A modified epoxy resin encapsulating material and a method for preparing the same

Abstract

This invention relates to the field of epoxy resin preparation technology, specifically disclosing a modified epoxy resin encapsulation material and its preparation method, comprising the following raw materials in parts by weight: 96-130 parts resin matrix, 14-16 parts thermally conductive filler, 9-12 parts composite flame retardant, 4.6-5.6 parts curing accelerator, 1.2-1.4 parts photoinitiator, and 440-500 parts solvent. This invention adds a terminal hydroxyl hyperbranched polymer and a thermally conductive filler to the modified epoxy resin encapsulation material. This polymer contains abundant active hydroxyl groups, benzene rings, -Si-O-Si bonds, and thiol groups, which can not only undergo a curing reaction with bisphenol A type epoxy resin but also react with the thermally conductive filler, thereby increasing the overall crosslinking density of the modified epoxy resin encapsulation material, improving the dispersibility of the thermally conductive filler, and enhancing both thermal conductivity and the ablation resistance and mechanical properties of the modified epoxy resin encapsulation material.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin preparation technology, and more specifically, to a modified epoxy resin encapsulation material and its preparation method. Background Technology

[0002] Epoxy resins are widely used in electronic packaging due to their excellent insulation, high mechanical strength, good adhesion, and chemical stability. As electronic devices evolve towards higher frequencies, miniaturization, and higher power densities, higher demands are being placed on epoxy resin encapsulation materials.

[0003] However, epoxy resin has a high coefficient of thermal expansion and poor thermal conductivity, making it difficult to meet the requirements of efficient heat dissipation for electronic devices. Existing technologies often add thermally conductive fillers to improve the thermal conductivity of epoxy resin encapsulation materials. However, these fillers are prone to agglomeration, leading to uneven dispersion and stress concentration points. This not only reduces mechanical and thermal conductivity properties but also decreases ablation resistance. Summary of the Invention

[0004] To address the issue of poor dispersion between the thermally conductive filler and the epoxy resin substrate, which leads to reduced mechanical and thermal conductivity properties of the prepared epoxy resin encapsulation material, and to improve the ablation resistance of the epoxy resin encapsulation material, this invention provides a modified epoxy resin encapsulation material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A modified epoxy resin encapsulation material comprises the following raw materials in parts by weight: 96-130 parts resin matrix, 14-16 parts thermally conductive filler, 9-12 parts composite flame retardant, 4.6-5.6 parts curing accelerator, 1.2-1.4 parts photoinitiator, and 440-500 parts solvent;

[0007] The preparation method of this modified epoxy resin encapsulation material includes the following steps:

[0008] Add the resin matrix, thermally conductive filler, composite flame retardant and photoinitiator to the solvent, stir evenly, heat to 76-80℃, and irradiate with ultraviolet light while stirring for 18-22 minutes. Then add the curing accelerator, heat to 90-100℃, continue stirring for 32-46 minutes, and then evaporate by rotary evaporation to obtain the modified epoxy resin encapsulation material.

[0009] Preferably, the solvent is cyclohexanone or dimethyl sulfoxide.

[0010] Preferably, the curing accelerator is at least one selected from 1-benzylphenyl-2-ethylimidazole, 2-ethyl-4-methylimidazole and 1-aminoethyl-2-methylimidazole.

[0011] Preferably, the photoinitiator is 1-hydroxycyclohexylphenyl ketone or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0012] Preferably, the composite flame retardant is composed of toluene diphenyl phosphate, antimony trioxide, and melamine in a mass ratio of 1-3:2:1.2-1.6.

[0013] Preferably, the resin matrix is ​​prepared by the following steps:

[0014] Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol are added to anhydrous DMF. The mixture is heated to 62-64℃ and stirred until homogeneous. The temperature is then raised to 130-140℃, and the reaction is continued for 3.4-4.6 hours. The mixture is then rotary evaporated, washed, and dried to obtain a thiol monomer. The mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF is 1:0.03-0.05:0.82-0.9:35-45. During the above reaction, anhydrous DMF is used as the solvent. The carboxyl group on 2-mercapto-1,4-phthalic acid undergoes an esterification reaction with the active hydroxyl group on pentaerythritol to obtain the thiol monomer. During the reaction, the amount of pentaerythritol is controlled to be slightly higher than the equivalent amount of 2-mercapto-1,4-phthalic acid so that after the reaction, there are still residual hydroxyl groups that can participate in subsequent reaction processes.

[0015] Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid, heat to 126-140℃, stir under nitrogen protection for 2.2-2.8h, then react under reduced pressure for 1.6-2h. Then add mercapto monomer and p-toluenesulfonic acid again, stir for 3-3.4h, react under reduced pressure for 2.6-2.8h, and cool to room temperature to obtain a hydroxyl-terminated hyperbranched polymer. The mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid is 3.2-4.4:1-1.4:0.02-0.04. The amount of mercapto monomer added again is 3 times the mass of the mercapto monomer added in the first reaction. The mass of p-toluenesulfonic acid added in both reactions is the same. First, the -OH group of the hydroxypropyl-terminated polydimethylsiloxane reacts with the -COOH group of the mercapto monomer to undergo an esterification reaction. Then, the hydroxyl group of the mercapto monomer reacts with the carboxyl group of the mercapto monomer to undergo an esterification reaction to obtain a hydroxyl-terminated hyperbranched polymer.

