Flexible circuit board and display device

Abstract

A flexible circuit board comprises a main body and an extension located on one side of the main body; the main body is provided with a plurality of electronic components, the extension comprises a first sub-extension and a second sub-extension which are at least partially overlapped and unconnected, the first sub-extension and the second sub-extension being able to bend independently in different directions; an end of the first sub-extension close to the main body and an end of the second sub-extension close to the main body are connected to the same position of the main body, an end of the first sub-extension away from the main body is provided with a first connector, and an end of the second sub-extension away from the main body is provided with a second connector. The flexible circuit board of the disclosed embodiment can save the space occupied by the flexible circuit board, and is conducive to achieving lightweight electronic products.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of circuit boards, and in particular to a flexible circuit board and a display device. Background Art

[0002] Flexible printed circuit boards (FPCs) are widely used in a variety of precision electronic devices due to their good bendability and thin appearance. Lightweighting is an important development trend of electronic consumer products. In this context, the circuits inside the products will be more integrated. Taking the display industry as an example, the structure of the touch screen has evolved from a rigid display component + touch component to a flexible display component + touch component and then to an integrated display and touch component, in order to achieve the purpose of reducing the size of the display frame.

[0003] In current electronic products, there are a large number of functional modules, such as display / touch / core computing / gravity sensing, etc. In order to facilitate the debugging of the whole machine and prevent signal crosstalk, each module usually uses a separate FPC, which is connected to the mainboard separately and routed separately. This makes it difficult to compress the space reserved for routing and FPC arrangement in the whole machine. The current design of multi-layer printed boards has solved the problem of insufficient routing space caused by multiple FPCs. However, when flexible circuit boards are currently used, they can only be connected to the whole machine at different positions. If the space reserved for the circuit board (such as width) of the whole machine is insufficient, it is difficult to lead out multiple signals, which restricts the application of flexible circuit boards. Summary of the invention

[0004] An embodiment of the present disclosure provides a flexible circuit board, comprising a main body and an extension portion located on one side of the main body; the main body is provided with a plurality of electronic components, the extension portion comprises a first sub-extension portion and a second sub-extension portion which are at least partially overlapped and unconnected, the first sub-extension portion and the second sub-extension portion being capable of independently bending in different directions; an end of the first sub-extension portion close to the main body and an end of the second sub-extension portion close to the main body are connected to the same position of the main body, an end of the first sub-extension portion away from the main body is provided with a first connector, and an end of the second sub-extension portion away from the main body is provided with a second connector.

[0005] The embodiment of the present disclosure further provides a display device, including a display module, wherein the display module includes a display panel and the flexible circuit board bound and connected to the display panel.

[0006] The flexible circuit board of the embodiment of the present disclosure extends from the same position of the main body to form a first sub-extension portion and a second sub-extension portion that are at least partially overlapped and unconnected. The first sub-extension portion and the second sub-extension portion can be independently bent in different directions. In this way, the first sub-extension portion can be independently connected to an external circuit through a first connector, and the second sub-extension portion can be independently connected to an external circuit through a second connector. The movable ranges of the first sub-extension portion and the second sub-extension portion are not restricted by each other, and each can be flexibly connected to an external circuit, with a large movable range. Moreover, since the first sub-extension portion and the second sub-extension portion both extend from the same position of the main body, the space occupied by the flexible circuit board can be saved, and thus the overall space of the electronic product to which the flexible circuit board of the embodiment of the present disclosure is applied can be saved, which is conducive to achieving lightweight electronic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings are used to provide a further understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure. The shapes and sizes of the components in the accompanying drawings do not reflect the actual proportions and are only intended to illustrate the contents of the present disclosure.

