Ceramic heat-conducting composite material and preparation method thereof

Abstract

The invention relates to the technical field of heat-conducting and electric-conducting bonding materials, in particular to a ceramic heat-conducting composite material and a preparation method thereof. The ceramic heat-conducting composite material is prepared from a ceramic heat-conducting material, silver powder, nickel powder and an auxiliary agent, the ceramic heat-conducting material further comprises modified boron nitride, and the modified boron nitride is prepared by reacting the silver powder with the nickel powder under the action of p-toluenesulfonic acid. And mixing and reacting the silver-loaded carboxylated nanocellulose, epoxy-terminated hyperbranched polyester and epoxidized boron oxide particles to obtain the silver-loaded hyperbranched polyester / epoxidized boron oxide composite material. The ceramic heat-conducting composite material disclosed by the invention has high heat conductivity, high strength and high conductivity, solves the problem of non-uniform performance of a traditional packaging material caused by filler agglomeration, and is particularly suitable for advanced packaging of high-power electronic devices.

Description

Technical Field

[0001] The present invention relates to the technical field of thermally conductive and electrically conductive adhesive materials, and in particular to a ceramic thermally conductive composite material and a preparation method thereof. Background Art

[0002] With the rapid development of electronic technology, especially the miniaturization and functionalization of electronic chips, packaging materials are required to have high thermal and electrical conductivity.

[0003] In the field of chip packaging, the commonly used thermally conductive and electrically conductive materials are mainly solder paste and conductive adhesive. Tin solder paste achieves the packaging effect by melting tin to bond the metal plating on the surface of the substrate and the component. The thermal and electrical conductivity of tin itself is not as good as that of metals such as silver and copper, and the thermal conductivity coefficient of tin solder paste is often less than 60W / m·k. Secondly, tin solder paste has reliability issues such as voids caused by high and low temperature cycles, resulting in low bonding performance, and cannot meet the high temperature resistance and high bonding performance requirements of integrated circuits. Conductive adhesive is a polymer adhesive with an organic resin as the bonding phase and conductive particles as the conductive phase. It has high organic residue and a thermal conductivity coefficient generally not exceeding 20W / m·k. Therefore, ceramic thermal conductive composite materials with low organic residue and high electrical and thermal conductivity can replace tin solder paste and conductive adhesive to become high thermal and electrical conductive chip packaging materials.

[0004] Patent technical document CN113582702A discloses an aluminum nitride ceramic composite material for electronic packaging and its preparation method. The invention combines aluminum nitride with aluminum oxide and nitride to produce a thermal expansion mismatch, thereby generating a residual stress field, improving the thermal conductivity of the ceramic composite material, enhancing the toughness of the ceramic composite material, and effectively improving the strength of the ceramic composite material.

[0005] However, due to the presence of a large amount of inorganic fillers in the system, the uneven dispersion of the fillers will inevitably lead to discontinuous thermal and electrical conduction networks and affect the mechanical properties. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a ceramic thermal conductive composite material and a preparation method thereof, so as to solve the problem that the mechanical, thermal and electrical conductivity of the composite material are poor due to agglomeration of the traditional ceramic thermal conductive composite material.

[0007] Based on the above purpose, the present invention provides a ceramic thermal conductive composite material, which is composed of the following raw materials, in parts by weight: 50-85 parts of ceramic thermal conductive material, 2.5-20 parts of silver powder, 0.3-15 parts of nickel powder, 10-15 parts of dispersant, 0.1-5 parts of thickener, and 0.2-5 parts of organic acid.

[0008] Preferably, the ceramic thermal conductive material is a mixture of modified boron nitride, aluminum oxide and ceramic particles in a weight ratio of 35:10-35:5-15.

