High-heat-dissipation composite functional material and preparation method and application thereof

Abstract

The application belongs to the field of electronic and electrical device packaging materials, and provides a high-heat-dissipation composite functional material and a preparation method and application thereof. Bisphenol A diglycidyl ether, diphenyl diglycidyl ether, 1,4-butanediol diglycidyl ether, 3-glycidyl ether oxypropyl trimethoxysilane, polyimide shell-coated hexagonal boron nitride core-shell filler, spherical alumina, methyl hexahydrophthalic anhydride and 2-ethyl-4-methyl imidazole are cooperatively designed, and the material is obtained through mixing, degassing and segmented curing. The obtained material has relatively high apparent thermal conductivity, volume resistivity, bending strength and breakdown strength, the uncured composition has suitable viscosity, the problems of poor fluidity under high filling conditions, limited processing window and difficult to balance high thermal conductivity and high electrical insulation are solved, and the material has good electronic and electrical device packaging application value.

Description

Technical Field

[0001] This invention relates to the field of composite materials for electronic and electrical device packaging, specifically to a high heat dissipation composite functional material and its preparation method and application. Background Technology

[0002] As electronic and electrical devices continue to evolve towards higher integration, higher power density, and longer lifespan, encapsulation materials are no longer simply insulating and adhesive media. They must simultaneously undertake multiple tasks, including heat conduction, structural support, interface protection, and long-term service stability. For epoxy-cured composite materials, it is crucial to maintain acceptable flowability, dispersibility, and molding adaptability after introducing a large amount of inorganic fillers to meet the requirements of processes such as potting, casting, and molding. Simultaneously, a dense and stable internal structure must be formed after curing to avoid weakening electrical insulation and mechanical reliability due to interface mismatch, residual pores, and localized stress concentration. Especially under high filler conditions, the continuity of the filler network, the interfacial bonding state, and defect control during the curing process often interact, and improvement in any single indicator may lead to fluctuations in another performance dimension. Therefore, establishing a synergistic balance between thermal conductivity, insulation, processing window, and structural stability has become a key issue in the research and development of composite materials for electronic and electrical device encapsulation.

[0003] Currently, existing technologies for epoxy-based high-heat-dissipation composite materials mainly focus on improvements through filler gradation, surface modification, or external field control. For example, Chinese patent CN115232444A discloses a high thermal conductivity spherical boron nitride composite epoxy resin and its preparation method. This scheme improves slurry viscosity and promotes the construction of a thermally conductive network by combining spherical boron nitride and spherical alumina. However, it can be seen from the disclosed scheme that its technical focus is mainly on the synergy of filler morphology and gradation. There is still room for improvement in achieving interfacial bonding stability, structural density, and the simultaneous balance of high thermal conductivity and high electrical insulation under high-filling conditions. Similarly, Chinese patent CN111574909B discloses a method for preparing a breakdown-resistant epoxy resin-boron nitride composite material. This scheme emphasizes improving breakdown behavior through surface modification and magnetic field-assisted curing. However, it can be seen from the disclosed scheme that further optimization is needed in balancing low-viscosity processing, efficient thermal transfer, volume resistivity, and comprehensive mechanical properties. Therefore, how to coordinate the construction of the filler network, the suppression of interfacial polarization, and the overall insulation performance without sacrificing the processing window remains an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a high heat dissipation composite functional material, its preparation method and application, to solve the problems that current high-filler composite materials for electronic and electrical packaging are prone to increased viscosity, poor flowability, limited processing window, and difficulty in balancing flexural strength, structural density, breakdown strength and volume resistivity when constructing efficient thermally conductive and electrically insulating networks.

[0005] This invention utilizes biphenyl diglycidyl ether, bisphenol A diglycidyl ether, and 1,4-butanediol diglycidyl ether to synergistically regulate flowability and cross-linking structure. It also employs a polyimide shell to coat a hexagonal boron nitride core-shell filler and spherical alumina to synergistically construct a thermally conductive pathway. Furthermore, it combines 3-glycidyl etheroxypropyltrimethoxysilane, vacuum degassing, and segmented curing to enhance interfacial bonding and density, thereby achieving a balance between thermal conductivity, insulation, mechanical properties, and processability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A high heat dissipation composite functional material is obtained by curing the following raw materials, which, by mass parts, include: 10-20 parts of bisphenol A diglycidyl ether; 5-15 parts of biphenyl diglycidyl ether; 2-8 parts of 1,4-butanediol diglycidyl ether; 1-4 parts of 3-glycidyl etheroxypropyltrimethoxysilane; 40-70 parts of polyimide shell-coated hexagonal boron nitride core-shell filler; 10-30 parts of spherical alumina; 10-25 parts of methylhexahydrophthalic anhydride; and 0.2-1.5 parts of 2-ethyl-4-methylimidazole. The mass ratio of the polyimide-shell-coated hexagonal boron nitride core-shell filler to the spherical alumina is 2:1-5:1, and the total addition amount is 55-85 parts by mass; the ratio of the total equivalent of acid anhydride groups to the total equivalent of epoxy groups is 0.85-1.05:1; wherein the median particle size D50 of the polyimide-shell-coated hexagonal boron nitride core-shell filler is 5-25 μm, the shell thickness is 5-30 nm, and the shell content is 1-8 wt%. The resulting high heat dissipation composite material has an apparent thermal conductivity of 2.5-6.0 W / m·K and a volume resistivity of 1×10⁻⁶. 12 -1×10 15 Ω·cm.

[0007] Furthermore, the biphenyl diglycidyl ether is prepared by the following steps: A1. Mix 100-150 parts by weight of 4,4'-dihydroxybiphenyl with 400-800 parts by weight of epichlorohydrin, and stir at 50-70°C for 0.5-2 hours; A2. Add 30-50wt% sodium hydroxide aqueous solution dropwise at 60-80℃, and control the molar ratio of sodium hydroxide to phenolic hydroxyl groups to be 1.8-2.4:1, and continue the reaction for 2-6 hours; A3. Filter to remove salt, and remove excess epichlorohydrin under reduced pressure at 50-80℃ under 0.005-0.020MPa; A4. When the epoxy equivalent of the product is 170-220 g / eq and the hydrolyzable chlorine content is ≤0.60 wt%, the biphenyl diglycidyl ether is obtained.

[0008] Furthermore, the aminosilanized hexagonal boron nitride used to prepare the polyimide shell-coated hexagonal boron nitride core-shell filler is prepared through the following steps: B1. Activate hexagonal boron nitride in air at 850-950℃ for 0.5-2h; B2. Add 2-10 parts by weight of 3-aminopropyltriethoxysilane to a mixture consisting of 300-800 parts by weight of ethanol, 20-100 parts by weight of deionized water and 0.5-3 parts by weight of glacial acetic acid, hydrolyze at 20-35℃ for 20-60 min, and adjust the pH to 4.5-5.5; B3. Add 100 parts by mass of activated hexagonal boron nitride obtained in step B1 to the hydrolysate obtained in step B2, and react at 60-80℃ for 2-6 hours; B4. After filtration and washing with ethanol and deionized water in sequence, dry at 80-120℃ for 4-10h to obtain aminosilanized hexagonal boron nitride with a silicon content of 0.3-2.0wt%.

[0009] Furthermore, the polyimide shell-coated hexagonal boron nitride core-shell filler is prepared through the following steps: C1. Dissolve 3-12 parts by weight of 4,4'-diaminodiphenyl ether in 300-900 parts by weight of 1-methyl-2-pyrrolidone and stir at 10-25°C for 0.5-2 hours; C2. After adding 100 parts by weight of the aminosilanized hexagonal boron nitride and dispersing for 0.5-2 hours, 3-12 parts by weight of pyromellitic anhydride are added in batches, controlling the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether to be 0.95-1.05:1, and reacting at 10-30°C for 4-12 hours to obtain the polyamic acid coated intermediate; C3. The polyamic acid-coated intermediate is filtered, washed and dried, and then thermally imidized at 180-260°C for 1-4 hours under an inert atmosphere; C4. Obtain the polyimide shell-coated hexagonal boron nitride core-shell filler with a shell content of 1-8 wt% and a shell thickness of 5-30 nm.

[0010] Furthermore, the median particle size D50 of the spherical alumina is 3-20 μm; the mass ratio of the polyimide shell-coated hexagonal boron nitride core-shell filler to the spherical alumina is 2:1-5:1; the ratio of the total equivalent of acid anhydride groups to the total equivalent of epoxy groups is 0.85-1.05:1; and the uncured composition formed by mixing the raw materials described above withstands a shear rate of 10 s at 25°C. -1 The apparent viscosity under the given conditions is 5-40 Pa·s; the flexural strength of the resulting high heat dissipation composite material is 70-130 MPa, and the breakdown strength is 15-30 kV / mm.

