Flexible circuit board structure and electronic device

Abstract

A flexible circuit board structure and an electronic device, relating 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 a first surface of the flexible circuit board body, and the first magnetic wave-absorbing material layer is used for suppressing a common-mode current; a first side of the first magnetic wave-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 wave-absorbing material layer is fixed to a second side of the flexible circuit board body on the first surface. When an EMC problem occurs, for example, when an electrostatic discharge phenomenon occurs, the first magnetic wave-absorbing material layer can present the impedance characteristic of a current in series-connected inductors, and the common-mode current is an alternating current, so that the magnitude of the common-mode current can be reduced, and an interference voltage is further 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

Flexible circuit board structure and electronic device

[0001] The present application claims priority to the Chinese patent application No. 202410462906.9, filed on April 16, 2024, and entitled "Flexible circuit board structure and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of terminals, and in particular to a flexible circuit board structure and an electronic device. BACKGROUND

[0003] Due to the advantages of light weight, thin thickness and strong bending resistance, flexible printed circuits (FPCs) are widely used in various electronic devices to realize flexible electrical connection between circuit boards or between circuit boards and devices.

[0004] In electronic devices, it is generally required that the electronic devices can ensure normal operation when facing strong common mode interference. However, when electromagnetic compatibility (EMC) problems occur, the common mode current flowing through the FPC will affect the normal operation of the electronic device.

[0005] Therefore, there is a need for a flexible circuit board structure with strong common mode interference resistance. SUMMARY

[0006] To solve the above problems, the present application provides a flexible circuit board structure and an electronic device, which reduces the common mode interference received by the flexible circuit board, thereby improving the anti-interference characteristics of the electronic device, and also ensures the bending resistance of the flexible circuit board as much as possible.

[0007] In a first aspect, the present application provides a flexible circuit board structure, which includes a flexible circuit board body and a first magnetic wave-absorbing material layer. The first magnetic wave-absorbing material layer covers a first surface of the flexible circuit board body, and the first magnetic wave-absorbing material layer is used to suppress common mode current. A first side of the first magnetic wave-absorbing material layer is fixed with a first side of the flexible circuit board body at the first surface, and a second side of the first magnetic wave-absorbing material layer is fixed with a second side of the flexible circuit board body at the first surface.

[0008] In the implementation, the first magnetic wave-absorbing material layer is covered on the first surface of the flexible circuit board body. When EMC problem occurs, for example, electrostatic discharge phenomenon, the first magnetic wave-absorbing material layer can present inductive current impedance characteristics, and the common mode current is alternating current. Therefore, the first magnetic wave-absorbing material layer can reduce the size of the common mode current, thereby reducing the interference voltage, improving the anti-interference characteristics of the electronic device, and reducing the interference sensitivity of the electronic device. In addition, the first magnetic wave-absorbing material layer only needs to be fixed at both ends of the flexible circuit board body to achieve coverage, and does not need to be 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 wave-absorbing material layer and the flexible circuit board body. Therefore, the influence on the flexible circuit board architecture is small, and the flexible circuit board body still has good bending resistance and can be normally bent.

[0009] Further, the application type of the scheme is wide, and the architecture of the flexible circuit board has no requirements, and the cost is friendly, the structure is simple, and the processing is easy to realize.

[0010] In a possible implementation, the flexible circuit board structure further includes a second magnetic wave-absorbing material layer. The second magnetic wave-absorbing material layer covers the second surface of the flexible circuit board body, and the second magnetic wave-absorbing material layer is used to suppress the common mode current. The first side of the second magnetic wave-absorbing material layer is fixed with the first side of the flexible circuit board body at the second surface, and the second side of the second magnetic wave-absorbing material layer is fixed with the second side of the flexible circuit board body at the second surface.

[0011] In the implementation, the magnetic wave-absorbing material layer is arranged on both surfaces of the flexible circuit board body. When EMC problem occurs, the inductive current impedance characteristics are increased, and the anti-interference characteristics of the electronic device are further improved.

[0012] In a possible implementation, the first side of the flexible circuit board body and the second side of the flexible circuit board body are located in the non-bending area of the flexible circuit board body.

[0013] In the implementation, the non-bending area of the flexible circuit board body is used to fix the first magnetic wave-absorbing material layer and the second magnetic wave-absorbing material layer, so as to avoid the influence on the bending resistance of the flexible circuit board body as much as possible. The flexible circuit board body still has good bending resistance and can be normally bent.

