A copper foil surface micro-texture treatment and laminating process for low thermal expansion high-frequency copper-clad plate

Abstract

This invention discloses a microtexturing treatment and lamination process for the copper foil surface of a low-thermal-expansion high-frequency copper-clad laminate (CCL). Belonging to the field of CCL manufacturing technology, it solves problems in existing CCL technologies, such as the difficulty in balancing peel strength and high-frequency transmission performance, excessively high coefficient of thermal expansion, easy delamination between layers, and patent conflicts. This invention employs a combined plasma etching and chemical micro-etching process to prepare a honeycomb-like pit-column-protrusion composite microtexture on the resin-coated surface of the substrate copper foil. After modification with a fluorine-containing and aminosilane coupling agent and mixed passivation treatment, a surface-modified copper foil is obtained. This foil is then laminated with a low-thermal-expansion high-frequency prepreg containing linear polyarylamide through a segmented preheating, gradual pressure curing, and slow cooling and depressurization process to prepare the CCL. This invention features a simple process, conforms to industrial practice, exhibits excellent overall performance, effectively avoids patent conflicts, and is suitable for high-end fields such as 5G communication and AI servers.

Description

Technical Field

[0001] This invention belongs to the field of copper clad laminate manufacturing technology, specifically relating to a microtexturation treatment and lamination process for the copper foil surface of a low thermal expansion high-frequency copper clad laminate. Background Technology

[0002] The high-frequency performance of copper-clad laminates (CCLs) primarily depends on the resin substrate and the surface condition of the copper foil, while low thermal expansion performance is closely related to the resin system, reinforcing materials, and lamination process. As the conductive layer of the CCL, the surface roughness of the copper foil directly affects its bonding strength with the resin (peel strength) and high-frequency transmission performance. An excessively rough surface exacerbates the skin effect of high-frequency signals, increasing conductor loss; an excessively smooth surface reduces the anchoring effect with the resin, making delamination more likely. In existing technologies, copper foil surface treatments often employ single chemical roughening, electrolytic roughening, or plasma etching processes, resulting in single-protrusion or single-pit structures that are difficult to balance peel strength and high-frequency transmission performance. For example, some patents use a single roughening treatment to obtain low-profile copper foil, which can reduce insertion loss, but the improvement in peel strength is limited, making it difficult to meet the reliability requirements of high-density integrated CCLs.

[0003] For example, CN 109601025 A discloses a copper-clad laminate that enhances the adhesion strength with resin and reduces insertion loss by controlling the roughness and thickness of the copper layer. However, this technology uses a single roughened surface, does not form a composite microtexture, and is not optimized for low thermal expansion performance, making it difficult to meet the low thermal expansion requirements of high-end fields such as AI servers. CN114369268 A discloses a low thermal expansion high-frequency copper-clad laminate that prepares a prepreg by mixing a fluorinated resin mixture with fiber cloth. Although it can reduce the coefficient of thermal expansion, the copper foil surface is not specifically modified, the lamination process does not achieve segmented preheating and uniform speed control, and the interlayer bonding reliability is insufficient.

[0004] Therefore, developing a copper foil surface microtexturing treatment and lamination process that can take into account peel strength, high-frequency transmission performance and low thermal expansion performance, and is significantly different from existing technologies, avoids patent conflicts, and conforms to the actual industrial production has become an urgent technical problem to be solved in the current copper clad laminate field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a microtexturing treatment and lamination process for the copper foil surface of low thermal expansion high-frequency copper-clad laminates. By designing a unique composite microtexture on the copper foil surface and optimizing the synergistic effect of the microtexturing treatment process and the lamination process, the invention solves the problems in existing technologies, such as the difficulty in balancing the peel strength and high-frequency transmission performance of copper-clad laminates, excessively high thermal expansion coefficient, and easy delamination and warping between layers. At the same time, it avoids the key points of existing patented technologies, achieving a unity of technological innovation and industrial feasibility.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A microtexturing process for the copper foil surface of a low thermal expansion high-frequency copper-clad laminate includes the following steps:

[0008] S1. Copper Foil Pretreatment: Electrolytic copper foil or rolled copper foil is selected as the base copper foil and subjected to degreasing, pickling, water washing and drying in sequence to remove oil, oxide layer and impurities on the surface of the base copper foil, so as to provide a clean and flat surface for subsequent microtexture preparation; the thickness of the base copper foil is 6-35μm, the tensile strength is ≥300MPa, the elongation is ≥8%, and it has good conductivity and mechanical properties, which is suitable for the thinning requirements of high frequency copper clad laminates.

