CN116285169A - A kind of fluorine-containing resin-based resin composition and its application - Google Patents

Abstract

The invention provides a fluorine-containing resin-based resin composition and its application. The fluorine-containing resin-based resin composition includes 20-70 parts of fluorine-containing resin and 30-70 parts of flame-processed silica in parts by weight; The purity of silicon dioxide is >99.99%, and the average particle size D50 is 5‑10 μm. In the fluorine-containing resin-based resin composition of the present invention, the purity and particle size of the flame-processed silica synergistically bring about lower dielectric loss and higher electric strength, and have a lower dielectric constant, so that the containing The substrate of the fluororesin-based resin composition obtains more excellent comprehensive performance, and meets various performance requirements for copper clad laminate materials in the high-frequency communication field.

Description

A kind of fluorine-containing resin-based resin composition and its application

technical field

The invention belongs to the technical field of laminated boards, and relates to a fluorine-containing resin-based resin composition and an application thereof.

Background technique

In recent years, with the continuous development of 5G communication technology, satellite communication, radar system, automobile anti-collision system, electronic navigation and high integrated circuit technology, electronic products continue to develop in the direction of high-frequency and high-speed signal transmission. In the field of high-frequency copper-clad laminates, fluorine-containing resins represented by polytetrafluoroethylene (PTFE) have many advantages such as low dielectric constant, low dielectric loss, high thermal stability and chemical stability that other polymer resins cannot match. It is an ideal base material for copper clad laminates.

Since the invention of PTFE-based CCL in the 1950s, researchers have gradually improved its manufacturing process through continuous optimization of formula and parameters. The polymer chain of fluorine-containing resin is relatively flexible, and it is usually necessary to introduce inorganic fillers to improve the mechanical strength of fluorine-containing resin-based copper-clad laminates; spherical silica has good filling properties, and is currently the most common inorganic filler in fluororesin-based copper-clad laminates. filler. For example, CN104175686A discloses a method for preparing a microwave circuit PTFE composite dielectric substrate. The method includes: first mixing a fluororesin emulsion, an inorganic filler and a thickener to obtain a stable and uniform dispersion, and then coating the dispersion Cover on a releaseable substrate, separate the resin layer from the substrate after baking, laminate the separated resin layer with copper foil, laminate and sinter at high temperature, and obtain a PTFE composite dielectric substrate with double-sided copper foil clad ; Wherein, the inorganic filler is preferably silicon dioxide and/or titanium dioxide. CN101838431A discloses a fluororesin mixture and a copper clad laminate made using it. The fluororesin mixture includes a polytetrafluoroethylene perfluoroalkyl vinyl ether emulsion, a polytetrafluoroethylene emulsion, an inorganic filler and a diluent. The inorganic filler It is silica powder, kaolin or titanium dioxide. US4849284A discloses a PTFE emulsion with silicon micropowder as the main filler to make a high-frequency copper-clad laminate with low dielectric constant and low thermal expansion coefficient. However, the introduction of a large amount of inorganic fillers is usually accompanied by a decline in dielectric properties and insulation reliability. With the innovation of communication technology and the development of high-frequency and high-speed development, the above-mentioned copper clad It is difficult to meet the performance requirements of electronic products in terms of electrical performance, reliability, and stability.

CN113652042A discloses the use of chemical spherical silicon with a purity of 99.99%, which can obtain excellent dielectric properties and withstand voltage performance, but the invention uses silicon dioxide with a small particle size, resulting in a dielectric loss that cannot be lowered. CN112574521A discloses a fluorine-containing resin composition, the fluorine-containing resin composition includes the following components: fluorine-containing polymer 30wt%-70wt% inorganic filler 30wt%-70wt%; the inorganic filler includes the following particle size distribution: D10 is greater than 1.5 μm, and D50 is 10-15 μm; although the D50 particle size is large and the dielectric loss has been improved, the insulation performance of the board cannot be higher.

Therefore, in this field, it is expected to develop a material that can make the copper clad laminate have more excellent dielectric properties and higher electric strength.

Contents of the invention

Aiming at the deficiencies of the prior art, the object of the present invention is to provide a fluorine-containing resin-based resin composition and its application.

For reaching this purpose, the present invention adopts following technical scheme:

In the first aspect, the present invention provides a fluorine-containing resin-based resin composition, which includes 20-70 parts by weight of fluorine-containing resin and 30-70 parts of flame-processed silica; The purity of the silicon dioxide is >99.99%, and the average particle diameter D50 is 5-10 μm.

