CN211457494U

CN211457494U - Flexible circuit board

Info

Publication number: CN211457494U
Application number: CN201921352056.8U
Authority: CN
Inventors: 姜陈炀; 陈忠建; 刘帅; 彭弘瑞
Original assignee: Huawei Machine Co Ltd
Current assignee: Huawei Machine Co Ltd
Priority date: 2019-08-20
Filing date: 2019-08-20
Publication date: 2020-09-08
Anticipated expiration: 2029-08-20

Abstract

The utility model provides a flexible circuit board, which comprises a first connecting end, a second connecting end and a convergence part, wherein the convergence part is positioned between the first connecting end and the second connecting end, and the width of the convergence part is smaller than the widths of the first connecting end and the second connecting end; the first dielectric layer and the at least one group of differential signal lines extend from the first connecting end to the second connecting end; the set of differential signal lines includes a first signal line and a second signal line; wherein, at the convergence portion, the first signal line and the second signal line are respectively located at different sides of the first medium layer; and the first signal line and the second signal line are positioned on the same side of the first medium layer at the first connecting end and the second connecting end. The embodiment of the utility model provides a flexible circuit board has the preparation of being convenient for, advantage such as resistant twist performance height.

Description

Flexible circuit board

Technical Field

The utility model relates to an electronic equipment technical field especially relates to a flexible circuit board.

Background

Flexible printed circuit (fpc) is a printed circuit board made of polyimide or mylar as a base material, which is preferred for its excellent characteristics such as light weight, thin thickness, and free bending and folding. Flexible circuit boards are widely used in electronic devices to transmit electrical energy or electrical signals between electronic devices.

For example, in a surveillance camera, the camera and the encoder board are usually connected by a flexible circuit board; in practical application, because the camera angle of the camera needs to be adjusted, the flexible circuit board can be twisted in the rotation process of the camera; the conventional flexible circuit board has a large width, and thus has low torsion resistance. In order to improve the torsion resistance of the flexible circuit board, some manufacturers reduce the local width of the flexible circuit board by cutting and bundling the flexible circuit board; particularly, after the flexible circuit board is manufactured and molded, the adjacent conducting circuits are cut and separated by adopting processes such as cutting and the like, and then the local part (such as the middle part) of the flexible circuit board is bound by adopting auxiliary parts such as adhesive tapes and the like, so that the purpose of reducing the local width of the flexible circuit board is achieved, and the torsion resistance of the flexible circuit board is improved. However, the manufacturing process required by the method is complex, and additional cutting and bundling processes are required, so that the manufacturing cost is increased; in addition, the consistency of the flexible circuit board during cutting and bundling is poor, so that the quality of the flexible circuit board is not balanced, and the requirement of high quality cannot be met.

SUMMERY OF THE UTILITY MODEL

The utility model provides a flexible circuit board with low costs, be convenient for preparation, have good resistant twist performance.

In an embodiment provided by the present invention, the flexible circuit board includes a first connection end, a second connection end and a convergence portion, the convergence portion is located between the first connection end and the second connection end, and the width of the convergence portion is smaller than the width of the first connection end and the second connection end; when the flexible circuit board is stressed to generate torsion, the flexible circuit board is easier to be twisted due to the smaller width of the convergence part, and the allowable torsion deformation amount is larger. In order to realize effective transmission of electric signals or electric energy, in the embodiment provided by the utility model, the flexible circuit board comprises a first medium layer extending from the first connecting end to the second connecting end and at least one group of differential signal lines; the group of differential signal lines comprises a first signal line and a second signal line; specifically, the differential signal lines in the flexible circuit board are used for realizing transmission of electric energy or electric signals, and the first dielectric layer can be used for bearing the differential signal lines so as to arrange the positions of the first signal lines and the second signal lines; in the convergence part, the first signal line and the second signal line are respectively positioned on different sides of the first medium layer so as to reduce the width of the convergence part; and the first signal line and the second signal line are positioned at the same side of the first medium layer at the first connecting end and the second connecting end so as to meet the required connection requirement.

