Flexible circuit board and foldable electronic equipment

Abstract

The invention provides a flexible circuit board and foldable electronic equipment. The flexible circuit board is provided with a first area, a second area and a third area which are arranged in sequence; the flexible circuit board comprises multiple layers of sub-circuit boards arranged in a stacked mode and bonding layers located between every two adjacent layers of sub-circuit boards, each bonding layer comprises a first connecting part and a second connecting part, the first connecting parts are located in the first area and connected with the two adjacent layers of sub-circuit boards, and the second connecting parts are located in the second area and connected with the two adjacent layers of sub-circuit boards. The second connecting part is located in the third area and is connected with the two adjacent layers of sub-circuit boards, and the bonding layer avoids the second area, so that a first gap is formed in the position, corresponding to the second area, of the two adjacent layers of sub-circuit boards. The flexible circuit board is high in reliability and long in bending life.

Description

Technical Field

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

[0002] With the development of technology and the improvement of people's daily life needs, electronic devices such as mobile phones and PDAs are no longer limited to straight-board designs, but have appeared in folding forms. In other words, foldable electronic devices have emerged. Foldable electronic devices include flexible circuit boards, which are usually arranged corresponding to the bendable parts of the foldable electronic devices. The flexible circuit boards in the related art are prone to breakage and failure when bent, which makes the reliability of the flexible circuit boards low and the lifespan short. Summary of the invention

[0003] In a first aspect, an embodiment of the present application provides a flexible circuit board, wherein the flexible circuit board has a first area, a second area, and a third area arranged in sequence;

[0004] The flexible circuit board includes a plurality of stacked sub-circuit boards and an adhesive layer located between two adjacent sub-circuit boards, the adhesive layer includes a first connecting portion and a second connecting portion, the first connecting portion is located in the first area and connects the two adjacent sub-circuit boards, the second connecting portion is located in the third area and connects the two adjacent sub-circuit boards, and the adhesive layer avoids the second area so that a first gap is formed between the two adjacent sub-circuit boards corresponding to the second area.

[0005] In a second aspect, an embodiment of the present application provides a foldable electronic device, the foldable electronic device comprising:

[0006] A first main body, the first main body comprising a first circuit board;

[0007] a second main body portion, the second main body portion comprising a second circuit board;

[0008] a bendable portion, the bendable portion being located between the first main body portion and the second main body portion; and

[0009] As for the flexible circuit board as described in the first aspect, the first area of ​​the flexible circuit board is arranged corresponding to the first main body and electrically connected to the first circuit board, the second area is arranged corresponding to the bendable part, and the third area is arranged corresponding to the second main body and electrically connected to the second circuit board.

[0010] In summary, the flexible circuit board provided in the embodiment of the present application includes a plurality of stacked sub-circuit boards and an adhesive layer located between two adjacent layers of sub-circuit boards. When the flexible circuit board is bent from the second region, the bending radius of the sub-circuit board located on the outer layer of the flexible circuit board is greater than the bending radius of the sub-circuit board located on the inner layer of the flexible circuit board, so the sub-circuit board on the outer layer of the flexible circuit board is not easy to break. Further, when the flexible circuit board is bent from the second region, the bending radius of the sub-circuit board located on the inner layer of the flexible circuit board is smaller than the bending radius of the sub-circuit board located on the outer layer of the flexible circuit board. Since the adhesive layer of the flexible circuit board avoids the second region, so that the adjacent two layers of sub-circuit boards form a first gap corresponding to the second region, the first gap can release the extrusion force on the sub-circuit board located on the inner layer, so that the sub-circuit board located on the inner layer of the flexible circuit board is not easy to break, thereby improving the reliability and bending life of the flexible circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the implementation will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 A top view of a flexible circuit board provided in one embodiment of the present application;

[0013] Figure 2 For one embodiment Figure 1 A cross-sectional view of the flexible circuit board along line II provided in;

[0014] Figure 3 For another embodiment Figure 1 A cross-sectional view of the flexible circuit board along line II provided in;

[0015] Figure 4 for Figure 3 A detailed identification diagram of the flexible circuit board shown in FIG.

[0016] Figure 5 For another embodiment Figure 1 A cross-sectional view of the flexible circuit board along line II provided in;

[0017] Figure 6 This is a schematic diagram of the cross section of rolled base copper under a scanning electron microscope;

[0018] Figure 7 This is a schematic diagram of the cross section of electrolytic copper under a scanning electron microscope;

[0019] Figure 8 for Figure 5 The flexible circuit board detail identification diagram shown in ;

[0020] Fig. 9 for Figure 8 A schematic diagram of the thickness of each film layer of the sub-circuit board of the flexible circuit board shown in FIG.

[0021] Fig.10 For another embodiment Figure 1 A cross-sectional view of the flexible circuit board along line II provided in;

[0022] Fig.11 A schematic diagram of a foldable electronic device in an unfolded state provided by an embodiment of the present application;

[0023] Fig.12 A schematic diagram of a foldable electronic device in a folded state provided by an embodiment of the present application;

[0024] Fig.13 for Fig.11 Schematic diagram of the partial structure of the foldable electronic device shown in. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0027] Reference to "embodiment" or "implementation" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment or implementation may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] The embodiment of the present application provides a flexible circuit board 50 and a foldable electronic device 1 including the flexible circuit board 50 . Next, the flexible circuit board 50 and the foldable electronic device 1 including the flexible circuit board 50 provided in the embodiment of the present application are introduced in detail.

[0029] Please also read Figure 1 , Figure 2 and Figure 3 , Figure 1 A top view of a flexible circuit board provided in one embodiment of the present application; Figure 2 For one embodiment Figure 1 A cross-sectional view of the flexible circuit board along line II provided in; Figure 3 For another embodiment Figure 1 . The flexible circuit board 50 has a first area 500a, a second area 500b and a third area 500c arranged in sequence. The flexible circuit board 50 includes a multi-layer sub-circuit board 510 stacked and an adhesive layer 520 located between two adjacent layers of sub-circuit boards 510. The adhesive layer 520 includes a first connecting portion 521 and a second connecting portion 522. The first connecting portion 521 is located in the first area 500a and connects the two adjacent layers of sub-circuit boards 510. The second connecting portion 522 is located in the third area 500c and connects the two adjacent layers of sub-circuit boards 510. The adhesive layer 520 avoids the second area 500b so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b.

[0030] In this embodiment, the first region 500a, the second region 500b and the third region 500c of the flexible circuit board 50 are arranged along the first direction D1. The flexible circuit board 50 includes a multi-layer sub-circuit board 510 stacked in layers, where the multi-layer refers to more than or equal to two layers. Figure 2 In the schematic diagram shown, the flexible circuit board 50 includes two layers of sub-circuit boards 510 stacked in layers. Figure 3 In the schematic diagram shown, the flexible circuit board 50 includes three layers of sub-circuit boards 510 stacked in layers. It can be understood that Figure 2 and Figure 3 The number of sub-circuit boards 510 included in the flexible circuit board 50 shown should not be understood as limiting the flexible circuit board 50 provided in the embodiment of the present application. The multi-layer sub-circuit boards 510 are arranged along the second direction D2. In this embodiment, the structure of the sub-circuit boards 510 will be described in detail later.

