Electronic device

Abstract

The utility model provides a flexible circuit board, a display module and electronic equipment. The flexible circuit board comprises a substrate, a reference ground layer and a signal layer, wherein the substrate comprises a first surface and a second surface which are arranged back to back; the reference ground layer is arranged on the first surface of the substrate, and the reference ground layer comprises a plurality of reference ground wires; the signal layer is arranged on the second surface of the substrate, the signal layer comprises a plurality of signal lines, the signal lines are arranged at intervals, the orthographic projection of each signal line on the substrate is partially covered by the orthographic projection of the reference ground lines on the substrate, or the orthographic projection of each signal line on the substrate is partially covered by the orthographic projection of the reference ground lines on the substrate. The orthographic projection of each signal line on the substrate is completely covered by the orthographic projection of one reference ground line on the substrate. According to the technical scheme, the shielding performance of the flexible circuit board can be optimized on the basis of ensuring that the flexible circuit board has good working performance.

Description

[0001] This application is a divisional application for the Chinese patent application with application number 202223600477.2, application date December 30, 2022, and invention name "Flexible circuit board, display module and electronic device". Technical Field

[0002] The present application relates to the technical field of circuit boards, and in particular to a flexible circuit board, a display module and an electronic device. Background Art

[0003] In electronic devices, interference refers to the high-frequency noise generated by the operation of high-speed electronic devices inside the device. When it falls into the communication frequency band, it will affect the receiving sensitivity of the device, resulting in deterioration of wireless performance. At present, flexible circuit boards are one of the components that are most likely to cause interference problems in electronic devices. How to achieve better shielding performance of flexible circuit boards while meeting the working performance of flexible circuit boards is a topic that the industry continues to explore. Utility Model Content

[0004] The embodiments of the present application provide a flexible circuit board, a display module and an electronic device, which can optimize the shielding performance of the flexible circuit board while ensuring that the flexible circuit board has good working performance.

[0005] In a first aspect, the present application provides a flexible circuit board, the flexible circuit board comprising:

[0006] A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other;

[0007] A reference ground layer, the reference ground layer is disposed on the first surface of the substrate, the reference ground layer includes a plurality of reference ground lines; and

[0008] A signal layer, wherein the signal layer is disposed on the second surface of the substrate, the signal layer comprises a plurality of signal lines, the plurality of signal lines are arranged at intervals, and the orthographic projection of each of the signal lines on the substrate is partially covered by the orthographic projection of the plurality of reference ground lines on the substrate, or the orthographic projection of each of the signal lines on the substrate is completely covered by the orthographic projection of a reference ground line on the substrate.

[0009] Therefore, in the height direction of the flexible circuit board, each signal line in the signal layer can have a certain overlap with multiple reference ground lines, so as to utilize the shielding effect of the reference ground layer and shield the signal lines in the signal layer from noise, thereby achieving good reliability. Alternatively, in the height direction of the flexible circuit board, each reference ground line can be set directly above one or more signal lines, thereby achieving a good shielding effect on the strongest radiation part of the signal line. In this way, the external interference of the flexible circuit board can be reduced without increasing the cost and affecting the flexibility and reliability of the flexible circuit board, thereby improving the wireless performance of the electronic equipment.

[0010] In one possible implementation, a plurality of the reference ground lines are cross-arranged to form a plurality of grids, the ratio of the width of the reference ground line to the width of the grid is 1:3, the width of the reference ground line is less than or equal to 0.1 mm, and the width of the grid is less than or equal to 0.3 mm.

[0011] It can be understood that by setting the reference ground layer as a grid copper structure, the reference ground layer can have good flexibility on the basis of realizing the shielding effect of the reference ground layer on the signal layer, so as to adapt to the bending requirements of the flexible circuit board and have good reliability.

[0012] In one possible implementation, a plurality of the reference ground lines are cross-arranged to form a plurality of grids, the ratio of the width of the reference ground line to the width of the grid is 1:5, the width of the reference ground line is less than or equal to 0.1 mm, and the width of the grid is less than or equal to 0.5 mm.

