Filter packaging structure and preparation method thereof

Abstract

The invention discloses a filter packaging structure and a preparation method thereof. The filter packaging structure comprises a circuit board, a solder mask deposited on the circuit board and a plurality of filters. Wherein the solder mask comprises a plurality of first areas used for exposing the circuit board, the arrangement position of the filter corresponds to the first areas, and the filter completely covers the first areas; the side, close to the circuit board, of the filter abuts against the solder mask layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter packaging, in particular to a filter packaging structure and a preparation method thereof. BACKGROUND

[0002] In the modern electronic manufacturing field, especially in the packaging process of radio frequency front-end modules (such as modules containing filters and switches), it is necessary to realize stable and reliable interconnection between the filter and the printed circuit board (PCB) substrate, and the manufacturing cost also needs to be considered.

[0003] At present, the existing technology adopts a surface film coating packaging process. After the filter is attached to the substrate, a special protective film is coated on the surface of the filter. The film needs to accurately cover all the filters and be bonded with the substrate, thereby forming a temporary cavity structure above the filter. Subsequently, the entire assembly with the protective film enters the reflow soldering furnace to complete the sintering and molding of the solder joints. After the high-temperature process is completed, the protective film is removed, and finally molding is performed to form a permanent package.

[0004] However, the special protective film is relatively expensive, and the film coating and film removal processes require additional production equipment and precise process control, significantly increasing equipment investment and process time, leading to an increase in overall packaging costs. Moreover, in the case where no protective film is used and the filter and the substrate are directly packaged, there may be a gap between the bottom of the filter and the solder resist layer on the substrate. This results in poor sealing of the packaging structure and compromises the reliability of the device.

[0005] In view of the technical problems of high cost and insufficient reliability in packaging the module with the attached filter in the existing technology, no effective solutions have been proposed so far. SUMMARY

[0006] The present disclosure provides a filter packaging structure and a preparation method thereof to at least solve the technical problems of high cost and insufficient reliability in packaging the module with the attached filter in the existing technology.

[0007] According to one aspect of the present application, a filter packaging structure is provided, comprising a circuit board, a solder resist layer deposited on the circuit board, and a plurality of filters. The solder resist layer includes a plurality of first areas for exposing the circuit board, the setting positions of the filters correspond to the first areas, and the filters completely cover the first areas; and the side of the filter close to the circuit board abuts against the solder resist layer.

[0008] According to another aspect of the present application, a method for manufacturing a filter packaging structure is provided, which is used for manufacturing the filter packaging structure as described above, and is implemented by the following steps: providing a circuit board, wherein a solder mask layer is formed on the circuit board, and a filter is arranged on a first region of the solder mask layer, and the filter completely covers the first region; mounting a cover plate on the plurality of filters, wherein the cover plate is formed with a plurality of cover plate protrusions corresponding to the filters on a side close to the circuit board, and the cover plate protrusions abut against the filters; reflow soldering the plurality of filters close to the circuit board to the solder mask layer by using a reflow soldering process; and removing the cover plate.

[0009] To solve the technical problem of high cost and insufficient reliability in packaging the module with the filter attached, the present application provides a filter packaging structure. In the solder mask layer, a plurality of first regions for exposing the circuit board are present. Since the filter is arranged at a position corresponding to the first region and completely covers the first region, a sealed cavity can be formed between the filter, the solder mask layer and the circuit board when the filter close to the circuit board abuts against the solder mask layer. Therefore, compared with the case of directly packaging the module with the filter attached, the above structure can avoid the gap between the filter and the solder mask layer on the circuit board, thereby improving the sealing performance of the filter packaging structure and ensuring the reliability of the filter packaging structure.

[0010] Moreover, the filter packaging structure provided by the present application does not need a film, which can simplify the production process and reduce the packaging cost. Thus, the technical problem of high cost and insufficient reliability in packaging the module with the filter attached in the prior art is solved.

[0011] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of some embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0012] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in different drawings denote the same or similar components or parts. It should be understood by those skilled in the art that the drawings are not necessarily drawn to scale. In the drawings: Figure 1 is a schematic cross-sectional view of the filter packaging structure according to an embodiment of the present application; Figure 2 is a flowchart of a method for manufacturing the filter packaging structure according to an embodiment of the present application; Figure 3 is a schematic view of a to-be-packaged structure without the cover plate and with a plurality of filters attached according to an embodiment of the present application; Figure 4is a schematic diagram of a structure to be packaged according to the cover plate and the plurality of filters attached in the embodiment of the present application; Figure 5 is a schematic diagram of a structure to be packaged according to the cover plate and the plurality of filters attached in the embodiment of the present application after reflow soldering; and Figure 6 is a schematic diagram of a structure to be packaged according to the cover plate and the plurality of filters attached in the embodiment of the present application after the cover plate is removed. DETAILED DESCRIPTION

[0013] It should be noted that the embodiments and features of the present disclosure can be combined if there is no conflict. The present disclosure will be described in detail with reference to the accompanying drawings and embodiments.

