Circuit board and electronic equipment

Abstract

The embodiment of the invention provides a circuit board and electronic equipment, relates to the technical field of signal transmission, and is used for solving the problem of signal crosstalk between different channels in the circuit board. A signal layer of the circuit board can comprise a first dielectric layer, a first grounding part and a second grounding part of two adjacent signal channels. The signal channel can comprise a transmission line arranged on the first dielectric layer, and a first grounding part and a second grounding part of the transmission line are located on the same side surface of the first dielectric layer to form a coplanar waveguide. The first grounding part and the second grounding part are located between the two adjacent signal channels and are arranged at intervals. The first grounding part and the second grounding part are used for providing different backflow paths to flow backflow signals of two adjacent signal channels, so that crosstalk between different backflow signals is reduced.

Description

Technical Field

[0001] This application relates to the technical field of signal transmission, and in particular, to a circuit board and an electronic device. Background Art

[0002] With the continuous development of communication technologies, the requirements for signal transmission are getting higher and higher. Currently, circuit boards are widely used for electrically connecting electronic components. A signal transmission line is provided inside the circuit board, and the signal transmission line can transmit signals between multiple electronic components electrically connected by the circuit board. The above signal transmission line can be a microstrip line, a coplanar waveguide (CPW), or a stripline, etc. To improve the signal transmission efficiency, multiple signal transmission lines can be provided in the circuit board to achieve multi-channel signal transmission. However, signals between different channels will cause crosstalk, thereby affecting the signal transmission quality. Summary of the Invention

[0003] This application provides a circuit board and an electronic device for solving the problem of signal crosstalk between different channels in a circuit board.

[0004] To achieve the above object, this application adopts the following technical solutions:

[0005] In one aspect of this application, a circuit board is provided. The circuit board may include a signal layer. The signal layer may include a first dielectric layer, two adjacent signal channels, a first grounding portion, and a second grounding portion. Among them, the signal channel may include a transmission line, and the transmission line is disposed on the first dielectric layer. The first grounding portion is disposed on the first dielectric layer, and the first grounding portion and the transmission line are on the same side surface of the first dielectric layer. The second grounding portion is disposed on the first dielectric layer, and the second grounding portion and the transmission line are on the same side surface of the first dielectric layer. In addition, the first grounding portion and the second grounding portion are located between the two adjacent signal channels, and the first grounding portion and the second grounding portion are spaced apart.

[0006] In summary, for the circuit board provided in the embodiments of the present application, for example, the signal layer of the above flexible circuit board includes a plurality of signal channels formed on the same side of the first dielectric layer, and a first ground portion and a second ground portion located between two adjacent signal channels. Thus, the first ground portion and the second ground portion can form a coplanar waveguide with the transmission lines in the signal channels. The first ground portion and the second ground portion in the coplanar waveguide are used to provide different return paths for the return signals flowing through two adjacent signal channels. Based on this, the two adjacent signal channels can be a first signal channel and a second signal channel, and the return signal of the first signal channel and the return signal of the second signal channel can respectively flow back to the reference ground through the first ground portion and the second ground portion. Since the first ground portion and the second ground portion are spaced apart, the return signal of the first ground portion and the return signal on the second ground portion can be spaced apart, so that the return paths of the return signals of different signal channels are decoupled from each other, reducing the crosstalk between the two return signals, achieving the purpose of reducing the coupling noise and improving the signal transmission quality.

[0007] In an optional implementation manner, the circuit board further includes a reference layer, and the reference layer and the signal layer are stacked. The reference layer includes a second dielectric layer and a metal spacer layer. Wherein, the metal spacer layer is disposed on the second dielectric layer, and a second opening penetrating the metal spacer layer is formed on the metal spacer layer, and the second opening exposes the transmission line, the first ground portion, and the second ground portion. The metal spacer layer may include a transmission line for transmitting low-speed signals and a block-shaped adjacent layer reference ground. In addition, by forming the second opening on the metal spacer layer. Wherein, the first ground portion and the second ground portion in the coplanar waveguide can be equivalent to signal lines for transmitting return signals. Therefore, in order to maintain the impedance stability of the coplanar waveguide (including the transmission line, the first ground portion, and the second ground portion), it is necessary to consider not only the influence of the metal layer in the reference layer on the impedance of the transmission line, but also the influence of the metal layer in the reference layer on the impedance of the first ground portion and the second ground portion. Therefore, the second opening formed on the metal spacer layer in the reference layer needs to expose the transmission line, the first ground portion, and the second ground portion at the same time. In this way, on the one hand, the signal transmitted by the coplanar waveguide can mainly use the first ground portion and the second ground portion in the coplanar waveguide as the reference ground, so that the return signal of the coplanar waveguide mainly flows back through the first ground portion and the second ground portion, and further reduces the phenomenon that the adjacent layer reference ground (located in the metal spacer layer) is used as the reference ground for the signal transmitted by the coplanar waveguide, resulting in a decrease in the characteristic impedance of the coplanar waveguide. On the other hand, when there is no metal layer covering the upper and lower sides of the coplanar waveguide, the metal limiting member and the coplanar waveguide can be isolated through the insulating dielectric layers, such as the third dielectric layer, the fourth dielectric layer, and the second dielectric layer. In this way, when the flexible circuit board abuts against the metal limiting member during the bending process of the electronic device, the influence of the metal limiting member on the impedance stability of the coplanar waveguide in the flexible circuit board can be reduced.

[0008] In an alternative embodiment, the first ends of the first grounding portion and the second grounding portion are located on the same side and electrically connected, and the second ends of the first grounding portion and the second grounding portion are located on the same side and electrically connected. In this way, adjacent first and second grounding portions can be electrically connected to each other, so that the return signals on the first and second grounding portions can be combined and transmitted to the grounding layer.

[0009] In an alternative embodiment, the signal layer further includes a first lead and a second lead. The first lead is disposed on the first dielectric layer and is electrically connected to the transmission line, and a metal spacer layer covers the first lead. For example, one end of the first lead can be electrically connected to the transmission line, and the other end of the first lead can be electrically connected to the signal source for providing high-speed signals, so that high-speed signals can be transmitted to the transmission line in the coplanar waveguide through the first lead. The second lead is disposed on the first dielectric layer, and the mutually electrically connected first and second grounding portions can be electrically connected to the same second lead, and a metal spacer layer covers the second lead, so that the first return signal of the first signal channel and the second return signal of the second signal channel can respectively pass through the first and second grounding portions and then return to the reference ground through the second lead, thereby simplifying the structure of the circuit board.

[0010] In an alternative embodiment, the line width of the transmission line is greater than the line width of the first lead. In this way, the coplanar coupling between the transmission line and the first and second grounding portions can be improved, and the insertion loss can be reduced. For example, the line width of the transmission line can be 50μm, 100μm, 150μm, 200μm, 240μm or 250μm.

[0011] In an alternative embodiment, the line width of at least one of the first grounding portion and the second grounding portion is greater than the line width of the second lead, so as to reduce the resistance on the return signal path.

[0012] In an alternative embodiment, the first dielectric layer and the second dielectric layer are flexible dielectric layers. In this case, the above circuit board can be a flexible circuit board.

[0013] In an alternative embodiment, the signal layer further includes a third dielectric layer, which is stacked with the first dielectric layer, and the transmission line, the first grounding portion and the second grounding portion are located between the first dielectric layer and the third dielectric layer. The reference layer further includes a fourth dielectric layer, which is stacked with the second dielectric layer, and the metal spacer layer is located between the second dielectric layer and the fourth dielectric layer. The third dielectric layer and the fourth dielectric layer are flexible dielectric layers. The first dielectric layer and the third dielectric layer can prevent the transmission line, the first grounding portion and the second grounding portion from being short-circuited with the metal part in the reference layer. Similarly, the second dielectric layer and the fourth dielectric layer can prevent the metal spacer layer from being short-circuited with the metal parts in other reference layers or signal layers.

[0014] In an alternative embodiment, there is an air gap between the signal layer and the reference layer. In this way, on the one hand, the distance between the metal limiting member and the coplanar waveguide can be increased through the above air gap, and the influence of the metal limiting member on the impedance stability of the coplanar waveguide in the flexible circuit board can be reduced. On the other hand, it can also enable the flexible circuit board to provide a certain deformation space during the bending process, reducing the probability of contact between the deformed signal layer and the reference layer in the bending area, making it easier for the flexible circuit board to bend in the bending area, so as to achieve the purpose of improving the deflection of the flexible circuit board.

[0015] In an alternative embodiment, the circuit board further includes an insulating support portion located within the air gap and connected to the signal layer and the reference layer, thereby supporting the signal layer and the reference layer adjacent to the signal layer through the insulating support portion to form the above air gap.

