Flexible circuit board assembly and electronic equipment

Abstract

The invention discloses a flexible circuit board assembly and electronic equipment, and relates to the technical field of circuits. The flexible circuit board assembly comprises a flexible circuit board body, a first wiring group and a second wiring group, and the first wiring group and the second wiring group are arranged on the flexible circuit board body; the second routing group extends along a first direction, the first routing group is spirally wound on the outer side of the second routing group, at least one switch piece is arranged in the first routing group, and the switch piece is used for adjusting the access length of the first routing group.

Description

Technical Field

[0001] This application relates to the field of circuit technology, specifically to a flexible circuit board assembly and electronic device. Background Technology

[0002] In related technologies, with the rapid development of electronic products, users have increasingly higher demands for thinner and lighter electronic products. Consequently, the internal stacking space of electronic products is approaching its limit. On the one hand, to meet users' needs for high-speed internet access, electronic products need to integrate more antennas to meet users' communication needs; on the other hand, to achieve more functions, more functional modules, such as cameras, fingerprint unlocking, linear motors, and speakers, need to be placed in a limited space to meet users' functional needs and improve user experience.

[0003] Against this backdrop and trend, insufficient internal stacking space in electronic products means that flexible printed circuit boards (FPCs) used for signal transmission inevitably need to be placed closer and closer to antennas. This results in insufficient isolation between the antenna and the FPC, causing interference to the signal traces of the FPC when the antenna is in operation. Summary of the Invention

[0004] This application provides a flexible circuit board assembly and an electronic device that can solve the problem of antenna interference with the signal traces of the FPC in related technologies.

[0005] In a first aspect, a flexible circuit board assembly is provided, comprising: a flexible circuit board body, a first wiring group and a second wiring group, wherein the first wiring group and the second wiring group are disposed on the flexible circuit board body;

[0006] The second wiring group extends along the first direction, and the first wiring group is spirally wound around the outside of the second wiring group. At least one switch is provided in the first wiring group, and the switch is used to adjust the access length of the first wiring group.

[0007] In a second aspect, an electronic device is provided, including a fingerprint module, a circuit board, an antenna module, and a flexible circuit board assembly as described in the first aspect, wherein the fingerprint module is electrically connected to the circuit board through the flexible circuit board assembly, the antenna module is disposed on the periphery of the fingerprint module, and the electronic device adjusts the conduction state of the switching element according to the working state of the antenna module to adjust the access length of the first wiring group.

[0008] In this embodiment, the flexible circuit board assembly includes a flexible circuit board body, a first trace group, and a second trace group, with the first trace group and the second trace group disposed on the flexible circuit board body. The first trace group is spirally wound around the outside of the second trace group. Since the first trace group is spirally shaped, it can be equivalent to a coreless solenoid coil. Thus, when the flexible circuit board assembly is within the radiation field range of the antenna, the alternating electromagnetic field generated by the antenna can couple to the first trace group, causing the first trace group to generate an induced field opposite to the antenna electromagnetic field. This induced field can cancel the influence of the antenna electromagnetic field on the internal traces of the flexible circuit board assembly, thereby reducing the induced voltage coupled from the antenna to the flexible circuit board assembly and improving the anti-interference capability of the flexible circuit board assembly. Furthermore, by providing at least one switch in the first trace group, which is used to adjust the access length of the first trace group, the access length of the first trace group can be adjusted by controlling the on / off state of the switch, thereby changing its equivalent inductance. This helps to optimize the equivalent impedance in a specific frequency band, thereby reducing the resonance effect caused by the inter-turn distributed capacitance, and thus reducing the interference of the antenna on the signal trace. Attached Figure Description

[0009] Figure 1 This is one of the side views of the fingerprint module and flexible circuit board assembly provided in the embodiments of this application when they are in a connected state;

[0010] Figure 2 This is one of the top views of the fingerprint module and flexible circuit board assembly provided in the embodiments of this application when they are in a connected state;

[0011] Figure 3 This is one of the cross-sectional schematic diagrams of the fingerprint module and flexible circuit board assembly in the connected state provided in the embodiments of this application;

[0012] Figure 4 This is a second top view of the fingerprint module and flexible circuit board assembly provided in this application embodiment when they are in a connected state;

[0013] Figure 5 This is the second cross-sectional schematic diagram of the fingerprint module and flexible circuit board assembly provided in the embodiments of this application when they are in a connected state;

[0014] Figure 6 This is a schematic diagram of the equivalent circuit structure of the first wiring group in the embodiments of this application;

[0015] Figure 7 This is a schematic diagram of the flexible circuit board assembly in the embodiments of this application;

[0016] Figure 8This is a schematic diagram of the structure of the electronic device in the embodiments of this application;

[0017] Figure 9 This is a structural block diagram of the flexible circuit board assembly in the embodiments of this application;

[0018] Figure 10 This is a second side view of the fingerprint module and flexible circuit board assembly provided in this application embodiment when they are in a connected state. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same class, not limited in number; for example, the first object can be one or more. Furthermore, "or" in this application indicates at least one of the connected objects. For example, the scope of protection for "A or B" covers at least three scenarios: Scenario 1: including A but not B; Scenario 2: including B but not A; Scenario 3: including both A and B. In addition, the terms "A and / or B," "at least one of A and B," and "at least one of A or B" also cover at least the above three scenarios. The character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The flexible circuit board assembly and electronic device provided in this application will be described in detail below with reference to the accompanying drawings and through some embodiments and application scenarios.

