1. The titanium dioxide filler with high dielectric property is characterized in that the titanium dioxide filler is micron-sized titanium dioxide powder, the crystalline phase of the titanium dioxide filler is rutile, the content of the titanium dioxide is more than or equal to 99.2 wt%, and the total content of impurity components is less than or equal to 0.8 wt%;

the composition and content of the impurity components are controlled as follows: 0.3 to 0.6 weight percent of barium oxide, less than or equal to 0.07 weight percent of calcium oxide, 0.03 to 0.06 weight percent of zirconium oxide, 0.02 to 0.04 weight percent of ferric oxide and less than or equal to 0.03 weight percent of sodium oxide.

2. The titanium dioxide filler with high dielectric properties as claimed in claim 1, wherein the titanium dioxide powder has a particle size of 1 μm to 30 μm.

3. The titanium dioxide filler with high dielectric property as claimed in claim 1 or 2, wherein the titanium dioxide powder has a form selected from the group consisting of spherical, angular and irregular forms.

4. A method for preparing the titanium dioxide filler with high dielectric property as defined in any one of claims 1-3, which comprises the following steps:

(1) adding water into the nano titanium dioxide to disperse to obtain slurry, doping the impurity components according to the selected components and content, and uniformly mixing for later use;

(2) drying the doped concentrated slurry to obtain micron-sized titanium dioxide aggregates;

(3) adding water into the obtained micron-sized titanium dioxide aggregate, uniformly dispersing, and carrying out hydrothermal reaction at the temperature of 200-230 ℃ to obtain spherical titanium dioxide powder with different particle sizes;

(4) and (3) carrying out high-temperature calcination treatment on the obtained spherical titanium dioxide powder at the temperature of 1000-1150 ℃ to obtain the spherical titanium dioxide powder with the required micron-sized particle size.

5. The method for preparing titanium dioxide filler with high dielectric properties as claimed in claim 4, wherein the temperature of the drying step in step (2) is 80-150 ℃.

6. The method for preparing titanium dioxide filler with high dielectric property as claimed in claim 4 or 5, wherein in the step (3), the micron-sized titanium dioxide aggregates are dispersed in water, the solid content is controlled to be 50-70%, and the filling amount is controlled to be 70-90%.

7. The method for preparing the titanium dioxide filler with high dielectric property as claimed in any one of claims 4 to 6, wherein the step (4) further comprises the step of pulverizing the spherical titanium dioxide powder to prepare micron-sized titanium dioxide powders with different morphologies.

8. Use of the high dielectric titanium dioxide filler of any one of claims 1-3 for the preparation of PTFE high frequency copper clad laminate substrates.

9. A PTFE high-frequency copper-clad plate substrate, which is characterized by comprising PTFE resin and the high-dielectric-property titanium dioxide filler of any one of claims 1 to 3.

10. A PTFE high-frequency substrate, which is characterized by being prepared from the PTFE high-frequency copper-clad plate base material of claim 9.

Background

With the popularization of 5G communication, society is highly informationized, electronic communication is also in a high-frequency era, and the use frequency of satellite communication, wireless networks and radar positioning systems is higher and higher. At present, in the high-frequency field, the main development trend of copper-clad plates is the multifunctional development of high density, thin wires, narrow spacing, high speed, low loss, high frequency, high reliability, multi-layer, low cost, automation and the like. In particular, the miniaturization, lightness, thinness and integration of electronic components have made higher requirements on high transmission rate, low transmission loss and less transmission delay of data transmission, and thus, the demand for high-frequency copper clad plates with high dielectric and low loss is more and more urgent. Meanwhile, in the field of microwave communication, transmission lines are also increasingly tending to be light, small, thin and short. According to the fundamental theory and design principle of microwave antennas, the size of a transmission line and the permittivity are in a negative correlation relationship, that is, the higher the permittivity, the smaller the size can be, so that a substrate with high dielectric constant and low dielectric loss is required. In particular, in the field of military aerospace, many high-precision microwave devices require a substrate material with a higher dielectric constant, and the dielectric constant is often greater than 10.3 at an application frequency of more than 10 GHz.

