A ceramic filter resonant unit and a method of manufacturing the same

Abstract

The application provides a ceramic filter resonant unit, which comprises an A ceramic body, a blind hole arranged in the center of the A ceramic body, a first conductor layer arranged on the inner side of the blind hole, a B ceramic body arranged on the bottom surface of the A ceramic body and in contact with the top surface of the A ceramic body, a second conductor layer arranged on the top surface of the B ceramic body and covering the blind hole, the second conductor layer being in communication with the first conductor layer, and a third conductor layer covering the top surface and the side surface of the A ceramic body and the bottom surface and the side surface of the B ceramic body. Compared with the prior art, the ceramic filter resonant unit provided by the application has the characteristics of small size and high Q value, and the second harmonic is far away, greater than 2 times the main frequency, and up to 3 times the main frequency, which has great market competitiveness.

Description

TECHNICAL FIELD

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

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

[0003] The ceramic resonator can greatly reduce the size and weight of the filter due to its small size and high Q value. However, the traditional ceramic coaxial resonant unit used in the current ceramic filter has a low Q value, and the second harmonic becomes closer to the main mode as the dielectric constant of the ceramic increases. The microwave dielectric ceramic with a dielectric constant of about 20.6 on the market usually has a second mode near 1.5 times the main frequency at 2.6G and 3.5G, which must be suppressed by an additional low-pass filter, further reducing the Q value of the filter. Therefore, it is of great significance to ensure high Q value, small size, and push away the second harmonic. SUMMARY

[0004] Therefore, the present application provides a new ceramic resonator for dielectric waveguide filter, which has a small size, a Q value higher than 40% of the traditional ceramic filter resonant unit, and a second harmonic pushed away more than 2 times the main frequency, up to 3 times the main frequency. In addition, the present application also provides a preparation method of the ceramic filter resonant unit, which is simple in process, low in equipment requirement, low in cost, easy to implement, and convenient for mass production. The present application provides a ceramic filter resonant unit and a preparation method thereof, which has great market competitiveness.

[0005] The present application provides a ceramic filter resonant unit, which comprises:

[0006] An A ceramic body, wherein a blind hole is arranged at the center of the A ceramic body, and a first conductor layer is arranged on the inner side of the blind hole;

[0007] A B ceramic body, wherein the top surface of the B ceramic body is in contact with and coincides with the bottom surface of the A ceramic body, a second conductor layer is arranged on the top surface of the B ceramic body, and the second conductor layer is in communication with the first conductor layer;

[0008] A third conductor layer, wherein the third conductor layer covers the top surface and the side surface of the A ceramic body, and the bottom surface and the side surface of the B ceramic body.

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

[0010] Preferably, the material of the B ceramic body is a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 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 diameter of the second conductor layer is greater than the diameter of the blind hole.

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

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

[0017] b) casting the material of the B ceramic body into a green tape, and then sequentially performing lamination, isostatic pressing and second sintering to obtain the B ceramic body;

[0018] c) silk-screening the second conductor layer on the top surface of the B ceramic body, assembling the A ceramic body and the B ceramic body, sequentially performing isostatic pressing and high-temperature curing to form an overall structure, and finally plating the first conductor layer and the third conductor layer on the surface of the overall structure to obtain the ceramic filter resonant unit.

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

[0020] Preferably, in step b), the thickness of the green tape is 150-250 μm; the pressure of the isostatic pressing is 55-65 MPa, and the time is 10-15 min; the temperature of the second sintering is 1300-1600 ℃, and the time is 3-5 h.

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

[0022] Preferably, in step c), the pressure of the isostatic pressing is 40-50 MPa; the temperature of the high-temperature curing is 600-700 ℃, and the time is 30-120 min.

[0023] The application provides a ceramic filter resonant unit, which comprises an A ceramic body, a blind hole arranged in the center of the A ceramic body, a first conductor layer covering the inner side of the blind hole, a B ceramic body in contact with and coinciding with the bottom surface of the A ceramic body, a second conductor layer arranged on the top surface of the B ceramic body and covering the blind hole, the second conductor layer being in communication with the first conductor layer, and a third conductor layer covering the top surface and side surface of the A ceramic body and the bottom surface and side surface of the B ceramic body.