[0011] As a concept of this invention, the design of using a polyimide shell-coated hexagonal boron nitride core-shell filler combined with spherical alumina is mainly used to enhance the overall performance of high heat dissipation composite materials, including apparent thermal conductivity, volume resistivity, breakdown strength, and flexural strength. The polyimide shell-coated hexagonal boron nitride core-shell filler can improve the interfacial compatibility between hexagonal boron nitride and the curing system while maintaining the thermal conductivity characteristics of hexagonal boron nitride, reducing the sensitivity to interfacial defects caused by direct contact with inorganic fillers; the spherical alumina is beneficial for adjusting the packing morphology, filling the voids between particles, and assisting in constructing a more continuous heat conduction path. The synergistic formulation of biphenyl diglycidyl ether, bisphenol A diglycidyl ether, and 1,4-butanediol diglycidyl ether balances the structural strength after crosslinking with the processing fluidity of the uncured composition. Furthermore, the curing pathway of 3-glycidyl etheroxypropyltrimethoxysilane and methylhexahydrophthalic anhydride can further enhance interfacial bonding, structural density, and uniform electric field distribution, resulting in a better balance between apparent thermal conductivity, volume resistivity, breakdown strength, and flexural strength.

[0012] This invention also discloses a method for preparing a high heat dissipation composite functional material, comprising the following steps: S1. Provide the prepared biphenyl diglycidyl ether; S2. Provides the prepared aminosilanized hexagonal boron nitride; S3. Provide a polyimide shell-coated hexagonal boron nitride core-shell filler, which is prepared using aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. 10-20 parts by weight of bisphenol A diglycidyl ether, 5-15 parts by weight of biphenyl diglycidyl ether provided in step S1, 2-8 parts by weight of 1,4-butanediol diglycidyl ether, 1-4 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 40-70 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler provided in step S3, 10-30 parts by weight of spherical alumina, 10-25 parts by weight of methylhexahydrophthalic anhydride, and 0.2-1.5 parts by weight of 2-ethyl-4-methylimidazolium are premixed and degassed using mechanical stirring or planetary stirring. The total treatment time is 20-55 min. First, the mixture is premixed at 1000-2000 r / min for 15-25 min, and then degassed under a vacuum of -0.098 MPa to -0.08 MPa for 5-30 min to obtain an uncured composition. S5. The uncured composition obtained in step S4 is molded, cast or potted, and then cured in stages at 80-100℃ for 1-3h, 120-150℃ for 1-3h and 160-180℃ for 1-3h to obtain a high heat dissipation composite functional material.

[0013] Furthermore, before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 are dried at 100-140℃ for 2-8 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is ≤0.10wt%.

[0014] Further, in step S4, the mass ratio of the polyimide shell-coated hexagonal boron nitride core-shell filler and the spherical alumina provided in step S3 is 2:1-5:1, and the total amount of the polyimide shell-coated hexagonal boron nitride core-shell filler and the spherical alumina provided in step S3 is 55-85 parts by mass; the mixing method in step S4 is to first premix at 1000-2000 r / min for 15-25 min, and then perform vacuum degassing for 5-30 min; the molding method in step S5 is molding, casting, or potting.

[0015] Furthermore, the segmented curing regime in step S5 is as follows: 1.5-2.5h at 85-95℃, 1.5-2.5h at 130-140℃, and 1.5-2.5h at 165-175℃; the porosity of the resulting high heat dissipation composite functional material is ≤2.0 vol%, and the thickness is 0.1-5.0 mm.

[0016] This invention also discloses the application of a high heat dissipation composite functional material in the packaging of electronic and electrical devices.

[0017] Furthermore, the silicon content is calculated based on the total mass of aminosilanized hexagonal boron nitride, and the shell content is calculated based on the total mass of polyimide shell-coated hexagonal boron nitride core-shell filler.

[0018] Furthermore, the silicon content is determined by elemental analysis or inductively coupled plasma atomic emission spectrometry, and the shell content is determined by thermogravimetric analysis.

[0019] Furthermore, the median particle size D50 was determined by laser particle size analysis, and the shell thickness was determined by electron microscopy.

[0020] Furthermore, the epoxy equivalent is determined by titration, and the hydrolyzable chlorine content is determined by chemical analysis.

[0021] Furthermore, the apparent thermal conductivity was measured at 25°C, and the volume resistivity was measured under normal temperature and humidity conditions.

[0022] Furthermore, the viscosity is the apparent viscosity of the uncured composition measured at a predetermined shear rate at 25°C.

[0023] Furthermore, the bending strength is measured by a three-point bending test, the breakdown strength is measured by a dielectric breakdown test, and the porosity is determined by density method or microscopic image analysis method.

[0024] Furthermore, the water content is determined by Karl Fischer method or halogen water method.

[0025] Furthermore, in step A2, the amount of 30-50wt% sodium hydroxide aqueous solution used is 200-600 parts by mass. The dropping is a continuous dropping with a controlled dropping rate of 2-10 mL / min. After the dropping is completed, the reaction continues at 60-80℃ for 2-6 h. In step A3, 0.005-0.020 MPa is an absolute pressure.

[0026] Furthermore, in step B2, the 3-aminopropyltriethoxysilane, ethanol, deionized water, and glacial acetic acid are all based on 100 parts by mass of activated hexagonal boron nitride obtained in step B1. The pH in step B2 is adjusted to 4.5-5.5 by adding glacial acetic acid or alkaline solution. The reaction in step B3 is carried out under mechanical stirring. The washing in step B4 includes sequential washing with ethanol and washing with deionized water.

[0027] Furthermore, in step C2, the dispersion is carried out using one of mechanical stirring, ultrasonic dispersion, or high-speed shear dispersion. Pyromellitic anhydride is added in 2-5 batches, with an interval of 10-30 min between adjacent batches. In step C3, the thermal imidization is carried out under a nitrogen or argon atmosphere using a programmed temperature rise method, with a heating rate of 2-10 °C / min and an inert gas flow rate of 50-200 mL / min.

[0028] Furthermore, the washing in step C3 is performed sequentially with 1-methyl-2-pyrrolidone and ethanol, followed by vacuum drying at 80-120°C for 2-8 hours.

[0029] Furthermore, the mixing in step S4 is carried out by mechanical stirring or planetary stirring, and the vacuum degree in step S4 is the gauge pressure relative to standard atmospheric pressure.

[0030] As another aspect of this invention, the preparation method employing a combination of degassing and segmented curing is primarily used to enhance the structural density, processing stability, and compatibility with electronic and electrical device packaging of high-heat-dissipation composite functional materials. By first providing pre-prepared biphenyl diglycidyl ether, aminosilanized hexagonal boron nitride, and polyimide shells to coat hexagonal boron nitride core-shell fillers, the key components can be made more stable and their composition more controllable. During the mixing stage, the combination of premixing and vacuum degassing improves the dispersion uniformity of the high-filling system and reduces residual bubbles and pores. In the curing stage, the segmented curing regime from low to high helps balance flow molding, gradual crosslinking, and stress release, avoiding localized defect concentration, thereby improving flexural strength, breakdown strength, volume resistivity, and structural density, and making the resulting material more suitable for electronic and electrical device packaging applications.

[0031] The key function of the polyimide shell-coated hexagonal boron nitride core-shell filler is to provide a highly efficient thermally conductive framework and improve interfacial compatibility with the curing system, reducing interfacial mismatch and defect sensitivity caused by exposed inorganic surfaces. The key function of the spherical alumina is to supplement particle packing, fill particle gaps, and facilitate more continuous heat transfer between fillers. The former focuses on improving apparent thermal conductivity and interfacial stability, while the latter focuses on regulating viscosity, molding flowability, and structural density. The combination of the two can create a synergy between thermal conductivity pathway construction, uniform electric field distribution, and defect suppression, enabling the material to achieve more stable flexural strength and processing adaptability while maintaining high volume resistivity and breakdown strength. Of course, this synergy is still influenced by the filler ratio, shell quality, and curing process, requiring further optimization based on specific processes.

[0032] Beneficial technical effects 1. By synergistically combining bisphenol A diglycidyl ether, biphenyl diglycidyl ether and 1,4-butanediol diglycidyl ether, and adjusting interfacial compatibility with 3-glycidyl etheroxypropyltrimethoxysilane, the high-filling system can maintain good flow and molding adaptability while maintaining high filler loading, which is beneficial to broaden the processing window and reduce process fluctuations.