In the high-frequency board, the substrate material plays a role in ensuring the performance and reliability of the PCB, and plays an important role in improving the competitiveness of the product. Therefore, many PCB manufacturers focus their research on the substrate material selected when developing such products. The substrate material mainly comprises organic resin, copper foil, inorganic filler and the like, wherein PTFE is widely used as matrix resin of high-speed and high-frequency substrate material due to excellent microwave electrical properties such as low dielectric constant and low dielectric loss, and the change of the dielectric constant and the dielectric loss along with the increase of frequency is not obvious. However, the dielectric constant of PTFE is lower by about 2.1, and PTFE has poor mechanical properties, including poor resilience, strength and hardness, and thus has poor processability and high application cost. Therefore, in order to improve the dielectric properties of the substrate, improve the processability thereof and reduce the cost, researchers have been working on filling PTFE resin with a high dielectric constant filler to prepare a high-performance copper clad substrate.

Titanium dioxide, also known as titanium dioxide, has excellent electrical properties due to its high dielectric constant. Research shows that titanium dioxide is used as filler and added into PTFE polymer to raise the dielectric and mechanical performance of the polymer obviously. However, in the field of copper clad plates, due to the small particle size and large specific surface area of nano-scale materials, agglomeration is easy to occur, and when the nano-scale materials are filled in an organic resin system, the problems of high oil absorption value, high water absorption, unstable dielectric constant, difficulty in uniform dispersion and the like exist. The existing research shows that in order to meet the performance requirement under the 10GHz working frequency, when the copper-clad plate with the dielectric constant of 10.3 is prepared, the adding proportion of titanium dioxide ceramic powder is increased, but when the adding proportion of the titanium dioxide powder exceeds 70%, the powder agglomeration phenomenon occurs, and the problems of uneven dispersion, low plate toughness, substandard mechanical property and the like are caused.

Therefore, there is a need in the art to develop a micron-sized titanium dioxide powder with high dielectric constant and low dielectric loss at high frequency, so as to be suitable for the development of high-performance copper-clad board substrate under high frequency condition.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a micron-sized titanium dioxide powder with high dielectric constant and low dielectric loss, so as to be suitable for preparing a copper-clad plate substrate with high performance under a high-frequency condition;

the second technical problem to be solved by the present invention is to provide a PTFE high frequency copper clad laminate substrate and a PTFE high frequency substrate having excellent properties.

In order to solve the technical problems, the titanium dioxide filler with high dielectric property is micron-sized titanium dioxide powder, the crystalline phase of the titanium dioxide filler is in a rutile form, wherein the content of the titanium dioxide is more than or equal to 99.2 wt%, and the total content of impurity components is less than or equal to 0.8 wt%;

the composition and content of the impurity components are controlled as follows: 0.3 to 0.6 weight percent of barium oxide, less than or equal to 0.07 weight percent of calcium oxide, 0.03 to 0.06 weight percent of zirconium oxide, 0.02 to 0.04 weight percent of ferric oxide and less than or equal to 0.03 weight percent of sodium oxide.

Specifically, the particle size of the titanium dioxide powder is 1-30 μm.

Specifically, the forms of the titanium dioxide powder comprise a spherical shape, an angular shape and an irregular shape.

The invention also discloses a method for preparing the titanium dioxide filler with high dielectric property, which comprises the following steps:

(1) adding water into the nano titanium dioxide to disperse to obtain slurry, doping the impurity components according to the selected components and content, and uniformly mixing for later use;

(2) drying the doped concentrated slurry to obtain micron-sized titanium dioxide aggregates;

(3) adding water into the obtained micron-sized titanium dioxide aggregate, uniformly dispersing, and carrying out hydrothermal reaction at the temperature of 200-230 ℃ to obtain spherical titanium dioxide powder with different particle sizes;

(4) and (3) carrying out high-temperature calcination treatment on the obtained spherical titanium dioxide powder at the temperature of 1000-1150 ℃ to obtain the spherical titanium dioxide powder with the required micron-sized particle size.

In particular, the followingIn the step (1), the nano titanium dioxide can be processed by using a commercially available product, or a nano titanium dioxide precursor (the precursor is BET) can be prepared by taking Ti salt as a raw material and performing hydrolysis or hydrothermal synthesis>80m²And/g, anatase phase), washing to remove impurity ions adsorbed on the surface (washing to the conductivity of 100 mu S/cm), and concentrating to obtain slurry for directly doping the impurity components.

