Filtering device and radio frequency front-end module

Abstract

The utility model discloses a filtering device and a radio frequency front-end module, and the filtering device comprises a substrate which is provided with a first surface; the plurality of interdigital transducers are arranged on the first surface; the first thin film layer is arranged on the first surface, the first thin film layer is provided with a plurality of first open holes penetrating to the first surface, and the interdigital transducers are located in the first open holes; the second thin film layer is arranged on the side, back to the first face, of the first thin film layer, and the second thin film layer and the positions, corresponding to the first open holes, of the first face define a plurality of cavities; the length of the cavity in the first direction is W, the length of the cavity in the second direction is L, the thickness of the first thin film layer in the third direction is H1, the first direction and the second direction are both parallel to the first surface and are perpendicular to each other, and the third direction is perpendicular to the first surface; wherein 2.5 < = W / H1 < = 25, and / or 2.5 < = L / H1 < = 25. The structural stability of the cavity can be improved, meanwhile, the overall size of the filtering device can be compatible, and instrument miniaturization is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of radio frequency filtering, in particular to a filtering device and a radio frequency front-end module. Background Art

[0002] As an important device of the radio frequency front end, the surface acoustic wave filter (SAWF) works on the principle that acoustic waves are transmitted on the chip surface. The package of the filter must ensure that the surface of the interdigital transducer (IDT) does not come into contact with other substances to guarantee the working space.

[0003] However, during the packaging process, due to external pressure such as the pressure generated during plastic packaging, the cavity structure of the filter may be deformed, and in severe cases, it may collapse, thus affecting the operation of the interdigital transducer. Therefore, how to improve the stability of the cavity structure has become an urgent problem to be solved. Summary of the Utility Model

[0004] In view of this, the utility model provides a filtering device and a radio frequency front-end module.

[0005] In a first aspect of the utility model, a filtering device is provided, including:

[0006] A substrate having a first surface;

[0007] A plurality of interdigital transducers disposed on the first surface;

[0008] A first thin film layer disposed on the first surface, and the first thin film layer is provided with a plurality of first openings penetrating through the first surface, and the interdigital transducers are located in the first openings;

[0009] A second thin film layer disposed on a side of the first thin film layer opposite to the first surface, and the second thin film layer and the first surface enclose a plurality of cavities corresponding to the plurality of first openings;

[0010] The length of the cavity in a first direction is W, the length of the cavity in a second direction is L, the thickness of the first thin film layer in a third direction is H1, the first direction and the second direction are both parallel to the first surface, and the first direction and the second direction are perpendicular to each other, and the third direction is perpendicular to the first surface;

[0011] Wherein, 2.5 ≤ W / H1 ≤ 25, and / or, 2.5 ≤ L / H1 ≤ 25.

[0012] In a second aspect of the utility model, a radio frequency front-end module is provided, including the above-mentioned filtering device.

[0013] As can be seen from the above technical solutions, the filtering device proposed by the present utility model constructs a cavity that can accommodate the interdigital transducer through the arrangement of the first thin film layer and the second thin film layer, ensuring the working space, and defining 2.5 ≤ W / H1 ≤ 25 or 2.5 ≤ L / H1 ≤ 25. While improving the structural stability of the cavity, it can also be compatible with the overall size of the filtering device, facilitating the miniaturization of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained as these drawings.

[0015] Figure 1 is a structural usage diagram of the filtering device proposed by the embodiment of the present application from a top view angle;

[0016] Figure 2 is Figure 1 a cross-sectional schematic view of the structure at A-A shown;

[0017] Figure 3 is Figure 1 a cross-sectional schematic view of the deformation mode of the structure at A-A shown;

[0018] Figure 4 is Figure 1 a cross-sectional schematic view of the structure at A-A shown with the second thin film layer and solder balls hidden.

[0019] DESCRIPTION OF THE REFERENCE NUMERALS:

[0020] 100, filtering device; 10, substrate; 10a, first surface; 11, piezoelectric layer; 12, substrate layer; 13, temperature compensation layer; 20, interdigital transducer; 30, first thin film layer; 31, first opening; 32, second opening; 40, second thin film layer; 41, third opening; 50, cavity; 60, pad; 70, solder ball. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0022] It should be understood that all the directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0023] It should also be understood that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element present at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or can also be indirectly connected to the other element through an intermediate element.

