An epoxy resin composite material with low dielectric constant and dielectric loss, a preparation method and application thereof

Abstract

This invention provides an epoxy resin composite material with low dielectric constant and dielectric loss, prepared from hollow microspheres and epoxy resin. The hollow microspheres are selected from nano-hollow organic microspheres or nano-hollow inorganic microspheres. The epoxy resin composite material provided by this invention can be uniformly dispersed in an epoxy resin matrix. In particular, the nano-hollow organic microspheres can still be uniformly dispersed in the matrix even when the addition amount is not less than 10%, achieving low dielectric constant and low dielectric loss in the composite material. The results show that compared with an unfilled epoxy resin matrix, the dielectric constant and dielectric loss of the prepared hollow microsphere / epoxy resin composite material are significantly reduced, with the lowest dielectric constant reaching 1.58 and the lowest dielectric loss reaching 0.013 at 1MHz.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, specifically relating to an epoxy resin composite material with low dielectric constant and dielectric loss, its preparation method, and its application. Background Technology

[0002] 5G communication uses the millimeter-wave band, which has the advantages of low latency and high propagation speed. However, it also has disadvantages such as poor penetration and high attenuation. Therefore, the dielectric properties of the propagation medium material must be as low as possible in terms of dielectric constant and dielectric loss. Existing 4G communication materials require a dielectric constant between 3.4 and 3.7, while 5G communication has a transmission rate 100 times that of 4G, resulting in a corresponding increase in signal attenuation in the transmission medium. Existing 4G communication materials cannot meet the requirements for the widespread application of 5G communication. Theoretically, the dielectric constant of the medium used in 5G communication is expected to be at least between 2.8 and 3.2, with lower being better. Currently, some low-dielectric materials used in the 5G communication field include polytetrafluoroethylene (PTFE) resin, polyimide resin, bismaleimide resin, and epoxy resin. Among them, PTFE has the lowest dielectric constant, typically around 2.0. However, PTFE has an inert surface, making it difficult to activate, and it also has poor adhesion and is expensive. (Huang A, Liu F, Cui ZX, et al. Composites Science and Technology, 2021, 214: 108980) Epoxy resins have advantages such as good adhesion, excellent thermal stability and mechanical properties, low cost and good processing performance. However, the dielectric constant of most epoxy resin materials is in the range of 3.5-5.0 (He Manjun, Chen Weixiao, Dong Xixia. Polymer Physics (Revised Edition) [M]. Shanghai: Fudan University Press, 2006: 372-392), which cannot meet the requirements of low dielectric constant for 5G communication.

[0003] Currently, there are two main methods for preparing epoxy resin materials with low dielectric constants. One method involves chemically modifying the epoxy resin system by introducing low electronic polarizability structures, such as C-C and C-Si bonds, into the epoxy resin monomer or curing agent molecular chains. This reduces the electron density of the internal chemical structure of the epoxy resin material, thereby lowering the dielectric constant. For example, using phenylsiloxane coupling agents to modify bisphenol A type epoxy resin results in dielectric constants of 4.2 and 2.8 at 1MHz for the resins before and after modification (Li C, Fan H, Tariq A, et al. ACS Sustainable Chemistry & Engineering, 2018, 6: 8856-8867). Alternatively, fluorine atoms can be introduced into the epoxy resin monomer or curing agent molecular chains. Because fluorine atoms have strong electronegativity, they can bind electrons, thereby reducing electron polarizability and thus lowering the dielectric constant of the epoxy resin. For example, a fluorine-atom-modified epoxy resin material can be prepared by chemically synthesizing anhydride-terminated imide oligomers (6FDA-ODA) and using them as epoxy resin curing agents. Compared with the unmodified material, its dielectric constant at 1 MHz decreased from 3.47 to 3.23 (Wu MH, Liu X, Zhou YB, et al. Chemical Engineering Journal, 2022, 437:135437). The raw materials used in the above method have certain toxicity and are costly, making large-scale use difficult. A second method to reduce the dielectric constant of epoxy resin materials is to introduce components with low dielectric constants, such as air with a dielectric constant of 1, into the epoxy resin matrix. For example, when epoxy resin is filled with hollow glass microspheres (HGMs) with an average particle size of 20 μm, the dielectric constants of the epoxy resin at 3 MHz before and after filling are 4.16 and 2.42, respectively, when the volume percentage of HGMs reaches 60.7% (Wu BY, Liu HB, Fu RL, et al. Journal of Alloys and Compounds, 2021, 869:159332). When epoxy resin is filled with hollow silica (H-SiO2) particles of about 50 nm, the dielectric constants of the epoxy resin at 1 MHz are measured to be 3.35 and 2.65, respectively, when the mass fraction of H-SiO2 is 10% (Zhang Cuicui, Zhou Hong, Zhu Jun. Insulating Materials, 2011, 3:44). In both of these materials, the particle size of hollow glass microspheres (HGMs) is generally in the micrometer range, which is not conducive to their use in ultra-thin, high-precision components in the 5G communication field. However, H-SiO2 particles with excessively small diameters are prone to agglomeration and are difficult to disperse due to their high surface energy. Therefore, the development of fillers used in the preparation of low-dielectric epoxy resin composites for 5G communication is still under research and exploration. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an epoxy resin composite material with low dielectric constant and dielectric loss, its preparation method and application. The epoxy resin composite material with low dielectric constant and dielectric loss provided by the present invention is uniformly dispersed in the epoxy resin matrix and has good dielectric constant and dielectric loss.