In the present invention, by selecting flame-process silica with a purity greater than 99.99%, and requiring the silica particle size D50 to be 5-10 μm, under the synergistic effect of silica purity and particle size, a more excellent comprehensive Performance, low dielectric constant, lower dielectric loss, and higher electrical strength, meeting the performance requirements of copper clad laminate materials in the high-frequency communication field.

In the present invention, the content of fluorine-containing resin in the fluorine-containing resin-based resin composition can be 20 parts, 25 parts, 30 parts, 40 parts, 50 parts, 60 parts or 70 parts, and the content of silicon dioxide is 30 parts, parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts or 70 parts.

In the present invention, the purity of the silicon dioxide is >99.99%, such as 99.992%, 99.994%, 99.996%, 99.998% or 99.999%. When the silicon dioxide purity is greater than 99.99%, the dielectric loss of the plate containing the fluorine-containing resin-based resin composition is significantly reduced.

In the present invention, the particle size D50 of the flame method silica is 5-10 μm, such as 5 μm, 5.5 μm, 5.8 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm. When the average particle size D50 of silicon dioxide is less than 5 μm, the loss of the plate containing the fluorine-containing resin-based resin composition cannot be lowered, and when the D50 is too low, the insulation performance of the plate cannot be higher, When the average particle diameter D50 is larger than 10 μm, the insulating properties of the board containing the fluorine-containing resin-based resin composition cannot be made higher. It is further preferably 5.5-6.9 μm, and the dielectric loss and electric strength of the plate are further optimized.

Preferably, the D100 of the flame-processed silica is ≤ 30 μm, for example, the D100 is 30 μm, 25 μm, 20 μm, 18 μm or 15 μm, etc. When the D100 is greater than 30 μm, the electrical strength of the sheet cannot be made higher.

In the present invention, the purity of the silicon dioxide is measured by an inductively coupled atomic emission spectrometer ICP-AES, and the average particle size of the silicon dioxide is measured by a Malvern 3000 laser particle size analyzer.

In the present invention, the preparation method of the flame-processed silica comprises the following steps: crushing and classifying high-purity fused silica powder with a purity >99.99%, to obtain fused silica powder with an average particle diameter D50 of 5-10 μm, and passing The flame method is prepared to obtain the flame method silica.

Preferably, the conductivity of the flame-processed silica is less than or equal to 20 μS/cm, such as 20 μS/cm, 18 μS/cm, 16 μS/cm, 14 μS/cm, 12 μS/cm, 10 μS/cm, 8 μS/cm, 5 μS/cm cm, 3μS/cm, etc.

In the present invention, the electrical conductivity of the flame-processed silica is measured by a Star A212 electrical conductivity meter.

Preferably, the silica includes surface-treated silica;

Preferably, the surface treatment agent includes any one or a combination of at least two of silane coupling agent, borate coupling agent, zirconate coupling agent or phosphate coupling agent, more preferably silane coupling agent;

Preferably, the silane coupling agent includes any one or a combination of at least two of fluorine-containing silane coupling agents, amino silane coupling agents or epoxy silane coupling agents;

Preferably, based on 100% of the mass of silicon dioxide to be surface treated, the amount of the surface treatment reagent is 0.05-1%, such as 0.05%, 0.08%, 0.1%, 0.3%, 0.5%, 0.7% , 0.9% or 1%.

Preferably, the fluorine-containing resin is selected from polytetrafluoroethylene, polytetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, polyperfluoroethylene propylene, polytetrafluoroethylene-perfluoroalkoxy perfluoroethylene Any one or a combination of at least two of base ether copolymers, polyvinylidene fluoride emulsions, ethylene-tetrafluoroethylene copolymers, polychlorotrifluoroethylene or ethylene-trifluoroethylene copolymers.

In the present invention, the fluorine-containing resin is provided by a fluorine-containing resin emulsion.

Preferably, the fluorine-containing resin-based resin composition also includes other fillers, and the other fillers include titanium dioxide, barium titanate, strontium titanate, chopped glass fiber, aluminum oxide, boron nitride, silicon nitride, hollow glass Any one or a combination of at least two of microbeads or hollow silica.

Preferably, the chopped glass fiber has a diameter of 0.5-10 μm (for example, 0.5 μm, 1 μm, 3 μm, 5 μm, 5.5 μm, 5.8 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10μm), other fillers except chopped glass fiber D50 at 5-10μm (such as 5μm, 5.5μm, 5.8μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm or 10μm ).

Preferably, the amount of other fillers added in the fluorine-containing resin-based resin composition is 0-10 parts by weight, such as 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight or 10 parts by weight.

Preferably, the fluorine-containing resin-based resin composition further includes a thickener.

