Copper-clad plate with low dielectric constant and preparation method thereof
By combining modified cellulose and polyether ether ketone matrix slurry with polylactic acid microspheres and aerogel precursor spraying to create a gradient porous structure, the problems of dielectric instability and mechanical property degradation of existing low-dielectric copper clad laminates in high-frequency signal transmission are solved, and copper clad laminates with low dielectric constant and low dielectric loss are prepared.
Patent Information
- Application Number
- CN202511305663.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-12
- Publication Date
- 2025-10-31
AI Technical Summary
Existing low-dielectric copper clad laminate materials are difficult to meet the requirements of 5G communication in terms of dielectric constant and dielectric loss during high-frequency signal transmission, and the porous modification technology has problems such as uneven pore distribution and poor stability.
A mixture of modified cellulose, polyetheretherketone, and N,N-dimethylacetamide was used as the matrix slurry. Dicumyl peroxide and an anti-settling agent were added to prepare a gradient porous structure. Polylactic acid microspheres were used as pore-forming agents, and combined with aerogel precursor dispersion spraying, a dense bottom layer and a high-porosity core layer were formed. A low dielectric constant copper-clad laminate was prepared by hot pressing and curing.
It significantly reduces the dielectric constant and dielectric loss of copper clad laminates, meets the requirements of 5G high-frequency signal transmission, ensures the dimensional stability and mechanical properties of copper clad laminates during thermal cycling, and avoids the ion residue problem of traditional pore-forming agents.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of copper clad laminate technology, specifically to a low dielectric constant copper clad laminate and its preparation method. Background Technology
[0002] With the rapid development of technologies such as 5G communication, millimeter-wave radar, and high-speed computing, the requirements for signal transmission rate and stability in electronic devices are constantly increasing. Copper clad laminates (CCLs), as a core basic material, need to meet lower dielectric constants (Dk) and dielectric losses (Df). In high-frequency signal transmission, high dielectric constant materials can lead to signal delay and increased attenuation, while excessive dielectric loss can cause energy waste and equipment overheating. Therefore, the industry urgently needs low-dielectric CCLs with dielectric constants ≤3.0 and dielectric losses ≤0.002. Currently, the dielectric properties of CCLs are mainly determined by the matrix resin, reinforcing materials, and microstructure. Developing composite systems that combine low dielectric properties, excellent mechanical properties, and thermal stability has become a research hotspot.
[0003] Existing low-dielectric copper-clad laminate (CCL) materials exhibit significant performance bottlenecks. Traditional epoxy resin-based CCLs, due to their strong molecular polarity, generally have a dielectric constant of 3.5-4.0, making them unsuitable for high-frequency applications. While polytetrafluoroethylene (PTFE)-based materials can achieve dielectric constants as low as 2.5-3.0, they suffer from poor mechanical strength (tensile strength <20MPa) and a large difference in interfacial polarity with copper foil, resulting in peel strengths often below 0.8N / mm. Complex surface treatments are required to improve adhesion, but these often introduce high-dielectric impurities, leading to performance degradation. Furthermore, glass fiber reinforcement is commonly used to improve the mechanical properties of PTFE, but the high dielectric constant of glass fibers (6-7) significantly increases the overall dielectric constant of the composite material.
[0004] At the structural design and process level, existing porous modification technologies for low-dielectric copper clad laminates have shortcomings. Traditional pore-forming agents mostly use inorganic microspheres or high-temperature foaming agents. The former can lead to uneven pore distribution due to poor compatibility at the inorganic-organic interface, while the latter can result in poor dielectric stability due to the difficulty in controlling the foaming of the foaming agent and large fluctuations in porosity. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a low dielectric constant copper clad laminate and its preparation method.