[0031] In this embodiment, the first direction D1 is taken as an example to be a direction from right to left. In other words, the first area 500a is the area where the flexible circuit board 50 is located on the right, the third area 500c is the area where the flexible circuit board 50 is located on the left, and the second area 500b is located between the first area 500a and the third area 500c. It can be understood that as the placement posture of the flexible circuit board 50 is different, the first direction D1 can also be other directions, and accordingly, the relative positions of the first area 500a and the third area 500c are also different.

[0032] In one embodiment, the second direction D2 is perpendicular to the first direction D1. In this embodiment, the second direction D2 is taken as an example of a direction from bottom to top. It can be understood that as the flexible circuit board 50 is placed in different postures, the second direction D2 can also be other directions.

[0033] The bonding layer 520 may be, but is not limited to, bonding glue or adhesive. When the bonding layer 520 is bonding glue or adhesive, it is also referred to as Adh glue or Adh glue layer.

[0034] Accordingly, the first connection part 521 may be, but not limited to, a bonding glue or an adhesive. The second connection part 522 may be, but not limited to, a bonding glue or an adhesive. The material of the second connection part 522 may be the same as that of the first connection part 521, or the material of the second connection part 522 may be different from that of the first connection part 521, and this application does not limit this.

[0035] The first connection portion 521 is located in the first area 500a and connects the two adjacent sub-circuit boards 510; the second connection portion 522 is located in the second area 500b and connects the two adjacent layers of sub-circuit boards 510; therefore, the two adjacent layers of sub-circuit boards 510 are connected together.

[0036] In addition, the adhesive layer 520 avoids the second area 500b, that is, the second area 500b is not provided with the adhesive layer 520. In other words, the first connection portion 521 and the second connection portion 522 are spaced apart to form a first gap 520a corresponding to the second area 500b.

[0037] Since the adjacent two layers of sub-circuit boards 510 have the first gap 520a corresponding to the second area 500b, the adjacent two layers of sub-circuit boards 510 of the circuit board are not connected together in the second area 500b. This structure of the flexible circuit board 50 is also called a delaminated structure.

[0038] In order to conveniently introduce the beneficial effects of the flexible circuit board 50 provided by the embodiment of the present application, the flexible circuit board 50 in the related art is first introduced. In the flexible circuit board 50 in the related art, the first gap 520a does not exist in the second area 500b corresponding to the two adjacent layers of sub-circuit boards 510 of the flexible circuit board 50. In other words, the adhesive layer 520 of the flexible circuit board 50 in the related art is a whole layer structure, that is, the adhesive layer 520 of the flexible circuit board 50 in the related art is set corresponding to the first area 500a, the second area 500b, and the third area 500c. Therefore, when the flexible circuit board 50 in the related art is bent from the second area 500b, the bending radius of the sub-circuit board 510 of the flexible circuit board 50 located in the inner layer is smaller than the bending radius of the sub-circuit board 510 of the flexible circuit board 50 located in the outer layer, and the inner sub-circuit board 510 corresponding to the second area 500b is compressed and the pressure has nowhere to be released, which causes the inner sub-circuit board 510 corresponding to the second area 500b to be easily broken and fail.

[0039] In the flexible circuit board 50 provided in the embodiment of the present application, when the flexible circuit board 50 is bent from the second area 500b, the bending radius of the sub-circuit boards 510 of each layer of the flexible circuit board 50 is different. Specifically, the bending radius of the sub-circuit board 510 located at the outer layer of the flexible circuit board 50 is greater than the bending radius of the sub-circuit board 510 located at the inner layer of the flexible circuit board 50. Since the bending radius of the sub-circuit board 510 located at the outer layer of the flexible circuit board 50 is greater than the bending radius of the sub-circuit board 510 located at the flexible circuit board 50 when the flexible circuit board 50 is bent from the second area 500b, the sub-circuit board 510 at the outer layer of the flexible circuit board 50 is not easy to break. Furthermore, when the flexible circuit board 50 is bent from the second area 500b, the bending radius of the sub-circuit board 510 located on the inner layer of the flexible circuit board 50 is smaller than the bending radius of the sub-circuit board 510 located on the outer layer of the flexible circuit board 50. Since the adhesive layer 520 of the flexible circuit board 50 avoids the second area 500b, so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b, the first gap 520a can release the extrusion force on the sub-circuit board 510 located on the inner layer, so that the sub-circuit board 510 located on the inner layer of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50.

[0040] In summary, the flexible circuit board 50 provided in the embodiment of the present application includes a plurality of stacked sub-circuit boards 510 and an adhesive layer 520 located between two adjacent layers of sub-circuit boards 510. When the flexible circuit board 50 is bent from the second area 500b, the bending radius of the sub-circuit board 510 located on the outer layer of the flexible circuit board 50 is greater than the bending radius of the sub-circuit board 510 located on the outer layer of the flexible circuit board 50, so the sub-circuit board 510 on the outer layer of the flexible circuit board 50 is not easy to break. Furthermore, when the flexible circuit board 50 is bent from the second area 500b, the bending radius of the sub-circuit board 510 located on the inner layer of the flexible circuit board 50 is smaller than the bending radius of the sub-circuit board 510 located on the outer layer of the flexible circuit board 50. Since the adhesive layer 520 of the flexible circuit board 50 avoids the second area 500b, so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b, the first gap 520a can release the extrusion force on the sub-circuit board 510 located on the inner layer, so that the sub-circuit board 510 located on the inner layer of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50.

[0041] Please also read Figure 3 and Figure 4 , Figure 4 for Figure 3 Detailed identification diagram of the flexible circuit board shown in . In this embodiment, the adhesive layer 520 also avoids the portion of the first area 500a adjacent to the second area 500b, so that the adjacent two-layer sub-circuit board 510 forms a second gap 520b corresponding to the portion of the first area 500a adjacent to the second area 500b, and the second gap 520b is connected to the first gap 520a. The adhesive layer 520 also avoids the portion of the third area 500c adjacent to the second area 500b, so that the adjacent two-layer sub-circuit board 510 forms a third gap 520c corresponding to the portion of the third area 500c adjacent to the second area 500b, and the third gap 520c is connected to the first gap 520a.

[0042] In one embodiment, the boundary between the first area 500a and the second area 500b is named as the first boundary L1, and the boundary between the third area 500c and the second area 500b is named as the second boundary L2. In other words, the first area 500a and the second area 500b have the first boundary L1, and the third area 500c and the second area 500b have the second boundary L2.

[0043] In an embodiment, the adhesive layer 520 avoids the portion of the first area 500a adjacent to the second area 500b, so that the adjacent two layers of sub-circuit boards 510 form a second gap 520b corresponding to the portion of the first area 500a adjacent to the second area 500b. In other words, there is a distance between the first connecting portion 521 and the first boundary line L1, so that the adjacent two layers of sub-circuit boards 510 and the first connecting portion 521 located between the two layers of sub-circuit boards 510 cooperate to form the second gap 520b.

