A ceramic dielectric filter

Abstract

The invention discloses a ceramic dielectric filter, comprising a filter body and a PCB board; an input end and an output end for connecting a signal input and output device are arranged on a signal transmission surface of the filter body; the PCB board is used for welding the signal transmission surface and a communication system board and then grounding; the PCB board and the input end and the output end are staggered; the PCB board comprises at least two sub-boards, the sub-boards are spaced apart from each other, so that stresses on the sub-boards cannot be transmitted to each other; compared with an existing ceramic dielectric filter connected to a whole PCB board structure, the stress on the PCB board used in the invention is greatly reduced, thereby effectively reducing the probability of ceramic cracking, solder joint cracking, and copper foil falling off on the PCB board of the dielectric filter.

Description

Technical Field

[0001] The present invention relates to the technical field of communication equipment, and in particular to a ceramic dielectric filter. Background Art

[0002] like Figure 1 As shown, the existing ceramic dielectric filter includes a filter body 1 and a PCB board 2; the signal transmission surface 13 of the filter body is provided with an input terminal 11 and an output terminal 12 for connecting a signal input and output device; the PCB board is used for welding the signal transmission surface and the communication system board and then grounding, and the PCB board is staggered with the input terminal and the output terminal. Among them, the welding of the filter body and the PCB board is usually achieved by tin. However, when the PCB board welded to the filter body is an integral structure, under high and low temperature conditions, the PCB board of the integral structure is deformed. Because the existence of the solder joint limits the deformation of the PCB board of the integral structure, the PCB board of the integral structure is subjected to great stress, resulting in the occurrence of ceramic cracking of the dielectric filter, cracking of the solder joint, and the shedding of the copper foil on the PCB board. The product is easily degraded or loses performance at once, which greatly shortens the service life of the product.

[0003] At temperature differences of 190°C, 125°C, and 65°C, the stresses on the existing overall structure PCB are shown in the following table:

[0004] Temperature range (°C) Temperature difference (°C) Stress (N) -40～150 190 1932 25～150 125 1080 -40～25 65 495 Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a ceramic dielectric filter, which can help reduce the stress on a PCB board.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is specifically as follows:

[0007] A ceramic dielectric filter comprises a filter body and a PCB board; an input terminal and an output terminal for connecting a signal input and output device are arranged on a signal transmission surface of the filter body; the PCB board is used for welding the signal transmission surface and a communication system board and then grounding, the PCB board is staggered with the input terminal and the output terminal, and the PCB board comprises at least two sub-boards, and the sub-boards are arranged spaced apart from each other.

[0008] Furthermore, the PCB board includes a first metal layer, a second metal layer, and a dielectric layer located between the first metal layer and the second metal layer; the first metal layer is used for welding the signal transmission surface, and the second metal layer is used for welding the communication system board.

[0009] Preferably, a metal via hole for conducting the first metal layer and the second metal layer is provided on the PCB board.

[0010] Further, a first notch and a second notch are provided on the first daughter board; the input end and the output end are respectively located in the first notch and the second notch.

[0011] Preferably, the first notch and the second notch are respectively in an arc structure.

[0012] More preferably, the arc structure is a major arc structure.

[0013] Alternatively, a first through hole corresponding to the input end and a second through hole corresponding to the output end are provided on the first daughter board; the input end and the output end are respectively located in the first through hole and the second through hole.

[0014] Preferably, a first impedance adjustment area corresponding to the input end and a second impedance adjustment area corresponding to the output end are further provided on the first daughter board; the first through hole is located in the first impedance adjustment area and forms a first annular impedance adjustment band with the first impedance adjustment area, the second through hole is located in the second impedance adjustment area and forms a second annular impedance adjustment band with the second impedance adjustment area; the input end includes an input metal covering area and a ceramic input dielectric area provided on the filter body; the input metal covering area is located in the ceramic input dielectric area and forms an annular input dielectric band with the ceramic input dielectric area; the input metal covering area faces the first through hole, and the outer diameter of the input metal covering area matches the outer diameter of the first through hole; the bandwidth of the first annular impedance adjustment band matches the bandwidth of the annular input dielectric band; the output end includes an output metal covering area and a ceramic output dielectric area provided on the filter body; the output metal covering area is located in the ceramic output dielectric area and forms an annular output dielectric band with the ceramic output dielectric area; the output metal covering area faces the second through hole, and the outer diameter of the output metal covering area matches the outer diameter of the second through hole; the bandwidth of the second annular impedance adjustment band matches the bandwidth of the annular output dielectric band.

