Flexible printed circuit, flexible display screen, and electronic device

Abstract

A flexible printed circuit, a flexible display screen, and an electronic device. The flexible printed circuit comprises a first conductive layer (1), a first filling layer (2) and a second conductive layer (3) which are arranged in a stacked manner; the elastic modulus of the first filling layer is less than that of the first conductive layer and that of the second conductive layer; and the first filling layer is provided with a plurality of micropores (21), the plurality of micropores are arranged at intervals, the axial direction of the micropores is parallel to the direction from the first conductive layer toward the second conductive layer, and the diameter of the micropores ranges from 1 micron to 1000 microns. The micropores facilitate reducing internal stress of the flexible printed circuit, improving the bending capability of the flexible printed circuit, and facilitating large-angle bending of the flexible printed circuit. The diameter of the micropores is relatively small, thereby avoiding stress concentration at the edges of micropore distribution, increasing the elongation at break, avoiding the generation of cracks, and improving the ability of the flexible printed circuit to withstand repeated bending and resist fatigue.

Description

Flexible circuit boards, flexible displays and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202510370514.4, filed on March 26, 2025, entitled "Flexible Circuit Board, Flexible Display Screen and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic equipment technology, and in particular to a flexible circuit board, a flexible display screen, and an electronic device. Background Technology

[0003] In the present technology, transmission lines usually adopt the structure of flexible printed circuit (FPC). With the rapid development of folding devices, while ensuring high-speed signal transmission, bending resistance has also become an important development direction for flexible printed circuits.

[0004] Currently, the bending resistance of FPC is generally poor. In foldable phones, in order to avoid dynamic bending of FPC, a through-shaft design is generally adopted. When the device is bent, FPC is easily squeezed by the shaft, which can cause the outer film material to crack. In addition, the pressure block that fixes FPC can easily introduce foreign objects such as metal shavings and dust during installation, which can cause FPC to be easily punctured when dropped, resulting in short circuits and a short service life of FPC.

[0005] Therefore, improving the bending resistance of FPCs is a key direction for extending the service life of flexible circuit boards. Summary of the Invention

[0006] The purpose of this application is to provide a flexible circuit board, a flexible display screen, and an electronic device.

[0007] In a first aspect, embodiments of this application provide a flexible circuit board, including a first conductive layer, a first filling layer, and a second conductive layer stacked together. The first filling layer is located between the first conductive layer and the second conductive layer and is fixedly connected to the first conductive layer and the second conductive layer. Both the first conductive layer and the second conductive layer are capable of transmitting electrical signals. The elastic modulus of the first filling layer is less than the elastic modulus of the first conductive layer and the elastic modulus of the second conductive layer. The first filling layer has a plurality of micropores, which are spaced apart. The axial direction of the micropores is parallel to the direction from the first conductive layer toward the second conductive layer, and the diameter of the micropores is in the range of 1 micrometer to 1000 micrometers.

[0008] For example, the elastic modulus of the first circuit layer of the first conductive layer is in the range of 50 GPa to 100 GPa.

[0009] For example, the elastic modulus of the second circuit layer of the second conductive layer is in the range of 50 GPa to 100 GPa.

[0010] For example, the elastic modulus of the first filler layer is in the range of 0.2 GPa to 2 GPa.

[0011] For example, the axial direction of the micropores is parallel to the arrangement direction of the first conductive layer and the second conductive layer.

[0012] For example, the diameter of a micropore can be the maximum size of the micropore in its radial direction.

[0013] In this embodiment, by setting micropores in the first filler layer, the material of the first filler layer is partially removed, which is equivalent to improving the flexibility of the flexible circuit board at the micropore opening, making the first filler layer easier to stretch and deform. When the first filler layer is compressed, the micropores provide space for the deformation of the first filler layer, so the local stress when the first filler layer is squeezed is smaller. In addition, since the first filler layer is connected to other stacked structures of the flexible circuit board, when the flexible circuit board is bent and deformed, the micropores also provide space for the deformation of other stacked layers, which is beneficial to releasing the stress of other stacked layers. Therefore, the micropores help reduce the internal stress of the flexible circuit board, improve the bending ability of the flexible circuit board, and facilitate the large-angle bending of the flexible circuit board.

[0014] Furthermore, due to the small diameter of the micropores, the stress at the edge of the micropores in the first filling layer is also small when the flexible circuit board is bent. This avoids cracks in the first filling layer at the edge of the micropores and between other layers after multiple bends of the flexible circuit board, thus improving the lifespan of the flexible circuit board after multiple bends and thus increasing its service life.

[0015] In some implementations, the diameter of the micropores ranges from 100 micrometers to 500 micrometers.

[0016] In this embodiment, the micropores have a small diameter and are easy to process and shape, which helps to reduce the manufacturing cost of flexible circuit boards.

[0017] In some implementations, the distance between adjacent micropores ranges from 10 micrometers to 1000 micrometers.

[0018] For example, the distance between adjacent micropores can be the distance between the centers of two adjacent micropores.

[0019] In this embodiment, the difference between the spacing between adjacent micropores and the diameter of the micropores themselves is small, the spacing between adjacent micropores is appropriate, and the density of multiple micropores is appropriate, so that the first filling layer has appropriate flexibility and support.

[0020] In some implementations, the micropores penetrate the first filling layer.

[0021] In this embodiment, the first filler layer is easy to process and shape, which helps to reduce the manufacturing cost of the first filler layer.

[0022] In some implementations, the micropores are blind pores, and the depth of the micropores is greater than or equal to 50% of the thickness of the first filler layer.

[0023] In this embodiment, one side of the first filler layer has good bending ability and good integrity, and the shape of the first filler layer itself is easy to maintain; thus, it is easy to fabricate the first filler layer with other stacked layers to form a flexible circuit board, and it is beneficial to avoid the breakage and peeling of the stacked layers in the flexible circuit board.

[0024] In some embodiments, the area where the multiple micropores are distributed on the first filling layer is called the micropore region of the first filling layer, and the ratio of the total area of ​​the multiple micropores to the total area of ​​the micropore region is greater than or equal to %.

[0025] In this embodiment, multiple micropores are formed in half or more of the area of ​​the micropore region. The density of micropores in the micropore region is relatively high, which helps to reduce the stress generated when the first filling layer undergoes structural deformation in the micropore region.

[0026] In some implementations, the ratio of the area of ​​the microvia region to the area of ​​the flexible circuit board is greater than or equal to 1% and less than or equal to 10%.

[0027] In this embodiment, the area of ​​the micro-hole region occupies only a small portion of the area of ​​the flexible circuit board. Correspondingly, the area of ​​the micro-hole region also occupies only a small portion of the area of ​​the first filling layer. The formation of the micro-hole region through local processing of the first filling layer is beneficial to improving processing efficiency. Furthermore, it is beneficial to maintain the support performance of other areas of the flexible circuit board. When the flexible circuit board is applied to a flexible display screen, it is beneficial to ensure the display effect of the flexible display screen.

[0028] In some embodiments, the flexible circuit board has a first plate, a second plate, and a third plate arranged along a first direction. When the flexible circuit board is bent, the second plate bends and the first and third plates move closer together. A plurality of microholes are located on the second plate and are divided into a plurality of sub-columns. The plurality of sub-columns are arranged along the first direction, and the plurality of microholes in each sub-column are arranged along a second direction, which is perpendicular to the first direction.

[0029] In this embodiment, the diameter of the micropores is set reasonably, and the micropores are located on the second plate. At the edge of the distribution of multiple micropores, the stress between the first filling layer and the stacked layer connected to it is more dispersed, thereby avoiding stress concentration at the edge of the micropore distribution and increasing the tensile strength at break, thus avoiding the generation of cracks and improving the multiple bending resistance and fatigue resistance of the second plate of the flexible circuit board. In the flexible display screen, it avoids problems such as peeling and light shadow caused by discontinuity, ensuring the service life and display effect of the flexible display screen.

[0030] In addition, the arrangement of multiple micro-holes is well-suited to the bending direction of the flexible circuit board, which is beneficial for the uniform deformation of the flexible circuit board in the first direction when it is bent.

[0031] In some implementations, the micropores are circular.

[0032] In this embodiment, the micropores have a simple shape and are easy to manufacture.

[0033] In some implementations, the size of the micropore in the second direction is larger than that in the first direction.

[0034] In this embodiment, the micropores are more easily deformed in the first direction than in the second direction. When the first filling layer is deformed by force, the first filling layer is more easily deformed in the first direction, which is beneficial to the release of stress.

[0035] In some implementations, the micropores in two adjacent sub-columns are staggered along the projection of the first direction.

[0036] For example, in two adjacent sub-columns, the projection of the micropores in one sub-column onto the vertical plane in the first direction is located in the middle of the interval between the projections of the micropores in the other sub-column onto the vertical plane in the first direction.

[0037] In this embodiment, when the flexible circuit board is deformed by force, multiple microholes deform accordingly. Due to the misalignment of adjacent sub-columns, the deformation of microholes in adjacent sub-columns can also be misaligned, thereby making the deformation of the material between adjacent microholes more uniform and reducing the local stress of the material between adjacent microholes.

[0038] In some embodiments, the plurality of sub-columns include a first sub-column, a second sub-column, and a third sub-column located between the centerline of the second plate and the third plate, and arranged sequentially adjacent to each other and spaced apart along the centerline of the second plate toward the third plate; wherein the distance between the first sub-column and the second sub-column is a first distance, the distance between the second sub-column and the third sub-column is a second distance, and the first distance is smaller than the second distance.

[0039] For example, along the centerline of the second plate towards the third plate, the spacing between adjacent sub-columns gradually increases.

[0040] In this embodiment, the spacing between the sub-rows in the middle of the microporous region is small, and the density of micropores is high. The spacing between the openings on both sides of the microporous region is large, and the density of micropores is low. By setting the spacing of multiple sub-rows, in this example, the density of micropores is high in the area of ​​large deformation of the flexible circuit board, and the density of micropores is low in the area of ​​small deformation of the flexible circuit board. The setting of micropores is more adapted to the deformation mode of the flexible circuit board, so that the flexible circuit board can deform evenly and has more balanced stress, which is beneficial to improving the overall life of the flexible circuit board.

[0041] In some embodiments, the material of the first filler layer includes at least one of acrylic resin and epoxy resin.

[0042] In some embodiments, the first conductive layer includes a first dielectric layer and a first circuit layer, with the first circuit layer fixed to the first dielectric layer; the first dielectric layer is located on the side of the first circuit layer opposite to the second conductive layer.

[0043] For example, the surface of the first dielectric layer opposite to the first circuit layer forms one side surface of the flexible circuit board. The flexible circuit board may not require a protective layer, which is beneficial for thinner design.

[0044] For example, when other layers are disposed opposite to the first circuit layer, the first dielectric layer can also be used to protect the first circuit layer.

[0045] In this embodiment, the first dielectric layer can provide protection for the internal stack-up of the flexible circuit board.

[0046] In some embodiments, the second conductive layer includes a second dielectric layer and a second circuit layer, with the second circuit layer fixed to the second dielectric layer; the second dielectric layer is located on the side of the second circuit layer opposite to the first conductive layer, and the surface of the second dielectric layer on the side opposite to the second circuit layer forms the other surface of the flexible circuit board.

[0047] For example, the surface of the second dielectric layer facing away from the first conductive layer can serve as the other side surface of the flexible circuit board. In this case, the flexible circuit board does not need a protective layer, which is beneficial for the thinning design of the flexible circuit board.

[0048] For example, when other stacked layers are provided on the side of the second dielectric layer away from the second circuit layer, the first dielectric layer can also be used to protect the first circuit layer.

[0049] In this embodiment, the second dielectric layer can provide protection for the internal stack-up of the flexible circuit board.