[0044] In this embodiment, the adhesive layer 520 avoids the portion of the third area 500c adjacent to the second area 500b, so the adjacent two layers of sub-circuit boards 510 form a third gap 520c corresponding to the portion of the third area 500c adjacent to the second area 500b. In other words, there is a distance between the second connecting portion 522 and the second boundary line L2, so that the adjacent two layers of sub-circuit boards 510 and the second connecting portion 522 located between the two layers of sub-circuit boards 510 cooperate to form the third gap 520c.

[0045] When the flexible circuit board 50 corresponds to the foldable electronic device 1 (see Figures 11 to 13 ) is set, the first area 500a corresponds to the first main body 10 of the foldable electronic device 1, the third area 500c corresponds to the second main body 20 of the foldable electronic device 1, and the second area 500b corresponds to the bendable part 30 of the foldable electronic device 1.

[0046] In this embodiment, in addition to the first gap 520a, the flexible circuit board 50 also has a second gap 520b and a third gap 520c. In the flexible circuit board 50, the second gap 520b is connected to the first gap 520a and the third gap 520c is connected to the first gap 520a to form an overall gap, and the overall gap is larger than the second area 500b.

[0047] In this embodiment, the adhesive layer 520 also avoids the portion of the first area 500a adjacent to the second area 500b, so that the adjacent two layers of sub-circuit boards 510 form a second gap 520b corresponding to the portion of the first area 500a adjacent to the second area 500b, and the second gap 520b is connected to the first gap 520a; therefore, the first connecting portion 521 is located in the first area 500a, and the first connecting portion 521 is at a certain distance from the boundary line (first boundary line L1) between the first area 500a and the second area 500b, so that when the second area 500b of the flexible circuit board 50 is bent, the first connecting portion 521 is in a static non-stress state, or a small stress state. Further, the boundary of the first connecting portion 521 adjacent to the second area 500b is also in a static non-stress state, or a small stress state. The first connection portion 521 is in a non-stress state, or a small stress state, so that when the second area 500b of the flexible circuit board 50 is bent, the first connection portion 521 does not squeeze or squeezes with small force the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 at the first boundary line L1, so that the sub-circuit board 510 in the inner layer of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50.

[0048] Furthermore, the adhesive layer 520 also avoids the portion of the third area 500c adjacent to the second area 500b, so that the adjacent two layers of sub-circuit boards 510 form a third gap 520c corresponding to the portion of the third area 500c adjacent to the second area 500b, and the third gap 520c is connected to the first gap 520a; therefore, the second connection portion 522 is located in the third area 500c, and the second connection portion 522 is at a certain distance from the boundary line (second boundary line L2) between the third area 500c and the second area 500b, so that when the second area 500b of the flexible circuit board is bent, the second connection portion 522 is in a static non-stress state, or a small stress state. Further, the second connection portion 522 adjacent to the boundary of the second area 500b is also in a static non-stress state, or a small stress state. The second connection portion 522 is in a non-stressed state, or a relatively small stress state, so that when the second area 500b of the flexible circuit board 50 is bent, the second connection portion 522 does not squeeze or squeezes relatively small force on the inner sub-circuit board 510 of the flexible circuit board 50 at the second boundary line L2, so that the inner sub-circuit board 510 of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50.

[0049] See also Figure 5 , Figure 5For another embodiment Figure 1 . In this embodiment, the sub-circuit board 510 includes a conductive layer 512. The first connecting portion 521 has a via hole 522a, and the flexible circuit board 50 also includes a conductive member 530, which is located in the via hole 522a and electrically connects the conductive layers 512 of two adjacent layers of the sub-circuit boards 510.

[0050] The conductive layer 512 may be, but is not limited to, base copper. When the conductive layer 512 is base copper, the conductive layer 512 may include, but is not limited to, electrolytic base copper or rolled base copper. In this embodiment, the conductive layer 512 includes rolled base copper as an example for illustration, which should be understood not to be a limitation on the flexible circuit board 50 provided in the embodiment of the present application.

[0051] The conductive member 530 may be, but is not limited to, a conductive member 530 formed by electroplating. For example, when the conductive member 530 includes copper, the conductive member 530 may include, but is not limited to, electroplated copper. When the conductive member 530 includes electroplated copper, the conductive member 530 has better electrical connection performance when electrically connecting the conductive layers 512 of the two adjacent layers of the sub-circuit boards 510.

[0052] Generally, when the conductive member 530 includes electroplated copper, the conductive member 530 has good electrical connection performance. However, there is an obvious contact surface between the crystal particles of the electroplated copper, which is easy to break and delaminate. If the electroplated copper is located in the second bendable area 500b of the flexible circuit board 50, then when the second area 500b of the flexible circuit board 50 is repeatedly bent, the contact surface between the crystal particles of the electroplated copper slides and is easy to break, thereby causing the flexible circuit board 50 to fail.

[0053] As can be seen from the above description, the first connection part 521 is arranged corresponding to the first area 500a, the first connection part 521 has a via hole 522a, and the conductive member 530 is located in the via hole 522a. Therefore, the conductive member 530 is arranged corresponding to the first area 500a. When the flexible circuit board 50 is bent, the second area 500b is bent, and the second area 500b is a bent area. The first area 500a and the third area 500c are both non-bent areas. The conductive member 530 is arranged corresponding to the first area 500a, that is, the conductive member 530 is arranged corresponding to the non-bent area of ​​the flexible circuit board 50. Therefore, when the second area 500b of the flexible circuit board 50 is bent, the conductive member 530 will not be bent or squeezed or is less bent and squeezed, so that the electrical connection performance of the conductive layer 512 of the adjacent two layers of sub-circuit boards 510 is better.

[0054] In one embodiment, the conductive layer 512 includes rolled base copper, the conductive member 530 includes electroplated copper, and the conductive layer 512 does not include electroplated copper. In other words, in the flexible circuit board 50 provided in one embodiment, not all conductive film layers include electroplated copper, thereby avoiding the reduction of the bending life of the flexible circuit board 50 when the electroplated copper is located in the second area 500b.

[0055] The flexible circuit board 50 provided in the embodiment of the present application is prepared by using a selective copper plating process, and the conductive member 530 is formed by using an electroplating process at the via hole 522a corresponding to the via hole 522a, and no copper is plated in the conductive layer 512 of the sub-circuit board 510 of the flexible circuit board 50, and the conductive layer 512 is retained to include electrolytic copper or rolled copper. As can be seen from the previous introduction, if the electroplated copper is bent, the contact surface between the crystal particles of the electroplated copper is dislocated and slid, and it is easy to break, thereby causing the flexible circuit board 50 to fail. The flexible circuit board 50 provided in the embodiment of the present application is electroplated in the via hole 522a of the first connecting part 521 set in the first area 500a to form electroplated copper, and no electroplated copper is set in the conductive layer 512 of the sub-circuit board 510 of the flexible circuit board 50, thereby avoiding the thickness of the conductive layer 512 to be large, and also avoiding the thickness of the connecting adhesive layer 513 caused by the large thickness of the conductive layer 512, and also avoiding the risk of easy bending and breaking of the conductive layer 512.

[0056] For further information, please refer to Figure 5 , the flexible circuit board 50 includes a plurality of adhesive layers 520. The via holes 522a of the first connection portion 521 of one of the plurality of adhesive layers 520 are alternately arranged with the via holes 522a of the first connection portion 521 of another of the plurality of adhesive layers 520.

