Flexible circuit board and display device comprising same
By setting a grid-shaped reinforcement layer in the flexible circuit board, the problem of thermal expansion and contraction when the flexible circuit board is bound to the printed circuit board is solved, a high-yield and stable connection is achieved, and poor binding and peeling are avoided.
Patent Information
- Application Number
- CN202422776228.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-13
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-11-13
AI Technical Summary
When the flexible circuit board is bound to the printed circuit board, the thermal expansion and contraction caused by temperature changes may lead to poor binding and affect the use effect.
A flexible circuit board is designed with a length greater than or equal to 60 mm, comprising a substrate, a metal routing layer, an insulating layer, and a reinforcement layer. At least one of the layers has a grid structure, and the reinforcement layer is used to reduce stress. The flexible circuit board is bonded using anisotropic conductive film.
Effectively reduce stress, improve connection yield after binding, avoid peeling problems, and improve product stability and yield.
Smart Images
Figure CN223334840U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electronic circuits, and in particular to a flexible circuit board and a display device containing the same. Background Art
[0002] Flexible Printed Circuit (FPC) is usually used to connect a display panel and a printed circuit board (PCB) and perform signal transmission.
[0003] There are temperature changes during the binding connection process between the flexible circuit board and the printed circuit board, and the printed circuit board is prone to obvious thermal expansion and contraction during this process, causing the flexible circuit board to be continuously subjected to stress during the pressing process, resulting in poor binding between the flexible circuit board and the printed circuit board, which in turn affects subsequent use. Utility Model Content
[0004] The embodiments of the present application provide a flexible circuit board and a display device including the same, so as to solve the problem in the related art that a flexible circuit board is prone to poor connection after being bound to a printed circuit board.
[0005] On the one hand, an embodiment of the present application provides a flexible circuit board, the length of which is greater than or equal to 60 mm, the flexible circuit board including a substrate, a first metal routing layer, a first insulating layer, and a first reinforcement layer located on one side of the substrate and arranged in sequence, and a second metal routing layer, a second insulating layer, and a second reinforcement layer located on the other side of the substrate and arranged in sequence; the first metal routing layer is located between the substrate and the first insulating layer, and the second metal routing layer is located between the substrate and the second insulating layer; at least one of the first reinforcement layer and the second reinforcement layer includes a plurality of first reinforcement metal wires arranged side by side and a plurality of second reinforcement metal wires arranged side by side, and the first reinforcement metal wires and the second reinforcement metal wires are cross-connected to form a grid structure.
[0006] In some embodiments, both the first reinforcement layer and the second reinforcement layer include the grid-like structure.
[0007] In some embodiments, the first metal trace layer includes a plurality of first metal traces arranged in parallel and spaced apart from each other, the second metal trace layer includes a plurality of second metal traces arranged in parallel and spaced apart from each other, the extension direction of the first metal trace is parallel to the extension direction of the second metal trace, and the extension direction of the first metal trace intersects with the length direction of the flexible circuit board.
[0008] In some embodiments, at least one of the first metal routing and the second metal routing includes a plurality of first sub-metal lines arranged side by side and a plurality of second sub-metal lines arranged side by side, and the first sub-metal lines and the second sub-metal lines are cross-connected.
[0009] In some embodiments, the flexible circuit board further includes a first protection layer located on a side of the first reinforcement layer facing away from the substrate and covering the first reinforcement layer.
[0010] In some embodiments, the flexible circuit board further includes a second protection layer located on a side of the second reinforcement layer facing away from the substrate and covering the second reinforcement layer.
[0011] Some embodiments of the present application also provide a flexible circuit board, the length of which is greater than or equal to 60 mm, and the flexible circuit board includes: a substrate, a first metal routing layer and a first protective layer located on one side of the substrate and arranged in sequence; the first metal routing layer is located between the substrate and the first protective layer, and the first protective layer covers the first metal routing layer.
[0012] In some embodiments, the flexible circuit board further includes a surface covering layer located between the first metal trace layer and the first protective layer, the surface covering layer covers the first metal trace layer, and a material of the surface covering layer includes at least one of nickel and gold.
[0013] Some embodiments of the present application also provide a display device, which includes a printed circuit board, a display panel, and a flexible circuit board as described in any of the above embodiments, wherein the display panel is provided with a solder pad, the printed circuit board is provided with a binding terminal, and the flexible circuit board is respectively connected to the solder pad and the binding terminal.