[0024] The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. Descriptions involving "first", "second", etc. in the present application are only for descriptive purposes and cannot be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0025] It should be further understood that the term "and / or" used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] Please refer to Figures 1 to 4 , an embodiment of the present application provides a filtering device 100, which includes a substrate 10, a plurality of interdigital transducers 20, a first thin film layer 30, and a second thin film layer 40. The substrate 10 has a first surface 10a; a plurality of interdigital transducers 20 are disposed on the first surface 10a; the first thin film layer 30 is disposed on the first surface 10a, and the first thin film layer 30 is provided with a plurality of first openings 31 penetrating to the first surface 10a, and the interdigital transducers 20 are located in the first openings 31. The second thin film layer 40 is disposed on a side of the first thin film layer 30 facing away from the first surface 10a, and the second thin film layer 40 encloses a plurality of cavities 50 corresponding to the plurality of first openings 31 on the first surface 10a. The length of the cavity 50 in the first direction is W, the length of the cavity 50 in the second direction is L, the thickness of the first thin film layer 30 in the third direction is H1, the first direction and the second direction are both parallel to the first surface 10a, and the first direction and the second direction are perpendicular to each other, and the third direction is perpendicular to the first surface 10a; wherein, 2.5 ≤ W / H1 ≤ 25, and / or, 2.5 ≤ L / H1 ≤ 25.

[0027] The filtering device 100 proposed in the embodiment of the present application constructs a cavity 50 that can accommodate the interdigital transducer 20 through the settings of the first thin film layer 30 and the second thin film layer 40, ensuring the working space of the interdigital transducer 20, and defining 2.5 ≤ W / H1 ≤ 25 or 2.5 ≤ L / H1 ≤ 25. While improving the structural stability of the cavity 50, it can also be compatible with the overall size of the filtering device 100, which is beneficial to the miniaturization of the device.

[0028] Among them, the substrate 10, the interdigital transducer 20 disposed on the first surface 10a of the substrate 10, and the reflection grating form a resonator.

[0029] In some embodiments, the cavity 50 can accommodate the interdigital transducer 20 and the reflection gratings on both sides of the interdigital transducer 20. Exemplarily, some cavities 50 can only accommodate the interdigital transducer 20 of a single resonator and the corresponding reflection grating, and some cavities 50 can accommodate the interdigital transducers 20 of multiple resonators and the corresponding reflection gratings, such as two cascaded or parallel resonators, or a longitudinally coupled surface acoustic wave resonator including at least two interdigital transducers 20.

[0030] It should be noted that the volume of the cavity 50 is determined by the length W in the first direction, the length L in the second direction, and the height in the third direction. The height of the cavity 50 in the third direction is limited by the thickness H1 of the first thin film layer 30 in the third direction. When the height is fixed, if it is too wide or too narrow, it is prone to collapse, and the cavity 50 needs to be stable. If the overall size of the cavity 50 is relatively large, it is easy to collapse. To ensure the structural stability of the cavity 50 and avoid the collapse of the cavity 50, the thickness of the first thin film layer 30 can be increased. If the overall size of the cavity 50 is relatively small, then for the same chip, the number of cavities 50 required will increase. To ensure the stability of the cavity 50 and take into account the process manufacturing conditions, a certain width needs to be reserved between the first openings 31 of the first thin film layer 30. The more cavities 50 there are, the more width needs to be reserved, thus increasing the size of the filtering device 100. Therefore, to be compatible with the structural stability of the cavity 50 and the miniaturization requirements of the filtering device 100, it is defined that 2.5 ≤ W / H1 ≤ 25, and / or 2.5 ≤ L / H1 ≤ 25, that is, the ratio of any one of W and L to H1 is limited within the range of 2.5 to 25. While improving the structural stability of the cavity 50, it can also be compatible with the overall size of the filtering device 100, which is beneficial to the miniaturization of the device.

[0031] Exemplarily, W / H1 can be any value within the range of 2.5 to 25. For example, W / H1 can be 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25, etc.

[0032] Exemplarily, L / H1 can be any value within the range of 2.5 to 25. For example, L / H1 can be 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25, etc.

[0033] In some embodiments, the substrate 10 can be a single-layer piezoelectric structure, that is, the substrate 10 is composed of a single piezoelectric material. Of course, in other embodiments, the substrate 10 can also be a multi-layer piezoelectric structure, which is composed of piezoelectric layers 11 of different materials or the same material but with different properties. These layers are stacked together in a specific manner to achieve the desired performance.

