Flexible circuit board, preparation method, and display module

Abstract

A flexible circuit board, a preparation method, and a display module. In the flexible circuit board, a first flexible substrate comprises a touch driving chip, a first contact, a first touch signal trace, a second touch signal trace, a display signal trace, and a binding structure, wherein the first touch signal trace, the second touch signal trace and the display signal trace are all electrically connected to the binding structure, the first touch signal trace is electrically connected to the touch driving chip, and the second touch signal trace is electrically connected to the first contact. A second flexible substrate is connected to the side of the first flexible substrate close to the touch driving chip, and the second flexible substrate is bent relative to the first flexible substrate and mated to the first flexible substrate. The second flexible substrate comprises a second contact and a third touch signal trace, the third touch signal trace is electrically connected to the second contact and the touch driving chip respectively, and the second contact is electrically connected to the first contact. The present application can reduce mutual interference between a display signal trace and a touch signal trace.

Description

Flexible circuit board, preparation method and display module

[0001] The present application claims priority from the Chinese patent application No. 202410693571.1 filed on May 30, 2024, and entitled "Flexible circuit board, preparation method and display module", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a flexible circuit board, a preparation method and a display module. BACKGROUND

[0003] The flexible multi-layer on cell (FMLOC) display device generally includes a display module, a touch module and a flexible circuit board, the flexible circuit board is electrically connected with the display module and the touch module respectively, so as to transmit signals to the display module and the touch module respectively. SUMMARY

[0004] The present application provides a flexible circuit board, a preparation method and a display module.

[0005] In a first aspect, the present application provides a flexible circuit board, comprising a first flexible substrate and a second flexible substrate;

[0006] The first flexible substrate comprises a touch driving chip, a first contact, a first touch signal trace, a second touch signal trace, a display signal trace and a binding structure, the binding structure is distributed along a first direction, in the first direction, the touch driving chip is close to a first end of the binding structure, the first contact is close to a second end of the binding structure, the first touch signal trace, the second touch signal trace and the display signal trace are all electrically connected with the binding structure, and the first touch signal trace is electrically connected with the touch driving chip, the second touch signal trace is electrically connected with the first contact, the first touch signal trace and the second touch signal trace are located in the same layer, and the first touch signal trace and the display signal trace are located in different layers;

[0007] The second flexible substrate is connected with the side of the first flexible substrate close to the touch driving chip, the second flexible substrate is folded relative to the first flexible substrate and is opposite to the first flexible substrate, the second flexible substrate comprises a second contact and a third touch signal trace, the third touch signal trace is electrically connected with the second contact, and the third touch signal trace is electrically connected with the touch driving chip, and the second contact is electrically connected with the first contact.

[0008] Thus, in the present application, the touch control driving chip can provide touch control driving signals to the first end of the binding structure through the first touch control signal trace, and provide touch control driving signals to the second end of the binding structure through the third touch control signal trace and the second touch control signal trace.

[0009] In an alternative technical solution of the above flexible circuit board, the first flexible substrate further comprises a fourth touch control signal trace, the fourth touch control signal trace is located in the same layer as the first touch control signal trace, the fourth touch control signal trace is electrically connected with the touch control driving chip, and the fourth touch control signal trace is electrically connected with the third touch control signal trace, and the third touch control signal trace is electrically connected with the touch control driving chip through the fourth touch control signal trace.

[0010] In an alternative technical solution of the above flexible circuit board, the first flexible substrate further comprises a first touch control connector electrically connected with the first contact, the second flexible substrate further comprises a second touch control connector electrically connected with the second contact, the first touch control connector and the second touch control connector are plug-in matched and electrically connected, and the second contact and the first contact are electrically connected through the second touch control connector and the first touch control connector.

[0011] In an alternative technical solution of the above flexible circuit board, the flexible circuit board further comprises an anisotropic conductive adhesive between the first contact and the second contact, and the second contact and the first contact are electrically connected through the anisotropic conductive adhesive.

[0012] In an alternative technical solution of the above flexible circuit board, the first flexible substrate or the second flexible substrate comprises a positioning mark, and the positioning mark is used for positioning the anisotropic conductive adhesive during the folding of the second flexible substrate and the first flexible substrate.

[0013] In an alternative technical solution of the above flexible circuit board, the flexible circuit board further comprises an externally supplied signal connector, the externally supplied signal connector is electrically connected with the first flexible substrate, and the externally supplied signal connector is used for providing external signals to the display signal trace and the touch control driving chip respectively.

[0014] In an alternative technical solution of the above flexible circuit board, the externally supplied signal connector is located on the side of the first flexible substrate close to the first contact.

[0015] In an alternative technical solution of the above flexible circuit board, the externally supplied signal connector and the binding structure are located on opposite sides of the first flexible substrate.

[0016] In an alternative of the flexible circuit board, the external signal connector is located on the first flexible substrate close to the touch driving chip.

[0017] In an alternative of the flexible circuit board, the first flexible substrate further comprises a first substrate, a first dielectric layer, a second dielectric layer, a first electromagnetic shielding layer and a second electromagnetic shielding layer, the first dielectric layer and the second dielectric layer are located on two sides of the first substrate, the first electromagnetic shielding layer is located on a side of the first dielectric layer away from the first substrate, the second electromagnetic shielding layer is located on a side of the second dielectric layer away from the first substrate, the first touch signal trace and the second touch signal trace are both located between the first substrate and the first dielectric layer, and the display signal trace is located between the first substrate and the second dielectric layer.

[0018] In an alternative of the flexible circuit board, the second flexible substrate further comprises a second substrate, a third dielectric layer and a third electromagnetic shielding layer, the second substrate, the third dielectric layer and the third electromagnetic shielding layer are stacked in sequence, and the third touch signal trace is located between the second substrate and the third dielectric layer.

[0019] In an alternative of the flexible circuit board, the second flexible substrate comprises a plurality of third touch signal traces, and the plurality of third touch signal traces are arranged at intervals between the second substrate and the third dielectric layer.

[0020] In an alternative of the flexible circuit board, the second flexible substrate further comprises a second substrate, a third dielectric layer, a fourth dielectric layer and a third electromagnetic shielding layer, the second substrate, the fourth dielectric layer, the third dielectric layer and the third electromagnetic shielding layer are stacked in sequence, the second flexible substrate comprises a plurality of third touch signal traces, at least one third touch signal trace is located between the second substrate and the fourth dielectric layer, and the rest of the third touch signal traces are located between the third dielectric layer and the fourth dielectric layer.

[0021] In an alternative of the flexible circuit board, the third touch signal traces located between the second substrate and the fourth dielectric layer and the third touch signal traces located between the third dielectric layer and the fourth dielectric layer are staggered.

