CN116330765A - A kind of multilayer structure high frequency flexible copper clad laminate material and preparation method thereof - Google Patents

Abstract

The invention relates to the field of material science and engineering, and aims to provide a high-frequency flexible copper clad laminate material with a multilayer structure and a preparation method thereof. The copper clad laminate material has a layered structure stacked in sequence, including: two copper foil layers on the outermost surface, a filling powder/fluororesin varnish layer in the center, and a copper foil layer and filling powder/fluororesin varnish layer The two liquid crystal polymer film layers between the layers; the filler powder/fluororesin varnish layer is based on glass fiber cloth, and the nitride filler powder and fluororesin mixture are attached to the substrate through impregnation, sintering and vacuum hot pressing. Formed on the surface of glass fiber cloth. The product of the present invention 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 scenarios at high frequency and high speed; , dimensional stability and other performance indicators can remain comparable to other similar materials.

Description

A kind of multilayer structure high frequency flexible copper clad laminate material and preparation method thereof

technical field

The invention relates to a high-frequency flexible copper-clad laminate material and a preparation method thereof, belonging to the field of material science and engineering.

Background technique

Flexible Printed Circuit Board (Flexible Printing Circuit, FPC) is made of flexible insulating materials, which has the characteristics of high integration density, light and thin, and bendable, which endows products with more design space and potential in terms of shape and reliability. The development of flexible substrates is in line with the development trend of miniaturization and thinning of electronic products in today's society, and has broad application prospects in consumer electronics such as smartphones, tablet computers, wearable devices, and other communication fields. In the production of FPC, flexible copper clad laminate (FCCL) is an important basic material. The flexible copper clad laminate includes a flexible insulating resin film and copper foil attached to the insulating resin film. Generally speaking, flexible copper-clad laminates are formed by applying pressure and lamination after coating copper foil on both sides of an insulating resin. The insulating resin film is mainly made of polyimide (PI) or polyester (Polyester; PET). However, PI or PET can only be used in the MHz frequency band; if the frequency of the signal is increased 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 ways to solve the above problems. At the same time, due to the miniaturization and integration of electronic equipment in recent years, the realization of high heat dissipation of electronic equipment has gradually become the focus of attention. Therefore, flexible copper clad laminates with low dielectric loss and high thermal conductivity have great application prospects.

Liquid crystal polymer (LCP) has 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 processability, while Its linear thermal expansion coefficient is close to that of copper, which can meet the material requirements for 5G communication products. Injection-grade LCP resin can be used for PCB motherboards, SMT connectors, etc., and film-grade LCP resin can be used for high-frequency signal transmission carriers, such as mobile phone antennas. However, LCP also has problems such as low bending resistance and high price.

At present, fluororesins have also received extensive attention because of their excellent dielectric properties. Compared with other polymer materials, fluororesin is not only superior in heat resistance, chemical resistance, weather resistance, electrical characteristics, etc., but also has unique properties such as non-stick and self-lubricating properties. The typical fluororesin used in the field of 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 the field of flexible substrates. Soluble polytetrafluoroethylene (PFA) is a copolymer of a small amount of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene. The melt adhesion is enhanced, the melt viscosity is reduced, and the performance is unchanged compared with PTFE. At 10GHz, the dielectric constant of PFA is 2.1, and the dielectric loss is 0.0003. Compared with PTFE, its dielectric constant is equivalent, and its dielectric loss is slightly higher. However, the processing performance has been greatly improved, especially the film-forming performance.

Introducing inorganic fillers into polymer substrates for compounding is a common method to improve the comprehensive properties of materials. At present, the commonly used method is to directly compound fillers and polymers by means of hot melt blending to obtain blended pellets, and then make the obtained pellets into composite substrates by vacuum hot pressing. Although the operation of direct blending is relatively simple, it also has some disadvantages. First of all, the filler tends to be evenly distributed in the matrix, so that the performance of the filler in some aspects is poor, and a large filler content is often required to achieve the required performance; in addition, some fillers will also be exposed on the surface of the composite substrate. On the one hand, It may affect the surface smoothness of the material. On the other hand, although some high-performance fillers have good dielectric properties, they are greatly affected by the acid, alkali, and water mist in the environment, and their exposure to the outside will also affect the final service performance of the substrate. There will also be adverse effects.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-layer structure high-frequency flexible copper clad laminate material and a preparation method thereof in view of the deficiencies of the prior art.

