Benzocyclobutene resin with low dielectric loss and low thermal expansion coefficient as well as preparation method and application of benzocyclobutene resin

Abstract

The invention discloses a benzocyclobutene resin with low dielectric loss and low thermal expansion coefficient, which is prepared by the following steps: adding a benzocyclobutene functional monomer, a vinyl compound, 1, 3-diolefin and an organic solvent into a reaction kettle, uniformly stirring at low temperature, adding an initiator, reacting for a period of time, adding a small amount of methanol for quenching reaction, and cooling to room temperature to obtain the benzocyclobutene resin with low dielectric loss and low thermal expansion coefficient. After the reaction liquid is recovered to the room temperature, pouring the reaction liquid into methanol to precipitate and filter, drying a filter cake, adding methylbenzene to dissolve, washing with ultrapure water, drying and concentrating to obtain the benzocyclobutene resin, which has the advantages of adjustable molecular weight, adjustable glass transition temperature and the like, and omits the tedious step of prepolymerization of the resin in the past; the benzocyclobutene resin has excellent thermal stability, mechanical property and dielectric property after being cured at high temperature, and can be used as a high-temperature-resistant dielectric material, a high-performance composite material, an electronic packaging material and an aeronautical material to be applied to the field of interlayer packaging of 5G / 6G high-frequency PCBs and chips.

Description

Technical Field

[0001] This invention belongs to the technical field of thermosetting polyolefin materials, specifically relating to a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion, its preparation method, and its application. Background Technology

[0002] In recent years, due to the demand for high-frequency and high-speed development, the size of very large-scale integrated circuits (VLSI) has been gradually shrinking, and the interconnection lines inside the chips have become increasingly dense. This has led to a series of problems such as signal transmission delay, crosstalk, and increased power loss, which have a significant impact on device performance. Using low-dielectric, low-loss materials as interlayer dielectrics is one of the important solutions. Therefore, the design and synthesis of high-performance low-dielectric, low-loss materials has become a topic of particular interest to contemporary researchers.

[0003] Benzocyclobutene (BCB) resins, as thermosetting resins, possess the following advantages: they are thermosetting without releasing small molecules, the cured product exhibits excellent heat resistance, an extremely low coefficient of thermal expansion, and superior electromechanical properties. These advantages make them popular in fields related to optics, electronics, and heat, and they are currently widely used in aerospace, microelectronics packaging, and other related industries. Applications include interlayer insulating materials, photoresist materials, electronic packaging materials, radar-transparent materials, and high-density interconnect circuit boards.

[0004] However, existing benzocyclobutene resins require prepolymerization during preparation, a cumbersome and complex process that results in poor dielectric properties. To improve the dielectric properties, various characteristic polymeric monomers have been added to the preparation system. For example, patent CN119081008B discloses a method for preparing benzocyclobutene resin by adding 4-vinylbenzocyclobutene or 1-vinylbenzocyclobutene to the system. This method requires a high-pressure reaction, which is dangerous and difficult to scale up. Furthermore, the molecular weight of the resulting resin is difficult to control, making it unsuitable for downstream product requirements, and the improvement in dielectric properties is limited. Therefore, a simple, safe, molecular weight-controllable method for preparing benzocyclobutene resin with excellent dielectric properties is urgently needed. Summary of the Invention

[0005] One object of the present invention is to at least solve the above-mentioned problems or defects and to provide a technical solution whose advantages will be described later.

[0006] To achieve these and other advantages of the present invention, a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion is provided, the benzocyclobutene resin having the following structural formula: Where x, y, z are integers ≥ 1, and w is an integer ≥ 0; the ratio of x + y to z + w is 1:9 to 9:1.

[0007] Preferably, in the structural formula, A is a structural unit that simultaneously contains a benzocyclobutenyl group and a double bond; R1 is one of -H or C1~C3 alkyl groups.

[0008] Preferably, in the structural formula, R2 is one of substituted or unsubstituted phenyl, benzocyclobutenyl, biphenyl, naphthyl, phenanthryl, and anthracene, wherein substitution means that one or more hydrogen atoms on the aryl group are substituted by a C1-C6 alkyl group.