[0009] S2. Microtexture Preparation: A composite process of plasma etching and chemical micro-etching is used to prepare a periodically interlaced "honeycomb-column protrusion" composite microtexture on the resin-coated surface of the substrate copper foil. The unique structure of the composite microtexture increases the contact area and anchoring effect between the copper foil and the resin, while avoiding the aggravation of high-frequency losses caused by a single rough structure. The plasma etching uses a mixture of argon and oxygen in a volume ratio of 5:1-2. Argon can play a physical bombardment role, while oxygen can form a slight oxide layer on the copper foil surface, enhancing the selectivity of subsequent chemical micro-etching. The chemical micro-etching uses a mixed micro-etching solution of copper sulfate and sulfuric acid, which can further prepare uniform honeycomb-shaped pits and columnar protrusions on the base surface formed by plasma etching. The microtexture size can be precisely controlled by adjusting the micro-etching parameters. In the composite microtexture, the honeycomb-shaped pits have a pore size of 0.3-1.2 μm, a depth of 0.1-0.4 μm, and a center-to-center distance between adjacent pits of 0.8-2.0 μm; the columnar protrusions have a height of 0.2-0.5 μm and a diameter of 0.1-0.3 μm, and are uniformly distributed on the inner wall of the honeycomb-shaped pits and in the gaps between the pits.

[0010] S3. Microtexture Post-treatment: The prepared composite microtextured copper foil is sequentially modified with a silane coupling agent, dried, and passivated to further enhance the chemical activity and corrosion resistance of the copper foil surface, strengthen the interfacial bonding strength with the resin, and extend the storage period of the copper foil. The silane coupling agent is a compound system of fluorinated silane coupling agent and aminosilane coupling agent with a mass ratio of 1:2-3. The fluorinated silane coupling agent can improve the hydrophobicity and high-frequency compatibility of the copper foil surface, while the aminosilane coupling agent can enhance the chemical bonding with the resin. The compound use can achieve synergistic effect. The passivation treatment uses a mixed passivation solution of chromate and phosphate, which can form a dense passivation film on the copper foil surface, improve corrosion resistance, and does not affect the bonding with the resin.

[0011] The present invention also provides a surface-modified copper foil prepared by the above-mentioned processing technology. The surface-modified copper foil has an arithmetic mean roughness Ra of 0.15-0.35 μm on the resin-coated surface and a peel strength to the resin ≥1.0 N / mm. These performance parameters ensure both low conductor loss during high-frequency transmission and good bonding with the resin, while avoiding the limitation of a single roughness range in existing patents.

[0012] A lamination process for low thermal expansion high-frequency copper-clad laminates involves laminating the aforementioned surface-modified copper foil with a low thermal expansion high-frequency prepreg. The specific steps are as follows:

[0013] A. Lamination Preparation: Select a low thermal expansion high-frequency prepreg and cut it to a size that matches the surface-modified copper foil. Align the resin-coated side of the surface-modified copper foil with one or both sides of the prepreg to form a laminated blank. The low thermal expansion high-frequency prepreg is prepared from a fluorinated resin mixture, low thermal expansion fiber cloth, and inorganic fillers. The fluorinated resin mixture contains 5-50 wt% of linear polyarylamide with a benzo[4]-4-membered ring structure, which can significantly reduce the thermal expansion coefficient of the prepreg while ensuring high-frequency performance.

[0014] The low thermal expansion fiber cloth is one of electronic grade alkali-free glass fiber cloth, carbon fiber or polyimide fiber cloth. Among them, carbon fiber and polyimide fiber cloth have extremely low coefficients of thermal expansion, which can further optimize the low thermal expansion performance of copper clad laminate. The inorganic filler is one or more of SiO2, Al2O3 or BN, and the addition amount is 15-30% of the mass of the fluorinated resin mixture. The inorganic filler can work synergistically with the resin system to reduce the coefficient of thermal expansion, while improving the mechanical properties and heat resistance of copper clad laminate.

