Preparation process of modified spherical alumina for high-filled epoxy plastic packaging material

Abstract

The application discloses a modified spherical alumina preparation process for high-filled epoxy plastic packaging materials and belongs to the technical field of electronic packaging materials. The process adopts fluorine-containing bis-epoxy triazole silane coupling agent to perform surface modification on graded spherical alumina, the coupling agent molecule simultaneously contains trialkoxy silane groups, bis-epoxy groups, fluorine-containing carbon chain segments and 1,2,3-triazole ring structures, and can form a chemical bonding multifunctional interface bridging layer between the alumina filler and the epoxy resin matrix. The modified spherical alumina has high activation index and hydrophobic properties, is filled in the epoxy resin matrix at a high proportion, is uniformly mixed with curing agents, accelerators, release agents and other additives, and can be used for preparing epoxy plastic packaging materials with high thermal conductivity, excellent fluidity, high mechanical strength and good moisture resistance, and is suitable for electronic packaging of semiconductor discrete devices, integrated circuits and power devices.

Description

Technical Field

[0001] This invention belongs to the field of electronic packaging materials technology, specifically relating to a process for preparing modified spherical alumina for high-filler epoxy molding compounds. Background Technology

[0002] Semiconductor devices are rapidly iterating towards higher integration and higher power density, making thermal management a core bottleneck determining device performance and long-term reliability. Epoxy molding compounds (EMC) are the mainstream materials for semiconductor packaging, and their thermal conductivity directly determines the device's heat dissipation efficiency and operational stability. Alumina, with its high thermal conductivity, excellent electrical insulation, chemical stability, and low cost, has become the core thermally conductive filler for EMC, significantly improving the overall heat dissipation capacity of the molding compound compared to traditional silica fillers. However, under high-filling conditions, the interfacial compatibility defects between alumina fillers and the epoxy resin matrix severely restrict the industrial application of high-end, high-thermal-conductivity EMCs.

[0003] Alumina has a surface rich in hydroxyl groups and strong hydrophilic polarity, while epoxy resin is a weakly polar or non-polar organic matrix. The significant difference in surface energy between the two leads to poor filler dispersion and agglomeration. This problem not only worsens the processing flowability of the composite material but also induces interfacial defects, forming stress concentration points and crack initiation points, reducing product reliability. Simultaneously, the significantly increased interfacial area in highly filled systems exacerbates the phonon spectrum mismatch between inorganic fillers and organic resins, resulting in a sharp increase in interfacial thermal resistance. This becomes a major barrier to heat transfer, causing the actual thermal conductivity of the composite material to be far lower than theoretically expected.

[0004] Traditional silane coupling agent modification can only slightly improve filler dispersibility. Their simple molecular structure and limited function fail to meet the diverse requirements of high-filler systems for low viscosity, high flowability, strong interfacial bonding, and low coefficient of thermal expansion. In particular, spherical alumina fillers, while improving thermal conductivity, significantly reduce material flexural strength. Furthermore, upgrades in system-in-package (SiP) and power device packaging technologies place higher demands on EMC thermal conductivity, requiring further increases in filler loading. However, this exacerbates interfacial defects, leading to continuous deterioration of material processing and mechanical properties. Therefore, achieving high filler loading while simultaneously maintaining material flowability, mechanical strength, and reliability remains a critical technical challenge in the EMC field. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides a process for preparing modified spherical alumina for high-filler epoxy molding compounds. This invention designs and synthesizes a fluorinated bis(epoxy)triazole silane coupling agent, which is used to modify the surface of spherical alumina. The modified spherical alumina is then filled into an epoxy resin matrix in a high proportion, resulting in an epoxy molding compound with high thermal conductivity, excellent flowability, high mechanical strength, and good reliability. The technical solution to achieve the objective of this invention is as follows: A modified spherical alumina is obtained by surface modification of spherical alumina with a fluorinated diepoxytriazole silane coupling agent; the fluorinated diepoxytriazole silane coupling agent has the following structural features: a polyamine backbone with three amino groups, and three side chains respectively connected to the three amino groups of the polyamine backbone, wherein two side chains each contain a 1,2,3-triazole ring and a fluorinated glycidyl ether group, and the other side chain contains a 1,2,3-triazole ring and a trialkoxysilyl group.

[0006] The spherical alumina is composed of three particle sizes: coarse, medium, and fine. The D50 of the coarse-sized spherical alumina is 20-30 μm, the D50 of the medium-sized spherical alumina is 5-10 μm, and the D50 of the fine-sized spherical alumina is 1-3 μm. In the fluorinated bis(epoxy)triazole silane coupling agent, the polyamine skeleton is selected from one or two of tri(2-aminoethyl)amine and tri(3-aminopropyl)amine; the trialkoxysilyl group is selected from one or two of trimethoxysilyl and triethoxysilyl; the trimethoxysilyl and triethoxysilyl groups are sourced from one or two of 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane.

[0007] The fluorinated glycidyl ether group is obtained by esterification of a fluorinated diol with an azide carboxylic acid and then etherification with epichlorohydrin; the fluorinated diol is selected from one or two of 2,2,3,3,4,4,5,5-octafluorohexane-1,6-diol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecanooctane-1,8-diol; the azide carboxylic acid is selected from one or more of 2-azidoacetic acid, 3-azidopropionic acid and 4-azidobutyric acid.

[0008] The amount of the fluorinated diepoxytriazole silane coupling agent is 1.5% to 3.5% of the weight of the spherical alumina.

