Electronic device and circuit board assembly

Abstract

An electronic device and a circuit board assembly, and relate to the technical field of electronic power. The electronic device comprises a rotating assembly and a multilayer flexible circuit board; the multilayer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly, both ends of the multilayer flexible circuit board are located outside the rotating assembly and are fixed on both sides of the rotating assembly respectively; the multilayer flexible circuit board comprises at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; one or more first areas and one or more second areas are included in the area where there is an air gap between the second circuit board and the first circuit board, the width of the radio frequency signal transmission line in the second area is wider than that in the first area; the distance between the second circuit board and the first circuit board at the first area is less than that at the second area. The scheme improves the impedance matching performance of the radio frequency signal transmission line and the receiving and transmitting quality of the radio frequency signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to an electronic device and a circuit board assembly. BACKGROUND

[0002] With the development of technology, folding electronic devices have been widely used in people's lives.

[0003] Taking a folding electronic device as a mobile phone device as an example, the folding mobile phone device generally includes multiple middle frames, and two adjacent middle frames in the multiple middle frames are rotationally connected to opposite sides of a rotating assembly, so as to change the form of the folding mobile phone device by rotation and realize the conversion of the folding mobile phone device between an unfolded state and a folded state. The folding mobile phone device generally includes multiple layers of flexible printed circuits (FPCs), both ends of the FPCs are located outside the rotating assembly, and specifically are located in the two middle frames on both sides, respectively. The FPCs pass through the rotating assembly, thereby realizing the transmission of signals between the two middle frames. When the folding electronic device is switched between the folded state and the unfolded state, the flexible printed circuit will be dynamically bent.

[0004] One or more layers of FPCs in the multiple layers of FPCs are used as reference grounds, and another one or more layers of FPCs are used as signal lines. During the dynamic bending process, the change in the form of the multiple layers of FPCs will cause the thickness of the air gap between the multiple layers of FPCs to change, so that the distance between the reference ground and the signal line changes, which will cause the impedance of the signal line to change. This means that the impedance of the signal line will fluctuate when the electronic device is switched between the folded state and the unfolded state. When the signal line is a radio frequency signal transmission line, the fluctuation of the impedance will cause the impedance matching condition to deteriorate, and the quality of radio frequency signal transmission and reception of the device will decrease. SUMMARY

[0005] In order to solve the above problems, the present application provides an electronic device and a circuit board assembly, which reduces the impedance fluctuation of the radio frequency signal transmission line before and after the electronic device is switched between the folded state and the unfolded state, improves the impedance matching performance, and further improves the quality of radio frequency signal transmission and reception.

[0006] In a first aspect, the present application provides an electronic device, which comprises a rotating assembly and a multi-layer flexible circuit board. The multi-layer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly, and both ends of the multi-layer flexible circuit board are located outside the rotating assembly and are fixed on both sides of the rotating assembly respectively. The multi-layer flexible circuit board comprises at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line. In a region where there is an air gap between the second circuit board and the first circuit board, one or more first regions are included, and one or more second regions are included, and the width of the radio frequency signal transmission line in the second region is wider than the width of the radio frequency signal transmission line in the first region. The distance between the second circuit board and the first circuit board at the first region is less than the distance between the second circuit board and the first circuit board at the second region.

[0007] In the multi-layer flexible circuit board, the first circuit board and the second circuit board can form a microstrip line or a strip line structure, and the region where the second circuit board and the first circuit board have an air gap is a dynamic bending area. According to the size of the air gap of the multi-layer FPC on the electronic device at different positions, the width of the radio frequency signal transmission line is adjusted. Specifically, for the first region, since the distance between the radio frequency signal transmission line and the first circuit board at the first region is short, the ground impedance of the radio frequency signal transmission line is small, and the radio frequency signal transmission line can be appropriately thinned, thereby increasing the ground impedance of the radio frequency signal transmission line. For the second region, since the distance between the radio frequency signal transmission line and the first circuit board at the second region is long, the ground impedance of the radio frequency signal transmission line is large, and the radio frequency signal transmission line can be appropriately widened, thereby reducing the ground impedance of the radio frequency signal transmission line. Through the above adjustment mode, the impedance fluctuation of the radio frequency signal transmission line before and after the electronic device switches between the folded state and the unfolded state is reduced, the impedance matching performance is improved, and the quality of the radio frequency signal transmission and reception is improved.

[0008] In a possible implementation, the second circuit board further comprises a second ground wire, and the second ground wire is distributed on both sides of the radio frequency signal transmission line. The first ground wire on the first circuit board corresponding to the at least one second region has a grid-shaped hollow region.

[0009] In this implementation, by providing a grid-shaped hollow region on the first ground wire on the first circuit board corresponding to the second region, the coupling area between the first ground wire and the radio frequency signal transmission line is reduced, so that the coupling between the radio frequency signal transmission line and the second ground wire in the second region is relatively stronger. At this time, the strip line structure or the microstrip line structure is transformed into a coplanar form, which is equivalent to realizing field transformation. By adjusting the impedance between the radio frequency signal transmission line and the second ground wire on both sides, the impedance matching performance can be guaranteed in the region with a large air gap.

[0010] In a possible implementation, the second circuit board further comprises a second ground wire, and the second ground wire is distributed on both sides of the radio frequency signal transmission line.

[0011] In this implementation, in the region with a large air gap, the first ground wire on the first circuit board and the radio frequency signal transmission line are far apart and have poor coupling, so the distance between the radio frequency signal transmission line and the second ground wire is short and the coupling is enhanced, and at this time the stripline structure or the microstrip line structure is changed into a coplanar form, which is equivalent to realizing field transformation, and by adjusting the impedance between the radio frequency signal transmission line and the second ground wire on both sides, the impedance matching performance can be ensured in the region with a large air gap.

[0012] In a possible implementation, the first ground wire on the first circuit board in at least one of the one or more first regions has a grid-shaped hollow region.

[0013] In this implementation, the first ground wire on the first circuit board in the first region is provided with a grid-shaped hollow region, which can reduce the coupling area between the first ground wire and the radio frequency signal transmission line when the air gap is small, and can be used to assist in increasing the ground impedance of the radio frequency signal transmission line in the first region, thereby avoiding that the radio frequency signal transmission line is too narrow and is prone to breakage.

[0014] In a possible implementation, the second circuit board further includes a second ground wire, and the second ground wire is distributed on both sides of the radio frequency signal transmission line. The distance between the second ground wire at at least one of the one or more second regions and the radio frequency signal transmission line is smaller than the distance between the second ground wire at the first region on the second circuit board and the radio frequency signal transmission line.

[0015] In this implementation, for the region with a large air gap in the multilayer flexible circuit board, the distance between the second ground wire on the second circuit board and the radio frequency signal transmission line can be closer. The coupling effect between the second ground wire and the radio frequency signal transmission line is improved by compressing the distance between the second ground wire and the radio frequency signal transmission line.

[0016] In a possible implementation, the medium material layer adjacent to the second circuit board on the first circuit board, and / or the medium material layer adjacent to the first circuit board on the second circuit board, uses one or more of the following materials: liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), and polyfluoroethylene propylene (FEP).

[0017] In a possible implementation, the medium material layer adjacent to the second circuit board on the first circuit board, and / or the medium material layer adjacent to the first circuit board on the second circuit board, has a dielectric constant less than or equal to 3.

[0018] In this implementation, by using a low dielectric constant medium material such as LCP, PTFE or FEP, the impedance fluctuation can be reduced to a certain extent. This is because the impedance of the radio frequency signal transmission line relative to the first ground line is determined by the air layer and the medium material layer between the two. When the air layer exists, the dielectric constant of the medium material layer is close to that of air, and the effect of reducing the impedance fluctuation is better.

[0019] In a possible implementation, the multilayer flexible circuit board includes at least two first circuit boards and one second circuit board; and each side of the second circuit board is provided with one first circuit board.

[0020] In this implementation, a stripline structure is formed in the multilayer flexible circuit board.

[0021] In a possible implementation, the first circuit board and the second circuit board each include a first medium material layer and a second medium material layer; the thickness of the second medium material layer of the first circuit board adjacent to the first medium material layer of the second circuit board is greater than the thickness of the second medium material layer of the second circuit board; and / or the thickness of the first medium material layer of the first circuit board adjacent to the second medium material layer of the second circuit board is greater than the thickness of the first medium material layer of the second circuit board.

[0022] In this implementation, the thickness of the medium material layer between the radio frequency signal transmission line and the first ground line is increased. When the thickness of the medium material layer is increased, the proportion of the air layer becomes smaller, which reduces the impedance fluctuation and improves the consistency of the impedance.

[0023] In a possible implementation, the first ground line adopts a grid-shaped hollow structure.

[0024] When the thickness of the medium material layer is increased, the risk of the first ground line on the first circuit board being broken under stress is increased, and therefore the first ground line can adopt a grid-shaped hollow structure to reduce the stress.

[0025] In a possible implementation, the multilayer flexible circuit board includes a plurality of fixing regions, including a first fixing region, a second fixing region, and a third fixing region, a plurality of bending regions, and a plurality of transition regions. In the first fixing region, the multilayer flexible circuit board passes through and is fixed relative to the rotating assembly; the second fixing region is used to fix the multilayer flexible circuit board on the first side of the rotating assembly; the third fixing region is used to fix the multilayer flexible circuit board on the second side of the rotating assembly; the multilayer flexible circuit board in the plurality of bending regions is in a bent state when the electronic device is in a folded state; and the transition region is a region between two adjacent bending regions or a region between an adjacent fixing region and a bending region.

[0026] In a possible implementation, each bending region is a first region. The first fixed region, the second fixed region and the third fixed region are first regions; a transition region between the second fixed region and an adjacent bending region, and a transition region between the third fixed region and an adjacent bending region are second regions.

[0027] In a possible implementation, when the electronic device is in the unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than the first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value; a transition region between two adjacent bending regions, and a transition region between the first fixed region and a bending region are a third region; the ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is respectively a first impedance value and a second impedance value; when the average of the first impedance value and the second impedance value is less than the first target impedance value, the third region is a first region, otherwise the third region is a second region.

[0028] In this way, the impedance of the radio frequency signal transmission line in the third region fluctuates uniformly above and below the first target impedance value when the electronic device is in the folded or unfolded state, which has little effect on the impedance matching performance, and the impedance matching performance of the electronic device in different states is taken into account.