[0008] Figure 1 Schematic diagram of a planar structure of a flexible circuit board according to some exemplary embodiments;

[0009] Figure 2 In some exemplary embodiments Figure 1 AA cross-sectional structural diagram of a flexible circuit board;

[0010] Figure 3a for Figure 1 A schematic plan view of the second composite structure layer of the flexible circuit board;

[0011] Figure 3b for Figure 1 A schematic diagram of the planar structure of a connection layer of a flexible circuit board;

[0012] Figure 3c for Figure 1 A schematic diagram of the planar structure of the first composite structure layer of the flexible circuit board;

[0013] Figure 4 Schematic diagrams of planar structures of flexible circuit boards of other exemplary embodiments;

[0014] Figure 5 for Figure 4 A schematic diagram of the planar structure of the first composite structure layer of the flexible circuit board;

[0015] Figure 6Schematic diagrams of planar structures of flexible circuit boards according to some further exemplary embodiments;

[0016] Figure 7 In some exemplary embodiments Figure 6 BB cross-sectional structural diagram of a flexible circuit board;

[0017] Figure 8a for Figure 6 A schematic plan view of the structure of a second double-layer board of a second composite structure layer of a flexible circuit board;

[0018] Figure 8b for Figure 6 A schematic plan view of the structure of a connecting layer of a flexible circuit board, a first single-layer board of a first composite structure layer, and a second single-layer board of a second composite structure layer;

[0019] Figure 8c for Figure 6 A schematic plan view of the structure of a first double-layer board of a first composite structure layer of a flexible circuit board;

[0020] Fig. 9 Schematic diagram of a partial structure of a display device according to some exemplary embodiments.

[0021] The accompanying drawings are marked as follows:

[0022] 10. Main body, 20. Extension, 21. First sub-extension, 22. Second sub-extension, 31. First connector, 32. Second connector, 41. First composite structure layer, 42. Second composite structure layer, 43. Connection layer,

[0023] 211, first extension section, 212, second extension section, 2121, transition section, 2122, tail section,

[0024] 411, a first single-layer board, 412, a first double-layer board, 413, a first adhesive layer,

[0025] 421, second single-layer board, 422, second double-layer board, 423, second adhesive layer,

[0026] 100. Display panel; 200. Flexible circuit board; 300. Opening of the middle frame assembly. DETAILED DESCRIPTION

[0027] Those skilled in the art should understand that the technical solutions of the embodiments of the present disclosure may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and all should be included in the scope of the claims of the present disclosure.

[0028] The present disclosure provides a flexible circuit board. In some exemplary embodiments, Figure 1 and Figure 2 As shown, Figure 1 is a schematic diagram of a planar structure of a flexible circuit board according to some exemplary embodiments, Figure 2 In some exemplary embodiments Figure 1 The AA cross-sectional structural schematic diagram of a flexible circuit board is shown, wherein the flexible circuit board includes a main body 10 and an extension portion 20 located on one side of the main body 10; the main body 10 is provided with a plurality of electronic components, and the extension portion 20 includes a first sub-extension portion 21 and a second sub-extension portion 22 which are at least partially overlapped and not connected, and the first sub-extension portion 21 and the second sub-extension portion 22 can be independently bent in different directions; an end of the first sub-extension portion 21 close to the main body 10 and an end of the second sub-extension portion 22 close to the main body 10 are connected to the same position of the main body 10, an end of the first sub-extension portion 21 away from the main body 10 is provided with a first connector 31, and an end of the second sub-extension portion 22 away from the main body 10 is provided with a second connector 32.

[0029] The flexible circuit board of the embodiment of the present disclosure extends a first sub-extension portion 21 and a second sub-extension portion 22 that are at least partially overlapped and unconnected from the same position of the main body 10. The first sub-extension portion 21 and the second sub-extension portion 22 can be independently bent in different directions. In this way, the first sub-extension portion 21 can be independently connected to an external circuit through a first connector 31, and the second sub-extension portion 22 can be independently connected to an external circuit through a second connector 32. The movable ranges of the first sub-extension portion 21 and the second sub-extension portion 22 are not restricted by each other, and each can be flexibly connected to an external circuit with a large movable range. Moreover, since the first sub-extension portion 21 and the second sub-extension portion 22 both extend from the same position of the main body 10, the space occupied by the flexible circuit board can be saved, and then the space of the entire electronic product to which the flexible circuit board of the embodiment of the present disclosure is applied can be saved, which is conducive to achieving lightweight electronic products.