[0033] 2. By constructing a multi-scale heat conduction path through a polyimide shell-coated hexagonal boron nitride core-shell filler and a spherical alumina compound, it is beneficial to improve the continuous heat transfer efficiency between the fillers and improve the particle packing and void filling effect, thereby achieving a better balance between apparent thermal conductivity and structural compactness.

[0034] 3. The polyimide shell, aminosilanized interface, and methylhexahydrophthalic anhydride curing system work together to enhance the bonding stability between the inorganic filler and the organic matrix, reduce interfacial polarization, local electric field concentration, and defect sensitivity, so that the resulting material can maintain thermal conductivity while having high volume resistivity and breakdown strength.

[0035] 4. By combining premixing, vacuum degassing, and segmented curing processes, residual air bubbles and uneven curing shrinkage in the uncured composition can be reduced, thereby improving the bending strength and overall reliability of the cured material. This makes it more suitable for applications such as electronic and electrical device packaging that have high requirements for heat dissipation, insulation, and mechanical stability. Attached Figure Description

[0036] Figure 1 The N1s high-resolution superimposed spectra of XPS for samples from Example 1, Comparative Example 3, and Comparative Example 4 are shown.

[0037] Figure 2 The images show the Si2p high-resolution superimposed spectra of XPS from samples of Example 1, Comparative Example 3, and Comparative Example 4.

[0038] Figure 3 The images show the O1s high-resolution superimposed spectra of XPS from samples of Example 1, Comparative Example 3, and Comparative Example 4.

[0039] Figure 4 This is a comparison diagram of the core energy level peak areas of XPS samples from Example 1, Comparative Example 3, and Comparative Example 4.

[0040] Figure 5 Thermogravimetric analysis curves of the samples from Example 1 and Comparative Example 3 are shown.

[0041] Figure 6 Thermogravimetric derivative analysis curves of the samples from Example 1 and Comparative Example 3 are shown.

[0042] Figure 7 The image shows the laser particle size differential volume distribution curves for samples from Example 1 and Comparative Example 5.

[0043] Figure 8 The cumulative volume distribution curves of laser particle size for the samples of Example 1 and Comparative Example 5 are shown.

[0044] Figure 9 The image shows a double logarithmic curve of viscosity-shear rate for samples from Example 1, Comparative Example 2, and Comparative Example 5.

[0045] Figure 10 Box plots of porosity for samples from Example 1, Comparative Example 7, and Comparative Example 8.

[0046] Figure 11 The image shows the Weibull linearized fit plot of the breakdown strength of the samples from Example 1, Comparative Example 7, and Comparative Example 8.

[0047] Figure 12 This is a comparison chart of the characteristic breakdown strength of samples from Example 1, Comparative Example 7, and Comparative Example 8.

[0048] Figure 13 This is a macroscopic optical photograph of the high heat dissipation composite material of Example 1.

[0049] Figure 14 This is a scanning electron microscope image of the high heat dissipation composite material of Example 1.

[0050] Figure 15 This is a transmission electron microscope image of the polyimide shell-coated hexagonal boron nitride core-shell filler of Example 1. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0052] Example 1

[0053] This embodiment provides a high heat dissipation composite functional material, which is obtained by curing the following raw materials. The raw materials include, by weight, 11 parts of bisphenol A diglycidyl ether, 6 parts of biphenyl diglycidyl ether, 3 parts of 1,4-butanediol diglycidyl ether, 1.5 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 48 parts of polyimide shell-coated hexagonal boron nitride core-shell filler, 18 parts of spherical alumina, 18 parts of methylhexahydrophthalic anhydride, and 0.8 parts of 2-ethyl-4-methylimidazole.

[0054] In this embodiment, the mass ratio of polyimide-coated hexagonal boron nitride core-shell filler to spherical alumina is 2.67:1, and the total amount added is 66 parts by mass. In this embodiment, the ratio of total equivalent of anhydride groups to total equivalent of epoxy groups is 0.90:1. The median particle size D50 of the polyimide-coated hexagonal boron nitride core-shell filler in this embodiment is 14 μm, the shell thickness is 15 nm, and the shell content is 4.2 wt%. The resulting high-heat-dissipation composite material has an apparent thermal conductivity of 3.8 W / m·K and a volume resistivity of 5 × 10¹³ Ω·cm.

[0055] The biphenyl diglycidyl ether of this embodiment was prepared by the following steps: A1. 125 parts by mass of 4,4'-dihydroxybiphenyl and 600 parts by mass of epichlorohydrin were mixed and stirred at 60°C for 1.2 h; A2. 282 parts by mass of 40 wt% sodium hydroxide aqueous solution were added dropwise at 70°C, and the molar ratio of sodium hydroxide to phenolic hydroxyl groups was controlled at 2.1:1, with a dropping rate of 5 mL / min. After the addition was completed, the reaction was continued for 4 h; A3. The product was filtered to remove salt, and excess epichlorohydrin was removed under reduced pressure at 65°C at 0.010 MPa; A4. When the epoxy equivalent of the product was 195 g / eq and the hydrolyzable chlorine content was 0.42 wt%, the biphenyl diglycidyl ether of this embodiment was obtained.

[0056] The aminosilane-coated hexagonal boron nitride used in this embodiment for preparing the polyimide shell-coated hexagonal boron nitride core-shell filler was prepared through the following steps: B1. Hexagonal boron nitride was activated in air at 900°C for 1.2 h; B2. 6 parts by mass of 3-aminopropyltriethoxysilane were added to a mixture of 550 parts by mass of ethanol, 60 parts by mass of deionized water, and 1.5 parts by mass of glacial acetic acid, and hydrolyzed at 28°C for 40 min, and the pH was adjusted to 5.0 by adding glacial acetic acid; B3. 100 parts by mass of the activated hexagonal boron nitride obtained in step B1 were added to the hydrolysate obtained in step B2, and the mixture was reacted at 70°C under mechanical stirring for 4 h; B4. After filtration, the mixture was washed sequentially with ethanol and deionized water, and dried at 100°C for 7 h to obtain aminosilane-coated hexagonal boron nitride with a silicon content of 1.1 wt%.

[0057] The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment is prepared by the following steps: C1. Dissolve 7.5 parts by weight of 4,4'-diaminodiphenyl ether in 600 parts by weight of 1-methyl-2-pyrrolidone and stir at 18°C ​​for 1.2 h; C2. Add 100 parts by weight of the aminosilanized hexagonal boron nitride prepared above and disperse by mechanical stirring for 1.2 h, then add 8.2 parts by weight of pyromellitic anhydride. The product was added in three batches by weight, with the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether controlled at 1.00:1. The interval between two adjacent batches was 20 min. The reaction was carried out at 20 °C for 8 h to obtain a polyamic acid-coated intermediate. C3. The polyamic acid-coated intermediate of this embodiment was filtered, washed sequentially with 1-methyl-2-pyrrolidone and ethanol, and vacuum dried at 100 °C for 5 h. Then, it was thermally imidized at 220 °C for 2.5 h under a nitrogen atmosphere using a programmed temperature rise method with a heating rate of 6 °C / min and a nitrogen flow rate of 120 mL / min. C4. The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment with a shell content of 4.2 wt% and a shell thickness of 15 nm was obtained.

[0058] The median particle size D50 of the spherical alumina in this embodiment is 11 μm. The viscosity of the uncured composition formed by mixing the raw materials in this embodiment is 18 Pa·s at 25°C. The resulting high heat dissipation composite material has a flexural strength of 95 MPa and a breakdown strength of 22 kV / mm.

[0059] The preparation method of the high heat dissipation composite functional material in this embodiment includes the following steps: S1. Providing the previously prepared biphenyl diglycidyl ether; S2. Providing the previously prepared aminosilanized hexagonal boron nitride; S3. Providing the previously prepared polyimide shell-coated hexagonal boron nitride core-shell filler, which is prepared using the aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. Before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, drying the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 at 120°C for 5 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is 0.06 wt%; The mass of 11 bisphenol A diglycidyl ether is... The following components were prepared by mixing: 6 parts by weight of biphenyl diglycidyl ether provided in step S1, 3 parts by weight of 1,4-butanediol diglycidyl ether, 1.5 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 48 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler provided in step S3, 18 parts by weight of spherical alumina, 18 parts by weight of methylhexahydrophthalic anhydride, and 0.8 parts by weight of 2-ethyl-4-methylimidazolium. The mixture was premixed at 1500 r / min for 20 min using planetary stirring, followed by degassing at a vacuum of -0.090 MPa for 15 min to obtain an uncured composition. S5. The uncured composition obtained in step S4 was molded and then cured in stages at 90℃ for 2 h, 135℃ for 2 h, and 170℃ for 2 h to obtain a high-heat-dissipation composite material with a porosity of 1.2 vol% and a thickness of 2.0 mm.

