A ceramic resonator and a method of manufacturing the same

Abstract

The application provides a ceramic resonator, which comprises a ceramic body A, a stepped through hole arranged in the center of the ceramic body A, the stepped through hole penetrating the ceramic body A through a small hole in the upper part and a large hole in the lower part, a first conductor layer covering the inner side of the small hole, a ceramic adhesive layer covering the inner side of the large hole, a ceramic body B embedded in the large hole of the ceramic body A, a second conductor layer covering the surface of the ceramic body B, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and communicates with the first conductor layer, and a third conductor layer covering the top surface, the side surface and the bottom surface of the ceramic body A. Compared with the prior art, the ceramic resonator provided by the application has the characteristics of small size and high Q value due to the specific structure and connection relationship, and has great market competitiveness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter, more particularly to a ceramic resonator and a preparation method thereof. BACKGROUND

[0002] With the development of 5G communication technology, ceramic dielectric filter is expected to become the mainstream technology, and has broad market prospects.

[0003] Miniaturization and light weight of ceramic filter is the industry trend, due to energy and heat dissipation problems, improving the Q value of resonator is both a technical pursuit and an environmental protection requirement. However, the high Q value of the ceramic resonator prepared by a single dielectric constant often means large size and large weight, so the solution of ensuring Q value under the premise of small volume is of great significance. SUMMARY

[0004] Therefore, the present application provides a new ceramic resonator for dielectric waveguide filter, which has a small volume and a Q value 30% higher than that of traditional ceramic resonators. The present application also provides a preparation method of the ceramic resonator, which is simple in process, low in equipment requirement and cost, easy to implement, and convenient for mass production. The present application provides a ceramic resonator and a preparation method thereof, which has great market competitiveness.

[0005] The present application provides a ceramic resonator, which comprises:

[0006] a ceramic body A, a stepped through hole is arranged at the center of the ceramic body A, the stepped through hole penetrates the ceramic body A through a small hole at the upper part and a large hole at the lower part, the inner side of the small hole is covered with a first conductor layer, and the inner side of the large hole is covered with a ceramic adhesive layer;

[0007] a ceramic body B embedded in the large hole of the ceramic body A, and a second conductor layer is arranged on the surface of the ceramic body B, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and is in communication with the first conductor layer;

[0008] a third conductor layer covering the top surface, side surface and bottom surface of the ceramic body A.

[0009] Preferably, the material of the ceramic body A is a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz.

[0010] Preferably, the material of the ceramic body B is a microwave dielectric material with a dielectric constant greater than that of the material of the ceramic body A and / or a QF value greater than or equal to 20000 GHz.

[0011] Preferably, the material of the first conductor layer is selected from one or more of copper, silver and gold.

[0012] The material of the second conductor layer is selected from one or more of copper, silver and gold;

[0013] The material of the third conductor layer is selected from one or more of copper, silver and gold.

[0014] Preferably, the small hole has a circular cross section; and the large hole has a circular or polygonal cross section.

[0015] The application also provides a preparation method of the ceramic resonator, comprising the following steps:

[0016] a) first dry-pressing the material of the ceramic body A and then performing first sintering to obtain the ceramic body A;

[0017] b) second dry-pressing the material of the ceramic body B and then performing second sintering to obtain the ceramic body B;

[0018] c) assembling the ceramic body B with the ceramic body A after plating the second conductor layer on the surface of the ceramic body B, sequentially performing vacuum compounding with ceramic adhesive, baking and high-temperature curing to form an integrated structure, and finally plating the first conductor layer and the third conductor layer on the surface of the integrated structure to obtain the ceramic resonator.

[0019] Preferably, the pressure of the first dry-pressing in step a) is 60-70 MPa; the temperature of the first sintering is 1300-1600 ℃, and the time is 3-5 h;

[0020] The pressure of the second dry-pressing in step b) is 60-70 MPa; the temperature of the second sintering is 1300-1600 ℃, and the time is 3-5 h.

[0021] Preferably, the thickness of the second conductor layer in step c) is 6-50 μm.

[0022] Preferably, the vacuum compounding of the ceramic adhesive in step c) is specifically as follows:

[0023] The assembled product is placed in a container containing ceramic adhesive, and the product and the container are simultaneously vacuumized for vacuum compounding.

