixing the diamond micro powder solution with the first silane coupling agent, adjusting the pH value, and then reacting.

[0009] Preferably, the solvent of the diamond micro powder solution is an ethanol solution with a concentration of 70-90%, and the ratio of diamond micro powder, solvent and first silane coupling agent is 100g:400-500mL:1-2.5g. The first silane coupling agent is one or more of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane; The pH value is 3.5~5.5, the reaction time is 2~6 hours, and the reaction temperature is 50~70℃.

[0010] Preferably, the method for preparing the modified boron nitride micro powder is as follows: The modified boron nitride micro powder is obtained by mixing hexagonal boron nitride micro powder solution with a second silane coupling agent, adjusting the pH value, and then reacting. The solvent for the hexagonal boron nitride micro powder solution is an ethanol solution with a concentration of 70-90%. The ratio of hexagonal boron nitride micro powder, solvent, and second silane coupling agent is 100g:450-550mL:2-4g. The second silane coupling agent is one or more of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane; The pH value is 4-5, the reaction time is 3-8 hours, and the reaction temperature is 60-80℃.

[0011] Preferably, the modified carbon nanotubes are prepared by: Carbon nanotubes are carboxylated, and then the carboxylation product, organic solvent, third silane coupling agent and condensing agent are mixed and reacted to obtain modified carbon nanotubes.

[0012] Preferably, the carboxylation treatment involves mixing carbon nanotubes with a mixed acid. The mass-to-volume ratio of carbon nanotubes to mixed acid is 8-12 g: 120-160 mL; The mixed acid includes concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 2.8~3.2:1; The mixing treatment time is 2~6 hours, and the mixing treatment temperature is 60~80℃.

[0013] Preferably, the ratio of carbon nanotubes, organic solvent, third silane coupling agent, and condensing agent is 8~12g:180~200mL:0.5~0.8g:0.3~0.6g; The organic solvent is N,N-dimethylformamide, the third silane coupling agent is 3-aminopropyltriethoxysilane, and the condensing agent is dicyclohexylcarbodiimide; The reaction time is 12-24 hours, and the reaction temperature is 80-100℃.

[0014] The present invention also provides a method for preparing the thermally conductive silicone gel, the method comprising the following steps: 1) Mix the raw materials according to the above-mentioned mass proportions to obtain component A and component B respectively; 2) Mix components A and B and then cure to obtain thermally conductive silicone gel.

[0015] Preferably, in step 2), the mass ratio of component A to component B is 0.8~1.2:1; The curing temperature is 25~80℃, and the curing time is 0.5~4h.

[0016] The present invention also provides the application of the thermally conductive silicone gel in the field of heat dissipation of microelectronic devices.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs a three-dimensional synergistic thermal conductivity network by scientifically combining four high thermal conductivity fillers: modified diamond, modified boron nitride, aluminum nitride, and modified carbon nanotubes. Diamond provides the core thermal conductivity framework, boron nitride expands the in-plane thermal conductivity pathways with its two-dimensional layered structure, spherical aluminum nitride fills the gaps between particles to increase the filling density, and carbon nanotubes bridge the filler particles with their fibrous structure. The four components produce a significant synergistic thermal conductivity enhancement effect.

[0018] After treatment with a silane coupling agent, diamond changes from oleophobic to oleophilic. Boron nitride achieves chemical bonding and embedding during the curing process through a vinyl silane coupling agent. Carbon nanotubes participate in the cross-linking reaction by covalently grafting silane coupling agents. The silicon-containing oxide layer on the surface of aluminum nitride both prevents hydrolysis and enhances compatibility. These modification measures fundamentally solve the interfacial compatibility problem between inorganic fillers and the organosilicon matrix, significantly reducing interfacial phonon scattering and interfacial thermal resistance.

[0019] The epoxy chain extender of this invention exhibits a multi-layered synergistic effect, including the consumption of active hydroxyl groups, stability of the chemical bonding interface, resistance to cracking of flexible segments, and waterproofing of the aluminum nitride surface. After aging at 150℃ for 1000 hours, its performance retention rate is significantly better than that of existing products.

[0020] This invention achieves high thermal conductivity while maintaining low system viscosity and good flowability through the rational gradation of four fillers with different morphologies and particle sizes, which can meet the requirements of automated dispensing processes for microelectronic device packaging. Detailed Implementation

[0021] This invention provides a thermally conductive silicone gel, which is composed of component A and component B; Component A comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 3-15 parts epoxy chain extender, and 0.1-1 parts platinum group catalyst. Component B comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 10-40 parts hydrogen-containing silicone oil, and 0.05-0.5 parts inhibitor.

