CN116367411B - Flexible circuit boards, flexible display modules and folding terminals - Google Patents

Abstract

Embodiments of the present application relate to the technical field of electronic equipment and provide a flexible circuit board, a flexible display module and a folding terminal. Wherein, the flexible circuit board includes a first flattened area, a second flattened area and a bending area connecting the first flattened area and the second flattened area. The flexible circuit board also includes a plurality of traces. Each trace includes a first sub-section located in the first flat area, a second sub-section located in the second flat area, and a first sub-section located in the bending area and electrically connected to the first sub-section. paragraph and the third subparagraph of the second subparagraph. Among them, the third sub-segment includes conductive materials with ductility greater than 10%.

Description

Flexible circuit boards, flexible display modules and folding terminals

Technical field

The present application relates to the technical field of electronic equipment, specifically, to a flexible circuit board, a flexible display module and a folding terminal.

Background technique

Existing folding terminals (such as folding mobile phones) usually include a rotating shaft assembly and a first middle frame and a second middle frame that are rotationally connected through the rotating shaft assembly. Through the movement of the rotating shaft assembly, the first middle frame and the second middle frame can be folded or unfolded relative to each other to achieve folding or unfolding of the folding terminal. Specifically, the existing folding terminal also includes a first mainboard installed on the first middle frame, a second mainboard installed on the second middle frame, and a flexible circuit board electrically connecting the first mainboard and the second mainboard. A perforation is provided on the rotating shaft component. One end of the flexible circuit board is electrically connected to the first main board, and the other end passes through the perforation on the rotating shaft component and is electrically connected to the second main board. The flexible circuit board can be bent with the movement of the rotating shaft component.

However, existing flexible circuit boards used in folding terminals are prone to breakage during the bending process with the movement of the rotating shaft assembly and have poor reliability.

Contents of the invention

A first aspect of the present application provides a flexible circuit board, which includes a first flattened area, a second flattened area, and a bending area connecting the first flattened area and the second flattened area; the flexible printed circuit board also includes a plurality of strips Traces, each trace includes:

The first subsection is located in the first flat area;

The second subsection is located within the second flat area; and

The third sub-section is located in the bending area and electrically connected to the first sub-section and the second sub-section;

Among them, the third subsection includes conductive materials with ductility greater than 10%.

The flexible circuit board according to the first aspect of the present application adopts segmented wiring corresponding to the first flat area, the second flat area and the bending area, and uses a conductive material with a ductility greater than 10% in the bending area. Since the wiring material in the bending area has better tensile properties, this can improve the bending resistance of the flexible circuit board in the bending area, thereby reducing the friction of the flexible circuit board with the rotating shaft assembly when it is used in folding terminals. There is no risk of wire breakage during bending due to movement, and the reliability is good.

In a possible implementation, the maximum ductility of the conductive material in the third sub-section is greater than the maximum ductility of the conductive material in the first sub-section and the maximum ductility of the conductive material in the second sub-section. ductility.

In a possible implementation, both the first sub-segment and the second sub-segment are made of conductive material with a resistivity less than 52 nΩ.m.

In a possible implementation, the third subsection includes a base made of a conductive material with a ductility greater than 10% and a plurality of support parts laminated in the base along the thickness direction of the flexible circuit board. The material of the support part Different material than the base. Among them, the support part plays the role of a skeleton in the third subsection, which can buffer strain when the flexible circuit board is bent.

In one possible implementation, the support part is made of inorganic insulating material, but is not limited thereto.

In a possible implementation, the third sub-section includes an insulating structure and a conductive structure wrapped in the insulating structure, the first sub-part of the conductive structure and a third sub-section directly in contact and electrically connected to the first sub-part. Two sub-parts; the first sub-part and the second sub-part are located at different thickness positions in the thickness direction of the flexible circuit board, but are both made of conductive material with a ductility greater than 10%.

In a possible implementation, the first sub-part is annular; and/or the second sub-part is annular. For example, the first sub-part and the second sub-part may both be circular rings or both may be rectangular rings, but are not limited thereto.

In a possible implementation, the third subsection includes a plurality of first subsections and a plurality of second subsections, and each first subsection is alternately arranged with a second subsection.

In a possible implementation, along the thickness direction of the flexible circuit board, the first sub-part has a trapezoidal cross-section to increase the contact area between the first sub-part and the second sub-part and reduce the contact resistance. Optionally, along the thickness direction of the flexible circuit board, the second sub-section has a trapezoidal cross-section. In other possible implementations, along the thickness direction of the flexible circuit board, the cross-sections of the first sub-part and the second sub-part may both be rectangular.

In a possible implementation, the first sub-section and the second sub-section at least partially overlap and define an overlapping area; the third sub-section also includes a via hole located in the overlapping area, and the via hole electrically connects the first sub-section and the second sub-section. Sub Department. The via hole is filled with conductive material with a resistivity less than 52nΩ.m. Conductive materials with a resistivity less than 52nΩ.m, such as CuSn alloy or CuAg alloy, can further improve the conductive performance of the traces while ensuring the bending performance of the bending area of the flexible circuit board.

In a possible implementation, the surface of the third sub-section in contact with the first sub-section defines a first recess, and the first sub-section extends into the first recess and is in direct contact with and electrically connected to the third sub-section. In this way, it is beneficial to increase the contact area between the first sub-section and the third sub-section and reduce signal conduction consumption.

In a possible implementation, a surface where the third sub-section contacts the second sub-section defines a second recess, and the second sub-section extends into the second recess and is in direct contact with and electrically connected to the third sub-section. In this way, it is beneficial to increase the contact area between the third sub-section and the second sub-section and reduce signal conduction consumption.

In a possible implementation, along the thickness direction of the flexible circuit board, the size of the first recess gradually increases from the third sub-section to the first sub-section. In this way, the reliability of the connection between the first sub-section and the third sub-section can be further improved.

In a possible implementation, along the thickness direction of the flexible circuit board, the size of the second recess gradually increases from the third sub-section to the second sub-section. In this way, the reliability of the connection between the second subsection and the third subsection can be further improved.

In a possible implementation, the flexible circuit board further includes a first pin and a second pin; the first pin is electrically connected to the first sub-section; and the second pin is electrically connected to the second sub-section. Wherein, the first pin and the second pin can be made of copper-based alloy, so as to facilitate the good electrical connection between the first pin and the first sub-section and the good electrical connection between the second pin and the second sub-section.