[0009] Preferably, the ceramic particles are one of aluminum nitride, silicon nitride, silicon carbide, and beryllium oxide;

[0010] Preferably, the modified boron nitride is obtained by first subjecting nano-boron nitride particles to epoxidation treatment to obtain epoxidized boron nitride particles; then, silver nanoparticles are compounded with carboxylated nanocellulose to form silver-loaded carboxylated nanocellulose; and then, under the action of p-toluenesulfonic acid, the silver-loaded carboxylated nanocellulose, the end-epoxy hyperbranched polyester and the epoxidized boron nitride particles are mixed and reacted to obtain the obtained product.

[0011] Preferably, the epoxidized boron nitride particles are obtained by treating nano boron nitride particles with a silane coupling agent KH-560.

[0012] Preferably, the weight ratio of the nano-boron nitride particles to the silane coupling agent KH-560 is 10-15:1-1.5.

[0013] Preferably, the silver-loaded carboxylated nanocellulose is obtained by mixing a silver nanoparticle suspension with a carboxylated nanocellulose suspension in a weight ratio of 10-20:80-90, and drying the mixture.

[0014] Preferably, the concentrations of the silver nanoparticle suspension and the carboxylated nanocellulose suspension are both 0.5 wt% to 1 wt%.

[0015] Preferably, the particle size of the silver nanoparticles is 50-100 nm.

[0016] Preferably, the length of the carboxylated nanocellulose is 1-3 μm.

[0017] Preferably, the weight ratio of the p-toluenesulfonic acid, the silver-loaded carboxylated nanocellulose, the epoxy-terminated hyperbranched polyester and the epoxidized boron nitride particles is 01.-0.2:3-5:0.1-0.3:10-15.

[0018] Preferably, the molecular weight of the epoxy-terminated hyperbranched polyester is 2500-3000.

[0019] Preferably, the particle sizes of the ceramic particles, modified boron nitride and aluminum oxide are all 50-1000 nm.

[0020] Preferably, the silver powder is one of flaky silver powder, spherical silver powder and dendritic silver powder, and has a particle size of 50-950 nm.

[0021] Preferably, the nickel powder has a particle size of 0.1-20 μm.

[0022] Preferably, the dispersant is one of n-butanol, isobutanol, ethylene glycol, glycerol, olive oil, cyclohexanone, and terpineol.

[0023] Preferably, the thickener is one or a mixture of organic bentonite DK2, polyamide wax H25, and fumed silica R974.

[0024] Preferably, the organic acid is glutaric acid, adipic acid, salicylic acid, or a mixture of several of them.

[0025] Furthermore, the present invention also provides a method for preparing a ceramic thermally conductive composite material, comprising the following steps:

[0026] The dispersant, thickener and organic acid are mixed and stirred, and then silver powder and nickel powder are added and stirred evenly. Finally, ceramic thermal conductive material is added and centrifuged to obtain a ceramic thermal conductive composite material.

[0027] Preferably, the stirring speed is 60-120 rpm, and the stirring time is 3-5 min.

[0028] Preferably, the dispersion speed is 1000-3000 rpm, and the time is 5-20 min.

[0029] Beneficial effects of the present invention:

[0030] This invention utilizes a composite system of epoxidized boron nitride and silver-loaded cellulose. Active functional groups on the boron nitride surface chemically bond with hyperbranched polymers, creating a three-dimensional thermal conductivity pathway from nanometer to micrometer scales. The cellulose support guides the silver particles into a directional structure that provides an auxiliary channel for electron conduction. This multi-scale collaborative design overcomes the limitations of a single thermal conductivity mechanism and the agglomeration phenomenon found in traditional composite materials, achieving both high thermal conductivity and high mechanical strength.

[0031] The invention utilizes a hyperbranched polymer to enhance the bond strength between the filler and the matrix through chemical bonding. The flexible motion of the molecular chains effectively mitigates thermal stress. The cellulose carrier's reticular structure provides a uniformly dispersed template for the silver particles, resolving the silver particle dispersion challenge. The chemically bonded interface significantly enhances stress transfer efficiency, while the intermolecular forces within the cellulose-silver composite system produce a significant toughening effect. This "rigid-flexible" design concept ensures the material possesses both high strength and high conductivity, meeting the stringent reliability requirements of electronic packaging materials.