[0029] In a possible implementation, when the electronic device is in the unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than the first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value; a transition region between two adjacent bending regions, and a transition region between the first fixed region and a bending region are a third region; the ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is respectively a first impedance value and a second impedance value; the ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is respectively a first impedance value and a second impedance value in ascending order; when the difference between the second impedance value and the first target impedance value is greater than the difference between the first target impedance value and the first impedance value, and the radio frequency signal transmission line is distributed with a second ground wire on both sides, the first ground wire on the first circuit board corresponding to the third region has a grid-shaped hollow region, and / or the distance between the second ground wire at the third region and the radio frequency signal transmission line is less than the distance between the second ground wire at a non-third region on the second circuit board and the radio frequency signal transmission line.

[0030] For the electronic device to be unfolded or folded, the ground impedance shifts in different directions for different regions, and when the air gap is small, the impedance shift amount in the impedance reduction direction is small, and when the air gap is large, the impedance shift amount in the impedance increase direction is large. For these regions, the impedance in the direction with a smaller impedance shift can be kept unchanged first, and the impedance in the direction with a larger impedance shift is preferentially inhibited in one direction. By making the coupling between the radio frequency signal transmission line and the second ground line dominant, the ground impedance can be adjusted to be close to the first target impedance value, and the impedance matching performance of the electronic device in different states is considered.

[0031] In a possible implementation, the electronic device includes a first antenna set and a second antenna set; the first antenna set and the radio frequency module of the first antenna set are located on the first side of the rotating assembly; and the second antenna set and the radio frequency module of the second antenna set are located on the second side of the rotating assembly.

[0032] In this implementation, the radio frequency module is arranged on the two sides of the rotating assembly in a distributed manner, which shortens the distance between the radio frequency module and the corresponding antenna, reduces the transmission line loss, and optimizes the radio frequency performance of the electronic device.

[0033] In a possible implementation, the first side of the rotating assembly and / or the second side of the rotating assembly includes an impedance matching circuit; the impedance matching circuit is connected to the radio frequency signal transmission line; the impedance matching circuit includes a switch circuit and multiple impedance adjustment branches; and the switch circuit is configured to select one or multiple impedance adjustment branches to reduce the absolute value of the difference between the ground impedance value of the radio frequency signal transmission line and the first target impedance value when the electronic device is in the folded state or the unfolded state.

[0034] With this scheme, when there is impedance mismatch, impedance matching can be achieved by adjusting the impedance adjustment branch accessed at the port of the radio frequency signal transmission line.

[0035] In a possible implementation, the electronic device further includes a screen support door plate, the inner screen support door plate is arranged between the screen back plate and the metal middle frame of the electronic device; the screen support door plate is fixed to the screen back plate; the screen support door plate is configured to position the multilayer flexible circuit board to separate the multilayer flexible circuit board and the screen back plate; and the second circuit board is located on the side close to the screen back plate in the multilayer flexible circuit board.

[0036] This implementation can ensure that the distance from the radio frequency signal transmission line to the screen back plate 61 is more stable and farther from the metal middle frame, and the impedance fluctuation is smaller.

[0037] In a second aspect, the present application also provides an electronic device, comprising: a rotating assembly and a multilayer flexible circuit board; the multilayer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly, both ends of the multilayer flexible circuit board are located outside the rotating assembly and are fixed on both sides of the rotating assembly respectively; the multilayer flexible circuit board comprises at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; the first side of the rotating assembly and / or the second side of the rotating assembly comprises an impedance matching circuit; the impedance matching circuit is connected to the radio frequency signal transmission line; the impedance matching circuit comprises a switching circuit and multiple impedance adjustment branches; the switching circuit is used to select one or multiple impedance adjustment branches to reduce the absolute value of the difference between the ground impedance value of the radio frequency signal transmission line and a second target impedance value when the electronic device is in a folded state or an unfolded state.

[0038] With the scheme, when there is impedance mismatch, impedance matching can be achieved by adjusting the impedance adjustment branch accessed at the port of the radio frequency signal transmission line, the impedance matching performance is improved, and the quality of the radio frequency signal transmission is improved.

[0039] In a third aspect, the present application also provides a circuit board assembly, comprising: a multilayer flexible circuit board; the multilayer flexible circuit board comprises at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; in the region where the second circuit board and the first circuit board have an air gap, one or more first regions and one or more second regions are included, the width of the radio frequency signal transmission line in the second region is wider than that in the first region; the distance between the second circuit board and the first circuit board at the first region is less than the distance between the second circuit board and the first circuit board at the second region.

[0040] In a possible implementation, the second circuit board further comprises a second ground wire; the second ground wire is distributed on both sides of the radio frequency signal transmission line; the first ground wire on the first circuit board corresponding to at least one of the first regions has a grid-shaped hollow region.

[0041] In a possible implementation, the second circuit board further comprises a second ground wire; the second ground wire is distributed on both sides of the radio frequency signal transmission line.

[0042] In a possible implementation, the first ground wire on the first circuit board corresponding to at least one of the first regions has a grid-shaped hollow region.

[0043] In a possible implementation, the second circuit board further includes a second ground wire; the second ground wire is distributed on both sides of the radio frequency signal transmission line; the distance between the second ground wire at at least one of the one or more second regions and the radio frequency signal transmission line is smaller than the distance between the second ground wire at the first region on the second circuit board and the radio frequency signal transmission line.

[0044] In a possible implementation, the multilayer flexible circuit board includes at least two first circuit boards and one second circuit board; one first circuit board is arranged on each side of the second circuit board; the first circuit board and the second circuit board each include a first dielectric material layer and a second dielectric material layer; the thickness of the second dielectric material layer of the first circuit board adjacent to the first dielectric material layer of the second circuit board is greater than the thickness of the second dielectric material layer of the second circuit board; and / or the thickness of the first dielectric material layer of the first circuit board adjacent to the second dielectric material layer of the second circuit board is greater than the thickness of the first dielectric material layer of the second circuit board.

[0045] In a possible implementation, the first ground wire adopts a grid-shaped hollow structure.

[0046] In a possible implementation, the multilayer flexible circuit board includes a first fixed region, a second fixed region, and a third fixed region, a plurality of bending regions, and a plurality of transition regions; the first fixed region passes through the rotating assembly and is fixed opposite to the rotating assembly; the second fixed region is used for fixing the multilayer flexible circuit board on a first side of the rotating assembly; the third fixed region is used for fixing the multilayer flexible circuit board on a second side of the rotating assembly; the multilayer flexible circuit board in the plurality of bending regions is in a bent state when the electronic device is in a folded state; the transition region is a region between two adjacent bending regions or a region between an adjacent fixed region and a bending region.

[0047] In a possible implementation, each bending region is a first region; the first fixed region, the second fixed region, and the third fixed region are first regions; the transition region between the second fixed region and an adjacent bending region and the transition region between the third fixed region and an adjacent bending region are second regions.

[0048] In a possible implementation, when the multi-layer flexible circuit board is in the unfolded state, the ground impedance of the radio frequency signal transmission line in the first area is greater than the first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second area is less than the first target impedance value; the transition area between each two adjacent bending areas and the transition area between each first fixed area and the bending area are a third area; the ground impedance of the radio frequency signal transmission line in the third area when the electronic device is folded and closed is the first impedance value and the second impedance value respectively; when the average of the first impedance value and the second impedance value is less than the first target impedance value, the third area is the first area, otherwise the third area is the second area.

[0049] In a possible implementation, when the electronic device is in the unfolded state, the ground impedance of the radio frequency signal transmission line in the first area is greater than the first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second area is less than the first target impedance value; the transition area between each two adjacent bending areas and the transition area between each first fixed area and the bending area are a third area; the ground impedance of the radio frequency signal transmission line in the third area when the electronic device is folded and unfolded is the first impedance value and the second impedance value respectively; the ground impedance of the radio frequency signal transmission line in the third area when the electronic device is folded and unfolded is sorted in ascending order as the first impedance value and the second impedance value respectively; when the difference between the second impedance value and the first target impedance value is greater than the difference between the first target impedance value and the first impedance value, and the radio frequency signal transmission line is distributed with the second ground wire on both sides, the first ground wire on the first circuit board corresponding to the third area has a grid-shaped hollow area, and / or the distance between the second ground wire at the third area and the radio frequency signal transmission line is less than the distance between the second ground wire at the non-third area on the second circuit board and the radio frequency signal transmission line. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A schematic diagram of a laterally folded electronic device is provided for the present application;

[0051] Figure 2 A schematic diagram of a vertically folded electronic device is provided for the present application;

[0052] Figure 3 A structural schematic of an electronic device is provided for the present application Figure 1 ;

[0053] Figure 4 A schematic diagram of an electronic device in an unfolded state is provided for the present application;

[0054] Figure 5 A schematic diagram of a microstrip line structure FPC is provided for the present application;

[0055] Figure 6A schematic diagram of a FPC with a stripline structure is provided in the present application.

[0056] Figure 7 A schematic diagram of an electronic device is provided in the present application.

[0057] Figure 8 A schematic diagram of a FPC provided in the present application is provided in the present application.

[0058] Figure 9 A side view of an electronic device provided in the present application is provided in the present application.

[0059] Figure 10 A side view of another electronic device provided in the present application is provided in the present application.

[0060] Figure 11 A schematic diagram of another FPC provided in the present application is provided in the present application.

[0061] Figure 12 A schematic diagram of a principle provided in the present application Figure 1 .

[0062] Figure 13 A schematic diagram of another FPC provided in the present application is provided in the present application.

[0063] Figure 14 A top view of a FPC provided in the present application is provided in the present application.

[0064] Figure 15 A schematic diagram of another FPC provided in the present application is provided in the present application.

[0065] Figure 16 A schematic diagram of another FPC provided in the present application is provided in the present application.

[0066] Figure 17 A schematic diagram of an electronic device is provided in the present application.

[0067] Figure 18 A schematic diagram of an electronic device is provided in the present application.

[0068] Figure 19 A schematic diagram of an impedance matching circuit is provided in the present application. DETAILED DESCRIPTION

[0069] 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.

[0070] See Figure 1 and Figure 2 . Wherein, Figure 1 is a schematic view of a transversely folded electronic device provided by the present application; Figure 2 is a schematic view of a vertically folded electronic device provided by the present application.