[0024] Preferably, the temperature of the baking in step c) is 100-120 ℃, and the time is 10-30 min; the temperature of the high-temperature curing is 600-700 ℃, and the time is 30-120 min.

[0025] The application provides a ceramic resonator, comprising: a ceramic body A; a stepped through hole is arranged in the center of the ceramic body A; the stepped through hole penetrates the ceramic body A through a small hole in the upper part and a large hole in the lower part; the inner side of the small hole is covered with a first conductor layer; the inner side of the large hole is covered with a ceramic adhesive layer; a ceramic body B is embedded in the large hole of the ceramic body A; the surface of the ceramic body B is covered with a second conductor layer, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and is in communication with the first conductor layer; and a third conductor layer covers the top surface, the side surface and the bottom surface of the ceramic body A. Compared with the prior art, the ceramic resonator provided by the application has the characteristics of small size and high Q value due to the specific structure and connection relationship, and has great market competitiveness.

[0026] In addition, the application further provides a preparation method of the ceramic resonator, which has simple process, low equipment requirement, low cost and is easy to implement, thereby providing convenience for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The application provides a ceramic resonator. DETAILED DESCRIPTION

[0028] The technical solutions of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0029] The application provides a ceramic resonator, comprising:

[0030] a ceramic body A; a stepped through hole is arranged in the center of the ceramic body A; the stepped through hole penetrates the ceramic body A through a small hole in the upper part and a large hole in the lower part; the inner side of the small hole is covered with a first conductor layer; the inner side of the large hole is covered with a ceramic adhesive layer;

[0031] a ceramic body B embedded in the large hole of the ceramic body A; the surface of the ceramic body B is covered with a second conductor layer, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and is in communication with the first conductor layer;

[0032] a third conductor layer covering the top surface, the side surface and the bottom surface of the ceramic body A.

[0033] Please refer to Figure 1 , Figure 1 The application provides a ceramic resonator.

[0034] In the present application, the ceramic resonator comprises, preferably consists of, a ceramic body A, a ceramic body B and a conductor layer.

[0035] In the present application, the material of the ceramic body A is preferably a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz, more preferably a microwave dielectric material with a dielectric constant of 5-21 and a QF value greater than 40000 GHz. The present application does not have special restrictions on the source of the material of the ceramic body A, and high-performance microwave dielectric ceramic materials prepared by methods well known to those skilled in the art can be used. In the preferred embodiments of the present application, the material of the ceramic body A is a material with a dielectric constant of 11 and a QF value of 42000 GHz, or a material with a dielectric constant of 20.5 and a QF value of 65000 GHz, or a material with a dielectric constant of 5 and a QF value of 50000 GHz.

[0036] In the present application, the shape of the ceramic body A can be cylindrical or other shapes according to filter design, and the present application does not have special restrictions thereon; the center (geometric center) of the ceramic body A is provided with a stepped through-hole; the stepped through-hole penetrates the ceramic body A through a small hole at the upper part and a large hole at the lower part;

[0037] In the present application, the cross section of the small hole is preferably circular, and on this basis, the diameter of the small hole can be defined as D1; the cross section of the large hole is preferably circular or polygonal, preferably rectangular, and its size is defined as D2, including length x width.

[0038] In the present application, the inside of the small hole is covered with a first conductor layer; the inside of the large hole is covered with a ceramic adhesive layer.

[0039] In the present application, the material of the first conductor layer is preferably selected from one or more of copper, silver and gold, more preferably silver; the present application does not have special restrictions on the source of the material of the first conductor layer, and commercially available products well known to those skilled in the art can be used.

[0040] In the present application, the material of the ceramic body B is preferably a microwave dielectric material with a dielectric constant greater than that of the material of the ceramic body A and / or a QF value greater than or equal to 20000 GHz, more preferably a microwave dielectric material with a dielectric constant greater than that of the material of the ceramic body A and a QF value greater than or equal to 20000 GHz. The present application does not have special restrictions on the source of the material of the ceramic body B, and high-performance microwave dielectric ceramic materials prepared by methods well known to those skilled in the art can be used. In the preferred embodiments of the present application, the material of the ceramic body B is a material with a dielectric constant of 45 and a QF value of 40000 GHz, or a material with a dielectric constant of 65 and a QF value of 20000 GHz, or a material with a dielectric constant of 76 and a QF value of 20000 GHz.