[0032] The ceramic thermally conductive composite material of the present invention has good printing process performance, fast curing speed, excellent heat resistance and thermal conductivity, good technical and economic performance, low requirements on equipment complexity, easy operation, stable process, high production efficiency, and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0034] The properties of the raw materials used in the examples and comparative examples of the present invention are as follows: the particle size of the boron nitride is 50-1000 nm; the particle size of the silver powder is 50-950 nm; the particle size of the nickel powder is 0.1-20 μm; the particle size of the silver nanoparticles is 50-100 nm; and the length of the carboxylated nanocellulose is 1-3 μm.

[0035] Example 1: A ceramic thermally conductive composite material, the specific preparation steps are as follows:

[0036] (1) 10 g of nano-boron nitride particles were mixed with 20 g of deionized water according to a mass ratio, and 30 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1 g of KH-560 was added. The mixture was stirred at 40 ° C for 1 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0037] (2) silver nanoparticles and carboxylated nanocellulose were separately dispersed in deionized water to obtain a suspension with a concentration of 0.5 wt %. Subsequently, 10 g of the nanosilver solution and 90 g of the nanocellulose solution were mixed, ultrasonically mixed for 2 h, filtered, and vacuum dried at 80° C. for 24 h to obtain silver-loaded carboxylated nanocellulose.

[0038] (3) 10 g of epoxidized boron nitride particles were mixed with 100 ml of acetone, and after ultrasonic homogenization, 3 g of silver-loaded carboxylated nanocellulose, 0.1 g of epoxy-terminated hyperbranched polyester, and 0.1 g of p-toluenesulfonic acid were added. The mixture was stirred at 100 °C for 40 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0039] (4) 10 g of ethylene glycol, 0.1 g of organic bentonite, and 0.2 g of salicylic acid were mixed and stirred at 60 rpm. Then, 2.5 g of flaky silver powder and 0.3 g of nickel powder were added and stirred for 3 min. Finally, 50 g of ceramic thermal conductive material (35 g of modified boron nitride, 10 g of aluminum nitride, and 5 g of aluminum oxide) was added and dispersed at 1000 rpm for 5 min to obtain a ceramic thermal conductive composite material.

[0040] Example 2: A ceramic thermally conductive composite material, the specific preparation steps are as follows:

[0041] (1) 13 g of nano-boron nitride particles were mixed with 25 g of deionized water in a mass ratio, and 40 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1.3 g of KH-560 was added. The mixture was stirred at 40°C for 2 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0042] (2) silver nanoparticles and carboxylated nanocellulose were separately dispersed in deionized water to obtain a suspension with a concentration of 1 wt %, and then 15 g of the nanosilver solution and 85 g of the nanocellulose solution were mixed, ultrasonically mixed for 3 h, filtered, and vacuum dried at 80° C. for 24 h to obtain silver-loaded carboxylated nanocellulose;

[0043] (3) 13 g of epoxidized boron nitride particles were mixed with 150 ml of acetone, and after ultrasonic homogenization, 4 g of silver-loaded carboxylated nanocellulose, 0.2 g of epoxy-terminated hyperbranched polyester, and 0.15 g of p-toluenesulfonic acid were added. The mixture was stirred at 105° C. for 50 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0044] (4) 13 g of ethylene glycol, 3 g of organic bentonite, and 3 g of salicylic acid were mixed and stirred at 90 rpm. Then, 10 g of flaky silver powder and 10 g of nickel powder were added and stirred for 4 min. Finally, 70 g of ceramic thermal conductive material (35 g of modified boron nitride, 30 g of aluminum nitride, and 5 g of aluminum oxide) was added and dispersed at 2000 rpm for 10 min to obtain a ceramic thermal conductive composite material.

