Thermally conductive material, method of making and use thereof

Abstract

The application relates to a heat-conducting material and a preparation method and application thereof, and relates to the technical field of power device heat dissipation, in particular to a heat-conducting material and a preparation method and application thereof, to solve the problem that the heat-conducting material in the related art is seriously pulverized under long-term high-temperature conditions and cannot be used for a long time. A heat-conducting material, raw materials of which include: a base material, inorganic heat-conducting fillers, a wetting dispersant, a cage polysilsesquioxane and a thixotropic aid; the base material includes first silicon oil with a viscosity of 20 centipoise to 500 centipoise; the wetting dispersant includes asymmetric silicon oil; the cage polysilsesquioxane has a number average molecular weight of 1200 g / mol to 2600 g / mol, a molecular weight dispersity of 1.0 to 1.6, and an average silicon atom number of 8 to 14 of the compound molecules contained; the thixotropic aid includes second silicon oil containing an epoxy group; in 100 parts of the heat-conducting material by weight, the base material is 3 parts to 4 parts, the inorganic heat-conducting fillers are 91 parts to 96 parts, the cage polysilsesquioxane is 0.5 part to 1.5 part, the wetting dispersant is 1 part to 3 parts, and the thixotropic aid is 0.1 part to 0.5 part.

Description

Technical Field

[0001] This application relates to the field of heat dissipation technology for power devices, and in particular to a thermally conductive material, its preparation method, and its application. Background Technology

[0002] With the global goal of "carbon peaking and carbon neutrality," the rapid development of green energy generation and green vehicles has led to an increasing demand for power generation, charging, and energy storage. Power devices, as electronic devices used to process high-voltage, high-current signals, primarily function to convert, control, and transmit electrical energy. Their core characteristics are the ability to withstand high voltage and current and effectively process electrical energy, making them widely used in power electronic equipment.

[0003] In power device applications, the junction temperature and lifespan of power modules are crucial. Currently used thermal conductive materials suffer from severe pulverization under long-term high-temperature conditions, making them unusable for extended periods. Summary of the Invention

[0004] Based on this, some embodiments of this application provide a thermally conductive material, its preparation method, and its application to solve the problem in related technologies that thermally conductive materials suffer severe pulverization under long-term high-temperature conditions and cannot be used for a long time.

[0005] In a first aspect, a thermally conductive material is provided, the raw materials of which include: a matrix material, an inorganic thermally conductive filler, a wetting and dispersing agent, a cage-type polysilsesquioxane, and a thixotropic additive;

[0006] The matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise; the wetting and dispersing agent includes a silane coupling agent, which includes an asymmetric silicone oil; the cage-type polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol, a molecular weight dispersion of 1.0 to 1.6, and the average number of silicon atoms in the compound molecules contained in the cage-type polysilsesquioxane is 8 to 14; the thixotropic agent includes a second silicone oil containing epoxy groups.

[0007] Based on 100 parts by weight of thermally conductive material, the matrix material comprises 3 to 4 parts, the inorganic thermally conductive filler comprises 91 to 96 parts, the cage-type polysilsesquioxane comprises 0.5 to 1.5 parts, the wetting and dispersing agent comprises 1 to 3 parts, and the thixotropic agent comprises 0.1 to 0.5 parts.

[0008] Among them, the first silicone oil, as the matrix material, plays a role in dispersing and wetting other raw materials of the thermal conductive material, and can adjust the viscosity and flowability of the thermal conductive material, thereby improving the overall storage stability, shape maintenance ability and anti-pumping performance of the thermal conductive material, and reducing the occurrence of dry powder and cracks.

[0009] Wetting and dispersing agents play a role in wetting and dispersing inorganic thermally conductive fillers. Asymmetric silicone oils can improve the dispersion uniformity of inorganic thermally conductive fillers and enhance the interfacial properties, viscosity, abrasion resistance, and reactivity of thermally conductive materials, thereby improving their mechanical properties and overall workability.

[0010] Cage-type polysilsesquioxanes mainly serve to improve the thermal stability and mechanical properties of thermally conductive materials, and can adjust the viscosity, modulus, thermal stability, dispersion properties and thixotropic properties of thermally conductive materials.

[0011] Thixotropic additives mainly improve the thixotropic properties of thermally conductive materials. The epoxy groups in the second silicone oil improve the thixotropic properties of thermally conductive materials by forming hydrogen bonds or other weak interactions with surrounding molecules. At the same time, the second silicone oil can also improve the dispersion properties of inorganic thermally conductive fillers, thereby improving the overall mechanical properties, thermal conductivity, and workability of thermally conductive materials.

[0012] By controlling the proportions of each raw material within the above range, the viscosity, elasticity, plasticity, thixotropic properties, and workability of the thermal conductive material can be comprehensively adjusted to obtain a non-curing thermal conductive material with excellent thixotropic properties, good elasticity and plasticity, and good workability.

[0013] In summary, by mixing the aforementioned matrix material, inorganic thermally conductive filler, wetting and dispersing agent, cage-type polysilsesquioxane, and thixotropic agent in a certain mass ratio, the matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise; the wetting and dispersing agent includes a silane coupling agent, which includes asymmetric silicone oil; the cage-type polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol and a molecular weight dispersion of 1.0 to 1.6; the average number of silicon atoms in the compound molecules contained in the cage-type polysilsesquioxane is 8 to 14; and the thixotropic agent includes a second silicone oil containing epoxy groups. Therefore, the matrix material, wetting and dispersing agent, cage-type... Polysilsesquioxane and thixotropic agents can effectively wet and disperse inorganic thermally conductive fillers, thereby preparing a uniform paste-like thermally conductive material with suitable viscosity. Simultaneously, the raw materials in this thermally conductive material synergistically impart excellent thermal conductivity, thixotropic properties, shape retention, and resistance to molecular chain separation and material flow. This makes the thermally conductive material easy to apply, with good storage stability and anti-pumping properties. Furthermore, research has found that this thermally conductive material also exhibits good high-temperature resistance, maintaining shape stability during long-term use and reducing pulverization and cracking. This solves the problem of severe pulverization and unusability of thermally conductive materials under long-term high-temperature conditions in related technologies.

[0014] Optionally, the raw materials satisfy at least one of the following conditions:

[0015] (1) The first silicone oil includes at least one of dimethyl polysiloxane and methylphenyl modified polysiloxane;

[0016] (2) The viscosity of the first silicone oil is 50 centipoise to 200 centipoise;

[0017] (3) The general structural formula of asymmetric silicone oil is shown in the following formula (I), where n is an integer from 36 to 84;

[0018]

[0019] (4) The silane coupling agent also includes at least one of methyltrimethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane and hexadecyltrimethoxysilane, and in the silane coupling agent, the mass percentage of asymmetric silicone oil is greater than or equal to 90%.

[0020] (5) The inorganic thermally conductive filler includes at least one of alumina, boron nitride, aluminum nitride, magnesium oxide and diamond; optionally, the sodium ion content in the inorganic thermally conductive filler is less than 100 ppm;

[0021] (6) The median particle size D50 of the inorganic thermally conductive filler is 0.2μm~100μm;

[0022] (7) The general structural formula of the cage-type polysilsesquioxane is: [RO 1 / 2 ] r [(C 10 H 21 SiO 3 / 2 ] q [PhSiO 3 / 2 ] p Where R is a hydrogen atom; Ph is a phenyl group; q and p are both integers greater than or equal to 1, and the sum of p and q is 8 to 14, and r is an integer from 0 to 1; optionally, the sum of p and q is 8, 10 or 12.