[0013] It can be understood that by setting the reference ground layer as a grid copper structure, the reference ground layer can have good flexibility on the basis of realizing the shielding effect of the reference ground layer on the signal layer, so as to adapt to the bending requirements of the flexible circuit board and have good reliability.

[0014] In a possible implementation, a plurality of the reference ground lines are spaced apart along the length direction of the substrate, a plurality of the signal lines are also arranged along the length direction of the substrate, and an orthographic projection of one of the reference ground lines on the substrate covers an orthographic projection of one or more of the signal lines on the substrate.

[0015] It is understandable that in the height direction of the flexible circuit board, each reference ground line can be set directly above one or more signal lines, thereby providing a good shielding effect on the strongest radiation part of the signal line. In this way, the external interference of the flexible circuit board can be reduced and the wireless performance of the electronic device can be improved without increasing the cost and affecting the flexibility and reliability of the flexible circuit board.

[0016] In a possible implementation, the distance between the center lines of two adjacent reference ground lines is a first distance, the distance between the center lines of two adjacent signal lines is a second distance, and the first distance is less than or equal to the second distance.

[0017] Thereby, it can be ensured that the reference ground line can completely cover the signal line in the height direction of the flexible circuit board, thereby further improving the shielding performance of the reference ground layer.

[0018] In a possible implementation manner, a ratio of a width of the reference ground line to a width of the signal line is in a range of 1:2 to 5:1.

[0019] Under this setting, multiple reference ground lines can achieve shielding performance in a one-to-one correspondence manner of one reference ground line corresponding to one signal line. Alternatively, multiple reference ground lines can also achieve shielding performance in a many-to-one correspondence manner of one reference ground line corresponding to multiple signal lines, which has good reliability.

[0020] In a possible implementation manner, the flexible circuit board further includes a first shielding layer, and the first shielding layer is disposed on a side of the signal layer away from the substrate.

[0021] It is understandable that when the proportion of grid copper is large, the shielding effectiveness of the reference formation will be weakened. In order to address the problem of insufficient electromagnetic compatibility caused by the weakened shielding effectiveness, it is necessary to add a metal layer on the outside of the signal layer and the reference formation to achieve shielding effectiveness. Since the shielding effectiveness of the reference formation in this application is better, it is suitable for both large and small grid copper ratios. Therefore, it can replace the coating on the reference formation side during use, so that there is no need to set another metal shielding layer on the reference formation side, thereby achieving the effect of reducing cost, thickness and weight.

[0022] In a possible implementation, the flexible circuit board further includes a first shielding layer and a second shielding layer, wherein the first shielding layer is disposed on a side of the signal layer away from the substrate, and the second shielding layer is disposed on a side of the reference ground layer away from the substrate.

[0023] By providing the first shielding layer and the second shielding layer, the shielding performance of the flexible circuit board can be further improved, and the reliability is good.

[0024] In a second aspect, the present application further provides a display module, which includes a display screen and the flexible circuit board as described above, wherein the flexible circuit board is electrically connected to the display screen.

[0025] In a third aspect, the present application also provides an electronic device, which includes the display module as described above. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 2 is along Figure 1 The schematic cross-sectional view of the section line AA shown in FIG.

[0028] Figure 3 yes Figure 2 A structural schematic diagram of a flexible circuit board shown;

[0029] Figure 4 yes Figure 3 A schematic top view of a signal layer of a substrate shown;

[0030] Figure 5 It is a schematic diagram of the structure of the reference stratum using solid copper in the prior art;

[0031] Figure 6 yes Figure 5 The magnetic field distribution diagram of the solid copper shown;

[0032] Figure 7 It is a schematic diagram of the structure of the reference stratum using grid copper in the prior art;

[0033] Figure 8 yes Figure 7 The magnetic field distribution diagram of the grid copper shown;

[0034] Fig. 9 yes Figure 3 A schematic top view of a first embodiment of a reference layer of a substrate shown;

[0035] Fig.10 yes Figure 3 Another schematic top view of the first embodiment of the reference formation of the substrate shown;

[0036] Fig.11 yes Figure 3 Another schematic top view of the first embodiment of the reference formation of the substrate shown;