[0041] In the present application, the shape of the ceramic body B is the same as the shape of the large hole of the ceramic body A, so as to ensure that the ceramic body B can be embedded in the large hole of the ceramic body A and completely fill the large hole of the ceramic body A.

[0042] In the present application, the surface of the ceramic body B is covered with a second conductor layer, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and communicates with the first conductor layer.

[0043] In the present application, the material of the second conductor layer is preferably selected from one or more of copper, silver and gold, and more preferably silver; the present application does not have special restrictions on the source of the material of the second conductor layer, and commercially available products known to those skilled in the art can be used.

[0044] In the present application, the third conductor layer covers the top surface, side surface and bottom surface of the ceramic body A; on this basis, the surface of the ceramic resonator is completely covered with a conductor layer, wherein the inside of the small hole of the ceramic body A is covered with a first conductor layer, the bottom surface of the blind hole formed by the small hole and the bottom surface after the large hole is filled with the ceramic body B are all covered with a second conductor layer, and the remaining part of the surface is covered with a third conductor layer.

[0045] In the present application, the material of the third conductor layer is preferably selected from one or more of copper, silver and gold, and more preferably silver; the present application does not have special restrictions on the source of the material of the third conductor layer, and commercially available products known to those skilled in the art can be used.

[0046] The present application adopts the above-mentioned high-performance microwave dielectric ceramic material as the main body of the ceramic resonator, and the ceramic resonator is mainly composed of two microwave dielectric ceramics, the overall shape of which is cylindrical or other shapes according to the design of the filter, and the surface is plated with a conductor layer; there is a blind hole in the geometric center of the ceramic resonator, the diameter of the blind hole is D1, the depth is H1, the other side of the blind hole is provided with a circular or polygonal filling hole with a size of D2 (D2>D1) and a depth of H2, and the hole is filled with a ceramic body B; the shape of the ceramic body B is consistent with that of the filling hole, the surface of the ceramic body B is plated with a conductor layer, so that the bottom surface of the blind hole (the conductor layer of the bottom surface of the blind hole communicates with the conductor layer of the side surface of the blind hole) and the bottom surface after the filling hole is filled with the ceramic body B are all covered with a conductor layer, and at the same time the entire surface of the resonator is plated with a conductor layer.

[0047] The ceramic resonator provided by the present application adopts a specific structure and connection relationship, and the harmonic frequency can be adjusted by adjusting the sizes of D1, D2, H1 and H2 and the dielectric constant of the ceramic; the second harmonic can be adjusted by adjusting the dielectric constant of the ceramic body B; the greater the sum of H1+H2, the lower the resonant frequency; the higher the dielectric constant of the ceramic body B, the lower the resonant frequency, the closer the second harmonic, the larger D1 and D2, the lower the resonant frequency; the ceramic resonator provided by the present application has the characteristics of small size and high Q value, and has great market competitiveness.

[0048] The application also provides a preparation method of the ceramic resonator, comprising the following steps:

[0049] a) performing first dry pressing of the material of the ceramic body A and then performing first sintering to obtain the ceramic body A;

[0050] b) performing second dry pressing of the material of the ceramic body B and then performing second sintering to obtain the ceramic body B;

[0051] c) assembling the ceramic body B with the ceramic body A after plating the second conductor layer on the surface of the ceramic body B, sequentially performing vacuum compounding, baking and high-temperature curing of the ceramic adhesive to form an integrated structure, and finally plating the first conductor layer and the third conductor layer on the surface of the integrated structure to obtain the ceramic resonator.

[0052] The application first performs first dry pressing of the material of the ceramic body A and then performs first sintering to obtain the ceramic body A. In the application, the material of the ceramic body A is the same as that in the above technical solution, and will not be repeated here.

[0053] The application does not have special restrictions on the device for the first dry pressing, and a dry powder presser known to those skilled in the art can be used; the pressure of the first dry pressing is preferably 60 MPa-70 MPa.