[0022] In an alternative of the flexible circuit board, the first substrate and the second substrate are in an integrated structure; and / or, the third dielectric layer and the first dielectric layer are in an integrated structure; and / or, the third electromagnetic shielding layer and the first electromagnetic shielding layer are in an integrated structure.

[0023] In an optional technical solution of the flexible circuit board, the flexible circuit board further comprises an insulating adhesive layer between the second electromagnetic shielding layer and the second substrate, and the insulating adhesive layer is used to bond the second electromagnetic shielding layer and the second substrate.

[0024] In an optional technical solution of the flexible circuit board, the binding structure comprises a display pin, a first touch pin and a second touch pin.

[0025] The display signal wire is electrically connected with the display pin.

[0026] The first touch signal wire is electrically connected with the first touch pin.

[0027] The second touch signal wire is electrically connected with the second touch pin.

[0028] In a second aspect, a display module is provided, comprising a display panel, a display driving chip and the flexible circuit board provided in the first aspect and any optional technical solution thereof.

[0029] The display panel comprises a display module and a touch module, and the data line and the gate line in the display module are electrically connected with the display driving chip.

[0030] The display driving chip is electrically connected with the binding structure in the flexible circuit board.

[0031] Part of transmitter (TX) wires in the touch module are electrically connected with the first end of the binding structure, and another part of TX wires in the touch module are electrically connected with the second end of the binding structure.

[0032] Part of receiver (RX) wires in the touch module are electrically connected with the first end of the binding structure, and another part of RX wires in the touch module are electrically connected with the second end of the binding structure.

[0033] In an optional technical solution of the display module, the display module is an organic light-emitting diode (OLED) display module.

[0034] In a third aspect, a preparation method of a flexible circuit board is provided, comprising:

[0035] forming a first flexible substrate and a second flexible substrate; the first flexible substrate comprises a touch control driving chip, a first contact, a first touch control signal trace, a second touch control signal trace, a display signal trace and a binding structure, the binding structure is distributed along a first direction, in the first direction, the touch control driving chip is close to a first end of the binding structure, the first contact is close to a second end of the binding structure, the first touch control signal trace, the second touch control signal trace and the display signal trace are electrically connected with the binding structure, the first touch control signal trace is electrically connected with the touch control driving chip, the second touch control signal trace is electrically connected with the first contact, the first touch control signal trace and the second touch control signal trace are located in the same layer, and the first touch control signal trace and the display signal trace are located in different layers; the second flexible substrate is connected with the first flexible substrate on a side close to the touch control driving chip, the second flexible substrate comprises a second contact and a third touch control signal trace, and the third touch control signal trace is electrically connected with the second contact;

[0036] folding the second flexible substrate relative to the first flexible substrate, so that the second flexible substrate is folded with the first flexible substrate, and the second contact is electrically connected with the first contact.

[0037] In an optional technical solution of the above preparation method, the forming of the first flexible substrate comprises:

[0038] forming, on one side of a first substrate, a touch control signal trace layer, a first dielectric layer and a first electromagnetic shielding layer in sequence, the touch control signal trace layer comprising the first touch control signal trace and the second touch control signal trace;

[0039] forming, on the other side of the first substrate, the display signal trace, a second dielectric layer and a second electromagnetic shielding layer in sequence.

[0040] In an optional technical solution of the above preparation method, the forming of the second flexible substrate comprises: forming, on one side of a second substrate, the third touch control signal trace, a third dielectric layer and a third electromagnetic shielding layer in sequence.

[0041] In an optional technical solution of the above preparation method, the forming of the third touch control signal trace on one side of a second substrate comprises: forming a plurality of third touch control signal traces on one side of the second substrate, the plurality of third touch control signal traces being arranged at intervals.

[0042] In an alternative technical solution of the above preparation method, the forming of the second flexible substrate comprises: sequentially forming a first touch control signal trace layer, a fourth dielectric layer, a second touch control signal trace layer, a third dielectric layer and a third electromagnetic shielding layer on one side of the second substrate, the first touch control signal trace layer and the second touch control signal trace layer each comprise at least one third touch control signal trace, the third touch control signal traces between the second substrate and the fourth dielectric layer are staggered with the third touch control signal traces between the third dielectric layer and the fourth dielectric layer.

[0043] In the flexible circuit board provided by the application, the first flexible substrate comprises two trace layers, i.e., a display signal trace layer and a first touch control signal trace layer (the first touch control signal trace and the second touch control signal trace are located in the same layer, and the first touch control signal trace layer is also the second touch control signal trace layer), and the second flexible substrate comprises one trace layer, i.e., a third touch control signal trace layer. In this way, the thickness of the first flexible substrate can be reduced, so that the first flexible substrate meets the design concept of thinness, and the arrangement path of the touch control signal traces is re-planned, so that part of the touch control signal traces (e.g., the first touch control signal trace and the second touch control signal trace) are located in the first flexible substrate, and the other part of the touch control signal traces (e.g., the third touch control signal trace) are located in the second flexible substrate, the display signal traces and the first touch control signal traces and the second touch control signal traces do not spatially cross in the first flexible substrate, and the third touch control signal traces and the display signal traces are located in different flexible substrates, thereby reducing the mutual interference between the display signal traces and the touch control signal traces. BRIEF DESCRIPTION OF DRAWINGS

[0044] Embodiments of the application will be described below with reference to the accompanying drawings, in which:

[0045] FIG. 1 is a schematic diagram of a flexible circuit board in a first state according to an embodiment of the application;

[0046] FIG. 2 is a schematic diagram of a flexible circuit board in a second state according to an embodiment of the application;

[0047] FIG. 3 is a cross-sectional view of a flexible circuit board in a first state according to an embodiment of the application;

[0048] FIG. 4 is a cross-sectional view of a flexible circuit board in a second state according to an embodiment of the application;

[0049] FIG. 5 is a schematic diagram of an arrangement of a third touch control signal trace according to an embodiment of the application;

[0050] FIG. 6 is a schematic diagram of another arrangement of a third touch control signal trace according to an embodiment of the application;

[0051] Fig. 7 is a schematic view of another flexible circuit board in a first state according to an embodiment of the present application;

[0052] Fig. 8 is a schematic view of another flexible circuit board in a second state according to an embodiment of the present application;

[0053] Fig. 9 is a schematic view of another flexible circuit board in a first state according to an embodiment of the present application;

[0054] Fig. 10 is a schematic view of another flexible circuit board in a second state according to an embodiment of the present application;

[0055] Fig. 11 is a flow chart of a manufacturing method of a flexible circuit board according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] Embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these embodiments are only used to explain the technical principles of the present application, and are not used to limit the protection scope of the present application. Those skilled in the art can make adjustments to them as needed in order to adapt to specific application occasions.