[0037] Fig.12 yes Fig. 9 The electric field distribution diagram of the reference formation shown;

[0038] Fig.13 yes Fig.10 The electric field distribution diagram of the reference formation shown;

[0039] Fig.14 yes Fig.11 The electric field distribution diagram of the reference formation shown;

[0040] Fig.15 yes Fig. 9The magnetic field distribution map of the reference formation shown;

[0041] Fig.16 yes Fig.10 The magnetic field distribution map of the reference formation shown;

[0042] Fig.17 yes Fig.11 The magnetic field distribution map of the reference formation shown;

[0043] Fig.18 yes Fig. 9 A schematic diagram showing the relative position relationship between the reference layer and the signal layer shown;

[0044] Fig.19 yes Figure 3 A schematic top view of a second embodiment of a reference layer of a substrate shown;

[0045] Fig. 20 yes Fig.19 A schematic diagram showing the relative position relationship between the reference layer and the signal layer shown;

[0046] Fig.21 yes Fig.19 The electric field vector diagram between the reference ground layer and the signal layer is shown;

[0047] Fig. 22 yes Fig.19 The magnetic field vector diagram between the reference ground layer and the signal layer is shown;

[0048] Fig.23 yes Fig.19 Schematic diagram of electric field distribution of reference formation shown;

[0049] Fig.24 yes Fig.19 A schematic diagram of magnetic field distribution of the reference formation shown;

[0050] Fig.25 yes Figure 2 Another structural schematic diagram of the flexible circuit board shown;

[0051] Fig.26 yes Figure 2 Another structural schematic diagram of a flexible circuit board is shown. DETAILED DESCRIPTION

[0052] For ease of understanding, the terms involved in the embodiments of the present application are first explained.

[0053] And / or: It is just a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0054] Multiple: refers to two or more than two.

[0055] Connection: should be understood in a broad sense. For example, A and B are connected, which can be either direct or indirect through an intermediary.

[0056] The specific implementation of the present application will be clearly described below in conjunction with the accompanying drawings.

[0057] Embodiments of the present application provide a flexible circuit board, a display module, and an electronic device.

[0058] Among them, the electronic device can be but is not limited to smart consumer electronic devices such as mobile phones, tablet computers, and laptops, or wearable electronic devices such as augmented reality (AR), virtual reality (VR), smart watches, and smart bracelets, or vehicle-mounted devices such as car computers.

[0059] The following description will be made by taking a mobile phone as an example of the electronic device, but it should be understood that the invention is not limited thereto.

[0060] Please refer to Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the structure of an electronic device 300 provided in an embodiment of the present application, Figure 2 is along Figure 1 The cross-sectional diagram shown is a schematic diagram of the cross-section obtained by cutting along the cutting line AA.

[0061] In the embodiment of the present application, for the convenience of illustration, the length direction of the electronic device 300 is the first direction X, the width direction of the electronic device 300 is the second direction Y, and the height direction of the electronic device 300 is the third direction Z. The first direction X, the second direction Y and the third direction Z are perpendicular to each other.

[0062] The electronic device 300 may include a display module 200, a frame 210, a back cover 220, a battery 230 and a circuit board 240. The display module 200 may be used to display text, images, videos, etc. The frame 210 is a structural bearing component of the electronic device 300, and is used to install other components such as the display module 200 and the back cover 220. The display module 200 and the back cover 220 are respectively connected to the opposite sides of the frame 210. When the electronic device 300 is a mobile phone, the frame 210 is the middle frame of the mobile phone, and the display module 200 is a cover plate facing the user's face when the user holds the mobile phone. It can be used to present visual information such as images, colors, and text by setting a display screen. The back cover 220 is a cover plate facing the user's face when the user holds the mobile phone. It can be used to capture static images or dynamic videos behind the mobile phone by setting a camera module as a rear camera. Exemplarily, the material of the back cover 220 includes glass, plastic or ceramic.