[0071] For Figure 1 the transversely folded electronic device shown, an inner folding or outer folding implementation can be adopted.

[0072] The inner folding implementation is as shown in 1-(1) to 1-(3) of Figure 1 1-(1) corresponds to a schematic view of the electronic device in a folded state, 1-(2) corresponds to a schematic view of the electronic device in an unfolding process, and 1-(3) corresponds to a schematic view of the electronic device in an unfolded state.

[0073] The outer folding implementation is as shown in 1-(4) to 1-(6) of Figure 1 1-(4) corresponds to a schematic view of the electronic device in a folded state, 1-(5) corresponds to a schematic view of the electronic device in an unfolding process, and 1-(6) corresponds to a schematic view of the electronic device in an unfolded state.

[0074] For Figure 2 the vertically folded electronic device shown, the rotating assembly is located in the middle of the vertical screen. The electronic device can be folded along the arrow direction in Figure 2 .

[0075] For the convenience of description, the inner folding electronic device as shown in 1-(1) to 1-(3) of Figure 1 is taken as an example for description in the following description of the present application. The principles are similar for electronic devices of other folding modes, and will not be described one by one. It can be understood that the scheme of the present application can also be applied to folding electronic devices including multiple rotating assemblies, i.e., electronic devices of "three-fold" and above.

[0076] Referring to Figure 3 , the figure is a structural schematic Figure 1 of an electronic device provided by the present application.

[0077] For the inner folding electronic device, it includes a first part 11 and a second part 21. The first part 11 includes a first circuit board 12, and the second part 21 includes a second circuit board 22. The electronic device generally includes at least two groups of FPCs. Each group of FPCs can include multiple layers of FPCs. The two sides of the FPC can be connected to the circuit boards through a board-to-board connector (BTB connector).

[0078] The first end of each group of FPCs is connected to the first circuit board 12 of the first part 11, and the second end of each group of FPCs is connected to the second circuit board 22 of the second part 21.

[0079] The first group of FPCs 41 can be used to transmit radio frequency signals, that is, the first group of FPCs 41 is provided with a radio frequency signal transmission line.

[0080] The second group of FPCs 42 can be used to transmit control signals and other non-radio frequency signals.

[0081] Referring to Figure 4 , which is a schematic view of an electronic device provided by the present application in an unfolded state.

[0082] Figure 4 Corresponding Figure 3 to the side view in the direction of arrow A. The rotating assembly at least includes a first fixing member 31 and a second fixing member 32. The first fixing member 31 can also be referred to as a shaft cover. The first fixing member 31 and the second fixing member 32 have a limiting and fixing effect on the first group of FPCs 41, and the first group of FPCs 41 passes through the gap between the second fixing member 32 through the first fixing member 31. The area where the first fixing member 31 passes through the second fixing member 32 can be referred to as a first fixing area.

[0083] The two sides of the first group of FPCs 41 are respectively connected to a third fixing member 80 and a fourth fixing member 81. The area where the third fixing member 80 is located can be referred to as a second fixing area, and the area where the fourth fixing member 81 is located can be referred to as a third fixing area.

[0084] After the side of the first group of FPCs 41 is fixed through the second fixing area, the L1 end extending out can be connected to a BTB connector, thereby connecting a circuit board, or the L1 end can be connected to other devices.

[0085] The other side of the first group of FPCs 41 can be fixed through the second fixing area, and the L2 end extending out can be connected to a BTB connector, thereby connecting a circuit board, or the L2 end can be connected to other devices.

[0086] Generally, the first fixing area, the second fixing area, the third fixing area, the L1 end, and the L2 end described above can be reinforced, that is, an outer FPC (generally, an FPC used for laying a ground wire) at these positions is additionally provided with a reinforcing material to enhance the mechanical strength and stability of the FPC, so as to reduce the risk of FPC fracture at these positions. The reinforcing material can be metal or non-metal, and the embodiments of the present application are not limited in this regard.

[0087] The first group of FPCs 41 is located between the metal middle frame 70 and the screen back plate 61.

[0088] In a possible implementation, the metal middle frame 70 is an aluminum alloy middle frame.

[0089] The screen backboard 61 is used to support and protect the display screen 60. In a possible implementation, the display screen 60 can be a flexible display screen.

[0090] The first fixed region and the second fixed region, and the first fixed region and the third fixed region can be referred to as dynamic bending regions. The form of the first group of FPCs 41 between the dynamic bending regions can change correspondingly with the unfolding or folding of the electronic device.

[0091] In order to disperse stress during bending, in the dynamic bending regions, the multiple layers of FPCs are not fixed together by glue, but are designed to have air gaps, so as to adapt to the deformation of the FPCs when the FPCs are bent, reduce concentrated stress, and prevent the FPCs and / or lines from being broken or damaged, thereby protecting the FPCs and lines.

[0092] This mode can cause the size of the air gap between the multiple layers of FPCs to be different at different positions in the dynamic bending regions. For example, the area with a larger air gap corresponds to the dashed box area in Figure 4 .

[0093] For the first group of FPCs 41 that transmit radio frequency signals, the multiple layers of FPCs generally form a stripline or microstrip structure, which will be described below with reference to the accompanying drawings.

[0094] Referring to Figure 5 , which is a schematic diagram of an FPC with a microstrip structure provided by the present application.

[0095] Figure 5 Corresponding to the side view in the direction of arrow B in Figure 3 .

[0096] At this time, the first group of FPCs 41 at least includes a first FPC 411 and a second FPC 412.

[0097] The first FPC 411 is used to carry the ground line 402.

[0098] The second FPC 412 is used to carry the radio frequency signal transmission line 404. The radio frequency signal transmission line 404 is a strip-shaped trace.

[0099] Each layer of FPC includes a layer of coverlay 403 and a layer of polyimide (PI) 401

[0100] The air medium layer 50 is between the first FPC 411 and the second FPC 412. The thickness of the air medium layer 50 is the size of the air gap between the two layers of FPCs.

[0101] For example, Figure 4 In the dynamic bending area in Figure 4 In the area corresponding to the dashed box in

[0102] Overall, due to the changing distance of the ground wire 402 relative to the radio frequency signal transmission line 404, the impedance of the radio frequency signal transmission line 404 to ground (hereinafter referred to as impedance) fluctuates.

[0103] The principle of impedance fluctuation when the multi-layer FPC forms a stripline structure is explained below.

[0104] Referring to Figure 6 , which is a schematic diagram of an FPC with a stripline structure provided by the present application.

[0105] At this time, the first group of FPCs 41 includes at least a first FPC 411A, a second FPC 411B, and a third FPC 412. The first FPC 411A and the second FPC 411B are used to carry the ground wire 402. The third FPC 412 is used to carry the radio frequency signal transmission line 404. The radio frequency signal transmission line 404 is a stripline.

[0106] Each layer of FPC includes a coverlay 403 and a polyimide (PI) 401.

[0107] The air dielectric layer 50 is included between the first FPC 411A and the third FPC 412, and between the second FPC 411B and the third FPC 412. The thickness of the air dielectric layer 50 is the size of the air gap between the two layers of FPC. Similarly, Figure 4 In the dynamic bending area in Figure 4 In the area corresponding to the dashed box in

[0108] The following is explained by taking the stripline as an example. The sum of the thicknesses of the first FPC 411A, the second FPC 411B, and the third FPC 412 is 120 microns.

[0109] When the first group of FPCs 41 is in the original flat state, the thickness of the two air dielectric layers 50 is 15 microns.

[0110] When the first group of FPCs 41 is in the compressed state at the bending position, the thickness of the two air dielectric layers 50 can be considered as 0.

[0111] When there is aFigure 4 The air gap space shown by the dashed box is taken as an example, and the thickness of the two air medium layers 50 is 30 microns. The impedance parameters of the FPC with the stripline structure can be seen from Table 1 below.

[0112] Table 1: Data table of impedance parameters of FPC with stripline structure

[0113] Original flat state Compressed state Air gap exists Thickness (unit: mm) 0.15 0.12 0.18 Signal line thickness (unit: μm) 10 10 10 Line width w (unit: mm) 0.075 0.075 0.075 Impedance (unit: Ω) 50.6 43.7 56.4

[0114] The original flat state impedance is 50.6, which basically meets the requirements of impedance matching. The impedance of the existing technology generally refers to the impedance in the flat state.

[0115] It can be found from Table 1 that when the first group of FPCs are pressed or there is an air gap, the impedance of the wire fluctuates greatly.

[0116] The fluctuation in the real scene is more complex, and the state of the impedance is more difficult to control. When the impedance of the radio frequency signal transmission line fluctuates greatly, the impedance matching condition deteriorates seriously, and the signal receiving and transmitting quality of the device decreases significantly.

[0117] To solve the above technical problems, the present application provides an electronic device and a circuit board assembly. In the present application, the width of the signal line of the radio frequency signal transmission line is adjusted, so that the signal transmission line is widened at the position where the impedance increases and narrowed at the position where the impedance decreases. This can effectively reduce the impedance fluctuation of the radio frequency signal transmission line before and after the electronic device switches between the folded state and the unfolded state, improve the impedance matching performance, and further improve the receiving and transmitting quality of the radio frequency signal.

[0118] It can be understood that the orientation names such as "up", "down", "left", "right" and the like in the following embodiments of the present application are only for the purpose of description, and need to refer to the directions in the drawings, and do not constitute a limitation on the technical solutions of the present application.

[0119] The words "first", "second" and the like in the description of the present application are only used for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated.

[0120] In the present application, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral; can be direct connection, or indirect connection through intermediate medium.

[0121] The electronic device provided by the embodiment of the present application is specifically described below with reference to the accompanying drawings.

[0122] Referring to Figure 7 , the figure is a schematic diagram of an electronic device provided by an embodiment of the present application.

[0123] The electronic device includes a rotating assembly and a first group of FPCs 41. The first group of FPCs 41 includes a plurality of layers of flexible circuit boards.

[0124] The plurality of layers of flexible circuit boards pass through the rotating assembly and are fixed relative to the rotating assembly. Two ends of the plurality of layers of flexible circuit boards are located outside the rotating assembly and are fixed on two sides of the rotating assembly, respectively.

