Dielectric filter with built-in negative coupling structure and manufacturing method thereof

Abstract

The dielectric filter with the built-in negative coupling structure comprises a dielectric block, a conductive layer and the negative coupling structure, at least two resonance holes are formed in the dielectric block, the conductive layer is laid on the surface of the dielectric block and the inner walls of the resonance holes, and the negative coupling structure is arranged between two adjacent resonators divided by the two resonance holes. The negative coupling structure comprises the two conducting strips which are arranged in parallel at an interval and the metalized via hole for connecting the two conducting strips, and the conducting strips and the metalized via hole are embedded in the dielectric block and are not connected with the resonance hole and the conducting layer, so that coupling can be realized in the dielectric block, exposure is not needed, and the strength is not reduced; according to the manufacturing method of the dielectric filter, the defects of deformation, local collapse and the like generated during firing can be avoided, the size of the dielectric filter can be greatly reduced, the requirement for miniaturization is met, the conducting strips and the metalized via holes are arranged in a prefabrication machining mode, the machining precision is high, the zero point position control is accurate, implementation is easy, and the yield is high.

Description

Technical Field

[0001] This invention relates to the field of dielectric filter technology, specifically to a dielectric filter with a built-in negative coupling structure and its fabrication method. Background Technology

[0002] A dielectric filter is a microwave filter that achieves frequency selection by using a dielectric resonator through multi-stage coupling. It is generally composed of several dielectric resonators coupled together. To achieve negative coupling, exposed coupling slots need to be opened between adjacent dielectric resonators on the dielectric block. These slots reduce the strength of the dielectric block itself and are prone to deformation, local collapse and other defects during firing. At the same time, these slots have specific openings on the dielectric block, making it difficult to reduce the size of this type of dielectric filter and failing to meet the increasingly stringent miniaturization requirements. Summary of the Invention

[0003] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide a dielectric filter with a built-in negative coupling structure and a method for manufacturing the same.

[0004] To achieve the above objectives, the product in the technical solution adopted by this invention is a dielectric filter with a built-in negative coupling structure, comprising: A dielectric block, on which at least two resonant holes are formed; A conductive layer is applied to the surface of the dielectric block and the inner wall of the resonant hole. The negative coupling structure is located between two adjacent resonators separated by two resonant holes. The negative coupling structure includes two parallel and spaced conductive plates and metallized vias connecting the two conductive plates. The conductive plates and metallized vias are embedded in the dielectric block and are not connected to the resonant holes or conductive layers.

[0005] Preferably, at least one end of the two conductive sheets is flush with the metallized via connected to that end.

[0006] More preferably, the two ends of the two conductive sheets are flush.

[0007] Preferably, the plane containing the conductive sheet is perpendicular to the axis of the resonant hole.

[0008] Preferably, the metallized via is perpendicularly connected to the conductive sheet.

[0009] Preferably, the dielectric block is formed by stacking and sintering multiple ceramic sheets, wherein two of the ceramic sheets have a solidified metal paste on their surfaces to form the conductive sheet.

[0010] More preferably, each of the ceramic sheets between the two conductive sheets has a through hole, and the inner wall of the through hole is provided with a cured metal paste, and all the through holes are combined to form the metallized via.

[0011] Preferably, there are four resonant holes, which divide the dielectric filter into four resonators.

[0012] To achieve the above objectives, the method employed in this invention is a method for manufacturing the aforementioned dielectric filter, comprising the following steps: S1. Decompose the dielectric block into several parallel ceramic sheets. During decomposition, adjust the thickness of the ceramic sheets so that the conductive sheets are located on the surface of the ceramic sheets. S2. A through hole corresponding to the location of the metallized via is made on the ceramic sheet between the two conductive sheets; S3. Print metal paste on the ceramic sheet at the corresponding positions of the conductive sheet and on the inner wall of the through hole; S4. Sinter all ceramic sheets together to obtain a dielectric block; S5. Metallize the dielectric block to form a conductive layer to obtain a dielectric filter.

[0013] Preferably, the through hole is provided on the ceramic sheet on which the conductive sheet is located.