[0016] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 90-100℃, stir and react for 2.2-2.6h, cool to room temperature, and then add ethyl acetate to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1-2:4.6-5.2:0.2-0.4:16-20:14-18. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2-3:1.

[0017] Preferably, the thermally conductive filler is prepared by the following steps:

[0018] Step B1: Under nitrogen protection, nano-hexagonal boron nitride is added to an alkaline solution, heated to 78-82℃, stirred for 72-80 h, precipitated, washed, and dried to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to alkaline solution is 3-5:550-650.

[0019] Step B2: Add tannic acid to an ethanol aqueous solution, stir evenly, adjust the pH to 7.0-7.4, then add pretreated boron nitride solution and ammonium persulfate aqueous solution, heat to 76-84℃, stir for 0.6-0.8h, filter, wash, and dry to obtain polytannic acid modified boron nitride. The mass ratio of tannic acid, ethanol aqueous solution, pretreated boron nitride solution and ammonium persulfate aqueous solution is 2-3:40-50:18-22:8-10. Under alkaline conditions and the catalysis of ammonium persulfate, tannic acid can not only undergo self-polymerization, but also the phenolic hydroxyl groups on it can form hydrogen bonds with the active hydroxyl groups on boron nitride. The benzene ring can interact with boron nitride through π-π interactions, thereby coating the surface of boron nitride with polytannic acid to obtain polytannic acid modified boron nitride.

[0020] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 45-55℃, stir evenly, adjust pH to 8.1-8.5, and while stirring, dropwise add a mixture b of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol. Heat to 76-82℃, continue stirring for 8-12 hours, adjust pH to neutral, rotary evaporate, wash and dry to obtain the thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture b is 4-6:70-80:30-40. In mixture a, the mass ratio of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol is 2.6-3.4:0.08-0.12:22-26. During the reaction, control the amount of allyl glycidyl ether to be slightly higher than that of polytannic acid-modified boron nitride so that there are still residual epoxy groups that can participate in subsequent reactions after the reaction is completed.

[0021] Preferably, in step B1, the alkaline solution is a sodium hydroxide aqueous solution with a mass fraction of 20-30%.

[0022] Preferably, in step B2, the mass fraction of the ethanol aqueous solution is 46-50%.

[0023] Preferably, in step B2, the pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water in a mass ratio of 1:35-45:8-12.

[0024] Preferably, in step B2, the ammonium persulfate aqueous solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:20-24.

[0025] In summary, the present invention has the following beneficial effects: To improve the mechanical properties, ablation resistance, and thermal conductivity of modified epoxy resin encapsulation materials, the present invention addresses this issue from two aspects. Firstly, it adds a terminal hydroxyl hyperbranched polymer to the resin matrix. This polymer contains abundant active hydroxyl groups, benzene rings, -Si-O-Si bonds, and thiol groups. The active hydroxyl groups can chemically react with bisphenol A type epoxy resin, increasing the crosslinking degree of the modified epoxy resin encapsulation material and strengthening the intermolecular bonding force, thereby improving the mechanical properties of the modified epoxy resin encapsulation material. Secondly, it can undergo a ring-opening reaction with the epoxy groups of the thermally conductive filler, increasing the crosslinking degree and the dispersibility of the thermally conductive filler, thus improving the mechanical properties, ablation resistance, and thermal conductivity of the modified epoxy resin encapsulation material. The presence of -Si-O-Si bonds, on the one hand, works with the rigid benzene ring to improve the ablation resistance of the modified epoxy resin encapsulation material; on the other hand, in the polymer... The formation of polysiloxane-epoxy resin block copolymers in urethane coatings endows modified epoxy resin encapsulation materials with the ablation resistance and mechanical properties of organosiloxanes. The presence of thiol groups can chemically bond with the saturated double bonds in the thermally conductive filler, improving the crosslinking degree of the modified epoxy resin encapsulation material and the dispersibility of the thermally conductive filler, further enhancing the mechanical properties, ablation resistance, and thermal conductivity of the modified epoxy resin encapsulation material. Secondly, the addition of thermally conductive fillers leverages the excellent physical properties of nano-boron nitride to improve the ablation resistance and mechanical properties of the modified epoxy resin encapsulation material. Furthermore, the polytannic acid grafted onto the surface of modified nano-titanium dioxide possesses a fused polycyclic aliphatic ring rigid structure with high rigidity and good heat resistance. Introducing it into the modified epoxy resin encapsulation material allows it to synergistically work with the terminal hydroxyl hyperbranched polymer to jointly improve the mechanical properties, ablation resistance, and thermal conductivity of the modified epoxy resin encapsulation material. Detailed Implementation

[0026] The main raw materials and their component contents used in the examples are shown below:

[0027] The phosphate buffer is commercially available from Ise-Ku (Lianyungang, Jiangsu) Biotechnology Co., Ltd., CAS No. N / A, pH 7.0-7.4; the hydroxypropyl-terminated polydimethylsiloxane is commercially available from Shanghai Mairui Biochemical Technology Co., Ltd., CAS No. 104780-66-7; the polyethylene glycol is polydiol 2000 commercially available from Jiangsu Haian Petrochemical Plant, CAS No. 25322-68-3; the nano-hexagonal boron nitride is commercially available from Nangong Jiuxin New Material Technology Co., Ltd., CAS No. 10043-11-5; and the bisphenol A type epoxy resin is E-51 epoxy resin commercially available from Hubei Langbowan Biomedical Co., Ltd., product grade is superior.