In a possible implementation, the flexible circuit board further includes a shielding layer; along the thickness direction of the flexible circuit board, the projection of the shielding layer at least partially covers the projection of the first subsection; and/or, along the thickness direction of the flexible circuit board direction, the projection of the shielding layer at least partially covers the projection of the second sub-section; and/or, along the thickness direction of the flexible circuit board, the projection of the shielding layer at least partially covers the projection of the third sub-section. The setting of the shielding layer helps to avoid interference between the wiring signals of the flexible circuit board and the display signals of the flexible screen.

A second aspect of this application provides a flexible display module, which includes:

Flexible screens, including display surfaces; and

The flexible circuit board of the first aspect of this application is located on the side of the flexible screen away from the display surface.

The flexible display module provided in the second aspect of this application has at least the same advantages as the flexible circuit board in the first aspect of this application, which will not be described again here.

In a possible implementation, the flexible display module further includes a reinforcing plate located between the flexible screen and the flexible circuit board to enhance the structural strength of the flexible screen.

A third aspect of the present application provides a folding terminal, which includes:

A foldable mid-frame assembly including a first side and a second side facing away from each other;

The flexible display module of the second aspect of this application is located on the first side of the middle frame assembly;

The first motherboard and the second motherboard are both located on the second side of the mid-frame assembly; and

a first flexible circuit board and a second flexible circuit board;

Wherein, the middle frame assembly includes a first middle frame, a second middle frame and a rotating shaft assembly. The first middle frame and the second middle frame are rotationally connected through the rotating shaft assembly; along the thickness direction of the folding terminal, the first middle frame is provided with a first through hole, the second middle frame is provided with a second through hole; the first flexible circuit board includes a first end and a second end, the first end is electrically connected to the first sub-section, and the second end passes through the first through hole and the second end. A main board is electrically connected; the second flexible circuit board includes a third end and a fourth end, the third end is electrically connected to the second sub-section, and the fourth end passes through the second through hole and is electrically connected to the second main board.

The folding terminal of the third aspect of the present application has at least the same advantages as the flexible circuit board of the first aspect of the present application. In addition, the wiring of the flexible circuit board in the folding terminal does not pass through the rotating shaft assembly, which avoids the small radius fatigue damage of the through-axis flexible circuit board in the related art and the wear of the through-axis flexible circuit board and the middle frame, avoiding Reliability risk of flexible circuit board through shaft. Moreover, since there is no need to make a hole in the rotating shaft assembly for the flexible circuit board to pass through, it is possible to avoid affecting the structural reliability of the rotating shaft assembly, thereby improving the reliability of the entire folding terminal. In addition, the folding terminal of the third aspect of the present application can also eliminate the movement space in the thickness direction (typical value is 3mm) reserved for the through-axis flexible circuit board in the related art, which is beneficial to reducing the thickness of the folding terminal.

In a possible implementation, the folding terminal further includes a first connector and a second connector. The first connector is disposed on the first flexible circuit board, the second connector is disposed on the first motherboard, the first end is electrically connected to the flexible circuit board through the first connector, and the second end is electrically connected to the first flexible circuit board through the second connector. Mainboard electrical connections. In other embodiments, the folding terminal may not include the first connector and the second connector, and the first flexible circuit board and the flexible circuit board, and the first flexible circuit board and the first main board are connected by welding, snapping or connecting respectively. Electrical connection is achieved by one of the methods of pop-up connection.

In a possible implementation, the folding terminal further includes a third connector and a fourth connector. The third connector is disposed on the second flexible circuit board, the fourth connector is disposed on the second motherboard, the third end is electrically connected to the flexible circuit board through the third connector, and the fourth end is electrically connected to the second flexible circuit board through the fourth connector. Mainboard electrical connections. In other embodiments, the folding terminal may not include the third connector and the fourth connector, and the connections between the second flexible circuit board and the flexible circuit board, and between the second flexible circuit board and the second main board are respectively connected by welding, buckling or Electrical connection is achieved by one of the methods of pop-up connection.

In a possible implementation, the second connector is located between the first motherboard and the first middle frame; the fourth connector is located between the second motherboard and the second middle frame. In this way, compared with the case where the second connector is located on a side of the first motherboard away from the first middle frame and the fourth connector is located on a side of the second motherboard away from the second middle frame, it is beneficial to reduce the stacking thickness of the folding terminals. In a possible implementation, the folding terminal further includes a first pressing member, the first pressing member is located between the first middle frame and the flexible display module, and the first pressing member is used to press the first end on a flexible circuit board. In this way, it is helpful to reduce the risk of separation of the flexible circuit board and the pins of the first connector during the unfolding or folding process of the folding terminal, and ensure the stability of the electrical connection between the pins of the first connector and the flexible circuit board.

In a possible implementation, the folding terminal further includes a second pressing member, the second pressing member is located between the second middle frame and the flexible display module, and the second pressing member is used to press the third end on a flexible circuit board. In this way, it is helpful to reduce the risk of separation of the flexible circuit board and the pins of the third connector during the unfolding or folding process of the folding terminal, and ensure the stability of the electrical connection between the pins of the third connector and the flexible circuit board.

In a possible implementation, the first pressing member is installed on the first middle frame or the flexible display module; the second pressing member is installed on the second middle frame or the flexible display module. For example, the first pressing member is fixed on the first middle frame through screws, bolts and other fasteners; or the first pressing member piece is bonded to the first middle frame through glue; or the first pressing member is installed on a flexible on the display module. The installation method of the second pressing member is similar to that of the first pressing member.

In a possible implementation, when the folding terminal is folded, both the first middle frame and the second middle frame are folded toward the first side. That is, the opposite sides of the folding terminal are the display surfaces of the flexible screen.

In a possible implementation, when the folding terminal is folded, both the first middle frame and the second middle frame are folded toward the second side. That is, the opposite sides of the folding terminal are respectively the first middle frame and the second middle frame. In this case, in the folded state, the flexible screen is protected by the first middle frame and the second middle frame, which helps prevent the flexible screen from being exposed and causing damage.

Description of the drawings

Figure 1 is a schematic structural diagram of a folding terminal in the related art.

(a) in FIG. 2 is a schematic diagram of the first middle frame, the second middle frame, the rotating shaft assembly, and the flexible circuit board in the folding terminal of the related art.

(b) in FIG. 2 is a cross-sectional view of a folding terminal in the related art.

Figure 3 is a cross-sectional view of the folding terminal according to the first embodiment of the present application.