[0050] In some embodiments, the flexible circuit board further includes a first protective layer, which is fixedly connected to the first conductive layer and is located on the side of the first conductive layer opposite to the second conductive layer.

[0051] For example, the elastic modulus of the first protective layer can be in the range of 1 GPa to 10 GPa.

[0052] In this embodiment, the first protective layer can serve as a surface film layer of the flexible circuit board, thereby providing protection for the flexible circuit board and improving its applicability in different environments.

[0053] In some embodiments, the flexible circuit board further includes a second protective layer, which is fixedly connected to the second conductive layer and is located on the side of the second conductive layer opposite to the first conductive layer.

[0054] For example, the elastic modulus of the second protective layer can be in the range of 1 GPa to 10 GPa.

[0055] In this embodiment, the second protective layer can serve as a surface film layer for the flexible circuit board, thereby providing protection for the flexible circuit board and improving its applicability in different environments.

[0056] In some embodiments, the elastic modulus of the first protective layer is less than that of the first conductive layer, the elastic modulus of the second protective layer is less than that of the second conductive layer, and the elastic modulus of the first protective layer is greater than that of the second protective layer.

[0057] In this embodiment, when the flexible circuit board is bent under stress, the first protective layer is closer to the bending center than the second protective layer. At this time, the first protective layer is under pressure, and the second protective layer is under tension. Stress concentration is more likely to occur at the pressure points of the flexible circuit board. In this embodiment, because the second protective layer is more easily deformable than the first protective layer, the first protective layer is more likely to maintain its shape under pressure, while the second protective layer is more likely to deform under tension. This reduces stress concentration in the first conductive layer and makes the overall deformation of the flexible circuit board more balanced.

[0058] In some embodiments, the flexible circuit board further includes a third dielectric layer and a second filler layer, which are located between the first conductive layer and the second conductive layer.

[0059] The first filling layer connects the third dielectric layer and the first conductive layer, and the second filling layer connects the third dielectric layer and the second conductive layer.

[0060] In this embodiment, the third dielectric layer is located between the first conductive layer and the second conductive layer, and also between the first filler layer and the second filler layer, serving as a neutral layer. When the flexible circuit board deforms, one of the first conductive layer and the second conductive layer is under tension, while the other is under compression. The deformation degrees of the first conductive layer and the second conductive layer are similar, thereby making the deformation of the flexible circuit board more balanced in its thickness direction. This avoids stress concentration caused by excessive local deformation of the first or second conductive layer, thus improving the service life of the flexible circuit board.

[0061] When the bending center of the flexible circuit board is closer to the first conductive layer, the first filler layer can better release the compressive stress of the first conductive layer.

[0062] In some embodiments, the flexible circuit board further includes a third dielectric layer and a second filler layer, which are located between the first conductive layer and the second conductive layer.

[0063] The first filling layer connects the third dielectric layer and the second conductive layer, and the second filling layer connects the third dielectric layer and the first conductive layer.

[0064] In this embodiment, the third dielectric layer is located between the first conductive layer and the second conductive layer, and also between the first filler layer and the second filler layer, serving as a neutral layer. When the flexible circuit board deforms, one of the first conductive layer and the second conductive layer is under tension, while the other is under compression. The deformation degrees of the first conductive layer and the second conductive layer are similar, thereby making the deformation of the flexible circuit board more balanced in its thickness direction. This avoids stress concentration caused by excessive local deformation of the first or second conductive layer, thus improving the service life of the flexible circuit board.

[0065] When the bending center of the flexible circuit board is closer to the first conductive layer, the first filler layer can better release the tensile stress of the second conductive layer.

[0066] In some embodiments, the elastic modulus of the third dielectric layer is greater than that of the first filler layer and the second filler layer.

[0067] For example, the elastic modulus of the third dielectric layer can be in the range of 2 GPa to 10 GPa.

[0068] In this embodiment, the third dielectric layer is more rigid than the first filling layer and the second filling layer, and the third dielectric layer has a stronger ability to balance the stress on the first conductive layer and the second conductive layer.

[0069] Secondly, embodiments of this application provide a flexible display screen, including a display layer and a flexible circuit board as provided in any of the embodiments of the first aspect, wherein the display layer and the flexible circuit board are fixedly connected and stacked.

[0070] In this embodiment, the flexible circuit board has strong bending ability and a long lifespan, thus the flexible display screen has a long service life and a good display effect.

[0071] In some embodiments, the flexible display screen further includes a support layer; the display layer, flexible circuit board, and support layer are sequentially fixedly connected and stacked; or, the display layer, support layer, and flexible circuit board are sequentially fixedly connected and stacked.

[0072] Thirdly, embodiments of this application provide an electronic device, including a housing device, a circuit assembly, and a flexible display screen as provided in any embodiment of the second aspect; the housing device includes a first housing, a folding mechanism, and a second housing, the folding mechanism connecting the first housing and the second housing; the circuit assembly includes a first circuit board and a second circuit board, the first circuit board being mounted on the first housing, and the second circuit board being mounted on the second housing; the flexible display screen is mounted on the first housing and the second housing, and the first circuit board and the second circuit board communicate through the flexible circuit board of the flexible display screen.

[0073] In this embodiment, by setting a flexible circuit board inside the flexible display screen, when the electronic device needs to communicate, the communication between the first circuit board and the second circuit board can be realized through the flexible circuit board. The flexible circuit board is integrated into the flexible display screen, eliminating the need to provide space for the flexible circuit board in the housing device, which is beneficial for the thin design of the electronic device. In addition, when the flexible display screen is bent, the flexible circuit board bends simultaneously, and the flexible circuit board does not need to pass through the folding mechanism. The bending of the flexible circuit board is small, which helps to improve the service life of the flexible circuit board.

[0074] Fourthly, embodiments of this application provide an electronic device, including a first device, a second device, and a flexible circuit board as provided in any embodiment of the first aspect, wherein the first device and the second device communicate through the flexible circuit board.

[0075] In this embodiment, when the space in the electronic device is relatively small or compact, the flexible circuit board needs to be bent at a large angle; or, when the electronic device is working, the flexible circuit board needs to be bent repeatedly. The flexible circuit board in this embodiment has strong bending performance, can be bent at a large angle, and also has a high lifespan after multiple bends, thereby improving the lifespan of the electronic device. Attached Figure Description

[0076] To illustrate the technical solutions in the embodiments or background art of this application, the accompanying drawings used in the embodiments or background art of this application will be described below.

[0077] Figure 1 is a schematic diagram of the structure of the electronic device provided in the embodiments of this application when it is in the open state in some embodiments;

[0078] Figure 2 is an exploded view of the electronic device shown in Figure 1;

[0079] Figure 3 is a simplified schematic diagram of the internal structure of the electronic device shown in Figure 1 in some embodiments;

[0080] Figure 4 is a simplified schematic diagram of the flexible display screen of the electronic device shown in Figure 3;

[0081] Figure 5 is a cross-sectional structural diagram of the flexible display screen shown in Figure 3 in some embodiments when it is in a bent state;

[0082] Figure 6 is a cross-sectional view of the flexible display screen shown in Figure 2 in some other embodiments when it is in a bent state;

[0083] Figure 7 is a schematic diagram of the internal structure of the flexible circuit board shown in Figure 4 in some embodiments;

[0084] Figure 8 is a schematic diagram of the structure of the first filling layer shown in Figure 7 in some embodiments;

[0085] Figure 9 is a structural schematic diagram of the first filler layer shown in Figure 7 in some other embodiments;

[0086] Figure 10 is a structural schematic diagram of the first filling layer shown in Figure 7 in some embodiments;

[0087] Figure 11 is a structural schematic diagram of the first filling layer shown in Figure 7 in some embodiments;

[0088] Figure 12 is a structural schematic diagram of the first filling layer shown in Figure 7 in some other embodiments;

[0089] Figure 13 is a structural schematic diagram of the flexible circuit board shown in Figure 7 in some other embodiments;

[0090] Figure 14 is a structural schematic diagram of the flexible circuit board shown in Figure 7 in some other embodiments;

[0091] Figure 15 is a structural schematic diagram of the flexible circuit board shown in Figure 7 in some embodiments;

[0092] Figure 16 is a structural schematic diagram of the flexible circuit board shown in Figure 7 in some other embodiments;

[0093] Figure 17 is a structural schematic diagram of the flexible circuit board shown in Figure 7 in some other embodiments;

[0094] Figure 18 is a schematic diagram of the structure of another electronic device provided in an embodiment of this application. Detailed Implementation

[0095] The embodiments of this application are described below with reference to the accompanying drawings.

[0096] In the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation," "connection," "joining," and "joining" should be interpreted broadly. For example, "joining" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an electrical connection or a mechanical connection. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Movable connection" refers to a connection where the relative positional relationship can change after connection. "Rotary connection" refers to a connection where the relative positional relationship can change. "Sliding connection" refers to a connection where the relative positional relationship can change. Furthermore, the integrated structure obtained by a one-piece molding process means that during the formation of one of the two components, that component is connected to the other component without requiring further processing (such as bonding, welding, snap-fit ​​connections, or screw connections) to connect the two components. Components A and B can be arranged relative to each other such that component A is projected along the target direction to obtain projection C, and component B is projected along the target direction to obtain projection D, with projection C and projection D at least largely overlapping. In some embodiments, the majority overlap can be any of the following: projection C is entirely within projection D; or projection D is entirely within projection C; or projection C and projection D intersect each other, and the intersection area of ​​projection C and projection D accounts for more than 50% of projection C or projection D.

[0097] The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "upper," and "lower," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0098] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. "Multiple" means at least two.

[0099] Furthermore, the limitations on relative positional relationships mentioned in the embodiments of this application, such as parallelism and perpendicularity, are all relative to the current technological level and are not absolutely strict limitations. Slight deviations are allowed; approximations of parallelism or perpendicularity are acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. Similarly, "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0100] In some embodiments, please refer to Figures 1 and 2. Figure 1 is a structural schematic diagram of the electronic device 100 provided in the present application in some embodiments when it is in the open state, and Figure 2 is an exploded structural schematic diagram of the electronic device 100 shown in Figure 1.

[0101] The electronic device 100 includes a housing 10, a flexible display screen 20, and a circuit assembly 30. The flexible display screen 20 is disposed within the housing 10, and the circuit assembly 30 is mounted inside the housing 10. The flexible display screen 20 is exposed relative to the housing 10 and is used to display images. The housing 10 is used to move the flexible display screen 20, and the circuit assembly 30 is used for communication and controlling other components of the electronic device 100.

[0102] For example, the housing device 10 includes a first housing 101, a folding mechanism 102, and a second housing 103 connected in sequence. The folding mechanism 102 is deformable to fold or unfold the first housing 101 and the second housing 103 relative to each other. That is, the folding mechanism 102 is deformable to fold or unfold the first housing 101 and the second housing 103 relative to each other.

[0103] The first housing 101 and the second housing 103 can be unfolded relative to each other to an open state, so that the folding mechanism 102, the housing device 10, and the electronic device 100 are all in an open state. The flexible display screen 20 unfolds with the housing device 10 and is in a flattened state. For example, when the housing device 10 is in the open state, the angle between the first housing 101 and the second housing 103 can be approximately 180°. In some other embodiments, when the housing device 10 is in the open state, the angle between the two can also deviate slightly from 180°, such as 165°, 177°, or 185°.

[0104] The first housing 101 and the second housing 103 can be folded relative to each other to a closed state, so that the folding mechanism 102, the housing device 10 and the electronic device 100 are all in a closed state. The flexible display screen 20 is folded along with the housing device 10 and is in a folded state. The flexible display screen 20 is located inside the housing device 10 and is wrapped by the housing device 10.