[0030] In the flexible circuit board of the embodiment of the present disclosure, a plane parallel to the flexible circuit board is used as a reference plane, and an orthographic projection of the first sub-extension portion in the reference plane and an orthographic projection of the second sub-extension portion in the reference plane have an overlapping area. The shape of the first sub-extension portion and the shape of the second sub-extension portion may be the same or different.

[0031] In some exemplary embodiments, Figure 2As shown, the first sub-extension 21 includes one or more circuit layers, and the second sub-extension 22 includes one or more circuit layers. The number of circuit layers of the first sub-extension 21 and the number of circuit layers of the second sub-extension 22 may be the same or different. The main body 10 includes a plurality of circuit layers, and the number of circuit layers of the main body 10 may be unlimited and may be set according to actual needs, such as four layers, six layers or more layers. The number of circuit layers of the main body 10 is greater than or equal to the number of circuit layers of the extension 20.

[0032] The main body 10 may be an electronic component area, and the extension 20 may be a signal line outlet area. The circuit layers of the first sub-extension 21 and the second sub-extension 22 may both include a plurality of leads, and the plurality of leads of the first sub-extension 21 are led out from the main body 10 and connected to the first connector 31, and the plurality of leads of the second sub-extension 22 are led out from the main body 10 and connected to the second connector 32. Through the first sub-extension 21 and the second sub-extension 22, the leads of the flexible circuit board can be led out from the same position of the main body 10 and divided into two groups, which are respectively connected to the first connector 31 and the second connector 32.

[0033] In some exemplary embodiments, Figure 2 As shown, the flexible circuit board includes a first composite structure layer 41 and a second composite structure layer 42 stacked together, and a connecting layer 43 bonded between the first composite structure layer 41 and the second composite structure layer 42; at least a portion of the film layer of the first composite structure layer 41 extends from the main body 10 to the extension portion 20, and the portion of the first composite structure layer 41 located in the extension portion 20 forms the first sub-extension portion 21; at least a portion of the film layer of the second composite structure layer 42 extends from the main body 10 to the extension portion 20, and the portion of the second composite structure layer 42 located in the extension portion 20 forms the second sub-extension portion 22.

[0034] For example, Figure 2 As shown, the first composite structure layer 41 and the second composite structure layer 42 may both include multiple circuit layers. The first composite structure layer 41 and the second composite structure layer 42 may both be double-layer boards, the double-layer boards including a substrate, two circuit layers respectively arranged on both sides of the substrate, and two covering layers respectively covering the two circuit layers. The materials of the substrate and the covering layers may be polyimide (PI), polyethylene terephthalate (PET), etc., and the material of the circuit layer may be copper, etc. The connecting layer 43 may be a film material such as PI or PET with adhesive on both sides. The first composite structure layer 41 and the second composite structure layer 42 are pressed and bonded together by the connecting layer 43.

[0035] Figure 2 In the example, the film layer structure of the first sub-extension portion 21 is the same as the film layer structure of the first composite structure layer 41, and the film layer structure of the second sub-extension portion 22 is the same as the film layer structure of the second composite structure layer 42. The number of layers of the circuit layer of the main body 10 is equal to the number of layers of the circuit layer of the extension portion 20.

[0036] For example, Figure 2 As shown, the portion of the first composite structure layer 41 located at the main body 10 is bonded to the portion of the second composite structure layer 42 located at the main body 10 via the connection layer 43. The portion of the first composite structure layer 41 located at the extension portion 20 (i.e., the first sub-extension portion 21) is not connected to the portion of the second composite structure layer 42 located at the extension portion 20 (i.e., the second sub-extension portion 22), that is, the extension portion 20 is not provided with the connection layer 43.

