Flexible circuit board structure and electronic equipment

Abstract

The invention discloses a flexible circuit board structure and electronic equipment, and relates to the technical field of terminals. The flexible circuit board structure comprises a flexible circuit board body and a first magnetic wave-absorbing material layer. The first magnetic wave-absorbing material layer covers the first surface of the flexible circuit board body, and the first magnetic wave-absorbing material layer is used for inhibiting common-mode current; the first side of the first magnetic wave-absorbing material layer and the first side of the flexible circuit board body are fixed on the first surface, and the second side of the first magnetic wave-absorbing material layer and the second side of the flexible circuit board body are fixed on the first surface. When an EMC (Electro Magnetic Compatibility) problem, such as an electrostatic discharge phenomenon, occurs, the first magnetic wave-absorbing material layer can present an impedance characteristic of an inductor series current, and a common-mode current is an alternating current, so that the size of the common-mode current can be reduced, and further the interference voltage is reduced. The first magnetic wave-absorbing material layer does not need to be completely attached to the surface of the flexible circuit board body, so that the flexible circuit board body can still have good bending resistance.

Description

Technical Field

[0001] This application relates to the field of terminal technology, and in particular to a flexible circuit board structure and electronic device. Background Technology

[0002] Flexible printed circuits (FPCs) are widely used in various electronic devices due to their advantages of being lightweight, thin, and highly resistant to bending. They are used to achieve flexible electrical connections between circuit boards or between circuit boards and devices.

[0003] In electronic devices, it is generally required that the device can operate normally when faced with strong common-mode interference. However, when electromagnetic compatibility (EMC) issues occur, the common-mode current flowing through the FPC can affect the normal operation of the electronic device.

[0004] Therefore, there is a need for a flexible circuit board structure with strong common-mode interference resistance. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a flexible circuit board structure and an electronic device. This flexible circuit board structure reduces common-mode interference received by the flexible circuit board, thereby improving the anti-interference characteristics of the electronic device, while also ensuring the bending resistance of the flexible circuit board itself as much as possible.

[0006] In a first aspect, this application provides a flexible circuit board structure, which includes a flexible circuit board body and a first magnetic absorbing material layer. The first magnetic absorbing material layer covers a first surface of the flexible circuit board body and is used to suppress common-mode current. A first side of the first magnetic absorbing material layer is fixed to a first side of the flexible circuit board body on the first surface, and a second side of the first magnetic absorbing material layer is fixed to a second side of the flexible circuit board body on the first surface.

[0007] In this implementation, a first magnetic absorbing material layer is covered on the first surface of the flexible circuit board body. When EMC problems occur, such as electrostatic discharge, the first magnetic absorbing material layer exhibits the impedance characteristics of an inductive series current. Since the common-mode current is alternating current, the first magnetic absorbing material layer can reduce the magnitude of the common-mode current, thereby reducing interference voltage, improving the anti-interference characteristics of the electronic device, and reducing its sensitivity to interference. Furthermore, the first magnetic absorbing material layer only needs to be fixed to both ends of the flexible circuit board body for coverage, rather than being completely adhered to the surface of the flexible circuit board body. That is, in the bending area of ​​the flexible circuit board body, there can be gaps between the magnetic absorbing material layer and the flexible circuit board body. Therefore, the impact on the flexible circuit board structure is minimal, ensuring that the flexible circuit board body still has good bending resistance and can still be bent normally.

[0008] Furthermore, this solution has wide applicability, does not require a flexible circuit board architecture, and is cost-effective, simple in structure, and easy to manufacture.

[0009] In one possible implementation, the flexible circuit board structure further includes a second magnetic absorbing material layer. The second magnetic absorbing material layer covers the second surface of the flexible circuit board body and is used to suppress common-mode current; a first side of the second magnetic absorbing material layer is fixed to a first side of the flexible circuit board body on the second surface, and a second side of the second magnetic absorbing material layer is fixed to a second side of the flexible circuit board body on the second surface.

[0010] In this implementation, magnetic absorbing material layers are applied to both surfaces of the flexible circuit board. This increases the impedance of the inductor series current in the event of EMC problems, further enhancing the anti-interference characteristics of the electronic device.

[0011] In one possible implementation, the first side and the second side of the flexible circuit board body are located in the non-bending area of ​​the flexible circuit board body.

[0012] In this implementation, the non-bending area of ​​the flexible circuit board body is used to fix the first magnetic absorbing material layer and the second magnetic absorbing material layer, which minimizes the impact on the bending resistance of the flexible circuit board body, so that the flexible circuit board body still has good bending resistance and can still be bent normally.