[0063] The display module 200, the back cover 220 and the frame 210 cooperate to form a receiving space W for the electronic device 300. Figure 1 and Figure 2 As shown, the circuit board 240 and the battery 230 are located in the receiving space W, and the circuit board 240 and the battery 230 are located between the frame 210 and the back cover 220. The display module 200 may include a flexible printed circuit 100 (Flexible Printed Circuit, FPC) and a display screen 250. The flexible circuit board 100 may include a plurality of bending portions 1 and a plurality of non-bending portions 2, and the bending portion 1 can be bent relative to the non-bending portion 2 so that the flexible circuit board 100 as a whole presents a bent and extended structural form. One end of the flexible circuit board 100 can be electrically connected to the display screen 250, and the other end of the flexible circuit board 100 can pass through the frame 210 and be electrically connected to the device on the circuit board 240 to realize the control function of the circuit board 240 for the display screen 250.

[0064] It is understandable that in the electronic device 300, the interference problem refers to the high-frequency noise generated by the operation of the high-speed electronic devices inside the device, which will affect the receiving sensitivity of the device when it falls into the communication frequency band, resulting in deterioration of the wireless performance. In the current electronic device 300, since the display screen 250 in the display module 200 has a high refresh rate and a large area, and the flexible circuit board 100 has a long wiring, the display module 200 is one of the modules that is most likely to cause interference problems. Therefore, the embodiment of the present application can provide a flexible circuit board 100 that can optimize the shielding performance of the flexible circuit board 100 on the basis of ensuring that the flexible circuit board 100 has good working performance, which will be specifically described below.

[0065] See also Figure 3 , Figure 3 yes Figure 2A structural schematic diagram of a flexible circuit board 100 is shown. The flexible circuit board 100 may include a substrate 10, a reference ground layer 20 and a signal layer 30. Exemplarily, the substrate 10 may be a flexible substrate. The signal layer 30 may be a signal layer including a MIPI (Mobile Industry Processor Interface) differential line. The reference ground layer 20 may be a reference ground layer for the MIPI differential line, and the reference ground layer 20 may provide a shielding effect for high-frequency noise on the MIPI differential line.

[0066] The substrate 10 may include a first surface 11 and a second surface 12 disposed opposite to each other. The reference ground layer 20 is disposed on the first surface 11 of the substrate 10, and the signal layer 30 is disposed on the second surface 12 of the substrate 10. That is, the reference ground layer 20 and the signal layer 30 are disposed on opposite sides of the substrate 10, respectively, and the substrate 10, the reference ground layer 20 and the signal layer 30 may together constitute the bending portion 1 and the non-bending portion 2 of the circuit board 240.

[0067] It should be noted that the following improvements on the structures of each layer of the flexible circuit board 100 can be applied to the bending portion 1 and the non-bending portion 2 of the flexible circuit board 100 without conflict, and the embodiments of the present application do not impose strict limitations on this.

[0068] See also Figure 4 , Figure 4 yes Figure 3 Schematic diagram of a top view of the signal layer 30 of the substrate 10 shown. The signal layer 30 may include a plurality of signal lines 31 and a plurality of ground lines 32, the signal lines 31 are used to realize the signal transmission function of the flexible circuit board 100, and the ground lines 32 are used to realize the grounding and the function of spacing the signal lines 31. The plurality of signal lines 31 are arranged at intervals along the length direction of the substrate 10 (that is, the first direction X). The gap area between two adjacent signal lines 31 is used to accommodate a ground line 32. That is, the plurality of signal lines 31 arranged at intervals can form a plurality of gap areas, and the plurality of ground lines 32 are arranged in sequence in the plurality of gap areas. Exemplarily, the material of the signal line 31 and the ground line 32 may be copper.

[0069] Please refer to Figure 5 , Figure 6 , Figure 7 and Figure 8 , Figure 5 This is a schematic diagram of the structure of the reference layer 3 using solid copper in the prior art. Figure 6 yes Figure 5 The magnetic field distribution diagram of solid copper is shown in the figure. Figure 7 This is a schematic diagram of the structure of the reference layer 3 using mesh copper in the prior art. Figure 8 yes Figure 7 The magnetic field distribution of the grid copper is shown.

