Heat-conducting composition as well as preparation method and application thereof

Abstract

The embodiment of the invention provides a heat-conducting composition as well as a preparation method and application thereof. The heat-conducting composition comprises a base material and a heat-conducting filler, the heat-conducting filler comprises a large-particle-size filler and a small-particle-size filler, the ratio of the average particle size of the large-particle-size filler to the average particle size of the small-particle-size filler is 3 or above, and the large-particle-size filler at least comprises a silicon carbide filler with the average sphericity degree of 0.8 or above. The large-particle-size filler of the heat-conducting composition comprises the silicon carbide filler with the sphericity degree of 0.8 or above, so that the heat-conducting composition containing the heat-conducting filler is relatively high in flowability and excellent in heat-conducting property, and the requirement of the field of electronic equipment on a heat-conducting material with excellent comprehensive performance is conveniently met.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of thermal conductive materials, and specifically to a thermal conductive composition, a preparation method thereof, and applications thereof. Background Art

[0002] Heat generated by heat-generating components like chips in electronic devices often needs to be dissipated through a heat sink. From a microscopic perspective, the interface between the chip and the heat sink is often uneven, requiring the interfacial thermal conductive material to reduce the contact thermal resistance.

[0003] Thermally conductive interface materials are typically formed by curing a thermally conductive composition containing an organic matrix and a solvent. To improve the thermal conductivity of the composition, a high-conductivity thermally conductive filler is often added. Silicon carbide, with its extremely high theoretical thermal conductivity and theoretical breakdown strength, holds promise as a high-performance thermally conductive filler. However, most existing silicon carbide powders come from the abrasive industry and have poor sphericity. Directly adding silicon carbide to thermally conductive compositions results in poor flowability and a low fill rate. Consequently, silicon carbide is rarely used as a high-conductivity filler in existing thermally conductive compositions. Summary of the Invention

[0004] In view of this, the embodiments of the present application provide a thermally conductive composition containing silicon carbide filler with good thermal conductivity and good fluidity, as well as a preparation method and application thereof, to better meet the demand for excellent performance thermal conductive materials in the field of electronic equipment.

[0005] Specifically, the first aspect of an embodiment of the present application provides a thermally conductive composition, comprising a base material and a thermally conductive filler distributed in the base material; the thermally conductive filler comprises a large-particle filler and a small-particle filler, wherein the ratio of the average particle size of the large-particle filler to the average particle size of the small-particle filler is greater than 3, and the large-particle filler comprises at least a silicon carbide filler with a sphericity greater than 0.8.

[0006] In the above-mentioned thermally conductive composition, the large-particle thermally conductive filler adopts a silicon carbide filler with high sphericity, which is conducive to fully utilizing the high thermal conductivity of silicon carbide, thereby making the thermally conductive performance of the thermally conductive composition better. The high sphericity of the silicon carbide filler also makes the above-mentioned thermally conductive composition have good fluidity, so that the thermally conductive composition can have good applicability and good thermal conductivity.

[0007] In some embodiments of the present application, the mass content of silicon carbide in the silicon carbide filler having a sphericity of 0.8 or greater is greater than or equal to 99.0%. The purity of the silicon carbide in the silicon carbide filler is relatively high, which helps improve its breakdown resistance. Furthermore, in some embodiments of the present application, the mass content of silicon carbide in the silicon carbide filler having a sphericity of 0.8 or greater is greater than or equal to 99.9%.

[0008] In some embodiments of the present application, the surface of the silicon carbide filler with a sphericity of 0.8 or greater further comprises an insulating coating layer. The presence of the insulating coating layer can enhance the breakdown resistance of the silicon carbide filler and its compatibility with the organic matrix material.

[0009] In embodiments of the present application, the silicon carbide filler having a sphericity of 0.8 or greater has a silicon carbide crystal form selected from one or more of the following: 2H phase, 3C phase, 4H phase, and 6H phase. This highly spherical silicon carbide filler possesses a suitable crystal form and can effectively enhance the thermal conductivity of the thermally conductive composition and its cured product.

[0010] In the embodiment of the present application, the physicochemical parameters of the silicon carbide filler with a sphericity of more than 0.8 meet the following requirements: the bulk density is greater than 1.5 g / cm 3 The critical breakdown field strength is greater than 200V / mm; the thermal conductivity is greater than 250W / (m·K). The silicon carbide filler particles are relatively round, have good breakdown resistance and thermal conductivity, and contribute to the excellent fluidity and thermal conductivity of the thermally conductive composition using them.

[0011] In some embodiments of the present application, the average particle size of the small-particle filler is less than 5 μm, and the average particle size of the large-particle filler is greater than 20 μm. The average particle sizes of the large and small-particle fillers can be selected and controlled according to actual needs. The average particle sizes of the large and small-particle fillers provided herein are more conducive to the thermally conductive composition meeting the heat dissipation requirements between electronic components such as chips and heat sinks in electronic devices.

[0012] In some embodiments of the present application, the average particle size of the large-particle filler is greater than 30 μm. The larger average particle size of the large-particle filler is more conducive to reducing the interfacial thermal resistance between the large-particle fillers, thereby improving the thermal conductivity of the above-mentioned thermal conductive composition.

[0013] In some embodiments of the present application, the large-particle filler includes a filler with an average particle size of 60 μm or greater; the filler with an average particle size of 60 μm or greater includes a silicon carbide filler with a sphericity of 0.8 or greater. In this case, the high-sphericity silicon carbide filler has a relatively large average particle size of 60 μm or greater, which is more conducive to improving the thermal conductivity of the thermally conductive composition. In some embodiments, the average particle size of the silicon carbide filler with a sphericity of 0.8 or greater is between 60 μm and 150 μm.

[0014] In some embodiments of the present application, the large-particle filler further comprises one or more of conventional silicon carbide fillers, aluminum nitride fillers, boron nitride fillers, silicon nitride fillers, and diamond fillers; wherein the conventional silicon carbide filler has a sphericity of less than 0.5. Other large-particle thermally conductive fillers may be introduced into the thermally conductive composition as needed.

[0015] In some embodiments of the present application, the small-particle filler includes at least two types of filler particles, one having an average particle size of less than 1 μm and the other having an average particle size greater than 1 μm and less than or equal to 5 μm. Using two small-particle fillers is more conducive to increasing the bulk density of the overall thermally conductive filler.

[0016] In some embodiments of the present application, the small particle size filler includes one or more of zinc oxide, aluminum oxide, and magnesium oxide. Oxide thermal conductive fillers generally have high sphericity, good fluidity, and generally contain hydroxyl groups on their surface, which have good compatibility with organic matrix materials.

[0017] In some embodiments of the present application, the thermally conductive filler further comprises a medium-sized filler, wherein the average particle size of the medium-sized filler is between that of the large-sized filler and the small-sized filler. The medium-sized filler can adjust the rheological properties, stability, and thermal conductivity of the thermally conductive composition.

[0018] In an embodiment of the present application, the medium-sized filler includes one or more of oxides, carbides, nitrides, and metals.

[0019] In the embodiments of the present application, the large-particle filler comprises 40% to 70% of the total mass of the thermally conductive composition. Controlling the mass proportion of the large-particle filler, which plays a primary role in thermal conductivity, within an appropriate range facilitates better thermal conductivity of the thermally conductive composition and enhances the mechanical properties of the cured product.

[0020] In some embodiments of the present application, the mass proportion of the silicon carbide filler having a sphericity of 0.8 or greater in the thermally conductive filler is within a range of 15% to 55%. Controlling the mass proportion of the high-sphericity silicon carbide filler, which is a large-particle filler component, within a suitably high range in the total thermally conductive filler composition is beneficial for improving the thermal conductivity of the thermally conductive composition containing the thermally conductive filler.

[0021] In the embodiment of the present application, the total mass proportion of the thermally conductive filler in the thermally conductive composition is 50%-98%, which ensures that the cured thermally conductive composition using the thermally conductive filler can construct a good thermal conductive network.

[0022] In some embodiments of the present application, the matrix material is an organic matrix; the organic matrix includes at least one of a silicone system, an epoxy system, an acrylic system, a polyurethane system, a polyimide system, a polyester system, and a polyolefin system.

[0023] In some embodiments of the present application, the organosilicon system is an addition reaction curing organosilicon system; and the thermal conductive composition further includes a catalyst and an inhibitor.

[0024] In some embodiments of the present application, the thermally conductive composition further comprises a filler treatment agent. The introduction of the filler treatment agent can reduce agglomeration / sedimentation of the thermally conductive fillers in the thermally conductive composition.

[0025] In the embodiment of the present application, the extrusion rate of the thermally conductive composition at a pressure of 0.62 MPa is greater than 6.0 g / min, and the thermal conductivity of the thermally conductive composition is greater than 7.0 W / (m·K). This indicates that the thermally conductive composition can achieve both good fluidity and thermal conductivity.

[0026] A second aspect of the present invention provides a method for preparing a thermally conductive composition, comprising the following steps:

[0027] Spheroidizing the silicon carbide powder to obtain a silicon carbide filler with a sphericity of 0.8 or more; wherein the spheroidizing treatment includes one or more of sand grinding, high-temperature plasma flame melting into balls, and micro-powder granulation into balls;

[0028] The thermally conductive filler with a small particle size, the thermally conductive filler with a large particle size including the silicon carbide filler with a sphericity of 0.8 or more, and the matrix material are mixed to obtain a thermally conductive composition.

[0029] In the above-mentioned method for preparing the thermally conductive composition, silicon carbide powder is first spheroidized using a specific method to effectively transform it into highly spherical particles. These particles are then mixed with the other components of the composition to produce a thermally conductive composition with excellent fluidity and thermal conductivity. This method for preparing the thermally conductive composition is simple, easy to operate, and suitable for large-scale industrial production.

