A high-frequency flexible copper-clad plate material with a multi-layer structure and a preparation method thereof

Abstract

The present application relates to the field of material science and engineering, and aims to provide a kind of multilayer structure high-frequency flexible copper-clad plate material and its preparation method.The copper-clad plate material has layered structure of sequentially superimposed, including: two copper foil layers located at the outermost surface, a filler powder / fluororesin paint cloth layer located at the center, and two liquid crystal polymer film layers located between the copper foil layer and the filler powder / fluororesin paint cloth layer;The filler powder / fluororesin paint cloth layer is formed by attaching the mixture of nitride filler powder and fluororesin on the surface of glass fiber cloth using glass fiber cloth as substrate and through dipping, sintering and vacuum hot pressing treatment.The product has the characteristics of low dielectric constant, low dielectric loss, low water absorption, high thermal decomposition temperature, high dimensional stability, etc.;The formed heat conduction path meets the application scenario under high frequency and high speed;The performance indicators such as water absorption, thermal decomposition temperature and dimensional stability can be maintained as other similar materials.

Description

Technical Field

[0001] This invention relates to a high-frequency flexible copper-clad laminate material and its preparation method, belonging to the field of materials science and engineering. Background Technology

[0002] Flexible printed circuit boards (FPCs) are made of flexible insulating materials and feature high integration density, thinness, and bendability, giving products more design space and potential in terms of shape and reliability. The development of flexible substrates aligns with the current trend of miniaturization and thinning of electronic products, and has broad application prospects in consumer electronics such as smartphones, tablets, and wearable devices, as well as other communication fields. Flexible copper clad laminates (FCCLs) are an important basic material in FPC production. FCCLs consist of a flexible insulating resin film and copper foil bonded to it. Typically, FCCLs are formed by laminating copper foil onto both sides of the insulating resin film under pressure. The insulating resin film mainly uses polyimide (PI) or polyester (PET). However, PI or PET can only be used in the MHz band; if the signal frequency increases to GHz, the dielectric loss will increase significantly, and the signal-to-noise ratio of the transmitted signal may decrease significantly. Reducing the dielectric loss of materials under high-frequency and high-speed conditions is one of the effective methods to solve the above problems. Meanwhile, in recent years, due to the miniaturization and integration of electronic devices, achieving high heat dissipation has gradually become a focus of attention. Therefore, flexible copper-clad laminates with low dielectric loss and high thermal conductivity have great application prospects.

[0003] Liquid crystal polymers (LCPs) possess high strength, high modulus, high heat resistance, and low dielectric properties, as well as excellent bending resistance, chemical corrosion resistance, aging resistance, high radiation resistance, and molding and processing performance. Furthermore, their coefficient of linear thermal expansion is close to that of copper, meeting the material requirements of 5G communication products. Injection-grade LCP resin can be used in PCB motherboards and SMT connectors, while film-grade LCP resin can be used in high-frequency signal transmission carriers, such as mobile phone antennas. However, LCPs also have drawbacks such as low bending resistance and high price.

[0004] Currently, fluoropolymers have attracted widespread attention due to their excellent dielectric properties. Compared with other polymer materials, fluoropolymers are superior in heat resistance, chemical resistance, weather resistance, and electrical properties, and also possess unique properties such as non-stickiness and self-lubrication. A typical fluoropolymer used in high-frequency copper-clad laminates is polytetrafluoroethylene (PTFE), which has low dielectric constant and dielectric loss, but its poor processing performance and film-forming ability limit its application in flexible substrates. Soluble polytetrafluoroethylene (PFA) is a copolymer of a small amount of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene. It exhibits enhanced melt adhesion and decreased melt viscosity, while its properties remain unchanged compared to polytetrafluoroethylene. At 10 GHz, PFA has a dielectric constant of 2.1 and a dielectric loss of 0.0003, comparable to PTFE in dielectric constant but slightly higher in dielectric loss. However, its processing performance is significantly improved, especially its film-forming properties.