[0013] In one possible implementation, the first and second magnetic absorbing material layers are made of one or more of the following materials: permalloy, carbonyl iron, silicon aluminum iron, or graphene composite materials. The first and second magnetic absorbing material layers can be made of the same or different materials.

[0014] In one possible implementation, the first magnetic absorbing material layer is fixed to the first surface by a fixing adhesive, and the second magnetic absorbing material layer is fixed to the second surface by a fixing adhesive.

[0015] In this implementation, the magnetic absorbing material layer and the flexible circuit board body are fixed with adhesive, resulting in a simple structure that is easy to implement and has a low cost.

[0016] In one possible implementation, one or more fixing points are included between the first magnetic absorbing material layer and the flexible circuit board body in the bending region of the first surface, and / or one or more fixing points are included between the second magnetic absorbing material layer and the flexible circuit board body in the bending region of the second surface.

[0017] In this implementation, by adding a certain number of fixing points between the magnetic absorbing material layer and the flexible circuit board body, the adhesion between the magnetic absorbing material layer and the flexible circuit board body is increased, thereby improving the anti-interference characteristics of the electronic device. Furthermore, by using fixing points, the impact on the bending resistance of the circuit board body can be minimized while increasing the adhesion.

[0018] In one possible implementation, the area of ​​the first magnetic absorbing material layer can be larger than the surface area of ​​the first surface of the flexible circuit board body, and the area of ​​the second magnetic absorbing material layer can be larger than the surface area of ​​the second surface of the flexible circuit board body. In this case, because the area of ​​the magnetic absorbing material layer is larger, when the bendable area of ​​the flexible circuit board body is bent, the magnetic absorbing material layer will not restrict the flexible circuit board body, thus maximizing the bending resistance of the flexible circuit board itself.

[0019] Secondly, this application also provides an electronic device that includes one or more flexible circuit board structures provided by the first aspect and any implementation thereof. Because the electronic device uses the flexible circuit board structure provided by this application, its anti-interference characteristics are improved.

[0020] In one possible implementation, the electronic device includes at least the following flexible circuit board structure: a first flexible circuit board structure. This first flexible circuit board structure is used to transmit the output signal of the photosensitive element of the electronic device. For example, one end of the first flexible circuit board structure is connected to the photosensitive element, and the other end is connected to an image signal processor (ISP), thereby reducing the interference voltage of electrostatic discharge when the camera of the electronic device is affected by electrostatic discharge.

[0021] In one possible implementation, the electronic device includes at least the following flexible circuit board structure: a second flexible circuit board structure. The second flexible circuit board structure is used to transmit the output signal of the fingerprint sensor of the electronic device. For example, one end of the second flexible circuit board structure is connected to the fingerprint sensor, and the other end is connected to the application processor, thereby reducing the interference voltage of electrostatic discharge when the fingerprint sensor of the electronic device is affected by electrostatic discharge. Attached Figure Description

[0022] Figure 1 Scenario illustration provided for embodiments of this application Figure 1 ;

[0023] Figure 2 Scenario illustration provided for embodiments of this application Figure 2 ;

[0024] Figure 3 This is a schematic diagram of a flexible circuit board structure provided in an embodiment of this application;

[0025] Figure 4 A schematic diagram of another flexible circuit board structure provided in an embodiment of this application;

[0026] Figure 5 A schematic diagram illustrating the magnetic permeability characteristics provided in an embodiment of this application;

[0027] Figure 6 This is a schematic diagram of simulation test results without using the solution proposed in this application;

[0028] Figure 7 A schematic diagram showing the simulation test results after using the solution proposed in this application;

[0029] Figure 8 A schematic diagram of yet another flexible circuit board structure provided in this application embodiment;

[0030] Figure 9 Scenario illustration provided for embodiments of this application Figure 3 ;

[0031] Figure 10 Scenario illustration provided for embodiments of this application Figure 4 . Detailed Implementation

[0032] To enable those skilled in the art to better understand the solution of this application, the application scenario of the technical solution of this application will be described first below.

[0033] EMC (Electromagnetic Computing) studies the generation, propagation, and reception of accidental electromagnetic energy in electrical engineering, as well as the harmful effects caused by this electromagnetic energy, including the problem of common-mode interference. Common-mode interference is an electrical interference that occurs between a signal line and its reference ground (usually power ground or earth ground), exhibiting the same amplitude and phase. Common-mode interference is primarily caused by external electromagnetic fields, internal electromagnetic coupling within the equipment, or differences in ground potential. In electronic equipment, common-mode interference can lead to signal distortion, malfunctions, and degraded equipment performance.