[0005] This invention provides an epoxy resin composite material with low dielectric constant and dielectric loss, which is prepared by hollow microsphere material and epoxy resin, wherein the hollow microsphere material is selected from nano-hollow organic microspheres or nano-hollow inorganic microspheres.

[0006] Preferably, the hollow microsphere material has a particle size of 200–400 nm and a wall thickness of 10–80 nm.

[0007] Preferably, the hollow microsphere material is selected from nano-hollow silica microspheres or nano-hollow polystyrene microspheres.

[0008] Preferably, the mass fraction of the nano-hollow silica microspheres in the epoxy resin composite material is not higher than 1%;

[0009] The nano-hollow polystyrene microspheres have a mass filling fraction of up to 10% in the epoxy resin composite material.

[0010] Preferably, the preparation method of the nano-hollow silica microspheres includes the following steps:

[0011] A) Styrene monomer, stabilizer, initiator and water are mixed and reacted to obtain polystyrene microspheres;

[0012] B) Polystyrene microspheres, surfactants, silicon sources and solvents are mixed and reacted to obtain SiO2-coated polystyrene microspheres;

[0013] C) The SiO2-coated polystyrene microspheres were calcined and then acid-washed to obtain nano-hollow silica microspheres.

[0014] Preferably, the stabilizer is selected from one or more of polyvinylpyrrolidone, hydroxypropyl cellulose, and polyvinyl alcohol;

[0015] The initiator is selected from azobisisobutyramidine hydrochloride (AIBA);

[0016] The surfactant is selected from one or more of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and octadecyltrimethylammonium bromide;

[0017] The silicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate;

[0018] The calcination temperature is 500–800°C.

[0019] Preferably, the preparation method of the nano-hollow polystyrene microspheres includes the following steps:

[0020] a) A silicon source, a silane coupling agent, and a solvent are mixed and reacted to obtain surface-modified silica microspheres;

[0021] b) Mix surfactant, pH buffer and solvent, then add surface-modified silica microspheres, followed by styrene, divinylbenzene and initiator to react and obtain polystyrene-coated silica microspheres;

[0022] c) The polystyrene-coated silica microspheres are etched with hydrofluoric acid and then treated with calcium bicarbonate solution to obtain nano-hollow polystyrene microspheres.

[0023] Preferably, the silicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate;

[0024] The silane coupling agent is selected from one or more of methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane;

[0025] The surfactant is selected from sodium dodecylbenzenesulfonate and / or sodium dodecyl sulfate;

[0026] The pH buffers are sodium bicarbonate and / or potassium bicarbonate;

[0027] The initiator is selected from one or more of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0028] The present invention also provides a method for preparing the above-mentioned epoxy resin composite material, comprising the following steps:

[0029] Hollow microspheres were mixed with epoxy resin, stirred, ultrasonicated, vacuum degassed, and cured to obtain epoxy resin composite material.

[0030] The present invention also provides an application of the above-mentioned epoxy resin composite material in integrated circuits, electronic packaging, and 5G communication.