[0030] A third aspect of the embodiments of the present application provides a thermally conductive material, which includes a cured product of the thermally conductive composition described in the first aspect of the embodiments of the present application, or includes a cured product of the thermally conductive composition described in the second aspect of the embodiments of the present application.

[0031] The cured product of the thermally conductive composition has high dielectric strength, good thermal conductivity, and good aging resistance and reliability. It can be designed into thermally conductive materials of various shapes and sizes according to actual application needs, thus better meeting insufficient application requirements.

[0032] The fourth aspect of the present invention provides an electronic device comprising the cured thermally conductive composition of the first aspect of the present invention. The cured thermally conductive composition provided above can be used as a thermally conductive material with excellent performance in electronic devices.

[0033] In some embodiments of the present application, the electronic device includes an electronic component and a heat sink disposed on the electronic component. A thermally conductive interface material is disposed between the electronic component and the heat sink. The thermally conductive interface material comprises a cured product of the thermally conductive composition described in the first aspect of the present application. This thermally conductive interface material is generally referred to as a board-level thermally conductive interface material. It utilizes the cured product of the thermally conductive composition provided herein. It can effectively and promptly conduct heat generated by the electronic component without affecting its normal operation. Furthermore, the thermally conductive interface material exhibits excellent aging resistance and high reliability.

[0034] In some embodiments of the present application, the electronic component is a packaged chip, comprising a substrate, a chip disposed on the substrate, and a heat dissipation cover. The chip is located within a housing formed by the heat dissipation cover and the substrate. A second thermally conductive interface material is disposed between the heat dissipation cover and a surface of the chip facing away from the substrate. The second thermally conductive interface material comprises a cured product of the thermally conductive composition described in the first aspect of the present application. This second thermally conductive interface material is generally referred to as a package-grade thermally conductive interface material. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural diagram of a circuit board provided with a heat sink and a chip.

[0036] Figure 2 Schematic diagram of the structure of the packaged chip. DETAILED DESCRIPTION

[0037] The embodiments of the present application will be described below with reference to the accompanying drawings.

[0038] Electronic devices are usually equipped with many heat-generating electronic components, such as chips. High temperatures can have a harmful effect on the stability, reliability, and life of electronic components. For example, excessively high temperatures can endanger semiconductor junctions, damage circuit connection interfaces, increase conductor resistance, and cause mechanical stress damage. Figure 1As shown, a heat-generating power device or a heat-generating module is provided on the circuit board 11. In this embodiment, the heat-generating power device is a chip 12 as an example for explanation, and a heat sink 14 is provided on the chip 12. However, there is usually a slight uneven gap between the contact interface of the chip 12 and the heat sink 14. If the chip 12 and the heat sink 14 are directly mounted together, there will be a lot of air gaps between the chip 12 and the heat sink 14. Since air is a poor conductor of heat, the contact thermal resistance between the chip 12 and the heat sink 14 will be very large, which will seriously hinder the conduction of heat and ultimately cause the efficiency of the heat sink 14 to be low. Therefore, it is necessary to fill the space between the chip 12 and the heat sink 14 with an interface thermal conductive material 13 to eliminate the air gap between the chip 12 and the heat sink 14 and establish an effective heat conduction channel between the chip 12 and the heat sink 14, which can greatly reduce the contact thermal resistance between the two and enable the heat sink 14 to play its full role.

[0039] The above-mentioned interface thermal conductive material 13 can be specifically referred to as board-level interface thermal conductive material (Second level thermal interface materials, abbreviated as TIM2). Figure 1 In the embodiment, a heat sink 14 may be provided on a single chip 12 , or a plurality of chips 12 may share a heat sink 14 .

[0040] In addition, the chip 12 can be a bare chip, or a ball grid array (BGA) packaged chip with a heat dissipation cover on top (such as Figure 2 As shown). Figure 2 The BGA packaged chip 12 shown includes a package substrate 121, a chip 122 (also known as a bare chip 122) disposed thereon, and a heat dissipation cover 124. The bare chip 122 is located in a housing space enclosed by the heat dissipation cover 124 and the package substrate 121. In addition, a plurality of solder balls 121a are provided on the side of the package substrate 121 facing away from the bare chip 122. The plurality of solder balls 121a are arranged in an array to form a solder ball array. Therefore, the BGA packaged chip can also be called a solder ball array packaged chip. Among them, the bare chip 122 ( Figure 2 A thermal interface material 123, specifically the surface of the bare chip 122 facing away from the package substrate 121, may also be filled between the heat dissipation cover 124. This material is referred to as a first-level thermal interface material (TIM1). The thermal interface material 123 is used to reduce the contact thermal resistance between the bare chip 122 and the heat dissipation cover 124, thereby transferring the heat generated by the bare chip 122 to the heat dissipation cover 124.

[0041] The above-mentioned interface thermal conductive materials are usually formed by coating a liquid thermal conductive composition containing an organic matrix, a thermally conductive filler and a solvent and then curing it. If the thermal conductivity of the above-mentioned interface thermal conductive material is poor, it will greatly affect the heat dissipation effect of the chip. In order to better improve the thermal conductivity of the interface thermal conductive material, the thermally conductive filler used in the interface thermal conductive material and the thermally conductive composition should have a higher thermal conductivity coefficient. Among them, the filler system with a high thermal conductivity coefficient usually uses a non-oxide filler as the largest particle size filler. For example, aluminum nitride, boron nitride, and diamond are common thermal conductive fillers with high theoretical thermal conductivity coefficients.

[0042] However, unlike oxide systems such as aluminum oxide and magnesium oxide, aluminum nitride cannot be spheroidized using traditional high-temperature melting to form balls as a thermally conductive filler, but requires a complicated spheroidization process, making the production cost of spherical aluminum nitride more than 10 times that of spherical aluminum oxide. Moreover, the spherical aluminum nitride particles obtained are usually smaller (less than 20 μm), and the thermal conductivity of the thermally conductive material cannot be significantly improved. Boron nitride has good dielectric properties and thermal conductivity, and is theoretically an ideal thermally conductive filler, but boron nitride currently exists in the form of hexagonal boron nitride, and the prior art has not yet broken through the granulation spheroidization technology of boron nitride, and hexagonal boron nitride can only be added slightly, otherwise it will cause the viscosity of the system to be too high and the fluidity to be too poor, and its small amount of addition has little effect on improving the thermal conductivity of the thermally conductive composition. The thermal conductivity of diamond powder is typically above 1000 W / mk. Theoretically, using diamond filler could potentially increase the thermal conductivity of a thermally conductive composition to over 12 W / mk. However, diamond filler has a very low content of surface active groups (such as hydroxyl groups), resulting in poor compatibility with organic matrices (such as epoxy resins and silicone resins) and a high tendency to agglomerate. Therefore, it can only be added in small quantities. When the volume percentage of diamond filler exceeds 15%, problems such as difficulty dispersing and phase separation can occur, making back-end processing impossible.

[0043] Silicon carbide materials are also expected to become excellent thermal conductive fillers due to their extremely high theoretical thermal conductivity, high theoretical breakdown strength and good chemical resistance. However, most existing silicon carbide powders come from the abrasive industry and have disadvantages such as poor sphericity. If they are directly filled into thermal conductive compositions, the thermal conductive compositions will have poor fluidity and low filling rates. Therefore, silicon carbide is rarely used as the main thermal filler in existing thermal conductive compositions. In view of this, the embodiments of the present application provide a thermal conductive composition containing silicon carbide filler that has both good thermal conductivity and fluidity.

[0044] Specifically, embodiments of the present application provide a thermally conductive composition comprising a base material and a thermally conductive filler distributed within the base material; the thermally conductive filler comprises a large-particle filler and a small-particle filler, wherein the ratio of the average particle size of the large-particle filler to the average particle size of the small-particle filler is greater than 3, and the large-particle filler comprises at least a silicon carbide filler having a sphericity of greater than 0.8. A cured product of this thermally conductive composition can be used as the aforementioned interface thermal conductive material or other materials with thermal conductivity.

[0045] Sphericity is a parameter that characterizes particle morphology. The closer the particle's morphology is to an ideal sphere, the closer its sphericity is to 1. The more irregular the particle's shape, the smaller its sphericity. Silicon carbide fillers have a sphericity of 0.8 or above, indicating a morphology that is closer to an ideal sphere. These silicon carbide fillers can be spherical or quasi-spherical particles.

[0046] The large-particle thermally conductive filler plays a primary role in thermal conductivity in the thermally conductive composition. The large-particle thermally conductive filler includes a silicon carbide filler with a high thermal conductivity coefficient and a sphericity of 0.8 or greater. This highly spherical silicon carbide filler plays a primary role in thermal conductivity in the thermally conductive composition and can be added at a relatively high mass ratio without significantly thickening the composition or affecting its fluidity, resulting in the composition having good applicability and excellent thermal conductivity. Furthermore, the highly spherical silicon carbide filler, as a large-particle thermally conductive filler component, minimizes interfacial contact, reduces interfacial thermal resistance, and minimizes phonon heat dissipation, further facilitating the full utilization of its inherent high thermal conductivity, resulting in even better thermal conductivity for the thermally conductive composition containing this silicon carbide filler.

[0047] Furthermore, by controlling the average particle size ratio of the large-particle filler to the small-particle filler to be greater than or equal to 3, the combination of large and small-particle filler particles can increase the overall packing density of the thermally conductive filler. This means that more thermally conductive filler is packed into a unit space, resulting in more effective thermal conductive pathways formed by the contact between the thermally conductive fillers. Consequently, the thermally conductive composition containing such thermally conductive filler has better thermal conductivity.