[0022] Please see Figures 1 to 3 This application provides a flexible circuit board assembly, including: a flexible circuit board body 100, a first wiring group 200 and a second wiring group 300, wherein the first wiring group 200 and the second wiring group 300 are disposed on the flexible circuit board body 100.

[0023] The second wiring group 300 extends along the first direction, and the first wiring group 200 is spirally wound around the outside of the second wiring group 300. At least one switch 220 is provided in the first wiring group 200, and the switch 220 is used to adjust the access length of the first wiring group.

[0024] Flexible circuit board assemblies can be used to connect circuit boards inside electronic devices and various functional modules within the electronic devices. For example, in some embodiments of this application, the flexible circuit board assembly can serve as an FPC connecting a fingerprint module 400, or as an FPC connecting a camera module, or as an external FPC connecting sensors, Universal Serial Bus (USB), screens, etc. In related technologies, the high-frequency energy of antennas in electronic devices can easily couple to the FPC traces of nearby fingerprint, camera, and other modules. When the high-frequency energy of the antenna coupled to the FPC traces flows through the FPC traces to the baseband processor's communication and control ports, which exhibit nonlinearity, harmonic components are generated under radio frequency energy excitation. These components are then radiated outward through the FPC, causing radiated spurious emissions (RSE) to fail to meet regulatory standards, affecting the project's market launch. Based on this, in this embodiment of the application, by making the first trace group 200 spiral, the first trace group 200 can be equivalent to a coreless solenoid coil. In this way, when the flexible circuit board assembly is within the radiation field range of the antenna, the alternating electromagnetic field generated by the antenna can be coupled to the first trace group 200, so that the first trace group 200 can generate an induced field opposite to the antenna electromagnetic field. This induced field can cancel the influence of the antenna electromagnetic field on the internal traces of the flexible circuit board assembly, thereby reducing the induced voltage of the antenna coupled to the flexible circuit board assembly, and thus improving the anti-interference capability of the flexible circuit board assembly.

[0025] The aforementioned first trace group 200 and second trace group 300 can be two trace groups obtained by dividing all traces included in the flexible circuit board assembly into two groups. The first trace group 200 includes at least one trace, and the second trace group 300 includes at least one trace. The types of traces included in the flexible circuit board assembly can be determined according to the application scenario of the flexible circuit board assembly. For example, in some embodiments of this application, when the flexible circuit board assembly is used as the FPC of the fingerprint module 400, the flexible circuit board assembly can include the following traces: Analog Voltage D (AVDD) power trace, Serial Peripheral Interface Clock (SPI CLK) signal line, and Reset (RST) control line and Interrupt (INT) control line. The traces included in the first trace group 200 and the second trace group 300 can be configured as needed. For example, in some embodiments of this application, the first trace group 200 may include traces in the flexible circuit board assembly with relatively high tolerance thresholds to antenna electromagnetic interference, such as INT control lines or RST control lines. Correspondingly, the second trace group 300 may include traces in the flexible circuit board assembly with relatively low tolerance thresholds to antenna electromagnetic interference, such as AVDD power traces and SPI CLK signal lines. In this way, a coreless solenoid coil can be formed by traces with relatively high tolerance thresholds to antenna electromagnetic interference, thereby improving the anti-interference capability of traces with relatively low tolerance thresholds inside.

[0026] Please see Figure 1 and Figure 2 The aforementioned spiral shape of the first trace group 200 can refer to the traces in the first trace group 200 having a hollow, cylindrical spiral structure. The extension direction of the first trace group 200 is the same as the length direction of the flexible circuit board body 100, that is, the spiral forward direction of the first trace group 200 is the same as the length direction of the flexible circuit board body 100, and also, the length direction of the central axis of the first trace group 200 is the same as the length direction of the flexible circuit board body 100. It can be understood that the aforementioned first direction can be the extension direction of the first trace group 200, that is, the length direction of the first trace group 200.

[0027] For ease of understanding, this application embodiment uses the flexible circuit board assembly as the FPC of the fingerprint module 400 as an example to further explain the structure of the flexible circuit board assembly:

[0028] In related technologies, the fingerprint module 400 is typically located on the side bezel of an electronic device. Furthermore, when the electronic device uses a metal frame, an antenna is usually also located within the side bezel, making the distance between the antenna and the fingerprint module 400 relatively close. Please refer to [link to relevant documentation]. Figure 8 This diagram illustrates the relative positional relationship between the fingerprint module 400 and the antenna. Since the fingerprint module 400 is located outside the antenna module 800, and the antenna module 800's main radiation direction during operation is towards the fingerprint module 400, mutual interference is likely to occur between them. The specific manifestations and principles of this problem are as follows:

[0029] A fingerprint module 400 typically consists of an AVDD power supply trace, an SPI CLK signal line, and RST and INT control lines, such as... Figure 9 As shown. Its interference mechanism is as follows:

[0030] The AVDD power trace supplies power to the analog circuitry of the fingerprint module 400, and it is highly sensitive to power supply ripple and noise. When the antenna transmits at high power, the radio frequency signal is superimposed on the AVDD power trace, causing ripple in the fingerprint module 400's supply voltage. This typically results in noticeable ripples or noise in the fingerprint image read by the fingerprint module 400, significantly affecting its recognition accuracy and effectiveness. In extreme scenarios, it can even cause the AVDD power supply voltage to exceed the fingerprint module 400's tolerance range, thus burning out the device.