[0005] Introducing inorganic fillers into polymer matrices is a common method to improve the overall performance of materials. Currently, a common approach is to directly composite the filler with the polymer through methods such as hot melt blending to obtain blended granules, and then fabricate the composite substrate using vacuum hot pressing. Although direct blending is relatively simple, it also has some drawbacks. First, the filler tends to be uniformly distributed within the matrix, resulting in poor performance improvement in certain aspects, often requiring a large filler content to achieve the desired properties. Second, some fillers may be exposed on the surface of the composite substrate, potentially affecting the surface smoothness of the material. Furthermore, while some high-performance fillers have good dielectric properties, they are significantly affected by environmental acids, alkalis, and water mist; their exposure can also negatively impact the final service performance of the substrate. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a multi-layered high-frequency flexible copper-clad laminate material and its preparation method, in view of the shortcomings of the prior art.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] A high-frequency flexible copper-clad laminate material with a multilayer structure is provided. The copper-clad laminate material has a layered structure stacked sequentially, including: two copper foil layers located on the outermost surface, a filler powder / fluororesin varnish layer located in the center, and two liquid crystal polymer film layers located between the copper foil layer and the filler powder / fluororesin varnish layer.

[0009] The filler powder / fluororesin coated cloth layer is formed by attaching a mixture of nitride filler powder and fluororesin to the surface of glass fiber cloth as a base through impregnation, sintering and vacuum hot pressing; the nitride filler powder is one or both of aluminum nitride or boron nitride.

[0010] As a preferred embodiment of the present invention, in the filler powder / fluororesin coating layer, the mass ratio of nitride filler powder to fluororesin is 1.5 to 2.3:1.

[0011] As a preferred embodiment of the present invention, the fluororesin is polytetrafluoroethylene perfluoroalkyl vinyl ether (PFA).

[0012] As a preferred embodiment of the present invention, the nitride filler powder is boron nitride and aluminum nitride, and the mass ratio of the two is 0.3 to 1.6:1.

[0013] As a preferred embodiment of the present invention, the thickness of the copper foil layer is 12 μm; or, the thickness of the filler powder / fluororesin varnish layer is 150 μm; or, the thickness of the liquid crystal polymer film layer is 25 μm.

[0014] As a preferred embodiment of the present invention, the thickness of each copper foil layer is the same; or, the thickness of each liquid crystal polymer film layer is the same.

[0015] As a preferred embodiment of the present invention, the sum of the thicknesses of the two liquid crystal polymer layers and the filler powder / fluororesin varnish layer is 200 μm.

[0016] This invention further provides a method for preparing the aforementioned multilayer high-frequency flexible copper-clad laminate material, comprising the following steps:

[0017] (1) Nitride filler powder is added to fluororesin emulsion, ultrasonically stirred and vacuum defoamed to obtain a uniformly dispersed slurry;

[0018] (2) The glass fiber cloth is impregnated in the mixed slurry, and after drying, sintering and vacuum hot pressing, the filled powder / fluororesin coated cloth is obtained.

[0019] (3) Stack the materials in the order of copper foil, liquid crystal polymer film, filler powder / fluororesin varnish cloth, liquid crystal polymer film, and copper foil; then place them in a vacuum hot press to hot press them to obtain a multi-layered high-frequency flexible copper-clad laminate material.

[0020] As a preferred embodiment of the present invention, in step (2), the drying temperature is controlled at 90°C and the time is 10 min; the sintering temperature is controlled at 320°C and the time is 10 min; the hot pressing pressure is controlled at 10 MPa, the temperature is 320°C and the time is 20 min, and the vacuum degree is -0.085 MPa.

[0021] As a preferred embodiment of the present invention, in step (3), the parameters of the hot pressing process are set as follows: pressure is 5 MPa, temperature is 315°C, time is 5 min, and vacuum degree is -0.085 MPa.