[0125] In a possible implementation, the rotating assembly specifically includes a first fixing member 31 and a second fixing member 32. The first fixing member 31, also referred to as a shaft cover, is generally made of metal, for example, made of aluminum alloy. The first fixing member 31 and the second fixing member 32 limit and fix the first group of FPCs 41. The first group of FPCs 41 passes through a gap between the second fixing member 32 through the first fixing member 31. The area where the first fixing member 31 passes through the second fixing member 32 is referred to as a first fixing area.

[0126] In the embodiments of the present application, the plurality of layers of flexible circuit boards at least include a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line.

[0127] For example, when the plurality of layers of flexible circuit boards include a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line, the plurality of layers of flexible circuit boards can form a microstrip line structure as shown in Figure 5 .

[0128] For another example, when the plurality of layers of flexible circuit boards include two first circuit boards for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line, the plurality of layers of flexible circuit boards can form a stripline structure as shown in Figure 6 .

[0129] The area where the first group of FPCs 41 is fixed by the third fixing member 80 is referred to as a second fixing area, and the area where the first group of FPCs 41 is fixed by the fourth fixing member 81 is referred to as a third fixing area.

[0130] Referring to Figure 8 , which is a schematic diagram of an FPC provided by the embodiments of the present application and used for laying a radio frequency signal transmission line.

[0131] Figure 8 Corresponding Figure 3 to the cross-sectional view in the direction of arrow C.

[0132] In the scheme of the embodiments of the present application, in the area where the air gap exists on the second circuit board 404, there are one or more first areas S1 and one or more second areas S2.

[0133] The region where the air gap exists on the second circuit board 404 at least includes a dynamic bending region between the first fixed region and the second fixed region, and a dynamic bending region between the first fixed region and the third fixed region.

[0134] The embodiments of the present application do not limit the specific number of the first region S1 and the second region S2. The widths of the radio frequency signal transmission lines of the plurality of first regions S1 can be the same or different, and the lengths of the radio frequency signal transmission lines of the plurality of first regions S1 can be the same or different. Similarly, the widths of the radio frequency signal transmission lines of the plurality of second regions S2 can be the same or different, and the lengths of the radio frequency signal transmission lines of the plurality of second regions S2 can be the same or different.

[0135] The width of the radio frequency signal transmission line in the second region S2 of the embodiments of the present application is wider than the width of the radio frequency signal transmission line in the first region S1.

[0136] In addition, the distance between the second circuit board 404 and the first circuit board at the second region S2 is greater than the distance between the second circuit board 404 and the first circuit board at the first region S1. The distance between the first circuit board and the second circuit board 404, that is, the size of the air gap between the first circuit board and the second circuit board 404.

[0137] In the prior art, when the first group FPC 41 is in the original flat state, the radio frequency signal transmission line is a metal line with uniform width, and the ground impedance is generally debugged to be uniform 50 ohms.

[0138] When the scheme of the embodiments of the present application is adopted, in order to adapt to the dynamic change of the impedance of the first group FPC 41 with the air gap, the scheme of the present application adjusts the width of the radio frequency signal transmission line according to the size and distribution of the air gap in the dynamic bending region.

[0139] For the first region, since the distance between the radio frequency signal transmission line and the first circuit board at the first region S1 is short, the ground impedance of the radio frequency signal transmission line is small, and the radio frequency signal transmission line can be appropriately thinned to increase the ground impedance of the radio frequency signal transmission line.

[0140] For the second region, since the distance between the radio frequency signal transmission line and the first circuit board at the second region S2 is long, the ground impedance of the radio frequency signal transmission line is large, and the radio frequency signal transmission line can be appropriately widened to reduce the ground impedance of the radio frequency signal transmission line.

[0141] Through the above adjustment mode, the radio frequency signal transmission line is adjusted from a metal line with uniform width to a metal line with varying width, that is, the metal line in the first region is thinner, and the metal line in the second region is wider, so that the first group of FPCs 41, although the impedance to ground is not 50 ohms when in the original flat state, after being assembled to the electronic device, the overall impedance to ground of the radio frequency signal transmission line can be as close to 50 ohms as possible from the input and output ports of the radio frequency signal transmission line, regardless of whether the electronic device is in an unfolded state or a folded state.

[0142] In the impedance adjustment process, the impedance is generally lowered first, because widening the line width is easier to implement and has better consistency than narrowing the line width.

[0143] In summary, by using the scheme provided in the embodiments of the present application, the width of the radio frequency signal transmission line is adjusted according to the size of the air gap between the FPCs on the electronic device at a specific position, which can effectively reduce the impedance fluctuation of the radio frequency signal transmission line during the unfolding and closing process of the folding machine, thus effectively improving the impedance matching performance, reducing signal reflection during signal transmission, and improving the quality of radio frequency signal transmission and reception.

[0144] In a possible implementation, when the first group of FPCs is in the original flat state, the radio frequency signal transmission line has an impedance to ground of 50 ohms as the first target impedance value, and the width of the radio frequency signal transmission line is a first width, then after using the technical scheme of the present application, the width of the radio frequency signal transmission line in the first region is less than the first width, the width of the radio frequency signal transmission line in the second region is greater than the first width, and there can be some regions on the entire radio frequency signal transmission line where the width of the radio frequency signal transmission line is equal to the first width.

[0145] The specific distribution of the first region and the second region in the first group of FPCs will be described below. In the following description, the impedance adjustment target of the radio frequency signal transmission line is taken as 50 ohms as an example for description.

[0146] Referring to Figure 7 and Figure 9 , wherein Figure 9 is a side view of an electronic device in a folded state provided by an embodiment of the present application.

[0147] The first group of FPCs 41 on the electronic device includes a first fixed region F1, a second fixed region F21, and a third fixed region F22. The first group of FPCs 41 includes multiple layers of flexible circuit boards.

[0148] Among them, in the first fixed region F1, the multiple layers of flexible circuit boards of the first group of FPCs 41 pass through the rotating assembly and are fixed relative to the rotating assembly.

[0149] The second fixing area F21 is used for fixing the multi-layer flexible circuit board on the first side of the rotating assembly, for example, the multi-layer flexible circuit board can be fixed by the third fixing member 80.

[0150] The third fixing area F22 is used for fixing the multi-layer flexible circuit board on the second side of the rotating assembly, for example, the multi-layer flexible circuit board can be fixed by the fourth fixing member 81.

[0151] The dynamic bending area is between the first fixing area F1 and the second fixing area F21, and between the first fixing area F1 and the third fixing area F22, and the form of the first group of FPCs 41 in the dynamic bending area changes with the unfolding and folding of the electronic device.

[0152] The dynamic bending area of the first group of FPCs 41 specifically includes a plurality of bending areas and a plurality of transition areas.

[0153] When the electronic device is in the folded state, the multi-layer flexible circuit board in the bending area is in the bent state. Figure 7 The bending areas in the first group of FPCs 41 are symmetrically distributed about the first fixing area F1, and the bending areas on one side are B11 and B21, and the bending areas on the other side are B12 and B22.

[0154] The transition area is the area between two adjacent bending areas, for example, including T21 and T22, and the transition area can also be the area between the adjacent fixing area and the bending area, for example, including T11, T31, T12 and T32.

[0155] Taking the first target impedance value of 50 ohms as the final impedance adjustment target, the line width of the radio frequency signal transmission line when the first group of FPCs 41 is in the original flat state can be w. In the scheme of the embodiment of the present application, the radio frequency signal transmission line impedance of the multi-layer flexible circuit board in different areas, without using the technical scheme of the present application, there are the following three impedance fluctuation situations:

[0156] 1. When the electronic device is in the unfolded or folded state, the impedance in the area is always less than the first target impedance value;

[0157] 2. When the electronic device is in the unfolded or folded state, the impedance in the area is always greater than the first target impedance value;

[0158] 3. When the electronic device is in the unfolded state, the impedance in the area is greater than the first target impedance value, and when the electronic device is in the folded state, the impedance in the area is less than the first target impedance value; or, when the electronic device is in the unfolded state, the impedance in the area is less than the first target impedance value, and when the electronic device is in the folded state, the impedance in the area is greater than the first target impedance value.

[0159] The region satisfying the first case above includes the bending region and the fixed region. The first region at least includes the bending region and the fixed region, that is, the first region at least includes a region whose impedance is always less than the first target impedance value when the electronic device is in the unfolded or folded state.

[0160] The first fixed region F1, the second fixed region F21, and the third fixed region F31 of the multilayer flexible circuit board are in a state of being compressed, and the air gap between the multilayer flexible circuit boards is always in a small state, so that the impedance of the radio frequency signal transmission line to the ground is always less than the first target impedance value. Therefore, the present application determines these fixed regions as the first region, and narrows the line width of the radio frequency signal transmission line in the first region, so that the impedance of the radio frequency signal transmission line to the ground is increased to close to the first target impedance value. Figure 7 and Figure 9 The first fixed region F1, the second fixed region F21, and the third fixed region F31 of the multilayer flexible circuit board are in a state of being compressed, and the air gap between the multilayer flexible circuit boards is always in a small state, so that the impedance of the radio frequency signal transmission line to the ground is always less than the first target impedance value. Therefore, the present application determines these fixed regions as the first region, and narrows the line width of the radio frequency signal transmission line in the first region, so that the impedance of the radio frequency signal transmission line to the ground is increased to close to the first target impedance value.

[0161] In addition, Figure 7 The bending regions B11, B21, B12, B22, etc. in the electronic device also satisfy the first case above.

[0162] Specifically, the bending regions B11, B21, B12, B22, etc. have a large bending radius when the electronic device is in the unfolded state, and under the action of the bending stress, the air gap between the multilayer flexible circuit boards is small, and the impedance of the radio frequency signal transmission line to the ground is less than the first target impedance value; when the electronic device is in the folded state, B11 and B21 are in the region B31 in Figure 9 , B12 and B22 are in the region B32 in Figure 9 , B31 and B32 are also in the bending state, and under the action of the bending stress, the air gap between the multilayer flexible circuit boards is small, and the impedance of the radio frequency signal transmission line to the ground is less than the first target impedance value. Therefore, the present application determines these bending regions as the first region, and narrows the line width of the radio frequency signal transmission line in the first region, so that the impedance of the radio frequency signal transmission line to the ground is increased to close to the first target impedance value.

[0163] The first case of impedance fluctuation is illustrated as follows.