[0070] In the prior art, Figure 5 and Figure 6 As shown in the figure, when the reference ground plane 3 is made of solid copper, the noise shielding effect on the signal layer is better. However, in the actual use of FPC, considering that FPC needs to be bent in some areas, it is necessary to reduce the proportion of copper in the reference ground plane 3 for flexibility considerations. Figure 7 and Figure 8 As shown, the final status quo is that the reference ground 3 of FPC adopts a grid-shaped reference ground design, commonly known as "grid copper". Among them, the ratio of line width to gap is called the grid copper ratio. According to the shielding principle, the smaller the grid copper ratio is, the closer it is to real copper, and the better the shielding performance is.

[0071] The reference ground layer 20 provided in the embodiment of the present application has a better shielding effect than the mesh copper in the prior art. The structure of the reference ground layer 20 will be described in detail through two specific embodiments as follows.

[0072] First embodiment:

[0073] See also Fig. 9 , Fig. 9 yes Figure 3 A schematic top view of a first embodiment of a reference ground layer 20 of a substrate 10 is shown. The reference ground layer 20 may include a plurality of reference ground lines 21, each of which is arranged obliquely to the first direction X, and a plurality of reference ground lines 21 are arranged crosswise to form a plurality of grids 22. Among them, the intersection angle of two adjacent reference ground lines 21 can be selected according to the actual application requirements of the reference ground layer 20, and it can be any angle such as 30°, 45°, etc., and this embodiment does not impose strict restrictions on the intersection angle of two adjacent reference ground lines 21. Exemplarily, the material of the reference ground line 21 can be copper.

[0074] It can be understood that by setting the reference ground layer 20 as a grid copper structure, the reference ground layer 20 can have good flexibility on the basis of realizing the shielding effect of the reference ground layer 20 on the signal layer 30 to adapt to the bending requirements of the flexible circuit board 100 and have good reliability.

[0075] The reference ground layer 20 may further include a plurality of grounding points 23 , which are spaced apart on the plurality of reference ground lines 21 , and are used to be electrically connected to the ground lines 32 of the signal layer 30 .

[0076] In a possible implementation manner, the ratio of the width of the reference ground line 21 to the width of the grid 22 may be 1:3, the width of the reference ground line 21 is less than or equal to 0.1 mm, and the width of the grid 22 is less than or equal to 0.3 mm.

[0077] For example, please refer to Fig. 9 , Fig.10 and Fig.11 , Fig.10 yes Figure 3 Another schematic top view of the first embodiment of the reference layer 20 of the substrate 10 is shown, Fig.11 yes Figure 3 Another schematic top view of the first embodiment of the reference layer 20 of the substrate 10 is shown.

[0078] in, Fig. 9 The line width of the reference ground line 21 is shown to be 0.1 mm, and the width of the grid 22 is 0.3 mm. Fig.10 The line width of the reference ground line 21 is shown to be 0.05 mm, and the width of the grid 22 is 0.15 mm. Fig.11 The line width of the reference ground line 21 shown is 0.02 mm, and the width of the grid 22 is 0.06 mm. That is, Fig.10 The line width of the reference ground line 21 is Fig. 9 One-half of the line width of the reference ground line 21 shown, Fig.11 The line width of the reference ground line 21 is Fig. 9 The line width of the reference ground line 21 shown is one fifth.

[0079] Please refer to Fig.12 , Fig.13 and Fig.14 , Fig.12 yes Fig. 9 The electric field distribution diagram of the reference formation 20 is shown, Fig.13 yes Fig.10 The electric field distribution diagram of the reference formation 20 is shown, Fig.14 yes Fig.11 The electric field distribution diagram of the reference ground layer 20 is shown. It can be seen that when the line width of the reference ground line 21 is reduced to one-half, the radiation electric field intensity is reduced by 20dB. When the line width of the reference ground line 21 is reduced to one-fifth, the radiation electric field intensity is reduced by 40dB.

[0080] Please refer to Fig.15 , Fig.16 and Fig.17 , Fig.15 yes Fig. 9 The magnetic field distribution diagram of the reference formation 20 is shown, Fig.16 yes Fig.10 The magnetic field distribution diagram of the reference formation 20 is shown, Fig.17 yes Fig.11 The magnetic field distribution diagram of the reference formation 20 is shown.