[0031] Compared with existing technologies, this invention provides an epoxy resin composite material with low dielectric constant and dielectric loss, prepared from hollow microspheres and epoxy resin. The hollow microspheres are selected from nano-hollow organic microspheres or nano-hollow inorganic microspheres. The epoxy resin composite material provided by this invention can be uniformly dispersed in an epoxy resin matrix. In particular, the nano-hollow organic microspheres can still be uniformly dispersed in the matrix even when the addition amount is not less than 10%, achieving low dielectric constant and low dielectric loss in the composite material. Results show that compared with an unfilled epoxy resin matrix, the prepared hollow microsphere / epoxy resin composite material exhibits significantly reduced dielectric constant and dielectric loss, with a minimum dielectric constant of 1.58 and a minimum dielectric loss of 0.013 at 1 MHz. Attached Figure Description

[0032] Figure 1 TEM image of PS microspheres;

[0033] Figure 2 TEM image of PS@SiO2 microspheres;

[0034] Figure 3 TEM image of H-SiO2 microspheres;

[0035] Figure 4 Infrared spectra of PS, PS@SiO2, and H-SiO2;

[0036] Figure 5 SEM images of the cross sections of (a) pure epoxy resin matrix and (b) 1% H-SiO2 / EP composite material;

[0037] Figure 6 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 1% H-SiO2 / EP composite material are given by frequency.

[0038] Figure 7 SEM images of the cross sections of (a) pure epoxy resin matrix and (b) 2% H-SiO2 / EP composite material;

[0039] Figure 8 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 2% H-SiO2 / EP composite material are given by frequency.

[0040] Figure 9 SEM images of the cross sections of (a) pure epoxy resin matrix and (b) 3% H-SiO2 / EP composite material;

[0041] Figure 10 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 3% H-SiO2 / EP composite material are given by frequency.

[0042] Figure 11 TEM image of SiO2-MPS microspheres;

[0043] Figure 12 TEM image of SiO2-MPS@PS microspheres;

[0044] Figure 13 TEM image of H-PS microspheres;

[0045] Figure 14 Infrared spectra of SiO2-MPS, SiO2-MPS@PS, and H-PS;

[0046] Figure 15 SEM images of cross sections of (a) pure epoxy resin matrix and (b) 1% H-PS / EP composite material;

[0047] Figure 16 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 1% H-PS / EP composite material are given by frequency.

[0048] Figure 17 SEM images of cross sections of (a) pure epoxy resin matrix and (b) 5% H-PS / EP composite material;

[0049] Figure 18 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 5% H-PS / EP composite material are given by frequency.

[0050] Figure 19 SEM images of cross sections of (a) pure epoxy resin matrix and (b) 10% H-PS / EP composite material;

[0051] Figure 20 The dielectric constant (a) and dielectric loss (b) of EP matrix material and 10% H-PS / EP composite material as a function of frequency are shown. Detailed Implementation

[0052] This invention provides an epoxy resin composite material with low dielectric constant and dielectric loss, which is prepared by hollow microsphere material and epoxy resin, wherein the hollow microsphere material is selected from nano-hollow organic microspheres or nano-hollow inorganic microspheres.

[0053] The hollow microsphere material has a particle size of 200–400 nm, preferably 200, 250, 300, 350, 400 nm, or any value between 200 and 400 nm, and a wall thickness of 10–80 nm, preferably 10, 20, 30, 40, 50, 60, 70, 80 nm, or any value between 10 and 80 nm.

[0054] In this invention, the hollow microsphere material is selected from nano-hollow silica microspheres or nano-hollow polystyrene microspheres.

[0055] When the hollow microsphere material is selected from nano-hollow silica microspheres, the mass filling fraction of the nano-hollow silica microspheres in the epoxy resin composite material is not higher than 1%, preferably 1%;

[0056] In this invention, the preparation method of the nano-hollow silica microspheres includes the following steps:

[0057] A) Styrene monomer, stabilizer, initiator and water are mixed and reacted to obtain polystyrene microspheres;

[0058] B) Polystyrene microspheres, surfactants, silicon sources and solvents are mixed and reacted to obtain SiO2-coated polystyrene microspheres;

[0059] C) The SiO2-coated polystyrene microspheres were calcined and then acid-washed to obtain nano-hollow silica microspheres.