Preferably, the thickener is polyoxyethylene distyrenated phenyl ether, sodium dodecylbenzenesulfonate, nonylphenol polyoxyethylene ether, sodium lauryl sulfate or polydimethylsilane Any one or a combination of at least two of them.

In a second aspect, the present invention provides a resin film comprising the fluorine-containing resin-based resin composition as described in the first aspect.

The resin composition of the first aspect is coated on the surface of PI film (polyimide film) with coating machine, obtains the PI film of gluing, places the PI film of gluing in high-temperature oven to bake, cools Finally, the resin layer and the PI film are peeled off to obtain a resin film.

In a third aspect, the present invention provides a prepreg, the prepreg comprising a reinforcing material, and the fluorine-containing resin-based resin composition as described in the first aspect attached to the reinforcing material by impregnation.

Preferably, the reinforcing material is one or a combination of at least two of natural fibers, organic synthetic fibers, organic fabrics, and inorganic fibers.

In a fourth aspect, the present invention provides a metal-clad board, the metal-clad board includes at least one resin film as described in the second aspect or at least one prepreg as described in the third aspect and is laminated Metal foil on both sides of the prepreg.

In a fifth aspect, the present invention provides a printed circuit board, which includes the resin film as described in the second aspect, the prepreg as described in the third aspect, or the coating as described in the fourth aspect. At least one of the copper plates.

Compared with the prior art, the present invention has the following beneficial effects:

In the fluorine-containing resin-based resin composition of the present invention, the purity and particle size of the flame-processed silica synergistically bring about lower dielectric loss and higher electric strength, and have a lower dielectric constant, so that the containing The substrate of the fluororesin-based resin composition obtains more excellent comprehensive performance, and meets various performance requirements for copper clad laminate materials in the high-frequency communication field.

Detailed ways

The technical solutions of the present invention will be further described below through specific embodiments. It should be clear to those skilled in the art that the examples are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

The present embodiment provides a fluorine-containing resin-based resin composition, which includes 20 parts by weight of polytetrafluoroethylene (PTFE emulsion, the resin solid content is 60%, the SN-1 of Chenguang Company, the addition amount is 33.4 parts), 10 parts of titanium dioxide (D50 is 5.5 μm, STO-500D of Shandong Guoci) and 70 parts of silicon dioxide (prepared by flame method, D50 is 5 μm, D100 is 15 μm, purity is 99.994%, from Jiangsu Lianrui).

This embodiment also provides a resin film and a copper clad laminate, the specific preparation method of which is as follows:

(1) PTFE emulsion, titanium dioxide and silicon dioxide of above-mentioned consumption are mixed, high-speed stirring mixes 2h, and the viscosity that records glue solution is 220mPa.s; Above-mentioned glue solution is coated on PI film (polyester) with coating machine imide film) to obtain a glue-coated PI film; place the glue-coated PI film in a vacuum oven at 100 ° C for 1 h to remove moisture, and bake at 260 ° C for 1 h to remove the additive (increase Thickener), baked at 350°C for 10 minutes, and peeled off the resin layer and PI film after cooling to obtain a 129 μm resin film with uniform thickness and good appearance;

(2) The two 129 μm thick resin films obtained in step (1) are laminated, and the size is 250mm × 250mm, and the upper and lower sides of the laminated resin film are covered with 1OZ thick copper foil, laminated, and applied The pressure is 400PSI, the highest temperature is 380°C, and the retention time is 60min, and laminated to obtain a copper clad laminate with an intermediate dielectric layer thickness of 0.254mm.

Example 2

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 70 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 116.7 parts) and 30 parts by weight Parts of silica (prepared by flame method, D50 is 5.5 μm, D100 is 15 μm, purity is 99.994%, from Jiangsu Lianrui).

This embodiment also provides a resin film and a copper clad laminate, the specific preparation method of which is as follows:

(1) Mix the PTFE emulsion and silicon dioxide in the above amount, add 0.6 parts of thickener (polyoxyethylene distyrenated phenyl ether, EMULGEN A-60 from Kao Corporation), stir and mix at high speed for 2 hours, The viscosity that records glue is 260mPa.s; Above-mentioned glue is coated on the surface of PI film (polyimide film) with coating machine, obtains the PI film of gluing; Place the PI film of gluing In a vacuum oven at 100°C, bake for 1 hour to remove moisture, bake at 260°C for 1 hour to remove additives (thickeners), bake at 350°C for 10 minutes, and peel off the resin layer and PI film after cooling to obtain 65μm resin film with uniform thickness and good appearance;

(2) 4 sheets of 64.5 μm thick resin films obtained in step (1) are stacked, and the size is 250mm × 250mm, and the upper and lower sides of the stacked resin films are covered with 1OZ thick copper foil for lamination, The applied pressure is 400PSI, the highest temperature is 380°C, and the retention time is 60min, and laminated to obtain a copper-clad laminate with an intermediate dielectric layer thickness of 0.254mm.