[0006] The objective of this invention can be achieved through the following technical solutions: On one hand, the present invention provides a method for preparing a low dielectric constant copper-clad laminate, comprising the following preparation steps: S1: Mix modified cellulose, polyetheretherketone and N,N-dimethylacetamide, heat and stir, add dicumyl peroxide and anti-settling agent, continue stirring to obtain matrix slurry; S2: Take a portion of the matrix slurry as the base slurry, coat it onto the PET release film, and pre-bake it to obtain the bottom prepreg; take the remaining matrix slurry as the core layer slurry, add a pore-forming agent to the core layer slurry, stir evenly to obtain the core layer prepreg slurry; coat the core layer prepreg slurry onto the bottom prepreg, pre-bake it to obtain the gradient porous prepreg; spray the aerogel precursor dispersion evenly onto the surface of the gradient porous prepreg core layer, let it stand, and obtain the gradient porous composite prepreg; S3: Immerse the electrolytic copper foil in a micro-etching solution for micro-etching treatment. After micro-etching treatment, immerse the electrolytic copper foil in a methyltriethoxysilane ethanol solution for soaking treatment. After taking it out, dry it to obtain pre-treated electrolytic copper foil. S4: In a hot press, release film, pretreated electrolytic copper foil, gradient porous composite prepreg, pretreated electrolytic copper foil, and release film are laid sequentially on a template to ensure layer alignment. After hot pressing and curing, and cooling to room temperature, the release film is peeled off to obtain a copper composite board. The copper composite board is then immersed in deionized water for soaking treatment, and after being taken out and dried, a low dielectric constant copper-clad laminate is obtained.
[0007] Further, the specific steps of S1 are as follows: mix modified cellulose, polyether ether ketone and N,N-dimethylacetamide, heat to 70℃-80℃, control the speed at 600rpm-1000rpm, stir for 20min-40min, add dicumyl peroxide and anti-settling agent, maintain the temperature and speed unchanged, and continue stirring for 30min-50min to obtain the matrix slurry.
[0008] Further, the specific steps of S2 are as follows: A portion of the matrix slurry is taken as the base slurry and uniformly coated onto the PET release film, controlling the wet film thickness of the base slurry to be 0.1 mm. It is then pre-baked at 60℃-80℃ for 10-18 minutes to obtain the bottom prepreg. The remaining matrix slurry is used as the core layer slurry. A pore-forming agent is added to the core layer slurry and stirred evenly to obtain the core layer prepreg slurry. The core layer prepreg slurry is coated onto the bottom prepreg, controlling the wet film thickness of the core layer prepreg slurry to be 0.2 mm. It is then pre-baked at 60℃-80℃ for 10-15 minutes to obtain the gradient porous prepreg. The aerogel precursor dispersion is uniformly sprayed onto the surface of the gradient porous prepreg core layer, with the spraying amount controlled at 10 g / m³. 2 -12g / m 2 After standing at room temperature for 5-10 minutes, a gradient porous composite prepreg is obtained.
[0009] Furthermore, the base slurry accounts for 25%-30% of the total matrix slurry, and the core layer slurry accounts for 70%-75% of the total matrix slurry.
[0010] Furthermore, the mass ratio of the core layer slurry to the matrix slurry and the pore-forming agent is 9-12:1.
[0011] Furthermore, the micro-etching solution is a sulfuric acid solution with a mass fraction of 5%-8%.
[0012] Furthermore, the mass fraction of the methyltriethoxysilane ethanol solution is 2%.
[0013] Furthermore, the parameters of the hot press during the hot pressing curing process in step S4 are: heating rate of 2℃ / min to 120℃, pressure of 1.5MPa, and holding time of 60min-80min.
[0014] Furthermore, in step S4, the copper composite plate is immersed in deionized water at a temperature of 80℃-90℃ for 2-3 hours, followed by drying at 110℃-130℃ for 40-60 minutes.
[0015] Further, the raw materials in the matrix slurry are as follows by weight: 30-40 parts modified cellulose, 60-80 parts polyether ether ketone, 100-150 parts N,N-dimethylacetamide, 1-2 parts dicumyl peroxide, and 0.5-1 parts anti-settling agent, wherein the anti-settling agent is fumed silica.
[0016] Furthermore, the modified cellulose is prepared as follows: Microcrystalline cellulose was added to anhydrous ethanol, followed by hydrochloric acid solution. After stirring and dispersing, the mixture was heated, and propyltrimethoxysilane was added while stirring. After the addition of propyltrimethoxysilane was complete, the reaction continued. After the reaction was completed, the mixture was washed and dried to obtain modified cellulose.