[0016] In an alternative embodiment, the circuit board includes at least two stacked reference layers, namely a first reference layer and a second reference layer, and the signal layer is located between the first reference layer and the second reference layer. The metal spacer layer in any of the above reference layers may include signal lines for transmitting low-speed signals and an adjacent reference ground for grounding, thereby improving the diversity of signal transmission of the circuit board.

[0017] In an alternative embodiment, the signal channel includes two transmission lines, and the above signal channel can transmit differential signals.

[0018] In an alternative embodiment, the reference layer includes a second dielectric layer and a metal spacer layer. Among them, the metal spacer layer is disposed on the second dielectric layer, and a second opening penetrating the metal spacer layer is formed on the metal spacer layer, and the second opening exposes the transmission line, the first grounding portion, and the second grounding portion. The metal spacer layer in the first reference layer may be located between the third dielectric layer and the second dielectric layer, and the metal spacer layer in the first reference layer shares the third dielectric layer with the coplanar waveguide. In addition, the metal spacer layer in the second reference layer may be located between the first dielectric layer and the second dielectric layer, so that the metal spacer layer in the second reference layer shares the first dielectric layer with the coplanar waveguide. In this way, the number of dielectric layers in the circuit board can be reduced, which is beneficial to reducing the thickness of the electronic device.

[0019] On the other hand, the present application provides an electronic device, which may include a rotating shaft mechanism, any one of the circuit boards described above, and a first circuit board and a second circuit board. The circuit board may be a flexible circuit board. A part of the flexible circuit board passes through the rotating shaft mechanism. In addition, one end of the flexible circuit board is electrically connected to the first circuit board. The first circuit board and the second circuit board are respectively arranged on both sides of the rotating shaft mechanism, and the other end of the flexible circuit board is electrically connected to the second circuit board. A part of the flexible circuit board passes through the above-mentioned rotating shaft mechanism, and this flexible circuit board may be referred to as a shaft-passing flexible circuit board. The above electronic device has the same technical effects as the foregoing embodiments, and will not be elaborated here.

[0020] In an alternative embodiment, the electronic device further includes a metal limiting member. At least a part of the metal limiting member is stacked with the flexible circuit board. When the electronic device is in a flattened state, there is a gap between the metal limiting member and the flexible circuit board; when the electronic device is in a folded state, the metal limiting member abuts against the flexible circuit board. In the case where the metal limiting member abuts against the flexible circuit board, there is a first distance L1 between the surface of the metal limiting member facing the flexible circuit board and the transmission line, and L1≥100μm. In this way, during the bending process of the electronic device, when the flexible circuit board abuts against the metal limiting member, the distance between the metal limiting member and the coplanar waveguide can be far enough, so as to reduce the influence of the metal limiting member on the impedance stability of the coplanar waveguide in the flexible circuit board.

[0021] In an alternative embodiment, the electronic device includes an insulating layer, and the insulating layer is arranged on the side of the metal limiting member facing the flexible circuit board. In this way, by providing the above insulating layer, the first distance L1 between the metal limiting member and the coplanar waveguide can satisfy L1≥100μm, and further reduce the influence of the metal limiting member on the impedance stability of the coplanar waveguide in the flexible circuit board to about 1%.

[0022] In an alternative embodiment, the electronic device includes a middle frame and a rear shell. Among them, the middle frame is connected to the rotating shaft mechanism. A receiving cavity is formed between the rear shell and the middle frame. The first circuit board or the second circuit board is located in the receiving cavity, and a part of the flexible circuit board is located in the receiving cavity and is electrically connected to the first circuit board or the second circuit board. Among them, at least one of the middle frame or the rear shell is a metal limiting member. When the electronic device is in a folded state, the part of the flexible circuit board in the bending area can be deformed (for example, bent). The bent part of the flexible circuit board can abut against the rear shell so that the rear shell can limit the further deformation of the flexible circuit board. Or, in some other embodiments, the bent part of the above flexible circuit board can also abut against the middle frame so that the middle frame can limit the further deformation of the flexible circuit board.

[0023] In an alternative embodiment, the electronic device further includes a display screen, and the rotating shaft mechanism includes a rotating shaft body and a door panel. Among them, the rotating shaft body is disposed on the back surface of the display screen. The door panel is disposed on the back surface of the display screen, and the door panel is connected to the rotating shaft body and the middle frame; the flexible circuit board is located on the side of the door panel away from the display screen, and the door panel serves as a metal limiting member. When the electronic device is in the folded state, the bent portion of the flexible circuit board can abut against the door panel, so that the door panel can limit further deformation of the flexible circuit board.

[0024] In an alternative embodiment, the first grounding portion, the second grounding portion and the transmission line in the same signal channel form a coplanar waveguide. When the electronic device changes from the flattened state to the folded state, the impedance change rate △Z of the coplanar waveguide satisfies the range: -10% ≤ △Z ≤ +10%. In this way, when the flexible circuit board abuts against the metal limiting member, the influence of the metal limiting member on the impedance stability of the coplanar waveguide in the flexible circuit board can be reduced.

[0025] In an alternative embodiment, the flexible circuit board includes a reference layer and an insulating support portion. Among them, the reference layer is stacked with the signal layer, and there is an air gap between the reference layer and the signal layer, and the air gap is located in the bending area. The insulating support portion is located in the air gap, and the insulating support layer is connected to the signal layer and the reference layer, and the insulating support layer is located in the fixed area. The insulating support portion can be located in the air gap and connected to the signal layer and the reference layer, so as to support the signal layer and the reference layer adjacent to the signal layer through the insulating support portion to form the above-mentioned air gap. As described above, the flexible circuit board needs to be bent in the bending area, and the fixed area of the flexible circuit board does not need to be bent, so the above-mentioned insulating layer support portion can be disposed in the fixed area. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of an electronic device provided by an embodiment of the present application;

[0027] Figure 2 is Figure 1 an exploded structural diagram of the electronic device in

[0028] Figure 3 is Figure 1 a schematic diagram of the folded state of the electronic device in

[0029] Figure 4 is a cross-sectional view taken along the dashed line A1-A2 in Figure 3 ;

[0030] Figure 5 is another schematic structural diagram of an electronic device provided by an embodiment of the present application;

[0031] Figure 6 is Figure 4Enlarged view at B in

[0032] Figure 7 Another structural schematic diagram of the electronic device provided by the embodiment of the present application;

[0033] Figure 8A Is along Figure 7 A top view obtained in the C direction in

[0034] Figure 8B Is along Figure 7 A top view obtained in the C direction in

[0035] Figure 9 Is along Figure 8A A cross-sectional view obtained by cutting along the dotted line D1 - D2 in

[0036] Figure 10 Is along Figure 7 Another top view obtained in the C direction in

[0037] Figure 11 Is along Figure 7 Another top view obtained in the C direction in

[0038] Figure 12 A structural schematic diagram of a circuit board provided by the related art;

[0039] Figure 13A Is along Figure 7 Another top view obtained in the C direction in

[0040] Figure 13B Is along Figure 7 Another top view obtained in the C direction in

[0041] Figure 14A Is along Figure 7 Another top view obtained in the C direction in

[0042] Figure 14B Is along Figure 7 Another top view obtained in the C direction in

[0043] Figure 15 Another structural schematic diagram of the electronic device provided by the embodiment of the present application;

[0044] Figure 16 A structural schematic diagram of a signal layer provided by the embodiment of the present application;

[0045] Figure 17 A structural schematic diagram of a flexible circuit board provided by the embodiment of the present application;

[0046] Figure 18 Is along Figure 17 A top view obtained in the E direction in

[0047] Figure 19 Another top view obtained along the E direction in Figure 17 ;

[0048] Figure 20 Another sectional view obtained by cutting along the dashed line F1 - F2 in Figure 17 ;

[0049] Figure 21 A graph showing the impedance of the coplanar waveguide provided by the application embodiment changing with the change of the distance between the flexible circuit board and the coplanar waveguide;

[0050] Figure 22 Another structural schematic diagram of the electronic device provided by the application embodiment;

[0051] Figure 23 Another structural schematic diagram of the electronic device provided by the application embodiment;

[0052] Figure 24 Another structural schematic diagram of the flexible circuit board provided by the application embodiment;

[0053] Figure 25 A structural schematic diagram of the circuit board provided by the application embodiment.