[0009] The preparation method of the fluorinated diepoxytriazole silane coupling agent includes the following steps: a) Reaction of polyamines with benzyl chloroformate yields a partially protected amine intermediate; b) React the partially protected amine intermediate with a propargylating agent to introduce a propargyl group; c) A propyl-containing intermediate is reacted with an amino-containing azide compound via a click chemistry reaction to form a 1,2,3-triazole ring; d) The intermediate containing the 1,2,3-triazole ring is reacted with an epoxy-containing silane coupling agent to obtain a coupling agent precursor containing a trialkoxysilane and a 1,2,3-triazole ring; e) Remove the protecting group to obtain an intermediate containing two free primary amines, a 1,2,3-triazole ring and a trialkoxysilyl group; f) The intermediate is reacted with a propargylating agent to introduce a dipropargyl group; g) A fluorinated diepoxytriazole silane coupling agent is obtained by reacting a dipropynyl intermediate with a fluorinated glycidyl ether azide compound via a click chemistry reaction.

[0010] Specifically, the click chemistry reactions described in steps c) and g) are carried out in a catalytic system with an amount equivalent to 0.2-0.5 eq of cuprous iodide and an amount equivalent to 0.4-1.0 eq of N,N,N',N'',N''-pentamethyldiethylenetriamine, at a reaction temperature of 20°C-30°C; the deprotection described in step e) is carried out by catalytic hydrogenolysis, with palladium on carbon as the catalyst, a hydrogen pressure of 0.1 MPa-0.2 MPa, a reaction temperature of 20°C-30°C, and a reaction time of 4-8 h.

[0011] Specifically, since 3-azidopropyl-1-amine contains a free primary amine group, which can coordinate with the Cu(I) catalyst to reduce its catalytic activity, the amount of catalyst used in step c) needs to be increased appropriately and the reaction time extended.

[0012] A method for preparing modified spherical alumina includes the following steps: (1) Disperse graded spherical alumina in an alcohol-water mixed solvent and ultrasonically disperse for 30-90 min to obtain a uniform suspension; (2) Add a fluorinated diepoxytriazole silane coupling agent to the suspension, adjust the pH to 5-6, raise the temperature to 60℃-80℃ under nitrogen protection, and stir for 4-6 hours. (3) After the reaction is complete, filter the mixture and wash the filter cake 2 to 4 times with anhydrous ethanol; (4) Place the washed filter cake in a vacuum drying oven and dry it for 4h~8h at 100℃~130℃ and absolute pressure ≤0.01MPa to obtain modified spherical alumina.

[0013] The modification reaction conditions in step (2) are mild. By controlling the pH at 5 to 6 and using an alcohol-water mixed solvent, the epoxy groups in the coupling agent molecule undergo only a very small amount of ring opening under these conditions, which does not affect the subsequent chemical bonding with the resin matrix.

[0014] A highly filled epoxy molding compound, by weight, comprises 80-90 parts modified spherical alumina, 5-12 parts epoxy resin, 2-6 parts phenolic curing agent, 0.1-0.5 parts accelerator, 0.1-0.6 parts release agent, and 0.1-0.4 parts colorant.

[0015] Specifically, the epoxy resin is selected from one or more of o-cresol epoxy resin, bisphenol A type epoxy resin, naphthyl ring type epoxy resin, biphenyl type epoxy resin, and phosphorus-containing epoxy resin; the epoxy equivalent of the epoxy resin is 150~250 g / eq; the phenolic curing agent is selected from one or more of linear phenolic resin, o-cresol resin, bisphenol A phenolic resin, and naphthyl phenolic resin; the hydroxyl equivalent of the phenolic curing agent is 100~130 g / eq; the accelerator is selected from one or more of triphenylphosphine, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, triethanolamine, and benzyl dimethylamine; the release agent is selected from one or more of carnauba wax, polyethylene wax, oxidized polyethylene wax, zinc stearate, and silicone release agent; and the colorant is selected from one or more of carbon black, titanium dioxide, iron oxide red, phthalocyanine blue, and phthalocyanine green.

[0016] A method for preparing a high-filler epoxy molding compound includes the following steps: S1. Add epoxy resin, phenolic curing agent, mold release agent and colorant into a mixer, control the temperature at 80℃~100℃, the rotor speed at 20~40rpm, and mix for 5~8 minutes until uniform. S2. Add the modified spherical alumina in 2 to 4 portions, and mix for 5 to 8 minutes after each addition. Add the accelerator before the last addition of filler, and continue mixing for 3 to 5 minutes until uniform to obtain the mixture. S3. Cool the mixture to room temperature, crush and sieve to obtain a high-filler epoxy molding compound premix; S4. Add the premixed material into the barrel of the transfer molding machine, control the mold temperature to 170℃~180℃, the injection pressure to 6MPa~10MPa, and the curing time to 80s~120s, and perform transfer molding. S5. Place the molded part in an oven at 170℃~180℃ and cure for 2h~4h to obtain a high-filled epoxy molding compound product.

[0017] The fluorinated bis(epoxy)triazole silane coupling agent designed in this invention is a multifunctional interface bridging molecule whose mechanism of action covers multiple levels, including chemical bonding, physical adsorption, and interface structure regulation.

[0018] Regarding anchoring on the packing surface, the trialkoxysilane group in the coupling agent molecule undergoes hydrolysis under acidic aqueous solution conditions to generate silanol groups. The silanol groups undergo dehydration condensation reaction with the hydroxyl groups on the surface of spherical alumina to form stable Si-O-Al covalent bonds, thereby firmly anchoring the coupling agent molecule to the surface of the alumina packing.

[0019] Regarding the bonding with the resin matrix, the coupling agent molecule contains two epoxy groups at its terminal. These epoxy groups can undergo ring-opening addition reactions with the epoxy resin curing agent during the molding compound curing process, forming part of a three-dimensional cross-linked network. In this way, a strong chemical bridge is established between the inorganic filler and the organic resin matrix.