[0014] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: The dielectric filter with a built-in negative coupling structure provided by this invention includes a dielectric block, a conductive layer, and a negative coupling structure. At least two resonant holes are formed on the dielectric block. The conductive layer is applied to the surface of the dielectric block and the inner wall of the resonant holes. The negative coupling structure is located between two adjacent resonators separated by the two resonant holes. By including two parallel and spaced conductive plates and metallized vias connecting these two conductive plates in the negative coupling structure, the conductive plates and metallized vias are embedded within the dielectric block and not connected to the resonant holes or conductive layer. This allows coupling to be achieved within the dielectric block without exposure, thus maintaining strength and avoiding defects such as deformation and localized collapse during firing. It also significantly reduces the size of the dielectric filter, meeting the requirements for miniaturization. The manufacturing method of the dielectric filter provided by this invention uses prefabrication to set the conductive plates and metallized vias, resulting in high processing precision, accurate zero-point position control, ease of implementation, and high yield. Attached Figure Description

[0015] Figure 1 This is a three-dimensional schematic diagram of Embodiment 1 of the present invention.

[0016] Figure 2 This is a three-dimensional schematic diagram of Embodiment 2 of the present invention.

[0017] Figure 3 yes Figure 2 A three-dimensional schematic diagram before lamination sintering.

[0018] Figure 4 yes Figure 3A schematic diagram of the structure of a ceramic sheet with one of its conductive plates.

[0019] Figure 5 yes Figure 4 A three-dimensional schematic diagram.

[0020] Figure 6 yes Figure 3 A schematic diagram of a ceramic sheet with another conductive sheet in the middle.

[0021] Figure 7 yes Figure 6 A three-dimensional schematic diagram.

[0022] Figure 8 yes Figure 3 A three-dimensional diagram after layering.

[0023] Among them: 10. Dielectric block; 11. Resonant hole; 12. Resonator; 13. Isolation groove; 14. Input / output interface; 15. Ceramic sheet; 16. Through hole; 20. Negative coupling structure; 21. Conductive sheet; 22. Metallized via. Detailed Implementation

[0024] Example 1, as Figure 1 As shown, the dielectric filter with built-in negative coupling structure provided by the present invention includes: a dielectric block 10, a conductive layer, and a negative coupling structure 20. The upper surface of the dielectric block 10 has two resonant holes 11, which are blind holes. The conductive layer is laid on the surface of the dielectric block 10 and the inner wall of the resonant holes 11. The negative coupling structure 20 is disposed between two adjacent resonators 12 divided by the two resonant holes 11. The negative coupling structure 20 includes two parallel and spaced conductive sheets 21 and a metallized via 22 connecting the two conductive sheets 21. The conductive sheets 21 and the metallized via 22 are both embedded in the dielectric block 10 and are not connected to the resonant holes 11 or the conductive layer.

[0025] The advantage of this setup is that it enables coupling within the dielectric block without exposure, thus maintaining strength. It also avoids defects such as deformation and local collapse during firing, and significantly reduces the size of the dielectric filter to meet miniaturization requirements.

[0026] In this embodiment, the plane where the conductive sheet 21 is located is perpendicular to the axis of the resonant hole 11. The two ends of the two conductive sheets 21 are flush. The metallized via 22 is perpendicularly connected to the flush ends of the two conductive sheets 21 to form an inverted U-shaped structure. Furthermore, the projection of the metallized via 22 on the conductive sheet 21 falls on the conductive sheet 21.

[0027] Example 2, as Figure 2As shown, Embodiment 2 is basically the same as Embodiment 1, except that there are four resonant holes 11, which divides the dielectric filter into four resonators 12. A cross-shaped isolation groove 13 is provided between the four resonators 12. The inner wall of the isolation groove 13 is covered with a conductive layer. Input and output interfaces 14 are provided on the back of two resonant holes 11, and the negative coupling structure 20 is not located on the resonators 14 corresponding to these two resonant holes 11.