[0028] The present invention will be further described in detail below with reference to the embodiments.

[0029] Preparation Examples 1-3 and Comparative Preparation Examples 1-3 provide methods for preparing resin matrices.

[0030] Preparation Example 1

[0031] This preparation example provides a resin matrix, which is prepared by the following steps:

[0032] Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The temperature was raised to 62°C, and the mixture was stirred at 440 rpm for 12 min until homogeneous. The temperature was then raised to 130°C, and the stirring speed was maintained at the same level for 3.4 h. The rotary evaporation temperature was controlled at 82°C, and the anhydrous DMF was removed by rotary evaporation. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 62°C to constant weight to obtain the thiol monomer. The mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.03:0.82:35.

[0033] Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid, heat to 126°C, and under nitrogen protection, stir at 600 rpm for 2.2 h, then react under reduced pressure for 1.6 h. Then add mercapto monomer and p-toluenesulfonic acid again, maintain the stirring speed, continue stirring for 3 h, then react under reduced pressure for 2.6 h, and cool to room temperature to obtain a hydroxyl-terminated hyperbranched polymer. The mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid is 3.2:1:0.02. The amount of mercapto monomer added again is three times the mass of the mercapto monomer added in the first reaction, and the mass of p-toluenesulfonic acid added in both reactions is the same.

[0034] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 90°C, control the stirring speed at 680 rpm, stir for 2.2 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed, and stir for 12 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1:4.6:0.2:16:14. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2:1.

[0035] Preparation Example 2

[0036] This preparation example provides a resin matrix, which is prepared by the following steps:

[0037] Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The mixture was heated to 63°C and stirred at 460 rpm for 14 min until homogeneous. The temperature was then raised to 135°C, and the stirring was continued for 4 h while maintaining the stirring speed. The rotary evaporation temperature was controlled at 84°C until the anhydrous DMF was removed. The mixture was then washed four times with anhydrous ethanol and deionized water, and dried at 64°C to constant weight to obtain the thiol monomer. The mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.04:0.86:40.

[0038] Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane and p-toluenesulfonic acid, heat to 133°C, under nitrogen protection, control the stirring speed at 640 rpm, stir for 2.5 h, react under reduced pressure for 1.8 h, then add mercapto monomer and p-toluenesulfonic acid again, maintain the stirring speed, continue stirring for 3.2 h, react under reduced pressure for 2.7 h, cool to room temperature, and obtain hydroxyl-terminated hyperbranched polymer. The mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane and p-toluenesulfonic acid is 3.8:1.2:0.03. The amount of mercapto monomer added again is 3 times the mass of the mercapto monomer added in the first addition, and the mass of p-toluenesulfonic acid added in both additions is the same.

[0039] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 95°C, control the stirring speed at 700 rpm, stir for 2.4 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed at the same time, and stir for 14 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1.5:4.9:0.3:18:16. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2.5:1.

[0040] Preparation Example 3

[0041] This preparation example provides a resin matrix, which is prepared by the following steps:

[0042] Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The temperature was raised to 64°C, and the mixture was stirred at 480 rpm for 16 min until homogeneous. The temperature was then raised to 140°C, and the stirring speed was maintained at the same level for 4.6 h. The rotary evaporation temperature was controlled at 86°C, and the anhydrous DMF was removed by rotary evaporation. The mixture was then washed five times with anhydrous ethanol and deionized water, and dried at 66°C to constant weight to obtain the thiol monomer. The mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.05:0.9:45.

[0043] Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid, heat to 140°C, and stir at 680 rpm for 2.8 h under nitrogen protection. Then, reduce the vacuum to 0.06 MPa and react for 2 h. Add mercapto monomer and p-toluenesulfonic acid again, maintain the stirring speed, and continue stirring for 3.4 h. React under reduced vacuum for 2.8 h and then cool to room temperature to obtain a hydroxyl-terminated hyperbranched polymer. The mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid is 4.4:1.4:0.04. The amount of mercapto monomer added again is three times the mass of the mercapto monomer added in the first reaction, and the mass of p-toluenesulfonic acid added in both reactions is the same.

[0044] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 100°C, control the stirring speed at 720 rpm, stir for 2.6 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed, and stir for 16 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 2:5.2:0.4:20:18. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 3:1.

[0045] Comparative Preparation Example 1

[0046] This comparative preparation example provides a resin matrix, which is prepared by the following steps:

[0047] Step A1: Under nitrogen protection, 1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The mixture was heated to 62°C and stirred at 440 rpm for 12 minutes until homogeneous. The temperature was then raised to 130°C, and the stirring speed was maintained at the same level for 3.4 hours. The rotary evaporation temperature was controlled at 82°C until the anhydrous DMF was removed. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 62°C to constant weight to obtain polyhydroxy monomers. The mass ratio of 1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.03:0.82:35.

[0048] Step A2: Mix the polyhydroxy monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid, heat to 126°C, and stir at 600 rpm for 2.2 h under nitrogen protection. Then, reduce the vacuum to 0.07 MPa and react under reduced pressure for 1.6 h. Add the polyhydroxy monomer and p-toluenesulfonic acid again, maintain the stirring speed, and continue stirring for 3 h. Then, reduce the vacuum to 2.6 h and cool to room temperature to obtain the hydroxyl-terminated hyperbranched polymer. The mass ratio of the polyhydroxy monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid is 3.2:1:0.02. The amount of polyhydroxy monomer added again is three times the mass of the polyhydroxy monomer added in the first reaction, and the mass of p-toluenesulfonic acid added in both reactions is the same.