[0105] The first housing 101 and the second housing 103 can also be unfolded or folded relative to each other to an intermediate state, so that the folding mechanism 102, the housing device 10, and the electronic device 100 are all in an intermediate state, which can be any state between the open state and the closed state. The flexible display screen 20 moves with the housing device 10.

[0106] In this embodiment, the flexible display screen 20 can be unfolded and folded along with the housing device 10. When the electronic device 100 is in the open state, the flexible display screen 20 is in a flattened state, and the flexible display screen 20 can display in full screen, giving the electronic device 100 a larger display area to improve the user's viewing and operating experience. When the electronic device 100 is in the closed state, the planar dimensions of the electronic device 100 are small (with a smaller width dimension), making it easy for users to carry and store.

[0107] When the housing device 10 is in the open state, the first housing 101 can be joined with the second housing 103. The joining of the first housing 101 and the second housing 103 includes situations where they abut against each other, and situations where there is a small gap between them. In this embodiment, by joining the first housing 101 and the second housing 103, the unfolding action of the housing device 10 can be stopped, preventing the housing device 10 from over-folding during unfolding, thereby reducing the stress on the flexible display screen 20 and improving the reliability of the flexible display screen 20 and the electronic device 100.

[0108] Furthermore, when the housing device 10 is in the closed state, the first housing 101 and the second housing 103 can be completely closed without any large gaps between them. This results in a better appearance for both the housing device 10 and the electronic device 100, as well as improved waterproof, dustproof, and foreign object protection performance. The complete closure of the first housing 101 and the second housing 103 includes situations where they are mutually resisting each other, and also situations where there is a small gap between them. When there is a small gap between the first housing 101 and the second housing 103, foreign objects from outside the electronic device 100 (such as nails, paper clips, glass shards, etc.) will not enter between the first housing 101 and the second housing 103 through this gap, thus preventing damage to the flexible display screen 20 and improving the reliability of the electronic device 100.

[0109] In some examples, the first housing 101 may include a first middle frame 1011 and a first cover plate 1012. The first middle frame 1011 can serve as the main structure of the first housing 101, supporting most of the components inside the first housing 101. The first cover plate 1012 can be fastened to the side of the first middle frame 1011 facing away from the flexible display screen 20, thereby enclosing the first middle frame 1011 to protect the components inside the first middle frame 1011. For example, the first cover plate 1012 can be bonded to the first middle frame 1011 using an adhesive.

[0110] In some examples, the second housing 103 may include a second middle frame 1031 and a second cover plate 1032. The second middle frame 1031 can serve as the main structure of the second housing 103, supporting most of the components inside the second housing 103. The second cover plate 1032 can be fastened to the side of the second middle frame 1031 facing away from the flexible display screen 20, thereby enclosing the second middle frame 1031 to protect the components inside. For example, the second cover plate 1032 can be bonded to the second middle frame 1031 using an adhesive. The second housing 103 may have through holes to allow for the obstruction of the camera module.

[0111] In some embodiments, the flexible display screen 20 includes a first portion 201, a second portion 202, and a third portion 203 arranged sequentially. The first portion 201 is fixedly connected to a first housing 101, and the third portion 203 is fixedly connected to a second housing 103. During the relative folding or unfolding of the first housing 101 and the second housing 103, the second portion 202 deforms. During the relative folding or unfolding of the first housing 101 and the second housing 103, the first housing 101 drives the first portion 201 to move, and the second housing 103 drives the third portion 203 to move, thus causing the first portion 201 and the third portion 203 to fold or unfold relative to each other.

[0112] In some embodiments, the flexible display screen 20 can be an organic light-emitting diode (OLED) flexible display screen, an active-matrix organic light-emitting diode (AMOLED) flexible display screen, a mini organic light-emitting diode (MOLED) flexible display screen, a micro light-emitting diode (MLED) flexible display screen, or a quantum dot light-emitting diode (QLED) flexible display screen.

[0113] For example, the first housing 101 includes a first support surface 1013 for supporting the flexible display screen 20, and the second housing 103 includes a second support surface 1033 for supporting the flexible display screen 20. For example, a first portion 201 of the flexible display screen 20 can be fixedly connected to the first support surface 1013 of the first housing 101. For example, the first portion 201 can be bonded to the first support surface 1013 of the first housing 101 using an adhesive layer. A third portion 203 is fixedly connected to the second support surface 1033 of the second housing 103. For example, the first portion 201 can be bonded to the second support surface 1033 of the second housing 103 using an adhesive layer.

[0114] In this embodiment, since the first part 201 is fixedly connected to the first housing 101 and the third part 203 is fixedly connected to the second housing 103, when the first housing 101 and the second housing 103 are folded or unfolded relative to each other, the relative folding and unfolding actions between the first part 201 and the third part 203 can be accurately controlled, making the deformation process and movement shape of the flexible display screen 20 controllable and highly reliable.

[0115] In some embodiments, the circuit assembly 30 may include a first circuit board 301 and a second circuit board 302. The first circuit board 301 is fixedly connected to the first housing 101, and the second circuit board 302 is fixedly connected to the second housing 103. The first circuit board 301 and the second circuit board 302 can communicate with each other.

[0116] The first circuit board 301 can be fixed to the first middle frame 1011, and the second circuit board 302 can be fixed to the second middle frame 1031. The first circuit board 301 and the second circuit board 302 do not need to be in contact, and they can transmit wireless signals to each other. For example, the first circuit board 301 and the second circuit board 302 can transmit display signals, CAM signals, radio frequency signals, and audio signals, so that the first circuit board 301 and the second circuit board 302 can work together to control the electronic device 100.

[0117] Both the first circuit board 301 and the second circuit board 302 may include circuit boards and functional modules. Functional modules may be mounted on the circuit boards and include, but are not limited to, processors, antenna modules, Bluetooth modules, WiFi (Wireless-Fidelity) modules, power management modules, and screen display and operation modules. Functional modules may also include microphone interfaces, speaker interfaces, camera interfaces, and interfaces for the flexible display screen 20. This embodiment does not strictly limit the functional modules. In some examples, the functional modules of the first circuit board 301 and the second circuit board 302 may be the same or different, depending on the requirements.

[0118] In some embodiments, the electronic device 100 may further include multiple modules (not shown in the figures), which may be housed inside the housing device 10. The multiple modules of the electronic device 100 may include, but are not limited to, a battery, a camera module, a handset module, a speaker module, a microphone module, a sensor module, etc. The embodiments of this application do not specifically limit the number, type, or location of the modules of the electronic device 100.

[0119] It is understood that when a user holds the electronic device 100, the position of the earpiece module of the electronic device 100 can be defined as the top of the electronic device 100, the position of the microphone module of the electronic device 100 can be defined as the bottom of the electronic device 100, and the two sides of the electronic device 100 held by the user's left and right hands can be defined as the left and right sides of the electronic device 100. In some embodiments, the electronic device 100 can be folded horizontally. In other embodiments, the electronic device 100 can be folded vertically.

[0120] It is understood that, taking the open state of electronic device 100 as an example, electronic device 100 has a width direction, a length direction, and a thickness direction. The width direction is the X direction, the length direction is the Y direction, and the thickness direction is the Z direction. The X, Y, and Z directions are perpendicular to each other. This embodiment is illustrated by the example that "the rotation axis of electronic device 100 is parallel to the length direction of electronic device 100". In this case, electronic device 100 can rotate left and right, and the folding and unfolding of electronic device 100 affects the width dimension of electronic device 100. In the relevant description of electronic device 100, the side of electronic device 100 with flexible display screen 20 is called "top", and the side of electronic device 100 away from flexible display screen 20 is called "bottom". In some other embodiments, the rotation axis of electronic device 100 can also be parallel to the width direction of electronic device 100. In this case, electronic device 100 can rotate up and down, and the folding and unfolding of electronic device 100 affects the length dimension of electronic device 100.

[0121] Please refer to Figure 3, which is a schematic diagram of the internal structure of the electronic device 100 shown in Figure 1 in some embodiments.

[0122] In some embodiments, the flexible display screen 20 may include a display layer 204, a flexible circuit board 205, and a support layer 206 stacked together. The display layer 204, flexible circuit board 205, and support layer 206 may form a stacked structure, with the flexible circuit board 205 located between the display layer 204 and the support layer 206. The flexible circuit board 205 connects the support layer 206 and the display layer 204. In the electronic device, the display layer 204 is located on the side of the flexible circuit board 205 facing away from the circuit assembly 30.

[0123] Here, display layer 204 refers to the structure in flexible display screen 20 used for displaying images. The display portion of display layer 204 generally includes multiple light-emitting elements, which work together to display images. It can be understood that display layer 204 can emit light towards the top.

[0124] For example, the support layer 206 can be a flexible membrane structure. The support layer 206 is used to support the display layer 204, and the shape of the support layer 206 can be consistent with the shape of the display layer 204.

[0125] For example, the flexible circuit board 205 can be a thin-film structure, and its shape can be substantially consistent with the shape of the display layer 204. The flexible circuit board 205 can be relatively thin to facilitate the thinning of the flexible display screen 20. It is understood that the flexible circuit board 205 is capable of transmitting electrical signals.

[0126] In this embodiment, by stacking the display layer 204 and the flexible circuit board 205, it is convenient to form the flexible display screen 20 and the thickness of the flexible display screen 20 is basically the same everywhere, resulting in good overall integrity of the flexible display screen 20. Furthermore, the flexible circuit board 205 is coupled inside the flexible display screen 20, enabling the flexible display screen 20 to transmit wireless signals and improving the integration of the flexible display screen 20.

[0127] In some embodiments, the flexible circuit board 205 may be electrically connected to the first circuit board 301 and the second circuit board 302 so that the first circuit board 301 and the second circuit board 302 can communicate.

[0128] For example, the portion of the flexible circuit board 205 connected to the first housing 101 may extend relative to the display layer 204 and be electrically connected to the first circuit board 301 after passing through the first housing 101. The portion of the flexible circuit board 205 connected to the second housing 103 may extend relative to the display layer 204 and be electrically connected to the second circuit board 302 after passing through the second housing 103.

[0129] By setting a flexible circuit board 205 inside the flexible display screen 20, when communication is required inside the electronic device 100, communication between the first circuit board 301 and the second circuit board 302 can be achieved through the flexible circuit board 205. The flexible circuit board 205 is integrated into the flexible display screen 20, eliminating the need to provide space for the flexible circuit board 205 in the housing device, which is beneficial for the thin design of the electronic device 100. In addition, when the flexible display screen 20 is bent, the flexible circuit board 205 bends simultaneously. The flexible circuit board 205 does not need to pass through the folding mechanism 102, and the bending of the flexible circuit board 205 is smaller, which helps to improve the service life of the flexible circuit board 205.

[0130] Please refer to Figures 4 and 5. Figure 4 is a simplified structural diagram of the flexible display screen 20 of the electronic device 100 shown in Figure 3, and Figure 5 is a cross-sectional structural diagram of the flexible display screen 20 shown in Figure 3 in some embodiments when it is in a bent state.

[0131] In some embodiments, the ratio of the area of ​​the flexible circuit board 205 to the area of ​​the display layer 204 is in the range of 0.9 to 1. In this case, the shape of the flexible circuit board 205 can be substantially consistent with the shape of the display layer 204, making it easy to form a stacked structure between the flexible circuit board 205 and the display layer 204.

[0132] For example, in a direction perpendicular to the flexible display screen 20, the flexible circuit board 205 overlaps with the display layer 204 (overlap of 90% or more is considered sufficient). Alternatively, the area of ​​the flexible circuit board 205 can be slightly smaller than the area of ​​the display layer 204, allowing for slight misalignment at the edges of the flexible circuit board 205 and the display layer 204, or subtle differences in shape at the edges. In this case, the flexible circuit board 205 is easily stacked and connected with the display layer 204, resulting in a flexible display screen 20 with a substantially uniform thickness. This makes the flexible display screen 20 easier to install, increases its reliability, and provides a better user experience.