[0009] Preferably, R3 is one of substituted or unsubstituted C4-C6 alkyl groups, wherein substitution means that one or more hydrogen atoms on the group are substituted, and the group that substituted the hydrogen atoms is a C1-C4 alkyl group, a phenyl group, or a phenyl group in which 1 to 3 hydrogen atoms on the benzene ring are substituted by an alkyl group having 1 to 4 carbon atoms. R3 may be one of substituted or unsubstituted phenyl, biphenyl, naphthyl, phenanthryl, or anthracene, wherein substitution means that one or more hydrogen atoms on the aryl group are substituted by a C1-C6 alkyl group.

[0010] A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: 4-Bromobenzocyclobutene, vinyl compound A, palladium acetate, potassium acetate, tri-o-tolylphosphine, tetrabutylammonium bromide, N,N-dimethylformamide, and ultrapure water are sequentially added to a reactor. After nitrogen protection, the reaction is carried out continuously under heating and vigorous stirring to obtain a reaction mother liquor. After the reaction is completed, the mixture is cooled to room temperature, extracted with ethyl acetate, washed with water and saturated brine, and the organic phase is separated. Anhydrous sodium sulfate is added for drying. After drying, the solvent is removed, and the mixture is purified by recrystallization with ethyl acetate to obtain the benzocyclobutene monomer. Step 2: Add the benzocyclobutene monomer, vinyl compound B and / or 1,3-diolefin and organic solvent to the reaction vessel, stir evenly at low temperature, then add the initiator, react for a period of time, and then add a small amount of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into methanol to precipitate and filter. After drying the filter cake, add toluene to dissolve it, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin.

[0011] Preferably, in step one, the molar ratio of 4-bromobenzocyclobutene, vinyl compound A, palladium acetate, potassium acetate, tri-o-tolylphosphine, tetrabutylammonium bromide, N,N-dimethylformamide, and ultrapure water is 40~60:20~40:0.01~0.05:0.6~2:0.04~0.08:2~4:0.25~0.3:5~6, vinyl compound A is one of tetravinyldisiloxane, styrene, and divinylbenzene, nitrogen gas is introduced for protection for 30~60 min, the heating and stirring temperature is 90~100℃, the stirring speed is 300~400 rpm, and the stirring is carried out for 48~60 h. When removing the solvent, the solvent is removed under the conditions of -0.09~-0.10 MPa and 40~50℃.

[0012] Preferably, in step two, the molar ratio of benzocyclobutene monomer, vinyl compound B, 1,3-diolefin, and organic solvent is 0.1~0.5:0~0.6:0~0.6:1~10, and the amount of initiator added is 0.001%~10% of the total number of moles of the added materials.

[0013] Preferably, in step two, the benzocyclobutene monomer is one of 1-phenyl,2-benzocyclobutenylethylene, 1,2-dibenzocyclobutenylethylene, and 1,4-dibenzocyclobutenyldivinylbenzene, and the vinyl compound is hexene, vinylcyclohexane, heptene, octene, styrene, 1-methylstyrene, 2-methylstyrene, p-methylstyrene, vinylbiphenyl, vinylnaphthalene and its substitutes, vinylphenanthrene and its substitutes, vinylanthracene and its substitutes. One of the following is used: the 1,3-diolefin is one of butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, or 2-methyl-1,3-pentadiene; the organic solvent is one of tetrahydrofuran, acetonitrile, 1,4-dioxane, or n-hexane; the initiator is one of n-butyllithium, sec-butyllithium, methyllithium, or sodium naphthalene; the reaction temperature is -5 to -78℃; the reaction time is 4 to 10 hours; when the reaction is quenched with methanol, the amount of methanol used is 1% to 5% of the volume of the organic solvent.

[0014] Preferably, in step three, the volume ratio of the reaction solution to methanol is 1:3~10.

[0015] An application of benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion is disclosed, in which the benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion is used as a high-temperature resistant dielectric material, high-performance composite material, electronic packaging material or aerospace material in the fields of 5G / 6G high-frequency PCB boards and interlayer packaging of chips.