[0060] Example 1 shows a core-shell filler with moderate shell content and thickness, and a median particle size of 14 μm. The resulting material has an apparent thermal conductivity of 3.8 W / m·K and a volume resistivity of 5 × 10¹³ Ω·cm, exhibiting both good thermal conductivity and electrical insulation properties, as well as moderate flexural strength and breakdown strength. This process is stable and reliable, suitable for packaging electronic and electrical devices with moderate requirements for thermal conductivity and mechanical strength, and particularly suitable for conventional heat dissipation packaging applications of power devices and LED modules.

[0061] Example 2

[0062] This embodiment provides a high heat dissipation composite functional material, which is obtained by curing the following raw materials. The raw materials include, by weight, 12 parts of bisphenol A diglycidyl ether, 9 parts of biphenyl diglycidyl ether, 4.5 parts of 1,4-butanediol diglycidyl ether, 2.5 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 60 parts of polyimide shell-coated hexagonal boron nitride core-shell filler, 20 parts of spherical alumina, 24 parts of methylhexahydrophthalic anhydride, and 1.2 parts of 2-ethyl-4-methylimidazole.

[0063] In this embodiment, the mass ratio of polyimide-coated hexagonal boron nitride core-shell filler to spherical alumina is 3:1, and the total amount added is 80 parts by mass. In this embodiment, the ratio of total equivalent of anhydride groups to total equivalent of epoxy groups is 0.89:1. The median particle size D50 of the polyimide-coated hexagonal boron nitride core-shell filler in this embodiment is 20 μm, the shell thickness is 22 nm, and the shell content is 6.5 wt%. The resulting high-heat-dissipation composite material has an apparent thermal conductivity of 5.2 W / m·K and a volume resistivity of 3 × 10¹³ Ω·cm.

[0064] The biphenyl diglycidyl ether of this embodiment was prepared by the following steps: A1. 140 parts by weight of 4,4'-dihydroxybiphenyl and 720 parts by weight of epichlorohydrin were mixed and stirred at 65°C for 1.5 h; A2. 294 parts by weight of 45 wt% sodium hydroxide aqueous solution were added dropwise at 75°C, and the molar ratio of sodium hydroxide to phenolic hydroxyl groups was controlled at 2.2:1, with a dropping rate of 7 mL / min. After the addition was completed, the reaction was continued for 5 h; A3. The product was filtered to remove salt, and excess epichlorohydrin was removed under reduced pressure at 70°C at 0.012 MPa; A4. When the epoxy equivalent of the product was 180 g / eq and the hydrolyzable chlorine content was 0.35 wt%, the biphenyl diglycidyl ether of this embodiment was obtained.

[0065] The aminosilane-coated hexagonal boron nitride used in this embodiment for preparing the polyimide shell-coated hexagonal boron nitride core-shell filler was prepared through the following steps: B1. Hexagonal boron nitride was activated in air at 920°C for 1.5 h; B2. 8 parts by mass of 3-aminopropyltriethoxysilane were added to a mixture of 680 parts by mass of ethanol, 80 parts by mass of deionized water, and 2.2 parts by mass of glacial acetic acid, and hydrolyzed at 30°C for 50 min, and the pH was adjusted to 4.8 by adding glacial acetic acid; B3. 100 parts by mass of the activated hexagonal boron nitride obtained in step B1 were added to the hydrolysate obtained in step B2, and the mixture was reacted at 75°C under mechanical stirring for 5 h; B4. After filtration, the mixture was washed successively with ethanol and deionized water, and dried at 110°C for 8 h to obtain aminosilane-coated hexagonal boron nitride with a silicon content of 1.6 wt%.

[0066] The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment is prepared by the following steps: C1. Dissolve 10 parts by weight of 4,4'-diaminodiphenyl ether in 750 parts by weight of 1-methyl-2-pyrrolidone and stir at 15°C for 1.5 h; C2. Add 100 parts by weight of the aminosilanized hexagonal boron nitride prepared above and disperse by high-speed shearing for 1.5 h, then add 10.9 parts by weight of pyromellitic anhydride. The product was added in four batches by weight, with the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether controlled at 1.00:1. The interval between two adjacent batches was 15 min. The reaction was carried out at 25°C for 10 h to obtain a polyamic acid-coated intermediate. C3. The polyamic acid-coated intermediate of this embodiment was filtered, washed sequentially with 1-methyl-2-pyrrolidone and ethanol, and vacuum dried at 110°C for 6 h. Then, it was thermally imidized at 240°C for 3 h under a nitrogen atmosphere using a programmed temperature rise method with a heating rate of 8°C / min and a nitrogen flow rate of 150 mL / min. C4. The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment with a shell content of 6.5 wt% and a shell thickness of 22 nm was obtained.

[0067] The median particle size D50 of the spherical alumina in this embodiment is 16 μm. The viscosity of the uncured composition formed by mixing the raw materials in this embodiment is 32 Pa·s at 25°C. The resulting high heat dissipation composite material has a flexural strength of 110 MPa and a breakdown strength of 26 kV / mm.

[0068] The preparation method of the high heat dissipation composite functional material in this embodiment includes the following steps: S1. Providing the previously prepared biphenyl diglycidyl ether; S2. Providing the previously prepared aminosilanized hexagonal boron nitride; S3. Providing the previously prepared polyimide shell-coated hexagonal boron nitride core-shell filler, wherein the polyimide shell-coated hexagonal boron nitride core-shell filler is prepared using the aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. Before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 are dried at 130°C for 6 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is 0.05 wt%; 12 parts by weight of bisphenol A diglycidyl ether, The following components were prepared in step S1: 9 parts by weight of biphenyl diglycidyl ether, 4.5 parts by weight of 1,4-butanediol diglycidyl ether, 2.5 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 60 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler, 20 parts by weight of spherical alumina, 24 parts by weight of methylhexahydrophthalic anhydride, and 1.2 parts by weight of 2-ethyl-4-methylimidazolium. The mixture was premixed at 1800 r / min for 22 min using planetary stirring, followed by degassing at a vacuum of -0.092 MPa for 20 min to obtain an uncured composition. In step S5, the uncured composition obtained in step S4 was cast and cured in stages at 95°C for 2.5 h, 140°C for 2 h, and 175°C for 2 h to obtain a high-heat-dissipation composite material with a porosity of 1.5 vol% and a thickness of 1.5 mm.

[0069] Example 2 achieves excellent thermal conductivity through high filler content and optimized filler particle size distribution, making it suitable for heat dissipation packaging of high power density electronic devices. It is particularly suitable for high-end heat dissipation applications with stringent requirements for thermal conductivity, such as high-power LEDs, IGBT modules, and server chips.

[0070] Example 3

[0071] This embodiment provides a high heat dissipation composite functional material, which is obtained by curing the following raw materials. The raw materials include, by weight, 10 parts of bisphenol A diglycidyl ether, 5.5 parts of biphenyl diglycidyl ether, 2.5 parts of 1,4-butanediol diglycidyl ether, 1.5 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 42 parts of polyimide shell-coated hexagonal boron nitride core-shell filler, 16 parts of spherical alumina, 16 parts of methylhexahydrophthalic anhydride, and 0.5 parts of 2-ethyl-4-methylimidazole.

[0072] In this embodiment, the mass ratio of polyimide-coated hexagonal boron nitride core-shell filler to spherical alumina is 2.625:1, and the total amount added is 58 parts by mass. In this embodiment, the ratio of total equivalent of anhydride groups to total equivalent of epoxy groups is 0.90:1. The median particle size D50 of the polyimide-coated hexagonal boron nitride core-shell filler in this embodiment is 8 μm, the shell thickness is 10 nm, and the shell content is 2.5 wt%. The resulting high-heat-dissipation composite material has an apparent thermal conductivity of 3.2 W / m·K and a volume resistivity of 8 × 10¹³ Ω·cm.