[0048] The "sphericity" of the silicon carbide filler specifically refers to its average sphericity, which can be measured based on a scanning electron microscope (SEM) photograph of the silicon carbide filler in combination with image analysis software. For example, the projected area A and projected perimeter PM of a single silicon carbide filler particle can be measured from an SEM photograph containing multiple (e.g., more than 100) silicon carbide filler particles. If the area of ​​the perfect circle corresponding to the perimeter PM is set to B, the sphericity of the particle is A / B. Since B = πr 2 , PM=2πr, so B=π×(PM / 2π) 2 , accordingly, the sphericity of each particle can be calculated according to A / B = A × 4π / (PM)2 The sphericity of 100 random particles is calculated, and the average value is taken as the average sphericity.

[0049] Silicon carbide materials have a high hardness and melting point, making them incapable of spheroidization using commonly used methods such as air flow crushing and melting into balls. However, in the embodiments of the present application, the silicon carbide filler with a sphericity of 0.8 or greater can be obtained by sand-grinding the carbide powder, melting it into balls using a high-temperature plasma flame, or granulating micron-sized silicon carbide powder into balls. This allows the silicon carbide powder to transform from angular particles (sphericity less than 0.5) to highly spherical silicon carbide filler particles, making it less likely to thicken when filled into the thermally conductive composition and achieving a high filling rate.

[0050] In the present application, the sphericity of the silicon carbide filler is within the range of 0.8-1.0, for example, 0.82, 0.83, 0.85, 0.86, 0.88, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.98, 0.99, etc. If the average sphericity of the silicon carbide filler is less than 0.8, the contact between the particles becomes significant, the interfacial thermal resistance increases, and the thermal conductivity of the overall thermally conductive composition is low. In some embodiments, the sphericity is within the range of 0.90-1.0.

[0051] In some embodiments of the present application, the mass content of silicon carbide in the silicon carbide filler with a sphericity of more than 0.8 is greater than or equal to 99.0%. That is, the purity of silicon carbide in the silicon carbide filler with a sphericity of more than 0.8 is greater than or equal to 99.0%. It is understandable that in this case, the mass content of impurity elements in the silicon carbide filler with a sphericity of more than 0.8 is less than or equal to 1%. Among them, the impurity elements include one or more of phosphorus (P), nitrogen (N), oxygen (O), boron (B), iron (Fe), nickel (Ni), etc., but are not limited to this. Among them, the sum of each impurity element and all impurity elements is less than or equal to 1%. Although the theoretical breakdown strength of silicon carbide material is strong and can reach 280KV / mm, as mentioned above, silicon carbide products on the market usually come from the abrasive industry, have low purity, and have more angular particles and are prone to tip discharge. The actual breakdown resistance is only tens to hundreds of volts per millimeter. The high-sphericity silicon carbide filler provided in the embodiment of the present application has a higher purity and a lower impurity content, which is more conducive to improving its breakdown resistance performance.

[0052] In some embodiments of the present application, the mass content of silicon carbide in the silicon carbide filler with a sphericity of 0.8 or greater is greater than or equal to 99.9%. It is understood that in this case, the mass content of impurity elements in the silicon carbide filler with a sphericity of 0.8 or greater is less than or equal to 0.1%. In some embodiments, the mass content of silicon carbide in the silicon carbide filler with a sphericity of 0.8 or greater is greater than or equal to 99.99%. The higher purity of the silicon carbide filler is more conducive to improving its breakdown resistance.

[0053] Exemplarily, in order to increase the content of silicon carbide in silicon carbide filler, when carbon powder and silicon powder are used to prepare silicon carbide powder by high-temperature curing reaction, the silicon powder used is controlled to be high-purity silicon powder with a purity greater than 99%, preferably greater than 99.99%. In addition, the synthesized / commercially available silicon carbide powder can be decarbonized under a high-temperature inert atmosphere to reduce the residual carbon content on the surface of the silicon carbide and reduce its effect on the breakdown resistance of the powder. In addition, in order to reduce the nitrogen content in the silicon carbide filler, the synthesized / commercially available silicon carbide powder can be denitrified. In addition, due to the high hardness of the silicon carbide material, during its air flow crushing and solid transportation process, the transported stainless steel / metal pipe will be scratched, thereby introducing impurity elements such as iron (Fe) and nickel (Ni), which ultimately leads to excessive impurity content. Therefore, it is necessary to perform secondary magnetic separation to purify and reduce the content of magnetic elements such as Fe and Ni.

[0054] In the present application, the content of silicon carbide and the content of impurity elements in the above-mentioned silicon carbide filler can be obtained by performing inductively coupled plasma (ICP) testing, X-ray photoelectron spectroscopy (XPS) testing, or other elemental analysis methods well known in the industry on the silicon carbide filler.

[0055] In some embodiments of the present application, the surface of the silicon carbide filler with a sphericity of more than 0.8 also has an insulating coating. It should be noted that the sphericity in this case specifically refers to the sphericity of the overall composite material composed of the silicon carbide core and the outer coating. Among them, the material of the coating can include insulating materials such as aluminum oxide, magnesium oxide, and silicon oxide. The presence of the insulating coating can improve the breakdown resistance of the silicon carbide filler and its compatibility with the organic matrix (such as resin material) to improve the dispersibility and fluidity of the above-mentioned thermal conductive composition. The thickness of the coating is usually at the nanometer level. Among them, the construction method of the coating can include but is not limited to one or more of co-precipitation method, sol-gel method, hydrothermal / solvothermal method, coating method, ball milling, physical vapor deposition (such as evaporation, ion plating, sputtering, etc.), chemical vapor deposition, etc.

[0056] In an embodiment of the present application, the silicon carbide crystal form of the silicon carbide filler with a sphericity of more than 0.8 can be selected from one or more of the 2H phase, 3C phase, 4H phase, and 6H phase. The thermal conductivity coefficients of silicon carbide materials of different crystal forms are somewhat different, and by controlling the silicon carbide material added to the above-mentioned thermally conductive composition to be selected from the above-mentioned suitable crystal form, the thermal conductivity of the thermally conductive composition and its cured product can be effectively improved. Among them, the 2H phase silicon carbide crystal is an ABAB type hexagonal crystal; the 3C phase silicon carbide crystal is an ABCABC type face-centered cubic crystal; the 4H phase silicon carbide crystal is an ABCBABCB type hexagonal crystal; and the 6H phase silicon carbide crystal is an ABCACB type hexagonal crystal. In some embodiments, the silicon carbide crystal form of the silicon carbide filler is 3C phase (also known as β phase). The thermal conductivity coefficient of the 3C phase silicon carbide material is very high, and it can greatly improve the thermal conductivity of the above-mentioned thermally conductive composition and its cured product. Among them, the silicon carbide crystal form in the silicon carbide filler can be determined by powder X-ray diffraction.

[0057] In the embodiment of the present application, the physicochemical parameters of the silicon carbide filler with a sphericity of more than 0.8 meet the following requirements: the bulk density is greater than 1.5 g / cm 3 The critical breakdown field strength is greater than 200V / mm; the thermal conductivity is greater than 250W / (m·K). The silicon carbide filler particles with high sphericity are rounder and can be densely packed. The bulk density (also known as tap density) can be greater than 1.5g / cm 3 At the same time, silicon carbide fillers with high sphericity are spherical or quasi-spherical with few or no edges, making them less prone to tip discharge and resulting in a higher critical breakdown field strength. In particular, when the silicon carbide content in the silicon carbide filler is greater than or equal to 99.0%, the critical breakdown field strength is even higher. Furthermore, silicon carbide fillers with high sphericity have less contact between particles and reduced interfacial thermal resistance, resulting in a higher thermal conductivity.

[0058] In some embodiments of the present application, the bulk density of the silicon carbide filler with a sphericity of 0.8 or more is greater than or equal to 2.0 g / cm 3 The critical breakdown field strength of the silicon carbide filler with a sphericity of 0.8 or greater is greater than or equal to 500 V / mm. The thermal conductivity of the silicon carbide filler with a sphericity of 0.8 or greater is greater than or equal to 280 W / (m·K).

[0059] In an embodiment of the present application, the particle size of the silicon carbide filler having a sphericity of 0.8 or more is between 1 μm and 300 μm. For example, the particle size may be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 220 μm, 250 μm, 280 μm, etc. Among them, the particle size of the silicon carbide filler having a sphericity of 0.8 or more does not exceed 300 μm, and may further be less than or equal to 200 μm, or less than or equal to 150 μm. The particle size of the silicon carbide filler with a sphericity of 0.8 or greater may be greater than or equal to 30 μm, or greater than or equal to 40 μm, or greater than or equal to 60 μm, or greater than or equal to 80 μm, or greater than or equal to 100 μm, etc.

[0060] In some embodiments, the silicon carbide filler having a sphericity of 0.8 or greater has a particle size between 30 μm and 160 μm, and can further be between 40 μm and 160 μm, 60 μm and 150 μm, or 100 μm and 150 μm. A suitably large particle size range for the silicon carbide filler ensures that it is easier to achieve high sphericity and effectively improves the thermal conductivity of a thermally conductive composition using it as a thermally conductive filler component, while also preventing sedimentation in the thermally conductive composition due to excessively large particle size.

[0061] In some embodiments of the present application, the average particle size of the small-particle filler is less than 5 μm, and the average particle size of the large-particle filler is greater than 20 μm.

[0062] The small-particle filler and the large-particle filler can independently include at least one filler with an average particle size, preferably including at least two fillers with different average particle sizes. Accordingly, the thermally conductive filler in the thermally conductive composition includes at least two filler particles with different average particle sizes (when there are two types, the large-particle filler and the small-particle filler each only include fillers with one average particle size), preferably including at least three filler particles with different average particle sizes (in this case, at least one of the small-particle filler and the large-particle filler includes at least two filler particles with different average particle sizes). In addition, taking the small-particle filler as an example, the two fillers with different average particle sizes can be made of the same material or different materials.