[0015] More preferably, the first impedance adjustment area is formed by etching the first metal layer area at the position corresponding to the input end on the first daughter board to expose the corresponding dielectric layer; the second impedance adjustment area is formed by etching the first metal layer area at the position corresponding to the output end on the first daughter board to expose the corresponding dielectric layer.

[0016] More preferably, both the first through hole and the second through hole are circular through holes, and both the input metal covering area and the output metal covering area are circular.

[0017] More preferably, both the first annular impedance adjustment strip and the annular input dielectric strip are circular, and both the second annular impedance adjustment strip and the annular output dielectric strip are circular.

[0018] Furthermore, the number of the daughter boards is two, three or four.

[0019] Furthermore, the PCB board is grounded after connecting the signal transmission surface and the communication system board through solder joints.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. For the ceramic dielectric filter of the present invention, since the number of daughter boards of the PCB board is more than two, and the daughter boards are arranged separately from each other and do not contact each other adjacent to each other, the restrictions on the deformation of the daughter boards caused by the solder joints on different daughter boards cannot be transmitted to each other, so that the stress effects received between the daughter boards cannot be transmitted to each other; moreover, since the daughter boards are arranged separately from each other, the boundary of each daughter board is free, so that the stress effect received by each daughter board can be completely released, and after measurement, the stress value approaches 0. Compared with the existing ceramic dielectric filter with a structure of connecting a whole PCB board, the overall stress received by the PCB board with more than two daughter boards used in the present invention is greatly reduced, effectively reducing the probability of ceramic cracking, solder joint cracking, and copper foil peeling on the PCB board. At the same time, when the PCB board is divided into smaller daughter board structures, the overall material consumption of the PCB board is reduced, thereby improving the material utilization rate and effectively reducing the cost.

[0022] 2. The PCB board is provided with metal vias for conducting the first metal layer and the second metal layer. Through the metal vias, the filter body and the communication system board can be grounded together, which helps to improve the overall grounding performance of the ceramic dielectric filter of the present invention.

[0023] 3. A first notch corresponding to the input end and a second notch corresponding to the output end are provided on the first daughter board; the input end and the output end are respectively located in the first notch and the second notch, and the first notch and the second notch are respectively in an arc structure, and the arc structure is a major arc structure, so that the wire can be better fixed when connecting the wire to the input end and the output end, preventing the wire from shifting, and ensuring the electrical connection performance of the ceramic dielectric filter of the present invention.

[0024] 4. The present invention is provided with a first through hole corresponding to the input end and a second through hole corresponding to the output end on the first sub-board, which can facilitate the connection of the input end and the output end of the filter body to the wires through the first through hole and the second through hole, ensuring the electrical performance of the ceramic dielectric filter of the present invention. The first through hole and the first impedance adjustment area are used to form a first annular impedance adjustment band, and the second through hole and the second impedance adjustment area are used to form a second annular impedance adjustment band. The bandwidths of the two respectively correspond to and match the bandwidths of the annular input dielectric band and the annular output dielectric band on the filter body, so as to form a capacitance between the first annular impedance adjustment band and the annular input dielectric band, and between the second annular impedance adjustment band and the annular output dielectric band; by adjusting the bandwidths of the first annular impedance adjustment band and the annular input dielectric band, the impedance between the first sub-board and the input end of the filter body is changed, and by adjusting the bandwidths of the second annular impedance adjustment band and the annular output dielectric band, the impedance between the first sub-board and the output end of the filter body is changed.

[0025] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given and described in detail in conjunction with the drawings as follows. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of an existing ceramic dielectric filter.

[0027] Figure 2 It is a schematic structural diagram of the first embodiment of the ceramic dielectric filter of the present invention.

[0028] Figure 3 It is a schematic structural diagram of the second embodiment of the ceramic dielectric filter of the present invention.

[0029] Figure 4 It is a schematic structural diagram of the third embodiment of the ceramic dielectric filter of the present invention.

[0030] Figure 5 It is a schematic structural diagram of the fifth embodiment of the ceramic dielectric filter of the present invention.