[0054] Reference numerals:

[0055] 01 - Electronic device; 10 - Display screen; 20 - Rotating shaft mechanism; 30a - First middle frame; 30b - Second middle frame; 31a - First rear shell; 31b - Second rear shell; 201a - First door panel; 201b - Second door panel; 202 - Rotating shaft body; 300a - First accommodation cavity; 300b - Second accommodation cavity; 40 - Flexible circuit board; 51 - First circuit board; 52 - Second circuit board; 401 - Bending area; 402 - Fixed area; 301 - Metal limiting member; 41 - Signal layer; 411 - First dielectric layer; 421 - Transmission line; 420a - First signal channel; 420b - Second signal channel; 430 - Ground wire; 4301 - First opening; 4311 - First grounding part; 4312 - Second grounding part; 441 - First lead; 442 - Second lead; 443 - Via hole; 400 - Adjacent layer reference ground; 413 - Third dielectric layer; 61 - First reference layer; 62 - Second reference layer; 410 - Metal spacer layer; 4101 - Second opening; 412 - Second dielectric layer; 414 - Fourth dielectric layer; 70 - Insulating layer; 71 - Air gap; 72 - Insulating support part; 4001 - Coplanar waveguide. Detailed implementation manners

[0056] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments.

[0057] Hereinafter, terms such as "first" and "second" are only used for convenience of description, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0058] In the present application, unless otherwise clearly specified and defined, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed mechanical connection, a detachable mechanical connection, or integrated; or, "connection" can be a direct connection, or an indirect connection through an intermediate medium. In addition, "transmission connection" means a connection relationship that can achieve mechanical transmission, such as rotational, translational, and other movements. This "transmission connection" includes, but is not limited to, fixed mechanical connections, detachable connections (such as snap connections, threaded connections), and abutment and meshing of surface contacts.

[0059] In addition, unless otherwise clearly specified and defined, the term "electrical connection" should be understood in a broad sense. For example, "electrical connection" can be a direct electrical connection. For example, two components are physically in contact and electrically conductive, and can also be understood as electrical connection between different components in a circuit structure through an entity line such as a copper foil or a wire of a printed circuit board (PCB) that can transmit electrical signals for electrical signal transmission; or, "electrical connection" can be an indirect electrical connection between two components through an intermediate medium; or, "electrical connection" can be an electrical connection between two components in an air-spaced / non-contact manner. For example, two components are electrically connected by means of capacitive coupling for electrical signal transmission.

[0060] "Communication connection" can refer to electrical signal transmission, including wireless communication connection and wired communication connection. Wireless communication connection does not require a physical medium and does not belong to a connection relationship that limits the product structure.

[0061] In the embodiments of the present application, the descriptions of "vertical" and "parallel" respectively represent approximately vertical and approximately parallel within a certain error range. The error range can be a range with an angular deviation less than or equal to 5°, 8°, or 10° relative to absolute vertical and absolute parallel, respectively, and will not be specifically limited herein.

[0062] In the embodiments of the present application, orientation terms such as "upper", "lower", "left", and "right" may include but are not limited to those defined relative to the schematic placement of components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative description and clarification and may change accordingly with the change in the orientation of the components placed in the drawings.

[0063] In the drawings of the embodiments of the present application, components are represented by guiding lines with arrows; parts are only represented by guiding lines; openings such as openings and apertures are represented by guiding lines with wavy lines at their ends.

[0064] The embodiments of the present application provide an electronic device, which can be applied to various communication systems or communication protocols, such as: Bluetooth (BT) communication technology, Global Positioning System (GPS) communication technology, Global System of Mobile Communication (GSM) communication technology, Wireless Fidelity (WiFi) communication technology, Wideband Code Division Multiple Access Wireless (WCDMA) communication technology, Long Term Evolution (LTE), 5G communication technology, and other future communication technologies. The electronic device in the embodiments of the present application can be a mobile phone, a tablet computer (pad), a laptop computer, a smart home, a smart wearable device (such as a smart watch, a smart bracelet, smart glasses, a smart helmet), a virtual reality (VR) electronic device, an augmented reality (AR) electronic device, etc. The electronic device can also be a handheld device with wireless communication function, a computing device, or other processing devices connected to a wireless modem, a vehicle-mounted device, an electronic device in a 5G network, or an electronic device in a future evolved Public Land Mobile Network (PLMN). The embodiments of the present application are not limited thereto.

[0065] In some embodiments, the above-mentioned electronic device may have a display function. In this case, the electronic device may include a display screen and a processor electrically connected to the display screen. The processor may provide display data to the display screen to drive the display screen to display images. For example, the above-mentioned processor may include one or more processing units. For example: the processor may include an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU), etc. Among them, different processing units may be independent devices or integrated in one or more processors.

[0066] In addition, the above-mentioned electronic device 01 may further include an external memory interface, an internal memory, a universal serial bus (USB) interface, a charging management module, a power management module, a battery, an antenna, a mobile communication module, a wireless communication module, an audio module, a speaker, a receiver, a microphone, a headphone interface, a sensor module, keys, and a camera, etc. The sensor module may include a pressure sensor, a gyroscope sensor, a barometric pressure sensor, a magnetic sensor, an acceleration sensor, a distance sensor, a proximity light sensor, a fingerprint sensor, a temperature sensor, a touch sensor, an ambient light sensor, and a bone conduction sensor, etc.

[0067] For example, for the sake of convenience of description below, the electronic device 01 is taken as a folding mobile phone for illustration. In this case, the electronic device 01 may include a display screen 10 as Figure 1 shown. The display screen 10 may be a flexible screen. In some embodiments of the present application, the display screen 10 may be a self-luminous display screen, such as an organic light emitting diode (OLED) display screen, a micro (or mini) light-emitting diode display screen, or a quantum dot light emitting diode (QLED) display screen, etc. Or, in some other embodiments of the present application, the display screen 10 may also be a liquid crystal display (LCD) that requires a backlight.

[0068] In addition, during the folding or flattening process of the electronic device 01, in order to support the above-mentioned display screen 10, the electronic device 01 may further include a rotation shaft mechanism 20, two middle frames (for example, the two middle frames may be a first middle frame 30a and a second middle frame 30b respectively), and two rear cases (for example, the two rear cases may be a first rear case 31a and a second rear case 31b respectively) disposed on the back surface of the display screen 10 (the surface opposite to the display surface of the display screen 10), as shown in Figure 2 FIG. The first rear case 31a is disposed on the side of the first middle frame 30a away from the display screen 10, and the first rear case 31a is connected to the first middle frame 30a. Similarly, the second rear case 31b is disposed on the side of the second middle frame 30b away from the display screen 10, and the second rear case 31b is connected to the second middle frame 30b. The first rear case 31a and the second rear case 31b are respectively disposed on both sides of the rotation shaft mechanism 20, and any one of the first rear case 31a and the second rear case 31b may be rotatably connected or slidably connected to the rotation shaft mechanism 20.

[0069] Based on this, the display screen 10 may be connected to the rotation shaft mechanism 20, the first middle frame 30a, and the second middle frame 30b. When the electronic device 01 is in the flattened state as shown in Figure 1 FIG., the user may hold the electronic device 01 and apply an external force to the first middle frame 30a and the second middle frame 30b as shown in Figure 2 FIG. to fold the first middle frame 30a and the second middle frame 30b, so that the first middle frame 30a and the second middle frame 30b rotate or slide relative to the rotation shaft mechanism 20, thereby causing the display screen 10 to undergo a bending deformation as shown in Figure 3 FIG., and further causing the electronic device 01 to be in the folded state as shown in Figure 3 FIG.

[0070] For example, in the embodiment of the present application, the flattened state of the electronic device 01 may mean that the angle between two parts of the display screen 10 respectively connected to the first middle frame 30a and the second middle frame 30b may be equal to or approximately equal to 180°. The folded state of the electronic device 01 may mean that the angle between two parts of the display screen 10 respectively connected to the first middle frame 30a and the second middle frame 30b may be less than 180°. Hereinafter, in order to illustrate the positional relationship of each component in the electronic device 01, an XYZ coordinate system as shown in Figure 2 FIG. may be established, where the XY plane is parallel to the display surface of the display screen 10 in the flattened state of the electronic device 01, the X direction is the direction from the first middle frame 30a to the second middle frame 30b, and the Y direction is parallel to the rotation center of the rotation shaft mechanism 20. In addition, the Z direction is the stacking direction of the display screen and the middle frames (for example, the first middle frame 30a and the second middle frame 30b).