[0022] In this invention, the modified diamond micro powder in component A is preferably 80-180 parts by mass, more preferably 100-150 parts, and even more preferably 120-130 parts by mass. The modified boron nitride micro powder is preferably 40-110 parts by weight, more preferably 50-100 parts by weight, and even more preferably 60-80 parts by weight. The aluminum nitride micro powder is preferably 30-70 parts by weight, more preferably 40-60 parts by weight, and even more preferably 50-55 parts by weight. The modified carbon nanotubes are preferably 4 to 14 parts by mass, more preferably 5 to 12 parts by mass, and even more preferably 8 to 10 parts by mass. The epoxy chain extender is preferably 5 to 14 parts by mass, more preferably 6 to 12 parts, and even more preferably 8 to 10 parts. The epoxy chain extender is preferably one or more of bisphenol A diglycidyl ether, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, or polypropylene glycol diglycidyl ether. The platinum-based catalyst is preferably 0.2 to 0.9 parts by mass, more preferably 0.4 to 0.8 parts, and even more preferably 0.5 to 0.6 parts by mass. The platinum-based catalyst is preferably a chloroplatinic acid-isopropanol solution, a platinum(O)-divinyltetramethyldisiloxane complex, or a platinum-cyclovinylmethylsiloxane complex.

[0023] In this invention, the modified diamond micro powder in component B is preferably 80-180 parts by mass, more preferably 100-150 parts, and even more preferably 120-130 parts. The modified boron nitride micro powder is preferably 40-110 parts by mass, more preferably 50-100 parts, and even more preferably 60-80 parts by mass. The aluminum nitride micro powder is preferably 30-70 parts by mass, more preferably 40-60 parts, and even more preferably 50-55 parts by mass. The aluminum nitride micro powder is preferably spherical aluminum nitride micro powder with a particle size of 2-20 μm, more preferably 5-18 μm, and even more preferably 10-15 μm. The modified carbon nanotubes are preferably 4 to 14 parts by mass, more preferably 5 to 12 parts by mass, and even more preferably 8 to 10 parts by mass. The hydrogen-containing silicone oil is preferably 15-35 parts by mass, more preferably 20-30 parts by mass, and even more preferably 25-28 parts by mass. The hydrogen-containing silicone oil is preferably a side-containing hydrogen polymethylhydrosiloxane. The inhibitor is preferably 0.1 to 0.4 parts by mass, more preferably 0.2 to 0.3 parts by mass, and the inhibitor is preferably one or more of 2-phenyl-3-butyn-2-ol, 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, tetramethyltetravinylcyclotetrasiloxane, and tetramethyltetrahydrocyclotetrasiloxane.

[0024] In this invention, the vinyl silicone oil is preferably vinyl-terminated polydimethylsiloxane, the viscosity is preferably 100~5000 mPa·s, more preferably 1000~4000 mPa·s, more preferably 2000~3000 mPa·s, and the vinyl content is preferably 0.1~1.2 wt%, more preferably 0.3~1 wt%, and more preferably 0.5~0.8 wt%.

[0025] In this invention, the epoxy groups of the epoxy chain extender can form chemical bonds or hydrogen bonds with the epoxy groups on the modified diamond surface, acting as a "molecular bridge" to further enhance the interconnection between fillers. The epoxy chain extender can fine-tune the organosilicon crosslinking network through its flexible segments, improving the flexibility and elongation of the gel. At the same time, its high thermal stability can effectively improve the aging resistance of the gel.

[0026] In this invention, the method for preparing the modified diamond micro powder is as follows: The modified diamond powder is obtained by mixing the diamond micro powder solution with the first silane coupling agent, adjusting the pH value, and then reacting.

[0027] In this invention, the particle size of the diamond micro powder is preferably 5~50μm, more preferably 10~40μm, and even more preferably 20~30μm.