[0031] SPI is a synchronous serial communication interface used for communication between microcontrollers and peripheral devices such as sensors, Secure Digital (SD) cards, and other microcontrollers. It typically uses four lines: Clock (SCK), Master Out Slave In (MOSI), Master In Slave Out (MISO), and Slave Select (SS). External electromagnetic interference from the antenna's transmission power can cause errors in the SPI bus signal transmission, thus affecting the demodulation of the fingerprint module 400.

[0032] RST Control Line: The RST pin of the fingerprint module 400 is the reset pin, used to restore the entire chip to its initial state. When a system fault or abnormality occurs, the reset circuit generates a reset signal, which is sent to the system processor through the RST pin. After receiving the reset signal, the system will perform a reset operation, clearing all registers and states to ensure correct system operation and improve system stability and reliability.

[0033] INT control line: Its main function is to detect user touch actions. When the system is in sleep mode, if it detects user touch on the fingerprint module 400, it will send an interrupt signal to the main control MCU to wake up the system. After the system is woken up, the fingerprint recognition module starts working, completes fingerprint matching, and after successful matching, the main control MCU controls the fingerprint module to power off. Then the system enters sleep mode, waiting for the next touch.

[0034] According to Faraday's law of electromagnetic induction, when the magnetic flux (Φ) through a closed conducting loop changes, an induced electromotive force (ε) is generated in the loop, thus producing an induced current. The magnitude of the induced electromotive force is equal to the negative of the rate of change of magnetic flux, calculated using the following formula:

[0035]

[0036] Induced electromotive force, unit: V, volt; Magnetic flux through a loop, unit: Wb, Weber.

[0037] The negative sign in the formula indicates that the direction of the induced electromotive force always opposes the change in magnetic flux. This can be explained by Lenz's law: the direction of the induced current always opposes the change in magnetic flux that caused the induced current. Therefore, the first trace group 200 can generate an induced field opposite to the antenna electromagnetic field, which can cancel the influence of the antenna electromagnetic field on the internal traces of the flexible circuit board assembly.

[0038] Based on the above principle, in this embodiment, a closed coil trace is designed on the fingerprint FPC, wherein the closed coil trace is the first trace group 200 mentioned above, which wraps around the internal fingerprint circuit trace. When the alternating electromagnetic field of the antenna is coupled to the closed coil of the fingerprint FPC, an induced field opposite to the electromagnetic field of the antenna is generated, which cancels the influence of the antenna on the fingerprint circuit trace, reduces the induced voltage of the antenna coupled to the fingerprint trace, and thus improves the mutual interference problem between the side fingerprint module 400 and the antenna.

[0039] In related technologies, due to the limited space for antenna stacking inside electronic devices, a single antenna often needs to be compatible with multiple frequency bands. The frequency bands can be covered by low-frequency antennas to high-frequency antennas, resulting in a large span of the antenna's operating frequency band.

[0040] It is understood that the aforementioned switch 220 may also include a control terminal, which can be electrically connected to the relevant control circuit board of the electronic device through the wiring in the second wiring group 300, so as to control the on / off state of each switch 220 through the circuit board.

[0041] Figure 1In the illustrated embodiment, since the number of turns of the electromagnetic induction coil formed by the first wiring group 200 is fixed, it is generally not compatible with all frequency bands from low to high frequencies. Due to the influence of the distributed capacitance between the turns of the electromagnetic induction coil, a resonance effect will occur within a specific frequency band, thereby changing the equivalent impedance and affecting the suppression effect of the induction coil on the antenna's electromagnetic field. Based on this, in this embodiment, the wiring in the first wiring group can be divided into at least two relatively independent spiral segments 210 along the length direction, and the spiral segments 210 can be connected by a switch 220. In this way, by controlling the on / off state of the switch 220, the connection between each spiral segment 210 can be controlled, thereby adjusting the access length of the first wiring group, making the access length of the first wiring group adjustable. When the access length of the first wiring group changes, its corresponding resonant frequency band will also change, thereby adapting to different antenna frequency bands.