[0022] Description of the invention principle:

[0023] This invention leverages the excellent high-frequency dielectric properties, low water absorption, and superior corrosion resistance, heat resistance, flexibility, and dimensional stability of liquid crystal polymers (LCPs). A high-frequency flexible copper-clad laminate (CCL) is fabricated by encapsulating a liquid crystal polymer resin film with a filler powder / fluororesin composite film. High-performance fiberglass cloth is used as a reinforcing phase to ensure the structural strength of the CCL and improve its dimensional stability. PFA resin is used as an intermediate layer to balance the CCL's flexibility and good dielectric properties. The addition of fillers significantly improves the material's thermal conductivity and further enhances its dimensional stability without compromising its flexibility. Liquid crystal polymers possess low dielectric constant, low dielectric loss, and low water absorption. The layered encapsulation design prevents direct contact between the intermediate filler powder / fluororesin varnish layer and the external environment, effectively reducing the overall water absorption rate. The liquid crystal polymer film also exhibits excellent flexibility and good dimensional stability; the introduction of the liquid crystal polymer layer does not negatively impact the overall flexibility and dimensional stability of the CCL.

[0024] Compared with existing technologies, the beneficial effects of this invention are:

[0025] 1. The copper-clad laminate prepared by the present invention is made by vacuum hot pressing of liquid crystal polymer and fluororesin with filler powder and glass fiber cloth copper foil, and has the characteristics of low dielectric constant, low dielectric loss, low water absorption, high thermal decomposition temperature and high dimensional stability.

[0026] 2. Compared with the commonly used MPI and LCP copper-clad laminates, the flexible copper-clad laminate material prepared by this invention has a multi-layer structure, which encapsulates the thermally conductive filler in the core layer, which helps to form a thermally conductive path and has a great advantage in thermal conductivity. It also has excellent dielectric properties, which well meet the current high-frequency and high-speed grounding application scenarios.

[0027] 3. The flexible copper-clad laminate material prepared by the present invention has a multi-layer structure and is covered with a liquid crystal polymer layer with high dimensional stability and extremely low water absorption rate, which enables it to maintain performance indicators such as water absorption rate, thermal decomposition temperature, and dimensional stability comparable to other similar materials.

[0028] 4. This invention uses fluororesin and liquid crystal polymer as the matrix and utilizes a layered composite structure design to improve the overall performance of the material, which has broad application prospects in the field of high-frequency flexible copper clad laminates. Detailed Implementation

[0029] The present invention will be further described in detail with reference to the following embodiments. It should be noted that these embodiments are not intended to limit the scope of the present invention.

[0030] The fluororesin used in each embodiment is a polytetrafluoroethylene perfluoroalkyl vinyl ether (PFA) emulsion, derived from a commercially available product (3M 6900GZ), wherein the PFA content is 50% (m / m).

[0031] Example 1:

[0032] Step (1): Take a certain amount of PFA emulsion, add boron nitride powder and ultrasonically stir for 30 minutes. Vacuum defoaming is performed to obtain a uniformly dispersed mixed slurry. The mass ratio of boron nitride powder to PFA emulsion is 0.77:1 (the mass ratio of the converted nitride filler powder to pure PFA is 1.5:1).

[0033] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0034] Step (3): Cover the upper and lower surfaces of the filler powder / PFA coated cloth obtained in step (2) with a liquid crystal polymer film, then place it between double-sided copper foil, and then transfer it to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the liquid crystal polymer film thickness is 25 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0035] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.4 (10 GHz), dielectric loss 1.7 × 10⁻⁶. -3 (10 GHz), thermal conductivity 4.3 W / (mK), water absorption 0.04%, dimensional stability 0.014%, thermal decomposition temperature 447.0℃, the final thickness of the flexible high-frequency copper clad laminate material is 224 micrometers, and the sum of the thicknesses of the two liquid crystal polymer layers and the filling powder / fluororesin varnish layer is 200 μm.

