A multi-layer flexible circuit board

Abstract

The present invention relates to a multi-layer flexible circuit board, which includes a circuit board body, a protection structure, and a dehumidification structure. The circuit board body includes multiple circuit boards stacked together. A buffer cavity is formed inside the circuit board body, and the buffer cavity is connected to the inner wall of the circuit board. The protection structure is arranged at the periphery of the circuit board body and is provided with a protection part relative to the circuit board body. An installation cavity is formed inside the protection structure, and the installation cavity surrounds the periphery of the circuit board body. The dehumidification structure penetrates through the installation cavity and is provided with a filter screen facing the buffer cavity, and a dehumidifying agent is filled inside the dehumidification structure. The present invention aims to improve the flexibility of the circuit board and ensure the stability of the circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit boards, and particularly to a multi-layer flexible circuit board. Background Art

[0002] Flexible circuit boards are widely used in various electronic products where there is relative movement between components during operation to provide power / signal transmission due to their excellent flexural performance. As electronic products develop towards being lighter, thinner, shorter, and smaller, higher requirements are also put forward for flexible circuit boards. A circuit board of the same area must include more circuits to provide more functions. Flexible circuit boards have gradually transitioned from single-sided boards to double-sided boards, and then from double-sided boards to multi-layer boards.

[0003] In related technologies, the thicknesses of the first outer circuit layer and the second outer circuit layer of the circuit board are relatively thin, so the conductive circuits in the first outer circuit layer and the second outer circuit layer can be made more detailed. Additionally, in the inner circuit layer, each undergoes copper reduction treatment and has a relatively thick thickness, which can prevent the inner circuit layer from being penetrated when forming blind holes on both sides, thereby avoiding the blind holes becoming through holes. This design is relatively complex, and when the number of circuit layers in the flexible circuit board exceeds six, its flexibility is greatly reduced. The contradiction between the reduction of the flexibility of the circuit board and the increase in the number of layers has become a problem that urgently needs to be solved. Summary of the Invention

[0004] The main object of the present invention is to provide a multi-layer flexible circuit board, aiming to improve the flexibility of the circuit board and ensure the stability of the circuit board.

[0005] To achieve the above object, a multi-layer flexible circuit board proposed by the present invention includes a circuit board body, a protection structure, and a dehumidification structure:

[0006] The circuit board body includes multiple circuit boards stacked together, and a buffer cavity is formed inside the circuit board body and is connected to the inner wall of the circuit board;

[0007] The protection structure is provided at the periphery of the circuit board body and has a protection part relative to the circuit board body. An installation cavity is formed inside the protection structure and surrounds the periphery of the circuit board body; and

[0008] The dehumidification structure penetrates through the installation cavity and is provided with a filter screen facing the buffer cavity, and a dehumidifying agent is filled inside the dehumidification structure.

[0009] In an embodiment of the present application, the circuit board includes a circuit main board and a circuit layer:

[0010] There are multiple groups of the circuit main boards, and multiple groups of the circuit main boards are stacked together; and

[0011] The circuit layer is inserted between adjacent circuit main boards, and the circuit layer includes two oppositely arranged circuit support boards, the board width of the circuit support boards is less than half of the board width of the circuit main board, the circuit support boards are stacked on the ends of the circuit main boards, and the circuit support boards and the circuit main board enclose a buffer cavity.

[0012] In one embodiment of the present application, the circuit layer is provided with a plurality of groups, and the plurality of circuit layers and the circuit main board are arranged alternately, and the buffer cavity is provided with a plurality of groups, and the plurality of buffer cavities are evenly distributed from the middle of the circuit board to the outer edge of the circuit board.

[0013] In one embodiment of the present application, the protection structure includes a plurality of stacked protection blocks, the protection blocks are arranged at the periphery of the circuit board and wrap around the circuit board, and each of the protection blocks corresponds to one circuit board.

