CN114380579A

CN114380579A - Low-dielectric-constant low-temperature co-fired ceramic material and preparation method of green ceramic tape thereof

Info

Publication number: CN114380579A
Application number: CN202210075120.2A
Authority: CN
Inventors: 尚勇; 陈传庆; 韩玉成; 杨俊�; 张秀; 敖来远; 班秀峰; 何创创
Original assignee: China Zhenhua Group Yunke Electronics Co Ltd
Current assignee: China Zhenhua Group Yunke Electronics Co Ltd
Priority date: 2022-01-22
Filing date: 2022-01-22
Publication date: 2022-04-22

Abstract

A low-dielectric constant low-temperature co-fired ceramic material and a preparation method of a green ceramic tape thereof belong to the field of electronic components. The low-temperature co-fired ceramic material comprises: 15 to 50 percent of potassium borosilicate glass, 15 to 55 percent of alumina, 40 to 80 percent of silicon oxide and 3 to 20 percent of boron oxide; the main raw materials of the potassium borosilicate glass comprise potassium oxide, boron oxide and silicon oxide; the particle size D50 of the silicon oxide is 1.5-2.5 μm, and the particle size D50 of the aluminum oxide is 3-6 μm. The preparation method of the green porcelain band comprises the steps of material mixing, primary ball milling, high-temperature smelting, secondary ball milling, casting material mixing, screen printing, low-temperature sintering and the like. The problems of high relative dielectric constant and high dielectric loss of the existing LTCC material under the high frequency of 15GHZ are solved. The method is widely applied to 5G high-frequency products.

Description

Low-dielectric-constant low-temperature co-fired ceramic material and preparation method of green ceramic tape thereof

Technical Field

The invention belongs to the field of electronic components, and further relates to the field of LTCC ceramic materials, in particular to a low-dielectric-constant low-temperature co-fired ceramic material and a preparation method of a green ceramic tape thereof.

Background

With the application of 5G technology, the market of electronic components is rapidly growing, which requires the development of electronic components toward high frequency and high integration. The Low Temperature Co-fired ceramics (LTCC) technology can realize that three basic components (resistors, capacitors and inductors) and various passive devices (such as filters, transformers and the like) thereof are packaged in a multilayer wiring substrate, and are integrated with active devices (transistors and IC modules) into a finished circuit module. Wherein, engineers use a large amount of LTCC materials with relative dielectric constant between 4 and 9 when designing the circuit. The lower the relative dielectric constant of the material, the faster the transmission speed of the signal and the lower the transmission delay. When the operating frequency reaches the millimeter wave frequency band, the size of the device is reduced to millimeter level, and the importance of device miniaturization is reduced compared with the deterioration of system performance. Therefore, in order to overcome the associated disadvantages of increased frequency, the relative dielectric constant of low temperature co-fired ceramic materials must be reduced. On the other hand, metals such as silver and copper co-fired with LTCC materials have a low melting point, which requires that the sintering temperature of LTCC materials be lower than the melting point of metal electrodes. In conclusion, the development of a low-temperature co-fired ceramic material with a low relative dielectric constant is of great significance for meeting the high-frequency application of electronic components.

The LTCC materials which are commercialized at present generally have higher dielectric constants, such as A6M material of Ferro company, the material system is Ca-B-Si glass ceramics, the relative dielectric constant of the material is 5.7, and the dielectric loss is 0.002; dupont951 material with a relative dielectric constant of 7.5 developed by Dupont corporation in the United states has a material system of Pb-B-Si glass and aluminum oxide composite, and the material has a high dielectric loss of 0.004. The Japan NEC company developed an MLS-25M Al-B-Si glass-alumina ceramic composite material having a relative dielectric constant of 4.8 and a dielectric loss of 0.002 at 1MHZ, but the dielectric loss of the material was as high as 0.004 at 15 GHz. MLS-25M materials have higher losses at high frequencies and are not suitable for 5G applications. Therefore, the development of a low-temperature co-fired ceramic material with the dielectric constant lower than 5 and the dielectric loss lower than 0.003 at the high frequency of 15GHz is of great significance for 5G application.