[0133] The flexible circuit board 205 can be flexible, and can bend synchronously when the flexible display screen 20 is bent. For example, the main bending area of ​​the flexible display screen 20 can be the second part 202, and the structure of the flexible circuit board 205 located in the second part 202 can also be bent.

[0134] It is understandable that the flexible display screen 20 may also include other stacked structures, such as an encapsulation layer with encapsulation function, a flexible layer with flexible support function, etc.

[0135] In some other embodiments, the shape of the flexible circuit board 205 may not be consistent with the shape of the flexible display screen 20, and the size of the flexible circuit board 205 may be much smaller than the size of the flexible display screen 20.

[0136] Referring to Figure 5, in some embodiments, the flexible display screen 20 may include a first adhesive layer 207 and a second adhesive layer 208. The flexible circuit board 205 is bonded to the display layer 204 via the first adhesive layer 207 and to the support layer 206 via the second adhesive layer 208. Both the first adhesive layer 207 and the second adhesive layer 208 may be made of adhesive material.

[0137] In some embodiments, the flexible circuit board 205 may include a first board 2021, a second board 2022, and a third board 2023. The second board 2022 is fixedly connected to the first board 2021 and the third board 2023.

[0138] For example, when the flexible circuit board 205 is in a flattened state, that is, when the flexible circuit board 205 is not bent, the first board 2021, the second board 2022, and the third board 2023 can be arranged along a first direction. For example, the first direction can be parallel to the X direction.

[0139] For example, the first plate 2021 corresponds to the first part 201 of the flexible display screen 20, the second plate 2022 corresponds to the second part 202 of the flexible display screen 20, and the third plate 2023 corresponds to the third part 203 of the flexible display screen 20. Therefore, the second plate 2022 can have better bending performance, so that the second part 202 of the flexible display screen 20 has good bending performance.

[0140] For example, the flexible display screen 20 can be bent towards the top side, in which case the flexible display screen 20 can be bent towards the top side of the display layer 204, and the flexible display screen 20 is folded inward. In some other examples, the flexible display screen 20 can be bent towards the bottom side, and the flexible display screen 20 is folded outward.

[0141] When the flexible display screen 20 is bent, the second part 202 of the flexible display screen 20 bends, while the first and third parts of the flexible display screen 20 remain essentially flat. Because the flexible display screen 20 has a layered structure, there is mutual stretching and compression between the layers. In the flexible circuit board 205, the second plate 2022 bends, while the first plate 2021 and the third plate 2023 move closer together, and the first plate 2021 and the third plate 2023 remain essentially flat.

[0142] In some embodiments, the support layer 206 may be provided with openings. The number of openings may be multiple. The openings may be located in the region of the second portion 202 of the flexible display screen 20 in the support layer 206. By providing openings in the support layer 206, when the flexible display screen 20 is bent, the openings in the support layer 206 can reduce the bending stress of the flexible display screen 20 and improve the lifespan of the flexible display screen 20.

[0143] Please refer to Figure 6, which is a cross-sectional view of the flexible display screen 20 shown in Figure 2 in a bent state in some other embodiments. The flexible display screen 20 shown in the embodiment of Figure 6 may include most of the technical features of the flexible display screen 20 in the embodiment of Figure 5. The technical features that are the same in both will not be repeated here; the following mainly describes the differences between the two.

[0144] In some embodiments, the display layer 204, flexible circuit board 205, and support layer 206 can form a stacked structure, with the flexible circuit board 205 located between the display layer 204 and the support layer 206. The display layer 204 is fixed to the flexible circuit board 205, and the flexible circuit board 205 is fixed to the support layer 206. The arrangement of the display layer 204, flexible circuit board 205, and support layer 206 can be referred to the relevant arrangement in the embodiment of Figure 4, and will not be repeated in this embodiment.

[0145] For example, the flexible circuit board 205 is bonded to the support layer 206 via the first adhesive layer 207.

[0146] In this embodiment, the display layer 204 and the support layer 206 sandwich the flexible circuit board 205. Both sides of the flexible circuit board 205 are covered by the display layer 204 and the support layer 206, respectively. Most of the structure of the flexible circuit board 205 does not come into contact with the external environment. The display layer 204 and the support layer 206 jointly protect the flexible circuit board 205, providing stronger protection. Furthermore, when the flexible display screen 20 is bent, the bending degree of the flexible circuit board 205 is basically the same as that of the flexible display screen 20, minimizing the bending degree of the flexible circuit board 205. This results in lower stress on the stacked layers of the flexible circuit board 205 and a longer service life for the flexible display screen 20.

[0147] Please refer to Figure 7, which is a schematic diagram of the internal structure of the flexible circuit board 205 shown in Figure 4 in some embodiments.

[0148] In some embodiments, the flexible circuit board 205 includes a first conductive layer 1, a first filler layer 2, and a second conductive layer 3. The first filler layer 2 is located between the first conductive layer 1 and the second conductive layer 3.

[0149] The first conductive layer 1 can be used to transmit electrical signals. The first conductive layer 1 may include a first dielectric layer 11 and a first circuit layer 12, and the first circuit layer 12 may be fixed to the first dielectric layer 11.

[0150] For example, the first dielectric layer 11 can serve as the substrate of the first conductive layer 1. The first dielectric layer 11 can be made of a flexible material, allowing the first conductive layer 1 to deform. For example, the first dielectric layer 11 can be made of a polymer material, such as polyimide (PI), polyethylene terephthalate (PET), etc. The first dielectric layer 11 can also be made of an inorganic material, such as glass. For example, the elongation at break of the first dielectric layer 11 can be greater than or equal to 20%.

[0151] For example, the first circuit layer 12 is used for signal transmission. The first circuit layer 12 may be made of a highly conductive material to enable the first conductive layer 1 to transmit signals at high speed. For example, the first circuit layer 12 may be made of copper, titanium copper, aluminum, or an aluminum alloy.

[0152] For example, in the first conductive layer 1, a conductive material can be grown from the surface of the first dielectric layer 11 first, and then a circuit can be formed by etching or other processes to form the first circuit layer 12. For example, the first circuit layer 12 can form a mesh circuit.

[0153] It should be noted that Figure 7 illustrates one embodiment of the first dielectric layer 11 and the first circuit layer 12 being arranged in layers. This illustration is only used to show the structural composition of the first conductive layer 1 and does not constitute a limitation on the specific form of the first dielectric layer 11 and the first circuit layer 12. In some embodiments, the first dielectric layer 11 and the first circuit layer 12 may be arranged at least partially in the same layer, or the first conductive layer 1 may be a composite layer in which the first dielectric layer 11 and the first circuit layer 12 are interlocked.

[0154] The first filling layer 2 can be used to connect the first conductive layer 1 and the second conductive layer 3.

[0155] For example, one side surface of the first filler layer 2 contacts and is fixedly connected to the first conductive layer 1, and the other side surface of the first filler layer 2 contacts and is fixedly connected to the second conductive layer 3. The area of ​​the first filler layer 2 can be equal to the area of ​​the first conductive layer 1 and / or the second conductive layer 3, that is, the size of the first filler layer 2 can substantially cover the size of the flexible circuit board 205.

[0156] For example, the first filler layer 2 may be made of an adhesive material. For instance, the first filler layer 2 may be made of at least one of materials such as acrylic resin and epoxy resin.

[0157] For example, the first filler layer 2 may also be flexible, so that the flexible circuit board 205 is flexible.

[0158] The second conductive layer 3 can be used to transmit electrical signals. The second conductive layer 3 may include a second dielectric layer 31 and a second circuit layer 32, and the second circuit layer 32 may be fixed to the second dielectric layer 31.

[0159] For example, the second dielectric layer 31 can serve as the substrate of the second conductive layer 3. The second dielectric layer 31 can be made of a flexible material, allowing the second conductive layer 3 to deform. For instance, the second dielectric layer 31 can be made of a polymer material, such as polyimide (PI) or polyethylene terephthalate (PET). The second dielectric layer 31 can also be made of an inorganic material, such as glass. For example, the elongation at break of the second dielectric layer 31 can be greater than or equal to 20%.

[0160] For example, the second circuit layer 32 is used for signal transmission. The second circuit layer 32 can be made of a highly conductive material to enable the second conductive layer 3 to transmit signals at high speed. For example, the second circuit layer 32 can be made of copper, titanium copper, aluminum, or aluminum alloy.

[0161] For example, in the second conductive layer 3, a conductive material can be grown from the surface of the second dielectric layer 31 first, and then the circuit is formed by etching and other processes to form the second circuit layer 32.

[0162] For example, the materials of the second dielectric layer 31 and the second circuit layer 32 may be the same as or different from the materials of the first dielectric layer 11 and the first circuit layer 12. This embodiment does not make specific limitations in this regard.

[0163] The first filling layer 2, the first conductive layer 1, and the second conductive layer 3 can each be a separate film layer, which are then hot-pressed to form the flexible circuit board 205. However, the forming method of the flexible circuit board 205 is not limited to this.

[0164] In this embodiment, the first filler layer 2 acts as an adhesive, connecting the first conductive layer 1 and the second conductive layer 3 to form a flexible circuit board 205 that can be bent and deformed. Furthermore, the flexible circuit board 205 is relatively thin, which helps to reduce the degree of deformation of each layer when bent, thereby reducing stress concentration.

[0165] It is understood that in this embodiment, the first filling layer 2 is directly connected to the first conductive layer 1 and the second conductive layer 3. In some other embodiments, there may be other layer structures between the first filling layer 2 and the first conductive layer 1, and between the first filling layer 2 and the second conductive layer 3. There may also be other layer structures on the side of the first conductive layer 1 away from the first filling layer 2 and on the side of the second conductive layer 3 away from the first filling layer 2.

[0166] In some embodiments, the elastic modulus of the first filling layer 2 is less than the elastic modulus of the first conductive layer 1 and less than the elastic modulus of the second conductive layer 3.

[0167] For example, the elastic modulus of the first circuit layer 12 of the first conductive layer 1 is in the range of 50 GPa to 100 GPa. For example, the elastic modulus of the first circuit layer 12 may be 50 GPa, 61 GPa, 69 GPa, 75 GPa, 83 GPa, 90 GPa or 100 GPa, etc.

[0168] For example, the elastic modulus of the second circuit layer 32 of the second conductive layer 3 is in the range of 50 GPa to 100 GPa. The elastic modulus of the second conductive layer 3 may be the same as or different from that of the first conductive layer 1. For example, the elastic modulus of the second conductive layer 3 may be 50 GPa, 61 GPa, 69 GPa, 75 GPa, 83 GPa, 90 GPa, or 100 GPa, etc.

[0169] For example, the elastic modulus of the first filler layer 2 is in the range of 0.2 GPa to 2 GPa. For instance, the elastic modulus of the first filler layer 2 is in the range of 0.5 GPa to 1 GPa. Specifically, the elastic modulus of the first filler layer 2 can be 0.5 GPa, 0.61 GPa, 0.72 GPa, 0.79 GPa, 0.89 GPa, or 1 GPa, etc. In this case, the first filler layer 2 has good support capacity; and the first filler layer 2 has good elasticity, strong ability to deform under stress, and good ability to reduce stress concentration.

[0170] For example, the elongation at break of the first filler layer 2 is greater than or equal to 20%.