[0073] The biphenyl diglycidyl ether of this embodiment was prepared by the following steps: A1. 110 parts by weight of 4,4'-dihydroxybiphenyl and 500 parts by weight of epichlorohydrin were mixed and stirred at 55°C for 0.8 h; A2. 257 parts by weight of 35 wt% sodium hydroxide aqueous solution were added dropwise at 65°C, and the molar ratio of sodium hydroxide to phenolic hydroxyl groups was controlled at 1.9:1, the dropping rate was 4 mL / min, and the reaction was continued for 3 h after the addition was completed; A3. The product was filtered to remove salt, and excess epichlorohydrin was removed under reduced pressure at 60°C at 0.008 MPa; A4. When the epoxy equivalent of the product was 205 g / eq and the hydrolyzable chlorine content was 0.50 wt%, the biphenyl diglycidyl ether of this embodiment was obtained.

[0074] The aminosilane-coated hexagonal boron nitride used in this embodiment for preparing the polyimide shell-coated hexagonal boron nitride core-shell filler was prepared through the following steps: B1. Hexagonal boron nitride was activated in air at 880°C for 0.8 h; B2. 4 parts by mass of 3-aminopropyltriethoxysilane were added to a mixture of 420 parts by mass of ethanol, 40 parts by mass of deionized water, and 0.8 parts by mass of glacial acetic acid, and hydrolyzed at 25°C for 30 min, and the pH was adjusted to 5.2 by adding glacial acetic acid; B3. 100 parts by mass of the activated hexagonal boron nitride obtained in step B1 were added to the hydrolysate obtained in step B2, and the mixture was reacted at 65°C under mechanical stirring for 3 h; B4. The mixture was filtered, washed sequentially with ethanol and deionized water, and dried at 90°C for 6 h to obtain aminosilane-coated hexagonal boron nitride with a silicon content of 0.7 wt%.

[0075] The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment is prepared by the following steps: C1. Dissolve 5 parts by mass of 4,4'-diaminodiphenyl ether in 450 parts by mass of 1-methyl-2-pyrrolidone and stir at 20°C for 0.8 h; C2. Add 100 parts by mass of the aminosilanized hexagonal boron nitride prepared above and disperse ultrasonically for 0.8 h, then add pyromellitic anhydride in two batches of 5.4 parts by mass each, controlling the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether to be 1.00:1, with an interval of 25 m between adjacent batches. C3. The polyamic acid-coated intermediate of this embodiment was filtered, washed sequentially with 1-methyl-2-pyrrolidone and ethanol, and vacuum dried at 90°C for 4 hours. Then, it was thermally imidized at 200°C for 2 hours under a nitrogen atmosphere using a programmed temperature rise method with a heating rate of 4°C / min and a nitrogen flow rate of 80 mL / min. C4. The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment with a shell content of 2.5 wt% and a shell thickness of 10 nm was obtained.

[0076] The median particle size D50 of the spherical alumina in this embodiment is 6 μm. The viscosity of the uncured composition formed by mixing the raw materials in this embodiment is 10 Pa·s at 25°C. The resulting high heat dissipation composite material has a flexural strength of 85 MPa and a breakdown strength of 20 kV / mm.

[0077] The preparation method of the high heat dissipation composite functional material in this embodiment includes the following steps: S1. Providing the previously prepared biphenyl diglycidyl ether; S2. Providing the previously prepared aminosilanized hexagonal boron nitride; S3. Providing the previously prepared polyimide shell-coated hexagonal boron nitride core-shell filler, wherein the polyimide shell-coated hexagonal boron nitride core-shell filler is prepared using the aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. Before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 are dried at 110°C for 4 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is 0.08 wt%; 10 parts by weight of bisphenol A diglycidyl ether, The following components were prepared in step S1: 5.5 parts by weight of biphenyl diglycidyl ether, 2.5 parts by weight of 1,4-butanediol diglycidyl ether, 1.5 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 42 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler, 16 parts by weight of spherical alumina, 16 parts by weight of methylhexahydrophthalic anhydride, and 0.5 parts by weight of 2-ethyl-4-methylimidazolium. The mixture was mechanically stirred, premixed at 1200 r / min for 18 min, and then degassed under a vacuum of -0.085 MPa for 10 min to obtain an uncured composition. In step S5, the uncured composition obtained in step S4 was potted and cured in stages at 85°C for 2 h, 130°C for 2 h, and 165°C for 2 h to obtain a high-heat-dissipation composite material with a porosity of 0.8 vol% and a thickness of 3.0 mm.

[0078] Example 3 emphasizes processing adaptability and electrical insulation performance, and is suitable for potting processes with high flowability requirements. It is particularly suitable for applications such as transformers, sensors, and precision electronic modules that have high requirements for electrical insulation performance and require complex structure potting.

[0079] Example 4

[0080] This embodiment provides a high heat dissipation composite functional material, which is obtained by curing the following raw materials. The raw materials include, by weight, 14 parts of bisphenol A diglycidyl ether, 8 parts of biphenyl diglycidyl ether, 4 parts of 1,4-butanediol diglycidyl ether, 2.8 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 65 parts of polyimide shell-coated hexagonal boron nitride core-shell filler, 17 parts of spherical alumina, 23 parts of methylhexahydrophthalic anhydride, and 1.3 parts of 2-ethyl-4-methylimidazole.

[0081] In this embodiment, the mass ratio of polyimide-coated hexagonal boron nitride core-shell filler to spherical alumina is 3.82:1, and the total amount added is 82 parts by mass. In this embodiment, the ratio of total equivalent of anhydride groups to total equivalent of epoxy groups is 0.86:1. The median particle size D50 of the polyimide-coated hexagonal boron nitride core-shell filler in this embodiment is 23 μm, the shell thickness is 27 nm, and the shell content is 7.2 wt%. The resulting high-heat-dissipation composite material has an apparent thermal conductivity of 5.6 W / m·K and a volume resistivity of 2 × 10¹³ Ω·cm.

[0082] The biphenyl diglycidyl ether of this embodiment was prepared by the following steps: A1. 145 parts by weight of 4,4'-dihydroxybiphenyl and 750 parts by weight of epichlorohydrin were mixed and stirred at 68°C for 1.8 h; A2. 299 parts by weight of 48 wt% sodium hydroxide aqueous solution were added dropwise at 78°C, and the molar ratio of sodium hydroxide to phenolic hydroxyl groups was controlled at 2.3:1, the dropping rate was 8 mL / min, and the reaction continued for 5.5 h after the addition was completed; A3. The product was filtered to remove salt, and excess epichlorohydrin was removed under reduced pressure at 75°C at 0.018 MPa; A4. When the epoxy equivalent of the product was 190 g / eq and the hydrolyzable chlorine content was 0.38 wt%, the biphenyl diglycidyl ether of this embodiment was obtained.

[0083] The aminosilane-coated hexagonal boron nitride used in this embodiment for preparing the polyimide-shell coated hexagonal boron nitride core-shell filler was prepared through the following steps: B1. Hexagonal boron nitride was activated in air at 940°C for 1.8 h; B2. 9 parts by mass of 3-aminopropyltriethoxysilane were added to a mixture of 750 parts by mass of ethanol, 90 parts by mass of deionized water, and 2.7 parts by mass of glacial acetic acid, and hydrolyzed at 33°C for 55 min, and the pH was adjusted to 4.6 by adding glacial acetic acid; B3. 100 parts by mass of the activated hexagonal boron nitride obtained in step B1 were added to the hydrolysate obtained in step B2, and the mixture was reacted at 78°C under mechanical stirring for 5.5 h; B4. The mixture was filtered, washed sequentially with ethanol and deionized water, and dried at 115°C for 9 h to obtain aminosilane-coated hexagonal boron nitride with a silicon content of 1.8 wt%.

[0084] The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment was prepared by the following steps: C1. Dissolving 11 parts by weight of 4,4'-diaminodiphenyl ether in 850 parts by weight of 1-methyl-2-pyrrolidone, and stirring at 12°C for 1.8 h; C2. Adding 100 parts by weight of the aminosilanized hexagonal boron nitride prepared above and dispersing it by high-speed shearing for 1.8 h, followed by adding 12.0 parts by weight of pyromellitic anhydride. The product was added in four batches by weight, with the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether controlled at 1.00:1. The interval between two adjacent batches was 12 min. The reaction was carried out at 28 °C for 11 h to obtain a polyamic acid-coated intermediate. C3. The polyamic acid-coated intermediate of this embodiment was filtered, washed sequentially with 1-methyl-2-pyrrolidone and ethanol, and vacuum dried at 115 °C for 7 h. Then, it was thermally imidized at 250 °C for 3.5 h under a nitrogen atmosphere using a programmed temperature rise method with a heating rate of 9 °C / min and a nitrogen flow rate of 180 mL / min. C4. The polyimide shell-coated hexagonal boron nitride core-shell filler of this embodiment with a shell content of 7.2 wt% and a shell thickness of 27 nm was obtained.