[0071] On this basis, as shown inFigure 4 (As shown by the sectional view obtained by cutting along the dashed line A1 - A2 in Figure 3 ), a receiving cavity can be formed between the first middle frame 30a and the first rear shell 31a, such as the first receiving cavity 300a. A receiving cavity can be formed between the second middle frame 30b and the second rear shell 31b, such as the second receiving cavity 300b. In addition, the above - mentioned electronic device 01 can further include a flexible printed circuit (FPC) 40, a first circuit board 51, and a second circuit board 52. Among them, the above - mentioned first circuit board 51 and second circuit board 52 can be printed circuit boards (PCBs). In order to avoid multiple circuit boards occupying too much layout space in the same receiving cavity, the first circuit board 51 and the second circuit board 52 can be respectively arranged on both sides of the rotating shaft mechanism 20, so that the first circuit board 51 is located in the first receiving cavity 300a, and the second circuit board 52 is located in the second receiving cavity 300b.

[0072] Exemplarily, the functions of the above - mentioned first circuit board 51 and second circuit board 52 can be the same or different, and the present application does not limit this. Exemplarily, at least one of the first circuit board 51 and the second circuit board 52 can be a mainboard, an interface circuit board (for example, a Type - C interface circuit board or a Type - A interface circuit board), or a circuit board for transmitting control signals.

[0073] Based on this, continuing as Figure 4 shown, in order to electrically connect the first circuit board 51 and the second circuit board 52 located in different receiving cavities by the flexible circuit board 40, a part of the flexible circuit board 40 passes through the above - mentioned rotating shaft mechanism 20, and this flexible circuit board 40 can be called a shaft - passing FPC. One end of the flexible circuit board 40 extends into the first receiving cavity 300a and is electrically connected to the first circuit board 51. The other end of the flexible circuit board 40 extends into the second receiving cavity 300b and is electrically connected to the second circuit board 52. Exemplarily, the two ends of the flexible circuit board 40 can be respectively welded to the first circuit board 51 and the second circuit board 52 by welding, so that the flexible circuit board 40 can be electrically connected to the first circuit board 51 and the second circuit board 52.

[0074] In some embodiments of the present application, as Figure 5 shown, the first circuit board 51 can be arranged on the first middle frame 30a, and this first circuit board 51 can be the mainboard of the electronic device 01. The second circuit board 52 can be arranged on the second middle frame 30b, and this second circuit board 52 can be an interface circuit board. Through the shaft - passing arrangement of the flexible circuit board 40, the first circuit board 51 and the second circuit board 52 located in different display parts can be electrically connected, so as to realize signal transmission between the above - mentioned mainboard and the interface circuit board through the flexible circuit board 40.

[0075] As can be seen from the above, continuing as Figure 5 shown, both ends of the flexible circuit board 40 are respectively connected to the first circuit board 51 and the second circuit board 52. In addition, the part of the flexible circuit board 40 passing through the above-mentioned rotating shaft mechanism 20 can also be connected to the rotating shaft mechanism 20. For example, the flexible circuit board 40 is connected to the rotating shaft mechanism 20 by means of adhesion. Therefore, the parts of the flexible circuit board 40 respectively connected to the first circuit board 51, the second circuit board 52, and the rotating shaft mechanism 20 will not deform during the bending process of the electronic device 01. The parts of the flexible circuit board 40 other than those connected to the above components (the first circuit board 51, the second circuit board 52, and the rotating shaft mechanism 20) can deform during the bending process of the electronic device 01.

[0076] In this case, the flexible circuit board 40 can include a bending area 401 and a fixed area 402. Among them, the parts of the flexible circuit board 40 respectively connected to the first circuit board 51, the second circuit board 52, and the rotating shaft mechanism 20 (as Figure 4 shown) are located in the fixed area 402. Therefore, the parts of the flexible circuit board 40 located in the fixed area 402 will not or will hardly deform during the bending process of the electronic device 01. In addition, the parts of the flexible circuit board 40 other than those located in the fixed area 402 can be the above-mentioned bending area 401. Therefore, the parts of the flexible circuit board 40 located in the bending area 401 can deform during the bending process of the electronic device 01.

[0077] The above takes the parts of the flexible circuit board 40 respectively connected to the first circuit board 51, the second circuit board 52, and the rotating shaft mechanism 20 (as Figure 4 shown) as an example to illustrate the setting of the bending area 401 and the fixed area 402 of the flexible circuit board 40. In some other embodiments of the present application, the flexible circuit board 40 can be connected to the first circuit board 51 and the second circuit board 52, and there may be no connection relationship between the flexible circuit board 40 and the rotating shaft mechanism 20. In this case, the part of the flexible circuit board 40 passing through the rotating shaft mechanism 20 can be located in the above-mentioned bending area 401. For the convenience of description below, all examples are given taking the parts of the flexible circuit board 40 respectively connected to the first circuit board 51, the second circuit board 52, and the rotating shaft mechanism 20 (as Figure 4 shown) as an example.

[0078] Based on this, when the electronic device is in the folded state, the part of the flexible circuit board 40 in the bending area 401 can undergo the same as Figure 4The deformation (for example, bending) shown. The bent portion of the flexible circuit board 40 may abut against the rear shell (for example, the first rear shell 31a and the second rear shell 31b) so that the rear shell can limit the further deformation of the flexible circuit board 40. Alternatively, in other embodiments, the bent portion of the flexible circuit board 40 may also abut against the middle frame (for example, the first middle frame 30a and the second middle frame 30b) so that the middle frame can limit the further deformation of the flexible circuit board 40. Alternatively, the bent portion of the flexible circuit board 40 may abut against both the rear shell and the middle frame. For example, the rear shell and the middle frame may be made of metal material. Therefore, at least one of the rear shell (for example, the first rear shell 31a and the second rear shell 31b) and the middle frame (for example, the first middle frame 30a and the second middle frame 30b) may be referred to as Figure 6 ( Figure 4 The metal stopper 301 is shown in the enlarged view of point B in FIG.

[0079] Or, continue as Figure 4 As shown, the hinge mechanism 20 may include a hinge body 202 and two door panels (for example, the two door panels are a first door panel 201a and a second door panel 201b), and the door panels may be disposed on the display screen 10 (for example, Figure 2 The flexible circuit board 40 may be located on the back of the door panel (eg, the first door panel 201a and the second door panel 201b) away from the display screen 10 (eg, Figure 2 The first door panel 201a and the second door panel 201b may be respectively arranged on both sides of the hinge body 202, and any one of the first door panel 201a and the second door panel 201b may be connected to the hinge body 202. Moreover, the first door panel 201a may be connected to the first middle frame 30a, and the second door panel 201b may be connected to the second middle frame 30b. The door panel and the hinge body 202 and any one of the middle frames may be rotatably connected, slidably connected or fixedly connected, so that when the electronic device 01 is bent, the display bending portion 103 of the display screen 10 may be bent as shown. Figure 3 The bending deformation shown in FIG. Figure 3 Shown in folded state.

[0080] Based on this, continue as Figure 4 As shown, when the electronic device is in a folded state, the bent portion of the flexible circuit board 40 can abut against the door panel (for example, the first door panel 201a and the second door panel 201b), so that the door panel can limit the further deformation of the flexible circuit board 40. For example, the above-mentioned door panel can be made of metal material. Therefore, the door panel (for example, the first door panel 201a and the second door panel 201b) can be called Figure 6 The metal stopper 301 is shown.

[0081] In this case, as Figure 6 shown, at least a part of the above-mentioned metal limiting member 301 can be stacked with the flexible circuit board 40. In this way, when the electronic device is in a folded state, the metal limiting member 301 can abut against the flexible circuit board 40 to limit further deformation of the flexible circuit board 40 through the metal limiting member 301. In addition, when the electronic device 01 is in Figure 7 the flattened state shown, there can be a gap between the metal limiting member 301 and the flexible circuit board 40, such as gap h1 or gap h2. Among them, the above-mentioned gap h1 or gap h2 can represent the gap between the flexible circuit board 40 and different metal limiting members 301, and the gap h1 or gap h2 provides a certain space for bending deformation for the flexible circuit board 40.

[0082] Based on this, the circuit board provided by the embodiment of the present application can be the above-mentioned flexible circuit board 40. The following will give a detailed example of the structure of the flexible circuit board 40. In some embodiments of the present application, the flexible circuit board 40 may include as Figure 8A (top view obtained along Figure 7 the C direction in Figure 8A shown) the signal layer 41. The signal layer 41 may include a first dielectric layer 411, two adjacent signal channels (for example, the two signal channels may be the first signal channel 420a and the second signal channel 420b respectively), and a first grounding portion 4311 and a second grounding portion 4312. Among them, the first grounding portion 4311 and the second grounding portion 4312 are located between two adjacent signal channels (for example, the first signal channel 420a and the second signal channel 420b). And, the first grounding portion 4311 and the second grounding portion 4312 are arranged at intervals. Any one of the above-mentioned first signal channel 420a and second signal channel 420b may include a transmission line 421. The present application does not limit the number of signal channels,

[0083] In some embodiments of the present application, as Figure 8A shown, the first grounding portion 4311 and the second grounding portion 4312 between two adjacent signal channels (for example, the first signal channel 420a and the second signal channel 420b) can be independently arranged, and the above-mentioned first grounding portion 4311 and second grounding portion 4312 can be grounded respectively.