[0014] In one embodiment of the present application, the protection block includes a first protection portion, a second protection portion and a third protection portion:

[0015] The first protection part is connected to the circuit board and is located at the end of the circuit board body, and the first protection part is provided with a guard part relative to the circuit board;

[0016] The second protection portion is connected to an end of the first protection portion away from the protection portion;

[0017] The third protection part is connected to the end face of the second protection part facing away from the first protection part. The third protection part is provided with two groups relatively. A sealing plate is provided on the end face of the third protection part away from the circuit board facing the buffer cavity. The two sealing plates abut against each other. The sealing plate, the third protection part and the circuit board enclose the installation cavity.

[0018] In one embodiment of the present application, two groups of the first protection parts are provided, and the two first protection parts are arranged opposite to each other. At least two groups of the second protection parts are provided opposite to each other. Multiple groups of the second protection parts are respectively connected to one group of the first protection parts, and are stacked together in sequence along the direction away from the protection parts.

[0019] In one embodiment of the present application, the protection block further includes a fourth protection portion, the fourth protection portion is disposed between the two third protection portions and corresponds to the buffer cavity, and the dehumidification structure is wrapped around the fourth protection portion.

[0020] In one embodiment of the present application, a snap-in groove is provided at one end of the third protection part and the fourth protection part away from the sealing plate, and the snap-in groove is provided on the end surface of the third protection part and the fourth protection part away from the circuit board, and the dehumidification structure is snap-connected to the snap-in groove.

[0021] In an embodiment of the present application, the dehumidification structure includes a protection tube and a capillary storage tube:

[0022] The protection tube penetrates through the installation cavity and is provided with the filter screen facing the buffer cavity; and

[0023] The capillary storage tube penetrates through the protection tube. The capillary storage tube is filled with a dehumidifying agent. A plurality of capillary holes are arrayed on the capillary storage tube, and an extension section is provided facing the filter screen. The extension section surrounds the periphery of the filter screen, and the dehumidifying agent is connected to the filter screen.

[0024] In an embodiment of the present application, one end of the protection tube away from the buffer cavity is connected to the protection structure, and a heat dissipation end is provided opposite to the protection structure. The heat dissipation end surrounds the outer edge of the capillary storage tube.

[0025] The technical solution of the present invention divides the multi-layer flexible circuit board into a circuit board body, a protection structure and a dehumidification structure structurally. The circuit board body is composed of multiple groups of circuit boards stacked together. The multiple groups of circuit boards can be interconnected, and complex circuit lines can be miniaturized to improve the performance of the circuit board. The circuit board itself is a multi-layer flexible circuit board. However, if the number of stacked layers is too large, the flexibility will decrease and the overall state of the circuit board will be poor. Therefore, multiple groups of buffer cavities are provided near the center of the circuit board body. Through the buffer cavities, the circuit board with more stacked layers can still retain flexibility, avoiding direct damage when the circuit board is impacted or the like. At the same time, a stress sensing module can be attached to the circuit board body in the buffer cavity. The stress sensing module is electrically connected to the circuit board. When the pressure received by the circuit board body is too large, the stress sensing module will send an alarm signal to the circuit board body. The circuit board body will electrically connect to a buzzer / diode for audible and visual alarm when receiving the alarm signal. At the same time, the circuit board body generates a delay shutdown command by itself and starts to shut down when the delay ends and no additional command is received again, which is beneficial to protecting the circuit board and enabling the circuit board to work stably. Similarly, the protection structure is provided at the periphery of the circuit board body, and protective parts are convexly provided opposite to the upper and lower end faces of the circuit board body. The protective parts are above the circuit board and can protect the edges of the circuit board body to avoid damage caused by bumping during use. At the same time, an installation cavity is provided in the protection structure. The installation cavity is arranged around the circuit board body for one week. The dehumidification structure can be installed through the installation cavity, which contains a dehumidifying agent. At the same time, the dehumidification structure is provided with a filter screen facing the buffer cavity, and the dehumidifying agent is connected to the filter screen. The filter screen can prevent the dehumidifying agent from falling out of the dehumidification structure and polluting the circuit board body. At the same time, it can absorb the water vapor in the circuit board, and when the circuit board body works and generates heat, the water vapor can be discharged from other positions through heat absorption, enabling the dehumidifying agent to be reused, and at the same time taking into account the heat dissipation effect. Through the above structure, the flexibility of the circuit board can be effectively improved and the stability of the circuit board can be ensured. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0027] Figure 1 It is a schematic structural diagram of an embodiment of a multi-layer flexible circuit board of the present invention;