[0014] In order to enable persons skilled in the art to better understand the present disclosure scheme, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all. Based on the embodiments in the present disclosure, all other embodiments obtained by persons skilled in the art without creative labor should belong to the scope of protection of the present disclosure.

[0015] It should be noted that the terms "first", "second", and the like in the specification and claims of the present disclosure and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the terms thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0016] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of a feature, step, operation, device, component and / or combination thereof.

[0017] Figure 1is a schematic cross-sectional view of a filter packaging structure according to embodiments of the present application. According to an aspect of the present application, there is provided a filter packaging structure 10, comprising: a circuit board 100, a solder resist layer 200 deposited on the circuit board 100, and a plurality of filters 310. The solder resist layer 200 comprises a plurality of first areas 210 for exposing the circuit board 100, the filters 310 are arranged at positions corresponding to the first areas 210, and the filters 310 completely cover the first areas 210; and a side of the filters 310 close to the circuit board 100 abuts against the solder resist layer 200.

[0018] Specifically, referring to Figure 1 As shown in the figure, the circuit board 100 in the filter packaging structure 10 is deposited with the solder resist layer 200 comprising a plurality of first areas 210, wherein the first areas 210 are for exposing the circuit board 100.

[0019] Further, above the first areas 210 vertically, corresponding filters 310 are arranged. The orthographic projection of the filters 310 on the circuit board 100 completely covers the first areas 210. And a side of the filters 310 close to the circuit board 100 abuts against the solder resist layer 200.

[0020] Thus, in the filter packaging structure 10 provided by the present application, a sealed cavity can be formed between the filters 310, the solder resist layer 200 and the circuit board 100, preventing external pollution factors from invading the inside of the filter packaging structure 10. That is, the above structure can improve the reliability of the filter packaging structure 10.

[0021] As described in the background, in the field of modern electronic manufacturing, especially in the packaging process of radio frequency front-end modules (such as modules containing filters and switches), it is necessary to realize stable and reliable interconnection between the filter and the printed circuit board (PCB) substrate, and the manufacturing cost also needs to be considered. At present, the surface film coating packaging process is adopted in the prior art. After the filter is attached to the substrate, a special protective film is coated on the surface of the filter. The film needs to accurately cover all the filters and adhere to the substrate, thereby forming a temporary cavity structure above the filter. Subsequently, the entire assembly with the protective film enters the reflow soldering furnace to complete the sintering and molding of the solder joints. After the high-temperature process is completed, the protective film is removed, and finally molding (Molding) is performed to form a permanent package. However, the special protective film is relatively expensive, and the film coating and film removal processes require additional production equipment and precise process control, significantly increasing equipment investment and process time, leading to an increase in overall packaging cost. Moreover, in the case where the protective film is not used and the filter and the substrate are directly packaged, there may be a gap between the bottom of the filter and the solder resist layer on the substrate. Thus, the sealing performance of the package is poor, which damages the reliability of the device.

[0022] Therefore, the filter packaging structure provided by the present application can avoid the gap between the filter and the solder resist layer on the circuit board, thereby improving the sealing performance of the filter packaging structure and ensuring the reliability of the filter packaging structure.

[0023] In addition, the filter packaging structure provided by the present application does not need a film, which can simplify the production process and reduce the packaging cost. Thus, the technical problem of high cost and insufficient reliability in packaging the module with the filter mounted thereon in the prior art is solved.

[0024] Preferably, the substrate of the filter 310 can be, for example, a lithium niobate (LN) substrate, a lithium tantalate (LT) substrate, and a POI substrate, etc. Those skilled in the art should note that this is not limited here.

[0025] Optionally, a plurality of first solder balls 311 are fixedly connected to the side of the filter 310 close to the circuit board 100.

[0026] Specifically, as shown in Figure 1 , a plurality of first solder balls 311 are arranged on the side of the filter 310 close to the circuit board 100, and each first solder ball 311 is fixedly connected to the filter 310.

[0027] Thus, each first solder ball 311 can provide stable electrical connection between the filter 310 and the circuit board 100, ensure signal transmission between the filter 310 and the circuit board 100, and also provide certain mechanical connection strength. In addition, the material of the first solder ball 311 can be, for example, gold material, tin material, copper material, etc.