[0023] (8) The second silicone oil includes: tris(epoxypropoxypropyldimethylsiloxy)phenylsilane.

[0024] The choice of primary silicone oil can improve the coating performance, thermal conductivity, high-temperature resistance, and oxidation resistance of the thermally conductive material. The viscosity of the primary silicone oil can further improve its dispersion performance with other raw materials, further adjusting the viscosity and flowability of the thermally conductive material, thus improving its application performance and workability. Asymmetric silicone oils can effectively improve the interfacial properties of the thermally conductive material and effectively adjust its viscosity, adhesion, and abrasion resistance, enhancing its overall performance as a thermal grease material. Adding other silane coupling agents can also improve the wettability and dispersion performance of inorganic thermally conductive fillers. By controlling the mass ratio of asymmetric silicone oil to be greater than or equal to 90%, good dispersion performance of the thermally conductive material can be maintained, preventing clumping or the formation of a dry powder. The cage-like polysilsesquioxane contains phenyl groups, which further enhances its thermal stability. At high temperatures, the phenyl groups reduce the decomposition or degradation of the cage-like polysilsesquioxane. Simultaneously, the rigid structure of the phenyl groups provides additional support and reinforcement, further improving the mechanical strength and properties of the entire thermally conductive material, such as tensile strength and flexural strength, facilitating subsequent construction. Tris(epoxypropoxypropyldimethylsiloxy)phenylsilane contains phenyl groups. The presence of phenyl groups provides this thixotropic agent with a certain degree of rigidity and thermal stability, effectively dispersing the thermal stress on the thermally conductive material and reducing thermal motion at high temperatures, thereby further improving the high-temperature resistance of the thermally conductive material. Furthermore, the siloxy groups in this silane coupling agent endow the thermally conductive material with organosilicon properties, such as good thermal stability, low surface tension, and excellent flexibility.

[0025] Optionally, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, single-crystal alumina and spherical alumina in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts and 69 parts respectively.

[0026] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is dimethyl polysiloxane with a viscosity of 100 centipoise or methyl phenyl modified siloxane with a viscosity of 100 centipoise. The median particle size D50 of the single crystal alumina is 1.5 μm and the sodium ion content is 20 ppm. The median particle size D50 of the spherical alumina is 45 μm and the sodium ion content is 59 ppm.

[0027] Optionally, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, irregular alumina and spherical alumina in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts and 69 parts respectively.

[0028] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of irregular alumina is 2.0 μm, the sodium ion content is 200 ppm, the median particle size D50 of spherical alumina is 43 μm, and the sodium ion content is 300 ppm.

[0029] Optionally, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, single-crystal alumina, spherical alumina and spherical magnesium oxide, in weight amounts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 15 parts, 25 parts and 55 parts, respectively.

[0030] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of single crystal alumina is 1.5 μm, the sodium ion content is 20 ppm, the median particle size D50 of spherical alumina is 45 μm, the sodium ion content is 59 ppm, the median particle size D50 of spherical magnesium oxide is 80 μm and it does not contain sodium ions, or the median particle size D50 of spherical magnesium oxide is 120 μm and it does not contain sodium ions.

[0031] Optionally, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, single-crystal alumina, and spherical alumina in weight parts of 1.0 parts, 0.45 parts, 2.0 parts, 3.05 parts, 26 parts, and 63.5 parts, respectively.

[0032] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the single crystal alumina is 1.5 μm, the sodium ion content is 20 ppm, the median particle size D50 of the spherical alumina is 45 μm, and the sodium ion content is 59 ppm.

[0033] Optionally, the thermally conductive material satisfies at least one of the following conditions:

[0034] (1) The thermally conductive material is a paste;

[0035] (2) The viscosity of the thermally conductive material is 206 Pa·s to 315 Pa·s;

[0036] (3) The thermal conductivity of the thermally conductive material is 5.4 W / m·K to 7.1 W / m·K.

[0037] This thermally conductive material is a uniform paste with suitable viscosity and high thermal conductivity, which can improve its workability and thermal conductivity.

[0038] Secondly, a method for preparing a thermally conductive material is provided, comprising:

[0039] The wetting and dispersing agent and the matrix material are mixed in the first step to prepare a first mixture;

[0040] Inorganic thermally conductive fillers are added to the first mixture in batches for a second mixing process to prepare the second mixture.

[0041] The second mixture is heated to 100℃~200℃ and reacted for 0.5h~2h, then subjected to the first degassing treatment and cooled to room temperature;

[0042] A cage-type polysilsesquioxane and a thixotropic additive are added to a cooled second mixture for a third mixing and followed by a second degassing treatment to prepare a thermally conductive material.

[0043] The definitions of matrix material, wetting and dispersing agent, inorganic thermally conductive filler, cage-type polysilsesquioxane and thixotropic agent are as described in the first aspect.

[0044] A first mixture is prepared by first mixing a wetting and dispersing agent and a matrix material. Then, an inorganic thermally conductive filler is added to the first mixture in batches for a second mixing to obtain a second mixture. This allows the inorganic thermally conductive filler to be uniformly mixed with silicone oil in the presence of a surfactant. Subsequently, the second mixture is reacted at 100℃~200℃ for 0.5~2h by raising the temperature, followed by a first degassing treatment and cooling to room temperature. This allows the inorganic thermally conductive filler to react uniformly with the wetting and dispersing agent and the matrix material, and removes air bubbles from the mixture, thereby improving the dispersion uniformity of the inorganic thermally conductive filler. Finally, cage-type polysilsesquioxane and a thixotropic agent are added to the cooled second mixture for a third mixing and a second degassing treatment. This allows the cage-type polysilsesquioxane and the thixotropic agent to be uniformly mixed with the cooled second mixture, resulting in a uniform paste-like thermally conductive material. The raw materials in this thermally conductive material work synergistically to impart excellent thermal conductivity, thixotropic properties, shape retention, and the ability to prevent molecular chain separation and material flow. This makes the thermally conductive material easy to apply, with good storage stability and anti-pumping properties. Furthermore, research has found that this thermally conductive material also has good high-temperature resistance, maintaining shape stability during long-term use and reducing pulverization and cracking. This solves the problem of severe pulverization and unusability of thermally conductive materials under long-term high-temperature conditions in related technologies.

[0045] Optionally, the preparation method satisfies at least one of the following conditions:

[0046] (1) Each step of the preparation method is carried out in a protective gas atmosphere;

[0047] (2) The first, second and third mixtures were all carried out at room temperature;

[0048] (3) The stirring rate of the first mixing is 100 r / min to 200 r / min, and the time is 10 min to 30 min;

[0049] (4) The stirring rate for the second mixing is 100 r / min to 200 r / min, and the time is 10 min to 30 min;

[0050] (5) The stirring rate of the third mixing is 100 r / min to 200 r / min, and the time is 10 min to 30 min;

[0051] (6) The vacuum degree of the first degassing treatment is less than -0.09 MPa;

[0052] (7) The vacuum degree of the second degassing treatment is less than -0.09 MPa.

[0053] Thirdly, the application of the thermally conductive material as described in the first aspect in heat dissipation of power devices is provided.

[0054] The power device can be a semiconductor power device, which may include, for example, heat-generating elements such as diodes, IGBTs (Insulated-Gate Bipolar Transistors), and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The thermally conductive material can be attached to the power device composed of these heat-generating elements to control the junction temperature of these elements through heat conduction and dissipation, thereby achieving heat dissipation for the power device.