[0017] Furthermore, the specific preparation method of the modified cellulose is as follows: Microcrystalline cellulose was added to anhydrous ethanol, followed by hydrochloric acid solution. The stirring speed was controlled at 200 rpm-400 rpm. After stirring for 10 min-20 min, the temperature was raised to 50℃-70℃. Propyltrimethoxysilane was added while stirring. After the addition of propyltrimethoxysilane was completed, the stirring speed and temperature were kept constant, and the reaction was continued for 2 h-5 h. After the reaction was completed, the product was washed 2-3 times with anhydrous ethanol and dried under vacuum at 60℃-80℃ for 4 h-6 h to obtain modified cellulose.
[0018] Furthermore, the mass ratio of the microcrystalline cellulose, propyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid solution is 30:4-5:60-70:5-12.
[0019] Furthermore, the hydrochloric acid solution has a mass fraction of 1%-3%.
[0020] Furthermore, the pore-forming agent is polylactic acid microspheres, and the preparation method of the polylactic acid microspheres is as follows: Polylactic acid was added to dichloromethane and stirred to dissolve, forming an oil phase. Polyvinyl alcohol was added to deionized water and stirred to dissolve, forming an aqueous phase. The oil phase was added to the aqueous phase and stirred to emulsify, resulting in an emulsion. The emulsion was then subjected to rotary evaporation, centrifugation, washing, and drying to obtain polylactic acid microspheres.
[0021] Furthermore, the specific preparation method of the polylactic acid microspheres is as follows: Polylactic acid was added to dichloromethane and stirred to dissolve, forming an oil phase. Polyvinyl alcohol was added to deionized water and stirred to dissolve, forming an aqueous phase. The oil phase was added to the aqueous phase, and the temperature was raised to 40℃-50℃. The stirring speed was controlled at 200rpm-300rpm, and the mixture was stirred and emulsified for 30min-50min to obtain an emulsion. The emulsion was then rotary evaporated at 50℃-60℃ for 2h-3h, centrifuged, washed 2-3 times with deionized water, and dried at 60℃-70℃ for 4h-6h to obtain polylactic acid microspheres.
[0022] Furthermore, the mass ratio of polylactic acid, dichloromethane, polyvinyl alcohol, and deionized water is 1:8-12:0.5-1:4-6.
[0023] Furthermore, the molecular weight of the polyvinyl alcohol is 4000-8000.
[0024] Furthermore, the preparation method of the aerogel precursor dispersion is as follows: Under nitrogen protection, N,N-dimethylacetamide, hexafluorodianhydride, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly, heated and stirred, and trifluoromethyl propylene oxide was added while stirring. After cooling, an aerogel precursor dispersion was obtained.
[0025] Furthermore, the specific preparation method of the aerogel precursor dispersion is as follows: Under nitrogen protection, N,N-dimethylacetamide, hexafluorodianhydride, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly with a stirring speed of 300-600 rpm. The mixture was heated to 50-60°C and stirred for 30-50 minutes. Trifluoromethyl propylene oxide was added while stirring, and stirring was continued for 15-30 minutes. After cooling, an aerogel precursor dispersion was obtained.
[0026] Further, the mass ratio of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, hexafluorodianhydride, N,N-dimethylacetamide and trifluoromethyl propylene oxide is 5:5-6:80-120:0.5-1.
[0027] On the other hand, the present invention provides a low dielectric constant copper clad laminate, which is made by the above-mentioned method for preparing a low dielectric constant copper clad laminate.
[0028] The beneficial effects of this invention are: This invention significantly reduces the dielectric constant and dielectric loss of copper-clad laminates through the synergistic effect of a gradient porous structure (dense bottom layer + high-porosity core layer) and a fluorine-based aerogel coating, thus meeting the stringent requirements of 5G high-frequency signal transmission for low latency and low loss.