LTCC materials generally include glass ceramic systems (composite of glass and crystalline ceramic, typical materials such as Dupont951), and microcrystalline glass systems (devitrification of all-glass systems, typical materials such as the A6M material from Ferro corporation). Also, for example, Dupont9K7 material, which encompasses the reaction mechanism of both glass-ceramic and glass-ceramic systems.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the problem of the current LTCC material relative dielectric constant is higher than 5 under 15GHZ high frequency, dielectric loss is higher than 0.004, and the application of the electronic component of the LTCC material under the GHZ high frequency is limited is solved.

The invention is based on the idea of using B₂O₃、Bi₂O₃、V₂O₅The low-melting point oxide is used as a sintering aid of the ceramic crystalline phase, and the low-melting point oxide can effectively reduce the sintering temperature of the ceramic crystalline phase. The LTCC green tape with uniform thickness and no defect is prepared by tape casting of a K-B-Si-Al potassium borosilicate system low-temperature co-fired ceramic material taking silicon oxide and aluminum oxide as crystalline phases, so that the LTCC ceramic material with the relative dielectric constant lower than 5 and the dielectric loss lower than 0.003 at the frequency of 15GHZ is realized.

Therefore, the invention provides a low-temperature co-fired ceramic material with a low relative dielectric constant, which adopts a K-B-Si-Al low-temperature co-fired ceramic material taking silicon oxide and aluminum oxide as crystalline phases and comprises the following components in percentage by mass: 15 to 50 percent of potassium borosilicate glass, 15 to 55 percent of alumina, 40 to 80 percent of silicon oxide and 3 to 20 percent of boron oxide.

The main raw materials of the potassium borosilicate glass comprise potassium oxide, boron oxide and silicon oxide;

the particle size D50 of the silicon oxide is 1.5-2.5 μm, and the particle size D50 of the aluminum oxide is 3-6 μm.

The potassium borosilicate glass comprises the following components in percentage by mass: 1 to 10 percent of potassium oxide, 30 to 60 percent of boron oxide and 40 to 70 percent of silicon oxide. The raw porcelain band of the material is prepared by ball milling, drying, preparing casting material and casting molding.

The potassium borosilicate glass also comprises cerium oxide, and the addition of the rare earth oxide helps to enhance the chemical stability of the glass structure and inhibit the precipitation of boron oxide.

The potassium borosilicate glass also includes barium oxide, the alkaline earth metal oxide has larger ion radius, and the barium oxide is added to help occupy the channel for ion movement, so that the movement of potassium ions in the glass is limited, and the dielectric loss is reduced.

The potassium borosilicate glass comprises the following components in percentage by mass: 1 to 10 percent of potassium oxide, 20 to 57 percent of boron oxide, 45 to 65 percent of silicon oxide, 0.5 to 1.5 percent of cerium oxide and 0.5 to 3 percent of barium oxide.

The low-temperature co-fired ceramic material comprises the following components in percentage by mass: 16 to 25 percent of potassium borosilicate glass, 18 to 22 percent of alumina, 63 to 75 percent of silicon oxide and 8 to 11 percent of boron oxide. Under the condition, the crystalline phase of the low-temperature co-fired ceramic material comprises a silicon oxide phase and an aluminum oxide phase, the relative dielectric constant of the low-temperature co-fired ceramic material is less than 5, and the dielectric loss of the low-temperature co-fired ceramic material is less than 0.003.

The low-temperature co-fired ceramic material has a relative dielectric constant of 3.76-4.82 at a frequency of 15GHZ, a dielectric loss of less than 0.003, a thermal expansion coefficient of 4.1 ppm/DEG C-7.2 ppm/DEG C, and a bending strength of 164 MPa-198 MPa.

The preparation method of the green ceramic tape of the low-temperature co-fired ceramic material with the low relative dielectric constant comprises the following steps:

(1) preparing materials: according to the stoichiometric ratio, potassium carbonate, boron oxide, silicon oxide, barium carbonate and cerium oxide are used as raw material ingredients of the potassium borosilicate glass.

(2) Primary ball milling: adding deionized water into the raw materials prepared in the step (1), mixing, and then ball-milling; after the ball milling was completed, the slurry was placed in an oven at 100 ℃ for 24 hours and then sieved.

(3) Molten glass: and (3) putting the powder obtained in the step (2) into a platinum crucible, smelting at 1300-1700 ℃ to form glass liquid, and performing water extraction and ultra-cooling to obtain the potassium borosilicate glass.

