Flexible circuit board, display module and display device

Abstract

The invention provides a flexible circuit board, a display module and a display device. The problem that the service life of a flexible circuit board is short in the prior art is solved. The flexible circuit board is provided with a main board area and a bending area which are adjacently arranged, and the flexible circuit board comprises a first base material layer, a second base material layer and a third base material layer, and a plurality of conductive layers stacked on at least one side of the first substrate layer, wherein the plurality of conductive layers comprise a first conductive layer and a second conductive layer, the first conductive layer extends from the mainboard area to the bending area, and the second conductive layer is located in the mainboard area; the bending resistance of the first conductive layer is better than that of the second conductive layer.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a flexible circuit board, a display module and a display device. Background Art

[0002] In recent years, the rise of foldable screen mobile phones has set off a market boom. In order to ensure the folding characteristics, the laminated materials of foldable display modules are all flexible. In this case, the touch stress will be transmitted to the flexible circuit board layer by layer. Frequent touch will cause fatigue failure of the flexible circuit board, circuit breakage, etc., which will lead to a decrease in the service life of the display product. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a flexible circuit board, a display module and a display device, which solve the problem of low life of the flexible circuit board in the prior art.

[0004] The first aspect of the present application provides a flexible circuit board having a main board area and a bending area arranged adjacent to each other, the flexible circuit board comprising: a first substrate layer; and a plurality of conductive layers, the plurality of conductive layers being stacked on at least one side of the first substrate layer; wherein the plurality of conductive layers comprise a first conductive layer and a second conductive layer, the first conductive layer extending from the main board area to the bending area, and the second conductive layer being located in the main board area; the first conductive layer has better bending resistance than the second conductive layer. The advantage is that while ensuring the electrical quality of the main board area, the bending characteristics of the bending area are also ensured, thereby improving the micro-motion performance of the bending area, reducing the problem of wire breakage caused by touch vibration in the bending area, and improving the service life.

[0005] In combination with the first aspect, in some possible implementations, the first conductive layer and the second conductive layer are located on the same side of the first substrate layer; preferably, the first conductive layer is located between the first substrate layer and the second conductive layer; preferably, the flexible circuit board also includes a second substrate layer, located in the main board area, and located between the second conductive layer and the first conductive layer; preferably, the flexible circuit board also includes a first adhesive layer, located between the second substrate layer and the first conductive layer; preferably, the first substrate layer extends from the main board area to the bending area.

[0006] In combination with the first aspect, in some possible implementations, the multiple conductive layers also include a third conductive layer, and the third conductive layer is located on the side of the first substrate layer away from the first conductive layer; the third conductive layer extends from the main board area to the bending area, or the third conductive layer is located in the main board area; preferably, the third conductive layer extends from the main board area to the bending area, and the third conductive layer has better bending resistance than the second conductive layer; preferably, the third conductive layer and the first conductive layer are made of the same material.

[0007] In combination with the first aspect, in some possible implementations, the flexible circuit board also includes a fourth conductive layer, which is located on the side of the third conductive layer away from the first substrate layer; the fourth conductive layer is located in the main board area; preferably, the bending resistance of the fourth conductive layer is inferior to that of the first conductive layer; preferably, the fourth conductive layer and the second conductive layer are made of the same material; preferably, the flexible circuit board also includes a second adhesive layer, which is located between the third conductive layer and the fourth conductive layer; preferably, the flexible circuit board also includes a third substrate layer, which is located on the side of the fourth conductive layer away from the first substrate layer.

[0008] In combination with the first aspect, in some possible implementations, the flexible circuit board also includes a fifth conductive layer, which is located on the side of the fourth conductive layer away from the first substrate layer and located in the main board area; preferably, the bending resistance of the fifth conductive layer is inferior to that of the first conductive layer; preferably, the material of the fifth conductive layer is the same as that of the second conductive layer; preferably, the flexible circuit board also includes a sixth conductive layer, which is located on the side of the fifth conductive layer away from the first substrate layer and located in the main board area; preferably, the bending resistance of the sixth conductive layer is inferior to that of the first conductive layer; preferably, the material of the sixth conductive layer is the same as that of the second conductive layer; preferably, the flexible circuit board also includes a fourth substrate layer, which is located between the fifth conductive layer and the sixth conductive layer; preferably, the flexible circuit board also includes a third adhesive layer, which is located between the fifth conductive layer and the fourth substrate layer.

[0009] In combination with the first aspect, in some possible implementations, the material of the first conductive layer includes rolled copper; and / or the material of the second conductive layer includes electrolytic copper.