In order to solve the technical problem, the solution of the present invention is:

Provide a multilayer high-frequency flexible copper clad laminate material, the copper clad laminate material has a layered structure stacked in sequence, including: two copper foil layers on the outermost surface, and a filling 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 filling powder/fluororesin varnish layer is based on glass fiber cloth, and is formed by attaching the nitride filling powder and fluororesin mixture to the surface of the glass fiber cloth through impregnation, sintering and vacuum hot pressing; the nitrogen The compound filling powder is one or both of aluminum nitride or boron nitride.

As a preferred solution of the present invention, in the filler powder/fluororesin varnish layer, the mass ratio of the nitride filler powder to the fluororesin is 1.5˜2.3:1.

As a preferred solution of the present invention, the fluororesin is polytetrafluoroethylene perfluoroalkyl vinyl ether (PFA).

As a preferred solution of the present invention, the nitride filling powder is boron nitride and aluminum nitride, and the mass ratio of the two is 0.3-1.6:1.

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

As a preferred solution of the present invention, the thicknesses of the copper foil layers are the same; or, the thicknesses of the liquid crystal polymer film layers are the same.

As a preferred solution 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.

The present invention further provides a method for preparing the aforementioned high-frequency flexible copper-clad laminate material with a multilayer structure, comprising the following steps:

(1) Add the nitride filling powder into the fluororesin emulsion, stir it ultrasonically and defoam in vacuum to obtain a uniformly dispersed mixed slurry;

(2) impregnating the glass fiber cloth in the mixed slurry, drying, sintering and vacuum hot pressing to obtain the filling powder/fluororesin varnish;

(3) According to the order of copper foil, liquid crystal polymer film, filling powder/fluororesin varnished cloth, liquid crystal polymer film, and copper foil, each layer of material is stacked in sequence; High frequency flexible copper clad laminate material with layer structure.

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

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

Description of invention principle:

Based on the excellent high-frequency dielectric properties, low water absorption, excellent corrosion resistance, heat resistance, and flexible dimensional stability of liquid crystal polymers, the present invention uses liquid crystal polymer resin films to sandwich filling powder/fluororesin composites Films were prepared for high-frequency flexible copper-clad laminates. The use of high-performance glass fiber cloth as the reinforcing phase ensures the structural strength of the copper clad laminate and improves the dimensional stability of the material. The use of PFA resin as the intermediate layer takes into account the flexibility and good dielectric properties of the copper clad laminate. The addition of fillers can greatly improve the thermal conductivity of the material and further improve the dimensional stability of the material without destroying its flexibility. Liquid crystal polymers have the characteristics of low dielectric constant, low dielectric loss and low water absorption. The layered sandwich structure design can avoid direct contact between the filling powder/fluororesin varnish layer and the external environment, effectively reducing the overall water absorption. The liquid crystal polymer film also has excellent flexibility and good dimensional stability, and the introduction of the liquid crystal polymer layer will not have a negative impact on the overall flexibility and dimensional stability of the copper clad laminate.

Compared with prior art, the beneficial effect of the present invention is:

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

2. Compared with the MPI and LCP copper clad laminates that are widely used at present, the flexible copper clad laminate material prepared by the present invention has a multi-layer structure, and the thermal conductive filler is encapsulated in the core layer, which helps it form a heat conduction path. It has great advantages in performance, and has excellent dielectric properties, which well meets the current high-frequency and high-speed application scenarios.

3. Due to the multi-layer structure of the flexible copper-clad laminate material prepared by the present invention, the surface is covered with a liquid crystal polymer layer with high dimensional stability and extremely low water absorption rate, so that it can be improved in water absorption rate, thermal decomposition temperature, dimensional stability, etc. The performance index can be kept comparable to other similar materials.

4. The present invention uses fluororesin and liquid crystal polymer as the matrix, and utilizes layered composite structural design to improve the comprehensive performance of the material, which has broad application prospects in the field of high-frequency flexible copper clad laminates.

Detailed ways

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

The fluororesin used in each example is polytetrafluoroethylene perfluoroalkyl vinyl ether (PFA) emulsion, which is derived from a commercial product (3M 6900GZ), wherein the PFA content is 50% (m/m).

Example 1:

Step (1): Take a certain amount of PFA emulsion, add boron nitride powder and ultrasonically stir for 30 minutes, vacuum defoam to obtain a uniformly dispersed mixed slurry, wherein the mass ratio of boron nitride powder and PFA emulsion is 0.77:1 (Nitrogen after conversion The mass ratio of chemical filler powder to pure PFA is 1.5:1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Cover the upper and lower surfaces of the filling powder/PFA varnish obtained in step (2) with a liquid crystal polymer film, then place between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain high High-frequency flexible copper clad laminate material, wherein the thickness of copper foil is 12 microns, the thickness of liquid crystal polymer film is 25 microns, the hot pressing temperature is 315 °C, the hot pressing pressure is 5 MPa, the hot pressing time is 5 minutes, and the vacuum degree during vacuum hot pressing is -0.085MPa.