[0171] In this embodiment, the first conductive layer 1 and the second conductive layer 3 of the flexible circuit board 205 have relatively large elastic moduli. When the flexible circuit board 205 is bent, one of the first conductive layer 1 and the second conductive layer 3 is compressed, and the pressure can be applied to the first filling layer 2. The other of the first conductive layer 1 and the second conductive layer 3 is stretched, and the pressure formed by the stretching is applied to the first filling layer 2. Since the elastic modulus of the first filling layer 2 is relatively small, the first filling layer 2 is more easily deformed. Therefore, the first filling layer 2 can alleviate the stress concentration when the flexible circuit board 205 is bent by deformation. Furthermore, when the flexible circuit board is bent, the layers may slip slightly due to stretching. The first filling layer 2 can counteract the slippage by deformation, thereby preventing the peeling between the layers.

[0172] In some embodiments, the flexible circuit board 205 may further include a first protective layer 4 and a second protective layer 5. The first protective layer 4 and the second protective layer 5 may be exposed outside the flexible circuit board 205.

[0173] For example, the first protective layer 4 can be fixedly connected to the first conductive layer 1 and located on the side of the first conductive layer 1 opposite to the second conductive layer 3. For example, the first protective layer 4 can be made of a flexible material; for example, the material of the first protective layer 4 may include, but is not limited to, polyimide (PI), optically clear adhesive (OCA), optically clear resin (OCR), pressure-sensitive adhesive (PSA), acrylic resin, and epoxy resin. For example, the elastic modulus of the first protective layer 4 can be in the range of 1 GPa to 10 GPa. For example, the elastic modulus of the first protective layer 4 can be 1 GPa, 3 GPa, 4.5 GPa, 5.5 GPa, 6 GPa, 7 GPa, 9 GPa, or 10 GPa. For example, the elongation at break of the first protective layer 4 can be greater than or equal to 20%.

[0174] For example, the second protective layer 5 can be fixedly connected to the second conductive layer 3 and located on the side of the second conductive layer 3 facing away from the first conductive layer 1. For example, the second protective layer 5 can be made of a flexible material; for example, the material of the second protective layer 5 may include, but is not limited to, polyimide (PI), optically clear adhesive (OCA), optically clear resin (OCR), pressure-sensitive adhesive (PSA), acrylic resin, and epoxy resin. For example, the elastic modulus of the second protective layer 5 can be in the range of 1 GPa to 10 GPa. For example, the elastic modulus of the first protective layer 4 can be 1 GPa, 2 GPa, 3.5 GPa, 4.5 GPa, 5.3 GPa, 6 GPa, 7 GPa, or 10 GPa. For example, the elongation at break of the second protective layer 5 can be greater than or equal to 20%.

[0175] In this embodiment, the first protective layer 4 and the second protective layer 5 can serve as surface film layers on the two surfaces of the flexible circuit board 205, thereby providing protection for the flexible circuit board 205 and improving the applicability of the flexible circuit board 205 in different environments.

[0176] In some embodiments, the elastic modulus of the first protective layer 4 is greater than that of the second protective layer 5.

[0177] For example, the material of the first protective layer 4 can be a material with a high elastic modulus. For instance, the material of the first protective layer 4 can be a composite material of PI and epoxy resin.

[0178] For example, the material of the second protective layer 5 can be a material with a low elastic modulus. For instance, the material of the second protective layer 5 can be PSA or OCA.

[0179] When the flexible circuit board 205 is bent under stress, the first protective layer 4 is closer to the bending center than the second protective layer 5. At this time, the first protective layer 4 is under pressure, and the second protective layer 5 is under tension. The part of the flexible circuit board 205 under pressure is more prone to stress concentration. In this embodiment, since the second protective layer 5 is more easily deformable than the first protective layer 4, the first protective layer 4 is more likely to maintain its shape under pressure, while the second protective layer 5 is more likely to deform under tension, reducing the stress concentration of the first conductive layer 1 and making the overall deformation of the flexible circuit board 205 more balanced.

[0180] In some other embodiments, the flexible circuit board 205 may not include the first protective layer 4 and the second protective layer 5. Alternatively, the flexible circuit board 205 may include only one of the first protective layer 4 and the second protective layer 5.

[0181] In some embodiments, the thickness of the flexible circuit board 205 is less than 50 micrometers. The thicknesses of the first dielectric layer 11, the first circuit layer 12, the first filler layer 2, the first protective layer 4, and the second protective layer 5 are all in the range of 1 micrometer to 10 micrometers. The thinner thickness of the flexible circuit board 205 helps reduce bending stress and facilitates deformation.

[0182] Please refer to Figures 7 and 8. Figure 8 is a schematic diagram of the structure of the first filling layer 2 shown in Figure 7 in some embodiments.

[0183] In some embodiments, a plurality of micropores 21 may be formed in the first filling layer 2. The micropores 21 are arranged at intervals. The axial direction of the micropores 21 is parallel to the arrangement direction of the first conductive layer 1 and the second conductive layer 3. For example, the axial direction of the micropores 21 is parallel to the Z-direction.

[0184] For example, the micro-holes 21 can penetrate the first filling layer 2. Multiple micro-holes 21 can be formed in the first filling layer 2 after it has been fabricated. For example, the micro-holes 21 can be formed by laser perforation, punching, or other methods. When the first filling layer 2 constitutes a stack of the flexible circuit board 205, the micro-holes 21 are correspondingly formed in the flexible circuit board 205.

[0185] For example, the micropore 21 can be a circular hole. In this case, the shape of the micropore 21 is simple and easy to manufacture. Furthermore, the shape of the micropore 21 ensures that the deformation of the hole wall is approximately the same at all points when subjected to forces in all directions, and the stress on the hole wall is approximately the same at all points, so that the first filling layer 2 can deform more uniformly at the micropore 21.

[0186] For example, the diameter of the micropore 21 can range from 1 micrometer to 3000 micrometers. For instance, when the micropore 21 is a circular hole, the radial diameter of the circular hole is the diameter of the micropore 21. When the micropore 21 is a hole of other shapes, the diameter of the micropore 21 can be the maximum size of the micropore 21 in its radial direction.

[0187] For example, the diameter of the microvia 21 can be in the range of 100 micrometers to 500 micrometers. Specifically, the diameter of the microvia 21 can be 100 micrometers, 180 micrometers, 230 micrometers, 260 micrometers, 300 micrometers, 350 micrometers, 420 micrometers, or 500 micrometers, etc. In this case, the diameter of the microvia 21 is relatively small and easy to process and shape, which helps to reduce the manufacturing cost of the flexible circuit board 205.

[0188] In this embodiment, by providing micropores 21 in the first filling layer 2, the material of the first filling layer 2 is partially removed, which is equivalent to improving the flexibility of the flexible circuit board 205 at the location of the micropores 21, making the first filling layer 2 easier to stretch and deform. When the first filling layer 2 is compressed, the micropores 21 provide space for the deformation of the first filling layer 2, so the local stress when the first filling layer 2 is squeezed is smaller. In addition, since the first filling layer 2 is connected to other stacked structures of the flexible circuit board 205, when the flexible circuit board 205 is bent and deformed, the micropores 21 also provide space for the deformation of other stacked layers, which is beneficial to releasing the stress of other stacked layers. Therefore, the micropores 21 are beneficial to reducing the internal stress of the flexible circuit board 205, improving the bending ability of the flexible circuit board 205, and facilitating the large-angle bending of the flexible circuit board 205.

[0189] Furthermore, since the diameter of the micro-hole 21 is small, the stress at the edge of the micro-hole 21 in the first filling layer 2 is also small when the flexible circuit board 205 is bent. This avoids cracks in the first filling layer 2 at the edge of the micro-hole 21 and other stacked layers after multiple bends of the flexible circuit board 205, thereby improving the lifespan of the flexible circuit board 205 after multiple bends and thus increasing the service life of the flexible circuit board 205.

[0190] In some embodiments, the distance between adjacent micropores 21 is in the range of 10 micrometers to 1000 micrometers. The distance between adjacent micropores 21 can be the distance between the centers of two adjacent micropores 21. For example, the distance between adjacent micropores 21 is in the range of 100 micrometers to 300 micrometers. For instance, the distance between adjacent micropores 21 can be 100 micrometers, 170 micrometers, 200 micrometers, 240 micrometers, or 300 micrometers, etc. In this case, the difference between the spacing between adjacent micropores 21 and the diameter of the micropores 21 is small, the spacing between adjacent micropores 21 is suitable, and the density of the multiple micropores 21 is suitable, thereby giving the first filling layer 2 suitable flexibility and support.

[0191] In some embodiments, a plurality of microholes 21 may be formed locally in the first filling layer 2. The area where the microholes 21 are formed can form a microhole region 22; that is, the area where the plurality of microholes 21 are distributed on the first filling layer 2 is the microhole region 22 of the first filling layer 2. In the length direction (e.g., the X direction) of the flexible circuit board 205, the boundary of the microhole region 22 may be the boundary of the length space occupied by the plurality of microholes 21; in the width direction of the flexible circuit board 205, the boundary of the microhole region 22 may be the boundary of the width space occupied by the plurality of microholes 21.

[0192] For example, the ratio of the total area of ​​the plurality of micropores 21 to the area of ​​the micropore region 22 is greater than or equal to 50%. For instance, the ratio of the total area of ​​the plurality of micropores 21 to the area of ​​the micropore region 22 can be 53%, 55%, 58%, 60%, or 66%, etc. That is, within the micropore region 22, half or more of the area is formed by a plurality of micropores 21, and the density of micropores 21 in the micropore region 22 is relatively high, which is beneficial to reducing the stress generated when the first filling layer 2 undergoes structural deformation in the micropore region 22.

[0193] For example, the ratio of the area of ​​the micro-hole region 22 to the area of ​​the flexible circuit board 205 is greater than or equal to 1% and less than or equal to 10%. For instance, the ratio can be 3%, 5%, 6.5%, 7%, or 9%. In this case, the area of ​​the micro-hole region 22 occupies only a small portion of the area of ​​the flexible circuit board 205, and correspondingly, the area of ​​the micro-hole region 22 also occupies only a small portion of the area of ​​the first filling layer 2. Forming the micro-hole region 22 locally within the first filling layer 2 improves processing efficiency and helps maintain the support performance of other areas of the flexible circuit board 205, thereby ensuring the display effect of the flexible display screen 20.

[0194] For example, the micro-hole region 22 can correspond to the second plate 2022 of the flexible circuit board 205, and thus, multiple micro-holes 21 are located in the second plate 2022. Since the second plate 2022 is the main deformation area in the flexible circuit board 205, the micro-hole region 22 can reduce the stress on the flexible circuit board 205 when the second plate 2022 is bent. The area of ​​the micro-hole region 22 can be smaller than the area of ​​the second plate 2022 to prevent the second plate 2022 from collapsing when the flexible circuit board 205 is bent, which would worsen the creases in the flexible display screen 20 and improve the display effect of the flexible circuit board 205.

[0195] In some other examples, the area of ​​the microporous region 22 may be greater than or equal to the area of ​​the second plate 2022.

[0196] In the flexible circuit board 205, when the flexible circuit board 205 is bent, there are dynamic bending areas where bending occurs, such as the second board 2022, and static areas where bending does not occur, such as the first board 2021 and the third board 2023. After the flexible circuit board 205 is bent multiple times, cracks or fractures are easily generated at the junction of the dynamic bending area and the static area due to stress concentration.

[0197] In this embodiment, the diameter of the micro-hole 21 is set reasonably, and the micro-hole 21 is located in the second plate 2022. At the edge where multiple micro-holes 21 are distributed, the stress between the first filling layer 2 and the stacked layer connected to it is more dispersed, thereby avoiding stress concentration at the edge where the micro-holes 21 are distributed, and increasing the tensile strength at break, thereby avoiding the generation of cracks and improving the multiple bending resistance and fatigue resistance of the second plate 2022 of the flexible circuit board 205. In the flexible display screen 20, it avoids problems such as peeling and light shadow caused by discontinuity, ensuring the service life and display effect of the flexible display screen 20.