[0010] In combination with the first aspect, in some possible implementations, the flexible circuit board further includes: a first protective film, at least one conductive layer located on the first side of the first substrate layer is away from the first substrate layer, and extends from the main board area to the bending area; and / or, a second protective film, at least one conductive layer located on the second side of the first substrate layer is away from the first substrate layer, and extends from the main board area to the bending area. The advantage is that the conductive layer is protected and prevented from oxidation, while increasing wear resistance and stain resistance, and improving the reliability and service life of the product.

[0011] In combination with the first aspect, in some possible implementations, the number of conductive layers on the first side of the first substrate layer is less than the number of conductive layers on the second side of the first substrate layer.

[0012] In combination with the first aspect, in some possible implementations, the flexible circuit board includes a first protective film; the flexible circuit board also includes a first supporting layer, which is arranged on the same layer as the first protective film and is located in the bending area; preferably, the first protective film and the first supporting layer are in contact; preferably, the flexible circuit board also includes a second protective film, and the orthographic projections of the first protective film and the first supporting layer on the first substrate layer are both located within the orthographic projection range of the second protective film on the first substrate layer; preferably, the flexible circuit board also includes a second supporting layer, which is located on the side of the second protective film away from the first substrate layer and is located in the main board area.

[0013] In combination with the first aspect, in some possible implementations, the flexible circuit board includes a first protective film, the first protective film includes a first portion and a second portion arranged adjacent to each other, the first portion covers the side wall of at least one conductive layer, and the second portion is located in the bending zone; the flexible circuit board also includes a first glue portion, which is located on the side of the first protective film away from the first substrate layer and is located at the junction of the first portion and the second portion; and / or, the flexible circuit board includes a second protective film, the second protective film includes a fourth portion and a fifth portion arranged adjacent to each other, the fourth portion covers the side wall of at least one conductive layer, and the fifth portion is located in the bending zone; the flexible circuit board also includes a second glue portion, which is located on the side of the second protective film away from the first substrate layer and Located at the junction of the fourth part and the fifth part; preferably, the ratio of the thickness of at least one of the first adhesive part and the second adhesive part to the thickness of the bending zone is 0.8-2; preferably, in the direction from the main board area to the bending zone, the length of at least one of the first adhesive part and the second adhesive part accounts for 4%-15% of the length of the bending zone; preferably, the modulus of the first adhesive part is greater than that of the second adhesive part; preferably, the first protective film also includes a third part, which is arranged adjacent to the first part and is located on the side of the first part away from the second part; the third part is located in the main board area; preferably, the second protective film also includes a sixth part, which is arranged adjacent to the fourth part and is located on the side of the fourth part away from the fifth part; the sixth part is located in the main board area. The advantage is that the stress point at the intersection of the multi-layer conductive layer can be protected to ensure that the force point is away from the stress concentration area during the micro-motion process.

[0014] In combination with the first aspect, in some possible implementations, the flexible circuit board further includes a second substrate layer, which is located on one side of the first substrate layer and is located in the main board area; the first substrate layer extends from the main board area to the bending area, and the modulus of the first substrate layer is smaller than that of the second substrate layer; preferably, the first conductive layer is located between the first substrate layer and the second conductive layer, and the second substrate layer is located between the second conductive layer and the first conductive layer; preferably, the flexible circuit board further includes a third substrate layer, which is located on the side of the first substrate layer away from the second substrate layer and is located in the main board area; the modulus of the first substrate layer is smaller than that of the third substrate layer; preferably, the modulus of the first substrate layer is less than or equal to 5Gpa. The advantage is that the stress and deformation generated in the first substrate layer 111 during static bending can be reduced, thereby improving the micro-motion performance of the flexible circuit board and improving the service life of the product.

[0015] A second aspect of the present application provides a display module, comprising: a display panel; and a flexible circuit board provided by any of the above embodiments, wherein the flexible circuit board further comprises a conductive pad located in a main board area, and the conductive pad is bonded to the display panel.

[0016] The third aspect of the present application provides a display device, including: the display module provided in the embodiment of the present application, the flexible circuit board also has a terminal area, located on the side of the bending area away from the main board area; the flexible circuit board also includes a wiring terminal, located in the terminal area; the bending area is in a bent state, and the wiring terminal is located on the side of the main board area away from the display panel; and the main board is bound to the wiring terminal.