[0084] Alternatively, in some other embodiments of the present application, the first end a1 of the first grounding portion 4311 and the first end b1 of the second grounding portion 4312 located on the same side can be electrically connected, and the second end a2 of the first grounding portion 4311 and the second end b2 of the second grounding portion 4312 located on the same side can be located on the same side and electrically connected, so that the first grounding portion 4311 and the second grounding portion 4312 electrically connected to each other form a Figure 8B A ground line 430 is shown.

[0085] For example, in the process of manufacturing the ground line 430, a metal film pattern layer can be formed on the first dielectric layer 411, and then a mask is formed on the metal film layer by a photolithography (mask) process. Figure 8B The first opening 4301 is formed so that the metal film pattern layer is separated into a first grounding portion 4311 and a second grounding portion 4312 through the first opening 4301. Alternatively, for example, a first grounding portion 4311 and a second grounding portion 4312 that are independent and spaced apart can be formed on the first dielectric layer 411. Then, a metal layer for connecting the first grounding portion 4311 and the second grounding portion 4312 is formed at the ends of the first grounding portion 4311 and the second grounding portion 4312, so that Figure 8B The present application does not limit the manufacturing process of the first grounding portion 4311 and the second grounding portion 4312. For the convenience of description, the following is based on Figure 8B The description is made by taking an example where two adjacent first grounding portions 4311 and second grounding portions 4312 are electrically connected to form a grounding line 430 .

[0086] In addition, if Figure 9 (along Figure 8A As shown in the cross-sectional view obtained by cutting along the line D1-D2 in FIG. 4 , the transmission line 421 and the ground line 430 can be arranged on the first dielectric layer 411, and the transmission line 421 and the ground line 430 can be located on the same side surface of the first dielectric layer 411. In this way, the transmission line 421 can form a coplanar waveguide with the ground line 430 adjacent to the transmission line 421. The coplanar waveguide has the advantages of high transmission speed, long transmission distance, and strong anti-interference ability.

[0087] Therefore, in some embodiments of the present application, the transmission line 421 can be used to transmit high-speed signals. For example, the transmission distance of the high-speed signal can be greater than 1 / 6λ. Wherein, λ is the wavelength of the high-speed signal. The high-speed signal can be a high-speed digital signal or a radio frequency signal. In some embodiments of the present application, the high-speed digital signal can include a differential signal. In this case, Figure 10 (along Figure 7As shown in the top view obtained in C), within the same signal channel, for example, the first signal channel 420a (or the second signal channel 420b), there can be two transmission lines 421. Exemplarily, the above-mentioned high-speed digital signal can be data for storage or reading, interface data, or screen control data.

[0088] Exemplarily, the above-mentioned first dielectric layer 411 can be made of a substrate prepared from a polymer material. A metal layer, such as a copper layer, is formed on the first dielectric layer 411, and then a part of the copper layer is retained through lithography, printing, and other patterning processes to form the above-mentioned transmission line 421 and ground wire 430, and the other part is removed.

[0089] Based on this, as can be seen from the above, as Figure 8B or Figure 10 shown, the first ground portion 4311 and the second ground portion 4312 between two adjacent signal channels (for example, the first signal channel 420a and the second signal channel 420b) are arranged at intervals. Therefore, the return signal of the high-speed signal transmitted on the first signal channel 420a can return to the reference ground after passing through the first ground portion 4311. And the return signal of the high-speed signal transmitted on the second signal channel 420b can return to the reference ground through the second ground portion 4312, and the above two return signals can be isolated through the gap between the first ground portion 4311 and the second ground portion 4312, such as the above-mentioned first opening 4301.

[0090] The return paths of the return signals of different signal channels on the first ground portion 4311 and the second ground portion 4312 are illustrated by way of example below. Exemplarily, as Figure 11 shown, there is a first ground portion 4311 between the first signal channel 420a and the first opening 4301. There is a second ground portion 4312 between the second signal channel 420b and the first opening 4301. In this case, the first return signal (represented by a solid arrow in the figure) of the high-speed signal transmitted on the first signal channel 420a can return to the reference ground from right to left (i.e., from the first end a1 to the second end a2) through the first ground portion 4311. In addition, the second return signal (represented by a dashed arrow in the figure) of the high-speed signal transmitted on the second signal channel 420b can return to the reference ground from left to right (i.e., from the second end b2 to the first end b1) through the second ground portion 4312.

[0091] Among them, Figure 11Taking as an example that the transmission directions of the return signals of the first signal channel 420a and the second signal channel 420b on the first grounding portion 4311 and the second grounding portion 4312 are opposite respectively. In some other embodiments of the present application, the transmission directions of the return signals of the first signal channel 420a and the second signal channel 420b on the first grounding portion 4311 and the second grounding portion 4312 may also be the same.

[0092] In summary, the circuit board provided by the embodiments of the present application, such as the flexible circuit board 40 (as Figure 4 shown), the signal layer 41 as Figure 11 shown includes a plurality of signal channels formed on the same side of the first dielectric layer 411 and the first grounding portion 4311 and the second grounding portion 4312 located between two adjacent signal channels (such as the first signal channel 420a and the second signal channel 420b). The first grounding portion 4311 and the second grounding portion 4312 can form a coplanar waveguide with the transmission line 421 in the signal channel, and the above coplanar waveguide can be used to transmit high-speed signals, such as high-speed digital signals or radio frequency signals. For the above high-speed signals, the high-speed signals need to return through the first grounding portion 4311 or the second grounding portion 4312 in the coplanar waveguide.

[0093] Based on this, the first return signal of the first signal channel 420a ( Figure 11 represented by a solid arrow in Figure 11 ) and the second return signal of the second signal channel 420b ( Figure 11 represented by a dotted arrow in Figure 11 ) can return to the reference ground through the first grounding portion 4311 and the second grounding portion 4312 respectively. The first grounding portion 4311 serves as the return path of the first return signal, and the second grounding portion 4312 serves as the return path of the second return signal. Since the first grounding portion 4311 and the second grounding portion 4312 are arranged at intervals, the first return signal on the first grounding portion 4311 and the second return signal on the second grounding portion 4312 can be spaced apart, so that the return paths of the return signals from different signal channels are decoupled from each other, reducing the crosstalk between the above two return signals, and achieving the purpose of reducing the coupling noise and improving the signal transmission quality.

[0094] On this basis, as Figure 11 shown, when the directions of the first return signal on the first grounding portion 4311 and the second return signal on the second grounding portion 4312 are opposite, the mutual cancellation effect between the first return signal and the second return signal can be reduced, and the signal transmission efficiency can be improved. In comparison, the circuit board with a coplanar waveguide provided by the related art, such as Figure 12As shown, the return signal directions of adjacent transmission signal lines S1 and S2 are opposite and flow into the same ground wire GND. The return signals of the above two transmission signal lines are not isolated in the ground wire GND, resulting in mutual cancellation and thus generating coupling noise.

[0095] On this basis, in order to transmit the above high-speed signal from the signal source to Figure 11 the transmission line 421 shown, and return the return signal of the high-speed signal to the reference ground through the first grounding portion 4311 or the second grounding portion 4312, the signal layer 41 may further include a first lead 441 and a second lead 442. Among them, the first lead 441 may be disposed on the first dielectric layer 411. One end of the first lead 441 may be electrically connected to the transmission line 421, and the other end of the first lead 441 may be electrically connected to the signal source for providing the high-speed signal, so that the high-speed signal can be transmitted to the transmission line 421 in the coplanar waveguide through the first lead 441.

[0096] In addition, the second lead 442 is disposed on the first dielectric layer 411. The mutually electrically connected first grounding portion 4311 and the second grounding portion 4312 may be electrically connected to the same second lead 442, so that the first return signal of the first signal channel 420a ( Figure 11 represented by a solid arrow in) and the second return signal of the second signal channel 420b ( Figure 11 represented by a dashed arrow in) can respectively pass through the first grounding portion 4311 and the second grounding portion 4312 and then return to the reference ground through the same second lead 442, which can simplify the structure of the flexible circuit board.