In the step (1), the dispersing step is preferably a tank mill mixing treatment, and the solid content and the filling content of the slurry are preferably controlled to be 20% and 60%.

Specifically, in the step (2), the temperature of the drying step is 80-150 ℃.

Specifically, in the step (3), in the step of adding water to disperse the micron-sized titanium dioxide aggregates, the solid content is controlled to be 50-70%, and the filling amount is controlled to be 70-90%.

Specifically, in the step (3), the hydrothermal reaction time is controlled to be 24-60 h.

Specifically, the step (4) further comprises a step of crushing the obtained spherical titanium dioxide powder to prepare micron-sized titanium dioxide powder with different morphologies, wherein the preferable crushing step is air flow crushing, and the preferable grinding step is sand milling to prepare angular titanium dioxide.

The invention also discloses application of the titanium dioxide filler with high dielectric property in preparation of a PTFE high-frequency copper-clad plate base material.

The invention also discloses a PTFE high-frequency copper-clad plate base material, namely the base material comprises PTFE resin and the titanium dioxide filler with high dielectric property.

The invention also discloses a PTFE high-frequency substrate which is prepared from the PTFE high-frequency copper-clad plate base material.

The micron-sized titanium dioxide powder filler with high dielectric property takes nano-sized titanium dioxide grains as raw materials, and prepares the required micron-sized titanium dioxide powder through high-temperature calcination by stably and accurately controlling the components and the content of impurity elements. In the calcining process, impurity ions with larger ionic radius can enter titanium dioxide crystal lattices to further form larger degree of crystal lattice distortion, so that the polarization strength of positive and negative ions is increased, and the dielectric constant of the obtained micron-sized titanium dioxide powder is improved.

According to the micron-sized titanium dioxide powder filler with high dielectric property, the optimization of the dielectric property of the material is realized by stably and accurately controlling the components and the content of impurity elements, and in the preparation process of titanium dioxide, when various impurity elements are in the preparation process of titanium dioxide, ions such as Ba enter crystal lattices to cause crystal lattice distortion and strengthen polarization, so that the dielectric constant of the titanium dioxide is improved, and the doping content of the impurities needs to be carefully controlled; if the content of Zr, Ca and other element ions exceeds the control range, the Zr, Ca and other element ions can be dispersed on the surface of the particles to influence the sintering activity; and if the content of the ions is too high, the ions conduct electricity in the working process, and further the electric energy is converted into the heat energy to cause the increase of the dielectric loss. Therefore, the micron-sized titanium dioxide powder material disclosed by the invention is prepared by carefully selecting the composition and content proportion of each impurity element, so that the titanium dioxide powder filler with ideal dielectric property is obtained, the preparation method is simple and feasible, and the stable and controllable product is easily prepared in an industrial production manner.

After the micron-sized titanium dioxide powder filler with high dielectric property is compounded with PTFE resin, the dielectric constant Dk is more than 11 and the dielectric loss Df is less than 0.003 under the detection of 10GHz, so that the new performance requirement of a PTFE high-frequency substrate can be met.

Drawings

In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,

FIG. 1 is an electron micrograph of spherical titanium dioxide having a D50 value of 15 μm prepared in example 2 of the present invention;

FIG. 2 is an electron micrograph of spherical titanium dioxide having a D50 value of 25 μm prepared in example 5 of the present invention;

FIG. 3 is an electron micrograph of titanium dioxide having an angular shape of 3 μm D50 prepared in example 6 according to the present invention;

FIG. 4 is an electron micrograph of titanium dioxide having an angular shape D50 of 5 μm prepared in example 7 of the present invention.

Detailed Description

Examples 1 to 7

The preparation method of the micron-sized titanium dioxide powder with high dielectric property, as shown in the following embodiments 1 to 7, comprises the following steps:

(1) taking Ti salt to synthesize a nano-scale titanium dioxide precursor by hydrolysis or hydro-thermal synthesis, wherein the precursor is BET>80m²(iv)/g, anatase phase; washing the obtained nano-scale titanium dioxide precursor to remove impurity ions adsorbed on the surface, and washing until the conductivity is 100 mu S/cm;

performing ball milling mixing on the obtained precursor slurry (controlling the solid content to be 20%, the filling content to be 60% and 0.65mm zirconium balls) to disperse uniformly, selecting a corresponding compound according to the doping proportion (wt%) listed in the following table 1 to dope impurity ions, and fully and uniformly mixing for later use;