[0028] In this invention, the solvent for the diamond micro powder solution is preferably an ethanol solution, and the concentration of the ethanol solution is preferably 70-90%, more preferably 75-85%, and even more preferably 80-82%. The ratio of diamond micro powder, solvent, and first silane coupling agent is preferably 100g:400-500mL:1-2.5g, more preferably 100g:420-480mL:1.2-2g, and even more preferably 100g:450-460mL:1.4-1.8g. The first silane coupling agent is preferably one or more of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane; The pH value is preferably 3.5~5.5, more preferably 3.8~5, and even more preferably 4~4.5. The reagent used to adjust the pH value is acetic acid. The reaction time is preferably 2~6h, more preferably 2.5~5h, and even more preferably 3~4h. The reaction temperature is preferably 50~70℃, more preferably 55~65℃, and even more preferably 60~62℃. After the reaction, the product is washed and dried sequentially. The washing reagent is preferably anhydrous ethanol, and the number of washings is preferably 2 to 5 times, more preferably 3 to 4 times. The drying is preferably vacuum drying, and the vacuum drying temperature is preferably 80 to 100°C, more preferably 85 to 95°C, more preferably 90 to 92°C. The vacuum drying time is preferably 6 to 12 hours, more preferably 7 to 10 hours, more preferably 8 to 9 hours.

[0029] In this invention, the silanol group generated by the hydrolysis of the alkoxy group at one end of the first silane coupling agent molecule undergoes dehydration condensation with the hydroxyl group on the diamond surface to form a Si-OC covalent bond, and the organic functional group at the other end interacts strongly with the organosilicon matrix, thereby achieving chemical bridging between the diamond and the organosilicon matrix. After modification treatment, the diamond surface changes from oleophobic to hydrophilic to oleophilic and hydrophobic, which greatly improves the compatibility with the silicone oil matrix.

[0030] In this invention, the method for preparing the modified boron nitride micro powder is as follows: The modified boron nitride micro powder is obtained by mixing hexagonal boron nitride micro powder solution with a second silane coupling agent, adjusting the pH value, and then reacting. The solvent for the hexagonal boron nitride micro powder solution is preferably an ethanol solution, and the concentration of the ethanol solution is preferably 70-90%, more preferably 75-85%, and even more preferably 80-82%. The ratio of hexagonal boron nitride micro powder, solvent, and second silane coupling agent is preferably 100g:450-550mL:2-4g, more preferably 100g:460-520mL:2.5-3.5g, and even more preferably 100g:480-500mL:3-3.2g. The second silane coupling agent is preferably one or more of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane; The pH value is preferably 4-5, more preferably 4.2-4.8, and even more preferably 4.5-4.6. The reagent used to adjust the pH value is acetic acid. The reaction time is preferably 3-8 hours, more preferably 4-7 hours, and even more preferably 5-6 hours. The reaction temperature is preferably 60-80°C, more preferably 65-75°C, and even more preferably 70-72°C. After the reaction, the product is washed and dried sequentially. The washing reagent is preferably anhydrous ethanol, and the number of washings is preferably 2 to 5 times, more preferably 3 to 4 times. The drying is preferably vacuum drying, and the vacuum drying temperature is preferably 80 to 100°C, more preferably 85 to 95°C, more preferably 90 to 92°C. The vacuum drying time is preferably 6 to 12 hours, more preferably 7 to 10 hours, more preferably 8 to 9 hours.

[0031] In this invention, the flake diameter of the hexagonal boron nitride micro powder is preferably 3~30μm, more preferably 5~25μm, and even more preferably 10~20μm.

[0032] In this invention, the silanol groups generated by the hydrolysis of the second silane coupling agent molecule undergo dehydration condensation with the hydroxyl groups at defects on the BN surface, forming stable Si-OB covalent bonds anchored to the BN surface. Simultaneously, the vinyl functional groups at the other end of the silane can participate in cross-linking and curing during subsequent hydrosilylation reactions, allowing BN particles to be chemically bonded into the organosilicon cross-linked network, significantly reducing interfacial phonon scattering effects. Furthermore, the organification of the BN surface after vinyl coupling agent treatment effectively suppresses filler agglomeration through steric hindrance.

[0033] In this invention, the method for preparing the modified carbon nanotubes is as follows: Carbon nanotubes are carboxylated, and then the carboxylation product, organic solvent, third silane coupling agent and condensing agent are mixed and reacted to obtain modified carbon nanotubes.

[0034] In this invention, the diameter of the carbon nanotubes is preferably 10-50 nm, more preferably 20-40 nm, and even more preferably 30-35 nm.

