Heat-conducting gel based on Cu-based core-shell structure heat-conducting filler and preparation method of heat-conducting gel

Abstract

The invention relates to the technical field of thermal interface materials, in particular to heat-conducting gel based on Cu-based core-shell structure heat-conducting filler and a preparation method of the heat-conducting gel. The component of the heat-conducting gel comprises a heat-conducting filler with a Cu-based core-shell structure, and the core-shell structure of particles in the heat-conducting filler is as follows: copper particles are used as cores, and a high-heat-conductivity compound is used as a shell; the high-thermal-conductivity compound is aluminum nitride, beryllium oxide, aluminum oxide, boron nitride, silicon carbide, zinc oxide, silicon nitride or magnesium oxide. The preparation method of the heat-conducting gel based on the Cu-based core-shell structure heat-conducting filler comprises the following steps: mixing the polymer matrix, the heat-conducting filler and the cross-linking agent in a heating state according to the formula ratio; after cooling, adding a catalyst and mixing; and carrying out vacuum defoaming to obtain the heat-conducting gel. The nano-copper particles with shells with high heat-conducting property are used as the heat-conducting filler, so that the high heat-conducting property of copper can be exerted, the insulativity and oxidation resistance of the heat-conducting filler can be ensured, and the heat-conducting gel has excellent electric conductivity.

Description

Technical Field

[0001] This invention relates to the field of thermal interface materials technology, and in particular to a thermally conductive gel based on Cu-based core-shell structure thermally conductive filler and its preparation method. Background Technology

[0002] With the rapid development of electronic devices towards higher power and higher integration, their heat flux density has increased dramatically, and heat dissipation has become a core challenge restricting device performance, reliability, and lifespan. Therefore, developing thermal interface materials with high thermal conductivity and low thermal resistance is key to solving thermal management problems.

[0003] Thermally conductive gels combine the advantages of other thermal interface materials, effectively filling gaps. However, existing thermally conductive gels are typically hybrid materials made by combining metallic thermally conductive fillers (such as copper, aluminum, and silver), alumina, magnesium oxide, aluminum nitride, and silicon nitride with a matrix. Metal fillers are highly susceptible to oxidation during processing and use, and their electrical conductivity can potentially cause internal short circuits in electronic devices. Alumina, magnesium oxide, aluminum nitride, and silicon nitride have very low thermal conductivity and poor interfacial bonding with the polymer matrix, significantly impacting the performance of the thermally conductive gel.

[0004] For example, CN119119741A discloses an insulating high thermal conductivity gel and its preparation method, using modified copper powder, modified boron nitride, and nano-metal droplets as thermally conductive fillers. The prepared gel material has a thermal conductivity greater than 6.5 W / (m·K) and a volume resistivity greater than 10⁻⁶. 9 Ω·cm. CN111320967A discloses a high thermal conductivity silicone sealant modified with a multi-level structure filler and its preparation method, using polypropylene fibers, polypropylene particles, and BN nanoparticles as composite thermally conductive fillers, with a thermal conductivity of approximately 1.05 W / (m·K). CN119220102A discloses an aging-resistant organosilicon gel prepared with high thermal conductivity fillers and its preparation method, using boron nitride and silicon nitride as thermally conductive fillers, with a thermal conductivity of 3.5 W / m·K or higher. CN112812753A discloses a high thermal conductivity organosilicon gel with a core-shell structure, using spherical Al2O3 and spherical BN coated with polymethyl methacrylate with a core-shell structure as thermally conductive fillers; the thermal conductivity of the organosilicon in the example is approximately 5 W / m·K. Therefore, the thermal conductivity of existing thermally conductive gels is poor, hindering the development of electronic devices towards high power and high integration.

[0005] In view of this, it is necessary to propose a thermally conductive gel with excellent thermal conductivity. Summary of the Invention

[0006] The purpose of this invention is to propose a thermally conductive gel based on a Cu-based core-shell thermally conductive filler and its preparation method. Using nano-copper particles with a shell having high thermal conductivity as the thermally conductive filler, the high thermal conductivity of copper can be utilized, while ensuring the insulation and oxidation resistance of the thermally conductive filler. This results in a thermally conductive gel with excellent electrical conductivity, meeting the heat dissipation requirements of high-power devices.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A thermally conductive gel based on a Cu-based core-shell thermally conductive filler, the components of which include a Cu-based core-shell thermally conductive filler, wherein the core-shell structure of the particles in the thermally conductive filler is: a copper particle as the core and a highly thermally conductive compound as the outer shell.