[0060] Specifically, the present invention first disperses the stabilizer in water to obtain an aqueous solution of the stabilizer. The stabilizer is selected from one or more of polyvinylpyrrolidone, hydroxypropyl cellulose, and polyvinyl alcohol, preferably polyvinylpyrrolidone;

[0061] Then, under magnetic stirring, polystyrene monomer was added, and nitrogen gas was introduced. The mixture was heated under a nitrogen atmosphere, and then an initiator was added to initiate the reaction, yielding a reaction solution. The initiator was selected from azobisisobutyramidine hydrochloride (AIBA).

[0062] After the reaction solution was naturally cooled to room temperature, it was centrifuged to obtain a solid precipitate. The solid precipitate was washed and dried to obtain polystyrene (PS) microspheres.

[0063] Next, the surfactant was mixed with water and anhydrous ethanol, and then polystyrene microspheres were added for ultrasonic dispersion. Ammonia water was then added and mixed with stirring. Finally, a silicon source was added to react and a reaction solution was obtained.

[0064] The surfactant is selected from one or more of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide, preferably dodecyltrimethylammonium bromide; the silicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate and tetrapropyl orthosilicate, preferably tetramethyl orthosilicate.

[0065] The reaction solution was centrifuged, washed, and dried to obtain the product of SiO2-coated PS microspheres (PS@SiO2).

[0066] The SiO2-coated polystyrene microspheres are calcined to obtain the calcined product. The calcination temperature is 500–800°C, preferably 500, 600, 700, or 800°C, or any value between 500 and 800°C.

[0067] Then, the calcined product was mixed with anhydrous ethanol and concentrated hydrochloric acid and reacted. After the reaction was completed, the reaction solution was centrifuged, washed, and dried to obtain H-SiO2 microspheres.

[0068] When the hollow microsphere material is selected from nano-hollow polystyrene microspheres, the mass filling fraction of the nano-hollow polystyrene microspheres in the epoxy resin composite material is as high as 10%, preferably 10%.

[0069] The preparation method of the nano-hollow polystyrene microspheres includes the following steps:

[0070] a) A silicon source, a silane coupling agent, and a solvent are mixed and reacted to obtain surface-modified silica microspheres;

[0071] b) Mix surfactant, pH buffer and solvent, then add surface-modified silica microspheres, followed by styrene, divinylbenzene and initiator to react and obtain polystyrene-coated silica microspheres;

[0072] c) The polystyrene-coated silica microspheres are etched with hydrofluoric acid and then treated with calcium bicarbonate solution to obtain nano-hollow polystyrene microspheres.

[0073] Specifically, the present invention first mixes a silicon source, ethanol, and water to obtain solution 1. Then, a silane coupling agent is dispersed in ethanol to obtain solution 2. Solution 2 is then added to solution 1 to react and obtain the reaction product. The silicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate; the silane coupling agent is selected from one or more of methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0074] Then, the reaction product is centrifuged, washed, and dried to obtain surface-modified silica microspheres.

[0075] Next, the surfactant, pH buffer, and water are mixed to obtain a mixed solution.

[0076] The surfactant is selected from sodium dodecylbenzenesulfonate and / or sodium dodecyl sulfate;

[0077] The pH buffers are sodium bicarbonate and / or potassium bicarbonate;

[0078] Surface-modified silica microspheres were dispersed in ethanol and then added to the above mixed solution for mixing. Styrene (St) and divinylbenzene (DVB) were then added, and nitrogen gas was introduced. The system was subsequently heated, and an initiator was added to initiate the reaction, yielding a reaction solution. The initiator was selected from one or more of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0079] The reaction solution was centrifuged, washed, and dried to obtain polystyrene-coated silica microspheres (SiO2@PS).

[0080] Finally, the polystyrene-coated silica microspheres were mixed with hydrofluoric acid and etched at room temperature. After etching, the reaction solution was centrifuged, the supernatant was treated with calcium bicarbonate solution, and the lower precipitate was washed and dried to obtain nano-hollow polystyrene microspheres.

[0081] The present invention also provides a method for preparing the above-mentioned epoxy resin composite material, comprising the following steps:

[0082] Hollow microspheres were mixed with epoxy resin, stirred, ultrasonicated, vacuum degassed, and cured to obtain epoxy resin composite material.