[0028] like Figures 3 to 8 As shown, in Embodiment 2, the dielectric block 10 is formed by stacking and sintering eight parallel ceramic sheets 15. The surfaces of the fourth and sixth ceramic sheets 15 are covered with cured metal paste to form conductive sheets 21. The conductive sheets 21 are located on the surfaces of the fourth and sixth ceramic sheets 15 facing away from each other. Through holes 16 are formed on the fourth, fifth, and sixth ceramic sheets 15. The inner walls of the through holes 16 are covered with cured metal paste. All the through holes 16 are combined to form metallized vias 22. The structure of the dielectric block 10 in Embodiment 1 is the same as that in Embodiment 2, and will not be described again here.

[0029] The present invention also provides a method for manufacturing the above-mentioned dielectric filter, comprising the following steps: S1. The dielectric block 10 is decomposed into several parallel ceramic sheets 15. During decomposition, the thickness of the ceramic sheets 15 is adjusted so that the conductive sheet 21 is located on the surface of the ceramic sheets 15. That is, the thickness of the ceramic sheets 15 can be the same or different. S2. A through hole 16 corresponding to the position of the metallized via 22 is made on the ceramic sheet 15 between the two conductive sheets 21; S3. Print metal paste on the ceramic sheet 15 at the position corresponding to the conductive sheet 21 and on the inner wall of the through hole 16; S4. Sinter all ceramic sheets 15 in layers to obtain dielectric block 10; S5. Metallize dielectric block 10 to form a conductive layer to obtain a dielectric filter.

[0030] This method sets conductive sheets and metallized vias through prefabrication, which has high processing precision, accurate zero-point position control, is easy to implement, and has a high yield rate.

[0031] Preferably, the ceramic sheet 15 on which the conductive sheet 21 is located has a through hole 16 to improve the connection effect between the metallized via 22 and the conductive sheet 21.

[0032] The embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A dielectric filter with a built-in negative coupling structure, comprising: A dielectric block, on which at least two resonant holes are formed; A conductive layer is applied to the surface of the dielectric block and the inner wall of the resonant hole. A negative coupling structure is placed between two adjacent resonators defined by two resonant holes; Its features are: The negative coupling structure includes two parallel and spaced conductive plates and a metallized via connecting the two conductive plates. The conductive plates and the metallized via are both embedded in the dielectric block and are not connected to the resonant hole or the conductive layer.

2. The dielectric filter according to claim 1, characterized in that: At least one end of the two conductive sheets is flush with the metallized via connected to that end.

3. The dielectric filter according to claim 2, characterized in that: The two ends of the two conductive sheets are flush.

4. The dielectric filter according to claim 1, characterized in that: The plane containing the conductive sheet is perpendicular to the axis of the resonant hole.

5. The dielectric filter according to claim 1, characterized in that: The metallized via is perpendicularly connected to the conductive sheet.

6. The dielectric filter according to claim 1, characterized in that: The dielectric block is formed by stacking and sintering multiple ceramic sheets, wherein two of the ceramic sheets have a solidified metal paste on their surfaces, forming the conductive sheet.

7. The dielectric filter according to claim 6, characterized in that: Through holes are formed on the ceramic sheet between the two conductive sheets, and the inner wall of the through holes is coated with solidified metal paste. All the through holes are combined to form the metallized via.

8. The dielectric filter according to claim 1, characterized in that: The dielectric filter is divided into four resonators by having four resonant holes.

9. A method for manufacturing the dielectric filter according to claims 1 to 8, characterized in that, Includes the following steps: S1. Decompose the dielectric block into several parallel ceramic sheets. During decomposition, adjust the thickness of the ceramic sheets so that the conductive sheets are located on the surface of the ceramic sheets. S2. A through hole corresponding to the position of the metallized via is made on the ceramic sheet between the two conductive sheets; S3. Print metal paste on the ceramic sheet at the corresponding positions of the conductive sheet and on the inner wall of the through hole; S4. Sinter all ceramic sheets together to obtain a dielectric block; S5. Metallize the dielectric block to form a conductive layer to obtain a dielectric filter.

10. The manufacturing method according to claim 9, characterized in that: The through hole is provided on the ceramic sheet on which the conductive sheet is located.

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