[0035] In this invention, the carboxylation treatment is preferably performed by mixing carbon nanotubes with a mixed acid; The preferred mass-to-volume ratio of carbon nanotubes to mixed acid is 8-12g:120-160mL, more preferably 9-11g:130-150mL, and even more preferably 10g:135-140mL; The mixed acid preferably includes concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is preferably 2.8~3.2:1, more preferably 2.9~3.1:1, and even more preferably 3:1; The mixing treatment time is preferably 2 to 6 hours, more preferably 2.5 to 5 hours, and even more preferably 3 to 4 hours. The mixing treatment temperature is preferably 60 to 80°C, more preferably 65 to 75°C, and even more preferably 68 to 70°C. After mixing, the resulting product is preferably washed and dried. The washing reagent is preferably water. Washing is stopped when the pH of the filtrate is neutral. Drying is preferably vacuum drying. The vacuum drying time is preferably 10-14 h, more preferably 11-13 h, and more preferably 12 h. The drying temperature is preferably 70-90 °C, more preferably 75-85 °C, and more preferably 78-80 °C.

[0036] In this invention, the preferred ratio of carbon nanotubes, organic solvent, third silane coupling agent, and condensing agent is 8-12g:180-200mL:0.5-0.8g:0.3-0.6g, more preferably 9-11g:185-195mL:0.55-0.7g:0.35-0.55g, and even more preferably 10g:190mL:0.6-0.65g:0.4-0.45g; The organic solvent is preferably N,N-dimethylformamide, the third silane coupling agent is preferably 3-aminopropyltriethoxysilane, and the condensing agent is preferably dicyclohexylcarbodiimide. The reaction time is preferably 12-24 h, more preferably 14-20 h, and even more preferably 16-18 h; the reaction temperature is preferably 80-100 °C, more preferably 85-95 °C, and even more preferably 90-92 °C. After the reaction, the product is preferably washed and dried sequentially. Washing is preferably done first with N,N-dimethylformamide and then with anhydrous ethanol. The number of washes is preferably 2 to 5, more preferably 3 to 4. Drying is preferably vacuum drying. The temperature of vacuum drying is preferably 60 to 80°C, more preferably 65 to 75°C, and more preferably 70 to 72°C. The time of vacuum drying is preferably 12 to 24 hours, more preferably 14 to 22 hours, and more preferably 16 to 20 hours.

[0037] In this invention, the carboxylation treatment involves introducing carboxyl groups onto the carbon nanotubes, facilitating the amidation reaction with the subsequent amino group of the third silane coupling agent, thereby covalently grafting the third silane coupling agent onto the carbon nanotube surface. Compared to traditional physical adsorption or π-π stacking, this covalent grafting method exhibits higher chemical stability and binding strength. The surface-grafted CNTs not only show significantly improved dispersibility, but the active silane groups on their surface also enable them to participate in hydrosilylation reactions during curing, forming a strong chemical crosslink with the organosilicon matrix.

[0038] The present invention also provides a method for preparing the thermally conductive silicone gel, the method comprising the following steps: 1) Mix the raw materials according to the above-mentioned mass proportions to obtain component A and component B respectively; 2) Mix components A and B and then cure to obtain thermally conductive silicone gel.

[0039] In this invention, during the preparation of components A and B, the mixing speed is preferably 500-2000 rpm, more preferably 800-1600 rpm, and even more preferably 1000-1200 rpm, and the mixing time is preferably 30-60 min, more preferably 35-50 min, and even more preferably 40-45 min.

[0040] In this invention, in step 2), the mass ratio of component A to component B is preferably 0.8~1.2:1, more preferably 0.9~1.1:1, and even more preferably 1:1; The curing temperature is preferably 25~80℃, more preferably 30~70℃, and even more preferably 50~60℃. The curing time is preferably 0.5~4h, more preferably 1~3h, and even more preferably 2~2.5h.

[0041] The present invention also provides the application of the thermally conductive silicone gel in the field of heat dissipation of microelectronic devices.

[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] In the embodiments and comparative examples of this invention, the number of parts refers to parts by mass.