[0028] Figure 2 It is a cross-sectional view of a multi-layer flexible circuit board of the present invention in one direction;

[0029] Figure 3 It is a cross-sectional view of a multi-layer flexible circuit board of the present invention in another direction.

[0030] Explanation of the reference numerals in the drawings:

[0031] 1. Circuit board body; 2. Circuit board; 21. Circuit main board; 22. Circuit layer; 23. Circuit branch board; 24. Buffer cavity; 3. Protection structure; 4. Protection block; 41. First protection part; 42. Protection part; 43. Second protection part; 44. Third protection part; 45. Sealing plate; 46. Installation cavity; 47. Fourth protection part; 48. Clamping groove; 5. Dehumidification structure; 51. Protection tube; 52. Filter screen; 53. Heat dissipation end; 54. Capillary storage tube; 55. Dehumidifying agent; 56. Extension section.

[0032] The realization of the object, functional features and advantages of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0033] In order to make the object, technical solution and advantages of the present application more clear, the following will further describe the present application in detail in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] Refer to Figures 1 to 3, in an embodiment of the present invention, a multi-layer flexible circuit board is proposed, which includes a circuit board body 1, a protection structure 3, and a dehumidification structure 5. The circuit board body 1 includes multiple groups of circuit boards 2 stacked together. A buffer cavity 24 is formed inside the circuit board body 1, and the buffer cavity 24 is connected to the inner wall of the circuit board 2; the protection structure 3 is provided at the periphery of the circuit board body 1, and a protection portion 42 is provided opposite to the circuit board body 1. An installation cavity 46 is formed inside the protection structure 3, and the installation cavity 46 surrounds the periphery of the circuit board body 1; the dehumidification structure 5 penetrates through the installation cavity 46 and is provided with a filter screen 52 facing the buffer cavity 24, and a dehumidifying agent 55 is filled inside the dehumidification structure 5.

[0035] In a multi-layer flexible circuit board of the present application, the multi-layer flexible circuit board is structurally divided into a circuit board body 1, a protection structure 3, and a dehumidification structure 5. The circuit board body 1 is composed of multiple groups of circuit boards 2 stacked together. The multiple groups of circuit boards 2 can be interconnected, which can miniaturize complex circuit lines and improve the performance of the circuit board. The circuit board itself is a multi-layer flexible circuit board. However, if the number of stacked layers is too large, the flexibility will decrease and the overall state of the circuit board will be poor. Therefore, multiple groups of buffer cavities 24 are formed near the center of the circuit board body 1. Through the buffer cavities 24, a circuit board with more stacked layers can still retain its flexibility, avoiding direct damage when the circuit board is impacted or the like. At the same time, a stress sensing module can be attached to the buffer cavity 24 relative to the circuit board body 1, and the stress sensing module is electrically connected to the circuit board 2. When the pressure received by the circuit board body 1 is too large, the stress sensing module will send an alarm signal to the circuit board body 1. The circuit board body 1 will receive the alarm signal and be electrically connected to a buzzer / diode for sound and light alarm. At the same time, the circuit board body 1 will generate a delay shutdown command by itself and start shutdown when the delay ends and no additional instruction is received again, which is beneficial to protecting the circuit board and enabling the circuit board to work stably. Similarly, the protection structure 3 is provided at the periphery of the circuit board body 1, and protection portions 42 are convexly provided on the upper and lower end faces of the protection structure 3 relative to the circuit board body 1. The protection portions 42 are located above the circuit board 2 and can protect the edges of the circuit board body 1 to avoid damage caused by bumping during use. At the same time, an installation cavity 46 is formed inside the protection structure 3, and the installation cavity 46 is arranged to surround the circuit board body 1 for one week. The dehumidification structure 5 can be installed through the installation cavity 46, and it contains a dehumidifying agent 55 inside. At the same time, the dehumidification structure 5 is provided with a filter screen 52 facing the buffer cavity 24, and the dehumidifying agent 55 is connected to the filter screen 52. The filter screen 52 can prevent the dehumidifying agent 55 from falling out of the dehumidification structure 5 and polluting the circuit board body 1. At the same time, it can absorb the water vapor inside the circuit board, and when the circuit board body 1 works and generates heat, the water vapor can be discharged from other positions through heat absorption, enabling the dehumidifying agent 55 to be reused, and at the same time taking into account the heat dissipation effect. Through the above structure, the flexibility of the circuit board can be effectively improved, and the stability of the circuit board can be ensured.