[0198] In some embodiments, the plurality of micropores 21 can be uniformly arranged. The plurality of micropores 21 can form a plurality of sub-rows 23, and each sub-row 23 can include a plurality of micropores 21. The plurality of sub-rows 23 can be arranged along a first direction. For example, the first direction can be parallel to the X direction.

[0199] For example, the plurality of micro-holes 21 in each sub-row 23 can be arranged along a second direction. This second direction differs from the first direction. For instance, the second direction can be perpendicular to the first direction, or parallel to the Y-direction. In this case, the arrangement of the plurality of micro-holes 21 is more compatible with the bending direction of the flexible circuit board 205, which is beneficial for the uniform deformation of the flexible circuit board 205 in the first direction when it bends. In some other embodiments, the second direction can form an acute angle with the first direction, in which case the plurality of micro-holes 21 in each sub-row 23 are essentially arranged at an angle.

[0200] For example, the plurality of micropores 21 in each sub-column 23 can be arranged at equal intervals. In this case, the plurality of micropores 21 in the sub-column 23 are equivalent to being uniformly arranged. In some other embodiments, the plurality of micropores 21 in the sub-column 23 can be arranged at unequal intervals.

[0201] For example, the spacing between the microholes 21 in different sub-rows 23 can be the same. In this case, all the microholes 21 are equivalent to being uniformly arranged in the second direction, and when the flexible circuit board 205 is deformed by force, the deformation of the first filling layer 2 in the second direction is relatively uniform. In some other embodiments, the spacing between the microholes 21 in different sub-rows 23 can be different.

[0202] For example, adjacent sub-columns 23 are spaced apart, and the spacing between any two adjacent sub-columns 23 can be the same. In this case, all microholes 21 are equivalent to being uniformly arranged in the first direction, and when the flexible circuit board 205 is deformed by force, the deformation of the first filling layer 2 in the first direction is relatively uniform. In some other embodiments, the spacing between any two adjacent sub-columns 23 can be different.

[0203] For example, the projections of the microholes 21 between two adjacent sub-columns 23 along the first direction can be staggered. Specifically, in two adjacent sub-columns 23, the projections of the microholes 21 in the first direction of one sub-column 23 do not completely coincide with the projections of the microholes 21 in the first direction of the other sub-column 23. In this case, when the flexible circuit board 205 is deformed under force, the multiple microholes 21 deform accordingly. Because the adjacent sub-columns 23 are staggered, the deformation of the microholes 21 in the adjacent sub-columns 23 can also be staggered, thereby making the deformation of the material between adjacent microholes 21 more uniform and reducing the local stress of the material between adjacent microholes 21.

[0204] Furthermore, in two adjacent sub-rows 23, the projection of the micro-hole 21 of one sub-row 23 onto the vertical plane in the first direction is located in the middle of the interval between the projections of the micro-hole 21 of the other sub-row 23 onto the vertical plane in the first direction. In this case, when the flexible circuit board 205 is deformed by force, the stress on the material between adjacent micro-holes 21 is more uniform.

[0205] In some embodiments, the multiple micropores 21 may be the same size.

[0206] For example, the micropores 21 in the same sub-row 23 can be the same size. For example, the micropores 21 in different sub-rows 23 can be the same size. For example, the diameter of the micropore 21 can be 300 micrometers.

[0207] At this point, all the micropores 21 are the same size, making them easy to process and shape, which helps to reduce manufacturing costs.

[0208] In some other embodiments, the size of the different micropores 21 may be different, and this embodiment does not specifically limit this.

[0209] In some embodiments, the multiple micropores 21 may have the same shape.

[0210] For example, the micropores 21 in the same sub-column 23 can have the same shape. For example, the micropores 21 in different sub-columns 23 can have the same shape. For example, the micropores 21 can be cylindrical and have holes that penetrate the first filling layer 2.

[0211] At this point, all the micropores 21 have the same shape, making them easy to process and shape, which helps to reduce manufacturing costs.

[0212] In some other embodiments, the shapes of the different micropores 21 may be different, and this embodiment does not specifically limit them.

[0213] Please refer to Figure 9, which is a structural schematic diagram of the first filling layer 2 shown in Figure 7 in some other embodiments. The first filling layer 2 shown in the embodiment of Figure 9 may include most of the technical features of the first filling layer 2 shown in the embodiment of Figure 8. For the technical features that are the same in both, this embodiment will not repeat them. The following mainly describes the differences between the two.

[0214] The main difference between the first filling layer 2 shown in the embodiment of Figure 9 and the first filling layer 2 shown in Figure 8 is the shape of the micropores 21.

[0215] In some embodiments, the micropores 21 of the first filling layer 2 can be rhomboid in shape. Specifically, the cross-section of the micropores 21 in the plane containing the first and second directions (i.e., the XY plane) is rhomboid.

[0216] For example, the two diagonals of the rhomboid hole can be parallel to the first direction and the second direction, respectively, so that the rhomboid hole can be more easily deformed in the first direction and the second direction.

[0217] For example, the long diagonal of the rhomboid hole can be parallel to the second direction, and the short diagonal of the rhomboid hole can be parallel to the first direction. That is, the size of the micro-hole 21 in the second direction (such as the Y direction) is larger than the size of the micro-hole 21 in the first direction (such as the X direction). In this case, the rhomboid hole is more easily deformed in the first direction than in the second direction. When the first filling layer 2 is subjected to force and deforms, the first filling layer 2 is more easily deformed in the first direction, which is beneficial for stress release.

[0218] For example, all micropores 21 may have the same shape and opening method, but are not limited thereto.

[0219] Please refer to Figure 10, which is a structural schematic diagram of the first filling layer 2 shown in Figure 7 in some embodiments. The first filling layer 2 shown in the embodiment of Figure 10 may include most of the technical features of the first filling layer 2 shown in the embodiment of Figure 8. For the technical features that are the same in both, this embodiment will not repeat them. The following mainly describes the differences between the two.

[0220] The main difference between the first filling layer 2 shown in the embodiment of Figure 10 and the first filling layer 2 shown in Figure 8 is the shape of the micropores 21.

[0221] In some embodiments, the micropores 21 of the first filling layer 2 can be rectangular. Specifically, the cross-section of the micropores 21 on the plane formed by the first and second directions (i.e., the XY plane) is rectangular.

[0222] For example, a rectangular hole can be an elongated hole. For instance, the length of the longer side of a rectangular hole can be more than three times the length of the shorter side, but is not limited to this.

[0223] For example, the long side and short side of the rectangular hole can be parallel to the first direction and the second direction, respectively, so that the rectangular hole can be more easily deformed in the first direction and the second direction.

[0224] For example, the long side of the rectangular hole can be parallel to the second direction, and the short side of the rectangular hole can be parallel to the first direction. That is, the size of the microhole 21 in the second direction (such as the Y direction) is larger than the size of the microhole 21 in the first direction (such as the X direction). In this case, the rectangular hole is more easily deformed in the first direction than in the second direction. When the first filling layer 2 is deformed by force, the first filling layer 2 is more easily deformed in the first direction, which is beneficial to stress release.

[0225] For example, all micropores 21 may have the same shape and opening method, but are not limited thereto.

[0226] Please refer to Figure 11, which is a structural schematic diagram of the first filling layer 2 shown in Figure 7 in some embodiments. The first filling layer 2 shown in the embodiment of Figure 11 may include most of the technical features of the first filling layer 2 shown in the embodiment of Figure 8. For the technical features that are the same in both, this embodiment will not repeat them. The following mainly describes the differences between the two.

[0227] The main difference between the first filling layer 2 shown in the embodiment of Figure 11 and the first filling layer 2 shown in Figure 8 lies in the arrangement of the micropores 21.

[0228] In some embodiments, multiple sub-columns 23 are arranged at intervals, and the multiple sub-columns 23 may be non-equidistant.

[0229] For example, the plurality of sub-columns 23 include a first sub-column 231, a second sub-column 232, and a third sub-column 233 located between the centerline of the second plate 2022 and the third plate 2023; the first sub-column 231, the second sub-column 232, and the third sub-column 233 are sequentially adjacent and spaced apart along the direction from the centerline of the second plate 2022 toward the third plate 2023. The distance between the first sub-column 231 and the second sub-column 232 is a first distance a1, and the distance between the second sub-column 232 and the third sub-column 233 is a second distance a2, wherein the first distance a1 is smaller than the second distance a2. The centerline of the second plate 2022 is a straight line on the center plane of the second plate 2022 in the first direction. It is understood that the plurality of sub-columns 23 may also include a greater number of other sub-columns 23; this embodiment does not specifically limit the number of sub-columns 23.

[0230] For example, referring to Figure 7, along the centerline of the second plate 2022 toward the third plate 2023 (as shown in the +X direction in Figure 11), the spacing between adjacent sub-columns 23 gradually increases.

[0231] For example, the plurality of sub-columns 23 also include a fourth sub-column 234, a fifth sub-column 235, and a sixth sub-column 236 located between the centerline of the second plate 2022 and the third plate 2023; the fourth sub-column 234, the fifth sub-column 235, and the sixth sub-column 236 are sequentially adjacent and spaced apart along the centerline of the second plate 2022 toward the first plate 2021. The distance between the fourth sub-column 234 and the fifth sub-column 235 is a third distance a3, and the distance between the fifth sub-column 235 and the sixth sub-column 236 is a fourth distance a4, wherein the third distance a3 is smaller than the fourth distance a4.

[0232] For example, referring to Figure 7, along the centerline of the second plate 2022 toward the first plate 2021 (as shown in the -X direction in Figure 11), the interval between adjacent sub-columns 23 gradually increases.

[0233] When the flexible circuit board 205 is applied in electronic devices, when the first filling layer 2 deforms, the deformation in the middle of the micro-hole region 22 is large, while the deformation on both sides is small. The stress in the middle of the micro-hole region 22 is more likely to concentrate, requiring the corresponding position of the first filling layer 2 to have a strong bending ability.

[0234] In this example, the spacing between the sub-rows 23 in the middle of the micro-hole region 22 is small, and the density of micro-holes 21 is high. The spacing between the openings on both sides of the micro-hole region 22 is large, and the density of micro-holes 21 is low. By setting the spacing of multiple sub-rows 23, in this example, the density of micro-holes 21 is high in the area of ​​large deformation of the flexible circuit board 205, and the density of micro-holes 21 is low in the area of ​​small deformation of the flexible circuit board 205. The setting of micro-holes 21 is more suitable for the deformation mode of the flexible circuit board 205, so that the flexible circuit board 205 can deform evenly and has more balanced stress, which is beneficial to improving the overall life of the flexible circuit board 205.

[0235] For example, the arrangement of multiple sub-columns 23 can be symmetrical. For instance, the first spacing a1 can be equal to the third spacing a3. However, this is not a limitation.

[0236] Please refer to Figure 12, which is a structural schematic diagram of the first filling layer 2 shown in Figure 7 in some other embodiments. The first filling layer 2 shown in the embodiment of Figure 12 may include most of the technical features of the first filling layer 2 shown in the embodiment of Figure 8. For the technical features that are the same in both, this embodiment will not repeat them. The following mainly describes the differences between the two.

[0237] The main difference between the first filling layer 2 shown in the embodiment of Figure 12 and the first filling layer 2 shown in Figure 8 is the size of the micropores 21.

[0238] In some embodiments, the micropores 21 in different sub-rows 23 have different sizes.