[0017] According to the flexible circuit board, display module and display device provided by the embodiments of the present application, by setting the first conductive layer to extend from the main board area to the bending area, the second conductive layer is located in the main board area, and the bending resistance of the first conductive layer is better than that of the second conductive layer, the electrical quality of the main board area can be guaranteed while ensuring the bending characteristics of the bending area, thereby improving the micro-motion performance of the bending area, reducing the problem of broken wires caused by touch vibration in the bending area, and improving the service life. At the same time, the bending resistance of the first conductive layer is better than that of the second conductive layer, and accordingly, the deformation amount of the second conductive layer under pressure is smaller than that of the first conductive layer. Based on this, in the preparation process of the flexible circuit board, after the preparation of the first conductive layer is completed, during the rolling process of preparing the second conductive layer, since the deformation amount of the second conductive layer is smaller than that of the first conductive layer, the alignment degree of the second conductive layer and the first conductive layer is facilitated, thereby improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the top structure of a flexible circuit board provided in one embodiment of the present application.

[0019] Figure 2 The first embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0020] Figure 3 The second embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0021] Figure 4 The third embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0022] Figure 5 The fourth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0023] Figure 6 The fifth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0024] Figure 7 The sixth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0025] Figure 8 The seventh embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0026] Fig. 9 The eighth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0027] Fig.10 The ninth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown.

[0028] Fig.11 for Fig.10 A partial enlarged view of the flexible circuit board shown.

[0029] Fig.12 A schematic diagram of the cross-sectional structure of a display module provided in one embodiment of the present application.

[0030] Fig.13 A schematic diagram of the structure of a display device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. When used herein, the singular forms of "one", "an" and "said / the" may also include plural forms, such as at least two or more, unless the context clearly indicates another way.

[0032] In recent years, foldable display terminal products represented by three-fold screen mobile phones have exploded the market, making foldable screens an indispensable part of the market for some time to come. In order to ensure the folding characteristics, the stacking layers of foldable display modules are all made of flexible materials, which means that when touching, the force will be more directly transmitted downward from the top protective film.

[0033] In the foldable display module, the display panel and the flexible printed circuit (FPC) are electrically connected using the flexible printed circuit on panel (FPC on panel, FOP) bonding process. After the FPC is bent, its connection end is bound to the mobile phone motherboard, and the FPC is in a static bent state.

[0034] When the user continuously touches the mobile phone screen with a single point, the bending area of ​​the FPC will continue to vibrate under external force. Under the continuous force, the FPC fatigues and fails, resulting in circuit breakage. Generally, the number of touches is ≤ 100,000 times.

[0035] In order to improve the micro-motion performance of FPC, the present application optimizes the stacking design of FPC and reasonably matches and selects materials to adjust the structure of FPC, thereby improving the micro-motion performance of FPC.

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. It is understood that when a structure is referred to as being "on or under" another structure, the structure may be directly on or under the other structure, or there may be intermediate structures. The same reference numerals always indicate the same structure. The structures mentioned herein include any of a film layer, an element, a device, a component, and an assembly.

[0038] When a structure is referred to as being “connected” to another structure, the structure may be directly connected to the other structure or indirectly connected to the other structure with one or more intervening structures interposed therebetween.

[0039] In this specification, "electrical connection" includes the case where components are connected together through an element having some electrical function. There is no particular limitation on the "element having some electrical function" as long as it can transmit and receive electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having various functions.

[0040] Figure 1 A schematic diagram of the top structure of a flexible circuit board provided in one embodiment of the present application. Figure 2 The first embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible printed circuit board along the N1N2 line is shown. Figure 1 and Figure 2 As shown, the flexible circuit board has a main board area A and a bending area S that are adjacently arranged. The flexible circuit board includes: a first substrate layer 111 and a plurality of conductive layers, and the plurality of conductive layers are stacked on at least one side of the first substrate layer 111. The plurality of conductive layers include a first conductive layer 121 and a second conductive layer 122, the first conductive layer 121 extends from the main board area A to the bending area S, and the second conductive layer 122 is located in the main board area A. The first conductive layer 121 has a better bending resistance than the second conductive layer 122.

[0041] The flexible circuit board serves as an electrical connection and is used to connect the display panel and the main board to achieve signal transmission and data exchange between the display panel and the main board.

[0042] The mainboard area A is provided with components and wires arranged in three-dimensional space. The components are coupled with the wires to form a circuit structure with predetermined functions. The bending area S is provided with an impedance line to match the signal requirements of customers.

[0043] The conductive layer can be a single material layer or a composite structure layer in which multiple material layers are stacked. Exemplarily, the material of the first conductive layer 121 includes rolled copper; and / or, the material of the second conductive layer 122 includes electrolytic copper. Exemplarily, the material of the first conductive layer 121 includes rolled copper and electroplated copper, and the rolled copper layer and the electroplated copper layer are stacked. The material of the second conductive layer 122 includes electrolytic copper and electroplated copper, and the electrolytic copper layer and the electroplated copper layer are stacked. In this case, the rolled copper layer and the electrolytic copper layer are the basic conductive layer for forming conductivity, and the electroplated copper layer is formed on the surface of the basic conductive layer for filling the vias that penetrate the first substrate layer 111, thereby electrically connecting the basic conductive layers on both sides of the first substrate layer 111.