[0036] Referring toFigures 2 to 3 , in an embodiment of the present application, the circuit board 2 includes a circuit main board 21 and a circuit layer 22. There are multiple groups of circuit main boards 21, and the multiple groups of circuit main boards 21 are stacked together; the circuit layer 22 is inserted between adjacent circuit main boards 21. The circuit layer 22 includes two oppositely arranged circuit support boards 23. The board width of the circuit support board 23 is less than half of the board width of the circuit main board 21. The circuit support board 23 is stacked at the end of the circuit main board 21, and a buffer cavity 24 is formed by enclosing the circuit support board 23 and the circuit main board 21.

[0037] In a multi-layer flexible circuit board of the present application, the circuit board 2 includes a circuit main board 21 and a circuit layer 22. The main circuits are all arranged on the circuit main board 21. Multiple groups of circuit main boards 21 are stacked together, and wire routing operations can be performed through the vias provided on the circuit main board 21, making the circuit design more convenient. Multiple groups of circuit main boards 21 stacked together can also have a certain degree of flexibility. However, when the number of circuits exceeds a certain amount, due to the excessive number of boards, the flexibility decreases. In order to protect the circuit board, the circuit layer 22 is oppositely provided. The circuit layer 22 is inserted between two circuit main boards 21. The circuit layer 22 includes two oppositely arranged circuit support boards 23. The board width of the circuit support board 23 is less than half of the board width of the circuit main board 21, and the circuit support board 23 is connected to the end of the circuit main board 21. The circuit support board 23 can assist the circuit main board 21 in wire routing to ensure the stability of the circuit. At the same time, a buffer cavity 24 is formed by enclosing the two oppositely arranged circuit support boards 23. Through the buffer cavity 24, the flexibility of the circuit board 2 can be maintained, and the circuit board 2 can be prevented from being easily damaged.

[0038] Referring to Figures 2 to 3 , in an embodiment of the present application, there are multiple groups of circuit layers 22. The multiple groups of circuit layers 22 and the circuit main boards 21 are arranged alternately. There are multiple groups of buffer cavities 24, and the multiple groups of buffer cavities 24 are evenly distributed from the middle of the circuit board 2 to the outer edge of the circuit board 2.

[0039] In a multi-layer flexible circuit board of the present application, there are multiple groups of circuit layers 22. The multiple groups of circuit layers 22 and the circuit main boards 21 are arranged alternately. Through the multiple groups of circuit layers 22, the number of circuit main boards 21 that can be stacked can also increase synchronously. And because there are multiple groups of circuit layers 22, multiple groups of buffer cavities 24 will be formed synchronously. The multiple groups of buffer cavities 24 are evenly dispersed from the middle of the circuit board 2 to the outer edge of the circuit board body 1, which can reduce the stress on the circuit board body 1 and ensure the safety of the circuit board body 1.

[0040] Referring to Figures 1 to 2 , in an embodiment of the present application, the protection structure 3 includes multiple groups of protection blocks 4 stacked together. The protection blocks 4 are provided at the periphery of the circuit board 2 and surround the circuit board 2. Each protection block 4 corresponds to a circuit board 2.