[0054] In the application, the temperature of the first sintering is preferably 1300-1600 °C, and the time is preferably 3-5 h.

[0055] Then, the application performs second dry pressing of the material of the ceramic body B and then performs second sintering to obtain the ceramic body B. In the application, the material of the ceramic body B is the same as that in the above technical solution, and will not be repeated here.

[0056] The application does not have special restrictions on the device for the second dry pressing, and a dry powder presser known to those skilled in the art can be used; the pressure of the second dry pressing is preferably 60 MPa-70 MPa.

[0057] In the application, the temperature of the second sintering is preferably 1300-1600 °C, and the time is preferably 3-5 h.

[0058] Finally, the application assembles the ceramic body B with the ceramic body A after plating the second conductor layer on the surface of the ceramic body B, sequentially performs vacuum compounding, baking and high-temperature curing of the ceramic adhesive to form an integrated structure, and finally plates the first conductor layer and the third conductor layer on the surface of the integrated structure to obtain the ceramic resonator. In the application, the materials of the first conductor layer, the second conductor layer and the third conductor layer are the same as those in the above technical solution, and will not be repeated here.

[0059] In the present application, the thickness of the first conductor layer, the second conductor layer and the third conductor layer is preferably 6-50 microns.

[0060] The present application does not have special restrictions on the assembling method, and the assembling of the ceramic body A and the ceramic body B can be performed according to the following steps. Figure 1 The assembling of the ceramic body A and the ceramic body B can be performed according to the following steps.

[0061] In the present application, the process of vacuum compounding of the ceramic adhesive is preferably as follows:

[0062] The assembled product is placed in a container containing the ceramic adhesive, and the product and the container are simultaneously vacuumized for vacuum compounding.

[0063] The present application does not have special restrictions on the type and source of the ceramic adhesive, and any ceramic adhesive known to those skilled in the art that can realize the bonding of the microwave dielectric ceramic can be used, and the ceramic adhesive finally forms a ceramic bonding layer.

[0064] In the present application, the baking temperature is preferably 100-120 DEG C, and the time is preferably 10-30 minutes, and a baking oven known to those skilled in the art can be used.

[0065] In the present application, the high-temperature curing temperature is preferably 600-700 DEG C, and the time is preferably 30-120 minutes; the present application does not have special restrictions on the device for high-temperature curing, and a high-temperature furnace known to those skilled in the art can be used.

[0066] The present application also provides a preparation method of the ceramic resonator, which has the advantages of simple process, low equipment requirement, low cost and easy implementation, and provides convenience for large-scale production.

[0067] The present application provides a ceramic resonator, comprising: a ceramic body A; the ceramic body A is provided with a stepped through hole in the center; the stepped through hole penetrates the ceramic body A through a small hole in the upper part and a large hole in the lower part; the inner side of the small hole is covered with a first conductor layer; the inner side of the large hole is covered with a ceramic adhesive layer; a ceramic body B embedded in the large hole of the ceramic body A; the surface of the ceramic body B is covered with a second conductor layer, wherein the second conductor layer on the top surface of the ceramic body B covers the small hole to form a blind hole and communicates with the first conductor layer; and a third conductor layer covers the top surface, the side surface and the bottom surface of the ceramic body A. Compared with the prior art, the ceramic resonator provided by the present application has the characteristics of small size and high Q value due to the specific structure and connection relationship, and has great market competitiveness.

[0068] In addition, the present application also provides a preparation method of the ceramic resonator, which has the advantages of simple process, low equipment requirement, low cost and easy implementation, and provides convenience for large-scale production.

[0069] In order to further illustrate the present application, the following examples are described in detail below. The structural schematic diagram of the ceramic resonator of the following examples of the present application is shown in Figure 1 The outer dimensions of the ceramic resonator are 10 mm x 10 mm x 5 mm or 10 mm x 10 mm x 6 mm (processing accuracy ± 0.05 mm), and the specific preparation method is as follows:

[0070] (1) A mold is prepared from tungsten steel according to the size of the resonant unit, and the material of the ceramic body A is dry-pressed into shape on a dry powder press with a forming pressure of 65 MPa. The formed product is sintered in a sintering furnace at a sintering temperature of 1450°C for 4 h to obtain the ceramic body A.