[0014] In some embodiments, there are multiple flexible circuit boards, and the multiple flexible circuit boards are arranged at intervals.
[0015] For the flexible circuit board provided in the embodiment of the present application, since its length is greater than or equal to 60 mm, a larger binding area is provided between the flexible circuit board and the printed circuit board. However, during the binding process between the flexible circuit board and the printed circuit board, the printed circuit board has significant thermal expansion and contraction, which causes the flexible circuit board to be continuously subjected to large stress during the pressing process. However, since the flexible circuit board in the present application is provided with a grid structure in at least one of the first reinforcement layer and the second reinforcement layer, the stress on the flexible circuit board can be effectively reduced, so that the flexible circuit board can effectively adapt to the thermal expansion and contraction of the printed circuit board to ensure the effective connection between the flexible circuit board and the printed circuit board after binding, thereby improving the product yield. In addition, the flexible circuit board and the printed circuit board are usually bound using anisotropic conductive film. Since the grid structure reduces the stress of the flexible circuit board itself, it can also effectively avoid the problem of peeling between the flexible circuit board and the anisotropic conductive film, thereby improving the stability of the product. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.
[0017] Figure 1 is a structural diagram of a display device provided in some embodiments of the present application;
[0018] Figure 2 is a cross-sectional view of a flexible circuit board provided in some embodiments of the present application;
[0019] Figure 3 is a structural diagram of a first reinforcement layer or a second reinforcement layer according to some embodiments of the present application;
[0020] Figure 4 is a structural diagram of a first metal routing layer or a second metal routing layer according to some embodiments of the present application;
[0021] Figure 5 is a cross-sectional view of a flexible circuit board provided in some other embodiments of the present application;
[0022] Figure 6 This is a cross-sectional view of another flexible circuit board provided in some embodiments of the present application. DETAILED DESCRIPTION
[0023] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. The described technical solutions are only used to explain and illustrate the ideas of the present application and should not be regarded as limiting the scope of protection of the present application.
[0024] In the description of this application, it should be understood that the terms "first," "second," and similar words do not indicate any order, quantity, or importance, but are simply used to distinguish different technical features. The term "plurality" and similar words mean two or more, unless otherwise expressly limited.
[0025] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.
[0026] The use of "suitable for" or "configured to" in this application is intended to be open and inclusive language, and does not exclude devices that are adapted or configured to perform additional tasks or steps. In addition, the use of "based on" is intended to be open and inclusive, as a process, step, calculation, or other action that is "based on" one or more stated conditions or values may, in practice, be based on additional conditions or values beyond those stated.
[0027] In this application, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is provided to enable any person skilled in the art to make and use the present application.
[0028] The various embodiments of the present application are similar, and features in different embodiments and / or different examples may be combined with each other.
[0029] Some embodiments of the present application provide a flexible circuit board 100, such as Figure 1 As shown, one end of the flexible circuit board 100 can be used to connect to the display panel 200, and the other end of the flexible circuit board 100 can be used to connect to the printed circuit board 300. The flexible circuit board 100 can realize the transmission of signals between the display panel 200 and the printed circuit board 300, so that the display panel 200 can display the picture.
[0030] The length L of the flexible circuit board 100 is greater than or equal to 60 mm. In this case, the flexible circuit board 100 is generally referred to as an extra-long flexible circuit board. Due to the relatively large length of the flexible circuit board 100, a relatively large bonding area can be provided between the flexible circuit board 100 and the printed circuit board 300.
[0031] like Figure 2As shown, the flexible circuit board 100 includes a substrate 10, a first metal trace layer 11, a first insulating layer 101, and a first reinforcement layer 12, which are sequentially arranged on one side of the substrate 10. The first metal trace layer 11 is located between the substrate 10 and the first insulating layer 101. In other words, the substrate 10, the first metal trace layer 11, the first insulating layer 101, and the first reinforcement layer 12 are stacked in sequence.
[0032] The flexible circuit board 100 further includes a second metal trace layer 13 , a second insulating layer 102 , and a second reinforcement layer 14 , which are sequentially arranged on the other side of the substrate 10 . The second metal trace layer 13 is located between the substrate 10 and the second insulating layer 102 .