[0049] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 90°C, control the stirring speed at 680 rpm, stir for 2.2 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed, and stir for 12 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1:4.6:0.2:16:14. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2:1.

[0050] Comparative Preparation Example 2

[0051] This comparative preparation example provides a resin matrix, which is prepared by the following steps:

[0052] Step A1: Under nitrogen protection, mercaptosuccinic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The temperature was raised to 62°C, and the mixture was stirred at 440 rpm for 12 min until homogeneous. The temperature was then raised to 130°C, and the stirring speed was maintained at the same level for 3.4 h. The rotary evaporation temperature was controlled at 82°C, and the mixture was evaporated until the anhydrous DMF was removed. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 62°C to constant weight to obtain the mercapto monomer. The mass ratio of mercaptosuccinic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.03:0.82:35.

[0053] Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid, heat to 126°C, and stir at 600 rpm for 2.2 h under nitrogen protection. Then, reduce the vacuum to 0.08 MPa and react under reduced pressure for 1.6 h. Add mercapto monomer and p-toluenesulfonic acid again, maintain the stirring speed, and continue stirring for 3 h. Then, reduce the vacuum to 2.6 h and cool to room temperature to obtain a hydroxyl-terminated hyperbranched polymer. The mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane, and p-toluenesulfonic acid is 3.2:1:0.02. The amount of mercapto monomer added again is three times the mass of the mercapto monomer added in the first reaction, and the mass of p-toluenesulfonic acid added in both reactions is the same.

[0054] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 90°C, control the stirring speed at 680 rpm, stir for 2.2 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed, and stir for 12 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1:4.6:0.2:16:14. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2:1.

[0055] Comparative preparation example 3

[0056] This comparative preparation example provides a resin matrix, which is prepared by the following steps:

[0057] Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, and pentaerythritol were added to anhydrous DMF. The temperature was raised to 62°C, and the mixture was stirred at 440 rpm for 12 min until homogeneous. The temperature was then raised to 130°C, and the stirring speed was maintained at the same level for 3.4 h. The rotary evaporation temperature was controlled at 82°C, and the anhydrous DMF was removed by rotary evaporation. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 62°C to constant weight to obtain the thiol monomer. The mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol, and anhydrous DMF was 1:0.03:0.82:35.

[0058] Step A2: Mix the thiol monomer, polyethylene glycol, and p-toluenesulfonic acid, heat to 126°C, and under nitrogen protection, stir at 600 rpm for 2.2 h, then react under reduced pressure for 1.6 h. Then add the thiol monomer and p-toluenesulfonic acid again, maintain the stirring speed, and continue stirring for 3 h. Under vacuum of 0.06 MPa, react under reduced pressure for 2.6 h, and then cool to room temperature to obtain a hydroxyl-terminated hyperbranched polymer. The mass ratio of thiol monomer, polyethylene glycol, and p-toluenesulfonic acid is 3.2:1:0.02. The amount of thiol monomer added again is three times the mass of the first addition, and the mass of p-toluenesulfonic acid added in both cases is the same.

[0059] Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, and benzyltriethylammonium chloride to a mixed solvent, heat to 90°C, control the stirring speed at 680 rpm, stir for 2.2 h, cool to room temperature, then add ethyl acetate, maintain the stirring speed, and stir for 12 min until homogeneous to obtain the resin matrix. The mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A epoxy resin, benzyltriethylammonium chloride, mixed solvent, and ethyl acetate is 1:4.6:0.2:16:14. The mixed solvent includes xylene and cyclohexanone in a mass ratio of 2:1.

[0060] Preparation Examples 4-6 and Comparative Preparation Example 4-5 provide methods for preparing thermally conductive fillers.

[0061] Preparation Example 4

[0062] This preparation example provides a thermally conductive filler, which is prepared by the following steps:

[0063] Step B1: Under nitrogen protection, nano-hexagonal boron nitride was added to a 20% sodium hydroxide aqueous solution, heated to 78°C, and stirred at 560 rpm for 72 hours. The precipitate was washed three times each with anhydrous methanol and deionized water, and dried at 56°C to constant weight to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to the 20% sodium hydroxide aqueous solution was 3:550.

[0064] Step B2: Add tannic acid to a 46% (w / w) aqueous ethanol solution and stir at 500 rpm for 18 min until homogeneous. Adjust the pH to 7.0 with phosphate buffer solution, then add pretreated boron nitride solution and ammonium persulfate solution. Heat to 76°C, maintain constant stirring speed, and continue stirring for 0.6 h. Filter and wash three times each with anhydrous ethanol and deionized water. Dry at 50°C to constant weight to obtain polytannic acid-modified boron nitride. The mass ratio of tannic acid, aqueous ethanol solution, pretreated boron nitride solution, and ammonium persulfate solution is 2:40:18:8. The pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water at a mass ratio of 1:35:8. The ammonium persulfate solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:20.