[0164] In practical applications, although the radio frequency signal transmission line in the above first region has an impedance to the ground less than 50 ohms when the electronic device is in the folded or unfolded state, there is still fluctuation with the change of the state of the electronic device. For example, for the B11 region, without the present application, when the electronic device is in the unfolded state as shown in Figure 7 , the average detection value of the impedance of the radio frequency signal transmission line to the ground is about 40 ohms, and when the electronic device is in the folded state as shown in Figure 9In the folded state shown, the average detected impedance to ground of the RF signal transmission line is approximately 48 ohms. First, the two average detected values ​​are averaged, resulting in 44 ohms. Then, the RF signal transmission line is narrowed to increase the impedance to ground. The target increase is 50-44=6 ohms, equivalent to increasing the impedance by 6 ohms in both states. After adjusting the line width, the impedance fluctuation range of the RF signal transmission line in segment B11 is between 46 ohms and 54 ohms. This impedance fluctuation around 50 ohms has a minimal impact on impedance matching performance, balancing the impedance matching performance of the electronic equipment in different states.

[0165] The regions satisfying the second condition above include the transition region T31 between the second fixed region F21 and the adjacent bending region B21, and the transition region T32 between the third fixed region F22 and the adjacent bending region B22. The second region includes at least the region where the impedance is always greater than the first target impedance value when the electronic device is in an unfolded or folded state.

[0166] Specifically, in transition regions T31 and T32, when the electronic device is in the unfolded state, the multilayer flexible circuit boards in the fixed and bent areas at both ends experience high stress, resulting in a larger air gap between the multilayer flexible circuit boards in the middle transition region, and the impedance of the RF signal transmission line to ground exceeding the first target impedance value; when the electronic device is in the folded state, transition region T31 is in... Figure 9 In region T51, transition region T32 is located Figure 9 In region T52, both ends of T51 and T52 are fixed and bent areas subject to high stress, resulting in a large air gap between the multilayer flexible circuit boards within T51 and T52, and the impedance of the RF signal transmission line to ground exceeding the first target impedance value. Therefore, this application defines the transition regions T31 and T32 as the second region. By increasing the linewidth of the RF signal transmission line within the second region, the impedance of the RF signal transmission line to ground is reduced to be close to the first target impedance value.

[0167] The following example illustrates the second type of impedance fluctuation described above.

[0168] In practical applications, although the impedance to ground of the RF signal transmission lines in the transition regions T31 and T32 is greater than the first target impedance value of 50 ohms when the electronic device is in a folded or unfolded state, it will still fluctuate with changes in the state of the electronic device. For example, in region T31, without the scheme of this application, when the electronic device is in... Figure 7 In the unfolded state shown, the average detected value of the RF signal transmission line's impedance to ground is approximately 85 ohms. When the electronic device is in... Figure 9In the folded state shown, the average detected impedance to ground of the RF signal transmission line is approximately 65 ohms. First, the two average detected values ​​are averaged, resulting in 75 ohms. Then, the RF signal transmission line is widened to reduce the impedance to ground. The target reduction difference is 75-50=25 ohms, equivalent to reducing the impedance by 25 ohms in both states. After adjusting the line width, the impedance fluctuation range of the RF signal transmission line in segment T31 is between 40 and 60 ohms. This impedance fluctuation around 50 ohms has a minimal impact on impedance matching performance, balancing the impedance matching performance of the electronic equipment in different states.

[0169] In the two impedance fluctuation scenarios above, the impedance to ground of the RF signal transmission line shifts to the same side as the first target impedance value when the electronic device is in an unfolded or folded state, that is, it is always greater than or always less than the first target impedance value. In the third scenario, the impedance shifts to the opposite side of the first target impedance value. The region that satisfies the third scenario above is the transition region at a specific location, which will be explained in detail below.

[0170] for Figure 7 The transition regions T11 and T12 shown in the diagram, when the electronic device is in the unfolded state, experience high stress on the multilayer flexible circuit boards in the two side regions (bending region and first fixed region, respectively), resulting in a larger air gap between the multilayer flexible circuit boards in the middle transition region. This causes the impedance of the RF signal transmission lines of T11 and T12 to ground to be greater than the first target impedance value. When the electronic device is in the folded state... Figure 9 The multilayer flexible circuit boards in transition regions T11 and T12 experience greater stress, resulting in smaller air gaps. Consequently, the impedance to ground of the RF signal transmission lines in T11 and T12 is less than the first target impedance value. Therefore, transition regions T11 and T12 satisfy the third impedance offset condition described above.

[0171] Similarly, for Figure 7 In the transition regions T21 and T22, when the electronic device is in the unfolded state, the bending areas on both sides experience greater stress, resulting in a larger air gap between the multilayer flexible circuit boards within T21 and T22. Consequently, the impedance of the RF signal transmission lines to ground within these regions exceeds the first target impedance value. When the electronic device is in the folded state, T21 is in... Figure 9 In region B31, T22 is located Figure 9 Regions B32, B31, and B32 in the circuit exhibit greater stress, resulting in smaller air gaps between the multilayer flexible circuit boards and an RF signal transmission line impedance to ground that is less than the first target impedance value. Therefore, transition regions T21 and T22 satisfy the third impedance offset condition described above.

[0172] It can be found that the area satisfying the third impedance shift condition can be referred to as a third area, and the third area generally includes a transition area between two adjacent bending areas and a transition area between the first fixed area and the bending area.

[0173] For the third area, the ground impedance of the radio frequency signal transmission line in the third area when the electronic device is folded and unfolded is respectively a first impedance value and a second impedance value. When the average of the first impedance value and the second impedance value is less than the first target impedance value, the third area is the first area, and the radio frequency signal transmission line is narrowed to increase the impedance. Otherwise, the third area is the second area, and the radio frequency signal transmission line is widened to reduce the impedance. The following will be specifically illustrated by examples.

[0174] For example, for the transition area T11, when the electronic device is in an unfolded state, the ground impedance of the radio frequency signal transmission line in T11 is 80 ohms, and when the electronic device is in a folded state, the ground impedance of the radio frequency signal transmission line in T11 is 40 ohms. That is, the first impedance value is 40 ohms, the second impedance value is 80 ohms, and the average is 60 ohms, which is greater than the first target impedance value 50 ohms. Therefore, the transition area T11 is the second area, and the radio frequency signal transmission line needs to be widened to reduce the ground impedance. The target difference to be reduced is 60-50=10 ohms. After adjusting the line width, the impedance fluctuation range of the radio frequency signal transmission line in the T11 segment is between 30 ohms and 70 ohms. In this way, the impedance fluctuates uniformly above and below 50 ohms, and the influence on the impedance matching performance is small, and the impedance matching performance of the electronic device in different states is considered.

[0175] For example, for the transition area T21, when the electronic device is in an unfolded state, the ground impedance of the radio frequency signal transmission line in T21 is 56 ohms, and when the electronic device is in a folded state, the ground impedance of the radio frequency signal transmission line in T11 is 40 ohms. That is, the first impedance value is 40 ohms, the second impedance value is 56 ohms, and the average is 48 ohms, which is less than the first target impedance value 50 ohms. Therefore, the transition area T11 is the first area, and the radio frequency signal transmission line needs to be narrowed to increase the ground impedance. The target difference to be increased is 50-48=2 ohms. After adjusting the line width, the impedance fluctuation range of the radio frequency signal transmission line in the T21 segment is between 42 ohms and 58 ohms. In this way, the impedance fluctuates uniformly above and below 50 ohms, and the influence on the impedance matching performance is small, and the impedance matching performance of the electronic device in different states is considered.

[0176] It can be understood that the area satisfying the third impedance shift condition can also exist in other areas, and the embodiments of the present application will not be repeated here. The above Figure 7 、 9The division of the various regions in 10 is merely illustrative and does not constitute a limitation on the technical solution of this application. In actual applications, the specific number and position of the first and second regions may be related to the length of the first group of FPC41 and the number of limiting structures between the screen back panel 61 and the metal frame 70.

[0177] The limiting structure is used to restrict the position of the first group of FPC41. Since the limiting structure achieves its positional constraint through contact with the first group of FPC41, it can apply stress to the first group of FPC41. This stress alters the air gap between the multilayer flexible circuit boards of the first group of FPC41 at the contact point, affecting the positional distribution of the first and second regions. The limiting structure 63 is typically made of a non-metallic material.

[0178] The limiting structure 63 in the figure can be a screen support panel. The screen support panel is disposed between the screen back panel 61 and the metal frame 70 of the electronic device. In one possible implementation, the screen support panel is fixed to the screen back panel 61.

[0179] The screen support panel is used to limit the multi-layer flexible circuit board to separate the multi-layer flexible circuit board from the screen back panel 61.

[0180] The second circuit board is located on the side closest to the screen backplate 61 in the multilayer flexible circuit board.

[0181] For example, a multilayer flexible circuit board includes six flexible circuit boards, denoted as a, b, c, and d respectively. Flexible circuit board a is closest to the metal frame 70, and flexible circuit board f is closest to the screen back panel 61. The two side flexible circuit boards form a microstrip line structure. In order to make the second circuit board closer to the screen back panel 61, d can be used as the second circuit board, followed by c, and then b.

[0182] This is because the portion of the multilayer flexible circuit board facing the metal frame 70 is only isolated by air from the metal frame 70. As the overall thickness of electronic devices decreases, the distance between the multilayer flexible circuit board and the metal frame 70 will further narrow. Coupled with redundant deformation during bending, if the RF signal transmission line is close to the outer metal frame 70, it will be more severely affected by the metal frame, especially for microstrip circuit boards, leading to significant impedance fluctuations in the RF signal transmission line. However, if the RF signal transmission line is close to the screen back panel 61, the design of the limiting structure 63 ensures a more stable distance between the RF signal transmission line and the screen back panel 61, and a greater distance from the metal frame, resulting in smaller impedance fluctuations.

[0183] For example, see Figure 10The figure is a side view of another electronic device provided in the embodiment of this application when it is in a folded state. Figure 10 Because the first set of FPC41 is longer, the bending area B11 is located in the middle after the electronic device is folded. Figure 10 In T41, the bending area B12 is located in the electronic device after it is folded. Figure 10 T42 in the middle. Figure 7 The air gap between the multilayer flexible circuit boards in the bending regions B11 and B12 is small, and the impedance to ground of the radio frequency signal transmission line is less than the first target impedance value. Figure 9 The air gap between the multilayer flexible circuit boards in T41 and T42 is relatively large, and the impedance to ground of the radio frequency signal transmission line is greater than the first target impedance value. Therefore, the bending regions B11 and B12 meet the third impedance fluctuation condition mentioned above. At this time, based on the relationship between the average impedance to ground of the bending regions B11 and B12 when the electronic device is folded and unfolded and the first target impedance value, it can be determined whether the radio frequency signal transmission line in the bending regions B11 and B12 should be narrowed or widened.