[0044] In one embodiment, Figure 1As shown, the first substrate layer 111 extends from the main board area A to the bending area S, and the first conductive layer 121 and the second conductive layer 122 are respectively located on both sides of the first substrate layer 111. In this case, the first substrate layer 111 can provide support for the first conductive layer 121 and the second conductive layer 122.

[0045] In one embodiment, the first substrate layer 111 is a substrate with a relatively small modulus, which may be an organic insulating layer. Exemplarily, the modulus of the first substrate layer 111 is less than or equal to 5 GPa. In this way, the stress and deformation generated in the first substrate layer 111 during static bending can be reduced, and the modulus here is mainly Young's modulus.

[0046] According to the flexible circuit board provided in this embodiment, by setting the first conductive layer 121 to extend from the main board area A to the bending area S, the second conductive layer 122 is located in the main board area A, and the bending resistance of the first conductive layer 121 is better than that of the second conductive layer 122, it can ensure the electrical quality of the main board area A while ensuring the bending characteristics of the bending area S, thereby improving the micro-motion performance of the bending area S, reducing the problem of wire breakage caused by touch vibration in the bending area S, and improving the service life.

[0047] At the same time, the bending resistance of the first conductive layer 121 is better than that of the second conductive layer 122, and accordingly, the deformation amount of the second conductive layer 122 under pressure is smaller than that of the first conductive layer 121. Based on this, in the preparation process of the flexible circuit board, after the preparation of the first conductive layer 121, during the rolling process of preparing the second conductive layer 122, since the deformation amount of the second conductive layer 122 is smaller than that of the first conductive layer 121, the alignment degree of the second conductive layer 122 and the first conductive layer 121 is facilitated, thereby improving the product yield.

[0048] Figure 3 The second embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 3 The flexible circuit board and Figure 2 The difference between the flexible circuit board shown is that, in this embodiment, the first conductive layer 121 and the second conductive layer 122 are located on the same side of the first substrate layer 111 .

[0049] Exemplarily, the first conductive layer 121 is located between the first substrate layer 111 and the second conductive layer 122. In this case, the flexible circuit board further includes the second substrate layer 112 and the first adhesive layer 131. The second substrate layer 112 is located in the main board area A and between the second conductive layer 122 and the first conductive layer 121. The first adhesive layer 131 is located between the second substrate layer 112 and the first conductive layer 121. That is, the flexible circuit board is formed by bonding two substrates through the first adhesive layer 131, one of which is composed of the first substrate layer 111 and the first conductive layer 121, and the other is composed of the second substrate layer 112 and the second conductive layer 122.

[0050] In one embodiment, the modulus of the second substrate layer 112 is greater than that of the first substrate layer 111 , that is, the modulus of the first substrate layer 111 is smaller than that of the second substrate layer 112 .

[0051] Figure 4 The third embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 4 The flexible circuit board and Figure 3 The difference of the flexible circuit board shown is that in this embodiment, the plurality of conductive layers further include a third conductive layer 123, which is located on the side of the first substrate layer 111 away from the first conductive layer 121. The third conductive layer 123 extends from the main board area A to the bending area S.

[0052] In one embodiment, the third conductive layer 123 has better bending resistance than the second conductive layer 122. Exemplarily, the third conductive layer 123 is made of the same material as the first conductive layer 121. For example, the material of the third conductive layer 123 includes rolled copper.

[0053] In this case, the flexible circuit board is formed by two substrates bonded together by a first adhesive layer 131 , wherein one substrate is formed by a first base material layer 111 , a first conductive layer 121 and a third conductive layer 123 , and the other substrate is formed by a second base material layer 112 and a second conductive layer 122 .

[0054] According to the flexible circuit board provided in this embodiment, the third conductive layer 123 is arranged to extend from the main board area A to the bending area S, and the bending resistance of the third conductive layer 123 is better than that of the second conductive layer 122, thereby ensuring the bending characteristics of the bending area S, thereby improving the micro-motion performance of the bending area S, reducing the problem of wire breakage caused by touch vibration in the bending area S, and improving the service life.

[0055] Figure 5 The fourth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 5 The flexible circuit board and Figure 4The difference of the flexible circuit board shown is that, in this embodiment, the third conductive layer 123 is located in the main board area A.