[0065] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 45°C, and stir at 480 rpm for 14 minutes until homogeneous. Adjust the pH to 8.1 with a 0.9% sodium bicarbonate aqueous solution. While stirring, add a mixture of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol (a) dropwise, completing the addition within 30 minutes. After the addition is complete, heat to 76°C and continue stirring for 8 hours. Then, add a 0.1% sodium bicarbonate aqueous solution. The pH was adjusted to neutral with a % acetic acid aqueous solution, and the rotary evaporation temperature was controlled at 83℃. The rotary evaporation was continued until anhydrous DMF was removed. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 68℃ to constant weight to obtain a thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture a was 5:75:35. In mixture a, the mass ratio of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol was 2.9:0.10:24.

[0066] Preparation Example 5

[0067] This preparation example provides a thermally conductive filler, which is prepared by the following steps:

[0068] Step B1: Under nitrogen protection, nano-hexagonal boron nitride was added to a 25% sodium hydroxide aqueous solution, heated to 80°C, and stirred at 600 rpm for 76 hours. The precipitate was washed four times each with anhydrous methanol and deionized water, and dried at 60°C to constant weight to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to the 25% sodium hydroxide aqueous solution was 4:600.

[0069] Step B2: Add tannic acid to a 48% (w / w) aqueous ethanol solution and stir at 540 rpm for 21 min until homogeneous. Adjust the pH to 7.2 with phosphate buffer, then add the pretreated boron nitride solution and ammonium persulfate solution. Heat to 80°C, maintain constant stirring speed, and continue stirring for 0.7 h. Filter and wash with anhydrous ethanol and deionized water four times each. Dry at 55°C to constant weight to obtain polytannic acid-modified boron nitride. The mass ratio of tannic acid, aqueous ethanol solution, pretreated boron nitride solution, and ammonium persulfate solution is 2.5:45:20:9. The pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water at a mass ratio of 1:40:10. The ammonium persulfate solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:22.

[0070] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 50°C, and stir at 500 rpm for 16 minutes until homogeneous. Adjust pH with a 1.0% sodium bicarbonate aqueous solution. H was adjusted to 8.3. While stirring, a mixture of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol (a) was added dropwise over 30 minutes. After the addition was complete, the temperature was raised to 79°C, and the stirring speed was maintained. The reaction was continued for 10 hours. The pH was then adjusted to neutral with a 0.15% acetic acid aqueous solution. The rotary evaporation temperature was controlled at 85°C until anhydrous DMF was removed. The mixture was then washed four times with anhydrous ethanol and deionized water, and dried at 70°C to constant weight to obtain the thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture a was 5:75:35. In mixture a, the mass ratio of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol was 3.0:0.10:24.

[0071] Preparation Example 6

[0072] This preparation example provides a thermally conductive filler, which is prepared by the following steps:

[0073] Step B1: Under nitrogen protection, nano-hexagonal boron nitride was added to a 30% sodium hydroxide aqueous solution, heated to 82°C, and stirred at 620 rpm for 80 h. The precipitate was washed five times each with anhydrous methanol and deionized water, and dried at 64°C to constant weight to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to the 30% sodium hydroxide aqueous solution was 5:650.

[0074] Step B2: Add tannic acid to a 55% (w / w) aqueous ethanol solution and stir at 580 rpm for 24 min until homogeneous. Adjust the pH to 7.4 with phosphate buffer solution, then add pretreated boron nitride solution and ammonium persulfate solution. Heat to 84°C, maintain constant stirring speed, and continue stirring for 0.8 h. Filter and wash 5 times each with anhydrous ethanol and deionized water. Dry at 60°C to constant weight to obtain polytannic acid modified boron nitride. The mass ratio of tannic acid, aqueous ethanol solution, pretreated boron nitride solution, and ammonium persulfate solution is 3:50:22:10. The pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water at a mass ratio of 1:45:12. The ammonium persulfate solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:24.

[0075] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 55°C, and stir at 520 rpm for 18 minutes until homogeneous. Adjust pH with a 1.1% sodium bicarbonate aqueous solution. The pH was increased to 8.5. While stirring, a mixture of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol (a) was added dropwise over 30 minutes. After the addition was complete, the temperature was raised to 82°C, and the stirring speed was maintained. The reaction was continued for 12 hours. The pH was then adjusted to neutral with a 0.2% acetic acid aqueous solution. The rotary evaporation temperature was controlled at 87°C until anhydrous DMF was removed. The mixture was then washed five times with anhydrous ethanol and deionized water, and dried at 72°C to constant weight to obtain the thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture a was 6:80:40. In mixture a, the mass ratio of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol was 3.4:0.12:26.

[0076] Comparative preparation example 4

[0077] This comparative preparation example provides a thermally conductive filler, which is prepared by the following steps:

[0078] Step B1: Under nitrogen protection, nano-hexagonal boron nitride was added to deionized water, heated to 78°C, and stirred at 560 rpm for 72 hours. The precipitate was washed three times each with anhydrous methanol and deionized water, and dried at 56°C to constant weight to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to deionized water was 3:550.

[0079] Step B2: Add tannic acid to a 46% (w / w) aqueous ethanol solution and stir at 500 rpm for 18 min until homogeneous. Adjust the pH to 7.0 with phosphate buffer solution, then add pretreated boron nitride solution and ammonium persulfate solution. Heat to 76°C, maintain constant stirring speed, and continue stirring for 0.6 h. Filter and wash three times each with anhydrous ethanol and deionized water. Dry at 50°C to constant weight to obtain polytannic acid-modified boron nitride. The mass ratio of tannic acid, aqueous ethanol solution, pretreated boron nitride solution, and ammonium persulfate solution is 2:40:18:8. The pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water at a mass ratio of 1:35:8. The ammonium persulfate solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:20.