[0031] Figure 6 For Figure 5 the filter body of

[0032] Among them, each reference numeral is:

[0033] 1. Filter body; 11. Input end; 111. Input metal covering area; 112. Annular input dielectric strip; 12. Output end; 121. Output metal covering area; 122. Annular output dielectric strip; 13. Signal transmission surface; 2. PCB board; 21. First sub-board; 211. First notch; 212. Second notch; 22. Second sub-board; 23. Third sub-board; 24. Fourth sub-board; 25. Metal via; 31. First through hole; 32. Second through hole; 41. First annular impedance adjustment strip; 42. Second annular impedance adjustment strip. DETAILED DESCRIPTION

[0034] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments:

[0035] Embodiment 1

[0036] Figure 2 This is a first specific implementation of the ceramic dielectric filter of the present invention, which includes a filter body 1 and a PCB board 2; the signal transmission surface 13 of the filter body is provided with an input terminal 11 and an output terminal 12 for connecting a signal input and output device; the PCB board is used for welding the signal transmission surface and a communication system board (not shown) and then grounding, the PCB board is staggered with the input terminal and the output terminal, and the PCB board 2 includes two sub-boards, and the sub-boards are spaced apart from each other.

[0037] The ceramic dielectric filter of the present invention has more than two sub-boards on its PCB board, and the sub-boards are arranged separately from each other, so that the restrictions on the deformation of the sub-boards caused by the soldering points on different sub-boards cannot be transmitted to each other, so that the stresses on the sub-boards cannot be transmitted to each other; and because the sub-boards are arranged separately from each other, the boundaries of each sub-board are free, so that the stress on each sub-board can be completely released, and the stress value is close to 0 after measurement. Compared with the existing ceramic dielectric filter connected to a whole PCB board structure, the PCB board with more than two sub-boards used in the present invention has a greatly reduced overall stress, which effectively reduces the probability of ceramic cracking, soldering point tearing, and copper foil falling off on the PCB board of the dielectric filter. At the same time, when the PCB board is divided into smaller sub-board structures, the overall material consumption of the PCB board is reduced, thereby improving the material utilization rate and effectively reducing the cost.

[0038] Specifically, the PCB board is connected to the signal transmission surface and the communication system board through solder joints and then grounded.

[0039] Specifically, the PCB board includes a first metal layer, a second metal layer, and a dielectric layer located between the first metal layer and the second metal layer; the first metal layer is used for soldering the signal transmission surface, and the second metal layer is used for soldering the communication system board. A metal via hole 25 for conducting the first metal layer and the second metal layer is provided on the PCB board, which can make the filter body and the communication system board share the same ground, contributing to improving the overall grounding performance of the ceramic dielectric filter of the present invention. Moreover, due to the presence of the metal via hole, the stress on the PCB board when connected to the filter body can be further reduced as well.

[0040] To facilitate the connection of the input end and the output end to the signal input and output device through wires, a first notch 211 corresponding to the input end and a second notch 212 corresponding to the output end are provided on the first sub-board 21; the input end and the output end are respectively located in the first notch and the second notch. Specifically, the input end and the output end are respectively connected to wires through the first notch and the second notch and lead the wires to the signal input and output device.

[0041] As a further improvement of this embodiment, the first notch and the second notch are respectively in an arc-shaped structure, so as to better match the shapes of the input end and the output end. More preferably, the arc-shaped structure is a major arc-shaped structure, so that the wires can be better fixed when the input end and the output end are connected to the wires, preventing the wires from shifting, and ensuring the electrical connection performance of the ceramic dielectric filter of the present invention.

[0042] The second sub-board 22 is in a strip structure in this embodiment, and of course, it can also be in other shapes. The user can set the specific shape of the sub-board according to actual usage needs.

[0043] Embodiment Two

[0044] Figure 3 This is the second specific embodiment of the ceramic dielectric filter of the present invention, and its difference from the first specific embodiment shown in Figure 2 is that: the PCB board 2 has 3 sub-boards. And the structure of the first sub-board 21 of it is the same as that of the first sub-board 21 in the first specific embodiment. The second sub-board 22 and the third sub-board 23 are in a square structure in this embodiment. Compared with the first specific embodiment shown in Figure 2 , due to the adoption of 3 sub-boards in the PCB board of the ceramic dielectric filter in this embodiment, and the centers of the 3 sub-boards are connected to form a triangle, the installation stability of the filter body on the communication system board is improved.