[0056] The bending resistance of the third conductive layer 123 is inferior to that of the first conductive layer 121. In one embodiment, the material of the third conductive layer 123 is the same as that of the second conductive layer 122. Exemplarily, the material of the third conductive layer 123 includes electrolytic copper.

[0057] Figure 6 The fifth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 6 The flexible circuit board and Figure 4 , Figure 5 The difference between the flexible circuit board shown is that Figure 4 Taking the flexible circuit board shown in the figure as an example, in this embodiment, the flexible circuit board further includes a fourth conductive layer 124, which is located on the side of the third conductive layer 123 away from the first substrate layer 111. The fourth conductive layer 124 is located in the main board area A.

[0058] In one embodiment, the flexible circuit board further includes a second adhesive layer 132 and a third substrate layer 113. The second adhesive layer 132 is located between the third conductive layer 123 and the fourth conductive layer 124. The third substrate layer 113 is located on the side of the fourth conductive layer 124 away from the first substrate layer 111. In this case, the flexible circuit board is formed by bonding three substrates. The first substrate includes the first substrate layer 111, the first conductive layer 121 and the third conductive layer 123, the second substrate includes the second substrate layer 112 and the second conductive layer 122, and the third substrate includes the third substrate layer 113 and the fourth conductive layer 124. The first substrate and the second substrate are bonded by the first adhesive layer 131, and the first substrate and the third substrate are bonded by the second adhesive layer 132.

[0059] In one embodiment, the bending resistance of the fourth conductive layer 124 is inferior to that of the first conductive layer 121. Exemplarily, the fourth conductive layer 124 is made of the same material as the second conductive layer 122. For example, the material of the fourth conductive layer 124 includes electrolytic copper.

[0060] In one embodiment, the modulus of the third substrate layer 113 is greater than that of the first substrate layer 111 , that is, the modulus of the first substrate layer 111 is smaller than that of the third substrate layer 113 .

[0061] Figure 7 The sixth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 7 The flexible circuit board and Figure 6The difference between the flexible circuit board shown is that, in this embodiment, the flexible circuit board further includes a fifth conductive layer 125 , which is located on a side of the fourth conductive layer 124 away from the first substrate layer 111 and is located in the main board area A.

[0062] In one embodiment, the bending resistance of the fifth conductive layer 125 is inferior to that of the first conductive layer 121. Exemplarily, the material of the fifth conductive layer 125 is the same as that of the second conductive layer 122. For example, the material of the fifth conductive layer 125 includes electrolytic copper.

[0063] In one embodiment, the flexible circuit board further includes a sixth conductive layer 126, which is located on the side of the fifth conductive layer 125 away from the first substrate layer 111 and located in the main board area A. Exemplarily, the bending resistance of the sixth conductive layer 126 is inferior to that of the first conductive layer 121. For example, the material of the sixth conductive layer 126 is the same as that of the second conductive layer 122, both of which are electrolytic copper.

[0064] In one embodiment, the flexible circuit board further includes a fourth substrate layer 114 and a third adhesive layer 133. The fourth substrate layer 114 is located between the fifth conductive layer 125 and the sixth conductive layer 126. The third adhesive layer 133 is located between the fifth conductive layer 125 and the fourth substrate layer 114.

[0065] Figure 8 The seventh embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Figure 8 The difference between the flexible circuit board shown in the figure and the flexible circuit board provided in any of the above embodiments is that Figure 7 Taking the flexible circuit board shown in the figure as an example, in this embodiment, the flexible circuit board further includes: a first protective film (Cover Layer, CVL) 141 and a second protective film 142. The first protective film 141 is located on the side of at least one conductive layer on the first side of the first substrate layer 111 away from the first substrate layer 111, and extends from the main board area A to the bending area S. The second protective film 142 is located on the side of at least one conductive layer on the second side of the first substrate layer away from the first substrate layer 111, and extends from the main board area A to the bending area S.

[0066] Exemplarily, the first protective film 141 and the second protective film 142 are made of the same material, such as polyethylene terephthalate (PET), polyurethane (PU) or other polymer materials. Either the first protective film 141 or the second protective film 142 is used to protect the conductive layer, prevent oxidation of the conductive layer, and increase wear resistance and stain resistance, thereby improving product reliability and service life.

[0067] In one embodiment, the number of conductive layers on the first side of the first substrate layer 111 is less than the number of conductive layers on the second side of the first substrate layer 111 .