[0034] More common EMC problems in electronic devices occur in electrostatic discharge (ESD) and antenna interference scenarios. When EMC problems occur, the common-mode current flowing through the FPC can affect the normal operation of the electronic device. The following explanation uses the ESD scenario as an example.

[0035] See Figure 1 This figure is a schematic diagram of a scenario provided in an embodiment of this application. Figure 1 .

[0036] When an electronic device has a camera module, electrostatic discharge can cause interference to the camera, as explained below.

[0037] Electronic devices typically have a decorative structure (DECO) 10 on the outside of the camera lens (Lens) 11.

[0038] The voice coil motor (VCM) is used to control the movement of the lens 11.

[0039] An optical image of an object is generated by lens 11 and projected onto sensor 13.

[0040] The photosensitive element 13 can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor.

[0041] The photosensitive element 13 converts the light signal into an electrical signal, and then the electrical signal is transmitted through the flexible circuit board 14 to the image signal processor (ISP) 17 to be converted into a digital image signal.

[0042] One end of the flexible circuit board 14 is connected to the electrical signal output by the photosensitive element 13, and the other end is connected to the board-to-board (B2B or BTB) connector 15 on the printed circuit board (PCB) 18.

[0043] A common-mode inductor 17, also known as a common-mode choke, can be installed on PCB18 to filter common-mode electromagnetic interference signals. PCB18 can be connected to the middle frame 19.

[0044] However, when static electricity enters the camera module from DECO10, it generates common-mode current. This common-mode current travels along the flexible circuit board 14 to PCB18, affecting the normal operation of ISP17 and potentially even other circuit components. The common-mode current flow path can be found in [reference needed]. Figure 1 Line ① in the middle.

[0045] See Figure 2 This figure is a schematic diagram of a scenario provided in an embodiment of this application. Figure 2 .

[0046] The electronic device can be a mobile phone, in which case it supports fingerprint unlocking, meaning there is a fingerprint unlocking area on the screen 20. When the user presses their finger on this area, the fingerprint sensor 21 uses the collected fingerprint characteristics to unlock the device. The fingerprint sensor 21 can be an optical fingerprint sensor, an ultrasonic sensor, a semiconductor capacitive sensor, etc., and this application does not specifically limit it. The fingerprint sensor 21 then outputs the collected data to the application processor (AP) 24 on the PCB via the flexible circuit board 22. One end of the flexible circuit board 22 is connected to the fingerprint sensor 21, and the other end is connected to the BTB connector 23 on the PCB 25.

[0047] During electrostatic discharge, the generated common-mode current travels along the flexible circuit board 22 to the PCB 25, affecting the normal operation of AP24 and potentially other circuit components. The common-mode current flow path can be found in [reference needed]. Figure 2 Line ② in the middle.

[0048] To reduce the impact of common-mode current on electronic devices, this application provides a flexible circuit board structure and electronic device. In the solution provided by this application, a magnetic absorbing material layer is covered on the surface of the flexible circuit board body. Utilizing the high permeability and high magnetic loss characteristics of the magnetic absorbing material layer, the first magnetic absorbing material layer can exhibit the impedance characteristics of inductive series current when EMC problems occur, thereby reducing the current magnitude and improving the anti-interference characteristics. Furthermore, the magnetic absorbing material layer only needs to be fixed to both ends of the flexible circuit board body to achieve coverage, rather than being completely attached to the surface of the flexible circuit board body. That is, in the bending area of ​​the flexible circuit board body, there can be a gap between the magnetic absorbing material layer and the flexible circuit board body. Therefore, the impact on the flexible circuit board structure is small, ensuring that the flexible circuit board still has good bending resistance and is still easy to bend.

[0049] The implementation of the proposed solution is explained in detail below with reference to the accompanying drawings.

[0050] See Figure 3 The figure is a schematic diagram of a flexible circuit board structure provided in an embodiment of this application.

[0051] The flexible circuit board structure shown in the figure includes a flexible circuit board body 31 and a first magnetic absorbing material layer 32.

[0052] The first magnetic absorbing material layer 32 covers the first surface of the flexible circuit board body 31.

[0053] In this embodiment of the application, the flexible circuit board body 31 includes two surfaces, namely a first surface and a second surface, which are opposite to each other.

[0054] Those skilled in the art will generally describe the two surfaces of the flexible circuit board body 31 as upper surface and lower surface. When the first surface is the upper surface, the second surface is the lower surface, and when the first surface is the lower surface, the second surface is the upper surface.

