Filter and Its Manufacturing Method

Abstract

The filter provided by the present invention includes a first resonator, a second resonator, an adhesive layer, and a conductive layer. By fitting the first and second resonators together, the adhesive layer is located between the fitting surfaces of the two and bonds them. A first coupling groove is formed on the fitting surface of the first resonator, and a second coupling groove with a notch aligned with the first coupling groove is formed on the fitting surface of the second resonator. The conductive layer covers the surfaces of the first and second resonators except the fitting surfaces and the sidewall surfaces around the adhesive layer. Capacitive coupling of the filter can be achieved through the combined action of the first and second coupling grooves. The coupling grooves have a shallow depth and a large opening, and the shape and size after sintering are precise. The electrical performance of the filter is stable. Even if slight deformation occurs, it can be corrected by grinding, reducing the scrap rate and lowering the production cost. The present invention also provides a method for manufacturing the above filter. The method has a simple process, is easy to implement, and is suitable for mass production.

Description

Technical Field

[0001] This application relates to the field of electronic communication devices, and particularly to a filter and a manufacturing method thereof. Background Art

[0002] With the advent of the "big bang" era of 5G communication, electronic communication devices have gradually become popular worldwide. Filters are an important part of electronic communication devices and determine key factors such as the radiation range and signal strength of electronic base stations.

[0003] Traditional filters have defects such as large volume, high loss, and low dielectric constant, and cannot meet the requirements of 5G communication. Therefore, waveguide filters have emerged. At the same resonant frequency, the dielectric constant of the material is higher and the volume is smaller. As the performance of base stations continues to improve, the performance requirements for filters are also getting higher and higher. Traditional waveguide filters mostly use inductive coupling methods and are difficult to meet specific electrical performance requirements such as the suppression of the proximal end of the filter frequency band. To solve this problem, filters using capacitive coupling have emerged in the market. For example, international patent application WO 2018148905 A1 discloses a filter that realizes capacitive coupling between resonant cavities by setting through holes and conductive isolation layers on a block. However, this solution requires additional conductive isolation layers, with complex processes, additional equipment needed, high costs, and, in this solution, the depth of the through holes is relatively large, and shrinkage or collapse easily occurs during the high-temperature sintering of ceramic materials, resulting in large changes in the shape and accuracy of the through holes, affecting the electrical performance of the dielectric filter. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a filter and a manufacturing method thereof with stable electrical performance, low cost, and capable of convenient mass production.

[0005] To achieve the above object, the product in the technical solution adopted by the present invention is a filter, including a first resonator, a second resonator, and a conductive layer. The first resonator is in contact with the second resonator. The contact surface of the first resonator is the first contact surface, and the contact surface of the second resonator is the second contact surface. A first coupling groove is formed on the first contact surface, and a second coupling groove is formed on the second contact surface. The notch of the first coupling groove is aligned with the notch of the second coupling groove.

[0006] The filter further includes an adhesive layer, which is located between the first contact surface and the second contact surface and is used to bond the first resonator and the second resonator together.

[0007] The conductive layer covers the surfaces of the first resonator except for the first bonding surface, the surfaces of the second resonator except for the second bonding surface, and the side wall surfaces around the adhesive layer;

[0008] The first coupling groove and the second coupling groove act together to achieve capacitive coupling between the first resonator and the second resonator.

[0009] Preferably, the adhesive layer also covers the inner wall of the first coupling groove and is located between the conductive layer and the inner wall of the first coupling groove; the adhesive layer also covers the inner wall of the second coupling groove and is located between the conductive layer and the inner wall of the second coupling groove.

[0010] Preferably, the adhesive layer is sintered from a composite adhesive, and the composite adhesive includes silica powder, barium oxide powder, and an adhesive.

[0011] More preferably, the sintering temperature of the composite adhesive is 800 - 950 °C.

[0012] Preferably, the material of the conductive layer is silver, and the thickness of the conductive layer is 8 - 12 μm.