[0016] The present invention has the following beneficial effects: The benzocyclobutene group characteristic polymeric monomers of the present invention exhibit structural diversity, and the most crucial benzocyclobutene group monomers can be prepared by a HECK reaction under normal pressure. The reaction is mild and has a high conversion rate. The synthesized monomers are all solid materials, and post-processing is simple; only simple recrystallization is needed to obtain high-purity polymeric monomers. The synthesis is simple and easy to scale up, without requiring high-temperature and high-pressure reactions. The benzocyclobutene resin prepared using the benzocyclobutene group monomers of the present invention has advantages such as adjustable molecular weight (the molecular weight can be well controlled within 3000-5000) and adjustable glass transition temperature. It also eliminates the cumbersome "prepolymerization" step previously required for this type of resin, allowing it to be directly used in the next application, significantly reducing production costs. The benzocyclobutene resin prepared by the present invention exhibits excellent thermal stability, mechanical properties, and dielectric properties after high-temperature curing. At a frequency of 10 GHz, its dielectric constant (Dk) is 2.35-2.60, and its dielectric loss (Df) is 0.0004-0.0007. 5% With a thermal decomposition temperature of 420-465℃ and a thermal expansion coefficient of 32-85 ppm / ℃@ 50℃, it can be used as a high-temperature resistant dielectric material, high-performance composite material, electronic packaging material, and aerospace material; it is applied to high-frequency PCB boards for 5G / 6G and interlayer packaging of chips. Attached Figure Description

[0017] Figure 1 The NMR spectrum of 1-phenyl,2-benzocyclobutenylethylene obtained in step one of Example 1; Figure 2 The NMR spectrum of 1,2-dibenzocyclobutenyl ethylene obtained in step one of Example 9; Figure 3 The NMR spectrum of 1,4-dibenzocyclobutenyldivinylbenzene obtained in step one of Example 14; Figure 4 The NMR spectrum of benzocyclobutene resin 1 prepared in Example 1; Figure 5 The NMR spectrum of benzocyclobutene resin 2 prepared in Example 2; Figure 6 The NMR spectrum of benzocyclobutene resin 7 prepared in Example 7 is shown below. Figure 7 The GPC spectrum of benzocyclobutene resin 1 prepared in Example 1 is shown below. Figure 8 The GPC spectrum of benzocyclobutene resin 14 prepared in Example 14 is shown below. Figure 9 The rheological curves of benzocyclobutene resin 1 prepared in Example 1 at 60-200℃ are shown. Figure 10The rheological curve of benzocyclobutene resin 1 prepared in Example 1 at 160°C is a constant temperature rheological curve. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, so that those skilled in the art can implement it based on the description.

[0019] Example 1 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: 4-Bromobenzocyclobutene (74.8 g, 400 mmol), styrene (200 mmol), palladium acetate (22.4 mg, 0.1 mmol), potassium acetate (5.88 g, 60 mmol), tri-o-tolylphosphine (120 mg, 0.4 mmol), tetrabutylammonium bromide (6.44 g, 20 mmol), 200 mL of N,N-dimethylformamide, and 100 mL of ultrapure water were sequentially added to a reactor. After purging with nitrogen for 30 min, the mixture was heated to 90 °C and vigorously stirred for 48 h to obtain a mother liquor. After the reaction was complete, the mixture was cooled to room temperature, extracted with ethyl acetate, washed with water and saturated brine, and the organic phase was separated. Anhydrous sodium sulfate was added for drying. After drying, the solvent was removed at a pressure of -0.09 MPa and a temperature of 40 °C. The mixture was then purified by recrystallization with ethyl acetate to obtain 1-phenyl,2-benzocyclobutenylethylene, whose NMR spectrum is shown below. Figure 1 As shown (chemical shift 3.25 represents the H in the four-membered ring of BCB); Step 2: Add 51.5 g (0.25 mol) of 1-phenyl,2-benzocyclobutenylethylene, 40.5 g (0.75 mol) of butadiene and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 13 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 1 with a yield of 91%. The structural formula of benzocyclobutene resin 1 is as follows: Its NMR spectrum is as follows Figure 4 As shown (chemical shift 3.25 represents the H of the four-membered ring in BCB, and the characteristic peak of polybutadiene can also be seen in the figure); its GPC spectrum is as follows. Figure 7 As shown in the figure, the peak is single-peaked and narrowly distributed, indicating a narrow molecular weight distribution; its rheological curves at 60-200℃ are as follows. Figure 9As shown in the rheological curves, the viscosity of the resin changes after 160℃, corresponding to double bonds and four-membered rings, respectively; its isothermal rheological curve at 160℃ is shown in the figure. Figure 10 As shown in the isothermal rheological curve, the viscosity of the resin increases with time after 160℃.