[0033] Because the length of the flexible circuit board 100 is greater than or equal to 60 mm and the flexible circuit board 100 includes two metal trace layers (i.e., the first metal trace layer 11 and the second metal trace layer 13), this can easily cause warping at the edges of the flexible circuit board 100. By providing the first reinforcement layer 12 and the second reinforcement layer 14, the modulus of the flexible circuit board 100 can be increased to a higher level, thereby preventing warping at the edges of the flexible circuit board 100.
[0034] In this embodiment, if Figure 3 As shown, at least one of the first reinforcement layer 12 and the second reinforcement layer 14 includes a plurality of first reinforcement metal lines 121 and a plurality of second reinforcement metal lines 122 arranged side by side. The first reinforcement metal lines 121 and the second reinforcement metal lines 122 are cross-connected to form a grid structure.
[0035] It is worth noting that during the bonding process of the flexible circuit board 100 and the printed circuit board 300 , the printed circuit board 300 undergoes significant thermal expansion and contraction, which may easily cause the flexible circuit board 100 to be continuously subjected to high stress during the bonding process.
[0036] Because at least one of the first reinforcement layer 12 and the second reinforcement layer 14 in the present application is provided with a grid structure, this can effectively reduce the stress in the corresponding layer, allowing the flexible circuit board 100 to effectively adapt to the thermal expansion and contraction of the printed circuit board 300, thereby improving the effective connection between the flexible circuit board 100 and the printed circuit board 300 after bonding, thereby improving product yield. In addition, the flexible circuit board 100 and the printed circuit board 300 are typically bonded using anisotropic conductive film (ACF). Due to the grid structure, the stress of the flexible circuit board 100 itself is reduced. This can also effectively prevent the problem of peeling between the flexible circuit board 100 and the ACF, thereby improving product stability.
[0037] In some examples, the first reinforcement layer 12 includes a grid structure, that is, the first reinforcement layer 12 includes a plurality of first reinforcement metal lines 121 and a plurality of second reinforcement metal lines 122 arranged side by side, and the first reinforcement metal lines 121 and the second reinforcement metal lines 122 are cross-connected to form the grid structure.
[0038] In other examples, the second reinforcement layer 14 includes a grid structure, that is, the second reinforcement layer 14 includes a plurality of first reinforcement metal lines 121 and a plurality of second reinforcement metal lines 122 arranged side by side, and the first reinforcement metal lines 121 and the second reinforcement metal lines 122 are cross-connected to form the grid structure.
[0039] In yet other examples, the first reinforcement layer 12 and the second reinforcement layer 14 both include a grid-like structure.
[0040] In some examples, the first reinforcement layer 12 and the second reinforcement layer 14 can be made of the same material, which is beneficial for cost savings. For example, the first reinforcement layer 12 and the second reinforcement layer 14 can be made of copper. Optionally, the first reinforcement layer 12 and the second reinforcement layer 14 can be made using a copper electroplating process.
[0041] In some embodiments, as Figure 1 As shown, the first metal trace layer 11 includes a plurality of first metal traces 110 arranged in parallel and spaced apart from each other, and the second metal trace layer 13 includes a plurality of second metal traces 130 arranged in parallel and spaced apart from each other. The first metal traces 110 and the second metal traces 130 extend in parallel and intersect with the length direction of the flexible circuit board 100. For example, the extension direction of the first metal traces 110 and the length direction of the flexible circuit board 100 can be perpendicular to each other. In this case, the extension direction of the first metal traces 110 is parallel to the width direction of the flexible circuit board 100, which facilitates the connection between the metal traces and the display panel and the printed circuit board.
[0042] As an example, Figure 1 As shown, the first metal trace 110 and the second metal trace 130 both extend along the second direction Y, while the length direction of the flexible circuit board 100 is along the first direction X. The first direction X and the second direction Y are perpendicular to each other.
[0043] In some embodiments, as Figure 4As shown, at least one of the first metal routing layer 11 and the second metal routing layer 13 includes a plurality of first sub-metal lines arranged side by side and a plurality of second sub-metal lines arranged side by side, and the first sub-metal lines and the second sub-metal lines are cross-connected. The structures of the first sub-metal lines and the second sub-metal lines can be configured with reference to the structures of the first reinforcement metal lines 121 and the second reinforcement metal lines 122 described above. In other words, at least one of the first metal routing 110 and the second metal routing 130 includes a grid-like structure.