[0055] The first side of the first magnetic absorbing material layer 32 is fixed to the first side of the flexible circuit board body 31 on the first surface, and the second side of the first magnetic absorbing material layer 32 is fixed to the second side of the flexible circuit board body 31 on the first surface.

[0056] The area of ​​the first magnetic absorbing material layer 32 can be greater than, less than, or equal to the area of ​​the first surface of the flexible circuit board body 31. In practical applications, in order to improve anti-interference characteristics, the area of ​​the first magnetic absorbing material layer 32 is generally greater than the area of ​​the first surface of the flexible circuit board body 31, or the two areas are basically the same.

[0057] The first magnetic absorbing material layer 32 uses a material with high magnetic permeability and high magnetic loss rate, including but not limited to one or a combination of materials such as permalloy alloy, carbonyl iron, silicon aluminum iron (FeSiAl), and graphene composite material.

[0058] The thickness of the first magnetic absorbing material layer 32 can be on the micrometer scale, for example, it can be tens of micrometers.

[0059] The principle behind the improved anti-interference performance of this application is explained in detail below.

[0060] See also Figure 1 and Figure 2 The scenario is illustrated. The inventors discovered that, in electrostatic discharge (ESD) scenarios, the core mechanism by which common-mode current interferes with electronic devices is that a common-mode current, which is alternating current, flows through the flexible circuit board. This common-mode current causes the electronic device to generate a significant interference voltage. Reducing this common-mode current can lower the interference voltage caused by ESD.

[0061] Therefore, the inventive concept of this application lies in constructing sufficient inductive reactance so that the flexible circuit board structure has a strong resistance to common-mode current in the form of alternating current. Therefore, this application adds a magnetic absorbing material layer to at least one surface of the flexible circuit board structure; for example, a first magnetic absorbing material layer 32 is added to the first surface. The mechanism of action lies in the complex relative permeability μ... r This can also be simply referred to as complex permeability or composite permeability. Composite permeability can be expressed by the following formula:

[0062] μ r =μ r (f) ’ -jμ r (f)(1)

[0063] The real part μ in equation (1) r (f) ’ μ is the real relative permeability, a function of the electrostatic discharge current frequency f. The imaginary part is μ. r (f) is the index of various magnetic losses.

[0064] The inductive reactance jωL generated by the introduced first magnetic absorbing material layer 32 bead It can be expressed as follows:

[0065] jωL bead =jωμ0μ r L bead K=jωμ0(μ r (f) ’ -jμr (f))L bead K=ωμ r (f)μ0K+jωμ r (f) ’ μ0K(2)

[0066] ωμ in equation (2) r The term “(f)μ0K” can be equivalent to R(f), which exhibits the characteristics of resistance. The jωμ in equation (2) r (f) ’ The μ0K term can be equivalent to L(f), which means it exhibits inductive characteristics.

[0067] The superposition of inductive and resistive characteristics gives the first magnetic absorbing material layer 32 a choking effect. When there is a common-mode current caused by electrostatic discharge, the first magnetic absorbing material layer 32 uses the heat dissipation generated by the high-frequency common-mode current to suppress the high-frequency common-mode current, thereby reducing the interference voltage generated by the common-mode current.

[0068] Furthermore, the first magnetic absorbing material layer 32 only needs to be fixed to both ends of the flexible circuit board body 31 to achieve coverage. For example, the first magnetic absorbing material layer 32 can be fixed to both ends of the flexible circuit board body 31 with glue 33. The first magnetic absorbing material layer 32 does not need to be completely adhered to the surface of the flexible circuit board body 31. This allows an air gap 34 to exist between the first magnetic absorbing material layer 32 and the flexible circuit board body 31 in the bending area of ​​the flexible circuit board body 31. Therefore, the impact on the flexible circuit board structure is small, and the bending resistance of the flexible circuit board body 31 is basically unaffected. The bending area of ​​the flexible circuit board body 31 can still be bent normally.

[0069] Understandable Figure 3 The air gap 34 is provided for ease of understanding only and does not constitute a limitation on the technical solution of this application. In practical applications, due to the different degrees of bending of the first magnetic absorbing material layer 32 and the flexible circuit board body 31, the air gap 34 may not be uniformly distributed, and there may be situations where the first magnetic absorbing material layer 32 and the flexible circuit board body 31 are in direct contact in non-fixed areas. For example, in the bending area of ​​the circuit board body 31, the first magnetic absorbing material layer 32 and the flexible circuit board body 31 may be in contact.