[0045] Embodiment Three

[0046] Figure 4This is the third specific implementation of the ceramic dielectric filter in this embodiment, which is different from Figure 2 the first specific implementation shown in that: the PCB board has 4 sub-boards. And the structure of its first sub-board 21 is the same as that of the first sub-board 21 in the first specific implementation. The second sub-board 22, the third sub-board 23, and the fourth sub-board 24 are square structures in this embodiment. And, the centers of the first sub-board, the second sub-board, and the third sub-board are connected to form a triangle, and the center of the fourth sub-board is located on the center line connecting the centers of the second sub-board and the third sub-board. Therefore, compared with the first and second specific implementations above.

[0047] Embodiment 4

[0048] Figure 5 and Figure 6 is the fourth specific implementation of the ceramic dielectric filter of the present invention, which is different from the first specific implementation in that:

[0049] On the first sub-board, there are provided a first through hole 31 corresponding to the input end and a first impedance adjustment area, and a second through hole 32 corresponding to the output end and a second impedance adjustment area; the first through hole is located in the first impedance adjustment area and forms a first annular impedance adjustment band 41 with the first impedance adjustment area, the second through hole is located in the second impedance adjustment area and forms a second annular impedance adjustment band 42 with the second impedance adjustment area; the input end includes an input metal covering area 111 and a ceramic input dielectric area provided on the filter body; the input metal covering area is located in the ceramic input dielectric area and forms an annular input dielectric band 112 with the ceramic input dielectric area; the input metal covering area faces the first through hole, and the outer diameter of the input metal covering area matches the outer diameter of the first through hole; the bandwidth of the first annular impedance adjustment band matches the bandwidth of the annular input dielectric band; the output end includes an output metal covering area 121 and a ceramic output dielectric area provided on the filter body; the output metal covering area is located in the ceramic output dielectric area and forms an annular output dielectric band 122 with the ceramic output dielectric area; the output metal covering area faces the second through hole, and the outer diameter of the output metal covering area matches the outer diameter of the second through hole; the bandwidth of the second annular impedance adjustment band matches the bandwidth of the annular output dielectric band.

[0050] In the present invention, a first annular impedance adjustment band is formed on the first daughter board by using a first through hole and a first impedance adjustment region, and a second annular impedance adjustment band is formed by using a second through hole and a second impedance adjustment region. The bandwidths of the two respectively correspond to the bandwidths of the annular input dielectric band and the annular output dielectric band on the matching filter body, so as to form a capacitance between the first annular impedance adjustment band and the annular input dielectric band, and between the second annular impedance adjustment band and the annular output dielectric band; by adjusting the bandwidths of the first annular impedance adjustment band and the annular input dielectric band, the impedance between the first daughter board and the input end of the filter body is changed, and by adjusting the bandwidths of the second annular impedance adjustment band and the annular output dielectric band, the impedance between the first daughter board and the output end of the filter body is changed.

[0051] The specific impedance change principle is as follows:

[0052] The impedance formula between the first daughter board and the input end of the filter body, or the impedance formula between the first daughter board and the output end of the filter body is as follows:

[0053]

[0054] The common simplified form is as follows:

[0055]

[0056] Among them, ε0 is the vacuum permittivity, with a value of 8.854187817×10 -12 F / m, ε γ is the relative permittivity of dry air without carbon dioxide under standard atmospheric pressure, and the value is 1.00053.

[0057] For the impedance between the first daughter board and the input end of the filter body, d refers to the outer diameter of the input metal covering area or the outer diameter of the first through hole, and D refers to the outer diameter of the first impedance adjustment region or the ceramic input dielectric region, and D - d refers to the bandwidth of the first annular impedance adjustment band or the bandwidth of the annular input dielectric band. When d takes a fixed value, that is, when the outer diameter of the input metal covering area and the outer diameter of the first through hole are the same constant, by changing the size of D, the change in the outer diameter of the first impedance adjustment region is synchronized with the change in the outer diameter of the ceramic input dielectric region (that is, the values of the bandwidths of the first annular impedance adjustment band and the annular input dielectric band are changed synchronously), so that the impedance between the first daughter board and the input end of the filter body changes.

[0058] Alternatively, when D is fixed, that is, when the outer diameters of the first impedance adjustment region and the ceramic input dielectric region are the same constant, by changing the size of d, the change in the outer diameter of the first impedance adjustment region is synchronized with the change in the outer diameter of the ceramic input dielectric region (i.e., synchronously changing the bandwidths of the first annular impedance adjustment band and the annular input dielectric band), so that the impedance between the first daughter board and the input end of the filter body changes.