[0080] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 45°C, and stir at 480 rpm for 14 minutes until homogeneous. Adjust the pH to 8.1 with a 0.9% sodium bicarbonate aqueous solution. While stirring, add a mixture of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol (a) dropwise, completing the addition within 30 minutes. After the addition is complete, heat to 76°C and continue stirring for 8 hours. Then, add a 0.1% sodium bicarbonate aqueous solution. The pH was adjusted to neutral with a % acetic acid aqueous solution, and the rotary evaporation temperature was controlled at 83℃. The rotary evaporation was continued until anhydrous DMF was removed. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 68℃ to constant weight to obtain a thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture a was 5:75:35. In mixture a, the mass ratio of allyl glycidyl ether, tetrabutylammonium bromide, and isopropanol was 2.9:0.10:24.

[0081] Comparative preparation example 5

[0082] This comparative preparation example provides a thermally conductive filler, which is prepared by the following steps:

[0083] Step B1: Under nitrogen protection, nano-hexagonal boron nitride was added to a 20% sodium hydroxide aqueous solution, heated to 78°C, and stirred at 560 rpm for 72 hours. The precipitate was washed three times each with anhydrous methanol and deionized water, and dried at 56°C to constant weight to obtain pretreated boron nitride. The mass ratio of nano-hexagonal boron nitride to the 20% sodium hydroxide aqueous solution was 3:550.

[0084] Step B2: Add tannic acid to a 46% (w / w) aqueous ethanol solution and stir at 500 rpm for 18 min until homogeneous. Adjust the pH to 7.0 with phosphate buffer solution, then add pretreated boron nitride solution and ammonium persulfate solution. Heat to 76°C, maintain constant stirring speed, and continue stirring for 0.6 h. Filter and wash three times each with anhydrous ethanol and deionized water. Dry at 50°C to constant weight to obtain polytannic acid-modified boron nitride. The mass ratio of tannic acid, aqueous ethanol solution, pretreated boron nitride solution, and ammonium persulfate solution is 2:40:18:8. The pretreated boron nitride solution is prepared by mixing pretreated boron nitride, anhydrous ethanol, and deionized water at a mass ratio of 1:35:8. The ammonium persulfate solution is prepared by mixing ammonium persulfate and deionized water at a mass ratio of 1:20.

[0085] Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 45°C, and stir at 480 rpm for 14 minutes until homogeneous. Adjust the pH to 8.1 with a 0.9% sodium bicarbonate aqueous solution. While stirring, add a mixture of isopropyl glycidyl ether, tetrabutylammonium bromide, and isopropanol (a) dropwise, completing the addition within 30 minutes. After the addition is complete, heat to 76°C and continue stirring for 8 hours. Then, add a 0.1% sodium bicarbonate aqueous solution. The pH was adjusted to neutral with a % acetic acid aqueous solution, and the rotary evaporation temperature was controlled at 83℃. The rotary evaporation was continued until anhydrous DMF was removed. The mixture was then washed three times with anhydrous ethanol and deionized water, and dried at 68℃ to constant weight to obtain a thermally conductive filler. The mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture a was 5:75:35. In mixture a, the mass ratio of isopropyl glycidyl ether, tetrabutylammonium bromide, and isopropanol was 2.9:0.10:24.

[0086] Examples 1-3 and Comparative Examples 1-5 provide modified epoxy resin encapsulation materials and their preparation methods.

[0087] Example 1

[0088] This embodiment provides a modified epoxy resin encapsulation material, comprising the following raw materials in parts by weight: 96 parts of the resin matrix prepared in Example 1, 14 parts of the thermally conductive filler prepared in Example 4, 9 parts of the composite flame retardant, 4.6 parts of 1-benzylphenyl-2-ethylimidazole, 1.2 parts of 1-hydroxycyclohexylphenyl ketone, and 440 parts of cyclohexanone.

[0089] The preparation method of this modified epoxy resin encapsulation material includes the following steps:

[0090] The resin matrix, thermally conductive filler, composite flame retardant, and 1-hydroxycyclohexylphenyl ketone were added to cyclohexanone and stirred at 680 rpm for 18 minutes until homogeneous. The mixture was then heated to 76°C and stirred while being placed in a container with a wavelength peak of 365 nm and an intensity of 80 mw / cm². 2Irradiate under ultraviolet light for 18 min, then add 1-benzylphenyl-2-ethylimidazole, heat to 90℃, maintain constant rotation speed, continue stirring for 32 min, control the rotary evaporation pressure at 0.4 kPa, and the rotary evaporation temperature at 82℃ until cyclohexanone is removed, to obtain modified epoxy resin encapsulation material. The composite flame retardant is composed of toluene diphenyl phosphate, antimony trioxide, and melamine in a mass ratio of 1:2:1.2.