[0029] The modified cellulose-reinforced skeleton and gradient pore design work together to suppress Z-axis thermal expansion, while the dense underlying structure provides rigid support, avoiding the mechanical property degradation problem common in porous materials and ensuring the dimensional stability of the copper-clad laminate during thermal cycling.
[0030] This invention uses polylactic acid microspheres as a pore-forming agent and achieves precise degradation and pore formation through temperature control, avoiding the ion residue problem of traditional chemical foaming agents. At the same time, it achieves precise control of porosity and distribution, ensuring the consistency of dielectric properties. Detailed Implementation
[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] In this embodiment of the invention, the polyetheretherketone was purchased from Jilin Zhongyan Polymer Materials Co., Ltd., and the model was PF series-330PF.
[0033] In this embodiment of the invention, the fumed silica was purchased from Zhejiang Yamei Nanotechnology Co., Ltd., and the model number is AM-SiO2-001-1.
[0034] Example 1 A method for preparing a low dielectric constant copper clad laminate includes the following preparation steps: Preparation of modified cellulose: 30 parts of microcrystalline cellulose were added to 60 parts of anhydrous ethanol, and 12 parts of 1% hydrochloric acid solution were added. The stirring speed was controlled at 200 rpm and stirred for 10 min. The temperature was then raised to 50℃, and 4 parts of propyltrimethoxysilane were added while stirring. The reaction was continued for 2 h while keeping the stirring speed and temperature constant. After the reaction was completed, the product was washed twice with anhydrous ethanol and dried under vacuum at 60℃ for 4 h to obtain modified cellulose.
[0035] Preparation of polylactic acid microspheres: 1 part polylactic acid was added to 8 parts dichloromethane and stirred to dissolve to form an oil phase. 0.5 parts polyvinyl alcohol with a molecular weight of 4000 was added to 4 parts deionized water and stirred to dissolve to form an aqueous phase. The oil phase was added to the aqueous phase, the temperature was raised to 40℃, the stirring speed was controlled at 200 rpm, and the mixture was stirred and emulsified for 30 min to obtain an emulsion. The emulsion was then evaporated at 50℃ for 2 h, centrifuged, washed twice with deionized water, and dried at 60℃ for 4 h to obtain polylactic acid microspheres.
[0036] Preparation of aerogel precursor dispersion: Under nitrogen protection, 80 parts of N,N-dimethylacetamide, 5 parts of hexafluorodianhydride, and 5 parts of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly, and the stirring speed was controlled at 300 rpm. The mixture was heated to 50℃ and stirred for 30 min. While stirring, 0.5 parts of trifluoromethyl propylene oxide were added. The stirring speed and temperature were kept constant, and stirring was continued for 15 min. After cooling, the aerogel precursor dispersion was obtained.
[0037] S1: Mix 30 parts modified cellulose, 60 parts polyetheretherketone and 100 parts N,N-dimethylacetamide, heat to 70℃, stir at 600 rpm for 20 min, add 1 part dicumyl peroxide and 0.5 parts fumed silica, maintain the temperature and speed, and continue stirring for 30 min to obtain the matrix slurry.
[0038] S2: Take 25% of the matrix slurry as the bottom layer slurry and coat it evenly on the PET release film. Control the wet film thickness of the bottom layer slurry to be 0.1 mm. Pre-bake at 60℃ for 10 min to obtain the bottom layer prepreg. The remaining 75% of the matrix slurry is used as the core layer slurry. Add polylactic acid microspheres to the core layer slurry. The mass ratio of core layer slurry to polylactic acid microspheres is 9:1. Stir evenly to obtain the core layer prepreg slurry. Coat it on the bottom layer prepreg. The wet film thickness of the core layer prepreg slurry is 0.2 mm. Pre-bake at 60℃ for 10 min to obtain the gradient porous prepreg. Add the aerogel precursor dispersion at 10 g / m³. 2 The amount of material is evenly sprayed onto the surface of the core layer and left to stand at room temperature for 5 minutes to obtain a gradient porous composite prepreg.