[0020] In terms of interface structure regulation, the fluorocarbon segments in the coupling agent molecules possess extremely low surface energy and excellent hydrophobic properties, effectively reducing the interfacial tension between the filler and the resin matrix and improving the wettability and dispersibility of the filler in the resin. Simultaneously, the low polarizability of the fluorocarbon segments helps reduce the dielectric constant of the composite material, while their low surface energy helps form an ordered hydrophobic layer in the interfacial region, alleviating interfacial stress caused by the difference in resin curing shrinkage and thermal expansion coefficients.

[0021] The 1,2,3-triazole ring structure serves as the core linking skeleton of the coupling agent molecule, exhibiting excellent chemical and thermal stability. The nitrogen atom in the 1,2,3-triazole ring can provide coordination, forming secondary interactions with metal ions or polar groups, further enhancing interfacial bonding.

[0022] In summary, this invention achieves the synergistic effect of silane anchoring, epoxy bonding, fluorocarbon hydrophobicity, and triazole reinforcement through molecular structure design, constructing a multifunctional and highly efficient interfacial bridging layer between the alumina filler and the epoxy resin matrix. This fundamentally solves the technical problems of poor interfacial compatibility, insufficient flowability, and deterioration of mechanical properties in highly filled systems.

[0023] Beneficial effects

[0024] Compared with the prior art, the present invention has the following beneficial effects: First, it significantly improves the interfacial compatibility between the filler and the resin. The fluorinated bisepoxytriazole silane coupling agent connects the inorganic filler and the organic resin simultaneously through chemical bonding, forming a stable chemical bridge in the interfacial region. This greatly reduces the interfacial thermal resistance and mechanical weaknesses, making the composite material exhibit higher reliability when subjected to external forces or thermal shocks.

[0025] Secondly, it effectively improves the processing fluidity of high-filler systems. The low surface energy of fluorocarbon segments reduces the friction and interfacial tension between the filler and the resin, allowing high-filler epoxy molding compounds to maintain good melt flow during transfer molding. This facilitates the complete filling of complex-shaped encapsulated devices and reduces molding defects such as underfill and porosity.

[0026] Third, a balance between thermal conductivity and mechanical properties is achieved. The modified filler of this invention improves the thermal conductivity of the composite material while maintaining high flexural strength and impact strength, overcoming the technical defect of traditional high thermal conductivity alumina fillers that cause a significant decrease in flexural strength, and meeting the stringent requirements of advanced packaging for the comprehensive performance of materials.

[0027] Fourth, it improves the moisture resistance and electrical reliability of packaged devices. The hydrophobic properties of the fluorocarbon segments reduce the material's water absorption rate, thereby reducing the risk of metal interconnect corrosion and electrical performance degradation caused by moisture penetration. This helps improve the long-term operational reliability of packaged devices in humid and high-temperature environments.

[0028] Fifth, it reduces the dielectric constant and dielectric loss. Fluorine has a low electronic polarizability, and the introduction of fluorine-containing coupling agents helps to reduce the dielectric constant of composite materials, thereby reducing signal transmission delay and crosstalk, making it suitable for packaging applications of high-frequency and high-speed electronic devices. Attached Figure Description

[0029] Figure 1 This is a synthetic route diagram for fluorinated glycidyl ether azidopropionate 1.

[0030] Figure 2 The synthetic route diagram is for fluorinated bis(epoxy)triazole silane coupling agent 1.

[0031] Figure 3 The image shows the 1H NMR spectrum of fluorinated diepoxytriazole silane coupling agent 1. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0034] The raw materials and equipment used in the examples and comparative examples are described below, where eq represents equivalent: Spherical alumina: Selected from Ji'an Yushun, composed of the following three gradations: coarse-grained spherical alumina, D... 50 =20~30μm; medium-sized spherical alumina, D 50 =5~10 μm; fine-grained spherical alumina, D 50 =3 μm = 1~3 μm.

[0035] o-Cresol-formaldehyde epoxy resin: epoxy equivalent 200~220g / eq, commercially available.

[0036] Linear phenolic resin: hydroxyl equivalent 105~120g / eq, commercially available.

[0037] Palladium on carbon: Palladium content 10wt%, commercially available.

[0038] Fluorinated glycidyl ether azidopropionate 1: Prepared in-house, as follows: 5.0 eq of 2,2,3,3,4,4,5,5-octafluorohexane-1,6-diol and 1.0 eq of 3-azidopropionic acid were dissolved in dichloromethane. 1.2 eq of N,N-dicyclohexylcarbodiimide and 0.1 eq of 4-dimethylaminopyridine were added, and the mixture was stirred at room temperature for 12 h. N,N-dicyclohexylurea was removed by filtration. The reaction product was a mixture of monoester, diester, and unreacted diol. The filtrate was filtered through a short silica gel column and purified by silica gel column chromatography to obtain 2,2,3,3,4,4,5,5-octafluoro-6-hydroxyhexyl-3-azido. Propionate: 1.0 eq of the above-mentioned 2,2,3,3,4,4,5,5-octafluoro-6-hydroxyhexyl-3-azidopropionate and 3.0 eq of epichlorohydrin were dissolved in anhydrous N,N-dimethylformamide. Under nitrogen protection, 2.5 eq of anhydrous potassium carbonate was added, the temperature was raised to 70°C, and the reaction was stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the potassium carbonate was removed by filtration. The filtrate was diluted with ethyl acetate, washed three times with saturated brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and the residue was purified by column chromatography to obtain fluorinated glycidyl ether azidopropionate 1.