[0057] As can be seen from the above description, the flexible circuit board 50 includes a plurality of sub-circuit boards 510 stacked in layers and an adhesive layer 520 located between two adjacent layers of sub-circuit boards 510. Specifically, the flexible circuit board 50 includes N layers of sub-circuit boards 510 and N-1 layers of adhesive layers 520, wherein N is a positive integer and N≥2. In this embodiment, N=3 is used as an example for illustration. That is, in this embodiment, the flexible circuit board 50 includes three layers of sub-circuit boards 510 stacked in layers and two layers of adhesive layers 520 as an example for illustration. It can be understood that the number of sub-circuit boards 510 and the number of adhesive layers 520 in the embodiment of the present application should not be understood as a limitation on the flexible circuit board 50 provided in the embodiment of the present application.

[0058] Each bonding layer 520 includes a first connection portion 521, and each first connection portion 521 has a via hole 522a. The via holes 522a of the first connection portion 521 of one of the plurality of bonding layers 520 are arranged alternately with the via holes 522a of the first connection portion 521 of another of the plurality of bonding layers 520, including: the distance from the via hole 522a of the first connection portion 521 of the one of the plurality of bonding layers 520 to the first boundary line L1 is not equal to the distance from the via hole 522a of the first connection portion 521 of the other of the plurality of bonding layers 520. Accordingly, the distance from the conductive member 530 in the via hole 522a of the first connection portion 521 of the one of the plurality of bonding layers 520 to the first boundary line L1 is not equal to the distance from the conductive member 530 in the via hole 522a of the first connection portion 521 of the other of the plurality of bonding layers 520.

[0059] In the schematic diagram of this embodiment, the distance between the sub-conductive member 530 located at the bottom and the first boundary line L1 is greater than the distance between the sub-conductive member 530 located at the top and the first boundary line L1. It can be understood that this should not be understood as a limitation on the flexible circuit board 50 provided in the embodiment of the present application.

[0060] The flexible circuit board 50 includes a plurality of adhesive layers 520. The via holes 522a of the first connection part 521 of one of the plurality of adhesive layers 520 are arranged alternately with the via holes 522a of the first connection part 521 of another of the plurality of adhesive layers 520, so that the conductive members 530 located in the via holes 522a of the first connection part 521 are arranged alternately. Therefore, when the flexible circuit board 50 is bent from the second area 500b, the conductive members 530 are squeezed less or not squeezed, so that the conductive members 530 have better electrical connection performance. In addition, it is also convenient to electrically connect the flexible circuit board 50 with the components arranged on the circuit board when the flexible circuit board 50 is connected to the circuit board.

[0061] See also Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the cross section of rolled base copper under a scanning electron microscope; Figure 7 Schematic diagram of the cross section of electrolytic copper under a scanning electron microscope. In this embodiment, the conductive layer 512 includes rolled copper.

[0062] Rolled copper is also called rolled copper, and electrolytic copper is also called electrolytic copper. Figure 6 and Figure 7It can be seen that the crystal particles of the rolled copper are different from the crystal particles of the electrolytic copper. Specifically, the particle size of the crystal particles of the rolled copper is larger than that of the electrolytic copper, the contact surface between the crystal particles of the rolled copper is less than that between the crystal particles of the electrolytic copper, and the fracture starting point of the rolled copper is less than that of the electrolytic copper. Therefore, when the flexible circuit board 50 is bent from the second area 500b, the possibility of fracture of the contact surface between the crystal particles of the rolled copper is greatly reduced compared with the electrolytic copper.

[0063] It can be seen that in the flexible circuit board 50 provided in the embodiment of the present application, the conductive layer 512 includes rolled base copper. Therefore, when the second area 500b of the flexible circuit board 50 is bent, the contact surface of the crystal particles of the rolled base copper is not easy to slide out of position, and is not easy to break. Therefore, it is not easy to cause the conductive layer 512 to break. In summary, the conductive layer 512 of the flexible circuit board 50 provided in the embodiment of the present application includes rolled base copper, and the conductive layer 512 of the flexible circuit board 50 has good bending resistance, and the conductive layer 512 of the flexible circuit board 50 is not easy to break.

[0064] Please also refer to Figure 5 , Figure 8 and Fig. 9 , Figure 8 for Figure 5 The flexible circuit board detail identification diagram shown in ; Fig. 9 for Figure 8 Schematic diagram of the thickness of each film layer of the sub-circuit board of the flexible circuit board shown in . The sub-circuit board 510 includes a base layer 511, a conductive layer 512, a connecting adhesive layer 513 and a coating layer 514 stacked in sequence. The thickness d1 of the base layer 511 satisfies: 10μm≤d1≤18μm. The thickness d2 of the conductive layer 512 satisfies: 5μm≤d2≤10μm. The thickness d3 of the connecting adhesive layer 513 satisfies: 8μm≤d3≤15μm, and the thickness of the connecting adhesive layer 513 is greater than the thickness of the conductive layer 512.

[0065] exist Fig. 9 In the figure, the base layer 511, the conductive layer 512 and the connecting adhesive layer 513 in the sub-circuit board 510 at the top are taken as an example. It can be understood that the thickness of the base layer 511, the conductive layer 512 and the connecting adhesive layer 513 in other sub-circuit boards 510 also meets the above range. It can be understood that the thickness of the same film layer in each sub-circuit 510 can be the same or different, and this application does not limit this, as long as it meets the above range.

[0066] The material of the base layer 511 may include but is not limited to polyimide (PI). When the material of the base layer 511 includes PI, the base layer 511 is also referred to as PI base. Please refer to the previous description for the conductive layer 512, which will not be repeated here.

[0067] The thickness d1 of the base layer 511 may be, but is not limited to, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, or 18 μm.

[0068] When the thickness of the base layer 511 is too small, the strength of the base layer 511 is weak, and the base layer 511 is easily damaged. When the thickness of the base layer 511 is too large, the bending performance of the base layer 511 is poor, it is easy to break, and the bending radius of the flexible circuit board 50 is large. In the flexible circuit board 50 provided in the embodiment of the present application, the thickness d1 of the base layer 511 satisfies: 10μm≤d1≤18μm, on the one hand, the base layer 511 can have relatively good strength, and the base layer 511 is not easily damaged; on the other hand, the base layer 511 has good bending performance, is not easy to break, and the flexible circuit board 50 has a smaller bending radius. In addition, in the flexible circuit board 50 provided in the embodiment of the present application, the thickness d1 of the base layer 511 satisfies: 10μm≤d1≤18μm, and the cost of the flexible circuit board 50 can also be taken into account, so that the cost of the flexible circuit board 50 is not too high.

[0069] The material of the conductive layer 512 can be found in the previous description and will not be described again.

[0070] The thickness d2 of the conductive layer 512 may be, but is not limited to, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0071] When the thickness of the conductive layer 512 is too small, the strength of the conductive layer 512 is relatively weak, and the electrical connection performance of the conductive layer 512 is relatively poor. When the thickness of the conductive layer 512 is too large, the bending performance of the conductive layer 512 is poor, it is easy to break, and the bending radius of the flexible circuit board 50 is large. In the flexible circuit board 50 provided in the embodiment of the present application, the thickness d2 of the conductive layer 512 satisfies: 5μm≤d2≤10μm, on the one hand, the conductive layer 512 has relatively good strength and electrical connection performance, and the conductive layer 512 is not easily damaged; on the other hand, the conductive layer 512 has good bending performance, is not easy to break, and the flexible circuit board 50 has a smaller bending radius.