[0044] Since at least one of the first metal trace 110 and the second metal trace 130 is provided with a grid structure, the stress of the corresponding trace layer can be effectively reduced, so that the flexible circuit board 100 can effectively adapt to the thermal expansion and contraction of the printed circuit board 300, thereby improving the effective connection between the flexible circuit board 100 and the printed circuit board 300 after binding, thereby improving the product yield.
[0045] In some examples, the first metal trace 110 includes a grid structure. That is, the first metal trace 110 includes a plurality of first sub-metal lines arranged side by side and a plurality of second sub-metal lines arranged side by side, and the first sub-metal lines and the second sub-metal lines are cross-connected.
[0046] In some other examples, the second metal trace 130 includes a grid structure. That is, the second metal trace 130 includes a plurality of first sub-metal lines and a plurality of second sub-metal lines arranged side by side, and the first sub-metal lines and the second sub-metal lines are cross-connected.
[0047] In yet other examples, both the first metal trace 110 and the second metal trace 130 comprise a grid-like structure. In this case, since the first metal trace 110, the second metal trace 130, the first reinforcement layer 12, and the second reinforcement layer 14 all comprise a grid-like structure, the stress in the metal layer within the flexible circuit board 100 can be significantly reduced. This effectively improves the flexible circuit board 100's adaptability to the thermal expansion and contraction of the printed circuit board 300, thereby enhancing the effective bonding between the flexible circuit board 100 and the printed circuit board 300. Furthermore, since the first metal trace 110, the second metal trace 130, the first reinforcement layer 12, and the second reinforcement layer 14 all comprise a grid-like structure, the flexible circuit board 100 as a whole has a relatively reasonable modulus, thereby effectively preventing the flexible circuit board 100 from warping.
[0048] In some examples, the first metal trace layer 11 and the second metal trace layer 13 may be made of the same material, which is beneficial to cost saving. For example, the first metal trace layer 11 and the second metal trace layer 13 may be made of copper.
[0049] In some examples, all first metal traces 110 in the first metal trace layer 11 include a grid structure.
[0050] In some examples, all second metal traces 130 in the second metal trace layer 13 include a grid structure.
[0051] In some examples, the flexible circuit board 100 further includes gold fingers. Each first metal trace 110 is connected to a gold finger at both ends and is connected to the display panel 200 or the printed circuit board 300 through the gold fingers, thereby achieving transmission of different signals.
[0052] In some embodiments, substrate 10 may be a flexible substrate. By using a flexible substrate, the flexibility of flexible circuit board 100 can be effectively guaranteed, facilitating operations such as bending. Optionally, the material of substrate 10 includes one of epoxy resin, polypropylene, polyphenylene ether, polypropylene, polyimide, polyethylene terephthalate, and polyethylene naphthalate.
[0053] In some examples, the combined thickness of the first metal trace layer 11 and the first reinforcement layer 12 is less than the thickness of the substrate 10, which helps ensure the overall structural stability of the flexible circuit board 100. For example, the thickness of the substrate 10 can be 25 μm, and the combined thickness of the first metal trace layer 11 and the first reinforcement layer 12 can be 20 μm. As an alternative embodiment, the thickness of the first metal trace layer 11 is 12 μm, and the thickness of the first reinforcement layer 12 is 8 μm.
[0054] In some embodiments, as Figure 5 As shown, the flexible circuit board 100 further includes a first protective layer 21 located on the side of the first reinforcement layer 12 facing away from the substrate 10. The first protective layer 21 covers the first reinforcement layer 12 and the first metal trace layer 11 and protects both, thereby ensuring the working stability and service life of the first metal trace layer 11.
[0055] In some examples, the first protection layer 21 includes a first adhesive layer 211 and a first cover layer 212 . The first adhesive layer 211 is used to adhere the first cover layer 212 to the first reinforcement layer 12 , thereby protecting the first metal wiring layer 11 and the first reinforcement layer 12 .
[0056] Among them, the material of the first covering layer 212 can be consistent with the material of the substrate 10. For example, the material of the first covering layer 212 can be polyimide. In this way, on the one hand, it can achieve good protection of metal layers such as the first metal wiring layer 11, and on the other hand, it also has good flexibility to adapt to the bending requirements of the flexible circuit board 100.
[0057] In some embodiments, as Figure 5As shown, the flexible circuit board 100 further includes a second protective layer 22 located on the side of the second reinforcement layer 14 facing away from the substrate 10. The second protective layer 22 covers and protects the second reinforcement layer 14 and the second metal trace layer 13, thereby ensuring the working stability and service life of the second metal trace layer 13.