[0014] In a possible implementation, the first magnetic wave-absorbing material layer and the second magnetic wave-absorbing material layer adopt one or more of the following materials: permalloy, carbonyl iron, silicon aluminum iron, or graphene composite material. The first magnetic wave-absorbing material layer and the second magnetic wave-absorbing material layer can be prepared by using the same or different materials.

[0015] In a possible implementation, the first magnetic wave-absorbing material layer is fixed to the first surface by the fixing glue, and the second magnetic wave-absorbing material layer is fixed to the second surface by the fixing glue.

[0016] In this implementation, the magnetic wave-absorbing material layer and the flexible circuit board body are fixed by the fixing glue, and the structure is simple, easy to implement, and low in cost.

[0017] In a possible implementation, one or more fixing points are included between the first magnetic wave-absorbing material layer and the flexible circuit board body in the bending area of the first surface, and / or one or more fixing points are included between the second magnetic wave-absorbing material layer and the flexible circuit board body in the bending area of the second surface.

[0018] In this implementation, by increasing the number of fixing points between the magnetic wave-absorbing material layer and the flexible circuit board body, the adhesion between the magnetic wave-absorbing material layer and the flexible circuit board body is increased, and the anti-interference performance of the electronic device is improved. In addition, by using the fixing points, the adhesion can be increased while the influence on the bending resistance of the circuit board body is minimized.

[0019] In a possible implementation, the area of the first magnetic wave-absorbing material layer can be greater than the surface area of the first surface of the flexible circuit board body, and the area of the second magnetic wave-absorbing material layer can be greater than the surface area of the second surface of the flexible circuit board body. At this time, because the area of the magnetic wave-absorbing material layer is large, when the bendable area of the flexible circuit board body is bent, the magnetic wave-absorbing material layer will not restrict the flexible circuit board body, and the bending resistance of the flexible circuit board itself is ensured as much as possible.

[0020] In a second aspect, the present application also provides an electronic device including one or more flexible circuit board structures provided by the first aspect and any one of the implementation manners of the first aspect. Because the electronic device uses the flexible circuit board structure provided by the present application, the anti-interference performance of the electronic device is improved.

[0021] In a possible implementation, 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 a 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), so that when the camera of the electronic device is affected by electrostatic discharge, the interference voltage of the electrostatic discharge can be reduced.

[0022] In a possible implementation, the electronic device at least includes the following flexible circuit board structure: a second flexible circuit board structure. The second flexible circuit board structure is configured to transmit an output signal of a 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 an application processor, so as to reduce the interference voltage of the electrostatic discharge when the fingerprint sensor of the electronic device is affected by the electrostatic discharge. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a schematic diagram of a scene according to an embodiment of the present application;

[0024] FIG. 2 is a schematic diagram of another scene according to an embodiment of the present application;

[0025] FIG. 3 is a schematic diagram of a flexible circuit board structure according to an embodiment of the present application;

[0026] FIG. 4 is a schematic diagram of another flexible circuit board structure according to an embodiment of the present application;

[0027] FIG. 5 is a schematic diagram of a magnetic permeability characteristic according to an embodiment of the present application;

[0028] FIG. 6 is a schematic diagram of simulation test results without using the scheme of the present application;

[0029] FIG. 7 is a schematic diagram of simulation test results after using the scheme of the present application;

[0030] FIG. 8 is a schematic diagram of another flexible circuit board structure according to an embodiment of the present application;

[0031] FIG. 9 is a schematic diagram of a scene according to an embodiment of the present application;

[0032] FIG. 10 is a schematic diagram of another scene according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the person skilled in the art more clearly understand the scheme of the present application, the application scenario of the technical scheme of the present application is first described below.

[0034] EMC is the study of the generation, propagation and reception of unwanted electromagnetic energy in electrical engineering, as well as the harmful effects caused by such electromagnetic energy, which includes the problem of common-mode interference. Common-mode interference is a kind of electrical interference that occurs between a signal line and its reference ground (usually the power supply ground or the ground), with the same amplitude and phase. Common-mode interference is mainly caused by external electromagnetic fields, internal electromagnetic coupling of equipment or ground potential difference. In electronic devices, common-mode interference can cause signal distortion, misoperation and performance degradation.