[0068] Fig. 9 The eighth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Fig. 9 The flexible circuit board and Figure 8 The difference between the flexible circuit board provided in the illustrated embodiment is that, in the present embodiment, the flexible circuit board further includes a first support layer 151 and a second support layer 152. The first support layer 151 is provided in the same layer as the first protective film 141 and is located in the bending zone S. In one embodiment, the first protective film 141 is in contact with the first support layer 151. Exemplarily, the first support layer 151 and the second support layer 152 are made of the same material, both of which are steel sheets. In this case, the bending direction Y of the bending zone S is toward the side of the second support layer 152, that is, the bending zone S can be bent toward the side of the second support layer 152.

[0069] In one embodiment, the orthographic projections of the first protection film 141 and the first supporting layer 151 on the first substrate layer 111 are both located within the orthographic projection range of the second protection film 142 on the first substrate layer 111 .

[0070] In one embodiment, the flexible circuit board further includes a second supporting layer 152 , which is located on a side of the second protection film 142 away from the first substrate layer 111 and is located in the main board area A.

[0071] Fig.10 The ninth embodiment of the present application provides Figure 1 The cross-sectional structure diagram of the flexible circuit board along the N1N2 line is shown in FIG. Fig.10 The flexible circuit board and Fig. 9 The difference between the flexible circuit board shown is that, in this embodiment, the first protective film 141 includes a first portion a and a second portion b arranged adjacent to each other, the first portion a covers the side wall of at least one conductive layer, and the second portion b is located in the bending zone S. The second protective film 142 includes a fourth portion d and a fifth portion e arranged adjacent to each other, the fourth portion d covers the side wall of at least one conductive layer, and the fifth portion e is located in the bending zone S. The flexible circuit board also includes a third adhesive portion 161 and a fourth adhesive portion 162. The third adhesive portion 161 is located on the side of the first protective film 141 away from the first substrate layer 111, and is located at the junction of the first portion a and the second portion b. The fourth adhesive portion 162 is located on the side of the second protective film 142 away from the first substrate layer 111, and is located at the junction of the fourth portion d and the fifth portion e.

[0072] In one embodiment, the first protection film 141 further includes a third portion c located on the side of the first portion a away from the second portion b and located in the main board region A. The second protection film 142 further includes a sixth portion f located on the side of the fourth portion d away from the fifth portion e and located in the main board region A.

[0073] According to the flexible circuit board provided in this embodiment, on the one hand, by setting the third glue part 161, the first bending force point Q1 is changed from the junction of the first part a and the second part b to the right edge of the third glue part 161, and the junction of the first part a and the second part b is the first stress point Q2, so that the first bending force point Q1 and the first stress point Q2 are separated, thereby realizing the protection of the first stress point Q1. On the other hand, by setting the fourth glue part 162, the second bending force point Q3 is changed from the junction of the fourth part d and the fifth part e to the right edge of the fourth glue part 162, and the junction of the fourth part d and the fifth part e is the second stress point Q4, so that the second bending force point Q3 and the second stress point Q4 are separated, thereby realizing the protection of the second stress point Q3. Combining the above two aspects, the stress point at the intersection of the multi-layer conductive layer can be protected to ensure that the force point is away from the stress point, that is, the stress concentration area during the micro-motion process.

[0074] Fig.11 for Fig.10 A partial enlarged view of the flexible circuit board shown. Fig.10 and Fig.11 As shown, the ratio of the thickness of at least one of the third adhesive portion 161 and the fourth adhesive portion 162 to the thickness of the bending zone S is 0.8-2. For example, the ratio D1 / D of the first thickness D1 of the third adhesive portion 161 and the total thickness D of the laminated layer of the bending zone S is 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, etc. The ratio D2 / D of the second thickness D2 of the fourth adhesive portion 162 and the total thickness D of the laminated layer of the bending zone S is 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, etc. Exemplarily, the third adhesive portion 161 and the fourth adhesive portion 162 have equal thickness.

[0075] In one embodiment, in combination Fig. 9 and Fig.10 As shown, in the direction from the main board area A to the bending area S, the length of at least one of the third adhesive portion 161 and the fourth adhesive portion 162 accounts for 4%-15% of the length of the bending area S. L1 / L may be 4%-15%. L2 / L may be 4%-15%. For example, the first length L1 of the third adhesive portion 161 accounts for 4%, 8%, 10%, 12%, 15% of the length L of the bending area S, etc. The second length L2 of the fourth adhesive portion 162 accounts for 4%, 8%, 10%, 12%, 15% of the length L of the bending area S, etc. Exemplarily, the lengths of the third adhesive portion 161 and the fourth adhesive portion 162 are equal.