[0039] Preparation Example Preparation Example 1 Fluorinated diepoxytriazole silane coupling agent 1: self-made, preparation method as follows: 1.0 eq of tris(2-aminoethyl)amine was dissolved in dichloromethane, and 3.0 eq of triethylamine was added. The mixture was cooled to 0°C, and 2.0 eq of benzyl chloroformate was added dropwise. The reaction was carried out at 0°C for 2 h, then at 25°C for 4 h. The precipitate was removed by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain a dibenzyloxycarbonyl protected intermediate. 1.0 eq of the dibenzyloxycarbonyl protected intermediate was dissolved in acetonitrile, and 2.0 eq of potassium carbonate was added. The mixture was cooled to 0–5°C under nitrogen protection. 1.1 eq of 3-bromopropyne was dissolved in a small amount of anhydrous acetonitrile and slowly added dropwise. After the addition was complete, the mixture was reacted at 0–5°C for 12 h. The mixture was filtered, concentrated under reduced pressure, and the residue was purified by column chromatography to obtain a monopropynyl biprotected intermediate. 1.0 eq of the monopropynyl biprotected intermediate was reacted with 3… 1.2 eq of azidopropyl-1-amine was dissolved in anhydrous N,N-dimethylformamide, and 0.5 eq of cuprous iodide and 1.0 eq of N,N,N',N'',N''-pentamethyldiethylenetriamine were added. The mixture was reacted at 25 °C for 24 h under nitrogen protection. The solution was diluted with ethyl acetate, filtered through a neutral alumina short column, and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography to obtain a monotriazole dual-protected intermediate. 1.0 eq of the above monotriazole dual-protected intermediate and 1.0 eq of 3-glycidyl etheroxypropyltrimethoxysilane were dissolved in anhydrous toluene and reacted at 45 °C for 12 h. Thin-layer chromatography was used to monitor the reaction until the starting material spot disappeared. The mixture was concentrated under reduced pressure below 30 °C, and the residue was purified by neutral alumina column chromatography to separate the triane-containing intermediate. Trialkoxysilyl monotriazole double-protected intermediate: 1.0 eq of the above-mentioned trialkoxysilyl monotriazole double-protected intermediate was dissolved in anhydrous tetrahydrofuran, and palladium on carbon was added at a total mass of 10 wt% of the trialkoxysilyl monotriazole double-protected intermediate. After three hydrogen purgings, the reaction was carried out at 25°C for 6 h under 1 atm hydrogen. After nitrogen purging, the palladium on carbon was removed by filtration. The filtrate was concentrated under reduced pressure below 30°C to obtain a trialkoxysilyl monotriazole intermediate containing two free primary amines. 1.0 eq of the above-mentioned trialkoxysilyl monotriazole intermediate containing two free primary amines was dissolved in anhydrous acetonitrile, and 3.0 eq of potassium carbonate was added. The mixture was cooled to 0-5°C under nitrogen protection. 2.2 eq of 3-bromopropyne was dissolved in a small amount of anhydrous acetonitrile and slowly added dropwise. After the addition was complete, the mixture was further dissolved in anhydrous acetonitrile. The reaction was carried out at 0-5℃ for 12 h, filtered, and concentrated under reduced pressure below 30℃. The residue was purified by neutral alumina column chromatography to obtain a diacetyltrialkyl triazole intermediate containing trialkoxysilane. 1.0 eq of the diacetyltrialkyltriazole intermediate containing trialkoxysilane and 2.2 eq of fluorinated glycidyl ether azidopropionate were dissolved in anhydrous N,N-dimethylformamide. 0.2 eq of cuprous iodide and 0.4 eq of N,N,N',N'',N''-pentamethyldiethylenetriamine were added, and the reaction was carried out at 25℃ for 8 h under nitrogen protection. The mixture was diluted with ethyl acetate, filtered through a short neutral alumina column, and the filtrate was concentrated under reduced pressure below 30℃. The residue was purified by neutral alumina column chromatography to obtain fluorinated diepoxytriazole silane coupling agent 1, with the structure shown below: .

[0040] It should be noted that the central nitrogen atom of tris(2-aminoethyl)amine is a tertiary amine, which exhibits a certain degree of nucleophilicity under alkaline conditions and may undergo a quaternization side reaction with 3-bromopropyne. By controlling the reaction temperature at 0–5 °C, slowly adding 3-bromopropyne over a period of at least 30 min, and controlling the amount of 3-bromopropyne to be 1.0–1.2 equivalents of the primary amine amino group, the selective N-alkylation of the primary amine can be preferentially carried out. The quaternary ammonium salt byproduct can then be effectively separated and removed by neutral alumina column chromatography.

[0041] Preparation Example 2 Trisilane polyhydroxyamine coupling agent 2: self-made, preparation method as follows: 1.0 eq of tris(2-aminoethyl)amine was dissolved in anhydrous toluene and cooled to 0°C under nitrogen protection. 3.0 eq of 3-glycidyl etheroxypropyltrimethoxysilane was dissolved in anhydrous toluene and slowly added dropwise. After the addition was complete, the temperature was naturally raised to 25°C and reacted for 4 h. The temperature was then raised to 40°C and reacted for 2 h. Thin-layer chromatography was used to monitor the reaction until the spot on the starting material disappeared. The solvent was removed by concentration under reduced pressure below 30°C. The residue was purified by neutral alumina column chromatography to obtain trisilane polyhydroxyamine coupling agent 2.

[0042] Preparation Example 3 Fluorinated tricyclic triazole compound 3: prepared in-house, the preparation method is as follows: 1.0 eq of tris(2-aminoethyl)amine was dissolved in acetonitrile, and 3.0 eq of potassium carbonate was added. The mixture was cooled to 0°C under nitrogen protection. 3.0 eq of 3-bromopropyne was dissolved in anhydrous acetonitrile and slowly added dropwise. After the addition was complete, the mixture was reacted at 0°C for 6 h, and then naturally raised to 25°C for 2 h. The mixture was filtered, concentrated under reduced pressure, and the residue was purified by column chromatography to obtain a triargylpropylamine intermediate. 1.0 eq of the above triargylpropylamine intermediate and 13.3 eq of fluorinated glycidyl ether azidopropionate were dissolved in anhydrous N,N-dimethylformamide, and 0.2 eq of cuprous iodide and 0.4 eq of N,N,N',N'',N''-pentamethyldiethylenetriamine were added. The mixture was reacted at 25°C for 16 h under nitrogen protection. The mixture was diluted with ethyl acetate, filtered through a neutral alumina short column, and the filtrate was concentrated under reduced pressure below 30°C. The residue was purified by neutral alumina column chromatography to obtain a fluorinated tricyclic triazole compound 3.