[0041] In a multi-layer flexible circuit board of the present application, in this embodiment, the protective structure 3 is not a whole. The protective structure 3 includes multiple groups of protective blocks 4 stacked together. The protective blocks 4 are arranged on the periphery of the circuit board 2. Each circuit board 2 has at least one group of protective blocks 4 on its outer edge. These protective blocks 4 can serve as supports to prevent the circuit board from being damaged due to bumps.

[0042] Combined with reference Figures 1 to 3 In one embodiment of the present application, the protection block 4 includes a first protection portion 41, a second protection portion 43 and a third protection portion 44. The first protection portion 41 is connected to the circuit board 2 and is located at the end of the circuit board body 1. The first protection portion 41 is provided with a protection portion 42 relative to the circuit board 2; the second protection portion 43 is connected to the end of the first protection portion 41 away from the protection portion 42; the third protection portion 44 is connected to the end face of the second protection portion 43 away from the first protection portion 41, and two groups of third protection portions 44 are provided opposite to each other. The end of the third protection portion 44 away from the circuit board 2 is provided with a sealing plate 45 facing the buffer cavity 24, and the two sealing plates 45 abut against each other. The sealing plate 45, the third protection portion 44 and the circuit board 2 enclose a mounting cavity 46.

[0043] In a multilayer flexible circuit board of the present application, the protection block 4 includes a first protection portion 41, a second protection portion 43 and a third protection portion 44, the first protection portion 41 is connected to the circuit board 2, and is located at the bottom end surface and / or the top end surface of the circuit board body 1, the first protection portion 41 is provided with a protection portion 42 opposite to the first protection portion 41, and the side of the circuit board body 1 can be protected by the protection portion 42, and the second protection portion 43 is connected to the first protection portion 41, and the second protection portion 43 is used to connect multiple protection blocks 4 into a whole to improve their protection performance, and a connecting portion or a so-called connection portion is provided between adjacent protection portions. The welding part and the docking part, while the circuit boards 2 are connected to each other, the protection part can reinforce the circuit board 2 and make the process more efficient. The third protection part 44 is connected to the second protection part 43, and two groups are relatively arranged. There is a certain distance between the two groups of third protection parts 44. The principle is that a sealing plate 45 is relatively arranged at one end of the circuit board 2. After the two sealing plates 45 are connected to each other, they are combined with the circuit board 2 to form an installation cavity 46. The installation cavity 46 can be used according to the heat dissipation structure. In this embodiment, the installation cavity 46 is provided with a dehumidification structure 5 to further protect the circuit board.

[0044] Combined with reference Figures 1 to 3 In one embodiment of the present application, two groups of first protection portions 41 are provided, and the two first protection portions 41 are arranged opposite to each other. At least two groups of second protection portions 43 are provided opposite to each other. Multiple groups of second protection portions 43 are respectively connected to one group of first protection portions 41, and are stacked together in sequence along a direction away from the protection portion 42.

[0045] In a multi-layer flexible circuit board of the present application, there are two sets of first protection parts 41. The two first protection parts 41 are arranged oppositely. Therefore, there are at least two sets of second protection parts 43 arranged oppositely. Since the buffer cavity 24 is arranged between the oppositely arranged second protection parts 43, more buffer cavities 24 can increase the number of second protection parts 43. However, if the number of second protection parts 43 exceeds a certain amount, the circuit board will also lose its flexibility due to the mutual support of multiple circuit boards 2. Only part of the second protection parts 43 can be divided into fourth protection parts 47 and buffer cavities 24 are provided to improve the lamination of the circuit board.

[0046] Referring to Figure 2 , in an embodiment of the present application, the protection block 4 further includes a fourth protection part 47. The fourth protection part 47 is arranged between two third protection parts 44 and is arranged corresponding to the buffer cavity 24. The dehumidification structure 5 is wrapped around the fourth protection part 47.