[0083] Specifically, the present invention first mixes and stirs epoxy monomers with hollow microspheres, then adds curing agent and mixes and stirs, and after vacuum degassing, obtains a mixture;

[0084] This invention does not impose any particular limitation on the specific type of epoxy monomer used; epoxy monomers with a viscosity below 1.8 Pa·s can be used in this invention. Preferably, the epoxy monomer is selected from diglycidyl tetrahydrophthalate (TADE).

[0085] The curing agent is selected from room temperature curing agents such as m-phenylenediamine, ethylenediamine, and triethylamine.

[0086] The mixture is transferred to a mold containing a release agent, heated and cured, and then naturally cooled to room temperature to obtain an epoxy resin composite material.

[0087] The release agent includes, but is not limited to, the following: and 1038.

[0088] The curing reaction temperature does not exceed 60°C.

[0089] The present invention also provides an application of the above-mentioned epoxy resin composite material in integrated circuits, electronic packaging, and 5G communication.

[0090] This invention proposes a method for preparing low dielectric constant epoxy resin composite materials. First, hollow microspheres (inorganic or organic microspheres) of a specific size are synthesized. Then, they are uniformly mixed with an epoxy resin monomer system in a certain proportion. Finally, the mixture is cured in situ to obtain an epoxy resin composite material filled with hollow microspheres.

[0091] Compared with the unfilled epoxy resin matrix, the prepared hollow microsphere / epoxy resin composite material has significantly reduced dielectric constant and dielectric loss. The dielectric constant can be as low as 1.58 and the dielectric loss can be as low as 0.013 at 1MHz, which is expected to be widely used in integrated circuits, electronic packaging, 5G communication and other fields.

[0092] To further understand the present invention, the following embodiments illustrate the epoxy resin composite material with low dielectric constant and dielectric loss provided by the present invention, its preparation method, and its application. The scope of protection of the present invention is not limited by the following embodiments.

[0093] Example 1: (Hollow silica microspheres / epoxy resin composite material - filler mass fraction of 1%)

[0094] 1. Preparation of hollow silica microspheres (H-SiO2)

[0095] 4.125 g of polyvinylpyrrolidone (PVP) was ultrasonically dispersed in a three-necked flask containing 250 mL of deionized water. 25 g of styrene (St) monomer was added under magnetic stirring, and nitrogen gas was purged for 20 min. The mixture was heated to 70 °C under a nitrogen atmosphere, and 1220 mg of azobisisobutyramidine hydrochloride (AIBA) was added. After reacting for 16 h, the reaction solution was allowed to cool naturally to room temperature. The solid precipitate was obtained by centrifugation (12000 rpm, 8 min), washed three times with anhydrous ethanol, and dried to constant weight in a 50 °C oven to obtain polystyrene (PS) microspheres. Transmission electron microscopy (TEM, JEOL2011(H-7650), 100 kV) images are shown below. Figure 1 As shown, the microspheres have a diameter of approximately 300 nm.

[0096] 4.0 g of hexadecyltrimethylammonium bromide (CTAB) was weighed and added to a single-necked flask containing 250 mL of deionized water and 80 mL of anhydrous ethanol, and ultrasonically dispersed until homogeneous. Then, 4.5 g of PS microspheres were weighed and ultrasonically dispersed in the same flask. Next, 10 mL of ammonia water was added dropwise, and the mixture was magnetically stirred for 30 min. Then, 5.0 mL of tetraethyl orthosilicate (TEOS) was slowly added dropwise, and the reaction was carried out at 50 °C for 12 h. After the reaction was complete, the reaction solution was centrifuged, washed, and dried to obtain the product of SiO2-coated PS microspheres (PS@SiO2). Its transmission electron microscope (TEM, JEOL2011(H-7650), 100 kV) image is shown below. Figure 2As shown, the microspheres have a particle size of approximately 400 nm.

[0097] A certain amount of PS@SiO2 microspheres were placed in a crucible, which was then placed in a muffle furnace and heated to 600℃ for 8 hours. The calcined microspheres were then placed in a 150mL single-necked flask, and 80mL of anhydrous ethanol and 5mL of concentrated hydrochloric acid were added. The mixture was ultrasonically dispersed for 10 minutes and reacted at 50℃ for 5 hours with magnetic stirring. After the reaction, the reaction solution was centrifuged, washed, and dried to obtain the H-SiO2 microsphere product. Its transmission electron microscope (TEM, JEOL2011(H-7650), 100kV) image is shown below. Figure 3 As shown, the microspheres have a diameter of approximately 290 nm and a wall thickness of approximately 20 nm.