[0063] In some embodiments, the small-particle filler includes a small-particle filler with an average particle size of less than 1 μm (which may be referred to as a first small-particle filler), and a small-particle filler with an average particle size greater than 1 μm and less than or equal to 5 μm (which may be referred to as a second small-particle filler). The small-particle filler has a high filling ability. The use of two small-particle fillers is more conducive to improving the filling rate of the small-particle thermal conductive filler and improving the bulk density of the overall thermal conductive filler. Among them, the average particle size of the small-particle filler may be greater than or equal to 0.1 μm. The average particle size of the small-particle filler with an average particle size of less than 1 μm can specifically be in the range of 0.1 μm-1 μm, for example, specifically 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, or 1.0 μm, etc. The average particle size of the small-particle filler with an average particle size between (1 μm, 5 μm) can specifically be 1.2 μm, 1.5 μm, 2 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, or 5.0 μm.

[0064] For example, the large-particle filler may include one or more of a filler having an average particle size of 30 μm or greater, a filler having an average particle size of 40 μm or greater, a filler having an average particle size of 60 μm or greater, a filler having an average particle size of 80 μm or greater, a filler having an average particle size of 100 μm or greater, and a filler having an average particle size of 120 μm or greater. Accordingly, the average particle size of the carbonized filler having a sphericity of 0.8 or greater may also be selected from one or more of these listed average particle size values, which are not listed one by one.

[0065] In some embodiments of the present application, the average particle size of the large-particle filler is greater than 30 μm. In some embodiments of the present application, the large-particle filler includes a filler with an average particle size of greater than 60 μm; the filler with an average particle size of greater than 60 μm includes the above-mentioned silicon carbide filler with a sphericity of greater than 0.8. That is, in this case, the average particle size of the silicon carbide filler with a sphericity of greater than 0.8 is greater than 60 μm. Furthermore, the average particle size of the silicon carbide filler is less than or equal to 300 μm, that is, between 60 μm and 300 μm, for example, specifically between 60 μm and 150 μm.

[0066] In other embodiments, the large-particle filler includes a filler having an average particle size greater than 20 μm and less than or equal to 40 μm, and a filler having an average particle size of 60 μm or more, and the filler having an average particle size of 60 μm or more includes the above-mentioned silicon carbide filler having a sphericity of 0.8 or more. In this case, the above-mentioned thermal conductive composition containing such silicon carbide filler can achieve higher thermal conductivity and facilitate the realization of a higher filler packing density. For example, the large-particle filler includes a filler having an average particle size of 30 μm and a filler having an average particle size of 120 μm, wherein the filler having an average particle size of 120 μm includes the above-mentioned carbonized filler having a sphericity of 0.8 or more.

[0067] In some other embodiments, the large-particle filler includes a filler having an average particle size of 100 μm or greater, and the filler having an average particle size of 100 μm or greater includes the silicon carbide filler having a sphericity of 0.8 or greater. In this case, the average particle size of the silicon carbide filler having a sphericity of 0.8 or greater is greater than 100 μm, for example, between 100 μm and 300 μm, and further can be between 100 μm and 150 μm.

[0068] In some embodiments of the present application, in addition to the silicon carbide filler having a sphericity of more than 0.8, the large particle size filler may also include one or more of conventional silicon carbide fillers, aluminum nitride fillers, boron nitride fillers, silicon nitride fillers, diamond fillers, etc., but is not limited thereto. Among them, the sphericity of conventional silicon carbide fillers is less than 0.5. The shape of conventional silicon carbide fillers can be spherical or spherical, or polyhedron (such as hexahedron, octahedron, etc.), or irregular shape, etc. In general, the thermal conductivity of large particle size fillers is higher than that of small particle size fillers, which is more conducive to improving the thermal conductivity of the thermally conductive composition containing thermally conductive fillers.

[0069] In the embodiments of the present application, the small-particle filler may be selected from at least one of an oxide (such as zinc oxide, aluminum oxide, magnesium oxide, etc.) and a metal, but is not limited thereto. The metal may include, but is not limited to, one or more of a single metal such as aluminum, silver, copper, gold, tin, indium, or a metal alloy or metal composite (such as aluminum-clad silver, aluminum-clad copper, etc.).

[0070] When the cured product of the thermally conductive composition has no requirements for insulation, the small-particle filler can be arbitrarily selected from the various materials mentioned above. When the cured product of the thermally conductive composition has requirements for insulation, the small-particle filler does not use metal materials, but generally uses oxides containing a large amount of hydroxyl groups on the surface, which have good compatibility with the organic matrix. In some embodiments, the small-particle filler is selected from one or more oxides such as zinc oxide, aluminum oxide, and magnesium oxide. In addition, the morphology of the small-particle filler can be one or more of spherical or quasi-spherical, flaky, fibrous, needle-shaped, amorphous, etc., and spherical or quasi-spherical shapes are more common.

[0071] In some embodiments of the present application, the ratio of the average particle size of the large-particle filler to the average particle size of the small-particle filler is greater than 20. If the large-particle filler and the small-particle filler each include two or more fillers with different average particle sizes, this specifically refers to the ratio of the average particle size of the large-particle thermally conductive filler with the largest average particle size to the small-particle thermally conductive filler with the smallest average particle size being greater than 20. According to theoretical calculations of thermally conductive filler fillings with multiple particle size combinations, a higher average particle size ratio of the large-particle filler to the small-particle filler is more conducive to achieving a higher packing density of the overall thermally conductive filler.

[0072] In some embodiments of the present application, the thermally conductive filler also includes a medium-particle size filler. That is, the thermally conductive filler includes a large-particle size filler, a small-particle size filler and a medium-particle size filler at the same time. Among them, the average particle size of the medium-particle size filler is between the average particle size of the small-particle size filler and the average particle size of the large-particle size filler. In this case, the thermally conductive filler includes at least 3 kinds of thermally conductive filler particles with different average particle sizes. In this case, the ratio of the average particle size of the large-particle size filler to the average particle size of the small-particle size filler is generally above 20. With the help of the coordination between thermally conductive fillers with large, medium and small multi-level particle sizes, it is more conducive to improving the bulk density of the overall thermally conductive filler. Similarly, the medium-particle size filler may include two or more fillers with different average particle sizes, or include a filler with one average particle size.

[0073] In some embodiments, the average particle size of the medium-sized filler is greater than 5 μm and less than or equal to 20 μm. For example, the average particle size of the medium-sized filler may include one or more of 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, etc. In some embodiments, the average particle size of the medium-sized filler is between 10 μm and 20 μm.

[0074] In the embodiment of the present application, the material of the medium-sized filler may include one or more of oxides, carbides, nitrides, and metals. For example, the oxide may be selected from one or more of zinc oxide, aluminum oxide, magnesium oxide, etc. The carbide may be selected from one or more of silicon carbide, boron carbide, tungsten carbide, etc. The nitride may be selected from one or more of aluminum nitride, boron nitride, silicon nitride, etc. The metal may be selected from one or more of aluminum, silver, copper, gold, tin, indium, or their alloys, composites, etc. Similarly, when the cured product of the above-mentioned thermally conductive composition requires insulation, the medium-sized filler does not use a metal material, but may use one or more of oxides, carbides, and nitrides. In addition, the morphology of the medium-sized filler may be selected from one or more of spherical or quasi-spherical, flaky, fibrous, needle-shaped, amorphous, etc.

[0075] It should be noted that, in this application, the terms "large particle size" and "small particle size" are all relative. In different application scenarios, the particle size ranges of large and small particles may vary. For example, in other embodiments of this application, the average particle size of the large particle size filler can be above 10 μm, while the average particle size of the small particle size filler can be less than 10 μm, or even at the nanometer level.

[0076] In this application, the average particle size of each of the materials mentioned above can be measured using a particle size distribution analyzer based on the laser diffraction method. From the obtained particle size distribution curve, the particle size corresponding to the cumulative volume distribution percentage of the material reaching 50% can be read, which is the average particle size, also known as the median particle size or D50 particle size.

[0077] In the embodiment of the present application, the total mass proportion of the thermally conductive filler in the thermally conductive composition is more than 50%, and further in the range of 50%-98%. This ensures that the cured thermally conductive composition using the thermally conductive filler is constructed with a good thermally conductive network, and the thermally conductive composition has appropriate fluidity. Exemplarily, the total mass proportion of the thermally conductive filler in the thermally conductive composition is specifically 60%, 70%, 80%, 85%, 90%, 92%, 93%, 95%, or 97%, etc. In some embodiments, the total mass proportion of the thermally conductive filler is 80%-98%, and can further be 90%-98%. The total mass proportion of the thermally conductive filler here refers to the total mass percentage of the large particle size filler, small particle size filler, and medium particle size filler (if any) contained in the above-mentioned thermally conductive composition.

[0078] Large-particle fillers play a primary role in thermal conductivity in the thermally conductive composition. In embodiments of the present application, the total mass percentage of large-particle fillers in the thermally conductive composition can be in the range of 40%-70%. This not only facilitates good thermal conductivity of the thermally conductive composition, but also prevents phase separation and poor mechanical properties of the cured thermally conductive composition. For example, the total mass percentage of large-particle fillers in the thermally conductive composition can be 42%, 45%, 50%, 55%, 60%, 62%, 65%, 68%, 69%, etc. In some embodiments, the mass percentage of large-particle fillers in the thermally conductive composition is in the range of 45%-68%. Furthermore, based on the weight of all thermally conductive fillers, in embodiments of the present application, the mass percentage of large-particle fillers in the thermally conductive composition can be in the range of 46%-72%, for example, 48%, 49%, 50%, 55%, 60%, 62%, 65%, 68%, 69%, 70%, 71%, etc.