[0055] Compared with related technologies, this application has at least the following beneficial technical effects:

[0056] By mixing the aforementioned matrix material, inorganic thermally conductive filler, wetting and dispersing agent, cage-type polysilsesquioxane, and thixotropic agent in a certain mass ratio, the matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise; the wetting and dispersing agent includes a silane coupling agent, which includes asymmetric silicone oil; the cage-type polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol and a molecular weight dispersion of 1.0 to 1.6; the average number of silicon atoms in the compound molecules contained in the cage-type polysilsesquioxane is 8 to 14; and the thixotropic agent includes a second silicone oil containing epoxy groups. Therefore, the matrix material, wetting and dispersing agent, cage-type polysilsesquioxane, and thixotropic agent are mixed in a specific mass ratio. Semi-siloxanes and thixotropic agents can effectively wet and disperse inorganic thermally conductive fillers, thereby enabling the preparation of a uniform paste-like thermally conductive material with suitable viscosity. Simultaneously, the raw materials in this thermally conductive material synergistically impart excellent thermal conductivity, thixotropic properties, shape retention, and resistance to molecular chain separation and material flow. This makes the thermally conductive material easy to apply, with good storage stability and anti-pumping properties. Furthermore, research has found that this thermally conductive material also exhibits good high-temperature resistance, maintaining shape stability during long-term use and reducing pulverization and cracking. This solves the problem of severe pulverization and unusability of thermally conductive materials under long-term high-temperature conditions in related technologies. Attached Figure Description

[0057] Figure 1 This is a schematic flowchart illustrating a method for preparing a thermally conductive material according to an embodiment of this application. Detailed Implementation

[0058] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0062] In this application, "at least one" means any one, any two, or more of the listed items.

[0063] In this application, the terms "combinations thereof," "any combination thereof," and "any combination thereof" as used include all suitable combinations of any two or more of the listed items.

[0064] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0065] In this application, numerical ranges are involved, and unless otherwise specified, the two endpoints of the numerical range are included.

[0066] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. The final concentration refers to the percentage of the added component in the system after its addition.

[0067] In this application, temperature parameters are involved. Unless otherwise specified, both isothermal processing and processing within a certain temperature range are permitted. The isothermal processing allows temperature fluctuations within the precision range controlled by the instrument.

[0068] To address the problem in related technologies that thermally conductive materials suffer severe pulverization under prolonged high-temperature conditions, making them unsuitable for long-term use, the specific implementation method of this application is described as follows:

[0069] In a first aspect, some embodiments of this application provide a thermally conductive material, the raw materials of which include: a matrix material, an inorganic thermally conductive filler, a wetting and dispersing agent, a cage-like polysilsesquioxane, and a thixotropic agent. The matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise; the wetting and dispersing agent includes a silane coupling agent, which includes asymmetric silicone oil; the cage-like polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol, a molecular weight dispersion of 1.0 to 1.6, and the average number of silicon atoms in the compound molecules contained in the cage-like polysilsesquioxane is 8 to 14; the thixotropic agent includes a second silicone oil containing epoxy groups.

[0070] The first silicone oil, as a base material, possesses inherent thermal conductivity. It acts as a dispersion medium in the thermally conductive material, dispersing other raw materials and adjusting the viscosity and flowability of the material. By limiting the viscosity of the first silicone oil to 20 centipoise to 500 centipoise, it is beneficial to adjust the workability and application properties of the thermally conductive material. This allows the thixotropic properties, viscosity, and flowability of the material to meet different operational requirements, improving its storage stability, shape retention, and anti-pumping properties, while reducing the occurrence of dry powder and cracks.

[0071] Here, the viscosity of the first silicone oil can be measured at room temperature, which can be 20℃ to 35℃. The viscosity of the first silicone oil can be measured using a Brookfield DV2T HB cone-plate viscometer. Taking a room temperature of 25℃ as an example, the specific test method is as follows: at 25℃, take 0.5mL of sample and fill the center of the test pan. Using the cone-plate viscometer, select the 52# rotor and record the sample viscosity at a speed of 1rpm for 2 minutes.

[0072] Because this wetting and dispersing agent includes a silane coupling agent, it possesses both hydrophilic and hydrophobic groups, enabling it to adsorb onto the surface of inorganic thermally conductive filler particles. Through steric hindrance or electrostatic repulsion, it prevents the aggregation of inorganic thermally conductive filler particles, thus ensuring uniform dispersion of the particles among other raw materials. Furthermore, since the silane coupling agent includes asymmetric silicone oil, its unique asymmetric molecular structure, compared to symmetrical silicone oil, allows for better adsorption onto the surface of the inorganic thermally conductive filler, modifying its surface and reducing the interaction forces between them. This improves the dispersion uniformity of the inorganic thermally conductive filler, thereby enhancing the thermal conductivity of the thermally conductive material. Simultaneously, the asymmetric silicone oil effectively improves the interfacial properties, viscosity, wear resistance, and reactivity of the thermally conductive material, thereby enhancing its mechanical properties and overall workability.

[0073] Possicular polysilsesquioxane (POSS) possesses an inorganic core composed of an alternating Si-O silicon-oxygen framework, with Si atoms bonded to R groups at its eight vertices. As the name suggests, POSS refers to a cage-like structure formed by alternating Si-O atoms. R can be organic functional groups attached to the Si atoms, extending outwards; these organic functional groups can be alkyl, aryl, unsaturated groups, etc. As an organic-inorganic hybrid structure, POSS combines the high thermal stability and high modulus of inorganic materials with the processability of organic materials.

[0074] When this cage-shaped polysilsesquioxane is applied to thermally conductive materials, the presence of the inorganic Si-O skeleton in the cage-shaped polysilsesquioxane enables it to withstand high temperatures and maintain good mechanical properties and chemical stability at high temperatures, thereby improving the heat resistance stability of the thermally conductive material. At the same time, the organic functional groups in the cage-shaped polysilsesquioxane can interact with the surface of the inorganic thermally conductive filler, improving the dispersion uniformity of the inorganic thermally conductive filler. Good dispersion enables the inorganic thermally conductive filler to form more contact points and thermal conduction channels, thereby improving the overall thermal conductivity of the thermally conductive material. In addition, cage-type polysilsesquioxanes, relying on their rigid structure, can provide a supporting structure for thermally conductive materials, thereby constructing a more stable and continuous thermally conductive network for inorganic thermally conductive fillers and improving thermal conductivity. At the same time, cage-type polysilsesquioxanes can also bind inorganic thermally conductive fillers and other raw materials in the cage structure, improving the dispersion performance of inorganic thermally conductive fillers, and utilizing the binding effect of the cage structure and the possible reactivity of organic functional groups to improve the overall thixotropic properties of thermally conductive materials.

[0075] The number-average molecular weight of the cage-type polysilsesquioxane is 1200 g / mol to 2600 g / mol, which means that the cage-type polysilsesquioxane has multiple compound molecules with different molecular weights. When the number of molecules is counted, the average molecular weight of the cage-type polysilsesquioxane is 1200 g / mol to 2600 g / mol.

[0076] Molecular weight dispersion is a parameter used to describe the breadth of the molecular weight distribution of a polymer, expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn). The molecular weight dispersion of this cage-like polysilsesquioxane is 1.0–1.6, meaning the ratio of its weight-average molecular weight (Mw) to number-average molecular weight (Mn) is between 1.0 and 1.6. An ideal molecular weight dispersion of 1.0 indicates that the cage-like polysilsesquioxane molecules have uniform molecular weight. When the molecular weight dispersion is greater than 1.0, the cage-like polysilsesquioxane molecules are not uniform in size.