[0239] For example, the plurality of sub-columns 23 include a first sub-column 231 and a second sub-column 232 located between the centerline of the second plate 2022 and the third plate 2023; the first sub-column 231 and the second sub-column 232 are arranged alternately along the centerline of the second plate 2022 toward the third plate 2023. It is understood that the plurality of sub-columns 23 may include a greater number of sub-columns 23; this embodiment does not specifically limit the number of sub-columns 23. The diameter of the micropores 21 in the first sub-column 231 is r1, and the diameter of the micropores 21 in the second sub-column 232 is r2. r1 can be greater than r2. It is understood that all micropores 21 in the first sub-column 231 can have the same shape and diameter. All micropores 21 in the second sub-column 232 can have the same shape and diameter.

[0240] For example, referring to Figure 7, along the direction from the centerline of the second plate 2022 toward the third plate 2023 (as shown in the +X direction in Figure 12), the diameter of the micropores 21 in different sub-rows 23 gradually decreases.

[0241] For example, the plurality of sub-columns 23 also include a fourth sub-column 234 and a fifth sub-column 235 located between the centerline of the second plate 2022 and the first plate 2021; the fourth sub-column 234 and the fifth sub-column 235 are arranged sequentially at intervals along the centerline of the second plate 2022 toward the first plate 2021. The diameter of the micropore 21 in the fourth sub-column 234 is r4, and the diameter of the micropore 21 in the fifth sub-column 235 is r5. r4 can be greater than r5. It is understood that all micropores 21 in the fourth sub-column 234 can have the same shape and diameter. All micropores 21 in the fifth sub-column 235 can have the same shape and diameter.

[0242] For example, referring to Figure 7, along the centerline of the second plate 2022 toward the first plate 2021 (as shown in the -X direction in Figure 12), the diameter of the micropores 21 in different sub-rows 23 gradually decreases.

[0243] When the flexible circuit board 205 is applied in electronic devices, when the first filling layer 2 deforms, the deformation in the middle of the micro-hole region 22 is large, while the deformation on both sides is small. The stress in the middle of the micro-hole region 22 is more likely to concentrate, requiring the corresponding position of the first filling layer 2 to have a strong bending ability.

[0244] In this example, the diameter of the micro-hole 21 in the middle of the micro-hole region 22 is large, and the deformation capacity of the micro-hole 21 is strong. The diameter of the micro-hole 21 on both sides of the micro-hole region 22 is small, and the deformation capacity of the micro-hole 21 is moderate. By setting the diameter of the micro-hole 21 in multiple sub-rows 23, in this example, the micro-hole 21 in the area of ​​large deformation of the flexible circuit board 205 has large deformation, and the micro-hole 21 in the area of ​​small deformation of the flexible circuit board 205 has small deformation. The setting of the micro-hole 21 is more suitable for the deformation mode of the flexible circuit board 205, so that the flexible circuit board 205 can deform evenly and has more balanced stress, which is beneficial to improving the overall life of the flexible circuit board 205.

[0245] Please refer to Figure 13, which is a structural schematic diagram of the flexible circuit board 205 shown in Figure 7 in some other embodiments. The embodiment of Figure 13 may include most of the technical features of the embodiment of Figure 7. For the technical features that are the same in both, this embodiment will not be described again. The following mainly describes the differences between the two.

[0246] The main difference between the flexible circuit board 205 shown in the embodiment of Figure 13 and the first filling layer 2 shown in Figure 7 is the shape of the micropores 21.

[0247] In some embodiments, the micropore 21 may be a blind pore.

[0248] For example, the micropore 21 can extend from one surface of the first filling layer 2 to the other surface, and the length of the extension is the depth of the micropore 21. The depth of the micropore 21 can be greater than or equal to half the thickness of the first filling layer 2. It is understood that, since the micropore 21 is a blind hole, its depth is less than the thickness of the first filling layer 2. In some other embodiments, the micropore 21 can also extend obliquely relative to the thickness direction of the first filling layer 2; this embodiment does not specifically limit this.

[0249] For example, the micropore 21 can extend from the surface of the first filling layer 2 connected to the first conductive layer 1 to the surface of the first filling layer 2 connected to the second conductive layer 3. In this case, the first filling layer 2 has better bendability towards the first conductive layer 1, which is beneficial for the first filling layer 2 to bend towards the first guide layer.

[0250] In this embodiment, one side of the first filling layer 2 has good bending ability and good integrity, and the shape of the first filling layer 2 is easy to maintain; thus, it is easy for the first filling layer 2 to be fabricated with other stacked layers to form a flexible circuit board 205, and it is beneficial to avoid the breakage and peeling of the stacked layers in the flexible circuit board 205.

[0251] Please refer to Figure 14, which is a structural schematic diagram of the flexible circuit board 205 shown in Figure 7 in some other embodiments. The flexible circuit board 205 shown in the embodiment of Figure 14 may include most of the technical features of the flexible circuit board 205 shown in the embodiment of Figure 7. For the technical features that are the same in both, this embodiment will not repeat them. The following mainly describes the differences between the two.

[0252] The main difference between the flexible circuit board 205 shown in the embodiment of Figure 14 and the first filling layer 2 shown in Figure 7 is the shape of the micropores 21.

[0253] In some embodiments, the diameter or area of ​​the micropores 21 varies in different cross sections along the thickness direction (e.g., the Z direction) of the first filling layer 2.

[0254] For example, in the direction from the first conductive layer 1 to the second conductive layer 3, the cross-sectional diameter of the micropore 21 gradually decreases. As shown in Figure 14, the cross-sectional diameter of the micropore 21 gradually decreases from the top side to the bottom side. It can be understood that the cross-sectional diameter of the micropore 21 can be the diameter of the cross-section perpendicular to the Z direction. In this case, the maximum diameter of the micropore 21 is taken as the diameter of the micropore 21.

[0255] The diameter of the micropore 21 can be set with reference to the relevant description in the previous embodiment, and will not be repeated in this embodiment.

[0256] In this example, since the cross-sectional diameter of the micro-hole 21 changes as it extends, the deformation of the micro-hole 21 is non-uniform. Because the diameter of the micro-hole 21 changes from large to small, the micro-hole 21 has a strong deformation capability on the side surface of the first filling layer 2 connected to the first conductive layer 1, and a weak deformation capability on the other side surface. When the first filling layer 2 deforms towards the first conductive layer 1, the deformation of the first filling layer 2 on that side is large, while the micro-hole 21 is easy to deform and has a large degree of deformation on that side (such as the top side). The deformation of the micro-hole 21 is more compatible with the overall deformation of the first filling layer 2, and thus the deformation of the first filling layer 2 at various points in terms of thickness is more uniform, and the stress distribution is also more uniform.

[0257] Please refer to Figure 15, which is a structural schematic diagram of the flexible circuit board 205 shown in Figure 7 in some embodiments. The embodiment of Figure 15 may include most of the technical features of the embodiment of Figure 7. For the technical features that are the same in both, this embodiment will not be repeated. The following mainly describes the differences between the two.

[0258] In some embodiments, the flexible circuit board 205 further includes a third dielectric layer 6 and a second filler layer 7. The third dielectric layer 6 and the second filler layer 7 are located between the first conductive layer 1 and the second conductive layer 3, the first filler layer 2 connects the third dielectric layer 6 and the first conductive layer 1, and the second filler layer 7 connects the third dielectric layer 6 and the second conductive layer 3.

[0259] For example, the material of the third dielectric layer 6 can be a flexible material. For instance, the third dielectric layer 6 can be a polymer material, such as polyimide (PI), polyethylene terephthalate (PET), etc. The third dielectric layer 6 can also be an inorganic material, such as glass.

[0260] For example, the elastic modulus of the third dielectric layer 6 is greater than that of the first filler layer 2 and / or the second filler layer 7. For instance, the elastic modulus of the third dielectric layer 6 can be in the range of 2 GPa to 10 GPa. Specifically, the elastic modulus of the third dielectric layer 6 can be 2 GPa, 3.6 GPa, 4.8 GPa, 5 GPa, 6.1 GPa, 7 GPa, 8 GPa, or 10 GPa, etc. In this case, the third dielectric layer 6 is more rigid than the first filler layer 2 and the second filler layer 7, and the third dielectric layer 6 has a stronger ability to balance the forces on the first conductive layer 1 and the second conductive layer 3.

[0261] For example, one side surface of the second filler layer 7 contacts and is fixedly connected to the second circuit layer 32, and the other side surface of the second filler layer 7 contacts and is fixedly connected to the third dielectric layer 6. The area of ​​the second filler layer 7 can be equal to the area of ​​the first conductive layer 1 and / or the second conductive layer 3, that is, the size of the second filler layer 7 can substantially cover the size of the flexible circuit board 205.

[0262] For example, the second filler layer 7 can be an adhesive material. For instance, the second filler layer 7 can be made of materials such as acrylic resin or epoxy resin. For example, the second filler layer 7 can be flexible to make the flexible circuit board 205 flexible. The second filler layer 7 acts as an adhesive material, connecting the third dielectric layer 6 and the second conductive layer 3.

[0263] For example, the elastic modulus of the second filler layer 7 is less than that of the first conductive layer 1 and less than that of the second conductive layer 3. For instance, the elastic modulus of the second filler layer 7 is in the range of 0.2 GPa to 2 GPa. Or, the elastic modulus of the second filler layer 7 is in the range of 0.5 to 1 GPa. Or, the elastic modulus of the second filler layer 7 can be 0.5 GPa, 0.55 GPa, 0.66 GPa, 0.71 GPa, 0.79 GPa, 0.9 GPa, or 1 GPa, etc. In this case, the second filler layer 7 has good support capacity; and the second filler layer 7 has good elasticity, strong ability to deform under stress, and good ability to reduce stress concentration.

[0264] For example, the elongation at break of the second filler layer 7 may be greater than or equal to 20%.

[0265] For example, the second filling layer 7 may not have micropores 21. In some other embodiments, the second filling layer 7 may have micropores, and the specific configuration of the micropores can refer to the configuration of the micropores 21 in the first filling layer 2. This embodiment does not make specific limitations.

[0266] For example, in the first conductive layer 1, the first dielectric layer 11 is located in the direction opposite to the second conductive layer 3 of the first circuit layer 12. The first dielectric layer 11 can provide protection for the internal stack of the flexible circuit board 205. The surface of the first dielectric layer 11 facing away from the second conductive layer 3 can serve as one side surface of the flexible circuit board 205. In this case, the flexible circuit board 205 may not require a protective layer, which is beneficial for thinning the design of the flexible circuit board 205. Furthermore, when other stacked layers are provided opposite to the first circuit layer 12, the first dielectric layer 11 can also be used to protect the first circuit layer 12.

[0267] For example, in the second conductive layer 3, the second dielectric layer 31 is located in the direction opposite to the first conductive layer 1 of the second circuit layer 32. The second dielectric layer 31 can provide protection for the internal stack of the flexible circuit board 205. The surface of the second dielectric layer 31 facing away from the first conductive layer 1 can serve as the other side surface of the flexible circuit board 205. In this case, the flexible circuit board 205 does not need a protective layer, which is beneficial for the thinning design of the flexible circuit board 205. Furthermore, when other stacked layers are provided on the side of the second dielectric layer 31 facing away from the second circuit layer 32, the first dielectric layer 11 can also be used to protect the first circuit layer 12.

[0268] In this embodiment, the third dielectric layer 6 is located between the first conductive layer 1 and the second conductive layer 3, and also between the first filler layer 2 and the second filler layer 7, serving as a neutral layer. When the flexible circuit board 205 deforms, one of the first conductive layer 1 and the second conductive layer 3 is subjected to tension, while the other is subjected to compression. The deformation degrees of the first conductive layer 1 and the second conductive layer 3 are similar, thereby making the deformation of the flexible circuit board 205 more balanced in its thickness direction. This avoids stress concentration caused by excessive local deformation of the first conductive layer 1 or the second conductive layer 3, thus improving the service life of the flexible circuit board 205.

[0269] When the bending center of the flexible circuit board 205 is closer to the first conductive layer 1, the first filler layer 2 can better release the compressive stress of the first conductive layer 1.