[0034] In some embodiments, the multi-layer piezoelectric structure includes a piezoelectric layer 11 and a substrate layer 12. A plurality of interdigital transducers 20 are disposed on the piezoelectric layer 11, and the substrate layer 12 is disposed on the side of the piezoelectric layer 11 opposite to the interdigital transducers 20. The piezoelectric layer 11 is made of a piezoelectric material, such as a piezoelectric material mainly composed of lithium niobate, lithium tantalate, or quartz. The piezoelectric layer 11 has a good piezoelectric effect and can convert mechanical stress into an electrical signal or convert an electrical signal into mechanical stress. The substrate layer 12 is a support layer for the piezoelectric layer 11, and its main function is to provide mechanical support and protection for the piezoelectric layer 11, and at the same time ensure that the piezoelectric layer 11 can be evenly stressed when subjected to an external force. In addition, the substrate layer 12 can also jointly form a specific acoustic structure with the piezoelectric layer 11 to optimize the performance of the resonator.

[0035] In some embodiments, the substrate layer 12 can be an insulating substrate 10 such as silicon material with high resistivity, sapphire, or spinel.

[0036] In some embodiments, the multi-layer piezoelectric structure can further include a temperature compensation layer 13. The temperature compensation layer 13 is disposed between the piezoelectric layer 11 and the substrate layer 12. The function of the temperature compensation layer 13 is to compensate for the influence of temperature change on the performance of the piezoelectric layer 11 through its specific thermal expansion coefficient and mechanical properties. This helps to maintain the stability and reliability of the device under different temperature conditions.

[0037] It can be understood that the materials or structures of the piezoelectric layer 11, the substrate layer 12, and the temperature compensation layer 13 of the present application are not limited herein, as long as the desired performance can be achieved.

[0038] In some embodiments, the filtering device 100 includes a plurality of resonators. The resonator includes a substrate 10, an interdigital transducer 20 disposed on the first surface 10a of the substrate 10, and two reflection gratings. The plurality of resonators in the filtering device 100 are disposed on the same substrate 10, that is, they share the substrate 10. The two reflection gratings are disposed on both sides of the interdigital transducer 20 along the propagation direction of the acoustic wave. The reflection grating is used to confine the surface acoustic wave within the interdigital transducer 20. The piezoelectric layer 11 has a piezoelectric effect, that is, a charge distribution and mechanical deformation will be generated when an electric field or mechanical stress is applied. The interdigital transducer 20, as an important part of the resonator, functions to complete the conversion between electrical energy and mechanical energy, that is, to generate and detect surface acoustic waves. The structure of the interdigital transducer 20 is usually fabricated onto the piezoelectric layer 11 using a lithography - coating - stripping or coating - lithography - etching process, or can also be fabricated by other process methods. When a voltage signal is applied to the piezoelectric layer 11, the interdigital transducer 20 excites acoustic waves in the piezoelectric material. This changing voltage causes the piezoelectric layer 11 to deform, thereby exciting surface acoustic waves, and using the piezoelectric effect to generate and propagate surface acoustic waves on the surface of the piezoelectric layer 11, so as to realize signal processing and transmission.

[0039] In some embodiments, the plurality of resonators can be arranged according to requirements. For example, the plurality of resonators can be arranged in parallel along the acoustic wave propagation direction to achieve the insertion loss and out - of - band rejection of the corresponding filtering device 100. The plurality of resonators can be two, three, four, etc.

[0040] In some embodiments, the length W of the cavity 50 in the first direction is orthogonal to the acoustic wave propagation direction, and the length L of the cavity 50 in the second direction is parallel to the acoustic wave propagation direction, so as to form a rectangular cavity 50 surrounding the interdigital transducer 20, which has better structural stability.

[0041] In some embodiments, the filtering device 100 can be a ladder - type structure filter. The ladder - type structure filter can include a plurality of series - arm resonators and a plurality of parallel - arm resonators. Of course, in some other embodiments, the filtering device 100 can also be other types of filters.

[0042] It should be noted that the resonator of the present application can be a common surface acoustic wave resonator, a TC - SAW (Temperature compensated SAW) resonator, a piezoelectric thin - film SAW resonator, an X - BAR (transversely excited thin - film bulk acoustic wave) resonator, etc., which have an interdigital transducer 20. The present application does not make a limitation here.