[0070] Furthermore, this solution has a simple structure, requiring only the addition of a first magnetic absorbing material layer 32, resulting in low hardware costs. It also does not impose specific limitations on the circuit board body 31 or its application environment. The first magnetic absorbing material layer 32 can be a flexible layer, meaning it is easily bent. The thickness of the first magnetic absorbing material layer 32 can be as thin as micrometers (μm), thus requiring virtually no additional layout space and having almost no impact on the layout of circuit components inside the electronic device.

[0071] In one possible implementation, the area of ​​the first magnetic absorbing material layer can be larger than the surface area of ​​the first surface of the flexible circuit board body. In this case, because the area of ​​the magnetic absorbing material layer is larger, when the bendable area of ​​the flexible circuit board body is bent, the magnetic absorbing material layer will not restrict the flexible circuit board body, thus ensuring the bending resistance of the flexible circuit board itself as much as possible.

[0072] The specific structure of the flexible circuit board body 31 is not limited in this application embodiment. The flexible circuit board body 31 can be a single-sided board, a double-sided board, a single-sided board formed from a substrate, a double-sided board formed from a substrate, or a multilayer board, etc.

[0073] Other implementation methods for flexible circuit board structures are described below.

[0074] See Figure 4 The figure is a schematic diagram of another flexible circuit board structure provided in this application.

[0075] The flexible circuit board structure includes: a flexible circuit board body 31, a first magnetic absorbing material layer 32, and a first magnetic absorbing material layer 35.

[0076] The first magnetic absorbing material layer 32 covers the first surface of the flexible circuit board body 31; the second magnetic absorbing material layer 35 covers the second surface of the flexible circuit board body 31.

[0077] Specifically, the first side of the first magnetic absorbing material layer 32 is fixed to the first side of the flexible circuit board body 31 on the first surface, and the second side of the first magnetic absorbing material layer 32 is fixed to the second side of the flexible circuit board body 31 on the first surface.

[0078] The first side of the second magnetic absorbing material layer 35 is fixed to the first side of the flexible circuit board body 31 on the second surface, and the second side of the second magnetic absorbing material layer 35 is fixed to the second side of the flexible circuit board body 31 on the second surface.

[0079] The area of ​​the first magnetic absorbing material layer 32 can be greater than, less than, or equal to the area of ​​the first surface of the flexible circuit board body 31. In practical applications, in order to improve anti-interference characteristics, the area of ​​the first magnetic absorbing material layer 32 is generally greater than the area of ​​the first surface of the flexible circuit board body 31, or the two areas are basically the same.

[0080] The area of ​​the second magnetic absorbing material layer 35 can be greater than, less than, or equal to the area of ​​the second surface of the flexible circuit board body 31. In practical applications, in order to improve anti-interference characteristics, the area of ​​the second magnetic absorbing material layer 35 is generally greater than the area of ​​the second surface of the flexible circuit board body 31, or the two areas are basically the same.

[0081] The areas of the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 can be the same or different; this embodiment does not impose specific limitations. In practical applications, because the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 are respectively disposed on different surfaces, different surfaces of the flexible circuit board body 31 may have different layout constraints. Figure 1 For example, the lower surface of a flexible circuit board may need to be connected to a connector, so the area of ​​the magnetic absorbing material layer covering the lower surface may be smaller than the area of ​​the magnetic absorbing material layer covering the upper surface.

[0082] The first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 can be made of the same material and have the same thickness.

[0083] The first side and the second side of the flexible circuit board body 31 are located in the non-bending area of ​​the flexible circuit board body 31, that is, they are generally located near the signal input end and the signal output end of the flexible circuit board body 31.

[0084] The bending area of ​​the flexible circuit board body 31 can be bent to adapt to the layout.

[0085] This embodiment of the application utilizes the non-bending area of ​​the flexible circuit board body 31 for fixation, avoiding the impact on the bending area of ​​the flexible circuit board body 31, so that the flexible circuit board body still has good bending resistance and can still be bent normally.

[0086] In this embodiment, the working principle of the second magnetic absorbing material layer 35 is similar to that of the first magnetic absorbing material layer 32, as can be found in the relevant descriptions of equations (1) and (2) above. When there is a common-mode current caused by electrostatic discharge, the second magnetic absorbing material layer 35 can exhibit the impedance characteristics of an inductor in series with a resistor, using the heat dissipation generated by the high-frequency common-mode current to suppress the high-frequency common-mode current, thereby reducing the interference voltage generated by the common-mode current.