[0097] In some embodiments of the present application, in order to enable the return signals on the first grounding portion 4311 and the second grounding portion 4312 to return to the reference ground through the second lead 442, as Figure 13A shown, the flexible circuit board 40 further includes an adjacent layer reference ground 400 stacked with the signal layer 41. The flexible circuit board 40 may further include a via 443, which may penetrate the first dielectric layer 411, so that the second lead 442 is electrically connected to the adjacent layer reference ground 400 through the via 443, so that the adjacent layer reference ground 400 serves as the reference ground of the second lead 442. Exemplarily, the adjacent layer reference ground 400 may be a block-shaped metal layer structure (for example, a block-shaped metal copper leakage area).

[0098] Figure 13A The example is given by taking the adjacent first grounding portion 4311 and the second grounding portion 4312 being mutually electrically connected and then being electrically connected to the adjacent layer reference ground 400 through the same second lead 442 and the same via 443. In some other embodiments of the present application, asFigure 13B As shown, when the first grounding portion 4311 and the second grounding portion 4312 are independently arranged, the first grounding portion 4311 and the second grounding portion 4312 can be respectively electrically connected to the adjacent-layer reference ground 400 through different vias 443.

[0099] In addition, in some embodiments of the present application, as Figure 11 shown, the line width of the transmission line 421 constituting the coplanar waveguide (the dimension along the Y direction, that is, perpendicular to the extension direction of the signal line) can be greater than the line width of the first lead 441. For example, the line width of the transmission line 421 can be between 50 - 250 μm. In this way, the coplanar coupling between the transmission line 421 and the ground line 430 can be improved, and the insertion loss can be reduced. For example, the line width of the transmission line 421 can be 50 μm, 100 μm, 150 μm, 200 μm, 240 μm or 250 μm.

[0100] In addition, since Figure 13A the adjacent-layer reference ground 400 shown can be a block-shaped metal layer structure, the adjacent-layer reference ground 400 has low-resistance characteristics. Therefore, the line width (the dimension along the Y direction) of the second lead 442 used to electrically connect the first grounding portion 4311 and the second grounding portion 4312 to the adjacent-layer reference ground 400 can be smaller than the line width (the dimension along the Y direction) of the ground line 430, so as to reduce the resistance on the return signal path.

[0101] On this basis, continuing as Figure 13A shown, when the distance between the ground line 430 and the adjacent transmission line 421 is far, it is not easy to generate coplanar coupling between the transmission line 421 and the ground line 430. And when the distance between the ground line 430 and the adjacent transmission line 421 is close, due to the conductivity of the ground line 430, the ground line 430 will pull down the impedance of the transmission line 421, resulting in unstable impedance of the transmission line 421. Based on this, the distance H1 between the above-mentioned ground line 430 and the adjacent transmission line 421 can be in the range of 20 μm to 100 μm. In this way, coplanar coupling can be achieved between the transmission line 421 and the ground line 430, and the impedance of the transmission line 421 can be stabilized. For example, the distance H1 between the ground line 430 and the adjacent transmission line 421 can be 20 μm to 100 μm. For example, H1 can be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm and 100 μm.

[0102] As can be seen from the above, the flexible circuit board 40 has a bending area 401 and a fixing area 402 as Figure 5 shown, wherein, in the flexible circuit board 40, the parts respectively connected to the first circuit board 51, the second circuit board 52 and the rotating shaft mechanism 20 (as Figure 4The portion connected to the flexible circuit board 40 is located in the fixing area 402. The portion of the flexible circuit board 40 other than the fixing area 402 is the bending area 401. Therefore, the bending area 401 occupies most of the area of ​​the flexible circuit board 40. Based on this, Figure 14A As shown, the transmission line 421 and the ground line 430 used to form the coplanar waveguide can be located in the bending area 401, so that the flexible circuit board 40 can transmit high-speed data. In addition, the first lead 441 and the second lead 442 can be arranged in the fixing area 402.

[0103] in, Figure 14A The flexible circuit board 40 is respectively Figure 4 The first circuit board 51, the second circuit board 52 and the rotating shaft mechanism 20 are connected as an example. In other embodiments of the present application, the flexible circuit board 40 is connected to the first circuit board 51 and the second circuit board 52, and the flexible circuit board 40 and the rotating shaft mechanism 20 may not be connected. In this case, Figure 14B As shown, the two ends of the flexible circuit board can be located in the above-mentioned fixing area 402, so that the two ends of the flexible circuit board are respectively connected to Figure 4 The first circuit board 51 and the second circuit board 52 are connected, and the portion of the flexible circuit board between the two fixed areas 402 is the bending area 401. For the convenience of description, the following is the arrangement of the bending area 401 and the fixed area 402 of the signal layer 41 in the flexible circuit board as shown in FIG. Figure 14A As shown in the figure, the coplanar waveguide formed by the transmission line 421 and the ground line 430 in the signal layer 41 is used to transmit high-speed signals, such as high-speed digital signals or radio frequency signals. In some embodiments of the present application, in the signal layer 41 of the same flexible circuit board, different transmission channels, for example, Figure 10 The first signal channel 420a and the second signal channel 420b in the embodiment can transmit the high-speed digital signal and the radio frequency signal respectively.

[0104] Or, in other embodiments of the present application, Figure 15 As shown, the electronic device 01 may include two flexible circuit boards, namely, a flexible circuit board 40a and a flexible circuit board 40b, and both ends of any one of the flexible circuit boards 40a and 40b are electrically connected to the first circuit board 51 and the second circuit board 52. Among them, the coplanar waveguide formed by the transmission line 421 and the ground line 430 in the flexible circuit board 40a can transmit high-speed digital signals, and the coplanar waveguide formed by the transmission line 421 and the ground line 430 in the flexible circuit board 40b can transmit radio frequency signals. The above is an example of the number of flexible circuit boards in the electronic device 01 and the transmitted signals, and does not constitute a limitation on the number of flexible circuit boards and the transmitted signals.

[0105] The above takes Figure 14A the signal layer 41 shown in the figure as an example, where the signal layer 41 includes a dielectric layer, such as the first dielectric layer 411. In some other embodiments of the present application, as Figure 16 shown, the signal layer 41 may further include a third dielectric layer 413. The third dielectric layer 413 may be stacked with the first dielectric layer 411, and the transmission line 421 and the ground line 430 are located between the first dielectric layer 411 and the third dielectric layer 413. For example, the transmission line 421 and the ground line 430 may be fabricated on the first dielectric layer 411. Or, as another example, the transmission line 421 and the ground line 430 may be fabricated on the surface of the third dielectric layer 413 facing the first dielectric layer 411. Wherein, the materials of the third dielectric layer 413 and the first dielectric layer 411 may be the same, and the third dielectric layer 413 and the first dielectric layer 411 may both be flexible dielectric layers.

[0106] On this basis, any flexible circuit board in the above electronic device 01 can transmit not only the above high-speed signals, but also non-high-speed signals such as low-speed signals or ground signals. Based on this, in order to enable the flexible circuit board to transmit the above non-high-speed signals, in some embodiments of the present application, the flexible circuit board may further include at least one reference layer. For example, as Figure 17 shown, the flexible circuit board 40 may be provided with two reference layers, namely the first reference layer 61 and the second reference layer 62.

[0107] Wherein, the first reference layer 61 and the second reference layer 62 may be stacked with the signal layer 41, and the signal layer 41 may be located between the first reference layer 61 and the second reference layer 62. In some embodiments of the present application, any one of the first reference layer 61 and the second reference layer 62 may include a second dielectric layer 412, a metal spacer layer 410, and a fourth dielectric layer 414, and the metal spacer layer 410 is stacked between the second dielectric layer 412 and the fourth dielectric layer 414. The second dielectric layer 412 may be located on the side of the fourth dielectric layer 414 facing away from the signal layer 41. For example, the metal spacer layer 410 may be provided on the second dielectric layer 412. Or, the metal spacer layer 410 may be provided on the fourth dielectric layer 414, and the present application does not limit this.

[0108] The second dielectric layer 412 and the fourth dielectric layer 414 can be flexible dielectric layers. For example, the materials of the second dielectric layer 412 and the fourth dielectric layer 414 can be the same as those of the first dielectric layer 411. The metal spacer layer 410 can include signal lines for transmitting the non-high-speed signals and a bulk reference ground (hereinafter referred to as the adjacent-layer reference ground). In this way, in the first reference layer 61 and the second reference layer 62, the metal spacer layer 410 in any one of the reference layers can include signal lines for transmitting low-speed signals and the adjacent-layer reference ground for grounding, thereby improving the diversity of signal transmission of the flexible circuit board 40. Among them, the first dielectric layer 411 and the third dielectric layer 413 can prevent the transmission line 421, the first grounding portion 4311, and the second grounding portion 4212 from being short-circuited with the metal parts in the reference layers (for example, the first reference layer 61 and the second reference layer 62). Similarly, the second dielectric layer 412 and the fourth dielectric layer 414 can prevent the metal spacer layer 410 from being short-circuited with the metal parts in other reference layers or the signal layer 41.