[0037] For example, Figure 1 , Figure 3a , Figure 3b and Figure 3c As shown, Figure 3a for Figure 1 A schematic diagram of the planar structure of the second composite structure layer of the flexible circuit board, Figure 3b for Figure 1 Schematic diagram of the planar structure of the connection layer of the flexible circuit board, Figure 3c for Figure 1 Schematic diagram of the planar structure of the first composite structure layer of the flexible circuit board, the shape of the portion of the first composite structure layer 41 located at the main body 10, the portion of the second composite structure layer 42 located at the main body 10 and the connecting layer 43 can be the same. The first composite structure layer 41 and the second composite structure layer 42 are pressed and bonded together by the connecting layer 43. The portion of the first composite structure layer 41 located at the extension portion 20 forms the first sub-extension portion 21, and the portion of the second composite structure layer 42 located at the extension portion 20 forms the second sub-extension portion 22.

[0038] In some exemplary embodiments, Figure 1 As shown, the first sub-extension portion 21 and the second sub-extension portion 22 may extend along the same straight line direction.

[0039] Exemplarily, the shapes of the first sub-extension 21 and the second sub-extension 22 may both be rectangular. The length of one of the first sub-extension 21 and the second sub-extension 22 may be greater than the length of the other, or the lengths of the first sub-extension 21 and the second sub-extension 22 may be the same. The widths of the first sub-extension 21 and the second sub-extension 22 may be the same or different. Taking a plane parallel to the flexible circuit board as a reference plane, the orthographic projection of one of the first sub-extension 21 and the second sub-extension 22 in the reference plane may include the orthographic projection of the other in the reference plane. The first connector 31 and the second connector 32 may be arranged on the same surface of the flexible circuit board.

[0040] In some exemplary embodiments, the first sub-extension portion may include a first extension segment connected to the main body portion and a second extension segment connected to the first extension segment; the first extension segment and the second sub-extension portion may extend along the same straight line direction, and the second extension segment is located on one side of the first extension segment.

[0041] In an example of this embodiment, Figure 4 and Figure 5 As shown, Figure 4 Schematic diagrams of planar structures of flexible circuit boards of other exemplary embodiments. Figure 5 for Figure 4 A schematic planar structural diagram of the first composite structural layer of a flexible circuit board, wherein the first sub-extension portion 21 may include a first extension segment 211 connected to the main body portion 10 and a second extension segment 212 connected to the first extension segment 211; the first extension segment 211 and the second sub-extension portion 22 extend along the same straight line direction, and the second extension segment 212 is located on one side of the first extension segment 211. Exemplarily, the second extension segment 212 may include a transition segment 2121 connected to the first extension segment 211 and a tail segment 2122 connected to the transition segment 2121, and the extension direction of the tail segment 2122 may be parallel to the extension direction of the first extension segment 211. The tail segment 2122 extends in a direction away from the main body portion 10. The first connector 31 is disposed at one end of the tail segment 2122 away from the main body portion 10. As shown in FIG. Figure 4 As shown, the first connector 31 and the second connector 31 can be respectively arranged on the two sides of the flexible circuit board. When the flexible circuit board is in use, the first sub-extension portion 21 can be bent around the bending axis M passing through the transition section 2121 to bend the tail section 2122 to overlap with the first extension section 211, so that Figure 4 The shape of the flexible circuit board can be realized as follows: Figure 1The shape of the flexible circuit board is the same as that of the flexible circuit board, and can be applied to electronic products that have strict restrictions on the shape of the flexible circuit board. The structure of the second composite structure layer 42 and the connecting layer 43 of the flexible circuit board in this example can be the same as that of the flexible circuit board. Figure 1 The second composite structure layer 42 and the connection layer 43 of the flexible circuit board of the example have the same structure.