[0020] Example 2 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 82.4 g (0.4 mol) of 1-phenyl,2-benzocyclobutenylethylene, 32.4 g (0.6 mol) of butadiene and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 20 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 3 with a yield of 95%. The structural formula of benzocyclobutene resin 2 is as follows: Its NMR spectrum is as follows Figure 5 As shown (chemical shift 3.25 represents the H of the four-membered ring in BCB, and the characteristic peak of polybutadiene can also be seen in the figure).

[0021] Example 3 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 1-phenyl,2-benzocyclobutenylethylene (103 g, 0.5 mol), butadiene (27 g, 0.5 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 20 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 3 with a yield of 95%. The structural formula of benzocyclobutene resin 3 is as follows: .

[0022] Example 4 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 41.2 g (0.2 mol) of 1-phenyl,2-benzocyclobutenylethylene, 27 g (0.5 mol) of butadiene, 31.2 g (0.3 mol) of styrene and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 15 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 4 with a yield of 92%. The structural formula of benzocyclobutene resin 4 is as follows: .

[0023] Example 5 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 1-phenyl,2-benzocyclobutenylethylene (61.8 g, 0.3 mol), styrene (31.2 g, 0.3 mol), butadiene (21.6 g, 0.4 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 18 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 5 with a yield of 94%. The structural formula of benzocyclobutene resin 5 is as follows: .

[0024] Example 6 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 1-phenyl,2-benzocyclobutenylethylene (103 g, 0.5 mol), styrene (31.2 g, 0.3 mol), butadiene (10.8 g, 0.2 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 12 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 6 with a yield of 92%. The structural formula of benzocyclobutene resin 6 is as follows: .

[0025] Example 7 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 1-phenyl,2-benzocyclobutenylethylene (41.2 g, 0.2 mol), vinylbiphenyl (54.6 g, 0.3 mol), butadiene (27 g, 0.5 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 15 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 7 with a yield of 86%. The structural formula of benzocyclobutene resin 7 is as follows: Its NMR spectrum is as follows Figure 6 As shown (chemical shift 3.25 represents the H of the four-membered ring in BCB, and the characteristic peak of polybutadiene can also be seen in the figure), Figure 5 Compared to 6, the only difference lies in the integral ratio of characteristic functional groups in the polymer.

[0026] Example 8 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: Same as in Example 1; Step 2: Add 1-phenyl,2-benzocyclobutenylethylene (61.8 g, 0.3 mol), vinylbiphenyl (54.6 g, 0.3 mol), butadiene (21.6 g, 0.4 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 15 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 8 with a yield of 82%. The structural formula of benzocyclobutene resin 8 is as follows: .