[0035] More common EMC problems in electronic devices occur in electrostatic discharge (ESD) scenarios and antenna interference scenarios. When EMC problems occur, the common-mode current flowing on the FPC will affect the normal operation of the electronic device. The following takes the electrostatic discharge scenario as an example for illustration.

[0036] Referring to FIG. 1, it is a schematic diagram of a scenario provided by an embodiment of the present application.

[0037] When the electronic device has a camera module, electrostatic discharge can cause the camera to be interfered, which is explained in detail below.

[0038] The electronic device generally has a decorative structure (DECO) 10 outside the lens (Lens) 11 of the camera.

[0039] The voice coil motor (VCM) is used to control the movement of the lens 11.

[0040] The object generates an optical image through the lens 11 and projects it to the photosensitive element (sensor) 13.

[0041] The photosensitive element 13 can be a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) phototransistor.

[0042] The photosensitive element 13 converts the optical signal into an electrical signal, and then transmits the electrical signal to the image signal processor (ISP) 17 through the flexible circuit board 14 to convert it into a digital image signal.

[0043] 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.

[0044] The PCB 18 can also be provided with a common-mode inductor 17, which can also be called a common-mode choke coil, which can be used to filter common-mode electromagnetic interference signals. The PCB 18 can be connected to the middle frame 19.

[0045] However, when static electricity enters the camera module from the DECO 10, a common-mode current will be generated, which will flow along the flexible circuit board 14 to the PCB 18, thereby affecting the normal operation of the ISP 17, and even possibly affecting the normal operation of other circuit components. The flow path of the common-mode current can be seen in the line ① in FIG. 1.

[0046] Referring to FIG. 2, which is a schematic diagram of a scenario provided by the embodiment of the present application.

[0047] The electronic device can be a mobile phone device, in which case the electronic device supports a fingerprint unlocking function, that is, there is a fingerprint unlocking area on the screen 20, and when a user presses the area with a finger, the fingerprint sensor 21 uses the collected fingerprint characteristics to achieve fingerprint unlocking. The fingerprint sensor 21 can be an optical fingerprint sensor, an ultrasonic sensor, a semiconductor capacitive sensor, etc., and the present application does not make specific limitations. At this time, the fingerprint sensor 21 outputs the collected data to the application processor (AP) 24 on the PCB through 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.

[0048] When electrostatic discharge occurs, the common-mode current generated will reach the PCB 25 through the flexible circuit board 22, thereby affecting the normal operation of the AP 24, and even possibly affecting the normal operation of other circuit components. At this time, the flow path of the common-mode current can be seen in line ② in FIG. 2.

[0049] In order to reduce the influence of the common-mode current on the electronic device, the present application provides a flexible circuit board structure and an electronic device. In the scheme provided by the present application, a magnetic wave-absorbing material layer is covered on the surface of the flexible circuit board body, and the high magnetic guide and high magnetic loss characteristics of the magnetic wave-absorbing material layer enable the first magnetic wave-absorbing material layer to exhibit the impedance characteristics of inductance in series with current when EMC problems occur, thereby reducing the size of the current and improving the anti-interference characteristics. Moreover, the magnetic wave-absorbing material layer only needs to be fixed at both ends of the flexible circuit board body to achieve coverage, without the need for complete adhesion to the surface of the flexible circuit board body. That is, there can be a gap between the magnetic wave-absorbing material layer and the flexible circuit board body in the bending area of the flexible circuit board body, so the influence on the flexible circuit board architecture is small, and the flexible circuit board still has good bending resistance and is still easy to bend.

[0050] The implementation mode of the scheme of the present application will be described in detail below with reference to the accompanying drawings.

[0051] Referring to FIG. 3, which is a schematic diagram of a flexible circuit board structure provided by the embodiment of the present application.

[0052] The illustrated flexible circuit board structure includes a flexible circuit board body 31 and a first magnetic wave-absorbing material layer 32.

[0053] The first magnetic wave-absorbing material layer 32 covers the first surface of the flexible circuit board body 31.

[0054] In the embodiments of the present application, the flexible circuit board body 31 includes two surfaces, namely a first surface and a second surface, and the first surface and the second surface are opposite.

[0055] The two surfaces of the flexible circuit board body 31 are generally described by the upper surface and the lower surface by those skilled in the art. 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.