[0072] In one embodiment, the conductive layer 512 has one or more conductive lines. When the conductive layer 512 includes a plurality of conductive lines, there is a gap between two adjacent conductive lines.

[0073] The connecting adhesive layer 513 is used to bond the conductive layer 512 and the coating layer 514. When there is a gap between two adjacent conductive lines in the conductive layer 512, the connecting adhesive layer 513 is used to fill the gap between the two adjacent conductive lines. The thickness of the connecting adhesive layer 513 is greater than the thickness of the conductive layer 512. Therefore, after the connecting adhesive layer 513 fills the gap between the two adjacent conductive lines, it can also be bonded to the coating layer 514, thereby ensuring the integrity of the sub-conductive layer 512.

[0074] The thickness d3 of the connecting adhesive layer 513 may be, but is not limited to, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm.

[0075] When the thickness of the connecting adhesive layer 513 is small, the connection effect of the connecting adhesive layer 513 is not good. When the thickness of the connecting adhesive layer 513 is large, the bending performance of the connecting adhesive layer 513 is poor, which leads to a large bending radius of the flexible circuit board 50. In the flexible circuit board 50 provided in the embodiment of the present application, the thickness d3 of the connecting adhesive layer 513 satisfies: 8μm≤d3≤15μm, which can ensure that the connection effect of the connecting adhesive layer 513 is good on the one hand; on the other hand, it can ensure that the bending performance of the flexible circuit board 50 is good and the bending radius is small.

[0076] The material of the cover layer 514 may be, but is not limited to, polyimide (PI), etc. The cover layer 514 is used to protect the conductive layer 512 .

[0077] For further information, see Figure 8 The flexible circuit board 50 includes a first surface 50a and a second surface 50b disposed opposite to each other. The multi-layer sub-circuit board 510 includes a first sub-circuit board 510a adjacent to the first surface 50a and a second sub-circuit board 510b adjacent to the second surface 50b. The base layer 511 of the first sub-circuit board 510a is away from the first surface 50a compared to the coating layer 514 of the first sub-circuit board 510a. The base layer 511 of the second sub-circuit board 510b is away from the second surface 50b compared to the coating layer 514 of the second sub-circuit board 510b.

[0078] In this embodiment, the first surface 50a and the second surface 50b of the flexible circuit board 50 are disposed opposite to each other, the first surface 50a is the outermost surface of the flexible circuit board 50, and the second surface 50b is the outermost surface of the flexible circuit board 50. In this embodiment, in the stacking direction of the plurality of sub-circuit boards 510, the first sub-circuit board 510a and the second sub-circuit board 510b are respectively the two outermost sub-circuit boards 510 of the flexible circuit board 50.

[0079] The base layer 511 of the first sub-circuit board 510a is away from the first surface 50a compared to the coating layer 514 of the first sub-circuit board 510a. In other words, the coating layer 514 of the first sub-circuit board 510a is adjacent to the first surface 50a compared to the base layer 511 of the first sub-circuit board 510a, or the surface of the coating layer 514 of the first sub-circuit board 510a away from the base layer 511 of the first sub-circuit board 510a is the first surface 50a. When the flexible circuit board 50 is electrically connected to the circuit of the circuit board or the device of the circuit board, a hole is usually opened in the coating layer 514 and the connecting glue layer 513 of the first sub-circuit board 510a to expose the conductive layer 512 of the first sub-circuit board 510a, so that the conductive layer 512 of the first sub-circuit board 510a is electrically connected to the circuit of the circuit board or the device of the circuit board.

[0080] Correspondingly, the base layer 511 of the second sub-circuit board 510b is away from the second surface 50b compared to the coating layer 514 of the second sub-circuit board 510b. In other words, the coating layer 514 of the second sub-circuit board 510b is adjacent to the second surface 50b compared to the base layer 511 of the second sub-circuit board 510b, or the surface of the coating layer 514 of the second sub-circuit board 510b away from the base layer 511 of the second sub-circuit board 510b is the second surface 50b. When the flexible circuit board 50 is electrically connected to the exposed part of the circuit board or the device of the circuit board, a hole is usually opened in the coating layer 514 and the connecting glue layer 513 of the second sub-circuit board 510b to expose the conductive layer 512 of the second sub-circuit board 510b, so that the conductive layer 512 of the second sub-circuit board 510b is electrically connected to the circuit of the circuit board or the device of the circuit board.

[0081] In this embodiment, the flexible circuit board includes a three-layer sub-circuit board 510. In other words, the multi-layer sub-circuit board 510 includes a first sub-circuit board 510a, a second sub-circuit board 510b and a third sub-circuit board 510c. The third sub-circuit board 510c is located between the first sub-circuit board 510a and the second sub-circuit board 510b.

[0082] In an embodiment, the base layer 511 of the third sub-circuit board 510c is adjacent to the second sub-circuit board 510b compared to the conductive layer 512 of the third sub-circuit board 510c. It can be understood that in other embodiments, the third sub-circuit board 510c is located between the first sub-circuit board 510a and the second sub-circuit board 510b, and the base layer 511 of the third sub-circuit board 510c is away from the second sub-circuit board 510b compared to the conductive layer 512 of the third sub-circuit board 510c.

[0083] In the schematic diagram of this embodiment, the flexible circuit board 50 includes three layers of sub-circuit boards 510, and accordingly, the flexible circuit board 50 includes two adhesive layers 520. For the convenience of description, the adhesive layer 520 located between the first sub-circuit board 510a and the third sub-circuit board 510c is named as adhesive layer 52a, and the adhesive layer 520 located between the second sub-circuit board 510b and the third sub-circuit board 510c is named as adhesive layer 52b. Accordingly, the conductive member 530 electrically connecting the conductive layer 512 of the first sub-circuit board 510a and the conductive layer 512 of the third sub-circuit board 510c is named as conductive member 530a; the conductive member 530 electrically connecting the conductive layer 512 of the second sub-circuit board 510b and the conductive layer 512 of the third sub-circuit board 510c is named as conductive member 530b.

[0084] The base layer 511 of the first sub-circuit board 510a, the coating layer 514 of the third sub-circuit board 510c, and the connecting adhesive layer 513 of the third sub-circuit board 510c all have through holes, and the through holes are connected to the via holes 522a of the first main body 10 of the bonding layer 52a. In this way, the conductive member 530a is located in the through holes and the via holes 522a of the first main body 10 of the bonding layer 52a to electrically connect the conductive layer 512 of the first sub-circuit board 510a with the conductive layer 512 of the second sub-circuit board 510b.

[0085] Correspondingly, the base layer 511 of the second sub-circuit board 510b and the base layer 511 of the third sub-circuit board 510c both have through holes, and the through holes are connected to the through holes 522a of the first main body 10 of the bonding layer 52b. In this way, the conductive member 530b is located in the through holes 522a of the first main body 10 of the bonding layer 52b to electrically connect the conductive layer 512 of the second sub-circuit board 510b with the conductive layer 512 of the third sub-circuit board 510c.