(4) Secondary ball milling: and (4) carrying out primary vibration crushing on the glass blocks obtained in the step (3), and carrying out secondary ball milling on the crushed glass powder by using alumina balls and deionized water as ball milling media. After the ball milling was completed, the slurry was placed in an oven at 100 ℃ for 24 hours and then sieved.

(5) Casting and batching: and (4) mixing and ball-milling the potassium borosilicate glass powder obtained in the step (4) with silicon oxide, aluminum oxide and boron oxide, wherein the ball-milling solvent is dimethylbenzene and absolute ethyl alcohol, and the used dispersing agents are herring fish oil and phosphate. Wherein the dispersion mechanism of the herring oil is steric hindrance; the phosphate ester is used for improving the surface charge of the powder, and the dispersion purpose is achieved through the charge repulsion between the powder.

(6) Tape casting: and (4) carrying out vacuum defoaming treatment on the casting slurry obtained in the step (5), and finally obtaining the LTCC green tape with excellent quality at a casting speed of (0.5-1.0) m/min.

(7) Screen printing: and (4) screen printing silver paste on the single layer of the LTCC green tape obtained in the step (6), then laminating 5 layers of the tape, and performing warm water isostatic pressing under 40MPa to form the LTCC blocks.

(8) And (3) sintering: and (3) placing the LTCC barblocks obtained in the step (7) in a sintering furnace, removing glue at 450 ℃ for 2 hours, heating to 840-890 ℃ at a heating rate of 5-8 ℃/min, preserving heat for 15-30 min, and naturally cooling to room temperature.

Compared with the prior art, the invention has the advantages that:

the dielectric constant of the K-B-Si-Al low-temperature co-fired ceramic material obtained by the invention is 3.76-4.82, which is lower than that of the existing commercial LTCC material, and the dielectric loss of the K-B-Si-Al low-temperature co-fired ceramic material is less than 0.003 at the frequency of 15GHZ, so that the transmission loss of electromagnetic signals at high frequency can be reduced, and the signal transmission speed can be increased. Meanwhile, the invention can be sintered at low temperature of 840-890 ℃, and is matched with Ag co-firing, thus having good chemical compatibility. In addition, the bending strength of the LTCC three-dimensional circuit module is 164 MPa-198 MPa, and the LTCC three-dimensional circuit module meets the application requirement of the LTCC three-dimensional circuit module. The coefficient of thermal expansion of the material is 4.1 ppm/DEG C-7.2 ppm/DEG C, and the coefficient of thermal expansion can be adjusted. The material has a thermal expansion coefficient of about 4.1 ppm/DEG C, and is matched with the thermal expansion coefficient of silicon. When the thermal expansion coefficient of the material is about 7.2 ppm/DEG C, the material is close to that of high-purity alumina ceramics, and has better thermal stability in an alumina film circuit.

In conclusion, the material disclosed by the invention is simple to prepare, can be subjected to tape casting, and can be widely applied to 5G high-frequency products.

Drawings

FIG. 1 is a schematic diagram of the phase structure of the sintered material in example 1.

FIG. 2 is a schematic representation of the sintered microstructure of the material of example 1.

FIG. 3 is a schematic diagram showing the phase structure of the sintered material in example 2.

FIG. 4 is a schematic representation of the sintered microstructure of the material of example 2.

FIG. 5 is a schematic diagram showing the phase structure of the sintered material in example 3.

FIG. 6 is a schematic representation of the sintered microstructure of the material of example 3.

Detailed Description

The technical scheme of the invention has the following specific implementation modes:

the material compositions (in mass%) of examples 1 to 3 are shown in table 1.

Table 1 comparative table (mass percentage) of material compositions of examples 1 to 3

Example 1:

(1) preparing materials: according to the stoichiometric ratio of Table 1, potassium carbonate, boron oxide, barium carbonate and cerium oxide were used as raw material ingredients of the potassium borosilicate glass.

(3) Molten glass: and (3) putting the powder obtained in the step (2) into a platinum crucible, smelting at the temperature of 1500 +/-20 ℃ to form glass liquid, and extracting with water to obtain the potassium borosilicate glass after ultra-cold.