[0028] Optionally, it further comprises a first pad 410 arranged on the circuit board 100 in the first area 210, and the first solder ball 311 is fixedly connected to the first pad 410.

[0029] Specifically, as shown in Figure 1 , the first pad 410 is located in the first area 210 of the solder resist layer 200 and is arranged on the circuit board 100 in the first area 210. The position of the first pad 410 corresponds to the first solder ball 311, and the first solder ball 311 is fixedly connected to the first pad 410.

[0030] Thus, the first soldering pad 410 can provide a stable electrical connection point for the filter 310 on the circuit board 100, thereby ensuring the reliability of the electrical connection between the filter 310 and the circuit board 100.

[0031] Optionally, the filter packaging structure 10 further comprises a switch 320, wherein the solder mask layer 200 comprises a second area 220 for exposing the circuit board 100, the switch 320 is arranged at a position corresponding to the second area 220, and the switch 320 completely covers the second area 220; and a gap exists between a side of the switch 320 close to the circuit board 100 and the solder mask layer 200.

[0032] Specifically, referring to FIG. 2, the filter packaging structure 10 further comprises the switch 320. Moreover, the solder mask layer 200 comprises the second area 220 for exposing the circuit board 100. Figure 1

[0033] Further, the switch 320 is arranged vertically above the second area 220. Herein, the orthographic projection of the switch 320 on the circuit board 100 completely covers the second area 220, and a gap exists between a side of the switch 320 close to the circuit board 100 and the solder mask layer 200. That is, the switch 320 does not contact the solder mask layer 200.

[0034] Preferably, the element arranged vertically above the second area 220, for example, can be not only the switch 320, but also a power amplifier (PA), a low noise amplifier (LNA), etc. Those skilled in the art should note that this is not limited herein.

[0035] Optionally, a plurality of second solder balls 321 are fixedly connected to a side of the switch 320 close to the circuit board 100.

[0036] Specifically, referring to FIG. 2, a plurality of second solder balls 321 are arranged on a side of the switch 320 close to the circuit board 100, and each second solder ball 321 is fixedly connected to the switch 320. Figure 1

[0037] Thus, each second solder ball 321 can provide a stable electrical connection for the switch 320 and the circuit board 100, and also provide a certain mechanical connection strength. Moreover, the material of the second solder ball 321 can be, for example, gold material, tin material, copper material, etc.

[0038] Optionally, the filter packaging structure 10 further comprises a second soldering pad 420 arranged on the circuit board 100 in the second area 220, and the second solder ball 321 is fixedly connected to the second soldering pad 420.

[0039] Specifically, referring to FIG. 2, the second soldering pad 420 is arranged on the circuit board 100 in the second area 220, and the second solder ball 321 is fixedly connected to the second soldering pad 420. Figure 1 ​​As shown, the second soldering pad 420 is located in the second area 220 of the solder resist layer 200, and is arranged on the circuit board 100 in the second area 220. The second soldering pad 420 is located corresponding to the second solder ball 321, and the second solder ball 321 is fixedly connected to the second soldering pad 420.

[0040] Therefore, the second soldering pad 420 can provide a stable electrical connection point for the switch 320 on the circuit board 100, thereby ensuring the reliability of the electrical connection between the switch 320 and the circuit board 100.

[0041] Optionally, the filter packaging structure 10 further comprises a packaging layer 500, wherein the packaging layer 500 covers the solder resist layer 200, the plurality of filters 310, and the switch 320, and fills the gap between the switch 320 and the circuit board 100.

[0042] Specifically, referring to Figure 1 As shown, the filter packaging structure 10 further comprises a packaging layer 500. The packaging layer 500 covers the solder resist layer 200, the plurality of filters 310, and the switch 320, and fills the gap between the switch 320 and the circuit board 100.

[0043] Therefore, the packaging layer 500 can realize airtight packaging of the plurality of filters 310 and the switch 320, and can provide mechanical protection.

[0044] Figure 2 A flowchart of a preparation method of a filter packaging structure according to an embodiment of the present application is shown. Figure 3 is a schematic diagram of a to-be-packaged structure according to an embodiment of the present application, which is not installed with a cover plate and has mounted a plurality of filters. Figure 4 is a schematic diagram of a to-be-packaged structure according to an embodiment of the present application, which is installed with a cover plate and has mounted a plurality of filters. Figure 5 is a schematic diagram of a to-be-packaged structure according to an embodiment of the present application, which has mounted a plurality of filters after reflow soldering. Figure 6 is a schematic diagram of a to-be-packaged structure according to an embodiment of the present application, which has mounted a plurality of filters after removing the cover plate.