[0045] Example 3: A ceramic thermally conductive composite material, the specific preparation steps are as follows:

[0046] (1) 15 g of nano-boron nitride particles were mixed with 30 g of deionized water according to a mass ratio, and 50 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1.5 g of KH-560 was added. The mixture was stirred at 40 ° C for 2 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0047] (2) silver nanoparticles and carboxylated nanocellulose were separately dispersed in deionized water to obtain a suspension with a concentration of 1 wt %, and then 20 g of the nanosilver solution and 80 g of the nanocellulose solution were mixed, ultrasonically mixed for 3 h, filtered, and vacuum dried at 80° C. for 24 h to obtain silver-loaded carboxylated nanocellulose;

[0048] (3) 5 g of epoxidized boron nitride particles were mixed with 200 ml of acetone, and after ultrasonic homogenization, 5 g of silver-loaded carboxylated nanocellulose, 0.3 g of epoxy-terminated hyperbranched polyester, and 0.2 g of p-toluenesulfonic acid were added. The mixture was stirred at 110° C. for 60 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0049] (4) 15 g of ethylene glycol, 5 g of organic bentonite, and 5 g of salicylic acid were mixed and stirred at 120 rpm. Then, 20 g of flaky silver powder and 15 g of nickel powder were added and stirred for 5 min. Finally, 85 g of ceramic thermal conductive material (35 g of modified boron nitride, 35 g of aluminum nitride, and 15 g of aluminum oxide) was added and dispersed at 3000 rpm for 5-20 min to obtain a ceramic thermal conductive composite material.

[0050] Comparative Example 1: The difference from Example 2 is that the silver-loaded carboxylated nanocellulose is replaced with carboxylated nanocellulose and carboxylated silver nanoparticles. The remaining steps are the same as Example 2. The specific steps are as follows:

[0051] (1) 13 g of nano-boron nitride particles were mixed with 25 g of deionized water in a mass ratio, and 40 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1.3 g of KH-560 was added. The mixture was stirred at 40°C for 2 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0052] (2) 13 g of epoxidized boron nitride particles were mixed with 150 ml of acetone, and after ultrasonic homogenization, 0.6 g of carboxylated silver nanoparticles, 3.4 g of carboxylated nanocellulose, 0.2 g of epoxy-terminated hyperbranched polyester, and 0.15 g of p-toluenesulfonic acid were added. The mixture was stirred at 105° C. for 50 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0053] (3) 13 g of ethylene glycol, 3 g of organic bentonite, and 3 g of salicylic acid were mixed and stirred at 90 rpm. Then, 10 g of flaky silver powder and 10 g of nickel powder were added and stirred for 4 min. Finally, 70 g of ceramic thermal conductive material (35 g of modified boron nitride, 30 g of aluminum nitride, and 5 g of aluminum oxide) was added and dispersed at 2000 rpm for 10 min to obtain a ceramic thermal conductive composite material.

[0054] Comparative Example 2: The difference from Example 2 is that the silver-loaded carboxylated nanocellulose is replaced with carboxylated silver nanoparticles. The remaining steps are the same as Example 2. The specific steps are as follows:

[0055] (1) 13 g of nano-boron nitride particles were mixed with 25 g of deionized water in a mass ratio, and 40 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1.3 g of KH-560 was added. The mixture was stirred at 40°C for 2 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0056] (2) 13 g of epoxidized boron nitride particles were mixed with 150 ml of acetone, and after ultrasonication, 4 g of carboxylated silver nanoparticles, 0.2 g of epoxy-terminated hyperbranched polyester, and 0.15 g of p-toluenesulfonic acid were added. The mixture was stirred at 105° C. for 50 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0057] (3) 13 g of ethylene glycol, 3 g of organic bentonite, and 3 g of salicylic acid were mixed and stirred at 90 rpm. Then, 10 g of flaky silver powder and 10 g of nickel powder were added and stirred for 4 min. Finally, 70 g of ceramic thermal conductive material (35 g of modified boron nitride, 30 g of aluminum nitride, and 5 g of aluminum oxide) was added and dispersed at 2000 rpm for 10 min to obtain a ceramic thermal conductive composite material.