[0039] S3: Immerse an 18μm thick electrolytic copper foil in a 6% hydrochloric acid solution for micro-etching for 75 seconds, then immerse it in a 2% methyltriethoxysilane ethanol solution for 6 minutes, and finally dry it at 70℃ for 8 minutes to obtain the pretreated electrolytic copper foil.
[0040] S4: In the hot press, release film, pretreated electrolytic copper foil, gradient porous composite prepreg, pretreated electrolytic copper foil, and release film are laid sequentially on the template. Before hot pressing and curing, the release film of the gradient porous composite prepreg needs to be peeled off to ensure the alignment between layers. Hot pressing and curing parameters: heating rate 2℃ / min to 120℃, pressure 1.5MPa, heat preservation for 60min, and after cooling to room temperature, the release film is peeled off to obtain a copper composite board. The copper composite board is immersed in 80℃ deionized water for 2h and dried at 110℃ for 40min to obtain a low dielectric constant copper clad laminate.
[0041] Example 2 A method for preparing a low dielectric constant copper clad laminate includes the following preparation steps: Preparation of modified cellulose: 30 parts of microcrystalline cellulose were added to 65 parts of anhydrous ethanol, and 10 parts of 2% hydrochloric acid solution were added. The stirring speed was controlled at 300 rpm and stirred for 15 min. Then the temperature was raised to 60℃, and 4.5 parts of propyltrimethoxysilane were added while stirring. The stirring speed and temperature were kept constant and the reaction was continued for 3.5 h. After the reaction was completed, the product was washed three times with anhydrous ethanol and dried under vacuum at 70℃ for 5 h to obtain modified cellulose.
[0042] Preparation of polylactic acid microspheres: 1 part polylactic acid was added to 10 parts dichloromethane and stirred to dissolve to form an oil phase. 0.75 parts polyvinyl alcohol with a molecular weight of 6000 was added to 5 parts deionized water and stirred to dissolve to form an aqueous phase. The oil phase was added to the aqueous phase, the temperature was raised to 45℃, the stirring speed was controlled at 250 rpm, and the mixture was stirred and emulsified for 40 min to obtain an emulsion. The emulsion was then evaporated at 55℃ for 2.5 h, centrifuged, washed three times with deionized water, and dried at 65℃ for 5 h to obtain polylactic acid microspheres.
[0043] Preparation of aerogel precursor dispersion: Under nitrogen protection, 100 parts of N,N-dimethylacetamide, 5.5 parts of hexafluorodianhydride, and 5 parts of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly, and the stirring speed was controlled at 450 rpm. The mixture was heated to 55℃ and stirred for 40 min. While stirring, 0.75 parts of trifluoromethyl propylene oxide were added. The stirring speed and temperature were kept constant, and stirring was continued for 22 min. After cooling, the aerogel precursor dispersion was obtained.
[0044] S1: Mix 35 parts modified cellulose, 70 parts polyetheretherketone and 125 parts N,N-dimethylacetamide, heat to 75℃, stir at 800 rpm for 30 min, add 1.5 parts dicumyl peroxide and 0.75 parts fumed silica, maintain the temperature and speed, and continue stirring for 40 min to obtain the matrix slurry.
[0045] S2: Take 27% of the matrix slurry as the bottom layer slurry and coat it evenly on the PET release film. Control the wet film thickness of the bottom layer slurry to be 0.1 mm. Pre-bake at 70℃ for 14 min to obtain the bottom layer prepreg. The remaining 73% of the matrix slurry is used as the core layer slurry. Add polylactic acid microspheres to the core layer slurry. The mass ratio of the core layer slurry to the polylactic acid microspheres is 10:1. Stir evenly to obtain the core layer prepreg slurry. Coat it on the bottom layer prepreg. The wet film thickness of the core layer prepreg slurry is 0.2 mm. Pre-bake at 70℃ for 12 min to obtain the gradient porous prepreg. Add the aerogel precursor dispersion at 11 g / m³. 2 The amount of material is evenly sprayed onto the surface of the core layer and left to stand at room temperature for 7 minutes to obtain a gradient porous composite prepreg.