In some embodiments, in order to achieve precise impedance control (for example, the impedance may be effectively controlled between 80 Ω to 120 Ω to satisfy data transmission performance above 1 GHz), the flexible circuit board may further include a ground line to improve the electromagnetic interference resistance and the transmission stability of the flexible circuit board.

Specifically, the flexible circuit board may further include ground lines extending from the first connection end to the second connection end, and the number of the ground lines may be the same as or equal to the sum of the number of the first signal lines (or the number of the second signal lines).

When the number of the ground lines is the same as the number of the first signal lines (or the second signal lines); in some embodiments, the ground line and the first signal line may be on the same side of the first dielectric layer at the convergence. In other embodiments, the ground line may also be located on the same side of the first dielectric layer as the second signal line at the convergence. In other embodiments, the ground line, the first signal line and the second signal line may be stacked at the convergence portion; specifically, the first dielectric layer may include a routing channel, and the ground line may be disposed in the routing channel; the grounding wire penetrates through the first dielectric layer, and the first signal wire and the second signal wire are respectively positioned on different sides of the first dielectric layer.

In addition, in some embodiments, the ground line may also be located on a different side of the first dielectric layer than the first signal line (and the second signal line) at the first connection end and the second connection end. In other embodiments, the ground line, the first signal line, and the second signal line may be located on the same side of the first dielectric layer at the first connection end and the second connection end.

When the number of ground lines is equal to the sum of the first signal line and the second signal line; in some embodiments, a portion of the ground line may be on the same side of the first dielectric layer as the first signal line and another portion of the ground line may be on the same side of the first dielectric layer as the second signal line at the convergence. In other embodiments, the ground line, the first signal line and the second signal line may be stacked at the convergence portion; specifically, the flexible circuit board may further include a second dielectric layer and a third dielectric layer extending from the first connection end to the second connection end, and the first dielectric layer is located between the second dielectric layer and the third dielectric layer; in the convergence part, the first signal line is positioned on one side of the second medium layer, and the second signal line is positioned on one side of the third medium layer; and one part of the grounding wire is positioned on the other side of the second dielectric layer, and the other part of the grounding wire is positioned on the other side of the third dielectric layer.

Certainly, in practical application, in order to prevent the first signal line, the second signal line and the ground line from being directly exposed in an external environment, the flexible circuit board may further include a protective film disposed on an outermost layer, that is, the protective film is disposed on a side of the first signal line away from the first dielectric layer and a side of the second signal line away from the first dielectric layer, so as to improve oxidation resistance, mechanical performance and the like of the flexible circuit board.

Drawings

Fig. 1 is a schematic view of a part of a monitoring camera according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a flexible circuit board according to an embodiment of the present invention;

FIG. 3 is a schematic view of the cross-sectional structure A-A of FIG. 2;

FIG. 4 is a schematic view of the cross-sectional structure B-B in FIG. 2;

fig. 5 is a schematic structural diagram of another flexible circuit board according to an embodiment of the present invention;

FIG. 6 is a schematic view of the cross-sectional structure A-A of FIG. 5;

FIG. 7 is a schematic view of the cross-sectional structure B-B in FIG. 5;

FIG. 8 is a schematic view of the cross-sectional structure C-C of FIG. 5;

fig. 9 is a schematic view of a partial molding process of a flexible circuit board according to an embodiment of the present invention;

fig. 10 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of another flexible circuit board according to an embodiment of the present invention;

FIG. 12 is a schematic view of the cross-sectional structure A-A of FIG. 11;

FIG. 13 is a schematic view of the cross-sectional structure B-B in FIG. 11;

fig. 14 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention;

fig. 15 is a schematic cross-sectional view of a converging portion of a flexible printed circuit according to another embodiment of the present invention;

fig. 16 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention;

fig. 17 is a schematic cross-sectional view illustrating a first connection end and a second connection end of another flexible circuit board according to an embodiment of the present invention;

fig. 18 is a schematic cross-sectional view illustrating a first connection end and a second connection end of another flexible circuit board according to an embodiment of the present invention;

fig. 19 is a schematic cross-sectional view illustrating a first connection end and a second connection end of another flexible circuit board according to an embodiment of the present invention;

fig. 20 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention;

fig. 21 is a schematic cross-sectional view of a converging portion of a flexible printed circuit according to another embodiment of the present invention;

fig. 22 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention;

fig. 23 is a schematic cross-sectional view of a converging portion of another flexible printed circuit board according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings.