[0044] Example 1

[0045] Preparation of modified diamond micro powder: 100 g of diamond micro powder (particle size 20 μm) was added to 500 mL of 90% ethanol solution to obtain a diamond micro powder solution. Then, 2 g of 3-glycidyl etheroxypropyltrimethoxysilane was added, and the pH value was adjusted to 4.5 with acetic acid. The reaction was stirred at 60 °C for 4 h. After the reaction was completed, the mixture was centrifuged and washed three times with anhydrous ethanol. The modified diamond micro powder was obtained by vacuum drying at 90 °C for 8 h. Preparation of modified boron nitride micro powder: 80 g of hexagonal boron nitride micro powder (10 μm in diameter) was added to 400 mL of 90% ethanol solution to obtain a hexagonal boron nitride micro powder solution. Then, 2.4 g of vinyltriethoxysilane was added, and the pH value was adjusted to 4.5 with acetic acid. The reaction was stirred at 70 °C for 6 h. After the reaction was completed, the mixture was centrifuged and washed three times with anhydrous ethanol. The mixture was then vacuum dried at 90 °C for 8 h to obtain the modified boron nitride micro powder. Preparation of modified carbon nanotubes: 10 g of carbon nanotubes were added to 150 mL of mixed acid (concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1) and ultrasonically stirred at 70 °C for 4 h; the filtrate was repeatedly washed with deionized water until the pH of the filtrate was neutral, and then vacuum dried at 80 °C for 12 h to obtain carboxylated carbon nanotubes; 8 g of carboxylated carbon nanotubes were dispersed in 200 mL of N,N-dimethylformamide and ultrasonically dispersed for 45 min; 0.6 g of 3-aminopropyltriethoxysilane and 0.5 g of dicyclohexylcarbodiimide were added; the reaction was stirred at 90 °C for 18 h under nitrogen protection; after the reaction was completed, the filtrate was repeatedly washed with N,N-dimethylformamide and ethanol, and then vacuum dried at 70 °C for 18 h to obtain modified carbon nanotubes; Component A formulation: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 500 mPa·s), 120 parts of modified diamond micro powder, 80 parts of modified boron nitride micro powder, 40 parts of aluminum nitride micro powder, 6 parts of modified carbon nanotubes, 8 parts of 1,4-butanediol diglycidyl ether, and 0.3 parts of platinum(O)-divinyltetramethyldisiloxane complex; Component B formulation: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 500 mPa·s), 120 parts of modified diamond micro powder, 80 parts of modified boron nitride micro powder, 40 parts of aluminum nitride micro powder, 6 parts of modified carbon nanotubes, 20 parts of side-hydrogen-containing polymethylhydrosiloxane, and 0.1 parts of 2-phenyl-3-butyn-2-ol; Preparation of thermally conductive silicone gel: Mix the raw materials of component A at 800 rpm for 45 min to obtain component A, and mix the raw materials of component B at 1000 rpm for 50 min to obtain component B. Mix components A and B in a 1:1 mass ratio, and then cure at 80°C for 1 hour to obtain a thermally conductive silicone gel.

[0046] Example 2

[0047] The formulations of component A and component B in Example 1 were modified as follows: "Component A: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 500 mPa·s), 160 parts of modified diamond micro powder, 60 parts of modified boron nitride micro powder, 50 parts of aluminum nitride micro powder, 10 parts of modified carbon nanotubes, 12 parts of 1,4-butanediol diglycidyl ether, and 0.3 parts of platinum(O)-divinyltetramethyldisiloxane complex; Component B: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 500 mPa·s), 160 parts of modified diamond micro powder, 60 parts of modified boron nitride micro powder, 50 parts of aluminum nitride micro powder, 10 parts of modified carbon nanotubes, 25 parts of side-hydrogenated polymethylhydrosiloxane, and 0.1 parts of 2-phenyl-3-butyn-2-ol;" The other steps are the same as in Example 1.

[0048] Example 3

[0049] In Example 1, “3-glycidyl etheroxypropyltrimethoxysilane” was modified to “3-methacryloxypropyltrimethoxysilane”, “vinyltriethoxysilane” was modified to “vinyltrimethoxysilane”, and “8 parts of 1,4-butanediol diglycidyl ether” was modified to “10 parts of neopentyl glycol diglycidyl ether”. The other steps were the same as in Example 1.

[0050] Comparative Example 1

[0051] Compared with Example 1, no modification was made to the diamond micro powder, boron nitride micro powder, and carbon nanotubes; the other steps were the same as in Example 1.

[0052] Comparative Example 2

[0053] Compared with Example 1, the addition of "1,4-butanediol diglycidyl ether" was omitted, and the other steps were the same as in Example 1.