[0098] The infrared spectra of PS, PS@SiO2, and H-SiO2 are as follows: Figure 4 As shown, 460cm -1 799cm -1 1090cm -1 The absorption peaks at 1452 cm⁻¹ represent the bending vibration, symmetric stretching vibration, and antisymmetric vibration absorption peaks of Si-O-Si, respectively. -1 1492cm -1 1600cm -1 The peak at this location represents the bending vibration absorption peak of the -C=C- ring on the benzene ring.

[0099] 2. Preparation of H-SiO2 / epoxy resin (H-SiO2 / EP) composite material

[0100] Tetrahydrophthalic acid diglycidyl ester (TADE) with an epoxy equivalent of 150–180 g / mol was used as the epoxy monomer, and m-phenylenediamine (M-XDA) was used as the curing agent. 2 g of TADE was weighed into a sample vial, which was placed on a heated stage equipped with a magnetic stirrer. The temperature was set to 50°C, and the stirring speed to 300 rpm / min. 24.4 mg of H-SiO2 was weighed and slowly added to the vial. After magnetic stirring for 2 hours, the vial was sonicated for 20 minutes, and this process was repeated three times. Then, 412 mg of M-XDA was weighed and added to the sample vial. After magnetic stirring for 10 minutes, the vial was placed in a vacuum oven for vacuum degassing. The mixture was then transferred to a container coated with a release agent. The mixture was placed in a stainless steel mold and then placed in a 60℃ oven for 2 hours. Afterward, it was removed and allowed to cool naturally to room temperature to obtain a 1% H-SiO2 / EP composite material. Scanning electron microscope (SEM, HITACHI SU8220, 3kV) images of the cross-section of the 1% H-SiO2 / EP composite material are shown below. Figure 5 As shown, H-SiO2 can be seen to be uniformly dispersed in the epoxy resin matrix.

[0101] Figure 6The dielectric constant and dielectric loss of the EP matrix and the 1% H-SiO2 / EP composite material are measured as a function of frequency within the frequency range of 1 kHz to 1 MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37, and the dielectric loss is 0.026; the dielectric constant of the 1% H-SiO2 / EP composite material is 2.19, and the dielectric loss is 0.013.

[0102] Comparative Example 1: (Hollow silica microspheres / epoxy resin composite material - filler mass fraction of 2%)

[0103] Except for changing the mass fraction of hollow silica from 1% to 2%, the experimental procedures were exactly the same as in Example 1, yielding a 2% H-SiO2 / EP composite material. A scanning electron microscope (SEM, HITACHI SU8220, 3kV) image of the cross-section of the 2% H-SiO2 / EP composite material is shown below. Figure 7 As shown, H-SiO2 can be seen to be uniformly dispersed in the epoxy resin matrix.

[0104] Figure 8 The dielectric constant and dielectric loss of the EP matrix and the 2% H-SiO2 / EP composite material are measured as a function of frequency within the frequency range of 1kHz to 1MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37, and the dielectric loss is 0.026; the dielectric constant of the 2% H-SiO2 / EP composite material is 4.23, and the dielectric loss is 0.024. Compared with the 1% H-SiO2 / EP composite material, both the dielectric constant and dielectric loss of the 2% H-SiO2 / EP composite material are increased.

[0105] Comparative Example 2: (Hollow silica microspheres / epoxy resin composite material - 3% by mass)

[0106] Except for changing the mass fraction of hollow silica from 1% to 3%, the experimental procedures were completely consistent with Example 1, yielding a 3% H-SiO2 / EP composite material. Scanning electron microscope (SEM, HITACHI SU8220, 3kV) images of the cross-section of the 3% H-SiO2 / EP composite material are shown below. Figure 9 As shown, H-SiO2 can be seen to be uniformly dispersed in the epoxy resin matrix.

[0107] Figure 10The dielectric constant and dielectric loss of the EP matrix and the 3% H-SiO2 / EP composite material are measured as a function of frequency within the frequency range of 1kHz to 1MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37 and the dielectric loss is 0.026; the dielectric constant of the 3% H-SiO2 / EP composite material is 4.78 and the dielectric loss is 0.032.