[0109] As can be seen from the above, as Figure 18 (in the top view obtained along Figure 17 the E direction in Figure 17 ), a second opening 4101 penetrating through the metal spacer layer 410 can be formed on the metal spacer layer 410, and the second opening 4101 is used to expose Figure 18 the transmission line 421 and the ground wire 430 in the signal layer 41 shown in

[0110] . Since the transmission line 421 and the ground wire 430 are arranged in the bending area 401, therefore, continuing Figure 19 (in the top view obtained along Figure 17 the E direction in

[0111] ), the second opening 4101 on the metal spacer layer 410 is located in the bending area 401, and the part of the metal spacer layer 410 where the second opening 4101 is not formed can be located in the fixing area 402. Figure 11As shown in FIG. 4 , the grounding line 430 is no longer a block-shaped metal reference ground, but is equivalent to a signal line for transmitting a return signal. Therefore, in order to maintain the stability of the impedance of the coplanar waveguide 4001, it is necessary not only to consider the influence of the metal layer in the reference layer (such as the first reference layer 61 or the second reference layer 62) on the impedance of the transmission line 421, but also to consider the influence of the metal layer in the reference layer on the impedance of the grounding line 430. Therefore, in any one of the first reference layer 61 and the second reference layer 62, the second opening 4101 opened on the metal spacer layer 410 needs to expose the transmission line 421 and the grounding line 430 at the same time.

[0112] In this case, if Figure 20 (along Figure 17 As shown in the cross-sectional view obtained by cutting along the dotted line F1-F2 in FIG. 1 , the coplanar waveguide 4001 (including Figure 17 There is no metal layer covering the transmission line 421 and the ground line 430 shown above and below. In this way, on the one hand, the signal transmitted by the coplanar waveguide 4001 can be mainly referenced to the ground line 430 in the coplanar waveguide 4001, so that the return signal of the coplanar waveguide 4001 mainly flows back through the ground line 430, thereby reducing the adjacent layer reference ground (located in the metal spacing layer 410) as the reference ground of the transmission signal of the coplanar waveguide 4001, resulting in the phenomenon of reducing the characteristic impedance of the coplanar waveguide 4001.

[0113] On the other hand, by Figure 4 It can be seen that during the bending process of the electronic device 01, at least one of the first door panel 201a, the second door panel 201b, the first rear shell 31a and the second rear shell 31b, the first middle frame 30a or the second middle frame 30b can serve as a metal stopper 301 to abut against the flexible circuit board 40. In this case, since the metal stopper 301 is a conductor, when the metal stopper 301 abuts against the flexible circuit board 40, the coplanar waveguide 4001 (such as Figure 20 The impedance of the coplanar waveguide 4001 is pulled down, resulting in a sudden change in the impedance of the coplanar waveguide 4001, thereby reducing the impedance stability of the coplanar waveguide.

[0114] For example, Figure 21 As shown, the horizontal axis is the extension direction of the flexible circuit board (for example Figure 20 The four curves in the figure represent four different distances between the flexible circuit board and the coplanar waveguide when the metal stopper is in contact with the flexible circuit board. Among all the curves, the distance between the flexible circuit board and the coplanar waveguide represented by curve ① is the largest. For example, when the flexible circuit board is in contact with the coplanar waveguide at positions G1 and G2 respectively, Figure 4When the first rear case 31a and the second rear case 31b in [[]] abut against each other, at position G1, the impedance of the coplanar waveguide is A1, and at position G2, the impedance of the coplanar waveguide is B1.

[0115] In addition, among all the curves, curve ④ represents the smallest distance between the flexible circuit board and the coplanar waveguide. For example, when the flexible circuit board abuts against the Figure 4 first rear case 31a and the second rear case 31b in [[]] at positions G1 and G2 respectively, at position G1, the impedance of the coplanar waveguide will instantaneously decrease from point A1 on curve ① to point A2 on curve ②, and at position G2, the impedance of the coplanar waveguide will instantaneously decrease from point B1 on curve ① to point B2 on curve ②.

[0116] In addition, curves ③ and ④ represent the distance between the flexible circuit board and the coplanar waveguide in the case where the metal limiting member abuts against the flexible circuit board, which is between curves ① and ②. Based on this, when there is no metal layer covering above and below the coplanar waveguide 4001 (including Figure 17 the transmission line 421 and the ground wire 430 shown in [[]]), as Figure 22 shown, it is possible to isolate the above-mentioned metal limiting member 301 from the coplanar waveguide 4001 through the above-mentioned insulating dielectric layer, such as the third dielectric layer 413, the fourth dielectric layer 414, and the second dielectric layer 412. In this way, during the bending process of the electronic device 01, when the flexible circuit board 40 abuts against the metal limiting member 301, the distance between the flexible circuit board and the coplanar waveguide can be increased, so that at position G1, the impedance of the coplanar waveguide is between point A1 and point A2, and at position G2, the impedance of the coplanar waveguide is between point B1 and point B2. In this way, it is possible to avoid a large instantaneous change in the impedance of the flexible circuit board, so as to reduce the influence of the metal limiting member 301 on the impedance stability of the coplanar waveguide in the flexible circuit board 40.

[0117] On this basis, in order to stabilize the impedance of the coplanar waveguide, in some embodiments of the present application, continuing as Figure 22 shown, when the metal limiting member 301 abuts against the flexible circuit board 40, there is a first distance L1 between the surface of the metal limiting member 301 facing the flexible circuit board 40 and the coplanar waveguide 4001 (including Figure 17 the transmission line 421 and the ground wire 430 shown in [[]]), and L1≥100μm. In this way, during the bending process of the electronic device 01, when the flexible circuit board 40 abuts against the metal limiting member 301, the distance between the metal limiting member 301 and the coplanar waveguide 4001 can be far enough, so as to reduce the influence of the metal limiting member 301 on the impedance stability of the coplanar waveguide in the flexible circuit board 40.

[0118] For example, continuing as Figure 21 shown, curve ③ represents theFigure 22 When the flexible circuit board 40 shown abuts against the metal limiting member 301, the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 is greater than that represented by curve ④ Figure 22 When the flexible circuit board 40 shown abuts against the metal limiting member 301, the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001. Therefore, it can be seen that when the flexible circuit board 40 abuts against the metal limiting member 301, the larger the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001, the smaller the reduction amplitude of the impedance of the coplanar waveguide and the stronger the impedance stability.

[0119] For example, when the flexible circuit board 40 abuts against the metal limiting member 301 and the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 satisfies L1≥100μm, when the electronic device 01 changes from a flattened state to a folded state, the range that the impedance change rate △Z of the coplanar waveguide 4001 satisfies can be: -10%≤△Z≤+10%. In this way, when the flexible circuit board 40 abuts against the metal limiting member 301, the influence of the metal limiting member 301 on the impedance stability of the coplanar waveguide in the flexible circuit board 40 can be reduced.

[0120] In some other embodiments of the present application, in order to make the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 satisfy L1≥100μm when the flexible circuit board 40 abuts against the metal limiting member 301, as Figure 23 shown, the above-mentioned electronic device may further include an insulating layer 70, and the insulating layer 70 may be disposed on the side of the metal limiting member 301 facing the flexible circuit board 40. For example, a layer of non-conductive material, such as a polymer material like Teflon, can be prepared on the surface of the metal limiting member 301 facing the flexible circuit board 40 by pasting or spraying, so as to reduce the influence of the metal limiting member 301 on the impedance stability of the coplanar waveguide in the flexible circuit board 40 to about 1%.

[0121] The above takes the case where the metal limiting member 301 is disposed above the flexible circuit board 40 as an example to illustrate the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001. In some other embodiments of the present application, the metal limiting member 301 may also be disposed below the flexible circuit board 40. In this case, the setting method of the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 is the same as that described above, and will not be elaborated here.

[0122] In some other embodiments of the present application, when the flexible circuit board 40 abuts against the metal limiting member 301, on the basis that the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 satisfies L1≥100μm, in order to improve the deflection characteristics of the entire flexible circuit board 40, so that the flexible circuit board 40 can meet tens of thousands of times, for example, more than 50,000 times of dynamic bending, as Figure 20 shown, an air gap 71 can be provided between the signal layer 41 and any one of the first reference layer 61 and the second reference layer 62.