[0081] It can be seen that when the line width of the reference ground line 21 is reduced to one-half, the radiation magnetic field intensity will be reduced. When the line width of the reference ground line 21 is reduced to one-fifth, the radiation magnetic field intensity will be further reduced.

[0082] Based on the above description, it should be understood that, under the same grid copper ratio, the line width of the reference ground line 21 can be adjusted to make the line width of the reference ground line 21 thinner, so that the grid 22 formed by the intersection of the reference ground line 21 is arranged more densely under the same board area to achieve a better shielding effect. In this way, the external interference of the flexible circuit board 100 can be reduced without increasing the cost and affecting the flexibility and reliability of the flexible circuit board 100, and the wireless performance of the electronic device 300 can be improved.

[0083] In another possible implementation, the ratio of the width of the reference ground line 21 to the width of the grid 22 may be 1:5, the width of the reference ground line 21 is less than or equal to 0.1 mm, and the width of the grid 22 is less than or equal to 0.5 mm.

[0084] It should be noted that the ratio of the width of the reference ground line 21 to the width of the grid 22 is not limited to the examples listed above. Ratios that can achieve a higher arrangement density under the same board area are all within the scope of protection requested by the embodiments of the present application and are not strictly limited.

[0085] See also Fig.18 , Fig.18 yes Fig. 9 Schematic diagram of the relative positional relationship between the reference ground layer 20 and the signal layer 30 shown. It can be seen that in the third direction Z, each signal line 31 in the signal layer 30 is partially covered by the multiple reference ground lines 21, and the part of each signal line 31 not covered by the reference ground line 21 is exposed through the grid 22. That is, the orthographic projection of each signal line 31 in the signal layer 30 on the substrate 10 is partially covered by the orthographic projection of the multiple reference ground lines 21 on the substrate 10.

[0086] Therefore, in the height direction of the flexible circuit board 100, each signal line 31 in the signal layer 30 has a certain overlapping portion with the multiple reference ground lines 21, so as to utilize the shielding effect of the reference ground layer 20 to shield the signal lines 31 in the signal layer 30 from noise, thereby achieving good reliability.

[0087] Second embodiment:

[0088] See also Fig.19 , Fig.19 yes Figure 3A schematic top view of a second embodiment of the reference ground layer 20 of the substrate 10 is shown. In this embodiment, the same contents as those of the first embodiment are not repeated, and the difference from the first embodiment is that a plurality of reference ground lines 21 are arranged at intervals along the length direction (i.e., the first direction X) of the substrate 10. In this arrangement, the plurality of reference ground lines 21 are distributed in a grid-like grid.

[0089] See also Fig. 20 , Fig. 20 yes Fig.19 Schematic diagram of the relative positional relationship between the reference ground layer 20 and the signal layer 30 shown. It can be seen that in the third direction Z, each signal line 31 in the signal layer 30 is completely covered by a reference ground line 21. In other words, the orthographic projection of each signal line 31 in the signal layer 30 on the substrate 10 is completely covered by the orthographic projection of a reference ground line 21 on the substrate 10.

[0090] It can be understood that the orthographic projection of a reference ground line 21 on the substrate 10 covers the orthographic projection of one or more signal lines 21 on the substrate 10. That is, in the height direction of the flexible circuit board 100, each reference ground line 21 can be set directly above one or more signal lines 31, thereby having a good shielding effect on the strongest radiation part of the signal line 31. In this way, the external interference of the flexible circuit board 100 can be reduced without increasing the cost and affecting the flexibility and reliability of the flexible circuit board 100, and the wireless performance of the electronic device 300 can be improved.