[0043] Examples and Comparative Examples Example 1

[0044] Modified spherical alumina 1: self-made, preparation method is as follows: 85 parts by weight of spherical alumina, with a particle size distribution of 45 parts coarse, 30 parts medium, and 10 parts fine, were added to a mixed solvent of 380 parts by weight of anhydrous ethanol and 20 parts by weight of deionized water and ultrasonically dispersed for 60 min. 2.5 parts by weight of fluorinated bis(epoxy)triazole silane coupling agent 1 were added, the pH was adjusted to 5 with glacial acetic acid, the temperature was raised to 70℃, and the reaction was stirred for 5 h under nitrogen protection. After the reaction was completed, the mixture was filtered, and the filter cake was washed three times with anhydrous ethanol. The washed filter cake was placed in a vacuum drying oven and dried for 6 h at 120℃ and an absolute pressure ≤0.01 MPa to obtain modified spherical alumina 1.

[0045] Example 2

[0046] Modified spherical alumina 2: prepared in-house. The preparation method is the same as that of modified spherical alumina 1, except that the fluorinated diepoxytriazole silane coupling agent 1 is replaced with 1.5 parts, while other conditions remain unchanged, to obtain modified spherical alumina 2.

[0047] Example 3

[0048] Modified spherical alumina 3: prepared in-house. The preparation method is the same as that of modified spherical alumina 1, except that the fluorinated diepoxytriazole silane coupling agent 1 is replaced with 2.9 parts, while other conditions remain unchanged, thus obtaining modified spherical alumina 3.

[0049] Comparative Example 1 Modified spherical alumina 4: self-made. The preparation method is the same as that of modified spherical alumina 1, except that the fluorinated bis(epoxytriazole)silane coupling agent 1 is replaced with trisilane polyhydroxyamine coupling agent 2, while other conditions remain unchanged, thus obtaining modified spherical alumina 4.

[0050] Comparative Example 2 Modified spherical alumina 5: prepared in-house. The preparation method is the same as that of modified spherical alumina 1, except that the fluorinated bicyclic triazole silane coupling agent 1 is replaced with the fluorinated tricyclic triazole compound 3, while other conditions remain unchanged, thus obtaining modified spherical alumina 5.

[0051] Comparative Example 3 Modified spherical alumina 6: prepared in-house. The preparation method is the same as that of modified spherical alumina 1, except that the fluorinated diepoxytriazole silane coupling agent 1 is replaced with 3-glycidyl etheroxypropyltrimethoxysilane, while other conditions remain unchanged, to obtain modified spherical alumina 6.

[0052] Application examples Application Example 1 High-filler epoxy molding compound 1: Self-made, preparation method as follows: Eight parts by weight of o-cresol epoxy resin, four parts by weight of linear phenolic resin, 0.3 parts by weight of carnauba wax, and 0.2 parts by weight of carbon black were added to a mixer. The temperature was controlled at 90°C and the rotor speed at 30 rpm. The mixture was mixed for 6 minutes until homogeneous. Eighty-seven parts by weight of modified spherical alumina 1 were added in three batches, and the mixture was mixed for 6 minutes after each addition. After the second addition of filler, 0.2 parts by weight of triphenylphosphine were added and the mixture was mixed for 4 minutes until homogeneous to obtain a homogeneous compound. The compound was cooled to room temperature and pulverized through a 40-mesh sieve to obtain a high-filled epoxy molding compound premix. The premix was added to the barrel of a transfer molding machine. The mold temperature was controlled at 175°C, the injection pressure at 8 MPa, and the curing time at 90 s for transfer molding. The molded part was placed in a 175°C oven and cured for 3 hours to obtain the high-filled epoxy molding compound 1.

[0053] Application Example 2 High-filler epoxy molding compound 2: self-made. The preparation method is the same as that of high-filler epoxy molding compound 1, except that the modified spherical alumina 1 is replaced with 90 parts, o-cresol epoxy resin is replaced with 6 parts, linear phenolic resin is replaced with 3 parts, triphenylphosphine is replaced with 0.1 parts, carnauba wax is replaced with 0.2 parts, and carbon black is replaced with 0.1 parts. All other conditions remain unchanged to obtain high-filler epoxy molding compound 2.

[0054] Application Example 3 High-filler epoxy molding compound 3: self-made. The preparation method is the same as that of high-filler epoxy molding compound 1, except that the modified spherical alumina 1 is replaced with 83 parts, o-cresol epoxy resin is replaced with 10 parts, linear phenolic resin is replaced with 5 parts, triphenylphosphine is replaced with 0.3 parts, carnauba wax is replaced with 0.5 parts, and carbon black is replaced with 0.3 parts. All other conditions remain unchanged to obtain high-filler epoxy molding compound 3.

[0055] Application Example 4 High-filled epoxy molding compound 4: self-made. The preparation method is the same as that of high-filled epoxy molding compound 1, except that modified spherical alumina 1 is replaced with modified spherical alumina 2, and other conditions remain unchanged, thus obtaining high-filled epoxy molding compound 4.

[0056] Application Example 5 High-filled epoxy molding compound 5: self-made. The preparation method is the same as that of high-filled epoxy molding compound 1, except that modified spherical alumina 1 is replaced with modified spherical alumina 3, and other conditions remain unchanged, thus obtaining high-filled epoxy molding compound 5.