For the convenience of understanding the flexible circuit board provided by the embodiment of the present invention, an application scenario thereof is first introduced below.

Flexible printed circuit (fpc), also known as flex board, is a printed circuit board made of a flexible, dielectric substrate, which may be polyimide or mylar. The flexible circuit board has excellent conductive performance, can meet the design requirements of miniaturization and high-density installation, is beneficial to reducing the assembly procedures and increasing the working reliability, and can meet the requirements of miniaturization and mobility of electronic products. Specifically, the flexible circuit board has certain bending, twisting and folding properties, so that when relative motion requirements exist between two electrical components (or electronic equipment) connected through the flexible circuit board, the flexible circuit board can generate bending and twisting deformation along with the relative motion requirements, and meanwhile, good connection stability can be provided.

However, with the continuous development of electronic products, the conventional flexible circuit board has not been able to provide higher deformation performance.

For example, as shown in fig. 1, a surveillance camera generally includes electronic devices such as a camera 01 and an encoder 02, and the camera 01 and the encoder 02 are usually connected by a flexible circuit board 03 to realize transmission of electric signals or electric power. When the angle of making a video recording of adjustment camera 01, camera 01 can be rotated, drives the action of flexible circuit board 03 simultaneously, makes flexible circuit board 03 produce the bending, twist reverse deformation. In order to realize adjustment of a larger shooting angle, the flexible circuit board 03 should have strong bending resistance and torsion resistance; however, under the same transmission performance condition, the width of the conventional flexible circuit board 03 is large, so that the requirement of large-angle torsion cannot be met.

Therefore, the embodiment of the utility model provides a flexible circuit board with better resistant twist performance is provided.

The terminology used in the following examples is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and the appended claims, the singular forms "a", "an", "the", and "the" are intended to include the plural forms as well, such as "one or more", unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of the present invention, "at least one", "one or more" means one, two or more. The term "and/or" is used to describe an association relationship that associates objects, meaning that three relationships may exist; for example, a and/or B, may represent: a alone, both A and B, and B alone, where A, B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

Reference throughout this specification to "one embodiment" or "some embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present invention. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," or the like, in various places throughout this specification are not necessarily all referring to the same embodiment, but rather "one or more but not all embodiments" unless specifically stated otherwise. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless expressly specified otherwise.

As shown in fig. 2, in an embodiment of the present invention, the flexible circuit board 10 includes a first connection end 101, a second connection end 102 and a convergence portion 103, the convergence portion 103 is located between the first connection end 101 and the second connection end 102, and a width of the convergence portion 103 is smaller than a width of the first connection end 101 and the second connection end 102; when the flexible circuit board 10 is forced to twist, the width of the converging portion 103 is smaller, so that the flexible circuit board is easier to twist, and the amount of allowed torsional deformation is larger. In order to realize effective transmission of electrical signals or electrical energy, as shown in fig. 3, in the embodiment provided by the present invention, the flexible circuit board includes a first dielectric layer 11 extending from the first connection end 101 to the second connection end 102 and at least one set of differential signal lines; a group of differential signal lines including a first signal line 12 and a second signal line 13; specifically, the differential signal lines in the flexible circuit board 10 are used for transmitting electrical energy or electrical signals, and the first dielectric layer 11 may be used for carrying the differential signal lines and isolating the first signal lines 12 from the second signal lines 13; referring to fig. 2 and 3, in the convergence portion 103, the first signal line 12 and the second signal line 13 are respectively located on different sides of the first medium layer 11 to reduce the width of the convergence portion 103; referring to fig. 2 and fig. 4, at the first connection end 101 and the second connection end 102, the first signal line 12 and the second signal line 13 are located at the same side of the first dielectric layer 11 to meet the required connection requirement.