[0042] In this embodiment, the flexible circuit board assembly includes a flexible circuit board body 100, a first trace group 200, and a second trace group 300, with the first trace group 200 and the second trace group 300 disposed on the flexible circuit board body 100. The first trace group 200 is spirally wound around the outside of the second trace group 300. Since the first trace group 200 is spirally shaped, it can be equivalent to a coreless solenoid coil. Thus, when the flexible circuit board assembly is within the radiation field range of the antenna, the alternating electromagnetic field generated by the antenna can couple to the first trace group 200, allowing the first trace group 200 to generate an induced field opposite to the antenna's electromagnetic field. This induced field can cancel the influence of the antenna's electromagnetic field on the internal traces of the flexible circuit board assembly, thereby reducing the induced voltage coupled from the antenna to the flexible circuit board assembly and improving the anti-interference capability of the flexible circuit board assembly. Furthermore, by providing at least one switch 220 in the first wiring group 200, the switch 220 is used to adjust the access length of the first wiring group 200. In this way, the access length of the first wiring group 200 can be adjusted by controlling the on / off state of the switch 220, thereby changing its equivalent inductance. This is beneficial for optimizing the equivalent impedance in a specific frequency band, thereby reducing the resonance effect caused by the inter-turn distributed capacitance.

[0043] Optionally, the flexible circuit board body 100 includes a first wiring layer 110, a second wiring layer 120 and a third wiring layer 130 arranged sequentially at intervals along the thickness direction of the flexible circuit board body 100.

[0044] The second wiring group 300 is disposed on the second wiring layer 120, and the first wiring group 200 passes through the first wiring layer 110 and the third wiring layer 130.

[0045] In some embodiments of this application, the first trace group 200 may include a first trace portion and a second trace portion, the first trace portion being located in the first wiring layer 110 and the second trace portion being located in the second wiring layer 120. The first trace portion includes a plurality of first sub-segments, and the second trace portion includes a plurality of second sub-segments. The plurality of first sub-segments are arranged at intervals along the length direction of the first wiring layer 110, and the plurality of second sub-segments are arranged at intervals along the length direction of the third wiring layer 130. Among the plurality of first sub-segments, two adjacent first sub-segments correspond to one second sub-segment, and two adjacent first sub-segments are electrically connected through their corresponding second sub-segments.

[0046] The flexible circuit board body 100 may include three or more wiring layers. When the number of wiring layers in the flexible circuit board body 100 is equal to three, the first wiring layer 110, the second wiring layer 120, and the third wiring layer 130 are the three wiring layers included in the flexible circuit board body 100. Correspondingly, when the number of wiring layers in the flexible circuit board body 100 is greater than three, the first wiring layer 110 and the third wiring layer 130 are the two outermost wiring layers of the flexible circuit board body 100, and the second wiring layer 120 is any one of the wiring layers between the first wiring layer 110 and the third wiring layer 130. An insulating dielectric layer may be filled between any two adjacent wiring layers in the flexible circuit board body 100 to separate the adjacent wiring layers. Various desired traces can be deployed in the above wiring layers.

[0047] For example, see Figure 1 In some embodiments of this application, the fingerprint FPC includes multiple layers of traces, with the fingerprint circuit traces designed in the inner layer and the GND traces designed in the outer layer. The GND traces diagonally cross the FPC from the first layer, punch a hole at the other end to the last layer, then diagonally cross the FPC from the last layer, punch a hole back to the first layer, and so on, repeating this process. By alternately routing the traces in a winding manner, an n-turn wound coil is formed.

[0048] The FPC design is approximated as a coreless solenoid coil, and the equivalent inductance of an electromagnetic induction coil is calculated using the simplified formula:

[0049]

[0050] , representing the vacuum permeability; N: total number of turns of the coil; A: cross-sectional area of ​​a single turn of the coil, in m², where A is approximately [missing information] in some embodiments of this application. ; : Coil length.

[0051] Based on this calculation, if 110 turns are wound on a 25mm long FPC, an electromagnetic induction coil with an equivalent inductance of 100nH can be obtained, that is, the width of a single turn trace is about 0.23mm, which is theoretically achievable by FPC technology.

[0052] From the formula, the number of coil turns N and the coil length As can be seen from the relationship, the more turns a coil has per unit length, the greater its equivalent inductance. Furthermore, given a fixed equivalent inductance, the number of turns can be reduced by increasing the coil winding density, thereby lowering the requirements for FPC manufacturing processes.

[0053] This allows for the addition of an electromagnetic induction coil to the FPC, reducing the induced voltage coupled from the antenna to the fingerprint traces and improving the mutual interference issue between the side fingerprint module 400 and the antenna. Simultaneously, the FPC traces are routed using a winding method, which does not affect the bending of the FPC, such as... Figure 7 The diagram shows one of the bending states of an FPC.

[0054] In this embodiment, the flexible circuit board body 100 includes a first wiring layer 110, a second wiring layer 120, and a third wiring layer 130 arranged sequentially at intervals along the thickness direction of the flexible circuit board body 100; the second trace group 300 is disposed in the second wiring layer 120, and the first trace group 200 passes through the first wiring layer 110 and the third wiring layer 130. In this way, an electromagnetic induction coil can be formed by the traces located on the outer layer to reduce the interference of the electromagnetic field of the external antenna on the traces in the inner layer.

[0055] Optionally, the first wiring group 200 is grounded, and the second wiring group 300 is used to transmit signals.