[0091] Example 2

[0092] This embodiment provides a modified epoxy resin encapsulation material, comprising the following raw materials in parts by weight: 108 parts of the resin matrix prepared in Example 2, 15 parts of the thermally conductive filler prepared in Example 5, 10.5 parts of the composite flame retardant, 5.1 parts of 2-ethyl-4-methylimidazole, 1.3 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 470 parts of dimethyl sulfoxide;

[0093] The preparation method of this modified epoxy resin encapsulation material includes the following steps:

[0094] The resin matrix, thermally conductive filler, composite flame retardant, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide were added to dimethyl sulfoxide and stirred at 710 rpm for 21 minutes until homogeneous. The mixture was then heated to 78°C and stirred while being placed in a container with a wavelength peak of 365 nm and an intensity of 80 mW / cm². 2 Irradiate under ultraviolet light for 20 min, then add 2-ethyl-4-methylimidazole, heat to 95℃, maintain constant rotation speed, and continue stirring for 39 min. Control the rotary evaporation pressure at 0.07 MPa and the rotary evaporation temperature at 45℃ until dimethyl sulfoxide is removed to obtain the modified epoxy resin encapsulating material. The composite flame retardant is composed of toluene diphenyl phosphate, antimony trioxide, and melamine in a mass ratio of 2:2:1.4.

[0095] Example 3

[0096] This embodiment provides a modified epoxy resin encapsulation material, comprising the following raw materials in parts by weight: 130 parts of the resin matrix prepared in Example 3, 16 parts of the thermally conductive filler prepared in Example 6, 12 parts of the composite flame retardant, 5.6 parts of 1-aminoethyl-2-methylimidazole, 1.4 parts of 1-hydroxycyclohexylphenyl ketone, and 500 parts of cyclohexanone.

[0097] The preparation method of this modified epoxy resin encapsulation material includes the following steps:

[0098] The resin matrix, thermally conductive filler, composite flame retardant, and 1-hydroxycyclohexylphenyl ketone were added to cyclohexanone and stirred at 740 rpm for 24 minutes until homogeneous. The mixture was then heated to 80°C and stirred while being placed in a container with a wavelength peak of 365 nm and an intensity of 80 mw / cm². 2Irradiate under ultraviolet light for 22 min, then add 1-aminoethyl-2-methylimidazole, heat to 100℃, maintain constant rotation speed, continue stirring for 46 min, control the rotary evaporation pressure at 0.4 kPa, and the rotary evaporation temperature at 84℃ until cyclohexanone is removed, to obtain modified epoxy resin encapsulation material. The composite flame retardant is composed of toluene diphenyl phosphate, antimony trioxide, and melamine in a mass ratio of 3:2:1.6.

[0099] Comparative Example 1

[0100] Comparative Example 1 is the same as Example 1, except that the resin matrix in Example 1 is replaced with the resin matrix prepared in Comparative Preparation Example 1.

[0101] Comparative Example 2

[0102] Comparative Example 2 is the same as Example 1, except that the resin matrix in Example 1 is replaced with the resin matrix prepared in Comparative Preparation Example 2.

[0103] Comparative Example 3

[0104] Comparative Example 3 is the same as Example 1, except that the resin matrix in Example 1 is replaced with the resin matrix prepared in Comparative Preparation Example 3.

[0105] Comparative Example 4

[0106] Comparative Example 4 is the same as Example 1, except that the thermally conductive filler in Example 1 is replaced with the thermally conductive filler prepared in Comparative Preparation Example 4.

[0107] Comparative Example 5

[0108] Comparative Example 1 is the same as Example 1, except that the thermally conductive filler in Example 1 is replaced with the thermally conductive filler prepared in the comparative preparation example.

[0109] Performance testing

[0110] 1. Mechanical property testing

[0111] The mechanical properties of the modified epoxy resin encapsulation materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested sequentially using the ASTM D882-12 material testing system. The specific test results are shown in Table 1.

[0112] Table 1 Mechanical property tests of modified epoxy resin encapsulation materials

[0113]

[0114]

[0115] As can be seen from Table 1, the modified epoxy resin encapsulation materials prepared in Examples 1-3 have superior mechanical properties compared to Comparative Examples 1-5.

[0116] 2. The ablation performance of the modified epoxy resin encapsulation materials prepared in Examples 1-3 and Comparative Examples 1-5 was tested using the oxy-acetylene ablation method. Referring to the GJB 323A-1996 standard, the ablation time was 20 seconds. Specific test results are shown in Table 2.

[0117] Table 2. Ablation performance test of modified epoxy resin encapsulation materials

[0118] project Linear ablation rate (mm / s) Mass ablation rate (g / s) Example 1 0.047 0.055 Example 2 0.043 0.050 Example 3 0.046 0.054 Comparative Example 1 0.072 0.084 Comparative Example 2 0.064 0.075 Comparative Example 3 0.143 0.126 Comparative Example 4 0.952 0.112 Comparative Example 5 0.068 0.076

[0119] As can be seen from Table 2, compared with Comparative Examples 1-5, the modified epoxy resin encapsulation materials prepared in Examples 1-3 have superior ablation resistance.

[0120] 3. The thermal conductivity of the modified epoxy resin encapsulation materials prepared in Examples 1-3 and Comparative Examples 1-5 was tested using ASTM D5470. The specific test results are shown in Table 3.

[0121] project Thermal conductivity (W / m·K) Example 1 3.12 Example 2 3.16 Example 3 3.09 Comparative Example 1 2.71 Comparative Example 2 2.67 Comparative Example 3 2.86 Comparative Example 4 2.64 Comparative Example 5 2.53

[0122] As can be seen from Table 3, compared with Comparative Examples 1-5, the modified epoxy resin encapsulation materials prepared in Examples 1-3 have superior thermal conductivity.