[0043] In some embodiments, the projected area of the cavity 50 on the first surface 10a is S, where S ≤ 0.25 mm 2Since the area of the cavity 50 is too large, it is prone to collapse and has poor structural stability. Therefore, in order to balance the structural stability and the overall size of the cavity 50, the area of the cavity 50 is set to be less than or equal to 0.25 mm 2 , which can improve the structural stability of the cavity 50 while also being compatible with the overall size of the filtering device 100, facilitating the miniaturization of the instrument.

[0044] Exemplarily, S can be 0.25 mm 2 , 0.24 mm 2 , 0.23 mm 2 , 0.22 mm 2 , 0.21 mm 2 , 0.2 mm 2 , 0.19 mm 2 , 0.18 mm 2 , 0.17 mm 2 , 0.16 mm 2 , 0.15 mm 2 , 0.14 mm 2 , 0.13 mm 2 , 0.12 mm 2 , 0.11 mm 2 , 0.1 mm 2 , 0.09 mm 2 , 0.08 mm 2 , 0.07 mm 2 , 0.06 mm 2 , 0.05 mm 2 , 0.04 mm 2 , 0.03 mm 2 , 0.02 mm 2 , 0.01 mm 2 etc.

[0045] In some embodiments, W is 25 μm to 250 μm, and / or, L is 25 μm to 250 μm. Since the area of the cavity 50 is determined by the length W in the first direction and the length L in the second direction, that is, S = W × L, and if the cavity 50 is too wide or too narrow, it is prone to collapse. If the area of the cavity 50 is too large, it is prone to collapse and has poor structural stability. If the area of the cavity 50 is too small, many cavities 50 are required to meet the resonator performance, and setting many cavities 50 requires more space, affecting the overall size. Therefore, W can be restricted within the range of 25 μm to 250 μm, and / or, L can be restricted within the range of 25 μm to 250 μm, so that the lengths of the cavity 50 in the first direction and the second direction can be limited within a suitable range, which can improve the structural stability of the cavity 50 while also being compatible with the overall size of the filtering device 100, facilitating the miniaturization of the instrument.

[0046] Exemplarily, W can be any value within the range of 25 μm to 250 μm. For example, W can be 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, or 250 μm, etc.

[0047] Exemplarily, L can be any value within the range of 25 μm to 250 μm. For example, L can be 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, 210 μm, 220 μm, 230 μm, 240 μm, or 250 μm, etc.

[0048] Please refer to Figure 1 , in some embodiments, among the multiple interdigital transducers 20, the distance between two adjacent interdigital transducers 20 is D1, and D1 ≥ 25 μm. Since the distance between adjacent interdigital transducers 20 is too close, it may affect the resonator performance. Therefore, it is defined that D1 ≥ 25 μm, so as to avoid affecting the resonator performance.

[0049] Exemplarily, D1 can be 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, or 40 μm, etc.

[0050] In some embodiments, among the multiple cavities 50, the distance between two adjacent cavities 50 is D2, the thickness of the first thin film layer 30 in the third direction is H1, the third direction is perpendicular to the first surface 10a, and D2 / H1 ≥ 2. Among them, if the distance between two adjacent cavities 50 is too wide, it will result in a large occupied area, and setting multiple cavities 50 requires more space, affecting the overall size. If the distance between two adjacent cavities 50 is too narrow, the cavity 50 is prone to collapse and the supporting force is insufficient. Therefore, it is defined that D2 / H1 ≥ 2, which can improve the structural stability of the cavity 50 while being compatible with the overall size of the filtering device 100, facilitating the miniaturization of the instrument.

[0051] In some embodiments, the volume of the cavity 50 is positively correlated with the thickness of the first thin film layer 30. Thus, when the thickness of the first thin film layer 30 is thicker, the volume of the cavity 50 can be set larger, and the structural stability of the cavity 50 can also be maintained.

[0052] In some embodiments, H1 ≥ 10 μm. Since the height of the cavity 50 is affected by the thickness of the first thin film layer 30, thus, in order to meet the resonator performance, setting the thickness H1 of the first thin film layer 30 to be greater than 10 μm can be compatible with the height of the cavity 50 and avoid affecting the resonator performance.

[0053] Exemplarily, H1 can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, or 30 μm, etc.