[0036] Example 2:

[0037] Step (1): Take a certain amount of PFA emulsion, add aluminum nitride powder and ultrasonically stir for 30 minutes, then vacuum defoam to obtain a uniformly dispersed slurry, wherein the mass ratio of aluminum nitride particles to PFA emulsion is 1.14:1 (the converted mass ratio of nitride filler powder to pure PFA is 2.3:1);

[0038] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0039] Step (3): Cover the upper and lower surfaces of the filler powder / PFA coated cloth obtained in step (2) with a liquid crystal polymer film, then place it between double-sided copper foil, and then transfer it to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the liquid crystal polymer film thickness is 25 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0040] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.8 (10 GHz), dielectric loss 6.7 × 10⁻⁶. -3 (10 GHz), thermal conductivity 1.9 W / (mK), water absorption 0.1%, dimensional stability 0.43%, thermal decomposition temperature 453.3℃, ​​the final thickness of the flexible high-frequency copper clad laminate material is 224 micrometers, and the sum of the thicknesses of the two liquid crystal polymer layers and the filling powder / fluororesin varnish layer is 200 μm.

[0041] Example 3:

[0042] Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder, and ultrasonically stir for 30 minutes. Vacuum defoaming is performed to obtain a uniformly dispersed mixed slurry. The mass ratio of boron nitride, aluminum nitride powder and PFA emulsion is 9.6:5.9:17.2 (the converted mass ratio of nitride filler powder to pure PFA is 1.8:1, and the mass ratio of boron nitride and aluminum nitride is 1.6:1).

[0043] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0044] Step (3): Cover the upper and lower surfaces of the filler powder / PFA coated cloth obtained in step (2) with a liquid crystal polymer film, then place it between double-sided copper foil, and then transfer it to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the liquid crystal polymer film thickness is 25 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0045] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.4 (10 GHz), dielectric loss 3.0 × 10⁻⁶. -3 (10 GHz), thermal conductivity 5.5 W / (mK), water absorption 0.04%, dimensional stability 0.022%, thermal decomposition temperature 462.7℃, the final thickness of the flexible high-frequency copper clad laminate material is 224 micrometers, and the sum of the thicknesses of the two liquid crystal polymer layers and the filling powder / fluororesin varnish layer is 200 μm.

[0046] Example 4:

[0047] Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder, and ultrasonically stir for 30 minutes. Vacuum defoaming is performed to obtain a uniformly dispersed mixed slurry. The mass ratio of boron nitride, aluminum nitride powder and PFA emulsion is 4.14:13.7:17.2 (the converted mass ratio of nitride filler powder to pure PFA is 2.1:1, and the mass ratio of boron nitride to aluminum nitride is 0.3:1).

[0048] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0049] Step (3): Cover the upper and lower surfaces of the filler powder / PFA coated cloth obtained in step (2) with a liquid crystal polymer film, then place it between double-sided copper foil, and then transfer it to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the liquid crystal polymer film thickness is 25 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0050] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.8 (10 GHz), dielectric loss 5.3 × 10⁻⁶. -3(10 GHz), thermal conductivity 3.2 W / (mK), water absorption 0.08%, dimensional stability 0.081%, thermal decomposition temperature 452.2℃, the final thickness of the flexible high-frequency copper clad laminate material is 224 micrometers, and the sum of the thicknesses of the two liquid crystal polymer layers and the filling powder / fluororesin varnish layer is 200 μm.

[0051] Example 5:

[0052] Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder, and ultrasonically stir for 30 minutes. Vacuum defoaming is performed to obtain a uniformly dispersed mixed slurry. The mass ratio of boron nitride, aluminum nitride powder and PFA emulsion is 6.9:9.8:17.2 (the converted mass ratio of nitride filler powder to pure PFA is 1.9:1, and the mass ratio of boron nitride and aluminum nitride is 0.7:1).