[0009] The high thermal conductivity compound is: aluminum nitride, beryllium oxide, aluminum oxide, boron nitride, silicon carbide, zinc oxide, silicon nitride, or magnesium oxide.

[0010] Furthermore, the copper particles have a particle size of 0.05–50 μm, and the thickness of the high thermal conductivity compound shell is 0.5–500 nm.

[0011] Furthermore, thermally conductive fillers are prepared in situ using electrochemical deposition, dual-source electron beam co-evaporation, or co-precipitation methods.

[0012] Furthermore, thermally conductive fillers are prepared by attaching highly thermally conductive compounds to the surface of copper particles using chemical vapor deposition, plasma-enhanced vapor deposition, reactive magnetron sputtering, arc discharge, ion beam sputtering-assisted reactive deposition, microwave plasma synthesis, sol-gel method, redox method, microemulsion method, or biosynthesis.

[0013] The further thermally conductive gel comprises, by weight, 80-150 parts of a polymer matrix, 50-400 parts of a thermally conductive filler, 1-20 parts of a crosslinking agent, and 0.01-5 parts of a catalyst.

[0014] Furthermore, the thermally conductive gel comprises, by weight, 80-130 parts of a polymer matrix, 50-500 parts of a thermally conductive filler, 1-15 parts of a crosslinking agent, and 0.01-3 parts of a catalyst.

[0015] Furthermore, the polymer matrix is ​​any one or more of dimethyl silicone oil, ethyl silicone oil, polystyrene, polyurethane, polydimethylsiloxane, epoxy resin, polyimide, polyvinyl alcohol, polycarbonate, and polystyrene.

[0016] The crosslinking agent is any one or more of ethylenediamine, diethylenetriamine, hexamethylene diisocyanate, dicumyl peroxide, glutaraldehyde, boric acid, pyromellitic dianhydride, phthalic anhydride, and toluene diisocyanate;

[0017] The catalyst is any one or more of boron trifluoride-amine complex, 2-ethyl-4-methylimidazolium, benzyl dimethylamine, dibutyltin dilaurate, stannous octoate, platinum catalyst, organotin compound, tetrabutylammonium bromide, and triethylamine.

[0018] Furthermore, the thermal conductivity of the thermally conductive gel after coating the substrate is ≥15 W / (m·K), and the volume resistivity is ≥0.15 × 10⁻⁶. 12 Ω·cm, thermal resistance ≤0.05Kcm 2 / W.

[0019] A method for preparing a thermally conductive gel, the method being used to prepare the above-mentioned thermally conductive gel based on a Cu-based core-shell structure thermally conductive filler, the method comprising the following steps:

[0020] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount;

[0021] (2) After cooling, add the catalyst and mix.

[0022] (3) Vacuum degassing to obtain the thermally conductive gel.

[0023] Furthermore, in step (1), the temperature of the mixer is 40-80℃, the rotation speed is 100-1500 r / min, and the time is 10-180 min;

[0024] In step (2), the temperature is lowered to about 25-30°C, and a catalyst is added for mixing.

[0025] The technical solution provided by this invention may include the following beneficial effects:

[0026] This technical solution fully utilizes the high thermal conductivity of copper by coating the surface of copper particles with a high thermal conductivity compound shell, significantly improving the thermal conductivity efficiency of the thermally conductive gel. The high thermal conductivity compound shell also effectively prevents oxidation of the copper particles and provides electrical insulation, avoiding the risk of short circuits in electronic devices, improving the long-term stability of the thermally conductive filler, and extending the service life of the thermally conductive gel.