[0056] The first side of the first magnetic wave-absorbing material layer 32 is fixed to the first side of the flexible circuit board body 31 at the first surface, and the second side of the first magnetic wave-absorbing material layer 32 is fixed to the second side of the flexible circuit board body 31 at the first surface.

[0057] The area of the first magnetic wave-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 actual application, in order to improve the anti-interference characteristic, the area of the first magnetic wave-absorbing material layer 32 is generally greater than the area of the first surface of the flexible circuit board body 31, or the areas are substantially the same.

[0058] The first magnetic wave-absorbing material layer 32 adopts a material with high magnetic permeability and high magnetic loss rate, including but not limited to one material or a combination of multiple materials such as permalloy alloy, carbonyl iron, FeSiAl, graphene composite material, etc.

[0059] The thickness of the first magnetic wave-absorbing material layer 32 can be microns, for example, can be tens of microns.

[0060] The principle of improving the anti-interference characteristic of the scheme of the present application is described below.

[0061] Referring to the scenarios shown in FIG. 1 and FIG. 2, the inventors have found that in the electrostatic discharge scenario, the core mechanism of the common-mode current causing interference to the electronic device is that the flexible circuit board flows through a common-mode current, the common-mode current is alternating current, and the common-mode current will cause the electronic device to generate a large interference voltage. If the common-mode current can be reduced, the interference voltage of the electrostatic discharge can be reduced.

[0062] Therefore, the inventive concept of the scheme of the present application is to construct sufficient inductive reactance, so that when the common-mode current in the form of alternating current appears, the flexible circuit board structure has strong resistance to the common-mode current. Therefore, in the present application, a magnetic wave-absorbing material layer is added to at least one surface of the flexible circuit board structure, for example, a first magnetic wave-absorbing material layer 32 is added to the first surface, and the mechanism of action is that the complex relative permeability (complex relative permeability) μ r which can also be referred to as complex permeability or composite permeability. The composite permeability can be expressed as follows:

[0063] μ r = μ r (f) - j μ r (f) (1)

[0064] The real part μ r (f)'in formula (1) is the real relative permeability, and is a function of the current frequency f of electrostatic discharge. The imaginary part μ r "(f) is the index of various magnetic losses.

[0065] The inductive reactance jωL bead generated by the first magnetic wave-absorbing material layer 32 introduced can be expressed by the following formula:

[0066] jωL bead = jωμ0μ r L bead K = jωμ0(μ r (f) - j μ r (f))L bead K = ωμ r (f) μ0K + jωμ r (f) μ0K (2)

[0067] The ωμ r "(f) μ0K term in formula (2) can be equivalent to R(f), that is, presents the characteristics of resistance. The jωμ r "(f)'μ0K term in formula (2) can be equivalent to L(f), that is, presents the characteristics of inductance.

[0068] After the superposition of the inductive characteristics and the resistance characteristics, the first magnetic wave-absorbing material layer 32 has the function of choke. When there is a common-mode current caused by electrostatic discharge, the first magnetic wave-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.

[0069] In addition, the first magnetic wave-absorbing material layer 32 only needs to be fixed with both ends of the flexible circuit board body 31 to achieve coverage, for example, the first magnetic wave-absorbing material layer 32 and the both ends of the flexible circuit board body 31 can be fixed by the glue 33, and the first magnetic wave-absorbing material layer 32 does not need to be completely attached to the surface of the flexible circuit board body 31. Therefore, there can be an air gap 34 between the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31 in the bending area of the flexible circuit board body 31, so the influence on the flexible circuit board architecture is small, and at this time the bending resistance of the flexible circuit board body 31 can be basically unaffected, and the bending area of the flexible circuit board body 31 can still be normally bent.

[0070] It can be understood that the air gap 34 in FIG. 3 is only for convenient understanding and does not constitute a limitation on the technical scheme of the present application. In actual application, affected by the different bending degrees of the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31, the air gap 34 can not be uniformly distributed, and there can be a case where the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31 are directly in contact in a non-fixed area, for example, in the bending area of the circuit board body 31, the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31 can be in contact.