[0047] In a multi-layer flexible circuit board of the present application, the protection block 4 further includes a fourth protection part 47. The fourth protection part 47 is arranged between two third protection parts 44, and a part of it is connected to the circuit branch board 23. The fourth protection part 47 is only arranged on the side of the circuit board 2 away from the buffer cavity 24. Therefore, generally, two sets of fourth protection parts 47 need to be arranged oppositely on one layer of the circuit board 2.

[0048] Referring to Figure 2 , in an embodiment of the present application, a clamping groove 48 is provided at one end of the third protection part 44 and the fourth protection part 47 away from the sealing plate 45. The clamping groove 48 is arranged on the end face of the third protection part 44 and the fourth protection part 47 facing away from the circuit board 2. The dehumidification structure 5 is clamped in the clamping groove 48.

[0049] In a multi-layer flexible circuit board of the present application, a clamping groove 48 is provided at one end of the third protection part 44 and the fourth protection part 47 away from the sealing plate 45. The clamping groove 48 is located at one end of the third protection part 44 and the fourth protection part 47 away from the circuit board body 1. The dehumidification structure 5 is clamped in the clamping groove 48, which can facilitate the transfer of moisture in the circuit board body 1 to the clamping groove 48 with the help of osmotic pressure by the dehumidification structure 5, facilitating the protection of the circuit board.

[0050] Referring to Figures 1 to 3 , in an embodiment of the present application, the dehumidification structure 5 includes a protection tube 51 and a capillary storage tube 54. The protection tube 51 penetrates through the installation cavity 46 and is provided with a filter screen 52 facing the buffer cavity 24; the capillary storage tube 54 penetrates through the protection tube 51. The capillary storage tube 54 is filled with a dehumidifying agent 55. A plurality of capillary holes are arrayed on the capillary storage tube 54, and an extension section 56 is provided facing the filter screen 52. The extension section 56 wraps around the periphery of the filter screen 52, and the dehumidifying agent 55 is connected to the filter screen 52.

[0051] In a multi-layer flexible circuit board of the present application, the dehumidification structure 5 includes a protective tube 51 and a capillary storage tube 54. The protective tube 51 is used to protect the capillary storage tube 54 and is connected to the protection structure 3. A filter screen 52 is provided in the area of the outer wall of the protective tube 51 facing the buffer cavity 24. The capillary storage tube 54 is filled with a dehumidifying agent 55, and a plurality of capillary holes are arrayed and penetrated on its surface. The position of the capillary storage tube 54 facing the filter screen 52 is provided with an extension end relative to the outer edge of the filter screen 52. The extension end wraps around the filter screen 52, so that the dehumidifying agent 55 can be directly connected to the filter screen 52 through the extension end, while the filter screen 52 can block the dehumidifying agent 55. Through the filter screen 52, the dehumidification structure 5 can absorb the moisture that may exist in the circuit board, so as to achieve the purpose of protecting the circuit board.

[0052] Referring to Figures 1 to 2 , in an embodiment of the present application, one end of the protective tube 51 away from the buffer cavity 24 is connected to the protection structure 3, and a heat dissipation end 53 is provided relative to the protection structure 3. The heat dissipation end 53 wraps around the outer edge of the capillary storage tube 54.

[0053] In a multi-layer flexible circuit board of the present application, one end of the protective tube 51 away from the buffer cavity 24 is connected to the protection structure 3, and a heat dissipation end 53 is provided relatively. The outer edge of the heat dissipation end 53 is connected to the protection structure 3, but the heat dissipation end 53 can still wrap the capillary storage tube 54 inside. Through the heat dissipation end 53, the capillary storage tube 54 can be directly in contact with the outside world, absorb water vapor at the filter screen 52, and at the same time can absorb the heat generated when the circuit board body 1 works. Because the dehumidifying agent 55 is filled in the capillary storage tube 54, with the help of the osmotic pressure and the heat dissipation end 53, the dehumidifying agent 55 will precipitate the absorbed water vapor while dissipating heat at the heat dissipation end 53, so that the dehumidifying agent 55 can return to its original state, which can make the dehumidifying agent 55 reusable, save costs, and at the same time help the circuit board dissipate heat. Through the above structure, the flexibility of the circuit board can be improved and the stability of the circuit board can be ensured.