[0015] The fluorinated resin mixture includes a fluorinated resin emulsion, a linear polyarylamide with a benzo[4]-4-membered ring structure, a coupling agent, and a flame retardant. The fluorinated resin emulsion is one or more of polytetrafluoroethylene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, which has excellent high-frequency performance. The coupling agent can improve the dispersibility and bonding strength between the inorganic filler and the resin, and the flame retardant can meet the flame retardant requirements of copper clad laminates.

[0016] B. Preheating treatment: The laminated preform is placed in the laminator and preheated in stages. The first stage preheating temperature is 80-100℃, and the second stage preheating temperature is 120-140℃. Stage preheating can remove moisture and volatiles from the laminated preform, and at the same time soften the resin of the prepreg, avoiding uneven resin flow caused by subsequent rapid heating, ensuring that the laminated preform is tightly bonded and reducing the gap between layers.

[0017] C. Pressure Curing: After preheating, gradually increase the temperature and pressure of the laminator until the temperature reaches 180-200℃ and the pressure reaches 2.5-3.5MPa. Under these conditions, maintain the temperature and pressure for 30-45 minutes to allow the resin to fully cure and crosslink, forming a dense interlayer bond. During the pressure curing process, an inert protective gas is simultaneously introduced to prevent the copper foil from being oxidized during high-temperature curing, while also removing volatiles generated during the curing process, reducing interlayer bubbles, and improving the density of the copper-clad laminate.

[0018] D. Cooling and Demolding: After curing, gradually cool down and release pressure to obtain a low thermal expansion high-frequency copper-clad laminate after demolding; slow cooling and pressure release can release interlayer stress and avoid warping of the copper-clad laminate.

[0019] This invention also provides a low thermal expansion high-frequency copper-clad laminate prepared using the above-mentioned lamination process. The copper-clad laminate has an X / Y axis thermal expansion coefficient of 2.8-5.0 ppm / ℃, which has good thermal matching with silicon chips (CTE approximately 2.6 ppm / ℃) and can effectively alleviate thermal stress; the Z axis thermal expansion coefficient is 25-35 ppm / ℃, avoiding interlayer peeling; the dielectric constant is ≤3.2 and the dielectric loss is ≤0.003 at 25℃ and 10GHz frequency, exhibiting excellent high-frequency transmission performance; the peel strength is ≥1.0 N / mm and the heat resistance temperature is ≥260℃. The mechanical and heat resistance properties meet the requirements of high-end electronic devices, and the various performance parameters are significantly different from those of existing patents, effectively avoiding patent conflicts.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention employs a combined plasma etching and chemical micro-etching process to prepare a composite microtexture of "honeycomb-column protrusions". Unlike the single roughening structure in the prior art, the composite microtexture increases the contact area through honeycomb-shaped pits and enhances the anchoring effect and peel strength through columnar protrusions. It also avoids the aggravation of high-frequency loss by precisely controlling the roughness range. At the same time, the dimensional parameters of the microtexture are completely different from those of existing patents, which can effectively avoid patent conflicts.

[0022] 2. This invention improves the interfacial bonding strength between copper foil and resin through compound modification with silane coupling agents; the lamination process adopts a segmented preheating and slow temperature and pressure increase mode, combined with inert gas protection, to reduce interlayer bubbles and internal stress, and avoid warping and delamination of copper clad laminate; at the same time, the low thermal expansion prepreg has good compatibility with surface modified copper foil, so that the prepared copper clad laminate has the advantages of low thermal expansion, high frequency transmission and high peel strength, meeting the stringent requirements of high-end electronic devices.

[0023] 3. Through passivation treatment with a mixture of chromate and phosphate, a dense passivation film is formed on the surface of the copper foil, which effectively improves the corrosion resistance of the copper foil and extends the storage period. At the same time, the coupling agent modification layer can enhance the chemical bonding between the copper foil and the resin, improve the long-term stability of the copper-clad laminate. After 500 cycles of thermal cycling at -40℃ to 85℃, there is no delamination or warping, and the signal stability does not decrease significantly. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of the low thermal expansion high frequency copper-clad laminate of the present invention.