[0087] When the flexible circuit board structure is simultaneously provided with a first magnetic absorbing material layer 32 and a second magnetic absorbing material layer 35, the equivalent inductance and capacitance of the two magnetic absorbing material layers are superimposed, which increases the ability to suppress common-mode current and improves the anti-interference characteristics of the flexible circuit board structure.

[0088] In one possible implementation, the first magnetic absorbing material layer 32 is fixed to the first surface of the flexible circuit board body 31 by adhesive 33, and the second magnetic absorbing material layer 35 is fixed to the second surface by adhesive 33. This implementation is relatively simple, requires no complex fixing structure, and is easy to implement.

[0089] In one possible implementation, the area of ​​the first magnetic absorbing material layer 32 can be larger than the surface area of ​​the first surface of the flexible circuit board body 31, and the area of ​​the second magnetic absorbing material layer 35 can be larger than the surface area of ​​the second surface of the flexible circuit board body 31. When the bendable area of ​​the flexible circuit board body is bent, the upper and lower magnetic absorbing material layers will not restrict the flexible circuit board body, thus ensuring the bending resistance of the flexible circuit board itself as much as possible.

[0090] The technical effects of the proposed solution are illustrated below with specific simulation results.

[0091] See Figure 5 The figure is a schematic diagram of the magnetic permeability characteristics provided in an embodiment of this application.

[0092] The relationship between the magnetic permeability characteristics of the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 and the frequency during simulation testing is shown in the following curves. Figure 5 As shown.

[0093] See also Figure 6 and Figure 7 ,in Figure 6 This is a schematic diagram of simulation test results without using the solution proposed in this application; Figure 7 This is a schematic diagram of the simulation test results after using the solution proposed in this application.

[0094] like Figure 6 As shown, the peak value of the interference voltage caused by the common-mode current during electrostatic discharge of a conventional flexible circuit board is approximately 0.10915797V.

[0095] In this embodiment of the application, the thickness of the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 is 40 μm as an example. Figure 7As shown, after adopting the solution of this application, the peak value of the interference voltage caused by the common-mode current is approximately 0.083884761V, which represents a decrease of approximately 23.2% compared to the original interference voltage. By appropriately increasing the thickness of the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35, the voltage reduction can be further improved.

[0096] Therefore, by covering the surface of the flexible circuit board with a magnetic absorbing material layer, the anti-interference capability of the flexible circuit board can be effectively improved.

[0097] In some scenarios, the length of the flexible circuit board body may be relatively long. In this case, the anti-interference characteristics of the flexible circuit board structure can be ensured by appropriately increasing the adhesion between the magnetic absorbing material layer and the flexible circuit board body. The following is a detailed explanation with reference to the attached figures.

[0098] See Figure 8 This figure is a schematic diagram of another flexible circuit board structure provided in an embodiment of this application.

[0099] Figure 8 The flexible circuit board structure shown is similar to Figure 4 The difference lies in the fact that, in the bending region of the first surface, there are one or more fixing points 37 between the first magnetic absorbing material layer 32 and the flexible circuit board body 31. Figure 8 The implementation is only shown with one fixed point; in the bending region of the second surface, one or more fixed points 37 are included between the second magnetic absorbing material layer 35 and the flexible circuit board body 31. Figure 8 The diagram only illustrates the implementation when there is only one fixed point.

[0100] The embodiments of this application do not specifically limit the first number of fixing points between the first magnetic absorbing material layer 32 and the flexible circuit board body 31, and the second number of fixing points between the second magnetic absorbing material layer 35 and the flexible circuit board body 31, and the first number and the second number can be the same or different.

[0101] In this implementation, by adding a certain number of fixing points between the magnetic absorbing material layer and the flexible circuit board body, the adhesion between the magnetic absorbing material layer and the flexible circuit board body is increased, thereby improving the anti-interference characteristics of the electronic device. Furthermore, by using fixing points instead of large-area adhesion, the impact on the flexible circuit board body can be minimized while increasing the adhesion, allowing the flexible circuit board body to still possess good bending resistance and remain bendable.

[0102] In addition, in some other possible implementations, a fixing point may be set only between the first magnetic absorbing material layer 32 and the flexible circuit board body 31, or a fixing point may be set only between the second magnetic absorbing material layer 35 and the flexible circuit board body 31. The principle is similar and will not be described in detail here.

[0103] When the first magnetic absorbing material layer 32, the second magnetic absorbing material layer 35, and the flexible circuit board body 31 are connected at the fixing point, a fixing adhesive can be used to achieve the connection. This application embodiment does not limit the specific type of fixing adhesive. The fixing adhesive and fixing adhesive 33 used at the fixing point can be the same or different fixing adhesives.