[0057] In the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the related devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The ordinal numbers "first", "second" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0058] In the description of the present application, unless otherwise specified, the terms "mounting", "connecting" should be understood broadly. For example, it can be fixed connection, or detachable connection or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0059] A flexible multi-layer on cell (FMLOC) display device generally comprises a display module, a touch module and a flexible printed circuit (FPC). In order to control the touch module and the display module, the FPC is usually electrically connected with a control mainboard of the touch module and the display module. In the FPC, display signal lines (i.e. lines for transmitting display signals) and touch signal lines (i.e. lines for transmitting touch signals) are distributed in different layers. However, since the touch signal lines and the display signal lines need to be electrically connected with a binding structure (e.g. a gold finger) of the FPC, the touch signal lines and the display signal lines will interfere with each other even if they are distributed in different layers. In order to reduce the interference between the touch signal lines and the display signal lines, a ground layer is usually arranged between the layer where the display signal lines are located and the layer where the touch signal lines are located. However, this will increase the number of layers of the FPC, which is difficult to meet the design concept of thinning the FPC, and will also complicate the manufacturing process of the FPC, thereby increasing the cost of the FPC.

[0060] In some related technologies, in order to improve the above problems, the touch signal lines are separately manufactured on a bridge FPC, and the bridge FPC is bound to the main body of the FPC. Compared with the above-mentioned method of adding a ground layer, this method can reduce the manufacturing cost of the FPC to a certain extent, but it will increase the manufacturing process and the binding process of the bridge FPC, so the improvement effect is limited, and the thickness of the FPC will also increase, so it is difficult to fundamentally solve the above problems.

[0061] Embodiments of the present application provide a flexible printed circuit which can reduce the mutual interference between display signal lines and touch signal lines. Embodiments of the present application do not need to arrange a ground layer between the layer where the display signal lines are located and the layer where the touch signal lines are located, can meet the design concept of thinning, and will not complicate the manufacturing process of the FPC and will not increase the cost of the FPC.

[0062] Referring to FIG. 1 and FIG. 2, FIG. 1 is a schematic diagram of a flexible printed circuit in a first state according to an embodiment of the present application, and FIG. 2 is a schematic diagram of the flexible printed circuit in a second state according to an embodiment of the present application. In combination with FIG. 1 and FIG. 2, the flexible printed circuit comprises a first flexible substrate 100 and a second flexible substrate 200.

[0063] The cross section of the first flexible substrate 100 can be rectangular to match the shape of the display panel. The first flexible substrate 100 includes a touch driving chip 101, a first touch contact 102, a first touch signal trace 103, a second touch signal trace 104, a display signal trace 105, and a binding structure 106. For example, the binding structure 106 is a gold finger. The binding structure 106 is distributed along a first direction x. The first direction x is the length direction of the first flexible substrate 100. For example, the binding structure 106 is distributed along one long side of the first flexible substrate 100 to facilitate binding and electrical connection of the first flexible substrate 100 and the display panel.

[0064] For convenience of description, the two ends of the binding structure 106 in the first direction x are referred to as a first end and a second end. In the first direction x, the touch driving chip 101 is close to the first end of the binding structure 106, and the first touch contact 102 is close to the second end of the binding structure 106. The first touch signal trace 103, the second touch signal trace 104, and the display signal trace 105 are all electrically connected to the binding structure 106, and the first touch signal trace 103 is electrically connected to the touch driving chip 101, and the second touch signal trace 104 is electrically connected to the first touch contact 102. For example, the first touch signal trace 103 is located between the touch driving chip 101 and the first end of the binding structure 106, the second touch signal trace 104 is located between the first touch contact 102 and the second end of the binding structure 106, one end of the first touch signal trace 103 is electrically connected to the touch driving chip 101, the other end of the first touch signal trace 103 is electrically connected to the first end of the binding structure 106, one end of the second touch signal trace 104 is electrically connected to the first touch contact 102, the other end of the second touch signal trace 104 is electrically connected to the second end of the binding structure 106, and the display signal trace 105 is electrically connected to the middle part of the binding structure 106. It should be noted that in the FMLOC display device, the display panel includes a touch module, the touch module includes transmitter (TX) traces and receiver (RX) traces, and a part of the TX traces in the touch module usually need to be electrically connected to the first end of the binding structure 106, another part of the TX traces in the touch module usually need to be electrically connected to the second end of the binding structure 106, and a part of the RX traces in the touch module usually need to be electrically connected to the first end of the binding structure 106, and another part of the RX traces in the touch module usually need to be electrically connected to the second end of the binding structure 106. The embodiment of the present application arranges the touch driving chip 101 close to the first end of the binding structure 106 and the first touch contact 102 close to the second end of the binding structure 106, which can facilitate the first touch signal trace 103 to electrically connect the touch driving chip 101 and the first end of the binding structure 106, and facilitate the second touch signal trace 104 to electrically connect the first touch contact 102 and the second end of the binding structure 106.

[0065] Referring to FIG. 3 and FIG. 4, FIG. 3 is a cross-sectional view of the flexible circuit board in a first state, and FIG. 4 is a cross-sectional view of the flexible circuit board in a second state. In combination with FIG. 3 and FIG. 4, the first touch signal trace 103 and the second touch signal trace 104 are located in the same layer (for example, the first touch signal trace 103 and the second touch signal trace 104 are both located in the trace layer 10' in FIG. 3 and FIG. 4), and the first touch signal trace 103 and the display signal trace 105 are located in different layers. Since the first touch signal trace 103 and the second touch signal trace 104 are located in the same layer, it can be understood that the second touch signal trace 104 and the display signal trace 105 are also located in different layers.

[0066] The second flexible substrate 200 is connected to the first flexible substrate 100 near the side of the touch driving chip 101, and the connection between the second flexible substrate 200 and the first flexible substrate 100 is located at different positions on the width direction (for example, the width direction is perpendicular to the first direction x mentioned above) of the first flexible substrate 100 from the touch driving chip 101. For example, in the width direction of the first flexible substrate 100, the touch driving chip 101 is closer to the bonding structure 106 relative to the second flexible substrate 200. The second flexible substrate 200 includes a second contact 201 and a third touch signal trace 202, the third touch signal trace 202 is electrically connected to the second contact 201, and the third touch signal trace 202 is electrically connected to the touch driving chip 101. As shown in FIG. 1 to FIG. 4, the second flexible substrate 200 can be bent relative to the first flexible substrate 100 and folded with the first flexible substrate 100, the first state is the state of the flexible circuit board before the second flexible substrate 200 is bent relative to the first flexible substrate 100 and folded with the first flexible substrate 100, and the second state is the state of the flexible circuit board after the second flexible substrate 200 is bent relative to the first flexible substrate 100 and folded with the first flexible substrate 100. As shown in FIG. 2 and FIG. 4, in the second state, the second flexible substrate 200 is bent relative to the first flexible substrate 100, and the second flexible substrate 200 is folded with the first flexible substrate 100, and the second contact 201 is electrically connected to the first contact 102.