[0071] (2) A mold is prepared from tungsten steel according to the size of the resonant unit, and the material of the ceramic body B is dry-pressed into shape on a dry powder press with a forming pressure of 65 MPa. The formed product is sintered in a sintering furnace at a sintering temperature of 1450°C for 4 h to obtain the ceramic body B.

[0072] (3) A second conductor layer with a thickness of 25 μm to 30 μm is plated on the surface of the ceramic body B, and then the ceramic body A is assembled (placed in a ceramic adhesive with a viscosity of 1.0 Pa.s and a solid content of more than 85%) to form a whole structure by vacuum compounding (the product and the container are simultaneously vacuumed to a vacuum degree of less than 0.3 atm), baking (oven, 110°C, 20 min) and high-temperature curing (high-temperature furnace, 650°C, 70-80 min). Finally, a first conductor layer and a third conductor layer (both with a thickness of 15 μm to 25 μm) are plated on the surface of the above whole structure to obtain the ceramic resonator.

[0073] The materials used for the A ceramic body and the B ceramic body are microwave dielectric materials, which can be commercially available or self-made products known to those skilled in the art and meet the corresponding requirements, such as a material with a dielectric constant of 20.5 or 20.6, which can be prepared according to the preparation method in other patents such as ZL201310720204.8, a material with a dielectric constant of 11, which can be prepared according to the preparation method in other patents such as ZL201410166735.1, a material with a dielectric constant of 45, which can be prepared according to the preparation method in other patents such as ZL201510508571.0, and a material with a dielectric constant of 76, which can be prepared according to the preparation method in other patents such as ZL201910184979.5. The material of the conductor layer is silver.

[0074] Example 1

[0075] The ceramic body A is made of a material having a dielectric constant of 11 and a QF value of 42000 GHz, D1 is 4.0 mm in diameter, and H1 is 1.7 mm. The ceramic body B is made of a material having a dielectric constant of 45 and a QF value of 40000 GHz, D2 is a rectangular solid of 6.2 mm x 4.5 mm x 4.3 mm, and H2 is 4.3 mm. Thus, a ceramic resonator having a resonance frequency of 3570 GHz and a Q value of 1400 is obtained.

[0076] Example 2

[0077] The ceramic body A is made of a material having a dielectric constant of 20.5 and a QF value of 65000 GHz, D1 is 2.0 mm in diameter, and H1 is 1.0 mm. The ceramic body B is made of a material having a dielectric constant of 45 and a QF value of 40000 GHz, D2 is a rectangular solid of 2.5 mm x 2.5 mm x 4.0 mm, and H2 is 4.0 mm. Thus, a ceramic resonator having a resonance frequency of 3506 GHz and a Q value of 1650 is obtained.

[0078] Example 3

[0079] The ceramic body A is made of a material having a dielectric constant of 20.5 and a QF value of 65000 GHz, D1 is 2.0 mm in diameter, and H1 is 1.9 mm. The ceramic body B is made of a material having a dielectric constant of 45 and a QF value of 40000 GHz, D2 is a rectangular solid of 3.0 mm x 3.0 mm x 3.1 mm, and H2 is 3.1 mm. Thus, a ceramic resonator having a resonance frequency of 2690 GHz and a Q value of 1800 is obtained.

[0080] Example 4

[0081] The ceramic body A is made of a material having a dielectric constant of 5 and a QF value of 50000 GHz, D1 is 4.0 mm in diameter, and H1 is 1.0 mm. The ceramic body B is made of a material having a dielectric constant of 45 and a QF value of 40000 GHz, D2 is a rectangular solid of 6.2 mm x 4.5 mm x 5.0 mm, and H2 is 5.0 mm. Thus, a ceramic resonator having a resonance frequency of 3480 GHz and a Q value of 1400 is obtained.