[0042] In another example of this embodiment, Figure 6 As shown, Figure 6 The planar structure diagram of the flexible circuit board of some other exemplary embodiments is shown in the figure. The first sub-extension portion 21 may include a first extension segment 211 connected to the main body 10 and a second extension segment 212 connected to the first extension segment 211; the first extension segment 211 and the second sub-extension portion 22 extend in the same straight line direction, and the second extension segment 212 is perpendicular to the first extension segment 211. The first connector 31 is arranged at an end of the second extension segment 212 away from the first extension segment 211. In this example, the first connector 31 and the second connector 31 may be arranged on the same surface of the flexible circuit board.

[0043] In some exemplary embodiments, Figure 7 As shown, Figure 7 In some exemplary embodiments Figure 6 The BB cross-sectional structure schematic diagram of a flexible circuit board is shown, wherein the flexible circuit board includes a first composite structure layer 41 and a second composite structure layer 42 stacked together, and a connecting layer 43 bonded between the first composite structure layer 41 and the second composite structure layer 42; at least a portion of the film layer of the first composite structure layer 41 extends from the main body 10 to the extension portion 20, and a portion of the first composite structure layer 41 located in the extension portion 20 forms the first sub-extension portion 21; at least a portion of the film layer of the second composite structure layer 42 extends from the main body 10 to the extension portion 20, and a portion of the second composite structure layer 42 located in the extension portion 20 forms the second sub-extension portion 22.

[0044] For example, Figure 7As shown, the first composite structure layer 41 and the second composite structure layer 42 may both include multiple circuit layers. The first composite structure layer 41 includes a first single-layer board 411 and a first double-layer board 412 stacked together, and the first single-layer board 411 and the first double-layer board 412 are bonded together by a first adhesive layer 413. The second composite structure layer 42 includes a second single-layer board 421 and a second double-layer board 422 stacked together, and the second single-layer board 421 and the second double-layer board 422 are bonded together by a second adhesive layer 423. The first single-layer board 411 and the second single-layer board 421 both include a substrate, a circuit layer provided on one side of the substrate, and a covering layer covering the circuit layer. The first double-layer board 412 and the second double-layer board 422 both include a substrate, two circuit layers respectively provided on both sides of the substrate, and two covering layers respectively covering the two circuit layers. The materials of the substrate and the cover layer in the single-layer board and the double-layer board can be polyimide (PI), polyethylene terephthalate (PET), etc., and the material of the circuit layer can be copper, etc. The connecting layer 43 can be a film material such as PI or PET with adhesive on both sides. The first composite structure layer 41 and the second composite structure layer 42 are pressed and bonded together by the connecting layer 43, and the connecting layer 43 is bonded between the first double-layer board 412 of the first composite structure layer 41 and the second double-layer board 422 of the second composite structure layer 42.

[0045] Figure 7 In the example of , the first double-layer board 412 of the first composite structure layer 41 extends from the main body 10 to the extension 20 and forms a first sub-extension 21, and the film structure of the first sub-extension 21 is the same as the film structure of the first double-layer board 412. The second double-layer board 422 of the second composite structure layer 42 extends from the main body 10 to the extension 20 and forms a second sub-extension 22, and the film structure of the second sub-extension 22 is the same as the film structure of the second double-layer board 422. The first single-layer board 411 of the first composite structure layer 41 and the second single-layer board 421 of the second composite structure layer 42 are both located in the main body 10 and do not extend to the extension 20. The number of layers of the circuit layer of the main body 10 is six, and the number of layers of the circuit layer of the extension 20 is four, wherein the number of layers of the circuit layer of the first sub-extension 21 and the second sub-extension 22 are both two, and the number of layers of the circuit layer of the main body 10 is greater than the number of layers of the circuit layer of the extension 20.