[0057] Comparative Application Example 1 High-filler epoxy molding compound 6: self-made. The preparation method is the same as that of high-filler epoxy molding compound 1, except that modified spherical alumina 1 is replaced with modified spherical alumina 4, while other conditions remain unchanged, to obtain high-filler epoxy molding compound 6.

[0058] Comparative Application Example 2 High-filler epoxy molding compound 7: self-made. The preparation method is the same as that of high-filler epoxy molding compound 1, except that modified spherical alumina 1 is replaced with modified spherical alumina 5, and other conditions remain unchanged, thus obtaining high-filler epoxy molding compound 7.

[0059] Comparative Application Example 3 High-filler epoxy molding compound 8: self-made. The preparation method is the same as that of high-filler epoxy molding compound 1, except that modified spherical alumina 1 is replaced with modified spherical alumina 6, and other conditions remain unchanged, thus obtaining high-filler epoxy molding compound 8.

[0060] The following are the test methods for performance parameters involved in this invention: 1. Nuclear magnetic resonance hydrogen spectrum test: Characterization was performed using a nuclear magnetic resonance spectrometer (Bruker Avance III HD600, 600MHz).

[0061] 2. Activation Index Test: The activation index of the modified spherical alumina was determined by flotation. A certain amount of the modified spherical alumina sample was weighed and placed in a beaker containing deionized water. After thorough stirring, it was allowed to stand for 2 hours. The powder floating on the water surface was collected, dried, and weighed. The activation index is expressed as a percentage of the mass of the floating portion to the total mass, accurate to 0.1%. This index reflects the degree of hydrophobicity of the powder after surface modification. The test results are shown in Table 1.

[0062] 3. Contact Angle Test: The sample preparation requirements were followed according to GB / T30447-2013 "Measurement of Contact Angle of Nanopowders," and the determination was conducted according to GB / T30693-2014 "Measurement of Contact Angle between Plastic Films and Water." The modified spherical alumina powder was pressed into a flat thin sheet using the seated drop method. The static contact angle of deionized water on the surface was measured using a contact angle meter. The droplet volume was 2 μL. Five measurements were taken at five different locations for each sample, and the average value was recorded. The results are expressed in degrees, accurate to 1°. The test results are shown in Table 1.

[0063] 4. Gelation Time Test: The gelation time was determined according to Section 6.1 of GB / T40564-2021 "Test Methods for Epoxy Molding Compounds for Electronic Packaging". The hot plate method was used. The epoxy molding compound powder to be tested was placed on a hot plate at a set temperature (175℃±2℃), and continuously stirred with a stainless steel scraper. The time required from the start of melting to the breakage of the fibers was recorded; this is the gelation time. The results are expressed in seconds, accurate to 1 second. The test results are shown in Table 2.

[0064] 5. Spiral Flow Length Test: The test was conducted according to Section 6.2 of GB / T40564-2021. Using a spiral flow mold, the length of the epoxy sealant flowing in the spiral groove was measured under the conditions of mold temperature 175℃±2℃, injection pressure 7.0MPa±0.5MPa, and curing time 90s. The results are expressed in centimeters, accurate to 0.1cm.

[0065] 6. Glass transition temperature test: The glass transition temperature was determined according to Section 6.8 of GB / T40564-2021 and GB / T19466.2-2004 "Differential scanning calorimetry (DSC) for plastics - Part 2: Determination of glass transition temperature". A differential scanning calorimeter (DSC) was used under a nitrogen atmosphere, with a heating rate of 10℃ / min and a temperature range of 25℃~250℃. The midpoint of the step change in the two-stage heating curve was taken as the glass transition temperature. The results are expressed in degrees Celsius, accurate to 1℃.

[0066] 7. Thermal conductivity test: The test shall be conducted in accordance with Section 6.6 of GB / T40564-2021 and ASTM D5470. The steady-state heat flow method shall be used. A cured circular sample (25 mm in diameter, 3 mm to 5 mm in thickness) shall be placed between a hot plate and a cold plate, and a constant heat flow and pressure shall be applied. The temperature difference between the two sides of the sample under steady-state conditions shall be measured, and the thermal conductivity shall be calculated. The results shall be expressed in W / (m·K), accurate to 0.01 W / (m·K).

[0067] 8. Water Absorption Test: The test shall be conducted in accordance with Section 6.10 of GB / T40564-2021. After the cured epoxy molding compound sample (50mm×50mm×3mm) is immersed in boiling water for 24 hours, it shall be removed, the surface moisture wiped dry, and immediately weighed. The percentage increase in mass shall be calculated. The result shall be expressed as a percentage, accurate to 0.01%. This method is applicable to finished epoxy molding compounds after molding and curing, but not to unformed powder or filler raw materials.

[0068] 9. Flame retardancy test: A vertical burning test shall be conducted in accordance with the provisions of Section 6.11 of GB / T40564-2021 and UL94 "Test for flammability of plastic materials for equipment and appliance components". The sample size is 125mm×13mm×3mm. The burning time and dripping pattern after 10s of flame application shall be recorded twice to evaluate the flame retardancy rating.

[0069] 10. Bending Strength Test: The test was conducted according to Section 7.1 of GB / T40564-2021 and GB / T9341-2008 "Test Method for Bending Properties of Plastics". The three-point bending method was used, with a sample size of 80mm × 10mm × 4mm, a span of 64mm, a loading speed of 2.0mm / min, and a test temperature of 23℃ ± 2℃. Results are expressed in megapascals (MPa), accurate to 1 MPa.

[0070] 11. Impact Strength Test: Unnotched impact tests were conducted according to Section 7.2 of GB / T40564-2021 and GB / T1043.1-2008 "Determination of Impact Properties of Simply Supported Plastic Beams". The specimen size was 80mm × 10mm × 4mm, the pendulum energy was 4J, and the test temperature was 23℃ ± 2℃. Results are expressed in kilojoules per square meter, accurate to 0.1kJ / m². 2 .