Example 3

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 38 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 63.3 parts) in parts by weight, 2 1 part of chopped fiber (chopped fiber diameter 0.7 μm, from Jiangsu Lianrui) and 60 parts of silica (prepared by flame method, D50 is 6 μm, D100 is 18 μm, purity is 99.994%, from Jiangsu Lianrui).

This embodiment also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 1.

Example 4

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silica (prepared by flame method, D50 is 6.9 μm, D100 is 20 μm, purity is 99.996%, from Jiangsu Lianrui).

This embodiment also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 1.

Example 5

The present embodiment provides a fluorine-containing resin-based resin composition, which includes 41 parts by weight of polytetrafluoroethylene emulsion (PTFE emulsion, the resin solid content is 60%, the SN-1 of Chenguang Company, the addition amount is 68.3 parts), 5 parts of tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (PFA emulsion, the resin solid content is 50%, Sichuan Chenguang PFA-E50, the addition amount is 10 parts), 4 parts of titanium dioxide (D50 is 5.5 μ m, Shandong State Porcelain STO-500D) and 50 parts of silicon dioxide (prepared by flame method, D50 is 10 μm, D100 is 28 μm, purity is 99.994%, from Jiangsu Lianrui).

This embodiment also provides a resin film (with a thickness of 64.5 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 2.

Example 6

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 46 parts by weight of perfluoroethylene propylene copolymer (FEP emulsion, resin solid content is 50%, ND-110 of Japanese Daikin Company, addition amount 92 ), 4 parts of titanium dioxide (D50 is 5.5 μm, STO-500D of Shandong Guoci) and 50 parts of silicon dioxide (prepared by flame method, D50 is 10 μm, D100 is 28 μm, purity is 99.994%, from Jiangsu Lianrui) .

This embodiment also provides a resin film (with a thickness of 64.5 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 2.

Example 7

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silicon dioxide (prepared by flame method, D50 is 6 μm, D100 is 18 μm, purity is 99.996%, from Jiangsu Lianrui; the reagent for surface treatment is epoxy silane coupling agent (KBM403 of Shin-Etsu Chemical), the amount of reagent 0.3% of the amount of silicon dioxide).

This embodiment also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 1.

Example 8

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Part silicon dioxide (prepared by flame method, D50 is 9 μm, D100 is 25 μm, purity is 99.994%, comes from Jiangsu Lianrui; the reagent for surface treatment is perfluorosilane coupling agent (F823 of Shandong Silicon Branch), the amount of reagent 0.3% of the amount of silicon dioxide).

This embodiment also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 1.

Example 9

The present embodiment provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silica (prepared by flame method, D50 is 6.5 μm, D100 is 36 μm, purity is 99.996%, from Jiangsu Lianrui).

This embodiment also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Embodiment 1.

Comparative example 1

This comparative example provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silica (prepared by flame method, D50 is 3.7 μm, D100 is 11 μm, purity is 99.994%, from Jiangsu Lianrui).

This comparative example also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Example 1.

Comparative example 2

This comparative example provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silica (prepared by flame method, D50 is 14 μm, D100 is 45 μm, purity is 99.994%, from Jiangsu Lianrui).

This comparative example also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Example 1.

Comparative example 3

This comparative example provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Part silicon dioxide (prepared by flame method, D50 is 6.9 μm, D100 is 20 μm, purity is 99.98%, from Jiangsu Lianrui).

This comparative example also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Example 1.

Comparative example 4

This comparative example provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silicon dioxide (prepared by flame method, D50 is 6 μm, D100 is 18 μm, purity is 99.98%, comes from Jiangsu Lianrui; the reagent for surface treatment is epoxy silane coupling agent (KBM403 of Shin-Etsu Chemical), the amount of reagent 0.3% of the amount of silicon dioxide).

This comparative example also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Example 1.

Comparative Example 5

This comparative example provides a kind of fluorine-containing resin-based resin composition, comprises 35 parts of polytetrafluoroethylene (PTFE emulsion, resin solid content is 60%, the SN-1 of morning light company, addition amount 58.3 parts) and 65 parts by weight Parts of silicon dioxide (prepared by organosilicon hydrolysis, average particle size D50 is 0.5 μm, D100 is 3 μm, purity is 99.996%, from Jiangsu Huimai).