[0046] For example, Figure 7As shown, the portion of the first composite structure layer 41 located at the main body 10 is bonded to the portion of the second composite structure layer 42 located at the main body 10 via the connection layer 43. The portion of the first composite structure layer 41 located at the extension portion 20 (i.e., the first sub-extension portion 21) is not connected to the portion of the second composite structure layer 42 located at the extension portion 20 (i.e., the second sub-extension portion 22), that is, the extension portion 20 is not provided with the connection layer 43.

[0047] For example, Figure 6 , Figure 8a , Figure 8b and Figure 8c As shown, Figure 8a for Figure 6 A schematic diagram of the planar structure of the second double-layer board of the second composite structure layer of the flexible circuit board, Figure 8b for Figure 6 A schematic diagram of the planar structure of the connecting layer of the flexible circuit board, the first single-layer board of the first composite structure layer, and the second single-layer board of the second composite structure layer, Figure 8c for Figure 6 Schematic diagram of the planar structure of the first double-layer board of the first composite structure layer of the flexible circuit board. The shapes of the connecting layer 43, the first single-layer board 411 of the first composite structure layer 41, and the second single-layer board 421 of the second composite structure layer 42 can be the same. The shapes of the portion of the first double-layer board 412 of the first composite structure layer 41 located at the main body 10, the portion of the second double-layer board 422 of the second composite structure layer 42 located at the main body 10, and the connecting layer 43 can be the same. The portion of the first double-layer board 412 of the first composite structure layer 41 located at the main body 10 and the portion of the second double-layer board 422 of the second composite structure layer 42 located at the main body 10 are pressed and bonded together by the connecting layer 43. The portion of the first double-layer board 412 of the first composite structure layer 41 located at the extension 20 forms the first sub-extension 21, and the portion of the second double-layer board 422 of the second composite structure layer 42 located at the extension 20 forms the second sub-extension 22.

[0048] The embodiment of the present disclosure further provides a display device, including a display module, wherein the display module includes a display panel and a flexible circuit board as described in any embodiment bound and connected to the display panel.

[0049] For example, Fig. 9 As shown, Fig. 9The schematic diagram of the partial structure of a display device of some exemplary embodiments, the display device includes a display module, the display module includes a display panel 100 and a flexible circuit board 200 described in any embodiment bound and connected to the display panel 100; the display device also includes a middle frame assembly arranged on the side of the display module away from the display side, and a control circuit board arranged on the side of the middle frame assembly away from the display module; the flexible circuit board 200 is bent to the side of the display panel 100 away from the display side, and the ends of the first sub-extension 21 and the second sub-extension 22 away from the main body 10 are passed through the same opening 300 provided on the middle frame assembly and connected to the control circuit board. Exemplarily, the display device can be a touch display device, and the flexible circuit board can integrate display circuits and touch circuits. In this example, the first sub-extension portion 21 and the second sub-extension portion 22 of the flexible circuit board 200 extend from the same position of the main body portion 10 of the flexible circuit board and can move freely and independently. Therefore, the first sub-extension portion 21 and the second sub-extension portion 22 can pass through the same opening 300 provided on the middle frame assembly and be connected to different positions of the control circuit board, which can save the space reserved for the flexible circuit board 200 of the whole machine and facilitate the lightweighting of electronic products.

[0050] The display device of the embodiment of the present disclosure may be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, or the like.

[0051] In the drawings, the size of the components, the thickness of the layers, or the regions are sometimes exaggerated for the sake of clarity. Therefore, the embodiments of the present disclosure are not necessarily limited to the dimensions, and the shape and size of each component in the drawings do not reflect the true proportions. In addition, the drawings schematically show some examples, and the embodiments of the present disclosure are not limited to the shapes or values ​​shown in the drawings.

[0052] In the description of this article, "parallel" refers to a state where the angle formed by two straight lines is greater than -10° and less than 10°, and therefore includes a state where the angle is greater than -5° and less than 5°. In addition, "perpendicular" refers to a state where the angle formed by two straight lines is greater than 80° and less than 100°, and therefore includes a state where the angle is greater than 85° and less than 95°.