[0026] In the figure: 1-Surface modified copper foil; 2-Low thermal expansion high-frequency semi-cured sheet; 3-Honeycomb pits; 4-Columnar protrusions; 5-Passivation film; 6-Coupling agent modified layer. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0028] Example 1

[0029] A microtextured treatment and lamination process for the copper foil surface of a low thermal expansion high-frequency copper-clad laminate, the specific steps of which are as follows:

[0030] 1. Copper foil surface microtexturing treatment process

[0031] S1. Copper foil pretreatment: Select electrolytic copper foil with a thickness of 12μm (tensile strength 320MPa, elongation 9%) as the base copper foil, and process it in sequence through degreasing, pickling, water washing and drying to remove surface oil, oxide layer and impurities.

[0032] S2. Microtexture preparation: A plasma etching machine was used to etch a mixture of argon and oxygen (volume ratio 5:1.5). After etching, the copper foil was placed in a mixed micro-etching solution of copper sulfate and sulfuric acid for micro-etching. After washing with water, a composite microtexture of "honeycomb pits-column protrusions" was obtained. The honeycomb pits had a pore size of 0.7 μm, a depth of 0.25 μm, and a center-to-center distance of 1.4 μm between adjacent pits. The columnar protrusions had a height of 0.35 μm and a diameter of 0.2 μm.

[0033] S3. Microtexture post-treatment: The copper foil is modified by immersing it in a compound silane coupling agent solution (containing fluorinated silane coupling agent and aminosilane coupling agent in a mass ratio of 1:2.5). After washing and drying, it is passivated by immersing it in a mixed passivation solution of chromate and phosphate. After washing and drying, the surface-modified copper foil is obtained.

[0034] 2. Lamination process

[0035] A. Lamination Preparation: Select a low thermal expansion high frequency prepreg (25wt% linear polyarylamide with a benzo4-membered ring structure added to a fluorinated resin mixture, 22% SiO2 added as inorganic filler, and electronic grade alkali-free fiber cloth), cut it to a size that matches the surface-modified copper foil, and stack the resin-coated side of the surface-modified copper foil with both sides of the prepreg to form a laminate blank.

[0036] B. Preheating treatment: The laminated preform is placed in a laminator for segmented preheating, with the first stage at 85°C and the second stage at 130°C, to complete the segmented preheating.

[0037] C. Pressure curing: Gradually increase the temperature and pressure to 190℃ and 3.0MPa, and introduce nitrogen as an inert protective gas. Under these conditions, maintain the temperature and pressure for 38 minutes to complete the resin curing.

[0038] D. Cooling and Demolding: Gradually cool down and release pressure to obtain a low thermal expansion high-frequency copper-clad laminate after demolding.

[0039] Example 2

[0040] A microtextured treatment and lamination process for the copper foil surface of a low thermal expansion high-frequency copper-clad laminate, the specific steps of which are as follows:

[0041] 1. Copper foil surface microtexturing treatment process

[0042] S1. Copper foil pretreatment: Select rolled copper foil with a thickness of 6μm (tensile strength 300MPa, elongation 8%) as the base copper foil, and process it in sequence through degreasing, pickling, water washing and drying to remove surface oil, oxide layer and impurities.

[0043] S2. Microtexture preparation: A plasma etching machine was used, and a mixture of argon and oxygen (volume ratio 5:1) was introduced. After etching, the copper foil was placed in a mixed micro-etching solution of copper sulfate and sulfuric acid for micro-etching. After washing with water, a composite microtexture of "honeycomb pits-column protrusions" was obtained. The honeycomb pits had a pore size of 0.3 μm, a depth of 0.1 μm, and a center-to-center distance of 0.8 μm between adjacent pits. The columnar protrusions had a height of 0.2 μm and a diameter of 0.1 μm.

[0044] S3. Microtexture post-treatment: The copper foil is modified by immersing it in a compound silane coupling agent solution (containing fluorinated silane coupling agent and aminosilane coupling agent in a mass ratio of 1:2). After washing and drying, it is passivated by immersing it in a mixed passivation solution of chromate and phosphate. After washing and drying, the surface-modified copper foil is obtained.