[0054] In the drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0055] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A multi-layer flexible circuit board, characterized in that: include: A circuit board body, the circuit board body comprising a plurality of circuit boards stacked together, a buffer cavity being provided in the circuit board body, and the buffer cavity being connected to an inner wall of the circuit board; A protection structure, wherein the protection structure is arranged at the periphery of the circuit board body and has a protection portion relative to the circuit board body, and an installation cavity is opened in the protection structure, and the installation cavity surrounds the periphery of the circuit board body; A dehumidification structure, wherein the dehumidification structure is disposed through the installation cavity and is provided with a filter screen facing the buffer cavity, and the dehumidification structure is filled with a dehumidifier; The protection structure includes a plurality of stacked protection blocks, the protection blocks are arranged at the periphery of the circuit board and surround the circuit board, and each protection block corresponds to one circuit board; The protection block includes a first protection part, a second protection part, and a third protection part. The first protection part is connected to the circuit board and is located at the end of the circuit board body. The first protection part is provided with a protection part relative to the circuit board. The second protection part is connected to the end of the first protection part away from the protection part. The third protection part is connected to the end face of the second protection part away from the first protection part. Two groups of the third protection parts are provided opposite to each other. A sealing plate is provided on the end face of the third protection part away from the circuit board facing the buffer cavity. The two sealing plates are abutted against each other. The sealing plate, the third protection part and the circuit board enclose the installation cavity.

2. A multi-layer flexible circuit board according to claim 1, characterized in that: The circuit board comprises: A circuit main board, wherein the circuit main board is provided in a plurality of groups, and the plurality of groups of the circuit main boards are stacked together; and The circuit layer is inserted between adjacent circuit main boards, and the circuit layer includes two oppositely arranged circuit support boards, the board width of the circuit support boards is less than half of the board width of the circuit main board, the circuit support boards are stacked on the ends of the circuit main boards, and the circuit support boards and the circuit main board enclose a buffer cavity.

3. A multi-layer flexible circuit board according to claim 2, characterized in that: The circuit layers are provided with a plurality of groups, and the circuit layers and the circuit main board are arranged alternately. The buffer cavities are provided with a plurality of groups, and the buffer cavities are evenly distributed from the middle of the circuit board to the outer edge of the circuit board.

4. A multi-layer flexible circuit board according to claim 1, characterized in that: The first protection parts are provided with two groups, the two first protection parts are arranged opposite to each other, the second protection parts are provided with at least two groups opposite to each other, and multiple groups of the second protection parts are respectively connected to one group of the first protection parts, and are stacked together in sequence along the direction away from the protection parts.

5. A multi-layer flexible circuit board according to claim 4, characterized in that: The protection block further includes a fourth protection portion, which is disposed between the two third protection portions and corresponds to the buffer cavity, and the dehumidification structure is wrapped around the fourth protection portion.

6. A multi-layer flexible circuit board according to claim 5, characterized in that: The third protection part and the fourth protection part are provided with a clamping groove at one end away from the sealing plate. The clamping groove is provided on the end surface of the third protection part and the fourth protection part away from the circuit board, and the dehumidification structure is clamped in the clamping groove.

7. A multi-layer flexible circuit board according to any one of claims 1 to 3, characterized in that: The dehumidification structure comprises: a protective tube, the protective tube being passed through the installation cavity and provided with the filter screen facing the buffer cavity; and A capillary storage tube is passed through the protective tube and filled with a dehumidifier. A plurality of capillary holes are arranged in an array on the capillary storage tube, and an extension section is provided facing the filter. The extension section is wrapped around the periphery of the filter, and the dehumidifier is connected to the filter.

8. The multi-layer flexible circuit board according to claim 7, characterized in that: One end of the protection tube away from the buffer cavity is connected to the protection structure, and a heat dissipation end is provided opposite to the protection structure. The heat dissipation end surrounds the outer edge of the capillary storage tube.

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