[0056] Since the first trace group 200 is grounded, the traces in the first trace group 200 can also be referred to as ground (GND) traces. Correspondingly, since the second trace group 300 is used for signal transmission, the second trace group 300 may include control traces or signal transmission traces.

[0057] The aforementioned GND trace can be electrically connected to the ground plane 600 or an equivalent ground structure in the flexible circuit board assembly. The traces in the aforementioned second trace group 300 can be determined according to the specific application scenario of the flexible circuit board assembly. For example, when the flexible circuit board assembly is used as a fingerprint FPC, the second trace group 300 may include the following traces: AVDD power trace, SPI CLK signal line, and RST control line and INT control line.

[0058] In this embodiment, by grounding the first trace group 200 and using the second trace group 300 for signal transmission, since the GND trace has a relatively high tolerance threshold to antenna electromagnetic interference, by placing the GND trace on the outer layer of the second trace group 300 to form an electromagnetic induction coil, effective protection can be achieved for the second trace group 300 located on the inner side, thereby reducing the interference of external antenna electromagnetic fields on the control traces.

[0059] Optionally, the first wiring group 200 includes at least two spiral segments 210, and the at least two spiral segments 210 are arranged along the first direction;

[0060] Of the at least two spiral segments 210, two adjacent spiral segments 210 are electrically connected by a switch element 220.

[0061] The first wiring group 200 mentioned above includes at least two spiral segments 210, which may mean that the grounding wiring in the first wiring group 200 includes at least two spiral segments 210.

[0062] It is understandable that the number of the aforementioned switch element 220 is one less than the number of the spiral segments 210, thus ensuring that there is a switch element 220 for connection between two adjacent spiral segments 210.

[0063] In related technologies, due to the limited space for antenna stacking inside electronic devices, a single antenna often needs to be compatible with multiple frequency bands. The frequency bands can be covered by low-frequency antennas to high-frequency antennas, resulting in a large span of the antenna's operating frequency band.

[0064] It is understood that the aforementioned switch 220 may also include a control terminal, which can be electrically connected to the relevant control circuit board of the electronic device through the wiring in the second wiring group 300, so as to control the on / off state of each switch 220 through the circuit board.

[0065] Figure 1 In the illustrated embodiment, since the number of turns of the electromagnetic induction coil formed by the first wiring group 200 is fixed, it is generally not compatible with all frequency bands from low to high frequencies. Due to the influence of the distributed capacitance between the turns of the electromagnetic induction coil, a resonance effect will occur within a specific frequency range, thereby changing the equivalent impedance and affecting the suppression effect of the induction coil on the antenna's electromagnetic field. Based on this, in this embodiment, the grounding wiring can be divided into at least two relatively independent spiral segments 210 along its length, and the spiral segments 210 can be connected by a switch 220. In this way, by controlling the on / off state of the switch 220, the connection between each spiral segment 210 can be controlled, thereby adjusting the length of the grounding wiring, making the length of the grounding wiring adjustable. When the length of the grounding wiring changes, its corresponding resonant frequency band will also change, thereby adapting to different antenna frequency bands.

[0066] In this embodiment, the grounding trace includes at least two spiral segments 210 and at least one switch 220. The spiral segments 210 are spiral-shaped and arranged along the first direction. Two adjacent spiral segments 210 are electrically connected by the switch 220. Thus, the number of turns of the electromagnetic induction coil formed by the grounding trace can be adjusted by controlling the on / off state of the switch 220, thereby changing its equivalent inductance. This is beneficial for optimizing the equivalent impedance in a specific frequency band, thereby reducing the resonance effect caused by the inter-turn distributed capacitance.

[0067] Optionally, the at least two spiral segments 210 include a first spiral segment 230 and a second spiral segment 240, and the at least one switching element 220 includes a first switching element 250, wherein the first spiral segment 230 and the second spiral segment 240 are any two adjacent spiral segments 210 among the at least two spiral segments 210, and the first switching element 250 is a switching element 220 connecting the first spiral segment 230 and the second spiral segment 240;

[0068] The flexible circuit board body 100 includes a first wiring layer 110, a second wiring layer 120, and a third wiring layer 130 arranged sequentially at intervals along the thickness direction of the flexible circuit board body 100. The second wiring layer 120 includes a ground layer 600. The first switching element 250 includes a moving end 251, a first stationary end 252, and a second stationary end 253. The moving end 251 is electrically connected to one end of the first spiral segment 230 facing the second spiral segment 240. The first stationary end 252 is electrically connected to one end of the second spiral segment 240 facing the first spiral segment 230. The second stationary end 253 is electrically connected to the ground layer 600.

[0069] When the first switch 250 is in the first state, the moving end 251 is connected to the first stationary end 252, and the moving end 251 is disconnected from the second stationary end 253;

[0070] When the first switch 250 is in the second state, the moving end 251 is disconnected from the first stationary end 252, and the moving end 251 is connected to the second stationary end 253.

[0071] It is understood that the connection method between the first spiral segment 230, the second spiral segment 240 and the first switch 250 is only an example of two adjacent spiral segments 210. In fact, in the above grounding wiring, any two adjacent spiral segments 210 are connected using this example connection method.