Specifically, the first connection end 101 of the flexible circuit board may be connected to an electronic device (e.g., a camera), the second connection end 102 may be connected to another electronic device (e.g., an encoder), and the two electronic devices transmit electrical signals or electrical energy through at least one set of differential signal lines extending to the first connection end 101 and the second connection end 102; since the first signal line 12 and the second signal line 13 are stacked at the convergence portion 103 (i.e., at the convergence portion 103, the first signal line 12 and the second signal line 13 are respectively located at different sides of the first dielectric layer 11), the width of the convergence portion 103 can be reduced, and when the flexible circuit board 10 is twisted, the convergence portion 103 is more easily twisted while allowing a larger angle of twisting, so that it is possible to have more excellent twisting resistance.

In practical applications, in order to meet the requirement of higher transmission rate, a plurality of sets of differential signal lines may be arranged at intervals in the width direction in the flexible circuit board 10. In the convergence portion 103, the first signal line 12 and the second signal line 13 of each set of differential signal lines are respectively located on different sides of the first dielectric layer 11; at the first connection end 101 and the second connection end 102, the first signal line 12 and the second signal line 13 of each group of differential signal lines are located on the same side of the first dielectric layer 11.

In order to facilitate understanding of the technical solution provided by the embodiment of the present invention, as shown in fig. 5, a specific description is first made below that the flexible circuit board 10 includes a group of differential signal lines; it is understood that a plurality of sets of differential signal lines may be included in the flexible circuit board 10, and the plurality of sets of differential signal lines may be disposed at intervals in the width direction (left-right direction in fig. 5) of the flexible circuit board 10.

Specifically, as shown in fig. 6, in an embodiment provided by the present invention, in the convergence portion 103, the first signal line 12 and the second signal line 13 are symmetrically disposed about the first medium layer 11; as shown in fig. 7, the first signal line 12 and the second signal line 13 are located on the same side of the first dielectric layer 11 at the first connection terminal 101 and the second connection terminal 102; with this structural arrangement, the width of the converging portion 103 can be effectively reduced.

In a specific implementation, as shown in fig. 8, a via structure 110 may be disposed on the first dielectric layer 11 at the boundary between the first connection end 101 and the convergence portion 103, so as to connect the second signal line 13 at the first connection end 101 with the second signal line 13 at the convergence portion 103. Specifically, via structure 110 is a through hole 1102 having a conductive layer 1101 on the inner wall, the lower end of conductive layer 1101 is connected to the lower second signal line 13, and the upper end of conductive layer 1101 is connected to the upper second signal line 13, so that the second signal line 13 at the first connection end 101 is connected to the second signal line 13 at the convergence portion 103. Of course, the via structure 110 may be disposed on the first dielectric layer 11 at the critical point between the second connection end 102 and the convergence portion 103, so that the second signal line 13 at the second connection end 102 is connected to the second signal line 13 at the convergence portion 103.

Of course, in other embodiments, the via structure 110 may also be disposed on the first dielectric layer 11 at the critical point between the first connection end 101 and the convergence portion 103, so that the first signal line 12 at the first connection end 101 is connected to the first signal line 12 at the convergence portion 103. Of course, the via structure 110 may be disposed on the first dielectric layer 11 at the critical point between the second connection end 102 and the convergence portion 103, so that the first signal line 12 at the second connection end 102 is connected to the first signal line 12 at the convergence portion 103.

In addition, in other embodiments, the via structure 110 may also be disposed on the first dielectric layer 11 at the critical point between the first connection end 101 and the convergence portion 103, so that the first signal line 12 located at the first connection end 101 is connected to the first signal line 12 located at the convergence portion 103; a via structure 110 is disposed on the first dielectric layer 11 at the critical point between the second connection end 102 and the convergence portion 103, so that the second signal line 13 at the second connection end 102 is connected to the second signal line 13 at the convergence portion 103.