[0053] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0054] Step (3): Cover the upper and lower surfaces of the filler powder / PFA coated cloth obtained in step (2) with a liquid crystal polymer film, then place it between double-sided copper foil, and then transfer it to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the liquid crystal polymer film thickness is 25 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0055] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.7 (10 GHz), dielectric loss 5.0 × 10⁻⁶. -3 (10 GHz), thermal conductivity 4.2 W / (mK), water absorption 0.08%, dimensional stability 0.054%, thermal decomposition temperature 453.9℃, the final thickness of the flexible high-frequency copper clad laminate material is 224 micrometers, and the sum of the thicknesses of the two liquid crystal polymer layers and the filler powder / fluororesin varnish layer is 200 μm.

[0056] Comparative Example 1:

[0057] Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder, and ultrasonically stir for 30 minutes. Vacuum defoaming is performed to obtain a uniformly dispersed mixed slurry. The mass ratio of boron nitride, aluminum nitride powder and PFA emulsion is 9.6:5.9:17.2 (the converted mass ratio of nitride filler powder to pure PFA is 1.8:1, and the mass ratio of boron nitride and aluminum nitride is 1.6:1).

[0058] Step (2): Using 1080 glass fiber cloth, the glass fiber cloth is impregnated in the filler powder / PFA mixed slurry obtained in step (1), and the solvent is dried at 90°C for 10 min, sintered at 320°C for 10 min, and vacuum hot-pressed at 320°C and 10MPa for 20 min to form a filler powder / PFA coated cloth with a thickness of 150μm; the vacuum degree during vacuum hot pressing is -0.085MPa.

[0059] Step (3): The filler powder / PFA varnish obtained in step (2) is arranged between double-sided copper foils, and then transferred to a vacuum hot press for hot pressing to obtain a high-frequency flexible copper-clad laminate material. The copper foil thickness is 12 micrometers, the hot pressing temperature is 315℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree during vacuum hot pressing is -0.085MPa.

[0060] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.7 (10 GHz), dielectric loss 2.8 × 10⁻⁶. -3 (10 GHz), thermal conductivity 5.7 W / (mK), water absorption 2.45%, dimensional stability 0.006%, thermal decomposition temperature 444℃, and the final thickness of the flexible high-frequency copper clad laminate material is 175 micrometers.

[0061] Comparative Example 2:

[0062] Step (1): Take a certain amount of pure PFA powder, liquid crystal polymer (LCP) powder and boron nitride ceramic particles, and weigh them precisely so that the mass ratio between PFA, LCP and boron nitride is 9:4:7.

[0063] Step (2): The powders weighed in step (1) are premixed and then put into a twin-screw extruder for hot melt blending, followed by extrusion granulation to obtain composite granules. The screw temperature is 325℃, the screw speed is 100r / min, and the blending time is 5min.

[0064] Step (3): The granules obtained in step (2) are placed in a vacuum hot press for hot pressing to obtain a composite flexible high frequency substrate. The hot pressing temperature is 325℃, the hot pressing pressure is 5MPa, the hot pressing time is 2min, and the vacuum degree is -0.085MPa.

[0065] Step (4): Place the composite flexible high-frequency substrate obtained in step (3) between double-sided copper foils, and then transfer it to a vacuum hot press to hot press to obtain a high-frequency flexible copper-clad laminate material, wherein the copper foil thickness is 12 micrometers, the hot pressing temperature is 325℃, the hot pressing pressure is 5MPa, the hot pressing time is 5min, and the vacuum degree is -0.085MPa.

[0066] The flexible high-frequency copper-clad laminate material prepared according to the aforementioned formula and process steps has the following performance indicators: dielectric constant 3.7 (10 GHz), dielectric loss 2.6 × 10⁻⁶. -3 (10 GHz), thermal conductivity 4.25 W / (mK), water absorption 0.02%, dimensional stability 0.018%, thermal decomposition temperature 472℃, and the final thickness of the flexible high-frequency copper clad laminate material is 180 micrometers.