[0024] In addition, the application further provides a preparation method of the ceramic filter resonant unit. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The application provides a ceramic filter resonant unit. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be apparently and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments of the application. Based on the embodiments of the application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0027] The application provides a ceramic filter resonant unit, which comprises:

[0028] an A ceramic body, a blind hole arranged in the center of the A ceramic body, a first conductor layer covering the inner side of the blind hole,

[0029] a B ceramic body in contact with and coinciding with the bottom surface of the A ceramic body, a second conductor layer arranged on the top surface of the B ceramic body and covering the blind hole, the second conductor layer being in communication with the first conductor layer,

[0030] and a third conductor layer covering the top surface and side surface of the A ceramic body and the bottom surface and side surface of the B ceramic body.

[0031] Please refer to Figure 1 , Figure 1 The application provides a ceramic filter resonant unit.

[0032] In the application, the ceramic filter resonant unit comprises, preferably consists of, an A ceramic body, a B ceramic body and a conductor layer.

[0033] In the present application, the material of the A ceramic body is preferably a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz, and 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 A ceramic body, and a high-performance microwave dielectric ceramic material prepared by a method well known to those skilled in the art can be used. In the preferred embodiments of the present application, the material of the A ceramic body is a material with a dielectric constant of 5 and a QF value of 50000 GHz, or a material with a dielectric constant of 20.5 and a QF value of 65000 GHz.

[0034] In the present application, the shape of the A ceramic body 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 A ceramic body is provided with a blind hole with a diameter of D1; the inner side of the blind hole is covered with a first conductor layer.

[0035] In the present application, the material of the first conductor layer is preferably one or more selected from copper, silver and gold, and more preferably silver; the present application does not have special restrictions on the source of the material of the first conductor layer, and a commercially available product well known to those skilled in the art can be used.

[0036] In the present application, the material of the B ceramic body is preferably a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz, and 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 B ceramic body, and a high-performance microwave dielectric ceramic material prepared by a method well known to those skilled in the art can be used. In the preferred embodiments of the present application, the material of the B ceramic body is a material with a dielectric constant of 5 and a QF value of 50000 GHz, or a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, or a material with a dielectric constant of 12 and a QF value of 40000 GHz.

[0037] In the present application, the dielectric constant of the material of the A ceramic body is preferably not greater than the dielectric constant of the material of the B ceramic body.

[0038] In the present application, the shape of the B ceramic body can be cylindrical or other shapes according to filter design, and the present application does not have special restrictions thereon, and is preferably matched with the shape of the A ceramic body, such as when the A ceramic body is cylindrical, the B ceramic body is also cylindrical and has the same outer diameter as the A ceramic body, so that they can be coincided together after assembly to form a structure with a whole cylindrical shape.

[0039] In the present application, the top surface of the B ceramic body is in contact with and coincides with the bottom surface of the A ceramic body; the top surface of the B ceramic body is provided with a second conductor layer covering the blind hole; and the second conductor layer is in communication with the first conductor layer.

[0040] 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; and 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.

[0041] In the present application, the diameter D2 of the second conductor layer is preferably greater than the diameter of the blind hole.

[0042] In the present application, the third conductor layer covers the top surface and side surface of the A ceramic body and the bottom surface and side surface of the B ceramic body; and on this basis, the surface of the ceramic filter resonant unit is completely covered by the conductor layer, wherein the inside of the blind hole of the A ceramic body is covered by the first conductor layer, the bottom surface formed by the blind hole and the B ceramic body is covered by the second conductor layer, and the remaining surface is covered by the third conductor layer.

[0043] 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; and 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.

[0044] The present application uses the above-mentioned high-performance microwave dielectric ceramic material as the main body of the resonant unit, the overall shape of the resonant unit is cylindrical or other shapes according to the design of the filter, the surface is plated with a conductor layer, there is a blind hole with a diameter of D1 in the geometric center of the resonant unit, a conductor layer (second conductor layer) with a diameter of D2 is plated in the ceramic at the bottom of the blind hole, which is in communication with the inner wall conductor layer (first conductor layer) of the stepped blind hole, and the inner conductor layer of the blind hole is in communication with the conductor layer outside the resonant unit.