[0027] Compared to traditional thermally conductive fillers, the core-shell structured thermally conductive filler in this invention optimizes the interfacial bonding force between the filler and the polymer matrix, enabling more efficient heat transfer, reducing interfacial thermal resistance, improving overall heat dissipation performance, and effectively improving the dispersion uniformity of copper particles in the polymer matrix, preventing filler agglomeration and enhancing the overall stability of the material's performance. The thermally conductive gel of this invention, based on a Cu-based core-shell structured thermally conductive filler, achieves a thermal conductivity exceeding 15 W / (m·K) while also possessing excellent thermal resistivity, meeting the heat dissipation requirements of high-power devices and promoting the development of electronic devices towards high power and high integration. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the present invention.

[0029] An embodiment of the present invention provides a thermally conductive gel based on a Cu-based core-shell thermally conductive filler, the composition of which includes a Cu-based core-shell thermally conductive filler, wherein the core-shell structure of the particles in the thermally conductive filler is: a copper particle as the core and a highly thermally conductive compound as the outer shell.

[0030] The high thermal conductivity compound is: aluminum nitride, beryllium oxide, aluminum oxide, boron nitride, silicon carbide, zinc oxide, silicon nitride, or magnesium oxide.

[0031] This technical solution fully utilizes the high thermal conductivity of copper by coating the surface of copper particles with a high thermal conductivity compound shell, significantly improving the thermal conductivity efficiency of the thermally conductive gel. The high thermal conductivity compound shell also effectively prevents oxidation of the copper particles and provides electrical insulation, avoiding the risk of short circuits in electronic devices, improving the long-term stability of the thermally conductive filler, and extending the service life of the thermally conductive gel.

[0032] Compared to traditional thermally conductive fillers, the core-shell structured thermally conductive filler in this invention optimizes the interfacial bonding force between the filler and the polymer matrix, enabling more efficient heat transfer, reducing interfacial thermal resistance, and improving overall heat dissipation performance. The thermally conductive gel of this invention, based on a Cu-based core-shell structured thermally conductive filler, achieves a thermal conductivity exceeding 15 W / (m·K) while also possessing excellent thermal resistivity, meeting the heat dissipation requirements of high-power devices and promoting the development of electronic devices towards high power and high integration.

[0033] Specifically, aluminum nitride (AlN), beryllium oxide (BeO), aluminum oxide (Al2O3), boron nitride (BN), silicon carbide (SiC), zinc oxide (ZnO), silicon nitride (Si3N4), and magnesium oxide (MgO) all possess excellent insulation properties with a volume resistivity >10. 12 The thermal conductivity is excellent, with a thermal conductivity of Ω·cm. Among them, BeO, c-BN, and SiC exhibit ultra-high thermal conductivity; AlN has a thermal conductivity of 170-230 W / (m·K), while Al2O3, Si3N4, MgO, ZnO, and h-BN have thermal conductivity between 20-40 W / (m·K), also making them relatively good thermal conductive materials. Therefore, this scheme uses BeO, c-BN, Si, AlN, Al2O3, Si3N4, MgO, ZnO, and BN as shell materials, enabling the thermally conductive gel to possess excellent thermal conductivity.

[0034] Inorganic shell materials, acting as thermal conductive materials between the copper core and the polymer matrix, significantly reduce local temperature differences, thereby reducing stress caused by local overheating and improving the long-term stability of the thermally conductive gel.

[0035] Preferably, the copper particles have a particle size of 0.05–50 μm, and the thickness of the high thermal conductivity compound shell is 0.5–500 nm.

[0036] The particle size of the copper particles and the thickness of the high thermal conductivity compound shell determine the particle size of the thermally conductive filler. Smaller particles are suitable for thin coatings, forming a high-density thermally conductive network and reducing interfacial thermal resistance. Larger particles are suitable for thick coatings, improving overall thermal conductivity through continuous thermal channels. While ensuring the insulation performance of the thermally conductive filler, a smaller high thermal conductivity compound shell results in better thermal conductivity of the thermally conductive gel. This design limits the thickness of the high thermal conductivity compound shell to 0.5–500 nm, ensuring the insulation performance of the thermally conductive filler, its anti-oxidation properties for the copper particles, and preventing an excessively thick shell from reducing thermal conduction between the copper particles and the molecular matrix.