[0027] Example 9 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: 4-Bromobenzocyclobutene (74.8 g, 400 mmol), tetravinyldisiloxane (200 mmol), palladium acetate (22.4 mg, 0.1 mmol), potassium acetate (5.88 g, 60 mmol), tri-o-tolylphosphine (120 mg, 0.4 mmol), tetrabutylammonium bromide (6.44 g, 20 mmol), 200 mL of N,N-dimethylformamide, and 100 mL of ultrapure water were sequentially added to a reactor. After purging with nitrogen for 30 min, the mixture was heated to 90 °C and vigorously stirred for 48 h to obtain a mother liquor. After the reaction was complete, the mixture was cooled to room temperature, extracted with ethyl acetate, washed with water and saturated brine, and the organic phase was separated. Anhydrous sodium sulfate was added for drying. After drying, the solvent was removed at -0.09 MPa and 40 °C. The mixture was then purified by recrystallization with ethyl acetate to obtain 1,2-dibenzocyclobutenylethylene, whose NMR spectrum is shown below. Figure 2 As shown (chemical shift 3.25 represents the H in the four-membered ring of BCB, and the integral ratio of the corresponding number of H is matched); Step 2: Add 58 g of 1,2-dibenzocyclobutenylethylene (0.25 mol), butadiene (40.5 g, 0.75 mol), and 300 mL of dry tetrahydrofuran to a 1 L reactor. Stir the mixture at -20 °C until homogeneous, then add 12 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 9 with a yield of 90%. The structural formula of benzocyclobutene resin 9 is as follows: .

[0028] Example 10 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1 is the same as in Example 9; Step 2: Add 92.8 g (0.4 mol) of 1,2-dibenzocyclobutenylethylene, 32.4 g (0.6 mol) of butadiene and 300 mL of dry tetrahydrofuran to a 1 L reactor. Stir the mixture at -20 °C until homogeneous, then add 20 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 10 with a yield of 92%. The structural formula of benzocyclobutene resin 10 is as follows: .

[0029] Example 11 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1 is the same as in Example 9; Step 2: Add 1,2-dibenzocyclobutenylethylene (116 g, 0.5 mol), butadiene (27 g, 0.5 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 20 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 11 with a yield of 91%. The structural formula of benzocyclobutene resin 11 is as follows: .

[0030] Example 12 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1 is the same as in Example 9; Step 2: Add 1,2-dibenzocyclobutenylethylene (46.4 g, 0.2 mol), styrene (31.2 g, 0.3 mol), butadiene (27 g, 0.5 mol) and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 15 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 12 with a yield of 92%. The structural formula of benzocyclobutene resin 12 is as follows: .

[0031] Example 13 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1 is the same as in Example 9; Step 2: Add 92.8 g (0.4 mol) of 1,2-dibenzocyclobutenylethylene, 62.4 g (0.6 mol) of styrene, 27 g (0.5 mol) of butadiene and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 15 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 6 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 13 with a yield of 92%. The structural formula of benzocyclobutene resin 13 is as follows: .

[0032] Example 14 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1: 4-Bromobenzocyclobutene (74.8 g, 400 mmol), divinylbenzene (200 mmol), palladium acetate (22.4 mg, 0.1 mmol), potassium acetate (5.88 g, 60 mmol), tri-o-tolylphosphine (120 mg, 0.4 mmol), tetrabutylammonium bromide (6.44 g, 20 mmol), 200 mL of N,N-dimethylformamide, and 100 mL of ultrapure water were sequentially added to a reactor. After purging with nitrogen for 30 min, the mixture was heated to 90 °C and vigorously stirred for 48 h to obtain a mother liquor. After the reaction was complete, the mixture was cooled to room temperature, extracted with ethyl acetate, washed with water and saturated brine, and the organic phase was separated. Anhydrous sodium sulfate was added for drying. After drying, the solvent was removed at -0.09 MPa and 40 °C. The mixture was then purified by recrystallization with ethyl acetate to obtain 1,4-dibenzocyclobutenyldivinylbenzene, whose NMR spectrum is shown below. Figure 3 As shown (chemical shift 3.25 represents the H in the four-membered ring of BCB); Step 2: Add 84 g (0.25 mol) of 1,4-dibenzocyclobutenyldivinylbenzene, 40.5 g (0.75 mol) of butadiene and 300 mL of dry tetrahydrofuran to a 1 L reactor. After stirring at -20 °C until homogeneous, add 12 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 1.5 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 14 with a yield of 95%. The structural formula of benzocyclobutene resin 14 is as follows: Its GPC map is as follows Figure 8 As shown in the figure, the resin has a wide distribution, and the reactive groups suggest that the resin may have localized branching.