(a) in FIG. 4 is a side view of the folding terminal in the unfolded state according to the first embodiment of the present application.

(b) in FIG. 4 is a side view of the folding terminal in the folded state according to the first embodiment of the present application.

Figure 5 is a side view of the foldable terminal in a folded state according to the second embodiment of the present application.

Figure 6 is a cross-sectional view of the flexible circuit board according to the first embodiment of the present application.

(a) in FIG. 7 is a top view of the shielding layer in the flexible circuit board according to the first embodiment of the present application.

(b) in Figure 7 is a schematic diagram of the arrangement of the first pin, the second pin and the traces.

(c) in Figure 7 is a schematic diagram of the first pressing member, the first flexible circuit board and the first pin.

(d) in Figure 7 is a schematic diagram of the second pressing member, the second flexible circuit board and the second pin.

(a) in FIG. 8 is a top view of the flexible circuit board according to the first embodiment of the present application.

Figure 8(b) is a side view of the third subsection of Figure 8(a).

(c) in Figure 8 is a cross-sectional view along line B-B of (a) in Figure 8 .

Figure 9 (a) is a cross-sectional view along line C-C of Figure 8 (a).

Figure 9(b) is a cross-sectional view along line D-D of Figure 8(a).

(c) in FIG. 9 is a cross-sectional view along line E-E in (a) of FIG. 8 .

(d) in FIG. 9 is a cross-sectional view along line F-F in (a) of FIG. 8 .

Figure 10(a) is a side view of the third subsection of the flexible circuit board according to the second embodiment of the present application.

(b) in FIG. 10 is a cross-sectional view of the third subsection of the flexible circuit board according to the second embodiment of the present application.

(c) in FIG. 10 is a top view of the third subsection of the flexible circuit board according to the third embodiment of the present application.

(a) in FIG. 11 is a top view of the flexible circuit board according to the fourth embodiment of the present application.

(b) in FIG. 11 is a cross-sectional view along line G-G of (a) in FIG. 11 .

Description of main component symbols:

Folding terminal 1000a, 1000b, 1000’

Flexible display module 100

Flexible circuit board 10a, 10b, 10c, 10d, 10, 10’

Base 11

Insulation layer 12

Routing 13

First subsection 131

First convex part 1311

Second subsection 132

Second convex part 1322

Third subparagraph 133a, 133b, 133c, 133d

First recess 1331

Second recess 1332

Base 1333

Support part 1334

Shield 14

Protective layer 15

First pin 161

Second pin 162

Flexible screen 20, 20’

Display surface 20a

Middle frame components 200a, 200b

First middle frame 210, 210’

First through hole 210h

Second middle frame 220, 220’

Second through hole 220h

Shaft assembly 230a, 230b, 230’

First motherboard 310, 310’

Second main board 320, 320’

The first flexible circuit board 410

Second flexible circuit board 420

First connector 510, 510’

Second connector 520, 520’

Third connector 530

Fourth connector 540

First pressing piece 610

Second pressing piece 620

Arrow AR1, AR2

First flat area A1

The second flat area A2

Bending area A3

Opening H

Via V

Perforated C

First conductive layer CL1

Second conductive layer CL2

Part One P1

Second Subpart P2

Side 1 S1

Second side S2

First end E1

Second end E2

Third terminal E3

Fourth terminal E4

First direction X

Second direction Y

Thickness direction Z

The following specific embodiments will further describe the present application in conjunction with the above-mentioned drawings.

Detailed ways

Figure 1 is a schematic structural diagram of a folding terminal in the related art. The folding terminal 1000' can be a mobile phone. As shown in Figure 1, the folding terminal 1000' includes a first middle frame 210', a second middle frame 210' and a rotating shaft assembly 230'. The first middle frame 210' and the second middle frame 220' are rotationally connected through the rotating shaft assembly 230'. The folding terminal 1000' further includes a first mainboard 310' installed on the first middle frame 210', a second mainboard 320' installed on the second middle frame 220', and a first connector located on the first mainboard 310'. 510', the second connector 520' located on the second main board 320' and the flexible circuit board 10'. The rotating shaft assembly 230' is provided with a through hole C. One end of the flexible circuit board 10' is electrically connected to the first mainboard 310' through the first connector 510', and the other end passes through the through hole C and is connected to the first mainboard 310' through the second connector 520'. The two main boards 320' are electrically connected, thus realizing the conduction of electrical signals between the first main board 310' and the second main board 320'. The folding terminal 1000' further includes a flexible screen 20' located on the side of the first middle frame 210' and the second middle frame 220' away from the first main board 310' and the second main board 320'. Through the movement of the rotating shaft assembly 230', the first middle frame 210' and the second middle frame 220' can be folded or unfolded relative to each other, and both the flexible circuit board 10' and the flexible screen 20' can move along with the first middle frame 210' and the second middle frame 220'. The middle frame 220' is bent due to the movement of the middle frame 220', so that the folding terminal 1000' can be folded or unfolded. However, the flexible circuit board 10' is prone to breakage during the bending process with the movement of the rotating shaft assembly 230', and has poor reliability.

Specifically, please refer to (a) and (b) in Figure 2. Since the flexible circuit board 10' (also called a through-axis flexible circuit board) needs to pass through the middle of the rotating shaft assembly 230', it is easy to be bent due to the bending process. The middle bending radius is too small (such as arrow AR1) or the middle frame is worn (such as arrow AR2), resulting in wire breakage. After disconnection, functional problems such as black screen and touch failure may occur. In order to ensure the reliability of the through-axis flexible circuit board, the hinge assembly 230' is required to have sufficient space in the thickness direction Z of the folding terminal 1000', which limits the folding terminal to be thinner and lighter, limiting the competitiveness of the folding terminal. In addition, a perforation C is provided on the rotating shaft assembly 230' to accommodate the flexible circuit board 10', so that the flexible circuit board 10' can pass through it. The position of the perforation C corresponding to the rotating shaft assembly 230' will also become a weak point in the structure, causing the folding terminal to suffer external impacts. Failure is more likely to occur during impact than at other locations.

In this regard, a first aspect of this application provides a flexible circuit board. The flexible circuit board includes a first flattened area, a second flattened area and a bending area connecting the first flattened area and the second flattened area. The flexible circuit board also includes a plurality of traces, each trace including a first sub-section located in the first flat area, a second sub-section located in the second flat area, and a first sub-section located in the bending area and electrically connected to the first sub-section. paragraph and the third subparagraph of the second subparagraph. Among them, the third subsection includes conductive materials with ductility greater than 10%.