[0082] Example 5

[0083] The ceramic body A is made of a material having a dielectric constant of 11 and a QF value of 42000 GHz, D1 is 4.0 mm in diameter, and H1 is 0.5 mm. The ceramic body B is made of a material having a dielectric constant of 65 and a QF value of 20000 GHz, D2 is a rectangular solid of 6.2 mm x 4.5 mm x 5.0 mm, and H2 is 5.0 mm. Thus, a ceramic resonator having a resonance frequency of 3420 GHz and a Q value of 1570 is obtained.

[0084] Example 6

[0085] The ceramic body A adopts a material with a dielectric constant of 11 and a QF value of 42000 GHz, D1 is 4.0 mm, and H1 is 1.0 mm; the ceramic body B adopts a material with a dielectric constant of 76 and a QF value of 20000 GHz, D2 is a cuboid with a size of 2.5 mm*2.5 mm*5.0 mm, and H2 is 5.0 mm, so that a ceramic resonator with a resonant frequency of 2550 GHz and a Q value of 1800 is obtained.

[0086] Table 1 Parameter data and effect data table of each embodiment and comparison group

[0087]

[0088] As shown in Table 1, compared with a resonator of a traditional ceramic filter, the ceramic resonator provided by the application has a smaller size or a lower frequency under the same size; meanwhile, the single-cavity Q value of the ceramic resonator provided by the application is higher, and the Q value is increased by more than 30% compared with a traditional resonator under the same volume and the same frequency.

[0089] The above description of disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ceramic resonator, comprising: Ceramic body A; a stepped through-hole is provided at the center of ceramic body A; the stepped through-hole penetrates ceramic body A through a small hole at the top and a large hole at the bottom; a first conductor layer is covered inside the small hole; a ceramic bonding layer is covered inside the large hole; the material of ceramic body A is a microwave dielectric material with a dielectric constant of 5~21 and a QF value greater than 40000GHz; A ceramic body B is embedded in a large hole in a ceramic body A; the surface of the ceramic body B is covered with a second conductor layer, wherein the second conductor layer on the top surface of the ceramic body B covers a small hole to form a blind hole and communicates with the first conductor layer; the material of the ceramic body B is a microwave dielectric material with a dielectric constant greater than that of the material of the ceramic body A and a QF value greater than or equal to 20000 GHz. A third conductor layer covering the top, side, and bottom surfaces of ceramic body A; The thicknesses of the first conductor layer, the second conductor layer, and the third conductor layer are all 6μm to 50μm.

2. The ceramic resonator according to claim 1, characterized in that, The material of the first conductor layer is selected from one or more of copper, silver, and gold; The material of the second conductor layer is selected from one or more of copper, silver, and gold; The material of the third conductor layer is selected from one or more of copper, silver, and gold.

3. The ceramic resonator according to claim 1, characterized in that, The cross-section of the small hole is circular; the cross-section of the large hole is circular or polygonal.

4. A method for fabricating a ceramic resonator as described in claim 1, comprising the following steps: a) After the material of ceramic body A is first dry-pressed into shape, it is sintered for the first time to obtain ceramic body A; b) After the material of ceramic body B is dry-pressed for the second time, it is sintered for the second time to obtain ceramic body B; c) After depositing the second conductor layer on the surface of ceramic body B, it is assembled with ceramic body A. The ceramic body B is then vacuum-bonded with ceramic adhesive, baked and cured at high temperature to form an integral structure. Finally, the first conductor layer and the third conductor layer are deposited on the surface of the integral structure to obtain a ceramic resonator.

5. The preparation method according to claim 4, characterized in that, The pressure of the first dry pressing in step a) is 60MPa~70MPa; the temperature of the first sintering is 1300℃~1600℃, and the time is 3h~5h. The pressure for the second dry pressing in step b) is 60MPa~70MPa; the temperature for the second sintering is 1300℃~1600℃, and the time is 3h~5h.

6. The preparation method according to claim 4, characterized in that, The vacuum bonding process of the ceramic binder described in step c) is specifically as follows: The assembled product is placed in a container containing ceramic binder, and the product and container are simultaneously vacuum-bonded.

7. The preparation method according to claim 4, characterized in that, The baking temperature in step c) is 100℃~120℃ and the time is 10min~30min; the high-temperature curing temperature is 600℃~700℃ and the time is 30min~120min.

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