In the specific manufacturing, a raw material having a double-layer copper foil may be used as a blank. Specifically, as shown in fig. 9, copper foils 111 may be laid on both sides of the first dielectric layer 11; according to actual requirements, the copper foils 111 on the two sides can be processed by adopting processes such as etching and the like to obtain the required first signal line 12 and second signal line 13; then, a via structure (not shown) is formed by punching, electroplating, etc. to connect the first signal line 12 or the second signal line 13 on both sides of the first dielectric layer 11. Of course, as shown in fig. 10, the protection films 14 may also be attached to two sides of the flexible circuit board 10 to improve the oxidation resistance, the mechanical performance, and the like of the flexible circuit board 10, and improve the working stability thereof. In specific implementation, the first dielectric layer 11 may be a film made of polyimide or polyester; of course, in order to improve the connection strength between the first dielectric layer 11 and the first and

second signal lines

12 and 13, adhesive layers 141 may be further disposed on two sides of the first dielectric layer 11. Specifically, the adhesive layer 141 may be made of polyethylene or epoxy resin; in addition, the protective film 14 may be made of polyimide or polyester, and an adhesive layer 141 may be disposed on one side of the protective film 14 to improve the connection strength between the protective film 14 and the first and

second signal lines

12 and 13.

In addition, in order to improve the anti-electromagnetic interference performance and the transmission stability of the flexible circuit board, the flexible circuit board may further include a ground wire.

Specifically, as shown in fig. 11, in an embodiment of the present invention, the flexible circuit board 10 may further include a ground wire 15 extending from the first connection end 101 to the second connection end 102, and the number of the ground wires 15 and the number of the first signal wires 12 (or the number of the second signal wires 13) may be the same. Specifically, in one embodiment, the present invention includes a first signal line 12, a second signal line 13, and a ground line 15.

In a specific implementation, as shown in fig. 12, the ground line 15 and the first signal line 12 may be located on the same side of the first dielectric layer 11 in the convergence portion 103. As shown in fig. 13, at the first connection terminal 101 and the second connection terminal 102, the ground line 15, the first signal line 12, and the second signal line 13 are located on the same side of the first dielectric layer 11, and the ground line 15 is located between the first signal line 12 and the second signal line 13.

Of course, in other embodiments, the ground line 15 and the second signal line 13 may be located on the same side of the first dielectric layer 11 in the convergence portion 103.

In addition, in some embodiments, the ground line may be stacked with the first signal line 12 and the second signal line 13 in the convergence portion 103.

For example, as shown in fig. 14, in one embodiment of the present invention, the first dielectric layer 11 has a trace channel therein, and the ground wire 15 is located in the trace channel. Of course, it is understood that the first dielectric layer 11 may also be a double-layer film structure, the ground line 15 is located between the film layers 11a and 11b, the first signal line 12 is located on the upper side of the film layer 11a, and the second signal line 13 is located on the lower side of the film layer 11 b.

The ground line 15 may be located on the same side of the first dielectric layer 11 as the first signal line 12 (and the second signal line 13) or on a different side of the first dielectric layer 11 from the first signal line 12 (and the second signal line 13) at the first connection terminal 101 and the second connection terminal 102. Specifically, as shown in fig. 13, in an embodiment of the present invention, at the first connection end 101 and the second connection end 102, the first signal line 12 and the second signal line 13 are both located on the same side of the first dielectric layer 11, when the ground line 15 and the first signal line 12 and the second signal line 13 are located on the same side of the first dielectric layer 11, the ground line may be located between the first signal line 12 and the second signal line 13, and the distances between the ground line and the first signal line 12 and the second signal line 13 may be equal, so as to provide better electromagnetic interference resistance.

In addition, in some embodiments, the number of the ground lines 15 may also be equal to the sum of the first signal lines 12 and the second signal lines 13. Specifically, when there are one first signal line 12 and one second signal line 13, the ground line 15 may have two.

For example, as shown in fig. 15, in one embodiment of the present invention, the converging portion 103 has a first signal line 12 and a ground line 15 on one side of the first medium layer 11, and a second signal line 13 and a ground line 15 on the other side of the first medium layer 11. Of course, in other embodiments, the ground line 15 may be stacked on the first signal line 12 and the second signal line 13 in the convergence portion 103.

For example, as shown in fig. 16, in another embodiment provided by the present invention, the flexible circuit board 10 further includes a second dielectric layer 16 and a third dielectric layer 17 extending from the first connection end 101 to the second connection end 102, the first dielectric layer 11 is located between the second dielectric layer 16 and the third dielectric layer 17; in the convergence portion 103, the first signal line 12 is positioned on the second medium layer 16 side, and the second signal line 13 is positioned on the third medium layer 17 side; the ground line 15a is located on the other side of the second dielectric layer 16, and the ground line 15b is located on the other side of the third dielectric layer 17.