The flexible circuit board according to the first aspect of the present application adopts segmented wiring corresponding to the first flat area, the second flat area and the bending area, and uses a conductive material with a ductility greater than 10% in the bending area. Since the wiring material in the bending area has better tensile properties, this can improve the bending resistance of the flexible circuit board in the bending area, thereby reducing the friction of the flexible circuit board with the rotating shaft assembly when it is used in folding terminals. There is no risk of wire breakage during bending due to movement, and the reliability is good.

A second aspect of this application provides a flexible display module. The flexible display module includes a flexible screen and the flexible circuit board provided in the first aspect of this application. The flexible screen includes a display surface, and the flexible circuit board is located on a side of the flexible screen away from the display surface.

The flexible display module provided in the second aspect of this application has at least the same advantages as the flexible circuit board in the first aspect of this application, which will not be described again here.

A third aspect of this application provides a folding terminal. The folding terminal includes a foldable middle frame assembly, the flexible display module provided in the second aspect of the present application, a first main board, a second main board, a first flexible circuit board and a second flexible circuit board. Among them, the flexible display module is located on the first side of the middle frame assembly. The first mainboard and the second mainboard are both located on the second side of the middle frame assembly, and the second side is opposite to the first side. The middle frame assembly includes a first middle frame, a second middle frame and a rotating shaft assembly. The first middle frame and the second middle frame are rotationally connected through the rotating shaft assembly. Along the thickness direction of the folding terminal, the first middle frame is provided with a first through hole, and the second middle frame is provided with a second through hole. The first flexible circuit board includes a first end and a second end, the first end is electrically connected to the first sub-section, and the second end passes through the first through hole and is electrically connected to the first main board. The second flexible circuit board includes a third end and a fourth end, the third end is electrically connected to the second sub-section, and the fourth end passes through the second through hole and is electrically connected to the second main board.

The folding terminal of the third aspect of the present application has at least the same advantages as the flexible circuit board of the first aspect of the present application. In addition, the wiring of the flexible circuit board in the folding terminal does not pass through the rotating shaft assembly, which avoids the small radius fatigue damage of the through-axis flexible circuit board in the related art and the wear of the through-axis flexible circuit board and the middle frame, avoiding Reliability risk of flexible circuit board through shaft. Moreover, since there is no need to make a hole in the rotating shaft assembly for the flexible circuit board to pass through, it is possible to avoid affecting the structural reliability of the rotating shaft assembly, thereby improving the reliability of the entire folding terminal. In addition, the folding terminal of the third aspect of the present application can also eliminate the movement space in the thickness direction (typical value is 3mm) reserved for the through-axis flexible circuit board in the related art, which is beneficial to reducing the thickness of the folding terminal.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments.

Figure 3 is a cross-sectional view of the folding terminal according to the first embodiment of the present application. The folding terminal can be a mobile phone, but is not limited to this. As shown in FIG. 3 , the folding terminal 1000a includes a flexible display module 100 , a foldable middle frame assembly 200 a , a first mainboard 310 , a second mainboard 320 , a first flexible circuit board 410 and a second flexible circuit board 420 .

The middle frame assembly 200a in the unfolded state has opposite first sides S1 and second sides S2. The flexible display module 100 is located on the first side S1 of the middle frame assembly 200a. The first motherboard 310 and the second motherboard 320 are both located on the second side S2 of the middle frame assembly 200a.

The middle frame assembly 200a includes a first middle frame 210, a second middle frame 220 and a rotating shaft assembly 230a. The first middle frame 210 and the second middle frame 220 are rotationally connected through the rotating shaft assembly 230a. Along the thickness direction of the folding terminal 1000a, the first middle frame 210 is provided with a first through hole 210h, and the second middle frame 220 is provided with a second through hole 220h.

The flexible display module 100 includes a flexible screen 20 and a flexible circuit board 10 . The flexible screen 20 includes a display surface 20a for displaying images, and the flexible circuit board 10 is located on a side of the flexible screen 20 away from the display surface 20a.

The flexible screen 20 is, for example, an organic light-emitting diode (OLED) display screen, but is not limited thereto. In other embodiments, the flexible display module 100 further includes a reinforcing plate (not shown) between the flexible screen 20 and the flexible circuit board 10 to enhance the structural strength of the flexible screen 20 . The material of the reinforcing plate is, for example, metal.

The flexible circuit board 10 includes a first flattened area A1, a second flattened area A2, and a bending area A3 connecting the first flattened area A1 and the second flattened area A2. The first flat area A1 is arranged corresponding to the first middle frame 210, the second flat area A2 is arranged corresponding to the second middle frame 220, and the bending area A3 is arranged corresponding to the rotating shaft assembly 230a.

The folding terminal 1000a also includes a first connector 510 and a second connector 520. The first connector 510 is located on the first side S1 of the middle frame assembly 200a and is disposed on the first flexible circuit board 410. The second connector 520 is disposed on the first motherboard 310 and is located between the first motherboard 310 and the first middle frame 210 . The first flexible circuit board 410 includes opposite first and second ends E1 and E2. The first end E1 of the first flexible circuit board 410 is electrically connected to the pin (such as the first pin 161 below) in the first flat area A1 of the flexible circuit board 10 through the first connector 510, and the second end E2 passes through The first through hole 210h is electrically connected to the first motherboard 310 through the second connector 520.

The folding terminal 1000a further includes a third connector 530 and a fourth connector 540. The third connector 530 is located on the first side S1 of the middle frame assembly 200a and is disposed on the second flexible circuit board 420. The fourth connector 540 is provided on the second motherboard 320 and is located between the second motherboard 320 and the second middle frame 220 . The second flexible circuit board 420 includes an opposite third end E3 and a fourth end E4. The third end E3 of the second flexible circuit board 420 is connected to the lead in the second flat area A2 of the flexible circuit board 10 through the third connector 530 . pin (such as the second pin 162 below) is electrically connected, and the fourth end E4 passes through the second through hole 220h and is electrically connected to the second motherboard 320 through the fourth connector 540 . In this way, the flexible circuit board 10 can replace the function of the existing through-axis flexible circuit board and connect the first main board 310 and the second main board 320 . Understandably, the first mainboard 310 and the second mainboard 320 can also be electrically connected to the flexible screen 20 through other connectors.