[0037] In one embodiment of the present invention, thermally conductive fillers are prepared in situ using electrochemical deposition, dual-source electron beam co-evaporation, or co-precipitation. The preparation efficiency of the thermally conductive fillers is high. Specifically, when preparing thermally conductive fillers in situ using dual-source electron beam co-evaporation, firstly, copper source evaporation material and shell evaporation material are prepared. Crucibles containing both materials are placed in the equipment, and the electron beam power is turned on separately to obtain nano-copper particles. Then, the shell evaporation material is applied to cover the surface of the nano-copper particles to obtain a thermally conductive filler based on a Cu-based core-shell structure.

[0038] In one embodiment of the present invention, a thermally conductive filler is prepared by attaching a highly thermally conductive compound to the surface of copper particles using chemical vapor deposition, plasma-enhanced vapor deposition, reactive magnetron sputtering, arc discharge, ion beam sputtering-assisted reactive deposition, microwave plasma synthesis, sol-gel method, redox method, microemulsion method, or biosynthesis.

[0039] In one embodiment of the present invention, the thermally conductive gel comprises, by weight, 80-150 parts of a polymer matrix, 50-400 parts of a thermally conductive filler, 1-20 parts of a crosslinking agent, and 0.01-5 parts of a catalyst.

[0040] This solution limits the formulation amounts of polymer matrix, thermally conductive filler, crosslinking agent, and catalyst to achieve thermally conductive gels with suitable flowability and excellent thermal conductivity.

[0041] Preferably, its components by weight include 80-130 parts of polymer matrix, 50-500 parts of thermally conductive filler, 1-15 parts of crosslinking agent and 0.01-3 parts of catalyst.

[0042] Preferably, the polymer matrix is ​​any one or more of dimethyl silicone oil, ethyl silicone oil, polystyrene, polyurethane, polydimethylsiloxane, epoxy resin, polyimide, polyvinyl alcohol, polycarbonate and polystyrene;

[0043] The crosslinking agent is any one or more of ethylenediamine, diethylenetriamine, hexamethylene diisocyanate, dicumyl peroxide, glutaraldehyde, boric acid, pyromellitic dianhydride, phthalic anhydride, and toluene diisocyanate;

[0044] The catalyst is any one or more of boron trifluoride-amine complex, 2-ethyl-4-methylimidazolium, benzyl dimethylamine, dibutyltin dilaurate, stannous octoate, platinum catalyst, organotin compound, tetrabutylammonium bromide, and triethylamine.

[0045] Specifically, the correspondence between the polymer matrix, crosslinking agent, and catalyst is shown in the table below.

[0046]

[0047] When the polymer matrix is ​​one or more of dimethyl silicone oil, polydimethylsiloxane, polycarbonate and polystyrene, dicumyl peroxide is used as the crosslinking agent and a platinum catalyst is used.

[0048] The thermal conductivity of the thermally conductive gel of the present invention, after being coated on the substrate, is ≥15 W / (m·K), and the volume resistivity is ≥0.15 × 10⁻⁶. 12 Ω·cm, thermal resistance ≤0.05Kcm 2 / W. This thermally conductive gel possesses excellent thermal conductivity and insulation properties, meeting the heat dissipation requirements of high-power devices and promoting the development of electronic devices towards high power and high integration. The conductive gel of this invention is coated between the chip and the heat sink, with a coating thickness of 0.1–2 mm.

[0049] Accordingly, the present invention provides a method for preparing a thermally conductive gel, which is used to prepare the above-mentioned thermally conductive gel based on a Cu-based core-shell structure thermally conductive filler. The method includes the following steps:

[0050] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount;

[0051] (2) After cooling, add the catalyst and mix.

[0052] (3) Vacuum degassing to obtain the thermally conductive gel.

[0053] The thermally conductive gel obtained by the above method possesses excellent thermal conductivity and insulation properties. Mixing the polymer matrix, thermally conductive filler, and crosslinking agent under heating conditions ensures more uniform dispersion of the thermally conductive filler in the system. Adding the catalyst after cooling allows for easier control of the reaction rate. This method is simple in procedure.

[0054] Furthermore, in step (1), the temperature of the mixer is 40-80℃, the rotation speed is 100-1500 r / min, and the time is 10-180 min;

[0055] In step (2), the temperature is lowered to about 25-30°C, and a catalyst is added for mixing.

[0056] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to conventional methods and conditions or according to the product instructions. Unless otherwise specified, the reagents are commercially available; and the performance of products from different sources does not have a significant impact.