The flexible high-frequency copper-clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.4 (10Ghz), dielectric loss 1.7×10 ^-3 (10Ghz), thermal conductivity 4.3 W/(mK), water absorption 0.04%, dimensional stability 0.014%, thermal decomposition temperature 447.0°C, flexible high-frequency copper clad laminate material final thickness 224 microns, two liquid crystal polymer layers and filling powder/fluororesin varnish layer The sum of the thicknesses is 200 μm.

Example 2:

Step (1): Take a certain amount of PFA emulsion, add aluminum nitride powder and ultrasonically stir for 30 minutes, and vacuum defoam to obtain a uniformly dispersed mixed slurry, in which the mass ratio of aluminum nitride particles and PFA emulsion is 1.14:1 (converted nitrogen The mass ratio of chemical filler powder to pure PFA is 2.3:1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Cover the upper and lower surfaces of the filling powder/PFA varnish obtained in step (2) with a liquid crystal polymer film, then place between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain high High-frequency flexible copper clad laminate material, wherein the thickness of copper foil is 12 microns, the thickness of liquid crystal polymer film is 25 microns, the hot pressing temperature is 315 °C, the hot pressing pressure is 5 MPa, the hot pressing time is 5 minutes, and the vacuum degree during vacuum hot pressing is -0.085MPa.

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.8 (10Ghz), dielectric loss 6.7×10 ^-3 (10Ghz), thermal conductivity 1.9 W/(mK), water absorption 0.1%, dimensional stability 0.43%, thermal decomposition temperature 453.3°C, flexible high-frequency copper clad laminate material final thickness 224 microns, two liquid crystal polymer layers and filling powder/fluororesin varnished cloth layer The sum of the thicknesses is 200 μm.

Example 3:

Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder and ultrasonically stir for 30 minutes, vacuum defoaming to obtain a uniformly dispersed mixed slurry, wherein the mass ratio of boron nitride, aluminum nitride powder and PFA emulsion 9.6︰5.9︰17.2 (the mass ratio of the converted nitride filled powder to pure PFA is 1.8︰1, and the mass ratio of boron nitride to aluminum nitride is 1.6︰1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Cover the upper and lower surfaces of the filling powder/PFA varnish obtained in step (2) with a liquid crystal polymer film, then place between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain high High-frequency flexible copper clad laminate material, wherein the thickness of copper foil is 12 microns, the thickness of liquid crystal polymer film is 25 microns, the hot pressing temperature is 315 °C, the hot pressing pressure is 5 MPa, the hot pressing time is 5 minutes, and the vacuum degree during vacuum hot pressing is -0.085MPa

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.4 (10Ghz), dielectric loss 3.0×10 ^-3 (10Ghz), thermal conductivity 5.5 W/(mK), water absorption 0.04%, dimensional stability 0.022%, thermal decomposition temperature 462.7°C, flexible high frequency copper clad laminate material final thickness 224 microns, two liquid crystal polymer layers and filling powder/fluororesin varnish layer The sum of the thicknesses is 200 μm.

Example 4:

Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder and ultrasonically stir for 30 minutes, vacuum defoaming to obtain a uniformly dispersed mixed slurry, wherein the mass ratio of boron nitride, aluminum nitride powder and PFA emulsion 4.14︰13.7︰17.2 (the mass ratio of the converted nitride filler powder to pure PFA is 2.1︰1, and the mass ratio of boron nitride to aluminum nitride is 0.3︰1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Cover the upper and lower surfaces of the filling powder/PFA varnish obtained in step (2) with a liquid crystal polymer film, then place between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain high High-frequency flexible copper clad laminate material, wherein the thickness of copper foil is 12 microns, the thickness of liquid crystal polymer film is 25 microns, the hot pressing temperature is 315 °C, the hot pressing pressure is 5 MPa, the hot pressing time is 5 minutes, and the vacuum degree during vacuum hot pressing is -0.085MPa

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.8 (10Ghz), dielectric loss 5.3×10 ^-3 (10Ghz), thermal conductivity 3.2 W/(mK), water absorption 0.08%, dimensional stability 0.081%, thermal decomposition temperature 452.2°C, flexible high-frequency copper clad laminate material final thickness 224 microns, two liquid crystal polymer layers and filling powder/fluororesin varnish layer The sum of the thicknesses is 200 μm.