[0071] Further, the scheme has a simple structure, only the first magnetic wave-absorbing material layer 32 needs to be added, the hardware cost is low, and there is no specific limitation on the circuit board body 31 and the application environment of the circuit board body 31. The first magnetic wave-absorbing material layer 32 can be a flexible layer, that is, it is also easy to bend, and the thickness of the first magnetic wave-absorbing material layer 32 can be micrometers (μm), so it basically does not need to occupy additional layout space and basically has no effect on the layout of the circuit components inside the electronic device.

[0072] In a possible implementation, the area of the above first magnetic wave-absorbing material layer can be greater than the surface area of the first surface of the flexible circuit board body. At this time, due to the large area of the magnetic wave-absorbing material layer, when the bendable area of the flexible circuit board body is bent, the magnetic wave-absorbing material layer will not bind the flexible circuit board body, and the bending resistance of the flexible circuit board itself is ensured as much as possible.

[0073] The present application embodiment does not limit the specific structure of the flexible circuit board body 31, and the flexible circuit board body 31 can be a single-sided board, a double-sided board, a substrate-generated single-sided board, a substrate-generated double-sided board, and a multi-layer board, and the like.

[0074] The other implementation modes of the flexible circuit board structure are described below.

[0075] Referring to FIG. 4, which is a schematic diagram of another flexible circuit board structure provided by the present application.

[0076] The flexible circuit board structure includes: a flexible circuit board body 31, a first magnetic wave-absorbing material layer 32, and a first magnetic wave-absorbing material layer 35.

[0077] Among them, the first magnetic wave-absorbing material layer 32 covers the first surface of the flexible circuit board body 31; the second magnetic wave-absorbing material layer 35 covers the second surface of the flexible circuit board body 31.

[0078] Specifically, the first side of the first magnetic wave-absorbing material layer 32 is fixed with the first side of the flexible circuit board body 31 at the first surface, and the second side of the first magnetic wave-absorbing material layer 32 is fixed with the second side of the flexible circuit board body 31 at the first surface.

[0079] The first side of the second magnetic wave-absorbing material layer 35 is fixed to the first side of the flexible circuit board body 31 at the second surface, and the second side of the second magnetic wave-absorbing material layer 35 is fixed to the second side of the flexible circuit board body 31 at the second surface.

[0080] The area of the first magnetic wave-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 actual applications, in order to improve the anti-interference characteristics, the area of the first magnetic wave-absorbing material layer 32 is generally greater than the area of the first surface of the flexible circuit board body 31, or the areas are substantially the same.

[0081] The area of the second magnetic wave-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 actual applications, in order to improve the anti-interference characteristics, the area of the second magnetic wave-absorbing material layer 35 is generally greater than the area of the second surface of the flexible circuit board body 31, or the areas are substantially the same.

[0082] The areas of the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 can be the same or different, and the embodiments of the present application are not limited in this regard. In actual applications, because the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 are respectively arranged on different surfaces, and different surfaces of the flexible circuit board body 31 can have different layout restrictions. For example, the lower surface of the flexible circuit board can need to be connected to a connector, and therefore the area of the magnetic wave-absorbing material layer covered on the lower surface can be smaller than the area of the magnetic wave-absorbing material layer covered on the upper surface.

[0083] The first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 can adopt the same material and the same thickness.

[0084] The first side of the flexible circuit board body 31 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, generally near the signal input end and near the signal output end of the flexible circuit board body 31.

[0085] The bending area of the flexible circuit board body 31 can be bent to adapt to the layout.

[0086] The embodiments of the present application utilize the non-bending area of the flexible circuit board body 31 for fixation, avoiding affecting 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.

[0087] In the embodiments of the present application, the second magnetic wave-absorbing material layer 35 has similar working principles as the first magnetic wave-absorbing material layer 32, and the related descriptions of the above formula (1) and formula (2) can be referred to. When the common-mode current caused by electrostatic discharge exists, the second magnetic wave-absorbing material layer 35 can exhibit the impedance characteristics of inductance in series with resistance, and the heat dissipation generated by the high-frequency common-mode current is used to suppress the high-frequency common-mode current, thereby reducing the interference voltage generated by the common-mode current.

[0088] When the flexible circuit board structure is provided with the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 at the same time, the equivalent inductance and capacitance of the two layers of magnetic wave-absorbing material layers are superimposed, the suppression ability to the common-mode current is increased, and the anti-interference characteristics of the flexible circuit board structure are improved.