This comparative example also provides a resin film (with a thickness of 129 μm) and a copper clad laminate (with an intermediate dielectric layer with a thickness of 0.254 mm), the specific preparation method of which is the same as that of Example 1.

Carry out performance test to the copper-clad board that embodiment 1～9, comparative example 1～5 provide, specific method is as follows:

(1) Dielectric constant Dk and dielectric loss Df: Tested by SPDR (Split Post Dielectric Resonator) method, the test condition is A state, and the frequency is 10GHz;

(2) Electric strength: tested by IPC-TM-650 2.5.6.2A method;

The performance test data are shown in Table 1.

Table 1

As can be seen from Table 1, compared with Comparative Examples 1-5, Examples 1-9 of the present invention adopt high-purity (purity greater than 99.99%) flame-process silica, and limit the silica particle size to D50 5-10μm, under the synergistic effect of the purity and particle size of silica, lower dielectric loss (below 0.00048) and higher electric strength performance (above 70) can be obtained, and has a lower dielectric loss Constant (below 3.8). It can be seen from Examples 1-9 that when D50 is preferably 5-6.9 μm, while ultra-low dielectric loss is obtained, the electric strength is also significantly improved. When D50 is preferably 5.5-6.9 μm, the dielectric loss of the plate And electric strength is further optimized.

The applicant declares that the present invention illustrates the fluorine-containing resin-based resin composition of the present invention and its application through the above examples, but the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to implement . Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A fluorine-containing resin-based resin composition characterized by comprising 20 to 70 parts by weight of a fluorine-containing resin and 30 to 70 parts by weight of flame process silica; the purity of the silicon dioxide is more than 99.99 percent, and the average particle diameter D50 is 5-10 mu m.

2. The fluorine-containing resin composition according to claim 1, wherein the flame-process silica has an average particle diameter D50 of 5.5 to 6.9 μm;

preferably, D100 of the flame process silica is less than or equal to 30 μm.

3. The fluorine-containing resin composition according to claim 1 or 2, wherein the method for producing flame-process silica comprises the steps of: crushing and grading molten silicon micro powder with purity more than 99.99%, obtaining molten silicon micro powder with average particle diameter D50 of 5-10 mu m, and preparing flame-process silicon dioxide with purity more than 99.99% by a flame process;

preferably, the conductivity of the flame process silica is 20 μS/cm or less.

4. A fluorine-containing resin composition according to any one of claims 1 to 3, wherein the silica comprises a surface-treated silica;

preferably, the surface-treating agent includes any one or a combination of at least two of a silane coupling agent, a borate coupling agent, a zirconate coupling agent, and a phosphate coupling agent, and further preferably a silane coupling agent;

preferably, the silane coupling agent comprises any one or a combination of at least two of fluorine-containing silane coupling agent, amino silane coupling agent or epoxy silane coupling agent;

preferably, the surface treatment agent is used in an amount of 0.05 to 1% based on 100% by mass of the silica to be surface-treated.

5. The fluorine-containing resin composition according to any one of claims 1 to 4, wherein the fluorine-containing resin is selected from any one or a combination of at least two of polytetrafluoroethylene, polytetrafluoroethylene-fluoropropyl perfluorovinyl ether copolymer, polytetrafluoroethylene propylene, polytetrafluoroethylene-perfluoroalkoxy perfluorovinyl ether copolymer, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, polytrifluoroethylene or ethylene-chlorotrifluoroethylene copolymer;

preferably, the fluorine-containing resin is provided by a fluorine-containing resin emulsion.

6. The fluorine-containing resin composition according to any one of claims 1 to 5, further comprising any one or a combination of at least two of titanium dioxide, barium titanate, strontium titanate, chopped glass fibers, aluminum oxide, boron nitride, silicon nitride, hollow glass microspheres, or hollow silica;

preferably, the fluorine-containing resin-based resin composition further comprises a thickener;

preferably, the thickener is any one or a combination of at least two of polyoxyethylene biphenyl styrenated phenyl ether, sodium dodecyl benzene sulfonate, nonylphenol polyoxyethylene ether, sodium dodecyl sulfate and polydimethyl silane.

7. A resin film comprising the fluorine-containing resin-based resin composition according to any one of claims 1 to 6.

8. A prepreg comprising a reinforcing material, and the fluorine-containing resin-based resin composition according to any one of claims 1 to 6 attached to the reinforcing material by impregnation.

9. A metal-clad sheet comprising at least one resin film according to claim 7 or at least one prepreg according to claim 8 and metal foils on both sides of the prepreg after lamination.

10. A printed circuit board comprising at least one of the resin film according to claim 7, the prepreg according to claim 8, or the copper-clad plate according to claim 9.