[0013] To achieve the above object, the method in the technical solution adopted by the present invention is the manufacturing method of the above filter, including the following steps:

[0014] a. Dry-press ceramic powder into the green bodies of the first resonator and the second resonator;

[0015] b. Sinter the green bodies of the first resonator and the second resonator into the first resonator and the second resonator;

[0016] c. Clean the first bonding surface of the first resonator and the second bonding surface of the second resonator, and apply the composite adhesive on the first bonding surface and / or the second bonding surface;

[0017] d. Fit the first resonator and the second resonator together, and bond the first resonator and the second resonator through the composite adhesive;

[0018] e. Sinter the bonded first resonator and second resonator, sinter the composite adhesive into the adhesive layer, and obtain the semi-finished product of the filter;

[0019] f. Coat a metal layer on the surface of the semi-finished product to make the filter.

[0020] Preferably, the composite adhesive in step c is also applied on the inner wall surfaces of the first coupling groove and the second coupling groove.

[0021] Preferably, the composite adhesive in step c is prepared by mixing an adhesive in silica powder and barium oxide powder.

[0022] Preferably, the sintering temperature in step e is less than or equal to the sintering temperature in step b.

[0023] Preferably, the material of the metal layer is silver, and the thickness of the metal layer is 8 - 12 μm.

[0024] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0025] The filter provided by the present invention includes a first resonator, a second resonator, an adhesive layer, and a conductive layer. By making the first resonator and the second resonator fit together, the adhesive layer is located between the fitting surfaces of the first resonator and the second resonator and bonds the first resonator and the second resonator. A first coupling groove is formed on the fitting surface of the first resonator, and a second coupling groove is formed on the fitting surface of the second resonator. The notch of the second coupling groove is aligned with the notch of the first coupling groove. The conductive layer covers the surface of the first resonator except the fitting surface, the surface of the second resonator except the fitting surface, and the side wall surface around the adhesive layer. Capacitive coupling between the first resonator and the second resonator can be achieved through the combined action of the first coupling groove and the second coupling groove; the first coupling groove and the second coupling groove have a shallow depth and a large opening, and the shape and size after sintering are precise, making the electrical performance of the filter stable. Even if the first coupling groove and / or the second coupling groove are slightly deformed after sintering, they can be corrected by grinding, reducing the rejection rate and thus reducing the production cost; the present invention also provides a method for manufacturing the above filter. This method has a simple process, is easy to implement, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a top view schematic diagram of a preferred embodiment of the present invention.

[0027] Figure 2 is Figure 1 a cross-sectional schematic diagram taken along the A - A direction in

[0028] Figure 3 is Figure 1 a cross-sectional schematic diagram taken along the B - B direction in

[0029] Figure 4 is Figure 1 a three-dimensional schematic diagram of the first resonator and the second resonator in

[0030] Figure 5 is a process flow chart of the manufacturing method in the present invention.

[0031] Wherein: 10. filter; 20. first resonator; 201. first debugging hole; 202. first bonding surface; 30. second resonator; 301. second debugging hole; 302. second bonding surface; 41. first coupling slot; 42. second coupling slot; 50. adhesive layer; 60. conductive layer. DETAILED DESCRIPTION