[0054] Comparative Example 3

[0055] Compared with Example 1, all modified diamond powder was replaced with an equal mass of alumina micro powder (average particle size 10 μm), all modified boron nitride micro powder was replaced with an equal mass of zinc oxide micro powder (average particle size 5 μm), modified carbon nanotubes were not added, and aluminum nitride micro powder was not added. Other steps were the same as in Example 1.

[0056] Comparative Example 4

[0057] Compared to Example 1, the application of modified carbon nanotubes is omitted, while the other steps are the same as in Example 1.

[0058] The thermally conductive silicone gels obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to the following performance tests: Thermal conductivity (W / (m·K)): Tested according to ISO 22007-2:2022 standard. The cured gel sample was made into a disc with a diameter of 30 mm and a thickness of 5 mm. The test temperature was 25℃. The test results are shown in Table 1. Viscosity (Pa·s): Measured using a rotational rheometer (MCR 302, Anton Paar, Austria) at 25°C with a shear rate of 10 s⁻¹. -1 The viscosity of the uncured adhesive after mixing was tested, and the test results are shown in Table 1. Hardness: The hardness of the cured gel was tested using a Shore OO hardness tester according to ASTM D2240 standard. The test results are shown in Table 1. Volume resistivity (Ω·cm): The volume resistivity of the cured gel was tested according to ASTM D257 standard, and the test results are shown in Table 1. High-temperature aging test: The cured gel sample was placed in a constant temperature oven at 150℃ and taken out at 250h, 500h, 750h and 1000h respectively. The changes in thermal conductivity and hardness were tested. The thermal conductivity retention rate was the percentage of the thermal conductivity after aging to the initial thermal conductivity. The test results are shown in Table 2. The hardness change rate was the percentage of the absolute value of the difference between the hardness after aging and the initial hardness to the initial hardness. The test results are shown in Table 3.

[0059] Table 1. Test results of the thermally conductive silicone gel obtained in Examples 1-3 and Comparative Examples 1-4

[0060] As shown in Table 1, the thermal conductivity of Examples 1 and 2 is as high as 11.2 and 13.5 W / (m·K), respectively. Comparative Example 1 (unmodified filler) has a thermal conductivity of only 5.6, demonstrating that filler modification is key to reducing interfacial thermal resistance. Comparative Example 2 (without chain extender) has a thermal conductivity of 8.7, a decrease of 22.3% compared to Example 1, indicating that the chain extender enhances filler interconnection. Comparative Example 3 (traditional filler) has a thermal conductivity of only 3.2, highlighting the significant advantages of the quaternary composite system. Regarding processing performance, Example 1 has a viscosity of 420 Pa·s, meeting the requirements for dispensing. Comparative Example 1's viscosity surges to 750 Pa·s, reflecting poor dispersibility and severe agglomeration of the unmodified filler. Comparative Example 3, while having a low viscosity, does so at the expense of thermal conductivity. The thermal conductivity of Comparative Example 4 (lacking carbon nanotubes) drops to 7.5 W / (m·K), a decrease of approximately 33% compared to Example 1, indicating that the "linear" bridging effect of carbon nanotubes is crucial for constructing continuous thermal conductive pathways; without them, the "point-to-surface" connection cannot be effectively established, significantly increasing thermal resistance.

[0061] Table 2. Thermal conductivity retention rate of the thermally conductive silicone gels obtained in Example 1 and Comparative Examples 1-4

[0062] Table 3. Hardness variation rate of thermally conductive silicone gels obtained in Example 1 and Comparative Examples 1-4

[0063] As shown in Tables 2 and 3, after aging at 150℃ for 1000 hours, Example 1 maintained a thermal conductivity retention rate of 91.6% and a hardness change rate of only 14.5%, demonstrating excellent aging resistance. Comparative Example 1 showed a retention rate of only 58.7% and a hardness change rate as high as 58.3%, indicating severe hardening. Comparative Example 2 maintained a retention rate of 78.5%, showing improvement but still significantly lower than Example 1, confirming the indispensability of epoxy chain extenders. Comparative Example 3 maintained a retention rate of only 52.8%, further demonstrating the significant contribution of the synergistic effect of modified fillers and chain extenders to aging resistance. In Comparative Example 4, after 1000 hours of aging, the thermal conductivity retention rate was 80.3%, and the hardness change rate was 22.7%, with aging resistance also significantly lower than Example 1. This is attributed to the reduction in chemical cross-linking points between fillers and decreased network structure stability after the absence of carbon nanotubes.