[0089] In a possible implementation, the first magnetic wave-absorbing material layer 32 is fixed to the first surface of the flexible circuit board body 31 by the fixing glue 33, and the second magnetic wave-absorbing material layer 35 is fixed to the second surface by the fixing glue 33. This implementation is relatively simple, does not need a complex fixing structure, and is easy to implement.

[0090] In a possible implementation, the area of the first magnetic wave-absorbing material layer 32 can be greater than the surface area of the first surface of the flexible circuit board body 31, and the area of the second magnetic wave-absorbing material layer 35 can be greater 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 layers of magnetic wave-absorbing material layers do not constrain the flexible circuit board body, and the bendability of the flexible circuit board itself is ensured as much as possible.

[0091] The technical effects of the present application scheme will be described below in combination with specific simulation results.

[0092] Referring to FIG. 5, this is a schematic diagram of the magnetic permeability characteristics provided by the embodiments of the present application.

[0093] The relationship curve between the magnetic permeability characteristics of the materials of the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 and the frequency in the simulation test is shown in FIG. 5.

[0094] Referring to FIGS. 6 and 7, FIG. 6 is a schematic diagram of the simulation test results without using the present application scheme, and FIG. 7 is a schematic diagram of the simulation test results after using the present application scheme.

[0095] As shown in FIG. 6, the peak value of the interference voltage caused by the common-mode current when the conventional flexible circuit board is electrostatically discharged is about 0.10915797 V.

[0096] In the embodiment of the present application, the thickness of the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 is 40 μm, as shown in FIG. 7, and after the present application is adopted, the peak value of the interference voltage caused by the common-mode current is about 0.083884761 V, which is about 23.2% lower than the original interference voltage. By appropriately increasing the thickness of the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35, the voltage drop value can be further improved.

[0097] As can be seen, by adopting the scheme of the present application, the anti-interference capability of the flexible circuit board can be effectively improved by covering the surface of the flexible circuit board body with the magnetic wave-absorbing material layer.

[0098] In some scenarios, the length of the flexible circuit board body can be relatively long, and in this case, the anti-interference characteristics of the flexible circuit board structure can be ensured by appropriately increasing the bonding degree between the magnetic wave-absorbing material layer and the flexible circuit board body. The following will be described in detail with reference to the accompanying drawings.

[0099] Referring to FIG. 8, it is a schematic diagram of another flexible circuit board structure provided by the embodiment of the present application.

[0100] The difference between the flexible circuit board structure shown in FIG. 8 and that shown in FIG. 4 is that in the bending area of the first surface, the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31 include one or more fixing points 37 (only the implementation manner including one fixing point is shown in FIG. 8); and in the bending area of the second surface, the second magnetic wave-absorbing material layer 35 and the flexible circuit board body 31 include one or more fixing points 37 (only the implementation manner including one fixing point is shown in FIG. 8).

[0101] The first number of fixing points between the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31 and the second number of fixing points between the second magnetic wave-absorbing material layer 35 and the flexible circuit board body 31 are not specifically limited in the embodiment of the present application, and the first number and the second number can be the same or different.

[0102] In this implementation manner, by increasing a certain number of fixing points between the magnetic wave-absorbing material layer and the flexible circuit board body, the bonding degree between the magnetic wave-absorbing material layer and the flexible circuit board body is increased, and the anti-interference characteristics of the electronic device are improved. Moreover, by the fixing point manner instead of large-area bonding, the influence on the flexible circuit board body can be minimized while the bonding degree is increased, so that the flexible circuit board body still has good bending resistance and can still be normally bent.

[0103] In addition, in other possible implementation manners, only a fixing point can be arranged between the first magnetic wave-absorbing material layer 32 and the flexible circuit board body 31, or only a fixing point can be arranged between the second magnetic wave-absorbing material layer 35 and the flexible circuit board body 31, and the principle is similar, which will not be described here again.

[0104] When the first magnetic wave-absorbing material layer 32, the second magnetic wave-absorbing material layer 35 and the flexible circuit board body 31 are connected at the fixing point, the connection can be achieved by using fixing glue. The specific type of the fixing glue is not limited in the embodiment of the present application. The fixing glue used at the fixing point and the fixing glue 33 can be the same or different fixing glue.