In some embodiments, the folding terminal 1000a may not be provided with the first connector 510, the second connector 520, the third connector 530 and the fourth connector 540. Between the first end E1 of the first flexible circuit board 410 and the flexible circuit board 10 , between the second end E2 of the first flexible circuit board 410 and the first main board 310 , between the third end E3 of the second flexible circuit board 420 and The flexible circuit boards 10 are electrically connected to each other, and the fourth end E4 of the second flexible circuit board 420 to the second main board 320 is electrically connected by one of methods such as welding, buckling, or snapping.

In addition, since the second connector 520 is located between the first motherboard 310 and the first middle frame 210 . The fourth connector 540 is located between the second motherboard 320 and the second middle frame 220 . Compared with the case where the second connector is located on the side of the first motherboard away from the first middle frame and the fourth connector is located on the side of the second motherboard away from the second middle frame, it is beneficial to reduce the stacking thickness of the folding terminals.

The flexible display module 100 covers the same side of the first middle frame 210, the second middle frame 220 and the rotating shaft assembly 230a. The entire flexible display module 100 can be folded or folded as the first middle frame 210 and the second middle frame 220 rotate. expanded state. As shown in (a) of FIG. 4 , when the folding terminal 1000 a is unfolded, the first middle frame 210 and the second middle frame 220 rotate away from each other to the unfolded state. At this time, the flexible display module 100 is unfolded. As shown in (b) of Figure 4, when the folding terminal 1000a is folded, the first middle frame 210 and the second middle frame 220 rotate toward each other, and both rotate toward the direction of the first side S1 to the folded state. At this time, the flexible display module 100 is folded following the first middle frame 210 and the second middle frame 220, and the opposite sides of the folding terminal 1000a are the display surfaces 20a of the flexible screen 20.

In another embodiment, as shown in FIG. 5 , the folding terminal 1000b is an inward-folding terminal. In the middle frame assembly 200b, the rotating shaft assembly 230b is an inward-folding rotating shaft. When the folding terminal 1000b is folded, the first middle frame 210 and the second middle frame 220 rotate toward each other and are folded toward the second side S2. The opposite sides of the folding terminal 1000b are the first middle frame 210 and the second middle frame 220 respectively. Middle frame 220.

As mentioned above, the existing flexible circuit boards used in folding terminals in the related art are prone to breakage during the bending process with the movement of the rotating shaft assembly, and have poor reliability. Flexible circuit boards according to different embodiments of the present application will be described in detail below with reference to the accompanying drawings. It can be understood that in the folding terminal 1000a and the folding terminal 1000b, the flexible circuit board 10 can be the flexible circuit board of any of the following embodiments.

As shown in FIG. 6 , the flexible circuit board 10 a of the first embodiment includes a base 11 , a plurality of insulating layers 12 , traces 13 , a shielding layer 14 , a protective layer 15 , first pins 161 and second pins 162 .

Specifically, the substrate 11 is a flexible material, such as polyimide, but is not limited thereto.

A plurality of insulating layers 12 are located on the substrate 11 . The insulating layer 12 is at least located between the wiring 13 and the shielding layer 14, between the shielding layer 14 and the first pin 161, and between the shielding layer 14 and the second pin 162 to serve as a gap between the two conductive film layers. The role of isolation and insulation.

The trace 13 includes a first sub-section 131 located in the first flattening area A1, a second sub-section 132 located in the second flattening area A2, and a first sub-section 131 located in the bending area A3 and electrically connected to the second sub-section Third subsection 133a of 132. Both the first sub-segment 131 and the second sub-segment 132 are made of a conductive material with a resistivity less than 52 nΩ.m (hereinafter also referred to as a conductive material with a resistivity less than 52 nΩ.m as a conductive material with high conductivity). The third subsection 133a includes a conductive material with a ductility greater than 10% (hereinafter also referred to as a conductive material with a ductility greater than 10% as a high-ductility conductive material). In this way, the portion of the trace 13 located in the first flattened area A1 and the second flattened area A2 is made of high conductivity material, and the portion of the trace 13 located in the bending area A3 is made of high ductility material, which can ensure the conductivity of the bending area A3. The bending performance requirements can also meet the conductive performance requirements.

Specifically, the conductive material with a resistivity less than 52 nΩ.m is, for example, CuSn alloy or CuAg alloy, but is not limited thereto. The conductive material with a ductility greater than 10% is, for example, CuNiSn alloy or TiAl alloy, but is not limited thereto.

In some embodiments, the maximum ductility of the conductive material in the third sub-section is greater than the maximum ductility of the conductive material in the first sub-section and the maximum ductility of the conductive material in the second sub-section, but Not limited to this.

The shielding layer 14 is located on the side of the trace 13 away from the substrate 11 . The shielding layer 14 and the first sub-section 131 , the second sub-section 132 and the third sub-section 133 a of the wiring 13 are all stacked, which helps avoid interference between the wiring 13 signal of the flexible circuit board 10 a and the display signal of the flexible screen 20 .

In some embodiments, along the thickness direction of the flexible circuit board 10a, the projection of the shielding layer 14 completely covers the traces 13.

In other embodiments, the projection of the shielding layer 14 may partially cover the traces 13 . That is, along the thickness direction of the flexible circuit board 10a, the projection of the shielding layer 14 at least partially covers the projection of the first sub-section 131; and/or, along the thickness direction of the flexible circuit board 10a, the projection of the shielding layer 14 at least partially covers the projection of the first sub-section 131. The projection of the second sub-section 132; and/or, along the thickness direction of the flexible circuit board 10a, the projection of the shielding layer 14 at least partially covers the projection of the third sub-section 133a.

As shown in (a) of FIG. 7 , the shielding layer 14 is generally in a grid shape, but is not limited thereto. The material of the shielding layer 14 is, for example, metal, but is not limited thereto.

Please refer to FIG. 6 again, the protective layer 15 covers the insulating layer 12 and exposes the first pin 161 and the second pin 162 . The material of the protective layer 15 is, for example, polyimide, but is not limited thereto. The first pin 161 is located in the first flat area A1 and is located on a side of the first sub-section 131 away from the substrate 11 . The first pin 161 overlaps the first sub-section 131 of the trace 13 . More specifically, the first pin 161 is in direct contact with the first sub-section 131 of the trace 13 and is electrically connected. The second pin 162 is located in the second flat area A2 and is located on a side of the second sub-section 132 away from the substrate 11 . The second pin 162 overlaps the second sub-section 132 of the trace 13 . More specifically, the second pin 162 directly contacts and is electrically connected to the second sub-section 132 of the trace 13 .