[0071] 12. Dielectric constant and dielectric loss factor test: The test shall be conducted in accordance with the provisions of Section 8.2 of GB / T40564-2021. A dielectric spectrometer shall be used, with a test frequency of 1MHz and a test temperature of 23℃±2℃. The results are expressed as dielectric constant (accurate to 0.01) and dielectric loss factor (accurate to 0.001), respectively.

[0072] Table 1 Performance test results of the examples and comparative examples

[0073] Table 2 Performance test results of application examples and comparative application examples

[0074] To verify the modification effect of the fluorinated bis(epoxy)triazole silane coupling agent, multiple sets of examples and comparative examples were conducted. In the surface modification test of spherical alumina, Example 1 used a medium amount of coupling agent, which effectively coated the filler, giving the material excellent activation index and hydrophobic properties. Example 3, with an appropriate increase in the amount of coupling agent, showed the best modification effect, while Example 2, with a reduced amount, showed a decrease in modification effect. Comparative Example 1, lacking fluorocarbon segments, and Comparative Example 2, lacking the trialkoxysilane group, respectively had problems with poor surface energy regulation and inability to form stable chemical bonds with alumina, resulting in a decrease in modification effect. Although Comparative Example 1 contained three silane groups, its large molecular weight and spherical spatial configuration led to a significant increase in the thickness of the adsorption layer on the alumina surface. According to the Langmuir adsorption model, the coverage density of macromolecules on a solid surface is inversely proportional to the molecular cross-sectional area. The three silane groups in trisilane coupling agent 2 are distributed at the three arms of the same molecule, and the molecular cross-sectional area is about 3 to 4 times that of conventional monosilane coupling agents. Therefore, the number of silane groups per unit area is actually lower than that of conventional monosilane coupling agents. In addition, trisilane coupling agent 2 contains multiple hydroxyl groups after epoxy ring opening. These hydroxyl groups have strong hydrophilicity, which partially offsets the hydrophobic effect brought about by silane anchoring, resulting in an activation index lower than that of conventional monosilane coupling agents. In contrast, the conventional coupling agent in Comparative Example 3 can only achieve basic modification, and its overall performance is inferior to that of the self-developed coupling agent.

[0075] In the application tests of high-filler epoxy molding compounds, Application Example 1, using standard modified filler, exhibited the best overall performance, combining excellent flowability, thermal conductivity, heat resistance, low water absorption, and high flame retardancy. Application Example 2, with a high filler content of 90 parts, had the highest thermal conductivity among all applications, demonstrating the positive contribution of high filler content to the thermal conductivity pathway. Application Example 3, with its filler content reduced to 83 parts, showed a corresponding decrease in thermal conductivity, but the increased resin content significantly improved its flexural strength and impact strength, reflecting a trade-off between thermal conductivity and mechanical properties. Application Examples 4 and 5, using fillers with different degrees of modification, showed differentiated performance depending on the amount of coupling agent. Comparative tests showed that coupling agents without fluorine or silane structures severely deteriorated the material's interfacial bonding ability, processing performance, mechanical properties, and moisture resistance and thermal conductivity; the overall modification effect of conventional coupling agents also had significant shortcomings. Application Example 3, with the highest resin content and lowest filler content, had the lowest dielectric constant among all applications, demonstrating the significantly lower volume-weighted effect of the matrix resin's dielectric constant compared to the alumina filler. Application Example 5, due to its highest fluorinated coupling agent content, effectively reduced the dielectric contribution of the interfacial layer due to the low polarizability of the fluorocarbon segments. Its dielectric constant was second only to Application Example 3 and significantly lower than all comparative application examples, confirming the optimizing effect of fluorinated modification on dielectric properties. Application Example 2, with its highest filler content, had the highest dielectric constant among the application examples, slightly higher than comparative application example 3, but still lower than comparative application examples 1 and 2. This indicates that the coupling agent of this invention can effectively control the increase in dielectric constant while increasing the filler content. Comparative application example 2, lacking silane anchoring groups, had the most interfacial defects due to weak coupling agent coating, resulting in the strongest Maxwell-Wagner interfacial polarization effect and the highest dielectric constant. This further demonstrates the crucial role of the trialkoxysilane anchoring group in suppressing interfacial polarization and controlling the increase in dielectric constant. All application examples and comparative application examples achieved a V-0 rating, mainly attributed to the significant dilution effect of the high filling amount of modified spherical alumina on the combustible resin matrix, and the physical flame-retardant mechanism of alumina absorbing a large amount of heat and inhibiting thermal decomposition when heated. Since the filler content in each group is relatively high, the differences in flame retardant rating are not significant. However, the application example of the fluorinated coupling agent of this invention shows better performance in terms of drip control and self-extinguishing time. In summary, this self-developed coupling agent can firmly anchor alumina filler with its trialkoxysilane groups and impart excellent hydrophobicity to the filler through its fluorocarbon segments. At the same time, its bi-epoxy groups can form chemical bonds with the resin matrix, and with the coordination reinforcement effect of the 1,2,3-triazole ring, it comprehensively improves the performance of the composite material, making the material superior to traditional modified systems in terms of flowability, thermal conductivity, mechanical strength, moisture resistance, and flame retardancy, demonstrating its unique technical advantages in the field of electronic packaging materials.

[0076] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A modified spherical alumina, characterized in that, It is obtained by surface modification of spherical alumina with a fluorinated diepoxytriazole silane coupling agent; the fluorinated diepoxytriazole silane coupling agent has the following structural features: a polyamine backbone with three amino groups, three side chains respectively connected to the three amino groups of the polyamine backbone, wherein two side chains each contain a 1,2,3-triazole ring and a fluorinated glycidyl ether group, and the other side chain contains a 1,2,3-triazole ring and a trialkoxysilyl group.