[0072] Please see Figures 4 to 6 In some embodiments of this application, the aforementioned switch 220 is a single-pole double-throw (SPDT) switch 220. Specifically, the operating frequency band of the antenna located near the flexible circuit board assembly can be identified by the electronic device to which the flexible circuit board assembly belongs, and the on / off state of the aforementioned switch 220 can be controlled according to the operating frequency band of the antenna. For example, when the electronic device detects that the antenna is operating at a low frequency, the coil needs to provide a relatively large equivalent inductance to suppress the antenna electromagnetic field. At this time, all or part of the switch 220 can be controlled to be in the first state to increase the length of the induction coil and increase the equivalent inductance. Correspondingly, when the antenna is operating at a high frequency, the inter-turn capacitance effect of the coil is enhanced. In order to avoid the inter-turn capacitance and the coil equivalent inductance forming LC resonance and affecting the anti-interference effect of the electromagnetic induction coil, all or part of the switch 220 can be controlled to be in the second state to reduce the length of the induction coil.

[0073] Typically, multiple antennas surround the fingerprint module 400, covering multiple antenna frequency bands. Therefore, it is often necessary to preset the length of the fingerprint FPC induction coil for various states to cope with electromagnetic interference from antennas at different locations and frequencies. Based on the above principle and solution, multiple SPDT switches can be added at different locations along the length of the grounding trace to adjust the number of turns of the coil formed by the grounding trace.

[0074] In this embodiment, by making the at least two spiral segments 210 include a first spiral segment 230 and a second spiral segment 240, and the at least one switching element 220 includes a first switching element 250, wherein the first spiral segment 230 and the second spiral segment 240 are any two adjacent spiral segments 210 among the at least two spiral segments 210, and the first switching element 250 is a switching element 220 connecting the first spiral segment 230 and the second spiral segment 240; the second wiring layer 120 includes a ground layer 600, and the first switching element 250 includes a moving end 251, a first stationary end 252, and a second stationary end 253, wherein the moving end 251 is oriented towards the second spiral segment 240 from the first spiral segment 230. One end of the first stationary end 252 is electrically connected to the end of the second spiral segment 240 facing the first spiral segment 230, and the second stationary end 253 is electrically connected to the ground layer 600. When the first switch 250 is in the first state, the moving end 251 is connected to the first stationary end 252 and disconnected from the second stationary end 253. When the first switch 250 is in the second state, the moving end 251 is disconnected from the first stationary end 252 and connected to the second stationary end 253. In this way, the number of turns of the induction coil formed by the grounding line can be adjusted by controlling the on / off state of the switch 220, thereby adapting to different antenna frequency bands.

[0075] Optionally, the first trace group 200 includes at least one of the following traces: a reset (RST) control trace and an interrupt (INT) control trace; the second trace group 300 includes at least one of the following traces: a synchronous serial communication interface (SPI) trace and an analog power supply voltage (AVDD) trace.

[0076] Since RST and INT control traces typically transmit digital control signals with levels between 1.2V and 1.8V, their requirements for ripple and signal quality are much lower than those for SPI and AVDD. Generally, ripple less than 1.2V*30%=0.36V or 1.8V*30%=0.54V is sufficient to meet system requirements, resulting in a relatively high tolerance threshold for antenna electromagnetic interference. Based on this, in the embodiments of this application, RST or INT can be designed as closed coils, utilizing signal traces with relatively high interference tolerance thresholds to protect sensitive traces, fully utilizing FPC trace space, and relatively... Figure 1 and Figure 4 The embodiments shown can achieve the goal of narrowing the FPC width or reducing the number of FPC layers, thereby saving stacking space and FPC manufacturing costs.

[0077] Based on the relatively high tolerance threshold of antenna electromagnetic interference to the RST and INT control traces, the AVDD and SPI lines are routed on the inner layer of the FPC, while the RST and INT lines are routed on the outer layer. This utilizes the RST and INT traces to protect the more sensitive AVDD and SPI traces. Taking a three-layer FPC design for a side fingerprint sensor as an example, sensitive traces such as AVDD and SPI are routed on the second layer. The RST or INT trace is routed diagonally across the FPC on the first layer, with a via on the other side leading to the third layer. It then crosses the FPC again from the third layer, with a via returning to the first layer, and so on. This process is repeated, using an alternating routing method to form an n-turn wound coil. With this routing method, the RST or INT control trace forms a closed coil on the FPC, thus canceling the interference of the antenna radiation field on sensitive traces such as AVDD and SPI.

[0078] In this embodiment, by including at least one of the following traces in the first trace group 200: a reset control trace and an interrupt control trace; and by including at least a synchronous serial communication interface (SPI) trace and an analog power supply voltage trace in the second trace group 300, sensitive traces are protected using signal traces with relatively high interference tolerance thresholds, thus making full use of the FPC trace space. Figure 10 The illustrated embodiment is relative to Figure 1 and Figure 4 The embodiments shown can achieve the goal of narrowing the FPC width or reducing the number of FPC layers, thereby saving stacking space and FPC manufacturing costs.