The ground line 15 may be located on the same side of the first dielectric layer 11 as the first signal line 12 (and the second signal line 13) or on a different side of the first dielectric layer 11 from the first signal line 12 (and the second signal line 13) at the first connection terminal 101 and the second connection terminal 102. Specifically, as shown in fig. 17, in an embodiment of the present invention, at the first connection end 101 and the second connection end 102, the first signal line 12 and the second signal line 13 are both located on the same side of the first dielectric layer 11, and when the two ground wires 15 and the first signal line 12 and the second signal line 13 are located on the same side of the first dielectric layer 11, the two ground wires 15 may be located between the first signal line 12 and the second signal line 13 and maintain a certain gap. In addition, as shown in fig. 18, in another embodiment provided by the present invention, only one grounding wire 15 may be included between the first signal wire 12 and the second signal wire 13, and another grounding wire 15 may be located on one side (right side) of the second signal wire 13. Of course, in other embodiments, another ground line 15 may also be located on one side (left side) of the first signal line 12.

In practical implementation, the widths and the intervals of the first signal line 12, the second signal line 13 and the ground line 15 may be various.

For example, the width of the first signal line 12 and the second signal line 13 may be 3 mils, the width of the ground line 15 may be 6 mils or 8 mils, and when the first signal line 12, the second signal line 13 and the ground line 15 are located on the same side of the first dielectric layer 11, the distance between the first signal line 12 and the second signal line 13 may be 3 mils, and the distance between the ground line 15 and the first signal line 12 and the second signal line 13 may be 3 mils. Of course, in other embodiments, the widths and the spacings of the first signal line 12, the second signal line 13 and the ground line 15 are not limited to the above-disclosed dimensions, and the dimensions may be adjusted accordingly according to actual needs. The thicknesses of the first dielectric layer 11, the second dielectric layer 16, and the third dielectric layer 17 may be various, and for example, the thicknesses of the first dielectric layer 11, the second dielectric layer 16, and the third dielectric layer 17 may be 2 mils. Of course, in other embodiments, the thicknesses of the first dielectric layer 11, the second dielectric layer 16 and the third dielectric layer 17 may also be adaptively adjusted according to actual requirements.

In addition, in some embodiments, as shown in fig. 19, an auxiliary ground layer 151 may be added to the first connection end 101 and the second connection end 102. Specifically, at the first connection end 101 and the second connection end 102, when the ground line 15 and the first signal line 12 and the second signal line 13 are located on the same side of the first dielectric layer 11, an auxiliary ground layer 151 may be disposed on the other side of the first dielectric layer 11, so as to effectively improve the anti-electromagnetic interference performance and the transmission stability of the flexible circuit board. In practical implementation, the width and thickness of the auxiliary ground layer 151 may be adaptively adjusted according to actual situations. In other embodiments, only the auxiliary ground layer 151 may be disposed at the first connection end 101 and the second connection end 102, and the ground line 15 may be omitted. It is understood that after the first connection end 101 and the second connection end 102 are omitted to provide the ground lines 15, the ground lines 15 located at the convergence portion 103 may be electrically connected to the auxiliary ground layer 151 through a via structure (which may be similar to the via structure 110 described above) to ensure the anti-electromagnetic interference performance and the transmission stability of the flexible circuit board.

In addition, in practical applications, the flexible circuit board 10 may include two or more groups of differential signal lines instead of only one group of differential signal lines.

For example, as shown in fig. 20, in one embodiment of the present invention, two sets of differential signal lines are included in the flexible circuit board 10; specifically, the flexible circuit board 10 includes a first signal line 12a, a first signal line 12b, a second signal line 13a, and a second signal line 13 b.

When the number of the ground wires 15 is the same as the number of the first signal wires 12 or the second signal wires 13, as shown in fig. 20, in an embodiment of the present invention, the ground wires 15a and the ground wires 15b are included in the flexible circuit board 10. In the convergence portion 103, the ground line 15a may be located between the first signal line 12a and the first signal line 12b, and the ground line 15b may be located on the right side of the second signal line 13 b.