The first pin 161 and the second pin 162 can be made of copper-based alloy. Since the copper-based alloy has good electrical conductivity, it is advantageous to achieve a good electrical connection between the first pin 161 and the first sub-section 131 and to achieve a good electrical connection between the second pin 162 and the second sub-section 132 .

Please refer to (b) in FIG. 7 . A plurality of first pins 161 are arranged at intervals, a plurality of traces 13 are arranged at intervals, and a plurality of second pins 162 are arranged at intervals. Each first pin 161 and each second pin 162 are respectively connected to opposite ends of a trace 13 . It is understandable that the number of first pins 161 , the number of traces 13 and the number of second pins 162 are not limited to that shown in (b) of FIG. 7 .

Please refer to Figure 3, Figure 6, and (c) in Figure 7. The first end E1 of the first flexible circuit board 410 is electrically connected to the first pin 161 on the flexible circuit board 10a through the first connector 510. . The folding terminal 1000a also includes a first pressing member 610. The first pressing member 610 is used to press the first end E1 of the first flexible circuit board 410 on the flexible circuit board 10a. Specifically, the first pressing member 610 is located between the first middle frame 210 and the flexible display module 100 . For example, the first pressing member 610 is fixed on the first middle frame 210 through screws, bolts and other fasteners; or the first pressing member 610 piece is bonded to the first middle frame 210 through glue; or the first pressing member 610 is fixed on the first middle frame 210 through glue. Component 610 is installed on the flexible display module 100. The material of the first pressing member 610 is metal, plastic, etc.

In some embodiments, the first pressing member 610 is a steel sheet to enhance the strength of the first pressing member 610 . The connection between the first connector 510 and the flexible circuit board 10a is similar to a zero insertion force socket (Zero insertion force, ZIF) socket. After the pins of the two are fitted, the first pressing member 610 is engaged to reduce the During the unfolding or folding process of the folding terminal 1000a, there is a risk that the first pin 161 of the flexible circuit board 10a is separated from the pin of the first connector 510, so as to ensure the electrical connection between the pin of the first connector 510 and the first pin 161. Connection stability.

Similarly, please refer to Figure 3, Figure 6, and Figure (d) in Figure 7. The third end E3 of the second flexible circuit board 420 is connected to the second pin on the flexible circuit board 10a through the third connector 530. 162 electrical connections. The folding terminal 1000a also includes a second pressing member 620. The second pressing member 620 is used to press the third end E3 of the second flexible circuit board 420 on the flexible circuit board 10a. Specifically, the second pressing member 620 is located between the second middle frame 220 and the flexible display module 100 . For example, the second pressing member 620 is fixed on the second middle frame 220 through screws, bolts and other fasteners; or the second pressing member 620 piece is bonded to the second middle frame 220 through glue; or the second pressing member 620 is fixed on the second middle frame 220 through glue. The component 620 is installed on the flexible display module 100. The material of the second pressing member 620 is metal, plastic, etc.

In some embodiments, the second pressing member 620 is a steel sheet to enhance the strength of the second pressing member 620 . The connection between the third connector 530 and the flexible circuit board 10a is similar to that of a ZIF socket. After the pins of the two are connected, the second pressing member 620 is fastened to reduce the flexibility of the folding terminal 1000a during the unfolding or folding process. The risk of the second pin 162 of the circuit board 10a being separated from the pin of the third connector 530 ensures the stability of the electrical connection between the pin of the third connector 530 and the second pin 162.

The specific settings of the trace 13 will be described in detail below. As shown in (a) of FIG. 8 , when the flexible circuit board 10 a is in a flat state, the first sub-section 131 , the third sub-section 133 a and the second sub-section 132 are connected in sequence along the first direction X. The plurality of traces 13 are spaced apart along the second direction Y. The first direction X is perpendicular to the second direction Y, but is not limited thereto. In other embodiments, the first direction X and the second direction Y may intersect but are not perpendicular.

Both the first sub-section 131 and the second sub-section 132 are elongated. The third subsection 133a includes a plurality of first subsections P1 and a plurality of second subsections P2. Each first sub-part P1 and each second sub-part P2 are circular. Along the first direction X, each first sub-section P1 and one second sub-section P2 are alternately arranged. (a) of FIG. 8 illustrates two second sub-parts P2 and three first sub-parts P1.

As shown in (b) and (c) of FIG. 8 , along the thickness direction of the flexible circuit board 10 a , the flexible circuit board 10 a includes a stacked first conductive layer CL1 and a second conductive layer CL2 . First conductive layer CL1 A plurality of first sub-portions P1 are formed from the first conductive layer CL1, and a plurality of second sub-portions P2 are formed from the second conductive layer CL2. The first conductive layer CL1 and the second conductive layer CL2 are both conductive materials with a ductility greater than 10%, such as CuNiSn alloy or TiAl alloy. The materials of the first conductive layer CL1 and the second conductive layer CL2 may be the same, but are not limited thereto. Each first sub-portion P1 partially overlaps the immediately adjacent second sub-portion P2 and defines an overlapping area. The third sub-section 133a also includes a via V located in the overlapping area, and the via V electrically connects the first sub-section P1 and the second sub-section P2. The via V is made of a conductive material (such as CuSn alloy or CuAg alloy) with a resistivity less than 52nΩ.m.

Therefore, it can also be said that the third sub-section 133a includes an insulating structure (ie, a plurality of insulating layers 12) and a conductive structure (ie, the first conductive layer CL1 and the second conductive layer CL2) wrapped in the insulating structure. The structure includes a first sub-part P1 and a second sub-part P2 that is in direct contact with and electrically connected to the first sub-part P1. The first sub-part P1 and the second sub-part P2 are located at different thickness positions in the thickness direction of the flexible circuit board 10a (or the third sub-section 133a), but both are made of conductive material with a ductility greater than 10%.

Each of the first sub-section P1 and the second sub-section P2 in the third sub-section 133a is annular, and the first sub-section P1 and the second sub-section P2 are staggeredly connected to each other up and down. The first sub-section P1 and the second sub-section P2 The connection position adopts a slope design to increase the contact area and reduce the contact resistance.

The via V can be prepared by etching holes at the junction of each first sub-part P1 and the adjacent second sub-part P2, and then the high-conductivity alloy particles enter the holes during the electromagnetic sputtering process, and are high with the upper and lower layers. Ductile alloy contact improves the deformation resistance of the high-ductility alloy contact surface.