[0045] The ceramic filter resonant unit provided by the application has the characteristics of small size and high Q value, and the second harmonic is far away, more than 2 times the main frequency, and up to 3 times the main frequency, which has great market competitiveness. Experimental results show that, compared with the resonator of the traditional ceramic filter, the ceramic filter resonant unit provided by the application has smaller size or lower frequency under the same size; at the same time, the second harmonic of the ceramic filter resonant unit provided by the application is farther, the second harmonic of the traditional resonator is about 1.5 times the main frequency, the application can be made to be more than 2 times the main frequency, and the highest can be made to be more than 3.5 times the main frequency; and the ceramic filter resonant unit provided by the application can adjust the frequency by adjusting the size of each part under the same volume, especially the 2.6G, 3.5G and 6.5G frequency bands of the current 5G mainstream frequency band can be realized; in addition, the Q value of the ceramic filter resonant unit provided by the application is more than 40% higher than that of the existing mainstream scheme.

[0046] The application further provides a preparation method of the ceramic filter resonant unit, comprising the following steps:

[0047] a) dry pressing and forming the material of the A ceramic body, and then performing first sintering to obtain the A ceramic body;

[0048] b) casting the material of the B ceramic body into a green tape, and then sequentially performing lamination, isostatic pressing and second sintering to obtain the B ceramic body;

[0049] c) silk-screening a second conductor layer on the top surface of the B ceramic body, and then assembling the A ceramic body, sequentially performing isostatic pressing and high-temperature curing to form an overall structure, and finally plating a first conductor layer and a third conductor layer on the surface of the overall structure to obtain the ceramic filter resonant unit.

[0050] Firstly, the material of the A ceramic body is dry pressed and formed, and then first sintering is performed to obtain the A ceramic body. In the application, the material of the A ceramic body is the same as in the above technical solution, and will not be repeated here.

[0051] The application does not have special restrictions on the device for dry pressing and forming, and a dry powder presser known to those skilled in the art can be used; the pressure for dry pressing and forming is preferably 60MPa-70MPa.

[0052] In the application, the temperature for first sintering is preferably 1300-1600 DEG C, and the time is preferably 3-5h.

[0053] Then, the material of the B ceramic body is cast into a green tape, and then sequentially performs lamination, isostatic pressing and second sintering to obtain the B ceramic body. In the application, the material of the B ceramic body is the same as in the above technical solution, and will not be repeated here.

[0054] The present application adopts a laminating process technology, wherein the device for casting is not particularly limited in the present application, and a casting machine well known to those skilled in the art can be adopted; the casting process adopts a casting method well known to those skilled in the art, and the material of the B ceramic body is prepared into a casting slurry with a solid content of 78% to 85% by mixing the material of the B ceramic body with alcohol, POM and a dispersing agent, and the viscosity is controlled to be 1.0 to 1.5 pa.s, and then the casting slurry is cast on a casting machine to form a green tape with a thickness.

[0055] In the present application, the thickness of the green tape is preferably 150 to 250 microns.

[0056] In the present application, the pressure for isostatic pressing is preferably 55 to 65 MPa, and the time is preferably 10 to 15 minutes.

[0057] In the present application, the temperature for the second sintering is preferably 1300 to 1600 degrees Celsius, and the time is preferably 3 to 5 hours.

[0058] Finally, the present application assembles the B ceramic body with the A ceramic body after silk printing a second conductor layer on the top surface of the B ceramic body, and then performs isostatic pressing and high-temperature curing to form an overall structure, and finally, a first conductor layer and a third conductor layer are plated on the surface of the overall structure to obtain a ceramic filter resonant unit. In the present application, the materials of the first conductor layer, the second conductor layer and the third conductor layer are the same as in the above technical solution, and will not be described here.

[0059] In the present application, the thickness of the second conductor layer is preferably 6 to 50 microns.

[0060] The present application does not have a special limitation on the assembly method, and the assembly of the A ceramic body and the B ceramic body can be performed according to Figure 1 , and preferably, a high-temperature ceramic adhesive well known to those skilled in the art is used (not provided at the second conductor layer).

[0061] In the present application, the pressure for isostatic pressing is preferably 40 to 50 MPa.

[0062] In the present application, the temperature for high-temperature curing is preferably 600 to 700 degrees Celsius, and the time is preferably 30 to 120 minutes; the present application does not have a special limitation on the device for high-temperature curing, and a high-temperature furnace well known to those skilled in the art can be adopted.

[0063] In the present application, the thickness of the first conductor layer and the third conductor layer is preferably 15 to 25 microns.

[0064] The present application also provides a preparation method of a ceramic filter resonant unit, which has simple process, low equipment requirement, low cost and is easy to implement, and provides convenience for large-scale production.