[0079] Some embodiments of this application also provide an electronic device, which includes a fingerprint module 400, a circuit board, an antenna module 800, and the flexible circuit board assembly described in the above embodiments. The fingerprint module 400 is electrically connected to the circuit board through the flexible circuit board assembly. The antenna module 800 is disposed around the fingerprint module 400. The electronic device adjusts the conduction state of the switch according to the working state of the antenna module 800 to adjust the access length of the first wiring group 200.

[0080] The circuit board can be various types of control circuit boards in electronic devices, such as the motherboard in an electronic device.

[0081] Please see Figure 1 In some embodiments of this application, one end of the flexible circuit board assembly is connected to the fingerprint module 400, and the other end of the flexible circuit board assembly is connected to a circuit board connector 500. The flexible circuit board assembly can be electrically connected to the circuit board through the circuit board connector 500.

[0082] In this embodiment, since the electronic device includes the flexible circuit board assembly described in the above embodiments, the electronic device can implement each process of the flexible circuit board assembly and has the same beneficial effects. To avoid repetition, it will not be described again here.

[0083] Optionally, the at least two spiral segments 210 have at least two operating states, each of which corresponds to at least two antenna frequency bands, and the access lengths corresponding to different operating states are different.

[0084] When at least two spiral segments 210 are in the first working state, the access length of the first wiring group 200 is matched with the antenna frequency band corresponding to the first working state, wherein the first working state is any one of the at least two working states.

[0085] In some embodiments of this application, the length and number of turns of each spiral segment 210 can be determined in advance according to the actual situation, so that each spiral segment 210 can correspond to an antenna frequency band independently. At the same time, when each spiral segment 210 is connected to other segments, it can also correspond to other frequency bands.

[0086] In this embodiment, by having at least two spiral segments 210 exist in at least two operating states, each of which corresponds to at least two antenna frequency bands, and the access lengths corresponding to different operating states are different; when the at least two spiral segments 210 are in a first operating state, the access length of the first trace group 200 matches the antenna frequency band corresponding to the first operating state, wherein the first operating state is any one of the at least two operating states, the first trace group 200 can cancel out different antenna frequency bands, thereby further improving the anti-interference effect of the flexible circuit board assembly.

[0087] Optionally, the at least two spiral segments 210 include a third spiral segment, a fourth spiral segment, and a fifth spiral segment, and the at least one switching element 220 includes a second switching element and a third switching element, wherein the third spiral segment, the fourth spiral segment, and the fifth spiral segment are any three adjacent spiral segments 210 among the at least two spiral segments 210, the second switching element is a switching element 220 connecting the third spiral segment and the fourth spiral segment, and the third switching element is a switching element 220 connecting the fourth spiral segment and the fifth spiral segment;

[0088] The access length of the third spiral segment is the first length, the access length of the fourth spiral segment is the second length, the access length of the fifth spiral segment is the third length, the sum of the access lengths of the third spiral segment and the fourth spiral segment is the fourth length, the sum of the access lengths of the fourth spiral segment and the fifth spiral segment is the fifth length, and the sum of the access lengths of the third spiral segment, the fourth spiral segment and the fifth spiral segment is the sixth length.

[0089] The adjustment range of the access length of the first wiring group 200 includes the first length, the second length, the third length, the fourth length, the fifth length, and the sixth length.

[0090] It is understood that this application embodiment only uses the third spiral segment, the fourth spiral segment, and the fifth spiral segment in the first wiring group 200 as examples to illustrate the adjustment method of the access length of the first wiring group 200. In fact, the first wiring group 200 may include other spiral segments in addition to the third spiral segment, the fourth spiral segment, and the fifth spiral segment. The third spiral segment, the fourth spiral segment, and the fifth spiral segment are just any three adjacent spiral segments in the first wiring group 200.

[0091] In some embodiments of this application, the first spiral segment 230 and the second spiral segment 240 may be two of the third spiral segment, the fourth spiral segment and the fifth spiral segment. Correspondingly, the first switching element 250 may be one of the second switching element and the third switching element.

[0092] Please see Figure 6 In some embodiments of this application, the grounding trace includes three helical segments 210 and two switching elements S1 and S2. The lengths of the three helical segments 210 are L1, L2, and L3, respectively. Thus, by switching the switching states of S1 and S2, the at least two helical segments 210 can be switched between at least two operating states. The at least two operating states can include the following six length states: L1, L2, L3, L1+L2, L1+L2+L3, and L2+L3. For the operating states L1, L2, and L3, the switching elements 220 are as follows: S1 and S2 are both in the second state. For L1+L2, the switching element 220 is as follows: S1 is in the first state, and S2 is in the second state. For L1+L2+L3, the switching element 220 is as follows: S1 and S2 are both in the first state. For L2+L3, the switching element 220 is as follows: S1 is in the second state, and S2 is in the first state.

[0093] In this embodiment, since each of the at least two spiral segments 210 can individually correspond to a frequency band, and combinations of different spiral segments can also correspond to other frequency bands, the number of frequency bands corresponding to the first trace group 200 can be further increased, thereby enabling the cancellation of more antenna frequency bands and further improving the anti-interference effect of the flexible circuit board assembly.