As shown in (c) of FIG. 8 , in the cross-section along the thickness direction of the flexible circuit board 10 a , the portion of the insulating layer 12 located between the two adjacent first sub-portions P1 has an inverted trapezoid shape. The inverted trapezoidal design of the insulating layer 12 is because metal is prone to slope angles during the dry engraving process. Therefore, in order to facilitate the process and increase the metal contact surface between the upper and lower layers, the first sub-section P1 of the first conductive layer CL1 adopts a trapezoidal shape. The design results in the insulating layer 12 being in an inverted trapezoid shape.

As shown in (a) and (b) of FIG. 9 , the surface of the third sub-section 133a in contact with the first sub-section 131 defines a first recess 1331 , and the first sub-section 131 extends into the first recess 1331 And is in direct contact with and electrically connected to the third sub-section 133a. Along the thickness direction of the flexible circuit board 10a, the size of the first recess 1331 gradually increases from the third sub-section 133a toward the first sub-section 131. Each first recess 1331 is wedge-shaped.

As shown in (c) and (d) of Figure 9 , the surface where the third sub-section 133a contacts the second sub-section 132 defines a second recess 1332, and the second sub-section 132 extends into the second recess 1332. And is in direct contact with and electrically connected to the third sub-section 133a. Along the thickness direction of the flexible circuit board 10a, the size of the second recess 1332 gradually increases from the third sub-section 133a toward the second sub-section 132. Each second recess 1332 is wedge-shaped. Among them, the contact surface between the first sub-section 131 and the third sub-section 133a and the contact surface between the second sub-section 132 and the third sub-section 133a adopt wedge-shaped trenching and metal sputtering deposition, which is conducive to increasing the contact area and reducing signal transmission consumption. .

As shown in (a) and (b) of Figure 10 , in the flexible circuit board 10b of the second embodiment, along the thickness direction of the flexible circuit board 10b, the first sub-section P1 and the third sub-section 133b The cross-section of the second sub-portion P2 may also be rectangular.

As shown in (c) of Figure 10 , in the flexible circuit board 10c of the third embodiment, the first sub-section P1 and the second sub-section P2 of the third sub-section 133c may also be rectangular rings.

As shown in (a) of FIG. 11 , the difference between the flexible circuit board 10d of the fourth embodiment and the flexible circuit board 10a of the first embodiment lies in the structural design of the third subsection. In the fourth embodiment, the third subsection 133d is strip-shaped along the first direction X, and has a plurality of openings H spaced apart along the first direction X. Each opening H is generally rectangular, but is not limited thereto.

In other embodiments, the position, shape and size of the opening H are based on the circuit routing in the flexible circuit board 10d, and the opening H is separated.

As shown in (b) of FIG. 11 , the third sub-section 133d includes a base 1333 made of a conductive material with a ductility greater than 10% and a plurality of base portions 1333 laminated in the thickness direction of the flexible circuit board 10d. Support portion 1334. The material of the supporting part 1334 is different from the material of the base part. For example, the supporting part 1334 is made of inorganic insulating material, but is not limited thereto.

During the preparation process of the flexible circuit board 10d, the third sub-section 133d of the trace 13 is formed by sputtering and etching multiple times. Specifically, a conductive film can be formed by first depositing a conductive material with a ductility greater than 10%, and then opening holes H in the conductive film at locations where the support portion 1334 needs to be provided, and then alternately forming a layer of conductive material with a ductility greater than 10% in the openings H. 10% conductive material, a layer of inorganic insulating material, until opening H is filled. In (b) of Figure 11, the exposed position of the opening H is for depositing a conductive material with a ductility greater than 10%, but is not limited to this.

The support portion 1334 functions as a skeleton in the third sub-section 133d, which can buffer strain when the flexible circuit board is bent. When the support part 1334 is made of inorganic insulating material, the mechanical strength of the inorganic insulating material is relatively high. In other embodiments, the material of the support portion 1334 can also be selected from conductive materials to improve the conductivity of the traces 13 . The third sub-section 133d is provided with a support portion 1334 of stacked sheets. During the bending process of the flexible circuit board 10d, the internal deformation of the alloy of the trace 13 is reduced through the spacing between the sheets along the thickness direction of the flexible circuit board 10d. Increase the number of bending resistance.

In summary, the flexible circuit boards of the first to fourth embodiments not only have high yield strength in the bending area, but also have a structural design that can withstand bending, which is conducive to the flexible circuit board withstanding multiple loads in the bending area. Bend times (more than 100,000 times).

It should be noted that in the embodiment of the present application, the flexible circuit board is prepared through a semiconductor manufacturing process. Among them, the flexible circuit board can be prepared directly on the reinforcement board of the flexible display module, or the flexible circuit board can be prepared separately first, and then the flexible circuit board and the reinforcement board of the flexible display module can be attached. combine.

In addition, the above description takes the flexible circuit board including two flat areas (ie, the first flat area and the second flat area) and one bending area as an example. In other embodiments, the number of flat areas and bending areas can be changed. , that is, the flexible circuit board may include more than two flat areas, and each bending area is located between two adjacent flat areas.

Further, the above description takes the folding terminal including two middle frames (i.e., the first middle frame and the second middle frame) and a rotating shaft assembly as an example. In other embodiments, the number of middle frames in the folding terminal and the number of the rotating shaft assembly The number can be changed, that is, the folding terminal includes more than two middle frames, and each adjacent middle frame can be rotated through a rotating shaft assembly. Understandably, it can be applied to the flexible circuit of a folding terminal with more than two middle frames. In the board, each flat area corresponds to a middle frame, and each bending area corresponds to a setting between two adjacent middle frames.

The above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced. None should deviate from the spirit and scope of the technical solution of this application.