[0032] The following is a detailed description of the technical solutions in the embodiments of the present invention, with reference to the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the attached Figure 1 The orientations or positional relationships shown are for ease of description and simplification of the present invention only. They are not intended to indicate or imply that the devices or components shown must have, be constructed, or operate in a specific orientation, and are not to be construed as limitations of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0035] like Figures 1-4As shown in the figure, the filter 10 provided by the present invention includes: a first resonator 20, a second resonator 30, an adhesive layer 40, and a conductive layer 50. Among them, the first resonator 20 is made of ceramic material. A first debugging hole 201 extending downward is provided on the upper surface of the first resonator 20. The first debugging hole 201 is a blind hole, and the first debugging hole 201 is used to debug the resonance frequency of the first resonator 20. There are two first debugging holes 201; the second resonator 30 is made of ceramic material. A second debugging hole 301 extending downward is provided on the upper surface of the second resonator 30. The second debugging hole 301 is a blind hole, and the second debugging hole 301 is used to debug the resonance frequency of the second resonator 30; the first resonator 20 and the second resonator 30 are fitted together. The fitting surface of the first resonator 20 is the first fitting surface 202, and the fitting surface of the second resonator 30 is the second fitting surface 302. It can be imagined that the fitting direction of the first resonator 20 and the second resonator 30 does not affect the implementation effect of the present invention. This fitting direction can be parallel to the horizontal plane, perpendicular to the horizontal plane, or at a certain angle with the horizontal plane. In this embodiment, the first resonator 20 and the second resonator 30 are fitted left and right in the horizontal direction, and the first fitting surface 202 and the second fitting surface 302 are perpendicular to the horizontal plane; a first coupling groove 41 is provided on the first fitting surface 202, and a second coupling groove 42 is provided on the second fitting surface 302. The notch of the first coupling groove 41 on the first fitting surface 202 is aligned with the notch of the second coupling groove 42 on the second fitting surface 302. It can be imagined that whether the first coupling groove 41 and the second coupling groove 42 penetrate the surface of the above-mentioned resonator does not affect the implementation effect of the present invention. In this embodiment, the first coupling groove 41 extends in the up and down direction and penetrates the upper and lower surfaces of the first resonator 20, and the second coupling groove 42 extends in the up and down direction and penetrates the upper and lower surfaces of the second resonator 30; the adhesive layer 50 is located between the first fitting surface 202 and the second fitting surface 302, and the adhesive layer 50 is used to bond the first resonator 20 and the second resonator 30 together; the conductive layer 60 covers the surface of the first resonator 20 except the first fitting surface 202, the surface of the second resonator 30 except the second fitting surface 302, and the side wall surface around the adhesive layer 50. The reason why the conductive layer 60 covers the surface of the first resonator 20 except the first fitting surface 202 is that the adhesive layer 50 covers the first fitting surface 202, blocking the entry of metal particles used to form the conductive layer 60. Similarly, the reason why the conductive layer 60 covers the surface of the second resonator 30 except the second fitting surface 302 is that the adhesive layer 50 covers the second fitting surface 302, blocking the entry of metal particles used to form the conductive layer 60; the first coupling groove 41 and the second coupling groove 42 jointly act to achieve capacitive coupling between the first resonator 20 and the second resonator 30. That is, the first coupling groove 41 and the second coupling groove 42 jointly act to achieve capacitive coupling of the filter 10.

[0036] In this embodiment, the bonding layer 50 is sintered from a composite adhesive, and the composite adhesive is composed of silica powder, barium oxide powder and an adhesive. The sintering temperature of the composite adhesive is 800 - 950 °C; the conductive layer 60 is made of silver, and the thickness of the conductive layer 60 is 8 - 12 μm. The reason for setting the thickness of the conductive layer 60 at 8 - 12 μm is to minimize the amount of silver material used while ensuring that the first coupling groove 41 and the second coupling groove 42 work together to achieve capacitive coupling of the filter 10, thereby reducing costs.

[0037] It can be conceived that covering the inner wall of the first coupling groove 41 with the bonding layer 50 and positioning it between the conductive layer 60 and the inner wall of the first coupling groove 41, and covering the inner wall of the second coupling groove 42 with the bonding layer 50 and positioning it between the conductive layer 60 and the inner wall of the second coupling groove 42 will not affect the implementation effect of the present invention.

[0038] The filter provided by the invention realizes capacitive coupling between the first resonator and the second resonator through the combined action of the first coupling groove and the second coupling groove, avoiding the method of opening long through - holes or deep blind - holes. Due to the shallow depth and large opening of the first coupling groove and the second coupling groove, the sintered shape and size are precise, making the electrical performance of the filter stable. Even if the first coupling groove and / or the second coupling groove generate slight deformation after sintering, it can be corrected by grinding, reducing the rejection rate and thus reducing the production cost.

[0039] The present invention also provides a manufacturing method for the above - mentioned filter, as Figure 5 shown, including the following steps:

[0040] a. Dry - press the ceramic powder into the green bodies of the first resonator and the second resonator;

[0041] b. Sinter the green bodies of the first resonator and the second resonator into the first resonator and the second resonator;

[0042] c. Clean the first bonding surface of the first resonator and the second bonding surface of the second resonator, and coat the composite adhesive on the first bonding surface and / or the second bonding surface;

[0043] d. Bond the first resonator and the second resonator together, and bond the first resonator and the second resonator through the composite adhesive;

[0044] e. Sinter the bonded first resonator and second resonator, sinter the composite adhesive into the bonding layer, and obtain the semi - finished product of the filter;

[0045] f. Coat a metal layer on the surface of the semi-finished product to fabricate the filter.