[0105] Based on the flexible circuit board structure provided in the above embodiment, the embodiment of the present application further provides an electronic device using the flexible circuit board structure. The electronic device in the embodiment of the present application can include a mobile phone, a tablet computer, a personal computer, a workstation device, a large-screen device (for example, a smart screen, a smart television, etc.), a wearable electronic device (for example, a smart watch, a head-mounted display device), a palm game console, a home game console, a virtual reality (VR) device, an augmented reality (AR) device, a mixed reality device, a vehicle-mounted intelligent terminal, an autonomous vehicle, a customer-premises equipment (CPE), etc.

[0106] The scene in which the electronic device applies the flexible circuit board structure will be specifically described below with reference to the accompanying drawings.

[0107] Referring to FIG. 9, which is a schematic diagram three of the scene provided in the embodiment of the present application.

[0108] In the scene shown in FIG. 9, the electronic device is an electronic device including a camera module, for example, a mobile phone, a tablet computer, etc.

[0109] The camera module of the electronic device is used to realize the photographing function. Among them, the lens 11 of the camera module is used to generate an optical image and project it to the photosensitive element 13, which 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 the electrical signal is transmitted to the ISP (not shown in the figure) through the flexible circuit board structure of the present application to convert it into a digital image signal.

[0110] In FIG. 9, the flexible circuit board structure includes the first magnetic wave-absorbing material layer 32, the flexible circuit board body 31, and the second magnetic wave-absorbing material layer 35. In this scenario, the first side 41 and the second side 42 of the flexible circuit board body 31 are in the non-bending area of the flexible circuit board body 31, which is mainly used to realize the connection and fixing 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 the board-to-board connector 15 on the other circuit board. For example, in some possible implementation manners, the ISP is arranged on the mainboard, and the second side 42 of the flexible circuit board body 31 is used to connect the board-to-board connector 15 on the mainboard.

[0111] 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 wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35.

[0112] As for the bending area of the flexible circuit board body 31, it can not be fixed with the upper and lower magnetic wave-absorbing material layers. That is, the magnetic wave-absorbing material layer basically does not constrain the bending area of the circuit board body 31 and basically does not affect the bending resistance of the bending area of the circuit board body 31.

[0113] When static electricity is discharged, the common-mode current caused by the static electricity is an alternating current. At this time, the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 present the impedance characteristics of resistance in series with inductance, which can suppress the high-frequency common-mode current, thereby reducing the interference voltage generated by the common-mode current, and avoiding the influence of the static electricity on the photographing function of the electronic device.

[0114] Another scenario in which the flexible circuit board structure is applied to the electronic device will be described below.

[0115] The electronic device is an electronic device supporting a fingerprint recognition function, for example, a mobile phone, a tablet computer, or the like. A mobile phone device will be taken as an example for description.

[0116] Referring to FIG. 10, which is a schematic diagram four of a scenario provided by an embodiment of the present application.

[0117] In the scenario shown in FIG. 10, the flexible circuit board structure includes the first magnetic wave-absorbing material layer 32, the flexible circuit board body 31, and the second magnetic wave-absorbing material layer 35. In this scenario, the first side 41 and the second side 42 of the flexible circuit board body 31 are in the non-bending area of the flexible circuit board body 31, which is mainly used to realize the connection and fixing function of the flexible circuit board structure.

[0118] The first side 41 of the flexible circuit board body 31 is used to connect 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 the substrate of the fingerprint sensor 21.

[0119] The second side 42 of the flexible circuit board body 31 is used to connect the board-to-board connector 23 on the other circuit board. For example, in some possible implementations, the processor used to process the detection data of the fingerprint sensor 21 is an application processor 24, and the application processor 24 is arranged on a mainboard 25. Therefore, the second side 42 of the flexible circuit board body 31 is used to connect the board-to-board connector 23 on the mainboard 25. 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 wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35.

[0120] For the bending area of the flexible circuit board body 31, the upper and lower magnetic wave-absorbing material layers can not be attached and fixed. That is, the magnetic wave-absorbing material layers basically do not constrain the bending area of the circuit board body 31 and basically do not affect the bending resistance of the bending area of the circuit board body 31.

[0121] When electrostatic discharge occurs, the first magnetic wave-absorbing material layer 32 and the second magnetic wave-absorbing material layer 35 exhibit the impedance characteristics of resistance in series with inductance, can inhibit high-frequency common-mode current, and further can reduce the interference voltage generated by the common-mode current, thereby avoiding the influence of electrostatic discharge on the fingerprint recognition function of the electronic device.