Claims (17)

1. A flexible circuit board, characterized in that it includes a first flattened area, a second flattened area and a bending area connecting the first flattened area and the second flattened area; the flexible circuit board also includes a plurality of tracks lines, each of which includes: The first subsection is located in the first flat area; a second subsection located within the second flat area; and A third subsection, located in the bending area and electrically connected to the first subsection and the second subsection; The third subsection includes a base made of a conductive material with a ductility greater than 10% and a plurality of support parts laminated in the base at intervals along the thickness direction of the flexible circuit board, and the support parts are made of different materials. Based on the material of the base; along the first direction perpendicular to the thickness direction of the flexible circuit board, the third sub-section has a plurality of openings arranged at intervals, and multiple layers are stacked in each opening. The conductive material with a ductility greater than 10% and the multi-layer inorganic insulating material; along the thickness direction of the flexible circuit board, corresponding to the position of each of the openings, each layer of the conductive material with a ductility greater than 10% Arranged alternately with one layer of the inorganic insulating material, each layer of the inorganic insulating material constitutes one of the supporting parts; Or, the third subsection includes an insulating structure and a conductive structure wrapped in the insulating structure. The conductive structure includes a first subsection and a second subsection that is in direct contact with and electrically connected to the first subsection. part, the first sub-part and the second sub-part are located at different thickness positions of the insulating structure in the thickness direction of the flexible circuit board, but both are composed of conductive materials with a ductility greater than 10%, so The third subsection includes a plurality of first subsections and a plurality of second subsections, and along a first direction perpendicular to the thickness direction of the flexible circuit board, each of the first subsections is connected to One of the second sub-sections is alternately arranged; along the thickness direction of the flexible circuit board, the first sub-section and the second sub-section at least partially overlap and define an overlapping area, and the third sub-section also It includes a via hole located in the overlapping area, the via hole electrically connects the first sub-part and the second sub-part, and the via hole is filled with a conductive material with a resistivity less than 52nΩ.m. 2. The flexible circuit board of claim 1, wherein the maximum ductility of the conductive material in the third sub-section is greater than the maximum ductility of the conductive material in the first sub-section and the second Maximum ductility of the conductive material in the subsection. 3. The flexible circuit board according to claim 1, wherein the first sub-section and the second sub-section are both made of conductive material with a resistivity less than 52nΩ.m. 4. The flexible circuit board of claim 1, wherein the third sub-section includes the conductive structure, and the conductive structure includes a plurality of first sub-sections and a plurality of second sub-sections. In this case, the first sub-section is annular; and/or the second sub-section is annular. 5. The flexible circuit board of claim 1, wherein the third sub-section includes the conductive structure, and the conductive structure includes a plurality of first sub-sections and a plurality of second sub-sections. In this case, along the thickness direction of the flexible circuit board, the cross section of the first sub-section is trapezoidal. 6. The flexible circuit board according to any one of claims 1 to 5, wherein the surface of the third sub-section in contact with the first sub-section defines a first recess, and the first sub-section The segment extends into the first recess and is in direct contact with and electrically connected to the third sub-segment; and/or the surface of the third sub-segment in contact with the second sub-segment defines a second recess, so The second sub-section extends into the second recess and is in direct contact with and electrically connected to the third sub-section. 7. The flexible circuit board according to claim 6, wherein when the third sub-section defines a first recess, along the thickness direction of the flexible circuit board, the first recess is The size gradually increases from the third sub-section to the first sub-section; in the case where the third sub-section defines a second recess, along the thickness direction of the flexible circuit board, the second recess The size of the recess gradually increases from the third subsection to the second subsection. 8. The flexible circuit board according to claim 6, wherein the flexible circuit board further includes a first pin and a second pin; the first pin is electrically connected to the first sub-section; The second pin is electrically connected to the second sub-segment. 9. The flexible circuit board according to claim 6, wherein the flexible circuit board further includes a shielding layer; Along the thickness direction of the flexible circuit board, the projection of the shielding layer at least partially covers the projection of the first sub-section; and/or, Along the thickness direction of the flexible circuit board, the projection of the shielding layer at least partially covers the projection of the second sub-section; and/or, Along the thickness direction of the flexible circuit board, the projection of the shielding layer at least partially covers the projection of the third subsection. 10. A flexible display module, characterized by comprising: Flexible screens, including display surfaces; and The flexible circuit board according to any one of claims 1 to 9, located on the side of the flexible screen away from the display surface. 11. The flexible display module according to claim 10, wherein the flexible display module further includes a reinforcing plate located between the flexible screen and the flexible circuit board. 12. A folding terminal, characterized in that it includes: A foldable mid-frame assembly including a first side and a second side facing away from each other; The flexible display module according to claim 10 or 11, located on the first side of the middle frame assembly; The first motherboard and the second motherboard are both located on the second side of the middle frame assembly; and a first flexible circuit board and a second flexible circuit board; Wherein, the middle frame assembly includes a first middle frame, a second middle frame and a rotating shaft assembly. The first middle frame and the second middle frame are rotationally connected through the rotating shaft assembly; along the thickness direction of the folding terminal On the top, the first middle frame is provided with a first through hole, and the second middle frame is provided with a second through hole; the first flexible circuit board includes a first end and a second end, and the first end is connected to The first sub-section is electrically connected, and the second end passes through the first through hole and is electrically connected to the first mainboard; the second flexible circuit board includes a third end and a fourth end, and the Three ends are electrically connected to the second sub-section, and the fourth end passes through the second through hole and is electrically connected to the second motherboard. 13. The folding terminal according to claim 12, wherein the folding terminal further includes: A first connector and a second connector, the first connector is provided on the first flexible circuit board, the second connector is provided on the first motherboard, the first end passes through the The first connector is electrically connected to the flexible circuit board, and the second end is electrically connected to the first mainboard through the second connector; and/or, A third connector and a fourth connector, the third connector is provided on the second flexible circuit board, the fourth connector is provided on the second motherboard, the third end passes through the The third connector is electrically connected to the flexible circuit board, and the fourth end is electrically connected to the second mainboard through the fourth connector. 14. The folding terminal according to claim 13, characterized in that: In the case where the folding terminal further includes a second connector, the second connector is located between the first motherboard and the first middle frame; In the case where the folding terminal further includes a fourth connector, the fourth connector is located between the second motherboard and the second middle frame. 15. The folding terminal according to claim 12, wherein the folding terminal further includes: A first pressing member, located between the first middle frame and the flexible display module, the first pressing member is used to press the first end against the flexible circuit board; and/ or, A second pressing member is located between the second middle frame and the flexible display module. The second pressing member is used to press the third end against the flexible circuit board. 16. The folding terminal according to claim 15, characterized in that: In the case where the folding terminal further includes a first pressing member, the first pressing member is installed on the first middle frame or the flexible display module; In the case where the folding terminal further includes a second pressing member, the second pressing member is installed on the second middle frame or the flexible display module. 17. The folding terminal according to any one of claims 12 to 16, characterized in that, When the folding terminal is folded, both the first middle frame and the second middle frame are folded toward the first side; or, When the folding terminal is folded, both the first middle frame and the second middle frame are folded toward the second side.