[0104] Based on the flexible circuit board structure provided in the above embodiments, this application also provides an electronic device using the flexible circuit board structure. The electronic device in this application may include mobile phones, tablets, personal computers, workstations, large-screen devices (e.g., smart screens, smart TVs, etc.), wearable electronic devices (e.g., smartwatches, head-mounted displays), handheld game consoles, home game consoles, virtual reality (VR) devices, augmented reality (AR) devices, mixed reality devices, in-vehicle intelligent terminals, autonomous vehicles, customer-premises equipment (CPE), etc.

[0105] The following description, in conjunction with the accompanying drawings, illustrates specific scenarios in which this flexible circuit board structure is applied in electronic devices.

[0106] See Figure 9 This figure is a schematic diagram of a scenario provided in an embodiment of this application. Figure 3 .

[0107] exist Figure 9 In the scenario shown, the electronic device is an electronic device that includes a camera module, such as a mobile phone or tablet computer.

[0108] The camera module of the electronic device is used to realize the photo-taking function. The lens 11 of the camera module is used to generate an optical image and project it onto a photosensitive element 13. The photosensitive element can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor. The photosensitive element 13 converts the optical signal into an electrical signal, and then transmits the electrical signal to the ISP (not shown in the figure) through the flexible circuit board structure of this application to convert it into a digital image signal.

[0109] Figure 9Taking a flexible circuit board structure comprising a first magnetic absorbing material layer 32, a flexible circuit board body 31, and a second magnetic absorbing material layer 35 as an example. In this scenario, the first side 41 and the second side 42 of the flexible circuit board body 31 are located in the non-bending area of ​​the flexible circuit board body 31. The non-bending area is mainly used to realize the connection and fixation function of the flexible circuit board structure. Specifically, the first side 41 is used to connect with the substrate of the photosensitive element 13 to obtain the electrical signal output by the photosensitive element 13. The second side 42 is used to connect to the board-to-board connector 15 on other circuit boards. For example, in some possible implementations, the ISP is set on the motherboard, and the second side 42 of the flexible circuit board body 31 is used to connect to the board-to-board connector 15 on the motherboard.

[0110] The first side 41 and the second side 42 of the flexible circuit board body 31 are also used to realize the connection with the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35.

[0111] As for the bending area of ​​the flexible circuit board body 31, it does not need to be bonded and fixed with the upper and lower magnetic absorbing material layers. That is, the magnetic absorbing material layers will not restrict the bending area of ​​the circuit board body 31, and will not affect the bending resistance of the bending area of ​​the circuit board body 31.

[0112] When electrostatic discharge occurs, the common-mode current caused by the electrostatic discharge is alternating current. At this time, the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 exhibit the impedance characteristics of resistor in series with inductor, which can suppress high-frequency common-mode current and reduce the interference voltage generated by the common-mode current, thus avoiding the impact of electrostatic discharge on the camera function of electronic devices.

[0113] The following describes another scenario in which this flexible circuit board structure is used in electronic devices.

[0114] Electronic devices that support fingerprint recognition, such as mobile phones and tablets, are used as an example below.

[0115] See Figure 10 This figure is a schematic diagram of a scenario provided in an embodiment of this application. Figure 4 .

[0116] exist Figure 10 In the scenario shown, the flexible circuit board structure includes a first magnetic absorbing material layer 32, a flexible circuit board body 31, and a second magnetic absorbing material layer 35. In this scenario, the first side 41 and the second side 42 of the flexible circuit board body 31 are located in the non-bending area of ​​the flexible circuit board body 31. The non-bending area is mainly used to realize the connection and fixation function of the flexible circuit board structure.

[0117] The first side 41 of the flexible circuit board body 31 is used to connect with the fingerprint sensor 21 to obtain the detection signal output by the fingerprint sensor 21. In another possible implementation, the first side 41 of the flexible circuit board body 31 can also be used to connect with the substrate of the fingerprint sensor 21.

[0118] The second side 42 of the flexible circuit board body 31 is used to connect to board-to-board connectors 23 on other circuit boards. For example, in some possible implementations, the processor used to process the detection data of the fingerprint sensor 21 is an application processor 24, which is located on the motherboard 25. In this case, the second side 42 of the flexible circuit board body 31 is used to connect to the board-to-board connectors 23 on the motherboard 25. The first side 41 and the second side 42 of the flexible circuit board body 31 are also used to connect to the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35.