[0122] In the above FIG. 10, only the implementation of under-screen fingerprint recognition is taken as an example for description. In another possible implementation, the side key fingerprint recognition mode can also be used, that is, the fingerprint sensor is integrated with the side key. At this time, the flexible circuit board structure is used to connect the fingerprint sensor at the side and the board-to-board connector on the circuit board. In another possible implementation, the rear cover fingerprint recognition mode can also be used, that is, the fingerprint detection area is located on the rear cover of the electronic device. At this time, the flexible circuit board structure is used to connect the fingerprint sensor at the rear cover and the board-to-board connector on the circuit board. However, no matter which implementation of the fingerprint recognition is used, the working principle of the flexible circuit board structure is similar to the description in the above embodiments, and thus will not be described herein again.

[0123] In the above embodiments, only the electrostatic discharge scenario is taken as an example for description. In actual application, the common-mode current interference can also occur on the electronic device due to other reasons, such as an antenna interference scenario, a wired charging scenario, a wireless charging scenario, and the like. In these scenarios, if the flexible circuit board is used to transmit data, the flexible circuit board can be replaced with the flexible circuit board structure provided in the embodiments of the present application to improve the resistance of the electronic device to the common-mode current, and to reduce the influence on the bending resistance of the circuit board body as much as possible while ensuring that the performance of the electronic device is not affected.

[0124] It should be understood that, in the present application, “at least one” refers to one or more, and “multiple” refers to two or more. “And / or” is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, “A and / or B” can represent three cases: only A exists, only B exists, and A and B exist at the same time, wherein A and B can be singular or plural. The character “ / ” generally represents that the associated objects before and after it are in an “or” relationship. “At least one of the following” or the like means any combination of these items, including any combination of single or multiple items.

[0125] The above and the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A flexible circuit board structure, characterized by, 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 a first surface of the flexible circuit board body, and the first magnetic wave-absorbing material layer is used for suppressing common-mode current; A first side of the first magnetic wave-absorbing material layer is fixed with a first side of the flexible circuit board body at the first surface, and a second side of the first magnetic wave-absorbing material layer is fixed with a second side of the flexible circuit board body at the first surface.

2. The flexible circuit board structure of claim 1, wherein, The flexible circuit board structure further comprises a second magnetic wave-absorbing material layer; The second magnetic wave-absorbing material layer covers a second surface of the flexible circuit board body, and the second magnetic wave-absorbing material layer is used for suppressing common-mode current; A first side of the second magnetic wave-absorbing material layer is fixed with a first side of the flexible circuit board body at the second surface, and a second side of the second magnetic wave-absorbing material layer is fixed with a second side of the flexible circuit board body at the second surface.

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

4. The flexible circuit board structure of claim 2, wherein, The first magnetic wave-absorbing material layer and the second magnetic wave-absorbing material layer adopt one or more of the following materials: Permalloy, carbonyl iron, silicon aluminum iron, or graphene composite material.

5. The flexible circuit board structure of claim 2, wherein, An area of the first magnetic wave-absorbing material layer is greater than an area of the first surface, and / or an area of the second magnetic wave-absorbing material layer is greater than an area of the second surface.

6. The flexible circuit board structure of claim 2, wherein, The first magnetic wave-absorbing material layer is fixed with the first surface through fixing glue, and the second magnetic wave-absorbing material layer is fixed with the second surface through the fixing glue.

7. The flexible circuit board structure of claim 2, wherein, In a bending area of the first surface, one or more fixing points are included between the first magnetic wave-absorbing material layer and the flexible circuit board body, and / or in a bending area of the second surface, one or more fixing points are included between the second magnetic wave-absorbing material layer and the flexible circuit board body.

8. An electronic device, comprising: The electronic device comprises at least one flexible circuit board structure according to any one of claims 1-7.

9. The electronic device of claim 8, wherein, The electronic device comprises at least the following flexible circuit board structure: a first flexible circuit board structure; The first flexible circuit board structure is used for transmitting an output signal of a photosensitive element of the electronic device.

10. The electronic device of claim 8, wherein, The electronic device comprises at least the following flexible circuit board structure: a second flexible circuit board structure; The second flexible circuit board structure is used for transmitting an output signal of a fingerprint sensor of the electronic device.

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