[0076] In one embodiment, the modulus of the third adhesive portion 161 is greater than that of the fourth adhesive portion 162. Since the bending area S can be bent toward the second supporting layer 152, the bending stress on the third adhesive portion 161 is greater than that on the fourth adhesive portion 162. In this case, setting the modulus of the third adhesive portion 161 to be greater than that of the fourth adhesive portion 162 can better release the bending stress, improve the micro-motion performance of the flexible circuit board, and thus improve the service life of the product.

[0077] The present application also provides a display module. Fig.12 Schematic diagram of the cross-sectional structure of a display module provided in one embodiment of the present application. Fig.12 As shown, the display module includes a display panel 20 and a flexible circuit board 10 provided in any of the above embodiments. The flexible circuit board 10 also includes a conductive pad 170 located in the main board area A. The conductive pad 170 and the display panel 20 are bonded and connected.

[0078] In one embodiment, the display panel includes a plurality of functional layers, and each functional layer is a flexible film layer.

[0079] Fig.13 This is a schematic diagram of the structure of a display device provided by an embodiment of the present application. Fig.13 As shown, the display device includes Fig.12 The display module and the main board 30 are shown. The flexible circuit board 10 further has a terminal area P, which is located on the side of the bending area S away from the main board area A. The flexible circuit board 10 also includes a connection terminal 180, which is located in the terminal area P. The connection terminal 180 is bound to the main board 30. The bending area S is in a bent state, and the main board 30 is located on the side of the main board area A of the flexible circuit board 10 away from the display panel 20.

[0080] A display device is a product with an image display function. For example, a display device can be used to display static images, such as pictures or photos. A display device can also be used to display dynamic images, such as videos.

[0081] The display device can be a laptop computer, a mobile phone, a handheld or portable computer, a camera, a camcorder, a vehicle-mounted intelligent central control screen, a calculator, a smart watch, a GPS navigator, an electronic photo, an electronic billboard or sign, a projector, etc.

[0082] In addition, the display device may also have functions such as taking photos, recording videos, fingerprint recognition, and face recognition. Accordingly, the display device also includes at least one functional module for realizing the above functions, such as an under-screen camera, an under-screen fingerprint recognition sensor, and the like.

[0083] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0084] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A flexible circuit board, characterized in that: The flexible circuit board has a first area and a second area disposed adjacent to each other, and includes: a first substrate layer; and A plurality of conductive layers, the plurality of conductive layers being stacked on at least one side of the first substrate layer; The multiple conductive layers include a first conductive layer and a second conductive layer, the first conductive layer extends from the first area to the second area, and the second conductive layer is located in the first area; the first conductive layer has better bending resistance than the second conductive layer.

2. The flexible circuit board according to claim 1, characterized in that: The first area is a main board area, and the second area is a bending area; Preferably, the first conductive layer and the second conductive layer are located on the same side of the first substrate layer; Preferably, the first conductive layer is located between the first substrate layer and the second conductive layer; Preferably, the flexible circuit board further comprises a second substrate layer, which is located in the main board area and between the second conductive layer and the first conductive layer; Preferably, the flexible circuit board further comprises a first adhesive layer, which is located between the second substrate layer and the first conductive layer; Preferably, the first substrate layer extends from the main board area to the bending area.

3. The flexible circuit board according to claim 2, characterized in that: The plurality of conductive layers further include a third conductive layer, the third conductive layer being located on a side of the first substrate layer away from the first conductive layer; the third conductive layer extending from the main board area to the bending area, or the third conductive layer being located in the main board area; Preferably, the third conductive layer extends from the main board area to the bending area, and the bending resistance of the third conductive layer is better than that of the second conductive layer; Preferably, the third conductive layer and the first conductive layer are made of the same material.

4. The flexible circuit board according to claim 3, characterized in that: It also includes a fourth conductive layer, which is located on the side of the third conductive layer away from the first substrate layer; the fourth conductive layer is located in the main board area; Preferably, the bending resistance of the fourth conductive layer is inferior to that of the first conductive layer; Preferably, the fourth conductive layer and the second conductive layer are made of the same material; Preferably, the flexible circuit board further comprises a second adhesive layer located between the third conductive layer and the fourth conductive layer; Preferably, the flexible circuit board further comprises a third substrate layer, which is located on a side of the fourth conductive layer away from the first substrate layer.