[0053] In the description herein, the terms "upper", "lower", "left", "right", "top", "inside", "outside", "axial", "four corners", etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are merely simplified descriptions for the convenience of describing the embodiments of the present disclosure, rather than indicating or implying that the referred structure has a specific orientation, is constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0054] In the description herein, unless otherwise clearly specified and limited, the terms "connection", "fixed connection", "installation", and "assembly" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection; the terms "installation", "connection", and "fixed connection" can be a direct connection, or an indirect connection through an intermediate medium, or the internal communication of two elements. For ordinary technicians in this field, the meanings of the above terms in the embodiments of the present disclosure can be understood according to the circumstances.

Claims

1. A flexible circuit board, characterized in that: The device comprises a main body and an extension portion located on one side of the main body; the main body is provided with a plurality of electronic components, the extension portion comprises a first sub-extension portion and a second sub-extension portion which are at least partially overlapped and not connected, and the first sub-extension portion and the second sub-extension portion can be independently bent in different directions; One end of the first sub-extension portion close to the main body portion and one end of the second sub-extension portion close to the main body portion are connected to the same position of the main body portion, one end of the first sub-extension portion away from the main body portion is provided with a first connector, and one end of the second sub-extension portion away from the main body portion is provided with a second connector.

2. The flexible circuit board according to claim 1, characterized in that: The first sub-extension portion and the second sub-extension portion extend along the same straight line direction.

3. The flexible circuit board according to claim 2, wherein: A length of one of the first sub-extension portion and the second sub-extension portion is greater than a length of the other.

4. The flexible circuit board according to claim 1, wherein: The first sub-extension portion includes a first extension segment connected to the main body portion and a second extension segment connected to the first extension segment; the first extension segment and the second sub-extension portion extend along the same straight line direction, and the second extension segment is located on one side of the first extension segment.

5. The flexible circuit board according to claim 4, characterized in that: The second extension section is perpendicular to the first extension section; or, the second extension section includes a transition section connected to the first extension section and a tail section connected to the transition section, and an extension direction of the tail section is parallel to an extension direction of the first extension section.

6. The flexible circuit board according to claim 1, wherein: The first sub-extension portion includes one or more circuit layers, and the second sub-extension portion includes one or more circuit layers.

7. The flexible circuit board according to claim 6, characterized in that: The main body includes a plurality of circuit layers, and the number of circuit layers of the main body is greater than or equal to the number of circuit layers of the extension part.

8. The flexible circuit board according to claim 1, wherein: The flexible circuit board includes a first composite structure layer and a second composite structure layer stacked together, and a connection layer bonded between the first composite structure layer and the second composite structure layer; At least a portion of the film layer of the first composite structural layer extends from the main body to the extension portion, and the portion of the first composite structural layer located in the extension portion forms the first sub-extension portion; at least a portion of the film layer of the second composite structural layer extends from the main body to the extension portion, and the portion of the second composite structural layer located in the extension portion forms the second sub-extension portion.

9. The flexible circuit board according to claim 8, characterized in that: A portion of the first composite structure layer located in the main body portion, a portion of the second composite structure layer located in the main body portion, and the connection layer have the same shape.

10. The flexible circuit board according to claim 8, characterized in that: The first composite structure layer and the second composite structure layer both include a plurality of circuit layers.

11. A display device, comprising a display module, characterized in that: The display module comprises a display panel and a flexible circuit board according to any one of claims 1 to 10 which is bound and connected to the display panel.

12. The display device according to claim 11, characterized in that: It also includes a middle frame assembly disposed on a side of the display module away from the display side, and a control circuit board disposed on a side of the middle frame assembly away from the display module; The flexible circuit board is bent to a side of the display panel away from the display side, and ends of the first sub-extension portion and the second sub-extension portion away from the main body portion pass through the same opening provided on the middle frame assembly and are connected to the control circuit board.

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