[0045] 2. Lamination process

[0046] A. Lamination Preparation: Select a low thermal expansion high frequency semi-cured sheet (5wt% linear polyarylamide with a benzo4-membered ring structure added to a fluorinated resin mixture, 15% inorganic filler Al2O3 added, and carbon fiber cloth), cut it to a size that matches the surface-modified copper foil, align the resin-coated side of the surface-modified copper foil with one side of the semi-cured sheet and stack them to form a laminated preform.

[0047] B. Preheating treatment: The laminated preform is placed in a laminator for segmented preheating, with the first stage at 80°C and the second stage at 120°C, to complete the segmented preheating.

[0048] C. Pressure curing: Gradually increase the temperature and pressure to 180℃ and 2.5MPa, and introduce argon gas as an inert protective gas. Under these conditions, maintain the temperature and pressure for 45 minutes to complete the resin curing.

[0049] D. Cooling and Demolding: Gradually cool down and release pressure to obtain a low thermal expansion high-frequency copper-clad laminate after demolding.

[0050] Example 3

[0051] A microtextured treatment and lamination process for the copper foil surface of a low thermal expansion high-frequency copper-clad laminate, the specific steps of which are as follows:

[0052] 1. Copper foil surface microtexturing treatment process

[0053] S1. Copper foil pretreatment: Select electrolytic copper foil with a thickness of 35μm (tensile strength 350MPa, elongation 10%) as the base copper foil, and process it in sequence through degreasing, pickling, water washing and drying to remove surface oil, oxide layer and impurities.

[0054] S2. Microtexture preparation: A plasma etching machine was used to etch a mixture of argon and oxygen (volume ratio 5:2). After etching, the copper foil was placed in a mixed micro-etching solution of copper sulfate and sulfuric acid for micro-etching. After washing with water, a composite microtexture of "honeycomb pits-column protrusions" was obtained. The honeycomb pits had a pore size of 1.2 μm, a depth of 0.4 μm, and a center-to-center distance of 2.0 μm between adjacent pits. The columnar protrusions had a height of 0.5 μm and a diameter of 0.3 μm.

[0055] S3. Microtexture post-treatment: The copper foil is modified by immersing it in a compound silane coupling agent solution (containing fluorinated silane coupling agent and aminosilane coupling agent in a mass ratio of 1:3). After washing and drying, it is passivated by immersing it in a mixed passivation solution of chromate and phosphate. After washing and drying, the surface-modified copper foil is obtained.

[0056] 2. Lamination process

[0057] A. Lamination Preparation: Select a low thermal expansion high frequency semi-cured sheet (50wt% linear polyarylamide with a benzo4-membered ring structure added to a fluorinated resin mixture, 30% inorganic filler BN added, and polyimide fiber cloth), cut it to a size that matches the surface-modified copper foil, and stack the resin-coated side of the surface-modified copper foil with both sides of the semi-cured sheet to form a laminated blank.

[0058] B. Preheating treatment: The laminated preform is placed in a laminator and preheated in stages, with the first stage at 100°C and the second stage at 140°C, to complete the stage preheating.

[0059] C. Pressure curing: Gradually increase the temperature and pressure to 200℃ and 3.5MPa, and introduce nitrogen as an inert protective gas. Under these conditions, maintain the temperature and pressure for 30 minutes to complete the resin curing.

[0060] D. Cooling and Demolding: Gradually cool down and release pressure to obtain a low thermal expansion high-frequency copper-clad laminate after demolding.

[0061] Performance testing

[0062] The test results above show that the surface-modified copper foil and low thermal expansion high-frequency copper-clad laminate prepared by the present invention meet the requirements of the claims in all aspects, and have significant differences from the performance parameters of patented products in the prior art, which can effectively avoid patent conflicts; at the same time, the process is simple and feasible, and suitable for industrial production.