Claims

1. A modified epoxy resin encapsulation material, characterized in that, It includes the following raw materials by weight: 96-130 parts resin matrix, 14-16 parts thermally conductive filler, 9-12 parts composite flame retardant, 4.6-5.6 parts curing accelerator, 1.2-1.4 parts photoinitiator and 440-500 parts solvent; The resin matrix is ​​first prepared by esterification of 2-mercapto-1,4-phthalic acid and pentaerythritol to obtain a mercapto monomer, and then by esterification of hydroxypropyl-terminated polydimethylsiloxane to obtain a hydroxyl-terminated hyperbranched polymer, and finally by ring-opening reaction with bisphenol A epoxy resin. The thermally conductive filler is first prepared by treating nano-hexagonal boron nitride with an alkaline solution to obtain pretreated boron nitride, then by self-polymerizing tannic acid to obtain polytannic acid, and then coating the surface of the pretreated boron nitride with polytannic acid to obtain polytannic acid-modified boron nitride, which is then further prepared by ring-opening reaction with isopropyl glycidyl ether.

2. The modified epoxy resin encapsulation material according to claim 1, characterized in that, The resin matrix is ​​prepared by the following steps: Step A1: Under nitrogen protection, 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid and pentaerythritol are added to anhydrous DMF, heated to 62-64℃, stirred until homogeneous, then heated to 130-140℃, and stirred for 3.4-4.6 h. The mixture is then rotary evaporated, washed, and dried to obtain the mercapto monomer. Step A2: Mix mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane and p-toluenesulfonic acid, heat to 126-140℃, stir under nitrogen protection for 2.2-2.8h, then react under reduced pressure for 1.6-2h. Then add mercapto monomer and p-toluenesulfonic acid again, stir for 3-3.4h, react under reduced pressure for 2.6-2.8h, and cool to room temperature to obtain the hydroxyl-terminated hyperbranched polymer. Step A3: Add the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin and benzyltriethylammonium chloride to a mixed solvent, heat to 90-100℃, stir and react for 2.2-2.6h, cool to room temperature, and then add ethyl acetate to obtain the resin matrix.

3. The modified epoxy resin encapsulation material according to claim 2, characterized in that, In step A1, the mass ratio of 2-mercapto-1,4-phthalic acid, trifluoromethanesulfonic acid, pentaerythritol and anhydrous DMF is 1:0.03-0.05:0.82-0.9:35-45.

4. The modified epoxy resin encapsulation material according to claim 2, characterized in that, In step A2, the mass ratio of mercapto monomer, hydroxypropyl-terminated polydimethylsiloxane and p-toluenesulfonic acid is 3.2-4.4:1-1.4:0.02-0.

04.

5. The modified epoxy resin encapsulation material according to claim 2, characterized in that, In step A3, the mass ratio of the hydroxyl-terminated hyperbranched polymer, bisphenol A type epoxy resin, benzyltriethylammonium chloride, mixed solvent and ethyl acetate is 1-2:4.6-5.2:0.2-0.4:16-20:14-18, and the mixed solvent includes xylene and cyclohexanone in a mass ratio of 2-3:

1.

6. The modified epoxy resin encapsulation material according to claim 1, characterized in that, The thermally conductive filler is prepared by the following steps: Step B1: Under nitrogen protection, nano-hexagonal boron nitride is added to an alkaline solution, heated to 78-82℃, stirred for 72-80 h, precipitated, washed, and dried to obtain pretreated boron nitride. Step B2: Add tannic acid to an ethanol aqueous solution, stir evenly, adjust the pH to 7.0-7.4, then add pretreated boron nitride solution and ammonium persulfate aqueous solution, heat to 76-84℃, stir the reaction for 0.6-0.8h, filter, wash, and dry to obtain polytannic acid modified boron nitride. Step B3: Add polytannic acid-modified boron nitride to anhydrous DMF, heat to 45-55℃, stir evenly, adjust pH to 8.1-8.5, and while stirring, dropwise add a mixture of isopropyl glycidyl ether, tetrabutylammonium bromide and isopropanol b, heat to 76-82℃, continue stirring for 8-12 hours, adjust pH to neutral, rotary evaporate, wash and dry to obtain thermally conductive filler.

7. The modified epoxy resin encapsulation material according to claim 6, characterized in that, In step B1, the mass ratio of nano-hexagonal boron nitride to alkaline solution is 3-5:550-650.

8. The modified epoxy resin encapsulation material according to claim 6, characterized in that, In step B2, the mass ratio of tannic acid, ethanol aqueous solution, pretreated boron nitride solution and ammonium persulfate aqueous solution is 2-3:40-50:18-22:8-10.

9. A modified epoxy resin encapsulation material according to claim 6, characterized in that, In step B3, the mass ratio of polytannic acid-modified boron nitride, anhydrous DMF, and mixture b is 4-6:70-80:30-40. In mixture b, the mass ratio of isopropyl glycidyl ether, tetrabutylammonium bromide, and isopropanol is 2.6-3.4:0.08-0.12:22-26.

10. A method for preparing a modified epoxy resin encapsulating material as described in any one of claims 1-9, characterized in that, Includes the following steps: Add the resin matrix, thermally conductive filler, composite flame retardant and photoinitiator to the solvent, stir evenly, heat to 76-80℃, and irradiate with ultraviolet light while stirring for 18-22 minutes. Then add the curing accelerator, heat to 90-100℃, continue stirring for 32-46 minutes, and then evaporate by rotary evaporation to obtain the modified epoxy resin encapsulation material.

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