[0086] See also Fig.10 , Fig.10 For another embodiment Figure 1A cross-sectional view of the flexible circuit board provided in the embodiment along line II. In this embodiment, the flexible circuit board 50 further includes an electromagnetic shielding film 540. The electromagnetic shielding film 540 is arranged on the side of the first sub-circuit board 510a away from the second sub-circuit board 510b. The flexible circuit board 50 further includes an electromagnetic shielding film 540 which can be combined with the flexible circuit board 50 provided in any of the previous embodiments. In the schematic diagram of this embodiment, the flexible circuit board 50 further includes an electromagnetic shielding film 540 combined with Figure 5 The flexible circuit board 50 shown in the illustrated embodiment is used as an example for illustration, and it can be understood that it should not be construed as a limitation on the embodiments of the present application.

[0087] The electromagnetic shielding film 540 can be used to shield electromagnetic radiation interference to protect the signal transmitted in the flexible circuit board 50 from interference or less interference. In one embodiment, the electromagnetic shielding film 540 includes a metal layer that can only shield electromagnetic waves, such as a silver paste layer.

[0088] In one implementation, the electromagnetic shielding film 540 may be attached to the surface of the first sub-circuit board 510 a facing away from the second sub-circuit board 510 b by glue.

[0089] In one embodiment, the electromagnetic shielding film 540 is resistant to bending and is not easily broken by bending.

[0090] In one embodiment, the thickness of the electromagnetic shielding film 540 is less than or equal to 10 μm. For example, the thickness of the electromagnetic shielding film 540 is 5 μm to 10 μm. For example, the thickness of the electromagnetic shielding film 540 is 5 μm, or 6 μm, or 7 μm, or 8 μm, or 9 μm, or 10 μm. The thickness of the electromagnetic shielding film 540 is 5 μm to 10 μm. On the one hand, the electromagnetic shielding film 540 has a better shielding effect; on the other hand, the electromagnetic shielding film 540 has a better bending performance, is not easy to break, and makes the flexible circuit board 50 have a smaller bending radius.

[0091] When the flexible circuit board 50 is also covered with an electromagnetic shielding film 540, the surface of the electromagnetic shielding film 540 facing away from the first sub-circuit board 510a is the first surface 50a of the flexible circuit board 50; when the flexible circuit board 50 does not include the electromagnetic shielding film 540, the surface of the first sub-circuit board 510a facing away from the second sub-circuit board 510b is the first surface 50a.

[0092] Please continue reading Figure 1 , Figure 3In the drawings, in one embodiment, the number of layers N of the sub-circuit boards 510 included in the flexible circuit board 50 satisfies: N≥3; and the width W of the flexible circuit board 50 satisfies: 10mm≤W≤50mm.

[0093] In one embodiment, the number N of layers of the sub-circuit boards 510 included in the flexible circuit board 50 satisfies 3≤W≤10. For example, the number N of layers of the sub-circuit boards 510 included in the flexible circuit board 50 may be, but is not limited to, 3, 4, 5, 6, 7, 8, 9, or 10.

[0094] The width W of the flexible circuit board 50 may be, but is not limited to, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, or 50 mm.

[0095] The conductive layer 512 in the flexible circuit board 50 has a conductor to transmit electrical signals. When the number of electrical signals to be transmitted is certain, the more layers of sub-circuit boards 510 in the flexible circuit board 50, the smaller the width of the flexible circuit board 50. In the flexible circuit board 50 provided in the embodiment of the present application, the number of layers N of the sub-circuit boards 510 included in the flexible circuit board 50 satisfies: N ≥ 3; the width W of the flexible circuit board 50 satisfies: 10mm ≤ W ≤ 50mm, so that the flexible circuit board 50 can meet the demand for transmitting electrical signals, and the width of the flexible circuit board 50 is narrow, and when the flexible circuit board 50 is applied to the foldable electronic device 1, it is convenient to assemble in the foldable electronic device 1.

[0096] In one embodiment, the flexible circuit board 50 includes a three-layer sub-circuit board 510, and the thickness of the flexible circuit board 50 is less than 200μm (for example, less than or equal to 195μm), wherein the thickness of the portion of the flexible circuit board 50 located in the second area 500b is less than or equal to 165μm. In this embodiment, the bending life of the flexible circuit board 50 can be more than 100,000 times. It should be noted that the thickness of the flexible circuit board 50 is less than 200μm, which means that the thickness of the portion of the flexible circuit board 50 located in the first area 500a is less than 200μm, and the thickness of the portion of the flexible circuit board 50 located in the third area 500c is less than 200μm.

[0097] In one embodiment, the thickness d1 of the base layer 511 of the sub-circuit board 510 of the flexible circuit board 50 satisfies: 10 μm ≤ d1 ≤ 18 μm, the thickness d2 of the conductive layer 512 satisfies: d2 ≤ 10 μm, the thickness d3 of the connecting adhesive layer 513 satisfies: d3 ≤ 15 μm, and the thickness d4 of the coating layer 514 (see Fig. 9In other embodiments, the thickness d4 of the coating layer 514 satisfies: 10 μm≤d4≤14 μm.

[0098] In summary, the flexible circuit board 50 provided in one embodiment of the present application has a first area 500a, a second area 500b and a third area 500c arranged in sequence. When the flexible circuit board 50 is applied to the foldable electronic device 1, the second area 500b of the flexible circuit board 50 can be bent. In other words, the second area 500b of the flexible circuit board 50 is arranged corresponding to the bendable portion 30 of the foldable electronic device 1. When the flexible circuit board 50 is bent from the second area 500b, the radius of the sub-circuit board 510 of the inner layer of the flexible circuit board 50 is different from the radius of the sub-circuit board 510 of the outer layer of the flexible circuit board 50. When the flexible circuit board 50 is bent, the radius of the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 is smaller than the radius of the sub-circuit board 510 located in the outer layer of the flexible circuit board 50. The flexible circuit board 50 provided in the embodiment of the present application has an active layer removal design, that is, the adhesive layer 520 is not provided in the second area 500b of the flexible circuit board 50, so that the sub-circuit board 510 bonded by the adhesive layer 520 is separated at the second area 500b. Specifically, the flexible circuit board 50 includes a multi-layer sub-circuit board 510 stacked and an adhesive layer 520 located between two adjacent layers of sub-circuit boards 510. The adhesive layer 520 includes a first connecting portion 521 and a second connecting portion 522. The first connecting portion 521 is located in the first area 500a and connects the two adjacent layers of sub-circuit boards 510. The second connecting portion 522 is located in the third area 500c and connects the two adjacent layers of sub-circuit boards 510. The adhesive layer 520 avoids the second area 500b so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b. It can be seen that the adhesive layer 520 of the flexible circuit board 50 avoids the second area 500b so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b. Therefore, the first gap 520a can release the extrusion force on the sub-circuit board 510 located in the inner layer, so that the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50.