[0033] Example 15 A method for preparing a benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion includes the following steps: Step 1 is the same as in Example 14; Step 2: Add 33.4 g, 0.1 mol of 1,4-dibenzocyclobutenyldivinylbenzene, 48.6 g, 0.9 mol of butadiene, and 300 mL of dry tetrahydrofuran to a 1 L reactor. Stir the mixture at -20 °C until homogeneous, then add 8 mL of n-butyllithium (1.6 M, n-hexane solution). After reacting for 1.5 h, add 3 mL of methanol to quench the reaction. Step 3: After the reaction solution returns to room temperature, pour the reaction solution into 1L of methanol to precipitate and filter. After drying the filter cake, dissolve it in 500mL of toluene, then wash with ultrapure water, dry and concentrate to obtain benzocyclobutene resin 15 with a yield of 93%. The structural formula of benzocyclobutene resin 15 is as follows: .

[0034] Comparative Example 1 Benzocyclobutene resin was prepared using the method described in patent CN119081008B.

[0035] Compared to patent CN119081008B, the characteristic polymeric monomers (benzocyclobutene group monomers) prepared in step one of this invention exhibit structural diversity. Most importantly, the synthesis of these monomers utilizes a HECK reaction under normal pressure, resulting in a mild reaction with high conversion rates. The synthesized monomers are all solid materials, simplifying post-processing; only simple recrystallization is required to obtain high-purity polymeric monomers. The preparation of these monomers is easily scaled up industrially. In contrast, the BCB characteristic polymeric monomers in CN119081008B require high-pressure reactions, which are hazardous and difficult to scale up. Furthermore, regarding polymerization, compared to patent CN119081008B, the characteristic polymeric monomers (benzocyclobutene group monomers) prepared in step one of this invention allow for better control of the molecular weight of the product within the range of 3000-5000 (the preferred molecular weight range for downstream applications).

[0036] The dielectric properties of the benzocyclobutene resin random copolymers prepared in Examples 1-15 were tested at 10 GHz, and the results are shown in Table 1.

[0037] Table 1 Example Dielectric constant Dielectric loss <![CDATA[T 5% (℃)]]> Coefficient of thermal expansion (ppm / ℃@50℃) 1 2.53 0.0005 443 67 2 2.54 0.0006 445 54 3 2.54 0.0006 445 54 4 2.66 0.00065 448 57 5 2.68 0.00065 442 52 6 2.64 0.0006 442 38 7 2.58 0.0006 464 64 8 2.60 0.00065 468 62 9 2.56 0.00055 445 61 10 2.54 0.0006 445 52 11 2.54 0.00055 445 49 12 2.61 0.0006 448 53 13 2.60 0.0006 445 40 14 2.60 0.0065 448 62 15 2.60 0.0065 442 65 Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion, characterized by, The benzocyclobutene resin has the following structural formula: In the formula, x, y, and z are integers greater than or equal to 1, and w is an integer greater than or equal to 0; the ratio of x+y to z+w is 1:9 to 9:

1.

2. The benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion according to claim 1, wherein, In the structural formula, A is a structural unit containing both a benzocyclobutene group and a double bond; R1 is one of -H or C1-C3 alkyl.

3. The benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion according to claim 1, wherein, In the structural formula, R2 is one of a substituted or unsubstituted phenyl group, benzocyclobutene group, biphenyl group, naphthyl group, phenanthryl group, or anthryl group, wherein the substitution means that one or more hydrogen atoms on the aryl group are substituted with a C1-C6 alkyl group.

4. The benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion according to claim 1, wherein, R3 is one of a substituted or unsubstituted C4-C6 alkyl group, wherein the substitution means that one or more hydrogen atoms on the group are substituted, and the group substituted with hydrogen atoms is a C1-C4 alkyl group, phenyl group, or phenyl group substituted with an alkyl group having 1-4 carbon atoms; or R3 is one of a substituted or unsubstituted phenyl group, biphenyl group, naphthyl group, phenanthryl group, or anthryl group, wherein the substitution means that one or more hydrogen atoms on the aryl group are substituted with a C1-C6 alkyl group.