[0057] Example 1

[0058] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0059]

[0060] In this embodiment, Cu@AlN particles are prepared by electrochemical deposition: copper chloride is used as the copper source, hydrogen (H2) is used as the reducing gas, and argon is used as the carrier gas;

[0061] First, by adjusting the evaporation rate of the CuCl2 precursor, spherical copper particles with a diameter of approximately 0.05 μm were obtained.

[0062] Then, the supply of copper chloride was stopped, and trimethylaluminum was used as the aluminum source and ammonia as the reducing gas.

[0063] After modifying the deposition parameters, a layer of aluminum nitride shell with a thickness of about 0.5 nm was finally coated on the copper particles, and Cu@AlN particles were obtained after cooling to room temperature.

[0064] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0065] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating conditions according to the formula amount. The temperature of the mixer is 50℃, the speed is 800r / min, and the time is 60min.

[0066] (2) After cooling to about 30°C, add the catalyst and mix for 30 minutes;

[0067] (3) Vacuum degassing to obtain the thermally conductive gel.

[0068] The prepared thermally conductive gel was coated between the chip and the heat sink with a coating thickness of 0.1 mm. After testing, the thermal conductivity was measured to be 62 W / (m·K), and the volume resistivity was 0.15 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.003Kcm 2 / W.

[0069] Example 2

[0070] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0071]

[0072] In this embodiment, a shell layer is attached to copper particles using chemical vapor deposition, as detailed below:

[0073] Copper nanoparticles were prepared by sol-gel method: copper nitrate was first dissolved in anhydrous ethanol, then citric acid was added and stirred until completely dissolved. The solution was then evaporated in a 60°C water bath to form a blue gel. After calcination at 600°C for 2 hours under argon protection, copper particles with a particle size of 0.2 μm were obtained.

[0074] A shell was attached to copper particles using chemical vapor deposition: boron trichloride was selected as the precursor, and ammonia was selected as the gas. By adjusting the deposition parameters, a boron nitride shell with a thickness of 2 nm was finally coated on the copper particles.

[0075] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0076] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount. The temperature of the mixer is 70℃, the speed is 1200r / min, and the time is 90min.

[0077] (2) After cooling to about 30°C, add the catalyst and mix for 20 minutes;

[0078] (3) Vacuum degassing to obtain the thermally conductive gel.

[0079] The prepared thermally conductive gel was coated between the chip and the heat sink with a thickness of 0.3 mm. After testing, the thermal conductivity was measured to be 55 W / (m·K), and the volume resistivity was 0.5 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.008Kcm 2 / W.

[0080] Example 3

[0081] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0082]

[0083] In this embodiment, a shell layer is attached to the surface of copper particles using reactive magnetron sputtering:

[0084] Copper particles were prepared by reduction method: silver acetate was added to ethylene glycol and stirred to obtain a first mixture. Then ascorbic acid was added to ethylene glycol and stirred to obtain a second mixture. The two mixtures were stirred to obtain a copper suspension. After centrifugation and drying, copper particles with a particle size of about 1 μm were obtained.

[0085] A shell layer was attached to the surface of copper particles using reactive magnetron sputtering: the target material was set to aluminum, the sputtering parameters were adjusted, and the collected copper particles were placed on the substrate so that a layer of aluminum was covered on the copper particles. Then, through a passivation reaction, an aluminum oxide shell with a thickness of about 10 nm was finally coated on the copper particles.

[0086] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0087] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount. The temperature of the mixer is 40℃, the speed is 500r / min, and the time is 120min.

[0088] (2) After cooling to about 25°C, add the catalyst and mix for 15 minutes;

[0089] (3) Vacuum degassing to obtain the thermally conductive gel.

[0090] The prepared thermally conductive gel was coated between the chip and the heat sink with a coating thickness of 0.8 mm. After testing, the thermal conductivity was measured to be 43 W / (m·K), and the volume resistivity was 3 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.015Kcm 2 / W.

[0091] Example 4

[0092] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0093]

[0094] The preparation method of the Cu-based core-shell thermally conductive filler in this embodiment is as follows:

[0095] Copper particles were prepared by microemulsion method: cyclohexane and sorbitan oleate were prepared as oil phase and copper sulfate as aqueous phase. The aqueous phase was then added dropwise to the oil phase and ultrasonically emulsified to form a microemulsion. Hydrazine hydrate was added as a reducing agent and stirred to obtain 8 μm copper particles.