[0058] Comparative Example 3: The difference from Example 2 is that no epoxy-terminated hyperbranched polyester is added. The remaining steps are the same as Example 2. The specific steps are as follows:

[0059] (1) 13 g of nano-boron nitride particles were mixed with 25 g of deionized water in a mass ratio, and 40 ml of ethanol was added. The mixture was stirred for 20 min using a magnetic stirrer, and then 1.3 g of KH-560 was added. The mixture was stirred at 40°C for 2 h. After the reaction was completed, the mixture was filtered, and the resulting precipitate was washed and dried to obtain epoxide boron nitride particles.

[0060] (2) silver nanoparticles and carboxylated nanocellulose were separately dispersed in deionized water to obtain a suspension with a concentration of 1 wt %, and then 15 g of the nanosilver solution and 85 g of the nanocellulose solution were mixed, ultrasonically mixed for 3 h, filtered, and vacuum dried at 80° C. for 24 h to obtain silver-loaded carboxylated nanocellulose;

[0061] (3) 13 g of epoxidized boron nitride particles were mixed with 150 ml of acetone, and after ultrasonication, 4 g of silver-loaded carboxylated nanocellulose and 0.15 g of p-toluenesulfonic acid were added. The mixture was stirred at 105 °C for 50 min. After the reaction was completed, the mixture was filtered, washed, and dried to obtain modified boron nitride.

[0062] (4) 13 g of ethylene glycol, 3 g of organic bentonite, and 3 g of salicylic acid were mixed and stirred at 90 rpm. Then, 10 g of flaky silver powder and 10 g of nickel powder were added and stirred for 4 min. Finally, 70 g of ceramic thermal conductive material (35 g of modified boron nitride, 30 g of aluminum nitride, and 5 g of aluminum oxide) was added and dispersed at 2000 rpm for 10 min to obtain a ceramic thermal conductive composite material.

[0063] Comparative Example 4: The difference from Example 2 is that the boron nitride is not modified. The remaining steps are the same as Example 2. The specific steps are as follows:

[0064] Mix 13g of ethylene glycol, 3g of organic bentonite, and 3g of salicylic acid and stir at 90rpm. Then add 10g of flaky silver powder and 10g of nickel powder and continue stirring for 4min. Finally, add 70g of ceramic thermal conductive material (35g of boron nitride, 30g of aluminum nitride, and 5g of aluminum oxide) and disperse at 2000rpm for 10min to obtain a ceramic thermal conductive composite material.

[0065] Performance Testing

[0066] The obtained ceramic thermal conductive composite material was placed on a template, and then placed in an oven for curing at 300°C for 15 minutes, and naturally cooled to room temperature. The obtained sample was then tested;

[0067] Bending strength: The experiment was conducted according to GB / T 4740-2024 using a microcomputer-controlled electronic universal testing machine. The test results are shown in Table 1.

[0068] Thermal conductivity: The experiment was conducted according to GB / T 10297-2015. The test results are shown in Table 1.

[0069] Volume resistivity: The experiment was conducted according to GB / T 5594.5-1985. The test results are shown in Table 1.

[0070] Table 1 Performance test results

[0071]

[0072] As can be seen from the data in Examples 1-3 in Table 1, the ceramic thermally conductive composite material prepared by the present invention exhibits excellent comprehensive performance. Its technical advantages are mainly reflected in the unique material system formed by the synergistic effect of three aspects. First, through the composite design of epoxidized boron nitride and silver-loaded cellulose, a multi-scale thermal conductive network is constructed within the material. The high thermal conductivity of boron nitride complements the electronic thermal conductivity mechanism of silver particles, enabling efficient heat transfer. Second, the introduction of hyperbranched polyester not only enhances the interfacial bonding through its three-dimensional topological structure, but also forms a stable chemical bond between the filler and the matrix. This strong interfacial interaction significantly improves the mechanical properties of the material. Finally, carboxylated nanocellulose acts as a carrier for silver particles, achieving uniform dispersion and directional arrangement of the silver particles through intermolecular forces. This ordered structure ensures the continuity of the conductive path.