2. The modified spherical alumina as described in claim 1, characterized in that, The spherical alumina is composed of three particle sizes: coarse, medium, and fine. The D50 of the coarse-sized spherical alumina is 20-30 μm, the D50 of the medium-sized spherical alumina is 5-10 μm, and the D50 of the fine-sized spherical alumina is 1-3 μm. In the fluorinated bis(epoxy)triazole silane coupling agent, the polyamine skeleton is selected from one or two of tri(2-aminoethyl)amine and tri(3-aminopropyl)amine; the trialkoxysilyl group is selected from one or two of trimethoxysilyl and triethoxysilyl; the trimethoxysilyl and triethoxysilyl are sourced from one or two of 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane.

3. The modified spherical alumina as described in claim 1, characterized in that, The fluorinated glycidyl ether group is obtained by esterification of a fluorinated diol with an azide carboxylic acid and then etherification with epichlorohydrin; the fluorinated diol is selected from one or two of 2,2,3,3,4,4,5,5-octafluorohexane-1,6-diol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecanooctane-1,8-diol; the azide carboxylic acid is selected from one or more of 2-azidoacetic acid, 3-azidopropionic acid and 4-azidobutyric acid.

4. The modified spherical alumina as described in claim 1, characterized in that, The amount of the fluorinated diepoxytriazole silane coupling agent is 1.5% to 3.5% of the weight of the spherical alumina.

5. The modified spherical alumina as described in claim 1, characterized in that, The preparation method of the fluorinated diepoxytriazole silane coupling agent includes the following steps: a) Reaction of polyamines with benzyl chloroformate yields a partially protected amine intermediate; b) React the partially protected amine intermediate with a propargylating agent to introduce a propargyl group; c) A propyl-containing intermediate is reacted with an amino-containing azide compound via a click chemistry reaction to form a 1,2,3-triazole ring; d) The intermediate containing the 1,2,3-triazole ring is reacted with an epoxy-containing silane coupling agent to obtain a coupling agent precursor containing a trialkoxysilane and a 1,2,3-triazole ring; e) Remove the protecting group to obtain an intermediate containing two free primary amines, a 1,2,3-triazole ring and a trialkoxysilyl group; f) The intermediate is reacted with a propargylating agent to introduce a dipropargyl group; g) A fluorinated diepoxytriazole silane coupling agent is obtained by reacting a dipropynyl intermediate with a fluorinated glycidyl ether azide compound via a click chemistry reaction.

6. The modified spherical alumina as described in claim 5, characterized in that, The click chemistry reactions described in steps c) and g) are carried out in a catalytic system of cuprous iodide and N,N,N',N'',N''-pentamethyldiethylenetriamine; the deprotection described in step e) is carried out by catalytic hydrogenolysis, with palladium on carbon as the catalyst.

7. A method for preparing modified spherical alumina as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Disperse graded spherical alumina in an alcohol-water mixed solvent and ultrasonically disperse for 30-90 min to obtain a uniform suspension; (2) Add a fluorinated diepoxytriazole silane coupling agent to the suspension, adjust the pH to 5-6, raise the temperature to 60℃-80℃ under nitrogen protection, and stir the reaction for 4-6 h. (3) After the reaction is complete, filter the mixture and wash the filter cake 2 to 4 times with anhydrous ethanol; (4) The washed filter cake was placed in a vacuum drying oven and dried at 100℃~130℃ and absolute pressure ≤0.01 MPa for 4 h~8 h to obtain modified spherical alumina.

8. A high-filler epoxy molding compound, characterized in that, Based on weight, it comprises 80-90 parts of modified spherical alumina as described in any one of claims 1-6, 5-12 parts of epoxy resin, 2-6 parts of phenolic curing agent, 0.1-0.5 parts of accelerator, 0.1-0.6 parts of release agent, and 0.1-0.4 parts of colorant.

9. The high-filler epoxy molding compound as described in claim 8, characterized in that, The epoxy resin is selected from one or more of o-cresol epoxy resin, bisphenol A type epoxy resin, naphthyl ring type epoxy resin, biphenyl type epoxy resin, and phosphorus-containing epoxy resin; the epoxy equivalent of the epoxy resin is 150~250 g / eq; the phenolic curing agent is selected from one or more of linear phenolic resin, o-cresol resin, bisphenol A phenolic resin, and naphthyl phenolic resin; the hydroxyl equivalent of the phenolic curing agent is 100~130 g / eq; the accelerator is selected from one or more of triphenylphosphine, 2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, triethanolamine, and benzyl dimethylamine; the release agent is selected from one or more of carnauba wax, polyethylene wax, oxidized polyethylene wax, zinc stearate, and silicone release agent; the colorant is selected from one or more of carbon black, titanium dioxide, iron oxide red, phthalocyanine blue, and phthalocyanine green.

10. A method for preparing a high-filler epoxy molding compound as described in any one of claims 8 to 9, characterized in that, Includes the following steps: S1. Add epoxy resin, phenolic curing agent, mold release agent and colorant into a mixer, control the temperature at 80℃~100℃, the rotor speed at 20~40 rpm, and mix for 5~8 minutes until uniform; S2. Add the modified spherical alumina in 2 to 4 portions, and mix for 5 to 8 minutes after each addition. Add the accelerator before the last addition of filler, and continue mixing for 3 to 5 minutes until uniform to obtain the mixture. S3. Cool the mixture to room temperature, crush and sieve to obtain a high-filler epoxy molding compound premix; S4. Add the premixed material into the barrel of the transfer molding machine, control the mold temperature to 170℃~180℃, the injection pressure to 6 MPa~10 MPa, and the curing time to 80 s~120 s, and perform transfer molding. S5. Place the molded part in an oven at 170℃~180℃ and cure for 2 h~4 h to obtain a high-filled epoxy molding compound product.

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