[0096] A shell layer was attached to the surface of copper particles using the sol-gel method: a TEOS-sucrose solution was prepared, copper particles were added and ultrasonically dried, and then the copper particles were immersed in the TEOS-sucrose solution. Finally, a silicon carbide shell layer with a thickness of 80 nm was coated on the copper particles.

[0097] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0098] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount. The temperature of the mixer is 80℃, the speed is 1500r / min, and the time is 180min.

[0099] (2) After cooling to about 30°C, add the catalyst and mix for 10 min;

[0100] (3) Vacuum degassing to obtain the thermally conductive gel.

[0101] The prepared thermally conductive gel was coated between the chip and the heat sink with a coating thickness of 1 mm. After testing, the thermal conductivity was measured to be 35 W / (m·K), and the volume resistivity was 2.3 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.01Kcm 2 / W.

[0102] Example 5

[0103] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0104]

[0105] The preparation method of the Cu-based core-shell thermally conductive filler in this embodiment is as follows:

[0106] Copper particles were prepared by electrochemical deposition: copper sulfate was first prepared as an electrolyte, and after adjusting the deposition parameters, the particles were ultrasonically cleaned and dried to obtain copper particles with a particle size of 25 μm.

[0107] Copper particles are immersed in a magnesium nitrate solution using a wet chemical method, ultrasonically dispersed, and ammonia is added to adjust the pH value to generate a precipitate. After calcination in an air atmosphere, the copper particles are finally coated with a magnesium oxide shell with a thickness of about 250 nm.

[0108] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0109] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount. The temperature of the mixer is 55℃, the speed is 100r / min, and the time is 10min.

[0110] (2) After cooling to about 25°C, add the catalyst and mix for 5 minutes;

[0111] (3) Vacuum degassing to obtain the thermally conductive gel.

[0112] The prepared thermally conductive gel was coated between the chip and the heat sink with a thickness of 1.5 mm. After testing, the thermal conductivity was measured to be 28 W / (m·K), and the volume resistivity was 3.2 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.02Kcm 2 / W.

[0113] Example 6

[0114] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0115]

[0116] In this embodiment, a Cu-based core-shell thermally conductive filler was prepared by dual-source electron beam co-evaporation. The size of the copper particles in the Cu-based core-shell structure was 50 μm, and the thickness of the silicon carbide shell was 500 nm.

[0117] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0118] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount. The temperature of the mixer is 80℃, the speed is 1500r / min, and the time is 180min.

[0119] (2) After cooling to about 25°C, add the catalyst and mix for 25 minutes;

[0120] (3) Vacuum degassing to obtain the thermally conductive gel.

[0121] The prepared thermally conductive gel was coated between the chip and the heat sink with a coating thickness of 2 mm. After testing, the thermal conductivity was measured to be 15 W / (m·K), and the volume resistivity was 5.5 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.05Kcm 2 / W.

[0122] Example 7

[0123] The thermally conductive gel prepared based on Cu-based core-shell structured metal thermally conductive filler in this embodiment uses raw materials in parts by weight as shown in the table below.

[0124]

[0125] The preparation steps of the Cu-based core-shell thermally conductive filler in this embodiment are as follows:

[0126] Copper particles were prepared by microemulsion method: cyclohexane and sorbitan oleate were prepared as oil phase and copper sulfate as aqueous phase. The aqueous phase was then added dropwise to the oil phase and ultrasonically emulsified to form a microemulsion. After stirring with hydrazine hydrate as a reducing agent, 50 μm copper particles were obtained.

[0127] A shell layer was attached to the surface of copper particles using the sol-gel method: a TEOS-sucrose solution was prepared, copper particles were added and ultrasonically dried, and then the copper particles were immersed in the TEOS-sucrose solution. Finally, a silicon carbide shell layer with a thickness of 500 nm was coated on the copper particles.

[0128] The preparation steps of the thermally conductive gel in this embodiment are as follows:

[0129] (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating conditions according to the formula amount. The temperature of the mixer is 50℃, the speed is 800r / min, and the time is 60min.