[0059] Similarly, for the impedance between the first daughter board and the output end of the filter body, d refers to the outer diameter of the output metal covering region or the outer diameter of the second through hole, and D refers to the outer diameter of the second impedance adjustment region or the ceramic output dielectric region, and D - d refers to the bandwidth of the second annular impedance adjustment band or the bandwidth of the annular output dielectric band. When d is fixed, that is, when the outer diameters of the output metal covering region and the second through hole are the same constant, by changing the size of D, the change in the outer diameter of the second impedance adjustment region is synchronized with the change in the outer diameter of the ceramic output dielectric region (i.e., synchronously changing the bandwidths of the second annular impedance adjustment band and the annular output dielectric band), so that the impedance between the first daughter board and the output end of the filter body changes.

[0060] Alternatively, when D is fixed, that is, when the outer diameters of the second impedance adjustment region and the ceramic output dielectric region are the same constant, by changing the size of d, the change in the outer diameter of the second impedance adjustment region is synchronized with the change in the outer diameter of the ceramic output dielectric region (i.e., synchronously changing the bandwidths of the second annular impedance adjustment band and the annular output dielectric band), so that the impedance between the first daughter board and the output end of the filter body changes.

[0061] Specifically, the first impedance adjustment region is formed by etching the first metal layer region corresponding to the input end position on the first daughter board to expose the corresponding dielectric layer; the second impedance adjustment region is formed by etching the first metal layer region corresponding to the output end position on the first daughter board to expose the corresponding dielectric layer.

[0062] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A ceramic dielectric filter, comprising a filter body and a PCB board; the signal transmission surface of the filter body is provided with an input terminal and an output terminal for connecting a signal input and output device; the PCB board is used for welding the signal transmission surface and a communication system board and then grounding, the PCB board is staggered with the input terminal and the output terminal, and is characterized in that: The PCB board includes at least two sub-boards, which are arranged separately from each other; The PCB board includes a first metal layer, a second metal layer, and a dielectric layer located between the first metal layer and the second metal layer; the first metal layer is used for soldering the signal transmission surface, and the second metal layer is used for soldering the communication system board; Metal vias for conducting the first metal layer and the second metal layer are provided on the PCB board; On the first sub-board, a first via corresponding to the input end and a second via corresponding to the output end are provided; the input end and the output end are respectively located in the first via and the second via; On the first sub-board, a first impedance adjustment area corresponding to the input end and a second impedance adjustment area corresponding to the output end are also provided; the first via is located in the first impedance adjustment area and forms a first annular impedance adjustment band with the first impedance adjustment area, and the second via is located in the second impedance adjustment area and forms a second annular impedance adjustment band with the second impedance adjustment area; the input end includes an input metal covering area and a ceramic input dielectric area provided on the filter body; the input metal covering area is located in the ceramic input dielectric area and forms an annular input dielectric band with the ceramic input dielectric area; the input metal covering area faces the first via, and the outer diameter of the input metal covering area matches the outer diameter of the first via; the bandwidth of the first annular impedance adjustment band matches the bandwidth of the annular input dielectric band; the output end includes an output metal covering area and a ceramic output dielectric area provided on the filter body; the output metal covering area is located in the ceramic output dielectric area and forms an annular output dielectric band with the ceramic output dielectric area; the output metal covering area faces the second via, and the outer diameter of the output metal covering area matches the outer diameter of the second via; the bandwidth of the second annular impedance adjustment band matches the bandwidth of the annular output dielectric band.

2. The ceramic dielectric filter according to claim 1, wherein: Both the first metal layer and the second metal layer are copper foils.

3. The ceramic dielectric filter according to claim 1, characterized in that: The first impedance adjustment area is formed by etching the first metal layer area at the position corresponding to the input end on the first sub-board to expose the corresponding dielectric layer; the second impedance adjustment area is formed by etching the first metal layer area at the position corresponding to the output end on the first sub-board to expose the corresponding dielectric layer.

4. The ceramic dielectric filter according to claim 1, wherein: Both the first via and the second via are circular vias, and both the input metal covering area and the output metal covering area are circular.

5. The ceramic dielectric filter according to claim 4, wherein: Both the first annular impedance adjustment band and the annular input dielectric band are circular rings, and both the second annular impedance adjustment band and the annular output dielectric band are circular rings.

6. The ceramic dielectric filter according to any one of claims 1-5, characterized in that: The number of sub-boards is 2 or 3 or 4.

7. The ceramic dielectric filter according to any one of claims 1-5, characterized in that : After the PCB board connects the signal transmission surface and the communication system board through solder joints, it is grounded.

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