[0054] In some embodiments, H1 ≥ 10 μm, then D2 ≥ 2H1, that is, D2 ≥ 20 μm. Exemplarily, D2 can be 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm, 52 μm, 54 μm, 56 μm, 58 μm, or 60 μm, etc.

[0055] Please refer to Figures 2 to 4 , in some embodiments, the first thin film layer 30 and the second thin film layer 40 have the same hardness or the same material, and the thickness of the second thin film layer 40 in the third direction is H2; wherein, H2 / H1 ≥ 2. Thus, the structure of the cavity 50 can be made more stable. Of course, in other embodiments, the hardness or the material of the first thin film layer 30 and the second thin film layer 40 can also be different. When the hardness of the second thin film layer 40 is greater than that of the first thin film layer 30, the second thin film layer 40 may not need to be thicker than the first thin film layer 30.

[0056] In some embodiments, the first thin film layer 30 and the second thin film layer 40 have the same hardness or the same material, H1 ≥ 10 μm, then H2 ≥ 2H1, then H2 ≥ 20 μm. Exemplarily, H2 can be 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 32 μm, 34 μm, 36 μm, 38 μm, 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm, 52 μm, 54 μm, 56 μm, 58 μm, or 60 μm, etc.

[0057] In some embodiments, the first thin film layer 30 is mainly composed of polyamide, epoxy resin, solder mask, or ultraviolet curable organic matter. It can be understood that the main component can be regarded as the metal with the highest content ratio in this layer structure, for example, the metal with the highest weight ratio. Exemplarily, the first thin film layer 30 may only contain polyamide, or may have other minor components in addition to polyamide. In other examples, the first thin film layer 30 may only contain epoxy resin, or may have other minor components in addition to epoxy resin. Or, the first thin film layer 30 may only contain solder mask, or may have other minor components in addition to solder mask. Or, the first thin film layer 30 may only contain ultraviolet curable organic matter, or may have other minor components in addition to ultraviolet curable organic matter. It can be understood that the first thin film layer 30 of the present application may also be mainly composed of other insulating organic materials, which are not limited herein as long as the required performance can be achieved.

[0058] In some embodiments, the second thin film layer 40 is mainly composed of polyamide, epoxy resin, solder mask, or ultraviolet curable organic matter. Exemplarily, the second thin film layer 40 may only contain polyamide, or may have other minor components in addition to polyamide. In other examples, the second thin film layer 40 may only contain epoxy resin, or may have other minor components in addition to epoxy resin. Or, the second thin film layer 40 may only contain solder mask, or may have other minor components in addition to solder mask. Or, the second thin film layer 40 may only contain ultraviolet curable organic matter, or may have other minor components in addition to ultraviolet curable organic matter. It can be understood that the second thin film layer 40 of the present application may also be mainly composed of other insulating organic materials, which are not limited herein as long as the required performance can be achieved.

[0059] Please refer to Figures 1 to 4 , in some embodiments, the first surface 10a is further provided with a pad 60, and the first thin film layer 30 is provided with a second opening 32 penetrating through to the pad 60; wherein, the length of the second opening 32 in the first direction is greater than or equal to 25 μm and less than the length of the pad 60 in the first direction. Thus, setting the length of the second opening 32 in the first direction to be greater than 25 μm is conducive to process implementation, and setting it to be less than the length of the pad 60 in the first direction can avoid affecting the performance of the resonator.

[0060] Exemplarily, the length of the second opening 32 in the first direction may be 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, or 40 μm, etc.

[0061] Please refer to Figures 2 to 3, in some embodiments, a third opening 41 is provided at the second thin film layer 40 corresponding to the second opening 32, and both the second opening 32 and the third opening 41 are filled with a conductive material; a solder ball 70 is provided on the side of the second thin film layer 40 facing away from the first thin film layer 30, and the solder ball 70 is connected to the pad 60 through the conductive material. Thus, by filling the first opening 31 and the third opening 41 with the conductive material, the electrical connection between the solder ball 70 and the pad 60 is realized, which is beneficial to the connection between the resonator and the circuit board.

[0062] Exemplarily, the solder ball 70 can be a weldable material such as tin, gold, copper, etc. The solder ball 70 can be provided at the top of the third opening 41 or near the third opening 41, which is not limited herein as long as the required performance can be achieved.