[0079] As described above, in the present application, the large-particle filler includes the above-mentioned silicon carbide filler with a sphericity of 0.8 or more. The mass proportion of the silicon carbide filler with a sphericity of 0.8 or more in the thermally conductive filler can be in the range of 15%-55%, for example, specifically 16%, 20%, 25%, 26%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 49%, 50%, or 52%, and can further be in the range of 16%-52%. Controlling the mass proportion of the high-sphericity silicon carbide filler as a large-particle filler component in all thermally conductive fillers within a suitably high range is more conducive to improving the thermal conductivity of the thermally conductive composition containing the thermally conductive filler. In addition, based on the weight of the thermally conductive composition, the total mass proportion of the silicon carbide filler having a sphericity of 0.8 or greater in the thermally conductive composition may be in the range of 15%-50%, for example, 15%, 20%, 22%, 25%, 30%, 32%, 35%, 40%, 42%, 45%, 47%, or 49%.

[0080] Small-particle fillers play a key role in the rheological properties and stability of the thermally conductive composition. Medium-particle fillers can adjust the rheological properties, stability, and thermal conductivity of the thermally conductive composition. In embodiments of the present application, the total mass proportion of small-particle fillers in the thermally conductive composition can be less than 50%, for example, within the range of 18%-50%. This ensures excellent fluidity of the thermally conductive composition. The total mass proportion of medium-particle fillers in the thermally conductive composition can be no more than 30%, for example, within the range of 15%-26%. This ensures optimal filling of the overall thermally conductive filler. For example, the total mass proportion of small-particle fillers in the thermally conductive composition can be 19%, 20%, 22%, 23%, 25%, 28%, 30%, 33%, 35%, 40%, 45%, 48%, etc. The total mass proportion of medium-particle fillers in the thermally conductive composition can be 16%, 18%, 20%, 22%, 25%, 26%, 30%, etc. In addition, based on the total mass of the thermally conductive filler, the mass percentage of the small particle size filler can be in the range of 19%-52%, and the mass percentage of the medium particle size filler can be in the range of 18%-28%.

[0081] In the present application, the matrix material in the thermally conductive composition serves as a continuous phase, and the dispersed phase (such as various thermally conductive fillers) in the thermally conductive composition can be dispersed in the matrix material. In the embodiments of the present application, the matrix material in the above-mentioned thermally conductive composition can be selected from one of an organic matrix, a metal matrix, and a ceramic matrix. In some embodiments of the present application, the matrix material in the thermally conductive composition is an organic matrix. The organic matrix is ​​particularly suitable for use in application scenarios where insulation is required for the cured product of the thermally conductive composition. The cured product of the thermally conductive composition refers to the product after the thermally conductive composition is cured, and the term "curing" mainly refers to the curing of the organic matrix.

[0082] In the embodiment of the present application, the organic matrix may include at least one of a silicone system, an epoxy system, an acrylic system, a polyurethane system, a polyimide system, a polyester system, a polyolefin system, and the like.

[0083] Examples of curable polymers include silicone polymers, epoxy polymers (such as epoxy resins), polyacrylates, urethane polymers (also known as polyurethanes), phenolic polymers, polyimide polymers, unsaturated polyesters, acrylonitrile butadiene rubber, ethylene-propylene-butadiene rubber, ethylene-propylene rubber, polybutadiene rubber, polyisoprene rubber, and natural rubber.

[0084] In some embodiments, the organic matrix is ​​made of an organosilicon material such as silicone rubber, silicone resin, silicone oil, or epoxy resin, with silicone materials being preferred. Silicone oil is a common name for organopolysiloxane. Generally, the organosilicon material can be an addition-curing organosilicon system or a condensation-curing organosilicon system. In some embodiments, the organosilicon system is an addition-curing organosilicon system, such as an addition polymerization-curing organosilicon rubber.

[0085] In some embodiments of the present application, the organosilicon system is a polysiloxane composition, which includes at least one polysiloxane having a curable functional group in the molecule, and a polysiloxane containing a hydrogen group (Si-H group). The viscosity of the polysiloxane composition at room temperature can be 10cps-2000cps. Wherein, the type of curable functional group is not particularly limited, as long as it is a functional group that can participate in the curing reaction of the resin, preferably an aliphatic unsaturated group such as a (meth) acryloyl or vinyl group that is cured by an addition reaction, more preferably a vinyl group. In addition, in the polysiloxane having a curable functional group in the molecule, the position of the curable functional group is not limited, and can be at the end of the polysiloxane molecular chain or on the side chain inside the molecule. Wherein, the exemplary general formula of the polysiloxane with a curable group at the end of the molecular chain can be:

[0086]

[0087] In formula (I), R a Contains a curable group, each R is independently selected from one or more of hydroxyl, alkyl, alkoxy, alkenyl, aryl, etc.; the value of n should be such that the substance represented by formula (I) is liquid at room temperature. Exemplary R can be at least one of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, methoxy, ethoxy, vinyl, phenyl, etc. Commonly, R is methyl, R a For vinyl.

[0088] In some embodiments of the present application, the addition reaction curing type organosilicon system may include two major basic components, namely, organopolysiloxanes containing alkenyl groups and organopolysiloxanes containing hydrogen groups (Si-H groups). These two types of polysiloxanes can undergo addition reactions under heating conditions to achieve system curing. The hydrogen groups here specifically refer to hydrogen atoms bonded to silicon atoms. In addition, in the case where the organic matrix is ​​an addition reaction curing type organosilicon system, the above-mentioned thermal conductive composition generally also includes functional additives such as catalysts and inhibitors to obtain a composition with better physical and chemical properties. Furthermore, the above-mentioned thermal conductive composition may also include coupling agents and cross-linking agents.

[0089] Among them, the alkenyl-containing organopolysiloxane can be selected from one or more organopolysiloxanes with vinyl groups at both ends, such as polydimethylsiloxane with vinyl groups at both ends, polyphenylmethylsiloxane with vinyl groups at both ends, dimethylsiloxane-diphenylsiloxane copolymer with vinyl groups at both ends, dimethylsiloxane-phenylmethylsiloxane copolymer with vinyl groups at both ends, and dimethylsiloxane-diethylsiloxane copolymer with vinyl groups at both ends.

[0090] The viscosity of the alkenyl group-containing organopolysiloxane at 25° C. may be 5 mPa·s to 10,000 mPa·s, or further 30 mPa·s to 500 mPa·s. The viscosity of the alkenyl group-containing organopolysiloxane may be measured using a rotational viscometer.

[0091] The number of hydrogen atoms bonded to silicon atoms in the hydrogen-containing organopolysiloxane molecule is 2 or more, preferably 2-50. For example, the hydrogen-containing organopolysiloxane can be selected from one or more of methylhydrogensiloxane-dimethylsiloxane copolymer, polymethylhydrogensiloxane, polyethylhydrogensiloxane, methylhydrogensiloxane-phenylmethylsiloxane copolymer, and the like. The molar ratio of the silicon hydrogen groups in the hydrogen-containing organopolysiloxane to the alkenyl groups in the alkenyl-containing organopolysiloxane can be 0.3-3, for example, specifically 0.5, 0.8, 1.0, 1.2, 1.5, 2.0, 2.2, 2.5, or 2.8. This ensures that the mixed system containing these two polysiloxanes has a suitable curing speed and a suitable hardness of the cured product.

[0092] The viscosity of the hydrogen group-containing organopolysiloxane at 25°C is not particularly limited, but is, for example, within the range of 1 mPa·s to 1000 mPa·s. It is sufficient as long as the hydrogen group-containing organopolysiloxane can be mixed with the alkenyl group-containing organopolysiloxane and cured to form a polymer with good physical properties. The viscosity of the hydrogen group-containing organopolysiloxane can be measured using a rotational viscometer.

[0093] The catalyst is used to catalyze the hydrosilylation reaction between an alkenyl group and a silyl group. The catalyst can be a precious metal catalyst, specifically a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, or the like. In some embodiments, the catalyst is a platinum-based catalyst, for example, one or more of common platinum-based catalysts such as elemental platinum, oxyplatinic acid, a platinum-olefin complex, a platinum-alcohol complex, and a platinum coordination compound. The content of the catalyst in the thermally conductive composition can be 0.1 ppm to 300 ppm, and further can be 0.1 ppm to 200 ppm.

[0094] The inhibitor is primarily used to inhibit the reaction between the silyl groups and alkenyl groups in the thermally conductive composition at room temperature, preventing their premature consumption, ensuring good room-temperature fluidity, and improving the room-temperature storage properties of the thermally conductive composition. In embodiments of the present application, the inhibitor can be selected from one or more of acetylene alcohols (such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol), organophosphorus compounds (such as triphenylphosphine), nitrogen-containing compounds (such as triallyl isocyanurate or its derivatives), and diallyl maleate. The content of the inhibitor in the thermally conductive composition can range from 0.01 wt% to 5 wt%, and further can range from 0.1 wt% to 1 wt%.

[0095] Furthermore, when using the aforementioned addition-curable silicone system as the organic matrix, the thermally conductive composition can be formulated as a two-component system or a one-component system. A two-component system refers to a thermally conductive composition consisting of two separately stored components that are then mixed and cured upon use. A one-component system involves adding various thermally conductive fillers and additives to the organic matrix to form a complete thermally conductive composition.

[0096] Similarly, when the organic matrix is ​​an epoxy resin, acrylic resin, or urethane resin, the above-mentioned thermal conductive composition may also contain a curing agent. The thermal conductive composition can be a one-component system or a two-component system. If it is a two-component system, the curing agent and the main resin component that reacts with it are usually stored separately. Among them, amine compounds are more common curing agents for epoxy resins. The curing agent for acrylic resins is usually an isocyanate compound. The curing agent used to form urethane resin is usually an isocyanate compound, and the main resin is usually a polyol resin.