[0130] (2) After cooling to about 30°C, add the catalyst and mix.

[0131] (3) Vacuum degassing to obtain the thermally conductive gel.

[0132] The prepared thermally conductive gel was coated between the chip and the heat sink with a coating thickness of 0.1 mm. After testing, the thermal conductivity was measured to be 18 W / (m·K), and the volume resistivity was 4.2 × 10⁻⁶. 12 Ω·cm, thermal resistance is 0.04Kcm 2 / W.

[0133] In the description of this specification, references to terms such as "embodiment," "example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0134] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A thermally conductive gel based on a Cu-based core-shell structure thermally conductive filler, characterized in that, Its components include a Cu-based core-shell thermally conductive filler, wherein the core-shell structure of the particles in the thermally conductive filler is: a copper particle as the core and a highly thermally conductive compound as the outer shell; The high thermal conductivity compound is: aluminum nitride, beryllium oxide, aluminum oxide, boron nitride, silicon carbide, zinc oxide, silicon nitride, or magnesium oxide.

2. The thermally conductive gel according to claim 1, characterized in that, The copper particles have a particle size of 0.05–50 μm, and the thickness of the high thermal conductivity compound shell is 0.5–500 nm.

3. The thermally conductive gel according to claim 1, characterized in that, Thermally conductive fillers are prepared in situ using electrochemical deposition, dual-source electron beam co-evaporation, or co-precipitation methods.

4. The thermally conductive gel according to claim 1, characterized in that, Thermally conductive fillers are prepared by attaching highly thermally conductive compounds to the surface of copper particles using chemical vapor deposition, plasma-enhanced vapor deposition, reactive magnetron sputtering, arc discharge, ion beam sputtering-assisted reactive deposition, microwave plasma synthesis, sol-gel method, redox method, microemulsion method, or biosynthesis.

5. The thermally conductive gel according to any one of claims 1 to 4, characterized in that, Its components, by weight, include 80-150 parts of polymer matrix, 50-400 parts of thermally conductive filler, 1-20 parts of crosslinking agent and 0.01-5 parts of catalyst.

6. The thermally conductive gel according to claim 5, characterized in that, Its components, by weight, include 80-130 parts of polymer matrix, 50-500 parts of thermally conductive filler, 1-15 parts of crosslinking agent, and 0.01-3 parts of catalyst.

7. The thermally conductive gel according to claim 5, characterized in that, The polymer matrix is ​​any one or more of dimethyl silicone oil, ethyl silicone oil, polystyrene, polyurethane, polydimethylsiloxane, epoxy resin, polyimide, polyvinyl alcohol, polycarbonate, and polystyrene. The crosslinking agent is any one or more of ethylenediamine, diethylenetriamine, hexamethylene diisocyanate, dicumyl peroxide, glutaraldehyde, boric acid, pyromellitic dianhydride, phthalic anhydride, and toluene diisocyanate; The catalyst is any one or more of boron trifluoride-amine complex, 2-ethyl-4-methylimidazolium, benzyl dimethylamine, dibutyltin dilaurate, stannous octoate, platinum catalyst, organotin compound, tetrabutylammonium bromide, and triethylamine.

8. The thermally conductive gel according to claim 5, characterized in that, The thermal conductivity of the thermally conductive gel after being coated on the substrate is ≥15 W / (m·K), and the volume resistivity is ≥0.15×10⁻⁶. 12 Ω·cm, thermal resistance ≤0.05Kcm 2 / W.

9. A method for preparing a thermally conductive gel, characterized in that, This method is used to prepare the thermally conductive gel based on the Cu-based core-shell structure thermally conductive filler as described in any one of claims 5 to 8. The method includes the following steps: (1) Mix the polymer matrix, thermally conductive filler and crosslinking agent under heating according to the formula amount; (2) After cooling, add the catalyst and mix. (3) Vacuum degassing to obtain the thermally conductive gel.

10. The preparation method according to claim 9, characterized in that, In step (1), the temperature of the mixer is 40-80℃, the rotation speed is 100-1500r / min, and the time is 10-180min; In step (2), the temperature is lowered to about 25-30°C, and a catalyst is added for mixing.

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