[0108] Comparative Example 3: (Hollow polystyrene / epoxy resin composite material - 1% by mass)

[0109] 1. Preparation and characterization of hollow polystyrene (H-PS) microspheres

[0110] 315 mL of ethanol, 104 mL of deionized water, and 30.8 mL of TEOS were placed in a 1000 mL round-bottom flask and magnetically stirred until homogeneous. This solution is labeled as Solution 1. 2 mL of MPS (methacryloyloxypropyltrimethoxysilane) was added to 100 mL of ethanol and magnetically stirred until homogeneous. This solution is labeled as Solution 2. Solution 1 was reacted at room temperature with magnetic stirring for 3 hours. Then, Solution 2 was slowly added dropwise to the flask using a dropping funnel, and the reaction continued for 36 hours. After the reaction was complete, the reaction solution was centrifuged, washed, and dried to obtain MPS-modified silica microspheres (SiO2-MPS). Transmission electron microscopy (TEM, JEOL2011(H-7650), 100 kV) images are shown below. Figure 11 As shown, the microspheres have a diameter of approximately 190 nm.

[0111] Weigh 30 mg of sodium dodecylbenzenesulfonate (SDBS) and 240 mg of sodium bicarbonate (NaHCO3) into a 250 mL four-necked flask, add 100 mL of deionized water, and sonicate for 10 min. Disperse 1.2 g of SiO2-MPS microspheres in 10 mL of ethanol using sonication, and pour the ethanol into the same four-necked flask. After sonicating for 10 min, add 3 mL of St and 2 mL of divinylbenzene (DVB), and purge with nitrogen for 20 min. Then, heat the system to 72 °C, add 120 mg of potassium persulfate (KPS), and react for 12 h. After the reaction, centrifuge, wash, and dry the reaction solution to obtain polystyrene-coated silica microspheres (SiO2@PS). Transmission electron microscopy (TEM, JEOL2011(H-7650), 100 kV) images are shown below. Figure 12 As shown, the microspheres have a diameter of approximately 310 nm.

[0112] 400 mg of SiO2@PS microspheres were weighed into a plastic beaker. 20 mL of hydrofluoric acid (HF) was measured and carefully transferred into the beaker in a fume hood. The beaker was sealed with sealing film, and then etched at room temperature for 24 h with magnetic stirring. After etching, the reaction solution was centrifuged (9000 rpm, 5 min). The supernatant was treated with calcium bicarbonate (CaHCO3) solution, and the lower precipitate was washed three times with anhydrous ethanol by centrifugation and dried to constant weight in a 50°C oven to obtain hollow PS (H-PS) microspheres. Transmission electron microscopy (TEM, JEOL2011(H-7650), 100 kV) images are shown below. Figure 13 As shown, the microspheres have a diameter of approximately 310 nm and a wall thickness of approximately 65 nm.

[0113] Infrared spectra of SiO2-MPS, SiO2-MPS@PS, and H-PS are as follows: Figure 14 As shown, 460cm -1 799cm -1 1095cm -1 The absorption peaks at 1452 cm⁻¹ represent the bending vibration, symmetric stretching vibration, and antisymmetric vibration absorption peaks of Si-O-Si, respectively. -1 1492cm -1 1600cm -1 The absorption peak at 2850 cm⁻¹ is due to the bending vibration of the -C=C- ring on the benzene ring. -1 2924cm -1 The absorption peaks are for the symmetric and antisymmetric stretching vibrations of -CH2-.

[0114] 2. Preparation of H-PS / Epoxy Resin (H-PS / EP) Composite Material

[0115] The preparation process, epoxy resin system materials, and formulation of the H-PS / EP composite material are exactly the same as those in Part 2 of Example 1. The difference is that 24.4 mg of H-PS microspheres were used instead of H-SiO2 microspheres in Example 1 to prepare a 1% H-PS / EP composite material. Its cross-sectional scanning electron microscope (SEM, HITACHI SU8220, 3kV) image is shown below. Figure 15 As shown, H-PS microspheres are uniformly dispersed in the epoxy resin matrix.

[0116] Figure 16The dielectric constant and dielectric loss of the EP matrix and the 1% H-PS / EP composite material are measured as a function of frequency in the frequency range of 1kHz to 1MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37 and the dielectric loss is 0.026, while the dielectric constant of the 1% H-PS / EP composite material is 4.12 and the dielectric loss is 0.028.