[0077] The molecular structure of this cage-like polysilsesquioxane resembles a cage, with an inorganic framework composed of silicon and oxygen at its center. The number of silicon atoms affects the thermal stability, compatibility with other materials, and other physicochemical properties such as viscosity and rigidity of the cage-like polysilsesquioxane, thereby influencing the properties of the thermally conductive material.

[0078] The average number of silicon atoms in the compound molecules contained in this cage-type polysilsesquioxane is 8 to 14. This means that the silicon atom content in the cage-type polysilsesquioxane molecules varies, and the ratio of the sum of silicon atoms contained in all molecules to the number of molecules can be 8 to 14.

[0079] By limiting the number-average molecular weight, molecular weight dispersion, and the average number of silicon atoms in the compound molecules contained in the cage-like polysilsesquioxane, it is possible to maintain a certain viscosity and modulus of the cage-like polysilsesquioxane. When applied to thermal conductive materials, it can work synergistically with other raw materials to adjust the viscosity, elasticity, thermal conductivity, and thixotropic properties of the thermal conductive filler, thus maintaining the thermal conductive material with good thermal conductivity and workability.

[0080] Thixotropic additives, as the name suggests, are additives that enhance the thixotropic properties of thermally conductive materials. These additives include a second silicone oil containing epoxy groups. These epoxy groups can form hydrogen bonds or other weak interactions with surrounding molecules. Under static conditions, these interactions cause the molecular chains to cross-link, forming a three-dimensional network structure. This increases the viscosity of the thermally conductive material, exhibiting a high-viscosity static state characteristic of thixotropic properties. However, when shear force is applied, these intermolecular interactions are disrupted, allowing molecules to move freely, resulting in a low-viscosity state characteristic of thixotropic properties. Therefore, the addition of this second silicone oil can effectively improve the thixotropic properties of the thermally conductive material.

[0081] Meanwhile, the second silicone oil can also act as a silane coupling agent to establish a good chemical bond between the inorganic thermally conductive filler and other organic raw materials, promote the interaction between the inorganic thermally conductive filler and other organic raw materials, improve the dispersion performance of the inorganic thermally conductive filler, and thus further improve the mechanical and thermal conductivity of the thermally conductive material.

[0082] The second silicone oil may include at least one of terminal epoxy silicone oil, side-chain epoxy silicone oil, and terminal-side epoxy silicone oil.

[0083] Terminal epoxy silicone oil, as the name suggests, has epoxy groups at both ends of the polysiloxane molecular chain; side-chain epoxy silicone oil is silicone oil with epoxy groups attached to the main chain of polysiloxane, and the epoxy groups are distributed in the side chain position of the main chain; end-side epoxy silicone oil has the structural characteristics of both terminal epoxy silicone oil and side-chain epoxy silicone oil, and it contains epoxy groups at both ends of the molecular chain and in the side chain position.

[0084] In some embodiments, based on 100 parts by weight of the thermally conductive material, the matrix material comprises 3 to 4 parts, the inorganic thermally conductive filler comprises 91 to 96 parts, the cage-type polysilsesquioxane comprises 0.5 to 1.5 parts, the wetting and dispersing agent comprises 1 to 3 parts, and the thixotropic agent comprises 0.1 to 0.5 parts.

[0085] In these embodiments, by controlling the proportions of each raw material within the above-mentioned range, the viscosity, elasticity, plasticity, thixotropic properties, and workability of the thermally conductive material can be comprehensively adjusted to obtain a non-curing thermally conductive material with excellent thixotropic properties, good elasticity and plasticity, and good workability.

[0086] In the thermally conductive material provided in the embodiments of this application, the inventors discovered that by mixing the above-mentioned matrix material, inorganic thermally conductive filler, wetting and dispersing agent, cage-type polysilsesquioxane, and thixotropic agent in a certain mass ratio, since the matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise, the wetting and dispersing agent includes a silane coupling agent, which includes asymmetric silicone oil, the cage-type polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol, a molecular weight dispersion of 1.0 to 1.6, and the average number of silicon atoms in the compound molecules contained in the cage-type polysilsesquioxane is 8 to 14; and the thixotropic agent includes a second silicone oil containing epoxy groups, therefore, the matrix material... Materials, wetting and dispersing agents, cage-type polysilsesquioxane, and thixotropic additives can effectively wet and disperse inorganic thermally conductive fillers, thereby preparing a uniform paste-like thermally conductive material with suitable viscosity. Simultaneously, the raw materials in this thermally conductive material synergistically impart good thermal conductivity, thixotropic properties, shape retention properties, and the ability to prevent molecular chain separation and material flow. This makes the thermally conductive material easy to apply, with good storage stability and anti-pumping properties. Furthermore, research has found that this thermally conductive material also has good high-temperature resistance, maintaining shape stability during long-term use and reducing pulverization and cracking, solving the problem of severe pulverization and unusability of thermally conductive materials under long-term high-temperature conditions in related technologies.

[0087] In some embodiments, the first silicone oil comprises at least one of dimethyl polysiloxane and methylphenyl modified polysiloxane.

[0088] Dimethyl polysiloxane is a linear polymer with Si-O bonds as the main chain and methyl groups as side chains. This structure gives it unique properties: the Si-O main chain provides good flexibility and thermal stability, while the methyl side chains impart a degree of hydrophobicity. When used as a base component to disperse other components, it imparts excellent spreadability and thermal conductivity to the thermally conductive material. Methylphenyl-modified polysiloxane is based on polysiloxane, modified by introducing methyl and phenyl groups. The introduction of phenyl groups increases the rigidity and steric hindrance of the molecular chain, stabilizing the molecular structure and giving this first silicone oil good high-temperature resistance and oxidation resistance. Simultaneously, methylphenyl-modified polysiloxane also exhibits good film-forming properties, heat dissipation properties, and waterproof properties.

[0089] In some embodiments, the viscosity of the first silicone oil is 50 centipoise to 200 centipoise.

[0090] In these embodiments, by limiting the viscosity of the first silicone oil to 50 centipoise to 200 centipoise, the dispersion performance of the first silicone oil on other raw materials can be further improved, the viscosity and flowability of the thermally conductive material can be further adjusted, and the construction performance and operability of the thermally conductive material can be improved.

[0091] In some embodiments, the general structural formula of the above-mentioned asymmetric silicone oil is shown in the following formula (I), where n is an integer from 36 to 84;

[0092]

[0093] In these embodiments, the asymmetric silicone oil can effectively improve the interfacial properties of the thermally conductive material and effectively regulate the viscosity, adhesion and wear resistance of the thermally conductive material, thereby improving the overall performance of the thermally conductive material as a silicone grease heat dissipation material.

[0094] In some embodiments, the silane coupling agent further includes at least one of methyltrimethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane, and hexadecyltrimethoxysilane; and in the wetting and dispersing agent, the mass percentage of asymmetric silicone oil is greater than or equal to 90%.

[0095] In these embodiments, the wetting and dispersing properties of inorganic thermally conductive fillers can also be improved by adding other silane coupling agents. By controlling the mass ratio of asymmetric silicone oil to be greater than or equal to 90%, the thermally conductive material can maintain good dispersibility and avoid clumping or dry powder.