[0065] The application provides a ceramic filter resonant unit, which comprises an A ceramic body, a blind hole arranged in the center of the A ceramic body, a first conductor layer arranged on the inner side of the blind hole, a B ceramic body in contact with and coinciding with the bottom surface of the A ceramic body, a second conductor layer arranged on the top surface of the B ceramic body and covering the blind hole, the second conductor layer being in communication with the first conductor layer, and a third conductor layer covering the top surface and side surface of the A ceramic body and the bottom surface and side surface of the B ceramic body. Compared with the prior art, the ceramic filter resonant unit provided by the application has the characteristics of small size and high Q value, and the second harmonic is far away from the main frequency, more than 2 times the main frequency, and up to 3 times the main frequency, thus having great market competitiveness.

[0066] In addition, the application further provides a preparation method of the ceramic filter resonant unit, which has simple process, low equipment requirement, low cost and is easy to realize, thus providing convenience for large-scale production.

[0067] In order to further illustrate the application, the following examples are used for detailed description. The structure schematic diagram of the ceramic filter resonant unit in the following examples of the application is shown in the figure, the outer dimension of the ceramic filter resonant unit is 10mm*10mm*5mm (the machining precision is ±0.05mm), and the specific preparation method is as follows. Figure 1

[0068] (1) A mold is prepared according to the size of the resonant unit by using tungsten steel, the material of the A ceramic body is dry-pressed into shape on a dry powder presser, the forming pressure is 65MPa, the formed product is sintered in a sintering furnace, the sintering temperature is 1450℃, and the sintering time is 4h, so that the A ceramic body is obtained;

[0069] (2) the material of the B ceramic body is prepared into a casting slurry with a solid content of 80% and a viscosity of 1.0-1.5pa.s by adding alcohol, POM and a dispersing agent, the green tape with a thickness of 150-250μm is prepared by casting on a casting machine, then the green tape is cut into the required size after lamination and isostatic pressing, the pressure of the isostatic pressing is 60MPa, and the time is 12-13min, finally the cut product is sintered in a sintering furnace, the sintering temperature is 1450℃, and the sintering time is 4h, so that the B ceramic body is obtained;

[0070] (3) the second conductor layer with a thickness of 25-30μm is screen-printed on the top surface of the B ceramic body, then the B ceramic body is assembled with the A ceramic body (by using a ceramic adhesive with a viscosity of 1.0Pa.s and a solid content of more than 85%), and the whole structure is formed by isostatic pressing (the pressure is 45MPa) and high-temperature curing (a high-temperature furnace, 650℃, 70-80min) in sequence, finally the first conductor layer and the third conductor layer (both with a thickness of 15-25μm) are plated on the surface of the whole structure, so that the ceramic filter resonant unit is obtained.​

[0071] The material used for the A ceramic body and the B ceramic body is a microwave dielectric material, which can be a commercially available product or a self-made product known to those skilled in the art and meeting the corresponding defined requirements. For example, a material with a dielectric constant of 20.6 can be prepared according to the preparation method in other patents such as ZL201310720204.8, and a material with a dielectric constant of 12 can be prepared according to the preparation method in other patents such as ZL201410166735.1; the material of the conductor layer is silver.

[0072] Example 1

[0073] The A ceramic body adopts a material with a dielectric constant of 5 and a QF value of 50000 GHz, and the D1 diameter is 2.0 mm. The B ceramic body adopts a material with a dielectric constant of 5 and a QF value of 50000 GHz, and the D2 diameter is 3.0 mm, wherein H1 is 2.0 mm. A ceramic filter resonant unit with a resonant frequency of 3621 GHz, a Q value of 2080, and a second harmonic of 7400 MHz is obtained.

[0074] Example 2

[0075] The A ceramic body adopts a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, and the D1 diameter is 2.0 mm. The B ceramic body adopts a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, and the D2 diameter is 3.0 mm, wherein H1 is 3.0 mm. A ceramic filter resonant unit with a resonant frequency of 2650 GHz, a Q value of 1900, and a second harmonic of 6470 MHz is obtained.

[0076] Example 3

[0077] The A ceramic body adopts a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, and the D1 diameter is 2.0 mm. The B ceramic body adopts a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, and the D2 diameter is 2.6 mm, wherein H1 is 2.0 mm. A ceramic filter resonant unit with a resonant frequency of 3560 GHz, a Q value of 1800, and a second harmonic of 7020 MHz is obtained.