[0046] S3: Immerse an 18μm thick electrolytic copper foil in an 8% hydrochloric acid solution for micro-etching for 60 seconds, then immerse it in a 2% methyltriethoxysilane ethanol solution for 4 minutes, and finally dry it at 75°C for 10 minutes to obtain the pretreated electrolytic copper foil.
[0047] S4: In a hot press, release film, pretreated electrolytic copper foil, gradient porous composite prepreg, pretreated electrolytic copper foil, and release film are laid sequentially on a template. Before hot pressing and curing, the release film of the gradient porous composite prepreg needs to be peeled off to ensure the alignment between layers. Hot pressing and curing parameters: heating rate 2℃ / min to 120℃, pressure 1.5MPa, holding temperature for 70min, and after cooling to room temperature, the release film is peeled off to obtain a copper composite board. The copper composite board is immersed in 85℃ deionized water for 2.5h and dried at 120℃ for 50min to obtain a low dielectric constant copper clad laminate.
[0048] Example 3 A method for preparing a low dielectric constant copper clad laminate includes the following preparation steps: Preparation of modified cellulose: 30 parts of microcrystalline cellulose were added to 70 parts of anhydrous ethanol, and 5 parts of 3% hydrochloric acid solution were added. The stirring speed was controlled at 400 rpm and stirred for 20 min. Then the temperature was raised to 70℃, and 5 parts of propyltrimethoxysilane were added while stirring. The stirring speed and temperature were kept constant and the reaction was continued for 5 h. After the reaction was completed, the product was washed 3 times with anhydrous ethanol and dried under vacuum at 80℃ for 6 h to obtain modified cellulose.
[0049] Preparation of polylactic acid microspheres: 1 part polylactic acid was added to 12 parts dichloromethane and stirred to dissolve to form an oil phase. 1 part polyvinyl alcohol with a molecular weight of 8000 was added to 6 parts deionized water and stirred to dissolve to form an aqueous phase. The oil phase was added to the aqueous phase, the temperature was raised to 50℃, the stirring speed was controlled at 300 rpm, and the mixture was stirred and emulsified for 50 min to obtain an emulsion. The emulsion was then rotary evaporated at 60℃ for 3 h, centrifuged, washed 3 times with deionized water, and dried at 70℃ for 6 h to obtain polylactic acid microspheres.
[0050] Preparation of aerogel precursor dispersion: Under nitrogen protection, 120 parts of N,N-dimethylacetamide, 6 parts of hexafluorodianhydride, and 5 parts of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly, and the stirring speed was controlled at 600 rpm. The mixture was heated to 60℃ and stirred for 50 min. While stirring, 1 part of trifluoromethyl propylene oxide was added. The stirring speed and temperature were kept constant, and stirring was continued for 30 min. After cooling, the aerogel precursor dispersion was obtained.
[0051] S1: Mix 40 parts modified cellulose, 80 parts polyether ether ketone and 150 parts N,N-dimethylacetamide, heat to 80℃, stir at 1000 rpm for 40 min, add 2 parts dicumyl peroxide and 1 part fumed silica, maintain temperature and speed unchanged, continue stirring for 50 min to obtain matrix slurry.
[0052] S2: Take 30% of the matrix slurry as the bottom layer slurry and coat it evenly on the PET release film. Control the wet film thickness of the bottom layer slurry to be 0.1 mm. Pre-bake at 80℃ for 18 min to obtain the bottom layer prepreg. The remaining 70% of the matrix slurry is used as the core layer slurry. Add polylactic acid microspheres to the core layer slurry. The mass ratio of the core layer slurry to the polylactic acid microspheres is 12:1. Stir evenly to obtain the core layer prepreg slurry. Coat it on the bottom layer prepreg. The wet film thickness of the core layer prepreg slurry is 0.2 mm. Pre-bake at 80℃ for 15 min to obtain the gradient porous prepreg. Add the aerogel precursor dispersion at 12 g / m³. 2 The amount of material is evenly sprayed onto the surface of the core layer and left to stand at room temperature for 10 minutes to obtain a gradient porous composite prepreg.