[0119] For the bending area of ​​the flexible circuit board body 31, it is not necessary to bond and fix it with the upper and lower magnetic absorbing material layers. That is, the magnetic absorbing material layers will not restrict the bending area of ​​the circuit board body 31, and will not affect the bending resistance of the bending area of ​​the circuit board body 31.

[0120] When electrostatic discharge occurs, the first magnetic absorbing material layer 32 and the second magnetic absorbing material layer 35 exhibit impedance characteristics of resistance in series with inductance, which can suppress high-frequency common-mode current, thereby reducing the interference voltage generated by the common-mode current and avoiding the impact of electrostatic discharge on the fingerprint recognition function of electronic devices.

[0121] The above Figure 10 In this example, we will only use the under-display fingerprint recognition method as an example. Another possible implementation is a side-button fingerprint recognition method, where the fingerprint sensor is integrated with the side button. In this case, the flexible circuit board structure is used to connect the side-mounted fingerprint sensor to the board-to-board connector on the circuit board. Yet another possible implementation is a rear-cover fingerprint recognition method, where the fingerprint detection area is located on the back cover of the electronic device. In this case, the flexible circuit board structure is used to connect the rear-cover fingerprint sensor to the board-to-board connector on the circuit board. Regardless of the fingerprint recognition implementation method used, the working principle of the flexible circuit board structure is similar to that described in the above embodiments, and will not be repeated here.

[0122] The above embodiments only illustrate the electrostatic discharge scenario. In practical applications, common-mode current interference may occur in electronic devices due to other reasons, such as antenna interference, wired charging, and wireless charging. In these scenarios, if data transmission using flexible circuit boards is involved, the flexible circuit board can be replaced with the flexible circuit board structure provided in this application embodiment to improve the electronic device's resistance to common-mode current and minimize the impact on the bending resistance of the circuit board body while ensuring that the performance of the electronic device is not affected.

[0123] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items.

[0124] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A flexible circuit board structure, characterized in that, The flexible circuit board structure includes: a flexible circuit board body and a first magnetic wave-absorbing material layer; The first magnetic absorbing material layer covers the first surface of the flexible circuit board body, and the first magnetic absorbing material layer is used to suppress common mode current. The first side of the first magnetic absorbing material layer is fixed to the first side of the flexible circuit board body on the first surface, and the second side of the first magnetic absorbing material layer is fixed to the second side of the flexible circuit board body on the first surface.

2. The flexible circuit board structure according to claim 1, characterized in that, The flexible circuit board structure also includes a second magnetic wave-absorbing material layer; The second magnetic absorbing material layer covers the second surface of the flexible circuit board body, and the second magnetic absorbing material layer is used to suppress common mode current; The first side of the second magnetic absorbing material layer is fixed to the first side of the flexible circuit board body on the second surface, and the second side of the second magnetic absorbing material layer is fixed to the second side of the flexible circuit board body on the second surface.

3. The flexible circuit board structure according to claim 1 or 2, characterized in that, The first side and the second side of the flexible circuit board body are located in the non-bending area of ​​the flexible circuit board body.

4. The flexible circuit board structure according to claim 2, characterized in that, The first magnetic absorbing material layer and the second magnetic absorbing material layer are made of one or more of the following materials: Permalloy, carbonyl iron, silicon aluminum iron, or graphene composite materials.

5. The flexible circuit board structure according to claim 2, characterized in that, The area of ​​the first magnetic absorbing material layer is greater than the area of ​​the first surface, and / or the area of ​​the second magnetic absorbing material layer is greater than the area of ​​the second surface.

6. The flexible circuit board structure according to claim 2, characterized in that, The first magnetic absorbing material layer is fixed to the first surface by a fixing adhesive, and the second magnetic absorbing material layer is fixed to the second surface by the fixing adhesive.

7. The flexible circuit board structure according to claim 2, characterized in that, In the bending region of the first surface, one or more fixing points are included between the first magnetic absorbing material layer and the flexible circuit board body, and / or, in the bending region of the second surface, one or more fixing points are included between the second magnetic absorbing material layer and the flexible circuit board body.

8. An electronic device, characterized in that, The electronic device includes at least one flexible circuit board structure as described in any one of claims 1-7.

9. The electronic device according to claim 8, characterized in that, The electronic device includes at least the following flexible circuit board structure: a first flexible circuit board structure; The first flexible circuit board structure is used to transmit the output signal of the photosensitive element of the electronic device.

10. The electronic device according to claim 8, characterized in that, The electronic device includes at least the following flexible circuit board structure: a second flexible circuit board structure; The second flexible circuit board structure is used to transmit the output signal of the fingerprint sensor of the electronic device.

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