5. The flexible circuit board according to claim 4, characterized in that: It also includes a fifth conductive layer, which is located on a side of the fourth conductive layer away from the first substrate layer and is located in the main board area; Preferably, the bending resistance of the fifth conductive layer is inferior to that of the first conductive layer; Preferably, the material of the fifth conductive layer is the same as the material of the second conductive layer; Preferably, the flexible circuit board further comprises a sixth conductive layer, which is located on a side of the fifth conductive layer away from the first substrate layer and is located in the main board area; Preferably, the bending resistance of the sixth conductive layer is inferior to that of the first conductive layer; Preferably, the material of the sixth conductive layer is the same as that of the second conductive layer; Preferably, the flexible circuit board further comprises a fourth substrate layer, which is located between the fifth conductive layer and the sixth conductive layer; Preferably, the flexible circuit board further includes a third adhesive layer located between the fifth conductive layer and the fourth substrate layer.

6. The flexible circuit board according to claim 1, characterized in that: The material of the first conductive layer comprises rolled copper; and / or The material of the second conductive layer includes electrolytic copper.

7. The flexible circuit board according to claim 2, characterized in that: Also includes: A first protective film, located on a side of at least one of the conductive layers on the first side of the first substrate layer facing away from the first substrate layer, and extending from the main board area to the bending area; and / or The second protective film is located on the second side of the first substrate layer, at least one of the conductive layers is away from the first substrate layer, and extends from the main board area to the bending area.

8. The flexible circuit board according to claim 7, characterized in that: The number of the conductive layers on the first side of the first substrate layer is smaller than the number of the conductive layers on the second side of the first substrate layer.

9. The flexible circuit board according to claim 7, characterized in that: The flexible circuit board further comprises a first supporting layer, which is arranged on the same layer as the first protective film and is located in the bending area; Preferably, the first protective film is in contact with the first supporting layer; Preferably, the flexible circuit board further comprises the second protective film, and the orthographic projections of the first protective film and the first supporting layer on the first substrate layer are both located within the orthographic projection range of the second protective film on the first substrate layer; Preferably, the flexible circuit board further comprises a second supporting layer, which is located on a side of the second protective film away from the first substrate layer and is located in the main board area.

10. The flexible circuit board according to claim 7, characterized in that: The flexible circuit board includes the first protective film, the first protective film includes a first portion and a second portion arranged adjacent to each other, the first portion covers at least one side wall of the conductive layer, and the second portion is located in the bending area; the flexible circuit board also includes a first adhesive portion, which is located on the side of the first protective film away from the first substrate layer and is located at the junction of the first portion and the second portion; and / or The flexible circuit board includes the second protective film, the second protective film includes a fourth portion and a fifth portion arranged adjacent to each other, the fourth portion covers at least one side wall of the conductive layer, and the fifth portion is located in the bending area; the flexible circuit board also includes a second adhesive portion, which is located on the side of the second protective film away from the first substrate layer and is located at the junction of the fourth portion and the fifth portion; Preferably, the ratio of the thickness of at least one of the first adhesive portion and the second adhesive portion to the thickness of the bending zone is 0.8-2; Preferably, in the direction from the main board area to the bending area, the length of at least one of the first adhesive portion and the second adhesive portion accounts for 4%-15% of the length of the bending area; Preferably, the modulus of the first adhesive portion is greater than that of the second adhesive portion; Preferably, the first protective film further includes a third portion, which is disposed adjacent to the first portion and is located on a side of the first portion away from the second portion; the third portion is located in the main board area; Preferably, the second protective film further includes a sixth portion, which is disposed adjacent to the fourth portion and located on a side of the fourth portion away from the fifth portion; the sixth portion is located in the main board area.

11. The flexible circuit board according to claim 2, characterized in that: It also includes a second substrate layer, which is located on one side of the first substrate layer and located in the main board area; the first substrate layer extends from the main board area to the bending area, and the modulus of the first substrate layer is smaller than that of the second substrate layer; Preferably, the first conductive layer is located between the first substrate layer and the second conductive layer, and the second substrate layer is located between the second conductive layer and the first conductive layer; Preferably, the flexible circuit board further comprises a third substrate layer, which is located on the side of the first substrate layer away from the second substrate layer and located in the main board area; the modulus of the first substrate layer is smaller than that of the third substrate layer; Preferably, the modulus of the first substrate layer is less than or equal to 5 GPa.

12. A display module, characterized in that: include: Display panel; and The flexible circuit board according to any one of claims 1-11, further comprising a conductive pad located in the main board area, wherein the conductive pad is bonded to the display panel.

13. A display device, characterized in that: include: The display module of claim 12, wherein the flexible circuit board further comprises a terminal area, which is located on the side of the bending area away from the main board area; the flexible circuit board further comprises a connection terminal, which is located on the terminal area; the bending area is in a bent state, and the connection terminal is located on the side of the main board area away from the display panel; and A mainboard is bound to the wiring terminals.

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