Example 5:

Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder and ultrasonically stir for 30 minutes, vacuum defoaming to obtain a uniformly dispersed mixed slurry, wherein the mass ratio of boron nitride, aluminum nitride powder and PFA emulsion 6.9︰9.8︰17.2 (the mass ratio of the converted nitride filled powder to pure PFA is 1.9︰1, and the mass ratio of boron nitride to aluminum nitride is 0.7︰1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Cover the upper and lower surfaces of the filling powder/PFA varnish obtained in step (2) with a liquid crystal polymer film, then place between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain high High-frequency flexible copper clad laminate material, wherein the thickness of copper foil is 12 microns, the thickness of liquid crystal polymer film is 25 microns, the hot pressing temperature is 315 °C, the hot pressing pressure is 5 MPa, the hot pressing time is 5 minutes, and the vacuum degree during vacuum hot pressing is -0.085MPa.

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.7 (10Ghz), dielectric loss 5.0×10 ^-3 (10Ghz), thermal conductivity 4.2 W/(mK), water absorption 0.08%, dimensional stability 0.054%, thermal decomposition temperature 453.9°C, flexible high frequency copper clad laminate material final thickness 224 microns, two liquid crystal polymer layers and filling powder/fluororesin varnish layer The sum of the thicknesses is 200 μm.

Comparative example 1:

Step (1): Take a certain amount of PFA emulsion, add boron nitride and aluminum nitride powder and ultrasonically stir for 30 minutes, vacuum defoaming to obtain a uniformly dispersed mixed slurry, wherein the mass ratio of boron nitride, aluminum nitride powder and PFA emulsion 9.6︰5.9︰17.2 (the mass ratio of the converted nitride filled powder to pure PFA is 1.8︰1, and the mass ratio of boron nitride to aluminum nitride is 1.6︰1);

Step (2): Use 1080 glass fiber cloth, soak the glass fiber cloth in the filler powder/PFA mixed slurry obtained in step (1), dry at 90°C for 10 minutes, dry the solvent, sinter at 320°C for 10 minutes, and then sinter at 320°C After vacuum hot pressing at 10 MPa for 20 minutes, a filling powder/PFA varnished cloth with a thickness of 150 μm was formed; the vacuum degree during vacuum hot pressing was -0.085 MPa.

Step (3): Arrange the filling powder/PFA paint obtained in step (2) between double-sided copper-clad foils, and then transfer to a vacuum hot press to obtain a high-frequency flexible copper-clad laminate material, in which the copper foil The thickness is 12 microns, the hot-pressing temperature is 315°C, the hot-pressing pressure is 5MPa, the hot-pressing time is 5min, and the vacuum degree during vacuum hot-pressing is -0.085MPa

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.7 (10Ghz), dielectric loss 2.8×10 ^-3 (10Ghz), thermal conductivity 5.7 W/(mK), water absorption rate of 2.45%, dimensional stability of 0.006%, thermal decomposition temperature of 444°C, and final thickness of the flexible high-frequency copper clad laminate material is 175 microns.

Comparative example 2:

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

Step (2): Premix the powders weighed in step (1) and put them into a twin-screw extruder for hot-melt blending, then extrude and granulate to obtain composite pellets, wherein the screw temperature is 325°C, The screw speed is 100r/min, and the blending time is 5min;

Step (3): Put the pellets obtained in step (2) into a vacuum hot press for hot-press molding to obtain a composite flexible high-frequency substrate. The hot-press temperature is 325°C, the hot-press pressure is 5MPa, and the hot-press time is 2min, the vacuum is -0.085MPa;

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

The flexible high-frequency copper clad laminate material obtained by the process formula prepared according to the aforementioned formula and process steps is: dielectric constant 3.7 (10Ghz), dielectric loss 2.6×10 ^-3 (10Ghz), thermal conductivity 4.25 W/(mK), water absorption rate 0.02%, dimensional stability 0.018%, thermal decomposition temperature 472 ℃, flexible high frequency copper clad laminate material final thickness is 180 microns.

According to the above performance test data, it can be seen that the high-frequency flexible copper-clad laminates prepared in Examples 1-5 of the present invention have excellent dielectric properties through the special design of the multi-layer structure. The Dk at 10 GHz is 3.4-3.8, and the lowest Df can reach 0.0017, good dimensional stability, all within ±0.1%, low water absorption, all within 0.1%, high thermal conductivity, up to 5.5W/(mK), good thermal stability, uniform thermal decomposition temperature Above 400°C.