[0053] S3: Immerse an 18μm thick electrolytic copper foil in a 10% hydrochloric acid solution for micro-etching for 40 seconds. After removal, immerse it in a 2% methyltriethoxysilane ethanol solution for 5 minutes. After removal, dry it at 80℃ for 12 minutes to obtain the pretreated electrolytic copper foil.
[0054] S4: In the hot press, release film, pretreated electrolytic copper foil, gradient porous composite prepreg, pretreated electrolytic copper foil, and release film are laid sequentially on the template to ensure layer alignment. The release film of the gradient porous composite prepreg needs to be peeled off before hot pressing and curing. Hot pressing and curing parameters: heating rate 2℃ / min to 120℃, pressure 1.5MPa, heat preservation for 80min, and after cooling to room temperature, the release film is peeled off to obtain a copper composite board. The copper composite board is immersed in 90℃ deionized water for 3h and dried at 130℃ for 60min to obtain a low dielectric constant copper clad laminate.
[0055] Comparative Example 1 Compared with Example 1, this comparative example replaces "modified cellulose" with the same mass of "microcrystalline cellulose". All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a copper-clad laminate with low dielectric constant.
[0056] Comparative Example 2 Compared with Example 1, this comparative example replaces "polylactic acid microspheres" with the same mass of "sodium bicarbonate". All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a copper-clad laminate with low dielectric constant.
[0057] Comparative Example 3 Compared with Example 1, this comparative example omits the aerogel precursor spraying step, while the remaining steps and parameters are the same. This comparative example will not be repeated here. The final result is a copper-clad laminate with low dielectric constant.
[0058] Comparative Example 4 Compared with Example 1, this comparative example eliminates the gradient structure, adds polylactic acid microspheres to the bottom slurry, and the mass ratio of the bottom slurry to the polylactic acid microspheres is 9:1. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, a copper clad laminate with low dielectric constant is obtained.
[0059] The low dielectric constant copper clad laminates prepared in Examples 1-3 and Comparative Examples 1-4 were tested, and the detailed test results are shown in Table 1.
[0060] Table 1
[0061] According to the analysis of test data, the low dielectric constant copper clad laminates prepared in Examples 1-3 of this invention have the advantages of ultra-low dielectric constant, excellent dimensional stability, high interfacial bonding force and low water absorption.
[0062] Comparing Comparative Example 1 and Example 1, it can be seen that when "modified cellulose" is replaced with "microcrystalline cellulose" of the same mass, the unmodified microcrystalline cellulose contains a large number of hydrophilic hydroxyl groups, which leads to increased water adsorption, increased dielectric constant, poor interfacial compatibility, pore aggregation, and decreased binding force under humid and hot conditions.
[0063] Comparing Comparative Example 2 and Example 1, it can be seen that Z-CTE increases and peel strength decreases. This is because the decomposition temperature of sodium bicarbonate is difficult to control, the uneven release of decomposition gas leads to pore collapse, residual sodium ions increase dielectric loss, and insufficient support of the bottom layer exacerbates thermal expansion.
[0064] Comparing Comparative Example 3 and Example 1, it can be seen that the peel strength decreased, the Z-CTE increased, the lack of aerogel interface layer led to direct exposure of the porous layer, the moisture absorption and expansion were aggravated, and the high-frequency signal was scattered at the edge of the pores.
[0065] Comparing Comparative Example 4 and Example 1, it can be seen that Dk increases, Df increases, and Z-CTE increases. After the gradient structure is removed, the bottom layer becomes loose and loses its supporting function. During hot pressing, the pores collapse, resulting in uneven density. The Z-axis expansion is suppressed by an unconstrained layer.
[0066] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.