[0099] Furthermore, in the flexible circuit board 50, the adhesive layer 520 includes a first connection portion 521 and a second connection portion 522. The first connection portion 521 is located in the first area 500a and connects the two adjacent layers of sub-circuit boards 510. The second connection portion 522 is located in the third area 500c and connects the two adjacent layers of sub-circuit boards 510. The adhesive layer 520 avoids the second area 500b, so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a at the second area 500b; therefore, the thickness of the flexible circuit board 50 corresponding to the second area 500b is less than the thickness of the flexible circuit board 50 corresponding to the first area 500a; accordingly, the thickness of the flexible circuit board 50 corresponding to the second area 500b is less than the thickness of the flexible circuit board 50 corresponding to the third area 500c. In this way, when the flexible circuit board 50 is bent from the second area 500b, the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 is not easily broken, thereby improving the reliability and bending life of the flexible circuit board 50.

[0100] In one embodiment, when the flexible circuit board 50 is bent, the first sub-circuit board 510a is a sub-circuit board of the inner layer of the flexible circuit board 50. In another embodiment, when the flexible circuit board 50 is bent, the first sub-circuit board 510a is a sub-circuit board of the outer layer of the flexible circuit board 50. The present application does not limit whether the first sub-circuit board 510a is located in the inner layer or the outer layer when the flexible circuit board 50 is bent.

[0101] Furthermore, the flexible circuit board 50 provided in one embodiment of the present application is made of thin film layers such as a base layer 511, a conductive layer 512, and a connecting adhesive layer 513; and the conductive layer 512 of the sub-circuit board 510 in the flexible circuit board 50 is optimized, and the conductive layer 512 includes rolled base copper; the design of the via 522a in the flexible circuit board 50 and the position setting of the conductive member 530; in addition, the conductive member 530 can be, but is not limited to, electroplated copper, that is, the electroplating process of the flexible circuit board 50 is optimized. It can be seen that the above measures of the flexible circuit board 50 provided in the embodiment of the present application make the flexible circuit board 50 thinner and improve the bending life of the flexible circuit board 50. When the flexible circuit board 50 is applied to the foldable electronic device 1, it can meet the design requirements of the foldable electronic device 1, and finally bring users high-quality and high-durability products.

[0102] The flexible circuit board 50 provided in one embodiment of the present application has a relatively thin thickness and a relatively low hardness. When the flexible circuit board 50 is applied to the foldable electronic device 1, the foldable electronic device 1 has a better bending feel.

[0103] The thickness of the flexible circuit board 50 provided in one embodiment of the present application is relatively thin. When bent, the bending radius of the sub-circuit board 510 of the inner layer of the flexible circuit board 50 is slightly different from the bending radius of the sub-circuit board 510 of the outer layer of the flexible circuit board 50. After the flexible circuit board 50 is bent multiple times, the layers of the bending area (the second area 500b in this embodiment) are not easily damaged.

[0104] In addition, the flexible circuit board 50 provided in one embodiment of the present application is thinner and has a smaller bending radius. When the flexible circuit board 50 is applied to the foldable electronic device 1, it is beneficial to the miniaturization of the hinge structure corresponding to the bendable portion 30 of the foldable electronic device 1 and the compactness of the overall size of the foldable electronic device 1.

[0105] The present application provides a foldable electronic device 1, which may be, but is not limited to, a mobile phone, a PDA, a laptop computer, an e-reader, a handheld computer, an electronic display screen, a notebook computer, an ultra-mobile personal computer (UMPC), a netbook, a personal digital assistant (PDA), an augmented reality (AR)\virtual reality (VR) device, a media player, a smart wearable device, and other foldable devices. In the schematic diagram of the present embodiment, the foldable electronic device 1 is illustrated as a foldable mobile phone, which is understandable and should not be understood as a limitation on the foldable electronic device 1 provided in the embodiment of the present application.

[0106] Please also read Fig.11 , Fig.12 and Fig.13 , Fig.11 A schematic diagram of a foldable electronic device in an unfolded state provided by an embodiment of the present application; Fig.12 A schematic diagram of a foldable electronic device in a folded state provided by an embodiment of the present application; Fig.13 for Fig.11Schematic diagram of a partial structure of a foldable electronic device shown in . The foldable electronic device 1 includes a first main body 10, a second main body 20, a bendable portion 30 and a flexible circuit board 50. The first main body 10 includes a first circuit board 110. The second main body 20 includes a second circuit board 210. The bendable portion 30 is located between the first main body 10 and the second main body 20. The first area 500a of the flexible circuit board 50 is arranged corresponding to the first main body 10 and is electrically connected to the first circuit board 110, the second area 500b is arranged corresponding to the bendable portion 30, and the third area 500c is arranged corresponding to the second main body 20 and is electrically connected to the second circuit board 210.

[0107] For specific details of the flexible circuit board 50 in the foldable electronic device 1, please refer to the detailed description of the flexible circuit board 50 in the previous embodiments, which will not be repeated here.

[0108] In this embodiment, the first main body portion 10 and the second main body portion 20 are bendably connected via the bendable portion 30. The foldable electronic device 1 of this embodiment has a flattened state and a folded state. The foldable electronic device 1 can be switched from the flattened state to the folded state, and from the folded state to the flattened state. It can be understood that in one embodiment, the foldable electronic device 1 also has a hovering state (also called an intermediate state) between the folded state and the flattened state. In this embodiment, the so-called flattened state refers to the state in which the first main body portion 10 and the second main body portion 20 of the foldable electronic device 1 are flat or approximately flat. The so-called folded state refers to the state in which the first main body portion 10 and the second main body portion 20 of the foldable electronic device 1 are bent and arranged relative to each other.

[0109] In one embodiment, the first main body 10 further includes a first housing 120 , and the first housing 120 is used to carry the first circuit board 110 . The second main body further includes a second housing 220 , and the second housing 220 is used to carry the second circuit board 210 .

[0110] In one embodiment, the foldable electronic device 1 further includes a display screen 60. The display screen 60 may be, but is not limited to, various components with corresponding functions such as a touch screen, a touch display screen 60, or a display screen 60 fixedly attached to a support member, such as a display screen 60 attached to a flexible steel plate, a touch screen, a touch display screen 60, etc. The display screen 60 may be unfolded or folded along with the first housing 120 and the second housing 220. In other words, the display screen 60 may be unfolded along with the unfolding of the first housing 120 and the second housing 220, and may be folded along with the folding of the first housing 120 and the second housing 220.

[0111] The display screen 60 includes a first display portion 610, a bendable display portion 620, and a second display portion 630. The first display portion 610 is fixed to the first housing 120, and the second display portion 630 is fixed to the second housing 220. The first display portion 610 and the second display portion 630 are respectively connected to two opposite sides of the bendable display portion 620. The display screen 60 includes the first display portion 610, the bendable display portion 620, and the second display portion 630, that is, the first main body 10 also includes the first display portion 610, and the second main body 20 also includes the second display portion 630.

[0112] In one embodiment, the foldable electronic device 1 may be an inward-folding electronic device. That is, when the electronic device 1 is in a folded state, the display screen 60 is located on the inner side of the foldable electronic device. The inward-folding foldable electronic device 1 can effectively reduce the possibility of the display screen 60 being hit, which is conducive to extending the service life of the display screen 60.