(2) drying the slurry obtained in the step (1) for 12 hours in a vacuum drying oven at the temperature of 80-150 ℃ to obtain a titanium dioxide aggregate;

(3) adding the micron-sized titanium dioxide aggregate obtained in the step (2) into water to adjust the solid content to be 60% and the filling content to be 80%, and carrying out hydrothermal reaction for 24 hours at the temperature of 200-230 ℃ to obtain spherical titanium dioxide powder;

(4) the obtained spherical titanium dioxide is subjected to high-temperature calcination treatment, the specific calcination mode is shown in the following table 1, micron-sized titanium dioxide powder (spherical powder with the particle size of 15-25 μm) with different particle sizes is obtained, and the obtained titanium dioxide powder is subjected to airflow pulverization according to needs to obtain angular titanium dioxide powder with different particle sizes (examples 6-7).

Comparative examples 1 to 4

The following comparative examples 1 to 4 were conducted in the same manner as in examples 1 to 7 except that the impurity compounds were doped at different doping ratios, and the specific doping ratios are shown in Table 1 below.

TABLE 1 impurity compound doping ratio (wt%) and process parameter control conditions

Numbering	TiO2	BaO	CaO	ZrO2	Fe2O3	Na2O	Calcination conditions	Form/sand grinding
									Example 1	99.6	0.3	0.04	0.03	0.02	0.01	1000℃/8h	Ball type/without
Example 2	99.5	0.4	0.02	0.03	0.03	0.02	1000℃/8h	Ball type/without
									Example 3	99.5	0.4	0.01	0.06	0.02	0.01	1000℃/8h	Ball type/without
Example 4	99.3	0.6	0.00	0.05	0.02	0.03	1000℃/8h	Ball type/without
									Comparative example 1	99.8	0.1	0.01	0.05	0.03	0.02	1000℃/8h	Ball type/without
Comparative example 2	99.1	0.8	0.05	0.03	0.01	0.01	1000℃/8h	Ball type/without
									Comparative example 3	99.5	0.4	0.08	0.01	0.01	0.00	1000℃/8h	Ball type/without
Comparative example 4	99.5	0.4	0.00	0.08	0.02	0.00	1000℃/8h	Ball type/without
									Example 5	99.5	0.4	0.02	0.03	0.03	0.02	1150℃/10h	Ball type/without
Example 6	99.5	0.4	0.02	0.03	0.03	0.02	1000℃/8h	Angular/jet milling
									Example 7	99.5	0.4	0.02	0.03	0.03	0.02	1150℃/10h	Angular/jet milling

Examples of the experiments

1. Particle size and particle morphology

The particle sizes and particle morphologies of the titanium dioxide powders obtained in examples 1 to 7 and comparative examples 1 to 4 were measured, and the results are reported in table 2 below.

TABLE 2 particle size D50 and morphology of titanium dioxide powder

2. Dielectric properties

The dielectric properties of the titanium dioxide powders obtained in examples 1 to 7 and comparative examples 1 to 4 were measured by the SPDR method.

The sample preparation method comprises the following steps: and (3) mechanically mixing PTFE resin with the different titanium dioxide powder samples (volume ratio is 1: 1) uniformly, and rolling and forming to obtain a sheet with the thickness of 0.4-0.6 mm.

The results of the performance testing are shown in Table 3 below.

Table 3 results of performance testing

Numbering	Dk	Df	H(mm)
				Example 1	11.78	0.0023	0.514
Example 2	11.89	0.0022	0.493
				Example 3	11.90	0.0026	0.496
Example 4	12.03	0.0019	0.492
				Comparative example 1	10.2	0.0016	0.497
Comparative example 2	12.10	0.0039	0.506
				Comparative example 3	11.61	0.0034	0.499
Comparative example 4	11.30	0.0037	0.508
				Example 5	11.76	0.0024	0.492
Example 6	12.20	0.0016	0.494
				Example 7	12.06	0.0019	0.466

Therefore, when the micron-sized titanium dioxide powder prepared by the method is used for preparing a PTFE high-frequency substrate material, the dielectric constant Dk of the product is more than 11, the dielectric loss Df is less than 0.003 under the detection of 10GHz, the dielectric property is better, and the new performance requirement of the PTFE high-frequency substrate can be met.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.