[0096] In some embodiments, the structural formula of the above-mentioned cage-like polysilsesquioxane is: [RO 1 / 2 ] r [(C 10 H 21 SiO 3 / 2 ] q [PhSiO 3 / 2 ] p Where R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; Ph is a phenyl group; q and p are both integers greater than or equal to 1, and the sum of p and q is 8 to 14; r is an integer from 0 to 1.

[0097] In these embodiments, the cage-like polysilsesquioxane contains phenyl groups, which can further improve the thermal stability of the polysilsesquioxane. Under high-temperature conditions, phenyl groups can reduce the decomposition or degradation of the cage-like polysilsesquioxane. At the same time, the rigid structure of phenyl groups can provide additional support and reinforcement for the cage-like polysilsesquioxane, further improving the mechanical strength and mechanical properties of the entire thermally conductive material, such as tensile strength and flexural strength, which facilitates subsequent construction.

[0098] In some embodiments, the sum of p and q is 8, 10, or 12.

[0099] In some embodiments, the second silicone oil comprises: tris(epoxypropoxypropyldimethylsiloxy)phenylsilane.

[0100] In these embodiments, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane contains a phenyl group. The presence of the phenyl group provides the thixotropic agent with a certain degree of rigidity and thermal stability, and can effectively disperse the thermal stress on the thermally conductive material, reducing the thermal motion of the thermally conductive material at high temperatures, thereby further improving the high-temperature resistance of the thermally conductive material. Simultaneously, the siloxy group in the silane coupling agent endows the thermally conductive material with organosilicon properties, such as good thermal stability, low surface tension, and excellent flexibility.

[0101] The structural formula of tris(epoxypropoxypropyldimethylsiloxy)phenylsilane is shown in formula (i) below:

[0102]

[0103] In some embodiments, the inorganic thermally conductive filler includes at least one of alumina, boron nitride, aluminum nitride, magnesium oxide, and diamond.

[0104] In these embodiments, these inorganic thermally conductive fillers are inorganic non-metallic thermally conductive fillers, which can improve the insulation performance of the thermally conductive material compared with metallic thermally conductive fillers, making it convenient for use in power devices.

[0105] The alumina may include at least one of the following: single-crystal alumina, irregular alumina, and spherical alumina. Magnesium oxide may include spherical magnesium oxide, etc.

[0106] In some embodiments, the sodium ion content in the inorganic thermally conductive filler is less than 100 ppm.

[0107] In these embodiments, the inorganic thermally conductive filler exhibits superior insulation properties.

[0108] In some embodiments, the median particle size D50 of the inorganic thermally conductive filler is 0.2 μm to 100 μm.

[0109] The median particle size D50 refers to the particle size corresponding to a cumulative volume distribution percentage of 50% for inorganic thermally conductive fillers.

[0110] In some embodiments, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, single-crystal alumina, and spherical alumina, in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts, and 69 parts, respectively.

[0111] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is dimethyl polysiloxane with a viscosity of 100 centipoise or methyl phenyl modified siloxane with a viscosity of 100 centipoise. The median particle size D50 of the single crystal alumina is 1.5 μm and the sodium ion content is 20 ppm. The median particle size D50 of the spherical alumina is 45 μm and the sodium ion content is 59 ppm.

[0112] In some embodiments, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), a first silicone oil, irregular alumina, and spherical alumina, in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts, and 69 parts, respectively.

[0113] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of irregular alumina is 2.0 μm, the sodium ion content is 200 ppm, the median particle size D50 of spherical alumina is 43 μm, and the sodium ion content is 300 ppm.

[0114] In some embodiments, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), first silicone oil, single-crystal alumina, spherical alumina, and spherical magnesium oxide, in weight amounts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 15 parts, 25 parts, and 55 parts, respectively.

[0115] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of single crystal alumina is 1.5 μm, the sodium ion content is 20 ppm, the median particle size D50 of spherical alumina is 45 μm, the sodium ion content is 59 ppm, the median particle size D50 of spherical magnesium oxide is 80 μm and it does not contain sodium ions, or the median particle size D50 of spherical magnesium oxide is 120 μm and it does not contain sodium ions.

[0116] In some embodiments, the raw materials for the thermally conductive material include: cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), a first silicone oil, single-crystal alumina, and spherical alumina, in weight parts of 1.0 parts, 0.45 parts, 2.0 parts, 3.05 parts, 26 parts, and 63.5 parts, respectively.

[0117] The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the single crystal alumina is 1.5 μm, the sodium ion content is 20 ppm, the median particle size D50 of the spherical alumina is 45 μm, and the sodium ion content is 59 ppm.

[0118] In some embodiments, the thermally conductive material satisfies at least one of the following conditions:

[0119] (1) The thermally conductive material is a paste;

[0120] (2) The viscosity of the thermally conductive material is 206 Pa·s to 315 Pa·s;

[0121] (3) The thermal conductivity of the thermally conductive material is 5.4 W / m·K to 7.1 W / m·K.

[0122] In these embodiments, the thermally conductive material is a uniform paste with suitable viscosity and high thermal conductivity, which can improve workability and thermal conductivity.

[0123] The viscosity mentioned above can be obtained using a Brookfield DV2T HB cone-plate viscometer, which can be measured at room temperature. Taking a room temperature of 25℃ as an example, the specific test method is as follows: at 25℃, take 0.5mL of sample and fill the center of the test pan. Using a cone-plate viscometer, select the 52# rotor and record the sample viscosity at a speed of 1rpm for 2 minutes.

[0124] The thermal conductivity mentioned above can be obtained by using a Hot disk thermal conductivity meter, which can be measured at room temperature. Taking a room temperature of 25°C as an example, the specific test method is as follows: at 25°C, take a sample, fill it into a standard mold, vacuum degas and spread it out, and test the thermal conductivity of the sample.

[0125] Secondly, some embodiments of this application provide a method for preparing a thermally conductive material, such as... Figure 1 As shown, the process includes the following steps S11 to S14:

[0126] S11. The wetting and dispersing agent and the matrix material are mixed in the first mixing to prepare the first mixture;

[0127] S12. Add the inorganic thermally conductive filler to the first mixture in batches for a second mixing to prepare the second mixture;

[0128] S13. The second mixture is heated to 100℃~200℃ and reacted for 0.5h~2h, then subjected to the first degassing treatment and cooled to room temperature;

[0129] In this step, the room temperature can be between 20℃ and 35℃.

[0130] S14. The cage-type polysilsesquioxane and thixotropic additive are added to the cooled second mixture for a third mixing and then subjected to a second degassing treatment to prepare the thermally conductive material.

[0131] The definitions of the matrix material, wetting and dispersing agent, inorganic thermally conductive filler, cage-type polysilsesquioxane and thixotropic agent are as described in the first aspect.