In addition, as shown in fig. 21, in another embodiment provided by the present invention, the ground wire 15 and the first signal wire 12 and the second signal wire 13 may be stacked. Specifically, the ground line 15a and the ground line 15b may be positioned between the film layer 11a and the film layer 11b of the first dielectric layer 11.

When the number of ground lines 15 is equal to the sum of the first signal line 12 and the second signal line 13, as shown in fig. 22, in an embodiment of the present invention, the flexible circuit board includes a ground line 15a, a ground line 15b, a ground line 15c, and a ground line 15 d; specifically, the ground line 15a is located between the first signal line 12a and the first signal line 12b, and the ground line 15b is located on the right side of the first signal line 12 b; the ground line 15c is located between the second signal line 13a and the second signal line 13b, and the ground line 15d is located on the right side of the second signal line 13 b.

In addition, as shown in fig. 23, in another embodiment provided by the present invention, the ground wire 15 and the first and

second signal wires

12 and 13 may be stacked in the convergence portion 103. Specifically, the

ground lines

15a and 15b may be positioned on an upper side of the second dielectric layer 16, the

ground lines

15c and 15d may be positioned on a lower side of the third dielectric layer 17, the first signal line 12a and the first signal line 12b may be positioned between the first dielectric layer 11 and the second dielectric layer 16, and the second signal line 13a and the second signal line 13b may be positioned between the first dielectric layer 11 and the third dielectric layer 17.

Of course, the above embodiments only show several cross-sectional structures of the flexible circuit board at the convergence portion 103, in practical applications, the relative positions of the first signal line 12, the second signal line 13, the ground wire 15 at the convergence portion 103, the first connection end 101, and the second connection end 102 may be arranged and the number may be multiple, which is not repeated herein.

The above embodiments are only specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention, and all should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A flexible circuit board is characterized by comprising a first connecting end, a second connecting end and a convergence part, wherein the convergence part is positioned between the first connecting end and the second connecting end, and the width of the convergence part is smaller than that of the first connecting end and the second connecting end;

the first dielectric layer and the at least one group of differential signal lines extend from the first connecting end to the second connecting end;

the set of differential signal lines includes a first signal line and a second signal line;

wherein, at the convergence portion, the first signal line and the second signal line are respectively located at different sides of the first medium layer; and the first signal line and the second signal line are positioned at the same side of the first medium layer at the first connecting end and the second connecting end.

2. The flexible circuit board according to claim 1, further comprising ground lines extending from the first connection end to the second connection end, the ground lines being the same number as the first signal lines.

3. The flexible circuit board according to claim 2, wherein the ground line and the first signal line are located on the same side of the first dielectric layer or the ground line and the second signal line are located on the same side of the first dielectric layer at the convergence portion.

4. The flexible circuit board of claim 2, wherein the first dielectric layer has a trace channel therein, and the ground line is located in the trace channel.

5. The flexible circuit board of claim 1, further comprising ground lines extending from the first connection end to the second connection end, the number of ground lines being equal to the sum of the first signal line and the second signal line.

6. The flexible circuit board according to claim 5, wherein a part of the ground line and the first signal line are located on the same side of the first dielectric layer, and another part of the ground line and the second signal line are located on the same side of the first dielectric layer in the converging portion.

7. The flexible circuit board of claim 6, further comprising a second dielectric layer and a third dielectric layer extending from the first connection end to the second connection end, the first dielectric layer being located between the second dielectric layer and the third dielectric layer;

in the convergence part, the first signal line is positioned on one side of the second medium layer, and the second signal line is positioned on one side of the third medium layer; and one part of the grounding wire is positioned on the other side of the second dielectric layer, and the other part of the grounding wire is positioned on the other side of the third dielectric layer.

8. The flexible circuit board according to any one of claims 2 to 7, wherein the ground line and the first signal line are located on the same side of the first dielectric layer at the first connection end or the second connection end.

9. The flexible circuit board according to claim 1, wherein the at least one set of differential signal lines are arranged at intervals in a width direction.

10. The flexible circuit board of claim 1, further comprising a protective film layer overlying a side of the first signal line away from the first dielectric layer and a side of the second signal line away from the first dielectric layer.