Claims
1. A method for preparing a low dielectric constant copper-clad laminate, characterized in that, The preparation steps include the following: S1: Mix modified cellulose, polyether ether ketone and N,N-dimethylacetamide evenly, add dicumyl peroxide and anti-settling agent, and continue to mix evenly to obtain a uniform matrix slurry; S2: Take a portion of the matrix slurry as the base slurry, coat it evenly on the PET release film, and pre-bake to obtain the bottom prepreg; take the remaining matrix slurry as the core layer slurry, add a pore-forming agent to the core layer slurry, stir evenly to obtain the core layer prepreg slurry; coat the core layer prepreg slurry on the bottom prepreg, pre-bake to obtain the gradient porous prepreg; spray the aerogel precursor dispersion evenly on the surface of the gradient porous prepreg core layer, let it stand, and obtain the gradient porous composite prepreg; S3: Immerse the electrolytic copper foil in a micro-etching solution for micro-etching treatment. After micro-etching treatment, immerse the electrolytic copper foil in a methyltriethoxysilane ethanol solution for soaking treatment. After taking it out, dry it to obtain pre-treated electrolytic copper foil. S4: In a hot press, release film, pretreated electrolytic copper foil, gradient porous composite prepreg, pretreated electrolytic copper foil, and release film are laid sequentially on a template to ensure layer alignment. After hot pressing and curing, and cooling to room temperature, the release film is peeled off to obtain a copper composite board. The copper composite board is then immersed in deionized water for soaking treatment, and after being taken out and dried, a low dielectric constant copper-clad laminate is obtained.
2. The method for preparing a low dielectric constant copper-clad laminate according to claim 1, characterized in that, The raw materials in the matrix slurry are as follows by weight: 30-40 parts modified cellulose, 60-80 parts polyether ether ketone, 100-150 parts N,N-dimethylacetamide, 1-2 parts dicumyl peroxide, and 0.5-1 parts anti-settling agent, wherein the anti-settling agent is fumed silica.
3. The method for preparing a low dielectric constant copper-clad laminate according to claim 1, characterized in that, The base slurry accounts for 25%-30% of the total base slurry, the core slurry accounts for 70%-75% of the total base slurry, and the micro-etching solution is a sulfuric acid solution with a mass fraction of 5%-8%.
4. The method for preparing a low dielectric constant copper-clad laminate according to claim 1, characterized in that, The modified cellulose is prepared as follows: Microcrystalline cellulose was added to anhydrous ethanol, followed by hydrochloric acid solution. After stirring and dispersing, the mixture was heated, and propyltrimethoxysilane was added while stirring. After the addition of propyltrimethoxysilane was complete, the reaction continued. After the reaction was completed, the mixture was washed and dried to obtain modified cellulose.
5. The method for preparing a low dielectric constant copper-clad laminate according to claim 4, characterized in that, The mass ratio of the microcrystalline cellulose, propyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid solution is 30:4-5:60-70:5-12.
6. The method for preparing a low dielectric constant copper-clad laminate according to claim 1, characterized in that, The pore-forming agent is polylactic acid microspheres, and the preparation method of the polylactic acid microspheres is as follows: Polylactic acid was added to dichloromethane and stirred to dissolve, forming an oil phase. Polyvinyl alcohol was added to deionized water and stirred to dissolve, forming an aqueous phase. The oil phase was added to the aqueous phase and stirred to emulsify, resulting in an emulsion. The emulsion was then subjected to rotary evaporation, centrifugation, washing, and drying to obtain polylactic acid microspheres.
7. The method for preparing a low dielectric constant copper-clad laminate according to claim 6, characterized in that, The mass ratio of polylactic acid, dichloromethane, polyvinyl alcohol, and deionized water is 1:8-12:0.5-1:4-6.
8. The method for preparing a low dielectric constant copper-clad laminate according to claim 1, characterized in that, The preparation method of the aerogel precursor dispersion is as follows: Under nitrogen protection, N,N-dimethylacetamide, hexafluorodianhydride, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl were mixed evenly, heated and stirred, and trifluoromethyl propylene oxide was added while stirring. After cooling, an aerogel precursor dispersion was obtained.
9. The method for preparing a low dielectric constant copper-clad laminate according to claim 8, characterized in that, The mass ratio of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, hexafluorodianhydride, N,N-dimethylacetamide and trifluoromethyl propylene oxide is 5:5-6:80-120:0.5-1.
10. A low dielectric constant copper-clad laminate, characterized in that, It is made by the method for preparing a low dielectric constant copper clad laminate as described in any one of claims 1-9.