[0184] In other embodiments, in addition to the radio frequency signal transmission line, a second ground line is also provided on the second circuit board. This will be described in detail below with reference to the accompanying drawings.

[0185] See Figure 11 This figure is a schematic diagram of another FPC with radio frequency signal transmission lines provided in an embodiment of this application.

[0186] The second ground wire 405 is distributed on both sides of the radio frequency signal transmission line 404.

[0187] See also Figure 12 This figure is a schematic diagram of the principle provided in the embodiment of this application. Figure 1 .

[0188] Figure 12 For the corresponding Figure 3 The side view in the B direction, where part 12-(A) is the side view without the second ground wire 405 and part 12-(B) is the side view with the second ground wire 405.

[0189] For section 12-(A), the two layers of first ground wires 402 and the radio frequency signal transmission line 404 form a stripline structure, and the energy is mainly concentrated between the radio frequency signal transmission line 404 and the upper and lower layers of first ground wires 402, such as Figure 12 - As indicated by the arrow in section (A).

[0190] For the 12-(B) part, if the air gap between the multi-layer flexible circuit boards is small, the distance between the radio frequency signal transmission line 404 and the upper and lower first ground lines 402 is close, at this time, the two first ground lines 402 and the radio frequency signal transmission line 404 still form a strip line structure, and the energy concentration position does not change. However, when the air gap between the multi-layer flexible circuit boards is large, the distance between the radio frequency signal transmission line 404 and the upper and lower first ground lines 402 is far, at this time, if the second ground line 405 is not set, impedance mismatch will inevitably occur, and when the second ground line 405 is set, the energy is mainly concentrated between the radio frequency signal transmission line 404 and the second ground line 405 on the left and right sides, which changes the strip line structure into a coplanar form, which is equivalent to realizing field transformation.

[0191] The scheme provided by the embodiment of the present application adjusts the distance between the radio frequency signal transmission line 404 and the second ground line 405 on the two sides, so that the impedance between the radio frequency signal transmission line 404 and the second ground line 405 on the two sides is 50 ohms, which can maintain the impedance at 50 ohms in the area with a large air gap.

[0192] It can be understood that the technical means of the embodiment of the present application can be used independently, or can be used in cooperation with the means for adjusting the radio frequency signal transmission line. That is, in at least one of one or more second regions, the second ground line is distributed on the two sides of the radio frequency signal transmission line 404, and through the cooperation of the two means, the impedance can be more accurately and reliably adjusted to be close to 50 ohms.

[0193] Further, considering the difference in coupling area between the strip line structure and the coplanar form, a hollow grid area can also be provided on the first ground line, which will be described in detail below with reference to the accompanying drawings.

[0194] Referring to Figure 13 , the figure is another schematic diagram of an FPC provided by the embodiment of the present application, which sets the radio frequency signal transmission line.

[0195] In actual process, the thickness H of the metal layer in the second ground line 405 is generally only about 9-12 microns, and due to the small coupling area, the coupling effect between the second ground line 405 and the radio frequency signal transmission line 404 is far worse than the coupling effect between the radio frequency signal transmission line 404 and the first ground line 402 in the vertical direction. Therefore, in order to avoid that when the air gap between the multi-layer flexible circuit boards is large, the radio frequency signal transmission line 404 still forms a strong coupling with the first ground line 402, a grid-shaped hollow area 4021 can be provided on the first ground line 402 in the area with a large air gap between the multi-layer flexible circuit boards, thereby reducing the coupling area between the radio frequency signal transmission line 404 and the first ground line 402, and enhancing the coupling effect between the second ground line 405 and the radio frequency signal transmission line 404 in the horizontal direction.

[0196] The embodiment of the present application does not make specific limitation to the porosity of the grid-shaped hollowed-out area 4021 arranged on the first ground wire 402, and the porosity can be adjusted according to actual capacitance requirement, and the purpose is to reduce the coupling effect between the radio frequency signal transmission line 404 and the first ground wire 402.

[0197] Referring to Figure 14 , the figure is a top view of an FPC provided by the embodiment of the present application and arranged with a radio frequency signal transmission line.

[0198] The embodiment of the present application does not make specific limitation to the hollow grid shape of the grid-shaped hollowed-out area 4021, and specifically, a circular shape, a triangular shape, a diamond shape, a rectangular shape, etc. can be adopted.

[0199] It can be understood that, therefore, if a large number of layers of flexible circuit boards are included on the first group of FPCs, there can be a case of including multiple layers of second circuit boards, at this time, due to the fact that the metal layer of the first ground wire 402 includes the grid-shaped hollowed-out area 4021, the mutual isolation effect between different radio frequency signal transmission lines is weakened, therefore, in order to ensure the isolation degree, the time spacing of different radio frequency signal transmission lines needs to be adjusted, for example, the spacing is increased to increase the spacing between different radio frequency signal transmission lines.

[0200] It can be understood that the technical means of arranging the grid-shaped hollowed-out area 4021 on the first ground wire 402 can also be used in the case that the second circuit board does not have a second ground wire, at this time, the grid-shaped hollowed-out area 4021 can be arranged in the first area, for assisting in increasing the ground impedance of the radio frequency signal transmission line in the first area, and further avoiding the radio frequency signal transmission line in the first area from being too narrow to cause the radio frequency signal transmission line to be easily broken.

[0201] Further, referring to Figure 15 and Figure 16 together. Among them, Figure 15 is another schematic view of an FPC provided by the embodiment of the present application and arranged with a radio frequency signal transmission line; Figure 16 is another schematic view of an FPC provided by the embodiment of the present application and arranged with a radio frequency signal transmission line.

[0202] At this time, the area with a larger air gap in the multiple layers of flexible circuit boards, the distance between the second ground wire 405 on the second circuit board 412 and the radio frequency signal transmission line 404 can be more close. At this time, the second ground wire 405 can adopt the form shown in Figure 15 or Figure 16 , the coupling effect between the second ground wire 405 and the radio frequency signal transmission line 404 is improved by compressing the distance between the second ground wire 405 and the radio frequency signal transmission line 404.

[0203] It can be understood that, due to the weak horizontal coupling ability and small coupling area, for the area with small air gap in the multilayer flexible circuit board, such as each bending area or fixed area, compressing the distance between the second ground wire 405 and the radio frequency signal transmission line 404 has little effect on improving the horizontal line coupling effect, because the coupling area between the radio frequency signal transmission line 404 and the first ground wire 402 is large, which will form a strong coupling. See also Figure 13 For the area with large air gap in the multilayer flexible circuit board, the thickness of the radio frequency signal transmission line 404 and the second ground wire 405 can also be increased, such as using double-sided copper, to further increase the coupling area.

[0204] Figure 15 And Figure 16 The technical means of compressing the distance between the second ground wire 405 and the radio frequency signal transmission line 404 can be used independently, or in combination with adjusting the radio frequency signal transmission line, and / or setting a grid-shaped hollow area in the first ground wire. That is, the distance between the second ground wire 405 and the radio frequency signal transmission line 404 at at least one of the one or more second areas is less than the distance between the second ground wire 405 and the radio frequency signal transmission line 404 at the first area on the second circuit board, and there is a grid-shaped hollow area in the first ground wire on the first circuit board corresponding to the second area.

[0205] Through the above combination of various means, the impedance adjustment can be more accurately and reliably adjusted to be close to 50 ohms. At the same time, it can also avoid the radio frequency signal transmission line in the second area being too wide, and avoid the risk of the radio frequency signal transmission line being broken due to the large difference in width between the radio frequency signal transmission line in the second area and the first area,

[0206] The above Figure 13-16 Corresponding to various means, it is suitable for the area to meet the above second impedance deviation condition, that is, when the electronic device is in an unfolded or folded state, the impedance in the area is always greater than the first target impedance value, and the air gap is always in a wide state. At this time, the second ground wire can be used to reduce the impedance of the radio frequency signal transmission line to ground.

[0207] The third kind of impedance shift satisfying the above-mentioned condition can also be applied to the areas, such as the transition areas T11 and T21. It is found through testing that the ground impedance of the electronic device is 80 ohms when the electronic device is unfolded, and the ground impedance of the electronic device is 40 ohms when the electronic device is folded. After adjusting the line width in the above example, the impedance fluctuation range of the radio frequency signal transmission line is between 30 ohms and 70 ohms, but the fluctuation is still large. It can be found that the ground impedance shift of the electronic device when it is folded is slightly deteriorated, only 10 ohms, but the ground impedance shift of the electronic device when it is unfolded is seriously deteriorated, reaching 30 ohms. Therefore, for the areas where the impedance shift directions are opposite and the shift amount of a single direction is obviously larger, the impedance in the direction with smaller impedance shift can be kept unchanged, and the impedance in the direction with larger impedance shift is preferentially inhibited in one direction. The following will be specifically explained.

[0208] For the third area, the ground impedance of the radio frequency signal transmission line in the third area when the electronic device is folded and unfolded is sorted in ascending order as the first impedance value and the second impedance value. When the difference between the second impedance value and the first target impedance value is greater than the difference between the first target impedance value and the first impedance value, the following measures can be taken on the second circuit board.

[0209] Measure one: a second ground line is arranged on both sides of the radio frequency signal transmission line, and the second ground line is closer to the radio frequency signal transmission line at the transition areas T11 and T21.

[0210] Measure two: a second ground line is arranged on both sides of the radio frequency signal transmission line, and the first ground line at the transition areas T11 and T21 is a grid-shaped hollow area.

[0211] Measure three: a second ground line is arranged on both sides of the radio frequency signal transmission line, and the second ground line is closer to the radio frequency signal transmission line at the transition areas T11 and T21, and the first ground line at the transition areas T11 and T21 is a grid-shaped hollow area.