[0091] For more information, please refer to Fig.21 and Fig. 22 , Fig.21 yes Fig.19 The electric field vector diagram between the reference ground layer 20 and the signal layer 30 is shown in FIG. Fig. 22 yes Fig.19 The magnetic field vector diagram between the reference ground layer 20 and the signal layer 30 is shown. It can be understood that since the grid-type reference ground line 21 is set directly above the signal line 31, and the reference ground line 21 is a metal line, the skin effect of the metal prevents the area with the strongest electromagnetic field around the signal line 31 from directly radiating outward, and when the electromagnetic field goes around the two sides of the reference ground line 21 and has the conditions for external radiation, the radiation intensity has been significantly reduced, thereby achieving a good shielding effect.

[0092] Please refer to Fig.12 , Fig.15 and Fig.23 , Fig.23 yes Fig.19 The electric field distribution diagram of the reference ground layer 20 is shown. It can be seen that after the reference ground layer 20 is replaced from a grid structure to a grid structure, the external radiation electric field effect of the flexible circuit board 100 is reduced by 30dB.

[0093] Please refer to Fig.13 , Fig.16 and Fig.24 , Fig.24 yes Fig.19 A schematic diagram of the magnetic field distribution of the reference formation 20 is shown.

[0094] It can be seen that after the reference ground layer 20 is replaced from a grid structure to a grating structure, the effect of the flexible circuit board 100 on externally radiating magnetic field is reduced.

[0095] Based on the above description, it should be understood that under the same grid-to-ground ratio, using a grid structure instead of a grid structure can achieve a stronger shielding effect, and the grid structure is relatively simple, which is conducive to reducing the production cost of the flexible circuit board 100.

[0096] In a possible implementation, the ratio of the width of the reference ground line 21 to the spacing between two adjacent reference ground lines 21 may be 1:3, the width of the reference ground line 21 is less than or equal to 0.1 mm, and the spacing between two adjacent reference ground lines 21 is less than or equal to 0.3 mm.

[0097] In another possible implementation, the ratio of the width of the reference ground line 21 to the spacing between two adjacent reference ground lines 21 may be 1:5, the width of the reference ground line 21 is less than or equal to 0.1 mm, and the spacing between two adjacent reference ground lines 21 is less than or equal to 0.5 mm.

[0098] It should be noted that the ratio of the width of the reference ground line 21 to the width of two adjacent reference ground lines 21 is not limited to the examples listed above. The ratio that can achieve a larger arrangement density under the same board area is within the scope of protection requested by the embodiments of the present application and is not strictly limited.

[0099] In this embodiment, the distance between the center lines of two adjacent reference ground lines 21 is a first distance, and the distance between the center lines of two adjacent signal lines 31 is a second distance, and the first distance may be less than or equal to the second distance. Thus, it can be ensured that the reference ground line 21 can completely cover the signal line 31 in the height direction of the flexible circuit board 100, thereby further improving the shielding performance of the reference ground layer 20.

[0100] Exemplarily, the ratio of the width of the reference ground line 21 to the width of the signal line 31 can be in the range of 1:2 to 5:1 (including the endpoint values ​​1:2 and 5:1). Under this setting, multiple reference ground lines 21 can achieve shielding performance in a one-to-one correspondence manner of one reference ground line 21 corresponding to one signal line 31. Alternatively, multiple reference ground lines 21 can also achieve shielding performance in a many-to-one correspondence manner of one reference ground line 21 corresponding to multiple signal lines 31, with good reliability.

[0101] In the embodiments of the present application, by adopting the reference ground layer 20 described in the above two embodiments, the external interference of the flexible circuit board 100 can be reduced and the electromagnetic shielding performance of the flexible circuit board 100 can be improved by increasing the layout density of the grid copper in embodiment one and / or using a grid grid ground to cover the signal line 31 in embodiment two while using the same grid copper ratio as in the prior art.

[0102] It should be noted that the above improvements on the structure of the reference layer 20 in the flexible circuit board 100 can also be applied to radio frequency transmission lines, and the embodiments of the present application do not impose strict limitations on this.

[0103] For a possible implementation, see Fig.25 , Fig.25 yes Figure 2 Another structural schematic diagram of the flexible circuit board 100 is shown. The flexible circuit board 100 may further include a first shielding layer 40, which is disposed on a side of the signal layer 30 away from the substrate 10. The first shielding layer 40 is made of metal.