[0132] In the method for preparing the thermally conductive material provided in this application embodiment, a first mixture is prepared by first mixing a wetting and dispersing agent and a matrix material. Then, an inorganic thermally conductive filler is added to the first mixture in batches for a second mixing to obtain a second mixture. This allows the inorganic thermally conductive filler to be uniformly mixed with silicone oil in the presence of a surfactant. Then, the second mixture is reacted at 100℃~200℃ for 0.5~2h by raising the temperature, followed by a first degassing treatment and cooling to room temperature. This allows the inorganic thermally conductive filler to react uniformly with the wetting and dispersing agent and the matrix material, and removes air bubbles from the mixture, thereby improving the dispersion uniformity of the inorganic thermally conductive filler. Finally, by adding cage-type polysilsesquioxane and a thixotropic agent to the cooled second mixture and performing a third mixing and a second degassing treatment, the cage-type polysilsesquioxane and the thixotropic agent can be uniformly mixed with the cooled second mixture, thereby obtaining a paste-like thermally conductive material with a uniform texture. The raw materials in this thermally conductive material work synergistically to impart excellent thermal conductivity, thixotropic properties, shape retention, and the ability to prevent molecular chain separation and material flow. This makes the thermally conductive material easy to apply, with good storage stability and anti-pumping properties. Furthermore, research has found that this thermally conductive material also has good high-temperature resistance, maintaining shape stability during long-term use and reducing pulverization and cracking. This solves the problem of severe pulverization and unusability of thermally conductive materials under long-term high-temperature conditions in related technologies.

[0133] In some embodiments, the steps included in the preparation method described above are performed in a protective gas atmosphere. The protective gas used in this protective gas atmosphere may include nitrogen, argon, helium, etc.

[0134] In these embodiments, each step can be carried out in an air-isolated atmosphere, reducing the impact of humidity and oxygen in the air on the reaction and minimizing unnecessary loss of raw materials and performance.

[0135] In some embodiments, the first mixing, the second mixing, and the third mixing are all performed at room temperature.

[0136] The meaning of this room temperature is the same as that in step 13, and will not be repeated here.

[0137] In some embodiments, the steps included in the preparation method can be carried out in a mixing device, which may include, but is not limited to, a homogenizer, a high-speed disperser, a single-cone double-helix mixer, a dual-motion mixer, a horizontal ribbon mixer, a zero-gravity mixer, a plow mixer, a hydraulic lifting mixer, a kettle mixing device, or a pneumatic mixer.

[0138] In some embodiments, the stirring rate of the first mixing can be 100 r / min to 200 r / min, and the time can be 10 min to 30 min; and / or, the stirring rate of the second mixing can be 100 r / min to 200 r / min, and the time can be 10 min to 30 min; and / or, the stirring rate of the third mixing can be 100 r / min to 200 r / min, and the time can be 10 min to 30 min.

[0139] In these embodiments, the mixing uniformity of the first mixture, the second mixture, and / or the third mixture can be maximized.

[0140] In some embodiments, the vacuum degree of the first degassing treatment is less than -0.09 MPa; and / or, the vacuum degree of the second degassing treatment is less than -0.09 MPa.

[0141] In these embodiments, the first degassing treatment and / or the second degassing treatment have a better degassing effect, which can further improve the mixing effect and obtain a paste-like thermal conductive material with a uniform texture.

[0142] Thirdly, some embodiments of this application provide an application of the thermally conductive material as described in the first aspect in the heat dissipation of power devices.

[0143] The power device can be a semiconductor power device, which may include, for example, heat-generating elements such as diodes, IGBTs (Insulated-Gate Bipolar Transistors), and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The thermally conductive material can be attached to the power device composed of these heat-generating elements to control the junction temperature of these elements through heat conduction and dissipation, thereby achieving heat dissipation for the power device.

[0144] The specific implementation methods of this application have been described above. In order to objectively illustrate the technical effects produced by this application, the following examples and comparative examples will be used to describe them in detail.

[0145] In the following examples and comparative examples, all raw materials were commercially available, and to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples had the same physical and chemical parameters or underwent the same treatment.

[0146] The main raw materials used in the following embodiments and comparative examples are as follows:

[0147] Component A: Cage-like molecular structure polysilsesquioxane;

[0148] Component B: Tris(epoxypropoxypropyldimethylsiloxy)phenylsilane;

[0149] Component C: Wetting and dispersing agent, with the structure shown in formula (I);

[0150] Component D-1: Dimethylpolysiloxane, 100 centipoise;

[0151] Component D-2: Dimethylpolysiloxane, 1000 centipoise;

[0152] Component D-3: Methylphenyl modified polysiloxane, 100 centipoise;

[0153] Component E-1: Monocrystalline alumina (D50 = 1.5 μm, sodium ion content 20 ppm);

[0154] Component E-2: Irregular alumina (D50 = 2.0 μm, sodium ion content 200 ppm);

[0155] Component E-3: Spherical alumina (D50 = 45 μm, sodium ion content 59 ppm);

[0156] Component E-4: Spherical alumina (D50 = 43 μm, sodium ion content 300 ppm);

[0157] Component E-5: Spherical magnesium oxide (D50 = 80 μm, purity ≥ 99.0%, and free of sodium ions);

[0158] Component E-6: Spherical magnesium oxide (D50 = 120 μm, purity ≥ 99.0%, and free of sodium ions).

[0159] Example 1

[0160] Example 1 provides a non-curing high-temperature resistant insulating and thermally conductive material. The preparation method of this thermally conductive material is as follows:

[0161] (1) Preparation of materials: Weigh each component according to the mass ratio of component A, component B, component C, component D-3, component E-1 and component E-3 of 0.5:0.25:1.25:3:26:69 and set aside for later use;

[0162] The preparation method of component A is as follows: 526.9 g of decyltrimethoxysilane, 398.1 g of phenyltrimethoxysilane, and 3000 mL of tetrahydrofuran were added to a 5000 mL three-necked flask to prepare a homogeneous solution. An aqueous solution consisting of 3.4 g of potassium hydroxide and 80 g of water was slowly added to this solution. The reaction mixture was heated under reflux at 75 °C for 8 h with stirring. After cooling, the reaction mixture was neutralized to pH 7, and volatile components were removed under reduced pressure to obtain component A. The structural formula of component A is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4, the separation yield was 97%.

[0163] (2) Add component C and component D into a high-speed disperser, and stir at a stirring speed of 150 r / min at room temperature (25°C) under a nitrogen atmosphere for 20 min to make component C and component D evenly mixed to obtain the first mixture;

[0164] (3) Components E-1 and E-3 were added to the first mixture in five separate portions, each portion being 20% ​​of the total amount added. The mixture was stirred at 150 r / min at room temperature (25°C) for 20 min to ensure that components E-1 and E-3 were mixed evenly. The mixture was then heated to 150°C and reacted for 1 h. After degassing under a vacuum of -0.092 MPa, the mixture was cooled to room temperature (25°C) to obtain the second mixture.

[0165] (4) Component A and component B are added to the second mixture and stirred at a stirring rate of 150 r / min for 20 min. After mixing evenly, the mixture is degassed under a vacuum of -0.092 MPa to obtain the thermal conductive material.

[0166] Example 2

[0167] The preparation method of the thermally conductive material provided in Example 2 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0168] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1, component E-3 and component E-5 of 0.5:0.25:1.25:3:15:25:55 and set aside for later use;

[0169] In step (3), components E-1, E-3 and E-5 are added to the first mixture in 5 portions and mixed evenly at room temperature (25°C). Then, the mixture is heated to 150°C and reacted for 1 hour to remove bubbles. After cooling to room temperature (25°C), the second mixture is obtained.

[0170] Example 3

[0171] The preparation method of the thermally conductive material provided in Example 3 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0172] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1, component E-3 and component E-6 of 0.5:0.25:1.25:3:15:25:55;

[0173] In step (3), components E-1, E-3 and E-6 are added to the first mixture in four separate batches and mixed evenly at room temperature (25°C). Each batch is 25% of the total amount added. The mixture is then heated to 150°C and reacted for 1 hour to remove bubbles. After cooling to room temperature (25°C), the second mixture is obtained.