(5) Casting and batching: mixing the potassium borosilicate glass powder obtained in the step (4) with silicon oxide and boron oxide according to the proportion in the table 1, and carrying out ball milling on the mixture, wherein ball milling solvents are dimethylbenzene and absolute ethyl alcohol, and dispersing agents are herring fish oil and phosphate ester. Wherein the dispersion mechanism of the herring oil is steric hindrance; the phosphate ester is used for improving the surface charge of the powder, and the dispersion purpose is achieved through the charge repulsion between the powder.

(8) And (3) sintering: and (3) placing the LTCC barblocks obtained in the step (7) in a sintering furnace, discharging glue at 450 ℃ for 2 hours, heating to 840-890 ℃ at a heating rate of (5-8) DEG C/min, preserving heat for 20min, and naturally cooling to room temperature.

The performance parameters of the glass-ceramic material provided in example 1 at different sintering temperatures are shown in table 2. From Table 2 it can be seen that the dielectric constant of the glass-ceramic material at 15GHz is between 3.76 and 3.92, and that it has a maximum bending strength of 172MPa at a sintering temperature of 880 ℃.

Table 2 properties of example 1 at different sintering temperatures

The XRD diffractogram of the glass ceramic material provided in example 1 is shown in fig. 1, and it can be seen from the XRD diffractogram that when the filling components are only silicon oxide and boron oxide, the crystalline phase is only silicon oxide phase; fig. 2 shows the microstructure of the glass-ceramic material provided in this embodiment, and it can be seen from fig. 2 that the microstructure of the material consists of a large amount of liquid phase, and the silicon oxide crystal grains are embedded in the glass phase, and the structure is dense.

Example 2:

(1) and (2) batching, namely taking potassium carbonate, boron oxide, silicon oxide, barium carbonate and cerium oxide as raw material batching of the potassium borosilicate glass according to the stoichiometric ratio.

(2) Performing primary ball milling, namely adding deionized water into the raw materials prepared in the step (1) for mixing and then performing ball milling; after the ball milling was completed, the slurry was placed in an oven at 100 ℃ for 24 hours and then sieved.

(3) And (3) melting glass, namely putting the powder obtained in the step (2) into a platinum crucible, smelting at the temperature of 1550 +/-20 ℃ to form glass liquid, and performing water extraction and ultra-cooling to obtain the potassium borosilicate glass.

(4) And (4) secondary ball milling, namely performing primary vibration crushing on the glass blocks obtained in the step (3), and performing secondary ball milling on the crushed glass powder by using alumina balls and deionized water as ball milling media. After the ball milling was completed, the slurry was placed in an oven at 100 ℃ for 24 hours and then sieved.

(5) And (3) casting and compounding, namely mixing the potassium borosilicate glass powder obtained in the step (4) with alumina and boron oxide, and performing ball milling on the mixture, wherein the ball milling solvent is xylene and absolute ethyl alcohol, and the used dispersing agents are herring fish oil and phosphate. Wherein the dispersion mechanism of the herring oil is steric hindrance; the phosphate ester is used for improving the surface charge of the powder, and the dispersion purpose is achieved through the charge repulsion between the powder.

(6) And (3) tape casting, namely performing vacuum defoaming treatment on the tape casting slurry obtained in the step (5), and finally obtaining the LTCC green tape with excellent quality at a tape casting speed of (0.5-1.0) m/min.

(7) And (4) screen printing, namely screen printing silver paste on the single layer of the LTCC green tape obtained in the step (6), laminating 5 layers of the silver paste, and performing warm water isostatic pressing under 40MPa to form the LTCC blocks.

(8) And (3) sintering, namely placing the LTCC barblock obtained in the step (7) in a sintering furnace, discharging glue at 450 ℃ for 2 hours, heating to 840-890 ℃ at the heating rate of (5-8) DEG C/min, preserving heat for 20min, and naturally cooling to room temperature.

The performance parameters of the glass-ceramic material provided in example 2 at different sintering temperatures are shown in table 3. From Table 3 it can be seen that the dielectric constant of the glass-ceramic material at 15GHz is between 4.56 and 4.82, and that it has a maximum bending strength of 198MPa at a sintering temperature of 880 ℃.