[0117] Comparative Example 4: (Hollow polystyrene / epoxy resin composite material - 5% by mass)

[0118] Except for changing the mass fraction of hollow polystyrene from 1% to 5%, the experimental procedures were completely consistent with Comparative Example 3, yielding a 5% H-PS / EP composite material. Scanning electron microscope (SEM, HITACHISU 8220, 3kV) images of the cross-section of the 5% H-PS / EP composite material are shown below. Figure 17 As shown, H-PS can be seen to be uniformly dispersed in the epoxy resin matrix.

[0119] Figure 18 The dielectric constant and dielectric loss curves of the EP matrix material and the 5% H-PS / EP composite material are shown as a function of frequency in the frequency range of 1kHz to 1MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37 and the dielectric loss is 0.026; the dielectric constant of the 5% H-PS / EP composite material is 3.65 and the dielectric loss is 0.029. Compared with the 1% H-PS / EP composite material, the dielectric constant and dielectric loss of the 5% H-PS / EP composite material are decreased.

[0120] Example 2: (Hollow polystyrene / epoxy resin composite material - 10% by mass)

[0121] Except for changing the mass fraction of hollow polystyrene from 1% to 10%, the experimental procedures were completely consistent with Comparative Example 3, yielding a 10% H-PS / EP composite material. Scanning electron microscope (SEM, HITACHI SU8220, 3kV) images of the cross-section of the 10% H-PS / EP composite material are shown below. Figure 19 As shown, H-PS can be seen to be uniformly dispersed in the epoxy resin matrix.

[0122] Figure 20The dielectric constant and dielectric loss curves of the EP matrix material and the 10% H-PS / EP composite material are shown as a function of frequency in the frequency range of 1kHz to 1MHz (Agilent E4980A LCR meter, 1V). The measured dielectric constant of the EP matrix is ​​4.37 and the dielectric loss is 0.026; the dielectric constant of the 10% H-PS / EP composite material is 1.58 and the dielectric loss is 0.017. The dielectric constant and dielectric loss are lower than those of the 1% H-PS / EP and 5% H-PS / EP composite materials. Compared with the 1% H-PS / EP and 5% H-PS / EP composite materials, the dielectric constant and dielectric loss of the 10% H-PS / EP composite material are significantly lower, indicating that the dielectric constant and dielectric loss of the composite material decrease with increasing H-PS mass fraction.

[0123] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An epoxy resin composite material having low dielectric constant and dielectric loss, characterized by, It is prepared from hollow microsphere material and epoxy resin, wherein the hollow microsphere material is selected from nano hollow polystyrene microspheres; The mass fraction of the hollow polystyrene microspheres in the epoxy resin composite material is not less than 10%, and the particle size of the hollow microsphere material is 200~400 nm, and the wall thickness is 10~80 nm.

2. The epoxy resin composite material according to claim 1, characterized in that, The preparation method of the nano-hollow polystyrene microspheres includes the following steps: a) A silicon source, a silane coupling agent, and a solvent are mixed and reacted to obtain surface-modified silica microspheres; b) Mix surfactant, pH buffer and solvent, then add surface-modified silica microspheres, followed by styrene, divinylbenzene and initiator to react and obtain polystyrene-coated silica microspheres; c) The polystyrene-coated silica microspheres are etched with hydrofluoric acid and then treated with calcium bicarbonate solution to obtain nano-hollow polystyrene microspheres.

3. The epoxy resin composite material according to claim 2, characterized in that, The silicon source is selected from one or more of tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate; The silane coupling agent is selected from one or more of methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane; The surfactant is selected from sodium dodecylbenzenesulfonate and / or sodium dodecyl sulfate; The pH buffer is selected from sodium bicarbonate and / or potassium bicarbonate; The initiator is selected from one or more of potassium persulfate, ammonium persulfate, and sodium persulfate.

4. A method for preparing an epoxy resin composite material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Hollow microspheres were mixed with epoxy resin, stirred, ultrasonicated, vacuum degassed, and cured to obtain epoxy resin composite material.

5. The application of an epoxy resin composite material as described in any one of claims 1 to 3 in integrated circuits, electronic packaging, and 5G communication.

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