[0174] Example 4

[0175] The preparation method of the thermally conductive material provided in Example 4 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0176] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1 and component E-3 as 1.0:0.45:2.0:3.05:26:67.5;

[0177] In step (3), components E-1 and E-3 are added to the first mixture in 6 portions and mixed evenly at room temperature (25°C). Each addition is 1 / 6 of the total addition. Then, the mixture is heated to 150°C and reacted for 1 hour to remove bubbles. After cooling to room temperature (25°C), the second mixture is obtained.

[0178] Example 5

[0179] The preparation method of the thermally conductive material provided in Example 5 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0180] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-2 and component E-4 of 0.5:0.25:1.25:3:26:69;

[0181] In step (3), components E-2 and E-4 are added to the first mixture in 5 portions and mixed evenly at room temperature (25°C). Each addition is 20% of the total addition amount of each component. The mixture is then heated to 150°C and reacted for 1 hour to remove bubbles. After cooling to room temperature (25°C), the second mixture is obtained.

[0182] Example 6

[0183] The preparation method of the thermally conductive material provided in Example 6 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0184] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-1, component E-1 and component E-3 of 0.5:0.25:1.25:3:26:69;

[0185] In step (2), component C and component D-1 are added to a high-speed disperser and mixed evenly at room temperature (25°C) under a nitrogen atmosphere to obtain the first mixture.

[0186] Comparative Example 1

[0187] The preparation method of the thermally conductive material provided in Comparative Example 1 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0188] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-2, component E-1 and component E-3 of 0.5:0.25:1.25:3:26:69;

[0189] In step (2), component C and component D-2 are added to a high-speed disperser and mixed evenly at room temperature (25°C) under a nitrogen atmosphere to obtain the first mixture.

[0190] Comparative Example 2

[0191] The preparation method of the thermally conductive material provided in Comparative Example 2 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0192] In step (1), each component is weighed according to the mass ratio of component A, component C, component D-3, component E-1 and component E-3 of 1.0:1.25:3:25.75:69;

[0193] In step (4), component A is added to the second mixture, mixed evenly, and degassed to obtain the thermally conductive material.

[0194] Comparative Example 3

[0195] The preparation method of the thermally conductive material provided in Comparative Example 3 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0196] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1 and component E-3 of 0.25:0.5:1.25:3:26:69;

[0197] In step (4), component B is added to the second mixture, mixed evenly, and degassed to obtain the thermally conductive material.

[0198] Comparative Example 4

[0199] The preparation method of the thermally conductive material provided in Comparative Example 4 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0200] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1 and component E-3 as 0.5:0.25:1.25:2.5:26.5:69.

[0201] Comparative Example 5

[0202] The preparation method of the thermally conductive material provided in Comparative Example 5 is basically the same as that of the thermally conductive material provided in Example 1, except that:

[0203] In step (1), each component is weighed according to the mass ratio of component A, component B, component C, component D-3, component E-1 and component E-3 of 0.5:0.25:0.75:3:26.5:69.

[0204] Test case

[0205] 1. Viscosity test:

[0206] According to the ASTM D1084 test standard, the viscosity of the thermally conductive materials provided in Examples 1-6 and Comparative Examples 1-5 was tested using a Brookfield DV2T HB cone-plate viscometer. The test method was as follows: at 25°C, 0.5 mL of sample was filled into the center of the test pan, and the sample viscosity was recorded for 2 minutes at a speed of 1 rpm using a cone-plate viscometer with a 52# rotor. The test results are shown in Table 1 below.

[0207] 2. Thermal conductivity test:

[0208] According to the ISO-CD 22007-2 testing standard, the thermal conductivity of the thermally conductive materials provided in Examples 1-6 and Comparative Examples 1-5 was tested using a Hot disk thermal conductivity meter. The test method was as follows: at 25°C, the sample was filled into a standard mold, vacuumed to remove bubbles and laid flat, and the thermal conductivity of the sample was tested. The test results were all experimental results of 3 times and the average value was taken. The test results are shown in Table 1 below.

[0209] 3. Anti-sagging test:

[0210] Two layers of electrical tape were applied to both edges of a stainless steel sheet. Then, 0.2 mL of the thermally conductive material samples provided in Examples 1-6 and Comparative Examples 1-5 were aspirated and placed on the upper middle part of the stainless steel sheet. The stainless steel sheet was sandwiched between two transparent glass plates and secured with dovetail clips. The initial outline of the sample was marked with a marker, and then the sample was placed vertically in an oven at 125°C, a high-temperature and high-humidity chamber at 85°C and 85% RH%, and a thermal shock chamber at -40°C to 125°C for 1000 hours respectively. The position of the sample's descent and its initial position were observed from the glass surface to examine the stability and adhesion of the thermally conductive material under different environments. Under all three conditions, if the displacement of any sample's descent position from its initial position was ≤5%, the anti-sagging performance was considered acceptable and rated OK. If the displacement of any sample's descent position from its initial position was ≥5% under all three conditions, the anti-sagging performance was considered unacceptable and rated NG.

[0211] 4. Temperature resistance test:

[0212] The thermally conductive material samples provided in Examples 1-6 and Comparative Examples 1-5 were uniformly coated onto the surface of copper sheets using stencil printing. After being heated in a forced-air drying oven at 150°C for 1000 hours, the presence of dry powder, hardening, or cracking was observed. If dry powder, hardening, or cracking occurred, the test result was deemed unsuccessful, and the reliability test evaluation was NG (Not Good). If no dry powder, hardening, or cracking occurred, the test result was deemed successful, and the reliability test evaluation was OK.

[0213] Table 1

[0214]

[0215]

[0216] As shown in Table 1, a homogeneous paste-like thermal conductive material can be prepared by mixing multiple components A, B, C, D-3, E-1, E-2, E-3, E-4, E-5, and E-6 in a certain proportion. This paste-like thermal conductive material has suitable viscosity and modulus, excellent anti-sagging effect, and can improve its storage stability, shape retention, and anti-pumping performance, making it easy to apply. Furthermore, by controlling the sodium ion content in components E-1, E-3, E-5, and E-6, the high-temperature resistance of the paste-like thermal conductive material can be further improved. However, when the sodium ion content in components E-2 and E-4 is slightly higher, the temperature resistance of the paste-like thermal conductive material decreases slightly.

[0217] Compared to Example 1, when the viscosity of the silicone oil in Comparative Example 1 is controlled to be high, Comparative Example 1 cannot form a uniform paste, but instead appears as a dry powder, which cannot meet the usage requirements.

[0218] Compared with Example 1, although a uniform paste-like thermal conductive material can be obtained by not adding component B in Comparative Example 2, its anti-sagging effect is poor and it cannot maintain its shape during use, thus failing to meet the usage requirements.

[0219] Compared to Example 1, by controlling the content of component A to be lower and the content of component B to be higher in Comparative Example 3, a paste-like thermal conductive material can be obtained. However, its viscosity is very high, which is not conducive to construction, and its temperature resistance cannot meet the requirements for use.

[0220] Compared to Example 1, by controlling the content of component D-3 to be lower and the content of component E-1 to be higher in Comparative Example 4, the viscosity of the resulting paste-like thermal conductive material is also very high, and the anti-sagging effect and temperature resistance are reduced to a certain extent, which cannot meet the usage requirements.

[0221] Compared to Example 1, by controlling the content of component C to be lower and the content of component E-1 to be higher in Comparative Example 5, the inorganic thermally conductive filler cannot be uniformly dispersed in the thermally conductive material, resulting in the thermally conductive material agglomerating and failing to meet the usage requirements.