[0064] Based on the results of Comparative Examples 1 to 4, it can be fully verified that the four fillers (diamond, boron nitride, aluminum nitride, and carbon nanotubes) form a significant synergistic effect through morphological complementarity and chemical bonding. The absence of any filler will lead to a significant decrease in thermal conductivity and aging resistance.

[0065] In summary, this invention, through a triple approach of synergistic compounding of quaternary high thermal conductivity fillers, targeted surface modification, and enhancement with epoxy chain extenders, outperforms existing technologies in three dimensions: thermal conductivity, processability, and aging resistance. This gel combines high thermal conductivity, good flowability, and excellent aging stability, making it particularly suitable for heat dissipation in microelectronic devices.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A heat-conducting silicone gel, characterized by, The thermally conductive silicone gel is composed of component A and component B; Component A comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 3-15 parts epoxy chain extender, and 0.1-1 parts platinum group catalyst. Component B comprises the following components in parts by weight: 100 parts vinyl silicone oil, 50-200 parts modified diamond micro powder, 30-120 parts modified boron nitride micro powder, 20-80 parts aluminum nitride micro powder, 2-15 parts modified carbon nanotubes, 10-40 parts hydrogen-containing silicone oil, and 0.05-0.5 parts inhibitor.

2. The thermally conductive silicone gel according to claim 1, characterized in that, The method for preparing the modified diamond micro powder is as follows: The modified diamond powder is obtained by mixing the diamond micro powder solution with the first silane coupling agent, adjusting the pH value, and then reacting.

3. The thermally conductive silicone gel according to claim 2, characterized in that, The solvent for the diamond micro powder solution is an ethanol solution with a concentration of 70-90%. The ratio of diamond micro powder, solvent, and first silane coupling agent is 100g:400-500mL:1-2.5g. The first silane coupling agent is one or more of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane and 3-methacryloyloxypropyltrimethoxysilane; The pH value is 3.5~5.5, the reaction time is 2~6 hours, and the reaction temperature is 50~70℃.

4. The thermally conductive silicone gel according to claim 1, characterized in that, The method for preparing the modified boron nitride micro powder is as follows: The modified boron nitride micro powder is obtained by mixing hexagonal boron nitride micro powder solution with a second silane coupling agent, adjusting the pH value, and then reacting. The solvent for the hexagonal boron nitride micro powder solution is an ethanol solution with a concentration of 70-90%. The ratio of hexagonal boron nitride micro powder, solvent, and second silane coupling agent is 100g:450-550mL:2-4g. The second silane coupling agent is one or more of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane; The pH value is 4-5, the reaction time is 3-8 hours, and the reaction temperature is 60-80℃.

5. The thermally conductive silicone gel according to claim 1, characterized in that, The method for preparing the modified carbon nanotubes is as follows: Carbon nanotubes are carboxylated, and then the carboxylation product, organic solvent, third silane coupling agent and condensing agent are mixed and reacted to obtain modified carbon nanotubes.

6. The thermally conductive silicone gel according to claim 5, characterized in that, The carboxylation treatment involves mixing carbon nanotubes with a mixed acid. The mass-to-volume ratio of carbon nanotubes to mixed acid is 8-12 g: 120-160 mL; The mixed acid includes concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 2.8~3.2:1; The mixing treatment time is 2~6 hours, and the mixing treatment temperature is 60~80℃.

7. The thermally conductive silicone gel according to claim 5 or 6, characterized in that, The ratio of carbon nanotubes, organic solvent, third silane coupling agent, and condensing agent is 8~12g:180~200mL:0.5~0.8g:0.3~0.6g; The organic solvent is N,N-dimethylformamide, the third silane coupling agent is 3-aminopropyltriethoxysilane, and the condensing agent is dicyclohexylcarbodiimide; The reaction time is 12-24 hours, and the reaction temperature is 80-100℃.

8. A method for preparing the thermally conductive silicone gel according to any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: 1) Mix the raw materials according to the above-mentioned mass proportions to obtain component A and component B respectively; 2) Mix components A and B and then cure to obtain thermally conductive silicone gel.

9. The method for preparing a thermally conductive silicone gel according to claim 8, characterized in that, In step 2), the mass ratio of component A to component B is 0.8~1.2:1; The curing temperature is 25~80℃, and the curing time is 0.5~4h.

10. The application of the thermally conductive silicone gel according to any one of claims 1 to 7 in the field of heat dissipation for microelectronic devices.

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