[0067] In an optional embodiment, the first flexible substrate 100 further comprises a fourth touch signal trace 107, the fourth touch signal trace 107 is located in the same layer as the first touch signal trace 103. Since the first touch signal trace 103 and the second touch signal trace 104 are located in the same layer, the fourth touch signal trace 107 and the second touch signal trace 104 are also located in the same layer. For example, the first touch signal trace 103, the second touch signal trace 104 and the fourth touch signal trace 107 are all located in the trace layer 10' described above. The fourth touch signal trace 107 is electrically connected with the touch driving chip 101, and the fourth touch signal trace 107 is electrically connected with the third touch signal trace 202, the third touch signal trace 202 is electrically connected with the touch driving chip 101 through the fourth touch signal trace 107. As shown in FIG. 1, in the first state, the fourth touch signal trace 107 is located between the touch driving chip 101 and the second flexible substrate 200, and the fourth touch signal trace 107 and the third touch signal trace 202 can be located in the same layer. Thus, in the first state, the first touch signal trace 103, the second touch signal trace 104, the third touch signal trace 202 and the fourth touch signal trace 107 can be located in the same layer. For example, the fourth touch signal trace 107 and the third touch signal trace 202 are an integral structure, and the fourth touch signal trace 107 extends to the second flexible substrate 200 to form the third touch signal trace 202.

[0068] In an optional embodiment, the flexible circuit board further comprises an external signal connector 300. The external signal connector 300 is electrically connected with the first flexible substrate 100, and the external signal connector 300 is configured to provide external signals to the display signal trace 105 and the touch driving chip 101 respectively. For example, one end of the display signal trace 105 is electrically connected with the external signal connector 300, and the other end of the display signal trace 105 is electrically connected with the middle part of the binding structure 106, so that the external signal connector 300 can transmit display driving signals to the binding structure 106 through the display signal trace 105. The external signal connector 300 is also electrically connected with the touch driving chip 101, so that the external signal connector 300 can transmit external signals to the touch driving chip 101, and then the touch driving chip 101 can provide touch driving signals to the binding structure 106 through the touch signal traces. For example, the touch driving signals provided by the touch driving chip 101 can be transmitted to the first end of the binding structure 106 through the first touch signal trace 103, so as to provide touch driving signals to the first end of the binding structure 106, and the touch driving signals provided by the touch driving chip 101 can be transmitted to the second end of the binding structure 106 through the fourth touch signal trace 107, the third touch signal trace 202, the second contact 201, the first contact 102 and the second touch signal trace 104 in sequence, so as to provide touch driving signals to the second end of the binding structure 106.

[0069] It should be noted that the middle part of the binding structure 106 is located between the first end of the binding structure 106 and the second end of the binding structure 106, and the middle part of the binding structure 106 is not limited to the geometric center of the binding structure 106 along the first direction x. The middle part of the binding structure 106 can be any area between the first end of the binding structure 106 and the second end of the binding structure 106. The above-mentioned external signals (including display driving signals) can include power signals, communication signals, etc., and the embodiments of the present application do not limit them.

[0070] In the embodiments of the present application, the binding structure 106 includes a plurality of bonding pins 1061 arranged along the first direction x, and the display signal wire 105 and the touch signal wire are electrically connected with the bonding pins 1061. For example, the binding structure 106 includes a display pin, a first touch pin and a second touch pin. The first touch pin can be located at the first end of the binding structure 106, the second touch pin can be located at the second end of the binding structure 106, and the display pin can be located at the middle of the binding structure 106. The display signal wire 105 is electrically connected with the display pin, so that the external signal connector 300 can transmit the display driving signal to the display pin through the display signal wire 105. The first touch signal wire 103 is electrically connected with the first touch pin, so that the touch driving signal provided by the touch driving chip 101 can be transmitted to the first touch pin through the first touch signal wire 103 to provide the touch driving signal to the first touch pin. The second touch signal wire 104 is electrically connected with the second touch pin, so that the touch driving signal provided by the touch driving chip 101 can be transmitted to the second touch pin through the fourth touch signal wire 107, the third touch signal wire 202, the second touch 201, the first touch 102 and the second touch signal wire 104 in sequence to provide the touch driving signal to the second touch pin.

[0071] In some embodiments, as shown in FIG. 2, in the second state, the second flexible substrate 200 passes from the side of the touch driving chip 101 away from the binding structure 106. In the width direction of the first flexible substrate 100, the second flexible substrate 200 and the binding structure 106 are located on both sides of the touch driving chip 101, so that the signal interference of the second flexible substrate 200 to the binding structure 106 can be avoided.

[0072] As described above, the flexible circuit board provided by the embodiments of the present application comprises a first flexible substrate 100 and a second flexible substrate 200, the second flexible substrate 200 is bent relative to the first flexible substrate 100 and the second flexible substrate 200 is folded with the first flexible substrate 100. The first flexible substrate 100 comprises two layers of wiring layers, i.e., a layer where the display signal wires 105 are located and a layer where the first touch signal wires 103 are located (the first touch signal wires 103 and the second touch signal wires 104 are located in the same layer, the layer where the first touch signal wires 103 are located is also the layer where the second touch signal wires 104 are located, for example, the wiring layer 10 in FIGS. 3 and 4), and the second flexible substrate 200 comprises one layer of wiring layer, i.e., a layer where the third touch signal wires 202 are located. In this way, not only the thickness of the first flexible substrate 100 can be reduced so that the first flexible substrate 100 meets the design concept of thinning, but also the arrangement path of the touch signal wires is re-planned, so that part of the touch signal wires (for example, the first touch signal wires 103 and the second touch signal wires 104) are located in the first flexible substrate 100, and the other part of the touch signal wires (for example, the third touch signal wires 202) are located in the second flexible substrate 200, the display signal wires 105 and the first touch signal wires 103 and the second touch signal wires 104 will not appear spatial intersection in the first flexible substrate 100, and the third touch signal wires 202 and the display signal wires 105 are located in different flexible substrates, thereby the mutual interference between the display signal wires 105 and the touch signal wires can be reduced.