[0222] In summary, only by controlling the mixing of the above components at a certain mass ratio and ensuring that the performance of each component meets certain requirements can a paste-like thermal conductive material with a uniform texture and easy application be prepared. Changes in the performance and addition ratio of one or more components will affect the performance of the thermal conductive material and will not be conducive to improving the overall performance of the thermal conductive material.

[0223] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0224] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A thermally conductive material, characterized in that, Its raw materials include: matrix material, inorganic thermally conductive filler, wetting and dispersing agent, cage-type polysilsesquioxane and thixotropic agent; The matrix material includes a first silicone oil with a viscosity of 20 centipoise to 500 centipoise; the wetting and dispersing agent includes a silane coupling agent, which includes an asymmetric silicone oil; the cage-like polysilsesquioxane has a number-average molecular weight of 1200 g / mol to 2600 g / mol, a molecular weight dispersion of 1.0 to 1.6, and the average number of silicon atoms in the compound molecules contained in the cage-like polysilsesquioxane is 8 to 14; the thixotropic agent includes a second silicone oil containing epoxy groups. Based on 100 parts by weight of the thermally conductive material, the matrix material comprises 3 to 4 parts, the inorganic thermally conductive filler comprises 91 to 96 parts, the cage-type polysilsesquioxane comprises 0.5 to 1.5 parts, the wetting and dispersing agent comprises 1 to 3 parts, and the thixotropic agent comprises 0.1 to 0.5 parts.

2. The thermally conductive material according to claim 1, characterized in that, The raw materials satisfy at least one of the following conditions: (1) The first silicone oil comprises at least one of dimethyl polysiloxane and methylphenyl modified polysiloxane; (2) The viscosity of the first silicone oil is 50 centipoise to 200 centipoise; (3) The general structural formula of the asymmetric silicone oil is shown in the following formula (I), where n is an integer from 36 to 84; (4) The silane coupling agent further includes at least one of methyltrimethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, n-decyltrimethoxysilane and hexadecyltrimethoxysilane, and in the silane coupling agent, the mass percentage of the asymmetric silicone oil is greater than or equal to 90%. (5) The inorganic thermally conductive filler includes at least one of alumina, boron nitride, aluminum nitride, magnesium oxide and diamond; optionally, the sodium ion content in the inorganic thermally conductive filler is less than 100 ppm; (6) The median particle size D50 of the inorganic thermally conductive filler is 0.2μm to 100μm; (7) The general structural formula of the cage-type polysilsesquioxane is: [RO 1 / 2 ] r [(C 10 H 21 SiO 3 / 2 ] q [PhSiO 3 / 2 ] p Wherein, R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; Ph is a phenyl group; p and q are both integers greater than or equal to 1, and the sum of p and q is 8 to 14, and r is an integer from 0 to 1; optionally, the sum of p and q is 8, 10 or 12. (8) The second silicone oil includes: tris(epoxypropyldimethylsiloxy)phenylsilane.

3. The thermally conductive material according to claim 2, characterized in that, The raw materials for the thermally conductive material include: The cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), the first silicone oil, single-crystal alumina and spherical alumina are contained in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts and 69 parts respectively. The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a dimethyl polysiloxane with a viscosity of 100 centipoise or a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the single crystal alumina is 1.5 μm and the sodium ion content is 20 ppm, the median particle size D50 of the spherical alumina is 45 μm and the sodium ion content is 59 ppm.

4. The thermally conductive material according to claim 2, characterized in that, The raw materials for the thermally conductive material include: The cage-shaped polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), the first silicone oil, irregular alumina and spherical alumina are contained in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 26 parts and 69 parts respectively. The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the irregular alumina is 2.0 μm and the sodium ion content is 200 ppm, and the median particle size D50 of the spherical alumina is 43 μm and the sodium ion content is 300 ppm.

5. The thermally conductive material according to claim 2, characterized in that, The raw materials for the thermally conductive material include: The cage-type polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), the first silicone oil, single crystal alumina, spherical alumina and spherical magnesium oxide are contained in weight parts of 0.5 parts, 0.25 parts, 1.25 parts, 3 parts, 15 parts, 25 parts and 55 parts respectively. The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the single crystal alumina is 1.5 μm and the sodium ion content is 20 ppm, the median particle size D50 of the spherical alumina is 45 μm and the sodium ion content is 59 ppm, the median particle size D50 of the spherical magnesium oxide is 80 μm and does not contain sodium ions, or the median particle size D50 of the spherical magnesium oxide is 120 μm and does not contain sodium ions.

6. The thermally conductive material according to claim 2, characterized in that, The raw materials for the thermally conductive material include: The cage-shaped polysilsesquioxane, tris(epoxypropoxypropyldimethylsiloxy)phenylsilane, the structure shown in formula (I), the first silicone oil, single-crystal alumina and spherical alumina are contained in weight parts of 1.0 parts, 0.45 parts, 2.0 parts, 3.05 parts, 26 parts and 63.5 parts respectively. The structural formula of the cage-type polysilsesquioxane is [HO]. 1 / 2 ][(C 10 H 21 SiO 3 / 2 ]4[PhSiO 3 / 2 ]4; The first silicone oil is a methylphenyl modified siloxane with a viscosity of 100 centipoise, the median particle size D50 of the single crystal alumina is 1.5 μm and the sodium ion content is 20 ppm, the median particle size D50 of the spherical alumina is 45 μm and the sodium ion content is 59 ppm.

7. The thermally conductive material according to any one of claims 1 to 6, characterized in that, The thermally conductive material satisfies at least one of the following conditions: (1) The thermally conductive material is a paste; (2) The viscosity of the thermally conductive material is 206 Pa·s to 315 Pa·s; (3) The thermal conductivity of the thermally conductive material is 5.4 W / m·K to 7.1 W / m·K.

8. A method for preparing a thermally conductive material, characterized in that, include: The wetting and dispersing agent and the matrix material are mixed in the first step to prepare a first mixture; Inorganic thermally conductive fillers are added to the first mixture in batches for a second mixing to prepare a second mixture; The second mixture is heated to 120℃~180℃ and reacted for 0.5h~2h, then subjected to the first degassing treatment and cooled to room temperature; The thermally conductive material is prepared by adding cage-type polysilsesquioxane and thixotropic additive to the cooled second mixture for a third mixing and a second degassing treatment. The matrix material, the wetting and dispersing agent, the inorganic thermally conductive filler, the cage-type polysilsesquioxane, and the thixotropic agent are defined as described in any one of claims 1 to 7.

9. The method for preparing the thermally conductive material according to claim 8, characterized in that, The preparation method satisfies at least one of the following conditions: (1) Each step of the preparation method is carried out in a protective gas atmosphere; (2) The first mixing, the second mixing, and the third mixing are all carried out at room temperature; (3) The stirring rate of the first mixture is 100 r / min to 200 r / min, and the time is 10 min to 30 min; (4) The stirring rate of the second mixture is 100 r / min to 200 r / min, and the time is 10 min to 30 min; (5) The stirring rate of the third mixing is 100 r / min to 200 r / min, and the time is 10 min to 30 min; (6) The vacuum degree of the first degassing treatment is less than -0.09 MPa; (7) The vacuum degree of the second degassing treatment is less than -0.09 MPa.

10. The application of a thermally conductive material as described in any one of claims 1 to 7 in heat dissipation of power devices.

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