[0097] To improve the wettability and interaction between the thermally conductive filler and the organic matrix, and to prevent agglomeration of the thermally conductive filler and thus increase viscosity, a filler treatment agent may be added to the thermally conductive composition of the present application. The filler treatment agent may be selected from one or more of silane compounds, organotitanium compounds, organoaluminum compounds, and phosphate compounds, with silane compounds being preferred. When the filler treatment agent is a silane compound, it may also be referred to as a silane coupling agent.

[0098] The siloxane compound used as the filler treatment agent can be selected from alkoxysilanes or chlorosilanes, preferably alkoxysilanes. For example, the alkoxysilane can be selected from one or more of n-decyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, dialkyldialkoxysilane, aryltrialkoxysilane, diaryldialkoxysilane, α-trimethylsiloxy-ω-(γ-trimethoxysilylethyl)dimethylsilyl-terminated polydimethylsiloxane, and the like.

[0099] In addition, the thermally conductive composition of the embodiment of the present application may further be added with at least one additive such as an anti-settling agent, an antioxidant, a heat stabilizer, a colorant, a flame retardant, an antistatic agent, etc. as needed, but is not limited thereto.

[0100] In the embodiments of the present application, the extrusion rate of the thermally conductive composition at a pressure of 0.62 MPa is greater than 6.0 g / min; the thermal conductivity of the thermally conductive composition is greater than 7.0 W / (m·K) (watts per meter per degree Kelvin). This higher extrusion rate reflects the higher fluidity of the thermally conductive composition, as well as the higher thermal conductivity and better thermal conductivity of the thermally conductive composition. It is understood that the thermal conductivity of the thermally conductive composition can essentially be reflected by the thermal conductivity of its cured product.

[0101] In some embodiments, the extrusion rate of the thermally conductive composition at a pressure of 0.62 MPa is greater than 7.0 g / min or greater than 8.0 g / min. In some embodiments, the extrusion rate is 6.0-20.0 g / min, for example, 7.0 g / min, 7.5 g / min, 8.0 g / min, 8.5 g / min, 8.8 g / min, 9.0 g / min, 9.2 g / min, 9.5 g / min, 9.6 g / min, 9.8 g / min, 10.0 g / min, 10.2 g / min, 10.5 g / min, 11 g / min, 11.5 g / min, 12 g / min, 12.5 g / min, 13 g / min, 13.5 g / min, 14 g / min, 14.5 g / min, 15 g / min, 16 g / min, 17 g / min, 18 g / min, or 19 g / min, and can further be in the range of 6.0-15.0 g / min, 7.0-15.0 g / min, or 8.0-12.0 g / min.

[0102] In some embodiments of the present application, the thermal conductivity of the thermally conductive composition is in the range of 7.0-12.0 W / (m·K), for example, 7.5 W / (m·K), 7.6 W / (m·K), 7.8 W / (m·K), 7.9 W / (m·K), 8.0 W / (m·K), 8.1 W / (m·K), 8.2 W / (m·K), 8.5 W / (m·K), 8.6 W / (m·K), 8.7 W / (m·K), 8.8 W / (m·K), 9.0 W / (m·K), 9.1 W / (m·K), 9.2 W / (m·K), / (m·K), 9.3W / (m·K), 9.5W / (m·K), 9.7W / (m·K), 9.8W / (m·K), 9.9W / (m·K), 10.0W / (m·K), 10.1W / (m·K), 10.2W / (m·K), 10.3W / (m·K), 10.4W / (m·K), 10.5W / (m·K), 10.7W / (m·K), 10.8W / (m·K), 11.0W / (m·K), 11.5W / (m·K), or 12W / (m·K), etc.

[0103] The thermal conductivity of the thermally conductive composition can be measured according to the ISO 22007-2 standard or the ASTM 5470 standard. In some embodiments, the thermal conductivity of the thermally conductive composition measured according to the ISO 22007-2 standard is above 7.5 W / (m·K), and can further be above 7.9 W / (m·K), above 8.0 W / (m·K), above 8.5 W / (m·K), or above 9.0 W / (m·K). In some embodiments, the thermal conductivity is within the range of 7.5-12.0 W / (m·K). In other embodiments, the thermal conductivity of the thermally conductive composition measured according to the ASTM 5470 standard is within the range of 7.0-10.0 W / (m·K).

[0104] The present invention also provides a method for preparing a thermally conductive composition, comprising the following steps:

[0105] (1) spheroidizing silicon carbide powder to obtain silicon carbide filler with a sphericity of 0.8 or more; wherein the spheroidizing treatment includes one or more of sand grinding, high-temperature plasma flame melting into balls, and micro-powder granulation into balls;

[0106] (2) Mixing a small-particle thermally conductive filler, a large-particle thermally conductive filler including the silicon carbide filler having a sphericity of 0.8 or greater, and a matrix material to obtain a thermally conductive composition.

[0107] In step (1), most of the silicon carbide powders on the market come from the abrasive industry, and their sphericity is too low, generally below 0.5. In addition, due to the large hardness and high melting point of silicon carbide, conventional sphericization methods such as air flow crushing and melting into balls cannot achieve sphericization treatment on it. To this end, the applicant provides an effective sphericization method for superhard silicon carbide powder, which can be sand grinding, or high-temperature plasma flame melting into balls, or granulating micron-sized silicon carbide powder into balls, thereby converting silicon carbide powder from particles with sharp edges and corners into particles with a sphericity of more than 0.8, or even more than 0.9, so that it can show a higher filling fraction and flow characteristics in the thermal conductive composition.

[0108] In some embodiments of the present application, in step (1), before the spheroidization treatment, the silicon carbide powder is further subjected to decarbonization treatment, denitrification treatment, and magnetic separation treatment to reduce the residual carbon content, residual nitrogen content, and magnetic element (iron, nickel, etc.) content.

[0109] In some embodiments of the present application, in step (1), after the spheroidization treatment, the process further comprises: coating the silicon carbide particles obtained after the spheroidization treatment to form a coating layer on the surface thereof. The material and formation method of the coating layer can be found in the description above.

[0110] In some embodiments of the present application, in step (2), the raw materials forming the thermally conductive composition further include a medium-particle-sized thermally conductive filler. In this case, step (2) comprises: mixing the small-particle-sized thermally conductive filler, the large-particle-sized thermally conductive filler, and the medium-particle-sized thermally conductive filler with a base material to obtain a thermally conductive composition. For properties such as the material, particle size, and content of the small-particle-sized thermally conductive filler, the large-particle-sized thermally conductive filler, and the medium-particle-sized thermally conductive filler, please refer to the description above in this application.

[0111] In some embodiments of the present application, in step (2), the thermally conductive composition further comprises a catalyst, an inhibitor, a filler treatment agent (such as a coupling agent), a cross-linking agent, and other functional additives. Accordingly, during the mixing, these components should be weighed to participate in the mixing.

[0112] Step (2) is the mixing process of the components constituting the thermally conductive composition. The "mixing" can be carried out in a mixing device such as a homogenizer, a planetary mixer, a meshing disperser, a mechanical fusion machine, a sand mill (such as a three-roll grinder). Among them, the components constituting the thermally conductive composition can be added together or added in batches. An example of adding in batches is as follows: first, the matrix material and the optional functional additives such as the filler treatment agent are added to the mixing device for mixing, and then small-particle-diameter thermally conductive fillers and medium-particle-diameter thermally conductive fillers (if any) are added, and then large-particle-diameter thermally conductive fillers are added after mixing, and mixed evenly. Generally, during or after the mixing, it is necessary to eliminate bubbles in the system. Among them, the way to eliminate bubbles can be vacuuming, ultrasound, standing, etc.

[0113] The interface thermal conductive material mentioned above in this application can be obtained by curing the above-mentioned thermal conductive composition, and the "curing" specifically refers to the curing of the base material. There is no special limitation on the curing process, and the curing process can be selected / regulated according to the type of base material. For example, when the base material is the above-mentioned addition reaction curing type silicone system, it is usually cured by heating. The common heating curing temperature can be in the range of 100-250°C, and the heating time can vary from half an hour to several hours. For example, when the base material is epoxy resin, acrylic resin, or urethane resin, the curing process is generally also heating curing. For another example, when the base material is the above-mentioned condensation reaction curing type silicone system, curing can be adopted under humid conditions, such as in humid air, or curing under humidified conditions.

[0114] In addition, before curing, the thermally conductive composition can be coated into a gasket, film, or other irregular shape according to product requirements. After curing, the resulting solidified product can be packaged or cut according to product requirements.

[0115] The present application also provides a thermally conductive material comprising a cured product of the thermally conductive composition described in the present application. Accordingly, the present application also provides the use of the thermally conductive composition in a thermally conductive material. It is understood that the thermally conductive material comprises a cured product of a base material and a thermally conductive filler distributed therein.

[0116] Furthermore, it should be noted that the thermally conductive material is not limited to any form and may be a thermally conductive film, a thermally conductive gasket, or a thermally conductive gel. The thermally conductive material may be an insulating material or a conductive material. As previously described in this application, if the thermally conductive material is a conductive material, the base material may be a metal material; and / or the thermally conductive filler may comprise a metal material.

[0117] The thermally conductive material of the embodiment of the present application can be arranged on a heating element or a heat sink. In some cases, the thermally conductive material is arranged between the heating element and the heat sink. Among them, the heating element may include one or more of a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), a SOC (system on chip), an LSI (Large Scale Integration), an integrated circuit (Integrated Circuit, IC), a power transistor, a power module, a diode, a resistor, an inductor, a temperature sensor, a power supply, etc., but not limited thereto. The heat sink may include one or more of a radiator, a heat sink, a heat sink, a heat pipe, a heat sink cover, etc., but not limited thereto.

[0118] The present application also provides an electronic device, which includes the cured product of the thermally conductive composition according to the present application. That is, the electronic device includes the thermally conductive material.