[0045] Referring to Figure 2 As shown, according to a second aspect of the present application, a preparation method of a filter packaging structure is provided, which is used to prepare a filter packaging structure 10 as described above, and is realized by the following steps: S202: providing a circuit board 100, wherein the circuit board 100 is formed with a solder resist layer 200, and a filter 210 is arranged corresponding to a first area 210 of the solder resist layer 200, and the filter 210 completely covers the first area 210; S204: mounting the cover plate 600 on the plurality of filters 310, wherein the cover plate 600 is formed with cover plate bumps 610 corresponding to the filters 310 on the side close to the circuit board 100, and the cover plate bumps 610 abut against the filters 310; S206: reflow soldering the plurality of filters 310 on the side close to the circuit board 100 to the solder mask 200 by using a reflow soldering process; S208: removing the cover plate 600.

[0046] Specifically, referring to Figures 3-6 the filter packaging structure 10, first, the circuit board 100 is provided and serves as the base of the filter packaging structure 10. The circuit board 100 is provided with a solder mask 200 including a plurality of first areas 210. The filters 310 are arranged vertically above the first areas 210, such that the first areas 210 are completely covered by the filters 310 (S202).

[0047] Then, the cover plate 600 with a plurality of cover plate bumps 610 is provided, and the cover plate 600 is mounted on the plurality of filters 310. Each cover plate bump 610 is formed on the side close to the circuit board 100 and corresponds to and abuts against each filter 310 (S204).

[0048] Further, the cover plate 600, the filters 310, and the solder mask 200 are reflow soldered, such that each filter 310 is fixedly connected to the solder mask on the side close to the circuit board 100 (S206).

[0049] Finally, the cover plate 600 is removed, and a to-be-packaged structure with the plurality of filters 310 mounted thereon is formed as shown in Figure 6 (S208).

[0050] Thus, by using the reflow soldering process and applying pressure to each filter 310 by the cover plate 600, a sealed cavity is formed between the filter 310, the solder mask 200, and the circuit board 100 in the filter packaging structure 10 provided in the present application, so as to prevent external pollution factors from invading the inside of the filter packaging structure 10. In turn, the reliability of the filter packaging structure 10 is improved.

[0051] Optionally, before the circuit board 100 is provided, the method further includes: depositing and etching the solder mask 200 on the circuit board 100 to form a plurality of first areas 210 for exposing the circuit board 100; depositing and etching a pad layer in the first areas 210 to form first pads 410; and forming first solder balls 311 on the filters 310 and placing the first solder balls 311 on the corresponding first pads 410.

[0052] Specifically, before packaging the structure to be packaged with the plurality of filters 310 mounted thereon, a structure to be packaged with the plurality of filters 310 mounted thereon is prepared in advance as shown in FIG. 2. Figure 3 The structure to be packaged with the plurality of filters 310 mounted thereon is shown in FIG. 2. First, a solder resist layer 200 is deposited and etched on the circuit board 100 to form a plurality of first areas 210 for exposing the circuit board 100. Then, a pad layer is deposited on the first areas 210 and etched to form a plurality of first pads 410. Further, a ball mounting process is adopted and a plurality of first solder balls 311 are fixed on the filters 310 by soldering. After that, the filters 310 are placed above the corresponding first areas 210 such that the first solder balls 311 are in contact with the corresponding first pads 410.

[0053] Thus, in the subsequent packaging process, the first solder balls 311 can be melted and fixedly connected with the first pads 410 by using a reflow soldering process.

[0054] Optionally, before providing the circuit board 100, the method further comprises: depositing and etching a solder resist layer 200 on the circuit board 100 to form a second area 220 for exposing the circuit board 100; depositing and etching a pad layer on the second area 220 to form a second pad 420; and providing a switch 320, forming a second solder ball 321 on the switch 320, and placing the second solder ball 321 on the corresponding second pad 420.

[0055] Specifically, while the structure to be packaged with the plurality of filters 310 mounted thereon is prepared, the switch 320 is also mounted on the circuit board 100. The preparation steps include: first, depositing and etching a solder resist layer 200 to form a second area 220 for exposing the circuit board 100. Then, a pad layer is deposited on the second area 220 and etched to form a second pad 420. Further, a ball mounting process is adopted and a second solder ball 321 is fixed on the switch 320 by soldering. After that, the switch 320 is placed above the corresponding second area 220 such that the second solder ball 321 is in contact with the corresponding second pad 420.

[0056] Thus, in the subsequent packaging process, the second solder ball 321 can be melted and fixedly connected with the second pad 420 by using a reflow soldering process.