[0085] The median particle size D50 of the spherical alumina in this embodiment is 18 μm. The viscosity of the uncured composition formed by mixing the raw materials in this embodiment is 36 Pa·s at 25°C. The resulting high heat dissipation composite material has a flexural strength of 118 MPa and a breakdown strength of 28 kV / mm.

[0086] The preparation method of the high heat dissipation composite functional material in this embodiment includes the following steps: S1. Providing the previously prepared biphenyl diglycidyl ether; S2. Providing the previously prepared aminosilanized hexagonal boron nitride; S3. Providing the previously prepared polyimide shell-coated hexagonal boron nitride core-shell filler, which is prepared using the aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. Before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, drying the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 at 135°C for 7 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is 0.04 wt%; 14 parts by weight of bisphenol A diglycidyl ether, step S4. Step S1: 8 parts by weight of biphenyl diglycidyl ether, 4 parts by weight of 1,4-butanediol diglycidyl ether, 2.8 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 65 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler, 17 parts by weight of spherical alumina, 23 parts by weight of methylhexahydrophthalic anhydride, and 1.3 parts by weight of 2-ethyl-4-methylimidazolium are premixed at 1900 r / min for 24 min using planetary stirring, followed by degassing at a vacuum of -0.095 MPa for 25 min to obtain an uncured composition. Step S5: The uncured composition obtained in step S4 is molded and then cured in stages at 98℃ for 2.2 h, 145℃ for 2.2 h, and 178℃ for 2.2 h to obtain a high-heat-dissipation composite material with a porosity of 1.8 vol% and a thickness of 0.8 mm.

[0087] Example 4 achieves extremely high thermal conductivity and excellent mechanical strength while ensuring electrical insulation performance through extremely high filler content, large filler particle size and thick polyimide shell. It is suitable for the extreme heat dissipation requirements of ultra-high power density electronic devices, and is particularly suitable for advanced packaging applications with extremely high requirements for thermal conductivity and mechanical reliability, such as electric vehicle power modules, 5G base station power amplifiers, and high-performance computing chips.

[0088] Comparative Example 1: It is basically the same as Example 1, except that in step S4, the amount of polyimide shell coating hexagonal boron nitride core-shell filler is 35 parts by mass, and other conditions remain unchanged.

[0089] Comparative Example 2: It is basically the same as Example 1, except that in step S4, the amount of polyimide shell coating hexagonal boron nitride core-shell filler is 72 parts by mass, and other conditions remain unchanged.

[0090] Comparative Example 3: It is basically the same as Example 1, except that the content of the polyimide shell layer coated with hexagonal boron nitride core-shell filler in this example is 0.8 wt%, and other conditions remain unchanged.

[0091] Comparative Example 4: Basically the same as Example 1, except that the shell thickness of the polyimide shell coating hexagonal boron nitride core-shell filler in this example is 33 nm, and other conditions remain unchanged.

[0092] Comparative Example 5: Basically the same as Example 1, except that the median particle size D50 of the polyimide shell-coated hexagonal boron nitride core-shell filler in this example is 3 μm, and other conditions remain unchanged.

[0093] Comparative Example 6: It is basically the same as Example 1, except that the amount of methylhexahydrophthalic anhydride used in step S4 is 15 parts by mass, and other conditions remain unchanged.

[0094] Comparative Example 7: Basically the same as Example 1, except that before step S4, the polyimide shell layer provided in step S3 is coated with hexagonal boron nitride core-shell filler and spherical alumina and dried at 90°C for 1 hour, while other conditions remain unchanged.

[0095] Comparative Example 8: It is basically the same as Example 1, except that the vacuum degassing time in step S4 is 3 minutes, and other conditions remain unchanged.

[0096] Performance testing: Unless otherwise specified, all performance test specimens are prepared separately with the same formula to the required size for the corresponding test; the “thickness” given in step S5 of each embodiment only represents the thickness of the representative molded product and is not used as a uniform size for thermal conductivity, breakdown or bending test specimens.

[0097] The processing window and flowability of highly filled systems at 25℃ were evaluated by rotational viscosity testing. The principle is to use a rotational viscometer to measure the apparent viscosity under constant shear conditions and determine the shear thinning behavior. After the sample was mixed and degassed, it was allowed to stand for 10 min. The sample was then placed in a 600 mL beaker, and the viscosity corresponding to 10 s^-1 was measured at 25±0.5℃ using a Brookfield rotational viscometer. The test was performed in triplicate. The test conditions were controlled at 25℃, 10 s^-1, and no obvious air bubbles in the sample. The results are expressed as mean and standard deviation. RSD ≤ 5% is considered valid.

[0098] The effectiveness of the internal thermal conductivity network of the material was verified by steady-state thermal conductivity testing. The principle is to allow a one-dimensional steady-state heat flow through the sample and calculate the apparent thermal conductivity based on the temperature difference and heat flow density. A 30mm×30mm cured sheet sample was clamped between upper and lower thermal conductive blocks, and a thin layer of thermally conductive medium was coated at the interface. After applying a constant contact pressure at 25℃, the steady-state temperature difference and heat flow were recorded. The test was performed in parallel for 3 times. The sample thickness was controlled to be 2.0±0.1mm and the contact pressure to be 0.3MPa. The results are expressed as mean ± standard deviation, and the interface thermal resistance was recorded simultaneously.

[0099] The volume insulation capability of materials under electronic packaging conditions is evaluated by DC insulation testing. The principle is to apply DC voltage to the retaining ring electrode system and calculate the volume resistivity by combining resistance with geometric dimensions. After the cured disc sample is pretreated for 24 hours at 23±2℃ and 50±5%RH, the steady-state current is tested at 500V for 60s. The test is repeated in parallel for 3 times. The sample thickness, effective electrode area and humidification time are carefully controlled. The results are expressed as the average volume resistivity ± standard deviation.

[0100] The dielectric breakdown test evaluates the material's ability to suppress local electric field concentration and defect sensitivity. The principle is to continuously increase the voltage under a power frequency electric field until the dielectric breaks down, and then calculate the breakdown strength. Cured sheets with a thickness of 0.5-1.0 mm are selected, and after surface discharge in an oil bath, the test is carried out using a ball-plate electrode. The voltage increase rate is controlled at 0.5 kV / s, and at least 10 valid data points are obtained. The key control points are the sample thickness, oil bath conditions and voltage increase rate. The results are expressed as mean ± standard deviation, and the original data required for Weibull fitting are retained.

[0101] The structural reliability of materials during the encapsulation, load-bearing, and assembly process is evaluated by a three-point bending test. The principle is to determine the bending strength of the outer surface layer of the sample when it reaches the maximum stress under three-point stress. A solidified rectangular beam sample of 80mm×10mm×4mm is prepared with the span set at a thickness ratio of 16:1 and the loading rate controlled at 2mm / min. Five parallel tests are conducted, with a focus on controlling the sample size, span ratio, and loading rate. The results are expressed as the average bending strength ± standard deviation, and the fracture mode is recorded.

[0102] The density conversion method is used to quantify the material's structural compactness and support the analysis of breakdown strength differences. The principle is to first measure the actual density of the sample, and then calculate the porosity by combining it with the theoretical density of the formula. After drying the cured block or sheet sample, the density is measured. The theoretical density is calculated by summing the theoretical volume obtained by converting the mass fraction of each component and its corresponding density. The test is performed in parallel for 3 times. The key control is the sample drying state, the test temperature of 23±2℃ and the liquid medium correction conditions. The porosity is calculated as (1-actual density / theoretical density)×100%**. The results are expressed as mean ± standard deviation.

[0103] Figure 1 The XPS:N1s high-resolution superimposed spectra of samples from Example 1, Comparative Example 3, and Comparative Example 4 are shown. X-ray photoelectron spectroscopy was used to analyze the chemical state of nitrogen on the sample surface. The basic parameters were the N1s binding energy (scanning range 397.0 to 404.5 eV) and signal intensity, while the variable parameters were the nitrogen-containing interfacial structure and hydrogen bonding environment of different samples. The results show that the N1s characteristic peak intensity and peak contribution of Example 1 are significantly higher than those of Comparative Example 3, and there is a distinguishable difference between Example 1 and Comparative Example 4. This indicates that the nitrogen-containing organic phase in Example 1 is more fully constructed on the filler surface, proving that the interfacial modification path is effective and reasonable.