[0058] In some examples, the second protection layer 22 includes a second adhesive layer 221 and a second cover layer 222 . The second adhesive layer 221 is used to bond the second cover layer 222 to the second reinforcement layer 14 , thereby protecting the second reinforcement layer 14 and the second metal wiring layer 13 .
[0059] The material of the second covering layer 222 can be the same as that of the first covering layer 212, which is not limited in this application. In addition, for the first protective layer 21 or the second protective layer 22, the thickness of the adhesive layer can be 15 μm, and the thickness of the covering layer can be 12.5 μm.
[0060] Some embodiments of the present application also provide a flexible circuit board, such as Figure 6 As shown, the length of the flexible circuit board 100' is greater than or equal to 60 mm. The flexible circuit board 100' includes a substrate 10 and a first metal trace layer 11 and a first protective layer 21 located on one side of the substrate 10 and arranged in sequence. The first metal trace layer 11 is located between the substrate 10 and the first protective layer 21, and the first protective layer 21 covers the first metal trace layer 11.
[0061] Because the length of the flexible circuit board 100 is greater than or equal to 60 mm, a larger bonding area is provided between the flexible circuit board 100 and the printed circuit board. However, during the bonding process between the flexible circuit board 100 and the printed circuit board, the printed circuit board undergoes significant thermal expansion and contraction, resulting in the flexible circuit board 100 being continuously subjected to significant stress during the bonding process. Because the flexible circuit board 100 includes only one metal trace layer, the overall modulus of the flexible circuit board 100 is relatively low. Furthermore, because the flexible circuit board 100 lacks a reinforcement layer, the first metal trace layer 11 effectively adapts to the thermal expansion and contraction of the printed circuit board 300 during the bonding process, thereby improving the effective connection between the flexible circuit board 100 and the printed circuit board 300 after bonding, and thereby increasing product yield.
[0062] In some examples, the first metal trace layer 11 includes a plurality of first metal traces 110 spaced apart from each other. The first metal traces 110 are used to implement signal transmission between the display panel 200 and the printed circuit board 300 .
[0063] In some examples, the flexible circuit board 100 ′ further includes a second protective layer 22 located on the other side of the substrate 10 , and the second protective layer 22 covers the substrate 10 .
[0064] The structures of the first protective layer 21 and the second protective layer 22 may be set with reference to the structures of the first protective layer 21 and the second protective layer 22 in the flexible circuit board 100 , and will not be described in detail here.
[0065] In some embodiments, as Figure 6 As shown, the flexible circuit board 100 ′ further includes a surface covering layer 15 located between the first metal trace layer 11 and the first protection layer 21 . The surface covering layer 15 covers the first metal trace layer 11 , and the material of the surface covering layer 15 includes at least one of nickel and gold.
[0066] The first metal trace 110 in the first metal trace layer 11 is surface-treated by using at least one of nickel and gold as a surface covering layer 15. This can improve the wear resistance, corrosion resistance, and conductivity of the first metal trace 110, thereby improving the performance of the flexible circuit board 100 and extending its service life.
[0067] In some examples, the thickness of the surface covering layer 15 may be 4 μm, so as to ensure that the performance of the flexible circuit board 100 is improved while avoiding excessive cost increase due to excessive thickness.
[0068] For flexible circuit boards (FPCBs) greater than or equal to 60mm in length, the metal routing layers and reinforcement layers on both sides of the substrate contribute to their high modulus. During the bonding process between the FPCB and the PCB, the FPCB struggles to adapt to the significant thermal expansion and contraction of the PCB, resulting in a defect rate exceeding 50% (i.e., the PCB and FPCB fail to connect effectively).
[0069] As for the flexible circuit board provided in this application (for example Figure 2 and Figure 5 The flexible circuit board 100 shown and Figure 6 The flexible circuit board 100 ′ shown in the figure can achieve a yield rate of up to 100% after being bound to the printed circuit board 300. Therefore, when the flexible circuit board provided by the present application is used, the binding connection between the flexible circuit board and the printed circuit board 300 can be effectively guaranteed.