[0078] Example 4

[0079] The A ceramic body adopts a material with a dielectric constant of 5 and a QF value of 50000 GHz, and the D1 diameter is 2.0 mm. The B ceramic body adopts a material with a dielectric constant of 12 and a QF value of 40000 GHz, and the D2 diameter is 3.6 mm, wherein H1 is 3.6 mm. A ceramic filter resonant unit with a resonant frequency of 3580 GHz, a Q value of 2100, and a second harmonic of 11145 MHz is obtained.

[0080] Example 5

[0081] A ceramic body adopts a material with a dielectric constant of 5 and a QF value of 50000 GHz, D1 is 1.0 mm in diameter, B ceramic body adopts a material with a dielectric constant of 20.6 and a QF value of 65000 GHz, D2 is 2.0 mm in diameter, wherein H1 is 2.5 mm, a ceramic filter resonant unit with a resonant frequency of 3600 GHz, a Q value of 2100 and a second harmonic of 8220 MHz is obtained.

[0082] Table 1 Parameter data and effect data table of each embodiment and comparison group

[0083]

[0084] Note: H2 = total thickness - H1.

[0085] As can be seen from Table 1, the ceramic filter resonant unit provided by the present application has smaller size compared with the resonator of the traditional ceramic filter, or in other words, the frequency is lower under the same size; at the same time, the second harmonic of the ceramic filter resonant unit provided by the present application is farther, the second harmonic of the traditional resonator is about 1.5 times the main frequency, the present application can be 2 times the main frequency or even 3.5 times the main frequency; and the ceramic filter resonant unit provided by the present application can adjust the frequency by adjusting the size of each part under the same volume, especially the 2.6G, 3.5G and 6.5G frequency bands of the current 5G mainstream frequency band can be realized; in addition, the Q value of the ceramic filter resonant unit provided by the present application is more than 40% higher than the existing mainstream scheme.

[0086] The above description of disclosed embodiments enables one of ordinary skill in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those of ordinary skill in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ceramic filter resonant unit, comprising: an A ceramic body, a blind hole being provided in the center of the A ceramic body, and a first conductor layer being provided on the inner side of the blind hole; a B ceramic body, the top surface of the B ceramic body being in contact with and coinciding with the bottom surface of the A ceramic body, and a second conductor layer being provided on the top surface of the B ceramic body, the second conductor layer being in communication with the first conductor layer; a third conductor layer covering the top surface and the side surface of the A ceramic body and the bottom surface and the side surface of the B ceramic body; the diameter of the second conductor layer being greater than the diameter of the blind hole.

2. The ceramic filter resonator unit according to claim 1, characterized by The material of the A ceramic body is a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz.

3. The ceramic filter resonator unit according to claim 1, characterized by The material of the B ceramic body is a microwave dielectric material with a dielectric constant of 5-21 and / or a QF value greater than 40000 GHz.

4. The ceramic filter resonator unit of claim 1, wherein, The material of the first conductor layer is selected from one or more of copper, silver and gold.

5. The ceramic filter resonator unit of claim 1, wherein, 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.

6. A preparation method of a ceramic filter resonant unit, comprising the following steps: a) dry pressing the material of the A ceramic body to form a green body, and then performing first sintering to obtain the A ceramic body; b) casting the material of the B ceramic body into a green tape, and then sequentially performing lamination, isostatic pressing and second sintering to obtain the B ceramic body; c) silk-screening the second conductor layer on the top surface of the B ceramic body, and then assembling the B ceramic body with the A ceramic body, sequentially performing isostatic pressing 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 filter resonant unit.

7. The production method according to claim 6, wherein In step a), the pressure of the dry pressing is 60-70 MPa, the temperature of the first sintering is 1300-1600 °C, and the time is 3-5 h.

8. The preparation method according to claim 6, characterized in that, In step b), the thickness of the green tape is 150-250 μm, the pressure of the isostatic pressing is 55-65 MPa, the time is 10-15 min, the temperature of the second sintering is 1300-1600 °C, and the time is 3-5 h.

9. The preparation method according to claim 6, characterized in that, In step c), the thickness of the second conductor layer is 6-50 μm.

10. The method of claim 6, wherein, In step c), the pressure of the isostatic pressing is 40-50 MPa, the temperature of the high-temperature curing is 600-700 °C, and the time is 30-120 min.

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