Table 3 properties of example 2 at different sintering temperatures

The XRD diffractogram of the glass ceramic material provided in example 2 is shown in fig. 3, and it can be seen from the XRD diffractogram that when the filling components are only alumina and boron oxide, the crystal phase is only alumina phase; fig. 4 shows the micro-morphology of the glass-ceramic material provided in this embodiment, and it can be seen from fig. 4 that the micro-morphology of the material is a dense structure composed of alumina grains and liquid phase.

Example 3:

(3) And (3) melting glass, namely putting the powder obtained in the step (2) into a platinum crucible, smelting at the temperature of 1480 +/-20 ℃ to form glass liquid, and performing water extraction and ultra-cooling to obtain the potassium borosilicate glass.

(5) And (3) casting and compounding, namely mixing the potassium borosilicate glass powder obtained in the step (4) with silicon oxide, aluminum oxide and boron oxide, and performing ball milling on the mixture, wherein ball milling solvents comprise xylene and absolute ethyl alcohol, and used dispersing agents comprise herring fish oil and phosphate. Wherein the dispersion mechanism of the herring oil is steric hindrance; the phosphate ester is used for improving the surface charge of the powder, and the dispersion purpose is achieved through the charge repulsion between the powder.

(8) And (3) sintering, namely placing the LTCC barblocks obtained in the step (7) in a sintering furnace, discharging glue at 450 ℃ for 2 hours, heating to 840-890 ℃ at the heating rate of (5-8) DEG C/min, preserving heat for 20min, and naturally cooling to room temperature.

The performance parameters of the glass-ceramic material provided in example 3 at different sintering temperatures are shown in table 4. From Table 4, it can be seen that the dielectric constant of the glass-ceramic material at 15GHz is between 4.32 and 4.48, and the glass-ceramic material has a maximum bending strength of 178MPa at a sintering temperature of 860 ℃.

Table 4 properties of example 3 at different sintering temperatures

The XRD diffractogram of the glass ceramic material provided in example 3 is shown in fig. 5, and it can be seen from the XRD diffractogram that when the filler components are silica, alumina and boria, the crystalline phases thereof include a primary crystalline phase of silica and a secondary crystalline phase of alumina; fig. 6 shows the microstructure of the glass-ceramic material provided in this embodiment, and it can be seen from fig. 6 that when the filling ceramic phase includes alumina and silica, the microstructure of the material is dense, and the crystal grains are embedded in the liquid phase of the material, so that the structure is dense.

Finally, it should be noted that: the above examples are merely examples for clarity of illustration, and the present invention includes but is not limited to the above examples, which are not necessarily exhaustive of all embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Embodiments that meet the requirements of the present invention are within the scope of the present invention.

Claims

1. A low-temperature co-fired ceramic material with a low relative dielectric constant is characterized by comprising the following components in percentage by mass: 15 to 50 percent of potassium borosilicate glass, 15 to 55 percent of alumina, 40 to 80 percent of silicon oxide and 3 to 20 percent of boron oxide;

2. The low-relative-dielectric-constant low-temperature co-fired ceramic material of claim 1, wherein the potassium borosilicate glass comprises the following components by mass percent: 1 to 10 percent of potassium oxide, 30 to 60 percent of boron oxide and 40 to 70 percent of silicon oxide.

3. The low relative dielectric constant low temperature co-fired ceramic material of claim 1, wherein the potassium borosilicate glass further comprises cerium oxide.

4. The low relative dielectric constant low temperature co-fired ceramic material of claim 1, wherein the potassium borosilicate glass further comprises barium oxide.

5. The low-relative-dielectric-constant low-temperature co-fired ceramic material of claim 1, wherein the potassium borosilicate glass comprises the following components by mass percent: 1 to 10 percent of potassium oxide, 20 to 57 percent of boron oxide, 45 to 65 percent of silicon oxide, 0.5 to 1.5 percent of cerium oxide and 0.5 to 3 percent of barium oxide.

6. A low-relative-dielectric-constant low-temperature co-fired ceramic material as claimed in any one of claims 1 to 5, comprising, in mass percent: 16 to 25 percent of potassium borosilicate glass, 18 to 22 percent of alumina, 63 to 75 percent of silicon oxide and 8 to 11 percent of boron oxide.

7. The low-relative-dielectric-constant low-temperature co-fired ceramic material according to any one of claims 1 to 5, wherein the low-temperature co-fired ceramic material has a relative dielectric constant of 3.76 to 4.82 at a frequency of 15GHZ, a dielectric loss of less than 0.003, a coefficient of thermal expansion of 4.1 ppm/DEG C to 7.2 ppm/DEG C, and a bending strength of 164MPa to 198 MPa.