[0073] In addition, in the case that the second flexible substrate 200 only comprises one layer of wiring layer, the thickness of the second flexible substrate 200 is relatively thin, and after the second flexible substrate 200 is folded with the first flexible substrate 100, the thickness of the entire flexible circuit board will not be greatly affected. Moreover, since only the third touch signal wires 202 need to be arranged on the second flexible substrate 200, and there is no other electronic device, the width of the second flexible substrate 200 is relatively smaller than the width of the first flexible substrate 100, and will not occupy too much space.

[0074] Moreover, in the preparation process of the flexible circuit board, the first flexible substrate 100 and the second flexible substrate 200 can be formed simultaneously using the same substrate, so that the processing cost can be reduced and the processing technology can be simplified.

[0075] In an implementation form of the embodiment of the present application, the first flexible substrate 100 comprises a first touch connector electrically connected with the first contact 102, and the second flexible substrate 200 comprises a second touch connector electrically connected with the second contact 201. After the second flexible substrate 200 is folded relative to the first flexible substrate 100 and is folded with the first flexible substrate 100, that is, in the second state of the flexible circuit board, the first touch connector is plugged and connected with the second touch connector, so that the second contact 201 is electrically connected with the first contact 102 through the second touch connector and the first touch connector.

[0076] In another implementation form of the embodiment of the present application, as shown in FIG. 4, the flexible circuit board further comprises an anisotropic conductive adhesive 400 between the first contact 102 and the second contact 201, and the second contact 201 and the first contact 102 are electrically connected through the anisotropic conductive adhesive 400. The anisotropic conductive adhesive 400 has the functions of one-way conduction (for example, vertical conduction and parallel non-conduction) and adhesive fixation. Therefore, by arranging the anisotropic conductive adhesive 400 between the first contact 102 and the second contact 201, the first flexible substrate 100 and the second flexible substrate 200 can be fixed, and the conduction of the first contact 102 and the second contact 201 can be realized. On the other hand, the anisotropic conductive adhesive has the form of a relatively thin adhesive layer. By connecting the first contact 102 and the second contact 201 through the anisotropic conductive adhesive, the distance between the first contact 102 and the second contact 201 is small, the thickness of the entire flexible circuit board is small, and the local bulging phenomenon of the flexible circuit board is avoided. From the perspective of processing cost, the connection mode of using the anisotropic conductive adhesive only needs a thin layer of adhesive material, without the need to add other electrical connecting components, so it is beneficial to control the cost.

[0077] In an optional embodiment of the above-mentioned another implementation manner, the first flexible substrate 100 further comprises a positioning mark 108, which is used to position the anisotropic conductive adhesive during the process of the second flexible substrate 200 being bonded with the first flexible substrate 100. The positioning mark 108 can be a ring-shaped positioning member distributed around the first contact 102, or a positioning hole used to fix the adhesive material composed of the anisotropic conductive adhesive, and the present application does not limit the embodiments thereof, and in actual application, the positioning mark 108 can be adjusted according to the requirement, so that the positioning mark 108 positions the anisotropic conductive adhesive during the process of the second flexible substrate 200 being bonded with the first flexible substrate 100. It should be noted that the positioning mark 108 is taken as an example to be arranged on the first flexible substrate 100. In some embodiments, the positioning mark 108 can be arranged on the second flexible substrate 200. In another embodiments, the positioning mark can be arranged on both the first flexible substrate 100 and the second flexible substrate 200. Whether the positioning mark is arranged on the first flexible substrate 100 or the second flexible substrate 200, the positioning mark can assist the anisotropic conductive adhesive to be positioned during the process of the second flexible substrate 200 being bonded with the first flexible substrate 100.

[0078] In an optional embodiment, as shown in FIG. 3 and FIG. 4, the first flexible substrate 100 further comprises a first substrate 111, a first dielectric layer 112, a second dielectric layer 113, a first electromagnetic shielding layer 114 and a second electromagnetic shielding layer 115. The first dielectric layer 112 and the second dielectric layer 113 are located on both sides of the first substrate 111, the first electromagnetic shielding layer 114 is located on the side of the first dielectric layer 112 away from the first substrate 111, and the first electromagnetic shielding layer 114 covers the first dielectric layer 112. The second electromagnetic shielding layer 115 is located on the side of the second dielectric layer 113 away from the first substrate 111, and the second electromagnetic shielding layer 115 covers the second dielectric layer 113. The first touch signal wire 103 and the second touch signal wire 104 (both of which are located in the wire layer 10' in FIG. 3 and FIG. 4) are located between the first substrate 111 and the first dielectric layer 112, and the display signal wire 105 is located between the first substrate 111 and the second dielectric layer 113.

[0079] In optional embodiments, as shown in Figures 3 and 4, the second flexible substrate 200 further includes a second substrate 211, a third dielectric layer 212, and a third electromagnetic shielding layer 213. The second substrate 211, the third dielectric layer 212, and the third electromagnetic shielding layer 213 are stacked sequentially, with the third electromagnetic shielding layer 213 covering the third dielectric layer 212. The third touch signal traces 202 are located between the second substrate 211 and the third dielectric layer 212. For example, the second flexible substrate 200 includes multiple third touch signal traces 202. Please refer to Figure 5, which is a cross-sectional view of a second flexible substrate 200 provided in an embodiment of this application. Figure 5 shows a schematic layout of one type of third touch signal trace 202. As shown in Figure 5, the multiple third touch signal traces 202 are arranged at intervals between the second substrate 211 and the third dielectric layer 212, thereby reducing mutual interference between adjacent second touch signal traces 202.

[0080] In some embodiments, the second flexible substrate 200 further includes a fourth dielectric layer located between the second substrate 211 and the third dielectric layer 212. The second flexible substrate 200 includes multiple third touch signal traces 202, with at least one third touch signal trace 202 located between the second substrate 211 and the fourth dielectric layer, and the remaining third touch signal traces 202 located between the third dielectric layer 212 and the fourth dielectric layer. For example, please refer to FIG6, which is a cross-sectional view of another second flexible substrate 200 provided in an embodiment of this application. FIG6 shows another schematic diagram of the layout of the third touch signal traces 202. As shown in FIG6, the second flexible substrate 200 further includes a second substrate 211, a third dielectric layer 212, a fourth dielectric layer 214, and a third electromagnetic shielding layer 213. The second substrate 211, the fourth dielectric layer 214, the third dielectric layer 212, and the third electromagnetic shielding layer 213 are stacked sequentially, and the third electromagnetic shielding layer 213 covers the third dielectric layer 212. The second flexible substrate 200 includes multiple third touch signal traces 202. At least one third touch signal trace 202 is located between the second substrate 211 and the fourth dielectric layer 214, while the remaining third touch signal traces 202 are located between the third dielectric layer 212 and the fourth dielectric layer 214. Furthermore, the third touch signal traces 202 located between the second substrate 211 and the fourth dielectric layer 214 are interleaved with the third touch signal traces 202 located between the third dielectric layer 212 and the fourth dielectric layer 214. This results in the multiple third touch signal traces 202 having a close arrangement of their orthogonal projections onto the second substrate 211. Moreover, due to the presence of the fourth dielectric layer 214, adjacent second touch signal traces 202 can be electrically isolated from each other, reducing mutual interference between adjacent second touch signal traces 202.