[0070] Some embodiments of the present application also provide a display device, such as Figure 1 As shown, the display device 1000 includes a display panel 200 , a printed circuit board 300 , and the flexible circuit board described in any one of the above embodiments. Figure 1Only the flexible circuit board 100 is used as an example. Of course, the display device 1000 may include a flexible circuit board 100 ′ to achieve signal transmission between the display panel 200 and the printed circuit board 300 .
[0071] Since the display device 1000 includes the flexible circuit board 100 (or the flexible circuit board 100 ′), the display device 1000 has all the technical effects of the flexible circuit board 100 (or the flexible circuit board 100 ′) described above, which will not be described in detail here.
[0072] In some examples, the display panel 200 is provided with pads, the printed circuit board 300 is provided with binding terminals, and the flexible circuit board 100 (or flexible circuit board 100 ′) is connected to the pads and binding terminals respectively, thereby realizing signal transmission between the display panel 200 and the printed circuit board 300.
[0073] In some embodiments, as Figure 1 As shown, there are multiple flexible circuit boards 100 (or flexible circuit boards 100'), and the multiple flexible circuit boards are arranged at intervals. Each flexible circuit board 100 (or flexible circuit board 100') is connected to a corresponding pad on the display panel 200 and a corresponding binding terminal on the printed circuit board 300. In this case, multiple flexible circuit boards can accommodate larger display panels 200, thereby meeting their stable signal transmission requirements.
[0074] The above is a detailed introduction to the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of the present application. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.
Claims
1. A flexible circuit board, characterized in that: The length of the flexible circuit board is greater than or equal to 60 mm, and the flexible circuit board comprises: substrate; a first metal routing layer, a first insulating layer, and a first reinforcement layer disposed on one side of the substrate and arranged in sequence, wherein the first metal routing layer is located between the substrate and the first insulating layer; and A second metal wiring layer, a second insulating layer and a second reinforcement layer are sequentially arranged on the other side of the substrate, wherein the second metal wiring layer is located between the substrate and the second insulating layer; wherein At least one of the first reinforcement layer and the second reinforcement layer includes a plurality of first reinforcement metal wires arranged side by side and a plurality of second reinforcement metal wires arranged side by side, and the first reinforcement metal wires and the second reinforcement metal wires are cross-connected to form a grid structure.
2. The flexible circuit board according to claim 1, wherein: The first reinforcement layer and the second reinforcement layer both include the grid structure.
3. The flexible circuit board according to claim 1, wherein: The first metal trace layer includes a plurality of first metal traces arranged in parallel and spaced apart from each other, and the second metal trace layer includes a plurality of second metal traces arranged in parallel and spaced apart from each other. The extension direction of the first metal trace is parallel to the extension direction of the second metal trace, and the extension direction of the first metal trace intersects with the length direction of the flexible circuit board.
4. The flexible circuit board according to claim 3, characterized in that: At least one of the first metal routing and the second metal routing includes a plurality of first sub-metal lines arranged side by side and a plurality of second sub-metal lines arranged side by side, and the first sub-metal lines and the second sub-metal lines are cross-connected.
5. The flexible circuit board according to any one of claims 1 to 4, characterized in that: The flexible circuit board further includes a first protection layer located on a side of the first reinforcement layer facing away from the substrate and covering the first reinforcement layer.
6. The flexible circuit board according to any one of claims 1 to 4, characterized in that: The flexible circuit board further includes a second protection layer located on a side of the second reinforcement layer facing away from the substrate and covering the second reinforcement layer.
7. A flexible circuit board, characterized in that: The length of the flexible circuit board is greater than or equal to 60 mm, and the flexible circuit board comprises: substrate; and A first metal routing layer and a first protective layer are located on one side of the substrate and are sequentially arranged, wherein the first metal routing layer is located between the substrate and the first protective layer, and the first protective layer covers the first metal routing layer.
8. The flexible circuit board according to claim 7, characterized in that: The flexible circuit board further includes a surface covering layer located between the first metal wiring layer and the first protective layer, the surface covering layer covers the first metal wiring layer, and the material of the surface covering layer includes at least one of nickel and gold.
9. A display device, characterized in that: It comprises a printed circuit board, a display panel and a flexible circuit board according to any one of claims 1 to 8, wherein the display panel is provided with a soldering pad, the printed circuit board is provided with a binding terminal, and the flexible circuit board is respectively connected to the soldering pad and the binding terminal.
10. The display device according to claim 9, wherein: There are multiple flexible circuit boards, and the multiple flexible circuit boards are arranged at intervals.