[0104] Figure 2 The XPS:Si2p high-resolution superimposed spectra of samples from Example 1, Comparative Example 3, and Comparative Example 4 are shown. X-ray photoelectron spectroscopy was used to analyze the silicon chemical environment on the sample surface. The basic parameters were the Si2p binding energy (scanning range 98.5 to 106.0 eV) and signal intensity, while the variable parameters were the silicon-oxygen structure and organosilicon layer state on the surface of different samples. The results show that Example 1 retains a clear Si2p characteristic response and exhibits different peak intensity and peak area distributions compared to Comparative Example 3 and Comparative Example 4, indicating that its surface silicon-oxygen framework achieves good synergistic bonding with the subsequent organic layer, demonstrating the stability of the interface construction.

[0105] Figure 3 The XPS:O1s high-resolution superimposed spectra of samples from Example 1, Comparative Example 3, and Comparative Example 4 are shown. X-ray photoelectron spectroscopy was used to analyze the chemical state of oxygen on the sample surface. The basic parameters were the O1s binding energy (scanning range 528.0 to 536.0 eV) and signal intensity, while the variable parameters were the relative contents of imide carbonyl oxygen and silicon-oxygen bond oxygen in different samples. The results show that Example 1 exhibits strong contributions from both organic and inorganic oxygen in the O1s region, indicating that its surface possesses both an organic shell layer and a silicon-oxygen framework, proving that the interface layer design can achieve effective composite formation.

[0106] Figure 4 XPS diagrams comparing the core level peak areas of samples from Example 1, Comparative Example 3, and Comparative Example 4 are provided. The total areas of the N1s, Si2p, and O1s core levels were compared using the integrated results of X-ray photoelectron spectroscopy peak sub-segments. The basic parameters were the peak area and corresponding atomic fraction of each core level, while the variable parameters were the surface elemental composition and interface layer structure of different samples. The results show that Example 1 exhibits a more balanced and targeted distribution of nitrogen and oxygen-related peak areas, indicating a better match between the introduction of the organic phase and the retention of the inorganic phase, thus proving that this structural scheme has a clear compositional basis.

[0107] Figure 5The TG curves for Samples 1 and 3 are shown. Thermogravimetric analysis (TGA) was used to characterize the mass retention behavior of the samples during the heating process. The basic parameter was the mass retention rate within the temperature range of 30 to 800°C, and the variable parameters were the presence or absence of surface coating structures and their differences in thermal stability for different sample types. The results show that Sample 1 exhibits more pronounced but still controlled weight loss characteristics in the medium-high temperature region, indicating that an organic shell layer was indeed introduced into its surface. At the same time, the overall thermal stability remained good, proving that the interface coating structure truly exists and is feasible for processing.

[0108] Figure 6 The DTG curves of Samples 1 and 3 (Comparative Example 3) are shown. Thermogravimetric derivative analysis was used to characterize the decomposition rate during the main weight loss phase of the samples. The basic parameter was the DTG signal within the range of 30 to 800°C, and the variable parameters were the peak position and intensity variations of the thermal decomposition rate for different samples. The results show that Sample 1 exhibits a clearer characteristic decomposition peak, while the peak value in Comparative Example 3 is weaker. This indicates that the organic interface layer in Sample 1 has an independent and identifiable thermal response process, further demonstrating that the modified layer is rationally constructed and has good bonding with the matrix.

[0109] Figure 7 The laser particle size distribution (LPD) curves for Samples 1 and 5 (Comparative Example 5) are shown. LPD was used to test the volume distribution of particle groups within different particle size ranges. The basic parameters were the particle size range of 0.3 to 80 μm and the differential volume distribution value. The variable parameters were the dispersion state and agglomeration degree of the particles in different samples. The results show that the distribution peak of Sample 1 shifts towards a larger and more concentrated particle size range, and the distribution morphology is more gradual and orderly, indicating that its particle wetting and dispersion state is better than that of Comparative Example 5. This demonstrates that interface treatment helps to obtain a stable slurry structure.

[0110] Figure 8 The laser particle size distribution curves for Examples 1 and 5 (Comparative Example 5) are shown. Laser particle size analysis was used to characterize the cumulative volume fraction of the particle group as a function of particle size. The basic parameters were the particle size range of 0.3 to 80 μm and the cumulative volume distribution value, while the variable parameters were the characteristic particle sizes D10, D50, and D90 of different samples. The results show that the cumulative distribution curve of Example 1 shifts to the right overall and the transition zone is more stable, indicating that its particle size window is more consistent with the target dispersion state. This proves that the scheme can effectively improve particle size distribution and processing consistency.

[0111] Figure 9Rheological analysis of samples 1, 2, and 5 is presented as a double logarithmic graph of viscosity-shear rate. Rheological testing was used to analyze the viscosity change behavior of the slurry at different shear rates. The basic parameters were the shear rate range of 0.1 to 1000 s⁻¹ and the apparent viscosity. Variable parameters included zero-shear viscosity, shear thinning degree, and fit index under different formulation conditions. The results show that Example 1 maintains stable shear thinning characteristics while ensuring a low processing viscosity, indicating that its slurry possesses both coatability and structural stability. This demonstrates that formulation design is an effective way to coordinate dispersion and workability.

[0112] Figure 10 For the porosity of samples from Example 1, Comparative Example 7, and Comparative Example 8: box plots and original scatter plots were used. Density analysis was employed to statistically analyze the porosity content and dispersion of the composite materials of different samples. The basic parameters were the volume fraction of porosity and the distribution of repeated samples for each group of samples. The variable parameters were the interfacial bonding quality and densification level of different samples. The results showed that Example 1 had the lowest porosity and the least data dispersion, indicating that its internal structure was denser and had fewer interfacial defects after molding. This demonstrates that the structural design is beneficial for suppressing pore formation and improving material uniformity.

[0113] Figure 11 The breakdown strength of samples from Example 1, Comparative Example 7, and Comparative Example 8 is shown in the Weibull linearized fitting graph. Dielectric breakdown testing combined with Weibull statistics was used to analyze the dispersion and reliability of the electrical breakdown of the samples. The basic parameters were breakdown field strength data, failure probability, and linearized coordinates, while the variable parameters were the Weibull slope and fitting distribution characteristics of different samples. The results show that the data points of Example 1 have better linear consistency and a higher slope, indicating that its breakdown behavior distribution is more concentrated and its reliability is higher, demonstrating that low defects and a uniform interface have a positive effect on electrical insulation performance.

[0114] Figure 12 The breakdown strength of samples from Example 1, Comparative Example 7, and Comparative Example 8 is compared using a characteristic breakdown strength comparison chart. The characteristic breakdown strength of each sample was extracted from the dielectric breakdown test results and compared. The basic parameters were characteristic breakdown strength, average value, and discrete parameters, while the variable parameters were the interface structure and internal defect level of different samples. The results show that Example 1 has the highest characteristic breakdown strength, which is consistent with the porosity and Weibull distribution results, indicating that this scheme can simultaneously improve microscopic compactness and macroscopic electrical performance, proving the consistency and rationality of the overall technical approach.

[0115] Figure 13This is a macroscopic optical photograph of the high heat dissipation composite material of Example 1, used to characterize the macroscopic appearance of the sample. The sample is a sheet-like solid with a relatively smooth and continuous surface, without obvious cracks, warping, or edge defects. Combined with the porosity, flexural strength, and breakdown strength results in Table 1, it can be shown that a relatively dense cured body was obtained under the described process conditions in this example.

[0116] Figure 14 This is a scanning electron microscope (SEM) image of the high heat dissipation composite material from Example 1. The low-magnification image shows that the lamellar hexagonal boron nitride and spherical alumina are relatively uniformly distributed in the resin matrix, with no large-scale agglomeration observed. This image is mainly used to characterize the microstructure and filler distribution of the composite material after curing.

[0117] Figure 15 The image shown is a transmission electron microscope (TEM) image of the polyimide-coated hexagonal boron nitride (BN) core-shell filler from Example 1. The bright-field image reveals a continuous coating layer of approximately 15 nm on the surface of the core BN sheet. The high-resolution image shows layered BN lattice fringes, indicating that the core crystal structure remains intact. Combined with the process and shell thickness test results from steps C2 and C3, it can be concluded that this example yielded a polyimide-coated BN core-shell filler.