[0081] As shown above, for the second flexible substrate 200 shown in Figure 5, there is only one layer of second touch signal traces 202 between the second substrate 211 and the third dielectric layer 212. Therefore, the thickness of the second flexible substrate 200 can be minimized, thereby reducing the overall thickness of the flexible circuit board. For the second flexible substrate 200 shown in Figure 6, although the thickness of the second flexible substrate 200 may be relatively large, the second touch signal traces 202 are closely arranged, which can minimize the width of the second flexible substrate 200, thereby reducing the space occupied by the second flexible substrate 200. In practical applications, the layout of the second touch signal traces 202 can be selected according to specific processing requirements. In addition, in the second flexible substrate 200, the aforementioned multiple third touch signal traces 202 may include power signal lines, communication signal lines, etc.

[0082] In some embodiments, the first substrate 111 and the second substrate 211 are integral structures; and / or, the third dielectric layer 212 and the first dielectric layer 112 are integral structures; and / or, the third electromagnetic shielding layer 213 and the first electromagnetic shielding layer 114 are integral structures. Thus, in the first state, the flexible circuit board has the first substrate 111 and the second substrate 211 co-layered; and / or, the third dielectric layer 212 and the first dielectric layer 112 co-layered; and / or, the third electromagnetic shielding layer 213 and the first electromagnetic shielding layer 114 co-layered. The integrally structured functional layers can be formed using the same material and the same fabrication process (e.g., patterning process), and the co-layered distribution means that these co-layered functional layers can be formed using the same material and the same fabrication process, thereby simplifying the fabrication process of the flexible circuit board. For example, the third dielectric layer 212 and the first dielectric layer 112 are formed in the same fabrication process, and the third electromagnetic shielding layer 213 and the first electromagnetic shielding layer 114 are formed in the same fabrication process.

[0083] In addition, the first electromagnetic shielding layer 114, the second electromagnetic shielding layer 115, and the third electromagnetic shielding layer 213 can reduce the electromagnetic interference of external magnetic fields on the signal traces within the flexible circuit board. In some embodiments, the electromagnetic shielding layer is also referred to as an electromagnetic interference (EMI) layer.

[0084] In optional embodiments, the first touch signal trace 103, the second touch signal trace 104, the third touch signal trace 202, the fourth touch signal trace 107, and the display signal trace 105 are all metal traces. For example, the materials of the first touch signal trace 103, the second touch signal trace 104, the third touch signal trace 202, the fourth touch signal trace 107, and the display signal trace 105 are all metals with good conductivity, such as copper. This application does not limit this aspect.

[0085] In one embodiment of this application, as shown in FIG4, the flexible circuit board further includes an insulating adhesive layer 500, which is located between the second substrate 211 and the second electromagnetic shielding layer 115. The insulating adhesive layer 500 is used to bond the second electromagnetic shielding layer 115 and the second substrate 211. FIG4 also shows that after the second flexible substrate 200 and the first flexible substrate 100 are assembled, the first contact on the first flexible substrate 100 and the second contact on the second flexible substrate 200 are electrically connected by anisotropic conductive adhesive 400. Since the second flexible substrate 200 is relatively thin, by providing the insulating adhesive layer 500, the flatness of the second flexible substrate 200 and the first flexible substrate 100 after assembly can be ensured, preventing wrinkles, warping, and other phenomena from occurring on the second flexible substrate 200.

[0086] In this embodiment, the positional relationship between the external signal connector 300 and the first flexible substrate 100 can be flexibly set.

[0087] In one embodiment, as shown in Figures 1 and 2, the external signal connector 300 is located on the side of the first flexible substrate 100 near the first contact 102. In the first state, the external signal connector 300 and the second flexible substrate 200 are located on opposite sides of the first flexible substrate 100.

[0088] In another embodiment, referring to Figures 7 and 8, Figure 7 is a schematic diagram of another flexible circuit board provided in the present application in a first state, and Figure 8 is a schematic diagram of the flexible circuit board shown in Figure 7 in a second state. Referring to Figures 7 and 8, the external signal connector 300 and the bonding structure 106 are located on opposite sides of the first flexible substrate 100. For example, the extension direction of the external signal connector 300 relative to the first flexible substrate 100 is substantially perpendicular to the distribution direction of the bonding structure 106 (i.e., the first direction x), and the external signal connector 300 is approximately located in the middle of the bonding structure 106 in the distribution direction of the bonding structure 106.

[0089] In another embodiment, referring to Figures 9 and 10, Figure 9 is a schematic diagram of another flexible circuit board provided in the present application in a first state, and Figure 10 is a schematic diagram of the flexible circuit board shown in Figure 9 in a second state. Referring to Figures 9 and 10, the external signal connector 300 is located on the side of the first flexible substrate 100 closer to the touch driver chip 101. As shown in Figure 9, in the first state, the external signal connector 300 and the second flexible substrate 200 are located on the same side of the first flexible substrate 100, and the extension direction of the external signal connector 300 relative to the first flexible substrate 100 is approximately parallel to the extension direction of the second flexible substrate 200. The distance between the external signal connector 300 and the first contact 102 is greater than the distance between the external signal connector 300 and the touch driver chip 101.

[0090] It should be noted that no matter where the external signal connector 300 is located on the first flexible substrate 100, it does not affect the bending of the second flexible substrate 200 relative to the first flexible substrate 100. Therefore, the position of the external signal connector 300 will not limit the technical solution of the embodiments of this application.

[0091] This application embodiment also provides a display module, which may be an FMLOC display module. The display module includes a display panel, a display driver chip, and the flexible circuit board provided in the above embodiment. The display panel includes a display module and a touch module. Data lines and gate lines in the display module are electrically connected to the display driver chip, and the display driver chip is electrically connected to the bonding structure 106 in the flexible circuit board. For example, the display driver chip is electrically connected to the display pins of the bonding structure 106. Thus, display signals can be sequentially provided to the display module through the display signal traces 105, the bonding structure 106, and the display driver chip in the flexible circuit board.