[0073] From the performance comparison data of Example 2 and Comparative Example 1 in Table 1, it can be observed that there are significant differences in mechanical properties, thermal conductivity and electrical behavior between the two. This difference is mainly due to the essential difference in the material system construction strategy. The silver-loaded carboxylated nanocellulose used in Example 2 is used as a silver particle carrier. A stable composite structure is formed by the coordination of the hydroxyl groups of cellulose with the silver surface. This design not only retains the high thermal conductivity of the silver particles, but also prevents particle agglomeration through the steric hindrance effect of cellulose. In Comparative Example 1, carboxylated silver particles are directly mixed with carboxylated cellulose. Due to the electrostatic repulsion between the carboxyl groups, the silver particles are unevenly distributed, forming local enrichment areas and depletion areas inside the material. This microscopic heterogeneity directly affects the transfer efficiency of heat flow and stress. In addition, the silver conductive path formed by the cellulose guidance in Example 2 has better continuity and orientation, and the electron transmission path is smoother. In Comparative Example 1, the conductive network formed by the randomly distributed carboxylated silver particles has more breakpoints, which increases the probability of carrier scattering.

[0074] From the performance comparison data of Example 2 and Comparative Example 2 in Table 1, it can be observed that there are systematic differences between the two in terms of mechanical properties, thermal conductivity, and electrical behavior. First, Example 2 uses carboxylated nanocellulose as a silver particle carrier, achieving uniform distribution of silver particles through ultrasound-assisted physical adsorption. While Comparative Example 2 directly uses carboxylated silver nanoparticles, although the carboxyl modification improves the hydrophilicity of the particles, the electrostatic repulsion between the carboxyl groups may cause the silver particles to be discretely distributed in the matrix. Second, the carboxyl groups on the cellulose molecular chains in Example 2 may form coordination bonds with the surface of the silver particles. This interaction not only maintains the nanoscale dispersion of the silver particles but also provides spatial support for the silver particles through the three-dimensional network structure of cellulose. In contrast, the carboxylated silver particles in Comparative Example 2 are more prone to agglomeration during subsequent processing due to the lack of such carrier support. At the same time, the cellulose carrier in Example 2 may guide the silver particles to form a more continuous thermal conductivity pathway, which is conducive to the coordinated conduction of phonons and electrons. In contrast, the thermal conductivity network formed by the discretely distributed silver particles in Comparative Example 2 has more interfacial barriers. Finally, the cellulose network of Example 2 may enhance the interfacial bonding through hydrogen bonding with the matrix, while the interaction between the carboxylated silver particles and the matrix in Comparative Example 2 is relatively weak.

[0075] From the performance comparison data of Example 2 and Comparative Example 3 in Table 1, it can be observed that the epoxy-terminated hyperbranched polyester in Example 2 may undergo a ring-opening reaction with the surface of epoxidized boron nitride through the epoxy groups in its molecular structure, and at the same time, its carboxyl groups form ester bonds with the hydroxyl groups of the silver-loaded cellulose. This bifunctional chemical bridging effect establishes a stable chemical bonding network between the filler and the matrix; while in Comparative Example 3, due to the lack of this component, the interface bonding mainly relies on physical adsorption and mechanical interlocking; at the same time, the three-dimensional topological structure of the hyperbranched polyester may provide a spatial positioning template for the silver particles, guiding them to form a more uniform distribution state, and the flexibility of its molecular chain helps to relieve thermal stress; in contrast, the distribution of silver particles in Comparative Example 3 may present a more random aggregation state; and the introduction of the hyperbranched polyester may effectively prevent the expansion of microcracks through the steric hindrance effect generated by its branched structure, while the stretching characteristics of its molecular chain can absorb part of the impact energy; while in Comparative Example 3, due to the lack of this toughening mechanism, the material is more likely to produce stress concentration when subjected to stress.