[0067] Based on the above performance test data, it can be seen that the high-frequency flexible copper-clad laminates prepared by the special design of the multilayer structure in Examples 1 to 5 of the present invention have excellent dielectric properties, with Dk of 3.4 to 3.8 at 10 GHz, Df as low as 0.0017, good dimensional stability (all within ±0.1%), low water absorption (all within 0.1%), high thermal conductivity (up to 5.5 W / (mK), and good thermal stability (all with thermal decomposition temperatures above 400℃).

[0068] Compared to the embodiments of the present invention, the product of Comparative Example 1 does not use a liquid crystal polymer film layer, and the final product is a three-layer sandwich structure used in conventional technology. A comparison of the product specifications of Example 3 and Comparative Example 1 shows that, because the surface of Example 3 is coated with a liquid crystal polymer film, it effectively isolates moisture from the environment. While the flexible high-frequency copper-clad laminate material prepared in Comparative Example 1 performs well in terms of dimensional stability and thermal conductivity, its excessively high water absorption rate limits its practical application in the high-frequency radio frequency field.

[0069] Compared to the embodiments of the present invention, although Comparative Example 2 also uses liquid crystal polymer and fluoropolymer components, the fluoropolymer is not used to prepare the filler powder / fluoropolymer coating layer for independent use. The final product is still a traditional copper-clad laminate structure. By comparing the product indicators of Example 1 and Comparative Example 2, it can be seen that Example 1, through its layered structural design, achieves higher thermal conductivity compared to the traditional blending process, while exhibiting similar performance in dielectric properties, water absorption, and dimensional stability.

[0070] In summary, the layered structure design described in this invention has a significant effect on improving the overall performance of materials.

Claims

1. A multi-layered high-frequency flexible copper-clad laminate material, characterized in that, The copper-clad laminate material has a layered structure that is stacked sequentially, including: two copper foil layers on the outermost surface, a filler powder / fluororesin varnish layer in the center, and two liquid crystal polymer film layers between the copper foil layer and the filler powder / fluororesin varnish layer. The filler powder / fluororesin coated cloth layer is formed by attaching a mixture of nitride filler powder and fluororesin to the surface of glass fiber cloth as a base through impregnation, sintering and vacuum hot pressing. In the filler powder / fluororesin coating layer, the mass ratio of nitride filler powder to fluororesin is 1.5~2.3:1; the fluororesin is polytetrafluoroethylene perfluoroalkyl vinyl ether; the nitride filler powder is boron nitride and aluminum nitride, and the mass ratio of the two is 0.3~1.6:

1.

2. The high-frequency flexible copper-clad laminate material according to claim 1, characterized in that, The copper foil layer has a thickness of 12 μm, the filler powder / fluororesin varnish layer has a thickness of 150 μm, and the liquid crystal polymer film layer has a thickness of 25 μm.

3. The method for preparing the multilayer high-frequency flexible copper-clad laminate material according to claim 1, characterized in that, Includes the following steps: (1) Nitride filler powder is added to fluororesin emulsion, ultrasonically stirred and vacuum defoamed to obtain a uniformly dispersed mixed slurry; (2) The glass fiber cloth is impregnated in the mixed slurry, and after drying, sintering and vacuum hot pressing, the filled powder / fluororesin coated cloth is obtained. (3) Stack the materials in the order of copper foil, liquid crystal polymer film, filler powder / fluororesin varnish cloth, liquid crystal polymer film and copper foil; then place them in a vacuum hot press to hot press to obtain a multi-layered high-frequency flexible copper-clad laminate material.

4. The method according to claim 3, characterized in that, In step (2), the drying temperature is controlled at 90℃ for 10 minutes; the sintering temperature is controlled at 320℃ for 10 minutes; the hot pressing pressure is controlled at 10 MPa, the temperature at 320℃ for 20 minutes, and the vacuum degree is -0.085 MPa.

5. The method according to claim 3, characterized in that, In step (3), the parameters of the hot pressing process are set as follows: pressure is 5 MPa, temperature is 315℃, time is 5 min, and vacuum degree is -0.085 MPa.