[0118] Table 1 Summary of performance of examples and comparative examples

[0119] As can be seen from the performance of the examples and comparative examples in Table 1, Examples 2 and 4, with their higher polyimide shell-coated hexagonal boron nitride core-shell filler content and better particle size and interface layer parameters, constructed a more continuous thermal conductivity pathway, resulting in significantly improved apparent thermal conductivity and flexural strength. Example 3 exhibited excellent processing adaptability and insulation stability with lower viscosity, lower porosity, and higher volume resistivity. Example 1 achieved a balance between thermal conductivity, insulation, mechanical properties, and processing window. Overall, each comparative example showed adverse changes in at least one or more key performance aspects, indicating that filler parameters and processing window have a significant impact on the overall material performance. The technical effect of this invention should be described as a comprehensive balance and optimization between thermal conductivity, insulation, mechanical properties, and processing performance, rather than all individual indicators being simultaneously optimal in all comparative examples. Among them, although Comparative Example 4 had a slightly higher breakdown strength than Example 1, its thermal conductivity was lower than that of Example 1, indicating that parameter combinations exceeding the shell thickness range of this invention did not achieve better overall performance.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A high heat dissipation composite functional material, characterized in that, The product is obtained by curing the following raw materials, which, by mass, include: 10-20 parts of bisphenol A diglycidyl ether; 5-15 parts of biphenyl diglycidyl ether; 2-8 parts of 1,4-butanediol diglycidyl ether; 1-4 parts of 3-glycidyl etheroxypropyltrimethoxysilane; 40-70 parts of polyimide-coated hexagonal boron nitride core-shell filler; 10-30 parts of spherical alumina; 10-25 parts of methylhexahydrophthalic anhydride; and 0.2-1.5 parts of 2-ethyl-4-methylimidazolium. The mass ratio of the polyimide-shell-coated hexagonal boron nitride core-shell filler to the spherical alumina is 2:1-5:1, and the total addition amount is 55-85 parts by mass; the ratio of the total equivalent of acid anhydride groups to the total equivalent of epoxy groups is 0.85-1.05:1; wherein the median particle size D50 of the polyimide-shell-coated hexagonal boron nitride core-shell filler is 5-25 μm, the shell thickness is 5-30 nm, and the shell content is 1-8 wt%. The resulting high heat dissipation composite material has an apparent thermal conductivity of 2.5-6.0 W / m·K and a volume resistivity of 1×10⁻⁶. 12 -1×10 15 Ω·cm.

2. The high heat dissipation composite functional material according to claim 1, characterized in that, The biphenyl diglycidyl ether is prepared by the following steps: A1. Mix 100-150 parts by weight of 4,4'-dihydroxybiphenyl with 400-800 parts by weight of epichlorohydrin, and stir at 50-70°C for 0.5-2 hours; A2. Add 30-50wt% sodium hydroxide aqueous solution dropwise at 60-80℃, and control the molar ratio of sodium hydroxide to phenolic hydroxyl groups to be 1.8-2.4:1, and continue the reaction for 2-6 hours; A3. Filter to remove salt, and remove excess epichlorohydrin under reduced pressure at 50-80℃ under 0.005-0.020MPa; A4. When the epoxy equivalent of the product is 170-220 g / eq and the hydrolyzable chlorine content is ≤0.60 wt%, the biphenyl diglycidyl ether is obtained.

3. The high heat dissipation composite functional material according to claim 1, characterized in that, The aminosilanized hexagonal boron nitride used to prepare the polyimide shell-coated hexagonal boron nitride core-shell filler is prepared through the following steps: B1. Activate hexagonal boron nitride in air at 850-950℃ for 0.5-2h; B2. Add 2-10 parts by weight of 3-aminopropyltriethoxysilane to a mixture consisting of 300-800 parts by weight of ethanol, 20-100 parts by weight of deionized water and 0.5-3 parts by weight of glacial acetic acid, hydrolyze at 20-35℃ for 20-60 min, and adjust the pH to 4.5-5.5; B3. Add 100 parts by mass of activated hexagonal boron nitride obtained in step B1 to the hydrolysate obtained in step B2, and react at 60-80℃ for 2-6 hours; B4. After filtration and washing with ethanol and deionized water in sequence, dry at 80-120℃ for 4-10h to obtain aminosilanized hexagonal boron nitride with a silicon content of 0.3-2.0wt%.

4. The high heat dissipation composite functional material according to claim 3, characterized in that, The polyimide shell-coated hexagonal boron nitride core-shell filler is prepared through the following steps: C1. Dissolve 3-12 parts by weight of 4,4'-diaminodiphenyl ether in 300-900 parts by weight of 1-methyl-2-pyrrolidone and stir at 10-25°C for 0.5-2 hours; C2. After adding 100 parts by weight of the aminosilanized hexagonal boron nitride and dispersing for 0.5-2 hours, 3-12 parts by weight of pyromellitic anhydride are added in batches, controlling the molar ratio of pyromellitic anhydride to 4,4'-diaminodiphenyl ether to be 0.95-1.05:1, and reacting at 10-30°C for 4-12 hours to obtain the polyamic acid coated intermediate; C3. The polyamic acid-coated intermediate is filtered, washed and dried, and then thermally imidized at 180-260°C for 1-4 hours under an inert atmosphere; C4. Obtain the polyimide shell-coated hexagonal boron nitride core-shell filler with a shell content of 1-8 wt% and a shell thickness of 5-30 nm.

5. The high heat dissipation composite functional material according to claim 1, characterized in that, The median particle size D50 of the spherical alumina is 3-20 μm; the mass ratio of the polyimide shell-coated hexagonal boron nitride core-shell filler to the spherical alumina is 2:1-5:1; the ratio of the total equivalent of acid anhydride groups to the total equivalent of epoxy groups is 0.85-1.05:1; the uncured composition formed by mixing the raw materials is subjected to a shear rate of 10 s at 25°C. -1 The apparent viscosity under the given conditions is 5-40 Pa·s; the flexural strength of the resulting high heat dissipation composite material is 70-130 MPa, and the breakdown strength is 15-30 kV / mm.

6. A method for preparing a high heat dissipation composite functional material as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Provide the prepared biphenyl diglycidyl ether; S2. Provides the prepared aminosilanized hexagonal boron nitride; S3. Provide a polyimide shell-coated hexagonal boron nitride core-shell filler, which is prepared using aminosilanized hexagonal boron nitride provided in step S2 as raw material; S4. Mix 10-20 parts by weight of bisphenol A diglycidyl ether, 5-15 parts by weight of biphenyl diglycidyl ether provided in step S1, 2-8 parts by weight of 1,4-butanediol diglycidyl ether, 1-4 parts by weight of 3-glycidyl etheroxypropyltrimethoxysilane, 40-70 parts by weight of polyimide shell-coated hexagonal boron nitride core-shell filler provided in step S3, 10-30 parts by weight of spherical alumina, 10-25 parts by weight of methylhexahydrophthalic anhydride, and 0.2-1.5 parts by weight of 2-ethyl-4-methylimidazolium at 500-3000 r / min for 10-40 min, wherein the mixture is first premixed at 1000-2000 r / min for 15-25 min, and then degassed at a vacuum of -0.098 MPa to -0.08 MPa for 5-30 min to obtain an uncured composition; S5. The uncured composition obtained in step S4 is molded, cast or potted, and then cured in stages at 80-100℃ for 1-3h, 120-150℃ for 1-3h and 160-180℃ for 1-3h to obtain a high heat dissipation composite functional material.

7. The preparation method according to claim 6, characterized in that, Before mixing the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 with other preparation raw materials, the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 are dried at 100-140℃ for 2-8 hours, so that the water content of the polyimide shell-coated hexagonal boron nitride core-shell filler and spherical alumina provided in step S3 is ≤0.10wt%.

8. The preparation method according to claim 6, characterized in that, In step S4, the mass ratio of the polyimide shell-coated hexagonal boron nitride core-shell filler and the spherical alumina provided in step S3 is 2:1-5:1, and the total amount of the polyimide shell-coated hexagonal boron nitride core-shell filler and the spherical alumina provided in step S3 is 55-85 parts by mass; the mixing method in step S4 is to first premix at 1000-2000 r / min for 15-25 min, and then perform vacuum degassing for 5-30 min; the molding method in step S5 is compression molding, casting, or potting molding.

9. The preparation method according to claim 6, characterized in that, The segmented curing regime in step S5 is as follows: 1.5-2.5h at 85-95℃, 1.5-2.5h at 130-140℃, and 1.5-2.5h at 165-175℃; the porosity of the resulting high heat dissipation composite functional material is ≤2.0 vol%, and the thickness is 0.1-5.0 mm.

10. The application of a high heat dissipation composite functional material as described in any one of claims 1-5 or a high heat dissipation composite functional material obtained by the preparation method described in any one of claims 6-9 in the packaging of electronic and electrical devices.

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