Compared with the example of the present invention, the product of Comparative Example 1 does not use liquid crystal polymer film layer, and the final product is a three-layer sandwich structure applied by traditional technology. By comparing the product indexes of Example 3 and Comparative Example 1, it can be seen that because the surface of Example 3 is coated with a liquid crystal polymer film, the moisture in the environment is effectively isolated. Although the flexible high-frequency copper-clad laminate material prepared in Comparative Example 1 performed well in terms of dimensional stability and thermal conductivity, its high water absorption limited the practical application of the product in the field of high-frequency radio frequency.

Compared with the examples of the present invention, although liquid crystal polymer and fluororesin components are also used in this comparative example 2, fluororesin is not used to prepare filling powder/fluororesin varnish layer to realize separate use, and the final product is still Traditional copper clad laminate structure. By comparing the product indicators of Example 1 and Comparative Example 2, it can be seen that Example 1 achieves higher thermal conductivity than the traditional blending process through the layered structure design, and at the same time has higher dielectric properties and water absorption. The rate and dimensional stability are similar.

In summary, the layered structure design of the present invention has a relatively significant effect on improving the comprehensive performance of materials.

Claims (10)

1. The high-frequency flexible copper-clad plate material with the multilayer structure is characterized by comprising a laminated structure which is sequentially overlapped, and the high-frequency flexible copper-clad plate material comprises the following components in parts by weight: two copper foil layers positioned on the outermost surface, a filling powder/fluororesin paint layer positioned in the center, and two liquid crystal polymer film layers positioned between the copper foil layers and the filling powder/fluororesin paint layer;

the filling powder/fluororesin varnish layer is formed by taking glass fiber cloth as a substrate, and attaching a mixture of nitride filling powder and fluororesin to the surface of the glass fiber cloth through dipping, sintering and vacuum hot pressing treatment; the nitride filling powder is one or two of aluminum nitride and boron nitride.

2. The high-frequency flexible copper-clad plate material according to claim 1, wherein the mass ratio of the nitride filling powder to the fluororesin in the filling powder/fluororesin varnish layer is 1.5-2.3:1.

3. The high-frequency flexible copper-clad plate material according to claim 1, wherein the fluororesin is polytetrafluoroethylene perfluoroalkyl vinyl ether.

4. The high-frequency flexible copper-clad plate material according to claim 1, wherein the nitride filling powder is boron nitride and aluminum nitride, and the mass ratio of the boron nitride to the aluminum nitride is 0.3-1.6:1.

5. The high-frequency flexible copper-clad plate material according to claim 1, wherein the thickness of the copper foil layer is 12 μm; alternatively, the thickness of the filler powder/fluororesin varnish layer is 150 μm; alternatively, the thickness of the liquid crystal polymer film layer is 25 μm.

6. The high-frequency flexible copper-clad plate material according to claim 1, wherein the thickness of each copper foil layer is the same; alternatively, the thickness of each liquid crystal polymer film layer is the same.

7. The high-frequency flexible copper-clad plate material according to claim 1, wherein the sum of the thicknesses of the two liquid crystal polymer layers and the filler powder/fluororesin varnish layer is 200 μm.

8. The method for preparing the high-frequency flexible copper-clad plate material with the multilayer structure as claimed in claim 1, which is characterized by comprising the following steps:

(1) Adding the nitride filling powder into the fluororesin emulsion, and obtaining uniformly dispersed mixed slurry after ultrasonic stirring and vacuum defoaming;

(2) Dipping the glass fiber cloth into the mixed slurry, and drying, sintering and carrying out vacuum hot pressing treatment to obtain filling powder/fluororesin varnished cloth;

(3) Sequentially stacking all layers of materials according to the sequence of the copper foil, the liquid crystal polymer film, the filling powder/fluororesin varnished cloth, the liquid crystal polymer film and the copper foil; and then placing the material in a vacuum hot press for hot pressing to obtain the high-frequency flexible copper-clad plate material with the multilayer structure.

9. The method according to claim 8, wherein in the step (2), the drying is performed at a controlled temperature of 90 ℃ for 10min; the sintering temperature is 320 ℃ and the sintering time is 10min; the pressure is controlled to be 10MPa, the temperature is 320 ℃, the time is 20min, and the vacuum degree is-0.085 MPa during hot pressing.

10. The method according to claim 8, wherein in the step (3), parameters of the hot pressing process are set as follows: the pressure is 5MPa, the temperature is 315 ℃, the time is 5min, and the vacuum degree is-0.085 MPa.