[0094] Optionally, the antenna module 800 and the fingerprint module 400 are respectively disposed on the frame of the electronic device, and the fingerprint module 400 is located outside the antenna module 800.

[0095] Please see Figure 8 Since the fingerprint module 400 is located outside the antenna module 800, it is within the radiation field of the antenna module 800. At the same time, since the fingerprint module 400 has anti-interference performance, the interference of the antenna radiation field on the fingerprint module 400 can be reduced.

[0096] In this embodiment, since the antenna module 800 and the fingerprint module 400 are respectively disposed on the frame of the electronic device, and the fingerprint module 400 is located outside the antenna module 800, the interference of the antenna radiation field on the fingerprint module 400 can be reduced.

[0097] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A flexible circuit board assembly, characterized in that, include: The flexible circuit board body, the first wiring group and the second wiring group are disposed on the flexible circuit board body; The second wiring group extends along the first direction, and the first wiring group is spirally wound around the outside of the second wiring group. At least one switch is provided in the first wiring group, and the switch is used to adjust the access length of the first wiring group.

2. The flexible circuit board assembly according to claim 1, characterized in that, The flexible circuit board body includes a first wiring layer, a second wiring layer and a third wiring layer arranged sequentially at intervals along the thickness direction of the flexible circuit board body. The second wiring group is disposed on the second wiring layer, and the first wiring group passes through the first wiring layer and the third wiring layer.

3. The flexible circuit board assembly according to claim 1 or 2, characterized in that, The first wiring group is grounded, and the second wiring group is used to transmit signals.

4. The flexible circuit board assembly according to claim 3, characterized in that, The first wiring group includes at least two helical segments, and the at least two helical segments are arranged along the first direction; In the at least two spiral segments, two adjacent spiral segments are electrically connected by one of the switching elements.

5. The flexible circuit board assembly according to claim 4, characterized in that, The at least two spiral segments include a first spiral segment and a second spiral segment, and the at least one switching element includes a first switching element, wherein the first spiral segment and the second spiral segment are any two adjacent spiral segments among the at least two spiral segments, and the first switching element is a switching element connecting the first spiral segment and the second spiral segment; The flexible circuit board body includes a first wiring layer, a second wiring layer and a third wiring layer arranged sequentially at intervals along the thickness direction of the flexible circuit board body. The second wiring layer includes a ground layer. The first switching element includes a moving end, a first stationary end and a second stationary end. The moving end is electrically connected to one end of the first spiral segment facing the second spiral segment. The first stationary end is electrically connected to one end of the second spiral segment facing the first spiral segment. The second stationary end is electrically connected to the ground layer. When the first switch is in the first state, the moving end is connected to the first stationary end, and the moving end is disconnected from the second stationary end; When the first switch is in the second state, the moving end is disconnected from the first stationary end, and the moving end is connected to the second stationary end.

6. The flexible circuit board assembly according to claim 1 or 2, characterized in that, The first routing group includes at least one of the following routings: a reset control routing and an interrupt control routing; the second routing group includes at least one of the following routings: a synchronous serial communication interface (SPI) routing and an analog power supply voltage routing.

7. An electronic device, characterized in that, The device includes a fingerprint module, a circuit board, an antenna module, and a flexible circuit board assembly as described in any one of claims 1-6, wherein the fingerprint module is electrically connected to the circuit board via the flexible circuit board assembly, the antenna module is disposed on the periphery of the fingerprint module, and the electronic device adjusts the conduction state of the switch according to the working state of the antenna module to adjust the access length of the first wiring group.

8. The electronic device according to claim 7, characterized in that, The at least two spiral segments have at least two operating states, and the at least two operating states correspond one-to-one with at least two antenna frequency bands. In the at least two operating states, the access lengths corresponding to different operating states are different. When at least two spiral segments are in the first working state, the access length of the first wiring group matches the antenna frequency band corresponding to the first working state, wherein the first working state is any one of the at least two working states.

9. The electronic device according to claim 7, characterized in that, The at least two spiral segments include a third spiral segment, a fourth spiral segment, and a fifth spiral segment; the at least one switching element includes a second switching element and a third switching element; wherein the third spiral segment, the fourth spiral segment, and the fifth spiral segment are any three adjacent spiral segments among the at least two spiral segments; the second switching element is a switching element connecting the third spiral segment and the fourth spiral segment; and the third switching element is a switching element connecting the fourth spiral segment and the fifth spiral segment. The access length of the third spiral segment is the first length, the access length of the fourth spiral segment is the second length, the access length of the fifth spiral segment is the third length, the sum of the access lengths of the third spiral segment and the fourth spiral segment is the fourth length, the sum of the access lengths of the fourth spiral segment and the fifth spiral segment is the fifth length, and the sum of the access lengths of the third spiral segment, the fourth spiral segment and the fifth spiral segment is the sixth length. The adjustment range of the access length of the first wiring group includes the first length, the second length, the third length, the fourth length, the fifth length, and the sixth length.

10. The electronic device according to any one of claims 7 to 9, characterized in that, The antenna module and the fingerprint module are respectively disposed on the frame of the electronic device, and the fingerprint module is located outside the antenna module.

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