[0119] As previously mentioned in this application Figure 1 As shown, the electronic device includes one or more heat-generating electronic components (also referred to as "heat source components", such as chips 12), a heat sink 14, and an interface thermal conductive material 13 located between each chip 12 and the heat sink 14. The interface thermal conductive material 13 can be a cured product of the above-mentioned thermal conductive composition of the embodiment of the present application. Figure 2 As shown, in the chip package, the interface thermal conductive material disposed between the chip 122 and the heat dissipation cover 124 may also be a cured product of the thermal conductive composition described above in the embodiment of the present application.

[0120] In addition, as mentioned above, in addition to chips, electronic components can also be one or more of CPU, GPU, SOC, power transistor, power module, diode, resistor, inductor, temperature sensor, power supply, etc.

[0121] In other embodiments of the present application, the aforementioned thermally conductive material can also be used for interfacial heat conduction between a thermally conductive structural component and another thermally conductive structural component in an electronic device. For example, the electronic device includes a first thermally conductive structural component and a second thermally conductive structural component, and a thermally conductive material disposed between the first and second thermally conductive structural components, the thermally conductive material comprising a cured product of the aforementioned thermally conductive composition. The first thermally conductive structural component can be the structural housing of a functional module in the electronic device, and the second thermally conductive structural component can be the structural housing of another functional module in the electronic device.

[0122] In the embodiment of the present application, the above-mentioned electronic devices may include but are not limited to mobile phones, tablet computers, laptops, wearable devices (such as glasses, watches, bracelets, etc.), televisions, burners, digital cameras, game consoles, adapters, routers, gateways, vehicle-mounted equipment, cars, battery systems and other various devices with heat dissipation requirements.

[0123] The embodiments of the present application are further described below with reference to a number of embodiments.

[0124] Before introducing the specific embodiments of the present application, the components involved below are introduced.

[0125] Silicone materials

[0126] a-1: vinyl group-containing organopolysiloxane, specifically dimethylvinylsiloxy-terminated dimethylpolysiloxane having a viscosity of 50 mPa·s (ie, 50 cps) at 25° C. and a vinyl content of 0.6 mmol / g.

[0127] a-2: Hydrogen-containing organopolysiloxane, specifically dimethylhydrogensiloxy-terminated dimethylpolysiloxane, having a viscosity of 30 mPa·s at 25° C. and a mass percentage of hydrogen atoms directly bonded to silicon atoms of 0.078%.

[0128] Filler treatment agent

[0129] b-1: polydimethylsiloxane terminated with α-trimethylsilyloxy-ω-(γ-trimethoxysilylethyl)dimethylsilyl, with a viscosity of 30 mPa·s at 25° C. and a number of chain segments n=22.

[0130] b-2: n-Hexyltrimethoxysilane.

[0131] <c>Thermally conductive fillers

[0132] c-1: Zinc oxide (ZnO) with an average particle size of 0.2 μm, in a polyhedral shape.

[0133] c-2: Alumina (Al2O3) with an average particle size of 5 μm, spherical.

[0134] c-3: Alumina (Al2O3) with an average particle size of 20 μm, spherical.

[0135] c-4: unshaped silicon carbide (SiC) with an average particle size of 120 μm, a purity of 99.0%, and an average sphericity of 0.5.

[0136] c-5: Shaped silicon carbide with an average particle size of 120 μm and a purity of 99.99%, spherical or quasi-spherical, with an average sphericity of 0.9.

[0137] c-6: Shaped silicon carbide with an average particle size of 120 μm and a purity of 99.0%, spherical or quasi-spherical, and an average sphericity of 0.9.

[0138] c-7: Coated silicon carbide with an average particle size of 120 μm, spherical or quasi-spherical, an average sphericity of 0.9, a core of 99.0% pure shaped silicon carbide, and a coating of insulating oxide.

[0139] c-8: Granulated silicon carbide having an average particle size of 120 μm and a purity of 99.0%, spherical in shape, and an average sphericity of 0.95.

[0140] c-9: Aluminum nitride (AlN) with an average particle size of 120 μm, spherical.

[0141] c-10: Aluminum nitride with an average particle size of 30 μm, spherical or quasi-spherical.

[0142] c-11: Silicon carbide with an average particle size of 30 μm, an average sphericity of 0.5, and a purity of 90%.

[0143] c-12: magnesium oxide (MgO) with an average particle size of 120 μm, spherical.

[0144] c-13: artificial diamond with an average particle size of 120 μm, untreated, polyhedral.

[0145] c-14: Alumina (Al2O3) with an average particle size of 120 μm, spherical.

[0146] <d>catalyst

[0147] d-1: 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex in a polysiloxane diluent, with a platinum content of 1000 ppm.

[0148] <e>inhibitors

[0149] e-1: 2-methyl-3-butyn-2-ol.

[0150] Examples 1-4 and Comparative Example 1

[0151] The components of the thermally conductive composition and their weight percentages shown in Table 1 were weighed and mixed in a homogenizer to produce thermally conductive compositions. The homogenizer was used for mixing by first stirring at 1500 rpm for 30 seconds and then at 2000 rpm for 30 seconds. The resulting thermally conductive compositions were allowed to stand overnight at room temperature and then tested for thermal conductivity, flowability, and dielectric strength. The results are summarized in Table 1.

[0152] Thermal Conductivity Test 1: According to ISO 22007-2, the thermal conductivity of the sample (denoted as TC-1) was tested using a Hot Disk transient technology thermal conductivity tester. Each thermally conductive composition was filled into two cups, and a planar sensor with a self-heating function was placed inside the cup. Using fine-tuning analysis, temperature drift compensation and time correction were selected between the 50-150 and 50-190 points on the instrument. During the test, the planar sensor was heated at 500mW for 2-5s, and the temperature (resistance) of the sensor during heating was measured over time. The thermal conductivity of the sample was then determined through mathematical model fitting.

[0153] Thermal Conductivity Test 2: According to ASTM D5470, a steady-state thermal resistance meter was used to test the thermal conductivity of the samples (denoted as TC-2). Each thermally conductive composition was applied to one end of a copper rod at varying thicknesses. Under a pressure of 40 psi, the temperature was gradually raised from room temperature to 80°C. Steady-state heat transfer was used to measure the thermal resistance of the thermally conductive material at varying thicknesses (0.5 mm, 1.0 mm, and 1.5 mm). The thermal conductivity of each thermally conductive and absorbent composition was then fitted.

[0154] Flowability Test: The extrusion rate (ER) of the thermally conductive composition was measured using a fluid dispensing device to assess its fluidity. Each thermally conductive composition was packaged into a 50cc twin syringe, fitted with a 21-section two-component mixing hose, and dispensed at a pressure of 0.62 MPa. The weight of the sample dispensed within 1 minute was recorded as the ER.

[0155] Dielectric strength test: After curing each thermally conductive composition at 60° C. for 12 hours, the insulation breakdown electric field strength (ie, dielectric strength) of the cured product of each thermally conductive composition was tested according to ASTM D149.

[0156] Table 1

[0157]

[0158] Note: "NG" in Table 1 represents sample data that was not successfully measured.

[0159] It can be seen from Table 1 that, when other components in the thermally conductive composition are the same, the use of high-sphericity silicon carbide (c-5 to c-8) as one of the thermally conductive filler components (specifically as a large-particle filler component) is compared to the use of unshaped SiC powder with low sphericity. The resulting thermally conductive composition has good fluidity and high breakdown resistance (good insulation), while the thermal conductivity is not significantly reduced, and even has a certain improvement. Furthermore, when the purity of the high-sphericity silicon carbide is above 99.0% (such as c-5 and c-6), the thermal conductivity of the thermally conductive composition is improved to a certain extent, and the higher the purity of the silicon carbide, the more obvious the improvement in the breakdown resistance of the material. In addition, surface coating of the SiC powder (such as c-7) is more conducive to improving the breakdown resistance and fluidity of the thermally conductive composition, but some thermal conductivity will be sacrificed accordingly.

[0160] Examples 5-11

[0161] According to the component ratios of the thermally conductive compositions shown in Table 2, various thermally conductive compositions were prepared and tested for thermal conductivity, fluidity, dielectric strength, etc. The results are also summarized in Table 2.

[0162] Table 2

[0163]

[0164]

[0165] As can be seen from Table 2, when the thermal conductive composition contains a high-sphericity, high-purity silicon carbide material (c-5) as a large-particle thermal conductive filler, the thermal conductivity and fluidity of the thermal conductive composition can also be adjusted by grading it with other fillers with an average particle size smaller than the large-particle size.

[0166] Examples 12-16

[0167] According to the component ratios of the thermally conductive compositions shown in Table 3, various thermally conductive compositions were prepared and tested for thermal conductivity, fluidity, dielectric strength, etc. The results are also summarized in Table 3.

[0168] Table 3

[0169]

[0170] Table 3 shows that when a thermally conductive composition contains a highly spherical coated silicon carbide material (c-7) as a large-particle filler component, the addition of large-particle aluminum nitride powder (c-9) with an average particle size of 120 μm and alumina, aluminum nitride, or silicon carbide (c-3, c-10, or c-11) with an average particle size of 20-30 μm can also achieve both good flowability and thermal conductivity. A comparison of Examples 12-14 shows that, under the same conditions, Example 14, which incorporates c-3 (alumina), exhibits slightly lower thermal conductivity.

[0171] Example 1 and Comparative Examples 2-5

[0172] Based on the component ratios of the thermally conductive compositions shown in Table 4, thermally conductive compositions of various comparative examples were prepared and tested for thermal conductivity, fluidity, aging resistance, and other characteristics. The results are summarized in Table 4. Furthermore, for better comparison, the formulation and related test results of the thermally conductive composition of Example 1 are also summarized in Table 4.