[0063] Exemplarily, the conductive material mainly consists of copper, aluminum, silver or gold. Exemplarily, the conductive material can only contain copper, or in addition to copper, it can also have other minor components. In other examples, the conductive material can only contain aluminum, or in addition to aluminum, it can also have other minor components. Or, the conductive material can only contain silver, or in addition to silver, it can also have other minor components. Or, the conductive material can only contain gold, or in addition to gold, it can also have other minor components. It can be understood that the conductive material of the present application can also mainly consist of other metal materials, which is not limited herein as long as the required performance can be achieved.

[0064] The embodiment of the present application also proposes a radio frequency front-end module, including the above-mentioned filtering device 100.

[0065] In some embodiments, the radio frequency front-end module can be applied to an electronic device, and the electronic device can include but is not limited to electronic devices or components with wireless communication functions such as tablet computers, laptop computers, desktop computers, navigators, mobile phones and electronic watches, etc., and the present application does not limit this.

[0066] In some embodiments, the radio frequency front-end module can include multiple filtering devices 100, and the multiple filtering devices 100 can be two, three, etc.

[0067] In some embodiments, the radio frequency front-end module can also include a low-noise amplifier, a radio frequency switch, a power amplifier, etc., and the specific connection method can refer to the prior art and will not be elaborated herein.

[0068] In addition, since the radio frequency front-end module includes the above-mentioned filtering device 100, therefore, the radio frequency front-end module has all the beneficial effects of the filtering device 100, which will not be elaborated one by one herein.

[0069] Subject to no contradiction, those skilled in the art may combine and integrate different embodiments or examples described in this specification and the features of different embodiments or examples.

[0070] As described above, the above are only specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily conceive various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. A filtering device, characterized in that, Comprising: A substrate having a first surface; A plurality of interdigital transducers disposed on the first surface; A first thin film layer disposed on the first surface, and the first thin film layer is provided with a plurality of first openings penetrating to the first surface, and the interdigital transducers are located in the first openings; A second thin film layer disposed on a side of the first thin film layer opposite to the first surface, and the second thin film layer and the first surface enclose a plurality of cavities at corresponding positions of the plurality of first openings; The length of the cavity in the first direction is W, the length of the cavity in the second direction is L, the thickness of the first thin film layer in the third direction is H1, the first direction and the second direction are both parallel to the first surface, and the first direction and the second direction are perpendicular to each other, and the third direction is perpendicular to the first surface; Wherein, 2.5 ≤ W / H1 ≤ 25, and / or, 2.5 ≤ L / H1 ≤ 25.

2. The filtering device according to claim 1, wherein, The projected area of the cavity on the first surface is S, where S ≤ 0.25 mm 2 ; and / or, W is 25 μm to 250 μm, and / or, L is 25 μm to 250 μm.

3. The filtering device according to claim 1, characterized in that Among the plurality of interdigital transducers, the distance between two adjacent interdigital transducers is D1, D1 ≥ 25 μm; and / or, Among the plurality of cavities, the distance between two adjacent cavities is D2, the thickness of the first thin film layer in the third direction is H1, the third direction is perpendicular to the first surface, D2 / H1 ≥ 2.

4. The filtering device according to claim 1, characterized in that The volume of the cavity is positively correlated with the thickness of the first thin film layer.

5. The filtering device according to claim 1, characterized in that The H1 ≥ 10 μm.

6. The filtering device according to claim 1, characterized in that, The first thin film layer and the second thin film layer have the same hardness or the same material, and the thickness of the second thin film layer in the third direction is H2; Wherein, H2 / H1 ≥ 2.

7. The filtering device according to claim 1, characterized in that, The first thin film layer includes any one of a polyacrylamide film, an epoxy resin film, a solder mask film, and an ultraviolet curable organic film; and / or, The second thin film layer includes any one of a polyacrylamide film, an epoxy resin film, a solder mask film, and an ultraviolet curable organic film.

8. The filtering device according to claim 1, characterized in that The first surface is further provided with a pad, and the first thin film layer is provided with a second opening penetrating to the pad; Wherein, the length of the second opening in the first direction is greater than or equal to 25 μm and less than the length of the pad in the first direction.

9. The filtering device according to claim 8, characterized in that, The second thin film layer is provided with a third opening corresponding to the second opening, and the second opening and the third opening are both filled with a conductive material; A solder ball is disposed on a side of the second thin film layer facing away from the first thin film layer, and the solder ball is connected to the pad through the conductive material.

10. A radio frequency front-end module, characterized in that, Comprising the filtering device according to any one of claims 1-9.

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