[0076] From the performance comparison data of Example 2 and Comparative Example 4 in Table 1, it can be observed that the surface epoxidation treatment of the boron nitride particles using the KH-560 silane coupling agent in Example 2 may introduce active epoxy groups on the filler surface through a hydrolysis condensation reaction. These functional groups can undergo ring-opening polymerization with the epoxy-terminated hyperbranched polyester to form a chemically bonded interfacial transition layer, thereby improving the wettability and dispersibility between the base materials and avoiding agglomeration.

[0077] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A ceramic thermally conductive composite material, characterized in that: The composition is composed of the following raw materials in parts by weight: 50-85 parts of ceramic thermal conductive material, 2.5-20 parts of silver powder, 0.3-15 parts of nickel powder, 10-15 parts of dispersant, 0.1-5 parts of thickener, and 0.2-5 parts of organic acid; The ceramic thermal conductive material is a mixture of modified boron nitride, aluminum oxide and ceramic particles in a weight ratio of 35:10-35:5-15; The modified boron nitride is prepared by first subjecting nano-boron nitride particles to epoxidation to obtain epoxidized boron nitride particles; subsequently, silver nanoparticles are compounded with carboxylated nanocellulose to form silver-loaded carboxylated nanocellulose; and then, under the action of p-toluenesulfonic acid, the silver-loaded carboxylated nanocellulose, epoxy-terminated hyperbranched polyester and epoxidized boron nitride particles are mixed and reacted to obtain the obtained product.

2. The thermally conductive ceramic composite material according to claim 1, wherein: The ceramic particles are one of aluminum nitride, silicon nitride, silicon carbide, and beryllium oxide. The particle sizes of the ceramic particles, modified boron nitride, and aluminum oxide are all 50-1000 nm.

3. The thermally conductive ceramic composite material according to claim 1, wherein: The silver powder is one of flaky silver powder, spherical silver powder and dendritic silver powder, and has a particle size of 50-950 nm; the nickel powder has a particle size of 0.1-20 μm.

4. The thermally conductive ceramic composite material according to claim 1, wherein: The dispersant is one of n-butanol, isobutanol, ethylene glycol, glycerin, olive oil, cyclohexanone, and terpineol; the thickener is one of organic bentonite DK2, polyamide wax H25, and fumed silica R974, or a mixture of several of them; and the organic acid is one of glutaric acid, adipic acid, and salicylic acid, or a mixture of several of them.

5. The ceramic thermally conductive composite material according to claim 1, characterized in that: The epoxidized boron nitride particles are obtained by treating nano boron nitride particles with a silane coupling agent KH-560. The weight ratio of the nano boron nitride particles to the silane coupling agent KH-560 is 10-15:1-1.

5.

6. The thermally conductive ceramic composite material according to claim 1, characterized in that: The weight ratio of the silver nanoparticles to the carboxylated nanocellulose in the silver-loaded carboxylated nanocellulose is 10-20:80-90.

7. The thermally conductive ceramic composite material according to claim 6, characterized in that: The particle size of the silver nanoparticles is 50-100 nm, and the length of the carboxylated nanocellulose is 1-3 μm.

8. The thermally conductive ceramic composite material according to claim 1, wherein: The weight ratio of the p-toluenesulfonic acid, the silver-loaded carboxylated nanocellulose, the epoxy-terminated hyperbranched polyester and the epoxidized boron nitride particles is 0.1-0.2:3-5:0.1-0.3:10-15.

9. A method for preparing the ceramic thermally conductive composite material according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: a dispersant, a thickener, and an organic acid are mixed and stirred, then silver powder and nickel powder are added and stirred evenly, and finally a ceramic thermal conductive material is added and centrifuged to obtain a ceramic thermal conductive composite material.

10. The preparation method according to claim 9, characterized in that The stirring speed is 60-120 rpm, and the time is 3-5 min; the dispersion speed is 1000-3000 rpm, and the time is 5-20 min.

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