[0092] The touch module includes TX and RX traces. A portion of the TX traces in the touch module are electrically connected to a first terminal of the bonding structure 106, and another portion of the TX traces in the touch module are electrically connected to a second terminal of the bonding structure 106. Similarly, a portion of the RX traces in the touch module are electrically connected to a first terminal of the bonding structure 106, and another portion of the RX traces in the touch module are electrically connected to a second terminal of the bonding structure 106. Thus, touch signals can be sequentially provided to the touch module through the touch driver chip 101, the touch signal traces, and the bonding structure 106 in the flexible circuit board.

[0093] In some embodiments, the display module is an organic light-emitting diode (OLED) display module.

[0094] This application also provides a method for fabricating a flexible circuit board. Referring to Figure 11, the fabrication method includes the following steps S1101 to S1102.

[0095] S1101. Forming a first flexible substrate and a second flexible substrate; the first flexible substrate includes a touch driver chip, a first contact, a first touch signal trace, a second touch signal trace, a display signal trace, and a bonding structure. The bonding structure is distributed along a first direction. In the first direction, the touch driver chip is close to a first end of the bonding structure, the first contact is close to a second end of the bonding structure, the first touch signal trace, the second touch signal trace, and the display signal trace are all electrically connected to the bonding structure, and the first touch signal trace is electrically connected to the touch driver chip, the second touch signal trace is electrically connected to the first contact, the first touch signal trace and the second touch signal trace are located on the same layer, and the first touch signal trace and the display signal trace are located on different layers; the second flexible substrate is connected to the side of the first flexible substrate close to the touch driver chip, the second flexible substrate includes a second contact and a third touch signal trace, and the third touch signal trace is electrically connected to the second contact.

[0096] In an optional embodiment, the first flexible substrate further includes a fourth touch signal trace, which is located on the same layer as the first touch signal trace. The fourth touch signal trace is electrically connected to the touch driver chip and is also electrically connected to the third touch signal trace. The third touch signal trace is electrically connected to the touch driver chip through the fourth touch signal trace.

[0097] In one embodiment, forming a first flexible substrate includes: sequentially forming a touch signal routing layer (e.g., routing layer 10' in Figures 3 and 4), a first dielectric layer, and a first electromagnetic shielding layer on one side of a first substrate, wherein the touch signal routing layer includes a first touch signal routing and a second touch signal routing; and sequentially forming a display signal routing layer, a second dielectric layer, and a second electromagnetic shielding layer on the other side of the first substrate.

[0098] In one embodiment, forming a second flexible substrate includes sequentially forming a third touch signal trace, a third dielectric layer, and a third electromagnetic shielding layer on one side of the second substrate. For example, multiple third touch signal traces are formed on one side of the second substrate, and the multiple third touch signal traces are arranged at intervals.

[0099] In another embodiment, forming a second flexible substrate includes: sequentially forming a first touch signal routing layer, a fourth dielectric layer, a second touch signal routing layer, a third dielectric layer, and a third electromagnetic shielding layer on one side of a second substrate. The first and second touch signal routing layers each include at least one third touch signal routing line. The third touch signal routing lines located between the second substrate and the fourth dielectric layer are interleaved with those located between the third and fourth dielectric layers. For example, the first touch signal routing layer is the layer containing the third touch signal routing line 202 located between the second substrate 211 and the fourth dielectric layer 214 in FIG. 6. The second touch signal routing layer is the layer containing the third touch signal routing line 202 located between the third dielectric layer 212 and the fourth dielectric layer 214 in FIG. 6.

[0100] In optional embodiments, the first substrate and the second substrate are an integral structure; and / or, the third dielectric layer and the first dielectric layer are an integral structure; and / or, the third electromagnetic shielding layer and the first electromagnetic shielding layer are an integral structure. The third dielectric layer and the first dielectric layer can be formed in a single fabrication process. The third electromagnetic shielding layer and the first electromagnetic shielding layer can be formed in a single fabrication process.

[0101] S1102. The second flexible substrate is bent relative to the first flexible substrate, so that the second flexible substrate and the first flexible substrate are aligned, and the second contact and the first contact are electrically connected.

[0102] In one implementation of this application, the first flexible substrate further includes a first touch connector electrically connected to the first contact, and the second flexible substrate further includes a second touch connector electrically connected to the second contact. The second flexible substrate is bent relative to the first flexible substrate so that the second flexible substrate and the first flexible substrate are aligned, and the first touch connector and the second touch connector are inserted and electrically connected. The second contact and the first contact are electrically connected to the first touch connector through the second touch connector.

[0103] In another implementation of this application, the second flexible substrate is bent relative to the first flexible substrate, so that the second flexible substrate and the first flexible substrate are aligned, and the second contact and the first contact are electrically connected by anisotropic conductive adhesive. Furthermore, the first flexible substrate or the second flexible substrate includes positioning marks, which are used for positioning with anisotropic conductive adhesive during the alignment process of the second flexible substrate and the first flexible substrate.

[0104] In this embodiment, the steps of forming the first flexible substrate and forming the second flexible substrate can be performed simultaneously. That is, the first flexible substrate and the second flexible substrate use the same substrate, and each functional layer is formed sequentially on the same substrate. In this way, the fabrication method of flexible circuit board can be simplified and the fabrication efficiency can be improved.

[0105] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A flexible circuit board, comprising a first flexible substrate and a second flexible substrate; the first flexible substrate comprises a touch driving chip, a first contact, a first touch signal trace, a second touch signal trace, a display signal trace and a binding structure, the binding structure is distributed along a first direction, in the first direction, the touch driving chip is close to a first end of the binding structure, the first contact is close to a second end of the binding structure, the first touch signal trace, the second touch signal trace and the display signal trace are electrically connected with the binding structure, the first touch signal trace is electrically connected with the touch driving chip, the second touch signal trace is electrically connected with the first contact, the first touch signal trace and the second touch signal trace are located in the same layer, and the first touch signal trace and the display signal trace are located in different layers; the second flexible substrate is connected with the first flexible substrate on a side close to the touch driving chip, the second flexible substrate is bent relative to the first flexible substrate and is folded with the first flexible substrate, the second flexible substrate comprises a second contact and a third touch signal trace, the third touch signal trace is electrically connected with the second contact, and the third touch signal trace is electrically connected with the touch driving chip, and the second contact is electrically connected with the first contact.