[0270] Please refer to Figure 16, which is a structural schematic diagram of the flexible circuit board 205 shown in Figure 7 in some other embodiments. The flexible circuit board 205 shown in the embodiment of Figure 16 may include most of the technical features of the flexible circuit board 205 shown in the embodiment of Figure 15. For technical features that are the same in both, this embodiment will not repeat them; the following mainly describes the differences between the two.

[0271] In some embodiments, the flexible circuit board 205 further includes a third dielectric layer 6 and a second filler layer 7. The third dielectric layer 6 and the second filler layer 7 are located between the first conductive layer 1 and the second conductive layer 3. The third dielectric layer 6 is connected to the first filler layer 2, the first filler layer 2 is connected to the third dielectric layer 6 and the second conductive layer 3, and the second filler layer 7 is connected to the third dielectric layer 6 and the first conductive layer 1.

[0272] The main difference between the flexible circuit board 205 shown in the embodiment of Figure 16 and the flexible circuit board 205 shown in Figure 15 lies in the different positions of the second filling layer 7 and the first filling layer 2. The arrangement of the first conductive layer 1, the second conductive layer 3, the first filling layer 2, the second filling layer 7, and the third dielectric layer 6 can be referred to the relevant description of the embodiment in Figure 15.

[0273] In this embodiment, the third dielectric layer 6 is located between the first conductive layer 1 and the second conductive layer 3, and also between the first filler layer 2 and the second filler layer 7, serving as a neutral layer. When the flexible circuit board 205 deforms, one of the first conductive layer 1 and the second conductive layer 3 is subjected to tension, while the other is subjected to compression. The deformation degrees of the first conductive layer 1 and the second conductive layer 3 are similar, thereby making the deformation of the flexible circuit board 205 more balanced in its thickness direction. This avoids stress concentration caused by excessive local deformation of the first conductive layer 1 or the second conductive layer 3, thus improving the service life of the flexible circuit board 205.

[0274] When the bending center of the flexible circuit board 205 is closer to the first conductive layer 1, the first filler layer 2 can better release the tensile stress of the second conductive layer 3.

[0275] Please refer to Figure 17, which is a structural schematic diagram of the flexible circuit board 205 shown in Figure 7 in some other embodiments. The flexible circuit board 205 shown in the embodiment of Figure 17 may include most of the technical features of the flexible circuit board 205 shown in the embodiment of Figure 7. For technical features that are the same in both, this embodiment will not repeat them; the following mainly describes the differences between the two.

[0276] In some embodiments, in the first conductive layer 1, the first dielectric layer 11 is located in the direction opposite to the second conductive layer 3 of the first circuit layer 12, and the surface of the first dielectric layer 11 opposite to the second conductive layer 3 serves as one side surface of the flexible circuit board 205. In this case, the first dielectric layer 11 can provide protection for the internal stack of the flexible circuit board 205, and the flexible circuit board 205 may not need to be provided with a protective layer, which is beneficial for the thinning design of the flexible circuit board 205.

[0277] Please refer to Figure 18, which is a schematic diagram of the structure of another electronic device 100 provided in an embodiment of this application.

[0278] In some embodiments, the electronic device 100 may include a first device 40, a second device 50, and a flexible circuit board 205. The flexible circuit board 205 is electrically connected to the first device 40 and the second device 50.

[0279] For example, electronic device 100 may be a mobile phone, watch, headphones, laptop, tablet, or other such device.

[0280] For example, the first device 40 and the second device 50 can be devices that require electrical connection, such as a circuit board or a flexible display screen 20. The first device 40 and the second device 50 can be devices of the same or different types. For example, the first device 40 can be the first circuit board in the embodiment of FIG3, and the second device 50 can be the second circuit board in the embodiment of FIG3.

[0281] In this embodiment, when the space in the electronic device 100 is relatively small or compact, the flexible circuit board 205 needs to be bent at a large angle; or, when the electronic device 100 is working, the flexible circuit board 205 needs to be bent repeatedly. The flexible circuit board 205 in this embodiment has strong bending performance, can be bent at a large angle, and also has a high lifespan after multiple bends, thereby improving the lifespan of the electronic device 100.

[0282] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other, and any combination of features in different embodiments is also within the protection scope of this application. That is to say, the multiple embodiments described above can also be arbitrarily combined according to actual needs.

[0283] It should be noted that all the above figures are exemplary illustrations of this application and do not represent the actual size of the product. Furthermore, the dimensional proportions between the components in the figures are not intended to limit the actual product of this application.

[0284] The above are merely some embodiments and implementation methods of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A flexible circuit board (205) characterized by, It includes a first conductive layer (1), a first filling layer (2) and a second conductive layer (3) stacked together. The first filling layer (2) is located between the first conductive layer (1) and the second conductive layer (3) and is fixedly connected to the first conductive layer (1) and the second conductive layer (3). Both the first conductive layer (1) and the second conductive layer (3) are capable of transmitting electrical signals. The elastic modulus of the first filling layer (2) is smaller than that of the first conductive layer (1) and the second conductive layer (3). The first filling layer (2) has a plurality of micropores (21) spaced apart. The axial direction of the micropores (21) is parallel to the direction of the first conductive layer (1) toward the second conductive layer (3). The diameter of the micropores (21) is in the range of 1 micrometer to 1000 micrometers.

2. The flexible circuit board (205) according to claim 1, characterized in that, The diameter of the micropore (21) is in the range of 100 micrometers to 500 micrometers.

3. The flexible circuit board (205) according to claim 1 or 2, characterized in that, The distance between adjacent micropores (21) is in the range of 10 micrometers to 1000 micrometers.

4. The flexible circuit board (205) according to any one of claims 1 to 3, characterized in that, The micropores (21) penetrate the first filling layer (2); Alternatively, the micropore (21) may be a blind hole, and the depth of the micropore (21) may be greater than or equal to 50% of the thickness of the first filling layer (2).

5. The flexible circuit board (205) according to any one of claims 1 to 4, characterized in that, The area where the plurality of micropores (21) are distributed on the first filling layer (2) is the micropore region (22) of the first filling layer (2), and the ratio of the total area of ​​the plurality of micropores (21) to the total area of ​​the micropore region (22) is greater than or equal to 50%.

6. The flexible circuit board (205) according to claim 5, characterized in that, The ratio of the area of ​​the microporous region (22) to the area of ​​the flexible circuit board (205) is greater than or equal to 1% and less than or equal to 10%.

7. The flexible circuit board (205) according to any one of claims 1 to 6, characterized in that, The flexible circuit board (205) has a first plate (2021), a second plate (2022) and a third plate (2023) arranged along a first direction. When the flexible circuit board (205) is bent, the second plate (2022) bends and the first plate (2021) and the third plate (2023) move closer together. The plurality of micropores (21) are located in the second plate (2022). The plurality of micropores (21) are divided into a plurality of sub-columns (23). The plurality of sub-columns (23) are arranged along the first direction. The plurality of micropores (21) in each sub-column (23) are arranged along the second direction, which is perpendicular to the first direction.

8. The flexible circuit board (205) according to claim 7, characterized in that, The micropore (21) is a circular pore; Alternatively, the micropore (21) may have a larger size in the second direction than in the first direction.

9. The flexible circuit board (205) according to claim 7 or 8, characterized in that, The micropores (21) in two adjacent sub-columns (23) are staggered along the projection of the first direction.

10. The flexible circuit board (205) according to any one of claims 7 to 9, characterized in that, The plurality of sub-columns (23) include a first sub-column (231), a second sub-column (232), and a third sub-column (233) located between the centerline of the second plate (2022) and the third plate (2023), in a direction from the centerline of the second plate (2022) toward the third plate (2023), wherein the first sub-column (231), the second sub-column (232), and the third sub-column (233) are arranged adjacent to each other and spaced apart. The distance between the first sub-column (231) and the second sub-column (232) is the first distance, and the distance between the second sub-column (232) and the third sub-column (233) is the second distance. The first distance is less than the second distance.

11. The flexible circuit board (205) according to any one of claims 1 to 10, characterized in that, The material of the first filler layer (2) includes at least one of acrylic resin and epoxy resin.

12. The flexible circuit board (205) according to any one of claims 1 to 11, characterized in that, The first conductive layer (1) includes a first dielectric layer (11) and a first circuit layer (12), wherein the first circuit layer (12) is fixed to the first dielectric layer (11); the first dielectric layer (11) is located on the side of the first circuit layer (12) opposite to the second conductive layer (3); and / or The second conductive layer (3) includes a second dielectric layer (31) and a second circuit layer (32), the second circuit layer (32) being fixed to the second dielectric layer (31); the second dielectric layer (31) is located on the side of the second circuit layer (32) away from the first conductive layer (1).

13. The flexible circuit board (205) according to any one of claims 1 to 12, characterized in that, The flexible circuit board (205) further includes a first protective layer (4), which is fixedly connected to the first conductive layer (1) and is located on the side of the first conductive layer (1) away from the second conductive layer (3).

14. The flexible circuit board (205) according to claim 13, characterized in that, The flexible circuit board (205) further includes a second protective layer (5), which is fixedly connected to the second conductive layer (3). The second protective layer (5) is located on the side of the second conductive layer (3) away from the first conductive layer (1).

15. The flexible circuit board (205) according to claim 14, characterized in that, The elastic modulus of the first protective layer (4) is less than that of the first conductive layer (1), the elastic modulus of the second protective layer (5) is less than that of the second conductive layer (3), and the elastic modulus of the first protective layer (4) is greater than that of the second protective layer (5).

16. The flexible circuit board (205) according to any one of claims 1 to 15, characterized in that, The flexible circuit board (205) further includes a third dielectric layer (6) and a second filler layer (7), wherein the third dielectric layer (6) and the second filler layer (7) are located between the first conductive layer (1) and the second conductive layer (3); Wherein, the first filling layer (2) connects the third dielectric layer (6) and the first conductive layer (1), and the second filling layer (7) connects the third dielectric layer (6) and the second conductive layer (3); or, The first filling layer (2) connects the third dielectric layer (6) and the second conductive layer (3), and the second filling layer (7) connects the third dielectric layer (6) and the first conductive layer (1).

17. The flexible circuit board (205) according to claim 16, characterized in that, The elastic modulus of the third dielectric layer (6) is greater than that of the first filling layer (2) and the second filling layer (7).

18. A flexible display screen (20), characterized in that, It includes a display layer (204) and a flexible circuit board (205) as claimed in any one of claims 1 to 17, wherein the display layer (204) and the flexible circuit board (205) are fixedly connected and stacked.

19. The flexible display screen (20) according to claim 18, characterized in that, The flexible display screen (20) also includes a support layer (206); The display layer (204), the flexible circuit board (205), and the support layer (206) are sequentially fixedly connected and stacked; or, the display layer (204), the support layer (206), and the flexible circuit board (205) are sequentially fixedly connected and stacked.

20. An electronic device (100), characterized in that, include: The housing device (10) includes a first housing (101), a folding mechanism (102), and a second housing (103), wherein the folding mechanism (102) connects the first housing (101) and the second housing (103); A circuit assembly (30) includes a first circuit board (301) and a second circuit board (302), the first circuit board (301) being mounted on the first housing (101) and the second circuit board (302) being mounted on the second housing (103); and The flexible display screen (20) as described in claim 18 or 19 is mounted on the first housing (101) and the second housing (103), and the first circuit board (301) and the second circuit board (302) communicate through the flexible circuit board (205) of the flexible display screen (20).

21. An electronic device (100), characterized in that, include: The first device (40), the second device (50), and the flexible circuit board (205) as claimed in any one of claims 1 to 17, wherein the first device (40) and the second device (50) communicate through the flexible circuit board (205).

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