5. A method of producing a benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion according to any one of claims 1 to 4, characterized by, The method comprises the following steps: Step one: 4-bromobenzocyclobutene, vinyl compound A, palladium acetate, potassium acetate, tri-o-tolylphosphine, tetrabutylammonium bromide, N,N-dimethylformamide, and ultrapure water are sequentially added to a reactor, nitrogen is introduced for protection, and then continuous reaction is carried out under heating and strong stirring; after the reaction is completed, the reaction solution is cooled to room temperature, extracted with ethyl acetate, washed with water and saturated brine, the organic phase is separated, dried with anhydrous sodium sulfate, and then the solvent is removed; after drying, the solvent is removed, and then recrystallized with ethyl acetate to obtain a benzocyclobutene group monomer; Step two: the benzocyclobutene group monomer, vinyl compound B and / or 1,3-position diolefin, and an organic solvent are added to a reaction kettle, and then the mixture is stirred uniformly at low temperature; an initiator is then added, and after a period of reaction, a small amount of methanol is added to quench the reaction; Step three: after the reaction solution is restored to room temperature, the reaction solution is poured into methanol to precipitate and filter; the filter cake is dried, dissolved in toluene, washed with ultrapure water, dried and concentrated to obtain a benzocyclobutene resin.

6. The method for preparing benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion as described in claim 5, characterized in that, In step one, the molar ratio of 4-bromobenzocyclobutene, vinyl compound A, palladium acetate, potassium acetate, tri-o-tolylphosphine, tetrabutylammonium bromide, N,N-dimethylformamide, and ultrapure water is 40-60:20-40:0.01-0.05:0.6-2:0.04-0.08:2-4:0.25-0.3:5-6; vinyl compound A is one of tetraethenyl disiloxane, styrene, and divinylbenzene; nitrogen is introduced for protection for 30-60 min; the heating and stirring temperature is 90-100℃; the strong stirring speed is 300-400 rpm; the stirring time is 48-60 h; and the solvent is removed at a temperature of 40-50℃ and a pressure of -0.09 to -0.10 MPa.

7. The method for preparing benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion as described in claim 5, characterized in that, In step two, the molar ratio of benzocyclobutene monomer, vinyl compound B, 1,3-diolefin, and organic solvent is 0.1~0.5:0~0.6:0~0.6:1~10, and the amount of initiator added is 0.001%~10% of the total number of moles of the added materials.

8. The method for preparing benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion as described in claim 5, characterized in that, In step two, the benzocyclobutene monomer is one of 1-phenyl,2-benzocyclobutenylethylene, 1,2-dibenzocyclobutenylethylene, and 1,4-dibenzocyclobutenyldivinylbenzene; the vinyl compound is one of hexene, vinylcyclohexane, heptene, octene, styrene, 1-methylstyrene, 2-methylstyrene, p-methylstyrene, vinylbiphenyl, vinylnaphthalene and its substitutes, vinylphenanthrene and its substitutes, and vinylanthracene and its substitutes; the 1,3-diolefin is one of butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, and 2-methyl-1,3-pentadiene; the organic solvent is one of tetrahydrofuran, acetonitrile, 1,4-dioxane, and n-hexane; the initiator is one of n-butyllithium, sec-butyllithium, methyllithium, and sodium naphthalene; the reaction temperature is -5 to -78°C; the reaction time is 4 to 10 hours; and when the reaction is quenched with methanol, the amount of methanol used is 1% to 5% of the volume of the organic solvent.

9. The method for preparing benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion as described in claim 5, characterized in that, In step three, the volume ratio of the reaction solution to methanol is 1:3~10.

10. Use of a benzocyclobutene resin having low dielectric loss and low coefficient of thermal expansion according to any one of claims 1 to 4, characterized in that, The benzocyclobutene resin with low dielectric loss and low coefficient of thermal expansion is used as a high-temperature resistant dielectric material, high-performance composite material, electronic packaging material or aerospace material in the fields of 5G / 6G high-frequency PCB boards and chip interlayer packaging.

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