[0046] Preferably, the composite adhesive in step c is also coated on the inner wall surfaces of the first coupling groove and the second coupling groove. The advantage of such a setting is that it can facilitate the coating operation of the composite adhesive without the need for skip coating at the first coupling groove and the second coupling groove.

[0047] Preferably, the composite adhesive in step c is prepared by mixing an adhesive in silicon oxide powder and barium oxide powder.

[0048] Preferably, the sintering temperature in step e is less than or equal to the sintering temperature in step b. Further preferably, the sintering temperature in step e is 800 - 950 °C. Of course, in order to save the energy consumption of the sintering furnace, steps b and e are preferably sintered without changing the temperature of the sintering furnace as much as possible. The sintering temperature in step e is preferably close to that in step b. Therefore, in this embodiment, the sintering temperature in step e is 800 - 890 °C.

[0049] Preferably, the material of the metal layer is silver and the thickness of the metal layer is 8 - 12 μm.

[0050] This method has a simple process, is easy to implement, and is suitable for mass production.

[0051] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0052] The above are only specific embodiments of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A filter comprising a first resonator, a second resonator, a conductive layer, and an adhesive layer. The first resonator and the second resonator are horizontally bonded to each other. The bonding surface of the first resonator is a first bonding surface perpendicular to the horizontal plane, and the bonding surface of the second resonator is a second bonding surface perpendicular to the horizontal plane. The first bonding surface is provided with a first coupling slot, and the second bonding surface is provided with a second coupling slot whose slot is aligned with the slot of the first coupling slot. The adhesive layer is located between the first bonding surface and the second bonding surface for bonding the first and second resonators. The conductive layer covers the surface of the first resonator other than the first bonding surface, the surface of the second resonator other than the second bonding surface, and the sidewall surfaces around the adhesive layer. The conductive layer is made of silver and has a thickness of 8-12 μm. Its characteristics are: The inner wall of the first coupling groove is concave relative to the first bonding surface, and the inner wall of the second coupling groove is concave relative to the second bonding surface. The first coupling groove extends in the vertical direction and penetrates the upper and lower surfaces of the first resonator, and the second coupling groove extends in the vertical direction and penetrates the upper and lower surfaces of the second resonator. The adhesive layer is formed by sintering a composite adhesive at 800-950°C. The composite adhesive is prepared by mixing an adhesive with silicon oxide powder and barium oxide powder. The adhesive layer is also used to block the entry of metal particles forming the conductive layer. The adhesive layer covers the inner wall of the first coupling groove and is located between the conductive layer and the inner wall of the first coupling groove, and covers the inner wall of the second coupling groove and is located between the conductive layer and the inner wall of the second coupling groove. The first coupling groove and the second coupling groove work together to achieve capacitive coupling between the first resonator and the second resonator.

2. A method for manufacturing the filter according to claim 1, characterized in that: The following steps are involved: a. Dry-pressing the ceramic powder into a green embryo of the first resonator and the second resonator; b. sintering the green embryo of the first resonator and the green embryo of the second resonator into the first resonator and the second resonator; c. Cleaning the first bonding surface of the first resonator and the second bonding surface of the second resonator, applying the composite adhesive on the first bonding surface and / or the second bonding surface, and applying the composite adhesive on the inner wall surface of the first coupling groove and the inner wall surface of the second coupling groove; d. Laminating the first resonator and the second resonator, and bonding the first resonator and the second resonator to each other by the composite adhesive; e. Sintering the first resonator and the second resonator after bonding, sintering the composite adhesive into the bonding layer to obtain a semi-finished filter; f. Plating a metal layer on the surface of the semi-finished product to produce the filter.

3. The production method according to claim 2, characterized in that: The sintering temperature in step e is less than or equal to the sintering temperature in step b.

Images