[0212] At this time, for the transition areas T11 and T21, the radio frequency signal transmission line can not be widened, thereby avoiding the further decrease of the ground impedance of the radio frequency signal transmission line when the electronic device is folded from 40 ohms. When the electronic device is in a folded state, the air gap spacing between the multi-layer flexible circuit boards is small, the coupling between the radio frequency signal transmission line and the first ground line is dominant, and the ground impedance can be maintained at about 40 ohms. When measures two or three are adopted, the ground impedance will also increase and be closer to 50 ohms. When the electronic device is in an unfolded state, the air gap spacing between the multi-layer flexible circuit boards is large. Through the above measures, the coupling between the radio frequency signal transmission line and the second ground line is dominant, and the ground impedance can be adjusted to be close to 50 ohms, which takes into account the impedance matching performance of the electronic device in different states.

[0213] In the above embodiments, the impedance adjustment is mainly achieved by adjusting the ground wire and the RF signal transmission line. The following describes other ways of adjusting the impedance using other parts of the flexible circuit board.

[0214] Referring to Figure 5 and Figure 6 , the upper layer of each flexible circuit board is a coverlay 403, and the lower layer is a PI 401. The PI is a film material. The coverlay 403 and the PI 401 can be referred to as dielectric material layers.

[0215] For the microstrip line structure shown in Figure 5 , the PI of the second circuit board 412 is adjacent to the coverlay 403 of the first circuit board 411.

[0216] For the stripline structure shown in Figure 6 , the coverlay of the second circuit board 412 is adjacent to the PI of the first circuit board 411B, and the PI of the second circuit board 412 is adjacent to the coverlay 403 of the first circuit board 411A.

[0217] In the embodiments of the present application, the dielectric material layer adjacent to the second circuit board on the first circuit board and / or the dielectric material layer adjacent to the first circuit board on the second circuit board uses a dielectric material with a low dielectric constant, which can reduce the impedance fluctuation to a certain extent. This is because the impedance of the RF signal transmission line relative to the first ground wire is determined by the air layer, the coverlay, and the PI between them. When the air layer exists, the dielectric constant of the coverlay and the PI is close to that of air, and the smaller the dielectric constant, the better the effect of reducing the impedance fluctuation.

[0218] The dielectric constant of the material used in the dielectric material layer is less than or equal to 3. The material used in the dielectric material layer can be polytetrafluoroethylene (PTFE), liquid crystal polymer (LCP), or fluorinated ethylene propylene (FEP), etc. It can also be other materials with a dielectric constant less than or equal to 3.

[0219] Further, taking the stripline structure as an example, the thickness of the dielectric material layer between the RF signal transmission line and the first ground wire can also be increased. When the thickness of the dielectric material layer increases, the proportion of the air layer decreases, which will make the impedance fluctuation smaller, and thus improve the consistency of the impedance.

[0220] In actual applications, the thickened dielectric material layer can affect the bending life of the flexible circuit board, and can cause the risk of fracture of the metal traces carried by the flexible circuit board to increase. Considering that the second circuit board is used to set the radio frequency signal transmission line, it is relatively more important, and therefore the dielectric material layer on the upper and lower two first circuit boards can be thickened.

[0221] Continuing to refer to Figure 6 Taking the first dielectric material layer as the coverlay 403 and the second dielectric material layer as the PI 401 as an example. In a possible implementation, the thickness of the second dielectric material layer of the first circuit board 411B adjacent to the first dielectric material layer of the second circuit board 412 is greater than the thickness of the second dielectric material layer of the second circuit board 412, and / or the thickness of the first dielectric material layer of the first circuit board 411A adjacent to the second dielectric material layer of the second circuit board 412 is greater than the thickness of the first dielectric material layer of the second circuit board 412. One of the coverlay 403 or the PI 401 can be thickened, or both can be thickened.

[0222] When the dielectric material layer is thickened, the risk of fracture of the first ground wire on the first circuit board under stress increases, and therefore the first ground wire can adopt a grid-shaped hollow structure to reduce stress; or the thickness of the metal material of the first ground wire can be thinned to improve the flexibility of the first ground wire. By adaptively improving the first ground wire, the bending life of the first ground wire can be improved while the dielectric material layer is thickened. It can be understood that the first ground wire in this implementation can adopt a grid-shaped hollow structure at all positions of the dynamic bending area.

[0223] In the above embodiments, impedance matching is achieved by adjusting the circuit board assembly on the electronic device, but the impedance can still be difficult to reach the first target impedance value of 50 ohms, at which time the insertion loss needs to be compensated. The insertion loss here mainly refers to the signal loss of the radio frequency signal transmission line between the radio frequency module and the antenna feed point. Therefore, the position of the radio frequency module is further adjusted to reduce the insertion loss, which is specifically described below with reference to the accompanying drawings.

[0224] Referring to Figure 17 The figure is a schematic diagram of another electronic device provided by an embodiment of the present application.

[0225] The electronic device includes a first part 11 and a second part 21. The first part 11 includes a first circuit board 12, and the second part 21 includes a second circuit board 22. In a possible implementation, the first circuit board 12 is a main board, and the second circuit board 22 is a vice main board.

[0226] The first part 11 includes at least a first antenna 13, and the second part 21 includes at least a second antenna 23.

[0227] The first circuit board 12 is provided with a first radio frequency module 121 and a first feed point 122, and the second circuit board 22 is provided with a second radio frequency module 221 and a second feed point 222.

[0228] The first radio frequency module 121 and the second radio frequency module 221 can be integrated with radio frequency switches, low-noise amplifiers (LNAs), filters, duplexers, power amplifiers, and the like.

[0229] When the antenna receives electromagnetic waves and converts them into corresponding signals, the corresponding radio frequency module can filter, amplify, and process the signals obtained from the antenna end, and transmit them to the modem processor for demodulation. The demodulator is used to demodulate the received signals into low-frequency baseband signals. Then the demodulator transmits the demodulated low-frequency baseband signals to the baseband processor for processing. After the low-frequency baseband signals are processed by the baseband processor, they can be transmitted to the application processor.

[0230] In the prior art, the radio frequency modules that process the signals received by each antenna including the first antenna 13 and the second antenna 23 are generally all arranged on the main board, i.e., the first circuit board 12. This approach can cause the signals of the antenna 23 of the second part 21 to need to pass through the traces on the second circuit board 22 and the radio frequency signal transmission lines on the first group of FPCs before reaching the radio frequency module, resulting in a long transmission line and large insertion loss.

[0231] In the technical solution of the present application, the radio frequency modules are arranged in a distributed manner on both sides of the rotating assembly 30, which can shorten the distance between the second radio frequency module 221 and the second feed point 222. In this case, the second feed point 222 can serve as a calibration point for impedance calibration, and the insertion loss caused by the line only needs to be considered between the second radio frequency module 221 and the second antenna 23, thereby reducing the transmission line loss and optimizing the radio frequency performance of the electronic device.

[0232] It can be understood that in actual applications, the first part 11 of the electronic device can include multiple antennas, i.e., the first part 11 includes a first antenna set. Similarly, the second part 21 can also include multiple antennas, i.e., the second part 21 includes a second antenna set. In this case, the first antenna set and the radio frequency modules of the first antenna set are located on the first side of the rotating assembly 30, and the second antenna set and the radio frequency modules of the second antenna set are located on the second side of the rotating assembly 30.

[0233] In the above embodiments, impedance matching is achieved by adjusting the circuit board assembly on the electronic device. In addition, a reactance device can also be added to the electronic device to adjust the port impedance. The following will be described in detail with reference to the accompanying drawings.

[0234] Referring to Figure 18Fig. 6 is a schematic diagram of another electronic device according to an embodiment of the present application.

[0235] The electronic device includes a first part 11 and a second part 21. The first part 11 includes a first circuit board 12, and the second part 21 includes a second circuit board 22. The first part 11 includes at least a first antenna 13, and the second part 21 includes at least a second antenna 23.

[0236] The first circuit board 12 is provided with a first radio frequency module 121, a first impedance matching circuit 123, and a first feed point 122. The second circuit board 22 is provided with a second impedance matching circuit 223 and a second feed point 222.

[0237] The first impedance matching circuit 123 and the second impedance matching circuit 223 are respectively located at two ports of the radio frequency signal transmission line of the first FPC 41, and are connected to the radio frequency signal transmission line, for adjusting the ground impedance of the radio frequency signal transmission line.

[0238] It can be understood that the first impedance matching circuit 123 and the second impedance matching circuit 223 above can also be provided with only one of them.

[0239] Referring to Figure 19 Fig. 7 is a schematic diagram of an impedance matching circuit according to an embodiment of the present application.

[0240] The impedance matching circuit includes a switching circuit 2231 and multiple impedance adjustment branches.

[0241] Each impedance adjustment branch includes a capacitor or an inductor, for adjusting the reactance. Figure 19 Fig. 7 only shows an implementation in which two impedance adjustment branches are included, one of which includes an inductor, and the other of which includes a capacitor. The impedance matching circuit can also include more branches.

[0242] The switching circuit 2231 is used to select one or more impedance adjustment branches when the electronic device is in a folded state or an unfolded state, so as to reduce the absolute value of the difference between the ground impedance of the radio frequency signal transmission line and the first target impedance value. In actual applications, the impedance offset of the electronic device in the folded state or the unfolded state can be determined through preliminary testing, and then the appropriate impedance adjustment branch is selected to be turned on.

[0243] In summary, the scheme provided by the embodiments of the present application can realize impedance matching by adjusting the impedance adjustment branch connected at the port of the radio frequency signal transmission line when there is impedance mismatch. The scheme can be independently implemented, or can be implemented together with the scheme of adjusting the width of the radio frequency signal transmission line.

[0244] Based on the electronic device provided in the above embodiments, the embodiments of the present application further provide a circuit board assembly, which comprises a plurality of flexible circuit boards, for example, the first group of FPCs in the above embodiments. For the specific implementation of the circuit board assembly, refer to the description in the above embodiments, which will not be repeated here.

[0245] It should be understood that, in the present application, "at least one" means one or more, and "multiple" means 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 mean: 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 similar expressions means any combination of these items, including any combination of single item or multiple items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, and c can be single or multiple.

[0246] The above description 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. An electronic device, comprising: The electronic device comprises a rotating assembly and a multi-layer flexible circuit board; The multi-layer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly, both ends of the multi-layer flexible circuit board are located outside the rotating assembly and are fixed on both sides of the rotating assembly respectively; The multi-layer flexible circuit board comprises at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; In the region where there is an air gap between the second circuit board and the first circuit board, one or more first regions are included, and one or more second regions are included, the width of the radio frequency signal transmission line in the second region is wider than that in the first region; The distance between the second circuit board and the first circuit board at the first region is less than the distance between the second circuit board and the first circuit board at the second region.