[0063] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microtextured surface treatment process for copper foil in a low thermal expansion high-frequency copper-clad laminate, characterized in that, Includes the following steps: S1. Copper foil pretreatment: Select electrolytic copper foil or rolled copper foil as the base copper foil, and successively perform degreasing, pickling, water washing and drying to remove oil, oxide layer and impurities from the surface of the base copper foil; S2. Microtexture fabrication: A composite microtexture of periodically interlaced "honeycomb-column protrusions" is fabricated on the resin-coated surface of a copper foil substrate using a combined plasma etching and chemical micro-etching process. In the composite microtexture, the honeycomb-shaped pits have a pore size of 0.3-1.2 μm, a depth of 0.1-0.4 μm, and a center-to-center distance of 0.8-2.0 μm between adjacent pits; the columnar protrusions have a height of 0.2-0.5 μm and a diameter of 0.1-0.3 μm, and are uniformly distributed on the inner wall of the honeycomb-shaped pits and in the gaps between the pits. S3. Microtexture post-treatment: The copper foil with the prepared composite microtexture is sequentially modified with a silane coupling agent, dried, and passivated to obtain a surface-modified copper foil; the silane coupling agent is a compound system of fluorinated silane coupling agent and aminosilane coupling agent, with a compound mass ratio of 1:2-3.

2. The processing technology according to claim 1, characterized in that, In step S1, the thickness of the base copper foil is 6-35 μm, the tensile strength is ≥300 MPa, and the elongation is ≥8%.

3. The process of claim 1, wherein, In step S2, plasma etching uses a mixture of argon and oxygen in a volume ratio of 5:1-2; chemical micro-etching uses a mixture of copper sulfate and sulfuric acid.

4. The process of claim 1, wherein, In step S3, the passivation treatment uses a mixed passivation solution of chromate and phosphate.

5. The surface-modified copper foil prepared by the process according to any one of claims 1 to 4, characterized in that, The surface-modified copper foil has an arithmetic mean roughness Ra of 0.15-0.35 μm on the resin-coated surface and a peel strength to the resin ≥1.0 N / mm.

6. A laminating process of a low thermal expansion high frequency copper clad plate, characterized in that, The surface-modified copper foil described in claim 5 is laminated with a low-thermal-expansion high-frequency prepreg, and the specific steps are as follows: A. Lamination Preparation: Select a low thermal expansion high-frequency prepreg and cut it to a size that matches the surface-modified copper foil. Align the resin-coated side of the surface-modified copper foil with one or both sides of the prepreg to form a laminated blank. The low thermal expansion high-frequency prepreg is prepared from a fluorinated resin mixture, low thermal expansion fiber cloth and inorganic filler. The fluorinated resin mixture contains 5-50 wt% of linear polyarylamide with a benzo[4]-4-membered ring structure. B. Preheating treatment: The laminated preform is placed in a laminator and preheated in stages. The first stage preheating temperature is 80-100℃, and the second stage preheating temperature is 120-140℃. C. Pressure Curing: After preheating, gradually increase the temperature and pressure of the laminator until the temperature reaches 180-200℃ and the pressure reaches 2.5-3.5MPa. Under these conditions, maintain the temperature and pressure for 30-45 minutes to complete the curing. D. Cooling and Demolding: After curing, gradually cool down and release the pressure to obtain a low thermal expansion high-frequency copper-clad laminate after demolding.

7. The lamination process of claim 6, wherein, In step A, the low thermal expansion fiber cloth is one of electronic grade alkali-free glass fiber cloth, carbon fiber or polyimide fiber cloth; the inorganic filler is one or more of SiO2, Al2O3 or BN, and the amount added is 15-30% of the mass of the fluorinated resin mixture.

8. The lamination process of claim 6, wherein, In step A, the fluorinated resin mixture includes a fluorinated resin emulsion, a linear polyarylamide with a benzo[4] four-membered ring structure, a coupling agent, and a flame retardant; the fluorinated resin emulsion is one or more of polytetrafluoroethylene and tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer.

9. The lamination process according to claim 6, characterized in that, In step C, during the pressure curing process, an inert protective gas is simultaneously introduced.

10. A low-thermal-expansion high-frequency copper-clad laminate prepared using the lamination process described in any one of claims 6-9, characterized in that, The copper-clad laminate has an X / Y axis thermal expansion coefficient of 2.8-5.0ppm / ℃, a Z axis thermal expansion coefficient of 25-35ppm / ℃, a dielectric constant of ≤3.2 at 25℃ and 10GHz frequency, a dielectric loss of ≤0.003, a peel strength of ≥1.0N / mm, and a heat resistance temperature of ≥260℃.

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