[0057] It should be noted by those skilled in the art that the preparation steps of mounting the filter module on the circuit board 100 and mounting the switch 320 on the circuit board 100 are performed simultaneously and will not be described herein.

[0058] Optionally, when the cover plate 600 is removed, the method further includes: encapsulating the plurality of filters 310 such that the resulting encapsulation layer 500 covers the solder mask layer 200, the plurality of filters 310 and the switch 320, and fills the gap between the switch 320 and the circuit board 100.

[0059] Specifically, refer to Figure 1 As shown, after removing the cover plate 600, flowing encapsulation material is filled into the gap between the switch 320 and the circuit board 100, and covers the solder mask layer 200, multiple filters 310, and the switch 320. This results in the formation of the encapsulation layer 500 after curing.

[0060] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0061] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0062] In the description of this disclosure, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this disclosure and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this disclosure; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0063] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A filter packaging structure (10), characterized in that, include: The circuit board (100), the solder mask (200) deposited on the circuit board (100), and the plurality of filters (310), wherein The solder mask layer (200) includes a plurality of first regions (210) for exposing the circuit board (100), the filter (310) is positioned corresponding to the first regions (210), and the filter (310) completely covers the first regions (210); and The filter (310) abuts against the solder mask layer (200) on the side of the circuit board (100) closest to the filter (310).

2. The filter packaging structure (10) according to claim 1, characterized in that, The filter (310) has a plurality of first solder balls (311) fixedly connected to one side of the circuit board (100).

3. The filter packaging structure (10) according to claim 2, characterized in that, Also includes: Within the first region (210), a first pad (410) is disposed on the circuit board (100), and the first solder ball (311) is fixedly connected to the first pad (410).

4. The filter packaging structure (10) according to claim 1, characterized in that, Also includes: A switch (320), wherein the solder mask layer (200) includes a second region (220) for exposing the circuit board (100), the switch (320) is positioned corresponding to the second region (220), and the switch (320) completely covers the second region (220); and There is a gap between the switch (320) and the solder mask layer (200) on the side of the switch (320) near the circuit board (100).

5. The filter packaging structure (10) according to claim 4, characterized in that, The switch (320) has a plurality of second solder balls (321) fixedly connected to one side of the circuit board (100).

6. The filter packaging structure (10) according to claim 5, characterized in that, Also includes: Within the second region (220), a second pad (420) is disposed on the circuit board (100), and the second solder ball (321) is fixedly connected to the second pad (420).

7. The filter packaging structure (10) according to claim 4, characterized in that, Also includes: An encapsulation layer (500) covers the solder mask layer (200), the plurality of filters (310) and the switch (320), and fills the gap between the switch (320) and the circuit board (100).

8. A method for fabricating a filter packaging structure, characterized in that, The filter packaging structure (10) as described in any one of claims 1 to 7 is achieved through the following steps: A circuit board (100) is provided, wherein a solder mask layer (200) is formed on the circuit board (100), and a filter (210) is disposed corresponding to a first region (210) of the solder mask layer (200), the filter (310) completely covering the first region (210). A cover plate (600) is installed on the plurality of filters (310), wherein the cover plate (600) forms a cover plate bump (610) corresponding to each filter (310) on the side of the circuit board (100), and the cover plate bump (610) abuts against the filter (310). Using a reflow soldering process, the plurality of filters (310) are reflow soldered to the solder mask layer (200) on the side of the circuit board (100) closest to it; and Remove the cover plate (600).

9. The method according to claim 8, characterized in that, Prior to providing the circuit board (100), the following are also included: The solder mask layer (200) is deposited and etched on the circuit board (100) to form a plurality of first regions (210) for exposing the circuit board (100). A pad layer is deposited and etched within the first region (210) to form a first pad (410); and A first solder ball (311) is formed on the filter (310) and the first solder ball (311) is placed on the corresponding first pad (410).

10. The method according to claim 8, characterized in that, Prior to providing the circuit board (100), the following are also included: The solder mask layer (200) is deposited and etched on the circuit board (100) to form a second region (220) for exposing the circuit board (100). A pad layer is deposited and etched within the second region (220) to form a second pad (420); and A switch (320) is provided, on which a second solder ball (321) is formed, and the second solder ball (321) is placed on the corresponding second pad (420).

11. The method according to claim 10, characterized in that, In the case of removing the cover plate (600), the method further includes: encapsulating the plurality of filters (310) such that the resulting encapsulation layer (500) covers the solder mask layer (200), the plurality of filters (310) and the switch (320), and fills the gap between the switch (320) and the circuit board (100).

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