[0123] In this way, on the one hand, through the above-mentioned air gap 71, the first distance L1 between the metal limiting member 301 and the coplanar waveguide 4001 can be increased, which is beneficial to making the first distance L1 satisfy L1≥100μm. On the other hand, it can also enable the flexible circuit board 40 to provide a certain deformation space during the bending process, reducing the probability of contact between the deformed signal layer 41 and any one of the first reference layer 61 and the second reference layer 62 in the bending region 401, making it easier for the flexible circuit board 40 to bend in the bending area 401, so as to achieve the purpose of improving the deflection of the flexible circuit board.

[0124] On this basis, in order to form the above-mentioned air gap 71 between the signal layer 41 and any one of the first reference layer 61 and the second reference layer 62, continue as Figure 20 shown, the flexible circuit board further includes an insulating support portion 72. The insulating support portion 72 can be located within the air gap 71 and is connected to the signal layer 41 and the reference layer (the first reference layer 61 or the second reference layer 62), so as to support the signal layer 41 and the reference layer adjacent to the signal layer 41 through the insulating support portion 72 to form the above-mentioned air gap 71. As can be seen from the above, the flexible circuit board 40 needs to be bent in the bending area 401, while the fixed area 402 of the flexible circuit board 40 does not need to be bent. Therefore, the above-mentioned insulating layer support portion 70 can be arranged in the fixed area 402.

[0125] The above is an example illustration taking the flexible circuit board 40 including two reference layers, such as the first reference layer 61 and the second reference layer 62. In some other embodiments of the present application, as Figure 24 shown, the flexible circuit board 40 can include at least three reference layers. For example, at least two first reference layers 61 are arranged above the signal layer 41, and at least two second reference layers 62 are arranged below the signal layer 41. In the flexible circuit board 40, an air gap 71 can be provided between any two adjacent reference layers, and the setting method and technical effect of the air gap 71 are the same as those described above, and will not be elaborated here.

[0126] Alternatively, in some other embodiments of the present application, the flexible circuit board 40 may further have a reference layer stacked with the signal layer 41, and the reference layer may be disposed above or below the flexible circuit board 40. The above is an example of the number of reference layers in the flexible circuit board 40, and does not constitute a limitation on the number of reference layers.

[0127] The above example is given taking the circuit board provided in the embodiment of the present application as the flexible circuit board 40. In some other embodiments of the present application, the above circuit board may also be a PCB. In this case, the PCB may include the above signal layer 41, and the arrangement manner and technical effects of the transmission line 421 and the ground layer 430 in the signal layer 41 are the same as those described above, and will not be repeated here. In addition, the PCB may further include a reference layer stacked with the signal layer 41, and the arrangement manner of the reference layer is the same as that described above, and will not be repeated here.

[0128] Alternatively, in some other embodiments of the present application, as Figure 25 shown, any one of the reference layers in the PGB, for example, any one of the first reference layer 61 or the second reference layer 62 may have only one dielectric layer, that is, the second dielectric layer 412. In this case, the metal spacer layer 410 in the first reference layer 61 may be located between the third dielectric layer 413 and the second dielectric layer 412, so that the metal spacer layer 410 in the first reference layer 61 shares the third dielectric layer 413 with the coplanar waveguide 4001. In addition, the metal spacer layer 410 in the second reference layer 62 may be located between the first dielectric layer 411 and the second dielectric layer 412, so that the metal spacer layer 410 in the second reference layer 62 shares the first dielectric layer 411 with the coplanar waveguide 4001. In this way, the number of dielectric layers in the PCB can be reduced, which is beneficial to reducing the thickness of the electronic device 01.

[0129] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any change or replacement within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A circuit board, characterized in that, it includes a signal layer, and the signal layer includes: a first dielectric layer; two adjacent signal channels, the signal channels include transmission lines, and the transmission lines are disposed on the first dielectric layer; a first grounding portion disposed on the first dielectric layer, and the first grounding portion and the transmission line are on the same side surface of the first dielectric layer; a second grounding portion disposed on the first dielectric layer, and the second grounding portion and the transmission line are on the same side surface of the first dielectric layer; the first grounding portion and the second grounding portion are located between the two adjacent signal channels, and the first grounding portion and the second grounding portion are spaced apart.

2. The circuit board according to claim 1, characterized in that, the circuit board further includes a reference layer, the reference layer is stacked with the signal layer, and the reference layer includes: a second dielectric layer; a metal spacer layer disposed on the second dielectric layer, and a second opening penetrating the metal spacer layer is formed on the metal spacer layer; the second opening exposes the transmission line, the first grounding portion and the second grounding portion.

3. The circuit board according to claim 1 or 2, characterized in that, the first ends of the first grounding portion and the second grounding portion are on the same side and electrically connected, and the second ends of the first grounding portion and the second grounding portion are on the same side and electrically connected.

4. The circuit board according to claim 3, characterized in that, the signal layer further includes: a first lead disposed on the first dielectric layer, the first lead is electrically connected to the transmission line, and the metal spacer layer covers the first lead; a second lead disposed on the first dielectric layer; the first grounding portion and the second grounding portion that are electrically connected to each other are electrically connected to the same second lead, and the metal spacer layer covers the second lead.

5. The circuit board according to claim 4, characterized in that, the line width of the transmission line is greater than the line width of the first lead.

6. The circuit board according to claim 4, characterized in that, the line width of at least one of the first grounding portion and the second grounding portion is greater than the line width of the second lead.

7. The circuit board according to any one of claims 2-6, characterized in that, the first dielectric layer and the second dielectric layer are flexible dielectric layers.

8. The circuit board according to claim 7, characterized in that, the signal layer further includes a third dielectric layer, the third dielectric layer is stacked with the first dielectric layer, and the transmission line, the first grounding portion and the second grounding portion are located between the first dielectric layer and the third dielectric layer; the reference layer further includes a fourth dielectric layer, the fourth dielectric layer is stacked with the second dielectric layer, and the metal spacer layer is located between the second dielectric layer and the fourth dielectric layer; wherein, the third dielectric layer and the fourth dielectric layer are flexible dielectric layers.

9. The circuit board according to claim 7, characterized in that, an air gap exists between the signal layer and the reference layer.

10. The circuit board according to claim 9, characterized in that, The circuit board further includes an insulating support portion located within the air gap, and the insulating support portion is connected to the signal layer and the reference layer.

11. The circuit board according to any one of claims 2-10, characterized in that the circuit board includes at least two stacked reference layers, namely a first reference layer and a second reference layer; the signal layer is located between the first reference layer and the second reference layer.

12. The circuit board according to any one of claims 1-11, characterized in that the signal channel includes two of the transmission lines.

13. An electronic device, characterized in that it includes: a rotating shaft mechanism; a circuit board according to any one of claims 1-12, the circuit board being a flexible circuit board; a part of the flexible circuit board passes through the rotating shaft mechanism; a first circuit board, one end of the flexible circuit board is electrically connected to the first circuit board; a second circuit board, the first circuit board and the second circuit board are respectively disposed on both sides of the rotating shaft mechanism; the other end of the flexible circuit board is electrically connected to the second circuit board.

14. The electronic device according to claim 13, characterized in that the electronic device further includes: a metal limiting member, at least a part of the metal limiting member is stacked with the flexible circuit board; when the electronic device is in a flattened state, there is a gap between the metal limiting member and the flexible circuit board; when the electronic device is in a folded state, the metal limiting member abuts against the flexible circuit board; when the metal limiting member abuts against the flexible circuit board, a first distance L1 exists between the surface of the metal limiting member facing the flexible circuit board and the transmission line, and L1≥100μm.

15. The electronic device according to claim 13 or 14, characterized in that the electronic device includes: an insulating layer disposed on the side of the metal limiting member facing the flexible circuit board.

16. The electronic device according to claim 14 or 15, characterized in that the electronic device includes: a middle frame connected to the rotating shaft mechanism; a rear shell, forming a receiving cavity with the middle frame; the first circuit board or the second circuit board is located in the receiving cavity, and a part of the flexible circuit board is located in the receiving cavity and is electrically connected to the first circuit board or the second circuit board; wherein at least one of the middle frame or the rear shell is the metal limiting member.

17. The electronic device according to claim 14 or 15, characterized in that the electronic device further includes a display screen; the rotating shaft mechanism includes: a rotating shaft body disposed on the back of the display screen; a door panel disposed on the back of the display screen, and the door panel is connected to the rotating shaft body and the middle frame; the flexible circuit board is located on the side of the door panel facing away from the display screen, and the door panel serves as the metal limiting member.

18. The electronic device according to any one of claims 14-17, characterized in that the first grounding portion, the second grounding portion and the transmission lines in the same signal channel form a coplanar waveguide; When the electronic device changes from the flattened state to the folded state, the range of the impedance change rate ΔZ of the coplanar waveguide satisfies: -10％≤△Z≤+10％。

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