2. The flexible circuit board of claim 1, wherein, the first flexible substrate further comprises a fourth touch signal trace, the fourth touch signal trace is located in the same layer with the first touch signal trace, the fourth touch signal trace is electrically connected with the touch driving chip, and the fourth touch signal trace is electrically connected with the third touch signal trace, and the third touch signal trace is electrically connected with the touch driving chip through the fourth touch signal trace.

3. The flexible circuit board according to claim 1 or 2, wherein, the first flexible substrate further comprises a first touch connector electrically connected with the first contact, the second flexible substrate further comprises a second touch connector electrically connected with the second contact, the first touch connector is plug-connected and electrically connected with the second touch connector, and the second contact and the first contact are electrically connected with the first touch connector through the second touch connector.

4. The flexible circuit board according to claim 1 or 2, wherein, the flexible circuit board further comprises anisotropic conductive adhesive between the first contact and the second contact, and the second contact and the first contact are electrically connected through the anisotropic conductive adhesive.

5. The flexible circuit board of claim 4, wherein, the first flexible substrate or the second flexible substrate comprises a positioning mark, the positioning mark is used for positioning the anisotropic conductive adhesive in the folding process of the second flexible substrate with the first flexible substrate.

6. The flexible circuit board of any one of claims 1 to 5, wherein, the flexible circuit board further comprises an externally supplied signal connector, the externally supplied signal connector is electrically connected with the first flexible substrate, and the externally supplied signal connector is used for supplying external signals to the display signal trace and the touch driving chip respectively.

7. The flexible circuit board of claim 6, wherein, the externally supplied signal connector is located on a side of the first flexible substrate close to the first contact.

8. The flexible circuit board of claim 6, wherein, the externally supplied signal connector and the binding structure are located on opposite sides of the first flexible substrate.

9. The flexible circuit board according to claim 6, wherein, The external signal connector is located on the side of the first flexible substrate close to the touch driving chip.

10. The flexible circuit board of any one of claims 1 to 9, wherein, The first flexible substrate further comprises a first substrate, a first dielectric layer, a second dielectric layer, a first electromagnetic shielding layer and a second electromagnetic shielding layer, the first dielectric layer and the second dielectric layer are located on two sides of the first substrate, the first electromagnetic shielding layer is located on the side of the first dielectric layer away from the first substrate, the second electromagnetic shielding layer is located on the side of the second dielectric layer away from the first substrate, the first touch signal trace and the second touch signal trace are both located between the first substrate and the first dielectric layer, and the display signal trace is located between the first substrate and the second dielectric layer.

11. The flexible circuit board of claim 10, wherein, The second flexible substrate further comprises a second substrate, a third dielectric layer and a third electromagnetic shielding layer, the second substrate, the third dielectric layer and the third electromagnetic shielding layer are sequentially stacked, and the third touch signal trace is located between the second substrate and the third dielectric layer.

12. The flexible circuit board of claim 11, wherein, The second flexible substrate comprises a plurality of third touch signal traces, and the plurality of third touch signal traces are arranged at intervals between the second substrate and the third dielectric layer.

13. The flexible circuit board of claim 10, wherein, The second flexible substrate further comprises a second substrate, a third dielectric layer, a fourth dielectric layer and a third electromagnetic shielding layer, the second substrate, the fourth dielectric layer, the third dielectric layer and the third electromagnetic shielding layer are sequentially stacked, the second flexible substrate comprises a plurality of third touch signal traces, at least one third touch signal trace is located between the second substrate and the fourth dielectric layer, and the remaining third touch signal traces are located between the third dielectric layer and the fourth dielectric layer.

14. The flexible circuit board of claim 13, wherein, The third touch signal traces located between the second substrate and the fourth dielectric layer and the third touch signal traces located between the third dielectric layer and the fourth dielectric layer are staggered.

15. The flexible circuit board according to any one of claims 11 to 14, wherein, the first substrate and the second substrate are an integral structure; and / or, the third dielectric layer and the first dielectric layer are an integral structure; and / or, the third electromagnetic shielding layer and the first electromagnetic shielding layer are an integral structure.

16. The flexible circuit board of any one of claims 11 to 15, wherein, The flexible circuit board further comprises an insulating adhesive layer, the insulating adhesive layer is located between the second electromagnetic shielding layer and the second substrate.

17. The flexible circuit board according to any one of claims 1 to 16, wherein, the binding structure comprises display pins, first touch pins and second touch pins; the display signal trace is electrically connected with the display pins; the first touch signal trace is electrically connected with the first touch pins; the second touch signal trace is electrically connected with the second touch pins.

18. A display module, comprising a display panel, a display driving chip and the flexible circuit board according to any one of claims 1 to 17. The display panel comprises a display module and a touch module, and data lines and gate lines in the display module are electrically connected with the display driving chip; the display driving chip is electrically connected with the binding structure in the flexible circuit board; Part of the TX lines of the touch module are electrically connected to the first end of the binding structure, and the other part of the TX lines of the touch module are electrically connected to the second end of the binding structure. Part of the RX lines of the touch module are electrically connected to the first end of the binding structure, and the other part of the RX lines of the touch module are electrically connected to the second end of the binding structure.

19. A method for manufacturing a flexible circuit board, comprising: forming a first flexible substrate and a second flexible substrate; the first flexible substrate comprises a touch driving chip, a first contact, a first touch signal line, a second touch signal line, a display signal line and a binding structure, the binding structure is distributed along a first direction, in the first direction, the touch driving chip is close to the first end of the binding structure, the first contact is close to the second end of the binding structure, the first touch signal line, the second touch signal line and the display signal line are electrically connected to the binding structure, and the first touch signal line is electrically connected to the touch driving chip, the second touch signal line is electrically connected to the first contact, the first touch signal line and the second touch signal line are located in the same layer, and the first touch signal line and the display signal line are located in different layers; the second flexible substrate is connected to the side of the first flexible substrate close to the touch driving chip, and the second flexible substrate comprises a second contact and a third touch signal line, and the third touch signal line is electrically connected to the second contact; bending the second flexible substrate relative to the first flexible substrate to make the second flexible substrate and the first flexible substrate fold together, and make the second contact and the first contact electrically connected.

20. The flexible circuit board of claim 19, wherein the first flexible substrate is formed by sequentially forming a touch signal line layer, a first dielectric layer and a first electromagnetic shielding layer on one side of a first substrate, the touch signal line layer comprises the first touch signal line and the second touch signal line; and sequentially forming the display signal line, a second dielectric layer and a second electromagnetic shielding layer on the other side of the first substrate; the second flexible substrate is formed by sequentially forming the third touch signal line, a third dielectric layer and a third electromagnetic shielding layer on one side of a second substrate.

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