[0113] In another embodiment, the foldable electronic device 1 may be an outward-folding electronic device. That is, when the foldable electronic device 1 is in a folded state, the display screen 60 is located outside the foldable electronic device 1. The outward-folding foldable electronic device 1 is still convenient for the user to use the display screen 60 when the foldable electronic device 1 is in a folded state.

[0114] The foldable electronic device 1 provided in the embodiment of the present application is an inward-folding electronic device. It can be understood that this should not be construed as a limitation on the foldable electronic device 1 provided in the embodiment of the present application.

[0115] In addition, in the embodiment of the present application, the foldable electronic device 1 includes two main body parts (i.e., a first main body part 10 and a second main body part 20) as an example for illustration. In other words, the foldable electronic device 1 shown in the schematic diagram of the embodiment of the present application is a two-folding electronic device. It can be understood that in other embodiments, the foldable electronic device 1 includes three or more main body parts (also called folding blocks). In other words, the foldable electronic device 1 includes multiple main body parts (identified as Q main body parts), where Q is greater than or equal to 2, and Q is a positive integer.

[0116] In one embodiment, taking into account the uniformity of the weight of the foldable electronic device 1 and making full use of the internal space of the foldable electronic device 1, multiple electrical components (such as batteries, circuit modules, etc.) inside the foldable electronic device 1 are distributed in the multiple main body parts. For example, when the foldable electronic device 1 includes two main body parts, namely, a first main body part 10 and a second main body part 20, multiple electrical modules (such as batteries, circuit modules, etc.) inside the foldable electronic device 1 are distributed in the first main body part 10 and the second main body part 20. The multiple electrical modules inside the electronic device need to be electrically connected. Specifically, in this embodiment, the first main body part 10 includes a first circuit board 110, the second main body part 20 includes a second circuit board 210, and the flexible circuit board 50 electrically connects the first circuit board 110 and the second circuit board 210.

[0117] The first region 500a of the flexible circuit board 50 is arranged corresponding to the first main body 10 and is electrically connected to the first circuit board 110, the second region 500b is arranged corresponding to the bendable portion 30, and the third region 500c is arranged corresponding to the second main body 20 and is electrically connected to the second circuit board 210. Therefore, when the foldable electronic device 1 is bent, the bendable portion 30 of the foldable electronic device 1 is bent, and the second region 500b of the flexible circuit board 50 is bent. The flexible circuit board 50 provided in the embodiment of the present application includes a plurality of stacked sub-circuit boards 510 and an adhesive layer 520 located between two adjacent layers of sub-circuit boards 510. When the flexible circuit board 50 is bent from the second region 500b, the bending radius of the sub-circuit board 510 located on the outer layer of the flexible circuit board 50 is greater than the bending radius of the sub-circuit board 510 located on the flexible circuit board 50, so the sub-circuit board 510 on the outer layer of the flexible circuit board 50 is not easy to break. Furthermore, when the flexible circuit board 50 is bent from the second area 500b, the bending radius of the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 is smaller than the bending radius of the sub-circuit board 510 located in the outer layer of the flexible circuit board 50. Since the adhesive layer 520 of the flexible circuit board 50 avoids the second area 500b, so that the two adjacent layers of sub-circuit boards 510 form a first gap 520a corresponding to the second area 500b, the first gap 520a can release the squeezing force on the sub-circuit board 510 located in the inner layer, so that the sub-circuit board 510 located in the inner layer of the flexible circuit board 50 is not easy to break, thereby improving the reliability and bending life of the flexible circuit board 50. In addition, the service life of the bendable electronic device to which the flexible circuit board 50 is applied is improved.

[0118] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application, and these improvements and modifications are also regarded as the scope of protection of the present application.

Claims

1. A flexible circuit board, characterized in that: The flexible circuit board has a first area, a second area and a third area arranged in sequence; The flexible circuit board includes a plurality of stacked sub-circuit boards and an adhesive layer located between two adjacent sub-circuit boards, the adhesive layer includes a first connecting portion and a second connecting portion, the first connecting portion is located in the first area and connects the two adjacent sub-circuit boards, the second connecting portion is located in the third area and connects the two adjacent sub-circuit boards, and the adhesive layer avoids the second area so that a first gap is formed between the two adjacent sub-circuit boards corresponding to the second area.

2. The flexible circuit board according to claim 1, characterized in that: The adhesive layer also avoids the portion of the first area adjacent to the second area, so that the two adjacent layers of sub-circuit boards form a second gap corresponding to the portion of the first area adjacent to the second area, and the second gap is connected to the first gap; The adhesive layer also avoids the portion of the third area adjacent to the second area, so that two adjacent layers of sub-circuit boards form a third gap corresponding to the portion of the third area adjacent to the second area, and the third gap is connected to the first gap.

3. The flexible circuit board according to claim 2, characterized in that: The sub-circuit board includes a conductive layer, the first connecting portion has a via hole, and the flexible circuit board also includes a conductive member, which is located in the via hole and electrically connects the conductive layers of two adjacent layers of the sub-circuit boards.

4. The flexible circuit board according to claim 3, characterized in that: The flexible circuit board includes a plurality of adhesive layers; The via holes of the first connection portion of one of the plurality of bonding layers are arranged alternately with the via holes of the first connection portion of another of the plurality of bonding layers.

5. The flexible circuit board according to claim 3, characterized in that: The conductive layer includes rolled base copper.

6. The flexible circuit board according to claim 1, characterized in that: The sub-circuit board comprises a base layer, a conductive layer, a connecting adhesive layer and a coating layer which are stacked in sequence; The thickness d1 of the base layer satisfies: 10 μm≤d1≤18 μm; The thickness d2 of the conductive layer satisfies: 5 μm≤d2≤10 μm; The thickness d3 of the connecting adhesive layer satisfies: 8 μm≤d3≤15 μm, and the thickness of the connecting adhesive layer is greater than the thickness of the conductive layer.

7. The flexible circuit board according to claim 6, characterized in that: The flexible circuit board includes a first surface and a second surface disposed opposite to each other, and the multilayer sub-circuit board includes a first sub-circuit board adjacent to the first surface and a second sub-circuit board adjacent to the second surface; The base layer of the first sub-circuit board is away from the first surface compared to the coating layer of the first sub-circuit board; The base layer of the second sub-circuit board is farther away from the second surface than the coating layer of the second sub-circuit board.

8. The flexible circuit board according to claim 7, characterized in that: Flexible circuit boards also include: An electromagnetic shielding film is arranged on a side of the first sub-circuit board facing away from the second sub-circuit board.

9. The flexible circuit board according to claim 1, characterized in that: The number of layers N of the sub-circuit boards included in the flexible circuit board satisfies: N≥3; The width W of the flexible circuit board satisfies: 10 mm ≤ W ≤ 50 mm.

10. A foldable electronic device, characterized in that: The foldable electronic device comprises: A first main body, the first main body comprising a first circuit board; a second main body portion, the second main body portion comprising a second circuit board; a bendable portion, the bendable portion being located between the first main body portion and the second main body portion; and According to any one of claims 1 to 9, the first area of ​​the flexible circuit board is arranged corresponding to the first main body and is electrically connected to the first circuit board, the second area is arranged corresponding to the bendable portion, and the third area is arranged corresponding to the second main body and is electrically connected to the second circuit board.

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