[0173] The high-temperature aging test, double 85°C aging test, and temperature cycle aging test in Table 4 below all used a sandwich-structured thermal resistance fixture with a cured thermal conductive composition (i.e., a corresponding thermal conductive composition was coated between two glass plates, and the thermal conductive composition was cured by heating to obtain the thermal resistance fixture).

[0174] Among them, the high-temperature aging test specifically involves placing the above-mentioned sandwich structure thermal resistance tooling in a high-temperature environment of 125°C for 2000 hours, observing the appearance of the thermal conductive composition cured film for cracks, and testing the thermal resistance change rate of the cured film before and after the high-temperature aging test (that is, the ratio of the difference between the thermal resistance value before the high-temperature aging test and the thermal resistance value after high-temperature aging to the thermal resistance value before the high-temperature aging test).

[0175] The temperature cycle aging test specifically involves taking the above-mentioned sandwich structure thermal resistance fixture and testing its thermal resistance value at room temperature. The above-mentioned thermal resistance fixture is then placed at -40°C for 15 minutes and then at 125°C for 15 minutes (one temperature cycle). The appearance of the thermal conductive composition cured film after undergoing a certain cycle (total test time is 2000 hours) is observed (for example, whether sag occurs), and the thermal resistance change rate of the cured film before and after the temperature cycle aging test is tested.

[0176] The double 85 aging test specifically involves placing the above-mentioned sandwich structure thermal resistance tooling in an environment with a temperature of 85°C and a relative humidity of 85% (referred to as double 85) for 2000 hours, observing whether there are any abnormalities in the appearance of the thermal conductive composition cured film, and testing the thermal resistance change rate of the cured film before and after the double 85 aging test.

[0177] Table 4

[0178]

[0179] Table 4 shows that, when the small-particle thermally conductive filler and other non-filler components in the thermally conductive composition are the same, when the large-particle thermally conductive filler with an average particle size of 120 μm, using the highly spherical silicon carbide (C-5) provided in the examples of this application, exhibits superior thermal resistance stability and a higher thermal conductivity than the cured thermally conductive composition using aluminum nitride (C-9) or magnesium oxide (C-12). When the large-particle thermally conductive filler using the highly spherical silicon carbide provided in this application, the cured thermally conductive composition exhibits higher thermal resistance stability and a better thermal performance-to-price ratio than when using diamond (C-13), and exhibits superior thermal conductivity compared to when using aluminum oxide (C-14).

[0180] The above merely represents several exemplary embodiments of the present application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art would be able to make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

[0181] It should be understood that the first, second and various numerical numbers involved in this document are only distinguished for the convenience of description and are not intended to limit the scope of this application.

[0182] In this application, "and / or" describes the relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the related objects are in an "or" relationship.

[0183] In the description of this application, unless otherwise specified, "multiple" means greater than or equal to two. "At least one" means one or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or plural, respectively.

[0184] In addition, the numerical range represented by "-" in this application refers to the range that includes the numerical values ​​recorded before and after "-" as the minimum and maximum values, respectively. In this application, expressions about parameter ranges, such as "greater than or equal to (≥)", "less than or equal to (≤)", "above...", and "below..." all include the number itself. The numerical values ​​and numerical ranges involved in the embodiments of this application are approximate values. Due to the influence of manufacturing process / testing method, etc., there may be a certain range of errors, which can be considered negligible by those skilled in the art.< / e> < / d> < / c>

Claims

1. A thermally conductive composition, characterized in that: The thermally conductive composition includes a matrix material and a thermally conductive filler distributed in the matrix material; the thermally conductive filler includes a large-particle filler and a small-particle filler, wherein the ratio of the average particle size of the large-particle filler to the average particle size of the small-particle filler is greater than 3, and the large-particle filler includes at least a silicon carbide filler with a sphericity of greater than 0.

8.

2. The thermally conductive composition according to claim 1, wherein The mass content of silicon carbide in the silicon carbide filler with a sphericity of 0.8 or higher is greater than or equal to 99.0%.

3. The thermally conductive composition according to claim 2, wherein The mass content of silicon carbide in the silicon carbide filler with a sphericity of 0.8 or more is greater than or equal to 99.9%.

4. The thermally conductive composition according to any one of claims 1 to 3, wherein The surface of the silicon carbide filler with a sphericity of 0.8 or greater further has an insulating coating layer.

5. The thermally conductive composition according to any one of claims 1 to 4, wherein The silicon carbide filler having a sphericity of greater than 0.8 has a silicon carbide crystal form selected from one or more of 2H phase, 3C phase, 4H phase, and 6H phase.

6. The thermally conductive composition according to any one of claims 1 to 5, wherein The physicochemical parameters of the silicon carbide filler with a sphericity of more than 0.8 meet the following requirements: the bulk density is greater than 1.5 g / cm 3 ; Critical breakdown field strength is greater than 200V / mm; thermal conductivity is greater than 250W / (m·K).

7. The thermally conductive composition according to any one of claims 1 to 6, wherein The average particle size of the small-particle filler is less than 5 μm, and the average particle size of the large-particle filler is greater than 20 μm.

8. The thermally conductive composition according to claim 7, wherein The average particle size of the large-particle filler is greater than 30 μm.

9. The thermally conductive composition according to any one of claims 7 to 8, wherein The large-particle filler includes a filler with an average particle size of 60 μm or more; the filler with an average particle size of 60 μm or more includes the silicon carbide filler with a sphericity of 0.8 or more.

10. The thermally conductive composition according to claim 9, wherein The average particle size of the silicon carbide filler with a sphericity of greater than 0.8 is between 60 μm and 150 μm.

11. The thermally conductive composition according to any one of claims 1 to 10, wherein The large-particle filler further includes one or more of conventional silicon carbide filler, aluminum nitride filler, boron nitride filler, silicon nitride filler, and diamond filler; wherein the sphericity of the conventional silicon carbide filler is below 0.

5.

12. The thermally conductive composition according to any one of claims 7 to 11, wherein The small-particle filler includes at least two types of filler particles, one having an average particle size of less than 1 μm and the other having an average particle size of greater than 1 μm and less than or equal to 5 μm.

13. The thermally conductive composition according to any one of claims 1 to 12, wherein: The small particle size filler includes one or more of zinc oxide, aluminum oxide, and magnesium oxide.

14. The thermally conductive composition according to any one of claims 1 to 13, wherein The thermally conductive filler further includes a medium-sized particle filler, wherein the average particle size of the medium-sized particle filler is between that of the large-sized particle filler and the small-sized particle filler.

15. The thermally conductive composition according to claim 14, wherein The average particle size of the medium-sized filler is greater than 5 μm and less than or equal to 20 μm.

16. The thermally conductive composition according to claim 14 or 15, wherein The medium-sized filler includes one or more of oxides, carbides, nitrides, and metals.

17. The thermally conductive composition according to any one of claims 1 to 16, wherein The mass proportion of the silicon carbide filler with a sphericity of greater than 0.8 in the thermal conductive filler is in the range of 15%-55%.

18. The thermally conductive composition according to any one of claims 1 to 17, wherein The total mass proportion of the large particle size filler in the thermal conductive composition is in the range of 40%-70%.

19. The thermally conductive composition according to any one of claims 1 to 18, wherein The thermally conductive filler accounts for 50% to 98% of the total mass of the thermally conductive composition.

20. The thermally conductive composition according to any one of claims 1 to 19, wherein The matrix material is an organic matrix; the organic matrix includes at least one of an organic silicon system, an epoxy system, an acrylic system, a polyurethane system, a polyimide system, a polyester system, and a polyolefin system.

21. The thermally conductive composition according to claim 20, wherein The organic silicon system is an addition reaction curing organic silicon system; the thermal conductive composition further comprises a catalyst and an inhibitor.

22. The thermally conductive composition according to any one of claims 1 to 21, wherein The thermally conductive composition also includes a filler treating agent.

23. The thermally conductive composition according to any one of claims 1 to 21, wherein The extrusion rate of the thermally conductive composition under a pressure of 0.62 MPa is above 6.0 g / min; and the thermal conductivity of the cured product of the thermally conductive composition is above 7.0 W / (m·K).

24. A method for preparing a thermally conductive composition, characterized in that: The following steps are involved: Spheroidizing the silicon carbide powder to obtain a silicon carbide filler with a sphericity of 0.8 or more; wherein the spheroidizing treatment includes one or more of sand grinding, high-temperature plasma flame melting into balls, and micro-powder granulation into balls; The thermally conductive filler with a small particle size, the thermally conductive filler with a large particle size including the silicon carbide filler with a sphericity of 0.8 or more, and the matrix material are mixed to obtain a thermally conductive composition.

25. A thermally conductive material, characterized in that: A cured product comprising the thermally conductive composition according to any one of claims 1 to 23.

26. An electronic device, characterized in that: A cured product comprising the thermally conductive composition according to any one of claims 1 to 23.

27. The electronic device according to claim 26, wherein: The electronic device includes an electronic component and a heat sink disposed on the electronic component, wherein an interface thermal conductive material is disposed between the electronic component and the heat sink, and the interface thermal conductive material includes a cured product of the thermal conductive composition.

28. The electronic device according to claim 27, wherein: The electronic component is a packaged chip, which includes a substrate, a chip arranged on the substrate, and a heat dissipation cover. The chip is located in a housing space enclosed by the heat dissipation cover and the substrate. A second interface thermal conductive material is further provided between a surface of the chip facing away from the substrate and the heat dissipation cover. The second interface thermal conductive material includes a cured product of the thermally conductive composition according to any one of claims 1 to 22.

29. The electronic device according to claim 26, wherein The electronic device includes a first heat-conducting structure and a second heat-conducting structure, and a heat-conducting material disposed between the first heat-conducting structure and the second heat-conducting structure. The heat-conducting material includes a cured product of the heat-conducting composition.

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