2. The electronic device of claim 1, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line; The first ground wire on the first circuit board opposite to the at least one first region of the one or more first regions has a grid-shaped hollow region.

3. The electronic device of claim 1, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line.

4. The electronic device of claim 1, wherein, The first ground wire on the first circuit board opposite to the at least one first region of the one or more first regions has a grid-shaped hollow region.

5. The electronic device of claim 1, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line; The distance between the second ground wire on the second circuit board and the radio frequency signal transmission line at the at least one second region of the one or more second regions is less than the distance between the second ground wire on the second circuit board and the radio frequency signal transmission line at the first region of the second circuit board.

6. The electronic device of claim 1, wherein, The medium material layer adjacent to the second circuit board on the first circuit board and / or the medium material layer adjacent to the first circuit board on the second circuit board adopts one or more of the following materials: Liquid crystal polymer LCP, polytetrafluoroethylene PTFE, polyperfluoroethylene propylene FEP.

7. The electronic device of claim 1, wherein, The dielectric constant of the medium material layer adjacent to the second circuit board on the first circuit board and / or the medium material layer adjacent to the first circuit board on the second circuit board is less than or equal to 3.

8. The electronic device of any of claims 1-7, wherein, The multi-layer flexible circuit board comprises at least two layers of the first circuit board and one layer of the second circuit board; Both sides of the second circuit board are respectively provided with a layer of the first circuit board.

9. The electronic device of claim 8, wherein, Both the first circuit board and the second circuit board comprise a first medium material layer and a second medium material layer; The thickness of the second medium material layer of the first circuit board adjacent to the first medium material layer of the second circuit board is greater than the thickness of the second medium material layer of the second circuit board; and / or, The thickness of the first medium material layer of the first circuit board adjacent to the second medium material layer of the second circuit board is greater than the thickness of the first medium material layer of the second circuit board.

10. The electronic device of claim 9, wherein, The first ground wire adopts a grid-shaped hollow structure.

11. The electronic device of claim 1, wherein, The multi-layer flexible circuit board comprises a plurality of fixed regions, including a first fixed region, a second fixed region, and a third fixed region, a plurality of bending regions, and a plurality of transition regions; In the first fixed region, the multi-layer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly; The second fixed region is used for fixing the multi-layer flexible circuit board on the first side of the rotating assembly; The third fixed region is used for fixing the multi-layer flexible circuit board on the second side of the rotating assembly; When the electronic device is in a folded state, the multi-layer flexible circuit board in the plurality of bending regions is in a bent state; The transition region is a region between two adjacent bending regions, or a region between an adjacent fixed region and a bending region.

12. The electronic device of claim 11, wherein, Each of the bending regions is the first region; The first fixed region, the second fixed region, and the third fixed region are the first region; The transition region between the second fixed region and an adjacent bending region, and the transition region between the third fixed region and an adjacent bending region are the second region.

13. The electronic device of claim 11, wherein, When the electronic device is in an unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than a first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value; The transition region between two adjacent bending regions, and the transition region between the first fixed region and the bending region are a third region; The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is a first impedance value and a second impedance value, respectively; When the average of the first impedance value and the second impedance value is less than the first target impedance value, the third region is the first region, otherwise the third region is the second region.

14. The electronic device of claim 11, wherein, When the electronic device is in an unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than a first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value; The transition region between two adjacent bending regions, and the transition region between the first fixed region and the bending region are a third region; The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is a first impedance value and a second impedance value, respectively; The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is a first impedance value and a second impedance value, respectively, in order from small to large; When the difference between the second impedance value and the first target impedance value is greater than the difference between the first target impedance value and the first impedance value, and the radio frequency signal transmission line is distributed with a second ground wire on both sides, the first ground wire on the first circuit board corresponding to the third region has a grid-shaped hollow area, and / or the distance between the second ground wire at the third region and the radio frequency signal transmission line is less than the distance between the second ground wire at a non-third region on the second circuit board and the radio frequency signal transmission line.

15. The electronic device of claim 1, wherein, The electronic device includes a first antenna set and a second antenna set; The first antenna set and the radio frequency module of the first antenna set are located on the first side of the rotating assembly; The second antenna set and the radio frequency module of the second antenna set are located on the second side of the rotating assembly.

16. The electronic device of claim 1, wherein, The first side of the rotating assembly and / or the second side of the rotating assembly includes an impedance matching circuit; The impedance matching circuit is connected to the radio frequency signal transmission line; The impedance matching circuit includes a switch circuit and multiple impedance adjustment branches; The switch circuit is configured to select one or more impedance adjustment branches to reduce the absolute value of the difference between the ground impedance value of the radio frequency signal transmission line and a first target impedance value when the electronic device is in a folded state or an unfolded state.

17. The electronic device of claim 1, wherein, The electronic device further includes a screen support door plate arranged between the screen back plate and the metal middle frame of the electronic device; The screen support door plate is fixed to the screen back plate; The screen support door plate is configured to limit the multi-layer flexible circuit board to separate the multi-layer flexible circuit board and the screen back plate; The second circuit board is located on the side close to the screen back plate in the multi-layer flexible circuit board.

18. An electronic device, comprising: The electronic device includes a rotating assembly and a multi-layer flexible circuit board; The multi-layer flexible circuit board passes through the rotating assembly and is fixed opposite to the rotating assembly, and both ends of the multi-layer flexible circuit board are located outside the rotating assembly and are fixed on both sides of the rotating assembly, respectively; The multi-layer flexible circuit board includes at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; The first side of the rotating assembly and / or the second side of the rotating assembly includes an impedance matching circuit; The impedance matching circuit is connected to the radio frequency signal transmission line; The impedance matching circuit includes a switch circuit and multiple impedance adjustment branches; The switch circuit is configured to select one or more impedance adjustment branches to reduce the absolute value of the difference between the ground impedance value of the radio frequency signal transmission line and a second target impedance value when the electronic device is in a folded state or an unfolded state.

19. A circuit board assembly, characterized by The circuit board assembly includes a multi-layer flexible circuit board; The multi-layer flexible circuit board includes at least a first circuit board for laying a first ground wire and a second circuit board for laying a radio frequency signal transmission line; In the region where the second circuit board and the first circuit board have air gap, one or more first regions are included, and one or more second regions are included, the width of the radio frequency signal transmission line in the second region is wider than that in the first region; The distance between the second circuit board and the first circuit board at the first region is less than the distance between the second circuit board and the first circuit board at the second region.

20. The circuit board assembly of claim 19, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line; The first ground wire on the first circuit board opposite to the at least one first region has a grid-shaped hollow region.

21. The circuit board assembly of claim 19, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line.

22. The circuit board assembly of claim 19, wherein, The first ground wire on the first circuit board opposite to the at least one first region has a grid-shaped hollow region.

23. The circuit board assembly of claim 19, wherein, The second circuit board further comprises a second ground wire; The second ground wire is distributed on both sides of the radio frequency signal transmission line; The distance between the second ground wire on the second circuit board and the radio frequency signal transmission line at the at least one second region is less than the distance between the second ground wire on the second circuit board and the radio frequency signal transmission line at the first region.

24. The circuit board assembly of any of claims 19-23, wherein, The multi-layer flexible circuit board comprises at least two layers of the first circuit board and one layer of the second circuit board; The second circuit board is provided with a layer of the first circuit board on each side; The first circuit board and the second circuit board each comprise a first dielectric material layer and a second dielectric material layer; The thickness of the second dielectric material layer of the first circuit board adjacent to the first dielectric material layer of the second circuit board is greater than the thickness of the second dielectric material layer of the second circuit board; and / or The thickness of the first dielectric material layer of the first circuit board adjacent to the second dielectric material layer of the second circuit board is greater than the thickness of the first dielectric material layer of the second circuit board.

25. The circuit board assembly of claim 24, wherein, The first ground wire adopts a grid-shaped hollow structure.

26. The circuit board assembly of claim 19, wherein, The multi-layer flexible circuit board comprises a first fixed region, a second fixed region, a third fixed region, a plurality of bending regions, and a plurality of transition regions; The first fixed region passes through the rotating assembly and is fixed opposite to the rotating assembly; The second fixed region is used for fixing the multi-layer flexible circuit board on the first side of the rotating assembly; The third fixed region is used for fixing the multi-layer flexible circuit board on the second side of the rotating assembly; When the electronic device is in a folded state, the multi-layer flexible circuit board of the plurality of bending regions is in a bent state; The transition region is a region between two adjacent bending regions, or a region between adjacent fixed regions and bending regions.

27. The circuit board assembly of claim 26, wherein, Each of the bending regions is the first region; The first fixed region, the second fixed region, and the third fixed region are the first region; The transition region between the second fixed region and the adjacent bending region, and the transition region between the third fixed region and the adjacent bending region are the second regions.

28. The circuit board assembly of claim 26, wherein, When the multi-layer flexible circuit board is in an unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than a first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value. The transition region between each two adjacent bending regions, and the transition region between each first fixed region and the bending region are third regions. The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and closed is a first impedance value and a second impedance value, respectively. When the average of the first impedance value and the second impedance value is less than the first target impedance value, the third region is the first region, otherwise the third region is the second region.

29. The circuit board assembly of claim 26, wherein, When the electronic device is in an unfolded state, the ground impedance of the radio frequency signal transmission line in the first region is greater than a first target impedance value, and the ground impedance of the radio frequency signal transmission line in the second region is less than the first target impedance value. The transition region between each two adjacent bending regions, and the transition region between each first fixed region and the bending region are third regions. The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is a first impedance value and a second impedance value, respectively. The ground impedance of the radio frequency signal transmission line in the third region when the electronic device is folded and unfolded is a first impedance value and a second impedance value, respectively. When the difference between the second impedance value and the first target impedance value is greater than the difference between the first target impedance value and the first impedance value, and the radio frequency signal transmission line is distributed with a second ground wire on both sides, the first ground wire on the first circuit board corresponding to the third region has a grid-shaped hollow region, and / or the distance between the second ground wire and the radio frequency signal transmission line at the third region is less than the distance between the second ground wire and the radio frequency signal transmission line at the non-third region on the second circuit board.

Images