[0104] It is understandable that when the proportion of grid copper is large, the shielding effectiveness of the reference stratum 20 will be weakened. In order to address the problem of insufficient electromagnetic compatibility caused by the weakened shielding effectiveness, it is necessary to add a metal layer on the outside of the signal layer 30 and the reference stratum 20 to achieve shielding effectiveness. Since the shielding effectiveness of the reference stratum 20 in this application is better, it is suitable for both large and small grid copper proportions. Therefore, it can replace the coating on the reference stratum 20 side during use, so there is no need to set another metal shielding layer on the reference stratum 20 side, thereby achieving the effect of reducing cost, reducing thickness, and reducing weight.

[0105] For another possible implementation, see Fig.26 , Fig.26 yes Figure 2 Another structural schematic diagram of the flexible circuit board 100 is shown. The flexible circuit board 100 may also include a first shielding layer 40 and a second shielding layer 50, wherein the first shielding layer 40 is disposed on a side of the signal layer 30 away from the substrate 10, and the second shielding layer 50 is disposed on a side of the reference ground layer 20 away from the substrate 10. The first shielding layer 40 and the second shielding layer 50 are made of metal. By providing the first shielding layer 40 and the second shielding layer 50, the shielding performance of the flexible circuit board 100 can be further improved, and the reliability is good.

[0106] The embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An electronic device, characterized in that: The electronic device includes a flexible circuit board, and the flexible circuit board includes: A substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; A reference ground layer, the reference ground layer is disposed on the first surface of the substrate, the reference ground layer comprises a plurality of reference ground lines disposed at intervals; and A signal layer, the signal layer is disposed on the second surface of the substrate, and the signal layer includes a signal line; The orthographic projection of at least one of the reference ground lines on the substrate covers the orthographic projection of one or more of the signal lines on the substrate.

2. The electronic device according to claim 1, wherein: The signal layer includes a plurality of signal lines, and the plurality of signal lines are arranged at intervals.

3. The electronic device according to claim 2, characterized in that: The plurality of reference ground lines are arranged in the same direction as the plurality of signal lines.

4. The electronic device according to claim 2 or 3, characterized in that: The orthographic projection of each of the reference ground lines on the substrate covers the orthographic projections of a plurality of the signal lines on the substrate.

5. The electronic device according to any one of claims 2 to 4, characterized in that: The signal layer includes a ground line, a plurality of reference ground lines are connected to the ground line, and the ground line is grounded.

6. The electronic device according to claim 2, characterized in that: The plurality of signal lines include differential signal lines.

7. The electronic device according to claim 1, wherein: The signal line and the reference ground line include copper.

8. The electronic device according to any one of claims 1 to 7, characterized in that: The flexible circuit board includes a bending portion and a non-bending portion, the bending portion is bent relative to the non-bending portion; the plurality of reference ground lines are arranged at the bending portion.

9. The electronic device according to any one of claims 1 to 8, characterized in that: The electronic device comprises a display screen, a back cover, a frame and a circuit board; The display screen is arranged on a first side of the frame, the back cover is arranged on a second side of the frame, the first side of the frame is opposite to the second side of the frame, and the circuit board is located between the back cover and the frame; One end of the flexible circuit board is connected to the display screen, and the other end of the flexible circuit board is connected to the circuit board.

10. The electronic device according to any one of claims 2 to 9, characterized in that: The distance between the center lines of two adjacent reference ground lines is a first distance, the distance between the center lines of two adjacent signal lines is a second distance, and the first distance is less than or equal to the second distance.

11. The electronic device according to any one of claims 2 to 9, characterized in that: The ratio of the width of the reference ground line to the width of the signal line is in the range of 1:2 to 5:

1.

12. The electronic device according to any one of claims 1 to 11, characterized in that: The flexible circuit board further includes a first shielding layer, which is arranged on a side of the signal layer away from the substrate.

13. The electronic device according to any one of claims 1 to 11, characterized in that: The flexible circuit board further includes a first shielding layer and a second shielding layer. The first shielding layer is arranged on a side of the signal layer away from the substrate, and the second shielding layer is arranged on a side of the reference ground layer away from the substrate.

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