8. The method for preparing the green ceramic tape of the low-relative-dielectric-constant low-temperature co-fired ceramic material according to claim 1, comprising the following steps:

(1) preparing materials: according to the stoichiometric ratio, taking potassium carbonate, boron oxide, silicon oxide, barium carbonate and cerium oxide as raw material ingredients of the potassium borosilicate glass;

(2) primary ball milling: adding deionized water into the raw materials prepared in the step (1), mixing, and then ball-milling; after the ball milling is finished, placing the slurry in an oven at 100 ℃ for 24 hours, and then sieving;

(3) molten glass: putting the powder obtained in the step (2) into a platinum crucible, smelting at 1300-1700 ℃ to form glass liquid, and carrying out water extraction and ultra-cooling to obtain potassium borosilicate glass;

(4) secondary ball milling: carrying out primary vibration crushing on the glass blocks obtained in the step (3), carrying out secondary ball milling on the crushed glass powder by using alumina balls and deionized water as ball milling media, placing the slurry in an oven at 100 ℃ for 24 hours after the ball milling is finished, and then sieving to obtain potassium borosilicate glass powder;

(5) casting and batching: mixing and ball-milling the potassium borosilicate glass powder obtained in the step (4) with silicon oxide, aluminum oxide and boron oxide, wherein the ball-milling solvent is dimethylbenzene and absolute ethyl alcohol, and the used dispersing agents are herring fish oil and phosphate ester to obtain casting slurry;

(6) tape casting: carrying out vacuum defoaming treatment on the casting slurry obtained in the step (5), and then obtaining the LTCC green tape at the casting speed of 0.5-1.0 m/min;

(7) screen printing: performing screen printing of silver paste on the single layer of the LTCC green tape obtained in the step (6), then laminating 5 layers of thickness, and performing warm water isostatic pressing under 40MPa to form an LTCC block;

(8) and (3) sintering: and (3) placing the LTCC barblocks obtained in the step (7) in a sintering furnace, discharging glue at 450 ℃ for 2 hours, heating to 840-890 ℃ at the heating rate of 5-8 ℃/min, preserving heat for 15-30 min, and naturally cooling to room temperature.

9. The method for preparing the green ceramic tape of the low-temperature co-fired ceramic material with the low relative dielectric constant as claimed in claim 8, wherein the ingredients in the step (1) are, by mass percent, one ingredient, two ingredients or three ingredients:

the first ingredient is as follows: k₂CO₃2.1% of B₂O₃14.5% of SiO₂16.7% of CeO₂0.2% of BaCO₃1.0% of SiO₂60.5% of B₂O₃Is 5%;

and the second ingredient: k₂CO₃1.8% of B₂O₃14.1% of SiO₂27.7% of CeO₂0.4% of BaCO₃2.0% of Al₂O₃46% and B₂O₃8 percent;

and the third ingredient is: k₂CO₃0.9% of B₂O₃6.5% of SiO₂16.0% of CeO₂0.4% of BaCO₃1.2% of Al₂O₃28.6% of SiO₂42.9% of B₂O₃The content was found to be 3.5%.

10. The method for preparing green ceramic tape of low-temperature co-fired ceramic material with low relative dielectric constant as claimed in claim 9, wherein:

the smelting temperature of the first ingredient is 1500 +/-20 ℃, the dielectric constant at 15GHz is 3.76-3.92, the dielectric loss is 0.0020-0.0025, and the maximum bending strength is 172MPa at the sintering temperature of 880 ℃;

the smelting temperature of the second ingredient is 1550 +/-20 ℃, the dielectric constant of the second ingredient is 4.56-4.82 at 15GHz, the dielectric loss of the second ingredient is 0.0011-0.0022, and the second ingredient has the maximum bending strength of 198MPa at the sintering temperature of 880 ℃;

the smelting temperature of the third ingredient is 1480 +/-20 ℃, the dielectric constant of the third ingredient is 4.32-4.48 at 15GHz, the dielectric loss is 0.0016-0.0023, and the maximum bending strength of the third ingredient is 174MPa at the sintering temperature of 880 ℃.